Bug 2160356

Summary: Libvirt should not allow to add device selinux label without label string when relabel="yes"
Product: Red Hat Enterprise Linux 9 Reporter: Han Han <hhan>
Component: libvirtAssignee: Michal Privoznik <mprivozn>
libvirt sub component: General QA Contact: zhentang <zhetang>
Status: VERIFIED --- Docs Contact:
Severity: low    
Priority: low CC: fqi, hshuai, jdenemar, lmen, mprivozn, virt-maint, yafu, yalzhang
Version: 9.2Keywords: Triaged, Upstream
Target Milestone: rc   
Target Release: ---   
Hardware: Unspecified   
OS: Unspecified   
Whiteboard:
Fixed In Version: libvirt-9.5.0-0rc1.1.el9 Doc Type: If docs needed, set a value
Doc Text:
Story Points: ---
Clone Of:
: 2209225 (view as bug list) Environment:
Last Closed: Type: Bug
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version: 9.5.0
Embargoed:
Bug Depends On:    
Bug Blocks: 2209225    
Attachments:
Description Flags
The XML of VM none

Description Han Han 2023-01-12 07:06:13 UTC 
Created attachment 1937534 [details]
The XML of VM

Description of problem:
As subject

Version-Release number of selected component (if applicable):
libvirt-8.10.0-2.el9.x86_64

How reproducible:
100%

Steps to Reproduce:
1. Start an VM
2. Attach the console 
<console type="file">
      <source path="/var/log/libvirt/test.log" append="on">
              <seclabel model="selinux" relabel="yes">
                </seclabel>
      </source>
       <alias name="ua-console"/>
      <target type="virtio" port="1"/>
    </console>

# virsh attach-device rhel-9.2 console-file.xml         
Device attached successfully 


3. Dump and validate the VM XML:
# virsh dumpxml rhel-9.2 > /tmp/vm.xml

# virt-xml-validate /tmp/vm.xml       
Relax-NG validity error : Extra element devices in interleave
/tmp/vm.xml:36: element devices: Relax-NG validity error : Element domain failed to validate content
/tmp/vm.xml fails to validate

4. Detach the console device and validate the VM XML:
# virsh dumpxml rhel-9.2 > /tmp/new.xml

# virt-xml-validate /tmp/new.xml
/tmp/new.xml validates

Actual results:
As above

Expected results:
As https://bugzilla.redhat.com/show_bug.cgi?id=1528628#c2 said, the <label> should be specificed. So libvirt should validate the device XML before attaching and pop up the error like "the label string should be specified for label='yes'"

Additional info:
See the domain XML of failed validating in the attachment
Comment 1 Michal Privoznik 2023-01-18 12:05:30 UTC 
There's a lot of historical baggage around parsing of <seclabel/>-s so we must be careful to not break existing applications.
Comment 4 Michal Privoznik 2023-05-29 12:48:11 UTC 
Patch proposed on the list:

https://listman.redhat.com/archives/libvir-list/2023-May/240090.html
Comment 5 Michal Privoznik 2023-06-01 11:58:02 UTC 
Merged upstream as:

commit a36318be9d6fec1be3bd2bafefff0849e6b9e13a
Author:     Michal Prívozník <mprivozn>
AuthorDate: Thu May 25 15:43:56 2023 +0200
Commit:     Michal Prívozník <mprivozn>
CommitDate: Thu Jun 1 13:53:09 2023 +0200

    conf: Reject invalid device's <seclabel relabel='yes'/> with no <label/>
    
    We allow (some) domain devices to have a different <seclabel/>
    than the top level domain one (this is mostly to allow access to
    a resource for multiple domains). Now, we do couple of sanity
    checks for such <seclabel/>, e.g. when the <label/> is specified,
    but '@relabel' is set to no. But what we are missing is the
    opposite: when '@relabel' is set, but no <label/> was provided.
    
    Our schema already denies such combination. Make our parser
    behave the same.
    
    Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=2160356
    Signed-off-by: Michal Privoznik <mprivozn>
    Reviewed-by: Ján Tomko <jtomko>

v9.4.0-2-ga36318be9d
Comment 8 zhentang 2023-07-07 08:54:02 UTC 
Tested on libvirt-9.5.0-0rc1.1.el9.x86_64

1. hotplug a device with seclabel model 'selinux' and relabel='yes' without label string , failed with clear error message
[root@zhetang-rhel93 hotplug]# cat seclabel.plug.xml 
<serial type='unix'>
      <source mode='bind' path='/tmp/test1.sock'>
        <seclabel model='selinux' relabel='yes'>
        </seclabel>
      </source>
      <target type='pci-serial' port='1'/>
    </serial>

[root@zhetang-rhel93 hotplug]# virsh attach-device rhel9 seclabel.plug.xml 
error: Failed to attach device from seclabel.plug.xml
error: XML error: Cannot specify relabel if label is missing. model=selinux


2. hotplug a device with seclabel model 'dac' and relabel='yes' without label string , failed with clear error message
[root@zhetang-rhel93 hotplug]# cat dac_hotplug.xml 
<serial type='unix'>
      <source mode='bind' path='/tmp/test1.sock'>
        <seclabel model='dac' relabel='yes'>
        </seclabel>
      </source>
      <target type='pci-serial' port='1'/>
    </serial>

[root@zhetang-rhel93 hotplug]# virsh attach-device rhel9 dac_hotplug.xml 
error: Failed to attach device from dac_hotplug.xml
error: XML error: Cannot specify relabel if label is missing. model=dac

3.hotplug a device with selinux label string , attached successfully
[root@zhetang-rhel93 hotplug]# cat seclabel.plug.xml 
<serial type='unix'>
      <source mode='bind' path='/tmp/test1.sock'>
        <seclabel model='selinux' relabel='yes'>
          <label>system_u:object_r:svirt_image_t:s0</label>
        </seclabel>
      </source>
      <target type='pci-serial' port='1'/>
    </serial>
[root@zhetang-rhel93 hotplug]# virsh attach-device rhel9 seclabel.plug.xml 
Device attached successfully

[root@zhetang-rhel93 hotplug]# virsh dumpxml rhel9 --xpath //serial
<serial type="unix">
  <source mode="bind" path="/tmp/test1.sock">
    <seclabel model="selinux" relabel="yes">
      <label>system_u:object_r:svirt_image_t:s0</label>
    </seclabel>
  </source>
  <target type="pci-serial" port="1">
    <model name="pci-serial"/>
  </target>
  <alias name="serial0"/>
  <address type="pci" domain="0x0000" bus="0x09" slot="0x01" function="0x0"/>
</serial>

[root@zhetang-rhel93 hotplug]# ll -Z /tmp | grep test
srwxrwxr-x. 1 qemu qemu system_u:object_r:svirt_image_t:s0          0 Jul  7 04:44 test1.sock



4.hotplug a device with dac label string,  attached successfully

[root@zhetang-rhel93 hotplug]# cat dac_hotplug.xml 
<serial type='unix'>
      <source mode='bind' path='/tmp/test1.sock'>
        <seclabel model='dac' relabel='yes'>
		<label>test:test</label>
        </seclabel>
      </source>
      <target type='pci-serial' port='1'/>
    </serial>
[root@zhetang-rhel93 hotplug]# virsh attach-device rhel9 dac_hotplug.xml 
Device attached successfully
[root@zhetang-rhel93 hotplug]# virsh dumpxml rhel9 --xpath //serial
<serial type="unix">
  <source mode="bind" path="/tmp/test1.sock">
    <seclabel model="dac" relabel="yes">
      <label>test:test</label>
    </seclabel>
  </source>
  <target type="pci-serial" port="1">
    <model name="pci-serial"/>
  </target>
  <alias name="serial0"/>
  <address type="pci" domain="0x0000" bus="0x09" slot="0x01" function="0x0"/>
</serial>

[root@zhetang-rhel93 hotplug]# ll /tmp | grep test
srwxrwxr-x. 1 test test         0 Jul  7 04:42 test1.sock


5. hotplug a device with relabel='no',  attached successfully

[root@zhetang-rhel93 hotplug]# cat norelabel-hotplug.xml 
<serial type='unix'>
      <source mode='bind' path='/tmp/test1.sock'>
        <seclabel model='selinux' relabel='no'>
        </seclabel>
      </source>
      <target type='pci-serial' port='1'/>
    </serial>

[root@zhetang-rhel93 hotplug]# virsh attach-device rhel9 norelabel-hotplug.xml 
Device attached successfully

[root@zhetang-rhel93 hotplug]# virsh dumpxml rhel9 --xpath //serial
<serial type="unix">
  <source mode="bind" path="/tmp/test1.sock">
    <seclabel model="selinux" relabel="no"/>
  </source>
  <target type="pci-serial" port="1">
    <model name="pci-serial"/>
  </target>
  <alias name="serial0"/>
  <address type="pci" domain="0x0000" bus="0x09" slot="0x01" function="0x0"/>
</serial>
Comment 11 zhentang 2023-08-11 04:16:47 UTC 
verified on libvirt-9.5.0-5.el9.x86_64

1. hotplug a device with seclabel model 'selinux' and relabel='yes' without label string , failed with clear error message
[root@zhetang-rhel93 hotplug]# cat seclabel.plug.xml 
<serial type='unix'>
      <source mode='bind' path='/tmp/test1.sock'>
        <seclabel model='selinux' relabel='yes'>
        </seclabel>
      </source>
      <target type='pci-serial' port='1'/>
    </serial>
[root@zhetang-rhel93 hotplug]# virsh attach-device blob-rhel9-3 seclabel.plug.xml 
error: Failed to attach device from seclabel.plug.xml
error: XML error: Cannot specify relabel if label is missing. model=selinux

2. hotplug a device with seclabel model 'dac' and relabel='yes' without label string , failed with clear error message
[root@zhetang-rhel93 hotplug]# cat dac_hotplug.xml 
<serial type='unix'>
      <source mode='bind' path='/tmp/test1.sock'>
        <seclabel model='dac' relabel='yes'>
        </seclabel>
      </source>
      <target type='pci-serial' port='1'/>
    </serial>
[root@zhetang-rhel93 hotplug]# virsh attach-device blob-rhel9-3 dac_hotplug.xml 
error: Failed to attach device from dac_hotplug.xml
error: XML error: Cannot specify relabel if label is missing. model=dac

3. hotplug a device with selinux label string , attached successfully
[root@zhetang-rhel93 hotplug]# cat seclabel.plug.xml 
<serial type='unix'>
      <source mode='bind' path='/tmp/test1.sock'>
        <seclabel model='selinux' relabel='yes'>
		<label>system_u:object_r:svirt_image_t:s0</label>
        </seclabel>
      </source>
      <target type='pci-serial' port='1'/>
    </serial>

[root@zhetang-rhel93 hotplug]# virsh attach-device rhel9 seclabel.plug.xml 
Device attached successfully

[root@zhetang-rhel93 hotplug]# virsh dumpxml rhel9 --xpath //serial
<serial type="unix">
  <source mode="bind" path="/tmp/test1.sock">
    <seclabel model="selinux" relabel="yes">
      <label>system_u:object_r:svirt_image_t:s0</label>
    </seclabel>
  </source>
  <target type="pci-serial" port="1">
    <model name="pci-serial"/>
  </target>
  <alias name="serial0"/>
  <address type="pci" domain="0x0000" bus="0x09" slot="0x01" function="0x0"/>
</serial>

4. hotplug a device with dac label string,  attached successfully
[root@zhetang-rhel93 hotplug]# cat dac_hotplug.xml 
<serial type='unix'>
      <source mode='bind' path='/tmp/test1.sock'>
        <seclabel model='dac' relabel='yes'>
		<label>test:test</label>
        </seclabel>
      </source>
      <target type='pci-serial' port='1'/>
    </serial>

[root@zhetang-rhel93 hotplug]# virsh attach-device rhel9 dac_hotplug.xml 
Device attached successfully

[root@zhetang-rhel93 hotplug]# virsh dumpxml rhel9 --xpath //serial
<serial type="unix">
  <source mode="bind" path="/tmp/test1.sock">
    <seclabel model="dac" relabel="yes">
      <label>test:test</label>
    </seclabel>
  </source>
  <target type="pci-serial" port="1">
    <model name="pci-serial"/>
  </target>
  <alias name="serial0"/>
  <address type="pci" domain="0x0000" bus="0x09" slot="0x01" function="0x0"/>
</serial>


5. hotplug a device with relabel='no',  attached successfully
[root@zhetang-rhel93 hotplug]# cat norelabel-hotplug.xml 
<serial type='unix'>
      <source mode='bind' path='/tmp/test1.sock'>
        <seclabel model='selinux' relabel='no'>
        </seclabel>
      </source>
      <target type='pci-serial' port='1'/>
    </serial>
[root@zhetang-rhel93 hotplug]# virsh attach-device rhel9 norelabel-hotplug.xml 
Device attached successfully
[root@zhetang-rhel93 hotplug]# virsh dumpxml rhel9 --xpath //serial
<serial type="unix">
  <source mode="bind" path="/tmp/test1.sock">
    <seclabel model="selinux" relabel="no"/>
  </source>
  <target type="pci-serial" port="1">
    <model name="pci-serial"/>
  </target>
  <alias name="serial0"/>
  <address type="pci" domain="0x0000" bus="0x09" slot="0x01" function="0x0"/>
</serial>