From 49d16b23cd1e61c028ee088c5a64e9ac6a9c6147 Mon Sep 17 00:00:00 2001 From: Andy Zhou Date: Fri, 15 May 2015 14:15:37 -0700 Subject: bridge_netfilter: No ICMP packet on IPv4 fragmentation error When bridge netfilter re-fragments an IP packet for output, all packets that can not be re-fragmented to their original input size should be silently discarded. However, current bridge netfilter output path generates an ICMP packet with 'size exceeded MTU' message for such packets, this is a bug. This patch refactors the ip_fragment() API to allow two separate use cases. The bridge netfilter user case will not send ICMP, the routing output will, as before. Signed-off-by: Andy Zhou Acked-by: Florian Westphal Signed-off-by: David S. Miller --- net/bridge/br_netfilter.c | 21 ++++++++++++++++++++- 1 file changed, 20 insertions(+), 1 deletion(-) (limited to 'net/bridge') diff --git a/net/bridge/br_netfilter.c b/net/bridge/br_netfilter.c index 2b0e8bb49944..1d2eb32d8270 100644 --- a/net/bridge/br_netfilter.c +++ b/net/bridge/br_netfilter.c @@ -853,6 +853,25 @@ static int br_nf_push_frag_xmit(struct sock *sk, struct sk_buff *skb) return br_dev_queue_push_xmit(sk, skb); } +static int br_nf_ip_fragment(struct sock *sk, struct sk_buff *skb, + int (*output)(struct sock *, struct sk_buff *)) +{ + unsigned int mtu = ip_skb_dst_mtu(skb); + struct iphdr *iph = ip_hdr(skb); + struct rtable *rt = skb_rtable(skb); + struct net_device *dev = rt->dst.dev; + + if (unlikely(((iph->frag_off & htons(IP_DF)) && !skb->ignore_df) || + (IPCB(skb)->frag_max_size && + IPCB(skb)->frag_max_size > mtu))) { + IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGFAILS); + kfree_skb(skb); + return -EMSGSIZE; + } + + return ip_do_fragment(sk, skb, output); +} + static int br_nf_dev_queue_xmit(struct sock *sk, struct sk_buff *skb) { int ret; @@ -886,7 +905,7 @@ static int br_nf_dev_queue_xmit(struct sock *sk, struct sk_buff *skb) skb_copy_from_linear_data_offset(skb, -data->size, data->mac, data->size); - ret = ip_fragment(sk, skb, br_nf_push_frag_xmit); + ret = br_nf_ip_fragment(sk, skb, br_nf_push_frag_xmit); } else { nf_bridge_info_free(skb); ret = br_dev_queue_push_xmit(sk, skb); -- cgit v1.2.3