On 1/17/23 1:20 AM, Jiri Olsa wrote:
On Mon, Jan 16, 2023 at 11:17:56PM -0800, Yonghong Song wrote:
On 1/16/23 5:29 AM, Jiri Olsa wrote:
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@xxxxxxxxxx>
Signed-off-by: Jiri Olsa <jolsa@xxxxxxxxxx>
Ack with a minor comment below.
Acked-by: Yonghong Song <yhs@xxxxxx>
---
v3 changes:
- use switch in can_be_sleepable [Alexei]
- added acks [Song]
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..966dbfc14288 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;
+}
+
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 kprobe/uprobe programs can be sleepable\n");
actually kprobe programs cannot be sleepable. See kernel/events/core.c.
perf_event_set_bpf_prog(...)
...
if (prog->type == BPF_PROG_TYPE_KPROBE && prog->aux->sleepable &&
!is_uprobe)
/* only uprobe programs are allowed to be sleepable */
return -EINVAL;
So I suggest to add a comment and remove the above 'kprobe' from error
message.
ok, is comment below ok?
Thanks! Sounds good to me.
jirka
---
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;
}
