br_netfilter: use single forward hook for ip and arp

br_netfilter registers two forward hooks, one for ip and one for arp.

Just use a common function for both and then call the arp/ip helper
as needed.
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

net/bridge/br_netfilter_hooks.c

@@ -570,18 +570,12 @@ static int br_nf_forward_finish(struct net *net, struct sock *sk, struct sk_buff
 }
 
 
-/* This is the 'purely bridged' case.  For IP, we pass the packet to
- * netfilter with indev and outdev set to the bridge device,
- * but we are still able to filter on the 'real' indev/outdev
- * because of the physdev module. For ARP, indev and outdev are the
- * bridge ports. */
-static unsigned int br_nf_forward_ip(void *priv,
-				     struct sk_buff *skb,
-				     const struct nf_hook_state *state)
+static unsigned int br_nf_forward_ip(struct sk_buff *skb,
+				     const struct nf_hook_state *state,
+				     u8 pf)
 {
 	struct nf_bridge_info *nf_bridge;
 	struct net_device *parent;
-	u_int8_t pf;
 
 	nf_bridge = nf_bridge_info_get(skb);
 	if (!nf_bridge)
@@ -600,15 +594,6 @@ static unsigned int br_nf_forward_ip(void *priv,
 	if (!parent)
 		return NF_DROP_REASON(skb, SKB_DROP_REASON_DEV_READY, 0);
 
-	if (IS_IP(skb) || is_vlan_ip(skb, state->net) ||
-	    is_pppoe_ip(skb, state->net))
-		pf = NFPROTO_IPV4;
-	else if (IS_IPV6(skb) || is_vlan_ipv6(skb, state->net) ||
-		 is_pppoe_ipv6(skb, state->net))
-		pf = NFPROTO_IPV6;
-	else
-		return NF_ACCEPT;
-
 	nf_bridge_pull_encap_header(skb);
 
 	if (skb->pkt_type == PACKET_OTHERHOST) {
@@ -620,19 +605,18 @@ static unsigned int br_nf_forward_ip(void *priv,
 		if (br_validate_ipv4(state->net, skb))
 			return NF_DROP_REASON(skb, SKB_DROP_REASON_IP_INHDR, 0);
 		IPCB(skb)->frag_max_size = nf_bridge->frag_max_size;
-	}
-
-	if (pf == NFPROTO_IPV6) {
+		skb->protocol = htons(ETH_P_IP);
+	} else if (pf == NFPROTO_IPV6) {
 		if (br_validate_ipv6(state->net, skb))
 			return NF_DROP_REASON(skb, SKB_DROP_REASON_IP_INHDR, 0);
 		IP6CB(skb)->frag_max_size = nf_bridge->frag_max_size;
+		skb->protocol = htons(ETH_P_IPV6);
+	} else {
+		WARN_ON_ONCE(1);
+		return NF_DROP;
 	}
 
 	nf_bridge->physoutdev = skb->dev;
-	if (pf == NFPROTO_IPV4)
-		skb->protocol = htons(ETH_P_IP);
-	else
-		skb->protocol = htons(ETH_P_IPV6);
 
 	NF_HOOK(pf, NF_INET_FORWARD, state->net, NULL, skb,
 		brnf_get_logical_dev(skb, state->in, state->net),
@@ -641,8 +625,7 @@ static unsigned int br_nf_forward_ip(void *priv,
 	return NF_STOLEN;
 }
 
-static unsigned int br_nf_forward_arp(void *priv,
-				      struct sk_buff *skb,
+static unsigned int br_nf_forward_arp(struct sk_buff *skb,
 				      const struct nf_hook_state *state)
 {
 	struct net_bridge_port *p;
@@ -659,11 +642,8 @@ static unsigned int br_nf_forward_arp(void *priv,
 	if (!brnet->call_arptables && !br_opt_get(br, BROPT_NF_CALL_ARPTABLES))
 		return NF_ACCEPT;
 
-	if (!IS_ARP(skb)) {
-		if (!is_vlan_arp(skb, state->net))
-			return NF_ACCEPT;
+	if (is_vlan_arp(skb, state->net))
 		nf_bridge_pull_encap_header(skb);
-	}
 
 	if (unlikely(!pskb_may_pull(skb, sizeof(struct arphdr))))
 		return NF_DROP_REASON(skb, SKB_DROP_REASON_PKT_TOO_SMALL, 0);
@@ -680,6 +660,28 @@ static unsigned int br_nf_forward_arp(void *priv,
 	return NF_STOLEN;
 }
 
+/* This is the 'purely bridged' case.  For IP, we pass the packet to
+ * netfilter with indev and outdev set to the bridge device,
+ * but we are still able to filter on the 'real' indev/outdev
+ * because of the physdev module. For ARP, indev and outdev are the
+ * bridge ports.
+ */
+static unsigned int br_nf_forward(void *priv,
+				  struct sk_buff *skb,
+				  const struct nf_hook_state *state)
+{
+	if (IS_IP(skb) || is_vlan_ip(skb, state->net) ||
+	    is_pppoe_ip(skb, state->net))
+		return br_nf_forward_ip(skb, state, NFPROTO_IPV4);
+	if (IS_IPV6(skb) || is_vlan_ipv6(skb, state->net) ||
+	    is_pppoe_ipv6(skb, state->net))
+		return br_nf_forward_ip(skb, state, NFPROTO_IPV6);
+	if (IS_ARP(skb) || is_vlan_arp(skb, state->net))
+		return br_nf_forward_arp(skb, state);
+
+	return NF_ACCEPT;
+}
+
 static int br_nf_push_frag_xmit(struct net *net, struct sock *sk, struct sk_buff *skb)
 {
 	struct brnf_frag_data *data;
@@ -937,13 +939,7 @@ static const struct nf_hook_ops br_nf_ops[] = {
 		.priority = NF_BR_PRI_BRNF,
 	},
 	{
-		.hook = br_nf_forward_ip,
-		.pf = NFPROTO_BRIDGE,
-		.hooknum = NF_BR_FORWARD,
-		.priority = NF_BR_PRI_BRNF - 1,
-	},
-	{
-		.hook = br_nf_forward_arp,
+		.hook = br_nf_forward,
 		.pf = NFPROTO_BRIDGE,
 		.hooknum = NF_BR_FORWARD,
 		.priority = NF_BR_PRI_BRNF,