On Thu, Jan 23, 2020 at 4:03 PM Richard Guy Briggs [off-list ref] wrote:

On 2020-01-22 16:29, Paul Moore wrote:

quoted

On Tue, Dec 31, 2019 at 2:51 PM Richard Guy Briggs [off-list ref] wrote:

quoted

Require the target task to be a descendant of the container
orchestrator/engine.

You would only change the audit container ID from one set or inherited
value to another if you were nesting containers.

If changing the contid, the container orchestrator/engine must be a
descendant and not same orchestrator as the one that set it so it is not
possible to change the contid of another orchestrator's container.

Since the task_is_descendant() function is used in YAMA and in audit,
remove the duplication and pull the function into kernel/core/sched.c

Signed-off-by: Richard Guy Briggs <redacted>
---
 include/linux/sched.h    |  3 +++
 kernel/audit.c           | 44 ++++++++++++++++++++++++++++++++++++--------
 kernel/sched/core.c      | 33 +++++++++++++++++++++++++++++++++
 security/yama/yama_lsm.c | 33 ---------------------------------
 4 files changed, 72 insertions(+), 41 deletions(-)

...

quoted

diff --git a/kernel/audit.c b/kernel/audit.c
index f7a8d3288ca0..ef8e07524c46 100644
--- a/kernel/audit.c
+++ b/kernel/audit.c

@@ -2603,22 +2610,43 @@ int audit_set_contid(struct task_struct *task, u64 contid)
        oldcontid = audit_get_contid(task);
        read_lock(&tasklist_lock);
        /* Don't allow the contid to be unset */
-       if (!audit_contid_valid(contid))
+       if (!audit_contid_valid(contid)) {
                rc = -EINVAL;
+               goto unlock;
+       }
        /* Don't allow the contid to be set to the same value again */
-       else if (contid == oldcontid) {
+       if (contid == oldcontid) {
                rc = -EADDRINUSE;
+               goto unlock;
+       }
        /* if we don't have caps, reject */
-       else if (!capable(CAP_AUDIT_CONTROL))
+       if (!capable(CAP_AUDIT_CONTROL)) {
                rc = -EPERM;
-       /* if task has children or is not single-threaded, deny */
-       else if (!list_empty(&task->children))
+               goto unlock;
+       }
+       /* if task has children, deny */
+       if (!list_empty(&task->children)) {
                rc = -EBUSY;
-       else if (!(thread_group_leader(task) && thread_group_empty(task)))
+               goto unlock;
+       }
+       /* if task is not single-threaded, deny */
+       if (!(thread_group_leader(task) && thread_group_empty(task))) {
                rc = -EALREADY;
-       /* if contid is already set, deny */
-       else if (audit_contid_set(task))
+               goto unlock;
+       }

It seems like the if/else-if conversion above should be part of an
earlier patchset.

I had considered that, but it wasn't obvious where that conversion
should happen since it wasn't necessary earlier and is now.  I can move
it earlier if you feel strongly about it.

Not particularly.

-- 
paul moore
www.paul-moore.com