From patchwork Wed May 13 09:44:09 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 225922 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=-6.9 required=3.0 tests=DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED, USER_AGENT_GIT 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 C16FDC2D0F9 for ; Wed, 13 May 2020 10:04:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A084F20575 for ; Wed, 13 May 2020 10:04:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1589364243; bh=fpRgZrHwhdR7cxhBmK4qzwEzPTjHE0NoVCfgcTVfCC0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=N4Jm+Agyq4JIYEkYOHS26Qingpa5Iuv7sz3tPgvboc55HCoLd+JcF/1vh1Ho18Ikt 76OwWUJzCoJKiPSGOsZgdMB5C24Zrq1BotRXeON3xyA0tnAs8tn06EFtZpM5u737xr tGwVHFLBzpZTAZAzYKf+YvNlXRi/0M1T1FoUx2GE= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1733001AbgEMJsH (ORCPT ); Wed, 13 May 2020 05:48:07 -0400 Received: from mail.kernel.org ([198.145.29.99]:46336 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732994AbgEMJsH (ORCPT ); Wed, 13 May 2020 05:48:07 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id AFDB820740; Wed, 13 May 2020 09:48:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1589363286; bh=fpRgZrHwhdR7cxhBmK4qzwEzPTjHE0NoVCfgcTVfCC0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=OMBGOthjyI33qXODT/sN6r42CA879J84RUmabZnpKE2dlVzCxdmPBqNsMk/HgcGxD W2jVwxPuqE95q+78Oyl2VT1xHW6wdyKdgm3QMGG3c8kOJg13EENEWo+RkxtgUDP5pR VIWOWcIQAv/jN6qTmyIw5ZJXoLRXwmbjCdbdlA4Q= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Nikolay Aleksandrov , David Ahern , "David S. Miller" Subject: [PATCH 5.4 13/90] ipv6: Use global sernum for dst validation with nexthop objects Date: Wed, 13 May 2020 11:44:09 +0200 Message-Id: <20200513094410.412050680@linuxfoundation.org> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20200513094408.810028856@linuxfoundation.org> References: <20200513094408.810028856@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: David Ahern [ Upstream commit 8f34e53b60b337e559f1ea19e2780ff95ab2fa65 ] Nik reported a bug with pcpu dst cache when nexthop objects are used illustrated by the following: $ ip netns add foo $ ip -netns foo li set lo up $ ip -netns foo addr add 2001:db8:11::1/128 dev lo $ ip netns exec foo sysctl net.ipv6.conf.all.forwarding=1 $ ip li add veth1 type veth peer name veth2 $ ip li set veth1 up $ ip addr add 2001:db8:10::1/64 dev veth1 $ ip li set dev veth2 netns foo $ ip -netns foo li set veth2 up $ ip -netns foo addr add 2001:db8:10::2/64 dev veth2 $ ip -6 nexthop add id 100 via 2001:db8:10::2 dev veth1 $ ip -6 route add 2001:db8:11::1/128 nhid 100 Create a pcpu entry on cpu 0: $ taskset -a -c 0 ip -6 route get 2001:db8:11::1 Re-add the route entry: $ ip -6 ro del 2001:db8:11::1 $ ip -6 route add 2001:db8:11::1/128 nhid 100 Route get on cpu 0 returns the stale pcpu: $ taskset -a -c 0 ip -6 route get 2001:db8:11::1 RTNETLINK answers: Network is unreachable While cpu 1 works: $ taskset -a -c 1 ip -6 route get 2001:db8:11::1 2001:db8:11::1 from :: via 2001:db8:10::2 dev veth1 src 2001:db8:10::1 metric 1024 pref medium Conversion of FIB entries to work with external nexthop objects missed an important difference between IPv4 and IPv6 - how dst entries are invalidated when the FIB changes. IPv4 has a per-network namespace generation id (rt_genid) that is bumped on changes to the FIB. Checking if a dst_entry is still valid means comparing rt_genid in the rtable to the current value of rt_genid for the namespace. IPv6 also has a per network namespace counter, fib6_sernum, but the count is saved per fib6_node. With the per-node counter only dst_entries based on fib entries under the node are invalidated when changes are made to the routes - limiting the scope of invalidations. IPv6 uses a reference in the rt6_info, 'from', to track the corresponding fib entry used to create the dst_entry. When validating a dst_entry, the 'from' is used to backtrack to the fib6_node and check the sernum of it to the cookie passed to the dst_check operation. With the inline format (nexthop definition inline with the fib6_info), dst_entries cached in the fib6_nh have a 1:1 correlation between fib entries, nexthop data and dst_entries. With external nexthops, IPv6 looks more like IPv4 which means multiple fib entries across disparate fib6_nodes can all reference the same fib6_nh. That means validation of dst_entries based on external nexthops needs to use the IPv4 format - the per-network namespace counter. Add sernum to rt6_info and set it when creating a pcpu dst entry. Update rt6_get_cookie to return sernum if it is set and update dst_check for IPv6 to look for sernum set and based the check on it if so. Finally, rt6_get_pcpu_route needs to validate the cached entry before returning a pcpu entry (similar to the rt_cache_valid calls in __mkroute_input and __mkroute_output for IPv4). This problem only affects routes using the new, external nexthops. Thanks to the kbuild test robot for catching the IS_ENABLED needed around rt_genid_ipv6 before I sent this out. Fixes: 5b98324ebe29 ("ipv6: Allow routes to use nexthop objects") Reported-by: Nikolay Aleksandrov Signed-off-by: David Ahern Reviewed-by: Nikolay Aleksandrov Tested-by: Nikolay Aleksandrov Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- include/net/ip6_fib.h | 4 ++++ include/net/net_namespace.h | 7 +++++++ net/ipv6/route.c | 25 +++++++++++++++++++++++++ 3 files changed, 36 insertions(+) --- a/include/net/ip6_fib.h +++ b/include/net/ip6_fib.h @@ -177,6 +177,7 @@ struct fib6_info { struct rt6_info { struct dst_entry dst; struct fib6_info __rcu *from; + int sernum; struct rt6key rt6i_dst; struct rt6key rt6i_src; @@ -260,6 +261,9 @@ static inline u32 rt6_get_cookie(const s struct fib6_info *from; u32 cookie = 0; + if (rt->sernum) + return rt->sernum; + rcu_read_lock(); from = rcu_dereference(rt->from); --- a/include/net/net_namespace.h +++ b/include/net/net_namespace.h @@ -428,6 +428,13 @@ static inline int rt_genid_ipv4(struct n return atomic_read(&net->ipv4.rt_genid); } +#if IS_ENABLED(CONFIG_IPV6) +static inline int rt_genid_ipv6(const struct net *net) +{ + return atomic_read(&net->ipv6.fib6_sernum); +} +#endif + static inline void rt_genid_bump_ipv4(struct net *net) { atomic_inc(&net->ipv4.rt_genid); --- a/net/ipv6/route.c +++ b/net/ipv6/route.c @@ -1388,9 +1388,18 @@ static struct rt6_info *ip6_rt_pcpu_allo } ip6_rt_copy_init(pcpu_rt, res); pcpu_rt->rt6i_flags |= RTF_PCPU; + + if (f6i->nh) + pcpu_rt->sernum = rt_genid_ipv6(dev_net(dev)); + return pcpu_rt; } +static bool rt6_is_valid(const struct rt6_info *rt6) +{ + return rt6->sernum == rt_genid_ipv6(dev_net(rt6->dst.dev)); +} + /* It should be called with rcu_read_lock() acquired */ static struct rt6_info *rt6_get_pcpu_route(const struct fib6_result *res) { @@ -1398,6 +1407,19 @@ static struct rt6_info *rt6_get_pcpu_rou pcpu_rt = this_cpu_read(*res->nh->rt6i_pcpu); + if (pcpu_rt && pcpu_rt->sernum && !rt6_is_valid(pcpu_rt)) { + struct rt6_info *prev, **p; + + p = this_cpu_ptr(res->nh->rt6i_pcpu); + prev = xchg(p, NULL); + if (prev) { + dst_dev_put(&prev->dst); + dst_release(&prev->dst); + } + + pcpu_rt = NULL; + } + return pcpu_rt; } @@ -2599,6 +2621,9 @@ static struct dst_entry *ip6_dst_check(s rt = container_of(dst, struct rt6_info, dst); + if (rt->sernum) + return rt6_is_valid(rt) ? dst : NULL; + rcu_read_lock(); /* All IPV6 dsts are created with ->obsolete set to the value