bpf: Support bpf_kptr_xchg into local kptr

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Currently, users can only stash kptr into map values with bpf_kptr_xchg().
This patch further supports stashing kptr into local kptr by adding local
kptr as a valid destination type.

When stashing into local kptr, btf_record in program BTF is used instead
of btf_record in map to search for the btf_field of the local kptr.

The local kptr specific checks in check_reg_type() only apply when the
source argument of bpf_kptr_xchg() is local kptr. Therefore, we make the
scope of the check explicit as the destination now can also be local kptr.

Acked-by: Martin KaFai Lau <martin.lau@kernel.org>
Signed-off-by: Dave Marchevsky <davemarchevsky@fb.com>
Signed-off-by: Amery Hung <amery.hung@bytedance.com>
Link: https://lore.kernel.org/r/20240813212424.2871455-5-amery.hung@bytedance.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

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Dave Marchevsky 2024-08-13 21:24:23 +00:00 • committed by Alexei Starovoitov

parent d59232afb0

commit b0966c7245

3 changed files with 37 additions and 20 deletions

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9

include/uapi/linux/bpf.h

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4

kernel/bpf/helpers.c

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44

kernel/bpf/verifier.c

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