Add syscall-specific variant of BPF_KPROBE named BPF_KPROBE_SYSCALL ([0]).
The new macro hides the underlying way of getting syscall input arguments.
With the new macro, the following code:
SEC("kprobe/__x64_sys_close")
int BPF_KPROBE(do_sys_close, struct pt_regs *regs)
{
int fd;
fd = PT_REGS_PARM1_CORE(regs);
/* do something with fd */
}
can be written as:
SEC("kprobe/__x64_sys_close")
int BPF_KPROBE_SYSCALL(do_sys_close, int fd)
{
/* do something with fd */
}
[0] Closes: https://github.com/libbpf/libbpf/issues/425
Signed-off-by: Hengqi Chen <hengqi.chen@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20220207143134.2977852-2-hengqi.chen@gmail.com
On s390, the first syscall argument should be accessed via orig_gpr2
(see arch/s390/include/asm/syscall.h). Currently gpr[2] is used
instead, leading to bpf_syscall_macro test failure.
orig_gpr2 cannot be added to user_pt_regs, since its layout is a part
of the ABI. Therefore provide access to it only through
PT_REGS_PARM1_CORE_SYSCALL() by using a struct pt_regs flavor.
Reported-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20220209021745.2215452-11-iii@linux.ibm.com
On arm64, the first syscall argument should be accessed via orig_x0
(see arch/arm64/include/asm/syscall.h). Currently regs[0] is used
instead, leading to bpf_syscall_macro test failure.
orig_x0 cannot be added to struct user_pt_regs, since its layout is a
part of the ABI. Therefore provide access to it only through
PT_REGS_PARM1_CORE_SYSCALL() by using a struct pt_regs flavor.
Reported-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20220209021745.2215452-10-iii@linux.ibm.com
riscv registers are accessed via struct user_regs_struct, not struct
pt_regs. The program counter member in this struct is called pc, not
epc. The frame pointer is called s0, not fp.
Fixes: 3cc31d794097 ("libbpf: Normalize PT_REGS_xxx() macro definitions")
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20220209021745.2215452-6-iii@linux.ibm.com
libbpf_set_strict_mode() checks that the passed mode doesn't contain
extra bits for LIBBPF_STRICT_* flags that don't exist yet.
It makes it difficult for applications to disable some strict flags as
something like "LIBBPF_STRICT_ALL & ~LIBBPF_STRICT_MAP_DEFINITIONS"
is rejected by this check and they have to use a rather complicated
formula to calculate it.[0]
One possibility is to change LIBBPF_STRICT_ALL to only contain the bits
of all existing LIBBPF_STRICT_* flags instead of 0xffffffff. However
it's not possible because the idea is that applications compiled against
older libbpf_legacy.h would still be opting into latest
LIBBPF_STRICT_ALL features.[1]
The other possibility is to remove that check so something like
"LIBBPF_STRICT_ALL & ~LIBBPF_STRICT_MAP_DEFINITIONS" is allowed. It's
what this commit does.
[0]: https://lore.kernel.org/bpf/20220204220435.301896-1-mauricio@kinvolk.io/
[1]: https://lore.kernel.org/bpf/CAEf4BzaTWa9fELJLh+bxnOb0P1EMQmaRbJVG0L+nXZdy0b8G3Q@mail.gmail.com/
Fixes: 93b8952d223a ("libbpf: deprecate legacy BPF map definitions")
Signed-off-by: Mauricio Vásquez <mauricio@kinvolk.io>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20220207145052.124421-2-mauricio@kinvolk.io
btf_ext__{func,line}_info_rec_size functions are used in conjunction
with already-deprecated btf_ext__reloc_{func,line}_info functions. Since
struct btf_ext is opaque to the user it was necessary to expose rec_size
getters in the past.
btf_ext__reloc_{func,line}_info were deprecated in commit 8505e8709b5ee
("libbpf: Implement generalized .BTF.ext func/line info adjustment")
as they're not compatible with support for multiple programs per
section. It was decided[0] that users of these APIs should implement their
own .btf.ext parsing to access this data, in which case the rec_size
getters are unnecessary. So deprecate them from libbpf 0.7.0 onwards.
[0] Closes: https://github.com/libbpf/libbpf/issues/277
Signed-off-by: Dave Marchevsky <davemarchevsky@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20220201014610.3522985-1-davemarchevsky@fb.com
Add coverage to the verifier tests and tests for reading bpf_sock fields to
ensure that 32-bit, 16-bit, and 8-bit loads from dst_port field are allowed
only at intended offsets and produce expected values.
While 16-bit and 8-bit access to dst_port field is straight-forward, 32-bit
wide loads need be allowed and produce a zero-padded 16-bit value for
backward compatibility.
Signed-off-by: Jakub Sitnicki <jakub@cloudflare.com>
Link: https://lore.kernel.org/r/20220130115518.213259-3-jakub@cloudflare.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
There are no relevant libbpf commits, but new checkpoint commit contains
important BPF selftests commits fixing CI failures from kernel repo
side.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Without it coverage reports can't be built
```
[2022-01-31 00:05:36,094 DEBUG] Generating file view html index file as: "/out/report/linux/file_view_index.html".
Traceback (most recent call last):
File "/opt/code_coverage/coverage_utils.py", line 829, in <module>
sys.exit(Main())
File "/opt/code_coverage/coverage_utils.py", line 823, in Main
return _CmdPostProcess(args)
File "/opt/code_coverage/coverage_utils.py", line 780, in _CmdPostProcess
processor.PrepareHtmlReport()
File "/opt/code_coverage/coverage_utils.py", line 577, in PrepareHtmlReport
self.GenerateFileViewHtmlIndexFile(per_file_coverage_summary,
File "/opt/code_coverage/coverage_utils.py", line 450, in GenerateFileViewHtmlIndexFile
self.GetCoverageHtmlReportPathForFile(file_path),
File "/opt/code_coverage/coverage_utils.py", line 422, in GetCoverageHtmlReportPathForFile
assert os.path.isfile(
AssertionError: "/tmp/tmp.UYax4l19Gh/lib/system.h" is not a file.
```
It's a follow-up to 393a058d06
Signed-off-by: Evgeny Vereshchagin <evvers@ya.ru>
TASK_COMM_LEN is now part of vmlinux.h on latest kernel. Regenerate
vmlinux.h to have it on 5.5 and 4.9 kernels.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Not sure why these APIs were added in the first place instead of
a completely generic (and not requiring constantly adding new APIs with
each new BPF program type) bpf_program__type() and
bpf_program__set_type() APIs. But as it is right now, there are 13 such
specialized is_type/set_type APIs, while latest kernel is already at 30+
BPF program types.
Instead of completing the set of APIs and keep chasing kernel's
bpf_prog_type enum, deprecate existing subset and recommend generic
bpf_program__type() and bpf_program__set_type() APIs.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20220124194254.2051434-4-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Deprecated bpf_map__resize() in favor of bpf_map__set_max_entries()
setter. In addition to having a surprising name (users often don't
realize that they need to use bpf_map__resize()), the name also implies
some magic way of resizing BPF map after it is created, which is clearly
not the case.
Another minor annoyance is that bpf_map__resize() disallows 0 value for
max_entries, which in some cases is totally acceptable (e.g., like for
BPF perf buf case to let libbpf auto-create one buffer per each
available CPU core).
[0] Closes: https://github.com/libbpf/libbpf/issues/304
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20220124194254.2051434-3-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This adds a helper for bpf programs to read the memory of other
tasks.
As an example use case at Meta, we are using a bpf task iterator program
and this new helper to print C++ async stack traces for all threads of
a given process.
Signed-off-by: Kenny Yu <kennyyu@fb.com>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20220124185403.468466-3-kennyyu@fb.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Add new macros for mem_hops field which can be used to
represent remote-node, socket and board level details.
Currently the code had macro for HOPS_0, which corresponds
to data coming from another core but same node.
Add new macros for HOPS_1 to HOPS_3 to represent
remote-node, socket and board level data.
For ex: Encodings for mem_hops fields with L2 cache:
L2 - local L2
L2 | REMOTE | HOPS_0 - remote core, same node L2
L2 | REMOTE | HOPS_1 - remote node, same socket L2
L2 | REMOTE | HOPS_2 - remote socket, same board L2
L2 | REMOTE | HOPS_3 - remote board L2
Signed-off-by: Kajol Jain <kjain@linux.ibm.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211206091749.87585-2-kjain@linux.ibm.com
This header is necessary for libbpf-sys to generate perf-related Rust
bindings. It's more convenient to have it available locally with libbpf.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
There is a new Ubuntu-based builder, and setup steps for it are
slightly different from what we had on the old RHEL-based one.
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
RHEL's podman sets /dev/kvm permissions to 0666, while Ubuntu's docker
sets them to 0660. Therefore, in order to use KVM from a container,
the user within must belong to the kvm group.
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
It should make it easier to start using CFLite or something like that
to fuzz libbpf without getting pointless CVEs :-) More importantly,
now it's possible to build the fuzzer by just cloning the repository,
installing clang and running `./scripts/build-fuzzers.h`:
```
git clone https://github.com/libbpf/libbpf
./scripts/build-fuzzers.h
unzip -d CORPUS fuzz/bpf-object-fuzzer_seed_corpus.zip
./out/bpf-object-fuzzer CORPUS
```
It should make it easier (for me at least) to report some
elfutils bugs because they are much easier to reproduce manually
now.
Introduce 4 new netlink-based XDP APIs for attaching, detaching, and
querying XDP programs:
- bpf_xdp_attach;
- bpf_xdp_detach;
- bpf_xdp_query;
- bpf_xdp_query_id.
These APIs replace bpf_set_link_xdp_fd, bpf_set_link_xdp_fd_opts,
bpf_get_link_xdp_id, and bpf_get_link_xdp_info APIs ([0]). The latter
don't follow a consistent naming pattern and some of them use
non-extensible approaches (e.g., struct xdp_link_info which can't be
modified without breaking libbpf ABI).
The approach I took with these low-level XDP APIs is similar to what we
did with low-level TC APIs. There is a nice duality of bpf_tc_attach vs
bpf_xdp_attach, and so on. I left bpf_xdp_attach() to support detaching
when -1 is specified for prog_fd for generality and convenience, but
bpf_xdp_detach() is preferred due to clearer naming and associated
semantics. Both bpf_xdp_attach() and bpf_xdp_detach() accept the same
opts struct allowing to specify expected old_prog_fd.
While doing the refactoring, I noticed that old APIs require users to
specify opts with old_fd == -1 to declare "don't care about already
attached XDP prog fd" condition. Otherwise, FD 0 is assumed, which is
essentially never an intended behavior. So I made this behavior
consistent with other kernel and libbpf APIs, in which zero FD means "no
FD". This seems to be more in line with the latest thinking in BPF land
and should cause less user confusion, hopefully.
For querying, I left two APIs, both more generic bpf_xdp_query()
allowing to query multiple IDs and attach mode, but also
a specialization of it, bpf_xdp_query_id(), which returns only requested
prog_id. Uses of prog_id returning bpf_get_link_xdp_id() were so
prevalent across selftests and samples, that it seemed a very common use
case and using bpf_xdp_query() for doing it felt very cumbersome with
a highly branches if/else chain based on flags and attach mode.
Old APIs are scheduled for deprecation in libbpf 0.8 release.
[0] Closes: https://github.com/libbpf/libbpf/issues/309
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/r/20220120061422.2710637-2-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Enact deprecation of legacy BPF map definition in SEC("maps") ([0]). For
the definitions themselves introduce LIBBPF_STRICT_MAP_DEFINITIONS flag
for libbpf strict mode. If it is set, error out on any struct
bpf_map_def-based map definition. If not set, libbpf will print out
a warning for each legacy BPF map to raise awareness that it goes away.
For any use of BPF_ANNOTATE_KV_PAIR() macro providing a legacy way to
associate BTF key/value type information with legacy BPF map definition,
warn through libbpf's pr_warn() error message (but don't fail BPF object
open).
BPF-side struct bpf_map_def is marked as deprecated. User-space struct
bpf_map_def has to be used internally in libbpf, so it is left
untouched. It should be enough for bpf_map__def() to be marked
deprecated to raise awareness that it goes away.
bpftool is an interesting case that utilizes libbpf to open BPF ELF
object to generate skeleton. As such, even though bpftool itself uses
full on strict libbpf mode (LIBBPF_STRICT_ALL), it has to relax it a bit
for BPF map definition handling to minimize unnecessary disruptions. So
opt-out of LIBBPF_STRICT_MAP_DEFINITIONS for bpftool. User's code that
will later use generated skeleton will make its own decision whether to
enforce LIBBPF_STRICT_MAP_DEFINITIONS or not.
There are few tests in selftests/bpf that are consciously using legacy
BPF map definitions to test libbpf functionality. For those, temporary
opt out of LIBBPF_STRICT_MAP_DEFINITIONS mode for the duration of those
tests.
[0] Closes: https://github.com/libbpf/libbpf/issues/272
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20220120060529.1890907-4-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
The helpers continue to use int for retval because all the hooks
are int-returning rather than long-returning. The return value of
bpf_set_retval is int for future-proofing, in case in the future
there may be errors trying to set the retval.
After the previous patch, if a program rejects a syscall by
returning 0, an -EPERM will be generated no matter if the retval
is already set to -err. This patch change it being forced only if
retval is not -err. This is because we want to support, for
example, invoking bpf_set_retval(-EINVAL) and return 0, and have
the syscall return value be -EINVAL not -EPERM.
For BPF_PROG_CGROUP_INET_EGRESS_RUN_ARRAY, the prior behavior is
that, if the return value is NET_XMIT_DROP, the packet is silently
dropped. We preserve this behavior for backward compatibility
reasons, so even if an errno is set, the errno does not return to
caller. However, setting a non-err to retval cannot propagate so
this is not allowed and we return a -EFAULT in that case.
Signed-off-by: YiFei Zhu <zhuyifei@google.com>
Reviewed-by: Stanislav Fomichev <sdf@google.com>
Link: https://lore.kernel.org/r/b4013fd5d16bed0b01977c1fafdeae12e1de61fb.1639619851.git.zhuyifei@google.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Add a hashmap to map the string offsets from a source btf to the
string offsets from a target btf to reduce overheads.
btf__add_btf() calls btf__add_str() to add strings from a source to a
target btf. It causes many string comparisons, and it is a major
hotspot when adding a big btf. btf__add_str() uses strcmp() to check
if a hash entry is the right one. The extra hashmap here compares
offsets of strings, that are much cheaper. It remembers the results
of btf__add_str() for later uses to reduce the cost.
We are parallelizing BTF encoding for pahole by creating separated btf
instances for worker threads. These per-thread btf instances will be
added to the btf instance of the main thread by calling btf__add_str()
to deduplicate and write out. With this patch and -j4, the running
time of pahole drops to about 6.0s from 6.6s.
The following lines are the summary of 'perf stat' w/o the change.
6.668126396 seconds time elapsed
13.451054000 seconds user
0.715520000 seconds sys
The following lines are the summary w/ the change.
5.986973919 seconds time elapsed
12.939903000 seconds user
0.724152000 seconds sys
V4 fixes a bug of error checking against the pointer returned by
hashmap__new().
[v3] https://lore.kernel.org/bpf/20220118232053.2113139-1-kuifeng@fb.com/
[v2] https://lore.kernel.org/bpf/20220114193713.461349-1-kuifeng@fb.com/
Signed-off-by: Kui-Feng Lee <kuifeng@fb.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20220119180214.255634-1-kuifeng@fb.com
Both description and returns section will become mandatory
for helpers and syscalls in a later commit to generate man pages.
This commit also adds in the documentation that BPF_PROG_RUN is
an alias for BPF_PROG_TEST_RUN for anyone searching for the
syscall in the generated man pages.
Signed-off-by: Usama Arif <usama.arif@bytedance.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20220119114442.1452088-1-usama.arif@bytedance.com
The btf.h header included with libbpf contains inline helper functions to
check for various BTF kinds. These helpers directly reference the
BTF_KIND_* constants defined in the kernel header, and because the header
file is included in user applications, this happens in the user application
compile units.
This presents a problem if a user application is compiled on a system with
older kernel headers because the constants are not available. To avoid
this, add #defines of the constants directly in btf.h before using them.
Since the kernel header moved to an enum for BTF_KIND_*, the #defines can
shadow the enum values without any errors, so we only need #ifndef guards
for the constants that predates the conversion to enum. We group these so
there's only one guard for groups of values that were added together.
[0] Closes: https://github.com/libbpf/libbpf/issues/436
Fixes: 223f903e9c83 ("bpf: Rename BTF_KIND_TAG to BTF_KIND_DECL_TAG")
Fixes: 5b84bd10363e ("libbpf: Add support for BTF_KIND_TAG")
Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Link: https://lore.kernel.org/bpf/20220118141327.34231-1-toke@redhat.com
When I checked the code in skeleton header file generated with my own
bpf prog, I found there may be possible NULL pointer dereference when
destroying skeleton. Then I checked the in-tree bpf progs, finding that is
a common issue. Let's take the generated samples/bpf/xdp_redirect_cpu.skel.h
for example. Below is the generated code in
xdp_redirect_cpu__create_skeleton():
xdp_redirect_cpu__create_skeleton
struct bpf_object_skeleton *s;
s = (struct bpf_object_skeleton *)calloc(1, sizeof(*s));
if (!s)
goto error;
...
error:
bpf_object__destroy_skeleton(s);
return -ENOMEM;
After goto error, the NULL 's' will be deferenced in
bpf_object__destroy_skeleton().
We can simply fix this issue by just adding a NULL check in
bpf_object__destroy_skeleton().
Fixes: d66562fba1ce ("libbpf: Add BPF object skeleton support")
Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20220108134739.32541-1-laoar.shao@gmail.com
Eric Dumazet suggested to allow users to modify max GRO packet size.
We have seen GRO being disabled by users of appliances (such as
wifi access points) because of claimed bufferbloat issues,
or some work arounds in sch_cake, to split GRO/GSO packets.
Instead of disabling GRO completely, one can chose to limit
the maximum packet size of GRO packets, depending on their
latency constraints.
This patch adds a per device gro_max_size attribute
that can be changed with ip link command.
ip link set dev eth0 gro_max_size 16000
Suggested-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Coco Li <lixiaoyan@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This adds documention for:
- bpf_map_delete_batch()
- bpf_map_lookup_batch()
- bpf_map_lookup_and_delete_batch()
- bpf_map_update_batch()
This also updates the public API for the `keys` parameter
of `bpf_map_delete_batch()`, and both the
`keys` and `values` parameters of `bpf_map_update_batch()`
to be constants.
Signed-off-by: Grant Seltzer <grantseltzer@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20220106201304.112675-1-grantseltzer@gmail.com
With perf_buffer__poll() and perf_buffer__consume() APIs available,
there is no reason to expose bpf_perf_event_read_simple() API to
users. If users need custom perf buffer, they could re-implement
the function.
Mark bpf_perf_event_read_simple() and move the logic to a new
static function so it can still be called by other functions in the
same file.
[0] Closes: https://github.com/libbpf/libbpf/issues/310
Signed-off-by: Christy Lee <christylee@fb.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20211229204156.13569-1-christylee@fb.com
Ubuntu reports incorrect kernel version through uname(), which on older
kernels leads to kprobe BPF programs failing to load due to the version
check mismatch.
Accommodate Ubuntu's quirks with LINUX_VERSION_CODE by using
Ubuntu-specific /proc/version_code to fetch major/minor/patch versions
to form LINUX_VERSION_CODE.
While at it, consolide libbpf's kernel version detection code between
libbpf.c and libbpf_probes.c.
[0] Closes: https://github.com/libbpf/libbpf/issues/421
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20211222231003.2334940-1-andrii@kernel.org
Refactor PT_REGS macros definitions in bpf_tracing.h to avoid excessive
duplication. We currently have classic PT_REGS_xxx() and CO-RE-enabled
PT_REGS_xxx_CORE(). We are about to add also _SYSCALL variants, which
would require excessive copying of all the per-architecture definitions.
Instead, separate architecture-specific field/register names from the
final macro that utilize them. That way for upcoming _SYSCALL variants
we'll be able to just define x86_64 exception and otherwise have one
common set of _SYSCALL macro definitions common for all architectures.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Tested-by: Ilya Leoshkevich <iii@linux.ibm.com>
Acked-by: Yonghong Song <yhs@fb.com>
Acked-by: Ilya Leoshkevich <iii@linux.ibm.com>
Link: https://lore.kernel.org/bpf/20211222213924.1869758-1-andrii@kernel.org
Given that the rootfs for Arch Linux uses the busybox variant of
mount(8), the `-l` doesn't exist on that binary and gives the following
error msg with version v1.34.1 of busybox when invoking
mkrootfs_arch.sh:
```
...
[ 0.781471] random: fast init done
starting pid 72, tty '': '/etc/init.d/rcS'
+ for path in /etc/rcS.d/S*
+ '[' -x /etc/rcS.d/S10-mount ']'
+ /etc/rcS.d/S10-mount
+ /bin/mount proc /proc -t proc
++ /bin/mount -l -t devtmpfs
/bin/mount: unrecognized option: l
...
```
This prevented me from generating a rootfs. This is fixed by removing
the `-l`, as plainly invoking `mount -t devtmpfs` returns the same
output with `mount -l ...` on the non-busybox variant (on Arch Linux, it
comes from the `utils-linux` package). After this change, I was able to
run `./tools/testing/selftests/bpf/vmtest.sh -i` (from the kernel src;
with modification to the script to pick up my locally-generated .zstd of
the new rootfs) and it worked.
Signed-off-by: Chris Tarazi <tarazichris@gmail.com>
Create three extensible alternatives to inconsistently named
feature-probing APIs:
- libbpf_probe_bpf_prog_type() instead of bpf_probe_prog_type();
- libbpf_probe_bpf_map_type() instead of bpf_probe_map_type();
- libbpf_probe_bpf_helper() instead of bpf_probe_helper().
Set up return values such that libbpf can report errors (e.g., if some
combination of input arguments isn't possible to validate, etc), in
addition to whether the feature is supported (return value 1) or not
supported (return value 0).
Also schedule deprecation of those three APIs. Also schedule deprecation
of bpf_probe_large_insn_limit().
Also fix all the existing detection logic for various program and map
types that never worked:
- BPF_PROG_TYPE_LIRC_MODE2;
- BPF_PROG_TYPE_TRACING;
- BPF_PROG_TYPE_LSM;
- BPF_PROG_TYPE_EXT;
- BPF_PROG_TYPE_SYSCALL;
- BPF_PROG_TYPE_STRUCT_OPS;
- BPF_MAP_TYPE_STRUCT_OPS;
- BPF_MAP_TYPE_BLOOM_FILTER.
Above prog/map types needed special setups and detection logic to work.
Subsequent patch adds selftests that will make sure that all the
detection logic keeps working for all current and future program and map
types, avoiding otherwise inevitable bit rot.
[0] Closes: https://github.com/libbpf/libbpf/issues/312
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Dave Marchevsky <davemarchevsky@fb.com>
Cc: Julia Kartseva <hex@fb.com>
Link: https://lore.kernel.org/bpf/20211217171202.3352835-2-andrii@kernel.org
Fix possible read beyond ELF "license" data section if the license
string is not properly zero-terminated. Use the fact that libbpf_strlcpy
never accesses the (N-1)st byte of the source string because it's
replaced with '\0' anyways.
If this happens, it's a violation of contract between libbpf and a user,
but not handling this more robustly upsets CIFuzz, so given the fix is
trivial, let's fix the potential issue.
Fixes: 9fc205b413b3 ("libbpf: Add sane strncpy alternative and use it internally")
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211214232054.3458774-1-andrii@kernel.org
The need to increase RLIMIT_MEMLOCK to do anything useful with BPF is
one of the first extremely frustrating gotchas that all new BPF users go
through and in some cases have to learn it a very hard way.
Luckily, starting with upstream Linux kernel version 5.11, BPF subsystem
dropped the dependency on memlock and uses memcg-based memory accounting
instead. Unfortunately, detecting memcg-based BPF memory accounting is
far from trivial (as can be evidenced by this patch), so in practice
most BPF applications still do unconditional RLIMIT_MEMLOCK increase.
As we move towards libbpf 1.0, it would be good to allow users to forget
about RLIMIT_MEMLOCK vs memcg and let libbpf do the sensible adjustment
automatically. This patch paves the way forward in this matter. Libbpf
will do feature detection of memcg-based accounting, and if detected,
will do nothing. But if the kernel is too old, just like BCC, libbpf
will automatically increase RLIMIT_MEMLOCK on behalf of user
application ([0]).
As this is technically a breaking change, during the transition period
applications have to opt into libbpf 1.0 mode by setting
LIBBPF_STRICT_AUTO_RLIMIT_MEMLOCK bit when calling
libbpf_set_strict_mode().
Libbpf allows to control the exact amount of set RLIMIT_MEMLOCK limit
with libbpf_set_memlock_rlim_max() API. Passing 0 will make libbpf do
nothing with RLIMIT_MEMLOCK. libbpf_set_memlock_rlim_max() has to be
called before the first bpf_prog_load(), bpf_btf_load(), or
bpf_object__load() call, otherwise it has no effect and will return
-EBUSY.
[0] Closes: https://github.com/libbpf/libbpf/issues/369
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20211214195904.1785155-2-andrii@kernel.org
strncpy() has a notoriously error-prone semantics which makes GCC
complain about it a lot (and quite often completely completely falsely
at that). Instead of pleasing GCC all the time (-Wno-stringop-truncation
is unfortunately only supported by GCC, so it's a bit too messy to just
enable it in Makefile), add libbpf-internal libbpf_strlcpy() helper
which follows what FreeBSD's strlcpy() does and what most people would
expect from strncpy(): copies up to N-1 first bytes from source string
into destination string and ensures zero-termination afterwards.
Replace all the relevant uses of strncpy/strncat/memcpy in libbpf with
libbpf_strlcpy().
This also fixes the issue reported by Emmanuel Deloget in xsk.c where
memcpy() could access source string beyond its end.
Fixes: 2f6324a3937f8 (libbpf: Support shared umems between queues and devices)
Reported-by: Emmanuel Deloget <emmanuel.deloget@eho.link>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20211211004043.2374068-1-andrii@kernel.org
In case of BPF_CORE_TYPE_ID_LOCAL we fill out target result explicitly.
But targ_res itself isn't initialized in such a case, and subsequent
call to bpf_core_patch_insn() might read uninitialized field (like
fail_memsz_adjust in this case). So ensure that targ_res is
zero-initialized for BPF_CORE_TYPE_ID_LOCAL case.
This was reported by Coverity static analyzer.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20211214010032.3843804-1-andrii@kernel.org
Adding following helpers for tracing programs:
Get n-th argument of the traced function:
long bpf_get_func_arg(void *ctx, u32 n, u64 *value)
Get return value of the traced function:
long bpf_get_func_ret(void *ctx, u64 *value)
Get arguments count of the traced function:
long bpf_get_func_arg_cnt(void *ctx)
The trampoline now stores number of arguments on ctx-8
address, so it's easy to verify argument index and find
return value argument's position.
Moving function ip address on the trampoline stack behind
the number of functions arguments, so it's now stored on
ctx-16 address if it's needed.
All helpers above are inlined by verifier.
Also bit unrelated small change - using newly added function
bpf_prog_has_trampoline in check_get_func_ip.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211208193245.172141-5-jolsa@kernel.org
During linking, type IDs in the resulting linked BPF object file can
change, and so ldimm64 instructions corresponding to
BPF_CORE_TYPE_ID_TARGET and BPF_CORE_TYPE_ID_LOCAL CO-RE relos can get
their imm value out of sync with actual CO-RE relocation information
that's updated by BPF linker properly during linking process.
We could teach BPF linker to adjust such instructions, but it feels
a bit too much for linker to re-implement good chunk of
bpf_core_patch_insns logic just for this. This is a redundant safety
check for TYPE_ID relocations, as the real validation is in matching
CO-RE specs, so if that works fine, it's very unlikely that there is
something wrong with the instruction itself.
So, instead, teach libbpf (and kernel) to ignore insn->imm for
BPF_CORE_TYPE_ID_TARGET and BPF_CORE_TYPE_ID_LOCAL relos.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211213010706.100231-1-andrii@kernel.org
libbpf's obj->nr_programs includes static and global functions. That number
could be higher than the actual number of bpf programs going be loaded by
gen_loader. Passing larger nr_programs to bpf_gen__init() doesn't hurt. Those
exra stack slots will stay as zero. bpf_gen__finish() needs to check that
actual number of progs that gen_loader saw is less than or equal to
obj->nr_programs.
Fixes: ba05fd36b851 ("libbpf: Perform map fd cleanup for gen_loader in case of error")
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Currently, we use hard code number to verify if we are in the
arp_interval timeslice. But some user may want to reduce/extend
the verify timeslice. With the similar team option 'missed_max'
the uers could change that number based on their own environment.
Acked-by: Jay Vosburgh <jay.vosburgh@canonical.com>
Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Fix error: "failed to pin map: Bad file descriptor, path:
/sys/fs/bpf/_rodata_str1_1."
In the old kernel, the global data map will not be created, see [0]. So
we should skip the pinning of the global data map to avoid
bpf_object__pin_maps returning error. Therefore, when the map is not
created, we mark “map->skipped" as true and then check during relocation
and during pinning.
Fixes: 16e0c35c6f7a ("libbpf: Load global data maps lazily on legacy kernels")
Signed-off-by: Shuyi Cheng <chengshuyi@linux.alibaba.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Deprecate non-extensible bpf_object__load_xattr() in v0.8 ([0]).
With log_level control through bpf_object_open_opts or
bpf_program__set_log_level(), we are finally at the point where
bpf_object__load_xattr() doesn't provide any functionality that can't be
accessed through other (better) ways. The other feature,
target_btf_path, is also controllable through bpf_object_open_opts.
[0] Closes: https://github.com/libbpf/libbpf/issues/289
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211209193840.1248570-9-andrii@kernel.org
Allow to set user-provided log buffer on a per-program basis ([0]). This
gives great deal of flexibility in terms of which programs are loaded
with logging enabled and where corresponding logs go.
Log buffer set with bpf_program__set_log_buf() overrides kernel_log_buf
and kernel_log_size settings set at bpf_object open time through
bpf_object_open_opts, if any.
Adjust bpf_object_load_prog_instance() logic to not perform own log buf
allocation and load retry if custom log buffer is provided by the user.
[0] Closes: https://github.com/libbpf/libbpf/issues/418
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211209193840.1248570-8-andrii@kernel.org
Instead of rewriting error code returned by the kernel of prog load with
libbpf-sepcific variants pass through the original error.
There is now also no need to have a backup generic -LIBBPF_ERRNO__LOAD
fallback error as bpf_prog_load() guarantees that errno will be properly
set no matter what.
Also drop a completely outdated and pretty useless BPF_PROG_TYPE_KPROBE
guess logic. It's not necessary and neither it's helpful in modern BPF
applications.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211209193840.1248570-7-andrii@kernel.org
Add missing "prog '%s': " prefixes in few places and use consistently
markers for beginning and end of program load logs. Here's an example of
log output:
libbpf: prog 'handler': BPF program load failed: Permission denied
libbpf: -- BEGIN PROG LOAD LOG ---
arg#0 reference type('UNKNOWN ') size cannot be determined: -22
; out1 = in1;
0: (18) r1 = 0xffffc9000cdcc000
2: (61) r1 = *(u32 *)(r1 +0)
...
81: (63) *(u32 *)(r4 +0) = r5
R1_w=map_value(id=0,off=16,ks=4,vs=20,imm=0) R4=map_value(id=0,off=400,ks=4,vs=16,imm=0)
invalid access to map value, value_size=16 off=400 size=4
R4 min value is outside of the allowed memory range
processed 63 insns (limit 1000000) max_states_per_insn 0 total_states 0 peak_states 0 mark_read 0
-- END PROG LOAD LOG --
libbpf: failed to load program 'handler'
libbpf: failed to load object 'test_skeleton'
The entire verifier log, including BEGIN and END markers are now always
youtput during a single print callback call. This should make it much
easier to post-process or parse it, if necessary. It's not an explicit
API guarantee, but it can be reasonably expected to stay like that.
Also __bpf_object__open is renamed to bpf_object_open() as it's always
an adventure to find the exact function that implements bpf_object's
open phase, so drop the double underscored and use internal libbpf
naming convention.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211209193840.1248570-6-andrii@kernel.org
Allow users to provide their own custom log_buf, log_size, and log_level
at bpf_object level through bpf_object_open_opts. This log_buf will be
used during BTF loading. Subsequent patch will use same log_buf during
BPF program loading, unless overriden at per-bpf_program level.
When such custom log_buf is provided, libbpf won't be attempting
retrying loading of BTF to try to provide its own log buffer to capture
kernel's error log output. User is responsible to provide big enough
buffer, otherwise they run a risk of getting -ENOSPC error from the
bpf() syscall.
See also comments in bpf_object_open_opts regarding log_level and
log_buf interactions.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211209193840.1248570-5-andrii@kernel.org
Add libbpf-internal btf_load_into_kernel() that allows to pass
preallocated log_buf and custom log_level to be passed into kernel
during BPF_BTF_LOAD call. When custom log_buf is provided,
btf_load_into_kernel() won't attempt an retry with automatically
allocated internal temporary buffer to capture BTF validation log.
It's important to note the relation between log_buf and log_level, which
slightly deviates from stricter kernel logic. From kernel's POV, if
log_buf is specified, log_level has to be > 0, and vice versa. While
kernel has good reasons to request such "sanity, this, in practice, is
a bit unconvenient and restrictive for libbpf's high-level bpf_object APIs.
So libbpf will allow to set non-NULL log_buf and log_level == 0. This is
fine and means to attempt to load BTF without logging requested, but if
it failes, retry the load with custom log_buf and log_level 1. Similar
logic will be implemented for program loading. In practice this means
that users can provide custom log buffer just in case error happens, but
not really request slower verbose logging all the time. This is also
consistent with libbpf behavior when custom log_buf is not set: libbpf
first tries to load everything with log_level=0, and only if error
happens allocates internal log buffer and retries with log_level=1.
Also, while at it, make BTF validation log more obvious and follow the log
pattern libbpf is using for dumping BPF verifier log during
BPF_PROG_LOAD. BTF loading resulting in an error will look like this:
libbpf: BTF loading error: -22
libbpf: -- BEGIN BTF LOAD LOG ---
magic: 0xeb9f
version: 1
flags: 0x0
hdr_len: 24
type_off: 0
type_len: 1040
str_off: 1040
str_len: 2063598257
btf_total_size: 1753
Total section length too long
-- END BTF LOAD LOG --
libbpf: Error loading .BTF into kernel: -22. BTF is optional, ignoring.
This makes it much easier to find relevant parts in libbpf log output.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211209193840.1248570-4-andrii@kernel.org
Similar to previous bpf_prog_load() and bpf_map_create() APIs, add
bpf_btf_load() API which is taking optional OPTS struct. Schedule
bpf_load_btf() for deprecation in v0.8 ([0]).
This makes naming consistent with BPF_BTF_LOAD command, sets up an API
for extensibility in the future, moves options parameters (log-related
fields) into optional options, and also allows to pass log_level
directly.
It also removes log buffer auto-allocation logic from low-level API
(consistent with bpf_prog_load() behavior), but preserves a special
treatment of log_level == 0 with non-NULL log_buf, which matches
low-level bpf_prog_load() and high-level libbpf APIs for BTF and program
loading behaviors.
[0] Closes: https://github.com/libbpf/libbpf/issues/419
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211209193840.1248570-3-andrii@kernel.org
To unify libbpf APIs behavior w.r.t. log_buf and log_level, fix
bpf_prog_load() to follow the same logic as bpf_btf_load() and
high-level bpf_object__load() API will follow in the subsequent patches:
- if log_level is 0 and non-NULL log_buf is provided by a user, attempt
load operation initially with no log_buf and log_level set;
- if successful, we are done, return new FD;
- on error, retry the load operation with log_level bumped to 1 and
log_buf set; this way verbose logging will be requested only when we
are sure that there is a failure, but will be fast in the
common/expected success case.
Of course, user can still specify log_level > 0 from the very beginning
to force log collection.
Suggested-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211209193840.1248570-2-andrii@kernel.org
This adds comments above functions in libbpf.h which document
their uses. These comments are of a format that doxygen and sphinx
can pick up and render. These are rendered by libbpf.readthedocs.org
These doc comments are for:
- bpf_object__open_file()
- bpf_object__open_mem()
- bpf_program__attach_uprobe()
- bpf_program__attach_uprobe_opts()
Signed-off-by: Grant Seltzer <grantseltzer@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20211206203709.332530-1-grantseltzer@gmail.com
bpf_prog_load_xattr() is high-level API that's named as a low-level
BPF_PROG_LOAD wrapper APIs, but it actually operates on struct
bpf_object. It's badly and confusingly misnamed as it will load all the
progs insige bpf_object, returning prog_fd of the very first BPF
program. It also has a bunch of ad-hoc things like log_level override,
map_ifindex auto-setting, etc. All this can be expressed more explicitly
and cleanly through existing libbpf APIs. This patch marks
bpf_prog_load_xattr() for deprecation in libbpf v0.8 ([0]).
[0] Closes: https://github.com/libbpf/libbpf/issues/308
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211201232824.3166325-10-andrii@kernel.org
Add bpf_program__set_log_level() and bpf_program__log_level() to fetch
and adjust log_level sent during BPF_PROG_LOAD command. This allows to
selectively request more or less verbose output in BPF verifier log.
Also bump libbpf version to 0.7 and make these APIs the first in v0.7.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211201232824.3166325-3-andrii@kernel.org
Without lskel the CO-RE relocations are processed by libbpf before any other
work is done. Instead, when lskel is needed, remember relocation as RELO_CORE
kind. Then when loader prog is generated for a given bpf program pass CO-RE
relos of that program to gen loader via bpf_gen__record_relo_core(). The gen
loader will remember them as-is and pass it later as-is into the kernel.
The normal libbpf flow is to process CO-RE early before call relos happen. In
case of gen_loader the core relos have to be added to other relos to be copied
together when bpf static function is appended in different places to other main
bpf progs. During the copy the append_subprog_relos() will adjust insn_idx for
normal relos and for RELO_CORE kind too. When that is done each struct
reloc_desc has good relos for specific main prog.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20211201181040.23337-10-alexei.starovoitov@gmail.com
struct bpf_core_relo is generated by llvm and processed by libbpf.
It's a de-facto uapi.
With CO-RE in the kernel the struct bpf_core_relo becomes uapi de-jure.
Add an ability to pass a set of 'struct bpf_core_relo' to prog_load command
and let the kernel perform CO-RE relocations.
Note the struct bpf_line_info and struct bpf_func_info have the same
layout when passed from LLVM to libbpf and from libbpf to the kernel
except "insn_off" fields means "byte offset" when LLVM generates it.
Then libbpf converts it to "insn index" to pass to the kernel.
The struct bpf_core_relo's "insn_off" field is always "byte offset".
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20211201181040.23337-6-alexei.starovoitov@gmail.com
enum bpf_core_relo_kind is generated by llvm and processed by libbpf.
It's a de-facto uapi.
With CO-RE in the kernel the bpf_core_relo_kind values become uapi de-jure.
Also rename them with BPF_CORE_ prefix to distinguish from conflicting names in
bpf_core_read.h. The enums bpf_field_info_kind, bpf_type_id_kind,
bpf_type_info_kind, bpf_enum_value_kind are passing different values from bpf
program into llvm.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20211201181040.23337-5-alexei.starovoitov@gmail.com
Make relo_core.c to be compiled for the kernel and for user space libbpf.
Note the patch is reducing BPF_CORE_SPEC_MAX_LEN from 64 to 32.
This is the maximum number of nested structs and arrays.
For example:
struct sample {
int a;
struct {
int b[10];
};
};
struct sample *s = ...;
int *y = &s->b[5];
This field access is encoded as "0:1:0:5" and spec len is 4.
The follow up patch might bump it back to 64.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20211201181040.23337-4-alexei.starovoitov@gmail.com
To prepare relo_core.c to be compiled in the kernel and the user space
replace btf__type_by_id with btf_type_by_id.
In libbpf btf__type_by_id and btf_type_by_id have different behavior.
bpf_core_apply_relo_insn() needs behavior of uapi btf__type_by_id
vs internal btf_type_by_id, but type_id range check is already done
in bpf_core_apply_relo(), so it's safe to replace it everywhere.
The kernel btf_type_by_id() does the check anyway. It doesn't hurt.
Suggested-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20211201181040.23337-2-alexei.starovoitov@gmail.com
Instead, jump directly to success case stores in case ret >= 0, else do
the default 0 value store and jump over the success case. This is better
in terms of readability. Readjust the code for kfunc relocation as well
to follow a similar pattern, also leads to easier to follow code now.
Suggested-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20211122235733.634914-3-memxor@gmail.com
This patch adds the kernel-side and API changes for a new helper
function, bpf_loop:
long bpf_loop(u32 nr_loops, void *callback_fn, void *callback_ctx,
u64 flags);
where long (*callback_fn)(u32 index, void *ctx);
bpf_loop invokes the "callback_fn" **nr_loops** times or until the
callback_fn returns 1. The callback_fn can only return 0 or 1, and
this is enforced by the verifier. The callback_fn index is zero-indexed.
A few things to please note:
~ The "u64 flags" parameter is currently unused but is included in
case a future use case for it arises.
~ In the kernel-side implementation of bpf_loop (kernel/bpf/bpf_iter.c),
bpf_callback_t is used as the callback function cast.
~ A program can have nested bpf_loop calls but the program must
still adhere to the verifier constraint of its stack depth (the stack depth
cannot exceed MAX_BPF_STACK))
~ Recursive callback_fns do not pass the verifier, due to the call stack
for these being too deep.
~ The next patch will include the tests and benchmark
Signed-off-by: Joanne Koong <joannekoong@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20211130030622.4131246-2-joannekoong@fb.com
git apply -3 doesn't always leave conflicted files in the working
directory. Use patch --merge instead, it seems to work better in more
complicated situations.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
The condition for the test is incorrect, we want to add a default exit
status if the file is empty. But [[ -s file ]] returns true if the file
exists and has a size greater than zero. Let's reverse the condition.
Fixes: 385b2d1738 ("ci: change VM's /exitstatus format to prepare it for several results")
Signed-off-by: Quentin Monnet <quentin@isovalent.com>
legacy_printk selftests is specially designed to be runnable on old
kernels and validate libbpf's bpf_trace_printk-related macros. Run them
in CI.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Move commands to existing sections, or add markers for new sections when
no surrounding existing section is relevant. This is to avoid having
logs outside of subsection for the “vmtest” step of the GitHub action.
Two changes come with this patch:
- Test groups report their exit status individually for the final
summary, by appending it to /exitstatus in the VM. “Test groups” are
test_maps, test_verifier, test_progs, and test_progs-no_alu32.
- For these separate reports to make sense, allow the CI action to carry
on even after one of the groups fails, by adding "&& true" to the
commands in order to neutralise the effect of the "set -e".
We recently introduced a summary for the results of the different groups
of tests for the CI, displayed after the machine is shut down. There are
currently two groups, "bpftool" and "vm_tests". We want to split the
latter into different subgroups. For that, we will make each group of
tests that runs in the VM print its exit status to the /exitstatus file.
In preparation for this, let's update the format of this /exitstatus
file. Instead of containing just an integer, it now contains a line with
a group name, a colon, and the integer result. This is easy enough to
parse on the other end.
We also drop the associative array, and iterate on /exitstatus instead
to produce the summary: this way, the order of the checks is preserved.
When compiling libbpf with gcc 4.8.5, we see:
CC staticobjs/btf_dump.o
btf_dump.c: In function ‘btf_dump_dump_type_data.isra.24’:
btf_dump.c:2296:5: error: ‘err’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
if (err < 0)
^
cc1: all warnings being treated as errors
make: *** [staticobjs/btf_dump.o] Error 1
While gcc 4.8.5 is too old to build the upstream kernel, it's possible it
could be used to build standalone libbpf which suffers from the same problem.
Silence the error by initializing 'err' to 0. The warning/error seems to be
a false positive since err is set early in the function. Regardless we
shouldn't prevent libbpf from building for this.
Fixes: 920d16af9b42 ("libbpf: BTF dumper support for typed data")
Signed-off-by: Alan Maguire <alan.maguire@oracle.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/1638180040-8037-1-git-send-email-alan.maguire@oracle.com
Add the __NR_bpf definitions to fix the following build errors for mips:
$ cd tools/bpf/bpftool
$ make
[...]
bpf.c:54:4: error: #error __NR_bpf not defined. libbpf does not support your arch.
# error __NR_bpf not defined. libbpf does not support your arch.
^~~~~
bpf.c: In function ‘sys_bpf’:
bpf.c:66:17: error: ‘__NR_bpf’ undeclared (first use in this function); did you mean ‘__NR_brk’?
return syscall(__NR_bpf, cmd, attr, size);
^~~~~~~~
__NR_brk
[...]
In file included from gen_loader.c:15:0:
skel_internal.h: In function ‘skel_sys_bpf’:
skel_internal.h:53:17: error: ‘__NR_bpf’ undeclared (first use in this function); did you mean ‘__NR_brk’?
return syscall(__NR_bpf, cmd, attr, size);
^~~~~~~~
__NR_brk
We can see the following generated definitions:
$ grep -r "#define __NR_bpf" arch/mips
arch/mips/include/generated/uapi/asm/unistd_o32.h:#define __NR_bpf (__NR_Linux + 355)
arch/mips/include/generated/uapi/asm/unistd_n64.h:#define __NR_bpf (__NR_Linux + 315)
arch/mips/include/generated/uapi/asm/unistd_n32.h:#define __NR_bpf (__NR_Linux + 319)
The __NR_Linux is defined in arch/mips/include/uapi/asm/unistd.h:
$ grep -r "#define __NR_Linux" arch/mips
arch/mips/include/uapi/asm/unistd.h:#define __NR_Linux 4000
arch/mips/include/uapi/asm/unistd.h:#define __NR_Linux 5000
arch/mips/include/uapi/asm/unistd.h:#define __NR_Linux 6000
That is to say, __NR_bpf is:
4000 + 355 = 4355 for mips o32,
6000 + 319 = 6319 for mips n32,
5000 + 315 = 5315 for mips n64.
So use the GCC pre-defined macro _ABIO32, _ABIN32 and _ABI64 [1] to define
the corresponding __NR_bpf.
This patch is similar with commit bad1926dd2f6 ("bpf, s390: fix build for
libbpf and selftest suite").
[1] https://gcc.gnu.org/git/?p=gcc.git;a=blob;f=gcc/config/mips/mips.h#l549
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/1637804167-8323-1-git-send-email-yangtiezhu@loongson.cn
`git am -3` will give up frequently even in cases when patch can be
auto-merged with:
```
Applying: libbpf: Unify low-level map creation APIs w/ new bpf_map_create()
error: sha1 information is lacking or useless (src/libbpf.c).
error: could not build fake ancestor
Patch failed at 0001 libbpf: Unify low-level map creation APIs w/ new bpf_map_create()
```
But `git apply -3` in the same situation will succeed with three-way merge just
fine:
```
error: patch failed: src/bpf_gen_internal.h:51
Falling back to three-way merge...
Applied patch to 'src/bpf_gen_internal.h' cleanly.
```
So if git am fails, try git apply and if that succeeds, automatically
`git am --continue`. If not, fallback to user actions.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
add_dst_sec() can invalidate bpf_linker's section index making
dst_symtab pointer pointing into unallocated memory. Reinitialize
dst_symtab pointer on each iteration to make sure it's always valid.
Fixes: faf6ed321cf6 ("libbpf: Add BPF static linker APIs")
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20211124002325.1737739-7-andrii@kernel.org
Sanitizer complains about qsort(), bsearch(), and memcpy() being called
with NULL pointer. This can only happen when the associated number of
elements is zero, so no harm should be done. But still prevent this from
happening to keep sanitizer runs clean from extra noise.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20211124002325.1737739-5-andrii@kernel.org
xsk.c is using own APIs that are marked for deprecation internally.
Given xsk.c and xsk.h will be gone in libbpf 1.0, there is no reason to
do public vs internal function split just to avoid deprecation warnings.
So just add a pragma to silence deprecation warnings (until the code is
removed completely).
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20211124193233.3115996-4-andrii@kernel.org
Mark the entire zoo of low-level map creation APIs for deprecation in
libbpf 0.7 ([0]) and introduce a new bpf_map_create() API that is
OPTS-based (and thus future-proof) and matches the BPF_MAP_CREATE
command name.
While at it, ensure that gen_loader sends map_extra field. Also remove
now unneeded btf_key_type_id/btf_value_type_id logic that libbpf is
doing anyways.
[0] Closes: https://github.com/libbpf/libbpf/issues/282
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20211124193233.3115996-2-andrii@kernel.org
Load global data maps lazily, if kernel is too old to support global
data. Make sure that programs are still correct by detecting if any of
the to-be-loaded programs have relocation against any of such maps.
This allows to solve the issue ([0]) with bpf_printk() and Clang
generating unnecessary and unreferenced .rodata.strX.Y sections, but it
also goes further along the CO-RE lines, allowing to have a BPF object
in which some code can work on very old kernels and relies only on BPF
maps explicitly, while other BPF programs might enjoy global variable
support. If such programs are correctly set to not load at runtime on
old kernels, bpf_object will load and function correctly now.
[0] https://lore.kernel.org/bpf/CAK-59YFPU3qO+_pXWOH+c1LSA=8WA1yabJZfREjOEXNHAqgXNg@mail.gmail.com/
Fixes: aed659170a31 ("libbpf: Support multiple .rodata.* and .data.* BPF maps")
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20211123200105.387855-1-andrii@kernel.org
According to [0], compilers sometimes might produce duplicate DWARF
definitions for exactly the same struct/union within the same
compilation unit (CU). We've had similar issues with identical arrays
and handled them with a similar workaround in 6b6e6b1d09aa ("libbpf:
Accomodate DWARF/compiler bug with duplicated identical arrays"). Do the
same for struct/union by ensuring that two structs/unions are exactly
the same, down to the integer values of field referenced type IDs.
Solving this more generically (allowing referenced types to be
equivalent, but using different type IDs, all within a single CU)
requires a huge complexity increase to handle many-to-many mappings
between canonidal and candidate type graphs. Before we invest in that,
let's see if this approach handles all the instances of this issue in
practice. Thankfully it's pretty rare, it seems.
[0] https://lore.kernel.org/bpf/YXr2NFlJTAhHdZqq@krava/
Reported-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20211117194114.347675-1-andrii@kernel.org
Libbpf provided LIBBPF_MAJOR_VERSION and LIBBPF_MINOR_VERSION macros to
check libbpf version at compilation time. This doesn't cover all the
needs, though, because version of libbpf that application is compiled
against doesn't necessarily match the version of libbpf at runtime,
especially if libbpf is used as a shared library.
Add libbpf_major_version() and libbpf_minor_version() returning major
and minor versions, respectively, as integers. Also add a convenience
libbpf_version_string() for various tooling using libbpf to print out
libbpf version in a human-readable form. Currently it will return
"v0.6", but in the future it can contains some extra information, so the
format itself is not part of a stable API and shouldn't be relied upon.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/bpf/20211118174054.2699477-1-andrii@kernel.org
This commit fixes the display of the BPF documentation in the sidebar
when rendered as HTML.
Before this patch, the sidebar would render as follows for some
sections:
| BPF Documentation
|- BPF Type Format (BTF)
|- BPF Type Format (BTF)
This was due to creating a heading in index.rst followed by
a sphinx toctree, where the file referenced carries the same
title as the section heading.
To fix this I applied a pattern that has been established in other
subfolders of Documentation:
1. Re-wrote index.rst to have a single toctree
2. Split the sections out in to their own files
Additionally maps.rst and programs.rst make use of a glob pattern to
include map_* or prog_* rst files in their toctree, meaning future map
or program type documentation will be automatically included.
Signed-off-by: Dave Tucker <dave@dtucker.co.uk>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/1a1eed800e7b9dc13b458de113a489641519b0cc.1636749493.git.dave@dtucker.co.uk
The bpftool checks work as expected when the CI runs, except that they
do not set any error status code for the script on error, which means
that the failures are lost among the logs and not reported in a clear
way to the reviewers.
This commit aims at fixing the issue. We could simply exit with a
non-zero error status when the bpftool checks, but that would prevent
the other tests from running. Instead, we propose to store the result of
the bpftool checks in a bash array. This array can later be reused to
print a summary of the different groups of tests, at the end of the CI
run, to help the reviewers understand where the failure happened without
having to manually unfold all the sections on the GitHub interface.
Currently, there are only two groups: the bpftool checks and the "VM
tests". The latter may later be split into test_maps, test_progs,
test_progs-no_alu32, etc. by teaching each of them to append their exit
status code to the "exitstatus" file.
Fixes: 88649fe655 ("ci: run script to test bpftool types/options sync")
For displaying a coloured title for the shutdown section in the logs,
instead of having the colour control codes directly written in run.sh,
we can pass the section title as an argument to "travis_fold()" and have
it format and print it for us.
This is cleaner, and slightly more in-line with what we do in the CI
files of the vmtest repository.
libbpf conforms to kernel style and uses the same -std=gnu89 standard
for compilation. So enforce it on Github projection as well.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Alexei reported a fd leak issue in gen loader (when invoked from
bpftool) [0]. When adding ksym support, map fd allocation was moved from
stack to loader map, however I missed closing these fds (relevant when
cleanup label is jumped to on error). For the success case, the
allocated fd is returned in loader ctx, hence this problem is not
noticed.
Make three changes, first MAX_USED_MAPS in MAX_FD_ARRAY_SZ instead of
MAX_USED_PROGS, the braino was not a problem until now for this case as
we didn't try to close map fds (otherwise use of it would have tried
closing 32 additional fds in ksym btf fd range). Then, do a cleanup for
all nr_maps fds in cleanup label code, so that in case of error all
temporary map fds from bpf_gen__map_create are closed.
Then, adjust the cleanup label to only generate code for the required
number of program and map fds. To trim code for remaining program
fds, lay out prog_fd array in stack in the end, so that we can
directly skip the remaining instances. Still stack size remains same,
since changing that would require changes in a lot of places
(including adjustment of stack_off macro), so nr_progs_sz variable is
only used to track required number of iterations (and jump over
cleanup size calculated from that), stack offset calculation remains
unaffected.
The difference for test_ksyms_module.o is as follows:
libbpf: //prog cleanup iterations: before = 34, after = 5
libbpf: //maps cleanup iterations: before = 64, after = 2
Also, move allocation of gen->fd_array offset to bpf_gen__init. Since
offset can now be 0, and we already continue even if add_data returns 0
in case of failure, we do not need to distinguish between 0 offset and
failure case 0, as we rely on bpf_gen__finish to check errors. We can
also skip check for gen->fd_array in add_*_fd functions, since
bpf_gen__init will take care of it.
[0]: https://lore.kernel.org/bpf/CAADnVQJ6jSitKSNKyxOrUzwY2qDRX0sPkJ=VLGHuCLVJ=qOt9g@mail.gmail.com
Fixes: 18f4fccbf314 ("libbpf: Update gen_loader to emit BTF_KIND_FUNC relocations")
Reported-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211112232022.899074-1-memxor@gmail.com
In the current code, the actual max tail call count is 33 which is greater
than MAX_TAIL_CALL_CNT (defined as 32). The actual limit is not consistent
with the meaning of MAX_TAIL_CALL_CNT and thus confusing at first glance.
We can see the historical evolution from commit 04fd61ab36ec ("bpf: allow
bpf programs to tail-call other bpf programs") and commit f9dabe016b63
("bpf: Undo off-by-one in interpreter tail call count limit"). In order
to avoid changing existing behavior, the actual limit is 33 now, this is
reasonable.
After commit 874be05f525e ("bpf, tests: Add tail call test suite"), we can
see there exists failed testcase.
On all archs when CONFIG_BPF_JIT_ALWAYS_ON is not set:
# echo 0 > /proc/sys/net/core/bpf_jit_enable
# modprobe test_bpf
# dmesg | grep -w FAIL
Tail call error path, max count reached jited:0 ret 34 != 33 FAIL
On some archs:
# echo 1 > /proc/sys/net/core/bpf_jit_enable
# modprobe test_bpf
# dmesg | grep -w FAIL
Tail call error path, max count reached jited:1 ret 34 != 33 FAIL
Although the above failed testcase has been fixed in commit 18935a72eb25
("bpf/tests: Fix error in tail call limit tests"), it would still be good
to change the value of MAX_TAIL_CALL_CNT from 32 to 33 to make the code
more readable.
The 32-bit x86 JIT was using a limit of 32, just fix the wrong comments and
limit to 33 tail calls as the constant MAX_TAIL_CALL_CNT updated. For the
mips64 JIT, use "ori" instead of "addiu" as suggested by Johan Almbladh.
For the riscv JIT, use RV_REG_TCC directly to save one register move as
suggested by Björn Töpel. For the other implementations, no function changes,
it does not change the current limit 33, the new value of MAX_TAIL_CALL_CNT
can reflect the actual max tail call count, the related tail call testcases
in test_bpf module and selftests can work well for the interpreter and the
JIT.
Here are the test results on x86_64:
# uname -m
x86_64
# echo 0 > /proc/sys/net/core/bpf_jit_enable
# modprobe test_bpf test_suite=test_tail_calls
# dmesg | tail -1
test_bpf: test_tail_calls: Summary: 8 PASSED, 0 FAILED, [0/8 JIT'ed]
# rmmod test_bpf
# echo 1 > /proc/sys/net/core/bpf_jit_enable
# modprobe test_bpf test_suite=test_tail_calls
# dmesg | tail -1
test_bpf: test_tail_calls: Summary: 8 PASSED, 0 FAILED, [8/8 JIT'ed]
# rmmod test_bpf
# ./test_progs -t tailcalls
#142 tailcalls:OK
Summary: 1/11 PASSED, 0 SKIPPED, 0 FAILED
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Tested-by: Johan Almbladh <johan.almbladh@anyfinetworks.com>
Tested-by: Ilya Leoshkevich <iii@linux.ibm.com>
Acked-by: Björn Töpel <bjorn@kernel.org>
Acked-by: Johan Almbladh <johan.almbladh@anyfinetworks.com>
Acked-by: Ilya Leoshkevich <iii@linux.ibm.com>
Link: https://lore.kernel.org/bpf/1636075800-3264-1-git-send-email-yangtiezhu@loongson.cn
Commit 2dc1e488e5cd ("libbpf: Support BTF_KIND_TYPE_TAG") added the
BTF_KIND_TYPE_TAG support. But to test vmlinux build with ...
#define __user __attribute__((btf_type_tag("user")))
... I needed to sync libbpf repo and manually copy libbpf sources to
pahole. To simplify process, I used BTF_KIND_RESTRICT to simulate the
BTF_KIND_TYPE_TAG with vmlinux build as "restrict" modifier is barely
used in kernel.
But this approach missed one case in dedup with structures where
BTF_KIND_RESTRICT is handled and BTF_KIND_TYPE_TAG is not handled in
btf_dedup_is_equiv(), and this will result in a pahole dedup failure.
This patch fixed this issue and a selftest is added in the subsequent
patch to test this scenario.
The other missed handling is in btf__resolve_size(). Currently the compiler
always emit like PTR->TYPE_TAG->... so in practice we don't hit the missing
BTF_KIND_TYPE_TAG handling issue with compiler generated code. But lets
add case BTF_KIND_TYPE_TAG in the switch statement to be future proof.
Fixes: 2dc1e488e5cd ("libbpf: Support BTF_KIND_TYPE_TAG")
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20211115163937.3922235-1-yhs@fb.com
Run it on the self-hosted builder with tag "z15".
Also add the infrastructure code for the self-hosted builder.
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Running vmtest inside a container removes the ability to use certain
root powers, among other things - mounting arbitrary images. Use
libguestfs in order to avoid having to mount anything.
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
A lot of tests in test_progs fail due to the missing trampoline
implementation on s390x (and a handful for other reasons). Yet, a lot
more pass, so disabling test_progs altogether is too heavy-handed.
So add a mechanism for arch-specific blacklists (as discussed in [1])
and introduce a s390x blacklist, that simply reflects the status quo.
[1] https://github.com/libbpf/libbpf/pull/204#discussion_r601768628
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
We need a different binary and console. Also use a fixed number of
cores in order to avoid OOM in case a builder has too many of them.
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Select the current config based on $ARCH value and thus rename
the existing config to config-latest.$ARCH.
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
The existing mkrootfs.sh is based on Arch Linux, which supports only
x86_64.
Add mkrootfs_debian.sh: a debootstrap-based script. Debian was chosen,
because it supports more architectures than other mainstream distros.
Move init setup to mkrootfs_tweak.sh, rename the existing Arch script
to mkrootfs_arch.sh.
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
There is no python-docutils on Debian Bullseye, but python3-docutils
exists everywhere. Since Python 2 is EOL anyway, use the Python 3
version.
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
LLVM patches ([1] for clang, [2] and [3] for BPF backend)
added support for btf_type_tag attributes. This patch
added support for the kernel.
The main motivation for btf_type_tag is to bring kernel
annotations __user, __rcu etc. to btf. With such information
available in btf, bpf verifier can detect mis-usages
and reject the program. For example, for __user tagged pointer,
developers can then use proper helper like bpf_probe_read_user()
etc. to read the data.
BTF_KIND_TYPE_TAG may also useful for other tracing
facility where instead of to require user to specify
kernel/user address type, the kernel can detect it
by itself with btf.
[1] https://reviews.llvm.org/D111199
[2] https://reviews.llvm.org/D113222
[3] https://reviews.llvm.org/D113496
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20211112012609.1505032-1-yhs@fb.com
Add new variants of perf_buffer__new() and perf_buffer__new_raw() that
use OPTS-based options for future extensibility ([0]). Given all the
currently used API names are best fits, re-use them and use
___libbpf_override() approach and symbol versioning to preserve ABI and
source code compatibility. struct perf_buffer_opts and struct
perf_buffer_raw_opts are kept as well, but they are restructured such
that they are OPTS-based when used with new APIs. For struct
perf_buffer_raw_opts we keep few fields intact, so we have to also
preserve the memory location of them both when used as OPTS and for
legacy API variants. This is achieved with anonymous padding for OPTS
"incarnation" of the struct. These pads can be eventually used for new
options.
[0] Closes: https://github.com/libbpf/libbpf/issues/311
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211111053624.190580-6-andrii@kernel.org
Change btf_dump__new() and corresponding struct btf_dump_ops structure
to be extensible by using OPTS "framework" ([0]). Given we don't change
the names, we use a similar approach as with bpf_prog_load(), but this
time we ended up with two APIs with the same name and same number of
arguments, so overloading based on number of arguments with
___libbpf_override() doesn't work.
Instead, use "overloading" based on types. In this particular case,
print callback has to be specified, so we detect which argument is
a callback. If it's 4th (last) argument, old implementation of API is
used by user code. If not, it must be 2nd, and thus new implementation
is selected. The rest is handled by the same symbol versioning approach.
btf_ext argument is dropped as it was never used and isn't necessary
either. If in the future we'll need btf_ext, that will be added into
OPTS-based struct btf_dump_opts.
struct btf_dump_opts is reused for both old API and new APIs. ctx field
is marked deprecated in v0.7+ and it's put at the same memory location
as OPTS's sz field. Any user of new-style btf_dump__new() will have to
set sz field and doesn't/shouldn't use ctx, as ctx is now passed along
the callback as mandatory input argument, following the other APIs in
libbpf that accept callbacks consistently.
Again, this is quite ugly in implementation, but is done in the name of
backwards compatibility and uniform and extensible future APIs (at the
same time, sigh). And it will be gone in libbpf 1.0.
[0] Closes: https://github.com/libbpf/libbpf/issues/283
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211111053624.190580-5-andrii@kernel.org
btf__dedup() and struct btf_dedup_opts were added before we figured out
OPTS mechanism. As such, btf_dedup_opts is non-extensible without
breaking an ABI and potentially crashing user application.
Unfortunately, btf__dedup() and btf_dedup_opts are short and succinct
names that would be great to preserve and use going forward. So we use
___libbpf_override() macro approach, used previously for bpf_prog_load()
API, to define a new btf__dedup() variant that accepts only struct btf *
and struct btf_dedup_opts * arguments, and rename the old btf__dedup()
implementation into btf__dedup_deprecated(). This keeps both source and
binary compatibility with old and new applications.
The biggest problem was struct btf_dedup_opts, which wasn't OPTS-based,
and as such doesn't have `size_t sz;` as a first field. But btf__dedup()
is a pretty rarely used API and I believe that the only currently known
users (besides selftests) are libbpf's own bpf_linker and pahole.
Neither use case actually uses options and just passes NULL. So instead
of doing extra hacks, just rewrite struct btf_dedup_opts into OPTS-based
one, move btf_ext argument into those opts (only bpf_linker needs to
dedup btf_ext, so it's not a typical thing to specify), and drop never
used `dont_resolve_fwds` option (it was never used anywhere, AFAIK, it
makes BTF dedup much less useful and efficient).
Just in case, for old implementation, btf__dedup_deprecated(), detect
non-NULL options and error out with helpful message, to help users
migrate, if there are any user playing with btf__dedup().
The last remaining piece is dedup_table_size, which is another
anachronism from very early days of BTF dedup. Since then it has been
reduced to the only valid value, 1, to request forced hash collisions.
This is only used during testing. So instead introduce a bool flag to
force collisions explicitly.
This patch also adapts selftests to new btf__dedup() and btf_dedup_opts
use to avoid selftests breakage.
[0] Closes: https://github.com/libbpf/libbpf/issues/281
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211111053624.190580-4-andrii@kernel.org
Add bpf_program__flags() API to retrieve prog_flags that will be (or
were) supplied to BPF_PROG_LOAD command.
Also add bpf_program__set_extra_flags() API to allow to set *extra*
flags, in addition to those determined by program's SEC() definition.
Such flags are logically OR'ed with libbpf-derived flags.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211111051758.92283-2-andrii@kernel.org
It may be helpful to have access to the ifindex during bpf socket
lookup. An example may be to scope certain socket lookup logic to
specific interfaces, i.e. an interface may be made exempt from custom
lookup code.
Add the ifindex of the arriving connection to the bpf_sk_lookup API.
Signed-off-by: Mark Pashmfouroush <markpash@cloudflare.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211110111016.5670-2-markpash@cloudflare.com
In some profiler use cases, it is necessary to map an address to the
backing file, e.g., a shared library. bpf_find_vma helper provides a
flexible way to achieve this. bpf_find_vma maps an address of a task to
the vma (vm_area_struct) for this address, and feed the vma to an callback
BPF function. The callback function is necessary here, as we need to
ensure mmap_sem is unlocked.
It is necessary to lock mmap_sem for find_vma. To lock and unlock mmap_sem
safely when irqs are disable, we use the same mechanism as stackmap with
build_id. Specifically, when irqs are disabled, the unlocked is postponed
in an irq_work. Refactor stackmap.c so that the irq_work is shared among
bpf_find_vma and stackmap helpers.
Signed-off-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Tested-by: Hengqi Chen <hengqi.chen@gmail.com>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20211105232330.1936330-2-songliubraving@fb.com
This deprecation annotation has no effect because for struct deprecation
attribute has to be declared after struct definition. But instead of
moving it to the end of struct definition, remove it. When deprecation
will go in effect at libbpf v0.7, this deprecation attribute will cause
libbpf's own source code compilation to trigger deprecation warnings,
which is unavoidable because libbpf still has to support that API.
So keep deprecation of APIs, but don't mark structs used in API as
deprecated.
Fixes: e21d585cb3db ("libbpf: Deprecate multi-instance bpf_program APIs")
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Dave Marchevsky <davemarchevsky@fb.com>
Link: https://lore.kernel.org/bpf/20211103220845.2676888-8-andrii@kernel.org
Add a new unified OPTS-based low-level API for program loading,
bpf_prog_load() ([0]). bpf_prog_load() accepts few "mandatory"
parameters as input arguments (program type, name, license,
instructions) and all the other optional (as in not required to specify
for all types of BPF programs) fields into struct bpf_prog_load_opts.
This makes all the other non-extensible APIs variant for BPF_PROG_LOAD
obsolete and they are slated for deprecation in libbpf v0.7:
- bpf_load_program();
- bpf_load_program_xattr();
- bpf_verify_program().
Implementation-wise, internal helper libbpf__bpf_prog_load is refactored
to become a public bpf_prog_load() API. struct bpf_prog_load_params used
internally is replaced by public struct bpf_prog_load_opts.
Unfortunately, while conceptually all this is pretty straightforward,
the biggest complication comes from the already existing bpf_prog_load()
*high-level* API, which has nothing to do with BPF_PROG_LOAD command.
We try really hard to have a new API named bpf_prog_load(), though,
because it maps naturally to BPF_PROG_LOAD command.
For that, we rename old bpf_prog_load() into bpf_prog_load_deprecated()
and mark it as COMPAT_VERSION() for shared library users compiled
against old version of libbpf. Statically linked users and shared lib
users compiled against new version of libbpf headers will get "rerouted"
to bpf_prog_deprecated() through a macro helper that decides whether to
use new or old bpf_prog_load() based on number of input arguments (see
___libbpf_overload in libbpf_common.h).
To test that existing
bpf_prog_load()-using code compiles and works as expected, I've compiled
and ran selftests as is. I had to remove (locally) selftest/bpf/Makefile
-Dbpf_prog_load=bpf_prog_test_load hack because it was conflicting with
the macro-based overload approach. I don't expect anyone else to do
something like this in practice, though. This is testing-specific way to
replace bpf_prog_load() calls with special testing variant of it, which
adds extra prog_flags value. After testing I kept this selftests hack,
but ensured that we use a new bpf_prog_load_deprecated name for this.
This patch also marks bpf_prog_load() and bpf_prog_load_xattr() as deprecated.
bpf_object interface has to be used for working with struct bpf_program.
Libbpf doesn't support loading just a bpf_program.
The silver lining is that when we get to libbpf 1.0 all these
complication will be gone and we'll have one clean bpf_prog_load()
low-level API with no backwards compatibility hackery surrounding it.
[0] Closes: https://github.com/libbpf/libbpf/issues/284
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211103220845.2676888-4-andrii@kernel.org
It's confusing that libbpf-provided helper macro doesn't start with
LIBBPF. Also "declare" vs "define" is confusing terminology, I can never
remember and always have to look up previous examples.
Bypass both issues by renaming DECLARE_LIBBPF_OPTS into a short and
clean LIBBPF_OPTS. To avoid breaking existing code, provide:
#define DECLARE_LIBBPF_OPTS LIBBPF_OPTS
in libbpf_legacy.h. We can decide later if we ever want to remove it or
we'll keep it forever because it doesn't add any maintainability burden.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Dave Marchevsky <davemarchevsky@fb.com>
Link: https://lore.kernel.org/bpf/20211103220845.2676888-2-andrii@kernel.org
e_shnum does include section #0 and as such is exactly the number of ELF
sections that we need to allocate memory for to use section indices as
array indices. Fix the off-by-one error.
This is purely accounting fix, previously we were overallocating one
too many array items. But no correctness errors otherwise.
Fixes: 25bbbd7a444b ("libbpf: Remove assumptions about uniqueness of .rodata/.data/.bss maps")
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20211103173213.1376990-5-andrii@kernel.org
.BTF and .BTF.ext ELF sections should have SHT_PROGBITS type and contain
data. If they are not, ELF is invalid or corrupted, so bail out.
Otherwise this can lead to data->d_buf being NULL and SIGSEGV later on.
Reported by oss-fuzz project.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20211103173213.1376990-4-andrii@kernel.org
Deprecate AF_XDP support in libbpf ([0]). This has been moved to
libxdp as it is a better fit for that library. The AF_XDP support only
uses the public libbpf functions and can therefore just use libbpf as
a library from libxdp. The libxdp APIs are exactly the same so it
should just be linking with libxdp instead of libbpf for the AF_XDP
functionality. If not, please submit a bug report. Linking with both
libraries is supported but make sure you link in the correct order so
that the new functions in libxdp are used instead of the deprecated
ones in libbpf.
Libxdp can be found at https://github.com/xdp-project/xdp-tools.
[0] Closes: https://github.com/libbpf/libbpf/issues/270
Signed-off-by: Magnus Karlsson <magnus.karlsson@intel.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/bpf/20211029090111.4733-1-magnus.karlsson@gmail.com
Add a simple wrapper for passing an fd and getting a new one >= 3 if it
is one of 0, 1, or 2. There are two primary reasons to make this change:
First, libbpf relies on the assumption a certain BPF fd is never 0 (e.g.
most recently noticed in [0]). Second, Alexei pointed out in [1] that
some environments reset stdin, stdout, and stderr if they notice an
invalid fd at these numbers. To protect against both these cases, switch
all internal BPF syscall wrappers in libbpf to always return an fd >= 3.
We only need to modify the syscall wrappers and not other code that
assumes a valid fd by doing >= 0, to avoid pointless churn, and because
it is still a valid assumption. The cost paid is two additional syscalls
if fd is in range [0, 2].
[0]: e31eec77e4ab ("bpf: selftests: Fix fd cleanup in get_branch_snapshot")
[1]: https://lore.kernel.org/bpf/CAADnVQKVKY8o_3aU8Gzke443+uHa-eGoM0h7W4srChMXU1S4Bg@mail.gmail.com
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Song Liu <songliubraving@fb.com>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20211028063501.2239335-5-memxor@gmail.com
This extends existing ksym relocation code to also support relocating
weak ksyms. Care needs to be taken to zero out the src_reg (currently
BPF_PSEUOD_BTF_ID, always set for gen_loader by bpf_object__relocate_data)
when the BTF ID lookup fails at runtime. This is not a problem for
libbpf as it only sets ext->is_set when BTF ID lookup succeeds (and only
proceeds in case of failure if ext->is_weak, leading to src_reg
remaining as 0 for weak unresolved ksym).
A pattern similar to emit_relo_kfunc_btf is followed of first storing
the default values and then jumping over actual stores in case of an
error. For src_reg adjustment, we also need to perform it when copying
the populated instruction, so depending on if copied insn[0].imm is 0 or
not, we decide to jump over the adjustment.
We cannot reach that point unless the ksym was weak and resolved and
zeroed out, as the emit_check_err will cause us to jump to cleanup
label, so we do not need to recheck whether the ksym is weak before
doing the adjustment after copying BTF ID and BTF FD.
This is consistent with how libbpf relocates weak ksym. Logging
statements are added to show the relocation result and aid debugging.
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211028063501.2239335-4-memxor@gmail.com
This uses the bpf_kallsyms_lookup_name helper added in previous patches
to relocate typeless ksyms. The return value ENOENT can be ignored, and
the value written to 'res' can be directly stored to the insn, as it is
overwritten to 0 on lookup failure. For repeating symbols, we can simply
copy the previously populated bpf_insn.
Also, we need to take care to not close fds for typeless ksym_desc, so
reuse the 'off' member's space to add a marker for typeless ksym and use
that to skip them in cleanup_relos.
We add a emit_ksym_relo_log helper that avoids duplicating common
logging instructions between typeless and weak ksym (for future commit).
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211028063501.2239335-3-memxor@gmail.com
This patch adds the libbpf infrastructure for supporting a
per-map-type "map_extra" field, whose definition will be
idiosyncratic depending on map type.
For example, for the bloom filter map, the lower 4 bits of
map_extra is used to denote the number of hash functions.
Please note that until libbpf 1.0 is here, the
"bpf_create_map_params" struct is used as a temporary
means for propagating the map_extra field to the kernel.
Signed-off-by: Joanne Koong <joannekoong@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20211027234504.30744-3-joannekoong@fb.com
This patch adds the kernel-side changes for the implementation of
a bpf bloom filter map.
The bloom filter map supports peek (determining whether an element
is present in the map) and push (adding an element to the map)
operations.These operations are exposed to userspace applications
through the already existing syscalls in the following way:
BPF_MAP_LOOKUP_ELEM -> peek
BPF_MAP_UPDATE_ELEM -> push
The bloom filter map does not have keys, only values. In light of
this, the bloom filter map's API matches that of queue stack maps:
user applications use BPF_MAP_LOOKUP_ELEM/BPF_MAP_UPDATE_ELEM
which correspond internally to bpf_map_peek_elem/bpf_map_push_elem,
and bpf programs must use the bpf_map_peek_elem and bpf_map_push_elem
APIs to query or add an element to the bloom filter map. When the
bloom filter map is created, it must be created with a key_size of 0.
For updates, the user will pass in the element to add to the map
as the value, with a NULL key. For lookups, the user will pass in the
element to query in the map as the value, with a NULL key. In the
verifier layer, this requires us to modify the argument type of
a bloom filter's BPF_FUNC_map_peek_elem call to ARG_PTR_TO_MAP_VALUE;
as well, in the syscall layer, we need to copy over the user value
so that in bpf_map_peek_elem, we know which specific value to query.
A few things to please take note of:
* If there are any concurrent lookups + updates, the user is
responsible for synchronizing this to ensure no false negative lookups
occur.
* The number of hashes to use for the bloom filter is configurable from
userspace. If no number is specified, the default used will be 5 hash
functions. The benchmarks later in this patchset can help compare the
performance of using different number of hashes on different entry
sizes. In general, using more hashes decreases both the false positive
rate and the speed of a lookup.
* Deleting an element in the bloom filter map is not supported.
* The bloom filter map may be used as an inner map.
* The "max_entries" size that is specified at map creation time is used
to approximate a reasonable bitmap size for the bloom filter, and is not
otherwise strictly enforced. If the user wishes to insert more entries
into the bloom filter than "max_entries", they may do so but they should
be aware that this may lead to a higher false positive rate.
Signed-off-by: Joanne Koong <joannekoong@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20211027234504.30744-2-joannekoong@fb.com
__BYTE_ORDER is supposed to be defined by a libc, and __BYTE_ORDER__ -
by a compiler. bpf_core_read.h checks __BYTE_ORDER == __LITTLE_ENDIAN,
which is true if neither are defined, leading to incorrect behavior on
big-endian hosts if libc headers are not included, which is often the
case.
Fixes: ee26dade0e3b ("libbpf: Add support for relocatable bitfields")
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20211026010831.748682-2-iii@linux.ibm.com
The name of the API doesn't convey clearly that this size is in number
of bytes (there needed to be a separate comment to make this clear in
libbpf.h). Further, measuring the size of BPF program in bytes is not
exactly the best fit, because BPF programs always consist of 8-byte
instructions. As such, bpf_program__insn_cnt() is a better alternative
in pretty much any imaginable case.
So schedule bpf_program__size() deprecation starting from v0.7 and it
will be removed in libbpf 1.0.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211025224531.1088894-5-andrii@kernel.org
Schedule deprecation of a set of APIs that are related to multi-instance
bpf_programs:
- bpf_program__set_prep() ([0]);
- bpf_program__{set,unset}_instance() ([1]);
- bpf_program__nth_fd().
These APIs are obscure, very niche, and don't seem to be used much in
practice. bpf_program__set_prep() is pretty useless for anything but the
simplest BPF programs, as it doesn't allow to adjust BPF program load
attributes, among other things. In short, it already bitrotted and will
bitrot some more if not removed.
With bpf_program__insns() API, which gives access to post-processed BPF
program instructions of any given entry-point BPF program, it's now
possible to do whatever necessary adjustments were possible with
set_prep() API before, but also more. Given any such use case is
automatically an advanced use case, requiring users to stick to
low-level bpf_prog_load() APIs and managing their own prog FDs is
reasonable.
[0] Closes: https://github.com/libbpf/libbpf/issues/299
[1] Closes: https://github.com/libbpf/libbpf/issues/300
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211025224531.1088894-4-andrii@kernel.org
Add APIs providing read-only access to bpf_program BPF instructions ([0]).
This is useful for diagnostics purposes, but it also allows a cleaner
support for cloning BPF programs after libbpf did all the FD resolution
and CO-RE relocations, subprog instructions appending, etc. Currently,
cloning BPF program is possible only through hijacking a half-broken
bpf_program__set_prep() API, which doesn't really work well for anything
but most primitive programs. For instance, set_prep() API doesn't allow
adjusting BPF program load parameters which are necessary for loading
fentry/fexit BPF programs (the case where BPF program cloning is
a necessity if doing some sort of mass-attachment functionality).
Given bpf_program__set_prep() API is set to be deprecated, having
a cleaner alternative is a must. libbpf internally already keeps track
of linear array of struct bpf_insn, so it's not hard to expose it. The
only gotcha is that libbpf previously freed instructions array during
bpf_object load time, which would make this API much less useful overall,
because in between bpf_object__open() and bpf_object__load() a lot of
changes to instructions are done by libbpf.
So this patch makes libbpf hold onto prog->insns array even after BPF
program loading. I think this is a small price for added functionality
and improved introspection of BPF program code.
See retsnoop PR ([1]) for how it can be used in practice and code
savings compared to relying on bpf_program__set_prep().
[0] Closes: https://github.com/libbpf/libbpf/issues/298
[1] https://github.com/anakryiko/retsnoop/pull/1
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211025224531.1088894-3-andrii@kernel.org
The sync-kernel.sh script has two consecutive tests for $BPF_BRANCH
being provided by the user (and so the second one can currently never
fail). Looking at the error message displayed in each case, we want to
keep the second one. Let's remove the first check.
Signed-off-by: Quentin Monnet <quentin@isovalent.com>
The commit_signature() function does not use the hash of the commit,
which typically differs between the kernel repo and the mirrored
version, but the subject for this commit. Fix the comment accordingly.
Signed-off-by: Quentin Monnet <quentin@isovalent.com>
Original code assumed fixed and correct BTF header length. That's not
always the case, though, so fix this bug with a proper additional check.
And use actual header length instead of sizeof(struct btf_header) in
sanity checks.
Fixes: 8a138aed4a80 ("bpf: btf: Add BTF support to libbpf")
Reported-by: Evgeny Vereshchagin <evvers@ya.ru>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211023003157.726961-2-andrii@kernel.org
btf_header's str_off+str_len or type_off+type_len can overflow as they
are u32s. This will lead to bypassing the sanity checks during BTF
parsing, resulting in crashes afterwards. Fix by using 64-bit signed
integers for comparison.
Fixes: d8123624506c ("libbpf: Fix BTF data layout checks and allow empty BTF")
Reported-by: Evgeny Vereshchagin <evvers@ya.ru>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211023003157.726961-1-andrii@kernel.org
Building libbpf sources out of kernel tree (in Github repo) we run into
compilation error due to unknown __aligned attribute. It must be coming
from some kernel header, which is not available to Github sources. Use
explicit __attribute__((aligned(16))) instead.
Fixes: 961632d54163 ("libbpf: Fix dumping non-aligned __int128")
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211022192502.2975553-1-andrii@kernel.org
Map name that's assigned to internal maps (.rodata, .data, .bss, etc)
consist of a small prefix of bpf_object's name and ELF section name as
a suffix. This makes it hard for users to "guess" the name to use for
looking up by name with bpf_object__find_map_by_name() API.
One proposal was to drop object name prefix from the map name and just
use ".rodata", ".data", etc, names. One downside called out was that
when multiple BPF applications are active on the host, it will be hard
to distinguish between multiple instances of .rodata and know which BPF
object (app) they belong to. Having few first characters, while quite
limiting, still can give a bit of a clue, in general.
Note, though, that btf_value_type_id for such global data maps (ARRAY)
points to DATASEC type, which encodes full ELF name, so tools like
bpftool can take advantage of this fact to "recover" full original name
of the map. This is also the reason why for custom .data.* and .rodata.*
maps libbpf uses only their ELF names and doesn't prepend object name at
all.
Another downside of such approach is that it is not backwards compatible
and, among direct use of bpf_object__find_map_by_name() API, will break
any BPF skeleton generated using bpftool that was compiled with older
libbpf version.
Instead of causing all this pain, libbpf will still generate map name
using a combination of object name and ELF section name, but it will
allow looking such maps up by their natural names, which correspond to
their respective ELF section names. This means non-truncated ELF section
names longer than 15 characters are going to be expected and supported.
With such set up, we get the best of both worlds: leave small bits of
a clue about BPF application that instantiated such maps, as well as
making it easy for user apps to lookup such maps at runtime. In this
sense it closes corresponding libbpf 1.0 issue ([0]).
BPF skeletons will continue using full names for lookups.
[0] Closes: https://github.com/libbpf/libbpf/issues/275
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20211021014404.2635234-10-andrii@kernel.org
Add support for having multiple .rodata and .data data sections ([0]).
.rodata/.data are supported like the usual, but now also
.rodata.<whatever> and .data.<whatever> are also supported. Each such
section will get its own backing BPF_MAP_TYPE_ARRAY, just like
.rodata and .data.
Multiple .bss maps are not supported, as the whole '.bss' name is
confusing and might be deprecated soon, as well as user would need to
specify custom ELF section with SEC() attribute anyway, so might as well
stick to just .data.* and .rodata.* convention.
User-visible map name for such new maps is going to be just their ELF
section names.
[0] https://github.com/libbpf/libbpf/issues/274
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20211021014404.2635234-8-andrii@kernel.org
Remove internal libbpf assumption that there can be only one .rodata,
.data, and .bss map per BPF object. To achieve that, extend and
generalize the scheme that was used for keeping track of relocation ELF
sections. Now each ELF section has a temporary extra index that keeps
track of logical type of ELF section (relocations, data, read-only data,
BSS). Switch relocation to this scheme, as well as .rodata/.data/.bss
handling.
We don't yet allow multiple .rodata, .data, and .bss sections, but no
libbpf internal code makes an assumption that there can be only one of
each and thus they can be explicitly referenced by a single index. Next
patches will actually allow multiple .rodata and .data sections.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20211021014404.2635234-5-andrii@kernel.org
Minimize the usage of class-agnostic gelf_xxx() APIs from libelf. These
APIs require copying ELF data structures into local GElf_xxx structs and
have a more cumbersome API. BPF ELF file is defined to be always 64-bit
ELF object, even when intended to be run on 32-bit host architectures,
so there is no need to do class-agnostic conversions everywhere. BPF
static linker implementation within libbpf has been using Elf64-specific
types since initial implementation.
Add two simple helpers, elf_sym_by_idx() and elf_rel_by_idx(), for more
succinct direct access to ELF symbol and relocation records within ELF
data itself and switch all the GElf_xxx usage into Elf64_xxx
equivalents. The only remaining place within libbpf.c that's still using
gelf API is gelf_getclass(), as there doesn't seem to be a direct way to
get underlying ELF bitness.
No functional changes intended.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20211021014404.2635234-4-andrii@kernel.org
There isn't a good use case where anyone but libbpf itself needs to call
btf__finalize_data(). It was implemented for internal use and it's not
clear why it was made into public API in the first place. To function, it
requires active ELF data, which is stored inside bpf_object for the
duration of opening phase only. But the only BTF that needs bpf_object's
ELF is that bpf_object's BTF itself, which libbpf fixes up automatically
during bpf_object__open() operation anyways. There is no need for any
additional fix up and no reasonable scenario where it's useful and
appropriate.
Thus, btf__finalize_data() is just an API atavism and is better removed.
So this patch marks it as deprecated immediately (v0.6+) and moves the
code from btf.c into libbpf.c where it's used in the context of
bpf_object opening phase. Such code co-location allows to make code
structure more straightforward and remove bpf_object__section_size() and
bpf_object__variable_offset() internal helpers from libbpf_internal.h,
making them static. Their naming is also adjusted to not create
a wrong illusion that they are some sort of method of bpf_object. They
are internal helpers and are called appropriately.
This is part of libbpf 1.0 effort ([0]).
[0] Closes: https://github.com/libbpf/libbpf/issues/276
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20211021014404.2635234-2-andrii@kernel.org
Patch set [1] introduced BTF_KIND_TAG to allow tagging
declarations for struct/union, struct/union field, var, func
and func arguments and these tags will be encoded into
dwarf. They are also encoded to btf by llvm for the bpf target.
After BTF_KIND_TAG is introduced, we intended to use it
for kernel __user attributes. But kernel __user is actually
a type attribute. Upstream and internal discussion showed
it is not a good idea to mix declaration attribute and
type attribute. So we proposed to introduce btf_type_tag
as a type attribute and existing btf_tag renamed to
btf_decl_tag ([2]).
This patch renamed BTF_KIND_TAG to BTF_KIND_DECL_TAG and some
other declarations with *_tag to *_decl_tag to make it clear
the tag is for declaration. In the future, BTF_KIND_TYPE_TAG
might be introduced per [3].
[1] https://lore.kernel.org/bpf/20210914223004.244411-1-yhs@fb.com/
[2] https://reviews.llvm.org/D111588
[3] https://reviews.llvm.org/D111199
Fixes: b5ea834dde6b ("bpf: Support for new btf kind BTF_KIND_TAG")
Fixes: 5b84bd10363e ("libbpf: Add support for BTF_KIND_TAG")
Fixes: 5c07f2fec003 ("bpftool: Add support for BTF_KIND_TAG")
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211012164838.3345699-1-yhs@fb.com
When fed an empty BPF object, bpftool gen skeleton -L crashes at
btf__set_fd() since it assumes presence of obj->btf, however for
the sequence below clang adds no .BTF section (hence no BTF).
Reproducer:
$ touch a.bpf.c
$ clang -O2 -g -target bpf -c a.bpf.c
$ bpftool gen skeleton -L a.bpf.o
/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
/* THIS FILE IS AUTOGENERATED! */
struct a_bpf {
struct bpf_loader_ctx ctx;
Segmentation fault (core dumped)
The same occurs for files compiled without BTF info, i.e. without
clang's -g flag.
Fixes: 67234743736a (libbpf: Generate loader program out of BPF ELF file.)
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20210930061634.1840768-1-memxor@gmail.com
Add a bulk copying api, btf__add_btf(), that speeds up and simplifies
appending entire contents of one BTF object to another one, taking care
of copying BTF type data, adjusting resulting BTF type IDs according to
their new locations in the destination BTF object, as well as copying
and deduplicating all the referenced strings and updating all the string
offsets in new BTF types as appropriate.
This API is intended to be used from tools that are generating and
otherwise manipulating BTFs generically, such as pahole. In pahole's
case, this API is useful for speeding up parallelized BTF encoding, as
it allows pahole to offload all the intricacies of BTF type copying to
libbpf and handle the parallelization aspects of the process.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Song Liu <songliubraving@fb.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Link: https://lore.kernel.org/bpf/20211006051107.17921-2-andrii@kernel.org
This change updates the BPF syscall loader to relocate BTF_KIND_FUNC
relocations, with support for weak kfunc relocations. The general idea
is to move map_fds to loader map, and also use the data for storing
kfunc BTF fds. Since both reuse the fd_array parameter, they need to be
kept together.
For map_fds, we reserve MAX_USED_MAPS slots in a region, and for kfunc,
we reserve MAX_KFUNC_DESCS. This is done so that insn->off has more
chances of being <= INT16_MAX than treating data map as a sparse array
and adding fd as needed.
When the MAX_KFUNC_DESCS limit is reached, we fall back to the sparse
array model, so that as long as it does remain <= INT16_MAX, we pass an
index relative to the start of fd_array.
We store all ksyms in an array where we try to avoid calling the
bpf_btf_find_by_name_kind helper, and also reuse the BTF fd that was
already stored. This also speeds up the loading process compared to
emitting calls in all cases, in later tests.
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211002011757.311265-9-memxor@gmail.com
Preserve these calls as it allows verifier to succeed in loading the
program if they are determined to be unreachable after dead code
elimination during program load. If not, the verifier will fail at
runtime. This is done for ext->is_weak symbols similar to the case for
variable ksyms.
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20211002011757.311265-8-memxor@gmail.com
This patch adds libbpf support for kernel module function call support.
The fd_array parameter is used during BPF program load to pass module
BTFs referenced by the program. insn->off is set to index into this
array, but starts from 1, because insn->off as 0 is reserved for
btf_vmlinux.
We try to use existing insn->off for a module, since the kernel limits
the maximum distinct module BTFs for kfuncs to 256, and also because
index must never exceed the maximum allowed value that can fit in
insn->off (INT16_MAX). In the future, if kernel interprets signed offset
as unsigned for kfunc calls, this limit can be increased to UINT16_MAX.
Also introduce a btf__find_by_name_kind_own helper to start searching
from module BTF's start id when we know that the BTF ID is not present
in vmlinux BTF (in find_ksym_btf_id).
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211002011757.311265-7-memxor@gmail.com
When the loader indicates an internal error (result of a checked bpf
system call), it returns the result in attr.test.retval. However, tests
that rely on ASSERT_OK_PTR on NULL (returned from light skeleton) may
miss that NULL denotes an error if errno is set to 0. This would result
in skel pointer being NULL, while ASSERT_OK_PTR returning 1, leading to
a SEGV on dereference of skel, because libbpf_get_error relies on the
assumption that errno is always set in case of error for ptr == NULL.
In particular, this was observed for the ksyms_module test. When
executed using `./test_progs -t ksyms`, prior tests manipulated errno
and the test didn't crash when it failed at ksyms_module load, while
using `./test_progs -t ksyms_module` crashed due to errno being
untouched.
Fixes: 67234743736a (libbpf: Generate loader program out of BPF ELF file.)
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210927145941.1383001-11-memxor@gmail.com
The previous patch to ignore STT_SECTION symbols only added the ignore
condition in one of them. This fails if there's more than one map
definition in the 'maps' section, because the subsequent modulus check will
fail, resulting in error messages like:
libbpf: elf: unable to determine legacy map definition size in ./xdpdump_xdp.o
Fix this by also ignoring STT_SECTION in the first loop.
Fixes: c3e8c44a9063 ("libbpf: Ignore STT_SECTION symbols in 'maps' section")
Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210929213837.832449-1-toke@redhat.com
Initial idea was to run it hourly, but when it runs hourly it produce a
lot of useless noise and we had to switch it do daily. When we run it
daily caching make much less sense and only make debugging more complex.
When a BPF object is compiled without BTF info (without -g),
trying to link such objects using bpftool causes a SIGSEGV due to
btf__get_nr_types accessing obj->btf which is NULL. Fix this by
checking for the NULL pointer, and return error.
Reproducer:
$ cat a.bpf.c
extern int foo(void);
int bar(void) { return foo(); }
$ cat b.bpf.c
int foo(void) { return 0; }
$ clang -O2 -target bpf -c a.bpf.c
$ clang -O2 -target bpf -c b.bpf.c
$ bpftool gen obj out a.bpf.o b.bpf.o
Segmentation fault (core dumped)
After fix:
$ bpftool gen obj out a.bpf.o b.bpf.o
libbpf: failed to find BTF info for object 'a.bpf.o'
Error: failed to link 'a.bpf.o': Unknown error -22 (-22)
Fixes: a46349227cd8 (libbpf: Add linker extern resolution support for functions and global variables)
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20210924023725.70228-1-memxor@gmail.com
Update "sk_lookup/" definition to be a stand-alone type specifier,
with backwards-compatible prefix match logic in non-libbpf-1.0 mode.
Currently in selftests all the "sk_lookup/<whatever>" uses just use
<whatever> for duplicated unique name encoding, which is redundant as
BPF program's name (C function name) uniquely and descriptively
identifies the intended use for such BPF programs.
With libbpf's SEC_DEF("sk_lookup") definition updated, switch existing
sk_lookup programs to use "unqualified" SEC("sk_lookup") section names,
with no random text after it.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Dave Marchevsky <davemarchevsky@fb.com>
Link: https://lore.kernel.org/bpf/20210928161946.2512801-11-andrii@kernel.org
Implement strict ELF section name handling for BPF programs. It utilizes
`libbpf_set_strict_mode()` framework and adds new flag: LIBBPF_STRICT_SEC_NAME.
If this flag is set, libbpf will enforce exact section name matching for
a lot of program types that previously allowed just partial prefix
match. E.g., if previously SEC("xdp_whatever_i_want") was allowed, now
in strict mode only SEC("xdp") will be accepted, which makes SEC("")
definitions cleaner and more structured. SEC() now won't be used as yet
another way to uniquely encode BPF program identifier (for that
C function name is better and is guaranteed to be unique within
bpf_object). Now SEC() is strictly BPF program type and, depending on
program type, extra load/attach parameter specification.
Libbpf completely supports multiple BPF programs in the same ELF
section, so multiple BPF programs of the same type/specification easily
co-exist together within the same bpf_object scope.
Additionally, a new (for now internal) convention is introduced: section
name that can be a stand-alone exact BPF program type specificator, but
also could have extra parameters after '/' delimiter. An example of such
section is "struct_ops", which can be specified by itself, but also
allows to specify the intended operation to be attached to, e.g.,
"struct_ops/dctcp_init". Note, that "struct_ops_some_op" is not allowed.
Such section definition is specified as "struct_ops+".
This change is part of libbpf 1.0 effort ([0], [1]).
[0] Closes: https://github.com/libbpf/libbpf/issues/271
[1] https://github.com/libbpf/libbpf/wiki/Libbpf:-the-road-to-v1.0#stricter-and-more-uniform-bpf-program-section-name-sec-handling
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Dave Marchevsky <davemarchevsky@fb.com>
Link: https://lore.kernel.org/bpf/20210928161946.2512801-10-andrii@kernel.org
Complete SEC() table refactoring towards unified form by rewriting
BPF_APROG_SEC and BPF_EAPROG_SEC definitions with
SEC_DEF(SEC_ATTACHABLE_OPT) (for optional expected_attach_type) and
SEC_DEF(SEC_ATTACHABLE) (mandatory expected_attach_type), respectively.
Drop BPF_APROG_SEC, BPF_EAPROG_SEC, and BPF_PROG_SEC_IMPL macros after
that, leaving SEC_DEF() macro as the only one used.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Dave Marchevsky <davemarchevsky@fb.com>
Link: https://lore.kernel.org/bpf/20210928161946.2512801-9-andrii@kernel.org
Refactor ELF section handler definitions table to use a set of flags and
unified SEC_DEF() macro. This allows for more succinct and table-like
set of definitions, and allows to more easily extend the logic without
adding more verbosity (this is utilized in later patches in the series).
This approach is also making libbpf-internal program pre-load callback
not rely on bpf_sec_def definition, which demonstrates that future
pluggable ELF section handlers will be able to achieve similar level of
integration without libbpf having to expose extra types and APIs.
For starters, update SEC_DEF() definitions and make them more succinct.
Also convert BPF_PROG_SEC() and BPF_APROG_COMPAT() definitions to
a common SEC_DEF() use.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Dave Marchevsky <davemarchevsky@fb.com>
Link: https://lore.kernel.org/bpf/20210928161946.2512801-8-andrii@kernel.org
Move closer to not relying on bpf_sec_def internals that won't be part
of public API, when pluggable SEC() handlers will be allowed. Drop
pre-calculated prefix length, and in various helpers don't rely on this
prefix length availability. Also minimize reliance on knowing
bpf_sec_def's prefix for few places where section prefix shortcuts are
supported (e.g., tp vs tracepoint, raw_tp vs raw_tracepoint).
Given checking some string for having a given string-constant prefix is
such a common operation and so annoying to be done with pure C code, add
a small macro helper, str_has_pfx(), and reuse it throughout libbpf.c
where prefix comparison is performed. With __builtin_constant_p() it's
possible to have a convenient helper that checks some string for having
a given prefix, where prefix is either string literal (or compile-time
known string due to compiler optimization) or just a runtime string
pointer, which is quite convenient and saves a lot of typing and string
literal duplication.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Dave Marchevsky <davemarchevsky@fb.com>
Link: https://lore.kernel.org/bpf/20210928161946.2512801-7-andrii@kernel.org
Refactor internals of libbpf to allow adding custom SEC() handling logic
easily from outside of libbpf. To that effect, each SEC()-handling
registration sets mandatory program type/expected attach type for
a given prefix and can provide three callbacks called at different
points of BPF program lifetime:
- init callback for right after bpf_program is initialized and
prog_type/expected_attach_type is set. This happens during
bpf_object__open() step, close to the very end of constructing
bpf_object, so all the libbpf APIs for querying and updating
bpf_program properties should be available;
- pre-load callback is called right before BPF_PROG_LOAD command is
called in the kernel. This callbacks has ability to set both
bpf_program properties, as well as program load attributes, overriding
and augmenting the standard libbpf handling of them;
- optional auto-attach callback, which makes a given SEC() handler
support auto-attachment of a BPF program through bpf_program__attach()
API and/or BPF skeletons <skel>__attach() method.
Each callbacks gets a `long cookie` parameter passed in, which is
specified during SEC() handling. This can be used by callbacks to lookup
whatever additional information is necessary.
This is not yet completely ready to be exposed to the outside world,
mainly due to non-public nature of struct bpf_prog_load_params. Instead
of making it part of public API, we'll wait until the planned low-level
libbpf API improvements for BPF_PROG_LOAD and other typical bpf()
syscall APIs, at which point we'll have a public, probably OPTS-based,
way to fully specify BPF program load parameters, which will be used as
an interface for custom pre-load callbacks.
But this change itself is already a good first step to unify the BPF
program hanling logic even within the libbpf itself. As one example, all
the extra per-program type handling (sleepable bit, attach_btf_id
resolution, unsetting optional expected attach type) is now more obvious
and is gathered in one place.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Dave Marchevsky <davemarchevsky@fb.com>
Link: https://lore.kernel.org/bpf/20210928161946.2512801-6-andrii@kernel.org
When parsing legacy map definitions, libbpf would error out when
encountering an STT_SECTION symbol. This becomes a problem because some
versions of binutils will produce SECTION symbols for every section when
processing an ELF file, so BPF files run through 'strip' will end up with
such symbols, making libbpf refuse to load them.
There's not really any reason why erroring out is strictly necessary, so
change libbpf to just ignore SECTION symbols when parsing the ELF.
Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210927205810.715656-1-toke@redhat.com
Similarly to recently added legacy kprobe attach interface support
through tracefs, support attaching uprobes using the legacy interface if
host kernel doesn't support newer FD-based interface.
For uprobes event name consists of "libbpf_" prefix, PID, sanitized
binary path and offset within that binary. Structuraly the code is
aligned with kprobe logic refactoring in previous patch. struct
bpf_link_perf is re-used and all the same legacy_probe_name and
legacy_is_retprobe fields are used to ensure proper cleanup on
bpf_link__destroy().
Users should be aware, though, that on old kernels which don't support
FD-based interface for kprobe/uprobe attachment, if the application
crashes before bpf_link__destroy() is called, uprobe legacy
events will be left in tracefs. This is the same limitation as with
legacy kprobe interfaces.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210921210036.1545557-5-andrii@kernel.org
Refactor legacy kprobe handling code to follow the same logic as uprobe
legacy logic added in the next patchs:
- add append_to_file() helper that makes it simpler to work with
tracefs file-based interface for creating and deleting probes;
- move out probe/event name generation outside of the code that
adds/removes it, which simplifies bookkeeping significantly;
- change the probe name format to start with "libbpf_" prefix and
include offset within kernel function;
- switch 'unsigned long' to 'size_t' for specifying kprobe offsets,
which is consistent with how uprobes define that, simplifies
printf()-ing internally, and also avoids unnecessary complications on
architectures where sizeof(long) != sizeof(void *).
This patch also implicitly fixes the problem with invalid open() error
handling present in poke_kprobe_events(), which (the function) this
patch removes.
Fixes: ca304b40c20d ("libbpf: Introduce legacy kprobe events support")
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210921210036.1545557-4-andrii@kernel.org
This adds comments above functions in libbpf.h which document
their uses. These comments are of a format that doxygen and sphinx
can pick up and render. These are rendered by libbpf.readthedocs.org
These doc comments are for:
- bpf_object__find_map_by_name()
- bpf_map__fd()
- bpf_map__is_internal()
- libbpf_get_error()
- libbpf_num_possible_cpus()
Signed-off-by: Grant Seltzer <grantseltzer@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210918031457.36204-1-grantseltzer@gmail.com
The __bpf_printk convenience macro was using a 'char' fmt string holder
as it predates support for globals in libbpf. Move to more efficient
'static const char', but provide a fallback to the old way via
BPF_NO_GLOBAL_DATA so users on old kernels can still use the macro.
Signed-off-by: Dave Marchevsky <davemarchevsky@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210917182911.2426606-6-davemarchevsky@fb.com
Instead of being a thin wrapper which calls into bpf_trace_printk,
libbpf's bpf_printk convenience macro now chooses between
bpf_trace_printk and bpf_trace_vprintk. If the arg count (excluding
format string) is >3, use bpf_trace_vprintk, otherwise use the older
helper.
The motivation behind this added complexity - instead of migrating
entirely to bpf_trace_vprintk - is to maintain good developer experience
for users compiling against new libbpf but running on older kernels.
Users who are passing <=3 args to bpf_printk will see no change in their
bytecode.
__bpf_vprintk functions similarly to BPF_SEQ_PRINTF and BPF_SNPRINTF
macros elsewhere in the file - it allows use of bpf_trace_vprintk
without manual conversion of varargs to u64 array. Previous
implementation of bpf_printk macro is moved to __bpf_printk for use by
the new implementation.
This does change behavior of bpf_printk calls with >3 args in the "new
libbpf, old kernels" scenario. Before this patch, attempting to use 4
args to bpf_printk results in a compile-time error. After this patch,
using bpf_printk with 4 args results in a trace_vprintk helper call
being emitted and a load-time failure on older kernels.
Signed-off-by: Dave Marchevsky <davemarchevsky@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210917182911.2426606-5-davemarchevsky@fb.com
bpf_object_open_opts.attach_prog_fd makes a pretty strong assumption
that bpf_object contains either only single freplace BPF program or all
of BPF programs in BPF object are freplaces intended to replace
different subprograms of the same target BPF program. This seems both
a bit confusing, too assuming, and limiting.
We've had bpf_program__set_attach_target() API which allows more
fine-grained control over this, on a per-program level. As such, mark
open_opts.attach_prog_fd as deprecated starting from v0.7, so that we
have one more universal way of setting freplace targets. With previous
change to allow NULL attach_func_name argument, and especially combined
with BPF skeleton, arguable bpf_program__set_attach_target() is a more
convenient and explicit API as well.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20210916015836.1248906-7-andrii@kernel.org
Allow to use bpf_program__set_attach_target to only set target attach
program FD, while letting libbpf to use target attach function name from
SEC() definition. This might be useful for some scenarios where
bpf_object contains multiple related freplace BPF programs intended to
replace different sub-programs in target BPF program. In such case all
programs will have the same attach_prog_fd, but different
attach_func_name. It's convenient to specify such target function names
declaratively in SEC() definitions, but attach_prog_fd is a dynamic
runtime setting.
To simplify such scenario, allow bpf_program__set_attach_target() to
delay BTF ID resolution till the BPF program load time by providing NULL
attach_func_name. In that case the behavior will be similar to using
bpf_object_open_opts.attach_prog_fd (which is marked deprecated since
v0.7), but has the benefit of allowing more control by user in what is
attached to what. Such setup allows having BPF programs attached to
different target attach_prog_fd with target functions still declaratively
recorded in BPF source code in SEC() definitions.
Selftests changes in the next patch should make this more obvious.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20210916015836.1248906-5-andrii@kernel.org
Doing substring matches allows accidental new tests to be enabled,
when they are not supposed to be. E.g., whitelisting "xdp" allows new
"xdpwall" test on 5.5.0, which wasn't supposed to happen.
Cc: Yucong Sun <fallentree@fb.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
There is a problem in bpf-next tree which causes get_stack_raw_tp and
few other selftests to produce tons of kernel warnings, timing out and
failing CI test runs. Blacklist until bpf tree, which has a fix, is
merged into bpf-next.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
LLVM14 added support for a new C attribute ([1])
__attribute__((btf_tag("arbitrary_str")))
This attribute will be emitted to dwarf ([2]) and pahole
will convert it to BTF. Or for bpf target, this
attribute will be emitted to BTF directly ([3], [4]).
The attribute is intended to provide additional
information for
- struct/union type or struct/union member
- static/global variables
- static/global function or function parameter.
For linux kernel, the btf_tag can be applied
in various places to specify user pointer,
function pre- or post- condition, function
allow/deny in certain context, etc. Such information
will be encoded in vmlinux BTF and can be used
by verifier.
The btf_tag can also be applied to bpf programs
to help global verifiable functions, e.g.,
specifying preconditions, etc.
This patch added basic parsing and checking support
in kernel for new BTF_KIND_TAG kind.
[1] https://reviews.llvm.org/D106614
[2] https://reviews.llvm.org/D106621
[3] https://reviews.llvm.org/D106622
[4] https://reviews.llvm.org/D109560
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210914223015.245546-1-yhs@fb.com
Remove almost all the code that explicitly iterated BPF program section
definitions in favor of using find_sec_def(). The only remaining user of
section_defs is libbpf_get_type_names that has to iterate all of them to
construct its result.
Having one internal API entry point for section definitions will
simplify further refactorings around libbpf's program section
definitions parsing.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20210914014733.2768-5-andrii@kernel.org
Remove the need to explicitly pass bpf_sec_def for auto-attachable BPF
programs, as it is already recorded at bpf_object__open() time for all
recognized type of BPF programs. This further reduces number of explicit
calls to find_sec_def(), simplifying further refactorings.
No functional changes are done by this patch.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20210914014733.2768-4-andrii@kernel.org
Refactor bpf_object__open() sequencing to perform BPF program type
detection based on SEC() definitions before we get to relocations
collection. This allows to have more information about BPF program by
the time we get to, say, struct_ops relocation gathering. This,
subsequently, simplifies struct_ops logic and removes the need to
perform extra find_sec_def() resolution.
With this patch libbpf will require all struct_ops BPF programs to be
marked with SEC("struct_ops") or SEC("struct_ops/xxx") annotations.
Real-world applications are already doing that through something like
selftests's BPF_STRUCT_OPS() macro. This change streamlines libbpf's
internal handling of SEC() definitions and is in the sprit of
upcoming libbpf-1.0 section strictness changes ([0]).
[0] https://github.com/libbpf/libbpf/wiki/Libbpf:-the-road-to-v1.0#stricter-and-more-uniform-bpf-program-section-name-sec-handling
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20210914014733.2768-3-andrii@kernel.org
Allow kprobe tracepoint events creation through legacy interface, as the
kprobe dynamic PMUs support, used by default, was only created in v4.17.
Store legacy kprobe name in struct bpf_perf_link, instead of creating
a new "subclass" off of bpf_perf_link. This is ok as it's just two new
fields, which are also going to be reused for legacy uprobe support in
follow up patches.
Signed-off-by: Rafael David Tinoco <rafaeldtinoco@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210912064844.3181742-1-rafaeldtinoco@gmail.com
Turn previously auto-generated libbpf_version.h header into a normal
header file. This prevents various tricky Makefile integration issues,
simplifies the overall build process, but also allows to further extend
it with some more versioning-related APIs in the future.
To prevent accidental out-of-sync versions as defined by libbpf.map and
libbpf_version.h, Makefile checks their consistency at build time.
Simultaneously with this change bump libbpf.map to v0.6.
Also undo adding libbpf's output directory into include path for
kernel/bpf/preload, bpftool, and resolve_btfids, which is not necessary
because libbpf_version.h is just a normal header like any other.
Fixes: 0b46b7550560 ("libbpf: Add LIBBPF_DEPRECATED_SINCE macro for scheduling API deprecations")
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210913222309.3220849-1-andrii@kernel.org
Introduce bpf_get_branch_snapshot(), which allows tracing pogram to get
branch trace from hardware (e.g. Intel LBR). To use the feature, the
user need to create perf_event with proper branch_record filtering
on each cpu, and then calls bpf_get_branch_snapshot in the bpf function.
On Intel CPUs, VLBR event (raw event 0x1b00) can be use for this.
Signed-off-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210910183352.3151445-3-songliubraving@fb.com
BPF programs may want to know hardware timestamps if NIC supports
such timestamping.
Expose this data as hwtstamp field of __sk_buff the same way as
gso_segs/gso_size. This field could be accessed from the same
programs as tstamp field, but it's read-only field. Explicit test
to deny access to padding data is added to bpf_skb_is_valid_access.
Also update BPF_PROG_TEST_RUN tests of the feature.
Signed-off-by: Vadim Fedorenko <vfedorenko@novek.ru>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20210909220409.8804-2-vfedorenko@novek.ru
Introduce a macro LIBBPF_DEPRECATED_SINCE(major, minor, message) to prepare
the deprecation of two API functions. This macro marks functions as deprecated
when libbpf's version reaches the values passed as an argument.
As part of this change libbpf_version.h header is added with recorded major
(LIBBPF_MAJOR_VERSION) and minor (LIBBPF_MINOR_VERSION) libbpf version macros.
They are now part of libbpf public API and can be relied upon by user code.
libbpf_version.h is installed system-wide along other libbpf public headers.
Due to this new build-time auto-generated header, in-kernel applications
relying on libbpf (resolve_btfids, bpftool, bpf_preload) are updated to
include libbpf's output directory as part of a list of include search paths.
Better fix would be to use libbpf's make_install target to install public API
headers, but that clean up is left out as a future improvement. The build
changes were tested by building kernel (with KBUILD_OUTPUT and O= specified
explicitly), bpftool, libbpf, selftests/bpf, and resolve_btfids builds. No
problems were detected.
Note that because of the constraints of the C preprocessor we have to write
a few lines of macro magic for each version used to prepare deprecation (0.6
for now).
Also, use LIBBPF_DEPRECATED_SINCE() to schedule deprecation of
btf__get_from_id() and btf__load(), which are replaced by
btf__load_from_kernel_by_id() and btf__load_into_kernel(), respectively,
starting from future libbpf v0.6. This is part of libbpf 1.0 effort ([0]).
[0] Closes: https://github.com/libbpf/libbpf/issues/278
Co-developed-by: Quentin Monnet <quentin@isovalent.com>
Co-developed-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Quentin Monnet <quentin@isovalent.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20210908213226.1871016-1-andrii@kernel.org
The kernel provides a "/proc/sys/net/ipv6/conf/<iface>/mtu"
file, which can temporarily record the mtu value of the last
received RA message when the RA mtu value is lower than the
interface mtu, but this proc has following limitations:
(1) when the interface mtu (/sys/class/net/<iface>/mtu) is
updeated, mtu6 (/proc/sys/net/ipv6/conf/<iface>/mtu) will
be updated to the value of interface mtu;
(2) mtu6 (/proc/sys/net/ipv6/conf/<iface>/mtu) only affect
ipv6 connection, and not affect ipv4.
Therefore, when the mtu option is carried in the RA message,
there will be a problem that the user sometimes cannot obtain
RA mtu value correctly by reading mtu6.
After this patch set, if a RA message carries the mtu option,
you can send a netlink msg which nlmsg_type is RTM_GETLINK,
and then by parsing the attribute of IFLA_INET6_RA_MTU to
get the mtu value carried in the RA message received on the
inet6 device. In addition, you can also get a link notification
when ra_mtu is updated so it doesn't have to poll.
In this way, if the MTU values that the device receives from
the network in the PCO IPv4 and the RA IPv6 procedures are
different, the user can obtain the correct ipv6 ra_mtu value
and compare the value of ra_mtu and ipv4 mtu, then the device
can use the lower MTU value for both IPv4 and IPv6.
Signed-off-by: Rocco Yue <rocco.yue@mediatek.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Link: https://lore.kernel.org/r/20210827150412.9267-1-rocco.yue@mediatek.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Use this list of enabled tests as a whitelist, so that we don't have to
keep updating BLACKLIST-5.5.0 anymore. I'll keep BLACKLIST-5.5.0 for
now, because it serves as a nice historic log of which tests depend on
which kernels.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
This change was necessary to enforce the implied contract
that bpf_object_skeleton->data should not be mutated. The data
will be cast to `void *` during assignment to handle the case
where a user is compiling with older libbpf headers to avoid
a compiler warning of `const void *` data being cast to `void *`
Signed-off-by: Matt Smith <alastorze@fb.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210901194439.3853238-2-alastorze@fb.com
If libbpf encounters an ELF file that has been stripped of its symbol
table, it will crash in bpf_object__add_programs() when trying to
dereference the obj->efile.symbols pointer.
Fix this by erroring out of bpf_object__elf_collect() if it is not able
able to find the symbol table.
v2:
- Move check into bpf_object__elf_collect() and add nice error message
Fixes: 6245947c1b3c ("libbpf: Allow gaps in BPF program sections to support overriden weak functions")
Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210901114812.204720-1-toke@redhat.com
The motivation behind this helper is to access userspace pt_regs in a
kprobe handler.
uprobe's ctx is the userspace pt_regs. kprobe's ctx is the kernelspace
pt_regs. bpf_task_pt_regs() allows accessing userspace pt_regs in a
kprobe handler. The final case (kernelspace pt_regs in uprobe) is
pretty rare (usermode helper) so I think that can be solved later if
necessary.
More concretely, this helper is useful in doing BPF-based DWARF stack
unwinding. Currently the kernel can only do framepointer based stack
unwinds for userspace code. This is because the DWARF state machines are
too fragile to be computed in kernelspace [0]. The idea behind
DWARF-based stack unwinds w/ BPF is to copy a chunk of the userspace
stack (while in prog context) and send it up to userspace for unwinding
(probably with libunwind) [1]. This would effectively enable profiling
applications with -fomit-frame-pointer using kprobes and uprobes.
[0]: https://lkml.org/lkml/2012/2/10/356
[1]: https://github.com/danobi/bpf-dwarf-walk
Signed-off-by: Daniel Xu <dxu@dxuuu.xyz>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/e2718ced2d51ef4268590ab8562962438ab82815.1629772842.git.dxu@dxuuu.xyz
Add an enum (cgroup_bpf_attach_type) containing only valid cgroup_bpf
attach types and a function to map bpf_attach_type values to the new
enum. Inspired by netns_bpf_attach_type.
Then, migrate cgroup_bpf to use cgroup_bpf_attach_type wherever
possible. Functionality is unchanged as attach_type_to_prog_type
switches in bpf/syscall.c were preventing non-cgroup programs from
making use of the invalid cgroup_bpf array slots.
As a result struct cgroup_bpf uses 504 fewer bytes relative to when its
arrays were sized using MAX_BPF_ATTACH_TYPE.
bpf_cgroup_storage is notably not migrated as struct
bpf_cgroup_storage_key is part of uapi and contains a bpf_attach_type
member which is not meant to be opaque. Similarly, bpf_cgroup_link
continues to report its bpf_attach_type member to userspace via fdinfo
and bpf_link_info.
To ease disambiguation, bpf_attach_type variables are renamed from
'type' to 'atype' when changed to cgroup_bpf_attach_type.
Signed-off-by: Dave Marchevsky <davemarchevsky@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210819092420.1984861-2-davemarchevsky@fb.com
This patch renames a documentation libbpf.rst to index.rst. In order
for readthedocs.org to pick this file up and properly build the
documentation site.
It also changes the title type of the ABI subsection in the
naming convention doc. This is so that readthedocs.org doesn't treat this
section as a separate document.
Signed-off-by: Grant Seltzer <grantseltzer@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210818151313.49992-1-grantseltzer@gmail.com
When attaching to uprobes through perf subsystem, it's possible to specify
offset of a so-called USDT semaphore, which is just a reference counted u16,
used by kernel to keep track of how many tracers are attached to a given
location. Support for this feature was added in [0], so just wire this through
uprobe_opts. This is important to enable implementing USDT attachment and
tracing through libbpf's bpf_program__attach_uprobe_opts() API.
[0] a6ca88b241d5 ("trace_uprobe: support reference counter in fd-based uprobe")
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20210815070609.987780-16-andrii@kernel.org
Wire through bpf_cookie for all attach APIs that use perf_event_open under the
hood:
- for kprobes, extend existing bpf_kprobe_opts with bpf_cookie field;
- for perf_event, uprobe, and tracepoint APIs, add their _opts variants and
pass bpf_cookie through opts.
For kernel that don't support BPF_LINK_CREATE for perf_events, and thus
bpf_cookie is not supported either, return error and log warning for user.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20210815070609.987780-12-andrii@kernel.org
Add ability to specify bpf_cookie value when creating BPF perf link with
bpf_link_create() low-level API.
Given BPF_LINK_CREATE command is growing and keeps getting new fields that are
specific to the type of BPF_LINK, extend libbpf side of bpf_link_create() API
and corresponding OPTS struct to accomodate such changes. Add extra checks to
prevent using incompatible/unexpected combinations of fields.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20210815070609.987780-11-andrii@kernel.org
Detect kernel support for BPF perf link and prefer it when attaching to
perf_event, tracepoint, kprobe/uprobe. Underlying perf_event FD will be kept
open until BPF link is destroyed, at which point both perf_event FD and BPF
link FD will be closed.
This preserves current behavior in which perf_event FD is open for the
duration of bpf_link's lifetime and user is able to "disconnect" bpf_link from
underlying FD (with bpf_link__disconnect()), so that bpf_link__destroy()
doesn't close underlying perf_event FD.When BPF perf link is used, disconnect
will keep both perf_event and bpf_link FDs open, so it will be up to
(advanced) user to close them. This approach is demonstrated in bpf_cookie.c
selftests, added in this patch set.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20210815070609.987780-10-andrii@kernel.org
bpf_link->destroy() isn't used by any code, so remove it. Instead, add ability
to override deallocation procedure, with default doing plain free(link). This
is necessary for cases when we want to "subclass" struct bpf_link to keep
extra information, as is the case in the next patch adding struct
bpf_link_perf.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20210815070609.987780-9-andrii@kernel.org
Add new BPF helper, bpf_get_attach_cookie(), which can be used by BPF programs
to get access to a user-provided bpf_cookie value, specified during BPF
program attachment (BPF link creation) time.
Naming is hard, though. With the concept being named "BPF cookie", I've
considered calling the helper:
- bpf_get_cookie() -- seems too unspecific and easily mistaken with socket
cookie;
- bpf_get_bpf_cookie() -- too much tautology;
- bpf_get_link_cookie() -- would be ok, but while we create a BPF link to
attach BPF program to BPF hook, it's still an "attachment" and the
bpf_cookie is associated with BPF program attachment to a hook, not a BPF
link itself. Technically, we could support bpf_cookie with old-style
cgroup programs.So I ultimately rejected it in favor of
bpf_get_attach_cookie().
Currently all perf_event-backed BPF program types support
bpf_get_attach_cookie() helper. Follow-up patches will add support for
fentry/fexit programs as well.
While at it, mark bpf_tracing_func_proto() as static to make it obvious that
it's only used from within the kernel/trace/bpf_trace.c.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20210815070609.987780-7-andrii@kernel.org
Add ability for users to specify custom u64 value (bpf_cookie) when creating
BPF link for perf_event-backed BPF programs (kprobe/uprobe, perf_event,
tracepoints).
This is useful for cases when the same BPF program is used for attaching and
processing invocation of different tracepoints/kprobes/uprobes in a generic
fashion, but such that each invocation is distinguished from each other (e.g.,
BPF program can look up additional information associated with a specific
kernel function without having to rely on function IP lookups). This enables
new use cases to be implemented simply and efficiently that previously were
possible only through code generation (and thus multiple instances of almost
identical BPF program) or compilation at runtime (BCC-style) on target hosts
(even more expensive resource-wise). For uprobes it is not even possible in
some cases to know function IP before hand (e.g., when attaching to shared
library without PID filtering, in which case base load address is not known
for a library).
This is done by storing u64 bpf_cookie in struct bpf_prog_array_item,
corresponding to each attached and run BPF program. Given cgroup BPF programs
already use two 8-byte pointers for their needs and cgroup BPF programs don't
have (yet?) support for bpf_cookie, reuse that space through union of
cgroup_storage and new bpf_cookie field.
Make it available to kprobe/tracepoint BPF programs through bpf_trace_run_ctx.
This is set by BPF_PROG_RUN_ARRAY, used by kprobe/uprobe/tracepoint BPF
program execution code, which luckily is now also split from
BPF_PROG_RUN_ARRAY_CG. This run context will be utilized by a new BPF helper
giving access to this user-provided cookie value from inside a BPF program.
Generic perf_event BPF programs will access this value from perf_event itself
through passed in BPF program context.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Yonghong Song <yhs@fb.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/bpf/20210815070609.987780-6-andrii@kernel.org
Introduce a new type of BPF link - BPF perf link. This brings perf_event-based
BPF program attachments (perf_event, tracepoints, kprobes, and uprobes) into
the common BPF link infrastructure, allowing to list all active perf_event
based attachments, auto-detaching BPF program from perf_event when link's FD
is closed, get generic BPF link fdinfo/get_info functionality.
BPF_LINK_CREATE command expects perf_event's FD as target_fd. No extra flags
are currently supported.
Force-detaching and atomic BPF program updates are not yet implemented, but
with perf_event-based BPF links we now have common framework for this without
the need to extend ioctl()-based perf_event interface.
One interesting consideration is a new value for bpf_attach_type, which
BPF_LINK_CREATE command expects. Generally, it's either 1-to-1 mapping from
bpf_attach_type to bpf_prog_type, or many-to-1 mapping from a subset of
bpf_attach_types to one bpf_prog_type (e.g., see BPF_PROG_TYPE_SK_SKB or
BPF_PROG_TYPE_CGROUP_SOCK). In this case, though, we have three different
program types (KPROBE, TRACEPOINT, PERF_EVENT) using the same perf_event-based
mechanism, so it's many bpf_prog_types to one bpf_attach_type. I chose to
define a single BPF_PERF_EVENT attach type for all of them and adjust
link_create()'s logic for checking correspondence between attach type and
program type.
The alternative would be to define three new attach types (e.g., BPF_KPROBE,
BPF_TRACEPOINT, and BPF_PERF_EVENT), but that seemed like unnecessary overkill
and BPF_KPROBE will cause naming conflicts with BPF_KPROBE() macro, defined by
libbpf. I chose to not do this to avoid unnecessary proliferation of
bpf_attach_type enum values and not have to deal with naming conflicts.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Yonghong Song <yhs@fb.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/bpf/20210815070609.987780-5-andrii@kernel.org
Currently weak typeless ksyms have default value zero, when they don't
exist in the kernel. However, weak typed ksyms are rejected by libbpf
if they can not be resolved. This means that if a bpf object contains
the declaration of a nonexistent weak typed ksym, it will be rejected
even if there is no program that references the symbol.
Nonexistent weak typed ksyms can also default to zero just like
typeless ones. This allows programs that access weak typed ksyms to be
accepted by verifier, if the accesses are guarded. For example,
extern const int bpf_link_fops3 __ksym __weak;
/* then in BPF program */
if (&bpf_link_fops3) {
/* use bpf_link_fops3 */
}
If actual use of nonexistent typed ksym is not guarded properly,
verifier would see that register is not PTR_TO_BTF_ID and wouldn't
allow to use it for direct memory reads or passing it to BPF helpers.
Signed-off-by: Hao Luo <haoluo@google.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210812003819.2439037-1-haoluo@google.com
Use "code-block: none" instead of "c" for non-C-language code blocks.
Removes these warnings:
lnx-514-rc4/Documentation/bpf/libbpf/libbpf_naming_convention.rst:111: WARNING: Could not lex literal_block as "c". Highlighting skipped.
lnx-514-rc4/Documentation/bpf/libbpf/libbpf_naming_convention.rst:124: WARNING: Could not lex literal_block as "c". Highlighting skipped.
Fixes: f42cfb469f9b ("bpf: Add documentation for libbpf including API autogen")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20210802015037.787-1-rdunlap@infradead.org
Add an option lacp_active, which is similar with team's runner.active.
This option specifies whether to send LACPDU frames periodically. If set
on, the LACPDU frames are sent along with the configured lacp_rate
setting. If set off, the LACPDU frames acts as "speak when spoken to".
Note, the LACPDU state frames still will be sent when init or unbind port.
v2: remove module parameter
Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Kernel docs from Documentation/bpf/libbpf go straight to docs/ under libbpf.
Also ignore libbpf-only parts of docs subdir.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
This adds documentation files, including ones for autogenerating API
documentation based on code comments in the source code that's pulled
in via the mirror.
Signed-off-by: Grant Seltzer <grantseltzer@gmail.com>
When new eBPF program, map, or attach types are added to the kernel,
bpftool needs to be updated in order to support the related features.
These updates should add the new types to the code itself, but also to
the help messages, documentation, and bash completion. Given that it is
easy to omit one of those, a script has been created to attempt to
validate that all parts have been consistently updated.
This new script for bpftool is hosted in the kernel repository, amongst
the BPF selftests. But it is not called from the Makefile, and not run
along with the other selftests. If it was, all patches updating the BPF
UAPI would require the relevant changes in bpftool at the same time, _in
the same patches_, which is not desirable.
To ensure that bpftool's parts remain in sync, let's run this script
from the CI. This patch adds a new section to the run.sh script, focused
on bpftool, and calling the new test_bpftool_synctypes.py.
Makefile needs relo_core object added to objects list to avoid static
linking errors when doing static compilation:
/bin/ld: .../libbpf.a(libbpf.o): in function `bpf_core_apply_relo':
.../libbpf/src/libbpf.c:5134: undefined reference to `bpf_core_apply_relo_insn'
Signed-off-by: Rafael David Tinoco <rafaeldtinoco@gmail.com>
Only keep stderr output in case of errors for kernel and selftests builds.
Having a multi-thousand-line output isn't useful and slows down Github
Actions' log view UI.
Also quiet down wget's "progress bar" output. While at the same time see some
totals from tar, just for the fun of it.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Makefile needs relo_core object added to objects list to avoid static
linking errors when doing static compilation:
/bin/ld: .../libbpf.a(libbpf.o): in function `bpf_core_apply_relo':
.../libbpf/src/libbpf.c:5134: undefined reference to `bpf_core_apply_relo_insn'
Signed-off-by: Rafael David Tinoco <rafaeldtinoco@gmail.com>
Only keep stderr output in case of errors for kernel and selftests builds.
Having a multi-thousand-line output isn't useful and slows down Github
Actions' log view UI.
Also quiet down wget's "progress bar" output. While at the same time see some
totals from tar, just for the fun of it.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Before this patch, btf_new() was liable to close an arbitrary FD 0 if
BTF parsing failed. This was because:
* btf->fd was initialized to 0 through the calloc()
* btf__free() (in the `done` label) closed any FDs >= 0
* btf->fd is left at 0 if parsing fails
This issue was discovered on a system using libbpf v0.3 (without
BTF_KIND_FLOAT support) but with a kernel that had BTF_KIND_FLOAT types
in BTF. Thus, parsing fails.
While this patch technically doesn't fix any issues b/c upstream libbpf
has BTF_KIND_FLOAT support, it'll help prevent issues in the future if
more BTF types are added. It also allow the fix to be backported to
older libbpf's.
Fixes: 3289959b97ca ("libbpf: Support BTF loading and raw data output in both endianness")
Signed-off-by: Daniel Xu <dxu@dxuuu.xyz>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/5969bb991adedb03c6ae93e051fd2a00d293cf25.1627513670.git.dxu@dxuuu.xyz
Add two new APIs: btf__load_vmlinux_btf and btf__load_module_btf.
btf__load_vmlinux_btf is just an alias to the existing API named
libbpf_find_kernel_btf, rename to be more precisely and consistent
with existing BTF APIs. btf__load_module_btf can be used to load
module BTF, add it for completeness. These two APIs are useful for
implementing tracing tools and introspection tools. This is part
of the effort towards libbpf 1.0 ([0]).
[0] Closes: https://github.com/libbpf/libbpf/issues/280
Signed-off-by: Hengqi Chen <hengqi.chen@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210730114012.494408-1-hengqi.chen@gmail.com
Variable "err" is initialised to -EINVAL so that this error code is
returned when something goes wrong in libbpf_find_prog_btf_id().
However, a recent change in the function made use of the variable in
such a way that it is set to 0 if retrieving linear information on the
program is successful, and this 0 value remains if we error out on
failures at later stages.
Let's fix this by setting err to -EINVAL later in the function.
Fixes: e9fc3ce99b34 ("libbpf: Streamline error reporting for high-level APIs")
Signed-off-by: Quentin Monnet <quentin@isovalent.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210729162028.29512-2-quentin@isovalent.com
When loading in parallel multiple programs which use the same to-be
pinned map, it is possible that two instances of the loader will call
bpf_object__create_maps() at the same time. If the map doesn't exist
when both instances call bpf_object__reuse_map(), then one of the
instances will fail with EEXIST when calling bpf_map__pin().
Fix the race by retrying reusing a map if bpf_map__pin() returns
EEXIST. The fix is similar to the one in iproute2: e4c4685fd6e4 ("bpf:
Fix race condition with map pinning").
Before retrying the pinning, we don't do any special cleaning of an
internal map state. The closer code inspection revealed that it's not
required:
- bpf_object__create_map(): map->inner_map is destroyed after a
successful call, map->fd is closed if pinning fails.
- bpf_object__populate_internal_map(): created map elements is
destroyed upon close(map->fd).
- init_map_slots(): slots are freed after their initialization.
Signed-off-by: Martynas Pumputis <m@lambda.lt>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210726152001.34845-1-m@lambda.lt
github action grouping is broken because we were outputing "::endgroup" where
it needs "::endgroup::". This patch also added some addtional grouping around
contianer setup phase, making output easier to read.
When retrieving the enum value associated with typed data during
"is data zero?" checking in btf_dump_type_data_check_zero(), the
return value of btf_dump_get_enum_value() is not passed to the caller
if the function returns a non-zero (error) value. Currently, 0
is returned if the function returns an error. We should instead
propagate the error to the caller.
Signed-off-by: Alan Maguire <alan.maguire@oracle.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/1626770993-11073-4-git-send-email-alan.maguire@oracle.com
__int128 is not supported for some 32-bit platforms (arm and i386).
__int128 was used in carrying out computations on bitfields which
aid display, but the same calculations could be done with __u64
with the small effect of not supporting 128-bit bitfields.
With these changes, a big-endian issue with casting 128-bit integers
to 64-bit for enum bitfields is solved also, as we now use 64-bit
integers for bitfield calculations.
Reported-by: Naresh Kamboju <naresh.kamboju@linaro.org>
Reported-by: Linux Kernel Functional Testing <lkft@linaro.org>
Signed-off-by: Alan Maguire <alan.maguire@oracle.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/1626770993-11073-2-git-send-email-alan.maguire@oracle.com
commit a82a66e ("Extend build and add install rules to Makefile") adds
special handling for LIBSUBDIR on x86_64. Expand this to all
architectures with 64 in name which suggests a 32bit variant exists, and
s390x which is 64bit extension of s390.
Fixes: #337
Fixes: a82a66e ("Extend build and add install rules to Makefile")
Signed-off-by: Michal Suchanek <msuchanek@suse.de>
If creating an outer map of a BTF-defined map-in-map fails (via
bpf_object__create_map()), then the previously created its inner map
won't be destroyed.
Fix this by ensuring that the destroy routines are not bypassed in the
case of a failure.
Fixes: 646f02ffdd49c ("libbpf: Add BTF-defined map-in-map support")
Reported-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Martynas Pumputis <m@lambda.lt>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20210719173838.423148-2-m@lambda.lt
__s64 can be defined as either long or long long, depending on the
architecture. On ppc64le it's defined as long, giving this error:
In file included from btf_dump.c:22:
btf_dump.c: In function 'btf_dump_type_data_check_overflow':
libbpf_internal.h:111:22: error: format '%lld' expects argument of
type 'long long int', but argument 3 has type '__s64' {aka 'long int'}
[-Werror=format=]
111 | libbpf_print(level, "libbpf: " fmt, ##__VA_ARGS__); \
| ^~~~~~~~~~
libbpf_internal.h:114:27: note: in expansion of macro '__pr'
114 | #define pr_warn(fmt, ...) __pr(LIBBPF_WARN, fmt, ##__VA_ARGS__)
| ^~~~
btf_dump.c:1992:3: note: in expansion of macro 'pr_warn'
1992 | pr_warn("unexpected size [%lld] for id [%u]\n",
| ^~~~~~~
btf_dump.c:1992:32: note: format string is defined here
1992 | pr_warn("unexpected size [%lld] for id [%u]\n",
| ~~~^
| |
| long long int
| %ld
Cast to size_t and use %zu instead.
Reported-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alan Maguire <alan.maguire@oracle.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/1626475617-25984-3-git-send-email-alan.maguire@oracle.com
If data is packed, data structures can store it outside of usual
boundaries. For example a 4-byte int can be stored on a unaligned
boundary in a case like this:
struct s {
char f1;
int f2;
} __attribute((packed));
...the int is stored at an offset of one byte. Some platforms have
problems dereferencing data that is not aligned with its size, and
code exists to handle most cases of this for BTF typed data display.
However pointer display was missed, and a simple function to test if
"ptr_is_aligned(data, data_sz)" would help clarify this code.
Suggested-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alan Maguire <alan.maguire@oracle.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/1626475617-25984-2-git-send-email-alan.maguire@oracle.com
Manjaro is a popular and friendly Arch based distro. Recently they also enabled the BTF support: https://forum.manjaro.org/t/co-re-support-in-kernel/46134/19
I can confirm that:
[user@pc ~]$ uname -a
Linux pc 5.12.16-1-MANJARO #1 SMP PREEMPT Sun Jul 11 13:23:34 UTC 2021 x86_64 GNU/Linux
[user@pc ~]$ ls -la /sys/kernel/btf/vmlinux
-r--r--r-- 1 root root 4226769 jul 17 15.27 /sys/kernel/btf/vmlinux
Add few new selftests to blacklist. They can't succeed on 5.5.
Also temporarily remove btf_dump for 4.9 due to newly added data dumping
subtests.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Temporary disable tc_bpf tests that seem to have regressed.
Temporary and artificially bump pahole version from 1.21 to 1.22 to get
per-CPU BTF data built.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
We used to have it disabled for GCC8, but now GCC10 is false-report same
warnings, so disable stringop-truncation warnigs for GCC10 as well.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
This is necessary to make runqslower compile with task->__state field on old
kernels, for which we don't have an actual vmlinux.h.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Add a BTF dumper for typed data, so that the user can dump a typed
version of the data provided.
The API is
int btf_dump__dump_type_data(struct btf_dump *d, __u32 id,
void *data, size_t data_sz,
const struct btf_dump_type_data_opts *opts);
...where the id is the BTF id of the data pointed to by the "void *"
argument; for example the BTF id of "struct sk_buff" for a
"struct skb *" data pointer. Options supported are
- a starting indent level (indent_lvl)
- a user-specified indent string which will be printed once per
indent level; if NULL, tab is chosen but any string <= 32 chars
can be provided.
- a set of boolean options to control dump display, similar to those
used for BPF helper bpf_snprintf_btf(). Options are
- compact : omit newlines and other indentation
- skip_names: omit member names
- emit_zeroes: show zero-value members
Default output format is identical to that dumped by bpf_snprintf_btf(),
for example a "struct sk_buff" representation would look like this:
struct sk_buff){
(union){
(struct){
.next = (struct sk_buff *)0xffffffffffffffff,
.prev = (struct sk_buff *)0xffffffffffffffff,
(union){
.dev = (struct net_device *)0xffffffffffffffff,
.dev_scratch = (long unsigned int)18446744073709551615,
},
},
...
If the data structure is larger than the *data_sz*
number of bytes that are available in *data*, as much
of the data as possible will be dumped and -E2BIG will
be returned. This is useful as tracers will sometimes
not be able to capture all of the data associated with
a type; for example a "struct task_struct" is ~16k.
Being able to specify that only a subset is available is
important for such cases. On success, the amount of data
dumped is returned.
Signed-off-by: Alan Maguire <alan.maguire@oracle.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/1626362126-27775-2-git-send-email-alan.maguire@oracle.com
kprobes can be placed on most instructions in a function, not
just entry, and ftrace and bpftrace support the function+offset
notification for probe placement. Adding parsing of func_name
into func+offset to bpf_program__attach_kprobe() allows the
user to specify
SEC("kprobe/bpf_fentry_test5+0x6")
...for example, and the offset can be passed to perf_event_open_probe()
to support kprobe attachment.
Signed-off-by: Alan Maguire <alan.maguire@oracle.com>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210714094400.396467-8-jolsa@kernel.org
Adding bpf_program__attach_kprobe_opts that does the same
as bpf_program__attach_kprobe, but takes opts argument.
Currently opts struct holds just retprobe bool, but we will
add new field in following patch.
The function is not exported, so there's no need to add
size to the struct bpf_program_attach_kprobe_opts for now.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210714094400.396467-7-jolsa@kernel.org
Adding bpf_get_func_ip helper for BPF_PROG_TYPE_KPROBE programs,
so it's now possible to call bpf_get_func_ip from both kprobe and
kretprobe programs.
Taking the caller's address from 'struct kprobe::addr', which is
defined for both kprobe and kretprobe.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>
Link: https://lore.kernel.org/bpf/20210714094400.396467-5-jolsa@kernel.org
Adding bpf_get_func_ip helper for BPF_PROG_TYPE_TRACING programs,
specifically for all trampoline attach types.
The trampoline's caller IP address is stored in (ctx - 8) address.
so there's no reason to actually call the helper, but rather fixup
the call instruction and return [ctx - 8] value directly.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210714094400.396467-4-jolsa@kernel.org
Introduce 'struct bpf_timer { __u64 :64; __u64 :64; };' that can be embedded
in hash/array/lru maps as a regular field and helpers to operate on it:
// Initialize the timer.
// First 4 bits of 'flags' specify clockid.
// Only CLOCK_MONOTONIC, CLOCK_REALTIME, CLOCK_BOOTTIME are allowed.
long bpf_timer_init(struct bpf_timer *timer, struct bpf_map *map, int flags);
// Configure the timer to call 'callback_fn' static function.
long bpf_timer_set_callback(struct bpf_timer *timer, void *callback_fn);
// Arm the timer to expire 'nsec' nanoseconds from the current time.
long bpf_timer_start(struct bpf_timer *timer, u64 nsec, u64 flags);
// Cancel the timer and wait for callback_fn to finish if it was running.
long bpf_timer_cancel(struct bpf_timer *timer);
Here is how BPF program might look like:
struct map_elem {
int counter;
struct bpf_timer timer;
};
struct {
__uint(type, BPF_MAP_TYPE_HASH);
__uint(max_entries, 1000);
__type(key, int);
__type(value, struct map_elem);
} hmap SEC(".maps");
static int timer_cb(void *map, int *key, struct map_elem *val);
/* val points to particular map element that contains bpf_timer. */
SEC("fentry/bpf_fentry_test1")
int BPF_PROG(test1, int a)
{
struct map_elem *val;
int key = 0;
val = bpf_map_lookup_elem(&hmap, &key);
if (val) {
bpf_timer_init(&val->timer, &hmap, CLOCK_REALTIME);
bpf_timer_set_callback(&val->timer, timer_cb);
bpf_timer_start(&val->timer, 1000 /* call timer_cb2 in 1 usec */, 0);
}
}
This patch adds helper implementations that rely on hrtimers
to call bpf functions as timers expire.
The following patches add necessary safety checks.
Only programs with CAP_BPF are allowed to use bpf_timer.
The amount of timers used by the program is constrained by
the memcg recorded at map creation time.
The bpf_timer_init() helper needs explicit 'map' argument because inner maps
are dynamic and not known at load time. While the bpf_timer_set_callback() is
receiving hidden 'aux->prog' argument supplied by the verifier.
The prog pointer is needed to do refcnting of bpf program to make sure that
program doesn't get freed while the timer is armed. This approach relies on
"user refcnt" scheme used in prog_array that stores bpf programs for
bpf_tail_call. The bpf_timer_set_callback() will increment the prog refcnt which is
paired with bpf_timer_cancel() that will drop the prog refcnt. The
ops->map_release_uref is responsible for cancelling the timers and dropping
prog refcnt when user space reference to a map reaches zero.
This uref approach is done to make sure that Ctrl-C of user space process will
not leave timers running forever unless the user space explicitly pinned a map
that contained timers in bpffs.
bpf_timer_init() and bpf_timer_set_callback() will return -EPERM if map doesn't
have user references (is not held by open file descriptor from user space and
not pinned in bpffs).
The bpf_map_delete_elem() and bpf_map_update_elem() operations cancel
and free the timer if given map element had it allocated.
"bpftool map update" command can be used to cancel timers.
The 'struct bpf_timer' is explicitly __attribute__((aligned(8))) because
'__u64 :64' has 1 byte alignment of 8 byte padding.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/bpf/20210715005417.78572-4-alexei.starovoitov@gmail.com
When loading a BPF program with a pinned map, the loader checks whether
the pinned map can be reused, i.e. their properties match. To derive
such of the pinned map, the loader invokes BPF_OBJ_GET_INFO_BY_FD and
then does the comparison.
Unfortunately, on < 4.12 kernels the BPF_OBJ_GET_INFO_BY_FD is not
available, so loading the program fails with the following error:
libbpf: failed to get map info for map FD 5: Invalid argument
libbpf: couldn't reuse pinned map at
'/sys/fs/bpf/tc/globals/cilium_call_policy': parameter
mismatch"
libbpf: map 'cilium_call_policy': error reusing pinned map
libbpf: map 'cilium_call_policy': failed to create:
Invalid argument(-22)
libbpf: failed to load object 'bpf_overlay.o'
To fix this, fallback to derivation of the map properties via
/proc/$PID/fdinfo/$MAP_FD if BPF_OBJ_GET_INFO_BY_FD fails with EINVAL,
which can be used as an indicator that the kernel doesn't support
the latter.
Signed-off-by: Martynas Pumputis <m@lambda.lt>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20210712125552.58705-1-m@lambda.lt
The update to streamline libbpf error reporting intended to change all
functions to return the errno as a negative return value if
LIBBPF_STRICT_DIRECT_ERRS is set. However, if the flag is *not* set, the
return value changes for the two functions that were already returning a
negative errno unconditionally: bpf_link__unpin() and perf_buffer__poll().
This is a user-visible API change that breaks applications; so let's revert
these two functions back to unconditionally returning a negative errno
value.
Fixes: e9fc3ce99b34 ("libbpf: Streamline error reporting for high-level APIs")
Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210706122355.236082-1-toke@redhat.com
Netlink helpers I added in 8bbb77b7c7a2 ("libbpf: Add various netlink
helpers") used char * casts everywhere, and there were a few more that
existed from before.
Convert all of them to void * cast, as it is treated equivalently by
clang/gcc for the purposes of pointer arithmetic and to follow the
convention elsewhere in the kernel/libbpf.
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20210619041454.417577-2-memxor@gmail.com
Coverity complains about OOB writes to nlmsghdr. There is no OOB as we
write to the trailing buffer, but static analyzers and compilers may
rightfully be confused as the nlmsghdr pointer has subobject provenance
(and hence subobject bounds).
Fix this by using an explicit request structure containing the nlmsghdr,
struct tcmsg/ifinfomsg, and attribute buffer.
Also switch nh_tail (renamed to req_tail) to cast req * to char * so
that it can be understood as arithmetic on pointer to the representation
array (hence having same bound as request structure), which should
further appease analyzers.
As a bonus, callers don't have to pass sizeof(req) all the time now, as
size is implicitly obtained using the pointer. While at it, also reduce
the size of attribute buffer to 128 bytes (132 for ifinfomsg using
functions due to the padding).
Summary of problem:
Even though C standard allows interconvertibility of pointer to first
member and pointer to struct, for the purposes of alias analysis it
would still consider the first as having pointer value "pointer to T"
where T is type of first member hence having subobject bounds,
allowing analyzers within reason to complain when object is accessed
beyond the size of pointed to object.
The only exception to this rule may be when a char * is formed to a
member subobject. It is not possible for the compiler to be able to
tell the intent of the programmer that it is a pointer to member
object or the underlying representation array of the containing
object, so such diagnosis is suppressed.
Fixes: 715c5ce454a6 ("libbpf: Add low level TC-BPF management API")
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20210619041454.417577-1-memxor@gmail.com
Let us sync linux/{pkt_cls.h,pkt_sched.h} to libbpf repo.
Otherwise, on ubuntu 16.04, system headers will be picked up
and this will result in compilation error like:
.../netlink.c:416:23: error: ‘TC_H_CLSACT’ undeclared (first use in this function)
*parent = TC_H_MAKE(TC_H_CLSACT,
^
.../netlink.c:418:9: error: ‘TC_H_MIN_INGRESS’ undeclared (first use in this function)
TC_H_MIN_INGRESS : TC_H_MIN_EGRESS);
^
.../netlink.c:418:28: error: ‘TC_H_MIN_EGRESS’ undeclared (first use in this function)
TC_H_MIN_INGRESS : TC_H_MIN_EGRESS);
^
.../netlink.c: In function ‘__get_tc_info’:
.../netlink.c:522:11: error: ‘TCA_BPF_ID’ undeclared (first use in this function)
if (!tbb[TCA_BPF_ID])
^
Signed-off-by: Yonghong Song <yhs@fb.com>
Make sure we run all of the tests even if some of them fail. This allows to
test all of them independently, especially kernel LATEST slow test.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
This patch is meant to start the initiative to document libbpf.
It includes .rst files which are text documentation describing building,
API naming convention, as well as an index to generated API documentation.
In this approach the generated API documentation is enabled by the kernels
existing kernel documentation system which uses sphinx. The resulting docs
would then be synced to kernel.org/doc
You can test this by running `make htmldocs` and serving the html in
Documentation/output. Since libbpf does not yet have comments in kernel
doc format, see kernel.org/doc/html/latest/doc-guide/kernel-doc.html for
an example so you can test this.
The advantage of this approach is to use the existing sphinx
infrastructure that the kernel has, and have libbpf docs in
the same place as everything else.
The current plan is to have the libbpf mirror sync the generated docs
and version them based on the libbpf releases which are cut on github.
This patch includes the addition of libbpf_api.rst which pulls comment
documentation from header files in libbpf under tools/lib/bpf/. The comment
docs would be of the standard kernel doc format.
Signed-off-by: grantseltzer <grantseltzer@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210618140459.9887-2-grantseltzer@gmail.com
bpf2go is the Go equivalent of libbpf skeleton. The convention is that
the compiled BPF is checked into the repository to facilitate distributing
BPF as part of Go packages. To make this portable, bpf2go by default
generates both bpfel and bpfeb variants of the C.
Using bpf_tracing.h is inherently non-portable since the fields of
struct pt_regs differ between platforms, so CO-RE can't help us here.
The only way of working around this is to compile for each target
platform independently. bpf2go can't do this by default since there
are too many platforms.
Define the various PT_... macros when no target can be determined and
turn them into compilation failures. This works because bpf2go always
compiles for bpf targets, so the compiler fallback doesn't kick in.
Conditionally define __BPF_MISSING_TARGET so that we can inject a
more appropriate error message at build time. The user can then
choose which platform to target explicitly.
Signed-off-by: Lorenz Bauer <lmb@cloudflare.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210616083635.11434-1-lmb@cloudflare.com
This patch introduces a new bpf_attach_type for BPF_PROG_TYPE_SK_REUSEPORT
to check if the attached eBPF program is capable of migrating sockets. When
the eBPF program is attached, we run it for socket migration if the
expected_attach_type is BPF_SK_REUSEPORT_SELECT_OR_MIGRATE or
net.ipv4.tcp_migrate_req is enabled.
Currently, the expected_attach_type is not enforced for the
BPF_PROG_TYPE_SK_REUSEPORT type of program. Thus, this commit follows the
earlier idea in the commit aac3fc320d94 ("bpf: Post-hooks for sys_bind") to
fix up the zero expected_attach_type in bpf_prog_load_fixup_attach_type().
Moreover, this patch adds a new field (migrating_sk) to sk_reuseport_md to
select a new listener based on the child socket. migrating_sk varies
depending on if it is migrating a request in the accept queue or during
3WHS.
- accept_queue : sock (ESTABLISHED/SYN_RECV)
- 3WHS : request_sock (NEW_SYN_RECV)
In the eBPF program, we can select a new listener by
BPF_FUNC_sk_select_reuseport(). Also, we can cancel migration by returning
SK_DROP. This feature is useful when listeners have different settings at
the socket API level or when we want to free resources as soon as possible.
- SK_PASS with selected_sk, select it as a new listener
- SK_PASS with selected_sk NULL, fallbacks to the random selection
- SK_DROP, cancel the migration.
There is a noteworthy point. We select a listening socket in three places,
but we do not have struct skb at closing a listener or retransmitting a
SYN+ACK. On the other hand, some helper functions do not expect skb is NULL
(e.g. skb_header_pointer() in BPF_FUNC_skb_load_bytes(), skb_tail_pointer()
in BPF_FUNC_skb_load_bytes_relative()). So we allocate an empty skb
temporarily before running the eBPF program.
Suggested-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.co.jp>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/netdev/20201123003828.xjpjdtk4ygl6tg6h@kafai-mbp.dhcp.thefacebook.com/
Link: https://lore.kernel.org/netdev/20201203042402.6cskdlit5f3mw4ru@kafai-mbp.dhcp.thefacebook.com/
Link: https://lore.kernel.org/netdev/20201209030903.hhow5r53l6fmozjn@kafai-mbp.dhcp.thefacebook.com/
Link: https://lore.kernel.org/bpf/20210612123224.12525-10-kuniyu@amazon.co.jp
When calling xsk_socket__create_shared(), the logic at line 1097 marks a
boolean flag true within the xsk_umem structure to track setup progress
in order to support multiple calls to the function. However, instead of
marking umem->tx_ring_setup_done, the code incorrectly sets
umem->rx_ring_setup_done. This leads to improper behaviour when
creating and destroying xsk and umem structures.
Multiple calls to this function is documented as supported.
Fixes: ca7a83e2487a ("libbpf: Only create rx and tx XDP rings when necessary")
Signed-off-by: Kev Jackson <foamdino@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/YL4aU4f3Aaik7CN0@linux-dev
These macros are convenient wrappers around the bpf_seq_printf and
bpf_snprintf helpers. They are currently provided by bpf_tracing.h which
targets low level tracing primitives. bpf_helpers.h is a better fit.
The __bpf_narg and __bpf_apply are needed in both files and provided
twice. __bpf_empty isn't used anywhere and is removed from bpf_tracing.h
Reported-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Florent Revest <revest@chromium.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210526164643.2881368-1-revest@chromium.org
This patch adds two flags BPF_F_BROADCAST and BPF_F_EXCLUDE_INGRESS to
extend xdp_redirect_map for broadcast support.
With BPF_F_BROADCAST the packet will be broadcasted to all the interfaces
in the map. with BPF_F_EXCLUDE_INGRESS the ingress interface will be
excluded when do broadcasting.
When getting the devices in dev hash map via dev_map_hash_get_next_key(),
there is a possibility that we fall back to the first key when a device
was removed. This will duplicate packets on some interfaces. So just walk
the whole buckets to avoid this issue. For dev array map, we also walk the
whole map to find valid interfaces.
Function bpf_clear_redirect_map() was removed in
commit ee75aef23afe ("bpf, xdp: Restructure redirect actions").
Add it back as we need to use ri->map again.
With test topology:
+-------------------+ +-------------------+
| Host A (i40e 10G) | ---------- | eno1(i40e 10G) |
+-------------------+ | |
| Host B |
+-------------------+ | |
| Host C (i40e 10G) | ---------- | eno2(i40e 10G) |
+-------------------+ | |
| +------+ |
| veth0 -- | Peer | |
| veth1 -- | | |
| veth2 -- | NS | |
| +------+ |
+-------------------+
On Host A:
# pktgen/pktgen_sample03_burst_single_flow.sh -i eno1 -d $dst_ip -m $dst_mac -s 64
On Host B(Intel(R) Xeon(R) CPU E5-2690 v3 @ 2.60GHz, 128G Memory):
Use xdp_redirect_map and xdp_redirect_map_multi in samples/bpf for testing.
All the veth peers in the NS have a XDP_DROP program loaded. The
forward_map max_entries in xdp_redirect_map_multi is modify to 4.
Testing the performance impact on the regular xdp_redirect path with and
without patch (to check impact of additional check for broadcast mode):
5.12 rc4 | redirect_map i40e->i40e | 2.0M | 9.7M
5.12 rc4 | redirect_map i40e->veth | 1.7M | 11.8M
5.12 rc4 + patch | redirect_map i40e->i40e | 2.0M | 9.6M
5.12 rc4 + patch | redirect_map i40e->veth | 1.7M | 11.7M
Testing the performance when cloning packets with the redirect_map_multi
test, using a redirect map size of 4, filled with 1-3 devices:
5.12 rc4 + patch | redirect_map multi i40e->veth (x1) | 1.7M | 11.4M
5.12 rc4 + patch | redirect_map multi i40e->veth (x2) | 1.1M | 4.3M
5.12 rc4 + patch | redirect_map multi i40e->veth (x3) | 0.8M | 2.6M
Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>
Link: https://lore.kernel.org/bpf/20210519090747.1655268-3-liuhangbin@gmail.com
Implement changes to error reporting for high-level libbpf APIs to make them
less surprising and less error-prone to users:
- in all the cases when error happens, errno is set to an appropriate error
value;
- in libbpf 1.0 mode, all pointer-returning APIs return NULL on error and
error code is communicated through errno; this applies both to APIs that
already returned NULL before (so now they communicate more detailed error
codes), as well as for many APIs that used ERR_PTR() macro and encoded
error numbers as fake pointers.
- in legacy (default) mode, those APIs that were returning ERR_PTR(err),
continue doing so, but still set errno.
With these changes, errno can be always used to extract actual error,
regardless of legacy or libbpf 1.0 modes. This is utilized internally in
libbpf in places where libbpf uses it's own high-level APIs.
libbpf_get_error() is adapted to handle both cases completely transparently to
end-users (and is used by libbpf consistently as well).
More context, justification, and discussion can be found in "Libbpf: the road
to v1.0" document ([0]).
[0] https://docs.google.com/document/d/1UyjTZuPFWiPFyKk1tV5an11_iaRuec6U-ZESZ54nNTY
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/bpf/20210525035935.1461796-5-andrii@kernel.org
Add libbpf_set_strict_mode() API that allows application to simulate libbpf
1.0 breaking changes before libbpf 1.0 is released. This will help users
migrate gradually and with confidence.
For now only ALL or NONE options are available, subsequent patches will add
more flags. This patch is preliminary for selftests/bpf changes.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/bpf/20210525035935.1461796-2-andrii@kernel.org
I'm getting the following error when running 'gen skeleton -L' as
regular user:
libbpf: Error in bpf_object__probe_loading():Operation not permitted(1).
Couldn't load trivial BPF program. Make sure your kernel supports BPF
(CONFIG_BPF_SYSCALL=y) and/or that RLIMIT_MEMLOCK is set to big enough
value.
Fixes: 67234743736a ("libbpf: Generate loader program out of BPF ELF file.")
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210521030653.2626513-1-sdf@google.com
The BPF program loading process performed by libbpf is quite complex
and consists of the following steps:
"open" phase:
- parse elf file and remember relocations, sections
- collect externs and ksyms including their btf_ids in prog's BTF
- patch BTF datasec (since llvm couldn't do it)
- init maps (old style map_def, BTF based, global data map, kconfig map)
- collect relocations against progs and maps
"load" phase:
- probe kernel features
- load vmlinux BTF
- resolve externs (kconfig and ksym)
- load program BTF
- init struct_ops
- create maps
- apply CO-RE relocations
- patch ld_imm64 insns with src_reg=PSEUDO_MAP, PSEUDO_MAP_VALUE, PSEUDO_BTF_ID
- reposition subprograms and adjust call insns
- sanitize and load progs
During this process libbpf does sys_bpf() calls to load BTF, create maps,
populate maps and finally load programs.
Instead of actually doing the syscalls generate a trace of what libbpf
would have done and represent it as the "loader program".
The "loader program" consists of single map with:
- union bpf_attr(s)
- BTF bytes
- map value bytes
- insns bytes
and single bpf program that passes bpf_attr(s) and data into bpf_sys_bpf() helper.
Executing such "loader program" via bpf_prog_test_run() command will
replay the sequence of syscalls that libbpf would have done which will result
the same maps created and programs loaded as specified in the elf file.
The "loader program" removes libelf and majority of libbpf dependency from
program loading process.
kconfig, typeless ksym, struct_ops and CO-RE are not supported yet.
The order of relocate_data and relocate_calls had to change, so that
bpf_gen__prog_load() can see all relocations for a given program with
correct insn_idx-es.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210514003623.28033-15-alexei.starovoitov@gmail.com
In order to be able to generate loader program in the later
patches change the order of data and text relocations.
Also improve the test to include data relos.
If the kernel supports "FD array" the map_fd relocations can be processed
before text relos since generated loader program won't need to manually
patch ld_imm64 insns with map_fd.
But ksym and kfunc relocations can only be processed after all calls
are relocated, since loader program will consist of a sequence
of calls to bpf_btf_find_by_name_kind() followed by patching of btf_id
and btf_obj_fd into corresponding ld_imm64 insns. The locations of those
ld_imm64 insns are specified in relocations.
Hence process all data relocations (maps, ksym, kfunc) together after call relos.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210514003623.28033-12-alexei.starovoitov@gmail.com
Add new helper:
long bpf_btf_find_by_name_kind(char *name, int name_sz, u32 kind, int flags)
Description
Find BTF type with given name and kind in vmlinux BTF or in module's BTFs.
Return
Returns btf_id and btf_obj_fd in lower and upper 32 bits.
It will be used by loader program to find btf_id to attach the program to
and to find btf_ids of ksyms.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210514003623.28033-10-alexei.starovoitov@gmail.com
Typical program loading sequence involves creating bpf maps and applying
map FDs into bpf instructions in various places in the bpf program.
This job is done by libbpf that is using compiler generated ELF relocations
to patch certain instruction after maps are created and BTFs are loaded.
The goal of fd_idx is to allow bpf instructions to stay immutable
after compilation. At load time the libbpf would still create maps as usual,
but it wouldn't need to patch instructions. It would store map_fds into
__u32 fd_array[] and would pass that pointer to sys_bpf(BPF_PROG_LOAD).
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210514003623.28033-9-alexei.starovoitov@gmail.com
LLVM patch https://reviews.llvm.org/D102712
narrowed the scope of existing R_BPF_64_64
and R_BPF_64_32 relocations, and added three
new relocations, R_BPF_64_ABS64, R_BPF_64_ABS32
and R_BPF_64_NODYLD32. The main motivation is
to make relocations linker friendly.
This change, unfortunately, breaks libbpf build,
and we will see errors like below:
libbpf: ELF relo #0 in section #6 has unexpected type 2 in
/home/yhs/work/bpf-next/tools/testing/selftests/bpf/bpf_tcp_nogpl.o
Error: failed to link
'/home/yhs/work/bpf-next/tools/testing/selftests/bpf/bpf_tcp_nogpl.o':
Unknown error -22 (-22)
The new relocation R_BPF_64_ABS64 is generated
and libbpf linker sanity check doesn't understand it.
Relocation section '.rel.struct_ops' at offset 0x1410 contains 1 entries:
Offset Info Type Symbol's Value Symbol's Name
0000000000000018 0000000700000002 R_BPF_64_ABS64 0000000000000000 nogpltcp_init
Look at the selftests/bpf/bpf_tcp_nogpl.c,
void BPF_STRUCT_OPS(nogpltcp_init, struct sock *sk)
{
}
SEC(".struct_ops")
struct tcp_congestion_ops bpf_nogpltcp = {
.init = (void *)nogpltcp_init,
.name = "bpf_nogpltcp",
};
The new llvm relocation scheme categorizes 'nogpltcp_init' reference
as R_BPF_64_ABS64 instead of R_BPF_64_64 which is used to specify
ld_imm64 relocation in the new scheme.
Let us fix the linker sanity checking by including
R_BPF_64_ABS64 and R_BPF_64_ABS32. There is no need to
check R_BPF_64_NODYLD32 which is used for .BTF and .BTF.ext.
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20210522162341.3687617-1-yhs@fb.com
This adds functions that wrap the netlink API used for adding, manipulating,
and removing traffic control filters.
The API summary:
A bpf_tc_hook represents a location where a TC-BPF filter can be attached.
This means that creating a hook leads to creation of the backing qdisc,
while destruction either removes all filters attached to a hook, or destroys
qdisc if requested explicitly (as discussed below).
The TC-BPF API functions operate on this bpf_tc_hook to attach, replace,
query, and detach tc filters. All functions return 0 on success, and a
negative error code on failure.
bpf_tc_hook_create - Create a hook
Parameters:
@hook - Cannot be NULL, ifindex > 0, attach_point must be set to
proper enum constant. Note that parent must be unset when
attach_point is one of BPF_TC_INGRESS or BPF_TC_EGRESS. Note
that as an exception BPF_TC_INGRESS|BPF_TC_EGRESS is also a
valid value for attach_point.
Returns -EOPNOTSUPP when hook has attach_point as BPF_TC_CUSTOM.
bpf_tc_hook_destroy - Destroy a hook
Parameters:
@hook - Cannot be NULL. The behaviour depends on value of
attach_point. If BPF_TC_INGRESS, all filters attached to
the ingress hook will be detached. If BPF_TC_EGRESS, all
filters attached to the egress hook will be detached. If
BPF_TC_INGRESS|BPF_TC_EGRESS, the clsact qdisc will be
deleted, also detaching all filters. As before, parent must
be unset for these attach_points, and set for BPF_TC_CUSTOM.
It is advised that if the qdisc is operated on by many programs,
then the program at least check that there are no other existing
filters before deleting the clsact qdisc. An example is shown
below:
DECLARE_LIBBPF_OPTS(bpf_tc_hook, .ifindex = if_nametoindex("lo"),
.attach_point = BPF_TC_INGRESS);
/* set opts as NULL, as we're not really interested in
* getting any info for a particular filter, but just
* detecting its presence.
*/
r = bpf_tc_query(&hook, NULL);
if (r == -ENOENT) {
/* no filters */
hook.attach_point = BPF_TC_INGRESS|BPF_TC_EGREESS;
return bpf_tc_hook_destroy(&hook);
} else {
/* failed or r == 0, the latter means filters do exist */
return r;
}
Note that there is a small race between checking for no
filters and deleting the qdisc. This is currently unavoidable.
Returns -EOPNOTSUPP when hook has attach_point as BPF_TC_CUSTOM.
bpf_tc_attach - Attach a filter to a hook
Parameters:
@hook - Cannot be NULL. Represents the hook the filter will be
attached to. Requirements for ifindex and attach_point are
same as described in bpf_tc_hook_create, but BPF_TC_CUSTOM
is also supported. In that case, parent must be set to the
handle where the filter will be attached (using BPF_TC_PARENT).
E.g. to set parent to 1:16 like in tc command line, the
equivalent would be BPF_TC_PARENT(1, 16).
@opts - Cannot be NULL. The following opts are optional:
* handle - The handle of the filter
* priority - The priority of the filter
Must be >= 0 and <= UINT16_MAX
Note that when left unset, they will be auto-allocated by
the kernel. The following opts must be set:
* prog_fd - The fd of the loaded SCHED_CLS prog
The following opts must be unset:
* prog_id - The ID of the BPF prog
The following opts are optional:
* flags - Currently only BPF_TC_F_REPLACE is allowed. It
allows replacing an existing filter instead of
failing with -EEXIST.
The following opts will be filled by bpf_tc_attach on a
successful attach operation if they are unset:
* handle - The handle of the attached filter
* priority - The priority of the attached filter
* prog_id - The ID of the attached SCHED_CLS prog
This way, the user can know what the auto allocated values
for optional opts like handle and priority are for the newly
attached filter, if they were unset.
Note that some other attributes are set to fixed default
values listed below (this holds for all bpf_tc_* APIs):
protocol as ETH_P_ALL, direct action mode, chain index of 0,
and class ID of 0 (this can be set by writing to the
skb->tc_classid field from the BPF program).
bpf_tc_detach
Parameters:
@hook - Cannot be NULL. Represents the hook the filter will be
detached from. Requirements are same as described above
in bpf_tc_attach.
@opts - Cannot be NULL. The following opts must be set:
* handle, priority
The following opts must be unset:
* prog_fd, prog_id, flags
bpf_tc_query
Parameters:
@hook - Cannot be NULL. Represents the hook where the filter lookup will
be performed. Requirements are same as described above in
bpf_tc_attach().
@opts - Cannot be NULL. The following opts must be set:
* handle, priority
The following opts must be unset:
* prog_fd, prog_id, flags
The following fields will be filled by bpf_tc_query upon a
successful lookup:
* prog_id
Some usage examples (using BPF skeleton infrastructure):
BPF program (test_tc_bpf.c):
#include <linux/bpf.h>
#include <bpf/bpf_helpers.h>
SEC("classifier")
int cls(struct __sk_buff *skb)
{
return 0;
}
Userspace loader:
struct test_tc_bpf *skel = NULL;
int fd, r;
skel = test_tc_bpf__open_and_load();
if (!skel)
return -ENOMEM;
fd = bpf_program__fd(skel->progs.cls);
DECLARE_LIBBPF_OPTS(bpf_tc_hook, hook, .ifindex =
if_nametoindex("lo"), .attach_point =
BPF_TC_INGRESS);
/* Create clsact qdisc */
r = bpf_tc_hook_create(&hook);
if (r < 0)
goto end;
DECLARE_LIBBPF_OPTS(bpf_tc_opts, opts, .prog_fd = fd);
r = bpf_tc_attach(&hook, &opts);
if (r < 0)
goto end;
/* Print the auto allocated handle and priority */
printf("Handle=%u", opts.handle);
printf("Priority=%u", opts.priority);
opts.prog_fd = opts.prog_id = 0;
bpf_tc_detach(&hook, &opts);
end:
test_tc_bpf__destroy(skel);
This is equivalent to doing the following using tc command line:
# tc qdisc add dev lo clsact
# tc filter add dev lo ingress bpf obj foo.o sec classifier da
# tc filter del dev lo ingress handle <h> prio <p> bpf
... where the handle and priority can be found using:
# tc filter show dev lo ingress
Another example replacing a filter (extending prior example):
/* We can also choose both (or one), let's try replacing an
* existing filter.
*/
DECLARE_LIBBPF_OPTS(bpf_tc_opts, replace_opts, .handle =
opts.handle, .priority = opts.priority,
.prog_fd = fd);
r = bpf_tc_attach(&hook, &replace_opts);
if (r == -EEXIST) {
/* Expected, now use BPF_TC_F_REPLACE to replace it */
replace_opts.flags = BPF_TC_F_REPLACE;
return bpf_tc_attach(&hook, &replace_opts);
} else if (r < 0) {
return r;
}
/* There must be no existing filter with these
* attributes, so cleanup and return an error.
*/
replace_opts.prog_fd = replace_opts.prog_id = 0;
bpf_tc_detach(&hook, &replace_opts);
return -1;
To obtain info of a particular filter:
/* Find info for filter with handle 1 and priority 50 */
DECLARE_LIBBPF_OPTS(bpf_tc_opts, info_opts, .handle = 1,
.priority = 50);
r = bpf_tc_query(&hook, &info_opts);
if (r == -ENOENT)
printf("Filter not found");
else if (r < 0)
return r;
printf("Prog ID: %u", info_opts.prog_id);
return 0;
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Co-developed-by: Daniel Borkmann <daniel@iogearbox.net> # libbpf API design
[ Daniel: also did major patch cleanup ]
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/bpf/20210512103451.989420-3-memxor@gmail.com
This change introduces a few helpers to wrap open coded attribute
preparation in netlink.c. It also adds a libbpf_netlink_send_recv() that
is useful to wrap send + recv handling in a generic way. Subsequent patch
will also use this function for sending and receiving a netlink response.
The libbpf_nl_get_link() helper has been removed instead, moving socket
creation into the newly named libbpf_netlink_send_recv().
Every nested attribute's closure must happen using the helper
nlattr_end_nested(), which sets its length properly. NLA_F_NESTED is
enforced using nlattr_begin_nested() helper. Other simple attributes
can be added directly.
The maxsz parameter corresponds to the size of the request structure
which is being filled in, so for instance with req being:
struct {
struct nlmsghdr nh;
struct tcmsg t;
char buf[4096];
} req;
Then, maxsz should be sizeof(req).
This change also converts the open coded attribute preparation with these
helpers. Note that the only failure the internal call to nlattr_add()
could result in the nested helper would be -EMSGSIZE, hence that is what
we return to our caller.
The libbpf_netlink_send_recv() call takes care of opening the socket,
sending the netlink message, receiving the response, potentially invoking
callbacks, and return errors if any, and then finally close the socket.
This allows users to avoid identical socket setup code in different places.
The only user of libbpf_nl_get_link() has been converted to make use of it.
__bpf_set_link_xdp_fd_replace() has also been refactored to use it.
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
[ Daniel: major patch cleanup ]
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/bpf/20210512103451.989420-2-memxor@gmail.com
Static maps never really worked with libbpf, because all such maps were always
silently resolved to the very first map. Detect static maps (both legacy and
BTF-defined) and report user-friendly error.
Tested locally by switching few maps (legacy and BTF-defined) in selftests to
static ones and verifying that now libbpf rejects them loudly.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210513233643.194711-2-andrii@kernel.org
For better future extensibility add per-file linker options. Currently
the set of available options is empty. This changes bpf_linker__add_file()
API, but it's not a breaking change as bpf_linker APIs hasn't been released
yet.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210507054119.270888-3-andrii@kernel.org
One of our benchmarks running in (Google-internal) CI pushes data
through the ringbuf faster htan than userspace is able to consume
it. In this case it seems we're actually able to get >INT_MAX entries
in a single ring_buffer__consume() call. ASAN detected that cnt
overflows in this case.
Fix by using 64-bit counter internally and then capping the result to
INT_MAX before converting to the int return type. Do the same for
the ring_buffer__poll().
Fixes: bf99c936f947 (libbpf: Add BPF ring buffer support)
Signed-off-by: Brendan Jackman <jackmanb@google.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210429130510.1621665-1-jackmanb@google.com
Add BTF_KIND_FLOAT support when doing CO-RE field type compatibility check.
Without this, relocations against float/double fields will fail.
Also adjust one error message to emit instruction index instead of less
convenient instruction byte offset.
Fixes: 22541a9eeb0d ("libbpf: Add BTF_KIND_FLOAT support")
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Lorenz Bauer <lmb@cloudflare.com>
Link: https://lore.kernel.org/bpf/20210426192949.416837-3-andrii@kernel.org
Use aptitude to actually see what's wrong with the dependencies. And it
actually magically resolves whatever minor version conflicts there are.
The big surprise came from the apparent difference in build-dep command
behavior. Aptitude's build-dep doesn't seem to install the libpfelf-dev
package itself. Adding explicit `aptitude install libelf-dev` after build-dep
solves the issue for now.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Force libc6 dependency version.
Drop explicit libelf-dev install command, as it should be pre-installed by
Travis CI already, according to .travis.yaml.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Add extra logic to handle map externs (only BTF-defined maps are supported for
linking). Re-use the map parsing logic used during bpf_object__open(). Map
externs are currently restricted to always match complete map definition. So
all the specified attributes will be compared (down to pining, map_flags,
numa_node, etc). In the future this restriction might be relaxed with no
backwards compatibility issues. If any attribute is mismatched between extern
and actual map definition, linker will report an error, pointing out which one
mismatches.
The original intent was to allow for extern to specify attributes that matters
(to user) to enforce. E.g., if you specify just key information and omit
value, then any value fits. Similarly, it should have been possible to enforce
map_flags, pinning, and any other possible map attribute. Unfortunately, that
means that multiple externs can be only partially overlapping with each other,
which means linker would need to combine their type definitions to end up with
the most restrictive and fullest map definition. This requires an extra amount
of BTF manipulation which at this time was deemed unnecessary and would
require further extending generic BTF writer APIs. So that is left for future
follow ups, if there will be demand for that. But the idea seems intresting
and useful, so I want to document it here.
Weak definitions are also supported, but are pretty strict as well, just
like externs: all weak map definitions have to match exactly. In the follow up
patches this most probably will be relaxed, with __weak map definitions being
able to differ between each other (with non-weak definition always winning, of
course).
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20210423181348.1801389-13-andrii@kernel.org
Add BPF static linker logic to resolve extern variables and functions across
multiple linked together BPF object files.
For that, linker maintains a separate list of struct glob_sym structures,
which keeps track of few pieces of metadata (is it extern or resolved global,
is it a weak symbol, which ELF section it belongs to, etc) and ties together
BTF type info and ELF symbol information and keeps them in sync.
With adding support for extern variables/funcs, it's now possible for some
sections to contain both extern and non-extern definitions. This means that
some sections may start out as ephemeral (if only externs are present and thus
there is not corresponding ELF section), but will be "upgraded" to actual ELF
section as symbols are resolved or new non-extern definitions are appended.
Additional care is taken to not duplicate extern entries in sections like
.kconfig and .ksyms.
Given libbpf requires BTF type to always be present for .kconfig/.ksym
externs, linker extends this requirement to all the externs, even those that
are supposed to be resolved during static linking and which won't be visible
to libbpf. With BTF information always present, static linker will check not
just ELF symbol matches, but entire BTF type signature match as well. That
logic is stricter that BPF CO-RE checks. It probably should be re-used by
.ksym resolution logic in libbpf as well, but that's left for follow up
patches.
To make it unnecessary to rewrite ELF symbols and minimize BTF type
rewriting/removal, ELF symbols that correspond to externs initially will be
updated in place once they are resolved. Similarly for BTF type info, VAR/FUNC
and var_secinfo's (sec_vars in struct bpf_linker) are staying stable, but
types they point to might get replaced when extern is resolved. This might
leave some left-over types (even though we try to minimize this for common
cases of having extern funcs with not argument names vs concrete function with
names properly specified). That can be addresses later with a generic BTF
garbage collection. That's left for a follow up as well.
Given BTF type appending phase is separate from ELF symbol
appending/resolution, special struct glob_sym->underlying_btf_id variable is
used to communicate resolution and rewrite decisions. 0 means
underlying_btf_id needs to be appended (it's not yet in final linker->btf), <0
values are used for temporary storage of source BTF type ID (not yet
rewritten), so -glob_sym->underlying_btf_id is BTF type id in obj-btf. But by
the end of linker_append_btf() phase, that underlying_btf_id will be remapped
and will always be > 0. This is the uglies part of the whole process, but
keeps the other parts much simpler due to stability of sec_var and VAR/FUNC
types, as well as ELF symbol, so please keep that in mind while reviewing.
BTF-defined maps require some extra custom logic and is addressed separate in
the next patch, so that to keep this one smaller and easier to review.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20210423181348.1801389-12-andrii@kernel.org
Make skip_mods_and_typedefs(), btf_kind_str(), and btf_func_linkage() helpers
available outside of libbpf.c, to be used by static linker code.
Also do few cleanups (error code fixes, comment clean up, etc) that don't
deserve their own commit.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20210423181348.1801389-9-andrii@kernel.org
Factor out logic for sanity checking SHT_SYMTAB and SHT_REL sections into
separate sections. They are already quite extensive and are suffering from too
deep indentation. Subsequent changes will extend SYMTAB sanity checking
further, so it's better to factor each into a separate function.
No functional changes are intended.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20210423181348.1801389-8-andrii@kernel.org
Refactor BTF-defined maps parsing logic to allow it to be nicely reused by BPF
static linker. Further, at least for BPF static linker, it's important to know
which attributes of a BPF map were defined explicitly, so provide a bit set
for each known portion of BTF map definition. This allows BPF static linker to
do a simple check when dealing with extern map declarations.
The same capabilities allow to distinguish attributes explicitly set to zero
(e.g., __uint(max_entries, 0)) vs the case of not specifying it at all (no
max_entries attribute at all). Libbpf is currently not utilizing that, but it
could be useful for backwards compatibility reasons later.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20210423181348.1801389-7-andrii@kernel.org
Currently libbpf is very strict about parsing BPF program instruction
sections. No gaps are allowed between sequential BPF programs within a given
ELF section. Libbpf enforced that by keeping track of the next section offset
that should start a new BPF (sub)program and cross-checks that by searching
for a corresponding STT_FUNC ELF symbol.
But this is too restrictive once we allow to have weak BPF programs and link
together two or more BPF object files. In such case, some weak BPF programs
might be "overridden" by either non-weak BPF program with the same name and
signature, or even by another weak BPF program that just happened to be linked
first. That, in turn, leaves BPF instructions of the "lost" BPF (sub)program
intact, but there is no corresponding ELF symbol, because no one is going to
be referencing it.
Libbpf already correctly handles such cases in the sense that it won't append
such dead code to actual BPF programs loaded into kernel. So the only change
that needs to be done is to relax the logic of parsing BPF instruction
sections. Instead of assuming next BPF (sub)program section offset, iterate
available STT_FUNC ELF symbols to discover all available BPF subprograms and
programs.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20210423181348.1801389-6-andrii@kernel.org
Define __hidden helper macro in bpf_helpers.h, which is a short-hand for
__attribute__((visibility("hidden"))). Add libbpf support to mark BPF
subprograms marked with __hidden as static in BTF information to enforce BPF
verifier's static function validation algorithm, which takes more information
(caller's context) into account during a subprogram validation.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20210423181348.1801389-5-andrii@kernel.org
When initializing the __param array with a one liner, if all args are
const, the initial array value will be placed in the rodata section but
because libbpf does not support relocation in the rodata section, any
pointer in this array will stay NULL.
Fixes: c09add2fbc5a ("tools/libbpf: Add bpf_iter support")
Signed-off-by: Florent Revest <revest@chromium.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210419155243.1632274-5-revest@chromium.org
The implementation takes inspiration from the existing bpf_trace_printk
helper but there are a few differences:
To allow for a large number of format-specifiers, parameters are
provided in an array, like in bpf_seq_printf.
Because the output string takes two arguments and the array of
parameters also takes two arguments, the format string needs to fit in
one argument. Thankfully, ARG_PTR_TO_CONST_STR is guaranteed to point to
a zero-terminated read-only map so we don't need a format string length
arg.
Because the format-string is known at verification time, we also do
a first pass of format string validation in the verifier logic. This
makes debugging easier.
Signed-off-by: Florent Revest <revest@chromium.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210419155243.1632274-4-revest@chromium.org
Synchronize tools/include/uapi/linux/bpf.h which was missing changes
from various commits:
- f3c45326ee71 ("bpf: Document PROG_TEST_RUN limitations")
- e5e35e754c28 ("bpf: BPF-helper for MTU checking add length input")
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
S50-run-tests uses -e, which means that it immediately exits on test
failures without writing /exitcode. Fix by temporarily turning -e off.
Another issue is that $? in S50-run-tests is not quoted, which causes
the random value from the host to be taken (in practice always 0), so
fix that as well.
Finally, this fix has a positive side effect - QEMU no longer hangs
when tests fail. This is because rcS (generated by mkrootfs.sh) also
uses -e and immediately exits, if one of the scripts that it calls
fails, without calling S99-poweroff.
Example output after the fix:
Summary: 53/184 PASSED, 5 SKIPPED, 1 FAILED
+ exitstatus=1
+ set -e
+ echo 1
+ chmod 644 /exitstatus
+ for path in /etc/rcS.d/S*
+ '[' -x /etc/rcS.d/S99-poweroff ']'
+ /etc/rcS.d/S99-poweroff
travis_fold:start:shutdown
Shutdown
starting pid 232, tty '': '/sbin/swapoff -a'
starting pid 233, tty '': '/bin/umount -a -r'
[ 45.909033] EXT4-fs (vda): re-mounted. Opts: (null)
The system is going down NOW!
Sent SIGTERM to all processes
Sent SIGKILL to all processes
Requesting system poweroff
[ 48.932007] ACPI: Preparing to enter system sleep state S5
[ 48.932785] reboot: Power down
Tests exit status: 1
travis_fold🔚shutdown
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
The scripts in this directory rely on certain environment variables, so
fail if they are not set in order to improve the debugging experience.
The vmtest/ scripts already do it.
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
This is the same as commit 4d86cae4f0 ("ci: disable GCC's
-Wstringop-truncation noisy error"), but for Ubuntu. Without this,
there are false positives in bpf_object__new() on Ubuntu 20.04:
this function calls strncpy() with the correct bounds, but still
triggers the warning.
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
It requires v5.9+ kernel when the test code is built with a newer
toolchain. The support was added by commit b33164f2bd1c ("bpf:
Iterate through all PT_NOTE sections when looking for build id").
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Prior to this commit xsk_socket__create(_shared) always attempted to create
the rx and tx rings for the socket. However this causes an issue when the
socket being setup is that which shares the fd with the UMEM. If a
previous call to this function failed with this socket after the rings were
set up, a subsequent call would always fail because the rings are not torn
down after the first call and when we try to set them up again we encounter
an error because they already exist. Solve this by remembering whether the
rings were set up by introducing new bools to struct xsk_umem which
represent the ring setup status and using them to determine whether or
not to set up the rings.
Fixes: 1cad07884239 ("libbpf: add support for using AF_XDP sockets")
Signed-off-by: Ciara Loftus <ciara.loftus@intel.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210331061218.1647-4-ciara.loftus@intel.com
If the call to xsk_socket__create fails, the user may want to retry the
socket creation using the same umem. Ensure that the umem is in the
same state on exit if the call fails by:
1. ensuring the umem _save pointers are unmodified.
2. not unmapping the set of umem rings that were set up with the umem
during xsk_umem__create, since those maps existed before the call to
xsk_socket__create and should remain in tact even in the event of
failure.
Fixes: 2f6324a3937f ("libbpf: Support shared umems between queues and devices")
Signed-off-by: Ciara Loftus <ciara.loftus@intel.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210331061218.1647-3-ciara.loftus@intel.com
The current code bails out with negative and positive returns.
If the callback returns a positive return code, 'ring_buffer__consume()'
and 'ring_buffer__poll()' will return a spurious number of records
consumed, but mostly important will continue the processing loop.
This patch makes positive returns from the callback a no-op.
Fixes: bf99c936f947 ("libbpf: Add BPF ring buffer support")
Signed-off-by: Pedro Tammela <pctammela@mojatatu.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210325150115.138750-1-pctammela@mojatatu.com
Reusing BPF_SK_SKB_STREAM_VERDICT is possible but its name is
confusing and more importantly we still want to distinguish them
from user-space. So we can just reuse the stream verdict code but
introduce a new type of eBPF program, skb_verdict. Users are not
allowed to attach stream_verdict and skb_verdict programs to the
same map.
Signed-off-by: Cong Wang <cong.wang@bytedance.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20210331023237.41094-10-xiyou.wangcong@gmail.com
Currently, if there are multiple xdpsock instances running on a single
interface and in case one of the instances is terminated, the rest of
them are left in an inoperable state due to the fact of unloaded XDP
prog from interface.
Consider the scenario below:
// load xdp prog and xskmap and add entry to xskmap at idx 10
$ sudo ./xdpsock -i ens801f0 -t -q 10
// add entry to xskmap at idx 11
$ sudo ./xdpsock -i ens801f0 -t -q 11
terminate one of the processes and another one is unable to work due to
the fact that the XDP prog was unloaded from interface.
To address that, step away from setting bpf prog in favour of bpf_link.
This means that refcounting of BPF resources will be done automatically
by bpf_link itself.
Provide backward compatibility by checking if underlying system is
bpf_link capable. Do this by looking up/creating bpf_link on loopback
device. If it failed in any way, stick with netlink-based XDP prog.
therwise, use bpf_link-based logic.
When setting up BPF resources during xsk socket creation, check whether
bpf_link for a given ifindex already exists via set of calls to
bpf_link_get_next_id -> bpf_link_get_fd_by_id -> bpf_obj_get_info_by_fd
and comparing the ifindexes from bpf_link and xsk socket.
For case where resources exist but they are not AF_XDP related, bail out
and ask user to remove existing prog and then retry.
Lastly, do a bit of refactoring within __xsk_setup_xdp_prog and pull out
existing code branches based on prog_id value onto separate functions
that are responsible for resource initialization if prog_id was 0 and
for lookup existing resources for non-zero prog_id as that implies that
XDP program is present on the underlying net device. This in turn makes
it easier to follow, especially the teardown part of both branches.
Signed-off-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210329224316.17793-7-maciej.fijalkowski@intel.com
This patch is to make libbpf able to handle the following extern
kernel function declaration and do the needed relocations before
loading the bpf program to the kernel.
extern int foo(struct sock *) __attribute__((section(".ksyms")))
In the collect extern phase, needed changes is made to
bpf_object__collect_externs() and find_extern_btf_id() to collect
extern function in ".ksyms" section. The func in the BTF datasec also
needs to be replaced by an int var. The idea is similar to the existing
handling in extern var. In case the BTF may not have a var, a dummy ksym
var is added at the beginning of bpf_object__collect_externs()
if there is func under ksyms datasec. It will also change the
func linkage from extern to global which the kernel can support.
It also assigns a param name if it does not have one.
In the collect relo phase, it will record the kernel function
call as RELO_EXTERN_FUNC.
bpf_object__resolve_ksym_func_btf_id() is added to find the func
btf_id of the running kernel.
During actual relocation, it will patch the BPF_CALL instruction with
src_reg = BPF_PSEUDO_FUNC_CALL and insn->imm set to the running
kernel func's btf_id.
The required LLVM patch: https://reviews.llvm.org/D93563
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210325015234.1548923-1-kafai@fb.com
This patch records the extern sym relocs first before recording
subprog relocs. The later patch will have relocs for extern
kernel function call which is also using BPF_JMP | BPF_CALL.
It will be easier to handle the extern symbols first in
the later patch.
is_call_insn() helper is added. The existing is_ldimm64() helper
is renamed to is_ldimm64_insn() for consistency.
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210325015227.1548623-1-kafai@fb.com
This patch refactors most of the logic from
bpf_object__resolve_ksyms_btf_id() into a new function
bpf_object__resolve_ksym_var_btf_id().
It is to get ready for a later patch adding
bpf_object__resolve_ksym_func_btf_id() which resolves
a kernel function to the running kernel btf_id.
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210325015207.1546749-1-kafai@fb.com
This patch adds support to BPF verifier to allow bpf program calling
kernel function directly.
The use case included in this set is to allow bpf-tcp-cc to directly
call some tcp-cc helper functions (e.g. "tcp_cong_avoid_ai()"). Those
functions have already been used by some kernel tcp-cc implementations.
This set will also allow the bpf-tcp-cc program to directly call the
kernel tcp-cc implementation, For example, a bpf_dctcp may only want to
implement its own dctcp_cwnd_event() and reuse other dctcp_*() directly
from the kernel tcp_dctcp.c instead of reimplementing (or
copy-and-pasting) them.
The tcp-cc kernel functions mentioned above will be white listed
for the struct_ops bpf-tcp-cc programs to use in a later patch.
The white listed functions are not bounded to a fixed ABI contract.
Those functions have already been used by the existing kernel tcp-cc.
If any of them has changed, both in-tree and out-of-tree kernel tcp-cc
implementations have to be changed. The same goes for the struct_ops
bpf-tcp-cc programs which have to be adjusted accordingly.
This patch is to make the required changes in the bpf verifier.
First change is in btf.c, it adds a case in "btf_check_func_arg_match()".
When the passed in "btf->kernel_btf == true", it means matching the
verifier regs' states with a kernel function. This will handle the
PTR_TO_BTF_ID reg. It also maps PTR_TO_SOCK_COMMON, PTR_TO_SOCKET,
and PTR_TO_TCP_SOCK to its kernel's btf_id.
In the later libbpf patch, the insn calling a kernel function will
look like:
insn->code == (BPF_JMP | BPF_CALL)
insn->src_reg == BPF_PSEUDO_KFUNC_CALL /* <- new in this patch */
insn->imm == func_btf_id /* btf_id of the running kernel */
[ For the future calling function-in-kernel-module support, an array
of module btf_fds can be passed at the load time and insn->off
can be used to index into this array. ]
At the early stage of verifier, the verifier will collect all kernel
function calls into "struct bpf_kfunc_desc". Those
descriptors are stored in "prog->aux->kfunc_tab" and will
be available to the JIT. Since this "add" operation is similar
to the current "add_subprog()" and looking for the same insn->code,
they are done together in the new "add_subprog_and_kfunc()".
In the "do_check()" stage, the new "check_kfunc_call()" is added
to verify the kernel function call instruction:
1. Ensure the kernel function can be used by a particular BPF_PROG_TYPE.
A new bpf_verifier_ops "check_kfunc_call" is added to do that.
The bpf-tcp-cc struct_ops program will implement this function in
a later patch.
2. Call "btf_check_kfunc_args_match()" to ensure the regs can be
used as the args of a kernel function.
3. Mark the regs' type, subreg_def, and zext_dst.
At the later do_misc_fixups() stage, the new fixup_kfunc_call()
will replace the insn->imm with the function address (relative
to __bpf_call_base). If needed, the jit can find the btf_func_model
by calling the new bpf_jit_find_kfunc_model(prog, insn).
With the imm set to the function address, "bpftool prog dump xlated"
will be able to display the kernel function calls the same way as
it displays other bpf helper calls.
gpl_compatible program is required to call kernel function.
This feature currently requires JIT.
The verifier selftests are adjusted because of the changes in
the verbose log in add_subprog_and_kfunc().
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210325015142.1544736-1-kafai@fb.com
Ensure that BPF static linker preserves all DATASEC BTF types, even if some of
them might not have any variable information at all. This may happen if the
compiler promotes local initialized variable contents into .rodata section and
there are no global or static functions in the program.
For example,
$ cat t.c
struct t { char a; char b; char c; };
void bar(struct t*);
void find() {
struct t tmp = {1, 2, 3};
bar(&tmp);
}
$ clang -target bpf -O2 -g -S t.c
.long 104 # BTF_KIND_DATASEC(id = 8)
.long 251658240 # 0xf000000
.long 0
.ascii ".rodata" # string offset=104
$ clang -target bpf -O2 -g -c t.c
$ readelf -S t.o | grep data
[ 4] .rodata PROGBITS 0000000000000000 00000090
Fixes: 8fd27bf69b86 ("libbpf: Add BPF static linker BTF and BTF.ext support")
Reported-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20210326043036.3081011-1-andrii@kernel.org
Update links to point to blog posts that have some new updates and are
generally kept more up-to-date.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
libbpf_util.h was removed in 7e8bbe24cb8b ("libbpf: xsk: Move barriers from
libbpf_util.h to xsk.h") upstream, so remove it from the list of installable
headers.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Similar to
https://lore.kernel.org/bpf/20210313210920.1959628-2-andrii@kernel.org/
When DECLARE_LIBBPF_OPTS is used with inline field initialization, e.g:
DECLARE_LIBBPF_OPTS(btf_dump_emit_type_decl_opts, opts,
.field_name = var_ident,
.indent_level = 2,
.strip_mods = strip_mods,
);
and compiled in debug mode, the compiler generates code which
leaves the padding uninitialized and triggers errors within libbpf APIs
which require strict zero initialization of OPTS structs.
Adding anonymous padding field fixes the issue.
Fixes: 9f81654eebe8 ("libbpf: Expose BTF-to-C type declaration emitting API")
Suggested-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: KP Singh <kpsingh@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210319192117.2310658-1-kpsingh@kernel.org
Add .BTF and .BTF.ext static linking logic.
When multiple BPF object files are linked together, their respective .BTF and
.BTF.ext sections are merged together. BTF types are not just concatenated,
but also deduplicated. .BTF.ext data is grouped by type (func info, line info,
core_relos) and target section names, and then all the records are
concatenated together, preserving their relative order. All the BTF type ID
references and string offsets are updated as necessary, to take into account
possibly deduplicated strings and types.
BTF DATASEC types are handled specially. Their respective var_secinfos are
accumulated separately in special per-section data and then final DATASEC
types are emitted at the very end during bpf_linker__finalize() operation,
just before emitting final ELF output file.
BTF data can also provide "section annotations" for some extern variables.
Such concept is missing in ELF, but BTF will have DATASEC types for such
special extern datasections (e.g., .kconfig, .ksyms). Such sections are called
"ephemeral" internally. Internally linker will keep metadata for each such
section, collecting variables information, but those sections won't be emitted
into the final ELF file.
Also, given LLVM/Clang during compilation emits BTF DATASECS that are
incomplete, missing section size and variable offsets for static variables,
BPF static linker will initially fix up such DATASECs, using ELF symbols data.
The final DATASECs will preserve section sizes and all variable offsets. This
is handled correctly by libbpf already, so won't cause any new issues. On the
other hand, it's actually a nice property to have a complete BTF data without
runtime adjustments done during bpf_object__open() by libbpf. In that sense,
BPF static linker is also a BTF normalizer.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210318194036.3521577-8-andrii@kernel.org
Introduce BPF static linker APIs to libbpf. BPF static linker allows to
perform static linking of multiple BPF object files into a single combined
resulting object file, preserving all the BPF programs, maps, global
variables, etc.
Data sections (.bss, .data, .rodata, .maps, maps, etc) with the same name are
concatenated together. Similarly, code sections are also concatenated. All the
symbols and ELF relocations are also concatenated in their respective ELF
sections and are adjusted accordingly to the new object file layout.
Static variables and functions are handled correctly as well, adjusting BPF
instructions offsets to reflect new variable/function offset within the
combined ELF section. Such relocations are referencing STT_SECTION symbols and
that stays intact.
Data sections in different files can have different alignment requirements, so
that is taken care of as well, adjusting sizes and offsets as necessary to
satisfy both old and new alignment requirements.
DWARF data sections are stripped out, currently. As well as LLLVM_ADDRSIG
section, which is ignored by libbpf in bpf_object__open() anyways. So, in
a way, BPF static linker is an analogue to `llvm-strip -g`, which is a pretty
nice property, especially if resulting .o file is then used to generate BPF
skeleton.
Original string sections are ignored and instead we construct our own set of
unique strings using libbpf-internal `struct strset` API.
To reduce the size of the patch, all the .BTF and .BTF.ext processing was
moved into a separate patch.
The high-level API consists of just 4 functions:
- bpf_linker__new() creates an instance of BPF static linker. It accepts
output filename and (currently empty) options struct;
- bpf_linker__add_file() takes input filename and appends it to the already
processed ELF data; it can be called multiple times, one for each BPF
ELF object file that needs to be linked in;
- bpf_linker__finalize() needs to be called to dump final ELF contents into
the output file, specified when bpf_linker was created; after
bpf_linker__finalize() is called, no more bpf_linker__add_file() and
bpf_linker__finalize() calls are allowed, they will return error;
- regardless of whether bpf_linker__finalize() was called or not,
bpf_linker__free() will free up all the used resources.
Currently, BPF static linker doesn't resolve cross-object file references
(extern variables and/or functions). This will be added in the follow up patch
set.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210318194036.3521577-7-andrii@kernel.org
Add btf__add_type() API that performs shallow copy of a given BTF type from
the source BTF into the destination BTF. All the information and type IDs are
preserved, but all the strings encountered are added into the destination BTF
and corresponding offsets are rewritten. BTF type IDs are assumed to be
correct or such that will be (somehow) modified afterwards.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210318194036.3521577-6-andrii@kernel.org
Extract BTF logic for maintaining a set of strings data structure, used for
BTF strings section construction in writable mode, into separate re-usable
API. This data structure is going to be used by bpf_linker to maintains ELF
STRTAB section, which has the same layout as BTF strings section.
Suggested-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210318194036.3521577-5-andrii@kernel.org
Extract and generalize the logic to iterate BTF type ID and string offset
fields within BTF types and .BTF.ext data. Expose this internally in libbpf
for re-use by bpf_linker.
Additionally, complete strings deduplication handling for BTF.ext (e.g., CO-RE
access strings), which was previously missing. There previously was no
case of deduplicating .BTF.ext data, but bpf_linker is going to use it.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210318194036.3521577-3-andrii@kernel.org
Given that vmlinux.h is not compatible with headers like stddef.h, NULL poses
an annoying problem: it is defined as #define, so is not captured in BTF, so
is not emitted into vmlinux.h. This leads to users either sticking to explicit
0, or defining their own NULL (as progs/skb_pkt_end.c does).
But it's easy for bpf_helpers.h to provide (conditionally) NULL definition.
Similarly, KERNEL_VERSION is another commonly missed macro that came up
multiple times. So this patch adds both of them, along with offsetof(), that
also is typically defined in stddef.h, just like NULL.
This might cause compilation warning for existing BPF applications defining
their own NULL and/or KERNEL_VERSION already:
progs/skb_pkt_end.c:7:9: warning: 'NULL' macro redefined [-Wmacro-redefined]
#define NULL 0
^
/tmp/linux/tools/testing/selftests/bpf/tools/include/vmlinux.h:4:9: note: previous definition is here
#define NULL ((void *)0)
^
It is trivial to fix, though, so long-term benefits outweight temporary
inconveniences.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20210317200510.1354627-2-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Adding such anonymous padding fixes the issue with uninitialized portions of
bpf_xdp_set_link_opts when using LIBBPF_DECLARE_OPTS macro with inline field
initialization:
DECLARE_LIBBPF_OPTS(bpf_xdp_set_link_opts, opts, .old_fd = -1);
When such code is compiled in debug mode, compiler is generating code that
leaves padding bytes uninitialized, which triggers error inside libbpf APIs
that do strict zero initialization checks for OPTS structs.
Adding anonymous padding field fixes the issue.
Fixes: bd5ca3ef93cd ("libbpf: Add function to set link XDP fd while specifying old program")
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210313210920.1959628-2-andrii@kernel.org
Linux headers might pull 'linux/stddef.h' which defines
'__always_inline' as the following:
#ifndef __always_inline
#define __always_inline inline
#endif
This becomes an issue if the program picks up the 'linux/stddef.h'
definition as the macro now just hints inline to clang.
This change now enforces the proper definition for BPF programs
regardless of the include order.
Signed-off-by: Pedro Tammela <pctammela@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210314173839.457768-1-pctammela@gmail.com
In commit 291471dd1559 ("libbpf, xsk: Add libbpf_smp_store_release
libbpf_smp_load_acquire") linux/compiler.h was added as a dependency
to xsk.h, which is the user-facing API. This makes it harder for
userspace application to consume the library. Here the header
inclusion is removed, and instead {READ,WRITE}_ONCE() is added
explicitly.
Signed-off-by: Björn Töpel <bjorn.topel@intel.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210310080929.641212-2-bjorn.topel@gmail.com
The vmlinux.h generated from BTF is invalid when building
drivers/phy/ti/phy-gmii-sel.c with clang:
vmlinux.h:61702:27: error: array type has incomplete element type ‘struct reg_field’
61702 | const struct reg_field (*regfields)[3];
| ^~~~~~~~~
bpftool generates a forward declaration for this struct regfield, which
compilers aren't happy about. Here's a simplified reproducer:
struct inner {
int val;
};
struct outer {
struct inner (*ptr_to_array)[2];
} A;
After build with clang -> bpftool btf dump c -> clang/gcc:
./def-clang.h:11:23: error: array has incomplete element type 'struct inner'
struct inner (*ptr_to_array)[2];
Member ptr_to_array of struct outer is a pointer to an array of struct
inner. In the DWARF generated by clang, struct outer appears before
struct inner, so when converting BTF of struct outer into C, bpftool
issues a forward declaration to struct inner. With GCC the DWARF info is
reversed so struct inner gets fully defined.
That forward declaration is not sufficient when compilers handle an
array of the struct, even when it's only used through a pointer. Note
that we can trigger the same issue with an intermediate typedef:
struct inner {
int val;
};
typedef struct inner inner2_t[2];
struct outer {
inner2_t *ptr_to_array;
} A;
Becomes:
struct inner;
typedef struct inner inner2_t[2];
And causes:
./def-clang.h:10:30: error: array has incomplete element type 'struct inner'
typedef struct inner inner2_t[2];
To fix this, clear through_ptr whenever we encounter an intermediate
array, to make the inner struct part of a strong link and force full
declaration.
Fixes: 351131b51c7a ("libbpf: add btf_dump API for BTF-to-C conversion")
Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210319112554.794552-2-jean-philippe@linaro.org
Allow to pass sk_lookup programs to PROG_TEST_RUN. User space
provides the full bpf_sk_lookup struct as context. Since the
context includes a socket pointer that can't be exposed
to user space we define that PROG_TEST_RUN returns the cookie
of the selected socket or zero in place of the socket pointer.
We don't support testing programs that select a reuseport socket,
since this would mean running another (unrelated) BPF program
from the sk_lookup test handler.
Signed-off-by: Lorenz Bauer <lmb@cloudflare.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210303101816.36774-3-lmb@cloudflare.com
xsk_lookup_bpf_maps, based on prog_fd, looks whether current prog has a
reference to XSKMAP. BPF prog can include insns that work on various BPF
maps and this is covered by iterating through map_ids.
The bpf_map_info that is passed to bpf_obj_get_info_by_fd for filling
needs to be cleared at each iteration, so that it doesn't contain any
outdated fields and that is currently missing in the function of
interest.
To fix that, zero-init map_info via memset before each
bpf_obj_get_info_by_fd call.
Also, since the area of this code is touched, in general strcmp is
considered harmful, so let's convert it to strncmp and provide the
size of the array name for current map_info.
While at it, do s/continue/break/ once we have found the xsks_map to
terminate the search.
Fixes: 5750902a6e9b ("libbpf: proper XSKMAP cleanup")
Signed-off-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Björn Töpel <bjorn.topel@intel.com>
Link: https://lore.kernel.org/bpf/20210303185636.18070-4-maciej.fijalkowski@intel.com
The logic follows that of BTF_KIND_INT most of the time. Sanitization
replaces BTF_KIND_FLOATs with equally-sized empty BTF_KIND_STRUCTs on
older kernels, for example, the following:
[4] FLOAT 'float' size=4
becomes the following:
[4] STRUCT '(anon)' size=4 vlen=0
With dwarves patch [1] and this patch, the older kernels, which were
failing with the floating-point-related errors, will now start working
correctly.
[1] https://github.com/iii-i/dwarves/commit/btf-kind-float-v2
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210226202256.116518-4-iii@linux.ibm.com
Syncing latest libbpf commits from kernel repository.
Baseline bpf-next commit: 86ce322d21eb032ed8fdd294d0fb095d2debb430
Checkpoint bpf-next commit: 303dcc25b5c782547eb13b9f29426de843dd6f34
Baseline bpf commit: 78031381ae9c88f4f914d66154f4745122149c58
Checkpoint bpf commit: 6185266c5a853bb0f2a459e3ff594546f277609b
Alexei Starovoitov (1):
bpf: Count the number of times recursion was prevented
Florent Revest (2):
bpf: Be less specific about socket cookies guarantees
bpf: Expose bpf_get_socket_cookie to tracing programs
Hangbin Liu (1):
bpf: Remove blank line in bpf helper description comment
Jesper Dangaard Brouer (2):
bpf: bpf_fib_lookup return MTU value as output when looked up
bpf: Add BPF-helper for MTU checking
Jonas Bonn (1):
Revert "GTP: add support for flow based tunneling API"
Martin KaFai Lau (1):
libbpf: Ignore non function pointer member in struct_ops
Stanislav Fomichev (1):
libbpf: Use AF_LOCAL instead of AF_INET in xsk.c
Yonghong Song (3):
bpf: Add bpf_for_each_map_elem() helper
libbpf: Move function is_ldimm64() earlier in libbpf.c
libbpf: Support subprog address relocation
include/uapi/linux/bpf.h | 140 +++++++++++++++++++++++++++++++++--
include/uapi/linux/if_link.h | 1 -
src/libbpf.c | 98 +++++++++++++++++++-----
src/xsk.c | 2 +-
4 files changed, 213 insertions(+), 28 deletions(-)
--
2.24.1
A new relocation RELO_SUBPROG_ADDR is added to capture
subprog addresses loaded with ld_imm64 insns. Such ld_imm64
insns are marked with BPF_PSEUDO_FUNC and will be passed to
kernel. For bpf_for_each_map_elem() case, kernel will
check that the to-be-used subprog address must be a static
function and replace it with proper actual jited func address.
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210226204930.3885367-1-yhs@fb.com
The bpf_for_each_map_elem() helper is introduced which
iterates all map elements with a callback function. The
helper signature looks like
long bpf_for_each_map_elem(map, callback_fn, callback_ctx, flags)
and for each map element, the callback_fn will be called. For example,
like hashmap, the callback signature may look like
long callback_fn(map, key, val, callback_ctx)
There are two known use cases for this. One is from upstream ([1]) where
a for_each_map_elem helper may help implement a timeout mechanism
in a more generic way. Another is from our internal discussion
for a firewall use case where a map contains all the rules. The packet
data can be compared to all these rules to decide allow or deny
the packet.
For array maps, users can already use a bounded loop to traverse
elements. Using this helper can avoid using bounded loop. For other
type of maps (e.g., hash maps) where bounded loop is hard or
impossible to use, this helper provides a convenient way to
operate on all elements.
For callback_fn, besides map and map element, a callback_ctx,
allocated on caller stack, is also passed to the callback
function. This callback_ctx argument can provide additional
input and allow to write to caller stack for output.
If the callback_fn returns 0, the helper will iterate through next
element if available. If the callback_fn returns 1, the helper
will stop iterating and returns to the bpf program. Other return
values are not used for now.
Currently, this helper is only available with jit. It is possible
to make it work with interpreter with so effort but I leave it
as the future work.
[1]: https://lore.kernel.org/bpf/20210122205415.113822-1-xiyou.wangcong@gmail.com/
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210226204925.3884923-1-yhs@fb.com
Commit 34b2021cc616 ("bpf: Add BPF-helper for MTU checking") added an extra
blank line in bpf helper description. This will make bpf_helpers_doc.py stop
building bpf_helper_defs.h immediately after bpf_check_mtu(), which will
affect future added functions.
Fixes: 34b2021cc616 ("bpf: Add BPF-helper for MTU checking")
Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>
Link: https://lore.kernel.org/bpf/20210223131457.1378978-1-liuhangbin@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This BPF-helper bpf_check_mtu() works for both XDP and TC-BPF programs.
The SKB object is complex and the skb->len value (accessible from
BPF-prog) also include the length of any extra GRO/GSO segments, but
without taking into account that these GRO/GSO segments get added
transport (L4) and network (L3) headers before being transmitted. Thus,
this BPF-helper is created such that the BPF-programmer don't need to
handle these details in the BPF-prog.
The API is designed to help the BPF-programmer, that want to do packet
context size changes, which involves other helpers. These other helpers
usually does a delta size adjustment. This helper also support a delta
size (len_diff), which allow BPF-programmer to reuse arguments needed by
these other helpers, and perform the MTU check prior to doing any actual
size adjustment of the packet context.
It is on purpose, that we allow the len adjustment to become a negative
result, that will pass the MTU check. This might seem weird, but it's not
this helpers responsibility to "catch" wrong len_diff adjustments. Other
helpers will take care of these checks, if BPF-programmer chooses to do
actual size adjustment.
V14:
- Improve man-page desc of len_diff.
V13:
- Enforce flag BPF_MTU_CHK_SEGS cannot use len_diff.
V12:
- Simplify segment check that calls skb_gso_validate_network_len.
- Helpers should return long
V9:
- Use dev->hard_header_len (instead of ETH_HLEN)
- Annotate with unlikely req from Daniel
- Fix logic error using skb_gso_validate_network_len from Daniel
V6:
- Took John's advice and dropped BPF_MTU_CHK_RELAX
- Returned MTU is kept at L3-level (like fib_lookup)
V4: Lot of changes
- ifindex 0 now use current netdev for MTU lookup
- rename helper from bpf_mtu_check to bpf_check_mtu
- fix bug for GSO pkt length (as skb->len is total len)
- remove __bpf_len_adj_positive, simply allow negative len adj
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/161287790461.790810.3429728639563297353.stgit@firesoul
The BPF-helpers for FIB lookup (bpf_xdp_fib_lookup and bpf_skb_fib_lookup)
can perform MTU check and return BPF_FIB_LKUP_RET_FRAG_NEEDED. The BPF-prog
don't know the MTU value that caused this rejection.
If the BPF-prog wants to implement PMTU (Path MTU Discovery) (rfc1191) it
need to know this MTU value for the ICMP packet.
Patch change lookup and result struct bpf_fib_lookup, to contain this MTU
value as output via a union with 'tot_len' as this is the value used for
the MTU lookup.
V5:
- Fixed uninit value spotted by Dan Carpenter.
- Name struct output member mtu_result
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/161287789952.790810.13134700381067698781.stgit@firesoul
When libbpf initializes the kernel's struct_ops in
"bpf_map__init_kern_struct_ops()", it enforces all
pointer types must be a function pointer and rejects
others. It turns out to be too strict. For example,
when directly using "struct tcp_congestion_ops" from vmlinux.h,
it has a "struct module *owner" member and it is set to NULL
in a bpf_tcp_cc.o.
Instead, it only needs to ensure the member is a function
pointer if it has been set (relocated) to a bpf-prog.
This patch moves the "btf_is_func_proto(kern_mtype)" check
after the existing "if (!prog) { continue; }". The original debug
message in "if (!prog) { continue; }" is also removed since it is
no longer valid. Beside, there is a later debug message to tell
which function pointer is set.
The "btf_is_func_proto(mtype)" has already been guaranteed
in "bpf_object__collect_st_ops_relos()" which has been run
before "bpf_map__init_kern_struct_ops()". Thus, this check
is removed.
v2:
- Remove outdated debug message (Andrii)
Remove because there is a later debug message to tell
which function pointer is set.
- Following mtype->type is no longer needed. Remove:
"skip_mods_and_typedefs(btf, mtype->type, &mtype_id)"
- Do "if (!prog)" test before skip_mods_and_typedefs.
Fixes: 590a00888250 ("bpf: libbpf: Add STRUCT_OPS support")
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210212021030.266932-1-kafai@fb.com
This reverts commit 9ab7e76aefc97a9aa664accb59d6e8dc5e52514a.
This patch was committed without maintainer approval and despite a number
of unaddressed concerns from review. There are several issues that
impede the acceptance of this patch and that make a reversion of this
particular instance of these changes the best way forward:
i) the patch contains several logically separate changes that would be
better served as smaller patches (for review purposes)
ii) functionality like the handling of end markers has been introduced
without further explanation
iii) symmetry between the handling of GTPv0 and GTPv1 has been
unnecessarily broken
iv) the patchset produces 'broken' packets when extension headers are
included
v) there are no available userspace tools to allow for testing this
functionality
vi) there is an unaddressed Coverity report against the patch concering
memory leakage
vii) most importantly, the patch contains a large amount of superfluous
churn that impedes other ongoing work with this driver
This patch will be reworked into a series that aligns with other
ongoing work and facilitates review.
Signed-off-by: Jonas Bonn <jonas@norrbonn.se>
Acked-by: Harald Welte <laforge@gnumonks.org>
Acked-by: Pravin B Shelar <pshelar@ovn.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Clang 13 regressed BPF code generation causing some of BPF selftests to fail.
Until that is mitigated, stick to version 12.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Clang 13 became the new nightly version, so switch to it. Also do vmlinux
compilation with a bit more parallelism. And account python-docutils
installation as part of selftests build.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Syncing latest libbpf commits from kernel repository.
Baseline bpf-next commit: 3db1a3fa98808aa90f95ec3e0fa2fc7abf28f5c9
Checkpoint bpf-next commit: 86ce322d21eb032ed8fdd294d0fb095d2debb430
Baseline bpf commit: 1a3449c19407a28f7019a887cdf0d6ba2444751a
Checkpoint bpf commit: 78031381ae9c88f4f914d66154f4745122149c58
Andrii Nakryiko (5):
libbpf: Add user-space variants of BPF_CORE_READ() family of macros
libbpf: Add non-CO-RE variants of BPF_CORE_READ() macro family
libbpf: Clarify kernel type use with USER variants of CORE reading
macros
libbpf: Support kernel module ksym externs
libbpf: Allow loading empty BTFs
Björn Töpel (1):
libbpf, xsk: Select AF_XDP BPF program based on kernel version
Brendan Jackman (4):
bpf: Clarify return value of probe str helpers
bpf: Rename BPF_XADD and prepare to encode other atomics in .imm
bpf: Add BPF_FETCH field / create atomic_fetch_add instruction
bpf: Add instructions for atomic_[cmp]xchg
Ian Rogers (1):
bpf, libbpf: Avoid unused function warning on bpf_tail_call_static
Jiri Olsa (1):
libbpf: Use string table index from index table if needed
Pravin B Shelar (1):
GTP: add support for flow based tunneling API
include/uapi/linux/bpf.h | 20 +++--
include/uapi/linux/if_link.h | 1 +
src/bpf_core_read.h | 169 +++++++++++++++++++++++++++--------
src/bpf_helpers.h | 2 +-
src/btf.c | 17 ++--
src/libbpf.c | 50 +++++++----
src/xsk.c | 81 ++++++++++++++++-
7 files changed, 265 insertions(+), 75 deletions(-)
--
2.24.1
For very large ELF objects (with many sections), we could
get special value SHN_XINDEX (65535) for elf object's string
table index - e_shstrndx.
Call elf_getshdrstrndx to get the proper string table index,
instead of reading it directly from ELF header.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210121202203.9346-4-jolsa@kernel.org
Empty BTFs do come up (e.g., simple kernel modules with no new types and
strings, compared to the vmlinux BTF) and there is nothing technically wrong
with them. So remove unnecessary check preventing loading empty BTFs.
Fixes: d8123624506c ("libbpf: Fix BTF data layout checks and allow empty BTF")
Reported-by: Christopher William Snowhill <chris@kode54.net>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20210110070341.1380086-2-andrii@kernel.org
Following patch add support for flow based tunneling API
to send and recv GTP tunnel packet over tunnel metadata API.
This would allow this device integration with OVS or eBPF using
flow based tunneling APIs.
Signed-off-by: Pravin B Shelar <pbshelar@fb.com>
Link: https://lore.kernel.org/r/20210110070021.26822-1-pbshelar@fb.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This adds two atomic opcodes, both of which include the BPF_FETCH
flag. XCHG without the BPF_FETCH flag would naturally encode
atomic_set. This is not supported because it would be of limited
value to userspace (it doesn't imply any barriers). CMPXCHG without
BPF_FETCH woulud be an atomic compare-and-write. We don't have such
an operation in the kernel so it isn't provided to BPF either.
There are two significant design decisions made for the CMPXCHG
instruction:
- To solve the issue that this operation fundamentally has 3
operands, but we only have two register fields. Therefore the
operand we compare against (the kernel's API calls it 'old') is
hard-coded to be R0. x86 has similar design (and A64 doesn't
have this problem).
A potential alternative might be to encode the other operand's
register number in the immediate field.
- The kernel's atomic_cmpxchg returns the old value, while the C11
userspace APIs return a boolean indicating the comparison
result. Which should BPF do? A64 returns the old value. x86 returns
the old value in the hard-coded register (and also sets a
flag). That means return-old-value is easier to JIT, so that's
what we use.
Signed-off-by: Brendan Jackman <jackmanb@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20210114181751.768687-8-jackmanb@google.com
A subsequent patch will add additional atomic operations. These new
operations will use the same opcode field as the existing XADD, with
the immediate discriminating different operations.
In preparation, rename the instruction mode BPF_ATOMIC and start
calling the zero immediate BPF_ADD.
This is possible (doesn't break existing valid BPF progs) because the
immediate field is currently reserved MBZ and BPF_ADD is zero.
All uses are removed from the tree but the BPF_XADD definition is
kept around to avoid breaking builds for people including kernel
headers.
Signed-off-by: Brendan Jackman <jackmanb@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Björn Töpel <bjorn.topel@gmail.com>
Link: https://lore.kernel.org/bpf/20210114181751.768687-5-jackmanb@google.com
Add support for searching for ksym externs not just in vmlinux BTF, but across
all module BTFs, similarly to how it's done for CO-RE relocations. Kernels
that expose module BTFs through sysfs are assumed to support new ldimm64
instruction extension with BTF FD provided in insn[1].imm field, so no extra
feature detection is performed.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Acked-by: Hao Luo <haoluo@google.com>
Link: https://lore.kernel.org/bpf/20210112075520.4103414-7-andrii@kernel.org
Add comments clarifying that USER variants of CO-RE reading macro are still
only going to work with kernel types, defined in kernel or kernel module BTF.
This should help preventing invalid use of those macro to read user-defined
types (which doesn't work with CO-RE).
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210108194408.3468860-1-andrii@kernel.org
BPF_CORE_READ(), in addition to handling CO-RE relocations, also allows much
nicer way to read data structures with nested pointers. Instead of writing
a sequence of bpf_probe_read() calls to follow links, one can just write
BPF_CORE_READ(a, b, c, d) to effectively do a->b->c->d read. This is a welcome
ability when porting BCC code, which (in most cases) allows exactly the
intuitive a->b->c->d variant.
This patch adds non-CO-RE variants of BPF_CORE_READ() family of macros for
cases where CO-RE is not supported (e.g., old kernels). In such cases, the
property of shortening a sequence of bpf_probe_read()s to a simple
BPF_PROBE_READ(a, b, c, d) invocation is still desirable, especially when
porting BCC code to libbpf. Yet, no CO-RE relocation is going to be emitted.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20201218235614.2284956-3-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Add BPF_CORE_READ_USER(), BPF_CORE_READ_USER_STR() and their _INTO()
variations to allow reading CO-RE-relocatable kernel data structures from the
user-space. One of such cases is reading input arguments of syscalls, while
reaping the benefits of CO-RE relocations w.r.t. handling 32/64 bit
conversions and handling missing/new fields in UAPI data structs.
Suggested-by: Gilad Reti <gilad.reti@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20201218235614.2284956-2-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
LIBBPF_APILIBBPF_DEPRECATED("btf_ext__reloc_func_info was never meant as a public API and has wrong assumptions embedded in it; it will be removed in the future libbpf versions")
intbtf_ext__reloc_func_info(conststructbtf*btf,
conststructbtf_ext*btf_ext,
@@ -86,15 +169,40 @@ int btf_ext__reloc_line_info(const struct btf *btf,
Some files were not shown because too many files have changed in this diff
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