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=-16.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,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 ABBEFC43461 for ; Wed, 12 May 2021 06:56:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7381E617C9 for ; Wed, 12 May 2021 06:56:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229627AbhELG5f (ORCPT ); Wed, 12 May 2021 02:57:35 -0400 Received: from mailout1.samsung.com ([203.254.224.24]:29642 "EHLO mailout1.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229626AbhELG53 (ORCPT ); Wed, 12 May 2021 02:57:29 -0400 Received: from epcas2p2.samsung.com (unknown [182.195.41.54]) by mailout1.samsung.com (KnoxPortal) with ESMTP id 20210512065618epoutp0153d8d9d1d46612f672e9855c289dead0~_P1utn1mB2280422804epoutp01k for ; Wed, 12 May 2021 06:56:18 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 mailout1.samsung.com 20210512065618epoutp0153d8d9d1d46612f672e9855c289dead0~_P1utn1mB2280422804epoutp01k DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=samsung.com; s=mail20170921; t=1620802578; bh=7i2CDfHh137h+0Yx+khzYwntcbYdWTB26Lu9nlZudh4=; h=From:To:Cc:In-Reply-To:Subject:Date:References:From; b=Ae2NGZhkI7cQVBwRAgJl5STBwV+NQWfS5pHFmHlV8y/P/5gB9UsoXFiiz0bQX5SIF E/+Dm+/6stnKyDSNB8imPIvbj0qFdsi7Bk6iJSrrkgNDdMXpkHDHg55sSraRB1ndSO GjnGjR3LnuQtS4IdOkEs/m8KXbzN32DjJfq7QCS0= Received: from epsnrtp4.localdomain (unknown [182.195.42.165]) by epcas2p4.samsung.com (KnoxPortal) with ESMTP id 20210512065618epcas2p43982d5a56d45cc068550a73d4dfd2fd7~_P1uSMLnC2509925099epcas2p4f; Wed, 12 May 2021 06:56:18 +0000 (GMT) Received: from epsmges2p3.samsung.com (unknown [182.195.40.183]) by epsnrtp4.localdomain (Postfix) with ESMTP id 4Fg5DH4Glwz4x9QP; Wed, 12 May 2021 06:56:15 +0000 (GMT) Received: from epcas2p4.samsung.com ( [182.195.41.56]) by epsmges2p3.samsung.com (Symantec Messaging Gateway) with SMTP id 76.54.09433.F0C7B906; Wed, 12 May 2021 15:56:15 +0900 (KST) Received: from epsmtrp1.samsung.com (unknown [182.195.40.13]) by epcas2p1.samsung.com (KnoxPortal) with ESMTPA id 20210512065615epcas2p1d961fcba48fe698b44705cc599b4eb85~_P1rJWL3P2548025480epcas2p1f; Wed, 12 May 2021 06:56:15 +0000 (GMT) Received: from epsmgms1p2.samsung.com (unknown [182.195.42.42]) by epsmtrp1.samsung.com (KnoxPortal) with ESMTP id 20210512065615epsmtrp18759fa2574faf0aa6011c3431e47fa25~_P1rIchAI3249932499epsmtrp17; Wed, 12 May 2021 06:56:15 +0000 (GMT) X-AuditID: b6c32a47-f4bff700000024d9-ad-609b7c0fa027 Received: from epsmtip2.samsung.com ( [182.195.34.31]) by epsmgms1p2.samsung.com (Symantec Messaging Gateway) with SMTP id 61.74.08163.E0C7B906; Wed, 12 May 2021 15:56:14 +0900 (KST) Received: from KORDO035731 (unknown [12.36.185.47]) by epsmtip2.samsung.com (KnoxPortal) with ESMTPA id 20210512065614epsmtip25e0ca34a0b60b77c7b76f9248dd550d4~_P1q8OGKz1561715617epsmtip2I; Wed, 12 May 2021 06:56:14 +0000 (GMT) From: "Dongseok Yi" To: "'Willem de Bruijn'" Cc: "'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'" , "'LKML'" In-Reply-To: Subject: RE: [PATCH bpf v2] bpf: check BPF_F_ADJ_ROOM_FIXED_GSO when upgrading mss in 6 to 4 Date: Wed, 12 May 2021 15:56:14 +0900 Message-ID: <01f901d746fb$e683ec60$b38bc520$@samsung.com> MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Mailer: Microsoft Outlook 16.0 Thread-Index: AQGn2ZQLsozVdio9CgO6qPhknutQhgG+YoocAZxTHfABt+AtLasVriFg Content-Language: ko X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFtrPJsWRmVeSWpSXmKPExsWy7bCmhS5/zewEg+4JMhbff89mtvjy8za7 xecjx9ksFi/8xmwx53wLi0XTjhVMFi8+PGG0eL6vl8niwrY+VovLu+awWRxbIGbx8/AZZovF PzcAVSyZwejA57Fl5U0mj4nN79g9ds66y+7RdeMSs8emVZ1sHp83yQWwReXYZKQmpqQWKaTm JeenZOal2yp5B8c7x5uaGRjqGlpamCsp5CXmptoqufgE6Lpl5gBdq6RQlphTChQKSCwuVtK3 synKLy1JVcjILy6xVUotSMkpMDQs0CtOzC0uzUvXS87PtTI0MDAyBapMyMlY8eEQe8FxxYq/ 7UfYGhjXS3QxcnJICJhI7H54iKmLkYtDSGAHo8TBu/uYIZxPjBJbtn9gg3A+M0qs2fWVDabl 2Nf3UFW7GCWadk2EqnrBKDFj63d2kCo2AS2JN7PaWUFsEQErif+zT7CDFDELTGORWH5/BQtI glMgUGJax00mEFtYIE5i9/dzYCtYBFQlrp2ZB1bDK2ApsftKJyOELShxcuYTsDizgLzE9rdz mCFOUpD4+XQZ1DI3iYnHp0DViEjM7mwDO1VC4AKHxKUpR6F+cJF4sPwTE4QtLPHq+BZ2CFtK 4mV/G5DNAWTXS7R2x0D09jBKXNkHsVhCwFhi1rN2RpAaZgFNifW79CHKlSWO3IJayyfRcfgv 1BReiY42IQhTSWLil3iIGRISL05OZpnAqDQLyV+zkPw1C8n9sxBWLWBkWcUollpQnJueWmxU YIwc2ZsYwSlZy30H44y3H/QOMTJxMB5ilOBgVhLhFUuanSDEm5JYWZValB9fVJqTWnyI0RQY 0hOZpUST84FZIa8k3tDUyMzMwNLUwtTMyEJJnPdnal2CkEB6YklqdmpqQWoRTB8TB6dUA1Pt EiH27V0t9rLXjmnkBnVz+Cf2LSo22bzJ5qb+Gt4fKXwu7469a239P/9Y48QZhZLsiZb1iX9u 5ZW+5hYpdWKe1r9xcsft3Zv8n+z+8OLSe8nPF5+9WnDI/fd54adaNX8sauQNP5ncvmgXdUX2 Xp/qjhcNZa7f6pdo5O3x/C3puCx/7ZmqmFsSvW62HwVqbI7OCI0p/9H2bP6hlq+LO6L+pDaK G3qstzrzv80rKHuddmbTWgHLDVq5Isks/QVmz441zInnSf49L41lQ6/m9rKqvEuLdTvNYqK9 Coz2tE/+aSAYPz3jUNg3jfbzP68ZfKm6cW8ap9hFhleJ2XWHa0UWaAVdbufcpRT4bobvTSWW 4oxEQy3mouJEALfOm6BSBAAA X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFlrNIsWRmVeSWpSXmKPExsWy7bCSvC5fzewEgyVnrSy+/57NbPHl5212 i89HjrNZLF74jdlizvkWFoumHSuYLF58eMJo8XxfL5PFhW19rBaXd81hszi2QMzi5+EzzBaL f24Aqlgyg9GBz2PLyptMHhOb37F77Jx1l92j68YlZo9NqzrZPD5vkgtgi+KySUnNySxLLdK3 S+DKWPHhEHvBccWKv+1H2BoY10t0MXJySAiYSBz7+p65i5GLQ0hgB6PE6Y3nGbsYOYASEhK7 NrtC1AhL3G85wgpR84xR4tqn8ywgCTYBLYk3s9pZQWwRASuJ/7NPsIMUMQssYJHoeDSJHaJj CpPE/GurmECqOAUCJaZ13ASzhQViJJq6l4B1swioSlw7Mw9sKq+ApcTuK52MELagxMmZT8Di zALaEr0PWxkhbHmJ7W/nMEOcpyDx8+kyqCvcJCYenwJVLyIxu7ONeQKj8Cwko2YhGTULyahZ SFoWMLKsYpRMLSjOTc8tNiwwykst1ytOzC0uzUvXS87P3cQIjk8trR2Me1Z90DvEyMTBeIhR goNZSYRXLGl2ghBvSmJlVWpRfnxRaU5q8SFGaQ4WJXHeC10n44UE0hNLUrNTUwtSi2CyTByc Ug1M1mubn0rt8AzsfLtM0k1Ns2hVQ30Iu+8bZbaNZo/ynqX8eW0g7lR4qcb4Bgv3ukr+pudK Fvn/J//KEtvGxFEvP2H7HamZ3xNmvvWs2bkvL8T9r7KW4CsW3Qa78kO+vU8+Hr1npRjI6zRj jcqEc+m2Nqv3v1das/f+N8Wtuy/ohca+ubv9eG1u/rdilfk3pqyTuHlpqxW/pvTWk+2JBzkO NrZfPVHBdDdq4pr9KbLGic3P6r88PXra3SGSK6lt/dm5tdPFlz+fF3iUL02dYXL3vPnzQ5OU zobdt710xvr1zQddTJWz0hly5U6tt1wyRbjAvL3m3X5ejbRFUju3vXt38byH5Dv5qo/xjbEC Jtf2KrEUZyQaajEXFScCAJGP10Y+AwAA X-CMS-MailID: 20210512065615epcas2p1d961fcba48fe698b44705cc599b4eb85 X-Msg-Generator: CA Content-Type: text/plain; charset="utf-8" X-Sendblock-Type: AUTO_CONFIDENTIAL CMS-TYPE: 102P DLP-Filter: Pass X-CFilter-Loop: Reflected X-CMS-RootMailID: 20210511065056epcas2p1788505019deb274f5c57650a2f5d7ef0 References: <1619690903-1138-1-git-send-email-dseok.yi@samsung.com> <1620714998-120657-1-git-send-email-dseok.yi@samsung.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, May 11, 2021 at 01:42:46PM -0400, Willem de Bruijn wrote: > On Tue, May 11, 2021 at 2:51 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 increase 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 increase MSS when BPF_F_ADJ_ROOM_FIXED_GSO is not set. > > > > Fixes: 6578171a7ff0 (bpf: add bpf_skb_change_proto helper) > > Signed-off-by: Dongseok Yi > > > > --- > > Thanks. Note that this feature does not preclude the alternatives > discussed, of converting the packet to non-TSO (by clearing gso_size) > or optionally modifying MSS (but that should get okay from TCP > experts). > > I would target this for bpf-next and drop the Fixes. But that is > admittedly debatable. No problem. We can make a better decision under bpf-next. > > > net/core/filter.c | 13 +++++++------ > > 1 file changed, 7 insertions(+), 6 deletions(-) > > > > v2: > > per Willem de Bruijn request, > > checked the flag instead of a generic approach. > > > > diff --git a/net/core/filter.c b/net/core/filter.c > > index cae56d0..a98b28d 100644 > > --- a/net/core/filter.c > > +++ b/net/core/filter.c > > @@ -3276,7 +3276,7 @@ static int bpf_skb_proto_4_to_6(struct sk_buff *skb) > > return 0; > > } > > > > -static int bpf_skb_proto_6_to_4(struct sk_buff *skb) > > +static int bpf_skb_proto_6_to_4(struct sk_buff *skb, u64 flags) > > { > > const u32 len_diff = sizeof(struct ipv6hdr) - sizeof(struct iphdr); > > u32 off = skb_mac_header_len(skb); > > @@ -3305,7 +3305,8 @@ static int bpf_skb_proto_6_to_4(struct sk_buff *skb) > > } > > > > /* Due to IPv4 header, MSS can be upgraded. */ > > - skb_increase_gso_size(shinfo, len_diff); > > + if (!(flags & BPF_F_ADJ_ROOM_FIXED_GSO)) > > + skb_increase_gso_size(shinfo, len_diff); > > /* Header must be checked, and gso_segs recomputed. */ > > shinfo->gso_type |= SKB_GSO_DODGY; > > shinfo->gso_segs = 0; > > @@ -3317,7 +3318,7 @@ static int bpf_skb_proto_6_to_4(struct sk_buff *skb) > > return 0; > > } > > > > -static int bpf_skb_proto_xlat(struct sk_buff *skb, __be16 to_proto) > > +static int bpf_skb_proto_xlat(struct sk_buff *skb, __be16 to_proto, u64 flags) > > { > > __be16 from_proto = skb->protocol; > > > > @@ -3327,7 +3328,7 @@ static int bpf_skb_proto_xlat(struct sk_buff *skb, __be16 to_proto) > > > > if (from_proto == htons(ETH_P_IPV6) && > > to_proto == htons(ETH_P_IP)) > > - return bpf_skb_proto_6_to_4(skb); > > + return bpf_skb_proto_6_to_4(skb, flags); > > > > return -ENOTSUPP; > > } > > @@ -3337,7 +3338,7 @@ BPF_CALL_3(bpf_skb_change_proto, struct sk_buff *, skb, __be16, proto, > > { > > int ret; > > > > - if (unlikely(flags)) > > + if (unlikely(flags & ~(BPF_F_ADJ_ROOM_FIXED_GSO))) > > return -EINVAL; > > Once allowing this flag, please immediately support it for both > bpf_skb_proto_6_to_4 and bpf_skb_4_to_6. > > We cannot do that later if we ignore the second case now. I will make v3 for both 6_to_4 and 4_to_6. > > > > /* General idea is that this helper does the basic groundwork > > @@ -3357,7 +3358,7 @@ BPF_CALL_3(bpf_skb_change_proto, struct sk_buff *, skb, __be16, proto, > > * that. For offloads, we mark packet as dodgy, so that headers > > * need to be verified first. > > */ > > - ret = bpf_skb_proto_xlat(skb, proto); > > + ret = bpf_skb_proto_xlat(skb, proto, flags); > > bpf_compute_data_pointers(skb); > > return ret; > > } > > -- > > 2.7.4 > >