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[libvirt] [PATCH] qemu: pass the information when disks are read-only



The problem is that even when the user indicates that a drive has to be
opened as read-only (for example a cd-rom) qemu didn't get the
information and tried to open read-write. This could get really nasty
in case SELinux is monitoring that no read-write access is attempted:

  https://bugzilla.redhat.com/show_bug.cgi?id=536760

Patch is relatively simple and based on teh assumption that if the
-device qemu options are allowed then qemu also knows about the
readonly option (this was added to the help string quite later so
we should not rely on that in this case).

* src/qemu/qemu_conf.c: add the ",readonly=on" for read-only disks
  and also parse it back in qemuParseCommandLineDisk()
* tests/qemuxml2argvtest.c
  tests/qemuxml2argvdata/qemuxml2argv-disk-drive-readonly-disk.args
  tests/qemuxml2argvdata/qemuxml2argv-disk-drive-readonly-disk.xml:
  add a specific regression test

diff --git a/src/qemu/qemu_conf.c b/src/qemu/qemu_conf.c
index 40ca221..fb23c52 100644
--- a/src/qemu/qemu_conf.c
+++ b/src/qemu/qemu_conf.c
@@ -2398,6 +2398,9 @@ qemuBuildDriveStr(virDomainDiskDefPtr disk,
     if (bootable &&
         disk->device == VIR_DOMAIN_DISK_DEVICE_DISK)
         virBufferAddLit(&opt, ",boot=on");
+    if (disk->readonly &&
+        qemuCmdFlags & QEMUD_CMD_FLAG_DEVICE)
+        virBufferAddLit(&opt, ",readonly=on");
     if (disk->driverType &&
         disk->type != VIR_DOMAIN_DISK_TYPE_DIR &&
         qemuCmdFlags & QEMUD_CMD_FLAG_DRIVE_FORMAT)
@@ -4694,6 +4697,9 @@ qemuParseCommandLineDisk(const char *val,
                                 _("cannot parse drive unit '%s'"), val);
                 goto cleanup;
             }
+        } else if (STREQ(keywords[i], "readonly")) {
+            if ((values[i] == NULL) || STREQ(values[i], "on"))
+                def->readonly = 1;
         }
     }
 
diff --git a/tests/qemuxml2argvdata/qemuxml2argv-disk-drive-readonly-disk.args b/tests/qemuxml2argvdata/qemuxml2argv-disk-drive-readonly-disk.args
new file mode 100644
index 0000000..fbc3226
--- /dev/null
+++ b/tests/qemuxml2argvdata/qemuxml2argv-disk-drive-readonly-disk.args
@@ -0,0 +1 @@
+LC_ALL=C PATH=/bin HOME=/home/test USER=test LOGNAME=test /usr/bin/qemu -S -M pc -m 214 -smp 1 -nographic -nodefaults -monitor unix:/tmp/test-monitor,server,nowait -no-acpi -boot c -drive file=/dev/HostVG/QEMUGuest1,if=none,id=drive-ide0-0-0 -device ide-drive,bus=ide.0,unit=0,drive=drive-ide0-0-0,id=ide0-0-0 -drive file=/dev/sr0,if=none,media=cdrom,id=drive-ide0-1-0,readonly=on -device ide-drive,bus=ide.1,unit=0,drive=drive-ide0-1-0,id=ide0-1-0 -usb -device virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x3
diff --git a/tests/qemuxml2argvdata/qemuxml2argv-disk-drive-readonly-disk.xml b/tests/qemuxml2argvdata/qemuxml2argv-disk-drive-readonly-disk.xml
new file mode 100644
index 0000000..39c3a1c
--- /dev/null
+++ b/tests/qemuxml2argvdata/qemuxml2argv-disk-drive-readonly-disk.xml
@@ -0,0 +1,30 @@
+<domain type='qemu'>
+  <name>QEMUGuest1</name>
+  <uuid>c7a5fdbd-edaf-9455-926a-d65c16db1809</uuid>
+  <memory>219200</memory>
+  <currentMemory>219200</currentMemory>
+  <vcpu>1</vcpu>
+  <os>
+    <type arch='i686' machine='pc'>hvm</type>
+    <boot dev='hd'/>
+  </os>
+  <clock offset='utc'/>
+  <on_poweroff>destroy</on_poweroff>
+  <on_reboot>restart</on_reboot>
+  <on_crash>destroy</on_crash>
+  <devices>
+    <emulator>/usr/bin/qemu</emulator>
+    <disk type='block' device='disk'>
+      <source dev='/dev/HostVG/QEMUGuest1'/>
+      <target dev='hda' bus='ide'/>
+      <address type='drive' controller='0' bus='0' unit='0'/>
+    </disk>
+    <disk type='block' device='cdrom'>
+       <source dev='/dev/sr0'/>
+       <target dev='hdc' bus='ide'/>
+       <readonly/>
+       <address type='drive' controller='0' bus='1' unit='0'/>
+    </disk>
+    <controller type='ide' index='0'/>
+  </devices>
+</domain>
diff --git a/tests/qemuxml2argvtest.c b/tests/qemuxml2argvtest.c
index 4ca946a..e3762c9 100644
--- a/tests/qemuxml2argvtest.c
+++ b/tests/qemuxml2argvtest.c
@@ -249,6 +249,8 @@ mymain(int argc, char **argv)
             QEMUD_CMD_FLAG_DRIVE_BOOT | QEMUD_CMD_FLAG_DRIVE_FORMAT);
     DO_TEST("disk-drive-fat", QEMUD_CMD_FLAG_DRIVE |
             QEMUD_CMD_FLAG_DRIVE_BOOT | QEMUD_CMD_FLAG_DRIVE_FORMAT);
+    DO_TEST("disk-drive-readonly-disk", QEMUD_CMD_FLAG_DRIVE |
+            QEMUD_CMD_FLAG_DEVICE);
     DO_TEST("disk-drive-fmt-qcow", QEMUD_CMD_FLAG_DRIVE |
             QEMUD_CMD_FLAG_DRIVE_BOOT | QEMUD_CMD_FLAG_DRIVE_FORMAT);
     DO_TEST("disk-drive-shared", QEMUD_CMD_FLAG_DRIVE |

-- 
Daniel Veillard      | libxml Gnome XML XSLT toolkit  http://xmlsoft.org/
daniel veillard com  | Rpmfind RPM search engine http://rpmfind.net/
http://veillard.com/ | virtualization library  http://libvirt.org/


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