net: ipv6: Add IPv6 support to the ping socket.

[backport of net-next 6d0bfe22611602f36617bc7aa2ffa1bbb2f54c67]

This adds the ability to send ICMPv6 echo requests without a
raw socket. The equivalent ability for ICMPv4 was added in
2011.

Instead of having separate code paths for IPv4 and IPv6, make
most of the code in net/ipv4/ping.c dual-stack and only add a
few IPv6-specific bits (like the protocol definition) to a new
net/ipv6/ping.c. Hopefully this will reduce divergence and/or
duplication of bugs in the future.

Caveats:

- Setting options via ancillary data (e.g., using IPV6_PKTINFO
  to specify the outgoing interface) is not yet supported.
- There are no separate security settings for IPv4 and IPv6;
  everything is controlled by /proc/net/ipv4/ping_group_range.
- The proc interface does not yet display IPv6 ping sockets
  properly.

Tested with a patched copy of ping6 and using raw socket calls.
Compiles and works with all of CONFIG_IPV6={n,m,y}.

Change-Id: Ia359af556021344fc7f890c21383aadf950b6498
Signed-off-by: Lorenzo Colitti <lorenzo@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
[lorenzo@google.com: backported to 3.0]
Signed-off-by: Lorenzo Colitti <lorenzo@google.com>
Signed-off-by: zwliew <zhaoweiliew@gmail.com>
ping: always initialize ->sin6_scope_id and ->sin6_flowinfo

[net-next commit c26d6b46da3ee86fa8a864347331e5513ca84c2b]

If we don't need scope id, we should initialize it to zero.
Same for ->sin6_flowinfo.

Change-Id: I28e4bc9593e76fc3434052182466fab4bb8ccf3a
Cc: Lorenzo Colitti <lorenzo@google.com>
Cc: David S. Miller <davem@davemloft.net>
Signed-off-by: Cong Wang <amwang@redhat.com>
Acked-by: Lorenzo Colitti <lorenzo@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: zwliew <zhaoweiliew@gmail.com>
net: ipv6: add missing lock in ping_v6_sendmsg

[net-next commit a1bdc45580fc19e968b32ad27cd7e476a4aa58f6]

Bug: 9469865
Change-Id: I480f8ce95956dd8f17fbbb26dc60cc162f8ec933
Signed-off-by: Lorenzo Colitti <lorenzo@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: zwliew <zhaoweiliew@gmail.com>