From patchwork Tue Apr 5 07:25:34 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 557469 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 DB4D1C41535 for ; Tue, 5 Apr 2022 09:52:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230216AbiDEJjF (ORCPT ); Tue, 5 Apr 2022 05:39:05 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58230 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S244506AbiDEJKB (ORCPT ); Tue, 5 Apr 2022 05:10:01 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4067F29CBD; Tue, 5 Apr 2022 01:59:42 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 4F60EB81A12; Tue, 5 Apr 2022 08:59:38 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id AA050C385A1; Tue, 5 Apr 2022 08:59:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1649149177; bh=60e7xbI6l1AgworDfHKiS/uO80AU3QEf7uiVgTT5KeY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=YAVCYcgXfu3JC0nTpW+d83UKmp8GFSPLPqbeiK2m2xhkJePRCk44Ya8XBBB3wuXtT 9VWhJjBBEFUjK3GQabxKqKHaMTRuisMliQtQpi4M7zNubmcMwnFVnPsS1KqALtF6dK gHLVaQDy7/NLiYrX3GfW5JmVwB8gyLGwiA457Vnk= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Guillaume Nault , David Ahern , Jakub Kicinski , Sasha Levin Subject: [PATCH 5.16 0621/1017] ipv4: Fix route lookups when handling ICMP redirects and PMTU updates Date: Tue, 5 Apr 2022 09:25:34 +0200 Message-Id: <20220405070412.716397649@linuxfoundation.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220405070354.155796697@linuxfoundation.org> References: <20220405070354.155796697@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Guillaume Nault [ Upstream commit 544b4dd568e3b09c1ab38a759d3187e7abda11a0 ] The PMTU update and ICMP redirect helper functions initialise their fl4 variable with either __build_flow_key() or build_sk_flow_key(). These initialisation functions always set ->flowi4_scope with RT_SCOPE_UNIVERSE and might set the ECN bits of ->flowi4_tos. This is not a problem when the route lookup is later done via ip_route_output_key_hash(), which properly clears the ECN bits from ->flowi4_tos and initialises ->flowi4_scope based on the RTO_ONLINK flag. However, some helpers call fib_lookup() directly, without sanitising the tos and scope fields, so the route lookup can fail and, as a result, the ICMP redirect or PMTU update aren't taken into account. Fix this by extracting the ->flowi4_tos and ->flowi4_scope sanitisation code into ip_rt_fix_tos(), then use this function in handlers that call fib_lookup() directly. Note 1: We can't sanitise ->flowi4_tos and ->flowi4_scope in a central place (like __build_flow_key() or flowi4_init_output()), because ip_route_output_key_hash() expects non-sanitised values. When called with sanitised values, it can erroneously overwrite RT_SCOPE_LINK with RT_SCOPE_UNIVERSE in ->flowi4_scope. Therefore we have to be careful to sanitise the values only for those paths that don't call ip_route_output_key_hash(). Note 2: The problem is mostly about sanitising ->flowi4_tos. Having ->flowi4_scope initialised with RT_SCOPE_UNIVERSE instead of RT_SCOPE_LINK probably wasn't really a problem: sockets with the SOCK_LOCALROUTE flag set (those that'd result in RTO_ONLINK being set) normally shouldn't receive ICMP redirects or PMTU updates. Fixes: 4895c771c7f0 ("ipv4: Add FIB nexthop exceptions.") Signed-off-by: Guillaume Nault Reviewed-by: David Ahern Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- net/ipv4/route.c | 18 ++++++++++++++---- 1 file changed, 14 insertions(+), 4 deletions(-) diff --git a/net/ipv4/route.c b/net/ipv4/route.c index 2c30c599cc16..750e229b7c49 100644 --- a/net/ipv4/route.c +++ b/net/ipv4/route.c @@ -498,6 +498,15 @@ void __ip_select_ident(struct net *net, struct iphdr *iph, int segs) } EXPORT_SYMBOL(__ip_select_ident); +static void ip_rt_fix_tos(struct flowi4 *fl4) +{ + __u8 tos = RT_FL_TOS(fl4); + + fl4->flowi4_tos = tos & IPTOS_RT_MASK; + fl4->flowi4_scope = tos & RTO_ONLINK ? + RT_SCOPE_LINK : RT_SCOPE_UNIVERSE; +} + static void __build_flow_key(const struct net *net, struct flowi4 *fl4, const struct sock *sk, const struct iphdr *iph, @@ -823,6 +832,7 @@ static void ip_do_redirect(struct dst_entry *dst, struct sock *sk, struct sk_buf rt = (struct rtable *) dst; __build_flow_key(net, &fl4, sk, iph, oif, tos, prot, mark, 0); + ip_rt_fix_tos(&fl4); __ip_do_redirect(rt, skb, &fl4, true); } @@ -1047,6 +1057,7 @@ static void ip_rt_update_pmtu(struct dst_entry *dst, struct sock *sk, struct flowi4 fl4; ip_rt_build_flow_key(&fl4, sk, skb); + ip_rt_fix_tos(&fl4); /* Don't make lookup fail for bridged encapsulations */ if (skb && netif_is_any_bridge_port(skb->dev)) @@ -1121,6 +1132,8 @@ void ipv4_sk_update_pmtu(struct sk_buff *skb, struct sock *sk, u32 mtu) goto out; new = true; + } else { + ip_rt_fix_tos(&fl4); } __ip_rt_update_pmtu((struct rtable *)xfrm_dst_path(&rt->dst), &fl4, mtu); @@ -2601,7 +2614,6 @@ static struct rtable *__mkroute_output(const struct fib_result *res, struct rtable *ip_route_output_key_hash(struct net *net, struct flowi4 *fl4, const struct sk_buff *skb) { - __u8 tos = RT_FL_TOS(fl4); struct fib_result res = { .type = RTN_UNSPEC, .fi = NULL, @@ -2611,9 +2623,7 @@ struct rtable *ip_route_output_key_hash(struct net *net, struct flowi4 *fl4, struct rtable *rth; fl4->flowi4_iif = LOOPBACK_IFINDEX; - fl4->flowi4_tos = tos & IPTOS_RT_MASK; - fl4->flowi4_scope = ((tos & RTO_ONLINK) ? - RT_SCOPE_LINK : RT_SCOPE_UNIVERSE); + ip_rt_fix_tos(fl4); rcu_read_lock(); rth = ip_route_output_key_hash_rcu(net, fl4, &res, skb);