How to setup permission for virtfs in system libvirtd

Question

I have troubles setting up the permissions for virtfs. I need to share a folder with several VMs in a way that user (same username, uid and gid on guests and host) can access it (have full permissions). I've tried various options but none gives the user the right permissions even with access=client option (of course the filesystem, ext4, is mounted with user_xattr and I've checked that I can set flags).

How to setup virtfs in such configuration? I'll use NFS for a time but virtfs should be faster.

It looks like mapped permission works if the file is created from within the VM and passthrough permission works for root but not other users - noone can access not-root owned files from guest and permission cannot be changed to non-root.

Answer 1

It looks like dropping the capabilities works. It's not entirely safe option as it allows for escalation from VM if qemu had an exploit.