On Wed, Jun 01, 2016 at 12:30:44AM +0800, address@hidden wrote:
From: Wei Xu <address@hidden>
Recently I'm working on a fd passing issue, selinux forbids qemu to
create a unix socket for a chardev when managing VMs with libvirt,
because qemu don't have sufficient permissions in this case, and
proposal from libvirt team is opening the 'fd' in libvirt and merely
passing it to qemu.
This sounds like a bug in libvirt, or selinux, or a mistaken configuration
of the guest. It is entirely possible for QEMU to create a unix socket - not
least because that is exactly what QEMU uses for its QMP monitor backend.
Looking at your example command line, I think the issue is simply that you
should be putting the sockets in a different location. ie at
/var/lib/libvirt/qemu/$guest-vhost-user1.sock where QEMU has permission to
create sockets already.
Alternatively you could enhance the SELinux policy to grant svirt_t the
permission to create sockets under /var/run/openvswitch too.
I finished a RFC patch for Unix socket after a glance of the code,
and not sure if this is right or there maybe other side-effects,
please point me out.
I tested it for both server and client mode 'PF_UNIX' socket with a VM
running vhost-user.
Old command line:
-chardev socket,id=char0,path=/var/run/openvswitch/vhost-user1,server
New command line:
-chardev socket,id=char0,path=/var/run/openvswitch/vhost-user1,server,sockfd=$n
because unix socket is bundled with a path, so it should be kept even with the
'fd' is indicated, this looks odd, any comments?
Yes, this syntax doesn't really make sense. The passed in sockfd may not
even be a UNIX socket - it could be a TCP socket. As such, the 'sockfd'
option should be mutually exclusive with the 'path' and 'host' options.
ie you can only supply one out of 'sockfd', 'path', or 'host'.