CVE-2016-10318 missing authorization check fscrypt_process_policy

CVE-2016-10318 missing authorization check fscrypt_process_policy

Port to UEK4 of mainline commit id 163ae1c6ad62.

On an ext4 or f2fs filesystem with file encryption supported, a user
could set an encryption policy on any empty directory(*) to which they
had readonly access.  This is obviously problematic, since such a
directory might be owned by another user and the new encryption policy
would prevent that other user from creating files in their own directory
(for example).

Fix this by requiring inode_owner_or_capable() permission to set an
encryption policy.  This means that either the caller must own the file,
or the caller must have the capability CAP_FOWNER.

(*) Or also on any regular file, for f2fs v4.6 and later and ext4
    v4.8-rc1 and later; a separate bug fix is coming for that.

Orabug: 25883175
Signed-off-by: Jack Vogel <jack.vogel@oracle.com>
Acked-by: Håkon Bugge <haakon.bugge@oracle.com>
Reviewed-by: Ethan Zhao <ethan.zhao@oracle.com>
Signed-off-by: Dhaval Giani <dhaval.giani@oracle.com>