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authorJiri Olsa <jolsa@kernel.org>2021-04-14 22:51:41 +0300
committerAlexei Starovoitov <ast@kernel.org>2021-04-26 07:09:01 +0300
commitf3a95075549e0e5c36db922caf86847db7a35403 (patch)
treefda5699680b0734c9371b80de632aef553c93750 /kernel
parent0ea1041bfa3aa2971f858edd9e05477c2d3d54a0 (diff)
downloadlinux-f3a95075549e0e5c36db922caf86847db7a35403.tar.xz
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
Diffstat (limited to 'kernel')
-rw-r--r--kernel/bpf/syscall.c23
-rw-r--r--kernel/bpf/trampoline.c4
2 files changed, 19 insertions, 8 deletions
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index fd495190115e..941ca06d9dfa 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -2648,14 +2648,25 @@ static int bpf_tracing_prog_attach(struct bpf_prog *prog,
* target_btf_id using the link_create API.
*
* - if tgt_prog == NULL when this function was called using the old
- * raw_tracepoint_open API, and we need a target from prog->aux
- *
- * The combination of no saved target in prog->aux, and no target
- * specified on load is illegal, and we reject that here.
+ * raw_tracepoint_open API, and we need a target from prog->aux
+ *
+ * - if prog->aux->dst_trampoline and tgt_prog is NULL, the program
+ * was detached and is going for re-attachment.
*/
if (!prog->aux->dst_trampoline && !tgt_prog) {
- err = -ENOENT;
- goto out_unlock;
+ /*
+ * Allow re-attach for TRACING and LSM programs. If it's
+ * currently linked, bpf_trampoline_link_prog will fail.
+ * EXT programs need to specify tgt_prog_fd, so they
+ * re-attach in separate code path.
+ */
+ if (prog->type != BPF_PROG_TYPE_TRACING &&
+ prog->type != BPF_PROG_TYPE_LSM) {
+ err = -EINVAL;
+ goto out_unlock;
+ }
+ btf_id = prog->aux->attach_btf_id;
+ key = bpf_trampoline_compute_key(NULL, prog->aux->attach_btf, btf_id);
}
if (!prog->aux->dst_trampoline ||
diff --git a/kernel/bpf/trampoline.c b/kernel/bpf/trampoline.c
index 4aa8b52adf25..2d44b5aa0057 100644
--- a/kernel/bpf/trampoline.c
+++ b/kernel/bpf/trampoline.c
@@ -444,7 +444,7 @@ int bpf_trampoline_link_prog(struct bpf_prog *prog, struct bpf_trampoline *tr)
tr->progs_cnt[kind]++;
err = bpf_trampoline_update(tr);
if (err) {
- hlist_del(&prog->aux->tramp_hlist);
+ hlist_del_init(&prog->aux->tramp_hlist);
tr->progs_cnt[kind]--;
}
out:
@@ -467,7 +467,7 @@ int bpf_trampoline_unlink_prog(struct bpf_prog *prog, struct bpf_trampoline *tr)
tr->extension_prog = NULL;
goto out;
}
- hlist_del(&prog->aux->tramp_hlist);
+ hlist_del_init(&prog->aux->tramp_hlist);
tr->progs_cnt[kind]--;
err = bpf_trampoline_update(tr);
out: