authz: add QAuthZList object type for an access control list

Add a QAuthZList object type that implements the QAuthZ interface. This
built-in implementation maintains a trivial access control list with a
sequence of match rules and a final default policy. This replicates the
functionality currently provided by the qemu_acl module.

To create an instance of this object via the QMP monitor, the syntax
used would be:

  {
    "execute": "object-add",
    "arguments": {
      "qom-type": "authz-list",
      "id": "authz0",
      "props": {
        "rules": [
           { "match": "fred", "policy": "allow", "format": "exact" },
           { "match": "bob", "policy": "allow", "format": "exact" },
           { "match": "danb", "policy": "deny", "format": "glob" },
           { "match": "dan*", "policy": "allow", "format": "exact" },
        ],
        "policy": "deny"
      }
    }
  }

This sets up an authorization rule that allows 'fred', 'bob' and anyone
whose name starts with 'dan', except for 'danb'. Everyone unmatched is
denied.

It is not currently possible to create this via -object, since there is
no syntax supported to specify non-scalar properties for objects. This
is likely to be addressed by later support for using JSON with -object,
or an equivalent approach.

In any case the future "authz-listfile" object can be used from the
CLI and is likely a better choice, as it allows the ACL to be refreshed
automatically on change.

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>

1 files changed, 271 insertions, 0 deletions

diff --git a/authz/list.c b/authz/list.c
new file mode 100644
index 0000000000..dc6b0fec13
--- /dev/null
+++ b/authz/list.c
@@ -0,0 +1,271 @@
+/*
+ * QEMU access control list 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/list.h"
+#include "authz/trace.h"
+#include "qom/object_interfaces.h"
+#include "qapi/qapi-visit-authz.h"
+
+static bool qauthz_list_is_allowed(QAuthZ *authz,
+                                   const char *identity,
+                                   Error **errp)
+{
+    QAuthZList *lauthz = QAUTHZ_LIST(authz);
+    QAuthZListRuleList *rules = lauthz->rules;
+
+    while (rules) {
+        QAuthZListRule *rule = rules->value;
+        QAuthZListFormat format = rule->has_format ? rule->format :
+            QAUTHZ_LIST_FORMAT_EXACT;
+
+        trace_qauthz_list_check_rule(authz, rule->match, identity,
+                                     format, rule->policy);
+        switch (format) {
+        case QAUTHZ_LIST_FORMAT_EXACT:
+            if (g_str_equal(rule->match, identity)) {
+                return rule->policy == QAUTHZ_LIST_POLICY_ALLOW;
+            }
+            break;
+        case QAUTHZ_LIST_FORMAT_GLOB:
+            if (g_pattern_match_simple(rule->match, identity)) {
+                return rule->policy == QAUTHZ_LIST_POLICY_ALLOW;
+            }
+            break;
+        default:
+            g_warn_if_reached();
+            return false;
+        }
+        rules = rules->next;
+    }
+
+    trace_qauthz_list_default_policy(authz, identity, lauthz->policy);
+    return lauthz->policy == QAUTHZ_LIST_POLICY_ALLOW;
+}
+
+
+static void
+qauthz_list_prop_set_policy(Object *obj,
+                            int value,
+                            Error **errp G_GNUC_UNUSED)
+{
+    QAuthZList *lauthz = QAUTHZ_LIST(obj);
+
+    lauthz->policy = value;
+}
+
+
+static int
+qauthz_list_prop_get_policy(Object *obj,
+                            Error **errp G_GNUC_UNUSED)
+{
+    QAuthZList *lauthz = QAUTHZ_LIST(obj);
+
+    return lauthz->policy;
+}
+
+
+static void
+qauthz_list_prop_get_rules(Object *obj, Visitor *v, const char *name,
+                           void *opaque, Error **errp)
+{
+    QAuthZList *lauthz = QAUTHZ_LIST(obj);
+
+    visit_type_QAuthZListRuleList(v, name, &lauthz->rules, errp);
+}
+
+static void
+qauthz_list_prop_set_rules(Object *obj, Visitor *v, const char *name,
+                           void *opaque, Error **errp)
+{
+    QAuthZList *lauthz = QAUTHZ_LIST(obj);
+    QAuthZListRuleList *oldrules;
+
+    oldrules = lauthz->rules;
+    visit_type_QAuthZListRuleList(v, name, &lauthz->rules, errp);
+
+    qapi_free_QAuthZListRuleList(oldrules);
+}
+
+
+static void
+qauthz_list_finalize(Object *obj)
+{
+    QAuthZList *lauthz = QAUTHZ_LIST(obj);
+
+    qapi_free_QAuthZListRuleList(lauthz->rules);
+}
+
+
+static void
+qauthz_list_class_init(ObjectClass *oc, void *data)
+{
+    QAuthZClass *authz = QAUTHZ_CLASS(oc);
+
+    object_class_property_add_enum(oc, "policy",
+                                   "QAuthZListPolicy",
+                                   &QAuthZListPolicy_lookup,
+                                   qauthz_list_prop_get_policy,
+                                   qauthz_list_prop_set_policy,
+                                   NULL);
+
+    object_class_property_add(oc, "rules", "QAuthZListRule",
+                              qauthz_list_prop_get_rules,
+                              qauthz_list_prop_set_rules,
+                              NULL, NULL, NULL);
+
+    authz->is_allowed = qauthz_list_is_allowed;
+}
+
+
+QAuthZList *qauthz_list_new(const char *id,
+                            QAuthZListPolicy policy,
+                            Error **errp)
+{
+    return QAUTHZ_LIST(
+        object_new_with_props(TYPE_QAUTHZ_LIST,
+                              object_get_objects_root(),
+                              id, errp,
+                              "policy", QAuthZListPolicy_str(policy),
+                              NULL));
+}
+
+ssize_t qauthz_list_append_rule(QAuthZList *auth,
+                                const char *match,
+                                QAuthZListPolicy policy,
+                                QAuthZListFormat format,
+                                Error **errp)
+{
+    QAuthZListRule *rule;
+    QAuthZListRuleList *rules, *tmp;
+    size_t i = 0;
+
+    rule = g_new0(QAuthZListRule, 1);
+    rule->policy = policy;
+    rule->match = g_strdup(match);
+    rule->format = format;
+    rule->has_format = true;
+
+    tmp = g_new0(QAuthZListRuleList, 1);
+    tmp->value = rule;
+
+    rules = auth->rules;
+    if (rules) {
+        while (rules->next) {
+            i++;
+            rules = rules->next;
+        }
+        rules->next = tmp;
+        return i + 1;
+    } else {
+        auth->rules = tmp;
+        return 0;
+    }
+}
+
+
+ssize_t qauthz_list_insert_rule(QAuthZList *auth,
+                                const char *match,
+                                QAuthZListPolicy policy,
+                                QAuthZListFormat format,
+                                size_t index,
+                                Error **errp)
+{
+    QAuthZListRule *rule;
+    QAuthZListRuleList *rules, *tmp;
+    size_t i = 0;
+
+    rule = g_new0(QAuthZListRule, 1);
+    rule->policy = policy;
+    rule->match = g_strdup(match);
+    rule->format = format;
+    rule->has_format = true;
+
+    tmp = g_new0(QAuthZListRuleList, 1);
+    tmp->value = rule;
+
+    rules = auth->rules;
+    if (rules && index > 0) {
+        while (rules->next && i < (index - 1)) {
+            i++;
+            rules = rules->next;
+        }
+        tmp->next = rules->next;
+        rules->next = tmp;
+        return i + 1;
+    } else {
+        tmp->next = auth->rules;
+        auth->rules = tmp;
+        return 0;
+    }
+}
+
+
+ssize_t qauthz_list_delete_rule(QAuthZList *auth, const char *match)
+{
+    QAuthZListRule *rule;
+    QAuthZListRuleList *rules, *prev;
+    size_t i = 0;
+
+    prev = NULL;
+    rules = auth->rules;
+    while (rules) {
+        rule = rules->value;
+        if (g_str_equal(rule->match, match)) {
+            if (prev) {
+                prev->next = rules->next;
+            } else {
+                auth->rules = rules->next;
+            }
+            rules->next = NULL;
+            qapi_free_QAuthZListRuleList(rules);
+            return i;
+        }
+        prev = rules;
+        rules = rules->next;
+        i++;
+    }
+
+    return -1;
+}
+
+
+static const TypeInfo qauthz_list_info = {
+    .parent = TYPE_QAUTHZ,
+    .name = TYPE_QAUTHZ_LIST,
+    .instance_size = sizeof(QAuthZList),
+    .instance_finalize = qauthz_list_finalize,
+    .class_size = sizeof(QAuthZListClass),
+    .class_init = qauthz_list_class_init,
+    .interfaces = (InterfaceInfo[]) {
+        { TYPE_USER_CREATABLE },
+        { }
+    }
+};
+
+
+static void
+qauthz_list_register_types(void)
+{
+    type_register_static(&qauthz_list_info);
+}
+
+
+type_init(qauthz_list_register_types);