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Commit 6c79bf0f2440fd250c8fce8d9b82fcf03d4e8350

Authored by Bart De Schuymer
Committed by Patrick McHardy
1 parent 6291055465
Exists in master and in 7 other branches imx_3.0.35_4.1.0, imx_3.10.17_1.0.1_ga, imx_3.10.53_1.1.0_ga, imx_3.14.28_1.0.0_ga, smarc-imx_3.10.53_1.1.0_ga, smarc-imx_3.14.28_1.0.0_ga, smarc-l5.0.0_1.0.0-ga

netfilter: bridge-netfilter: fix refragmenting IP traffic encapsulated in PPPoE traffic 

The MTU for IP traffic encapsulated inside PPPoE traffic is smaller
than the MTU of the Ethernet device (1500). Connection tracking
gathers all IP packets and sometimes will refragment them in
ip_fragment(). We then need to subtract the length of the
encapsulating header from the mtu used in ip_fragment(). The check in
br_nf_dev_queue_xmit() which determines if ip_fragment() has to be
called is also updated for the PPPoE-encapsulated packets.
nf_bridge_copy_header() is also updated to make sure the PPPoE data
length field has the correct value.

Signed-off-by: Bart De Schuymer <bdschuym@pandora.be>
Signed-off-by: Patrick McHardy <kaber@trash.net>

Showing 3 changed files with 12 additions and 1 deletions Side-by-side Diff

include/linux/netfilter_bridge.h
Diff comments   View file @ 6c79bf0
... ... @@ -68,6 +68,13 @@
68 68 }
69 69 }
70 70  
  71 +static inline unsigned int nf_bridge_mtu_reduction(const struct sk_buff *skb)
  72 +{
  73 + if (unlikely(skb->nf_bridge->mask & BRNF_PPPoE))
  74 + return PPPOE_SES_HLEN;
  75 + return 0;
  76 +}
  77 +
71 78 extern int br_handle_frame_finish(struct sk_buff *skb);
72 79 /* Only used in br_device.c */
73 80 static inline int br_nf_pre_routing_finish_bridge_slow(struct sk_buff *skb)
net/bridge/br_netfilter.c
Diff comments   View file @ 6c79bf0
... ... @@ -745,7 +745,7 @@
745 745 static int br_nf_dev_queue_xmit(struct sk_buff *skb)
746 746 {
747 747 if (skb->nfct != NULL && skb->protocol == htons(ETH_P_IP) &&
748   - skb->len > skb->dev->mtu &&
  748 + skb->len + nf_bridge_mtu_reduction(skb) > skb->dev->mtu &&
749 749 !skb_is_gso(skb))
750 750 return ip_fragment(skb, br_dev_queue_push_xmit);
751 751 else
net/ipv4/ip_output.c
Diff comments   View file @ 6c79bf0
... ... @@ -469,6 +469,10 @@
469 469  
470 470 hlen = iph->ihl * 4;
471 471 mtu = dst_mtu(&rt->u.dst) - hlen; /* Size of data space */
  472 +#ifdef CONFIG_BRIDGE_NETFILTER
  473 + if (skb->nf_bridge)
  474 + mtu -= nf_bridge_mtu_reduction(skb);
  475 +#endif
472 476 IPCB(skb)->flags |= IPSKB_FRAG_COMPLETE;
473 477  
474 478 /* When frag_list is given, use it. First, check its validity: