Merge branch 'l3mdev-accept'

David Ahern says:

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net: Allow accepted sockets to be bound to l3mdev domain

Allow accepted sockets to derive their sk_bound_dev_if setting from the
l3mdev domain in which the packets originated. This version adds a sysctl
to control whether the setting is inherited, making the functionality
similar to sk_mark and its sysctl_tcp_fwmark_accept setting.

This effectively allow a process to have a "VRF-global" listen socket,
with child sockets bound to the VRF device in which the packet originated.
A similar behavior can be achieved using sk_mark, but a solution using marks
is incomplete as it does not handle duplicate addresses in different L3
domains/VRFs. Allowing sockets to inherit the sk_bound_dev_if from l3mdev
domain provides a complete solution.
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Signed-off-by: David S. Miller <davem@davemloft.net>