netfilter: nf_log: do not assume ethernet header in netdev family

In netdev family, we will handle non ethernet packets, so using
eth_hdr(skb)->h_proto is incorrect.

Meanwhile, we can use socket(AF_PACKET...) to sending packets, so
skb->protocol is not always set in bridge family.

Add an extra parameter into nf_log_l2packet to solve this issue.

Fixes: 1fddf4bad0ac ("netfilter: nf_log: add packet logging for netdev family")
Signed-off-by: Liping Zhang <zlpnobody@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

include/net/netfilter/nf_log.h

@@ -109,7 +109,9 @@ void nf_log_dump_packet_common(struct nf_log_buf *m, u_int8_t pf,
 			       const struct net_device *out,
 			       const struct nf_loginfo *loginfo,
 			       const char *prefix);
-void nf_log_l2packet(struct net *net, u_int8_t pf, unsigned int hooknum,
+void nf_log_l2packet(struct net *net, u_int8_t pf,
+		     __be16 protocol,
+		     unsigned int hooknum,
 		     const struct sk_buff *skb,
 		     const struct net_device *in,
 		     const struct net_device *out,

net/bridge/netfilter/nf_log_bridge.c

@@ -24,7 +24,8 @@ static void nf_log_bridge_packet(struct net *net, u_int8_t pf,
 				 const struct nf_loginfo *loginfo,
 				 const char *prefix)
 {
-	nf_log_l2packet(net, pf, hooknum, skb, in, out, loginfo, prefix);
+	nf_log_l2packet(net, pf, eth_hdr(skb)->h_proto, hooknum, skb,
+			in, out, loginfo, prefix);
 }
 
 static struct nf_logger nf_bridge_logger __read_mostly = {

net/netfilter/nf_log_common.c

@@ -177,6 +177,7 @@ EXPORT_SYMBOL_GPL(nf_log_dump_packet_common);
 
 /* bridge and netdev logging families share this code. */
 void nf_log_l2packet(struct net *net, u_int8_t pf,
+		     __be16 protocol,
 		     unsigned int hooknum,
 		     const struct sk_buff *skb,
 		     const struct net_device *in,
@@ -184,7 +185,7 @@ void nf_log_l2packet(struct net *net, u_int8_t pf,
 		     const struct nf_loginfo *loginfo,
 		     const char *prefix)
 {
-	switch (eth_hdr(skb)->h_proto) {
+	switch (protocol) {
 	case htons(ETH_P_IP):
 		nf_log_packet(net, NFPROTO_IPV4, hooknum, skb, in, out,
 			      loginfo, "%s", prefix);

net/netfilter/nf_log_netdev.c

@@ -23,7 +23,8 @@ static void nf_log_netdev_packet(struct net *net, u_int8_t pf,
 				 const struct nf_loginfo *loginfo,
 				 const char *prefix)
 {
-	nf_log_l2packet(net, pf, hooknum, skb, in, out, loginfo, prefix);
+	nf_log_l2packet(net, pf, skb->protocol, hooknum, skb, in, out,
+			loginfo, prefix);
 }
 
 static struct nf_logger nf_netdev_logger __read_mostly = {