Re: sys_chroot+sys_fchdir Fix

[David Newall <david@davidnewall.com>]

Serge E. Hallyn wrote:
> Quoting David Newall (david@davidnewall.com):
>   
> > Serge E. Hallyn wrote:
> >     
> > > Quoting David Newall (david@davidnewall.com):
> > >   
> > >       
> > > > It might be tidy if pivot_root could be used (instead of a hack based on 
> > > > a chroot bug), but it'd still be unportable.
> > > >     
> > > >         
> > > It can.
> > >
> > > Please re-read my previous msg.
> > >       
> > I read it.  Currently pivot_root can't be used to affect a single process.  
> >     
> No.  If you unshare your mounts namespace immediately before pivot_root,
> then pivot_root will only affect that single process.
>   
Bugger.  You're right, I didn't read your previous message; I thought I 
had but I was wrong.
> > 	unshare(CLONE_NEWNS);
> > 	chdir(new_dir);
> > 	pivot_root(new_dir, oldroot);

After further RTFMing, and assuming "any processes or threads which  
use  the  old  root directory" means what you imply, and surely it does, 
then I agree: pivot_root already does the job.  Does anybody still need 
to use a bug in chroot?
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