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=-7.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,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 9AE1FC433B4 for ; Wed, 12 May 2021 14:15:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 66E526127A for ; Wed, 12 May 2021 14:15:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231624AbhELOQ3 (ORCPT ); Wed, 12 May 2021 10:16:29 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58860 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231559AbhELOPZ (ORCPT ); Wed, 12 May 2021 10:15:25 -0400 Received: from mail-ej1-x630.google.com (mail-ej1-x630.google.com [IPv6:2a00:1450:4864:20::630]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9FA27C06138E for ; Wed, 12 May 2021 07:14:14 -0700 (PDT) Received: by mail-ej1-x630.google.com with SMTP id t4so35290545ejo.0 for ; Wed, 12 May 2021 07:14:14 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=B8+dsnVGPf7hsY+HQXduPDAnUEDSpNmU6uRk4M3oaqs=; b=c917zy549w9VdfbQA59q0ZGjmJzDalQGHwIAgrrORe6nhbyLpIm0hOhpfbR2lf56Do H4sq4JTjpYYzjFFtG0b3QjgOoRtfJPFdkjU9BzxOynd4sqh1WtoW8wGUXVi+Q6m6w22i kFeD/tXYufp88NZZwKtwHsIma/lW4Qxa4v5H11u4IUqDvj7C/BJPM/XGh4ma0/LydrAn utQySur7OvheW+UY9CJyqdC8EuH9SEGAQfSNUx682LoK/ZuEvSs5agLzdXj+D8v3A7OW mjja+ixSxQt/u0Qwy5OKTNtrwqxTXmk9tq3TKUOb1PkTmGMm2EiTX2wT/ZqpiDoRlZNg hYAw== 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=B8+dsnVGPf7hsY+HQXduPDAnUEDSpNmU6uRk4M3oaqs=; b=Kq7cLn7zcO4sxHV95THZhK7JkNAvrFb5lDGKPuOFXktuFo3U94vodr3RPp/VpRi+M8 qJDiNKD7Gly8B/gBia7iEcCiIH9B+sbZyUeWPcGdVW2Zx+n9JwqwUZ5nomhkmM7KWISG kz9bImA5YJGyGZO1GPSlTQgXZynETXUjqkPor10Mfr4wsqvGIHrlOU4MWLwbQ+SHAGs/ 8+shScMEpKYpVhZkn28LkDNW+Mflx4XKWYQZF3LVEoltxh9bamDxIm/XBOjSxDxBs3Vi P0mfE/N9SHHV7v43AoK/MHbjd6H+UoJZrmrSzX/ReGO6ctnfa81Kj7Kx5dODjqlHNYci Eb9A== X-Gm-Message-State: AOAM53129MQnLHSkHaKKz4fc4k0kPB+9hlTDCIg5EitksbiDdRYkLtMt /kMbQOWifCr+Z+niV5S/RVqR9Mhu+yBkFg== X-Google-Smtp-Source: ABdhPJw8SlktX8dsixbWlXO7Non9hffmxokViC/0m0wWbQfshEDSr0xDEK+UxgmssiFbswmzvjm82Q== X-Received: by 2002:a17:906:68c:: with SMTP id u12mr774733ejb.470.1620828852912; Wed, 12 May 2021 07:14:12 -0700 (PDT) Received: from mail-wm1-f50.google.com (mail-wm1-f50.google.com. [209.85.128.50]) by smtp.gmail.com with ESMTPSA id h11sm17812370eds.15.2021.05.12.07.14.11 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 12 May 2021 07:14:11 -0700 (PDT) Received: by mail-wm1-f50.google.com with SMTP id 4-20020a05600c26c4b0290146e1feccd8so3129543wmv.1 for ; Wed, 12 May 2021 07:14:11 -0700 (PDT) X-Received: by 2002:a1c:ba05:: with SMTP id k5mr7661497wmf.169.1620828850704; Wed, 12 May 2021 07:14:10 -0700 (PDT) MIME-Version: 1.0 References: <1620714998-120657-1-git-send-email-dseok.yi@samsung.com> <1620804453-57566-1-git-send-email-dseok.yi@samsung.com> In-Reply-To: <1620804453-57566-1-git-send-email-dseok.yi@samsung.com> From: Willem de Bruijn Date: Wed, 12 May 2021 10:13:32 -0400 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH bpf-next v3] bpf: check for BPF_F_ADJ_ROOM_FIXED_GSO when bpf_skb_change_proto To: Dongseok Yi Cc: Willem de Bruijn , Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Martin KaFai Lau , Song Liu , Yonghong Song , John Fastabend , KP Singh , "David S. Miller" , Jakub Kicinski , Network Development , bpf , linux-kernel Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, May 12, 2021 at 3:41 AM Dongseok Yi wrote: > > In the forwarding path GRO -> BPF 6 to 4 -> GSO for TCP traffic, the > coalesced packet payload can be > MSS, but < MSS + 20. > bpf_skb_proto_6_to_4 will upgrade the MSS and it can be > the payload > length. After then tcp_gso_segment checks for the payload length if it > is <= MSS. The condition is causing the packet to be dropped. > > tcp_gso_segment(): > [...] > mss = skb_shinfo(skb)->gso_size; > if (unlikely(skb->len <= mss)) > goto out; > [...] > > Allow to upgrade/downgrade MSS only when BPF_F_ADJ_ROOM_FIXED_GSO is > not set. > > Signed-off-by: Dongseok Yi Acked-by: Willem de Bruijn