From 9e074421d5623b6962dc66994d519012b40334b9 Mon Sep 17 00:00:00 2001 From: Colin Walters Date: Sat, 30 May 2015 09:06:23 -0400 Subject: [PATCH] backend: Handle invalid object paths in RegisterAuthenticationAgent Properly propagate the error, otherwise we dereference a `NULL` pointer. This is a local, authenticated DoS. Reported-by: Tavis Ormandy Signed-off-by: Colin Walters --- .../polkitbackendinteractiveauthority.c | 53 ++++++++++++---------- 1 file changed, 30 insertions(+), 23 deletions(-) diff --git a/src/polkitbackend/polkitbackendinteractiveauthority.c b/src/polkitbackend/polkitbackendinteractiveauthority.c index 59028d5..f45fdf1 100644 --- a/src/polkitbackend/polkitbackendinteractiveauthority.c +++ b/src/polkitbackend/polkitbackendinteractiveauthority.c @@ -1551,36 +1551,42 @@ 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; } @@ -2383,8 +2389,6 @@ 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); @@ -2471,7 +2475,10 @@ 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), -- 1.8.3.1