From patchwork Tue May 15 10:52:12 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Pablo Neira Ayuso X-Patchwork-Id: 913571 X-Patchwork-Delegate: pablo@netfilter.org Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=none (mailfrom) smtp.mailfrom=vger.kernel.org (client-ip=209.132.180.67; helo=vger.kernel.org; envelope-from=netfilter-devel-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=none (p=none dis=none) header.from=netfilter.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 40lZCH6YZzz9s1R for ; Tue, 15 May 2018 20:52:27 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752674AbeEOKw1 (ORCPT ); Tue, 15 May 2018 06:52:27 -0400 Received: from mail.us.es ([193.147.175.20]:44976 "EHLO mail.us.es" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752379AbeEOKwZ (ORCPT ); Tue, 15 May 2018 06:52:25 -0400 Received: from antivirus1-rhel7.int (unknown [192.168.2.11]) by mail.us.es (Postfix) with ESMTP id EC1B11EC2CE for ; Tue, 15 May 2018 12:51:27 +0200 (CEST) Received: from antivirus1-rhel7.int (localhost [127.0.0.1]) by antivirus1-rhel7.int (Postfix) with ESMTP id D6C73DA872 for ; Tue, 15 May 2018 12:51:27 +0200 (CEST) Received: by antivirus1-rhel7.int (Postfix, from userid 99) id D5801DA86F; Tue, 15 May 2018 12:51:27 +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=-108.2 required=7.5 tests=ALL_TRUSTED,BAYES_50, SMTPAUTH_US2,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 60CD2DA86F; Tue, 15 May 2018 12:51:25 +0200 (CEST) Received: from 192.168.1.97 (192.168.1.97) by antivirus1-rhel7.int (F-Secure/fsigk_smtp/550/antivirus1-rhel7.int); Tue, 15 May 2018 12:51:25 +0200 (CEST) X-Virus-Status: clean(F-Secure/fsigk_smtp/550/antivirus1-rhel7.int) Received: from salvia.here (sys.soleta.eu [212.170.55.40]) (Authenticated sender: pneira@us.es) by entrada.int (Postfix) with ESMTPA id 178C2403F022; Tue, 15 May 2018 12:51:25 +0200 (CEST) X-SMTPAUTHUS: auth mail.us.es From: Pablo Neira Ayuso To: netfilter-devel@vger.kernel.org Cc: kristian.evensen@gmail.com, havlicek@avast.com, fw@strlen.de, mkubecek@suse.cz Subject: [PATCH nf-next, v2 3/3] netfilter: nfnetlink_queue: resolve clash for unconfirmed conntracks Date: Tue, 15 May 2018 12:52:12 +0200 Message-Id: <20180515105212.2111-3-pablo@netfilter.org> X-Mailer: git-send-email 2.11.0 In-Reply-To: <20180515105212.2111-1-pablo@netfilter.org> References: <20180515105212.2111-1-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 In nfqueue, two consecutive skbuffs may race to create the conntrack entry. Hence, the one that loses the race gets dropped due to clash in the insertion into the hashes from the nf_conntrack_confirm() path. This patch adds a new nf_conntrack_update() function which searches for possible clashes and resolve them. NAT mangling for the packet losing race is corrected by using the conntrack information that won race. In order to avoid direct module dependencies with conntrack and NAT, the nf_ct_hook and nf_nat_hook structures are used for this purpose. Signed-off-by: Pablo Neira Ayuso --- v2: check for verdict == NF_ACCEPT || NF_STOP. include/linux/netfilter.h | 2 + include/net/netfilter/nf_nat_core.h | 3 ++ net/netfilter/nf_conntrack_core.c | 73 +++++++++++++++++++++++++++++++++++++ net/netfilter/nf_nat_core.c | 41 +++++++++++++-------- net/netfilter/nfnetlink_queue.c | 33 +++++++++++++++-- 5 files changed, 133 insertions(+), 19 deletions(-) diff --git a/include/linux/netfilter.h b/include/linux/netfilter.h index 3baa48a4bb90..8e264d0f6ea7 100644 --- a/include/linux/netfilter.h +++ b/include/linux/netfilter.h @@ -360,6 +360,8 @@ struct nf_conn; enum ip_conntrack_info; struct nf_ct_hook { + int (*update)(struct net *net, struct sk_buff *skb, struct nf_conn *ct, + enum ip_conntrack_info ctinfo); void (*destroy)(struct nf_conntrack *); }; extern struct nf_ct_hook __rcu *nf_ct_hook; diff --git a/include/net/netfilter/nf_nat_core.h b/include/net/netfilter/nf_nat_core.h index 25b037cfe248..0cf4dc80872f 100644 --- a/include/net/netfilter/nf_nat_core.h +++ b/include/net/netfilter/nf_nat_core.h @@ -30,6 +30,9 @@ struct nf_nat_hook { int (*parse_nat_setup)(struct nf_conn *ct, enum nf_nat_manip_type manip, const struct nlattr *attr); void (*decode_session)(struct sk_buff *skb, struct flowi *fl); + unsigned int (*manip_pkt)(struct sk_buff *skb, struct nf_conn *ct, + enum nf_nat_manip_type mtype, + enum ip_conntrack_dir dir); }; extern struct nf_nat_hook __rcu *nf_nat_hook; diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c index 8d109d750073..904aaf5826ff 100644 --- a/net/netfilter/nf_conntrack_core.c +++ b/net/netfilter/nf_conntrack_core.c @@ -1607,6 +1607,78 @@ static void nf_conntrack_attach(struct sk_buff *nskb, const struct sk_buff *skb) nf_conntrack_get(skb_nfct(nskb)); } +static int nf_conntrack_update(struct net *net, struct sk_buff *skb, + struct nf_conn *ct, + enum ip_conntrack_info ctinfo) +{ + const struct nf_conntrack_l3proto *l3proto; + const struct nf_conntrack_l4proto *l4proto; + struct nf_conntrack_tuple_hash *h; + struct nf_conntrack_tuple tuple; + struct nf_nat_hook *nat_hook; + unsigned int dataoff, status; + u16 l3num; + u8 l4num; + + l3num = nf_ct_l3num(ct); + l3proto = nf_ct_l3proto_find_get(l3num); + + if (l3proto->get_l4proto(skb, skb_network_offset(skb), &dataoff, + &l4num) <= 0) + return 0; + + l4proto = nf_ct_l4proto_find_get(l3num, l4num); + + if (!nf_ct_get_tuple(skb, skb_network_offset(skb), dataoff, l3num, + l4num, net, &tuple, l3proto, l4proto)) + return 0; + + if (ct->status & IPS_SRC_NAT) { + memcpy(tuple.src.u3.all, + ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u3.all, + sizeof(tuple.src.u3.all)); + tuple.src.u.all = + ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u.all; + } + + if (ct->status & IPS_DST_NAT) { + memcpy(tuple.dst.u3.all, + ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.u3.all, + sizeof(tuple.dst.u3.all)); + tuple.dst.u.all = + ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.u.all; + } + + h = nf_conntrack_find_get(net, &ct->zone, &tuple); + if (!h) + return 0; + + /* Store status bits of the conntrack that is clashing to re-do NAT + * mangling according to what it has been done already to this packet. + */ + status = ct->status; + + nf_ct_put(ct); + ct = nf_ct_tuplehash_to_ctrack(h); + nf_ct_set(skb, ct, ctinfo); + + nat_hook = rcu_dereference(nf_nat_hook); + if (!nat_hook) + return 0; + + if (status & IPS_SRC_NAT && + nat_hook->manip_pkt(skb, ct, NF_NAT_MANIP_SRC, + IP_CT_DIR_ORIGINAL) == NF_DROP) + return -1; + + if (status & IPS_DST_NAT && + nat_hook->manip_pkt(skb, ct, NF_NAT_MANIP_DST, + IP_CT_DIR_ORIGINAL) == NF_DROP) + return -1; + + return 0; +} + /* Bring out ya dead! */ static struct nf_conn * get_next_corpse(int (*iter)(struct nf_conn *i, void *data), @@ -2126,6 +2198,7 @@ int nf_conntrack_init_start(void) } static struct nf_ct_hook nf_conntrack_hook = { + .update = nf_conntrack_update, .destroy = destroy_conntrack, }; diff --git a/net/netfilter/nf_nat_core.c b/net/netfilter/nf_nat_core.c index ae58088d00d4..e5603143a514 100644 --- a/net/netfilter/nf_nat_core.c +++ b/net/netfilter/nf_nat_core.c @@ -475,17 +475,36 @@ nf_nat_alloc_null_binding(struct nf_conn *ct, unsigned int hooknum) } EXPORT_SYMBOL_GPL(nf_nat_alloc_null_binding); +static unsigned int nf_nat_manip_pkt(struct sk_buff *skb, struct nf_conn *ct, + enum nf_nat_manip_type mtype, + enum ip_conntrack_dir dir) +{ + const struct nf_nat_l3proto *l3proto; + const struct nf_nat_l4proto *l4proto; + struct nf_conntrack_tuple target; + + /* We are aiming to look like inverse of other direction. */ + nf_ct_invert_tuplepr(&target, &ct->tuplehash[!dir].tuple); + + l3proto = __nf_nat_l3proto_find(target.src.l3num); + l4proto = __nf_nat_l4proto_find(target.src.l3num, + target.dst.protonum); + if (!l3proto->manip_pkt(skb, 0, l4proto, &target, mtype)) + return NF_DROP; + + return NF_ACCEPT; +} + /* Do packet manipulations according to nf_nat_setup_info. */ unsigned int nf_nat_packet(struct nf_conn *ct, enum ip_conntrack_info ctinfo, unsigned int hooknum, struct sk_buff *skb) { - const struct nf_nat_l3proto *l3proto; - const struct nf_nat_l4proto *l4proto; + enum nf_nat_manip_type mtype = HOOK2MANIP(hooknum); enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo); + unsigned int verdict = NF_ACCEPT; unsigned long statusbit; - enum nf_nat_manip_type mtype = HOOK2MANIP(hooknum); if (mtype == NF_NAT_MANIP_SRC) statusbit = IPS_SRC_NAT; @@ -497,19 +516,10 @@ unsigned int nf_nat_packet(struct nf_conn *ct, statusbit ^= IPS_NAT_MASK; /* Non-atomic: these bits don't change. */ - if (ct->status & statusbit) { - struct nf_conntrack_tuple target; - - /* We are aiming to look like inverse of other direction. */ - nf_ct_invert_tuplepr(&target, &ct->tuplehash[!dir].tuple); + if (ct->status & statusbit) + verdict = nf_nat_manip_pkt(skb, ct, mtype, dir); - l3proto = __nf_nat_l3proto_find(target.src.l3num); - l4proto = __nf_nat_l4proto_find(target.src.l3num, - target.dst.protonum); - if (!l3proto->manip_pkt(skb, 0, l4proto, &target, mtype)) - return NF_DROP; - } - return NF_ACCEPT; + return verdict; } EXPORT_SYMBOL_GPL(nf_nat_packet); @@ -806,6 +816,7 @@ struct nf_nat_hook nat_hook = { #ifdef CONFIG_XFRM .decode_session = __nf_nat_decode_session, #endif + .manip_pkt = nf_nat_manip_pkt, }; static int __init nf_nat_init(void) diff --git a/net/netfilter/nfnetlink_queue.c b/net/netfilter/nfnetlink_queue.c index 74a04638ef03..d9c3f5e39926 100644 --- a/net/netfilter/nfnetlink_queue.c +++ b/net/netfilter/nfnetlink_queue.c @@ -227,6 +227,30 @@ find_dequeue_entry(struct nfqnl_instance *queue, unsigned int id) return entry; } +static void nfqnl_reinject(struct nf_queue_entry *entry, unsigned int verdict) +{ + enum ip_conntrack_info ctinfo; + struct nf_ct_hook *ct_hook; + struct nf_conn *ct; + int err; + + ct = nf_ct_get(entry->skb, &ctinfo); + if (ct && !nf_ct_is_confirmed(ct) && + (verdict == NF_ACCEPT || verdict == NF_STOP)) { + rcu_read_lock(); + ct_hook = rcu_dereference(nf_ct_hook); + if (ct_hook) { + err = ct_hook->update(entry->state.net, entry->skb, + ct, ctinfo); + if (err < 0) + verdict = NF_DROP; + } + rcu_read_unlock(); + } + + nf_reinject(entry, verdict); +} + static void nfqnl_flush(struct nfqnl_instance *queue, nfqnl_cmpfn cmpfn, unsigned long data) { @@ -237,7 +261,7 @@ nfqnl_flush(struct nfqnl_instance *queue, nfqnl_cmpfn cmpfn, unsigned long data) if (!cmpfn || cmpfn(entry, data)) { list_del(&entry->list); queue->queue_total--; - nf_reinject(entry, NF_DROP); + nfqnl_reinject(entry, NF_DROP); } } spin_unlock_bh(&queue->lock); @@ -686,7 +710,7 @@ __nfqnl_enqueue_packet(struct net *net, struct nfqnl_instance *queue, err_out_unlock: spin_unlock_bh(&queue->lock); if (failopen) - nf_reinject(entry, NF_ACCEPT); + nfqnl_reinject(entry, NF_ACCEPT); err_out: return err; } @@ -1085,7 +1109,8 @@ static int nfqnl_recv_verdict_batch(struct net *net, struct sock *ctnl, list_for_each_entry_safe(entry, tmp, &batch_list, list) { if (nfqa[NFQA_MARK]) entry->skb->mark = ntohl(nla_get_be32(nfqa[NFQA_MARK])); - nf_reinject(entry, verdict); + + nfqnl_reinject(entry, verdict); } return 0; } @@ -1208,7 +1233,7 @@ static int nfqnl_recv_verdict(struct net *net, struct sock *ctnl, if (nfqa[NFQA_MARK]) entry->skb->mark = ntohl(nla_get_be32(nfqa[NFQA_MARK])); - nf_reinject(entry, verdict); + nfqnl_reinject(entry, verdict); return 0; }