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bpf: Allow trampoline re-attach for tracing and lsm programs
Currently we don't allow re-attaching of trampolines. Once it's detached, it can't be re-attach even when the program is still loaded. Adding the possibility to re-attach the loaded tracing and lsm programs. Fixing missing unlock with proper cleanup goto jump reported by Julia. Reported-by: kernel test robot <lkp@intel.com> Reported-by: Julia Lawall <julia.lawall@lip6.fr> Signed-off-by: Jiri Olsa <jolsa@kernel.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Toke Høiland-Jørgensen <toke@redhat.com> Acked-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: KP Singh <kpsingh@kernel.org> Link: https://lore.kernel.org/bpf/20210414195147.1624932-2-jolsa@kernel.org
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parent
0ea1041bfa
commit
f3a9507554
kernel/bpf
@ -2650,13 +2650,24 @@ static int bpf_tracing_prog_attach(struct bpf_prog *prog,
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* - if tgt_prog == NULL when this function was called using the old
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* raw_tracepoint_open API, and we need a target from prog->aux
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*
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* The combination of no saved target in prog->aux, and no target
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* specified on load is illegal, and we reject that here.
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* - if prog->aux->dst_trampoline and tgt_prog is NULL, the program
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* was detached and is going for re-attachment.
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*/
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if (!prog->aux->dst_trampoline && !tgt_prog) {
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err = -ENOENT;
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/*
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* Allow re-attach for TRACING and LSM programs. If it's
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* currently linked, bpf_trampoline_link_prog will fail.
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* EXT programs need to specify tgt_prog_fd, so they
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* re-attach in separate code path.
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*/
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if (prog->type != BPF_PROG_TYPE_TRACING &&
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prog->type != BPF_PROG_TYPE_LSM) {
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err = -EINVAL;
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goto out_unlock;
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}
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btf_id = prog->aux->attach_btf_id;
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key = bpf_trampoline_compute_key(NULL, prog->aux->attach_btf, btf_id);
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}
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if (!prog->aux->dst_trampoline ||
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(key && key != prog->aux->dst_trampoline->key)) {
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@ -444,7 +444,7 @@ int bpf_trampoline_link_prog(struct bpf_prog *prog, struct bpf_trampoline *tr)
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tr->progs_cnt[kind]++;
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err = bpf_trampoline_update(tr);
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if (err) {
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hlist_del(&prog->aux->tramp_hlist);
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hlist_del_init(&prog->aux->tramp_hlist);
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tr->progs_cnt[kind]--;
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}
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out:
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@ -467,7 +467,7 @@ int bpf_trampoline_unlink_prog(struct bpf_prog *prog, struct bpf_trampoline *tr)
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tr->extension_prog = NULL;
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goto out;
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}
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hlist_del(&prog->aux->tramp_hlist);
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hlist_del_init(&prog->aux->tramp_hlist);
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tr->progs_cnt[kind]--;
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err = bpf_trampoline_update(tr);
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out:
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