test: Add basic test coverage for DBUS_COOKIE_SHA1

We don't actually complete successful authentication, because that
would require us to generate a cookie and compute the correct SHA1,
which is difficult to do in a deterministic authentication script.
However, we do assert that dbus#269 (CVE-2019-12749) has been fixed.

Signed-off-by: Simon McVittie <smcv@collabora.com>

test/Makefile.am

@@ -630,6 +630,8 @@ static_data = \
 	data/auth/anonymous-server-successful.auth-script \
 	data/auth/cancel.auth-script \
 	data/auth/client-out-of-mechanisms.auth-script \
+	data/auth/cookie-sha1-username.auth-script \
+	data/auth/cookie-sha1.auth-script \
 	data/auth/external-auto.auth-script \
 	data/auth/external-failed.auth-script \
 	data/auth/external-root.auth-script \

test/data/auth/cookie-sha1-username.auth-script

@@ -0,0 +1,12 @@
+UNIX_ONLY
+SERVER
+SEND 'AUTH DBUS_COOKIE_SHA1 WRONG_USERNAME_HEX'
+EXPECT_COMMAND REJECTED
+EXPECT_STATE WAITING_FOR_INPUT
+EXPECT_HAVE_NO_CREDENTIALS
+SEND 'AUTH DBUS_COOKIE_SHA1 USERNAME_HEX'
+EXPECT_COMMAND DATA
+EXPECT_STATE WAITING_FOR_INPUT
+EXPECT_HAVE_NO_CREDENTIALS
+# We don't actually complete DBUS_COOKIE_SHA1 authentication, because
+# it's non-trivial.

test/data/auth/cookie-sha1.auth-script

@@ -0,0 +1,11 @@
+SERVER
+SEND 'AUTH DBUS_COOKIE_SHA1 WRONG_USERID_HEX'
+EXPECT_COMMAND REJECTED
+EXPECT_STATE WAITING_FOR_INPUT
+EXPECT_HAVE_NO_CREDENTIALS
+SEND 'AUTH DBUS_COOKIE_SHA1 USERID_HEX'
+EXPECT_COMMAND DATA
+EXPECT_STATE WAITING_FOR_INPUT
+EXPECT_HAVE_NO_CREDENTIALS
+# We don't actually complete DBUS_COOKIE_SHA1 authentication, because
+# it's non-trivial.

test/internals/dbus-auth-script.c

@@ -41,6 +41,8 @@
 # include "dbus/dbus-userdb.h"
 #endif
 
+#include "test/test-utils.h"
+
 /**
  * @defgroup DBusAuthScript code for running unit test scripts for DBusAuth
  * @ingroup  DBusInternals
@@ -526,8 +528,36 @@ _dbus_auth_script_run (const DBusString *filename)
           {
             int where;
 
-            if (_dbus_string_find (&to_send, 0,
-                                   "USERID_HEX", &where))
+            if (_dbus_string_find (&to_send, 0, "WRONG_USERID_HEX", &where))
+              {
+                /* This must be checked for before USERID_HEX, because
+                 * that's a substring. */
+                DBusString uid = _DBUS_STRING_INIT_INVALID;
+
+                if (!_dbus_string_init (&uid) ||
+                    !_dbus_test_append_different_uid (&uid))
+                  {
+                    _dbus_warn ("no memory for uid");
+                    _dbus_string_free (&to_send);
+                    _dbus_string_free (&uid);
+                    goto out;
+                  }
+
+                _dbus_string_delete (&to_send, where,
+                                     (int) strlen ("WRONG_USERID_HEX"));
+
+                if (!_dbus_string_hex_encode (&uid, 0, &to_send, where))
+                  {
+                    _dbus_warn ("no memory to subst WRONG_USERID_HEX");
+                    _dbus_string_free (&to_send);
+                    _dbus_string_free (&uid);
+                    goto out;
+                  }
+
+                _dbus_string_free (&uid);
+              }
+            else if (_dbus_string_find (&to_send, 0,
+                                        "USERID_HEX", &where))
               {
                 DBusString username;
 
@@ -559,6 +589,45 @@ _dbus_auth_script_run (const DBusString *filename)
 
                 _dbus_string_free (&username);
               }
+            else if (_dbus_string_find (&to_send, 0,
+                                        "WRONG_USERNAME_HEX", &where))
+              {
+                /* This must be checked for before USERNAME_HEX, because
+                 * that's a substring. */
+#ifdef DBUS_UNIX
+                DBusString username = _DBUS_STRING_INIT_INVALID;
+
+                if (!_dbus_string_init (&username) ||
+                    !_dbus_test_append_different_username (&username))
+                  {
+                    _dbus_warn ("no memory for username");
+                    _dbus_string_free (&to_send);
+                    _dbus_string_free (&username);
+                    goto out;
+                  }
+
+                _dbus_string_delete (&to_send, where,
+                                     (int) strlen ("WRONG_USERNAME_HEX"));
+
+                if (!_dbus_string_hex_encode (&username, 0,
+                                              &to_send, where))
+                  {
+                    _dbus_warn ("no memory to subst WRONG_USERNAME_HEX");
+                    _dbus_string_free (&to_send);
+                    _dbus_string_free (&username);
+                    goto out;
+                  }
+
+                _dbus_string_free (&username);
+#else
+                /* No authentication mechanism uses the login name on
+                 * Windows, so there's no point in it appearing in an
+                 * auth script that is not UNIX_ONLY. */
+                _dbus_warn ("WRONG_USERNAME_HEX cannot be used on Windows");
+                _dbus_string_free (&to_send);
+                goto out;
+#endif
+              }
             else if (_dbus_string_find (&to_send, 0,
                                         "USERNAME_HEX", &where))
               {

test/test-utils.c

@@ -35,8 +35,15 @@
 #include <locale.h>
 #endif
 
+#include <dbus/dbus-sysdeps.h>
+
 #ifdef DBUS_UNIX
+# include <sys/types.h>
+# include <unistd.h>
+
 # include <dbus/dbus-sysdeps-unix.h>
+#else
+# include <dbus/dbus-sysdeps-win.h>
 #endif
 
 #include "dbus/dbus-message-internal.h"
@@ -455,6 +462,70 @@ test_pending_call_store_reply (DBusPendingCall *pc,
 }
 
 #ifdef DBUS_ENABLE_EMBEDDED_TESTS
+
+#ifdef DBUS_UNIX
+
+/*
+ * Set uid to a machine-readable authentication identity (numeric Unix
+ * uid or ConvertSidToStringSid-style Windows SID) that is likely to exist,
+ * and differs from the identity of the current process.
+ *
+ * @param uid Populated with a machine-readable authentication identity
+ *    on success
+ * @returns #FALSE if no memory
+ */
+dbus_bool_t
+_dbus_test_append_different_uid (DBusString *uid)
+{
+  if (geteuid () == 0)
+    return _dbus_string_append (uid, "65534");
+  else
+    return _dbus_string_append (uid, "0");
+}
+
+/*
+ * Set uid to a human-readable authentication identity (login name)
+ * that is likely to exist, and differs from the identity of the current
+ * process. This function currently only exists on Unix platforms.
+ *
+ * @param uid Populated with a machine-readable authentication identity
+ *    on success
+ * @returns #FALSE if no memory
+ */
+dbus_bool_t
+_dbus_test_append_different_username (DBusString *username)
+{
+  if (geteuid () == 0)
+    return _dbus_string_append (username, "nobody");
+  else
+    return _dbus_string_append (username, "root");
+}
+
+#else /* !defined(DBUS_UNIX) */
+
+#define ANONYMOUS_SID "S-1-5-7"
+#define LOCAL_SYSTEM_SID "S-1-5-18"
+
+dbus_bool_t
+_dbus_test_append_different_uid (DBusString *uid)
+{
+  char *sid = NULL;
+  dbus_bool_t ret;
+
+  if (!_dbus_getsid (&sid, _dbus_getpid ()))
+    return FALSE;
+
+  if (strcmp (sid, ANONYMOUS_SID) == 0)
+    ret = _dbus_string_append (uid, LOCAL_SYSTEM_SID);
+  else
+    ret = _dbus_string_append (uid, ANONYMOUS_SID);
+
+  LocalFree (sid);
+  return ret;
+}
+
+#endif /* !defined(DBUS_UNIX) */
+
 /*
  * _dbus_test_main:
  * @argc: number of command-line arguments

test/test-utils.h

@@ -88,4 +88,12 @@ int _dbus_test_main (int                  argc,
                      void               (*test_pre_hook) (void),
                      void               (*test_post_hook) (void));
 
+_DBUS_WARN_UNUSED_RESULT
+dbus_bool_t _dbus_test_append_different_uid (DBusString *uid);
+
+#ifdef DBUS_UNIX
+_DBUS_WARN_UNUSED_RESULT
+dbus_bool_t _dbus_test_append_different_username (DBusString *username);
+#endif
+
 #endif