api: disallow virConnectGetDomainCapabilities on read-only connections

This API can be used to execute arbitrary emulators.
Forbid it on read-only connections.

Fixes: CVE-2019-10167
Signed-off-by: Ján Tomko <jtomko@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
(cherry picked from commit 8afa68bac0)
Signed-off-by: Ján Tomko <jtomko@redhat.com>

src/admin/admin_server_dispatch.c

@@ -66,6 +66,28 @@ remoteAdmClientNew(virNetServerClientPtr client ATTRIBUTE_UNUSED,
                    void *opaque)
 {
     struct daemonAdmClientPrivate *priv;
+    uid_t clientuid;
+    gid_t clientgid;
+    pid_t clientpid;
+    unsigned long long timestamp;
+
+    if (virNetServerClientGetUNIXIdentity(client,
+                                          &clientuid,
+                                          &clientgid,
+                                          &clientpid,
+                                          &timestamp) < 0)
+        return NULL;
+
+    VIR_DEBUG("New client pid %lld uid %lld",
+              (long long)clientpid,
+              (long long)clientuid);
+
+    if (geteuid() != clientuid) {
+        virReportRestrictedError(_("Disallowing client %lld with uid %lld"),
+                                 (long long)clientpid,
+                                 (long long)clientuid);
+        return NULL;
+    }
 
     if (VIR_ALLOC(priv) < 0)
         return NULL;

src/libvirt-domain.c

@@ -1073,9 +1073,7 @@ virDomainRestoreFlags(virConnectPtr conn, const char *from, const char *dxml,
  * previously by virDomainSave() or virDomainSaveFlags().
  *
  * No security-sensitive data will be included unless @flags contains
- * VIR_DOMAIN_XML_SECURE; this flag is rejected on read-only
- * connections.  For this API, @flags should not contain either
- * VIR_DOMAIN_XML_INACTIVE or VIR_DOMAIN_XML_UPDATE_CPU.
+ * VIR_DOMAIN_XML_SECURE.
  *
  * Returns a 0 terminated UTF-8 encoded XML instance, or NULL in case of
  * error.  The caller must free() the returned value.
@@ -1091,12 +1089,7 @@ virDomainSaveImageGetXMLDesc(virConnectPtr conn, const char *file,
 
     virCheckConnectReturn(conn, NULL);
     virCheckNonNullArgGoto(file, error);
-
-    if ((conn->flags & VIR_CONNECT_RO) && (flags & VIR_DOMAIN_XML_SECURE)) {
-        virReportError(VIR_ERR_OPERATION_DENIED, "%s",
-                       _("virDomainSaveImageGetXMLDesc with secure flag"));
-        goto error;
-    }
+    virCheckReadOnlyGoto(conn->flags, error);
 
     if (conn->driver->domainSaveImageGetXMLDesc) {
         char *ret;
@@ -9431,6 +9424,7 @@ virDomainManagedSaveDefineXML(virDomainPtr domain, const char *dxml,
 
     virCheckDomainReturn(domain, -1);
     conn = domain->conn;
+    virCheckReadOnlyGoto(conn->flags, error);
 
     if (conn->driver->domainManagedSaveDefineXML) {
         int ret;
@@ -11222,6 +11216,7 @@ virConnectGetDomainCapabilities(virConnectPtr conn,
     virResetLastError();
 
     virCheckConnectReturn(conn, NULL);
+    virCheckReadOnlyGoto(conn->flags, error);
 
     if (conn->driver->connectGetDomainCapabilities) {
         char *ret;

src/locking/virtlockd-admin.socket.in

@@ -5,6 +5,7 @@ Before=libvirtd.service
 [Socket]
 ListenStream=@localstatedir@/run/libvirt/virtlockd-admin-sock
 Service=virtlockd.service
+SocketMode=0600
 
 [Install]
 WantedBy=sockets.target

src/locking/virtlockd.socket.in

@@ -4,6 +4,7 @@ Before=libvirtd.service
 
 [Socket]
 ListenStream=@localstatedir@/run/libvirt/virtlockd-sock
+SocketMode=0600
 
 [Install]
 WantedBy=sockets.target

src/logging/virtlogd-admin.socket.in

@@ -5,6 +5,7 @@ Before=libvirtd.service
 [Socket]
 ListenStream=@localstatedir@/run/libvirt/virtlogd-admin-sock
 Service=virtlogd.service
+SocketMode=0600
 
 [Install]
 WantedBy=sockets.target

src/logging/virtlogd.socket.in

@@ -4,6 +4,7 @@ Before=libvirtd.service
 
 [Socket]
 ListenStream=@localstatedir@/run/libvirt/virtlogd-sock
+SocketMode=0600
 
 [Install]
 WantedBy=sockets.target

src/qemu/qemu_driver.c

@@ -6798,7 +6798,7 @@ qemuDomainSaveImageGetXMLDesc(virConnectPtr conn, const char *path,
     if (fd < 0)
         goto cleanup;
 
-    if (virDomainSaveImageGetXMLDescEnsureACL(conn, def, flags) < 0)
+    if (virDomainSaveImageGetXMLDescEnsureACL(conn, def) < 0)
         goto cleanup;
 
     ret = qemuDomainDefFormatXML(driver, def, flags);

src/remote/remote_protocol.x

@@ -5117,8 +5117,7 @@ enum remote_procedure {
     /**
      * @generate: both
      * @priority: high
-     * @acl: domain:read
-     * @acl: domain:read_secure:VIR_DOMAIN_XML_SECURE
+     * @acl: domain:write
      */
     REMOTE_PROC_DOMAIN_SAVE_IMAGE_GET_XML_DESC = 235,