Packets arriving in a VRF currently are delivered to UDP sockets that aren't bound to any interface. TCP defaults to not delivering packets arriving in a VRF to unbound sockets. IP route lookup and socket transmit both assume that unbound means using the default table and UDP applications that haven't been changed to be aware of VRFs may not function correctly in this case since they may not be able to handle overlapping IP address ranges, or be able to send packets back to the original sender if required. So add a sysctl, udp_l3mdev_accept, to control this behaviour with it being analgous to the existing tcp_l3mdev_accept, namely to allow a process to have a VRF-global listen socket. Have this default to off as this is the behaviour that users will expect, given that there is no explicit mechanism to set unmodified VRF-unaware application into a default VRF. Signed-off-by: Robert Shearman <rshearma@brocade.com> Acked-by: David Ahern <dsa@cumulusnetworks.com> Tested-by: David Ahern <dsa@cumulusnetworks.com> Signed-off-by: David S. Miller <davem@davemloft.net>