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>

kernel/ptrace.c

@@ -198,13 +198,12 @@ int __ptrace_may_access(struct task_struct *task, unsigned int mode)
 		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;

kernel/signal.c

@@ -767,11 +767,10 @@ static int kill_ok_by_cred(struct task_struct *t)
 	const struct cred *cred = current_cred();
 	const struct cred *tcred = __task_cred(t);
 
-	if (cred->user_ns == tcred->user_ns &&
-	    (cred->euid == tcred->suid ||
-	     cred->euid == tcred->uid ||
-	     cred->uid  == tcred->suid ||
-	     cred->uid  == tcred->uid))
+	if (uid_eq(cred->euid, tcred->suid) ||
+	    uid_eq(cred->euid, tcred->uid)  ||
+	    uid_eq(cred->uid,  tcred->suid) ||
+	    uid_eq(cred->uid,  tcred->uid))
 		return 1;
 
 	if (ns_capable(tcred->user_ns, CAP_KILL))
@@ -1389,10 +1388,8 @@ static int kill_as_cred_perm(const struct cred *cred,
 			     struct task_struct *target)
 {
 	const struct cred *pcred = __task_cred(target);
-	if (cred->user_ns != pcred->user_ns)
-		return 0;
-	if (cred->euid != pcred->suid && cred->euid != pcred->uid &&
-	    cred->uid  != pcred->suid && cred->uid  != pcred->uid)
+	if (!uid_eq(cred->euid, pcred->suid) && !uid_eq(cred->euid, pcred->uid) &&
+	    !uid_eq(cred->uid,  pcred->suid) && !uid_eq(cred->uid,  pcred->uid))
 		return 0;
 	return 1;
 }

kernel/sys.c

@@ -131,9 +131,8 @@ static bool set_one_prio_perm(struct task_struct *p)
 {
 	const struct cred *cred = current_cred(), *pcred = __task_cred(p);
 
-	if (pcred->user_ns == cred->user_ns &&
-	    (pcred->uid  == cred->euid ||
-	     pcred->euid == cred->euid))
+	if (uid_eq(pcred->uid,  cred->euid) ||
+	    uid_eq(pcred->euid, cred->euid))
 		return true;
 	if (ns_capable(pcred->user_ns, CAP_SYS_NICE))
 		return true;
@@ -1582,13 +1581,12 @@ static int check_prlimit_permission(struct task_struct *task)
 		return 0;
 
 	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))
 		return 0;
 	if (ns_capable(tcred->user_ns, CAP_SYS_RESOURCE))
 		return 0;