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Description of problem:
In this code:
int qemuSetupCgroup(struct qemud_driver *driver,
virDomainObjPtr vm)
....
if (vm->def->nsounds) {
rc = virCgroupAllowDeviceMajor(cgroup, 'c', DEVICE_SND_MAJOR);
qemuDomainCgroupAudit(vm, cgroup, "allow", "major", "sound",
rc == 0);
if (rc != 0) {
virReportSystemError(-rc, "%s",
_("unable to allow /dev/snd/ devices"));
goto cleanup;
}
}
We have granted QEMU access to the host sound devices, regardless of whether the guest XML config needs it.
We only need to grant access if the graphics type is SDL, or if the graphics type is VNC & vnc_allow_host_audio == 1.
ie, we should be denying access when VNC is used by default, or if SPICE is used.
Version-Release number of selected component (if applicable):
libvirt-0.8.7-6.el6
How reproducible:
Always
Steps to Reproduce:
1. Create a guest with VNC graphics, and vnc_allow_host_audio == 0
2.
3.
Actual results:
Sound devices allowed in cgroups ACL
Expected results:
Sound devices denied.
Additional info:
checked with : libvirt-0.8.7-11.el6.x86_64
Steps to Verify:
1. look up the Major number for the sound device
# ll /dev/snd/controlC0
crw-rw----+ 1 root audio 116, 8 Mar 10 07:51 /dev/snd/controlC0
so the major number is 116
2. set vnc_allow_host_audio == 0 in /etc/libvirt/qemu.conf and restart libvirtd service
3. create a guest with vnc graphical framebuffer
4. check the cgroup ACL
# grep 116 /cgroup/devices/libvirt/qemu/guest/devices.list
5. create a guest with spice graphical framebuffer
6. check the cgroup ACL
# grep 116 /cgroup/devices/libvirt/qemu/guest/devices.list
Actual result :
1. with buggy libvirt-0.8.7-6 , could get "c 116:* rwm"
2. with bug fixed libvirt-0.8.7.11, the audio devices is not record to cgroups ACL
So set bug status to VERIFIED
An advisory has been issued which should help the problem
described in this bug report. This report is therefore being
closed with a resolution of ERRATA. For more information
on therefore solution and/or where to find the updated files,
please follow the link below. You may reopen this bug report
if the solution does not work for you.
http://rhn.redhat.com/errata/RHBA-2011-0596.html
Description of problem: In this code: int qemuSetupCgroup(struct qemud_driver *driver, virDomainObjPtr vm) .... if (vm->def->nsounds) { rc = virCgroupAllowDeviceMajor(cgroup, 'c', DEVICE_SND_MAJOR); qemuDomainCgroupAudit(vm, cgroup, "allow", "major", "sound", rc == 0); if (rc != 0) { virReportSystemError(-rc, "%s", _("unable to allow /dev/snd/ devices")); goto cleanup; } } We have granted QEMU access to the host sound devices, regardless of whether the guest XML config needs it. We only need to grant access if the graphics type is SDL, or if the graphics type is VNC & vnc_allow_host_audio == 1. ie, we should be denying access when VNC is used by default, or if SPICE is used. Version-Release number of selected component (if applicable): libvirt-0.8.7-6.el6 How reproducible: Always Steps to Reproduce: 1. Create a guest with VNC graphics, and vnc_allow_host_audio == 0 2. 3. Actual results: Sound devices allowed in cgroups ACL Expected results: Sound devices denied. Additional info: