From: Martin KaFai Lau Date: Wed, 11 Sep 2024 15:48:50 +0000 (-0700) Subject: Merge branch 'bpf: Allow skb dynptr for tp_btf' X-Git-Url: https://git.kernel.dk/?a=commitdiff_plain;h=fdfd9d82a43a7a50b9d0989a0440d12a3d68ea15;p=linux-block.git Merge branch 'bpf: Allow skb dynptr for tp_btf' Philo Lu says: ==================== This makes bpf_dynptr_from_skb usable for tp_btf, so that we can easily parse skb in tracepoints. This has been discussed in [0], and Martin suggested to use dynptr (instead of helpers like bpf_skb_load_bytes). For safety, skb dynptr shouldn't be used in fentry/fexit. This is achieved by add KF_TRUSTED_ARGS flag in bpf_dynptr_from_skb defination, because pointers passed by tracepoint are trusted (PTR_TRUSTED) while those of fentry/fexit are not. Another problem raises that NULL pointers could be passed to tracepoint, such as trace_tcp_send_reset, and we need to recognize them. This is done by add a "__nullable" suffix in the func_proto of the tracepoint, discussed in [1]. 2 Test cases are added, one for "__nullable" suffix, and the other for using skb dynptr in tp_btf. changelog v2 -> v3 (Andrii Nakryiko): Patch 1: - Remove prog type check in prog_arg_maybe_null() - Add bpf_put_raw_tracepoint() after get() - Use kallsyms_lookup() instead of sprintf("%ps") Patch 2: Add separate test "tp_btf_nullable", and use full failure msg v1 -> v2: - Add "__nullable" suffix support (Alexei Starovoitov) - Replace "struct __sk_buff*" with "void*" in test (Martin KaFai Lau) [0] https://lore.kernel.org/all/20240205121038.41344-1-lulie@linux.alibaba.com/T/ [1] https://lore.kernel.org/all/20240430121805.104618-1-lulie@linux.alibaba.com/T/ ==================== Signed-off-by: Martin KaFai Lau --- fdfd9d82a43a7a50b9d0989a0440d12a3d68ea15