From 5055376a3b44c4021de8830c9157f086a97731df Mon Sep 17 00:00:00 2001 From: Miaohe Lin Date: Mon, 8 Apr 2019 10:04:20 +0800 Subject: net: vrf: Fix ping failed when vrf mtu is set to 0 When the mtu of a vrf device is set to 0, it would cause ping failed. So I think we should limit vrf mtu in a reasonable range to solve this problem. I set dev->min_mtu to IPV6_MIN_MTU, so it will works for both ipv4 and ipv6. And if dev->max_mtu still be 0 can be confusing, so I set dev->max_mtu to ETH_MAX_MTU. Here is the reproduce step: 1.Config vrf interface and set mtu to 0: 3: enp4s0: mtu 1500 qdisc fq_codel master vrf1 state UP mode DEFAULT group default qlen 1000 link/ether 52:54:00:9e:dd:c1 brd ff:ff:ff:ff:ff:ff 2.Ping peer: 3: enp4s0: mtu 1500 qdisc fq_codel master vrf1 state UP group default qlen 1000 link/ether 52:54:00:9e:dd:c1 brd ff:ff:ff:ff:ff:ff inet 10.0.0.1/16 scope global enp4s0 valid_lft forever preferred_lft forever connect: Network is unreachable 3.Set mtu to default value, ping works: PING 10.0.0.2 (10.0.0.2) 56(84) bytes of data. 64 bytes from 10.0.0.2: icmp_seq=1 ttl=64 time=1.88 ms Fixes: ad49bc6361ca2 ("net: vrf: remove MTU limits for vrf device") Signed-off-by: Miaohe Lin Reviewed-by: David Ahern Signed-off-by: David S. Miller --- drivers/net/vrf.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) (limited to 'drivers/net/vrf.c') diff --git a/drivers/net/vrf.c b/drivers/net/vrf.c index 6d1a1abbed27..cd15c32b2e43 100644 --- a/drivers/net/vrf.c +++ b/drivers/net/vrf.c @@ -1275,8 +1275,12 @@ static void vrf_setup(struct net_device *dev) dev->priv_flags |= IFF_NO_QUEUE; dev->priv_flags |= IFF_NO_RX_HANDLER; - dev->min_mtu = 0; - dev->max_mtu = 0; + /* VRF devices do not care about MTU, but if the MTU is set + * too low then the ipv4 and ipv6 protocols are disabled + * which breaks networking. + */ + dev->min_mtu = IPV6_MIN_MTU; + dev->max_mtu = ETH_MAX_MTU; } static int vrf_validate(struct nlattr *tb[], struct nlattr *data[], -- cgit v1.2.3-59-g8ed1b