The common use-case in production is to have multiple cgroup-bpf
programs per attach type that cover multiple use-cases. Such programs
are attached with BPF_F_ALLOW_MULTI and can be maintained by different
people.
Order of programs usually matters, for example imagine two egress
programs: the first one drops packets and the second one counts packets.
If they're swapped the result of counting program will be different.
It brings operational challenges with updating cgroup-bpf program(s)
attached with BPF_F_ALLOW_MULTI since there is no way to replace a
program:
* One way to update is to detach all programs first and then attach the
new version(s) again in the right order. This introduces an
interruption in the work a program is doing and may not be acceptable
(e.g. if it's egress firewall);
* Another way is attach the new version of a program first and only then
detach the old version. This introduces the time interval when two
versions of same program are working, what may not be acceptable if a
program is not idempotent. It also imposes additional burden on
program developers to make sure that two versions of their program can
co-exist.
Solve the problem by introducing a "replace" mode in BPF_PROG_ATTACH
command for cgroup-bpf programs being attached with BPF_F_ALLOW_MULTI
flag. This mode is enabled by newly introduced BPF_F_REPLACE attach flag
and bpf_attr.replace_bpf_fd attribute to pass fd of the old program to
replace
That way user can replace any program among those attached with
BPF_F_ALLOW_MULTI flag without the problems described above.
Details of the new API:
* If BPF_F_REPLACE is set but replace_bpf_fd doesn't have valid
descriptor of BPF program, BPF_PROG_ATTACH will return corresponding
error (EINVAL or EBADF).
* If replace_bpf_fd has valid descriptor of BPF program but such a
program is not attached to specified cgroup, BPF_PROG_ATTACH will
return ENOENT.
BPF_F_REPLACE is introduced to make the user intent clear, since
replace_bpf_fd alone can't be used for this (its default value, 0, is a
valid fd). BPF_F_REPLACE also makes it possible to extend the API in the
future (e.g. add BPF_F_BEFORE and BPF_F_AFTER if needed).
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Andrii Narkyiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/30cd850044a0057bdfcaaf154b7d2f39850ba813.1576741281.git.rdna@fb.com
Add support for extern variables, provided to BPF program by libbpf. Currently
the following extern variables are supported:
- LINUX_KERNEL_VERSION; version of a kernel in which BPF program is
executing, follows KERNEL_VERSION() macro convention, can be 4- and 8-byte
long;
- CONFIG_xxx values; a set of values of actual kernel config. Tristate,
boolean, strings, and integer values are supported.
Set of possible values is determined by declared type of extern variable.
Supported types of variables are:
- Tristate values. Are represented as `enum libbpf_tristate`. Accepted values
are **strictly** 'y', 'n', or 'm', which are represented as TRI_YES, TRI_NO,
or TRI_MODULE, respectively.
- Boolean values. Are represented as bool (_Bool) types. Accepted values are
'y' and 'n' only, turning into true/false values, respectively.
- Single-character values. Can be used both as a substritute for
bool/tristate, or as a small-range integer:
- 'y'/'n'/'m' are represented as is, as characters 'y', 'n', or 'm';
- integers in a range [-128, 127] or [0, 255] (depending on signedness of
char in target architecture) are recognized and represented with
respective values of char type.
- Strings. String values are declared as fixed-length char arrays. String of
up to that length will be accepted and put in first N bytes of char array,
with the rest of bytes zeroed out. If config string value is longer than
space alloted, it will be truncated and warning message emitted. Char array
is always zero terminated. String literals in config have to be enclosed in
double quotes, just like C-style string literals.
- Integers. 8-, 16-, 32-, and 64-bit integers are supported, both signed and
unsigned variants. Libbpf enforces parsed config value to be in the
supported range of corresponding integer type. Integers values in config can
be:
- decimal integers, with optional + and - signs;
- hexadecimal integers, prefixed with 0x or 0X;
- octal integers, starting with 0.
Config file itself is searched in /boot/config-$(uname -r) location with
fallback to /proc/config.gz, unless config path is specified explicitly
through bpf_object_open_opts' kernel_config_path option. Both gzipped and
plain text formats are supported. Libbpf adds explicit dependency on zlib
because of this, but this shouldn't be a problem, given libelf already depends
on zlib.
All detected extern variables, are put into a separate .extern internal map.
It, similarly to .rodata map, is marked as read-only from BPF program side, as
well as is frozen on load. This allows BPF verifier to track extern values as
constants and perform enhanced branch prediction and dead code elimination.
This can be relied upon for doing kernel version/feature detection and using
potentially unsupported field relocations or BPF helpers in a CO-RE-based BPF
program, while still having a single version of BPF program running on old and
new kernels. Selftests are validating this explicitly for unexisting BPF
helper.
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20191214014710.3449601-3-andriin@fb.com
Add ability to memory-map contents of BPF array map. This is extremely useful
for working with BPF global data from userspace programs. It allows to avoid
typical bpf_map_{lookup,update}_elem operations, improving both performance
and usability.
There had to be special considerations for map freezing, to avoid having
writable memory view into a frozen map. To solve this issue, map freezing and
mmap-ing is happening under mutex now:
- if map is already frozen, no writable mapping is allowed;
- if map has writable memory mappings active (accounted in map->writecnt),
map freezing will keep failing with -EBUSY;
- once number of writable memory mappings drops to zero, map freezing can be
performed again.
Only non-per-CPU plain arrays are supported right now. Maps with spinlocks
can't be memory mapped either.
For BPF_F_MMAPABLE array, memory allocation has to be done through vmalloc()
to be mmap()'able. We also need to make sure that array data memory is
page-sized and page-aligned, so we over-allocate memory in such a way that
struct bpf_array is at the end of a single page of memory with array->value
being aligned with the start of the second page. On deallocation we need to
accomodate this memory arrangement to free vmalloc()'ed memory correctly.
One important consideration regarding how memory-mapping subsystem functions.
Memory-mapping subsystem provides few optional callbacks, among them open()
and close(). close() is called for each memory region that is unmapped, so
that users can decrease their reference counters and free up resources, if
necessary. open() is *almost* symmetrical: it's called for each memory region
that is being mapped, **except** the very first one. So bpf_map_mmap does
initial refcnt bump, while open() will do any extra ones after that. Thus
number of close() calls is equal to number of open() calls plus one more.
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Song Liu <songliubraving@fb.com>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Link: https://lore.kernel.org/bpf/20191117172806.2195367-4-andriin@fb.com
The current bpf_probe_read() and bpf_probe_read_str() helpers are broken
in that they assume they can be used for probing memory access for kernel
space addresses /as well as/ user space addresses.
However, plain use of probe_kernel_read() for both cases will attempt to
always access kernel space address space given access is performed under
KERNEL_DS and some archs in-fact have overlapping address spaces where a
kernel pointer and user pointer would have the /same/ address value and
therefore accessing application memory via bpf_probe_read{,_str}() would
read garbage values.
Lets fix BPF side by making use of recently added 3d7081822f7f ("uaccess:
Add non-pagefault user-space read functions"). Unfortunately, the only way
to fix this status quo is to add dedicated bpf_probe_read_{user,kernel}()
and bpf_probe_read_{user,kernel}_str() helpers. The bpf_probe_read{,_str}()
helpers are kept as-is to retain their current behavior.
The two *_user() variants attempt the access always under USER_DS set, the
two *_kernel() variants will -EFAULT when accessing user memory if the
underlying architecture has non-overlapping address ranges, also avoiding
throwing the kernel warning via 00c42373d397 ("x86-64: add warning for
non-canonical user access address dereferences").
Fixes: a5e8c07059d0 ("bpf: add bpf_probe_read_str helper")
Fixes: 2541517c32be ("tracing, perf: Implement BPF programs attached to kprobes")
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/796ee46e948bc808d54891a1108435f8652c6ca4.1572649915.git.daniel@iogearbox.net
Introduce new helper that reuses existing skb perf_event output
implementation, but can be called from raw_tracepoint programs
that receive 'struct sk_buff *' as tracepoint argument or
can walk other kernel data structures to skb pointer.
In order to do that teach verifier to resolve true C types
of bpf helpers into in-kernel BTF ids.
The type of kernel pointer passed by raw tracepoint into bpf
program will be tracked by the verifier all the way until
it's passed into helper function.
For example:
kfree_skb() kernel function calls trace_kfree_skb(skb, loc);
bpf programs receives that skb pointer and may eventually
pass it into bpf_skb_output() bpf helper which in-kernel is
implemented via bpf_skb_event_output() kernel function.
Its first argument in the kernel is 'struct sk_buff *'.
The verifier makes sure that types match all the way.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20191016032505.2089704-11-ast@kernel.org
Add attach_btf_id attribute to prog_load command.
It's similar to existing expected_attach_type attribute which is
used in several cgroup based program types.
Unfortunately expected_attach_type is ignored for
tracing programs and cannot be reused for new purpose.
Hence introduce attach_btf_id to verify bpf programs against
given in-kernel BTF type id at load time.
It is strictly checked to be valid for raw_tp programs only.
In a later patches it will become:
btf_id == 0 semantics of existing raw_tp progs.
btd_id > 0 raw_tp with BTF and additional type safety.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20191016032505.2089704-5-ast@kernel.org
Various small fixes to BPF helper documentation comments, enabling
automatic header generation with a list of BPF helpers.
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This patch adds a 'flags' field to the umem_config and umem_reg structs.
This will allow for more options to be added for configuring umems.
The first use for the flags field is to add a flag for unaligned chunks
mode. These flags can either be user-provided or filled with a default.
Since we change the size of the xsk_umem_config struct, we need to version
the ABI. This patch includes the ABI versioning for xsk_umem__create. The
Makefile was also updated to handle multiple function versions in
check-abi.
Signed-off-by: Kevin Laatz <kevin.laatz@intel.com>
Signed-off-by: Ciara Loftus <ciara.loftus@intel.com>
Acked-by: Jonathan Lemon <jonathan.lemon@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Synchronise the bpf.h header under tools, to report the addition of the
new BPF_BTF_GET_NEXT_ID syscall command for bpf().
Signed-off-by: Quentin Monnet <quentin.monnet@netronome.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit adds support for the new need_wakeup flag in AF_XDP. The
xsk_socket__create function is updated to handle this and a new
function is introduced called xsk_ring_prod__needs_wakeup(). This
function can be used by the application to check if Rx and/or Tx
processing needs to be explicitly woken up.
Signed-off-by: Magnus Karlsson <magnus.karlsson@intel.com>
Acked-by: Jonathan Lemon <jonathan.lemon@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Pull in updates in BPF helper function description.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Sync updated documentation for bpf_redirect_map.
Sync the bpf_tcp_gen_syncookie helper function definition with the one
in tools/uapi.
Signed-off-by: Petar Penkov <ppenkov@google.com>
Reviewed-by: Lorenz Bauer <lmb@cloudflare.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This adds the devmap_hash BPF map type to the uapi headers in tools/.
Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Acked-by: Yonghong Song <yhs@fb.com>
Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Update bpf_sock_addr comments to indicate support for 8-byte reads
from user_ip6 and msg_src_ip6.
Cc: Yonghong Song <yhs@fb.com>
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Merge commit 1c8c5a9d38f60 ("Merge
git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next") undid the
fix from commit 36f9814a494 ("bpf: fix uapi hole for 32 bit compat
applications") by taking the gpl_compatible 1-bit field definition from
commit b85fab0e67b162 ("bpf: Add gpl_compatible flag to struct
bpf_prog_info") as is. That breaks architectures with 16-bit alignment
like m68k. Add 31-bit pad after gpl_compatible to restore alignment of
following fields.
Thanks to Dmitry V. Levin his analysis of this bug history.
Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Acked-by: Song Liu <songliubraving@fb.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Convert the cgroup-v1 files to ReST format, in order to
allow a later addition to the admin-guide.
The conversion is actually:
- add blank lines and identation in order to identify paragraphs;
- fix tables markups;
- add some lists markups;
- mark literal blocks;
- adjust title markups.
At its new index.rst, let's add a :orphan: while this is not linked to
the main index.rst file, in order to avoid build warnings.
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
Export new prog type and hook points to the libbpf.
Cc: Andrii Nakryiko <andriin@fb.com>
Cc: Martin Lau <kafai@fb.com>
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Make it possible for the application to determine whether the AF_XDP
socket is running in zero-copy mode. To achieve this, add a new
getsockopt option XDP_OPTIONS that returns flags. The only flag
supported for now is the zero-copy mode indicator.
Signed-off-by: Maxim Mikityanskiy <maximmi@mellanox.com>
Signed-off-by: Tariq Toukan <tariqt@mellanox.com>
Acked-by: Saeed Mahameed <saeedm@mellanox.com>
Acked-by: Björn Töpel <bjorn.topel@intel.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Currently, gratuitous ARP/ND packets are sent every `miimon'
milliseconds. This commit allows a user to specify a custom delay
through a new option, `peer_notif_delay'.
Like for `updelay' and `downdelay', this delay should be a multiple of
`miimon' to avoid managing an additional work queue. The configuration
logic is copied from `updelay' and `downdelay'. However, the default
value cannot be set using a module parameter: Netlink or sysfs should
be used to configure this feature.
When setting `miimon' to 100 and `peer_notif_delay' to 500, we can
observe the 500 ms delay is respected:
20:30:19.354693 ARP, Request who-has 203.0.113.10 tell 203.0.113.10, length 28
20:30:19.874892 ARP, Request who-has 203.0.113.10 tell 203.0.113.10, length 28
20:30:20.394919 ARP, Request who-has 203.0.113.10 tell 203.0.113.10, length 28
20:30:20.914963 ARP, Request who-has 203.0.113.10 tell 203.0.113.10, length 28
In bond_mii_monitor(), I have tried to keep the lock logic readable.
The change is due to the fact we cannot rely on a notification to
lower the value of `bond->send_peer_notif' as `NETDEV_NOTIFY_PEERS' is
only triggered once every N times, while we need to decrement the
counter each time.
iproute2 also needs to be updated to be able to specify this new
attribute through `ip link'.
Signed-off-by: Vincent Bernat <vincent@bernat.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
Sync the changes to the flags made in "bpf: simplify definition of
BPF_FIB_LOOKUP related flags" with the BPF UAPI headers.
Doing in a separate commit to ease syncing of github/libbpf.
Signed-off-by: Martynas Pumputis <m@lambda.lt>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Sync BPF uapi header in order to pull in BPF_CGROUP_UDP{4,6}_RECVMSG
attach types. This is done and preferred as an extra patch in order
to ease sync of libbpf.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrey Ignatov <rdna@fb.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Add sk to struct bpf_sock_addr and struct bpf_sock_ops.
Cc: Martin Lau <kafai@fb.com>
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Sync new bpf prog load flag "BPF_F_TEST_RND_HI32" to tools/.
Signed-off-by: Jiong Wang <jiong.wang@netronome.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
The bpf uapi header include/uapi/linux/bpf.h is sync'ed
to tools/include/uapi/linux/bpf.h.
Acked-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Synchronise the bpf.h header under tools, to report the fixes and
additions recently brought to the documentation for the BPF helpers.
Signed-off-by: Quentin Monnet <quentin.monnet@netronome.com>
Acked-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
This adds BPF_PROG_TYPE_RAW_TRACEPOINT_WRITABLE, and fixes up the
error: enumeration value ‘BPF_PROG_TYPE_RAW_TRACEPOINT_WRITABLE’ not handled in switch [-Werror=switch-enum]
build errors it would otherwise cause in libbpf.
Signed-off-by: Matt Mullins <mmullins@fb.com>
Acked-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Sync include/uapi/linux/bpf.h with tools/ equivalent to add
BPF_F_ADJ_ROOM_ENCAP_L2(len) macro.
Signed-off-by: Alan Maguire <alan.maguire@oracle.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Support recently introduced input/output context for test runs.
We extend only bpf_prog_test_run_xattr. bpf_prog_test_run is
unextendable and left as is.
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Pull in latest changes from both headers, so we can make use of
them in libbpf.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Sync include/uapi/linux/bpf.h with tools/
Changes
v1->v2:
- BPF_F_ADJ_ROOM_MASK moved, no longer in this commit
v2->v3:
- BPF_F_ADJ_ROOM_ENCAP_L3_MASK moved, no longer in this commit
Signed-off-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
