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

This adds the capability to evaluate 802.1ad, QinQ, PPPoE and PPPoE-in-Q
packets in the bridge filter chain.

Signed-off-by: Eric Woudstra <[email protected]>
---
 include/net/netfilter/nf_tables.h | 48 +++++++++++++++++++++++++++++++
 net/netfilter/nft_chain_filter.c  | 17 +++++++++--
 2 files changed, 62 insertions(+), 3 deletions(-)

diff --git a/include/net/netfilter/nf_tables.h b/include/net/netfilter/nf_tables.h
index e2128663b160..4a55972881b1 100644
--- a/include/net/netfilter/nf_tables.h
+++ b/include/net/netfilter/nf_tables.h
@@ -10,6 +10,7 @@
 #include <linux/netfilter/nf_tables.h>
 #include <linux/u64_stats_sync.h>
 #include <linux/rhashtable.h>
+#include <linux/if_vlan.h>
 #include <net/netfilter/nf_flow_table.h>
 #include <net/netlink.h>
 #include <net/flow_offload.h>
@@ -88,6 +89,53 @@ static inline void nft_set_pktinfo_unspec(struct nft_pktinfo *pkt)
 	pkt->fragoff = 0;
 }
 
+/**
+ * nft_set_bridge_pktinfo - calls nft_set_pktinfo and advances
+ * network_header to the header that follows the pppoe- or vlan-header.
+ */
+static inline int nft_set_bridge_pktinfo(struct nft_pktinfo *pkt,
+					 struct sk_buff *skb,
+					 const struct nf_hook_state *state,
+					 __be16 *proto)
+{
+	nft_set_pktinfo(pkt, skb, state);
+
+	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);
+			skb_set_network_header(skb, PPPOE_SES_HLEN);
+			return PPPOE_SES_HLEN;
+		case htons(PPP_IPV6):
+			*proto = htons(ETH_P_IPV6);
+			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;
+}
+
 /**
  * 	struct nft_verdict - nf_tables verdict
  *
diff --git a/net/netfilter/nft_chain_filter.c b/net/netfilter/nft_chain_filter.c
index b16185e9a6dd..a5174adb1abc 100644
--- a/net/netfilter/nft_chain_filter.c
+++ b/net/netfilter/nft_chain_filter.c
@@ -233,10 +233,16 @@ nft_do_chain_bridge(void *priv,
 		    const struct nf_hook_state *state)
 {
 	struct nft_pktinfo pkt;
+	int ret, offset;
+	__be16 proto;
 
-	nft_set_pktinfo(&pkt, skb, state);
+	proto = eth_hdr(skb)->h_proto;
+
+	offset = nft_set_bridge_pktinfo(&pkt, skb, state, &proto);
+	if (offset < 0)
+		return NF_ACCEPT;
 
-	switch (eth_hdr(skb)->h_proto) {
+	switch (proto) {
 	case htons(ETH_P_IP):
 		nft_set_pktinfo_ipv4_validate(&pkt);
 		break;
@@ -248,7 +254,12 @@ nft_do_chain_bridge(void *priv,
 		break;
 	}
 
-	return nft_do_chain(&pkt, priv);
+	ret = nft_do_chain(&pkt, priv);
+
+	if (offset && ret == NF_ACCEPT)
+		skb_reset_network_header(skb);
+
+	return ret;
 }
 
 static const struct nft_chain_type nft_chain_filter_bridge = {
-- 
2.50.0