From patchwork Thu Jan 2 22:08:19 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: 234630 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,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 CB94DC3276E for ; Thu, 2 Jan 2020 22:44:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A1E2924650 for ; Thu, 2 Jan 2020 22:44:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1578005063; bh=74fqs5Wy4RM4aHtz7JM6pMpAGJ5BmR8x9LyWRifFgEI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=OA6cIBMYNOtBZD2/JcsnullaKiqMN/hIpK6gEG0lUt4xHkplV7sCQiTsnKepInczL tH6+Ge8N7U+46rZ5i4jqeQ/loAMV7j0oVbusQBCgwNxdClOI5z0mfO/XQJ48ww/8Xp HAUUiHsv0JN4sMBs1qJeydickgJKrqgisk+q9CzY= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729899AbgABWoS (ORCPT ); Thu, 2 Jan 2020 17:44:18 -0500 Received: from mail.kernel.org ([198.145.29.99]:41086 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728800AbgABWdd (ORCPT ); Thu, 2 Jan 2020 17:33:33 -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 55FF120866; Thu, 2 Jan 2020 22:33:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1578004411; bh=74fqs5Wy4RM4aHtz7JM6pMpAGJ5BmR8x9LyWRifFgEI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=P8hiDY+ARuRk0AGwsLottYZi+dR4QqNHDzfevBD6a4yHuIF3zbqeHcGq3sweeqCCw lMCZvAgNBl+fHmuQJdRbgibYrptQNm8vRu5LrJGKG+9vcTSB5pDBV8kx9RSZFr92od x97u4nCosQ1zgxJL2Hb93Y3Etb9JGwO2GSRgDc/M= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Eric Dumazet , Michal Kubecek , Firo Yang , Jakub Kicinski Subject: [PATCH 4.9 168/171] tcp/dccp: fix possible race __inet_lookup_established() Date: Thu, 2 Jan 2020 23:08:19 +0100 Message-Id: <20200102220609.977307127@linuxfoundation.org> X-Mailer: git-send-email 2.24.1 In-Reply-To: <20200102220546.960200039@linuxfoundation.org> References: <20200102220546.960200039@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: Eric Dumazet commit 8dbd76e79a16b45b2ccb01d2f2e08dbf64e71e40 upstream. Michal Kubecek and Firo Yang did a very nice analysis of crashes happening in __inet_lookup_established(). Since a TCP socket can go from TCP_ESTABLISH to TCP_LISTEN (via a close()/socket()/listen() cycle) without a RCU grace period, I should not have changed listeners linkage in their hash table. They must use the nulls protocol (Documentation/RCU/rculist_nulls.txt), so that a lookup can detect a socket in a hash list was moved in another one. Since we added code in commit d296ba60d8e2 ("soreuseport: Resolve merge conflict for v4/v6 ordering fix"), we have to add hlist_nulls_add_tail_rcu() helper. Fixes: 3b24d854cb35 ("tcp/dccp: do not touch listener sk_refcnt under synflood") Signed-off-by: Eric Dumazet Reported-by: Michal Kubecek Reported-by: Firo Yang Reviewed-by: Michal Kubecek Link: https://lore.kernel.org/netdev/20191120083919.GH27852@unicorn.suse.cz/ Signed-off-by: Jakub Kicinski [stable-4.9: we also need to update code in __inet_lookup_listener() and inet6_lookup_listener() which has been removed in 5.0-rc1.] Signed-off-by: Michal Kubecek Signed-off-by: Greg Kroah-Hartman --- include/linux/rculist_nulls.h | 37 +++++++++++++++++++++++++++++++++++++ include/net/inet_hashtables.h | 12 +++++++++--- include/net/sock.h | 5 +++++ net/ipv4/inet_diag.c | 3 ++- net/ipv4/inet_hashtables.c | 18 +++++++++--------- net/ipv4/tcp_ipv4.c | 7 ++++--- net/ipv6/inet6_hashtables.c | 3 ++- 7 files changed, 68 insertions(+), 17 deletions(-) --- a/include/linux/rculist_nulls.h +++ b/include/linux/rculist_nulls.h @@ -100,6 +100,43 @@ static inline void hlist_nulls_add_head_ } /** + * hlist_nulls_add_tail_rcu + * @n: the element to add to the hash list. + * @h: the list to add to. + * + * Description: + * Adds the specified element to the specified hlist_nulls, + * while permitting racing traversals. + * + * The caller must take whatever precautions are necessary + * (such as holding appropriate locks) to avoid racing + * with another list-mutation primitive, such as hlist_nulls_add_head_rcu() + * or hlist_nulls_del_rcu(), running on this same list. + * However, it is perfectly legal to run concurrently with + * the _rcu list-traversal primitives, such as + * hlist_nulls_for_each_entry_rcu(), used to prevent memory-consistency + * problems on Alpha CPUs. Regardless of the type of CPU, the + * list-traversal primitive must be guarded by rcu_read_lock(). + */ +static inline void hlist_nulls_add_tail_rcu(struct hlist_nulls_node *n, + struct hlist_nulls_head *h) +{ + struct hlist_nulls_node *i, *last = NULL; + + /* Note: write side code, so rcu accessors are not needed. */ + for (i = h->first; !is_a_nulls(i); i = i->next) + last = i; + + if (last) { + n->next = last->next; + n->pprev = &last->next; + rcu_assign_pointer(hlist_next_rcu(last), n); + } else { + hlist_nulls_add_head_rcu(n, h); + } +} + +/** * hlist_nulls_for_each_entry_rcu - iterate over rcu list of given type * @tpos: the type * to use as a loop cursor. * @pos: the &struct hlist_nulls_node to use as a loop cursor. --- a/include/net/inet_hashtables.h +++ b/include/net/inet_hashtables.h @@ -98,12 +98,18 @@ struct inet_bind_hashbucket { struct hlist_head chain; }; -/* - * Sockets can be hashed in established or listening table +/* Sockets can be hashed in established or listening table. + * We must use different 'nulls' end-of-chain value for all hash buckets : + * A socket might transition from ESTABLISH to LISTEN state without + * RCU grace period. A lookup in ehash table needs to handle this case. */ +#define LISTENING_NULLS_BASE (1U << 29) struct inet_listen_hashbucket { spinlock_t lock; - struct hlist_head head; + union { + struct hlist_head head; + struct hlist_nulls_head nulls_head; + }; }; /* This is for listening sockets, thus all sockets which possess wildcards. */ --- a/include/net/sock.h +++ b/include/net/sock.h @@ -661,6 +661,11 @@ static inline void __sk_nulls_add_node_r hlist_nulls_add_head_rcu(&sk->sk_nulls_node, list); } +static inline void __sk_nulls_add_node_tail_rcu(struct sock *sk, struct hlist_nulls_head *list) +{ + hlist_nulls_add_tail_rcu(&sk->sk_nulls_node, list); +} + static inline void sk_nulls_add_node_rcu(struct sock *sk, struct hlist_nulls_head *list) { sock_hold(sk); --- a/net/ipv4/inet_diag.c +++ b/net/ipv4/inet_diag.c @@ -868,12 +868,13 @@ void inet_diag_dump_icsk(struct inet_has for (i = s_i; i < INET_LHTABLE_SIZE; i++) { struct inet_listen_hashbucket *ilb; + struct hlist_nulls_node *node; struct sock *sk; num = 0; ilb = &hashinfo->listening_hash[i]; spin_lock_bh(&ilb->lock); - sk_for_each(sk, &ilb->head) { + sk_nulls_for_each(sk, node, &ilb->nulls_head) { struct inet_sock *inet = inet_sk(sk); if (!net_eq(sock_net(sk), net)) --- a/net/ipv4/inet_hashtables.c +++ b/net/ipv4/inet_hashtables.c @@ -218,9 +218,10 @@ struct sock *__inet_lookup_listener(stru int score, hiscore = 0, matches = 0, reuseport = 0; bool exact_dif = inet_exact_dif_match(net, skb); struct sock *sk, *result = NULL; + struct hlist_nulls_node *node; u32 phash = 0; - sk_for_each_rcu(sk, &ilb->head) { + sk_nulls_for_each_rcu(sk, node, &ilb->nulls_head) { score = compute_score(sk, net, hnum, daddr, dif, exact_dif); if (score > hiscore) { reuseport = sk->sk_reuseport; @@ -441,10 +442,11 @@ static int inet_reuseport_add_sock(struc bool match_wildcard)) { struct inet_bind_bucket *tb = inet_csk(sk)->icsk_bind_hash; + const struct hlist_nulls_node *node; struct sock *sk2; kuid_t uid = sock_i_uid(sk); - sk_for_each_rcu(sk2, &ilb->head) { + sk_nulls_for_each_rcu(sk2, node, &ilb->nulls_head) { if (sk2 != sk && sk2->sk_family == sk->sk_family && ipv6_only_sock(sk2) == ipv6_only_sock(sk) && @@ -482,9 +484,9 @@ int __inet_hash(struct sock *sk, struct } if (IS_ENABLED(CONFIG_IPV6) && sk->sk_reuseport && sk->sk_family == AF_INET6) - hlist_add_tail_rcu(&sk->sk_node, &ilb->head); + __sk_nulls_add_node_tail_rcu(sk, &ilb->nulls_head); else - hlist_add_head_rcu(&sk->sk_node, &ilb->head); + __sk_nulls_add_node_rcu(sk, &ilb->nulls_head); sock_set_flag(sk, SOCK_RCU_FREE); sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1); unlock: @@ -527,10 +529,7 @@ void inet_unhash(struct sock *sk) spin_lock_bh(lock); if (rcu_access_pointer(sk->sk_reuseport_cb)) reuseport_detach_sock(sk); - if (listener) - done = __sk_del_node_init(sk); - else - done = __sk_nulls_del_node_init_rcu(sk); + done = __sk_nulls_del_node_init_rcu(sk); if (done) sock_prot_inuse_add(sock_net(sk), sk->sk_prot, -1); spin_unlock_bh(lock); @@ -666,7 +665,8 @@ void inet_hashinfo_init(struct inet_hash for (i = 0; i < INET_LHTABLE_SIZE; i++) { spin_lock_init(&h->listening_hash[i].lock); - INIT_HLIST_HEAD(&h->listening_hash[i].head); + INIT_HLIST_NULLS_HEAD(&h->listening_hash[i].nulls_head, + i + LISTENING_NULLS_BASE); } } EXPORT_SYMBOL_GPL(inet_hashinfo_init); --- a/net/ipv4/tcp_ipv4.c +++ b/net/ipv4/tcp_ipv4.c @@ -1917,13 +1917,14 @@ static void *listening_get_next(struct s struct tcp_iter_state *st = seq->private; struct net *net = seq_file_net(seq); struct inet_listen_hashbucket *ilb; + struct hlist_nulls_node *node; struct sock *sk = cur; if (!sk) { get_head: ilb = &tcp_hashinfo.listening_hash[st->bucket]; spin_lock_bh(&ilb->lock); - sk = sk_head(&ilb->head); + sk = sk_nulls_head(&ilb->nulls_head); st->offset = 0; goto get_sk; } @@ -1931,9 +1932,9 @@ get_head: ++st->num; ++st->offset; - sk = sk_next(sk); + sk = sk_nulls_next(sk); get_sk: - sk_for_each_from(sk) { + sk_nulls_for_each_from(sk, node) { if (!net_eq(sock_net(sk), net)) continue; if (sk->sk_family == st->family) --- a/net/ipv6/inet6_hashtables.c +++ b/net/ipv6/inet6_hashtables.c @@ -133,9 +133,10 @@ struct sock *inet6_lookup_listener(struc int score, hiscore = 0, matches = 0, reuseport = 0; bool exact_dif = inet6_exact_dif_match(net, skb); struct sock *sk, *result = NULL; + struct hlist_nulls_node *node; u32 phash = 0; - sk_for_each(sk, &ilb->head) { + sk_nulls_for_each(sk, node, &ilb->nulls_head) { score = compute_score(sk, net, hnum, daddr, dif, exact_dif); if (score > hiscore) { reuseport = sk->sk_reuseport;