bpf: verifier: refactor check_attach_btf_id()
The check_attach_btf_id() function really does three things: 1. It performs a bunch of checks on the program to ensure that the attachment is valid. 2. It stores a bunch of state about the attachment being requested in the verifier environment and struct bpf_prog objects. 3. It allocates a trampoline for the attachment. This patch splits out (1.) and (3.) into separate functions which will perform the checks, but return the computed values instead of directly modifying the environment. This is done in preparation for reusing the checks when the actual attachment is happening, which will allow tracing programs to have multiple (compatible) attachments. This also fixes a bug where a bunch of checks were skipped if a trampoline already existed for the tracing target. Fixes: 6ba43b76 ("bpf: Attachment verification for BPF_MODIFY_RETURN") Fixes: 1e6c62a8 ("bpf: Introduce sleepable BPF programs") Acked-by:Andrii Nakryiko <andriin@fb.com> Signed-off-by:
Toke Høiland-Jørgensen <toke@redhat.com> Signed-off-by:
Alexei Starovoitov <ast@kernel.org>
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