authz: add QAuthZ object as an authorization base class

The current qemu_acl module provides a simple access control list
facility inside QEMU, which is used via a set of monitor commands
acl_show, acl_policy, acl_add, acl_remove & acl_reset.

Note there is no ability to create ACLs - the network services (eg VNC
server) were expected to create ACLs that they want to check.

There is also no way to define ACLs on the command line, nor potentially
integrate with external authorization systems like polkit, pam, ldap
lookup, etc.

The QAuthZ object defines a minimal abstract QOM class that can be
subclassed for creating different authorization providers.

Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Tested-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>

3 files changed, 87 insertions, 0 deletions

diff --git a/authz/Makefile.objs b/authz/Makefile.objs
new file mode 100644
index 0000000000..12597c9528
--- /dev/null
+++ b/authz/Makefile.objs
@@ -0,0 +1 @@
+authz-obj-y += base.o
diff --git a/authz/base.c b/authz/base.c
new file mode 100644
index 0000000000..110dfa4195
--- /dev/null
+++ b/authz/base.c
@@ -0,0 +1,82 @@
+/*
+ * QEMU authorization framework base class
+ *
+ * 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/base.h"
+#include "authz/trace.h"
+
+bool qauthz_is_allowed(QAuthZ *authz,
+                       const char *identity,
+                       Error **errp)
+{
+    QAuthZClass *cls = QAUTHZ_GET_CLASS(authz);
+    bool allowed;
+
+    allowed = cls->is_allowed(authz, identity, errp);
+    trace_qauthz_is_allowed(authz, identity, allowed);
+
+    return allowed;
+}
+
+
+bool qauthz_is_allowed_by_id(const char *authzid,
+                             const char *identity,
+                             Error **errp)
+{
+    QAuthZ *authz;
+    Object *obj;
+    Object *container;
+
+    container = object_get_objects_root();
+    obj = object_resolve_path_component(container,
+                                        authzid);
+    if (!obj) {
+        error_setg(errp, "Cannot find QAuthZ object ID %s",
+                   authzid);
+        return false;
+    }
+
+    if (!object_dynamic_cast(obj, TYPE_QAUTHZ)) {
+        error_setg(errp, "Object '%s' is not a QAuthZ subclass",
+                   authzid);
+        return false;
+    }
+
+    authz = QAUTHZ(obj);
+
+    return qauthz_is_allowed(authz, identity, errp);
+}
+
+
+static const TypeInfo authz_info = {
+    .parent = TYPE_OBJECT,
+    .name = TYPE_QAUTHZ,
+    .instance_size = sizeof(QAuthZ),
+    .class_size = sizeof(QAuthZClass),
+    .abstract = true,
+};
+
+static void qauthz_register_types(void)
+{
+    type_register_static(&authz_info);
+}
+
+type_init(qauthz_register_types)
+
diff --git a/authz/trace-events b/authz/trace-events
new file mode 100644
index 0000000000..481c90f511
--- /dev/null
+++ b/authz/trace-events
@@ -0,0 +1,4 @@
+# See docs/devel/tracing.txt for syntax documentation.
+
+# authz/base.c
+qauthz_is_allowed(void *authz, const char *identity, bool allowed) "AuthZ %p check identity=%s allowed=%d"