lkml.org 
[lkml]   [2003]   [Jun]   [29]   [last100]   RSS Feed
Views: [more markup]  [less markup]  [headers]  [forward] 
 
Messages in this thread
/
DateSun, 29 Jun 2003 16:24:59 +0200
FromWilly TARREAU <>
SubjectRe: [RFC][PATCH-2.4] Prevent mounting on ".."
On Sun, Jun 29, 2003 at 04:09:40PM +0200, Arjan van de Ven wrote:
> On Sun, 2003-06-29 at 15:09, Willy TARREAU wrote:
> > Hi Al and Marcelo,
> > 
> > while I was trying to get maximum restrictions on a chroot on 2.4.21-pre,
> > I found that it's always possible to mount a ramfs or a tmpfs on "..",
> > and then upload whatever I wanted in it. It's a shame because I was
> > trying to isolate network daemons inside empty, read-only file-systems,
> > and I discovered that this effort was worthless. To resume, imagine a
> > network daemon which does :
> 
> well...
> you need to be root to mount. If you're root you can break out of a
> chroot anyway....

not in all cases. for the classical "mkdir a; chroot a; chdir ..", you need a
writable directory to create "a" or an existing directory somewhere to serve
as a mount point. If neither of them is true, I don't see other means of
escaping the chroot. And here, ".." is the only one I could exploit, that's why
I proposed this patch which closes what is, to me, the only weakness in this
very particular case.

Cheers,
Willy

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2005-03-22 12:40    [W:0.419 / U:0.140 seconds]
©2003-2008 Jasper Spaans