sandbox/linux/tests/unit_tests.cc

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include <fcntl.h>
   6 #include <poll.h>
   7 #include <signal.h>
   8 #include <stdio.h>
   9 #include <sys/resource.h>
  10 #include <sys/time.h>
  11 #include <unistd.h>
  12
  13 #include "base/file_util.h"
  14 #include "base/third_party/valgrind/valgrind.h"
  15 #include "build/build_config.h"
  16 #include "sandbox/linux/tests/unit_tests.h"
  17
  18 namespace {
  19 std::string TestFailedMessage(const std::string& msg) {
  20   return msg.empty() ? std::string() : "Actual test failure: " + msg;
  21 }
  22
  23 int GetSubProcessTimeoutTimeInSeconds() {
  24   // 10s ought to be enough for anybody.
  25   return 10;
  26 }
  27
  28 // Returns the number of threads of the current process or -1.
  29 int CountThreads() {
  30   struct stat task_stat;
  31   int task_d = stat("/proc/self/task", &task_stat);
  32   // task_stat.st_nlink should be the number of tasks + 2 (accounting for
  33   // "." and "..".
  34   if (task_d != 0 || task_stat.st_nlink < 3)
  35     return -1;
  36   const int num_threads = task_stat.st_nlink - 2;
  37   return num_threads;
  38 }
  39
  40 }  // namespace
  41
  42 namespace sandbox {
  43
  44 bool IsAndroid() {
  45 #if defined(OS_ANDROID)
  46   return true;
  47 #else
  48   return false;
  49 #endif
  50 }
  51
  52 bool IsArchitectureArm() {
  53 #if defined(ARCH_CPU_ARM_FAMILY)
  54   return true;
  55 #else
  56   return false;
  57 #endif
  58 }
  59
  60 // TODO(jln): figure out why base/.../dynamic_annotations.h's
  61 // RunningOnValgrind() cannot link.
  62 bool IsRunningOnValgrind() { return RUNNING_ON_VALGRIND; }
  63
  64 static const int kExpectedValue = 42;
  65 static const int kIgnoreThisTest = 43;
  66 static const int kExitWithAssertionFailure = 1;
  67 static const int kExitForTimeout = 2;
  68
  69 static void SigAlrmHandler(int) {
  70   const char failure_message[] = "Timeout reached!\n";
  71   // Make sure that we never block here.
  72   if (!fcntl(2, F_SETFL, O_NONBLOCK)) {
  73     ignore_result(write(2, failure_message, sizeof(failure_message) - 1));
  74   }
  75   _exit(kExitForTimeout);
  76 }
  77
  78 // Set a timeout with a handler that will automatically fail the
  79 // test.
  80 static void SetProcessTimeout(int time_in_seconds) {
  81   struct sigaction act = {};
  82   act.sa_handler = SigAlrmHandler;
  83   SANDBOX_ASSERT(sigemptyset(&act.sa_mask) == 0);
  84   act.sa_flags = 0;
  85
  86   struct sigaction old_act;
  87   SANDBOX_ASSERT(sigaction(SIGALRM, &act, &old_act) == 0);
  88
  89   // We don't implemenet signal chaining, so make sure that nothing else
  90   // is expecting to handle SIGALRM.
  91   SANDBOX_ASSERT((old_act.sa_flags & SA_SIGINFO) == 0);
  92   SANDBOX_ASSERT(old_act.sa_handler == SIG_DFL);
  93   sigset_t sigalrm_set;
  94   SANDBOX_ASSERT(sigemptyset(&sigalrm_set) == 0);
  95   SANDBOX_ASSERT(sigaddset(&sigalrm_set, SIGALRM) == 0);
  96   SANDBOX_ASSERT(sigprocmask(SIG_UNBLOCK, &sigalrm_set, NULL) == 0);
  97   SANDBOX_ASSERT(alarm(time_in_seconds) == 0);  // There should be no previous
  98                                                 // alarm.
  99 }
 100
 101 // Runs a test in a sub-process. This is necessary for most of the code
 102 // in the BPF sandbox, as it potentially makes global state changes and as
 103 // it also tends to raise fatal errors, if the code has been used in an
 104 // insecure manner.
 105 void UnitTests::RunTestInProcess(UnitTests::Test test,
 106                                  void* arg,
 107                                  DeathCheck death,
 108                                  const void* death_aux) {
 109   // We need to fork(), so we can't be multi-threaded, as threads could hold
 110   // locks.
 111   int num_threads = CountThreads();
 112 #if defined(THREAD_SANITIZER)
 113   // Under TSAN, there is a special helper thread. It should be completely
 114   // invisible to our testing, so we ignore it. It should be ok to fork()
 115   // with this thread. It's currently buggy, but it's the best we can do until
 116   // there is a way to delay the start of the thread
 117   // (https://code.google.com/p/thread-sanitizer/issues/detail?id=19).
 118   num_threads--;
 119 #endif
 120   ASSERT_EQ(1, num_threads) << "Running sandbox tests with multiple threads "
 121                             << "is not supported and will make the tests "
 122                             << "flaky.\n";
 123   int fds[2];
 124   ASSERT_EQ(0, pipe(fds));
 125   // Check that our pipe is not on one of the standard file descriptor.
 126   SANDBOX_ASSERT(fds[0] > 2 && fds[1] > 2);
 127
 128   pid_t pid;
 129   ASSERT_LE(0, (pid = fork()));
 130   if (!pid) {
 131     // In child process
 132     // Redirect stderr to our pipe. This way, we can capture all error
 133     // messages, if we decide we want to do so in our tests.
 134     SANDBOX_ASSERT(dup2(fds[1], 2) == 2);
 135     SANDBOX_ASSERT(!close(fds[0]));
 136     SANDBOX_ASSERT(!close(fds[1]));
 137
 138     // Don't set a timeout if running on Valgrind, since it's generally much
 139     // slower.
 140     if (!IsRunningOnValgrind()) {
 141       SetProcessTimeout(GetSubProcessTimeoutTimeInSeconds());
 142     }
 143
 144     // Disable core files. They are not very useful for our individual test
 145     // cases.
 146     struct rlimit no_core = {0};
 147     setrlimit(RLIMIT_CORE, &no_core);
 148
 149     test(arg);
 150     _exit(kExpectedValue);
 151   }
 152
 153   close(fds[1]);
 154   std::vector<char> msg_buf;
 155   ssize_t rc;
 156
 157   // Make sure read() will never block as we'll use poll() to
 158   // block with a timeout instead.
 159   const int fcntl_ret = fcntl(fds[0], F_SETFL, O_NONBLOCK);
 160   ASSERT_EQ(fcntl_ret, 0);
 161   struct pollfd poll_fd = {fds[0], POLLIN | POLLRDHUP, 0};
 162
 163   int poll_ret;
 164   // We prefer the SIGALRM timeout to trigger in the child than this timeout
 165   // so we double the common value here.
 166   int poll_timeout = GetSubProcessTimeoutTimeInSeconds() * 2 * 1000;
 167   while ((poll_ret = poll(&poll_fd, 1, poll_timeout) > 0)) {
 168     const size_t kCapacity = 256;
 169     const size_t len = msg_buf.size();
 170     msg_buf.resize(len + kCapacity);
 171     rc = HANDLE_EINTR(read(fds[0], &msg_buf[len], kCapacity));
 172     msg_buf.resize(len + std::max(rc, static_cast<ssize_t>(0)));
 173     if (rc <= 0)
 174       break;
 175   }
 176   ASSERT_NE(poll_ret, -1) << "poll() failed";
 177   ASSERT_NE(poll_ret, 0) << "Timeout while reading child state";
 178   close(fds[0]);
 179   std::string msg(msg_buf.begin(), msg_buf.end());
 180
 181   int status = 0;
 182   int waitpid_returned = HANDLE_EINTR(waitpid(pid, &status, 0));
 183   ASSERT_EQ(pid, waitpid_returned) << TestFailedMessage(msg);
 184
 185   // At run-time, we sometimes decide that a test shouldn't actually
 186   // run (e.g. when testing sandbox features on a kernel that doesn't
 187   // have sandboxing support). When that happens, don't attempt to
 188   // call the "death" function, as it might be looking for a
 189   // death-test condition that would never have triggered.
 190   if (!WIFEXITED(status) || WEXITSTATUS(status) != kIgnoreThisTest ||
 191       !msg.empty()) {
 192     // We use gtest's ASSERT_XXX() macros instead of the DeathCheck
 193     // functions.  This means, on failure, "return" is called. This
 194     // only works correctly, if the call of the "death" callback is
 195     // the very last thing in our function.
 196     death(status, msg, death_aux);
 197   }
 198 }
 199
 200 void UnitTests::DeathSuccess(int status, const std::string& msg, const void*) {
 201   std::string details(TestFailedMessage(msg));
 202
 203   bool subprocess_terminated_normally = WIFEXITED(status);
 204   ASSERT_TRUE(subprocess_terminated_normally) << details;
 205   int subprocess_exit_status = WEXITSTATUS(status);
 206   ASSERT_EQ(kExpectedValue, subprocess_exit_status) << details;
 207   bool subprocess_exited_but_printed_messages = !msg.empty();
 208   EXPECT_FALSE(subprocess_exited_but_printed_messages) << details;
 209 }
 210
 211 void UnitTests::DeathMessage(int status,
 212                              const std::string& msg,
 213                              const void* aux) {
 214   std::string details(TestFailedMessage(msg));
 215   const char* expected_msg = static_cast<const char*>(aux);
 216
 217   bool subprocess_terminated_normally = WIFEXITED(status);
 218   ASSERT_TRUE(subprocess_terminated_normally) << details;
 219   int subprocess_exit_status = WEXITSTATUS(status);
 220   ASSERT_EQ(kExitWithAssertionFailure, subprocess_exit_status) << details;
 221   bool subprocess_exited_without_matching_message =
 222       msg.find(expected_msg) == std::string::npos;
 223   EXPECT_FALSE(subprocess_exited_without_matching_message) << details;
 224 }
 225
 226 void UnitTests::DeathExitCode(int status,
 227                               const std::string& msg,
 228                               const void* aux) {
 229   int expected_exit_code = static_cast<int>(reinterpret_cast<intptr_t>(aux));
 230   std::string details(TestFailedMessage(msg));
 231
 232   bool subprocess_terminated_normally = WIFEXITED(status);
 233   ASSERT_TRUE(subprocess_terminated_normally) << details;
 234   int subprocess_exit_status = WEXITSTATUS(status);
 235   ASSERT_EQ(subprocess_exit_status, expected_exit_code) << details;
 236 }
 237
 238 void UnitTests::DeathBySignal(int status,
 239                               const std::string& msg,
 240                               const void* aux) {
 241   int expected_signo = static_cast<int>(reinterpret_cast<intptr_t>(aux));
 242   std::string details(TestFailedMessage(msg));
 243
 244   bool subprocess_terminated_by_signal = WIFSIGNALED(status);
 245   ASSERT_TRUE(subprocess_terminated_by_signal) << details;
 246   int subprocess_signal_number = WTERMSIG(status);
 247   ASSERT_EQ(subprocess_signal_number, expected_signo) << details;
 248 }
 249
 250 void UnitTests::AssertionFailure(const char* expr, const char* file, int line) {
 251   fprintf(stderr, "%s:%d:%s", file, line, expr);
 252   fflush(stderr);
 253   _exit(kExitWithAssertionFailure);
 254 }
 255
 256 void UnitTests::IgnoreThisTest() {
 257   fflush(stderr);
 258   _exit(kIgnoreThisTest);
 259 }
 260
 261 }  // namespace