AppArmor: Fix security_task_setrlimit logic for 2.6.36 changes

2.6.36 introduced the abilitiy to specify the task that is having its
rlimits set.  Update mediation to ensure that confined tasks can only
set their own group_leader as expected by current policy.

Add TODO note about extending policy to support setting other tasks
rlimits.

Signed-off-by: John Johansen <john.johansen@canonical.com>
Signed-off-by: James Morris <jmorris@namei.org>

3 files changed, 15 insertions, 11 deletions

diff --git a/security/apparmor/include/resource.h b/security/apparmor/include/resource.h
index 3c88be946494..02baec732bb5 100644
--- a/security/apparmor/include/resource.h
+++ b/security/apparmor/include/resource.h
@@ -33,8 +33,8 @@ struct aa_rlimit {
 };
 
 int aa_map_resource(int resource);
-int aa_task_setrlimit(struct aa_profile *profile, unsigned int resource,
-                      struct rlimit *new_rlim);
+int aa_task_setrlimit(struct aa_profile *profile, struct task_struct *,
+                      unsigned int resource, struct rlimit *new_rlim);
 
 void __aa_transition_rlimits(struct aa_profile *old, struct aa_profile *new);
 
diff --git a/security/apparmor/lsm.c b/security/apparmor/lsm.c
index f73e2c204218..cf1de4462ccd 100644
--- a/security/apparmor/lsm.c
+++ b/security/apparmor/lsm.c
@@ -614,7 +614,7 @@ static int apparmor_task_setrlimit(struct task_struct *task,
         int error = 0;
 
         if (!unconfined(profile))
-                error = aa_task_setrlimit(profile, resource, new_rlim);
+                error = aa_task_setrlimit(profile, task, resource, new_rlim);
 
         return error;
 }
diff --git a/security/apparmor/resource.c b/security/apparmor/resource.c
index 4a368f1fd36d..a4136c10b1c6 100644
--- a/security/apparmor/resource.c
+++ b/security/apparmor/resource.c
@@ -72,6 +72,7 @@ int aa_map_resource(int resource)
 /**
  * aa_task_setrlimit - test permission to set an rlimit
  * @profile - profile confining the task  (NOT NULL)
+ * @task - task the resource is being set on
  * @resource - the resource being set
  * @new_rlim - the new resource limit  (NOT NULL)
  *
@@ -79,18 +80,21 @@ int aa_map_resource(int resource)
  *
  * Returns: 0 or error code if setting resource failed
  */
-int aa_task_setrlimit(struct aa_profile *profile, unsigned int resource,
-                      struct rlimit *new_rlim)
+int aa_task_setrlimit(struct aa_profile *profile, struct task_struct *task,
+                      unsigned int resource, struct rlimit *new_rlim)
 {
         int error = 0;
 
-        if (profile->rlimits.mask & (1 << resource) &&
-            new_rlim->rlim_max > profile->rlimits.limits[resource].rlim_max)
-
-                error = audit_resource(profile, resource, new_rlim->rlim_max,
-                        -EACCES);
+        /* 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
+         */
+        if ((task != current->group_leader) ||
+            (profile->rlimits.mask & (1 << resource) &&
+             new_rlim->rlim_max > profile->rlimits.limits[resource].rlim_max))
+                error = -EACCES;
 
-        return error;
+        return audit_resource(profile, resource, new_rlim->rlim_max, error);
 }
 
 /**