Re: [Qemu-devel] [PATCH] block: handle filenames with colons better

[Iustin Pop <iusty@k1024.org>]

On Thu, Aug 16, 2012 at 11:24:11PM +0400, Michael Tokarev wrote:
> On 16.08.2012 18:58, Iustin Pop wrote:
> > Commit 947995c (block: protect path_has_protocol from filenames with
> > colons) introduced a way to handle filenames with colons based on
> > whether the path contains a slash or not. IMHO this is not optimal,
> > since we shouldn't rely on the contents of the path but rather on
> > whether the given path exists as a file or not.
> > 
> > As such, this patch tries to handle both files with and without
> > slashes by falling back to opening them as files if no drivers
> > supporting the protocol has been identified.
> 
> I for one dislike this idea entirely: I think there should be a
> way to stop qemu from trying to open something as a file.  It
> opens a security hole after all, "what if" such a file will actually
> exist?

I'm not sure I understand the concern here. You pass what is a file path
(and not an existing protocol path), and you want qemu not to open it?
Or are you worried that a typo in the protocol name can lead to attacks?

> If I can vote, I'm voting against this with both hands.

It's fine to have a way to stop QEMU opening something as a file, but
please tell me how I can make it so that "qemu -hda x:0" works for both
regular files and block/char devices. Right now, it behaves differently
for these two, and from the code it looks like this difference is rather
accidental than intentional.

regards,
iustin