• David Ahern's avatar
    net: ipv6: Allow shorthand delete of all nexthops in multipath route · 0ae81335
    David Ahern authored
    IPv4 allows multipath routes to be deleted using just the prefix and
    length. For example:
        $ ip ro ls vrf red
        unreachable default metric 8192
        1.1.1.0/24
            nexthop via 10.100.1.254  dev eth1 weight 1
            nexthop via 10.11.200.2  dev eth11.200 weight 1
        10.11.200.0/24 dev eth11.200 proto kernel scope link src 10.11.200.3
        10.100.1.0/24 dev eth1 proto kernel scope link src 10.100.1.3
    
        $ ip ro del 1.1.1.0/24 vrf red
    
        $ ip ro ls vrf red
        unreachable default metric 8192
        10.11.200.0/24 dev eth11.200 proto kernel scope link src 10.11.200.3
        10.100.1.0/24 dev eth1 proto kernel scope link src 10.100.1.3
    
    The same notation does not work with IPv6 because of how multipath routes
    are implemented for IPv6. For IPv6 only the first nexthop of a multipath
    route is deleted if the request contains only a prefix and length. This
    leads to unnecessary complexity in userspace dealing with IPv6 multipath
    routes.
    
    This patch allows all nexthops to be deleted without specifying each one
    in the delete request. Internally, this is done by walking the sibling
    list of the route matching the specifications given (prefix, length,
    metric, protocol, etc).
    
        $  ip -6 ro ls vrf red
        2001:db8:1::/120 dev eth1 proto kernel metric 256  pref medium
        2001:db8:2::/120 dev eth2 proto kernel metric 256  pref medium
        2001:db8:200::/120 via 2001:db8:1::2 dev eth1 metric 1024  pref medium
        2001:db8:200::/120 via 2001:db8:2::2 dev eth2 metric 1024  pref medium
        ...
    
        $ ip -6 ro del vrf red 2001:db8:200::/120
    
        $ ip -6 ro ls vrf red
        2001:db8:1::/120 dev eth1 proto kernel metric 256  pref medium
        2001:db8:2::/120 dev eth2 proto kernel metric 256  pref medium
        ...
    
    Because IPv6 allows individual nexthops to be deleted without deleting
    the entire route, the ip6_route_multipath_del and non-multipath code
    path (ip6_route_del) have to be discriminated so that all nexthops are
    only deleted for the latter case. This is done by making the existing
    fc_type in fib6_config a u16 and then adding a new u16 field with
    fc_delete_all_nh as the first bit.
    Suggested-by: default avatarDinesh Dutt <ddutt@cumulusnetworks.com>
    Signed-off-by: default avatarDavid Ahern <dsa@cumulusnetworks.com>
    Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
    0ae81335
ip6_fib.h 6.84 KB