netdev - [PATCH v12 nf-next 1/2] netfilter: bridge: Add conntrack double vlan and pppoe

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Message-ID: <20250617065835.23428-2-ericwouds@gmail.com>
Date: Tue, 17 Jun 2025 08:58:34 +0200
From: Eric Woudstra <ericwouds@...il.com>
To: Pablo Neira Ayuso <pablo@...filter.org>,
	Jozsef Kadlecsik <kadlec@...filter.org>,
	Nikolay Aleksandrov <razor@...ckwall.org>,
	Ido Schimmel <idosch@...dia.com>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>,
	Paolo Abeni <pabeni@...hat.com>,
	Simon Horman <horms@...nel.org>
Cc: netfilter-devel@...r.kernel.org,
	bridge@...ts.linux.dev,
	netdev@...r.kernel.org,
	Eric Woudstra <ericwouds@...il.com>
Subject: [PATCH v12 nf-next 1/2] netfilter: bridge: Add conntrack double vlan and pppoe

This adds the capability to conntrack 802.1ad, QinQ, PPPoE and PPPoE-in-Q
packets that are passing a bridge, only when a conntrack zone is set.

Signed-off-by: Eric Woudstra <ericwouds@...il.com>
---
 net/bridge/netfilter/nf_conntrack_bridge.c | 83 ++++++++++++++++++----
 1 file changed, 71 insertions(+), 12 deletions(-)

diff --git a/net/bridge/netfilter/nf_conntrack_bridge.c b/net/bridge/netfilter/nf_conntrack_bridge.c
index 6482de4d8750..6a17bd81038e 100644
--- a/net/bridge/netfilter/nf_conntrack_bridge.c
+++ b/net/bridge/netfilter/nf_conntrack_bridge.c
@@ -242,53 +242,112 @@ static unsigned int nf_ct_bridge_pre(void *priv, struct sk_buff *skb,
 {
 	struct nf_hook_state bridge_state = *state;
 	enum ip_conntrack_info ctinfo;
+	u32 len, data_len = U32_MAX;
+	int ret, offset = 0;
 	struct nf_conn *ct;
-	u32 len;
-	int ret;
+	__be16 outer_proto;
 
 	ct = nf_ct_get(skb, &ctinfo);
 	if ((ct && !nf_ct_is_template(ct)) ||
 	    ctinfo == IP_CT_UNTRACKED)
 		return NF_ACCEPT;
 
+	if (ct && nf_ct_zone_id(nf_ct_zone(ct), CTINFO2DIR(ctinfo)) !=
+			NF_CT_DEFAULT_ZONE_ID) {
+		switch (skb->protocol) {
+		case htons(ETH_P_PPP_SES): {
+			struct ppp_hdr {
+				struct pppoe_hdr hdr;
+				__be16 proto;
+			} *ph;
+
+			offset = PPPOE_SES_HLEN;
+			if (!pskb_may_pull(skb, offset))
+				return NF_ACCEPT;
+			outer_proto = skb->protocol;
+			ph = (struct ppp_hdr *)(skb->data);
+			switch (ph->proto) {
+			case htons(PPP_IP):
+				skb->protocol = htons(ETH_P_IP);
+				break;
+			case htons(PPP_IPV6):
+				skb->protocol = htons(ETH_P_IPV6);
+				break;
+			default:
+				nf_ct_set(skb, NULL, IP_CT_UNTRACKED);
+				return NF_ACCEPT;
+			}
+			data_len = ntohs(ph->hdr.length) - 2;
+			__skb_pull(skb, offset);
+			skb_reset_network_header(skb);
+			break;
+		}
+		case htons(ETH_P_8021Q): {
+			struct vlan_hdr *vhdr;
+
+			offset = VLAN_HLEN;
+			if (!pskb_may_pull(skb, offset))
+				return NF_ACCEPT;
+			outer_proto = skb->protocol;
+			vhdr = (struct vlan_hdr *)(skb->data);
+			skb->protocol = vhdr->h_vlan_encapsulated_proto;
+			data_len = U32_MAX;
+			__skb_pull(skb, offset);
+			skb_reset_network_header(skb);
+			break;
+		}
+		}
+	}
+
+	ret = NF_ACCEPT;
 	switch (skb->protocol) {
 	case htons(ETH_P_IP):
 		if (!pskb_may_pull(skb, sizeof(struct iphdr)))
-			return NF_ACCEPT;
+			goto do_not_track;
 
 		len = skb_ip_totlen(skb);
+		if (data_len < len)
+			len = data_len;
 		if (pskb_trim_rcsum(skb, len))
-			return NF_ACCEPT;
+			goto do_not_track;
 
 		if (nf_ct_br_ip_check(skb))
-			return NF_ACCEPT;
+			goto do_not_track;
 
 		bridge_state.pf = NFPROTO_IPV4;
 		ret = nf_ct_br_defrag4(skb, &bridge_state);
 		break;
 	case htons(ETH_P_IPV6):
 		if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))
-			return NF_ACCEPT;
+			goto do_not_track;
 
 		len = sizeof(struct ipv6hdr) + ntohs(ipv6_hdr(skb)->payload_len);
+		if (data_len < len)
+			len = data_len;
 		if (pskb_trim_rcsum(skb, len))
-			return NF_ACCEPT;
+			goto do_not_track;
 
 		if (nf_ct_br_ipv6_check(skb))
-			return NF_ACCEPT;
+			goto do_not_track;
 
 		bridge_state.pf = NFPROTO_IPV6;
 		ret = nf_ct_br_defrag6(skb, &bridge_state);
 		break;
 	default:
 		nf_ct_set(skb, NULL, IP_CT_UNTRACKED);
-		return NF_ACCEPT;
+		goto do_not_track;
 	}
 
-	if (ret != NF_ACCEPT)
-		return ret;
+	if (ret == NF_ACCEPT)
+		ret = nf_conntrack_in(skb, &bridge_state);
 
-	return nf_conntrack_in(skb, &bridge_state);
+do_not_track:
+	if (offset) {
+		__skb_push(skb, offset);
+		skb_reset_network_header(skb);
+		skb->protocol = outer_proto;
+	}
+	return ret;
 }
 
 static unsigned int nf_ct_bridge_in(void *priv, struct sk_buff *skb,
-- 
2.47.1