userns: Convert ptrace, kill, set_priority permission checks to work with kuids and kgids

Update the permission checks to use the new uid_eq and gid_eq helpers
and remove the now unnecessary user_ns equality comparison.

Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index 24e0a5a..a232bb5 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -198,13 +198,12 @@
 		return 0;
 	rcu_read_lock();
 	tcred = __task_cred(task);
-	if (cred->user_ns == tcred->user_ns &&
-	    (cred->uid == tcred->euid &&
-	     cred->uid == tcred->suid &&
-	     cred->uid == tcred->uid  &&
-	     cred->gid == tcred->egid &&
-	     cred->gid == tcred->sgid &&
-	     cred->gid == tcred->gid))
+	if (uid_eq(cred->uid, tcred->euid) &&
+	    uid_eq(cred->uid, tcred->suid) &&
+	    uid_eq(cred->uid, tcred->uid)  &&
+	    gid_eq(cred->gid, tcred->egid) &&
+	    gid_eq(cred->gid, tcred->sgid) &&
+	    gid_eq(cred->gid, tcred->gid))
 		goto ok;
 	if (ptrace_has_cap(tcred->user_ns, mode))
 		goto ok;