From: KP Singh <kpsingh@chromium.org>
To: John Fastabend <john.fastabend@gmail.com>
Cc: Alexei Starovoitov <alexei.starovoitov@gmail.com>,
open list <linux-kernel@vger.kernel.org>,
bpf <bpf@vger.kernel.org>, Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Martin KaFai Lau <kafai@fb.com>, Song Liu <songliubraving@fb.com>,
Paul Turner <pjt@google.com>, Jann Horn <jannh@google.com>,
Hao Luo <haoluo@google.com>
Subject: Re: [PATCH bpf-next v2 7/8] bpf: Add tests for task_local_storage
Date: Wed, 4 Nov 2020 12:11:28 +0100 [thread overview]
Message-ID: <CACYkzJ50d65j3kfQUdoLXOx+t-6UDK7mhb0M_oF8uoveXo+GYw@mail.gmail.com> (raw)
In-Reply-To: <CACYkzJ7v4TNopZ0VhFezax-i3TF59Ok2mfgb_W+mTH52fd_gRw@mail.gmail.com>
On Wed, Nov 4, 2020 at 12:03 PM KP Singh <kpsingh@chromium.org> wrote:
>
> [...]
>
> > > Ahh. Yes. That should do it. Right now I don't see concerns with safety
> > > of the bpf_spin_lock in bpf_lsm progs.
> >
> > What about sleepable lsm hooks? Normally we wouldn't expect to sleep with
> > a spinlock held. Should we have a check to ensure programs bpf_spin_lock
> > are not also sleepable?
>
> Thanks. Yes, I added that to my patch:
>
> diff --git a/kernel/bpf/bpf_lsm.c b/kernel/bpf/bpf_lsm.c
> index 61f8cc52fd5b..93383df2140b 100644
> --- a/kernel/bpf/bpf_lsm.c
> +++ b/kernel/bpf/bpf_lsm.c
> @@ -63,6 +63,10 @@ bpf_lsm_func_proto(enum bpf_func_id func_id, const
> struct bpf_prog *prog)
> return &bpf_task_storage_get_proto;
> case BPF_FUNC_task_storage_delete:
> return &bpf_task_storage_delete_proto;
> + case BPF_FUNC_spin_lock:
> + return &bpf_spin_lock_proto;
> + case BPF_FUNC_spin_unlock:
> + return &bpf_spin_unlock_proto;
> default:
> return tracing_prog_func_proto(func_id, prog);
> }
> diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
> index 314018e8fc12..8892f7ba2041 100644
> --- a/kernel/bpf/verifier.c
> +++ b/kernel/bpf/verifier.c
> @@ -9739,6 +9739,23 @@ static int check_map_prog_compatibility(struct
> bpf_verifier_env *env,
> return -EINVAL;
> }
>
> + if (map_value_has_spin_lock(map)) {
> + if (prog_type == BPF_PROG_TYPE_SOCKET_FILTER) {
> + verbose(env, "socket filter progs cannot use
> bpf_spin_lock yet\n");
> + return -EINVAL;
> + }
> +
> + if (is_tracing_prog_type(prog_type)) {
> + verbose(env, "tracing progs cannot use
> bpf_spin_lock yet\n");
> + return -EINVAL;
> + }
> +
> + if (prog->aux->sleepable) {
> + verbose(env, "sleepable progs cannot use
> bpf_spin_lock\n");
I think this can still be "yet" as it's doable; we can disable/enable
preemption in the helpers
and then have the verifier track that no sleepable helper is called
when a spin lock is held.
I would, however, prefer if we do it in a subsequent patch.
- KP
> + return -EINVAL;
> + }
> + }
> +
next prev parent reply other threads:[~2020-11-04 11:11 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-03 15:31 [PATCH bpf-next v2 0/8] Implement task_local_storage KP Singh
2020-11-03 15:31 ` [PATCH bpf-next v2 1/8] bpf: Implement task local storage KP Singh
2020-11-03 23:47 ` Song Liu
2020-11-03 23:54 ` KP Singh
2020-11-03 15:31 ` [PATCH bpf-next v2 2/8] libbpf: Add support for " KP Singh
2020-11-03 19:28 ` Andrii Nakryiko
2020-11-03 20:28 ` KP Singh
2020-11-03 15:31 ` [PATCH bpf-next v2 3/8] bpftool: " KP Singh
2020-11-03 23:50 ` Song Liu
2020-11-03 15:31 ` [PATCH bpf-next v2 4/8] bpf: Implement get_current_task_btf and RET_PTR_TO_BTF_ID KP Singh
2020-11-03 23:57 ` Song Liu
2020-11-03 15:31 ` [PATCH bpf-next v2 5/8] bpf: Fix tests for local_storage KP Singh
2020-11-04 0:16 ` Song Liu
2020-11-03 15:31 ` [PATCH bpf-next v2 6/8] bpf: Update selftests for local_storage to use vmlinux.h KP Singh
2020-11-04 0:16 ` Song Liu
2020-11-03 15:31 ` [PATCH bpf-next v2 7/8] bpf: Add tests for task_local_storage KP Singh
2020-11-03 18:47 ` Alexei Starovoitov
2020-11-03 18:59 ` KP Singh
2020-11-04 0:05 ` KP Singh
2020-11-04 1:27 ` Alexei Starovoitov
2020-11-04 1:55 ` KP Singh
2020-11-04 1:57 ` Alexei Starovoitov
2020-11-04 6:51 ` John Fastabend
2020-11-04 11:03 ` KP Singh
2020-11-04 11:11 ` KP Singh [this message]
2020-11-03 15:31 ` [PATCH bpf-next v2 8/8] bpf: Exercise syscall operations for inode and sk storage KP Singh
2020-11-03 22:32 ` Song Liu
2020-11-03 22:58 ` KP Singh
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