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 overriden using a value that means unlimited for a particular resource. Signed-off-by: Jeff Mahoney <[email protected]> --- security/apparmor/resource.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) --- a/security/apparmor/resource.c +++ b/security/apparmor/resource.c @@ -101,9 +101,11 @@ int aa_task_setrlimit(struct aa_profile /* 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(current, profile, CAP_SYS_RESOURCE, 1)) || (profile->rlimits.mask & (1 << resource) && new_rlim->rlim_max > profile->rlimits.limits[resource].rlim_max)) error = -EACCES; -- Jeff Mahoney SUSE Labs -- AppArmor mailing list [email protected] Modify settings or unsubscribe at: https://lists.ubuntu.com/mailman/listinfo/apparmor
