From 3b03a27cd00c2f032661d2bf8905795425752fc7 Mon Sep 17 00:00:00 2001
From: Peter Krempa <pkrempa@redhat.com>
Date: Tue, 14 Nov 2017 15:37:09 +0100
Subject: [PATCH] qemu: domain: Reject shared disk access if backing format
 does not support it

Disk sharing between two VMs may corrupt the images if the format driver
does not support it. Check that the user declared use of a supported
storage format when they want to share the disk.

Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1511480
---
 src/qemu/qemu_domain.c                        | 27 ++++++++++++++++++
 .../qemuxml2argv-disk-drive-shared-qcow.xml   | 28 +++++++++++++++++++
 .../qemuxml2argv-disk-drive-shared.args       |  2 +-
 .../qemuxml2argv-disk-drive-shared.xml        |  2 +-
 tests/qemuxml2argvtest.c                      |  1 +
 5 files changed, 58 insertions(+), 2 deletions(-)
 create mode 100644 tests/qemuxml2argvdata/qemuxml2argv-disk-drive-shared-qcow.xml

diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c
index bd96b26172..d068b36f4e 100644
--- a/src/qemu/qemu_domain.c
+++ b/src/qemu/qemu_domain.c
@@ -25,6 +25,7 @@
 
 #include "qemu_domain.h"
 #include "qemu_alias.h"
+#include "qemu_block.h"
 #include "qemu_cgroup.h"
 #include "qemu_command.h"
 #include "qemu_process.h"
@@ -3724,6 +3725,29 @@ qemuDomainDeviceDefValidateVideo(const virDomainVideoDef *video)
 }
 
 
+static int
+qemuDomainDeviceDefValidateDisk(const virDomainDiskDef *disk)
+{
+    if (disk->src->shared && !disk->src->readonly) {
+        if (disk->src->format <= VIR_STORAGE_FILE_AUTO) {
+            virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
+                           _("shared access for disk '%s' requires use of "
+                             "explicitly specified disk format"), disk->dst);
+            return -1;
+        }
+
+        if (!qemuBlockStorageSourceSupportsConcurrentAccess(disk->src)) {
+            virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
+                           _("shared access for disk '%s' requires use of "
+                             "supported storage format"), disk->dst);
+            return -1;
+        }
+    }
+
+    return 0;
+}
+
+
 static int
 qemuDomainDeviceDefValidate(const virDomainDeviceDef *dev,
                             const virDomainDef *def,
@@ -3765,6 +3789,9 @@ qemuDomainDeviceDefValidate(const virDomainDeviceDef *dev,
         break;
 
     case VIR_DOMAIN_DEVICE_DISK:
+        ret = qemuDomainDeviceDefValidateDisk(dev->data.disk);
+        break;
+
     case VIR_DOMAIN_DEVICE_LEASE:
     case VIR_DOMAIN_DEVICE_FS:
     case VIR_DOMAIN_DEVICE_INPUT:
diff --git a/tests/qemuxml2argvdata/qemuxml2argv-disk-drive-shared-qcow.xml b/tests/qemuxml2argvdata/qemuxml2argv-disk-drive-shared-qcow.xml
new file mode 100644
index 0000000000..ca88a944b3
--- /dev/null
+++ b/tests/qemuxml2argvdata/qemuxml2argv-disk-drive-shared-qcow.xml
@@ -0,0 +1,28 @@
+<domain type='qemu'>
+  <name>QEMUGuest1</name>
+  <uuid>c7a5fdbd-edaf-9455-926a-d65c16db1809</uuid>
+  <memory unit='KiB'>219136</memory>
+  <currentMemory unit='KiB'>219136</currentMemory>
+  <vcpu placement='static'>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-system-i686</emulator>
+    <disk type='block' device='disk'>
+      <driver name='qemu' type='qcow2'/>
+      <source dev='/dev/HostVG/QEMUGuest1'/>
+      <target dev='hda' bus='ide'/>
+      <shareable/>
+      <address type='drive' controller='0' bus='0' target='0' unit='0'/>
+    </disk>
+    <controller type='usb' index='0'/>
+    <controller type='ide' index='0'/>
+    <memballoon model='virtio'/>
+  </devices>
+</domain>
diff --git a/tests/qemuxml2argvdata/qemuxml2argv-disk-drive-shared.args b/tests/qemuxml2argvdata/qemuxml2argv-disk-drive-shared.args
index e9c7bb9deb..f449ddca72 100644
--- a/tests/qemuxml2argvdata/qemuxml2argv-disk-drive-shared.args
+++ b/tests/qemuxml2argvdata/qemuxml2argv-disk-drive-shared.args
@@ -19,7 +19,7 @@ server,nowait \
 -no-acpi \
 -boot c \
 -usb \
--drive file=/dev/HostVG/QEMUGuest1,format=qcow2,if=none,id=drive-ide0-0-0,\
+-drive file=/dev/HostVG/QEMUGuest1,format=raw,if=none,id=drive-ide0-0-0,\
 serial=XYZXYZXYZYXXYZYZYXYZY,cache=none \
 -device ide-drive,bus=ide.0,unit=0,drive=drive-ide0-0-0,id=ide0-0-0 \
 -drive file=/dev/HostVG/QEMUGuest2,format=raw,if=none,id=drive-ide0-1-0,\
diff --git a/tests/qemuxml2argvdata/qemuxml2argv-disk-drive-shared.xml b/tests/qemuxml2argvdata/qemuxml2argv-disk-drive-shared.xml
index 9f74723783..677c2b0b7d 100644
--- a/tests/qemuxml2argvdata/qemuxml2argv-disk-drive-shared.xml
+++ b/tests/qemuxml2argvdata/qemuxml2argv-disk-drive-shared.xml
@@ -15,7 +15,7 @@
   <devices>
     <emulator>/usr/bin/qemu-system-i686</emulator>
     <disk type='block' device='disk'>
-      <driver name='qemu' type='qcow2'/>
+      <driver name='qemu' type='raw'/>
       <source dev='/dev/HostVG/QEMUGuest1'/>
       <target dev='hda' bus='ide'/>
       <shareable/>
diff --git a/tests/qemuxml2argvtest.c b/tests/qemuxml2argvtest.c
index 66af2d3285..cb8a964d27 100644
--- a/tests/qemuxml2argvtest.c
+++ b/tests/qemuxml2argvtest.c
@@ -908,6 +908,7 @@ mymain(void)
             QEMU_CAPS_DRIVE_BOOT);
     DO_TEST("disk-drive-shared",
             QEMU_CAPS_DRIVE_SERIAL);
+    DO_TEST_PARSE_ERROR("disk-drive-shared-qcow", NONE);
     DO_TEST("disk-drive-error-policy-stop",
             QEMU_CAPS_MONITOR_JSON);
     DO_TEST("disk-drive-error-policy-enospace",
-- 
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