netfilter: nf_conntrack_irc: Fix forged IP logic

stable inclusion
from stable-v5.10.143
commit e12ce30fe593dd438c5b392290ad7316befc11ca
category: bugfix
bugzilla: https://gitee.com/src-openeuler/kernel/issues/I5OWZ7
CVE: CVE-2022-2663

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=e12ce30fe593dd438c5b392290ad7316befc11ca

---------------------------

[ Upstream commit 0efe125c ]

Ensure the match happens in the right direction, previously the
destination used was the server, not the NAT host, as the comment
shows the code intended.

Additionally nf_nat_irc uses port 0 as a signal and there's no valid way
it can appear in a DCC message, so consider port 0 also forged.

Fixes: 869f37d8 ("[NETFILTER]: nf_conntrack/nf_nat: add IRC helper port")
Signed-off-by: NDavid Leadbeater <dgl@dgl.cx>
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: NSasha Levin <sashal@kernel.org>
Signed-off-by: NLiu Jian <liujian56@huawei.com>
Reviewed-by: NYue Haibing <yuehaibing@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

net/netfilter/nf_conntrack_irc.c

@@ -207,8 +207,9 @@ static int help(struct sk_buff *skb, unsigned int protoff,
 
 			/* dcc_ip can be the internal OR external (NAT'ed) IP */
 			tuple = &ct->tuplehash[dir].tuple;
-			if (tuple->src.u3.ip != dcc_ip &&
-			    tuple->dst.u3.ip != dcc_ip) {
+			if ((tuple->src.u3.ip != dcc_ip &&
+			     ct->tuplehash[!dir].tuple.dst.u3.ip != dcc_ip) ||
+			    dcc_port == 0) {
 				net_warn_ratelimited("Forged DCC command from %pI4: %pI4:%u\n",
 						     &tuple->src.u3.ip,
 						     &dcc_ip, dcc_port);