base/security_unittest.cc

   1 // Copyright (c) 2013 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 <stdio.h>
   7 #include <stdlib.h>
   8 #include <string.h>
   9 #include <sys/stat.h>
  10 #include <sys/types.h>
  11
  12 #include <algorithm>
  13 #include <limits>
  14
  15 #include "base/file_util.h"
  16 #include "base/logging.h"
  17 #include "base/memory/scoped_ptr.h"
  18 #include "build/build_config.h"
  19 #include "testing/gtest/include/gtest/gtest.h"
  20
  21 #if defined(OS_POSIX)
  22 #include <sys/mman.h>
  23 #include <unistd.h>
  24 #endif
  25
  26 using std::nothrow;
  27 using std::numeric_limits;
  28
  29 namespace {
  30
  31 // This function acts as a compiler optimization barrier. We use it to
  32 // prevent the compiler from making an expression a compile-time constant.
  33 // We also use it so that the compiler doesn't discard certain return values
  34 // as something we don't need (see the comment with calloc below).
  35 template <typename Type>
  36 Type HideValueFromCompiler(volatile Type value) {
  37 #if defined(__GNUC__)
  38   // In a GCC compatible compiler (GCC or Clang), make this compiler barrier
  39   // more robust than merely using "volatile".
  40   __asm__ volatile ("" : "+r" (value));
  41 #endif  // __GNUC__
  42   return value;
  43 }
  44
  45 // - NO_TCMALLOC (should be defined if we compile with linux_use_tcmalloc=0)
  46 // - ADDRESS_SANITIZER because it has its own memory allocator
  47 // - IOS does not use tcmalloc
  48 // - OS_MACOSX does not use tcmalloc
  49 #if !defined(NO_TCMALLOC) && !defined(ADDRESS_SANITIZER) && \
  50     !defined(OS_IOS) && !defined(OS_MACOSX)
  51   #define TCMALLOC_TEST(function) function
  52 #else
  53   #define TCMALLOC_TEST(function) DISABLED_##function
  54 #endif
  55
  56 // TODO(jln): switch to std::numeric_limits<int>::max() when we switch to
  57 // C++11.
  58 const size_t kTooBigAllocSize = INT_MAX;
  59
  60 // Detect runtime TCMalloc bypasses.
  61 bool IsTcMallocBypassed() {
  62 #if defined(OS_LINUX) || defined(OS_CHROMEOS)
  63   // This should detect a TCMalloc bypass from Valgrind.
  64   char* g_slice = getenv("G_SLICE");
  65   if (g_slice && !strcmp(g_slice, "always-malloc"))
  66     return true;
  67 #elif defined(OS_WIN)
  68   // This should detect a TCMalloc bypass from setting
  69   // the CHROME_ALLOCATOR environment variable.
  70   char* allocator = getenv("CHROME_ALLOCATOR");
  71   if (allocator && strcmp(allocator, "tcmalloc"))
  72     return true;
  73 #endif
  74   return false;
  75 }
  76
  77 bool CallocDiesOnOOM() {
  78 // The wrapper function in base/process_util_linux.cc that is used when we
  79 // compile without TCMalloc will just die on OOM instead of returning NULL.
  80 // This function is explicitly disabled if we compile with AddressSanitizer,
  81 // MemorySanitizer or ThreadSanitizer.
  82 #if defined(OS_LINUX) && defined(NO_TCMALLOC) && \
  83     (!defined(ADDRESS_SANITIZER) && \
  84      !defined(MEMORY_SANITIZER) && \
  85      !defined(THREAD_SANITIZER))
  86   return true;
  87 #else
  88   return false;
  89 #endif
  90 }
  91
  92 // Fake test that allow to know the state of TCMalloc by looking at bots.
  93 TEST(SecurityTest, TCMALLOC_TEST(IsTCMallocDynamicallyBypassed)) {
  94   printf("Malloc is dynamically bypassed: %s\n",
  95          IsTcMallocBypassed() ? "yes." : "no.");
  96 }
  97
  98 // The MemoryAllocationRestrictions* tests test that we can not allocate a
  99 // memory range that cannot be indexed via an int. This is used to mitigate
 100 // vulnerabilities in libraries that use int instead of size_t.  See
 101 // crbug.com/169327.
 102
 103 TEST(SecurityTest, TCMALLOC_TEST(MemoryAllocationRestrictionsMalloc)) {
 104   if (!IsTcMallocBypassed()) {
 105     scoped_ptr<char, base::FreeDeleter> ptr(static_cast<char*>(
 106         HideValueFromCompiler(malloc(kTooBigAllocSize))));
 107     ASSERT_TRUE(!ptr);
 108   }
 109 }
 110
 111 TEST(SecurityTest, TCMALLOC_TEST(MemoryAllocationRestrictionsCalloc)) {
 112   if (!IsTcMallocBypassed()) {
 113     scoped_ptr<char, base::FreeDeleter> ptr(static_cast<char*>(
 114         HideValueFromCompiler(calloc(kTooBigAllocSize, 1))));
 115     ASSERT_TRUE(!ptr);
 116   }
 117 }
 118
 119 TEST(SecurityTest, TCMALLOC_TEST(MemoryAllocationRestrictionsRealloc)) {
 120   if (!IsTcMallocBypassed()) {
 121     char* orig_ptr = static_cast<char*>(malloc(1));
 122     ASSERT_TRUE(orig_ptr);
 123     scoped_ptr<char, base::FreeDeleter> ptr(static_cast<char*>(
 124         HideValueFromCompiler(realloc(orig_ptr, kTooBigAllocSize))));
 125     ASSERT_TRUE(!ptr);
 126     // If realloc() did not succeed, we need to free orig_ptr.
 127     free(orig_ptr);
 128   }
 129 }
 130
 131 typedef struct {
 132   char large_array[kTooBigAllocSize];
 133 } VeryLargeStruct;
 134
 135 TEST(SecurityTest, TCMALLOC_TEST(MemoryAllocationRestrictionsNew)) {
 136   if (!IsTcMallocBypassed()) {
 137     scoped_ptr<VeryLargeStruct> ptr(
 138         HideValueFromCompiler(new (nothrow) VeryLargeStruct));
 139     ASSERT_TRUE(!ptr);
 140   }
 141 }
 142
 143 TEST(SecurityTest, TCMALLOC_TEST(MemoryAllocationRestrictionsNewArray)) {
 144   if (!IsTcMallocBypassed()) {
 145     scoped_ptr<char[]> ptr(
 146         HideValueFromCompiler(new (nothrow) char[kTooBigAllocSize]));
 147     ASSERT_TRUE(!ptr);
 148   }
 149 }
 150
 151 // The tests bellow check for overflows in new[] and calloc().
 152
 153 #if defined(OS_IOS) || defined(OS_WIN)
 154   #define DISABLE_ON_IOS_AND_WIN(function) DISABLED_##function
 155 #else
 156   #define DISABLE_ON_IOS_AND_WIN(function) function
 157 #endif
 158
 159 // There are platforms where these tests are known to fail. We would like to
 160 // be able to easily check the status on the bots, but marking tests as
 161 // FAILS_ is too clunky.
 162 void OverflowTestsSoftExpectTrue(bool overflow_detected) {
 163   if (!overflow_detected) {
 164 #if defined(OS_LINUX) || defined(OS_ANDROID) || defined(OS_MACOSX)
 165     // Sadly, on Linux, Android, and OSX we don't have a good story yet. Don't
 166     // fail the test, but report.
 167     printf("Platform has overflow: %s\n",
 168            !overflow_detected ? "yes." : "no.");
 169 #else
 170     // Otherwise, fail the test. (Note: EXPECT are ok in subfunctions, ASSERT
 171     // aren't).
 172     EXPECT_TRUE(overflow_detected);
 173 #endif
 174   }
 175 }
 176
 177 // Test array[TooBig][X] and array[X][TooBig] allocations for int overflows.
 178 // IOS doesn't honor nothrow, so disable the test there.
 179 // Crashes on Windows Dbg builds, disable there as well.
 180 TEST(SecurityTest, DISABLE_ON_IOS_AND_WIN(NewOverflow)) {
 181   const size_t kArraySize = 4096;
 182   // We want something "dynamic" here, so that the compiler doesn't
 183   // immediately reject crazy arrays.
 184   const size_t kDynamicArraySize = HideValueFromCompiler(kArraySize);
 185   // numeric_limits are still not constexpr until we switch to C++11, so we
 186   // use an ugly cast.
 187   const size_t kMaxSizeT = ~static_cast<size_t>(0);
 188   ASSERT_EQ(numeric_limits<size_t>::max(), kMaxSizeT);
 189   const size_t kArraySize2 = kMaxSizeT / kArraySize + 10;
 190   const size_t kDynamicArraySize2 = HideValueFromCompiler(kArraySize2);
 191   {
 192     scoped_ptr<char[][kArraySize]> array_pointer(new (nothrow)
 193         char[kDynamicArraySize2][kArraySize]);
 194     OverflowTestsSoftExpectTrue(!array_pointer);
 195   }
 196   // On windows, the compiler prevents static array sizes of more than
 197   // 0x7fffffff (error C2148).
 198 #if !defined(OS_WIN) || !defined(ARCH_CPU_64_BITS)
 199   {
 200     scoped_ptr<char[][kArraySize2]> array_pointer(new (nothrow)
 201         char[kDynamicArraySize][kArraySize2]);
 202     OverflowTestsSoftExpectTrue(!array_pointer);
 203   }
 204 #endif  // !defined(OS_WIN) || !defined(ARCH_CPU_64_BITS)
 205 }
 206
 207 // Call calloc(), eventually free the memory and return whether or not
 208 // calloc() did succeed.
 209 bool CallocReturnsNull(size_t nmemb, size_t size) {
 210   scoped_ptr<char, base::FreeDeleter> array_pointer(
 211       static_cast<char*>(calloc(nmemb, size)));
 212   // We need the call to HideValueFromCompiler(): we have seen LLVM
 213   // optimize away the call to calloc() entirely and assume
 214   // the pointer to not be NULL.
 215   return HideValueFromCompiler(array_pointer.get()) == NULL;
 216 }
 217
 218 // Test if calloc() can overflow.
 219 TEST(SecurityTest, CallocOverflow) {
 220   const size_t kArraySize = 4096;
 221   const size_t kMaxSizeT = numeric_limits<size_t>::max();
 222   const size_t kArraySize2 = kMaxSizeT / kArraySize + 10;
 223   if (!CallocDiesOnOOM()) {
 224     EXPECT_TRUE(CallocReturnsNull(kArraySize, kArraySize2));
 225     EXPECT_TRUE(CallocReturnsNull(kArraySize2, kArraySize));
 226   } else {
 227     // It's also ok for calloc to just terminate the process.
 228 #if defined(GTEST_HAS_DEATH_TEST)
 229     EXPECT_DEATH(CallocReturnsNull(kArraySize, kArraySize2), "");
 230     EXPECT_DEATH(CallocReturnsNull(kArraySize2, kArraySize), "");
 231 #endif  // GTEST_HAS_DEATH_TEST
 232   }
 233 }
 234
 235 #if (defined(OS_LINUX) || defined(OS_CHROMEOS)) && defined(__x86_64__)
 236 // Useful for debugging.
 237 void PrintProcSelfMaps() {
 238   int fd = open("/proc/self/maps", O_RDONLY);
 239   file_util::ScopedFD fd_closer(&fd);
 240   ASSERT_GE(fd, 0);
 241   char buffer[1<<13];
 242   int ret;
 243   ret = read(fd, buffer, sizeof(buffer) - 1);
 244   ASSERT_GT(ret, 0);
 245   buffer[ret - 1] = 0;
 246   fprintf(stdout, "%s\n", buffer);
 247 }
 248
 249 // Check if ptr1 and ptr2 are separated by less than size chars.
 250 bool ArePointersToSameArea(void* ptr1, void* ptr2, size_t size) {
 251   ptrdiff_t ptr_diff = reinterpret_cast<char*>(std::max(ptr1, ptr2)) -
 252                        reinterpret_cast<char*>(std::min(ptr1, ptr2));
 253   return static_cast<size_t>(ptr_diff) <= size;
 254 }
 255
 256 // Check if TCMalloc uses an underlying random memory allocator.
 257 TEST(SecurityTest, TCMALLOC_TEST(RandomMemoryAllocations)) {
 258   if (IsTcMallocBypassed())
 259     return;
 260   size_t kPageSize = 4096;  // We support x86_64 only.
 261   // Check that malloc() returns an address that is neither the kernel's
 262   // un-hinted mmap area, nor the current brk() area. The first malloc() may
 263   // not be at a random address because TCMalloc will first exhaust any memory
 264   // that it has allocated early on, before starting the sophisticated
 265   // allocators.
 266   void* default_mmap_heap_address =
 267       mmap(0, kPageSize, PROT_READ|PROT_WRITE,
 268            MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
 269   ASSERT_NE(default_mmap_heap_address,
 270             static_cast<void*>(MAP_FAILED));
 271   ASSERT_EQ(munmap(default_mmap_heap_address, kPageSize), 0);
 272   void* brk_heap_address = sbrk(0);
 273   ASSERT_NE(brk_heap_address, reinterpret_cast<void*>(-1));
 274   ASSERT_TRUE(brk_heap_address != NULL);
 275   // 1 MB should get us past what TCMalloc pre-allocated before initializing
 276   // the sophisticated allocators.
 277   size_t kAllocSize = 1<<20;
 278   scoped_ptr<char, base::FreeDeleter> ptr(
 279       static_cast<char*>(malloc(kAllocSize)));
 280   ASSERT_TRUE(ptr != NULL);
 281   // If two pointers are separated by less than 512MB, they are considered
 282   // to be in the same area.
 283   // Our random pointer could be anywhere within 0x3fffffffffff (46bits),
 284   // and we are checking that it's not withing 1GB (30 bits) from two
 285   // addresses (brk and mmap heap). We have roughly one chance out of
 286   // 2^15 to flake.
 287   const size_t kAreaRadius = 1<<29;
 288   bool in_default_mmap_heap = ArePointersToSameArea(
 289       ptr.get(), default_mmap_heap_address, kAreaRadius);
 290   EXPECT_FALSE(in_default_mmap_heap);
 291
 292   bool in_default_brk_heap = ArePointersToSameArea(
 293       ptr.get(), brk_heap_address, kAreaRadius);
 294   EXPECT_FALSE(in_default_brk_heap);
 295
 296   // In the implementation, we always mask our random addresses with
 297   // kRandomMask, so we use it as an additional detection mechanism.
 298   const uintptr_t kRandomMask = 0x3fffffffffffULL;
 299   bool impossible_random_address =
 300       reinterpret_cast<uintptr_t>(ptr.get()) & ~kRandomMask;
 301   EXPECT_FALSE(impossible_random_address);
 302 }
 303
 304 #endif  // (defined(OS_LINUX) || defined(OS_CHROMEOS)) && defined(__x86_64__)
 305
 306 }  // namespace