From patchwork Mon Mar 28 17:57:54 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Pablo Neira Ayuso X-Patchwork-Id: 602554 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 3qYhW03vvmz9s3T for ; Tue, 29 Mar 2016 04:59:24 +1100 (AEDT) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755295AbcC1R7K (ORCPT ); Mon, 28 Mar 2016 13:59:10 -0400 Received: from mail.us.es ([193.147.175.20]:50832 "EHLO mail.us.es" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751281AbcC1R6L (ORCPT ); Mon, 28 Mar 2016 13:58:11 -0400 Received: from antivirus1-rhel7.int (unknown [192.168.2.11]) by mail.us.es (Postfix) with ESMTP id D2C81E839E for ; Mon, 28 Mar 2016 19:58:09 +0200 (CEST) Received: from antivirus1-rhel7.int (localhost [127.0.0.1]) by antivirus1-rhel7.int (Postfix) with ESMTP id 8B481DA38F for ; Mon, 28 Mar 2016 19:58:10 +0200 (CEST) Received: by antivirus1-rhel7.int (Postfix, from userid 99) id 80A3ADA38B; Mon, 28 Mar 2016 19:58:10 +0200 (CEST) X-Spam-Checker-Version: SpamAssassin 3.4.1 (2015-04-28) on antivirus1-rhel7.int X-Spam-Level: X-Spam-Status: No, score=-103.2 required=7.5 tests=BAYES_50,SMTPAUTH_US, USER_IN_WHITELIST autolearn=disabled version=3.4.1 Received: from antivirus1-rhel7.int (localhost [127.0.0.1]) by antivirus1-rhel7.int (Postfix) with ESMTP id 4DB8CDA38A for ; Mon, 28 Mar 2016 19:58:08 +0200 (CEST) Received: from 192.168.1.13 (192.168.1.13) by antivirus1-rhel7.int (F-Secure/fsigk_smtp/522/antivirus1-rhel7.int); Mon, 28 Mar 2016 19:58:08 +0200 (CEST) X-Virus-Status: clean(F-Secure/fsigk_smtp/522/antivirus1-rhel7.int) Received: (qmail 29470 invoked from network); 28 Mar 2016 19:58:07 +0200 Received: from 77.166.216.87.static.jazztel.es (HELO salvia.here) (pneira@us.es@87.216.166.77) by mail.us.es with SMTP; 28 Mar 2016 19:58:07 +0200 From: Pablo Neira Ayuso To: netfilter-devel@vger.kernel.org Cc: davem@davemloft.net, netdev@vger.kernel.org Subject: [PATCH 1/9] netfilter: ipset: fix race condition in ipset save, swap and delete Date: Mon, 28 Mar 2016 19:57:54 +0200 Message-Id: <1459187882-5357-2-git-send-email-pablo@netfilter.org> X-Mailer: git-send-email 2.1.4 In-Reply-To: <1459187882-5357-1-git-send-email-pablo@netfilter.org> References: <1459187882-5357-1-git-send-email-pablo@netfilter.org> X-Virus-Scanned: ClamAV using ClamSMTP Sender: netfilter-devel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netfilter-devel@vger.kernel.org From: Vishwanath Pai This fix adds a new reference counter (ref_netlink) for the struct ip_set. The other reference counter (ref) can be swapped out by ip_set_swap and we need a separate counter to keep track of references for netlink events like dump. Using the same ref counter for dump causes a race condition which can be demonstrated by the following script: ipset create hash_ip1 hash:ip family inet hashsize 1024 maxelem 500000 \ counters ipset create hash_ip2 hash:ip family inet hashsize 300000 maxelem 500000 \ counters ipset create hash_ip3 hash:ip family inet hashsize 1024 maxelem 500000 \ counters ipset save & ipset swap hash_ip3 hash_ip2 ipset destroy hash_ip3 /* will crash the machine */ Swap will exchange the values of ref so destroy will see ref = 0 instead of ref = 1. With this fix in place swap will not succeed because ipset save still has ref_netlink on the set (ip_set_swap doesn't swap ref_netlink). Both delete and swap will error out if ref_netlink != 0 on the set. Note: The changes to *_head functions is because previously we would increment ref whenever we called these functions, we don't do that anymore. Reviewed-by: Joshua Hunt Signed-off-by: Vishwanath Pai Signed-off-by: Jozsef Kadlecsik Signed-off-by: Pablo Neira Ayuso --- include/linux/netfilter/ipset/ip_set.h | 4 ++++ net/netfilter/ipset/ip_set_bitmap_gen.h | 2 +- net/netfilter/ipset/ip_set_core.c | 33 ++++++++++++++++++++++++++++----- net/netfilter/ipset/ip_set_hash_gen.h | 2 +- net/netfilter/ipset/ip_set_list_set.c | 2 +- 5 files changed, 35 insertions(+), 8 deletions(-) diff --git a/include/linux/netfilter/ipset/ip_set.h b/include/linux/netfilter/ipset/ip_set.h index 0e1f433..f48b8a6 100644 --- a/include/linux/netfilter/ipset/ip_set.h +++ b/include/linux/netfilter/ipset/ip_set.h @@ -234,6 +234,10 @@ struct ip_set { spinlock_t lock; /* References to the set */ u32 ref; + /* References to the set for netlink events like dump, + * ref can be swapped out by ip_set_swap + */ + u32 ref_netlink; /* The core set type */ struct ip_set_type *type; /* The type variant doing the real job */ diff --git a/net/netfilter/ipset/ip_set_bitmap_gen.h b/net/netfilter/ipset/ip_set_bitmap_gen.h index b0bc475..2e8e7e5 100644 --- a/net/netfilter/ipset/ip_set_bitmap_gen.h +++ b/net/netfilter/ipset/ip_set_bitmap_gen.h @@ -95,7 +95,7 @@ mtype_head(struct ip_set *set, struct sk_buff *skb) if (!nested) goto nla_put_failure; if (mtype_do_head(skb, map) || - nla_put_net32(skb, IPSET_ATTR_REFERENCES, htonl(set->ref - 1)) || + nla_put_net32(skb, IPSET_ATTR_REFERENCES, htonl(set->ref)) || nla_put_net32(skb, IPSET_ATTR_MEMSIZE, htonl(memsize))) goto nla_put_failure; if (unlikely(ip_set_put_flags(skb, set))) diff --git a/net/netfilter/ipset/ip_set_core.c b/net/netfilter/ipset/ip_set_core.c index 7e6568c..a748b0c 100644 --- a/net/netfilter/ipset/ip_set_core.c +++ b/net/netfilter/ipset/ip_set_core.c @@ -497,6 +497,26 @@ __ip_set_put(struct ip_set *set) write_unlock_bh(&ip_set_ref_lock); } +/* set->ref can be swapped out by ip_set_swap, netlink events (like dump) need + * a separate reference counter + */ +static inline void +__ip_set_get_netlink(struct ip_set *set) +{ + write_lock_bh(&ip_set_ref_lock); + set->ref_netlink++; + write_unlock_bh(&ip_set_ref_lock); +} + +static inline void +__ip_set_put_netlink(struct ip_set *set) +{ + write_lock_bh(&ip_set_ref_lock); + BUG_ON(set->ref_netlink == 0); + set->ref_netlink--; + write_unlock_bh(&ip_set_ref_lock); +} + /* Add, del and test set entries from kernel. * * The set behind the index must exist and must be referenced @@ -1002,7 +1022,7 @@ static int ip_set_destroy(struct net *net, struct sock *ctnl, if (!attr[IPSET_ATTR_SETNAME]) { for (i = 0; i < inst->ip_set_max; i++) { s = ip_set(inst, i); - if (s && s->ref) { + if (s && (s->ref || s->ref_netlink)) { ret = -IPSET_ERR_BUSY; goto out; } @@ -1024,7 +1044,7 @@ static int ip_set_destroy(struct net *net, struct sock *ctnl, if (!s) { ret = -ENOENT; goto out; - } else if (s->ref) { + } else if (s->ref || s->ref_netlink) { ret = -IPSET_ERR_BUSY; goto out; } @@ -1171,6 +1191,9 @@ static int ip_set_swap(struct net *net, struct sock *ctnl, struct sk_buff *skb, from->family == to->family)) return -IPSET_ERR_TYPE_MISMATCH; + if (from->ref_netlink || to->ref_netlink) + return -EBUSY; + strncpy(from_name, from->name, IPSET_MAXNAMELEN); strncpy(from->name, to->name, IPSET_MAXNAMELEN); strncpy(to->name, from_name, IPSET_MAXNAMELEN); @@ -1206,7 +1229,7 @@ ip_set_dump_done(struct netlink_callback *cb) if (set->variant->uref) set->variant->uref(set, cb, false); pr_debug("release set %s\n", set->name); - __ip_set_put_byindex(inst, index); + __ip_set_put_netlink(set); } return 0; } @@ -1328,7 +1351,7 @@ dump_last: if (!cb->args[IPSET_CB_ARG0]) { /* Start listing: make sure set won't be destroyed */ pr_debug("reference set\n"); - set->ref++; + set->ref_netlink++; } write_unlock_bh(&ip_set_ref_lock); nlh = start_msg(skb, NETLINK_CB(cb->skb).portid, @@ -1396,7 +1419,7 @@ release_refcount: if (set->variant->uref) set->variant->uref(set, cb, false); pr_debug("release set %s\n", set->name); - __ip_set_put_byindex(inst, index); + __ip_set_put_netlink(set); cb->args[IPSET_CB_ARG0] = 0; } out: diff --git a/net/netfilter/ipset/ip_set_hash_gen.h b/net/netfilter/ipset/ip_set_hash_gen.h index e5336ab..d32fd6b 100644 --- a/net/netfilter/ipset/ip_set_hash_gen.h +++ b/net/netfilter/ipset/ip_set_hash_gen.h @@ -1082,7 +1082,7 @@ mtype_head(struct ip_set *set, struct sk_buff *skb) if (nla_put_u32(skb, IPSET_ATTR_MARKMASK, h->markmask)) goto nla_put_failure; #endif - if (nla_put_net32(skb, IPSET_ATTR_REFERENCES, htonl(set->ref - 1)) || + if (nla_put_net32(skb, IPSET_ATTR_REFERENCES, htonl(set->ref)) || nla_put_net32(skb, IPSET_ATTR_MEMSIZE, htonl(memsize))) goto nla_put_failure; if (unlikely(ip_set_put_flags(skb, set))) diff --git a/net/netfilter/ipset/ip_set_list_set.c b/net/netfilter/ipset/ip_set_list_set.c index 24c6c19..a2a89e4 100644 --- a/net/netfilter/ipset/ip_set_list_set.c +++ b/net/netfilter/ipset/ip_set_list_set.c @@ -458,7 +458,7 @@ list_set_head(struct ip_set *set, struct sk_buff *skb) if (!nested) goto nla_put_failure; if (nla_put_net32(skb, IPSET_ATTR_SIZE, htonl(map->size)) || - nla_put_net32(skb, IPSET_ATTR_REFERENCES, htonl(set->ref - 1)) || + nla_put_net32(skb, IPSET_ATTR_REFERENCES, htonl(set->ref)) || nla_put_net32(skb, IPSET_ATTR_MEMSIZE, htonl(sizeof(*map) + n * set->dsize))) goto nla_put_failure;