Smack:- Use overlay inode label in smack_inode_copy_up()

commit 387ef964

 upstream.

Currently in "smack_inode_copy_up()" function, process label is
changed with the label on parent inode. Due to which,
process is assigned directory label and whatever file or directory
created by the process are also getting directory label
which is wrong label.

Changes has been done to use label of overlay inode instead
of parent inode.

Signed-off-by: Vishal Goel <vishal.goel@samsung.com>
Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
[4.19: adjusted for the lack of helper functions]
Fixes: d6d80cb5

 ("Smack: Base support for overlayfs")
Signed-off-by: Munehisa Kamata <kamatam@amazon.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>