security, apparmor: add (Set|Restore)InputLabel

d8116b5a "security: Introduce functions for input device hot(un)plug"
implemented the code (Set|Restore)InputLabel for several security modules,
this patch adds an AppArmor implementation for it as well.

That fixes hot-plugging event input devices by generating a rule for the
path that needs to be accessed.

Example hot adding:
  <input type='passthrough' bus='virtio'>
     <source evdev='/dev/input/event0' />
  </input>
Creates now:
  "/dev/input/event0" rwk,

Fixes: https://bugs.launchpad.net/ubuntu/+source/libvirt/+bug/1755153Acked-by: NJamie Strandboge <jamie@canonical.com>
Signed-off-by: NChristian Ehrhardt <christian.ehrhardt@canonical.com>

src/security/security_apparmor.c

@@ -759,6 +759,51 @@ AppArmorRestoreMemoryLabel(virSecurityManagerPtr mgr,
     return reload_profile(mgr, def, NULL, false);
 }
 
+/* Called when hotplugging */
+static int
+AppArmorSetInputLabel(virSecurityManagerPtr mgr,
+                      virDomainDefPtr def,
+                      virDomainInputDefPtr input)
+{
+    if (input == NULL)
+        return 0;
+
+    switch ((virDomainInputType) input->type) {
+    case VIR_DOMAIN_INPUT_TYPE_PASSTHROUGH:
+        if (input->source.evdev == NULL) {
+            virReportError(VIR_ERR_INTERNAL_ERROR,
+                           _("%s: passthrough input device has no source"),
+                           __func__);
+            return -1;
+        }
+        if (!virFileExists(input->source.evdev)) {
+            virReportError(VIR_ERR_INTERNAL_ERROR,
+                           _("%s: \'%s\' does not exist"),
+                           __func__, input->source.evdev);
+            return -1;
+        }
+        return reload_profile(mgr, def, input->source.evdev, true);
+        break;
+
+    case VIR_DOMAIN_INPUT_TYPE_MOUSE:
+    case VIR_DOMAIN_INPUT_TYPE_TABLET:
+    case VIR_DOMAIN_INPUT_TYPE_KBD:
+    case VIR_DOMAIN_INPUT_TYPE_LAST:
+        break;
+    }
+
+    return 0;
+}
+
+
+static int
+AppArmorRestoreInputLabel(virSecurityManagerPtr mgr,
+                          virDomainDefPtr def,
+                          virDomainInputDefPtr input ATTRIBUTE_UNUSED)
+{
+    return reload_profile(mgr, def, NULL, false);
+}
+
 /* Called when hotplugging */
 static int
 AppArmorSetSecurityImageLabel(virSecurityManagerPtr mgr,
@@ -1161,6 +1206,9 @@ virSecurityDriver virAppArmorSecurityDriver = {
     .domainSetSecurityMemoryLabel       = AppArmorSetMemoryLabel,
     .domainRestoreSecurityMemoryLabel   = AppArmorRestoreMemoryLabel,
 
+    .domainSetSecurityInputLabel        = AppArmorSetInputLabel,
+    .domainRestoreSecurityInputLabel    = AppArmorRestoreInputLabel,
+
     .domainSetSecurityDaemonSocketLabel = AppArmorSetSecurityDaemonSocketLabel,
     .domainSetSecuritySocketLabel       = AppArmorSetSecuritySocketLabel,
     .domainClearSecuritySocketLabel     = AppArmorClearSecuritySocketLabel,