On Tue, Mar 26, 2019 at 04:20:02PM +0100, Pavel Hrdina wrote: > On Tue, Mar 26, 2019 at 01:36:14PM +0000, Daniel P. Berrangé wrote: > > On Tue, Mar 26, 2019 at 02:30:00PM +0100, Pavel Hrdina wrote: > > > On Tue, Mar 26, 2019 at 01:20:46PM +0000, Daniel P. Berrangé wrote: > > > > On Tue, Mar 26, 2019 at 12:49:28PM +0100, Andrea Bolognani wrote: > > > > > Our current defaults are root:wheel on FreeBSD and macOS, root:root > > > > > everywhere else. > > > > > > > > > > Looking at what downstream distributions actually do, we can see that > > > > > these defaults are overriden the vast majority of the time, with a > > > > > number of variations showing up in the wild: > > > > > > > > > > * qemu:qemu -> Used by CentOS, Fedora, Gentoo, OpenSUSE, RHEL > > > > > and... As it turns out, our very own spec file :) > > > > > > > > > > * libvirt-qemu:libvirt-qemu -> Used by Debian. > > > > > > > > > > * libvirt-qemu:kvm -> Used by Ubuntu. > > > > > > > > > > * nobody:nobody -> Used by Arch Linux. > > > > > > > > > > Based on the above, we can conclude that qemu:qemu are the preferred > > > > > credentials to be used when spawning a QEMU process, while our > > > > > current defaults get very little love. > > > > > > > > > > Changing our defaults aligns with what most downstreams are actually > > > > > doing, promotes running QEMU under a non-root user - which is a very > > > > > good idea anyway - and shields random people building libvirt from > > > > > source from unwittingly running their guests as root. > > > > > > > > While I understand the motivation, this impl is problematic because > > > > it will guarantee that someone building & installing libvirt from > > > > source on Debian, Ubuntu and Arch will have a non-functional QEMU > > > > driver as it will try to use a "qemu:qemu" user/group which does > > > > not exist on those distros. > > > > > > > > If we want to change this, we must ensure that we honour the distro > > > > specific user/group names you show above, and fallback to root/root > > > > for distros we don't know about. > > > > > > Or possibly we can fallback to nobody or similar that is used by every > > > distro. That way we would not use root:root for unknown distros as > > > well. > > > > I'm not sure falling back to "nobody" is a good idea. The "nobody" > > account is often used for setting file permissions on things that > > nothing should be allowed to access. By running qemu as "nobody" > > we would be given access to those files which may be a security > > issue. Yes Arch is using this account, so they've decided it is > > safe for their distro, but we can't assume other distros use "nobody" > > the same way as Arch. > > Right, did not realize that. I guess that there is no other user widely > used by majority of distributions so we probably need to fallback to > root:root. Of course I should note running with root:root is guaranteed to be insecure on every distro :-) The point is more that running as "nobody" potentially gives a potentially problematic sense of security. Regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :| -- libvir-list mailing list libvir-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/libvir-list
