4.20-stable review patch. If anyone has any objections, please let me know.
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From: Yunjian Wang wangyunjian@huawei.com
[ Upstream commit 28c1382fa28f2e2d9d0d6f25ae879b5af2ecbd03 ]
The skb header should be set to ethernet header before using is_skb_forwardable. Because the ethernet header length has been considered in is_skb_forwardable(including dev->hard_header_len length).
To reproduce the issue: 1, add 2 ports on linux bridge br using following commands: $ brctl addbr br $ brctl addif br eth0 $ brctl addif br eth1 2, the MTU of eth0 and eth1 is 1500 3, send a packet(Data 1480, UDP 8, IP 20, Ethernet 14, VLAN 4) from eth0 to eth1
So the expect result is packet larger than 1500 cannot pass through eth0 and eth1. But currently, the packet passes through success, it means eth1's MTU limit doesn't take effect.
Fixes: f6367b4660dd ("bridge: use is_skb_forwardable in forward path") Cc: bridge@lists.linux-foundation.org Cc: Nkolay Aleksandrov nikolay@cumulusnetworks.com Cc: Roopa Prabhu roopa@cumulusnetworks.com Cc: Stephen Hemminger stephen@networkplumber.org Signed-off-by: Yunjian Wang wangyunjian@huawei.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/bridge/br_forward.c | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-)
--- a/net/bridge/br_forward.c +++ b/net/bridge/br_forward.c @@ -36,10 +36,10 @@ static inline int should_deliver(const s
int br_dev_queue_push_xmit(struct net *net, struct sock *sk, struct sk_buff *skb) { + skb_push(skb, ETH_HLEN); if (!is_skb_forwardable(skb->dev, skb)) goto drop;
- skb_push(skb, ETH_HLEN); br_drop_fake_rtable(skb);
if (skb->ip_summed == CHECKSUM_PARTIAL && @@ -98,12 +98,11 @@ static void __br_forward(const struct ne net = dev_net(indev); } else { if (unlikely(netpoll_tx_running(to->br->dev))) { - if (!is_skb_forwardable(skb->dev, skb)) { + skb_push(skb, ETH_HLEN); + if (!is_skb_forwardable(skb->dev, skb)) kfree_skb(skb); - } else { - skb_push(skb, ETH_HLEN); + else br_netpoll_send_skb(to, skb); - } return; } br_hook = NF_BR_LOCAL_OUT;