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netfilter: nf_conntrack_irc: Fix forged IP logic

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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: 869f37d8e4 ("[NETFILTER]: nf_conntrack/nf_nat: add IRC helper port")
Signed-off-by: David Leadbeater <dgl@dgl.cx>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
This commit is contained in:
David Leadbeater 2022-08-26 14:56:58 +10:00 committed by Pablo Neira Ayuso
parent 77972a36ec
commit 0efe125cfb
1 changed files with 3 additions and 2 deletions
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5
net/netfilter/nf_conntrack_irc.c
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@ -194,8 +194,9 @@ 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);