apparmor: allow SYS_CAP_RESOURCE to be sufficient to prlimit another task
While using AppArmor, SYS_CAP_RESOURCE is insufficient to call prlimit
on another task. The only other example of a AppArmor mediating access to
another, already running, task (ignoring fork+exec) is ptrace.
The AppArmor model for ptrace is that one of the following must be true:
1) The tracer is unconfined
2) The tracer is in complain mode
3) The tracer and tracee are confined by the same profile
4) The tracer is confined but has SYS_CAP_PTRACE
1), 2, and 3) are already true for setrlimit.
We can match the ptrace model just by allowing CAP_SYS_RESOURCE.
We still test the values of the rlimit since it can always be overridden
using a value that means unlimited for a particular resource.
Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: John Johansen <john.johansen@canonical.com>
diff --git a/security/apparmor/resource.c b/security/apparmor/resource.c
index 748bf0c..67a6072 100644
--- a/security/apparmor/resource.c
+++ b/security/apparmor/resource.c
@@ -101,9 +101,11 @@
/* TODO: extend resource control to handle other (non current)
* profiles. AppArmor rules currently have the implicit assumption
* that the task is setting the resource of a task confined with
- * the same profile.
+ * the same profile or that the task setting the resource of another
+ * task has CAP_SYS_RESOURCE.
*/
- if (profile != task_profile ||
+ if ((profile != task_profile &&
+ aa_capable(profile, CAP_SYS_RESOURCE, 1)) ||
(profile->rlimits.mask & (1 << resource) &&
new_rlim->rlim_max > profile->rlimits.limits[resource].rlim_max))
error = -EACCES;