Merge branch 'netlink-nested-policy-validation'

Johannes Berg says:

====================
netlink: nested policy validation

This adds nested policy validation, which lets you specify the
nested attribute type, e.g. NLA_NESTED with sub-policy, or the
new NLA_NESTED_ARRAY with sub-sub-policy.

Changes in v2:
 * move setting the bad attr pointer/message into validate_nla()
 * remove the recursion patch since that's no longer needed
 * simply skip the generic bad attr pointer/message setting in
   case of nested nla_validate() failing since that could fail
   only due to validate_nla() failing inside, which already sets
   the extack information

Changes in v3:
 * fix NLA_REJECT to have an error message if none is in policy
====================

Signed-off-by: David S. Miller <davem@davemloft.net>