Re: [PATCH] Add hw random number generator (/dev/hwrng) to default qemu cgroup ACL

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On Mon, Nov 18, 2013 at 09:05:21AM -0700, Eric Blake wrote:
> On 11/18/2013 08:20 AM, Daniel P. Berrange wrote:
> 
> >>  static const char *const defaultDeviceACL[] = {
> >>      "/dev/null", "/dev/full", "/dev/zero",
> >> -    "/dev/random", "/dev/urandom",
> >> +    "/dev/random", "/dev/urandom", "/dev/hwrng",
> >>      "/dev/ptmx", "/dev/kvm", "/dev/kqemu",
> >>      "/dev/rtc", "/dev/hpet", "/dev/vfio/vfio",
> >>      NULL,
> > 
> > NACK, for any device listed in the XML, we should add it in the per-VM
> > cgroups setup code.
> > 
> > The existing /dev/random & /dev/urandom devices are there because they
> > are used for basic crypto libraries unrelated to the XML config.
> 
> /dev/urandom, probably.  /dev/random - really?  Isn't that a DoS
> potential for one guest to starve entropy from other guests, in spite of
> sVirt?

It is a tradeoff between providing the crypto libraries a weaker
entropy source vs DOS potential via entropy starvation. Given that
/dev/random is world writable on Linux in general, I think it is
acceptable to allow QEMU access by default. Paranoid admins can
always set the cgroups device ACL in /etc/libvirt/.qemu.conf if
they want to restrict it.

Daniel
-- 
|: http://berrange.com      -o-    http://www.flickr.com/photos/dberrange/ :|
|: http://libvirt.org              -o-             http://virt-manager.org :|
|: http://autobuild.org       -o-         http://search.cpan.org/~danberr/ :|
|: http://entangle-photo.org       -o-       http://live.gnome.org/gtk-vnc :|

--
libvir-list mailing list
libvir-list@xxxxxxxxxx
https://www.redhat.com/mailman/listinfo/libvir-list




[Index of Archives]     [Virt Tools]     [Libvirt Users]     [Lib OS Info]     [Fedora Users]     [Fedora Desktop]     [Fedora SELinux]     [Big List of Linux Books]     [Yosemite News]     [KDE Users]     [Fedora Tools]