From patchwork Wed Mar 9 22:20:33 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ilya Maximets X-Patchwork-Id: 12775660 X-Patchwork-Delegate: kuba@kernel.org Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 47C29C433F5 for ; Wed, 9 Mar 2022 22:20:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238590AbiCIWVo (ORCPT ); Wed, 9 Mar 2022 17:21:44 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46046 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233383AbiCIWVm (ORCPT ); Wed, 9 Mar 2022 17:21:42 -0500 Received: from relay12.mail.gandi.net (relay12.mail.gandi.net [IPv6:2001:4b98:dc4:8::232]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5E2F5119841; Wed, 9 Mar 2022 14:20:42 -0800 (PST) Received: (Authenticated sender: i.maximets@ovn.org) by mail.gandi.net (Postfix) with ESMTPSA id 4EAFC200002; Wed, 9 Mar 2022 22:20:37 +0000 (UTC) From: Ilya Maximets To: Jakub Kicinski , Roi Dayan Cc: "David S. Miller" , Pravin B Shelar , Toms Atteka , netdev@vger.kernel.org, dev@openvswitch.org, linux-kernel@vger.kernel.org, Johannes Berg , Aaron Conole , Ilya Maximets Subject: [PATCH net-next v2] net: openvswitch: fix uAPI incompatibility with existing user space Date: Wed, 9 Mar 2022 23:20:33 +0100 Message-Id: <20220309222033.3018976-1-i.maximets@ovn.org> X-Mailer: git-send-email 2.34.1 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org X-Patchwork-Delegate: kuba@kernel.org Few years ago OVS user space made a strange choice in the commit [1] to define types only valid for the user space inside the copy of a kernel uAPI header. '#ifndef __KERNEL__' and another attribute was added later. This leads to the inevitable clash between user space and kernel types when the kernel uAPI is extended. The issue was unveiled with the addition of a new type for IPv6 extension header in kernel uAPI. When kernel provides the OVS_KEY_ATTR_IPV6_EXTHDRS attribute to the older user space application, application tries to parse it as OVS_KEY_ATTR_PACKET_TYPE and discards the whole netlink message as malformed. Since OVS_KEY_ATTR_IPV6_EXTHDRS is supplied along with every IPv6 packet that goes to the user space, IPv6 support is fully broken. Fixing that by bringing these user space attributes to the kernel uAPI to avoid the clash. Strictly speaking this is not the problem of the kernel uAPI, but changing it is the only way to avoid breakage of the older user space applications at this point. These 2 types are explicitly rejected now since they should not be passed to the kernel. Additionally, OVS_KEY_ATTR_TUNNEL_INFO moved out from the '#ifdef __KERNEL__' as there is no good reason to hide it from the userspace. And it's also explicitly rejected now, because it's for in-kernel use only. Comments with warnings were added to avoid the problem coming back. (1 << type) converted to (1ULL << type) to avoid integer overflow on OVS_KEY_ATTR_IPV6_EXTHDRS, since it equals 32 now. [1] beb75a40fdc2 ("userspace: Switching of L3 packets in L2 pipeline") Fixes: 28a3f0601727 ("net: openvswitch: IPv6: Add IPv6 extension header support") Link: https://lore.kernel.org/netdev/3adf00c7-fe65-3ef4-b6d7-6d8a0cad8a5f@nvidia.com Link: https://github.com/openvswitch/ovs/commit/beb75a40fdc295bfd6521b0068b4cd12f6de507c Reported-by: Roi Dayan Signed-off-by: Ilya Maximets Acked-by: Nicolas Dichtel Acked-by: Aaron Conole --- Version 2: - (1 << type) --> (1ULL << type) to fix the integer overflow. - Tested with OVS 2.13 LTS and latest OVS 2.17 releases: * 'make check-kernel' and 'check-system-userspace' testsuites succeeded. ('make check-kernel' fails with the current net-next without the patch) * 'make check-offloads' fails HW offloading tests, but this is not a kernel's fault. OVS offloading fails to handle perfectly valid cases where kernel and user space are parsing different number of packet fields (ODP_FIT_TOO_LITTLE and ODP_FIT_TOO_MUCH cases). The problem is purely in user space and can not be fixed by kernel changes. FWIW, quick'n'dirty version of a fix for the OVS user space may look like this: https://pastebin.com/qR0ZjvQ7 include/uapi/linux/openvswitch.h | 18 ++++++++++++++---- net/openvswitch/flow_netlink.c | 13 ++++++++++--- 2 files changed, 24 insertions(+), 7 deletions(-) diff --git a/include/uapi/linux/openvswitch.h b/include/uapi/linux/openvswitch.h index 9d1710f20505..ce3e1738d427 100644 --- a/include/uapi/linux/openvswitch.h +++ b/include/uapi/linux/openvswitch.h @@ -351,11 +351,21 @@ enum ovs_key_attr { OVS_KEY_ATTR_CT_ORIG_TUPLE_IPV4, /* struct ovs_key_ct_tuple_ipv4 */ OVS_KEY_ATTR_CT_ORIG_TUPLE_IPV6, /* struct ovs_key_ct_tuple_ipv6 */ OVS_KEY_ATTR_NSH, /* Nested set of ovs_nsh_key_* */ - OVS_KEY_ATTR_IPV6_EXTHDRS, /* struct ovs_key_ipv6_exthdr */ -#ifdef __KERNEL__ - OVS_KEY_ATTR_TUNNEL_INFO, /* struct ip_tunnel_info */ -#endif + /* User space decided to squat on types 29 and 30. They are defined + * below, but should not be sent to the kernel. + * + * WARNING: No new types should be added unless they are defined + * for both kernel and user space (no 'ifdef's). It's hard + * to keep compatibility otherwise. + */ + OVS_KEY_ATTR_PACKET_TYPE, /* be32 packet type */ + OVS_KEY_ATTR_ND_EXTENSIONS, /* IPv6 Neighbor Discovery extensions */ + + OVS_KEY_ATTR_TUNNEL_INFO, /* struct ip_tunnel_info. + * For in-kernel use only. + */ + OVS_KEY_ATTR_IPV6_EXTHDRS, /* struct ovs_key_ipv6_exthdr */ __OVS_KEY_ATTR_MAX }; diff --git a/net/openvswitch/flow_netlink.c b/net/openvswitch/flow_netlink.c index 8b4124820f7d..5176f6ccac8e 100644 --- a/net/openvswitch/flow_netlink.c +++ b/net/openvswitch/flow_netlink.c @@ -346,7 +346,7 @@ size_t ovs_key_attr_size(void) /* Whenever adding new OVS_KEY_ FIELDS, we should consider * updating this function. */ - BUILD_BUG_ON(OVS_KEY_ATTR_TUNNEL_INFO != 30); + BUILD_BUG_ON(OVS_KEY_ATTR_MAX != 32); return nla_total_size(4) /* OVS_KEY_ATTR_PRIORITY */ + nla_total_size(0) /* OVS_KEY_ATTR_TUNNEL */ @@ -482,7 +482,14 @@ static int __parse_flow_nlattrs(const struct nlattr *attr, return -EINVAL; } - if (attrs & (1 << type)) { + if (type == OVS_KEY_ATTR_PACKET_TYPE || + type == OVS_KEY_ATTR_ND_EXTENSIONS || + type == OVS_KEY_ATTR_TUNNEL_INFO) { + OVS_NLERR(log, "Key type %d is not supported", type); + return -EINVAL; + } + + if (attrs & (1ULL << type)) { OVS_NLERR(log, "Duplicate key (type %d).", type); return -EINVAL; } @@ -495,7 +502,7 @@ static int __parse_flow_nlattrs(const struct nlattr *attr, } if (!nz || !is_all_zero(nla_data(nla), nla_len(nla))) { - attrs |= 1 << type; + attrs |= 1ULL << type; a[type] = nla; } }