From 48e646918efb2bf0b3b505747655726d7869f31c Mon Sep 17 00:00:00 2001
From: Colin Walters <walters@redhat.com>
Date: Sat, 30 May 2015 09:06:23 -0400
Subject: CVE-2015-3218: backend: Handle invalid object paths in
RegisterAuthenticationAgent
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Properly propagate the error, otherwise we dereference a `NULL`
pointer. This is a local, authenticated DoS.
`RegisterAuthenticationAgentWithOptions` and
`UnregisterAuthentication` have been validated to not need changes for
this.
http://lists.freedesktop.org/archives/polkit-devel/2015-May/000420.html
https://bugs.freedesktop.org/show_bug.cgi?id=90829
Reported-by: Tavis Ormandy <taviso@google.com>
Reviewed-by: Philip Withnall <philip@tecnocode.co.uk>
Reviewed-by: Miloslav Trmač <mitr@redhat.com>
Signed-off-by: Colin Walters <walters@redhat.com>
diff --git a/src/polkitbackend/polkitbackendinteractiveauthority.c b/src/polkitbackend/polkitbackendinteractiveauthority.c
index f6ea0fc..587f954 100644
--- a/src/polkitbackend/polkitbackendinteractiveauthority.c
+++ b/src/polkitbackend/polkitbackendinteractiveauthority.c
@@ -1566,36 +1566,42 @@ authentication_agent_new (PolkitSubject *scope,
const gchar *unique_system_bus_name,
const gchar *locale,
const gchar *object_path,
- GVariant *registration_options)
+ GVariant *registration_options,
+ GError **error)
{
AuthenticationAgent *agent;
- GError *error;
+ GDBusProxy *proxy;
- agent = g_new0 (AuthenticationAgent, 1);
+ if (!g_variant_is_object_path (object_path))
+ {
+ g_set_error (error, POLKIT_ERROR, POLKIT_ERROR_FAILED,
+ "Invalid object path '%s'", object_path);
+ return NULL;
+ }
+
+ proxy = g_dbus_proxy_new_for_bus_sync (G_BUS_TYPE_SYSTEM,
+ G_DBUS_PROXY_FLAGS_DO_NOT_LOAD_PROPERTIES |
+ G_DBUS_PROXY_FLAGS_DO_NOT_CONNECT_SIGNALS,
+ NULL, /* GDBusInterfaceInfo* */
+ unique_system_bus_name,
+ object_path,
+ "org.freedesktop.PolicyKit1.AuthenticationAgent",
+ NULL, /* GCancellable* */
+ error);
+ if (proxy == NULL)
+ {
+ g_prefix_error (error, "Failed to construct proxy for agent: " );
+ return NULL;
+ }
+ agent = g_new0 (AuthenticationAgent, 1);
agent->ref_count = 1;
agent->scope = g_object_ref (scope);
agent->object_path = g_strdup (object_path);
agent->unique_system_bus_name = g_strdup (unique_system_bus_name);
agent->locale = g_strdup (locale);
agent->registration_options = registration_options != NULL ? g_variant_ref (registration_options) : NULL;
-
- error = NULL;
- agent->proxy = g_dbus_proxy_new_for_bus_sync (G_BUS_TYPE_SYSTEM,
- G_DBUS_PROXY_FLAGS_DO_NOT_LOAD_PROPERTIES |
- G_DBUS_PROXY_FLAGS_DO_NOT_CONNECT_SIGNALS,
- NULL, /* GDBusInterfaceInfo* */
- agent->unique_system_bus_name,
- agent->object_path,
- "org.freedesktop.PolicyKit1.AuthenticationAgent",
- NULL, /* GCancellable* */
- &error);
- if (agent->proxy == NULL)
- {
- g_warning ("Error constructing proxy for agent: %s", error->message);
- g_error_free (error);
- /* TODO: Make authentication_agent_new() return NULL and set a GError */
- }
+ agent->proxy = proxy;
return agent;
}
@@ -2398,8 +2404,6 @@ polkit_backend_interactive_authority_register_authentication_agent (PolkitBacken
caller_cmdline = NULL;
agent = NULL;
- /* TODO: validate that object path is well-formed */
-
interactive_authority = POLKIT_BACKEND_INTERACTIVE_AUTHORITY (authority);
priv = POLKIT_BACKEND_INTERACTIVE_AUTHORITY_GET_PRIVATE (interactive_authority);
@@ -2486,7 +2490,10 @@ polkit_backend_interactive_authority_register_authentication_agent (PolkitBacken
polkit_system_bus_name_get_name (POLKIT_SYSTEM_BUS_NAME (caller)),
locale,
object_path,
- options);
+ options,
+ error);
+ if (!agent)
+ goto out;
g_hash_table_insert (priv->hash_scope_to_authentication_agent,
g_object_ref (subject),
--
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