Re: [RESEND PATCH] prctl: add PR_[GS]ET_PDEATHSIG_PROC

[Jürg Billeter]

On Tue, 2017-10-03 at 12:40 -0500, Eric W. Biederman wrote:
> JÃrg Billeter <j@xxxxxxxxx> writes:
> > What's actually the reason that CLONE_NEWPID requires CAP_SYS_ADMIN? 
> > Does CLONE_NEWPID pose any risks that don't exist for
> > CLONE_NEWUSER|CLONE_NEWPID?  Assuming we can't simply drop the
> > CAP_SYS_ADMIN requirement, do you see a better solution for this use
> > case?
> 
> CLONE_NEWPID without a permission check would allow runing a setuid root
> application in a pid namespace.  Off the top of my head I can't think of
> a really good exploit.  But when you mess up pid files, and hide
> information from a privileged application I can completely imagine
> forcing that application to misbehave in ways the attacker can control.
> Leading to bad things.

Could we allow unprivileged CLONE_NEWPID if the no_new_privs bit is
set?

JÃrg