From 6c79bf0f2440fd250c8fce8d9b82fcf03d4e8350 Mon Sep 17 00:00:00 2001 From: Bart De Schuymer Date: Tue, 20 Apr 2010 16:22:01 +0200 Subject: [PATCH] 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 Signed-off-by: Patrick McHardy --- include/linux/netfilter_bridge.h | 7 +++++++ net/bridge/br_netfilter.c | 2 +- net/ipv4/ip_output.c | 4 ++++ 3 files changed, 12 insertions(+), 1 deletion(-) diff --git a/include/linux/netfilter_bridge.h b/include/linux/netfilter_bridge.h index ea0e44b..0ddd161 100644 --- a/include/linux/netfilter_bridge.h +++ b/include/linux/netfilter_bridge.h @@ -68,6 +68,13 @@ static inline unsigned int nf_bridge_encap_header_len(const struct sk_buff *skb) } } +static inline unsigned int nf_bridge_mtu_reduction(const struct sk_buff *skb) +{ + if (unlikely(skb->nf_bridge->mask & BRNF_PPPoE)) + return PPPOE_SES_HLEN; + return 0; +} + extern int br_handle_frame_finish(struct sk_buff *skb); /* Only used in br_device.c */ static inline int br_nf_pre_routing_finish_bridge_slow(struct sk_buff *skb) diff --git a/net/bridge/br_netfilter.c b/net/bridge/br_netfilter.c index 6b80ebc..93f80fe 100644 --- a/net/bridge/br_netfilter.c +++ b/net/bridge/br_netfilter.c @@ -745,7 +745,7 @@ static unsigned int br_nf_forward_arp(unsigned int hook, struct sk_buff *skb, static int br_nf_dev_queue_xmit(struct sk_buff *skb) { if (skb->nfct != NULL && skb->protocol == htons(ETH_P_IP) && - skb->len > skb->dev->mtu && + skb->len + nf_bridge_mtu_reduction(skb) > skb->dev->mtu && !skb_is_gso(skb)) return ip_fragment(skb, br_dev_queue_push_xmit); else diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c index b0b2e30..d979710 100644 --- a/net/ipv4/ip_output.c +++ b/net/ipv4/ip_output.c @@ -469,6 +469,10 @@ int ip_fragment(struct sk_buff *skb, int (*output)(struct sk_buff *)) hlen = iph->ihl * 4; mtu = dst_mtu(&rt->u.dst) - hlen; /* Size of data space */ +#ifdef CONFIG_BRIDGE_NETFILTER + if (skb->nf_bridge) + mtu -= nf_bridge_mtu_reduction(skb); +#endif IPCB(skb)->flags |= IPSKB_FRAG_COMPLETE; /* When frag_list is given, use it. First, check its validity: -- 2.7.4