• Mathieu Desnoyers's avatar
    ipv6/icmp: l3mdev: Perform icmp error route lookup on source device routing table (v2) · 272928d1
    Mathieu Desnoyers authored
    As per RFC4443, the destination address field for ICMPv6 error messages
    is copied from the source address field of the invoking packet.
    
    In configurations with Virtual Routing and Forwarding tables, looking up
    which routing table to use for sending ICMPv6 error messages is
    currently done by using the destination net_device.
    
    If the source and destination interfaces are within separate VRFs, or
    one in the global routing table and the other in a VRF, looking up the
    source address of the invoking packet in the destination interface's
    routing table will fail if the destination interface's routing table
    contains no route to the invoking packet's source address.
    
    One observable effect of this issue is that traceroute6 does not work in
    the following cases:
    
    - Route leaking between global routing table and VRF
    - Route leaking between VRFs
    
    Use the source device routing table when sending ICMPv6 error
    messages.
    
    [ In the context of ipv4, it has been pointed out that a similar issue
      may exist with ICMP errors triggered when forwarding between network
      namespaces. It would be worthwhile to investigate whether ipv6 has
      similar issues, but is outside of the scope of this investigation. ]
    
    [ Testing shows that similar issues exist with ipv6 unreachable /
      fragmentation needed messages.  However, investigation of this
      additional failure mode is beyond this investigation's scope. ]
    
    Link: https://tools.ietf.org/html/rfc4443Signed-off-by: default avatarMathieu Desnoyers <mathieu.desnoyers@efficios.com>
    Reviewed-by: default avatarDavid Ahern <dsahern@gmail.com>
    Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
    272928d1
ip6_output.c 49.8 KB