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=-20.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 5C20CC433FE for ; Fri, 4 Dec 2020 19:04:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 07FC022CA0 for ; Fri, 4 Dec 2020 19:04:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729132AbgLDTEX (ORCPT ); Fri, 4 Dec 2020 14:04:23 -0500 Received: from www62.your-server.de ([213.133.104.62]:56666 "EHLO www62.your-server.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726021AbgLDTEX (ORCPT ); Fri, 4 Dec 2020 14:04:23 -0500 Received: from sslproxy03.your-server.de ([88.198.220.132]) by www62.your-server.de with esmtpsa (TLSv1.3:TLS_AES_256_GCM_SHA384:256) (Exim 4.92.3) (envelope-from ) id 1klGMn-0000ZR-Iz; Fri, 04 Dec 2020 20:03:41 +0100 Received: from [85.7.101.30] (helo=pc-9.home) by sslproxy03.your-server.de with esmtpsa (TLSv1.3:TLS_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1klGMn-000D50-Cp; Fri, 04 Dec 2020 20:03:41 +0100 Subject: Re: [PATCH bpf-next v2 1/3] bpf: Expose bpf_get_socket_cookie to tracing programs From: Daniel Borkmann To: Florent Revest , bpf@vger.kernel.org Cc: ast@kernel.org, andrii@kernel.org, kpsingh@chromium.org, revest@google.com, linux-kernel@vger.kernel.org References: <20201203213330.1657666-1-revest@google.com> Message-ID: <7c70a64f-1aba-0e11-983d-9338f25a367e@iogearbox.net> Date: Fri, 4 Dec 2020 20:03:40 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.2 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit X-Authenticated-Sender: daniel@iogearbox.net X-Virus-Scanned: Clear (ClamAV 0.102.4/26007/Thu Dec 3 14:13:31 2020) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/4/20 7:56 PM, Daniel Borkmann wrote: > On 12/3/20 10:33 PM, Florent Revest wrote: >> This creates a new helper proto because the existing >> bpf_get_socket_cookie_sock_proto has a ARG_PTR_TO_CTX argument and only >> works for BPF programs where the context is a sock. >> >> This helper could also be useful to other BPF program types such as LSM. >> >> Signed-off-by: Florent Revest >> --- >>   include/uapi/linux/bpf.h       | 7 +++++++ >>   kernel/trace/bpf_trace.c       | 4 ++++ >>   net/core/filter.c              | 7 +++++++ >>   tools/include/uapi/linux/bpf.h | 7 +++++++ >>   4 files changed, 25 insertions(+) >> >> diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h >> index c3458ec1f30a..3e0e33c43998 100644 >> --- a/include/uapi/linux/bpf.h >> +++ b/include/uapi/linux/bpf.h >> @@ -1662,6 +1662,13 @@ union bpf_attr { >>    *     Return >>    *         A 8-byte long non-decreasing number. >>    * >> + * u64 bpf_get_socket_cookie(void *sk) >> + *     Description >> + *         Equivalent to **bpf_get_socket_cookie**\ () helper that accepts >> + *         *sk*, but gets socket from a BTF **struct sock**. >> + *     Return >> + *         A 8-byte long non-decreasing number. > > I would not mention this here since it's not fully correct and we should avoid users > taking non-decreasing granted in their progs. The only assumption you can make is > that it can be considered a unique number. See also [0] with reverse counter.. > >   [0] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=92acdc58ab11af66fcaef485433fde61b5e32fac One more thought, in case you plan to use this from sleepable context, you would need to use sock_gen_cookie() variant in the BPF helper instead.