• Eric Dumazet's avatar
    vlan: mask vlan prio bits · d4b812de
    Eric Dumazet authored
    In commit 48cc32d3
    ("vlan: don't deliver frames for unknown vlans to protocols")
    Florian made sure we set pkt_type to PACKET_OTHERHOST
    if the vlan id is set and we could find a vlan device for this
    particular id.
    
    But we also have a problem if prio bits are set.
    
    Steinar reported an issue on a router receiving IPv6 frames with a
    vlan tag of 4000 (id 0, prio 2), and tunneled into a sit device,
    because skb->vlan_tci is set.
    
    Forwarded frame is completely corrupted : We can see (8100:4000)
    being inserted in the middle of IPv6 source address :
    
    16:48:00.780413 IP6 2001:16d8:8100:4000:ee1c:0:9d9:bc87 >
    9f94:4d95:2001:67c:29f4::: ICMP6, unknown icmp6 type (0), length 64
           0x0000:  0000 0029 8000 c7c3 7103 0001 a0ae e651
           0x0010:  0000 0000 ccce 0b00 0000 0000 1011 1213
           0x0020:  1415 1617 1819 1a1b 1c1d 1e1f 2021 2223
           0x0030:  2425 2627 2829 2a2b 2c2d 2e2f 3031 3233
    
    It seems we are not really ready to properly cope with this right now.
    
    We can probably do better in future kernels :
    vlan_get_ingress_priority() should be a netdev property instead of
    a per vlan_dev one.
    
    For stable kernels, lets clear vlan_tci to fix the bugs.
    Reported-by: default avatarSteinar H. Gunderson <sesse@google.com>
    Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
    Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
    d4b812de
vlan_core.c 9.12 KB