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apparmor: allow SYS_CAP_RESOURCE to be sufficient to prlimit another task

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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>
This commit is contained in:
Jeff Mahoney 2015-11-06 15:17:30 -05:00 committed by John Johansen
parent 38dbd7d8be
commit ff118479a7
1 changed files with 4 additions and 2 deletions
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6
security/apparmor/resource.c
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@ -101,9 +101,11 @@ int aa_task_setrlimit(struct aa_profile *profile, struct task_struct *task,
/* 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;