bridge: Save frag_max_size between PRE_ROUTING and POST_ROUTING

As we may defragment the packet in IPv4 PRE_ROUTING and refragment
it after POST_ROUTING we should save the value of frag_max_size.

This is still very wrong as the bridge is supposed to leave the
packets intact, meaning that the right thing to do is to use the
original frag_list for fragmentation.

Unfortunately we don't currently guarantee that the frag_list is
left untouched throughout netfilter so until this changes this is
the best we can do.

There is also a spot in FORWARD where it appears that we can
forward a packet without going through fragmentation, mark it
so that we can fix it later.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/bridge/br_netfilter.c b/net/bridge/br_netfilter.c
index a615264..4063898 100644 (file)
--- a/net/bridge/br_netfilter.c
+++ b/net/bridge/br_netfilter.c
@@ -404,6 +404,7 @@ static int br_nf_pre_routing_finish_bridge(struct sk_buff *skb)
                                                         ETH_HLEN-ETH_ALEN);
                        /* tell br_dev_xmit to continue with forwarding */
                        nf_bridge->mask |= BRNF_BRIDGED_DNAT;
+                       /* FIXME Need to refragment */
                        ret = neigh->output(neigh, skb);
                }
                neigh_release(neigh);
@@ -459,6 +460,10 @@ static int br_nf_pre_routing_finish(struct sk_buff *skb)
        struct nf_bridge_info *nf_bridge = skb->nf_bridge;
        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;
 
        if (nf_bridge->mask & BRNF_PKT_TYPE) {
                skb->pkt_type = PACKET_OTHERHOST;
@@ -863,13 +868,19 @@ static unsigned int br_nf_forward_arp(const struct nf_hook_ops *ops,
 static int br_nf_dev_queue_xmit(struct sk_buff *skb)
 {
        int ret;
+       int frag_max_size;
 
+       /* This is wrong! We should preserve the original fragment
+        * boundaries by preserving frag_list rather than refragmenting.
+        */
        if (skb->protocol == htons(ETH_P_IP) &&
            skb->len + nf_bridge_mtu_reduction(skb) > skb->dev->mtu &&
            !skb_is_gso(skb)) {
+               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;
                ret = ip_fragment(skb, br_dev_queue_push_xmit);
        } else
                ret = br_dev_queue_push_xmit(skb);

diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h
index b6c04cb..2398369 100644 (file)
--- a/net/bridge/br_private.h
+++ b/net/bridge/br_private.h
@@ -305,10 +305,14 @@ struct net_bridge
 
 struct br_input_skb_cb {
        struct net_device *brdev;
+
 #ifdef CONFIG_BRIDGE_IGMP_SNOOPING
        int igmp;
        int mrouters_only;
 #endif
+
+       u16 frag_max_size;
+
 #ifdef CONFIG_BRIDGE_VLAN_FILTERING
        bool vlan_filtered;
 #endif