Re: [Libguestfs] [libvirt] qemu command line quoting (was: Re: [PATCH 0/5] rbd improvements)

On Sun, May 12, 2013 at 02:42:36PM -0400, Mike Kelly wrote: > On Thu, May 9, 2013 at 12:21 PM, Richard W.M. Jones <rjones(a)redhat.com&gt; wrote: > > On Thu, May 09, 2013 at 11:23:55AM -0400, Mike Kelly wrote: > >> On Wed, May 8, 2013 at 6:53 AM, Richard W.M. Jones <rjones(a)redhat.com&gt; wrote: > >> > One worry I have is whether quoting is required for the server > >> > name(s), export name, username and secret. > >> > >> Well. I think the main things we had to quote were ':' and ';', but > >> none of those are valid in a hostname. Username also probably doesn't > >> contain anything special, and secret is a base64-encoded string. I > >> confirmed that even with the string ending in '==', it was parsed just > >> fine by qemu, at least in my limited manual testing. > >> > >> If you can suggest a way to be more robust this, though, then I can > >> try to work that into a future patch series. > > > > The quoting problem happens when someone writes a program which takes > > (eg) a hostname string from the user and passes it unmodified to the > > guestfs API. It's an issue if this string can cause unexpected [even > > malicious/exploitable] things to happen when passed unquoted on the > > qemu command line. > > Well, I'm not sure if this way of setting things up is still > encouraged, but at least this documentation suggests basically using > the fact that libvirt won't quote the image name as a "feature": > > http://ceph.com/w/index.php?title=QEMU-RBD#Caching > > <disk type='network' device='disk'> > <source protocol='rbd' > name='poolname/imagename:rbd_cache=1:rbd_cache_size=67108864:rbd_cache_max_dirty=0'/> Hmmm ... This is a bug in libvirt, but also a missing feature of libvirt since it cannot express these other configuration fields.