Hi Serge,

On 11/06, Serge Hallyn wrote:
>
> Hi Oleg,
>
> commit 40a0d32d1eaffe6aac7324ca92604b6b3977eb0e :
> "fork: unify and tighten up CLONE_NEWUSER/CLONE_NEWPID checks"
> breaks lxc-attach in 3.12.  That code forks a child which does
> setns() and then does a clone(CLONE_PARENT).  That way the
> grandchild can be in the right namespaces (which the child was
> not) and be a child of the original task, which is the monitor.

Thanks...

Yes, this is what 40a0d32d1ea explicitly tries to disallow.

> Is there a real danger in allowing CLONE_PARENT
> when current->nsproxy->pidns_for_children is not our pidns,
> or was this done out of an "over-abundance of caution"?

I am not sure... This all was based on the long discussion, and
it was decided that the CLONE_PARENT check should be consistent
wrt CLONE_NEWPID and pidns_for_children != task_active_pid_ns().

> Can we
> safely revert that new extra check?

Well, usually we do not break user-space, but I am not sure about
this case...

Eric, Andy, what do you think?

And if we allow CLONE_PARENT when ->pidns_for_children was changed,
should we also allow, say, CLONE_NEWPID && CLONE_PARENT ?

Oleg.


------------------------------------------------------------------------------
November Webinars for C, C++, Fortran Developers
Accelerate application performance with scalable programming models. Explore
techniques for threading, error checking, porting, and tuning. Get the most 
from the latest Intel processors and coprocessors. See abstracts and register
http://pubads.g.doubleclick.net/gampad/clk?id=60136231&iu=/4140/ostg.clktrk
_______________________________________________
Lxc-devel mailing list
Lxc-devel@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/lxc-devel

Reply via email to