Merge: netfilter: stable backport for 10.1 phase 2

MR: https://gitlab.com/redhat/centos-stream/src/kernel/centos-stream-10/-/merge_requests/1096

JIRA: https://issues.redhat.com/browse/RHEL-96603

 * 932b32f netfilter: socket: Lookup orig tuple for IPv6 SNAT
 * aa04c6f netfilter: bridge: Move specific fragmented packet to slow_path instead of dropping it

Signed-off-by: CKI Backport Bot <cki-ci-bot+cki-gitlab-backport-bot@redhat.com>

---

<small>Created 2025-06-24 09:36 UTC by backporter - [KWF FAQ](https://red.ht/kernel_workflow_doc) - [Slack #team-kernel-workflow](https://redhat-internal.slack.com/archives/C04LRUPMJQ5) - [Source](https://gitlab.com/cki-project/kernel-workflow/-/blob/main/webhook/utils/backporter.py) - [Documentation](https://gitlab.com/cki-project/kernel-workflow/-/blob/main/docs/README.backporter.md) - [Report an issue](https://issues.redhat.com/secure/CreateIssueDetails!init.jspa?pid=12334433&issuetype=1&priority=4&summary=backporter+webhook+issue&components=kernel-workflow+/+backporter)</small>

Approved-by: Xin Long <lxin@redhat.com>
Approved-by: Phil Sutter <psutter@redhat.com>

Merged-by: Julio Faracco <jfaracco@redhat.com>

Author: jcfaracco

net/bridge/netfilter/nf_conntrack_bridge.c

@@ -60,19 +60,19 @@ static int nf_br_ip_fragment(struct net *net, struct sock *sk,
 		struct ip_fraglist_iter iter;
 		struct sk_buff *frag;
 
-		if (first_len - hlen > mtu ||
-		    skb_headroom(skb) < ll_rs)
+		if (first_len - hlen > mtu)
 			goto blackhole;
 
-		if (skb_cloned(skb))
+		if (skb_cloned(skb) ||
+		    skb_headroom(skb) < ll_rs)
 			goto slow_path;
 
 		skb_walk_frags(skb, frag) {
-			if (frag->len > mtu ||
-			    skb_headroom(frag) < hlen + ll_rs)
+			if (frag->len > mtu)
 				goto blackhole;
 
-			if (skb_shared(frag))
+			if (skb_shared(frag) ||
+			    skb_headroom(frag) < hlen + ll_rs)
 				goto slow_path;
 		}
 

net/ipv6/netfilter.c

@@ -164,20 +164,20 @@ int br_ip6_fragment(struct net *net, struct sock *sk, struct sk_buff *skb,
 		struct ip6_fraglist_iter iter;
 		struct sk_buff *frag2;
 
-		if (first_len - hlen > mtu ||
-		    skb_headroom(skb) < (hroom + sizeof(struct frag_hdr)))
+		if (first_len - hlen > mtu)
 			goto blackhole;
 
-		if (skb_cloned(skb))
+		if (skb_cloned(skb) ||
+		    skb_headroom(skb) < (hroom + sizeof(struct frag_hdr)))
 			goto slow_path;
 
 		skb_walk_frags(skb, frag2) {
-			if (frag2->len > mtu ||
-			    skb_headroom(frag2) < (hlen + hroom + sizeof(struct frag_hdr)))
+			if (frag2->len > mtu)
 				goto blackhole;
 
 			/* Partially cloned skb? */
-			if (skb_shared(frag2))
+			if (skb_shared(frag2) ||
+			    skb_headroom(frag2) < (hlen + hroom + sizeof(struct frag_hdr)))
 				goto slow_path;
 		}
 

net/ipv6/netfilter/nf_socket_ipv6.c

@@ -103,6 +103,10 @@ struct sock *nf_sk_lookup_slow_v6(struct net *net, const struct sk_buff *skb,
 	struct sk_buff *data_skb = NULL;
 	int doff = 0;
 	int thoff = 0, tproto;
+#if IS_ENABLED(CONFIG_NF_CONNTRACK)
+	enum ip_conntrack_info ctinfo;
+	struct nf_conn const *ct;
+#endif
 
 	tproto = ipv6_find_hdr(skb, &thoff, -1, NULL, NULL);
 	if (tproto < 0) {
@@ -136,6 +140,25 @@ struct sock *nf_sk_lookup_slow_v6(struct net *net, const struct sk_buff *skb,
 		return NULL;
 	}
 
+#if IS_ENABLED(CONFIG_NF_CONNTRACK)
+	/* Do the lookup with the original socket address in
+	 * case this is a reply packet of an established
+	 * SNAT-ted connection.
+	 */
+	ct = nf_ct_get(skb, &ctinfo);
+	if (ct &&
+	    ((tproto != IPPROTO_ICMPV6 &&
+	      ctinfo == IP_CT_ESTABLISHED_REPLY) ||
+	     (tproto == IPPROTO_ICMPV6 &&
+	      ctinfo == IP_CT_RELATED_REPLY)) &&
+	    (ct->status & IPS_SRC_NAT_DONE)) {
+		daddr = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u3.in6;
+		dport = (tproto == IPPROTO_TCP) ?
+			ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u.tcp.port :
+			ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u.udp.port;
+	}
+#endif
+
 	return nf_socket_get_sock_v6(net, data_skb, doff, tproto, saddr, daddr,
 				     sport, dport, indev);
 }