queue-5.0/net-vrf-fix-ping-failed-when-vrf-mtu-is-set-to-0.patch

   1 From f46010b917db41a3475f25295dde1bccc24d8ffa Mon Sep 17 00:00:00 2001
   2 From: Miaohe Lin <linmiaohe@huawei.com>
   3 Date: Mon, 8 Apr 2019 10:04:20 +0800
   4 Subject: net: vrf: Fix ping failed when vrf mtu is set to 0
   5
   6 [ Upstream commit 5055376a3b44c4021de8830c9157f086a97731df ]
   7
   8 When the mtu of a vrf device is set to 0, it would cause ping
   9 failed. So I think we should limit vrf mtu in a reasonable range
  10 to solve this problem. I set dev->min_mtu to IPV6_MIN_MTU, so it
  11 will works for both ipv4 and ipv6. And if dev->max_mtu still be 0
  12 can be confusing, so I set dev->max_mtu to ETH_MAX_MTU.
  13
  14 Here is the reproduce step:
  15
  16 1.Config vrf interface and set mtu to 0:
  17 3: enp4s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel
  18 master vrf1 state UP mode DEFAULT group default qlen 1000
  19     link/ether 52:54:00:9e:dd:c1 brd ff:ff:ff:ff:ff:ff
  20
  21 2.Ping peer:
  22 3: enp4s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel
  23 master vrf1 state UP group default qlen 1000
  24     link/ether 52:54:00:9e:dd:c1 brd ff:ff:ff:ff:ff:ff
  25     inet 10.0.0.1/16 scope global enp4s0
  26        valid_lft forever preferred_lft forever
  27 connect: Network is unreachable
  28
  29 3.Set mtu to default value, ping works:
  30 PING 10.0.0.2 (10.0.0.2) 56(84) bytes of data.
  31 64 bytes from 10.0.0.2: icmp_seq=1 ttl=64 time=1.88 ms
  32
  33 Fixes: ad49bc6361ca2 ("net: vrf: remove MTU limits for vrf device")
  34 Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
  35 Reviewed-by: David Ahern <dsahern@gmail.com>
  36 Signed-off-by: David S. Miller <davem@davemloft.net>
  37 Signed-off-by: Sasha Levin <sashal@kernel.org>
  38 ---
  39  drivers/net/vrf.c | 8 ++++++--
  40  1 file changed, 6 insertions(+), 2 deletions(-)
  41
  42 diff --git a/drivers/net/vrf.c b/drivers/net/vrf.c
  43 index 6d1a1abbed27..cd15c32b2e43 100644
  44 --- a/drivers/net/vrf.c
  45 +++ b/drivers/net/vrf.c
  46 @@ -1275,8 +1275,12 @@ static void vrf_setup(struct net_device *dev)
  47         dev->priv_flags |= IFF_NO_QUEUE;
  48         dev->priv_flags |= IFF_NO_RX_HANDLER;
  49
  50 -       dev->min_mtu = 0;
  51 -       dev->max_mtu = 0;
  52 +       /* VRF devices do not care about MTU, but if the MTU is set
  53 +        * too low then the ipv4 and ipv6 protocols are disabled
  54 +        * which breaks networking.
  55 +        */
  56 +       dev->min_mtu = IPV6_MIN_MTU;
  57 +       dev->max_mtu = ETH_MAX_MTU;
  58  }
  59
  60  static int vrf_validate(struct nlattr *tb[], struct nlattr *data[],
  61 --
  62 2.19.1
  63