netfilter: bridge: add and use nf_bridge_info_get helper

Don't access skb->nf_bridge directly, this pointer will be removed soon.
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

net/bridge/br_netfilter.c

@@ -124,6 +124,11 @@ struct brnf_frag_data {
 static DEFINE_PER_CPU(struct brnf_frag_data, brnf_frag_data_storage);
 #endif
 
+static struct nf_bridge_info *nf_bridge_info_get(const struct sk_buff *skb)
+{
+	return skb->nf_bridge;
+}
+
 static inline struct rtable *bridge_parent_rtable(const struct net_device *dev)
 {
 	struct net_bridge_port *port;
@@ -268,7 +273,7 @@ static void nf_bridge_update_protocol(struct sk_buff *skb)
  * bridge PRE_ROUTING hook. */
 static int br_nf_pre_routing_finish_ipv6(struct sk_buff *skb)
 {
-	struct nf_bridge_info *nf_bridge = skb->nf_bridge;
+	struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb);
 	struct rtable *rt;
 
 	if (nf_bridge->mask & BRNF_PKT_TYPE) {
@@ -300,7 +305,6 @@ static int br_nf_pre_routing_finish_ipv6(struct sk_buff *skb)
  */
 static int br_nf_pre_routing_finish_bridge(struct sk_buff *skb)
 {
-	struct nf_bridge_info *nf_bridge = skb->nf_bridge;
 	struct neighbour *neigh;
 	struct dst_entry *dst;
 
@@ -310,6 +314,7 @@ static int br_nf_pre_routing_finish_bridge(struct sk_buff *skb)
 	dst = skb_dst(skb);
 	neigh = dst_neigh_lookup_skb(dst, skb);
 	if (neigh) {
+		struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb);
 		int ret;
 
 		if (neigh->hh.hh_len) {
@@ -396,7 +401,7 @@ static int br_nf_pre_routing_finish(struct sk_buff *skb)
 {
 	struct net_device *dev = skb->dev;
 	struct iphdr *iph = ip_hdr(skb);
-	struct nf_bridge_info *nf_bridge = skb->nf_bridge;
+	struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb);
 	struct rtable *rt;
 	int err;
 	int frag_max_size;
@@ -488,7 +493,7 @@ static struct net_device *brnf_get_logical_dev(struct sk_buff *skb, const struct
 /* Some common code for IPv4/IPv6 */
 static struct net_device *setup_pre_routing(struct sk_buff *skb)
 {
-	struct nf_bridge_info *nf_bridge = skb->nf_bridge;
+	struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb);
 
 	if (skb->pkt_type == PACKET_OTHERHOST) {
 		skb->pkt_type = PACKET_HOST;
@@ -687,7 +692,7 @@ static unsigned int br_nf_local_in(const struct nf_hook_ops *ops,
 /* PF_BRIDGE/FORWARD *************************************************/
 static int br_nf_forward_finish(struct sk_buff *skb)
 {
-	struct nf_bridge_info *nf_bridge = skb->nf_bridge;
+	struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb);
 	struct net_device *in;
 
 	if (!IS_ARP(skb) && !IS_VLAN_ARP(skb)) {
@@ -738,6 +743,10 @@ static unsigned int br_nf_forward_ip(const struct nf_hook_ops *ops,
 	if (!nf_bridge_unshare(skb))
 		return NF_DROP;
 
+	nf_bridge = nf_bridge_info_get(skb);
+	if (!nf_bridge)
+		return NF_DROP;
+
 	parent = bridge_parent(out);
 	if (!parent)
 		return NF_DROP;
@@ -751,7 +760,6 @@ static unsigned int br_nf_forward_ip(const struct nf_hook_ops *ops,
 
 	nf_bridge_pull_encap_header(skb);
 
-	nf_bridge = skb->nf_bridge;
 	if (skb->pkt_type == PACKET_OTHERHOST) {
 		skb->pkt_type = PACKET_HOST;
 		nf_bridge->mask |= BRNF_PKT_TYPE;
@@ -886,7 +894,7 @@ static unsigned int br_nf_post_routing(const struct nf_hook_ops *ops,
 				       const struct net_device *out,
 				       int (*okfn)(struct sk_buff *))
 {
-	struct nf_bridge_info *nf_bridge = skb->nf_bridge;
+	struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb);
 	struct net_device *realoutdev = bridge_parent(skb->dev);
 	u_int8_t pf;
 
@@ -955,7 +963,7 @@ static unsigned int ip_sabotage_in(const struct nf_hook_ops *ops,
  */
 static void br_nf_pre_routing_finish_bridge_slow(struct sk_buff *skb)
 {
-	struct nf_bridge_info *nf_bridge = skb->nf_bridge;
+	struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb);
 
 	skb_pull(skb, ETH_HLEN);
 	nf_bridge->mask &= ~BRNF_BRIDGED_DNAT;