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Andrii Nakryiko says: ==================== Enhance BPF global subprogs with argument tags This patch set adds verifier support for annotating user's global BPF subprog arguments with few commonly requested annotations, to improve global subprog verification experience. These tags are: - ability to annotate a special PTR_TO_CTX argument; - ability to annotate a generic PTR_TO_MEM as non-null. We utilize btf_decl_tag attribute for this and provide two helper macros as part of bpf_helpers.h in libbpf (patch #8). Besides this we also add abilit to pass a pointer to dynptr into global subprog. This is done based on type name match (struct bpf_dynptr *). This allows to pass dynptrs into global subprogs, for use cases that deal with variable-sized generic memory pointers. Big chunk of the patch set (patches #1 through #5) are various refactorings to make verifier internals around global subprog validation logic easier to extend and support long term, eliminating BTF parsing logic duplication, factoring out argument expectation definitions from BTF parsing, etc. New functionality is added in patch #6 (ctx and non-null) and patch #7 (dynptr), extending global subprog checks with awareness for arg tags. Patch #9 adds simple tests validating each of the added tags and dynptr argument passing. Patch #10 adds a simple negative case for freplace programs to make sure that target BPF programs with "unreliable" BTF func proto cannot be freplaced. v2->v3: - patch #10 improved by checking expected verifier error (Eduard); v1->v2: - dropped packet args for now (Eduard); - added back unreliable=true detection for entry BPF programs (Eduard); - improved subprog arg validation (Eduard); - switched dynptr arg from tag to just type name based check (Eduard). ==================== Link: https://lore.kernel.org/r/20231215011334.2307144-1-andrii@kernel.org Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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