Re: [Qemu-devel] [PATCH V4 00/13] Proxy FS driver for VirtFS

["M. Mohan Kumar" <mohan@in.ibm.com>]

On Thursday, December 08, 2011 11:16:33 PM Stefan Hajnoczi wrote:
> On Mon, Dec 05, 2011 at 09:48:37PM +0530, M. Mohan Kumar wrote:
> > From: "M. Mohan Kumar" <mohan@in.ibm.com>
> > 
> > Pass-through security model in QEMU 9p server needs root privilege to do
> > few file operations (like chown, chmod to any mode/uid:gid).  There are
> > two issues in pass-through security model
> > 
> > 1) TOCTTOU vulnerability: Following symbolic links in the server could
> > provide access to files beyond 9p export path.
> > 
> > 2) Running QEMU with root privilege could be a security issue.
> > 
> > To overcome above issues, following approach is used: A new filesytem
> > type 'proxy' is introduced. Proxy FS uses chroot + socket combination
> > for securing the vulnerability known with following symbolic links.
> > Intention of adding a new filesystem type is to allow qemu to run
> > in non-root mode, but doing privileged operations using socket IO.
> 
> Fails to build against qemu.git/master (217bfb4):
> 
>   CC    libhw64/9pfs/virtio-9p-proxy.o
> hw/9pfs/virtio-9p-proxy.c:1195:5: error: unknown field ‘parse_opts’
> specified in initializer hw/9pfs/virtio-9p-proxy.c:1195:5: warning:
> initialization from incompatible pointer type [enabled by default]
> hw/9pfs/virtio-9p-proxy.c:1195:5: warning: (near initialization for
> ‘proxy_ops.init’) [enabled by default]
> 
> Is this against another public tree?
>

Sorry, It depends on Aneesh's patch "Move opt validation to FsDriver callback"  
http://lists.gnu.org/archive/html/qemu-devel/2011-11/msg00275.html