[RFC PATCH 8/8] KEYS: Verify the key identity in __keyctl_unlink

[David Howells]

This will show it:

	keyctl newring ring_a @s
	keyctl newring ring_b @s
	A=`keyctl add user A ss %:ring_a`
	B=`keyctl add user A qq %:ring_b`
	keyctl newring R @s
	keyctl show
	keyctl link $A %:R
	keyctl show
	keyctl link $B %:R
	keyctl show
	keyctl unlink $A %:R
	keyctl show  # R is now incorrectly empty

Reviewed-by: David Howells <dhowells at redhat.com>