apparmor: add utility function to get an arbitrary tasks profile.

Signed-off-by: John Johansen <john.johansen@canonical.com>
Acked-by: Steve Beattie <sbeattie@ubuntu.com>

security/apparmor/context.c

@@ -68,6 +68,23 @@ void aa_dup_task_context(struct aa_task_cxt *new, const struct aa_task_cxt *old)
 	aa_get_profile(new->onexec);
 }
 
+/**
+ * aa_get_task_profile - Get another task's profile
+ * @task: task to query  (NOT NULL)
+ *
+ * Returns: counted reference to @task's profile
+ */
+struct aa_profile *aa_get_task_profile(struct task_struct *task)
+{
+	struct aa_profile *p;
+
+	rcu_read_lock();
+	p = aa_get_profile(__aa_task_profile(task));
+	rcu_read_unlock();
+
+	return p;
+}
+
 /**
  * aa_replace_current_profile - replace the current tasks profiles
  * @profile: new profile  (NOT NULL)

security/apparmor/domain.c

@@ -62,17 +62,14 @@ static int may_change_ptraced_domain(struct task_struct *task,
 				     struct aa_profile *to_profile)
 {
 	struct task_struct *tracer;
-	const struct cred *cred = NULL;
 	struct aa_profile *tracerp = NULL;
 	int error = 0;
 
 	rcu_read_lock();
 	tracer = ptrace_parent(task);
-	if (tracer) {
+	if (tracer)
 		/* released below */
-		cred = get_task_cred(tracer);
+		tracerp = aa_get_task_profile(tracer);
-		tracerp = aa_cred_profile(cred);
-	}
 
 	/* not ptraced */
 	if (!tracer || unconfined(tracerp))
@@ -82,8 +79,7 @@ static int may_change_ptraced_domain(struct task_struct *task,
 
 out:
 	rcu_read_unlock();
-	if (cred)
+	aa_put_profile(tracerp);
-		put_cred(cred);
 
 	return error;
 }

security/apparmor/include/context.h

@@ -80,23 +80,8 @@ int aa_replace_current_profile(struct aa_profile *profile);
 int aa_set_current_onexec(struct aa_profile *profile);
 int aa_set_current_hat(struct aa_profile *profile, u64 token);
 int aa_restore_previous_profile(u64 cookie);
+struct aa_profile *aa_get_task_profile(struct task_struct *task);
 
-/**
- * __aa_task_is_confined - determine if @task has any confinement
- * @task: task to check confinement of  (NOT NULL)
- *
- * If @task != current needs to be called in RCU safe critical section
- */
-static inline bool __aa_task_is_confined(struct task_struct *task)
-{
-	struct aa_task_cxt *cxt = __task_cred(task)->security;
-
-	BUG_ON(!cxt || !cxt->profile);
-	if (unconfined(aa_newest_version(cxt->profile)))
-		return 0;
-
-	return 1;
-}
 
 /**
  * aa_cred_profile - obtain cred's profiles
@@ -113,6 +98,30 @@ static inline struct aa_profile *aa_cred_profile(const struct cred *cred)
 	return aa_newest_version(cxt->profile);
 }
 
+/**
+ * __aa_task_profile - retrieve another task's profile
+ * @task: task to query  (NOT NULL)
+ *
+ * Returns: @task's profile without incrementing its ref count
+ *
+ * If @task != current needs to be called in RCU safe critical section
+ */
+static inline struct aa_profile *__aa_task_profile(struct task_struct *task)
+{
+	return aa_cred_profile(__task_cred(task));
+}
+
+/**
+ * __aa_task_is_confined - determine if @task has any confinement
+ * @task: task to check confinement of  (NOT NULL)
+ *
+ * If @task != current needs to be called in RCU safe critical section
+ */
+static inline bool __aa_task_is_confined(struct task_struct *task)
+{
+	return !unconfined(__aa_task_profile(task));
+}
+
 /**
  * __aa_current_profile - find the current tasks confining profile
  *

security/apparmor/ipc.c

@@ -95,23 +95,18 @@ int aa_ptrace(struct task_struct *tracer, struct task_struct *tracee,
 	 *       - tracer profile has CAP_SYS_PTRACE
 	 */
 
-	struct aa_profile *tracer_p;
+	struct aa_profile *tracer_p = aa_get_task_profile(tracer);
-	/* cred released below */
-	const struct cred *cred = get_task_cred(tracer);
 	int error = 0;
-	tracer_p = aa_cred_profile(cred);
 
 	if (!unconfined(tracer_p)) {
-		/* lcred released below */
+		struct aa_profile *tracee_p = aa_get_task_profile(tracee);
-		const struct cred *lcred = get_task_cred(tracee);
-		struct aa_profile *tracee_p = aa_cred_profile(lcred);
 
 		error = aa_may_ptrace(tracer, tracer_p, tracee_p, mode);
 		error = aa_audit_ptrace(tracer_p, tracee_p, error);
 
-		put_cred(lcred);
+		aa_put_profile(tracee_p);
 	}
-	put_cred(cred);
+	aa_put_profile(tracer_p);
 
 	return error;
 }