bpf: return PTR_TO_BTF_ID | PTR_TRUSTED from BPF kfuncs by default

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Teach the BPF verifier to treat pointers to struct types returned from
BPF kfuncs as implicitly trusted (PTR_TO_BTF_ID | PTR_TRUSTED) by
default. Returning untrusted pointers to struct types from BPF kfuncs
should be considered an exception only, and certainly not the norm.

Update existing selftests to reflect the change in register type
printing (e.g. `ptr_` becoming `trusted_ptr_` in verifier error
messages).

Link: https://lore.kernel.org/bpf/aV4nbCaMfIoM0awM@google.com/
Signed-off-by: Matt Bobrowski <mattbobrowski@google.com>
Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20260113083949.2502978-1-mattbobrowski@google.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

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This commit is contained in:

Matt Bobrowski 2026-01-13 08:39:47 +00:00 • committed by Alexei Starovoitov

parent b9da17391e

commit f8ade2342e

5 changed files with 34 additions and 22 deletions

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46

kernel/bpf/verifier.c

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4

tools/testing/selftests/bpf/progs/map_kptr_fail.c

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2

tools/testing/selftests/bpf/progs/struct_ops_kptr_return_fail__wrong_type.c

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2

tools/testing/selftests/bpf/progs/verifier_global_ptr_args.c

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2

tools/testing/selftests/bpf/verifier/calls.c

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