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Bug 886456 - change-media fail with permission denied on virtio scsi cdrom
Summary: change-media fail with permission denied on virtio scsi cdrom
Keywords:
Status: CLOSED ERRATA
Alias: None
Product: Red Hat Enterprise Linux 7
Classification: Red Hat
Component: libvirt
Version: 7.0
Hardware: x86_64
OS: Linux
high
medium
Target Milestone: rc
: ---
Assignee: Peter Krempa
QA Contact: Virtualization Bugs
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2012-12-12 10:31 UTC by Wayne Sun
Modified: 2016-04-26 15:20 UTC (History)
12 users (show)

Fixed In Version: libvirt-1.2.17-8.el7
Doc Type: Bug Fix
Doc Text:
Clone Of:
Environment:
Last Closed: 2015-11-19 05:36:16 UTC
Target Upstream Version:
Embargoed:

Attachments (Terms of Use)
change-media log file (14.91 KB, application/zip)
2015-09-22 11:00 UTC, Han Han 		no flags Details
View All


Links
System ID Private Priority Status Summary Last Updated
Red Hat Product Errata RHBA-2015:2202 0 normal SHIPPED_LIVE libvirt bug fix and enhancement update 2015-11-19 08:17:58 UTC

Description Wayne Sun 2012-12-12 10:31:25 UTC 
Description of problem:
virsh change-media fail with permission denied on scsi cdrom

Version-Release number of selected component (if applicable):
libvirt-0.10.2-11.el6.x86_64
qemu-kvm-rhev-0.12.1.2-2.337.el6.x86_64
kernel-2.6.32-345.el6.x86_64

How reproducible:
always

Steps to Reproduce:

1.create two iso via mkiso
# mkisofs -o /var/lib/libvirt/images/bb.iso /tmp

# ll -Z /var/lib/libvirt/images/bb.iso
-rw-r--r--. qemu qemu system_u:object_r:virt_content_t:s0
/var/lib/libvirt/images/bb.iso


2.setup a domain with empty scsi cdrom
...
    <disk type='file' device='cdrom'>
      <driver name='qemu' type='raw'/>
      <target dev='sdc' bus='scsi' tray='open'/>
      <readonly/>
      <alias name='scsi0-0-1-0'/>
      <address type='drive' controller='0' bus='0' target='1' unit='0'/>
    </disk>
    <controller type='scsi' index='0' model='virtio-scsi'>
      <alias name='scsi0'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x05' function='0x0'/>
    </controller>
...

3. insert cdrom
# virsh change-media libvirt_test_api sdc /var/lib/libvirt/images/bb.iso
--insert
error: Failed to complete action insert on media
error: internal error unable to execute QEMU command 'change': Could not
open '/var/lib/libvirt/images/bb.iso': Permission denied

# virsh change-media libvirt_test_api sdc /var/lib/libvirt/images/bb.iso
--insert --force
error: Failed to complete action insert on media
error: internal error unable to execute QEMU command 'change': Could not
open '/var/lib/libvirt/images/bb.iso': Permission denied


4. edit domain xml
# mkisofs -o /tmp/aaa.iso /tmp

# ll -Z /tmp/aaa.iso
-rw-r--r--. root root unconfined_u:object_r:user_tmp_t:s0 /tmp/aaa.iso

# virsh edit libvirt_test_api
...
    <disk type='file' device='cdrom'>
      <driver name='qemu' type='raw'/>
      <source file='/tmp/aaa.iso'/>
      <target dev='sdc' bus='scsi'/>
      <readonly/>
      <address type='drive' controller='0' bus='0' target='1' unit='0'/>
    </disk>
...

# virsh start libvirt_test_api
Domain libvirt_test_api started

# ll -Z /tmp/aaa.iso
-rw-r--r--. qemu qemu system_u:object_r:virt_content_t:s0 /tmp/aaa.iso


5. change-media with update

# virsh change-media libvirt_test_api sdc /var/lib/libvirt/images/bb.iso
--update --force
error: Failed to complete action update on media
error: internal error unable to execute QEMU command 'change': Could not
open '/var/lib/libvirt/images/bb.iso': Permission denied

6. eject
# virsh change-media libvirt_test_api sdc --eject
succeeded to complete action eject on media

7. make selinux permissive
# setenforce 0
# virsh change-media libvirt_test_api sdc /tmp/aaa.iso --insert
succeeded to complete action insert on media

It succeeded when selinux in permissive.

Actual results:
change-media fail with permission denied on scsi cdrom

Expected results:
should success

Additional info:
No AVC denial but only got:
# ausearch -m VIRT_RESOURCE
type=VIRT_RESOURCE msg=audit(1355306961.927:134802): user pid=7604 uid=0 auid=4294967295 ses=4294967295 subj=system_u:system_r:virtd_t:s0-s0:c0.c1023 msg='virt=kvm resrc=disk reason=update vm="libvirt_test_api" uuid=05867c1a-afeb-300e-e55e-2673391ae080 old-disk="?" new-disk="/tmp/aaa.iso" exe="/usr/sbin/libvirtd" hostname=? addr=? terminal=? res=failed'
Comment 6 Jiri Denemark 2014-04-04 21:37:17 UTC 
This bug was not selected to be addressed in Red Hat Enterprise Linux 6. We will look at it again within the Red Hat Enterprise Linux 7 product.
Comment 9 Peter Krempa 2015-09-15 06:08:36 UTC 
Steps 1-3 don't fail any more in the current versions but I didn't go through and try to find where we fixed it actually. Marking test-only.
Comment 10 Han Han 2015-09-22 10:59:32 UTC 
Peter, I test it in steps1-3 with latest libvirt. There is still a error when change-media.
Version:
libvirt-1.2.17-9.el7.x86_64
qemu-kvm-rhev-2.3.0-24.el7.x86_64
Steps:
1. Preparing a running guest, and an iso file.
# virsh list 
 Id    Name                           State
----------------------------------------------------
 10    t62                            running

# virsh dumpxml t62|awk '/<disk/,/<\/disk/'
    <disk type='file' device='disk'>
      <driver name='qemu' type='qcow2'/>
      <source file='/var/lib/libvirt/images/t62.qcow2'/>
      <backingStore/>
      <target dev='vda' bus='virtio'/>
      <alias name='virtio-disk0'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x07' function='0x0'/>
    </disk>
    <disk type='file' device='cdrom'>
      <driver name='qemu' type='raw'/>
      <backingStore/>
      <target dev='sdc' bus='scsi' tray='open'/>
      <readonly/>
      <alias name='scsi0-0-0-2'/>
      <address type='drive' controller='0' bus='0' target='0' unit='2'/>
    </disk>

# ls -Z /var/lib/libvirt/images/boot.iso 
-rw-r--r--. qemu qemu system_u:object_r:virt_content_t:s0 /var/lib/libvirt/images/boot.iso

2. Run virsh change-media, the first time failed, the second time succeed.
# virsh change-media t62 sdc --insert /var/lib/libvirt/images/boot.iso                             
error: Failed to complete action insert on media
error: internal error: unable to execute QEMU command 'eject': Device 'drive-scsi0-0-0-2' is locked

# virsh change-media t62 sdc --insert /var/lib/libvirt/images/boot.iso                             
error: Failed to complete action insert on media
error: internal error: unable to execute QEMU command 'eject': Device 'drive-scsi0-0-0-2' is locked

The log is in change-media-log.

Is it an issue about qemu or libvirt?
Comment 11 Han Han 2015-09-22 11:00:51 UTC 
Created attachment 1075771 [details]
change-media log file
Comment 12 Peter Krempa 2015-09-22 11:15:31 UTC 
"Device 'drive-scsi0-0-0-2' is locked" means that the guest locked the CDROM drive. Please umount it from the guest to avoid that problem.
Comment 13 Han Han 2015-09-23 08:47:03 UTC 
(In reply to Peter Krempa from comment #12)
> "Device 'drive-scsi0-0-0-2' is locked" means that the guest locked the CDROM
> drive. Please umount it from the guest to avoid that problem.

But there is no CDROM mounted in guest when first time change-media and no media in cdrom. I think the issue is not related to guest's mount.

I mistook the second time change-media results in comment10. It should be:
# virsh change-media t62 sdc --insert /var/lib/libvirt/images/boot.iso 
Successfully inserted media.
Comment 14 Han Han 2015-10-12 06:36:38 UTC 
Peter, pls check the issue in Comment10 and Comment13
Comment 15 Han Han 2015-10-13 03:51:14 UTC 
Verify it in libvirt-1.2.17-13.el7.x86_64:
1. Enforce selinux and set iso selinux label
# setenforce 1
# chown qemu:qemu /var/lib/libvirt/images/bb.iso
# chcon -u system_u -r object_r -t virt_content_t  /var/lib/libvirt/images/bb.iso
# ls -Z /var/lib/libvirt/images/bb.iso
-rw-r--r--. qemu qemu system_u:object_r:virt_content_t:s0 /var/lib/libvirt/images/bb.iso

2. Setup a domain with empty scsi cdrom
...
<disk type='file' device='cdrom'>
      <driver name='qemu' type='raw'/>
      <target dev='sdc' bus='scsi'/>
      <readonly/>
      <address type='drive' controller='0' bus='0' target='0' unit='2'/>
    </disk>
   <controller type='scsi' index='0' model='virtio-scsi'>
      <alias name='scsi0'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x05' function='0x0'/>
    </controller>
...

3. Insert cdrom
# virsh start t111
Domain t111 started
# virsh change-media t111 sdc  /var/lib/libvirt/images/bb.iso --insert
Successfully inserted media.
Login guest, mount and read the media successfully.

4. Update cdrom
Destroy and start t111
# virsh destroy t111&&virsh start t111
Domain t111 destroyed
Domain t111 started
update the cdrom
# virsh change-media t111 sdc  /var/lib/libvirt/images/bb.iso --update                          
Successfully updated media.

5.Get selinux info
# ausearch -m VIRT_RESOURCE|grep t111
type=VIRT_RESOURCE msg=audit(1444707931.767:34143): pid=5574 uid=0 auid=4294967295 ses=4294967295 subj=system_u:system_r:virtd_t:s0-s0:c0.c1023 msg='virt=kvm resrc=disk reason=update vm="t111" uuid=11b957c8-2e76-44f5-9959-791d350a4215 old-disk="?" new-disk="/var/lib/libvirt/images/bb.iso" exe="/usr/sbin/libvirtd" hostname=? addr=? terminal=? res=success'
Comment 16 Han Han 2015-10-13 07:56:36 UTC 
For the issues in Comment10, refer to https://bugzilla.redhat.com/show_bug.cgi?id=1271069
Comment 18 errata-xmlrpc 2015-11-19 05:36:16 UTC 
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://rhn.redhat.com/errata/RHBA-2015-2202.html
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