On 13/12/30, Oleg Nesterov wrote:
> On 12/23, Richard Guy Briggs wrote:
> >
> > Store and log all PIDs with reference to the initial PID namespace and
> > use the access functions task_pid_nr() and task_tgid_nr() for task->pid
> > and task->tgid rather than access them directly.
>
> At first glance this patch looks like a good cleanup, but...
>
> > @@ -429,6 +429,19 @@ static struct audit_entry *audit_data_to_entry(struct
> > audit_rule_data *data,
> > f->val = 0;
> > }
> >
> > + if ((f->type == AUDIT_PID) || (f->type == AUDIT_PPID)) {
> > + struct pid *pid;
> > + rcu_read_lock();
> > + pid = find_vpid(f->val);
> > + if (!pid) {
> > + rcu_read_unlock();
> > + err = -ESRCH;
> > + goto exit_free;
> > + }
> > + f->val = pid_nr(pid);
> > + rcu_read_unlock();
> > + }
>
> I do not really understand this change, but this doesn't matter, I do
> not understand audit.
Is this pid_t handed down from userspace a valid pid_t in its
namespace? If not, generate an error. If it is, store its global
pid_t for future comparisons. It might be better to store a struct
task_struct * or a struct pid *, but then the comparison functions would
have to change too, along with the rule reporting functions, which still
report pid_t to userspace.
> However, I think this deserves a separate patch with the changelog.
All *that* would need a seperate patch...
> > @@ -278,9 +278,12 @@ static void dump_common_audit_data(struct audit_buffer
> > *ab,
> > }
> > case LSM_AUDIT_DATA_TASK:
> > tsk = a->u.tsk;
> > - if (tsk && tsk->pid) {
> > - audit_log_format(ab, " pid=%d comm=", tsk->pid);
> > - audit_log_untrustedstring(ab, tsk->comm);
> > + if (tsk) {
> > + pid_t pid = task_pid_nr(tsk);
> > + if (pid) {
> > + audit_log_format(ab, " pid=%d comm=", pid);
> > + audit_log_untrustedstring(ab, tsk->comm);
>
> Just curious, is it really possible that a->u.tsk is an idle thread?
No. It is possible a->u.tsk isn't filled in.
> Oleg.
- RGB
--
Richard Guy Briggs <rbri...@redhat.com>
Senior Software Engineer, Kernel Security, AMER ENG Base Operating Systems, Red
Hat
Remote, Ottawa, Canada
Voice: +1.647.777.2635, Internal: (81) 32635, Alt: +1.613.693.0684x3545
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