On Sun, Oct 05, 2014 at 11:53:43AM +0800, Herbert Xu wrote:
>
> What we should do therefore is to save any necessary information
> such as frag_max_size into the bridge CB area when reentering the
> bridge and then copy it back upon the next reentry into the IP stack.
Here's a patch that does just that:
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@xxxxxxxxxxxxxxxxxxx>
diff --git a/net/bridge/br_netfilter.c b/net/bridge/br_netfilter.c
index 389d1c6..47fe079 100644
--- a/net/bridge/br_netfilter.c
+++ b/net/bridge/br_netfilter.c
@@ -398,6 +398,7 @@ 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);
@@ -453,6 +454,10 @@ 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;
@@ -864,13 +869,19 @@ 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
--- 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
Cheers,
--
Email: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
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