[libvirt] [PATCH] apparmor: fix vfio usage without initial hostdev

Christian Ehrhardt christian.ehrhardt at canonical.com
Mon Jun 11 13:23:40 UTC 2018


On Mon, Jun 11, 2018 at 2:48 PM, Erik Skultety <eskultet at redhat.com> wrote:

> On Mon, Jun 11, 2018 at 01:52:54PM +0200, Christian Ehrhardt wrote:
> > The base vfio has not much functionality but to provide a custom
> > container by opening this path.
> > See https://www.kernel.org/doc/Documentation/vfio.txt for more.
> >
> > Systems with static hostdevs will get /dev/vfio/vfio by virt-aa-hotplug
> > right from the beginning. But if the guest initially had no hostdev at
> > all it will run into the following deny before the security module
> > labelling callbacks will make the actual vfio device (like /dev/vfio/93)
> > known.
> >
> > Access by qemu is "wr" even thou in theory it could maybe be "r":
>
> ^this sentence is not necessary for the commit message and should be
> dropped.
>

Agreed will be dropped on a V2 or when pushing the change.


> > [ 2652.756712] audit: type=1400 audit(1491303691.719:25):
> >   apparmor="DENIED" operation="open"
> >   profile="libvirt-17a61b87-5132-497c-b928-421ac2ee0c8a"
> >   name="/dev/vfio/vfio" pid=8486 comm="qemu-system-x86"
> >   requested_mask="wr" denied_mask="wr" fsuid=64055 ouid=0
> >
> > Bug-Ubuntu: https://bugs.launchpad.net/bugs/1678322
> > Bug-Ubuntu: https://bugs.launchpad.net/bugs/1775777
> >
> > Signed-off-by: Christian Ehrhardt <christian.ehrhardt at canonical.com>
> > Signed-off-by: Stefan Bader <stefan.bader at canonical.com>
> > ---
> >  examples/apparmor/libvirt-qemu | 3 +++
> >  1 file changed, 3 insertions(+)
> >
> > diff --git a/examples/apparmor/libvirt-qemu b/examples/apparmor/libvirt-
> qemu
> > index 2c47652250..874aca2092 100644
> > --- a/examples/apparmor/libvirt-qemu
> > +++ b/examples/apparmor/libvirt-qemu
> > @@ -193,6 +193,9 @@
> >    deny /dev/shm/lttng-ust-wait-* r,
> >    deny /run/shm/lttng-ust-wait-* r,
> >
> > +  # for vfio hotplug on systems without static vfio (LP: #1775777)
> > +  /dev/vfio/vfio rw,
>
> Per the kernel doc you linked in the commit message I think this is fine.
>
> Reviewed-by: Erik Skultety <eskultet at redhat.com>
>

Thanks, will add the reviewed-by on a V2 or when pushing the change.

I'll leave it out for discussion as-is a bit more ...



-- 
Christian Ehrhardt
Software Engineer, Ubuntu Server
Canonical Ltd
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