Commit Graph

1519 Commits

Author SHA1 Message Date
Cryolitia PukNgae
83fe1f4494 libbpf: Add documentation to version and error API functions
Add documentation for the following API functions:

- libbpf_major_version()
- libbpf_minor_version()
- libbpf_version_string()
- libbpf_strerror()

Signed-off-by: Cryolitia PukNgae <cryolitia@uniontech.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20250820-libbpf-doc-1-v1-1-13841f25a134@uniontech.com
2025-08-21 13:39:29 -07:00
Mykyta Yatsenko
9f8984fba5 libbpf: Export bpf_object__prepare symbol
Add missing LIBBPF_API macro for bpf_object__prepare function to enable
its export. libbpf.map had bpf_object__prepare already listed.

Fixes: 1315c28ed809 ("libbpf: Split bpf object load into prepare/load")
Signed-off-by: Mykyta Yatsenko <yatsenko@meta.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20250819215119.37795-1-mykyta.yatsenko5@gmail.com
2025-08-21 13:39:29 -07:00
Yureka Lilian
04a23358c7 libbpf: Fix reuse of DEVMAP
Previously, re-using pinned DEVMAP maps would always fail, because
get_map_info on a DEVMAP always returns flags with BPF_F_RDONLY_PROG set,
but BPF_F_RDONLY_PROG being set on a map during creation is invalid.

Thus, ignore the BPF_F_RDONLY_PROG flag in the flags returned from
get_map_info when checking for compatibility with an existing DEVMAP.

The same problem is handled in a third-party ebpf library:
- https://github.com/cilium/ebpf/issues/925
- https://github.com/cilium/ebpf/pull/930

Fixes: 0cdbb4b09a06 ("devmap: Allow map lookups from eBPF")
Signed-off-by: Yureka Lilian <yuka@yuka.dev>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20250814180113.1245565-3-yuka@yuka.dev
2025-08-21 13:39:29 -07:00
Ilya Leoshkevich
8ce18b6b73 libbpf: Add the ability to suppress perf event enablement
Automatically enabling a perf event after attaching a BPF prog to it is
not always desirable.

Add a new "dont_enable" field to struct bpf_perf_event_opts. While
introducing "enable" instead would be nicer in that it would avoid
a double negation in the implementation, it would make
DECLARE_LIBBPF_OPTS() less efficient.

Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Suggested-by: Jiri Olsa <jolsa@kernel.org>
Tested-by: Thomas Richter <tmricht@linux.ibm.com>
Co-developed-by: Thomas Richter <tmricht@linux.ibm.com>
Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Link: https://lore.kernel.org/r/20250806162417.19666-2-iii@linux.ibm.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2025-08-12 12:51:17 -07:00
Achill Gilgenast
df60ff2a29 libbpf: Avoid possible use of uninitialized mod_len
Though mod_len is only read when mod_name != NULL and both are initialized
together, gcc15 produces a warning with -Werror=maybe-uninitialized:

libbpf.c: In function 'find_kernel_btf_id.constprop':
libbpf.c:10100:33: error: 'mod_len' may be used uninitialized [-Werror=maybe-uninitialized]
10100 |                 if (mod_name && strncmp(mod->name, mod_name, mod_len) != 0)
      |                                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
libbpf.c:10070:21: note: 'mod_len' was declared here
10070 |         int ret, i, mod_len;
      |                     ^~~~~~~

Silence the false positive.

Signed-off-by: Achill Gilgenast <fossdd@pwned.life>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20250729094611.2065713-1-fossdd@pwned.life
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2025-08-12 12:51:17 -07:00
Andrii Nakryiko
9823ef295d libbpf: dump Makefile version to 1.7.0
With new development cycle comes updated Makefile.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
2025-07-18 17:20:48 -07:00
Eduard Zingerman
8e59f80a93 libbpf: Verify that arena map exists when adding arena relocations
Fuzzer reported a memory access error in bpf_program__record_reloc()
that happens when:
- ".addr_space.1" section exists
- there is a relocation referencing this section
- there are no arena maps defined in BTF.

Sanity checks for maps existence are already present in
bpf_program__record_reloc(), hence this commit adds another one.

[1] https://github.com/libbpf/libbpf/actions/runs/16375110681/job/46272998064

Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20250718222059.281526-1-eddyz87@gmail.com
2025-07-18 17:20:48 -07:00
Andrii Nakryiko
fb66fb4948 libbpf: Fix handling of BPF arena relocations
Initial __arena global variable support implementation in libbpf
contains a bug: it remembers struct bpf_map pointer for arena, which is
used later on to process relocations. Recording this pointer is
problematic because map pointers are not stable during ELF relocation
collection phase, as an array of struct bpf_map's can be reallocated,
invalidating all the pointers. Libbpf is dealing with similar issues by
using a stable internal map index, though for BPF arena map specifically
this approach wasn't used due to an oversight.

The resulting behavior is non-deterministic issue which depends on exact
layout of ELF object file, number of actual maps, etc. We didn't hit
this until very recently, when this bug started triggering crash in BPF
CI when validating one of sched-ext BPF programs.

The fix is rather straightforward: we just follow an established pattern
of remembering map index (just like obj->kconfig_map_idx, for example)
instead of `struct bpf_map *`, and resolving index to a pointer at the
point where map information is necessary.

While at it also add debug-level message for arena-related relocation
resolution information, which we already have for all other kinds of
maps.

Fixes: 2e7ba4f8fd1f ("libbpf: Recognize __arena global variables.")
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Tested-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20250718001009.610955-1-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2025-07-18 17:20:48 -07:00
Matteo Croce
a9dbcc32fd libbpf: Fix warning in calloc() usage
When compiling libbpf with some compilers, this warning is triggered:

libbpf.c: In function ‘bpf_object__gen_loader’:
libbpf.c:9209:28: error: ‘calloc’ sizes specified with ‘sizeof’ in the earlier argument and not in the later argument [-Werror=calloc-transposed-args]
 9209 |         gen = calloc(sizeof(*gen), 1);
      |                            ^
libbpf.c:9209:28: note: earlier argument should specify number of elements, later size of each element

Fix this by inverting the calloc() arguments.

Signed-off-by: Matteo Croce <teknoraver@meta.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/bpf/20250717200337.49168-1-technoboy85@gmail.com
2025-07-18 17:20:48 -07:00
Andrii Nakryiko
2b39ea081f libbpf: start v1.7 dev cycle
With libbpf 1.6.0 released, adjust libbpf.map and libbpf_version.h to
start v1.7 development cycles.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20250716175936.2343013-1-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2025-07-18 17:20:48 -07:00
Eduard Zingerman
5f4a34c606 libbpf: __arg_untrusted in bpf_helpers.h
Make btf_decl_tag("arg:untrusted") available for libbpf users via
macro. Makes the following usage possible:

  void foo(struct bar *p __arg_untrusted) { ... }
  void bar(struct foo *p __arg_trusted) {
    ...
    foo(p->buz->bar); // buz derefrence looses __trusted
    ...
  }

Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20250704230354.1323244-6-eddyz87@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2025-07-16 08:57:15 -07:00
Kumar Kartikeya Dwivedi
c2850a3840 libbpf: Introduce bpf_prog_stream_read() API
Introduce a libbpf API so that users can read data from a given BPF
stream for a BPF prog fd. For now, only the low-level syscall wrapper
is provided, we can add a bpf_program__* accessor as a follow up if
needed.

Acked-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20250703204818.925464-11-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2025-07-16 08:57:15 -07:00
Kumar Kartikeya Dwivedi
9bb5c46da4 libbpf: Add bpf_stream_printk() macro
Add a convenience macro to print data to the BPF streams. BPF_STDOUT and
BPF_STDERR stream IDs in the vmlinux.h can be passed to the macro to
print to the respective streams.

Acked-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20250703204818.925464-10-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2025-07-16 08:57:15 -07:00
Adin Scannell
b58f5a3e77 libbpf: Fix possible use-after-free for externs
The `name` field in `obj->externs` points into the BTF data at initial
open time. However, some functions may invalidate this after opening and
before loading (e.g. `bpf_map__set_value_size`), which results in
pointers into freed memory and undefined behavior.

The simplest solution is to simply `strdup` these strings, similar to
the `essent_name`, and free them at the same time.

In order to test this path, the `global_map_resize` BPF selftest is
modified slightly to ensure the presence of an extern, which causes this
test to fail prior to the fix. Given there isn't an obvious API or error
to test against, I opted to add this to the existing test as an aspect
of the resizing feature rather than duplicate the test.

Fixes: 9d0a23313b1a ("libbpf: Add capability for resizing datasec maps")
Signed-off-by: Adin Scannell <amscanne@meta.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20250625050215.2777374-1-amscanne@meta.com
2025-07-01 15:38:22 -07:00
Yuan Chen
de1d0a25a8 libbpf: Fix null pointer dereference in btf_dump__free on allocation failure
When btf_dump__new() fails to allocate memory for the internal hashmap
(btf_dump->type_names), it returns an error code. However, the cleanup
function btf_dump__free() does not check if btf_dump->type_names is NULL
before attempting to free it. This leads to a null pointer dereference
when btf_dump__free() is called on a btf_dump object.

Fixes: 351131b51c7a ("libbpf: add btf_dump API for BTF-to-C conversion")
Signed-off-by: Yuan Chen <chenyuan@kylinos.cn>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20250618011933.11423-1-chenyuan_fl@163.com
2025-07-01 15:38:22 -07:00
Amery Hung
f6284bb875 sync: auto-generate latest BPF helpers
Latest changes to BPF helper definitions.

Signed-off-by: Amery Hung <ameryhung@gmail.com>
2025-06-16 08:52:44 -07:00
Andrii Nakryiko
7356be641d libbpf: Handle unsupported mmap-based /sys/kernel/btf/vmlinux correctly
libbpf_err_ptr() helpers are meant to return NULL and set errno, if
there is an error. But btf_parse_raw_mmap() is meant to be used
internally and is expected to return ERR_PTR() values. Because of this
mismatch, when libbpf tries to mmap /sys/kernel/btf/vmlinux, we don't
detect the error correctly with IS_ERR() check, and never fallback to
old non-mmap-based way of loading vmlinux BTF.

Fix this by using proper ERR_PTR() returns internally.

Reported-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Reviewed-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Fixes: 3c0421c93ce4 ("libbpf: Use mmap to parse vmlinux BTF from sysfs")
Cc: Lorenz Bauer <lmb@isovalent.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20250606202134.2738910-1-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2025-06-16 08:52:44 -07:00
Yonghong Song
553676e8f5 libbpf: Support link-based cgroup attach with options
Currently libbpf supports bpf_program__attach_cgroup() with signature:
  LIBBPF_API struct bpf_link *
  bpf_program__attach_cgroup(const struct bpf_program *prog, int cgroup_fd);

To support mprog style attachment, additionsl fields like flags,
relative_{fd,id} and expected_revision are needed.

Add a new API:
  LIBBPF_API struct bpf_link *
  bpf_program__attach_cgroup_opts(const struct bpf_program *prog, int cgroup_fd,
                                  const struct bpf_cgroup_opts *opts);
where bpf_cgroup_opts contains all above needed fields.

Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20250606163146.2429212-1-yonghong.song@linux.dev
2025-06-16 08:52:44 -07:00
Blake Jones
439433a909 libbpf: Add support for printing BTF character arrays as strings
The BTF dumper code currently displays arrays of characters as just that -
arrays, with each character formatted individually. Sometimes this is what
makes sense, but it's nice to be able to treat that array as a string.

This change adds a special case to the btf_dump functionality to allow
0-terminated arrays of single-byte integer values to be printed as
character strings. Characters for which isprint() returns false are
printed as hex-escaped values. This is enabled when the new ".emit_strings"
is set to 1 in the btf_dump_type_data_opts structure.

As an example, here's what it looks like to dump the string "hello" using
a few different field values for btf_dump_type_data_opts (.compact = 1):

- .emit_strings = 0, .skip_names = 0:  (char[6])['h','e','l','l','o',]
- .emit_strings = 0, .skip_names = 1:  ['h','e','l','l','o',]
- .emit_strings = 1, .skip_names = 0:  (char[6])"hello"
- .emit_strings = 1, .skip_names = 1:  "hello"

Here's the string "h\xff", dumped with .compact = 1 and .skip_names = 1:

- .emit_strings = 0:  ['h',-1,]
- .emit_strings = 1:  "h\xff"

Signed-off-by: Blake Jones <blakejones@google.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20250603203701.520541-1-blakejones@google.com
2025-06-16 08:52:44 -07:00
Jiawei Zhao
224ea3ec50 libbpf: Correct some typos and syntax issues in usdt doc
Fix some incorrect words, such as "and" -> "an", "it's" -> "its".  Fix
some grammar issues, such as removing redundant "will", "would
complicated" -> "would complicate".

Signed-off-by: Jiawei Zhao <Phoenix500526@163.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20250531095111.57824-1-Phoenix500526@163.com
2025-06-16 08:52:44 -07:00
Lorenz Bauer
01dd871a20 libbpf: Use mmap to parse vmlinux BTF from sysfs
Teach libbpf to use mmap when parsing vmlinux BTF from /sys. We don't
apply this to fall-back paths on the regular file system because there
is no way to ensure that modifications underlying the MAP_PRIVATE
mapping are not visible to the process.

Signed-off-by: Lorenz Bauer <lmb@isovalent.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Tested-by: Alan Maguire <alan.maguire@oracle.com>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20250520-vmlinux-mmap-v5-3-e8c941acc414@isovalent.com
2025-06-16 08:52:44 -07:00
Alan Maguire
8df8d67f63 libbpf/btf: Fix string handling to support multi-split BTF
libbpf handling of split BTF has been written largely with the
assumption that multiple splits are possible, i.e. split BTF on top of
split BTF on top of base BTF.  One area where this does not quite work
is string handling in split BTF; the start string offset should be the
base BTF string section length + the base BTF string offset.  This
worked in the past because for a single split BTF with base the start
string offset was always 0.

Signed-off-by: Alan Maguire <alan.maguire@oracle.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20250519165935.261614-2-alan.maguire@oracle.com
2025-06-16 08:52:44 -07:00
Amery Hung
f580871b42 libbpf: Support creating and destroying qdisc
Extend struct bpf_tc_hook with handle, qdisc name and a new attach type,
BPF_TC_QDISC, to allow users to add or remove any qdisc specified in
addition to clsact.

Signed-off-by: Amery Hung <amery.hung@bytedance.com>
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://patch.msgid.link/20250409214606.2000194-8-ameryhung@gmail.com
2025-06-16 08:51:34 -07:00
Mykyta Yatsenko
453601a65a libbpf: Check bpf_map_skeleton link for NULL
Avoid dereferencing bpf_map_skeleton's link field if it's NULL.
If BPF map skeleton is created with the size, that indicates containing
link field, but the field was not actually initialized with valid
bpf_link pointer, libbpf crashes. This may happen when using libbpf-rs
skeleton.
Skeleton loading may still progress, but user needs to attach struct_ops
map separately.

Signed-off-by: Mykyta Yatsenko <yatsenko@meta.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20250514113220.219095-1-mykyta.yatsenko5@gmail.com
2025-05-19 10:07:42 -07:00
Anton Protopopov
8e34ca4e8f libbpf: Use proper errno value in nlattr
Return value of the validate_nla() function can be propagated all the
way up to users of libbpf API. In case of error this libbpf version
of validate_nla returns -1 which will be seen as -EPERM from user's
point of view. Instead, return a more reasonable -EINVAL.

Fixes: bbf48c18ee0c ("libbpf: add error reporting in XDP")
Suggested-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Anton Protopopov <a.s.protopopov@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20250510182011.2246631-1-a.s.protopopov@gmail.com
2025-05-19 10:07:42 -07:00
Andrii Nakryiko
5ee9fbf7d7 libbpf: Improve BTF dedup handling of "identical" BTF types
BTF dedup has a strong assumption that compiler with deduplicate identical
types within any given compilation unit (i.e., .c file). This property
is used when establishing equilvalence of two subgraphs of types.

Unfortunately, this property doesn't always holds in practice. We've
seen cases of having truly identical structs, unions, array definitions,
and, most recently, even pointers to the same type being duplicated
within CU.

Previously, we mitigated this on a case-by-case basis, adding a few
simple heuristics for validating that two BTF types (having two
different type IDs) are structurally the same. But this approach scales
poorly, and we can have more weird cases come up in the future.

So let's take a half-step back, and implement a bit more generic
structural equivalence check, recursively. We still limit it to
reasonable depth to avoid long reference loops. Depth-wise limiting of
potentially cyclical graph isn't great, but as I mentioned below doesn't
seem to be detrimental performance-wise. We can always improve this in
the future with per-type visited markers, if necessary.

Performance-wise this doesn't seem too affect vmlinux BTF dedup, which
makes sense because this logic kicks in not so frequently and only if we
already established a canonical candidate type match, but suddenly find
a different (but probably identical) type.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Reviewed-by: Alan Maguire <alan.maguire@oracle.com>
Link: https://lore.kernel.org/r/20250501235231.1339822-1-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2025-05-19 10:07:42 -07:00
Anton Protopopov
d88ca95133 bpf: Fix uninitialized values in BPF_{CORE,PROBE}_READ
With the latest LLVM bpf selftests build will fail with
the following error message:

    progs/profiler.inc.h:710:31: error: default initialization of an object of type 'typeof ((parent_task)->real_cred->uid.val)' (aka 'const unsigned int') leaves the object uninitialized and is incompatible with C++ [-Werror,-Wdefault-const-init-unsafe]
      710 |         proc_exec_data->parent_uid = BPF_CORE_READ(parent_task, real_cred, uid.val);
          |                                      ^
    tools/testing/selftests/bpf/tools/include/bpf/bpf_core_read.h:520:35: note: expanded from macro 'BPF_CORE_READ'
      520 |         ___type((src), a, ##__VA_ARGS__) __r;                               \
          |                                          ^

This happens because BPF_CORE_READ (and other macro) declare the
variable __r using the ___type macro which can inherit const modifier
from intermediate types.

Fix this by using __typeof_unqual__, when supported. (And when it
is not supported, the problem shouldn't appear, as older compilers
haven't complained.)

Fixes: 792001f4f7aa ("libbpf: Add user-space variants of BPF_CORE_READ() family of macros")
Fixes: a4b09a9ef945 ("libbpf: Add non-CO-RE variants of BPF_CORE_READ() macro family")
Signed-off-by: Anton Protopopov <a.s.protopopov@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20250502193031.3522715-1-a.s.protopopov@gmail.com
2025-05-19 10:07:42 -07:00
Anton Protopopov
28deee2663 libbpf: Use proper errno value in linker
Return values of the linker_append_sec_data() and the
linker_append_elf_relos() functions are propagated all the
way up to users of libbpf API. In some error cases these
functions return -1 which will be seen as -EPERM from user's
point of view. Instead, return a more reasonable -EINVAL.

Fixes: faf6ed321cf6 ("libbpf: Add BPF static linker APIs")
Signed-off-by: Anton Protopopov <a.s.protopopov@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20250430120820.2262053-1-a.s.protopopov@gmail.com
2025-05-19 10:07:42 -07:00
Andrii Nakryiko
27dc274f68 sync: auto-generate latest BPF helpers
Latest changes to BPF helper definitions.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
2025-04-29 11:33:37 -07:00
Alan Maguire
c8a28812fb libbpf: Add identical pointer detection to btf_dedup_is_equiv()
Recently as a side-effect of

commit ac053946f5c4 ("compiler.h: introduce TYPEOF_UNQUAL() macro")

issues were observed in deduplication between modules and kernel BTF
such that a large number of kernel types were not deduplicated so
were found in module BTF (task_struct, bpf_prog etc).  The root cause
appeared to be a failure to dedup struct types, specifically those
with members that were pointers with __percpu annotations.

The issue in dedup is at the point that we are deduplicating structures,
we have not yet deduplicated reference types like pointers.  If multiple
copies of a pointer point at the same (deduplicated) integer as in this
case, we do not see them as identical.  Special handling already exists
to deal with structures and arrays, so add pointer handling here too.

Reported-by: Alexei Starovoitov <ast@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/20250429161042.2069678-1-alan.maguire@oracle.com
2025-04-29 11:33:37 -07:00
Jonathan Wiepert
88ae865423 Use thread-safe function pointer in libbpf_print
This patch fixes a thread safety bug where libbpf_print uses the
global variable storing the print function pointer rather than the local
variable that had the print function set via __atomic_load_n.

Fixes: f1cb927cdb62 ("libbpf: Ensure print callback usage is thread-safe")
Signed-off-by: Jonathan Wiepert <jonathan.wiepert@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Mykyta Yatsenko <mykyta.yatsenko5@gmail.com>
Link: https://lore.kernel.org/bpf/20250424221457.793068-1-jonathan.wiepert@gmail.com
2025-04-29 11:33:37 -07:00
Tao Chen
a2dc135196 libbpf: Remove sample_period init in perf_buffer
It seems that sample_period is not used in perf buffer. Actually, only
wakeup_events are meaningful to enable events aggregation for wakeup notification.
Remove sample_period setting code to avoid confusion.

Fixes: fb84b8224655 ("libbpf: add perf buffer API")
Signed-off-by: Tao Chen <chen.dylane@linux.dev>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Link: https://lore.kernel.org/bpf/20250423163901.2983689-1-chen.dylane@linux.dev
2025-04-29 11:33:37 -07:00
Feng Yang
715808d3e2 libbpf: Fix event name too long error
When the binary path is excessively long, the generated probe_name in libbpf
exceeds the kernel's MAX_EVENT_NAME_LEN limit (64 bytes).
This causes legacy uprobe event attachment to fail with error code -22.

The fix reorders the fields to place the unique ID before the name.
This ensures that even if truncation occurs via snprintf, the unique ID
remains intact, preserving event name uniqueness. Additionally, explicit
checks with MAX_EVENT_NAME_LEN are added to enforce length constraints.

Before Fix:
	./test_progs -t attach_probe/kprobe-long_name
	......
	libbpf: failed to add legacy kprobe event for 'bpf_testmod_looooooooooooooooooooooooooooooong_name+0x0': -EINVAL
	libbpf: prog 'handle_kprobe': failed to create kprobe 'bpf_testmod_looooooooooooooooooooooooooooooong_name+0x0' perf event: -EINVAL
	test_attach_kprobe_long_event_name:FAIL:attach_kprobe_long_event_name unexpected error: -22
	test_attach_probe:PASS:uprobe_ref_ctr_cleanup 0 nsec
	#13/11   attach_probe/kprobe-long_name:FAIL
	#13      attach_probe:FAIL

	./test_progs -t attach_probe/uprobe-long_name
	......
	libbpf: failed to add legacy uprobe event for /root/linux-bpf/bpf-next/tools/testing/selftests/bpf/test_progs:0x13efd9: -EINVAL
	libbpf: prog 'handle_uprobe': failed to create uprobe '/root/linux-bpf/bpf-next/tools/testing/selftests/bpf/test_progs:0x13efd9' perf event: -EINVAL
	test_attach_uprobe_long_event_name:FAIL:attach_uprobe_long_event_name unexpected error: -22
	#13/10   attach_probe/uprobe-long_name:FAIL
	#13      attach_probe:FAIL
After Fix:
	./test_progs -t attach_probe/uprobe-long_name
	#13/10   attach_probe/uprobe-long_name:OK
	#13      attach_probe:OK
	Summary: 1/1 PASSED, 0 SKIPPED, 0 FAILED

	./test_progs -t attach_probe/kprobe-long_name
	#13/11   attach_probe/kprobe-long_name:OK
	#13      attach_probe:OK
	Summary: 1/1 PASSED, 0 SKIPPED, 0 FAILED

Fixes: 46ed5fc33db9 ("libbpf: Refactor and simplify legacy kprobe code")
Fixes: cc10623c6810 ("libbpf: Add legacy uprobe attaching support")
Signed-off-by: Hengqi Chen <hengqi.chen@gmail.com>
Signed-off-by: Feng Yang <yangfeng@kylinos.cn>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20250417014848.59321-2-yangfeng59949@163.com
2025-04-29 11:33:37 -07:00
Ihor Solodrai
02bc656f90 libbpf: Verify section type in btf_find_elf_sections
A valid ELF file may contain a SHT_NOBITS .BTF section. This case is
not handled correctly in btf_parse_elf, which leads to a segfault.

Before attempting to load BTF section data, check that the section
type is SHT_PROGBITS, which is the expected type for BTF data.  Fail
with an error if the type is different.

Bug report: https://github.com/libbpf/libbpf/issues/894
v1: https://lore.kernel.org/bpf/20250408184104.3962949-1-ihor.solodrai@linux.dev/

Signed-off-by: Ihor Solodrai <ihor.solodrai@linux.dev>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20250410182823.1591681-1-ihor.solodrai@linux.dev
2025-04-29 11:33:37 -07:00
Viktor Malik
806b4e0a9f libbpf: Fix buffer overflow in bpf_object__init_prog
As shown in [1], it is possible to corrupt a BPF ELF file such that
arbitrary BPF instructions are loaded by libbpf. This can be done by
setting a symbol (BPF program) section offset to a large (unsigned)
number such that <section start + symbol offset> overflows and points
before the section data in the memory.

Consider the situation below where:
- prog_start = sec_start + symbol_offset    <-- size_t overflow here
- prog_end   = prog_start + prog_size

    prog_start        sec_start        prog_end        sec_end
        |                |                 |              |
        v                v                 v              v
    .....................|################################|............

The report in [1] also provides a corrupted BPF ELF which can be used as
a reproducer:

    $ readelf -S crash
    Section Headers:
      [Nr] Name              Type             Address           Offset
           Size              EntSize          Flags  Link  Info  Align
    ...
      [ 2] uretprobe.mu[...] PROGBITS         0000000000000000  00000040
           0000000000000068  0000000000000000  AX       0     0     8

    $ readelf -s crash
    Symbol table '.symtab' contains 8 entries:
       Num:    Value          Size Type    Bind   Vis      Ndx Name
    ...
         6: ffffffffffffffb8   104 FUNC    GLOBAL DEFAULT    2 handle_tp

Here, the handle_tp prog has section offset ffffffffffffffb8, i.e. will
point before the actual memory where section 2 is allocated.

This is also reported by AddressSanitizer:

    =================================================================
    ==1232==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x7c7302fe0000 at pc 0x7fc3046e4b77 bp 0x7ffe64677cd0 sp 0x7ffe64677490
    READ of size 104 at 0x7c7302fe0000 thread T0
        #0 0x7fc3046e4b76 in memcpy (/lib64/libasan.so.8+0xe4b76)
        #1 0x00000040df3e in bpf_object__init_prog /src/libbpf/src/libbpf.c:856
        #2 0x00000040df3e in bpf_object__add_programs /src/libbpf/src/libbpf.c:928
        #3 0x00000040df3e in bpf_object__elf_collect /src/libbpf/src/libbpf.c:3930
        #4 0x00000040df3e in bpf_object_open /src/libbpf/src/libbpf.c:8067
        #5 0x00000040f176 in bpf_object__open_file /src/libbpf/src/libbpf.c:8090
        #6 0x000000400c16 in main /poc/poc.c:8
        #7 0x7fc3043d25b4 in __libc_start_call_main (/lib64/libc.so.6+0x35b4)
        #8 0x7fc3043d2667 in __libc_start_main@@GLIBC_2.34 (/lib64/libc.so.6+0x3667)
        #9 0x000000400b34 in _start (/poc/poc+0x400b34)

    0x7c7302fe0000 is located 64 bytes before 104-byte region [0x7c7302fe0040,0x7c7302fe00a8)
    allocated by thread T0 here:
        #0 0x7fc3046e716b in malloc (/lib64/libasan.so.8+0xe716b)
        #1 0x7fc3045ee600 in __libelf_set_rawdata_wrlock (/lib64/libelf.so.1+0xb600)
        #2 0x7fc3045ef018 in __elf_getdata_rdlock (/lib64/libelf.so.1+0xc018)
        #3 0x00000040642f in elf_sec_data /src/libbpf/src/libbpf.c:3740

The problem here is that currently, libbpf only checks that the program
end is within the section bounds. There used to be a check
`while (sec_off < sec_sz)` in bpf_object__add_programs, however, it was
removed by commit 6245947c1b3c ("libbpf: Allow gaps in BPF program
sections to support overriden weak functions").

Add a check for detecting the overflow of `sec_off + prog_sz` to
bpf_object__init_prog to fix this issue.

[1] https://github.com/lmarch2/poc/blob/main/libbpf/libbpf.md

Fixes: 6245947c1b3c ("libbpf: Allow gaps in BPF program sections to support overriden weak functions")
Reported-by: lmarch2 <2524158037@qq.com>
Signed-off-by: Viktor Malik <vmalik@redhat.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Reviewed-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
Link: https://github.com/lmarch2/poc/blob/main/libbpf/libbpf.md
Link: https://lore.kernel.org/bpf/20250415155014.397603-1-vmalik@redhat.com
2025-04-29 11:33:37 -07:00
Mykyta Yatsenko
abdb15bedd libbpf: Add getters for BTF.ext func and line info
Introducing new libbpf API getters for BTF.ext func and line info,
namely:
  bpf_program__func_info
  bpf_program__func_info_cnt
  bpf_program__line_info
  bpf_program__line_info_cnt

This change enables scenarios, when user needs to load bpf_program
directly using `bpf_prog_load`, instead of higher-level
`bpf_object__load`. Line and func info are required for checking BTF
info in verifier; verification may fail without these fields if, for
example, program calls `bpf_obj_new`.

Signed-off-by: Mykyta Yatsenko <yatsenko@meta.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20250408234417.452565-2-mykyta.yatsenko5@gmail.com
2025-04-29 11:33:37 -07:00
Anton Protopopov
7a1388d55f libbpf: Add likely/unlikely macros and use them in selftests
A few selftests and, more importantly, consequent changes to the
bpf_helpers.h file, use likely/unlikely macros, so define them here
and remove duplicate definitions from existing selftests.

Signed-off-by: Anton Protopopov <a.s.protopopov@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20250331203618.1973691-3-a.s.protopopov@gmail.com
2025-04-29 11:33:37 -07:00
Carlos Llamas
732d6c011f libbpf: Fix implicit memfd_create() for bionic
Since memfd_create() is not consistently available across different
bionic libc implementations, using memfd_create() directly can break
some Android builds:

  tools/lib/bpf/linker.c:576:7: error: implicit declaration of function 'memfd_create' [-Werror,-Wimplicit-function-declaration]
    576 |         fd = memfd_create(filename, 0);
        |              ^

To fix this, relocate and inline the sys_memfd_create() helper so that
it can be used in "linker.c". Similar issues were previously fixed by
commit 9fa5e1a180aa ("libbpf: Call memfd_create() syscall directly").

Fixes: 6d5e5e5d7ce1 ("libbpf: Extend linker API to support in-memory ELF files")
Signed-off-by: Carlos Llamas <cmllamas@google.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20250330211325.530677-1-cmllamas@google.com
2025-04-29 11:33:37 -07:00
Ian Rogers
2a228c7885 libbpf: Add namespace for errstr making it libbpf_errstr
When statically linking symbols can be replaced with those from other
statically linked libraries depending on the link order and the hoped
for "multiple definition" error may not appear. To avoid conflicts it
is good practice to namespace symbols, this change renames errstr to
libbpf_errstr. To avoid churn a #define is used to turn use of
errstr(err) to libbpf_errstr(err).

Fixes: 1633a83bf993 ("libbpf: Introduce errstr() for stringifying errno")
Signed-off-by: Ian Rogers <irogers@google.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20250320222439.1350187-1-irogers@google.com
2025-04-02 14:24:25 -07:00
Mykyta Yatsenko
90844e28dc libbpf: Pass BPF token from find_prog_btf_id to BPF_BTF_GET_FD_BY_ID
Pass BPF token from bpf_program__set_attach_target to
BPF_BTF_GET_FD_BY_ID bpf command.
When freplace program attaches to target program, it needs to look up
for BTF of the target, this may require BPF token, if, for example,
running from user namespace.

Signed-off-by: Mykyta Yatsenko <yatsenko@meta.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/bpf/20250317174039.161275-4-mykyta.yatsenko5@gmail.com
2025-04-02 14:24:25 -07:00
Mykyta Yatsenko
855a5d7904 libbpf: Split bpf object load into prepare/load
Introduce bpf_object__prepare API: additional intermediate preparation
step that performs ELF processing, relocations, prepares final state of
BPF program instructions (accessible with bpf_program__insns()), creates
and (potentially) pins maps, and stops short of loading BPF programs.

We anticipate few use cases for this API, such as:
* Use prepare to initialize bpf_token, without loading freplace
programs, unlocking possibility to lookup BTF of other programs.
* Execute prepare to obtain finalized BPF program instructions without
loading programs, enabling tools like veristat to process one program at
a time, without incurring cost of ELF parsing and processing.

Signed-off-by: Mykyta Yatsenko <yatsenko@meta.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20250303135752.158343-4-mykyta.yatsenko5@gmail.com
Signed-off-by: Ihor Solodrai <ihor.solodrai@linux.dev>
2025-03-10 15:35:17 -07:00
Mykyta Yatsenko
16c58c33c8 libbpf: Introduce more granular state for bpf_object
We are going to split bpf_object loading into 2 stages: preparation and
loading. This will increase flexibility when working with bpf_object
and unlock some optimizations and use cases.
This patch substitutes a boolean flag (loaded) by more finely-grained
state for bpf_object.

Signed-off-by: Mykyta Yatsenko <yatsenko@meta.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20250303135752.158343-3-mykyta.yatsenko5@gmail.com
Signed-off-by: Ihor Solodrai <ihor.solodrai@linux.dev>
2025-03-10 15:35:17 -07:00
Mykyta Yatsenko
e14bb3629f libbpf: Use map_is_created helper in map setters
Refactoring: use map_is_created helper in map setters that need to check
the state of the map. This helps to reduce the number of the places that
depend explicitly on the loaded flag, simplifying refactoring in the
next patch of this set.

Signed-off-by: Mykyta Yatsenko <yatsenko@meta.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20250303135752.158343-2-mykyta.yatsenko5@gmail.com
Signed-off-by: Ihor Solodrai <ihor.solodrai@linux.dev>
2025-03-10 15:35:17 -07:00
Ihor Solodrai
be18fdb16a libbpf: Implement bpf_usdt_arg_size BPF function
Information about USDT argument size is implicitly stored in
__bpf_usdt_arg_spec, but currently it's not accessbile to BPF programs
that use USDT.

Implement bpf_sdt_arg_size() that returns the size of an USDT argument
in bytes.

v1->v2:
  * do not add __bpf_usdt_arg_spec() helper

v1: https://lore.kernel.org/bpf/20250220215904.3362709-1-ihor.solodrai@linux.dev/

Suggested-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Ihor Solodrai <ihor.solodrai@linux.dev>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Reviewed-by: Jiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/bpf/20250224235756.2612606-1-ihor.solodrai@linux.dev
2025-03-10 15:35:17 -07:00
Nandakumar Edamana
82f60c9b5e libbpf: Fix out-of-bound read
In `set_kcfg_value_str`, an untrusted string is accessed with the assumption
that it will be at least two characters long due to the presence of checks for
opening and closing quotes. But the check for the closing quote
(value[len - 1] != '"') misses the fact that it could be checking the opening
quote itself in case of an invalid input that consists of just the opening
quote.

This commit adds an explicit check to make sure the string is at least two
characters long.

Signed-off-by: Nandakumar Edamana <nandakumar@nandakumar.co.in>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20250221210110.3182084-1-nandakumar@nandakumar.co.in
Signed-off-by: Ihor Solodrai <ihor.solodrai@linux.dev>
2025-03-10 15:35:17 -07:00
Andrii Nakryiko
4c893341f5 Makefile: detect pkg-config availability
Detect whether build system has pkg-config tool, and if not, fallback to
manually specifying -lelf -lz as dependency.

Closes: https://github.com/libbpf/libbpf/issues/885
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
2025-03-03 18:59:47 -08:00
Andrii Nakryiko
041d5948f3 libbpf: Fix hypothetical STT_SECTION extern NULL deref case
Fix theoretical NULL dereference in linker when resolving *extern*
STT_SECTION symbol against not-yet-existing ELF section. Not sure if
it's possible in practice for valid ELF object files (this would require
embedded assembly manipulations, at which point BTF will be missing),
but fix the s/dst_sym/dst_sec/ typo guarding this condition anyways.

Fixes: faf6ed321cf6 ("libbpf: Add BPF static linker APIs")
Fixes: a46349227cd8 ("libbpf: Add linker extern resolution support for functions and global variables")
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20250220002821.834400-1-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Ihor Solodrai <ihor.solodrai@linux.dev>
2025-02-24 15:10:59 -08:00
Tao Chen
39a589c74e libbpf: Wrap libbpf API direct err with libbpf_err
Just wrap the direct err with libbpf_err, keep consistency
with other APIs.

Signed-off-by: Tao Chen <chen.dylane@linux.dev>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/bpf/20250219153711.29651-1-chen.dylane@linux.dev
Signed-off-by: Ihor Solodrai <ihor.solodrai@linux.dev>
2025-02-24 15:10:59 -08:00
Andrii Nakryiko
d7a4ab1548 libbpf: fix LDX/STX/ST CO-RE relocation size adjustment logic
Libbpf has a somewhat obscure feature of automatically adjusting the
"size" of LDX/STX/ST instruction (memory store and load instructions),
based on originally recorded access size (u8, u16, u32, or u64) and the
actual size of the field on target kernel. This is meant to facilitate
using BPF CO-RE on 32-bit architectures (pointers are always 64-bit in
BPF, but host kernel's BTF will have it as 32-bit type), as well as
generally supporting safe type changes (unsigned integer type changes
can be transparently "relocated").

One issue that surfaced only now, 5 years after this logic was
implemented, is how this all works when dealing with fields that are
arrays. This isn't all that easy and straightforward to hit (see
selftests that reproduce this condition), but one of sched_ext BPF
programs did hit it with innocent looking loop.

Long story short, libbpf used to calculate entire array size, instead of
making sure to only calculate array's element size. But it's the element
that is loaded by LDX/STX/ST instructions (1, 2, 4, or 8 bytes), so
that's what libbpf should check. This patch adjusts the logic for
arrays and fixed the issue.

Reported-by: Emil Tsalapatis <emil@etsalapatis.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20250207014809.1573841-1-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Ihor Solodrai <ihor.solodrai@linux.dev>
2025-02-24 15:10:59 -08:00
Ihor Solodrai
cc278ff7c0 libbpf: Check the kflag of type tags in btf_dump
If the kflag is set for a BTF type tag, then the tag represents an
arbitrary __attribute__. Change btf_dump accordingly.

Signed-off-by: Ihor Solodrai <ihor.solodrai@linux.dev>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Reviewed-by: Alan Maguire <alan.maguire@oracle.com>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20250130201239.1429648-4-ihor.solodrai@linux.dev
2025-02-24 15:10:59 -08:00