Re: [PATCH 2/2] exit_notify: kill the wrong capable(CAP_KILL) check

Serge E. Hallyn
2009-02-25T22:44:50Z

Quoting Oleg Nesterov (oleg@redhat.com):
> On 02/25, Serge E. Hallyn wrote:
> >
> > Quoting Oleg Nesterov (oleg@redhat.com):
> > > On 02/25, Serge E. Hallyn wrote:
> > > Can't understand... Why do you think CAP_KILL makes things better?
> > >
> > > Actually, how can it make any difference in this case?
> >
> > Well the check by itself isn't quite right - it seems to me it
> > should also check whether tsk->euid == parent->uid. But letting
> > an unprivileged task send SIGSTOP to a privileged one bc of
> > some fluke in the task hierarchy doesn't seem right.
>
> I think you misread this CAP_KILL check.
>
> It does not restrict the unprivileged task to send the signal. Instead,
> if the exiting task has CAP_KILL, we bypass other security checks.

? If the exiting task does not have CAP_KILL, we set the signal to
SIGCHILD (which is deemed safe).

Or, I'm completely misreading...

-serge