[RFC,ghak32,V2,02/13] audit: check children and threading before allowing containerid

Submitted by Richard Guy Briggs on March 16, 2018, 9 a.m.

Details

Message ID 995b77557010b2f9aed0e10435f7b8536df7a5db.1521179281.git.rgb@redhat.com
State New
Series "audit: implement container id"
Headers show

Commit Message

Richard Guy Briggs March 16, 2018, 9 a.m.
Check if a task has existing children or co-threads and refuse to set
the container ID if either are present.  Failure to check this could
permit games where a child scratches its parent's back to work around
inheritance and double-setting policy.

Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
---
 kernel/auditsc.c | 4 ++++
 1 file changed, 4 insertions(+)

Patch hide | download patch | download mbox

diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index 29c8482..a6b0a52 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -2087,6 +2087,10 @@  static int audit_set_containerid_perm(struct task_struct *task, u64 containerid)
 	/* if we don't have caps, reject */
 	if (!capable(CAP_AUDIT_CONTROL))
 		return -EPERM;
+	/* if task has children or is not single-threaded, deny */
+	if (!list_empty(&task->children) ||
+	    !(thread_group_leader(task) && thread_group_empty(task)))
+		return -EPERM;
 	/* if containerid is unset, allow */
 	if (!audit_containerid_set(task))
 		return 0;

Comments

Paul Moore April 19, 2018, 12:11 a.m.
On Fri, Mar 16, 2018 at 5:00 AM, Richard Guy Briggs <rgb@redhat.com> wrote:
> Check if a task has existing children or co-threads and refuse to set
> the container ID if either are present.  Failure to check this could
> permit games where a child scratches its parent's back to work around
> inheritance and double-setting policy.
>
> Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
> ---
>  kernel/auditsc.c | 4 ++++
>  1 file changed, 4 insertions(+)

I would just include this in patch 1/2 as I can't think of world where
we wouldn't this check.

> diff --git a/kernel/auditsc.c b/kernel/auditsc.c
> index 29c8482..a6b0a52 100644
> --- a/kernel/auditsc.c
> +++ b/kernel/auditsc.c
> @@ -2087,6 +2087,10 @@ static int audit_set_containerid_perm(struct task_struct *task, u64 containerid)
>         /* if we don't have caps, reject */
>         if (!capable(CAP_AUDIT_CONTROL))
>                 return -EPERM;
> +       /* if task has children or is not single-threaded, deny */
> +       if (!list_empty(&task->children) ||
> +           !(thread_group_leader(task) && thread_group_empty(task)))
> +               return -EPERM;
>         /* if containerid is unset, allow */
>         if (!audit_containerid_set(task))
>                 return 0;
> --
> 1.8.3.1