On Tue, Feb 21, 2017 at 10:59:18AM +0000, Stefan Hajnoczi wrote: > On Mon, Feb 20, 2017 at 03:34:57AM -0800, ashish mittal wrote: > > On Mon, Feb 20, 2017 at 3:02 AM, Stefan Hajnoczi <stefa...@gmail.com> wrote: > > > On Sat, Feb 18, 2017 at 12:30:31AM +0000, Ketan Nilangekar wrote: > > >> On 2/17/17, 1:42 PM, "Jeff Cody" <jc...@redhat.com> wrote: > > >> > > >> On Thu, Feb 16, 2017 at 02:24:19PM -0800, ashish mittal wrote: > > >> > Hi, > > >> > > > >> > I am getting the following error with checkpatch.pl > > >> > > > >> > ERROR: externs should be avoided in .c files > > >> > #78: FILE: block/vxhs.c:28: > > >> > +QemuUUID qemu_uuid __attribute__ ((weak)); > > >> > > > >> > Is there any way to get around this, or does it mean that I would > > >> have > > >> > to add a vxhs.h just for this one entry? > > >> > > > >> > > >> I remain skeptical on the use of the qemu_uuid as a way to select > > >> the TLS > > >> cert. > > >> > > >> [ketan] > > >> Is there another identity that can be used for uniquely identifying > > >> instances? > > >> The requirement was to enforce vdisk access to owner instances. > > > > > > The qemu_uuid weak attribute looks suspect. What is going to provide a > > > strong qemu_uuid symbol? > > > > > > Why aren't configuration parameters like the UUID coming from the QEMU > > > command-line? > > > > > > Stefan > > > > UUID will in fact come from the QEMU command line. VxHS is not doing > > anything special here. It will just use the value already available to > > qemu-kvm process. > > > > QemuUUID qemu_uuid; > > bool qemu_uuid_set; > > > > Both the above are defined in vl.c. vl.c will provide the strong > > symbol when available. There are certain binaries that do not get > > linked with vl.c (e.g. qemu-img). The weak symbol will come into > > affect for such binaries, and in this case, the default VXHS UUID will > > get picked up. I had, in a previous email, explained how we plan to > > use the default UUID. In the regular case, the VxHS controller will > > not allow access to the default UUID (non qemu-kvm) binaries, but it > > may choose to grant temporary access to specific vdisks for these > > binaries depending on the workflow. > > That idea sounds like a security problem. During this time window > anyone could use the default UUID to access the data?
Any use of the VM UUID as a means to control authorization on the server side is a security flaw, as this is a public value which cannot be trusted on its own. There needs to be some kind of authentication step to verify the reported identity, eg a password associated with the VM UUID that is validated before trusting the VM UUID. Alternatively there needs to be a completely separate UUID, unrelated to the VM UUID, which is treated as a private value (eg uses the '-object secret' framework in QEMU) > Just make the UUID (or TLS client certificate file) a command-line > parameter that qemu-system, qemu-img, and other tools accept (e.g. > qemu-img via the --image-opts/--object syntax). Regards, Daniel -- |: http://berrange.com -o- http://www.flickr.com/photos/dberrange/ :| |: http://libvirt.org -o- http://virt-manager.org :| |: http://entangle-photo.org -o- http://search.cpan.org/~danberr/ :|
