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=-6.8 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=ham 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 ECFD2C432C0 for ; Wed, 27 Nov 2019 20:44:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id BFAB5217C3 for ; Wed, 27 Nov 2019 20:44:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1574887469; bh=qgj2vyTA3YFVevW3R4p4edeEoRJfzSV9gm9IqOFXZLM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=N7cfraxaPYO9CUcStc8Tn19duTn0VNnjaDk2X/awLDMmI+4gqLKfoY8afiqtnCc0I b+KHeCFRo61cqqU8793bXxyT1yZ0J55RNF28oqi0bJ0OX4koa9lfnc0XhR8sBZqCfk FTPEh4LZ5F5qX1pip5eCV7+ubTm58h4smNqV8HrE= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729596AbfK0Uo2 (ORCPT ); Wed, 27 Nov 2019 15:44:28 -0500 Received: from mail.kernel.org ([198.145.29.99]:53800 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729593AbfK0Uo1 (ORCPT ); Wed, 27 Nov 2019 15:44:27 -0500 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 16D542158A; Wed, 27 Nov 2019 20:44:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1574887466; bh=qgj2vyTA3YFVevW3R4p4edeEoRJfzSV9gm9IqOFXZLM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=eF6oiRkCpnl8StmBjVNSy7/0iSTX1DRcjgc8oM6V4VERlxrg/1fLdwF7ABgPJwluA nOGXER6867HN37ITp+xhXMT51tPWCaJsOdFpOlYAGehmjCMvSxyDW+btjL0vKEbl28 LkLHF1Xxb39yn4IN0Lxr6Zc1lpm30Ud5u3kZmdqA= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Guillaume Nault , "David S. Miller" , Nicolas Schier Subject: [PATCH 4.9 123/151] l2tp: dont use l2tp_tunnel_find() in l2tp_ip and l2tp_ip6 Date: Wed, 27 Nov 2019 21:31:46 +0100 Message-Id: <20191127203045.193982777@linuxfoundation.org> X-Mailer: git-send-email 2.24.0 In-Reply-To: <20191127203000.773542911@linuxfoundation.org> References: <20191127203000.773542911@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Guillaume Nault commit 8f7dc9ae4a7aece9fbc3e6637bdfa38b36bcdf09 upstream. Using l2tp_tunnel_find() in l2tp_ip_recv() is wrong for two reasons: * It doesn't take a reference on the returned tunnel, which makes the call racy wrt. concurrent tunnel deletion. * The lookup is only based on the tunnel identifier, so it can return a tunnel that doesn't match the packet's addresses or protocol. For example, a packet sent to an L2TPv3 over IPv6 tunnel can be delivered to an L2TPv2 over UDPv4 tunnel. This is worse than a simple cross-talk: when delivering the packet to an L2TP over UDP tunnel, the corresponding socket is UDP, where ->sk_backlog_rcv() is NULL. Calling sk_receive_skb() will then crash the kernel by trying to execute this callback. And l2tp_tunnel_find() isn't even needed here. __l2tp_ip_bind_lookup() properly checks the socket binding and connection settings. It was used as a fallback mechanism for finding tunnels that didn't have their data path registered yet. But it's not limited to this case and can be used to replace l2tp_tunnel_find() in the general case. Fix l2tp_ip6 in the same way. Fixes: 0d76751fad77 ("l2tp: Add L2TPv3 IP encapsulation (no UDP) support") Fixes: a32e0eec7042 ("l2tp: introduce L2TPv3 IP encapsulation support for IPv6") Signed-off-by: Guillaume Nault Signed-off-by: David S. Miller Cc: Nicolas Schier Signed-off-by: Greg Kroah-Hartman --- net/l2tp/l2tp_ip.c | 24 +++++++++--------------- net/l2tp/l2tp_ip6.c | 24 +++++++++--------------- 2 files changed, 18 insertions(+), 30 deletions(-) --- a/net/l2tp/l2tp_ip.c +++ b/net/l2tp/l2tp_ip.c @@ -116,6 +116,7 @@ static int l2tp_ip_recv(struct sk_buff * unsigned char *ptr, *optr; struct l2tp_session *session; struct l2tp_tunnel *tunnel = NULL; + struct iphdr *iph; int length; if (!pskb_may_pull(skb, 4)) @@ -174,24 +175,17 @@ pass_up: goto discard; tunnel_id = ntohl(*(__be32 *) &skb->data[4]); - tunnel = l2tp_tunnel_find(net, tunnel_id); - if (tunnel) { - sk = tunnel->sock; - sock_hold(sk); - } else { - struct iphdr *iph = (struct iphdr *) skb_network_header(skb); - - read_lock_bh(&l2tp_ip_lock); - sk = __l2tp_ip_bind_lookup(net, iph->daddr, iph->saddr, - inet_iif(skb), tunnel_id); - if (!sk) { - read_unlock_bh(&l2tp_ip_lock); - goto discard; - } + iph = (struct iphdr *)skb_network_header(skb); - sock_hold(sk); + read_lock_bh(&l2tp_ip_lock); + sk = __l2tp_ip_bind_lookup(net, iph->daddr, iph->saddr, inet_iif(skb), + tunnel_id); + if (!sk) { read_unlock_bh(&l2tp_ip_lock); + goto discard; } + sock_hold(sk); + read_unlock_bh(&l2tp_ip_lock); if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb)) goto discard_put; --- a/net/l2tp/l2tp_ip6.c +++ b/net/l2tp/l2tp_ip6.c @@ -128,6 +128,7 @@ static int l2tp_ip6_recv(struct sk_buff unsigned char *ptr, *optr; struct l2tp_session *session; struct l2tp_tunnel *tunnel = NULL; + struct ipv6hdr *iph; int length; if (!pskb_may_pull(skb, 4)) @@ -187,24 +188,17 @@ pass_up: goto discard; tunnel_id = ntohl(*(__be32 *) &skb->data[4]); - tunnel = l2tp_tunnel_find(net, tunnel_id); - if (tunnel) { - sk = tunnel->sock; - sock_hold(sk); - } else { - struct ipv6hdr *iph = ipv6_hdr(skb); - - read_lock_bh(&l2tp_ip6_lock); - sk = __l2tp_ip6_bind_lookup(net, &iph->daddr, &iph->saddr, - inet6_iif(skb), tunnel_id); - if (!sk) { - read_unlock_bh(&l2tp_ip6_lock); - goto discard; - } + iph = ipv6_hdr(skb); - sock_hold(sk); + read_lock_bh(&l2tp_ip6_lock); + sk = __l2tp_ip6_bind_lookup(net, &iph->daddr, &iph->saddr, + inet6_iif(skb), tunnel_id); + if (!sk) { read_unlock_bh(&l2tp_ip6_lock); + goto discard; } + sock_hold(sk); + read_unlock_bh(&l2tp_ip6_lock); if (!xfrm6_policy_check(sk, XFRM_POLICY_IN, skb)) goto discard_put;