Re: [Qemu-devel] [RFC PATCH] virtio-9p: Use clone approach to fix TOCTOU vulnerability

[Venkateswararao Jujjuri]

On 06/15/2011 10:35 AM, Stefan Hajnoczi wrote:
> On Tue, Jun 14, 2011 at 9:12 AM, M. Mohan Kumar<address@hidden>  wrote:
> > [RFC PATCH] virtio-9p: Use clone approach to fix TOCTOU vulnerability
> >
> > In passthrough security model, following a symbolic link in the server
> > side could result in TOCTTOU vulnerability.
> >
> > Use clone system call to create a thread which runs in chrooted
> > environment. All passthrough model file operations are done from this
> > thread to avoid TOCTTOU vulnerability.
> How will chroot(2) work when QEMU runs as non-root (i.e. secure
> production environments)?
This is used only in passthrough mode; passthrough mode needs root 
access by design.
There is no TOCTTOU vulnerability in mapped mode as symlinks are not 
actual symlinks on host FS.

JV

> Stefan