authz: add QAuthZSimple object type for easy whitelist auth checks

In many cases a single VM will just need to whitelist a single identity
as the allowed user of network services. This is especially the case for
TLS live migration (optionally with NBD storage) where we just need to
whitelist the x509 certificate distinguished name of the source QEMU
host.

Via QMP this can be configured with:

  {
    "execute": "object-add",
    "arguments": {
      "qom-type": "authz-simple",
      "id": "authz0",
      "props": {
        "identity": "fred"
      }
    }
  }

Or via the command line

  -object authz-simple,id=authz0,identity=fred
Reviewed-by: NMarc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: NPhilippe Mathieu-Daudé <philmd@redhat.com>
Tested-by: NPhilippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>

authz/Makefile.objs

 authz-obj-y += base.o
+authz-obj-y += simple.o

authz/simple.c

+/*
+ * QEMU simple authorization driver
+ *
+ * Copyright (c) 2018 Red Hat, Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include "qemu/osdep.h"
+#include "authz/simple.h"
+#include "authz/trace.h"
+#include "qom/object_interfaces.h"
+
+static bool qauthz_simple_is_allowed(QAuthZ *authz,
+                                     const char *identity,
+                                     Error **errp)
+{
+    QAuthZSimple *sauthz = QAUTHZ_SIMPLE(authz);
+
+    trace_qauthz_simple_is_allowed(authz, sauthz->identity, identity);
+    return g_str_equal(identity, sauthz->identity);
+}
+
+static void
+qauthz_simple_prop_set_identity(Object *obj,
+                                const char *value,
+                                Error **errp G_GNUC_UNUSED)
+{
+    QAuthZSimple *sauthz = QAUTHZ_SIMPLE(obj);
+
+    g_free(sauthz->identity);
+    sauthz->identity = g_strdup(value);
+}
+
+
+static char *
+qauthz_simple_prop_get_identity(Object *obj,
+                                Error **errp G_GNUC_UNUSED)
+{
+    QAuthZSimple *sauthz = QAUTHZ_SIMPLE(obj);
+
+    return g_strdup(sauthz->identity);
+}
+
+
+static void
+qauthz_simple_finalize(Object *obj)
+{
+    QAuthZSimple *sauthz = QAUTHZ_SIMPLE(obj);
+
+    g_free(sauthz->identity);
+}
+
+
+static void
+qauthz_simple_class_init(ObjectClass *oc, void *data)
+{
+    QAuthZClass *authz = QAUTHZ_CLASS(oc);
+
+    authz->is_allowed = qauthz_simple_is_allowed;
+
+    object_class_property_add_str(oc, "identity",
+                                  qauthz_simple_prop_get_identity,
+                                  qauthz_simple_prop_set_identity,
+                                  NULL);
+}
+
+
+QAuthZSimple *qauthz_simple_new(const char *id,
+                                const char *identity,
+                                Error **errp)
+{
+    return QAUTHZ_SIMPLE(
+        object_new_with_props(TYPE_QAUTHZ_SIMPLE,
+                              object_get_objects_root(),
+                              id, errp,
+                              "identity", identity,
+                              NULL));
+}
+
+
+static const TypeInfo qauthz_simple_info = {
+    .parent = TYPE_QAUTHZ,
+    .name = TYPE_QAUTHZ_SIMPLE,
+    .instance_size = sizeof(QAuthZSimple),
+    .instance_finalize = qauthz_simple_finalize,
+    .class_size = sizeof(QAuthZSimpleClass),
+    .class_init = qauthz_simple_class_init,
+    .interfaces = (InterfaceInfo[]) {
+        { TYPE_USER_CREATABLE },
+        { }
+    }
+};
+
+
+static void
+qauthz_simple_register_types(void)
+{
+    type_register_static(&qauthz_simple_info);
+}
+
+
+type_init(qauthz_simple_register_types);

authz/trace-events

@@ -2,3 +2,6 @@
 
 # authz/base.c
 qauthz_is_allowed(void *authz, const char *identity, bool allowed) "AuthZ %p check identity=%s allowed=%d"
+
+# auth/simple.c
+qauthz_simple_is_allowed(void *authz, const char *wantidentity, const char *gotidentity) "AuthZ simple %p check want identity=%s got identity=%s"

include/authz/simple.h

+/*
+ * QEMU simple authorization driver
+ *
+ * Copyright (c) 2018 Red Hat, Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#ifndef QAUTHZ_SIMPLE_H__
+#define QAUTHZ_SIMPLE_H__
+
+#include "authz/base.h"
+
+#define TYPE_QAUTHZ_SIMPLE "authz-simple"
+
+#define QAUTHZ_SIMPLE_CLASS(klass)                        \
+    OBJECT_CLASS_CHECK(QAuthZSimpleClass, (klass),        \
+                       TYPE_QAUTHZ_SIMPLE)
+#define QAUTHZ_SIMPLE_GET_CLASS(obj)              \
+    OBJECT_GET_CLASS(QAuthZSimpleClass, (obj),    \
+                      TYPE_QAUTHZ_SIMPLE)
+#define QAUTHZ_SIMPLE(obj) \
+    INTERFACE_CHECK(QAuthZSimple, (obj),          \
+                    TYPE_QAUTHZ_SIMPLE)
+
+typedef struct QAuthZSimple QAuthZSimple;
+typedef struct QAuthZSimpleClass QAuthZSimpleClass;
+
+
+/**
+ * QAuthZSimple:
+ *
+ * This authorization driver provides a simple mechanism
+ * for granting access based on an exact matched username.
+ *
+ * To create an instance of this class via QMP:
+ *
+ *  {
+ *    "execute": "object-add",
+ *    "arguments": {
+ *      "qom-type": "authz-simple",
+ *      "id": "authz0",
+ *      "props": {
+ *        "identity": "fred"
+ *      }
+ *    }
+ *  }
+ *
+ * Or via the command line
+ *
+ *   -object authz-simple,id=authz0,identity=fred
+ *
+ */
+struct QAuthZSimple {
+    QAuthZ parent_obj;
+
+    char *identity;
+};
+
+
+struct QAuthZSimpleClass {
+    QAuthZClass parent_class;
+};
+
+
+QAuthZSimple *qauthz_simple_new(const char *id,
+                                const char *identity,
+                                Error **errp);
+
+
+#endif /* QAUTHZ_SIMPLE_H__ */
+

qemu-options.hx

@@ -4365,6 +4365,30 @@ e.g to launch a SEV guest
      .....
 
 @end example
+
+
+@item -object authz-simple,id=@var{id},identity=@var{string}
+
+Create an authorization object that will control access to network services.
+
+The @option{identity} parameter is identifies the user and its format
+depends on the network service that authorization object is associated
+with. For authorizing based on TLS x509 certificates, the identity must
+be the x509 distinguished name. Note that care must be taken to escape
+any commas in the distinguished name.
+
+An example authorization object to validate a x509 distinguished name
+would look like:
+@example
+ # $QEMU \
+     ...
+     -object 'authz-simple,id=auth0,identity=CN=laptop.example.com,,O=Example Org,,L=London,,ST=London,,C=GB' \
+     ...
+@end example
+
+Note the use of quotes due to the x509 distinguished name containing
+whitespace, and escaping of ','.
+
 @end table
 
 ETEXI

tests/Makefile.include

@@ -116,6 +116,7 @@ endif
 check-unit-y += tests/test-timed-average$(EXESUF)
 check-unit-$(CONFIG_INOTIFY1) += tests/test-util-filemonitor$(EXESUF)
 check-unit-y += tests/test-util-sockets$(EXESUF)
+check-unit-y += tests/test-authz-simple$(EXESUF)
 check-unit-y += tests/test-io-task$(EXESUF)
 check-unit-y += tests/test-io-channel-socket$(EXESUF)
 check-unit-y += tests/test-io-channel-file$(EXESUF)
@@ -536,6 +537,7 @@ test-qapi-obj-y = tests/test-qapi-visit.o tests/test-qapi-types.o \
 benchmark-crypto-obj-y = $(crypto-obj-y) $(test-qom-obj-y)
 test-crypto-obj-y = $(crypto-obj-y) $(test-qom-obj-y)
 test-io-obj-y = $(io-obj-y) $(test-crypto-obj-y)
+test-authz-obj-y = $(test-qom-obj-y) $(authz-obj-y)
 test-block-obj-y = $(block-obj-y) $(test-io-obj-y) tests/iothread.o
 
 tests/check-qnum$(EXESUF): tests/check-qnum.o $(test-util-obj-y)
@@ -662,6 +664,7 @@ tests/test-util-filemonitor$(EXESUF): tests/test-util-filemonitor.o \
 	$(test-util-obj-y)
 tests/test-util-sockets$(EXESUF): tests/test-util-sockets.o \
 	tests/socket-helpers.o $(test-util-obj-y)
+tests/test-authz-simple$(EXESUF): tests/test-authz-simple.o $(test-authz-obj-y)
 tests/test-io-task$(EXESUF): tests/test-io-task.o $(test-io-obj-y)
 tests/test-io-channel-socket$(EXESUF): tests/test-io-channel-socket.o \
         tests/io-channel-helpers.o tests/socket-helpers.o $(test-io-obj-y)

tests/test-authz-simple.c

+/*
+ * QEMU simple authorization object testing
+ *
+ * Copyright (c) 2018 Red Hat, Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include "qemu/osdep.h"
+#include "qapi/error.h"
+
+#include "authz/simple.h"
+
+
+static void test_authz_simple(void)
+{
+    QAuthZSimple *authz = qauthz_simple_new("authz0",
+                                            "cthulu",
+                                            &error_abort);
+
+    g_assert(!qauthz_is_allowed(QAUTHZ(authz), "cthul", &error_abort));
+    g_assert(qauthz_is_allowed(QAUTHZ(authz), "cthulu", &error_abort));
+    g_assert(!qauthz_is_allowed(QAUTHZ(authz), "cthuluu", &error_abort));
+    g_assert(!qauthz_is_allowed(QAUTHZ(authz), "fred", &error_abort));
+
+    object_unparent(OBJECT(authz));
+}
+
+
+int main(int argc, char **argv)
+{
+    g_test_init(&argc, &argv, NULL);
+    module_call_init(MODULE_INIT_QOM);
+
+    g_test_add_func("/authz/simple", test_authz_simple);
+
+    return g_test_run();
+}