Re: [PATCH ghak90 V6 02/10] audit: add container id

Tycho Andersen
2019-05-29T14:57:49Z

On Mon, Apr 08, 2019 at 11:39:09PM -0400, Richard Guy Briggs wrote:
> It is not permitted to unset the audit container identifier.
> A child inherits its parent's audit container identifier.

...

> /**
> + * audit_set_contid - set current task's audit contid
> + * @contid: contid value
> + *
> + * Returns 0 on success, -EPERM on permission failure.
> + *
> + * Called (set) from fs/proc/base.c::proc_contid_write().
> + */
> +int audit_set_contid(struct task_struct *task, u64 contid)
> +{
> + u64 oldcontid;
> + int rc = 0;
> + struct audit_buffer *ab;
> + uid_t uid;
> + struct tty_struct *tty;
> + char comm[sizeof(current->comm)];
> +
> + task_lock(task);
> + /* Can't set if audit disabled */
> + if (!task->audit) {
> + task_unlock(task);
> + return -ENOPROTOOPT;
> + }
> + oldcontid = audit_get_contid(task);
> + read_lock(&tasklist_lock);
> + /* Don't allow the audit containerid to be unset */
> + if (!audit_contid_valid(contid))
> + rc = -EINVAL;
> + /* if we don't have caps, reject */
> + else if (!capable(CAP_AUDIT_CONTROL))
> + rc = -EPERM;
> + /* if task has children or is not single-threaded, deny */
> + else if (!list_empty(&task->children))
> + rc = -EBUSY;
> + else if (!(thread_group_leader(task) && thread_group_empty(task)))
> + rc = -EALREADY;
> + read_unlock(&tasklist_lock);
> + if (!rc)
> + task->audit->contid = contid;
> + task_unlock(task);
> +
> + if (!audit_enabled)
> + return rc;

...but it is allowed to change it (assuming
capable(CAP_AUDIT_CONTROL), of course)? Seems like this might be more
immediately useful since we still live in the world of majority
privileged containers if we didn't allow changing it, in addition to
un-setting it.

Tycho