Re: [PATCH 2/2] taskstats: restrict access to user
From: Vasiliy Kulikov
Date: Wed Jun 29 2011 - 16:17:29 EST
On Wed, Jun 29, 2011 at 06:57 +0530, Balbir Singh wrote:
> On Fri, Jun 24, 2011 at 5:39 PM, Vasiliy Kulikov <segoon@xxxxxxxxxxxx> wrote:
> > + task = find_task_by_vpid(s->pid);
> > + if (!task || __task_cred(task)->euid != cred->euid) {
If consider this patch for inclusion, it also needs some check for
the listener root ability. __task_cred(task)->euid == 0 or smth like
that. But ptrace_task_may_access_current() is better.
> > + rcu_read_unlock();
> > + continue;
> > + }
> > + rcu_read_unlock();
> > +
>
> Release the lock prior to up_read()
>
> > skb_next = NULL;
> > if (!list_is_last(&s->list, &listeners->list)) {
> > skb_next = skb_clone(skb_cur, GFP_KERNEL);
> > @@ -199,14 +211,19 @@ static void fill_stats(struct task_struct *tsk, struct taskstats *stats)
> > static int fill_stats_for_pid(pid_t pid, struct taskstats *stats)
> > {
> > struct task_struct *tsk;
> > + int rc = -ESRCH;
> >
> > rcu_read_lock();
> > tsk = find_task_by_vpid(pid);
> > + if (tsk && !ptrace_may_access(tsk, PTRACE_MODE_READ)) {
> > + tsk = NULL;
> > + rc = -EACCES;
> > + }
> > if (tsk)
> > get_task_struct(tsk);
> > rcu_read_unlock();
> > if (!tsk)
> > - return -ESRCH;
> > + return rc;
> > fill_stats(tsk, stats);
> > put_task_struct(tsk);
> > return 0;
> > @@ -224,6 +241,10 @@ static int fill_stats_for_tgid(pid_t tgid, struct taskstats *stats)
> > */
> > rcu_read_lock();
> > first = find_task_by_vpid(tgid);
> > + if (first && !ptrace_may_access(first, PTRACE_MODE_READ)) {
> > + rc = -EACCES;
> > + goto out;
> > + }
> >
> > if (!first || !lock_task_sighand(first, &flags))
> > goto out;
>
> Balbir Singh
--
Vasiliy Kulikov
http://www.openwall.com - bringing security into open computing environments
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