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| author | Toke Høiland-Jørgensen <toke@redhat.com> | 2020-09-29 14:45:50 +0200 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2020-09-29 13:09:23 -0700 |
| commit | 3aac1ead5eb6b76f3d2b8d111e6de1c2de23fb34 (patch) | |
| tree | fb66fb0f2de431275e8c5a09d896a97f9641dacb /kernel/bpf/verifier.c | |
| parent | 85e3f318506ece12714535821d0b3186f7121b5b (diff) | |
| download | lwn-3aac1ead5eb6b76f3d2b8d111e6de1c2de23fb34.tar.gz lwn-3aac1ead5eb6b76f3d2b8d111e6de1c2de23fb34.zip | |
bpf: Move prog->aux->linked_prog and trampoline into bpf_link on attach
In preparation for allowing multiple attachments of freplace programs, move
the references to the target program and trampoline into the
bpf_tracing_link structure when that is created. To do this atomically,
introduce a new mutex in prog->aux to protect writing to the two pointers
to target prog and trampoline, and rename the members to make it clear that
they are related.
With this change, it is no longer possible to attach the same tracing
program multiple times (detaching in-between), since the reference from the
tracing program to the target disappears on the first attach. However,
since the next patch will let the caller supply an attach target, that will
also make it possible to attach to the same place multiple times.
Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/160138355059.48470.2503076992210324984.stgit@toke.dk
Diffstat (limited to 'kernel/bpf/verifier.c')
| -rw-r--r-- | kernel/bpf/verifier.c | 11 |
1 files changed, 7 insertions, 4 deletions
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 2ee343dda73a..a97a2f2964e3 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -2648,8 +2648,7 @@ static int check_map_access(struct bpf_verifier_env *env, u32 regno, static enum bpf_prog_type resolve_prog_type(struct bpf_prog *prog) { - return prog->aux->linked_prog ? prog->aux->linked_prog->type - : prog->type; + return prog->aux->dst_prog ? prog->aux->dst_prog->type : prog->type; } static bool may_access_direct_pkt_data(struct bpf_verifier_env *env, @@ -11475,7 +11474,7 @@ int bpf_check_attach_target(struct bpf_verifier_log *log, static int check_attach_btf_id(struct bpf_verifier_env *env) { struct bpf_prog *prog = env->prog; - struct bpf_prog *tgt_prog = prog->aux->linked_prog; + struct bpf_prog *tgt_prog = prog->aux->dst_prog; struct bpf_attach_target_info tgt_info = {}; u32 btf_id = prog->aux->attach_btf_id; struct bpf_trampoline *tr; @@ -11501,6 +11500,10 @@ static int check_attach_btf_id(struct bpf_verifier_env *env) return ret; if (tgt_prog && prog->type == BPF_PROG_TYPE_EXT) { + /* to make freplace equivalent to their targets, they need to + * inherit env->ops and expected_attach_type for the rest of the + * verification + */ env->ops = bpf_verifier_ops[tgt_prog->type]; prog->expected_attach_type = tgt_prog->expected_attach_type; } @@ -11529,7 +11532,7 @@ static int check_attach_btf_id(struct bpf_verifier_env *env) if (!tr) return -ENOMEM; - prog->aux->trampoline = tr; + prog->aux->dst_trampoline = tr; return 0; } |