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=-6.9 required=3.0 tests=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 autolearn=unavailable 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 5A53FC433DF for ; Mon, 15 Jun 2020 14:44:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3424520679 for ; Mon, 15 Jun 2020 14:44:05 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=cloudflare.com header.i=@cloudflare.com header.b="Kvpm8lif" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730686AbgFOOn6 (ORCPT ); Mon, 15 Jun 2020 10:43:58 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40234 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730405AbgFOOn6 (ORCPT ); Mon, 15 Jun 2020 10:43:58 -0400 Received: from mail-oo1-xc41.google.com (mail-oo1-xc41.google.com [IPv6:2607:f8b0:4864:20::c41]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0F115C05BD43 for ; Mon, 15 Jun 2020 07:43:57 -0700 (PDT) Received: by mail-oo1-xc41.google.com with SMTP id y45so3396398ooi.8 for ; Mon, 15 Jun 2020 07:43:57 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=cloudflare.com; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=r8im4dJtuxkkAaqZZS6bmcni2naI0KL21K/0KZhRnTg=; b=Kvpm8lif52moFLeMmaNKGAHoyXK5aBJWB+oAUhzGn06yJXqIvn/PnfObLHY9dxrmon 3LBcru7CGHTqvQ2q9h7SG/2RHOsw3K4VKzqDapSU6QXnYY72ZBKse0+FifGxXpmZGSa2 WqECeuk02tQWmywJxEP3fjo9i0CJIQPSkhfB4= 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=r8im4dJtuxkkAaqZZS6bmcni2naI0KL21K/0KZhRnTg=; b=oEXbGrjDpE5O/rlpgLiIhC2kcfVvhsqCr2YzJ2S82nJjXc1/cbFGkhY5OnBH4VCcPj 1tgOcOKC3u0NbZhbhVtGv8AeHBQ1Nvc8jbPF97E3wirZgL076Lcagrouwdd2C4g8Lnpa gDcYKKKMUR1jV68waJi2C8gkjhVr8O35DMI7+1II3brfv9NTzDjMFHjaXK+0q2isT22q uxeZTjyOHLf8MppHXT5Vd0eQ5MUQgAJaBbockuAZnLRSYf8yXs3CdOUPxAIP+7FB/4b8 Ce38CaYGJNgZ24VS4KYGxg2FGyjg2Gmyuom58XRjhfk2icMZvBSqO+Zu8j4Vs+qkVmZ3 BPmw== X-Gm-Message-State: AOAM531lh8mHcGNEA+HTHCzC2Ff4NECrzA9pRa0TEEa2uhgVweSBNHDH 6dcZFyNneQY4QZsttN1wqouIHmFUYYQU3bM/AxhOPQ== X-Google-Smtp-Source: ABdhPJzQC7JHZFZ5lcxDRbQbodCqupHVOnlokMDpxwYb3ub+OdcyuaHCeS2Lw5IKYZvlIc7mtPcUVZqSHhJ+MgwjgzQ= X-Received: by 2002:a4a:3559:: with SMTP id w25mr21208459oog.6.1592232236922; Mon, 15 Jun 2020 07:43:56 -0700 (PDT) MIME-Version: 1.0 References: <20200612160141.188370-1-lmb@cloudflare.com> In-Reply-To: From: Lorenz Bauer Date: Mon, 15 Jun 2020 15:43:45 +0100 Message-ID: Subject: Re: [PATCH bpf 1/2] flow_dissector: reject invalid attach_flags To: Alexei Starovoitov Cc: Alexei Starovoitov , Daniel Borkmann , Jakub Sitnicki , kernel-team , Network Development , bpf , LKML Content-Type: text/plain; charset="UTF-8" Sender: bpf-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On Fri, 12 Jun 2020 at 23:36, Alexei Starovoitov wrote: > > On Fri, Jun 12, 2020 at 9:02 AM Lorenz Bauer wrote: > > > > Using BPF_PROG_ATTACH on a flow dissector program supports neither flags > > nor target_fd but accepts any value. Return EINVAL if either are non-zero. > > > > Signed-off-by: Lorenz Bauer > > Fixes: b27f7bb590ba ("flow_dissector: Move out netns_bpf prog callbacks") > > --- > > kernel/bpf/net_namespace.c | 3 +++ > > 1 file changed, 3 insertions(+) > > > > diff --git a/kernel/bpf/net_namespace.c b/kernel/bpf/net_namespace.c > > index 78cf061f8179..56133e78ae4f 100644 > > --- a/kernel/bpf/net_namespace.c > > +++ b/kernel/bpf/net_namespace.c > > @@ -192,6 +192,9 @@ int netns_bpf_prog_attach(const union bpf_attr *attr, struct bpf_prog *prog) > > struct net *net; > > int ret; > > > > + if (attr->attach_flags || attr->target_fd) > > + return -EINVAL; > > + > > In theory it makes sense, but how did you test it? Not properly it seems, sorry! > test_progs -t flow > fails 5 tests. I spent today digging through this, and the issue is actually more annoying than I thought. BPF_PROG_DETACH for sockmap and flow_dissector ignores attach_bpf_fd. The cgroup and lirc2 attach point use this to make sure that the program being detached is actually what user space expects. We actually have tests that set attach_bpf_fd for these to attach points, which tells me that this is an easy mistake to make. Unfortunately I can't come up with a good fix that seems backportable: - Making sockmap and flow_dissector have the same semantics as cgroup and lirc2 requires a bunch of changes (probably a new function for sockmap) - Returning EINVAL from BPF_PROG_DETACH if attach_bpf_fd is specified leads to a lot of churn in selftests Is it worth just landing these fixes on bpf or bpf-next without backporting them? -- Lorenz Bauer | Systems Engineer 6th Floor, County Hall/The Riverside Building, SE1 7PB, UK www.cloudflare.com