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=-2.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no 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 D40ECC433B4 for ; Sat, 3 Apr 2021 13:29:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9341F610D1 for ; Sat, 3 Apr 2021 13:29:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236698AbhDCN3H (ORCPT ); Sat, 3 Apr 2021 09:29:07 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59976 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236687AbhDCN3G (ORCPT ); Sat, 3 Apr 2021 09:29:06 -0400 Received: from mail-io1-xd33.google.com (mail-io1-xd33.google.com [IPv6:2607:f8b0:4864:20::d33]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9156AC0613E6; Sat, 3 Apr 2021 06:29:03 -0700 (PDT) Received: by mail-io1-xd33.google.com with SMTP id v26so7778945iox.11; Sat, 03 Apr 2021 06:29:03 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc:content-transfer-encoding; bh=SWygQCqYJBcPdL7J1tLNEfA+a85qIQLhd/8toqYvPTY=; b=RcCal+FaiZlVHr9+Itmdy5eyBBDc1E+duNmvNCUnDHX5FimjB4mtCaC3BQGjWkd/+T ja7+iww0gg8b2bSV8nAv3ja+XOLgHcJKKgO14auqx53IRcgAzdRI0fjkshKdejnoCXDW f0N0voeHWUpggPsQ6Io3hFqRfajoNQSsEd4P0n8g2facYNpNi+pZewvZOD0th1h75GeI 7A3RkHNa9sQ2G39WwX7rEsZchBvN3rrWYyUyzwCCDBmH7I0dlz3ZzTCJPoQi+/GUdb5h dnRjcutXMml57UYIwoOvJPmUUpntiLfj3RDW0SSrht+KW37De1ZQ3vsGloQa2BNBFHzm gDUQ== 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:content-transfer-encoding; bh=SWygQCqYJBcPdL7J1tLNEfA+a85qIQLhd/8toqYvPTY=; b=nMuxSPcZspsXagqVvdklKIjSqv1/6VppzDRJ5qROlVRacZ/C4435uB9jHwTbBNM/nV o8o6I/igDHjtLaQO9aw6VMgveAiBZ63AXPtjCgJybRrsTlaNUlZNvQigqZnLQ6PghTDF t35q2VLKlDWGijMvLeX7Zu65DvL3KjaIbnKOpL+LWxkanuNkvrM7FotFP9De8ocjWXop V2X35moT5b+4AJitycG/vyGBbWabOdf+z+UGkCFZHCd4AUNjd5a63TPWpP+FcVZCop1J F3exfCbn1BhIUAiotI7dNkDpw0ghwgzmuC6aGvmeCgNKduFcCBW9CA5uHuoZjSBcgfWc xH9w== X-Gm-Message-State: AOAM532nBNvCs3UN6zZ7aliSryrjrIfgujd/S6OWyawdmAHwAZSkYgpb pPbkAhgfMCBL70Ow4mktK4AjjvhXitggDZho1IY= X-Google-Smtp-Source: ABdhPJxxrKXQHHQY41eKZq2fLVXoyDOq2SytVF0laLpS7kdw5Sg8Debs7tTWKHsJdFRTuswjmjUzv7oJkK3mFDRX1lM= X-Received: by 2002:a02:c908:: with SMTP id t8mr16841871jao.78.1617456542948; Sat, 03 Apr 2021 06:29:02 -0700 (PDT) MIME-Version: 1.0 References: <20210330223748.399563-1-pctammela@mojatatu.com> In-Reply-To: From: Pedro Tammela Date: Sat, 3 Apr 2021 10:28:51 -0300 Message-ID: Subject: Re: [PATCH bpf-next v2] bpf: check flags in 'bpf_ringbuf_discard()' and 'bpf_ringbuf_submit()' To: Andrii Nakryiko Cc: Alexei Starovoitov , Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Martin KaFai Lau , Song Liu , Yonghong Song , John Fastabend , KP Singh , Joe Stringer , Quentin Monnet , "open list:BPF (Safe dynamic programs and tools)" , "open list:BPF (Safe dynamic programs and tools)" , open list , Pedro Tammela Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org Em qua., 31 de mar. de 2021 =C3=A0s 04:02, Andrii Nakryiko escreveu: > > On Tue, Mar 30, 2021 at 4:16 PM Alexei Starovoitov > wrote: > > > > On Tue, Mar 30, 2021 at 3:54 PM Pedro Tammela wro= te: > > > > > > BPF_CALL_2(bpf_ringbuf_submit, void *, sample, u64, flags) > > > { > > > + if (unlikely(flags & ~(BPF_RB_NO_WAKEUP | BPF_RB_FORCE_WAKEUP= ))) > > > + return -EINVAL; > > > + > > > bpf_ringbuf_commit(sample, flags, false /* discard */); > > > + > > > return 0; > > > > I think ringbuf design was meant for bpf_ringbuf_submit to never fail. > > If we do flag validation it probably should be done at the verifier tim= e. > > Oops, replied on another version already. But yes, BPF verifier relies > on it succeeding. I don't think we can do flags validation at BPF > verification time, though, because it is defined as non-const integer > and we do have valid cases where we dynamically determine whether to > FORCE_WAKEUP or NO_WAKEUP, based on application-driven criteria (e.g., > amount of enqueued data). Then shouldn't we remove the flags check in 'bpf_ringbuf_output()'?