On Mon, Feb 07, 2022 at 01:05:16PM +0000, Daniel P. Berrangé wrote: > On Wed, Feb 02, 2022 at 02:39:26PM -0500, Vivek Goyal wrote: > > Hi, > > > > This is V5 of the patches. I posted V4 here. > > > > https://listman.redhat.com/archives/virtio-fs/2022-January/msg00041.html > > > > These will allow us to support SELinux with virtiofs. This will send > > SELinux context at file creation to server and server can set it on > > file. > > I've not entirely figured it out from the code, so easier for me > to ask... > > How is the SELinux labelled stored on the host side ? It is stored > directly in the security.* xattr namespace, or is is subject to > xattr remapping that virtiofsd already supports. > > Storing directly means virtiofsd has to run in an essentially > unconfined context, to let it do arbitrary changes on security.* > xattrs without being blocked by SELinux) and has risk that guest > initiated changes can open holes in the host confinement if > the exported FS is generally visible to processes on the host. > > > Using remapping lets virtiofsd be strictly isolated by SELinux > policy on the host, and ensures that guest context changes > can't open up holes in the host. > > Both are valid use cases, so I'd ultimately expect us to want > to support both, but my preference for a "default" behaviour > would be remapping.
I am expecting users to configure virtiofsd to remap "security.selinux" to "trusted.virtiofsd.security.selinux" and that will allow guest and host security selinux to co-exist and allow separate SELinux policies for guest and host. I agree that my preference for a default behavior is remapping as well. That makes most sense. One downside of mapping to trusted namespace is that it requires CAP_SYS_ADMIN for virtiofsd. Having said that, these patches don't enforce the remapping default. That has to come from the user because it also needs to be given CAP_SYS_ADMIN. So out of box default is no remapping and passthrough SELinux. Thanks Vivek > > 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 :| >