On Wed, Jan 11, 2023 at 2:13 AM Jiri Olsa <jolsa@xxxxxxxxxx> 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.
>
> Signed-off-by: Jiri Olsa <jolsa@xxxxxxxxxx>
Acked-by: Song Liu <song@xxxxxxxxxx>
> ---
> v2 changes:
> - use bool for can_be_sleepable return value [Song]
> - add tests [Song]
>
> kernel/bpf/verifier.c | 17 ++++++++++++++---
> 1 file changed, 14 insertions(+), 3 deletions(-)
>
> diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
> index fa4c911603e9..f20777c2a957 100644
> --- a/kernel/bpf/verifier.c
> +++ b/kernel/bpf/verifier.c
> @@ -16743,6 +16743,18 @@ 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) {
> + return prog->expected_attach_type == BPF_TRACE_FENTRY ||
> + prog->expected_attach_type == BPF_TRACE_FEXIT ||
> + prog->expected_attach_type == BPF_MODIFY_RETURN ||
> + prog->expected_attach_type == BPF_TRACE_ITER;
> + }
> + 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 +16773,8 @@ 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");
> return -EINVAL;
> }
>
> --
> 2.39.0
>
