route: add support for directed broadcast forwarding

This patch implements the feature described in rfc1812#section-5.3.5.2
and rfc2644. It allows the router to forward directed broadcast when
sysctl bc_forwarding is enabled.

Note that this feature could be done by iptables -j TEE, but it would
cause some problems:
- target TEE's gateway param has to be set with a specific address,
and it's not flexible especially when the route wants forward all
directed broadcasts.
- this duplicates the directed broadcasts so this may cause side
effects to applications.

Besides, to keep consistent with other os router like BSD, it's also
necessary to implement it in the route rx path.

Note that route cache needs to be flushed when bc_forwarding is
changed.

Signed-off-by: Xin Long <lucien.xin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

License cleanup: add SPDX license identifier to uapi header files with no license

Many user space API headers are missing licensing information, which
makes it hard for compliance tools to determine the correct license.

By default are files without license information under the default
license of the kernel, which is GPLV2. Marking them GPLV2 would exclude
them from being included in non GPLV2 code, which is obviously not
intended. The user space API headers fall under the syscall exception
which is in the kernels COPYING file:

NOTE! This copyright does *not* cover user programs that use kernel
services by normal system calls - this is merely considered normal use
of the kernel, and does *not* fall under the heading of "derived work".

otherwise syscall usage would not be possible.

Update the files which contain no license information with an SPDX
license identifier. The chosen identifier is 'GPL-2.0 WITH
Linux-syscall-note' which is the officially assigned identifier for the
Linux syscall exception. SPDX license identifiers are a legally binding
shorthand, which can be used instead of the full boiler plate text.

This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne. See the previous patch in this series for the
methodology of how this patch was researched.

Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

net: mpls: Add support for netconf

Add netconf support to MPLS. Allows userpsace to learn and be notified
of changes to 'input' enable setting per interface.

Acked-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Signed-off-by: David Ahern <dsa@cumulusnetworks.com>
Acked-by: Robert Shearman <rshearma@brocade.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

netconf: add macro to represent all attributes

This patch adds macro NETCONFA_ALL to represent all type of netconf
attributes for IPv4 and IPv6.

Signed-off-by: Zhang Shengju <zhangshengju@cmss.chinamobile.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

ipv4: add support for linkdown sysctl to netconf

This kernel patch exports the value of the new
ignore_routes_with_linkdown via netconf.

v2: changes to notify userspace via netlink when sysctl values change
and proposed for 'net' since this could be considered a bugfix

Signed-off-by: Andy Gospodarek <gospo@cumulusnetworks.com>
Suggested-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Acked-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

netconf: rename PROXY_ARP to NEIGH_PROXY

Use same field for both IPv4 (proxy_arp) and IPv6 (proxy_ndp)
so fix it before API is set to be a common name

Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
Acked-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

netconf: add proxy-arp support

Add support to netconf to show changes to proxy-arp status on a per
interface basis via netlink in a manner similar to forwarding
and reverse path state.

Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
Acked-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

netconf: advertise mc_forwarding status

This patch advertise the MC_FORWARDING status for IPv4 and IPv6.
This field is readonly, only multicast engine in the kernel updates it.

Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

rtnl/ipv4: use netconf msg to advertise rp_filter status

Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

rtnl: add a new type of msg to advertise protocol configuration

A new type is added to allow userland to monitor protocol configuration, like
IPv4 or IPv6.
For example, monitoring the state of the forwarding status of an interface of
the system.

Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Signed-off-by: David S. Miller <davem@davemloft.net>