Re: 2.4+ptrace exploit fix breaks root's ability to strace

[Yusuf Wilajati Purna <purna@sm.sony.co.jp>]

Hi,

On 2003-03-22 17:28:54, Arjan van de Ven wrote:
>On Sat, Mar 22, 2003 at 05:13:12PM +0000, Russell King wrote:
>> 
>> int ptrace_check_attach(struct task_struct *child, int kill)
>> {
>> 	...
>> +       if (!is_dumpable(child))
>> +               return -EPERM;
>> }
>> 
>> So, we went from being able to ptrace daemons as root, to being able to
>> attach daemons and then being unable to do anything with them, even if
>> you're root (or have the CAP_SYS_PTRACE capability).  I think this
>> behaviour is getting on for being described as "insane" 8) and is
>> clearly wrong.
>
>ok it seems this check is too strong. It *has* to check
>child->task_dumpable and return -EPERM, but child->mm->dumpable is not
>needed.

So, do you mean that the following is enough:

int ptrace_check_attach(struct task_struct *child, int kill)
{
      ...
+       if (!child->task_dumpable)
+               return -EPERM;
}

Regards,

Purna