netfilter: bridge: refactor frag_max_size

Currently frag_max_size is member of br_input_skb_cb and copied back and
forth using IPCB(skb) and BR_INPUT_SKB_CB(skb) each time it is changed or
used.

Attach frag_max_size to nf_bridge_info and set value in pre_routing and
forward functions. Use its value in forward and xmit functions.

Signed-off-by: Bernhard Thaler <bernhard.thaler@wvnet.at>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

include/linux/skbuff.h

@@ -174,6 +174,7 @@ struct nf_bridge_info {
 		BRNF_PROTO_PPPOE
 	} orig_proto:8;
 	bool			pkt_otherhost;
+	__u16			frag_max_size;
 	unsigned int		mask;
 	struct net_device	*physindev;
 	union {

net/bridge/br_netfilter.c

@@ -440,10 +440,8 @@ static int br_nf_pre_routing_finish(struct sock *sk, struct sk_buff *skb)
 	struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb);
 	struct rtable *rt;
 	int err;
-	int frag_max_size;
 
-	frag_max_size = IPCB(skb)->frag_max_size;
-	BR_INPUT_SKB_CB(skb)->frag_max_size = frag_max_size;
+	nf_bridge->frag_max_size = IPCB(skb)->frag_max_size;
 
 	if (nf_bridge->pkt_otherhost) {
 		skb->pkt_type = PACKET_OTHERHOST;
@@ -738,11 +736,9 @@ static int br_nf_forward_finish(struct sock *sk, struct sk_buff *skb)
 	struct net_device *in;
 
 	if (!IS_ARP(skb) && !IS_VLAN_ARP(skb)) {
-		int frag_max_size;
 
 		if (skb->protocol == htons(ETH_P_IP)) {
-			frag_max_size = IPCB(skb)->frag_max_size;
-			BR_INPUT_SKB_CB(skb)->frag_max_size = frag_max_size;
+			nf_bridge->frag_max_size = IPCB(skb)->frag_max_size;
 		}
 
 		in = nf_bridge->physindev;
@@ -806,12 +802,9 @@ static unsigned int br_nf_forward_ip(const struct nf_hook_ops *ops,
 	}
 
 	if (pf == NFPROTO_IPV4) {
-		int frag_max = BR_INPUT_SKB_CB(skb)->frag_max_size;
-
 		if (br_parse_ip_options(skb))
 			return NF_DROP;
-
-		IPCB(skb)->frag_max_size = frag_max;
+		IPCB(skb)->frag_max_size = nf_bridge->frag_max_size;
 	}
 
 	nf_bridge->physoutdev = skb->dev;
@@ -904,7 +897,7 @@ static int br_nf_ip_fragment(struct sock *sk, struct sk_buff *skb,
 static int br_nf_dev_queue_xmit(struct sock *sk, struct sk_buff *skb)
 {
 	int ret;
-	int frag_max_size;
+	struct nf_bridge_info *nf_bridge;
 	unsigned int mtu_reserved;
 
 	if (skb_is_gso(skb) || skb->protocol != htons(ETH_P_IP)) {
@@ -913,17 +906,18 @@ static int br_nf_dev_queue_xmit(struct sock *sk, struct sk_buff *skb)
 	}
 
 	mtu_reserved = nf_bridge_mtu_reduction(skb);
+	nf_bridge = nf_bridge_info_get(skb);
 	/* This is wrong! We should preserve the original fragment
 	 * boundaries by preserving frag_list rather than refragmenting.
 	 */
 	if (skb->len + mtu_reserved > skb->dev->mtu) {
 		struct brnf_frag_data *data;
 
-		frag_max_size = BR_INPUT_SKB_CB(skb)->frag_max_size;
 		if (br_parse_ip_options(skb))
 			/* Drop invalid packet */
 			return NF_DROP;
-		IPCB(skb)->frag_max_size = frag_max_size;
+
+		IPCB(skb)->frag_max_size = nf_bridge->frag_max_size;
 
 		nf_bridge_update_protocol(skb);
 

net/bridge/br_private.h

@@ -304,7 +304,6 @@ struct br_input_skb_cb {
 	int mrouters_only;
 #endif
 
-	u16 frag_max_size;
 	bool proxyarp_replied;
 
 #ifdef CONFIG_BRIDGE_VLAN_FILTERING