capabilites: introduce new has_ns_capabilities_noaudit

For consistency in interfaces, introduce a new interface called
has_ns_capabilities_noaudit.  It checks if the given task has the given
capability in the given namespace.  Use this new function by
has_capabilities_noaudit.

Signed-off-by: Eric Paris <eparis@redhat.com>
Acked-by: Serge E. Hallyn <serge.hallyn@canonical.com>

include/linux/capability.h

@@ -543,6 +543,8 @@ extern bool has_capability(struct task_struct *t, int cap);
 extern bool has_ns_capability(struct task_struct *t,
 			      struct user_namespace *ns, int cap);
 extern bool has_capability_noaudit(struct task_struct *t, int cap);
+extern bool has_ns_capability_noaudit(struct task_struct *t,
+				      struct user_namespace *ns, int cap);
 extern bool capable(int cap);
 extern bool ns_capable(struct user_namespace *ns, int cap);
 extern bool task_ns_capable(struct task_struct *t, int cap);

kernel/capability.c

@@ -325,7 +325,33 @@ bool has_capability(struct task_struct *t, int cap)
 }
 
 /**
- * has_capability_noaudit - Does a task have a capability (unaudited)
+ * has_ns_capability_noaudit - Does a task have a capability (unaudited)
+ * in a specific user ns.
+ * @t: The task in question
+ * @ns: target user namespace
+ * @cap: The capability to be tested for
+ *
+ * Return true if the specified task has the given superior capability
+ * currently in effect to the specified user namespace, false if not.
+ * Do not write an audit message for the check.
+ *
+ * Note that this does not set PF_SUPERPRIV on the task.
+ */
+bool has_ns_capability_noaudit(struct task_struct *t,
+			       struct user_namespace *ns, int cap)
+{
+	int ret;
+
+	rcu_read_lock();
+	ret = security_capable_noaudit(__task_cred(t), ns, cap);
+	rcu_read_unlock();
+
+	return (ret == 0);
+}
+
+/**
+ * has_capability_noaudit - Does a task have a capability (unaudited) in the
+ * initial user ns
  * @t: The task in question
  * @cap: The capability to be tested for
  *
@@ -337,13 +363,7 @@ bool has_capability(struct task_struct *t, int cap)
  */
 bool has_capability_noaudit(struct task_struct *t, int cap)
 {
-	int ret;
-
-	rcu_read_lock();
-	ret = security_capable_noaudit(__task_cred(t), &init_user_ns, cap);
-	rcu_read_unlock();
-
-	return (ret == 0);
+	return has_ns_capability_noaudit(t, &init_user_ns, cap);
 }
 
 /**