apparmor: relax the restrictions on setting rlimits

Instead of limiting the setting of the processes limits to current,
relax this to tasks confined by the same profile, as the apparmor
controls for rlimits are at a profile level granularity.
Signed-off-by: John Johansen <john.johansen@canonical.com>
Acked-by: Steve Beattie <sbeattie@ubuntu.com>

security/apparmor/resource.c

@@ -15,6 +15,7 @@
 #include <linux/audit.h>
 
 #include "include/audit.h"
+#include "include/context.h"
 #include "include/resource.h"
 #include "include/policy.h"
 
@@ -90,17 +91,25 @@ int aa_map_resource(int resource)
 int aa_task_setrlimit(struct aa_profile *profile, struct task_struct *task,
 		      unsigned int resource, struct rlimit *new_rlim)
 {
+	struct aa_profile *task_profile;
 	int error = 0;
 
+	rcu_read_lock();
+	task_profile = aa_get_profile(aa_cred_profile(__task_cred(task)));
+	rcu_read_unlock();
+
 	/* TODO: extend resource control to handle other (non current)
-	 * processes.  AppArmor rules currently have the implicit assumption
-	 * that the task is setting the resource of the current process
+	 * profiles.  AppArmor rules currently have the implicit assumption
+	 * that the task is setting the resource of a task confined with
+	 * the same profile.
 	 */
-	if ((task != current->group_leader) ||
+	if (profile != task_profile ||
 	    (profile->rlimits.mask & (1 << resource) &&
 	     new_rlim->rlim_max > profile->rlimits.limits[resource].rlim_max))
 		error = -EACCES;
 
+	aa_put_profile(task_profile);
+
 	return audit_resource(profile, resource, new_rlim->rlim_max, error);
 }