MinSFI: Passing arguments to the entry function

tests/minsfi/test_invoke_args.c

+/*
+ * Copyright (c) 2014 The Native Client Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+#include <string.h>
+
+#include "native_client/src/include/minsfi.h"
+#include "native_client/src/include/minsfi_priv.h"
+#include "native_client/src/include/nacl_assert.h"
+
+/*
+ * Helper function which creates a NULL-terminated string that occupies
+ * the given number of bytes.
+ */
+static inline char *get_str(int bytes) {
+  char *str = (char*) malloc(bytes);
+  memset(str, 'A', bytes - 1);
+  str[bytes - 1] = 0;
+  return str;
+}
+
+/*
+ * Test the CopyArguments function. We verify that it will not attempt to write
+ * beyond the bounds of the untrusted stack.
+ */
+void test_copy_limits(void) {
+  const MinsfiSandbox *sb;
+  int stack_fit;
+  char *argv_fit[1];
+  char *argv_info_overflow[1];
+  char *argv_arg_overflow[2];
+
+  /* Initialize the sandbox. */
+  MinsfiInitializeSandbox();
+  sb = MinsfiGetActiveSandbox();
+
+  /* argc < 0 doesn't make sense */
+  ASSERT_EQ(0, MinsfiCopyArguments(-5, NULL, sb));
+
+  /*
+   * Test that CopyArguments allows to fill the whole stack.
+   * The info structure will contain two integers. We cannot invoke the sandbox
+   * because it would immediately overflow the stack.
+   */
+  stack_fit = sb->mem_layout.stack.length - 2 * sizeof(sfiptr_t);
+  argv_fit[0] = get_str(stack_fit);
+  ASSERT_EQ(sb->mem_layout.stack.offset, MinsfiCopyArguments(1, argv_fit, sb));
+
+  /*
+   * Test that CopyArguments fails if the arguments don't leave enough space
+   * for the info structure.
+   */
+  argv_info_overflow[0] = get_str(stack_fit + 1);
+  ASSERT_EQ(0, MinsfiCopyArguments(1, argv_info_overflow, sb));
+  ASSERT_EQ(EXIT_FAILURE, MinsfiInvokeSandbox(1, argv_info_overflow));
+
+  /*
+   * Test that CopyArguments fails if the arguments do not fit onto the stack.
+   * The info structure will contain three integers.
+   */
+  stack_fit = sb->mem_layout.stack.length - 3 * sizeof(sfiptr_t);
+  argv_arg_overflow[0] = get_str(stack_fit - 15);
+  argv_arg_overflow[1] = get_str(16);
+  ASSERT_EQ(0, MinsfiCopyArguments(2, argv_arg_overflow, sb));
+  ASSERT_EQ(EXIT_FAILURE, MinsfiInvokeSandbox(2, argv_arg_overflow));
+
+  /* Clean up. */
+  MinsfiDestroySandbox();
+  free(argv_fit[0]);
+  free(argv_info_overflow[0]);
+  free(argv_arg_overflow[0]);
+  free(argv_arg_overflow[1]);
+}
+
+/*
+ * This tests whether arguments are correctly passed to the sandbox. We do
+ * this by passing it a series of strings containing integer numbers. The
+ * sandbox is expected to parse the arguments and return their sum.
+ */
+void test_arguments_valid(void) {
+  char *argv_99[] = { "99" };
+  char *argv_1_22_333[] = { "1", "22", "333" };
+
+  /* Prepare the sandbox. */
+  MinsfiInitializeSandbox();
+
+  /* Empty arguments. The sandbox should always receive at least one argument
+   * (the name of the binary) but we test this anyway. */
+  ASSERT_EQ(0, MinsfiInvokeSandbox(0, NULL));
+
+  /* Single argument. */
+  ASSERT_EQ(99, MinsfiInvokeSandbox(1, argv_99));
+
+  /* Multiple arguments. */
+  ASSERT_EQ(356, MinsfiInvokeSandbox(3, argv_1_22_333));
+
+  /* Clean up. */
+  MinsfiDestroySandbox();
+}
+
+int main(void) {
+  test_copy_limits();
+  test_arguments_valid();
+  return 0;
+}