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=-6.8 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,URIBL_BLOCKED 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 8EBA8C433E0 for ; Tue, 16 Jun 2020 08:30:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6A08220656 for ; Tue, 16 Jun 2020 08:30:24 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=cloudflare.com header.i=@cloudflare.com header.b="xNw2XJ3W" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727804AbgFPIaW (ORCPT ); Tue, 16 Jun 2020 04:30:22 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35068 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727119AbgFPIaU (ORCPT ); Tue, 16 Jun 2020 04:30:20 -0400 Received: from mail-ot1-x344.google.com (mail-ot1-x344.google.com [IPv6:2607:f8b0:4864:20::344]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9AF59C03E97C for ; Tue, 16 Jun 2020 01:30:18 -0700 (PDT) Received: by mail-ot1-x344.google.com with SMTP id u23so15332807otq.10 for ; Tue, 16 Jun 2020 01:30:18 -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=iFZu21anIecqeWnmtHDcKq9io7f3G/fD/2SgVahSB5o=; b=xNw2XJ3W6+QRI42l+XFlKIs2oUp3ZMllemOdGovEuifvIF3kEWzDFTdYX+xBKVJZe0 XZ+aHBfFXcExTyTXZx2pwIo6GF3KWtHNfN0wD8alb7/4mqnwZMoxYoZfDZcDY6mRwH7X 1OI8kbUZYWXgNEdjExp8YSuk1HrapdVEoQ5v4= 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=iFZu21anIecqeWnmtHDcKq9io7f3G/fD/2SgVahSB5o=; b=EFjVLLd+JYtkuOcwcmD37MI7KaxqDruHYf8t3CG/P2v30SpoY/fE85xYj349JD6PL8 Oj1eEyU+E/8P/jvGOqhRCt0L+MDTD2k71W7p92Kky8iwdDj+EL8X/+rgLskcYIytTM9N Gb7Qr4wcOJZMz0HfKe2frCS7DwNK0pA2wn2RtAXzMsUPQltV/a2oPjTfI7GSoxyjEfUM MZ6IoYt+FHGqCkb2aqOMubGExCjwMn1BbUcJdYhnH2W5P3FR/SYa2oh216f4mxKK0oUX DjHgupaBCym6ryr/eSq/W/UswEcj+11FUr9h9hes3SymyenZBoVH3euPz/ZX4buMDVZA SXig== X-Gm-Message-State: AOAM532MUNLIwaBsth15Q2yNpc00VvNVLuosucwS2GKJIZ02pWDjvAim dwiGlX8Rxx7I3Uq6684XOCe8ggOMXb/tvH23xRqy/Q== X-Google-Smtp-Source: ABdhPJxrzvbJdzoHn4DvVnkgACjbZuigtgxQERvnRr4I09yrEvDM8GB18hU9JmN3mH7A3JSLwqB26+Qq3j6dQyXGWTc= X-Received: by 2002:a9d:5cc1:: with SMTP id r1mr1384294oti.147.1592296217878; Tue, 16 Jun 2020 01:30:17 -0700 (PDT) MIME-Version: 1.0 References: <20200612160141.188370-1-lmb@cloudflare.com> In-Reply-To: From: Lorenz Bauer Date: Tue, 16 Jun 2020 09:30:06 +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 Tue, 16 Jun 2020 at 04:55, Alexei Starovoitov wrote: > > On Mon, Jun 15, 2020 at 7:43 AM Lorenz Bauer wrote: > > > > 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) > > making flow dissector pass prog_fd as cg and lirc is certainly my preference. > Especially since tests are passing fd user code is likely doing the same, > so breakage is unlikely. Also it wasn't done that long ago, so > we can backport far enough. > It will remove cap_net_admin ugly check in bpf_prog_detach() > which is the only exception now in cap model. SGTM. What about sockmap though? The code for that has been around for ages. -- Lorenz Bauer | Systems Engineer 6th Floor, County Hall/The Riverside Building, SE1 7PB, UK www.cloudflare.com