From patchwork Tue Jan 12 17:45:00 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jesper Dangaard Brouer X-Patchwork-Id: 12014243 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=-11.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,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 E99E8C4332B for ; Tue, 12 Jan 2021 17:47:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9B4A523107 for ; Tue, 12 Jan 2021 17:47:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2391589AbhALRqu (ORCPT ); Tue, 12 Jan 2021 12:46:50 -0500 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:35080 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2391180AbhALRqt (ORCPT ); Tue, 12 Jan 2021 12:46:49 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1610473523; 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=+lqA2oW216IffgVLse7jSxzzKT75ytHb1bfBjowVRV4=; b=HMTOyvxKgugW4YV/MREuVB0QxhLgxPjDyjzCGZQ/+1eE0pS8oE2FdpJqjscIbuF8Mka6IK 1NrDZjtAMKlh8bFXSXPJtBsnahQzSQ5GTR1GicadWjRx9FnR/7sJCo1AxAqaa3nK8W6Tu/ xd8IvxExHJe1yPwTz8A9vSCA1x+vI/E= 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-433-z8adBOD_OTuye75KEXQqLg-1; Tue, 12 Jan 2021 12:45:10 -0500 X-MC-Unique: z8adBOD_OTuye75KEXQqLg-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 85F758049C4; Tue, 12 Jan 2021 17:45:06 +0000 (UTC) Received: from firesoul.localdomain (unknown [10.40.208.19]) by smtp.corp.redhat.com (Postfix) with ESMTP id B422C5C25A; Tue, 12 Jan 2021 17:45:01 +0000 (UTC) Received: from [192.168.42.3] (localhost [IPv6:::1]) by firesoul.localdomain (Postfix) with ESMTP id 8F5B532138454; Tue, 12 Jan 2021 18:45:00 +0100 (CET) Subject: [PATCH bpf-next V11 0/7] 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, colrack@gmail.com Date: Tue, 12 Jan 2021 18:45:00 +0100 Message-ID: <161047346644.4003084.2653117664787086168.stgit@firesoul> User-Agent: StGit/0.19 MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 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. V6: Use bpf_check_mtu() in selftest V7: Fix logic using tot_len and add another selftest V8: Add better selftests for BPF-helper bpf_check_mtu V9: Remove patch that use skb_set_redirected V10: Fix selftests and 'tot_len' MTU check like XDP V11: Fix nitpicks in selftests --- Jesper Dangaard Brouer (7): bpf: Remove MTU check in __bpf_skb_max_len bpf: fix bpf_fib_lookup helper MTU check for SKB ctx 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 selftests/bpf: use bpf_check_mtu in selftest test_cls_redirect bpf/selftests: tests using bpf_check_mtu BPF-helper include/linux/netdevice.h | 31 +++ include/uapi/linux/bpf.h | 78 +++++++ net/core/dev.c | 19 -- net/core/filter.c | 183 +++++++++++++++-- tools/include/uapi/linux/bpf.h | 78 +++++++ tools/testing/selftests/bpf/prog_tests/check_mtu.c | 216 ++++++++++++++++++++ tools/testing/selftests/bpf/progs/test_check_mtu.c | 198 ++++++++++++++++++ .../selftests/bpf/progs/test_cls_redirect.c | 7 + 8 files changed, 766 insertions(+), 44 deletions(-) create mode 100644 tools/testing/selftests/bpf/prog_tests/check_mtu.c create mode 100644 tools/testing/selftests/bpf/progs/test_check_mtu.c --