From patchwork Fri Oct 30 16:50:47 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jesper Dangaard Brouer X-Patchwork-Id: 11870291 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=-3.9 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,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 2924EC4741F for ; Fri, 30 Oct 2020 16:51:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BF7F52075E for ; Fri, 30 Oct 2020 16:51:00 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="hp4GZ18e" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726424AbgJ3QvA (ORCPT ); Fri, 30 Oct 2020 12:51:00 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:49908 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725922AbgJ3QvA (ORCPT ); Fri, 30 Oct 2020 12:51:00 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1604076658; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=MEMmusbGX/O+e3LL3XBF0hvrxPzkfS24s7nqpxx/rko=; b=hp4GZ18euqY7eZiA1JUZGuePbRs1rEdIbNiaX2yLQ6vqONjXv43qV6BQaF+sYYXVl8TIAg zGWf9vKcdkOV+dsZ8kwJuHjd9NMDp1zYLBu3cb032z05uBCCnVhW4PRgr8AGzeRmdMLB19 n31X3u29wpBismyqllxADrKO24ChfVg= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-455-F_jV20kiNPGoO5ZLbHu54g-1; Fri, 30 Oct 2020 12:50:54 -0400 X-MC-Unique: F_jV20kiNPGoO5ZLbHu54g-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 178AD1019642; Fri, 30 Oct 2020 16:50:52 +0000 (UTC) Received: from firesoul.localdomain (unknown [10.40.208.22]) by smtp.corp.redhat.com (Postfix) with ESMTP id 570705DA2A; Fri, 30 Oct 2020 16:50:48 +0000 (UTC) Received: from [192.168.42.3] (localhost [IPv6:::1]) by firesoul.localdomain (Postfix) with ESMTP id 2A5F630736C8B; Fri, 30 Oct 2020 17:50:47 +0100 (CET) Subject: [PATCH bpf-next V5 0/5] Subj: bpf: New approach for BPF MTU handling From: Jesper Dangaard Brouer To: bpf@vger.kernel.org Cc: Jesper Dangaard Brouer , netdev@vger.kernel.org, Daniel Borkmann , Alexei Starovoitov , maze@google.com, lmb@cloudflare.com, shaun@tigera.io, Lorenzo Bianconi , marek@cloudflare.com, John Fastabend , Jakub Kicinski , eyal.birger@gmail.com Date: Fri, 30 Oct 2020 17:50:47 +0100 Message-ID: <160407661383.1525159.12855559773280533146.stgit@firesoul> User-Agent: StGit/0.19 MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org X-Patchwork-Delegate: bpf@iogearbox.net This patchset drops all the MTU checks in TC BPF-helpers that limits growing the packet size. This is done because these BPF-helpers doesn't take redirect into account, which can result in their MTU check being done against the wrong netdev. The new approach is to give BPF-programs knowledge about the MTU on a netdev (via ifindex) and fib route lookup level. Meaning some BPF-helpers are added and extended to make it possible to do MTU checks in the BPF-code. If BPF-prog doesn't comply with the MTU then the packet will eventually get dropped as some other layer. In some cases the existing kernel MTU checks will drop the packet, but there are also cases where BPF can bypass these checks. Specifically doing TC-redirect from ingress step (sch_handle_ingress) into egress code path (basically calling dev_queue_xmit()). It is left up to driver code to handle these kind of MTU violations. One advantage of this approach is that it ingress-to-egress BPF-prog can send information via packet data. With the MTU checks removed in the helpers, and also not done in skb_do_redirect() call, this allows for an ingress BPF-prog to communicate with an egress BPF-prog via packet data, as long as egress BPF-prog remove this prior to transmitting packet. This patchset is primarily focused on TC-BPF, but I've made sure that the MTU BPF-helpers also works for XDP BPF-programs. V2: Change BPF-helper API from lookup to check. V3: Drop enforcement of MTU in net-core, leave it to drivers. V4: Keep sanity limit + netdev "up" checks + rename BPF-helper. V5: Fix uninit variable + name struct output member mtu_result. --- Jesper Dangaard Brouer (5): bpf: Remove MTU check in __bpf_skb_max_len bpf: bpf_fib_lookup return MTU value as output when looked up bpf: add BPF-helper for MTU checking bpf: drop MTU check when doing TC-BPF redirect to ingress bpf: make it possible to identify BPF redirected SKBs include/linux/netdevice.h | 31 +++++++ include/uapi/linux/bpf.h | 81 +++++++++++++++++++ net/core/dev.c | 21 +---- net/core/filter.c | 168 ++++++++++++++++++++++++++++++++++++---- net/sched/Kconfig | 1 tools/include/uapi/linux/bpf.h | 81 +++++++++++++++++++ 6 files changed, 342 insertions(+), 41 deletions(-) --