From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 58983C2D0A3 for ; Wed, 4 Nov 2020 22:44:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id F3F9E20BED for ; Wed, 4 Nov 2020 22:44:37 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="IFzi+wpr" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732475AbgKDWoh (ORCPT ); Wed, 4 Nov 2020 17:44:37 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38656 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732518AbgKDWod (ORCPT ); Wed, 4 Nov 2020 17:44:33 -0500 Received: from mail-lj1-x241.google.com (mail-lj1-x241.google.com [IPv6:2a00:1450:4864:20::241]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5676DC0613D2 for ; Wed, 4 Nov 2020 14:44:31 -0800 (PST) Received: by mail-lj1-x241.google.com with SMTP id l10so188124lji.4 for ; Wed, 04 Nov 2020 14:44:31 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=ktpmn2NX0J5OPT7QN9c8op6gbH7kVw1jxv9tLBj7cuc=; b=IFzi+wpry5wW+UcbEC2QWIKhQYjtR1ggicBVKASHjN2NV+62ExLtw0CYZFhffyZaXL 4wTGZ6IFAYjBXdxC509EJd1UuJfOZjza4SMu0WCgKRO5+PLp6Z3oo3u+GOMeeADnqSx+ E53VmeaTZqtXGiTWQogT9aH06dJf/lXRuON2c= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=ktpmn2NX0J5OPT7QN9c8op6gbH7kVw1jxv9tLBj7cuc=; b=TdGSpHoB2QPc7km3n5VTGLwXttf2wkdiDyD4NreATzkBqN/bxWrnBE/WlHg3OHhOQ0 SL39tJrb5MOs2Hb8Il34IGsPMs2Pid7+wSvA78AwOb6C4uaLxpMWLEx5hmoyJ1daXvkR W3xYrwq0M699rHcbOl7Zv6AfbcaBNZ9BXZPpPG4yuOugm9t7vNEepW8J8ScY0ASn64vB dIInfhd1Eyj1pOFDPcB3ab5vULlYevA5oZ6CTUg3hzMRDZS2CodSt+Fb1wY9nx20cAau SWINzv/anzHlx8CjCj4nlWlEEWWg8iEjPnG734zdlFrtMisd85rH/ybitAPmm8XQ9aOW vt7w== X-Gm-Message-State: AOAM53254Wx9O/7AcM7Uf/G4Bwnkft4U9F5c/SO/YzSGad1R4pleHh9j OC0adaWe2tleiAQsHrAU8oOxpw1J0ftRCtWy1iHoqw== X-Google-Smtp-Source: ABdhPJzm68ST7IajXhinHgxQieZdPSWnEWAiPZh6ZuCwMd/GrrlZYyo+OqdFWO/eE/CGMKWBWkLVz2Bh2AbNfubgAM0= X-Received: by 2002:a2e:1517:: with SMTP id s23mr71620ljd.83.1604529869714; Wed, 04 Nov 2020 14:44:29 -0800 (PST) MIME-Version: 1.0 References: <20201104164453.74390-1-kpsingh@chromium.org> <20201104164453.74390-6-kpsingh@chromium.org> <20201104223539.pwtwnx6penoqm37j@kafai-mbp.dhcp.thefacebook.com> In-Reply-To: <20201104223539.pwtwnx6penoqm37j@kafai-mbp.dhcp.thefacebook.com> From: KP Singh Date: Wed, 4 Nov 2020 23:44:19 +0100 Message-ID: Subject: Re: [PATCH bpf-next v3 5/9] bpf: Allow LSM programs to use bpf spin locks To: Martin KaFai Lau Cc: open list , bpf , Alexei Starovoitov , Daniel Borkmann , Song Liu , Paul Turner , Jann Horn , Hao Luo Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On Wed, Nov 4, 2020 at 11:35 PM Martin KaFai Lau wrote: > > On Wed, Nov 04, 2020 at 05:44:49PM +0100, KP Singh wrote: > > From: KP Singh > > > > Usage of spin locks was not allowed for tracing programs due to > > insufficient preemption checks. The verifier does not currently prevent > > LSM programs from using spin locks, but the helpers are not exposed > > via bpf_lsm_func_proto. > This could be the first patch but don't feel strongly about it. > > > > > Based on the discussion in [1], non-sleepable LSM programs should be > > able to use bpf_spin_{lock, unlock}. > > > > Sleepable LSM programs can be preempted which means that allowng spin > > locks will need more work (disabling preemption and the verifier > > ensuring that no sleepable helpers are called when a spin lock is held). > > > > [1]: https://lore.kernel.org/bpf/20201103153132.2717326-1-kpsingh@chromium.org/T/#md601a053229287659071600d3483523f752cd2fb > > > > Signed-off-by: KP Singh > > --- > > kernel/bpf/bpf_lsm.c | 4 ++++ > > kernel/bpf/verifier.c | 17 +++++++++++++++++ > > 2 files changed, 21 insertions(+) > > > > 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..7c6c246077cf 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; > > + } > It is good to have a more specific verifier log. However, > these are duplicated checks (a few lines above in the same function). > They should at least be removed. > Thanks, I fixed this up and will move this as the first patch. > > + > > + if (prog->aux->sleepable) { > > + verbose(env, "sleepable progs cannot use bpf_spin_lock yet\n"); > > + return -EINVAL; > > + } > > + } > > + > > if ((bpf_prog_is_dev_bound(prog->aux) || bpf_map_is_dev_bound(map)) && > > !bpf_offload_prog_map_match(prog, map)) { > > verbose(env, "offload device mismatch between prog and map\n"); > > -- > > 2.29.1.341.ge80a0c044ae-goog > >