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=-3.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS 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 BA2D2C71122 for ; Sun, 14 Oct 2018 15:47:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8B7B820645 for ; Sun, 14 Oct 2018 15:47:05 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8B7B820645 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=decadent.org.uk Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729632AbeJNX21 (ORCPT ); Sun, 14 Oct 2018 19:28:27 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:37253 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728125AbeJNX20 (ORCPT ); Sun, 14 Oct 2018 19:28:26 -0400 Received: from [2a02:8011:400e:2:cbab:f00:c93f:614] (helo=deadeye) by shadbolt.decadent.org.uk with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.84_2) (envelope-from ) id 1gBiM3-0004co-66; Sun, 14 Oct 2018 16:30:55 +0100 Received: from ben by deadeye with local (Exim 4.91) (envelope-from ) id 1gBiLS-0000KU-Ar; Sun, 14 Oct 2018 16:30:18 +0100 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "David S. Miller" , "Guillaume Nault" Date: Sun, 14 Oct 2018 16:25:41 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.16 139/366] l2tp: fix race in duplicate tunnel detection In-Reply-To: X-SA-Exim-Connect-IP: 2a02:8011:400e:2:cbab:f00:c93f:614 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.60-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Guillaume Nault commit f6cd651b056ffd3b4e8496afd44d4ed44bf69136 upstream. We can't use l2tp_tunnel_find() to prevent l2tp_nl_cmd_tunnel_create() from creating a duplicate tunnel. A tunnel can be concurrently registered after l2tp_tunnel_find() returns. Therefore, searching for duplicates must be done at registration time. Finally, remove l2tp_tunnel_find() entirely as it isn't use anywhere anymore. Fixes: 309795f4bec2 ("l2tp: Add netlink control API for L2TP") Signed-off-by: Guillaume Nault Signed-off-by: David S. Miller [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings --- net/l2tp/l2tp_core.c | 35 ++++++++++++++--------------------- net/l2tp/l2tp_core.h | 1 - net/l2tp/l2tp_netlink.c | 6 ------ 3 files changed, 14 insertions(+), 28 deletions(-) --- a/net/l2tp/l2tp_core.c +++ b/net/l2tp/l2tp_core.c @@ -395,26 +395,6 @@ err_tlock: } EXPORT_SYMBOL_GPL(l2tp_session_register); -/* Lookup a tunnel by id - */ -struct l2tp_tunnel *l2tp_tunnel_find(struct net *net, u32 tunnel_id) -{ - struct l2tp_tunnel *tunnel; - struct l2tp_net *pn = l2tp_pernet(net); - - rcu_read_lock_bh(); - list_for_each_entry_rcu(tunnel, &pn->l2tp_tunnel_list, list) { - if (tunnel->tunnel_id == tunnel_id) { - rcu_read_unlock_bh(); - return tunnel; - } - } - rcu_read_unlock_bh(); - - return NULL; -} -EXPORT_SYMBOL_GPL(l2tp_tunnel_find); - struct l2tp_tunnel *l2tp_tunnel_find_nth(struct net *net, int nth) { struct l2tp_net *pn = l2tp_pernet(net); @@ -1625,6 +1605,7 @@ static int l2tp_validate_socket(const st int l2tp_tunnel_register(struct l2tp_tunnel *tunnel, struct net *net, struct l2tp_tunnel_cfg *cfg) { + struct l2tp_tunnel *tunnel_walk; struct l2tp_net *pn; struct socket *sock; struct sock *sk; @@ -1653,7 +1634,16 @@ int l2tp_tunnel_register(struct l2tp_tun tunnel->l2tp_net = net; pn = l2tp_pernet(net); + spin_lock_bh(&pn->l2tp_tunnel_list_lock); + list_for_each_entry(tunnel_walk, &pn->l2tp_tunnel_list, list) { + if (tunnel_walk->tunnel_id == tunnel->tunnel_id) { + spin_unlock_bh(&pn->l2tp_tunnel_list_lock); + + ret = -EEXIST; + goto err_sock; + } + } list_add_rcu(&tunnel->list, &pn->l2tp_tunnel_list); spin_unlock_bh(&pn->l2tp_tunnel_list_lock); @@ -1683,7 +1673,10 @@ int l2tp_tunnel_register(struct l2tp_tun return 0; err_sock: - sockfd_put(sock); + if (tunnel->fd < 0) + sock_release(sock); + else + sockfd_put(sock); err: return ret; } --- a/net/l2tp/l2tp_core.h +++ b/net/l2tp/l2tp_core.h @@ -240,7 +240,6 @@ struct l2tp_session *l2tp_session_get_nt struct l2tp_session *l2tp_session_get_by_ifname(const struct net *net, const char *ifname, bool do_ref); -struct l2tp_tunnel *l2tp_tunnel_find(struct net *net, u32 tunnel_id); struct l2tp_tunnel *l2tp_tunnel_find_nth(struct net *net, int nth); int l2tp_tunnel_create(struct net *net, int fd, int version, u32 tunnel_id, --- a/net/l2tp/l2tp_netlink.c +++ b/net/l2tp/l2tp_netlink.c @@ -177,12 +177,6 @@ static int l2tp_nl_cmd_tunnel_create(str if (info->attrs[L2TP_ATTR_DEBUG]) cfg.debug = nla_get_u32(info->attrs[L2TP_ATTR_DEBUG]); - tunnel = l2tp_tunnel_find(net, tunnel_id); - if (tunnel != NULL) { - ret = -EEXIST; - goto out; - } - ret = -EINVAL; switch (cfg.encap) { case L2TP_ENCAPTYPE_UDP: