From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pablo Neira Ayuso Subject: [PATCH 06/10] netfilter: bridge: honor frag_max_size when refragmenting Date: Wed, 15 Mar 2017 18:01:08 +0100 Message-ID: <1489597272-30347-7-git-send-email-pablo@netfilter.org> References: <1489597272-30347-1-git-send-email-pablo@netfilter.org> Cc: davem@davemloft.net, netdev@vger.kernel.org To: netfilter-devel@vger.kernel.org Return-path: In-Reply-To: <1489597272-30347-1-git-send-email-pablo@netfilter.org> Sender: netfilter-devel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org From: Florian Westphal consider a bridge with mtu 9000, but end host sending smaller packets to another host with mtu < 9000. In this case, after reassembly, bridge+defrag would refragment, and then attempt to send the reassembled packet as long as it was below 9k. Instead we have to cap by the largest fragment size seen. Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso --- net/bridge/br_netfilter_hooks.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) diff --git a/net/bridge/br_netfilter_hooks.c b/net/bridge/br_netfilter_hooks.c index 95087e6e8258..3c5185021c1c 100644 --- a/net/bridge/br_netfilter_hooks.c +++ b/net/bridge/br_netfilter_hooks.c @@ -721,18 +721,20 @@ static unsigned int nf_bridge_mtu_reduction(const struct sk_buff *skb) static int br_nf_dev_queue_xmit(struct net *net, struct sock *sk, struct sk_buff *skb) { - struct nf_bridge_info *nf_bridge; - unsigned int mtu_reserved; + struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb); + unsigned int mtu, mtu_reserved; mtu_reserved = nf_bridge_mtu_reduction(skb); + mtu = skb->dev->mtu; + + if (nf_bridge->frag_max_size && nf_bridge->frag_max_size < mtu) + mtu = nf_bridge->frag_max_size; - if (skb_is_gso(skb) || skb->len + mtu_reserved <= skb->dev->mtu) { + if (skb_is_gso(skb) || skb->len + mtu_reserved <= mtu) { nf_bridge_info_free(skb); return br_dev_queue_push_xmit(net, sk, skb); } - nf_bridge = nf_bridge_info_get(skb); - /* This is wrong! We should preserve the original fragment * boundaries by preserving frag_list rather than refragmenting. */ -- 2.1.4