Revert "evm: Translate user/group ids relative to s_user_ns when computing HMAC"

commit 19339c251607a3defc7f089511ce8561936fee45 upstream.

This reverts commit 0b3c9761.

Seth Forshee <seth.forshee@canonical.com> writes:
> All right, I think 0b3c9761 should be
> reverted then. EVM is a machine-local integrity mechanism, and so it
> makes sense that the signature would be based on the kernel's notion of
> the uid and not the filesystem's.

I added a commment explaining why the EVM hmac needs to be in the
kernel's notion of uid and gid, not the filesystems to prevent
remounting the filesystem and gaining unwaranted trust in files.

Acked-by: Seth Forshee <seth.forshee@canonical.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Aditya Kali <adityakali@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>