Merge git://git.kernel.org/pub/scm/linux/kernel/git/netfilter/nf

Florian Westphal says:

====================
netfilter: bug fixes for net

1. Fix IP address check in irc DCC conntrack helper, this should check
   the opposite direction rather than the destination address of the
   packets' direction, from David Leadbeater.

2. bridge netfilter needs to drop dst references, from Harsh Modi.
   This was fine back in the day the code was originally written,
   but nowadays various tunnels can pre-set metadata dsts on packets.

3. Remove nf_conntrack_helper sysctl and the modparam toggle, users
   need to explicitily assign the helpers to use via nftables or
   iptables.  Conntrack helpers, by design, may be used to add dynamic
   port redirections to internal machines, so its necessary to restrict
   which hosts/peers are allowed to use them.
   It was discovered that improper checking in the irc DCC helper makes
   it possible to trigger the 'please do dynamic port forward'
   from outside by embedding a 'DCC' in a PING request; if the client
   echos that back a expectation/port forward gets added.
   The auto-assign-for-everything mechanism has been in "please don't do this"
   territory since 2012.  From Pablo.

4. Fix a memory leak in the netdev hook error unwind path, also from Pablo.

* git://git.kernel.org/pub/scm/linux/kernel/git/netfilter/nf:
  netfilter: nf_conntrack_irc: Fix forged IP logic
  netfilter: nf_tables: clean up hook list when offload flags check fails
  netfilter: br_netfilter: Drop dst references before setting.
  netfilter: remove nf_conntrack_helper sysctl and modparam toggles
====================

Link: https://lore.kernel.org/r/20220901071238.3044-1-fw@strlen.de
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

1 files changed, 3 insertions, 2 deletions

diff --git a/net/netfilter/nf_conntrack_irc.c b/net/netfilter/nf_conntrack_irc.c
index 1796c456ac98..992decbcaa5c 100644
--- a/net/netfilter/nf_conntrack_irc.c
+++ b/net/netfilter/nf_conntrack_irc.c
@@ -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);