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bridge: Save frag_max_size between PRE_ROUTING and POST_ROUTING

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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>
This commit is contained in:
Herbert Xu 2014-10-05 12:00:22 +08:00 committed by David S. Miller
parent 88b09a6d95
commit 93fdd47e52
2 changed files with 15 additions and 0 deletions
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11
net/bridge/br_netfilter.c
View File

@ -404,6 +404,7 @@ static int br_nf_pre_routing_finish_bridge(struct sk_buff *skb)
ETH_HLEN-ETH_ALEN); ETH_HLEN-ETH_ALEN);
/* tell br_dev_xmit to continue with forwarding */ /* tell br_dev_xmit to continue with forwarding */
nf_bridge->mask |= BRNF_BRIDGED_DNAT; nf_bridge->mask |= BRNF_BRIDGED_DNAT;
/* FIXME Need to refragment */
ret = neigh->output(neigh, skb); ret = neigh->output(neigh, skb);
} }
neigh_release(neigh); 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 nf_bridge_info *nf_bridge = skb->nf_bridge;
struct rtable *rt; struct rtable *rt;
int err; 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) { if (nf_bridge->mask & BRNF_PKT_TYPE) {
skb->pkt_type = PACKET_OTHERHOST; 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) static int br_nf_dev_queue_xmit(struct sk_buff *skb)
{ {
int ret; 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) && if (skb->protocol == htons(ETH_P_IP) &&
skb->len + nf_bridge_mtu_reduction(skb) > skb->dev->mtu && skb->len + nf_bridge_mtu_reduction(skb) > skb->dev->mtu &&
!skb_is_gso(skb)) { !skb_is_gso(skb)) {
frag_max_size = BR_INPUT_SKB_CB(skb)->frag_max_size;
if (br_parse_ip_options(skb)) if (br_parse_ip_options(skb))
/* Drop invalid packet */ /* Drop invalid packet */
return NF_DROP; return NF_DROP;
IPCB(skb)->frag_max_size = frag_max_size;
ret = ip_fragment(skb, br_dev_queue_push_xmit); ret = ip_fragment(skb, br_dev_queue_push_xmit);
} else } else
ret = br_dev_queue_push_xmit(skb); ret = br_dev_queue_push_xmit(skb);

4
net/bridge/br_private.h
View File

@ -305,10 +305,14 @@ struct net_bridge
struct br_input_skb_cb { struct br_input_skb_cb {
struct net_device *brdev; struct net_device *brdev;
#ifdef CONFIG_BRIDGE_IGMP_SNOOPING #ifdef CONFIG_BRIDGE_IGMP_SNOOPING
int igmp; int igmp;
int mrouters_only; int mrouters_only;
#endif #endif
u16 frag_max_size;
#ifdef CONFIG_BRIDGE_VLAN_FILTERING #ifdef CONFIG_BRIDGE_VLAN_FILTERING
bool vlan_filtered; bool vlan_filtered;
#endif #endif