[PATCHv4 bpf-next 1/2] bpf: Do not allow to load sleepable BPF_TRACE_RAW_TP program

[Jiri Olsa <jolsa@kernel.org>]

Currently we allow to load any tracing program as sleepable,
but BPF_TRACE_RAW_TP can't sleep. Making the check explicit
for tracing programs attach types, so sleepable BPF_TRACE_RAW_TP
will fail to load.

Updating the verifier error to mention iter programs as well.

Acked-by: Song Liu <song@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
v4 changes:
  - remove kprobe from verifier output and add uprobe comment [Yonghong]
  - added ack [Yonghong]

 kernel/bpf/verifier.c | 22 +++++++++++++++++++---
 1 file changed, 19 insertions(+), 3 deletions(-)

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index fa4c911603e9..ca7db2ce70b9 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -16743,6 +16743,23 @@ BTF_ID(func, rcu_read_unlock_strict)
 #endif
 BTF_SET_END(btf_id_deny)
 
+static bool can_be_sleepable(struct bpf_prog *prog)
+{
+	if (prog->type == BPF_PROG_TYPE_TRACING) {
+		switch (prog->expected_attach_type) {
+		case BPF_TRACE_FENTRY:
+		case BPF_TRACE_FEXIT:
+		case BPF_MODIFY_RETURN:
+		case BPF_TRACE_ITER:
+			return true;
+		default:
+			return false;
+		}
+	}
+	return prog->type == BPF_PROG_TYPE_LSM ||
+	       prog->type == BPF_PROG_TYPE_KPROBE; /* only for uprobes */
+}
+
 static int check_attach_btf_id(struct bpf_verifier_env *env)
 {
 	struct bpf_prog *prog = env->prog;
@@ -16761,9 +16778,8 @@ static int check_attach_btf_id(struct bpf_verifier_env *env)
 		return -EINVAL;
 	}
 
-	if (prog->aux->sleepable && prog->type != BPF_PROG_TYPE_TRACING &&
-	    prog->type != BPF_PROG_TYPE_LSM && prog->type != BPF_PROG_TYPE_KPROBE) {
-		verbose(env, "Only fentry/fexit/fmod_ret, lsm, and kprobe/uprobe programs can be sleepable\n");
+	if (prog->aux->sleepable && !can_be_sleepable(prog)) {
+		verbose(env, "Only fentry/fexit/fmod_ret, lsm, iter and uprobe programs can be sleepable\n");
 		return -EINVAL;
 	}
 
-- 
2.39.0