Re: [PATCH 0/3] New system call, unshare

Janak Desai
2005-08-10T15:06:04Z

serue@us.ibm.com wrote:
> Quoting Florian Weimer (fw@deneb.enyo.de):
>
>>* Janak Desai:
>>
>>
>>>With unshare, namespace setup can be done using PAM session
>>>management functions without patching individual commands.
>>
>>I don't think it's a good idea to use security-critical code well
>
>
> Note that this patch is not removing the CAP_SYS_ADMIN requirement,
> just allowing the operation to happen outside of clone(). Unlike
> domain transitions in selinux, which should be tied to exec() so
> as to tie them to known code, I don't see what clone() would provide
> in terms of safety which we are losing.
>
>
>>without its original specification. Clearly the current situation
>>sucks, but this is mainly a lack of PAM functionality, IMHO.
>
>
> I'm not sure this is to do with PAM functionality, rather than
> just its design. Is there a way of "fixing" pam so that we don't
> need unshare()?
>

I have been trying to narrow down the problem since Alan's post
about using clone() instead of unshare. The problem comes down to
parent, on _exit(), clobbering controlling tty. I have tried, from
the child, to close and open the tty stored in PAM but that has
not helped.

-Janak