qemu_hotplug: Relabel memdev

Now that we have APIs for relabel memdevs on hotplug, fill in the
missing implementation in qemu hotplug code.

The qemuSecurity wrappers might look like overkill for now,
because qemu namespace code does not deal with the nvdimms yet.
Nor does our cgroup code.  But hey, there's cgroup_device_acl
variable in qemu.conf. If users add their /dev/pmem* device in
there, the device is allowed in cgroups and created in the
namespace so they can successfully passthrough it to the domain.
It doesn't look like overkill after all, does it?

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>

src/qemu/qemu_hotplug.c

@@ -2215,6 +2215,7 @@ qemuDomainAttachMemory(virQEMUDriverPtr driver,
     char *objalias = NULL;
     const char *backendType;
     bool objAdded = false;
+    bool teardownlabel = false;
     virJSONValuePtr props = NULL;
     virObjectEventPtr event;
     int id;
@@ -2244,15 +2245,15 @@ qemuDomainAttachMemory(virQEMUDriverPtr driver,
                                   priv->qemuCaps, vm->def, mem, NULL, true) < 0)
         goto cleanup;
 
-    if (virDomainMemoryInsert(vm->def, mem) < 0) {
-        virJSONValueFree(props);
+    if (qemuSecuritySetMemoryLabel(driver, vm, mem) < 0)
         goto cleanup;
-    }
+    teardownlabel = true;
 
-    if (qemuDomainAdjustMaxMemLock(vm) < 0) {
-        virJSONValueFree(props);
+    if (virDomainMemoryInsert(vm->def, mem) < 0)
+        goto cleanup;
+
+    if (qemuDomainAdjustMaxMemLock(vm) < 0)
         goto removedef;
-    }
 
     qemuDomainObjEnterMonitor(driver, vm);
     rv = qemuMonitorAddObject(priv->mon, backendType, objalias, props);
@@ -2288,6 +2289,12 @@ qemuDomainAttachMemory(virQEMUDriverPtr driver,
  audit:
     virDomainAuditMemory(vm, oldmem, newmem, "update", ret == 0);
  cleanup:
+    if (mem && ret < 0) {
+        if (teardownlabel && qemuSecurityRestoreMemoryLabel(driver, vm, mem) < 0)
+            VIR_WARN("Unable to restore security label on memdev");
+    }
+
+    virJSONValueFree(props);
     virObjectUnref(cfg);
     VIR_FREE(devstr);
     VIR_FREE(objalias);
@@ -3748,6 +3755,9 @@ qemuDomainRemoveMemoryDevice(virQEMUDriverPtr driver,
     if ((idx = virDomainMemoryFindByDef(vm->def, mem)) >= 0)
         virDomainMemoryRemove(vm->def, idx);
 
+    if (qemuSecurityRestoreMemoryLabel(driver, vm, mem) < 0)
+        VIR_WARN("Unable to restore security label on memdev");
+
     virDomainMemoryDefFree(mem);
 
     /* fix the balloon size */

src/qemu/qemu_security.c

@@ -245,3 +245,59 @@ qemuSecurityRestoreHostdevLabel(virQEMUDriverPtr driver,
     virSecurityManagerTransactionAbort(driver->securityManager);
     return ret;
 }
+
+
+int
+qemuSecuritySetMemoryLabel(virQEMUDriverPtr driver,
+                           virDomainObjPtr vm,
+                           virDomainMemoryDefPtr mem)
+{
+    int ret = -1;
+
+    if (qemuDomainNamespaceEnabled(vm, QEMU_DOMAIN_NS_MOUNT) &&
+        virSecurityManagerTransactionStart(driver->securityManager) < 0)
+        goto cleanup;
+
+    if (virSecurityManagerSetMemoryLabel(driver->securityManager,
+                                         vm->def,
+                                         mem) < 0)
+        goto cleanup;
+
+    if (qemuDomainNamespaceEnabled(vm, QEMU_DOMAIN_NS_MOUNT) &&
+        virSecurityManagerTransactionCommit(driver->securityManager,
+                                            vm->pid) < 0)
+        goto cleanup;
+
+    ret = 0;
+ cleanup:
+    virSecurityManagerTransactionAbort(driver->securityManager);
+    return ret;
+}
+
+
+int
+qemuSecurityRestoreMemoryLabel(virQEMUDriverPtr driver,
+                               virDomainObjPtr vm,
+                               virDomainMemoryDefPtr mem)
+{
+    int ret = -1;
+
+    if (qemuDomainNamespaceEnabled(vm, QEMU_DOMAIN_NS_MOUNT) &&
+        virSecurityManagerTransactionStart(driver->securityManager) < 0)
+        goto cleanup;
+
+    if (virSecurityManagerRestoreMemoryLabel(driver->securityManager,
+                                             vm->def,
+                                             mem) < 0)
+        goto cleanup;
+
+    if (qemuDomainNamespaceEnabled(vm, QEMU_DOMAIN_NS_MOUNT) &&
+        virSecurityManagerTransactionCommit(driver->securityManager,
+                                            vm->pid) < 0)
+        goto cleanup;
+
+    ret = 0;
+ cleanup:
+    virSecurityManagerTransactionAbort(driver->securityManager);
+    return ret;
+}

src/qemu/qemu_security.h

@@ -62,6 +62,14 @@ int qemuSecurityRestoreHostdevLabel(virQEMUDriverPtr driver,
                                     virDomainObjPtr vm,
                                     virDomainHostdevDefPtr hostdev);
 
+int qemuSecuritySetMemoryLabel(virQEMUDriverPtr driver,
+                               virDomainObjPtr vm,
+                               virDomainMemoryDefPtr mem);
+
+int qemuSecurityRestoreMemoryLabel(virQEMUDriverPtr driver,
+                                   virDomainObjPtr vm,
+                                   virDomainMemoryDefPtr mem);
+
 /* Please note that for these APIs there is no wrapper yet. Do NOT blindly add
  * new APIs here. If an API can touch a /dev file add a proper wrapper instead.
  */