[PATCH nf 2/2 v2] bridge: set the pktinfo for IPv4/IPv6 traffic

[Alvaro Neira Ayuso <alvaroneay@gmail.com>]

This patch sets the pktinfo for IPv4/IPv6 traffic. Therefore, we can check the
meta l4proto for IPv4/IPv6 traffic in bridge, before we don't have enough
information to do it. Example:

  nft add rule bridge filter input ether type {ip, ip6} meta l4proto udp counter
and
  nft add rule bridge filter input ether type {ip, ip6} meta l4proto tcp counter

With this patch, we can filter the traffic using the transport context that we
want.

Signed-off-by: Alvaro Neira Ayuso <alvaroneay@gmail.com>
---
[changes in v2]
 * Refactor the code to make it more clear
 * Make sure that IPv6 is enabled

 net/bridge/netfilter/nf_tables_bridge.c |   21 ++++++++++++++++++++-
 1 file changed, 20 insertions(+), 1 deletion(-)

diff --git a/net/bridge/netfilter/nf_tables_bridge.c b/net/bridge/netfilter/nf_tables_bridge.c
index d468c19..f4471d7 100644
--- a/net/bridge/netfilter/nf_tables_bridge.c
+++ b/net/bridge/netfilter/nf_tables_bridge.c
@@ -16,6 +16,8 @@
 #include <net/netfilter/nf_tables_bridge.h>
 #include <linux/ip.h>
 #include <linux/ipv6.h>
+#include <net/netfilter/nf_tables_ipv4.h>
+#include <net/netfilter/nf_tables_ipv6.h>
 
 int nft_bridge_iphdr_validate(struct sk_buff *skb)
 {
@@ -71,7 +73,24 @@ nft_do_chain_bridge(const struct nf_hook_ops *ops,
 {
 	struct nft_pktinfo pkt;
 
-	nft_set_pktinfo(&pkt, ops, skb, in, out);
+	switch (eth_hdr(skb)->h_proto) {
+	case htons(ETH_P_IP):
+		if (!nft_bridge_iphdr_validate(skb))
+			nft_set_pktinfo(&pkt, ops, skb, in, out);
+		else
+			nft_set_pktinfo_ipv4(&pkt, ops, skb, in, out);
+		break;
+	case htons(ETH_P_IPV6):
+		#if IS_ENABLED(CONFIG_IPV6)
+			if (!nft_bridge_ip6hdr_validate(skb) ||
+			    nft_set_pktinfo_ipv6(&pkt, ops, skb, in, out) < 0)
+				nft_set_pktinfo(&pkt, ops, skb, in, out);
+			break;
+		#endif
+	default:
+		nft_set_pktinfo(&pkt, ops, skb, in, out);
+		break;
+	}
 
 	return nft_do_chain(&pkt, ops);
 }
-- 
1.7.10.4