bpf: Add KF_PERFMON kfunc flag

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Tracing related BPF helpers e.g. under bpf_base_func_proto() are gated
behind CAP_PERFMON. However, the same is currently not true for kfuncs
and they are accessible via plain CAP_BPF. Add a new KF_PERFMON flag
which can be used such that check_kfunc_call() ensures env->allow_ptr_leaks
is permitted. This follows similar pattern to existing KF_DESTRUCTIVE flag.

The rejection returns -EPERM to match the other CAP_PERFMON gates in the
verifier, that is, check_ptr_to_btf_access() and check_ptr_to_map_access(),
which report the very same policy to user space.

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/r/20260910213510.49358-1-daniel@iogearbox.net
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

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Daniel Borkmann 2026-09-10 23:35:07 +02:00 • committed by Alexei Starovoitov

parent e4a62833ad

commit 88ce88e933

3 changed files with 25 additions and 0 deletions

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10

Documentation/bpf/kfuncs.rst

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1

include/linux/btf.h

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14

kernel/bpf/verifier.c

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