netdev - [PATCH v15 nf-next 2/3] netfilter: bridge: Add conntrack double vlan and pppoe

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Message-ID: <20250925183043.114660-3-ericwouds@gmail.com>
Date: Thu, 25 Sep 2025 20:30:42 +0200
From: Eric Woudstra <ericwouds@...il.com>
To: Pablo Neira Ayuso <pablo@...filter.org>,
	Jozsef Kadlecsik <kadlec@...filter.org>,
	Florian Westphal <fw@...len.de>,
	"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>,
	Nikolay Aleksandrov <razor@...ckwall.org>,
	Ido Schimmel <idosch@...dia.com>
Cc: netfilter-devel@...r.kernel.org,
	netdev@...r.kernel.org,
	bridge@...ts.linux.dev,
	Eric Woudstra <ericwouds@...il.com>
Subject: [PATCH v15 nf-next 2/3] 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 | 97 ++++++++++++++++++----
 1 file changed, 80 insertions(+), 17 deletions(-)

diff --git a/net/bridge/netfilter/nf_conntrack_bridge.c b/net/bridge/netfilter/nf_conntrack_bridge.c
index 6482de4d8750..d3745af60f3a 100644
--- a/net/bridge/netfilter/nf_conntrack_bridge.c
+++ b/net/bridge/netfilter/nf_conntrack_bridge.c
@@ -237,58 +237,121 @@ static int nf_ct_br_ipv6_check(const struct sk_buff *skb)
 	return 0;
 }
 
+/**
+ * nf_ct_bridge_pre_inner - advances network_header to the header that follows
+ * the pppoe- or vlan-header.
+ */
+
+static int nf_ct_bridge_pre_inner(struct sk_buff *skb, __be16 *proto, u32 *len)
+{
+	switch (*proto) {
+	case htons(ETH_P_PPP_SES): {
+		struct ppp_hdr {
+			struct pppoe_hdr hdr;
+			__be16 proto;
+		} *ph;
+
+		if (!pskb_may_pull(skb, PPPOE_SES_HLEN))
+			return -1;
+		ph = (struct ppp_hdr *)(skb->data);
+		switch (ph->proto) {
+		case htons(PPP_IP):
+			*proto = htons(ETH_P_IP);
+			*len = ntohs(ph->hdr.length) - 2;
+			skb_set_network_header(skb, PPPOE_SES_HLEN);
+			return PPPOE_SES_HLEN;
+		case htons(PPP_IPV6):
+			*proto = htons(ETH_P_IPV6);
+			*len = ntohs(ph->hdr.length) - 2;
+			skb_set_network_header(skb, PPPOE_SES_HLEN);
+			return PPPOE_SES_HLEN;
+		}
+		break;
+	}
+	case htons(ETH_P_8021Q): {
+		struct vlan_hdr *vhdr;
+
+		if (!pskb_may_pull(skb, VLAN_HLEN))
+			return -1;
+		vhdr = (struct vlan_hdr *)(skb->data);
+		*proto = vhdr->h_vlan_encapsulated_proto;
+		skb_set_network_header(skb, VLAN_HLEN);
+		return VLAN_HLEN;
+	}
+	}
+	return 0;
+}
+
 static unsigned int nf_ct_bridge_pre(void *priv, struct sk_buff *skb,
 				     const struct nf_hook_state *state)
 {
 	struct nf_hook_state bridge_state = *state;
+	int ret = NF_ACCEPT, offset = 0;
 	enum ip_conntrack_info ctinfo;
+	u32 len, pppoe_len = 0;
 	struct nf_conn *ct;
-	u32 len;
-	int ret;
+	__be16 proto;
 
 	ct = nf_ct_get(skb, &ctinfo);
 	if ((ct && !nf_ct_is_template(ct)) ||
 	    ctinfo == IP_CT_UNTRACKED)
 		return NF_ACCEPT;
 
-	switch (skb->protocol) {
-	case htons(ETH_P_IP):
-		if (!pskb_may_pull(skb, sizeof(struct iphdr)))
+	proto = skb->protocol;
+
+	if (ct && nf_ct_zone_id(nf_ct_zone(ct), CTINFO2DIR(ctinfo)) !=
+			NF_CT_DEFAULT_ZONE_ID) {
+		offset = nf_ct_bridge_pre_inner(skb, &proto, &pppoe_len);
+		if (offset < 0)
 			return NF_ACCEPT;
+	}
+
+	switch (proto) {
+	case htons(ETH_P_IP):
+		if (!pskb_may_pull(skb, offset + sizeof(struct iphdr)))
+			goto do_not_track;
 
 		len = skb_ip_totlen(skb);
-		if (pskb_trim_rcsum(skb, len))
-			return NF_ACCEPT;
+		if (pppoe_len && pppoe_len != len)
+			goto do_not_track;
+		if (pskb_trim_rcsum(skb, offset + len))
+			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;
+		if (!pskb_may_pull(skb, offset + sizeof(struct ipv6hdr)))
+			goto do_not_track;
 
 		len = sizeof(struct ipv6hdr) + ntohs(ipv6_hdr(skb)->payload_len);
-		if (pskb_trim_rcsum(skb, len))
-			return NF_ACCEPT;
+		if (pppoe_len && pppoe_len != len)
+			goto do_not_track;
+		if (pskb_trim_rcsum(skb, offset + len))
+			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);
+
+do_not_track:
+	if (offset && ret == NF_ACCEPT)
+		skb_reset_network_header(skb);
 
-	return nf_conntrack_in(skb, &bridge_state);
+	return ret;
 }
 
 static unsigned int nf_ct_bridge_in(void *priv, struct sk_buff *skb,
-- 
2.50.0