[ Upstream commit 5055376a3b44c4021de8830c9157f086a97731df ]
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: <BROADCAST,MULTICAST,UP,LOWER_UP> 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: <BROADCAST,MULTICAST,UP,LOWER_UP> 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 linmiaohe@huawei.com Reviewed-by: David Ahern dsahern@gmail.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/net/vrf.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)
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[],