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/files/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 #if defined(OS_WIN)
  27 #include <new.h>
  28 #endif
  29
  30 using std::nothrow;
  31 using std::numeric_limits;
  32
  33 namespace {
  34
  35 #if defined(OS_WIN)
  36 // This is a permitted size but exhausts memory pretty quickly.
  37 const size_t kLargePermittedAllocation = 0x7FFFE000;
  38
  39 int OnNoMemory(size_t) {
  40   _exit(1);
  41 }
  42
  43 void ExhaustMemoryWithMalloc() {
  44   for (;;) {
  45     // Without the |volatile|, clang optimizes away the allocation.
  46     void* volatile buf = malloc(kLargePermittedAllocation);
  47     if (!buf)
  48       break;
  49   }
  50 }
  51
  52 void ExhaustMemoryWithRealloc() {
  53   size_t size = kLargePermittedAllocation;
  54   void* buf = malloc(size);
  55   if (!buf)
  56     return;
  57   for (;;) {
  58     size += kLargePermittedAllocation;
  59     void* new_buf = realloc(buf, size);
  60     if (!buf)
  61       break;
  62     buf = new_buf;
  63   }
  64 }
  65 #endif
  66
  67 // This function acts as a compiler optimization barrier. We use it to
  68 // prevent the compiler from making an expression a compile-time constant.
  69 // We also use it so that the compiler doesn't discard certain return values
  70 // as something we don't need (see the comment with calloc below).
  71 template <typename Type>
  72 NOINLINE Type HideValueFromCompiler(volatile Type value) {
  73 #if defined(__GNUC__)
  74   // In a GCC compatible compiler (GCC or Clang), make this compiler barrier
  75   // more robust than merely using "volatile".
  76   __asm__ volatile ("" : "+r" (value));
  77 #endif  // __GNUC__
  78   return value;
  79 }
  80
  81 // Tcmalloc and Windows allocator shim support setting malloc limits.
  82 // - NO_TCMALLOC (should be defined if compiled with use_allocator!="tcmalloc")
  83 // - ADDRESS_SANITIZER and SYZYASAN because they have their own memory allocator
  84 // - IOS does not use tcmalloc
  85 // - OS_MACOSX does not use tcmalloc
  86 // - Windows allocator shim defines ALLOCATOR_SHIM
  87 #if (!defined(NO_TCMALLOC) || defined(ALLOCATOR_SHIM)) &&                     \
  88     !defined(ADDRESS_SANITIZER) && !defined(OS_IOS) && !defined(OS_MACOSX) && \
  89     !defined(SYZYASAN)
  90 #define MALLOC_OVERFLOW_TEST(function) function
  91 #else
  92 #define MALLOC_OVERFLOW_TEST(function) DISABLED_##function
  93 #endif
  94
  95 // TODO(jln): switch to std::numeric_limits<int>::max() when we switch to
  96 // C++11.
  97 const size_t kTooBigAllocSize = INT_MAX;
  98
  99 // Detect runtime TCMalloc bypasses.
 100 bool IsTcMallocBypassed() {
 101 #if defined(OS_LINUX)
 102   // This should detect a TCMalloc bypass from Valgrind.
 103   char* g_slice = getenv("G_SLICE");
 104   if (g_slice && !strcmp(g_slice, "always-malloc"))
 105     return true;
 106 #endif
 107   return false;
 108 }
 109
 110 bool CallocDiesOnOOM() {
 111 // The sanitizers' calloc dies on OOM instead of returning NULL.
 112 // The wrapper function in base/process_util_linux.cc that is used when we
 113 // compile without TCMalloc will just die on OOM instead of returning NULL.
 114 #if defined(ADDRESS_SANITIZER) || \
 115     defined(MEMORY_SANITIZER) || \
 116     defined(THREAD_SANITIZER) || \
 117     (defined(OS_LINUX) && defined(NO_TCMALLOC))
 118   return true;
 119 #else
 120   return false;
 121 #endif
 122 }
 123
 124 // Fake test that allow to know the state of TCMalloc by looking at bots.
 125 TEST(SecurityTest, MALLOC_OVERFLOW_TEST(IsTCMallocDynamicallyBypassed)) {
 126   printf("Malloc is dynamically bypassed: %s\n",
 127          IsTcMallocBypassed() ? "yes." : "no.");
 128 }
 129
 130 // The MemoryAllocationRestrictions* tests test that we can not allocate a
 131 // memory range that cannot be indexed via an int. This is used to mitigate
 132 // vulnerabilities in libraries that use int instead of size_t.  See
 133 // crbug.com/169327.
 134
 135 TEST(SecurityTest, MALLOC_OVERFLOW_TEST(MemoryAllocationRestrictionsMalloc)) {
 136   if (!IsTcMallocBypassed()) {
 137     scoped_ptr<char, base::FreeDeleter> ptr(static_cast<char*>(
 138         HideValueFromCompiler(malloc(kTooBigAllocSize))));
 139     ASSERT_TRUE(!ptr);
 140   }
 141 }
 142
 143 #if defined(GTEST_HAS_DEATH_TEST) && defined(OS_WIN)
 144 TEST(SecurityTest, MALLOC_OVERFLOW_TEST(MemoryAllocationMallocDeathTest)) {
 145   _set_new_handler(&OnNoMemory);
 146   _set_new_mode(1);
 147   {
 148     scoped_ptr<char, base::FreeDeleter> ptr;
 149     EXPECT_DEATH(ptr.reset(static_cast<char*>(
 150                       HideValueFromCompiler(malloc(kTooBigAllocSize)))),
 151                   "");
 152     ASSERT_TRUE(!ptr);
 153   }
 154   _set_new_handler(NULL);
 155   _set_new_mode(0);
 156 }
 157
 158 TEST(SecurityTest, MALLOC_OVERFLOW_TEST(MemoryAllocationExhaustDeathTest)) {
 159   _set_new_handler(&OnNoMemory);
 160   _set_new_mode(1);
 161   {
 162     ASSERT_DEATH(ExhaustMemoryWithMalloc(), "");
 163   }
 164   _set_new_handler(NULL);
 165   _set_new_mode(0);
 166 }
 167
 168 TEST(SecurityTest, MALLOC_OVERFLOW_TEST(MemoryReallocationExhaustDeathTest)) {
 169   _set_new_handler(&OnNoMemory);
 170   _set_new_mode(1);
 171   {
 172     ASSERT_DEATH(ExhaustMemoryWithRealloc(), "");
 173   }
 174   _set_new_handler(NULL);
 175   _set_new_mode(0);
 176 }
 177 #endif
 178
 179 TEST(SecurityTest, MALLOC_OVERFLOW_TEST(MemoryAllocationRestrictionsCalloc)) {
 180   if (!IsTcMallocBypassed()) {
 181     scoped_ptr<char, base::FreeDeleter> ptr(static_cast<char*>(
 182         HideValueFromCompiler(calloc(kTooBigAllocSize, 1))));
 183     ASSERT_TRUE(!ptr);
 184   }
 185 }
 186
 187 TEST(SecurityTest, MALLOC_OVERFLOW_TEST(MemoryAllocationRestrictionsRealloc)) {
 188   if (!IsTcMallocBypassed()) {
 189     char* orig_ptr = static_cast<char*>(malloc(1));
 190     ASSERT_TRUE(orig_ptr);
 191     scoped_ptr<char, base::FreeDeleter> ptr(static_cast<char*>(
 192         HideValueFromCompiler(realloc(orig_ptr, kTooBigAllocSize))));
 193     ASSERT_TRUE(!ptr);
 194     // If realloc() did not succeed, we need to free orig_ptr.
 195     free(orig_ptr);
 196   }
 197 }
 198
 199 typedef struct {
 200   char large_array[kTooBigAllocSize];
 201 } VeryLargeStruct;
 202
 203 TEST(SecurityTest, MALLOC_OVERFLOW_TEST(MemoryAllocationRestrictionsNew)) {
 204   if (!IsTcMallocBypassed()) {
 205     scoped_ptr<VeryLargeStruct> ptr(
 206         HideValueFromCompiler(new (nothrow) VeryLargeStruct));
 207     ASSERT_TRUE(!ptr);
 208   }
 209 }
 210
 211 #if defined(GTEST_HAS_DEATH_TEST) && defined(OS_WIN)
 212 TEST(SecurityTest, MALLOC_OVERFLOW_TEST(MemoryAllocationNewDeathTest)) {
 213   _set_new_handler(&OnNoMemory);
 214   {
 215     scoped_ptr<VeryLargeStruct> ptr;
 216     EXPECT_DEATH(
 217         ptr.reset(HideValueFromCompiler(new (nothrow) VeryLargeStruct)), "");
 218     ASSERT_TRUE(!ptr);
 219   }
 220   _set_new_handler(NULL);
 221 }
 222 #endif
 223
 224 TEST(SecurityTest, MALLOC_OVERFLOW_TEST(MemoryAllocationRestrictionsNewArray)) {
 225   if (!IsTcMallocBypassed()) {
 226     scoped_ptr<char[]> ptr(
 227         HideValueFromCompiler(new (nothrow) char[kTooBigAllocSize]));
 228     ASSERT_TRUE(!ptr);
 229   }
 230 }
 231
 232 // The tests bellow check for overflows in new[] and calloc().
 233
 234 // There are platforms where these tests are known to fail. We would like to
 235 // be able to easily check the status on the bots, but marking tests as
 236 // FAILS_ is too clunky.
 237 void OverflowTestsSoftExpectTrue(bool overflow_detected) {
 238   if (!overflow_detected) {
 239 #if defined(OS_LINUX) || defined(OS_ANDROID) || defined(OS_MACOSX)
 240     // Sadly, on Linux, Android, and OSX we don't have a good story yet. Don't
 241     // fail the test, but report.
 242     printf("Platform has overflow: %s\n",
 243            !overflow_detected ? "yes." : "no.");
 244 #else
 245     // Otherwise, fail the test. (Note: EXPECT are ok in subfunctions, ASSERT
 246     // aren't).
 247     EXPECT_TRUE(overflow_detected);
 248 #endif
 249   }
 250 }
 251
 252 #if defined(OS_IOS) || defined(OS_WIN) || defined(THREAD_SANITIZER) || defined(OS_MACOSX)
 253 #define MAYBE_NewOverflow DISABLED_NewOverflow
 254 #else
 255 #define MAYBE_NewOverflow NewOverflow
 256 #endif
 257 // Test array[TooBig][X] and array[X][TooBig] allocations for int overflows.
 258 // IOS doesn't honor nothrow, so disable the test there.
 259 // Crashes on Windows Dbg builds, disable there as well.
 260 // Fails on Mac 10.8 http://crbug.com/227092
 261 TEST(SecurityTest, MAYBE_NewOverflow) {
 262   const size_t kArraySize = 4096;
 263   // We want something "dynamic" here, so that the compiler doesn't
 264   // immediately reject crazy arrays.
 265   const size_t kDynamicArraySize = HideValueFromCompiler(kArraySize);
 266   // numeric_limits are still not constexpr until we switch to C++11, so we
 267   // use an ugly cast.
 268   const size_t kMaxSizeT = ~static_cast<size_t>(0);
 269   ASSERT_EQ(numeric_limits<size_t>::max(), kMaxSizeT);
 270   const size_t kArraySize2 = kMaxSizeT / kArraySize + 10;
 271   const size_t kDynamicArraySize2 = HideValueFromCompiler(kArraySize2);
 272   {
 273     scoped_ptr<char[][kArraySize]> array_pointer(new (nothrow)
 274         char[kDynamicArraySize2][kArraySize]);
 275     OverflowTestsSoftExpectTrue(!array_pointer);
 276   }
 277   // On windows, the compiler prevents static array sizes of more than
 278   // 0x7fffffff (error C2148).
 279 #if defined(OS_WIN) && defined(ARCH_CPU_64_BITS)
 280   ALLOW_UNUSED_LOCAL(kDynamicArraySize);
 281 #else
 282   {
 283     scoped_ptr<char[][kArraySize2]> array_pointer(new (nothrow)
 284         char[kDynamicArraySize][kArraySize2]);
 285     OverflowTestsSoftExpectTrue(!array_pointer);
 286   }
 287 #endif  // !defined(OS_WIN) || !defined(ARCH_CPU_64_BITS)
 288 }
 289
 290 // Call calloc(), eventually free the memory and return whether or not
 291 // calloc() did succeed.
 292 bool CallocReturnsNull(size_t nmemb, size_t size) {
 293   scoped_ptr<char, base::FreeDeleter> array_pointer(
 294       static_cast<char*>(calloc(nmemb, size)));
 295   // We need the call to HideValueFromCompiler(): we have seen LLVM
 296   // optimize away the call to calloc() entirely and assume the pointer to not
 297   // be NULL.
 298   return HideValueFromCompiler(array_pointer.get()) == NULL;
 299 }
 300
 301 // Test if calloc() can overflow.
 302 TEST(SecurityTest, CallocOverflow) {
 303   const size_t kArraySize = 4096;
 304   const size_t kMaxSizeT = numeric_limits<size_t>::max();
 305   const size_t kArraySize2 = kMaxSizeT / kArraySize + 10;
 306   if (!CallocDiesOnOOM()) {
 307     EXPECT_TRUE(CallocReturnsNull(kArraySize, kArraySize2));
 308     EXPECT_TRUE(CallocReturnsNull(kArraySize2, kArraySize));
 309   } else {
 310     // It's also ok for calloc to just terminate the process.
 311 #if defined(GTEST_HAS_DEATH_TEST)
 312     EXPECT_DEATH(CallocReturnsNull(kArraySize, kArraySize2), "");
 313     EXPECT_DEATH(CallocReturnsNull(kArraySize2, kArraySize), "");
 314 #endif  // GTEST_HAS_DEATH_TEST
 315   }
 316 }
 317
 318 #if defined(OS_LINUX) && defined(__x86_64__)
 319 // Check if ptr1 and ptr2 are separated by less than size chars.
 320 bool ArePointersToSameArea(void* ptr1, void* ptr2, size_t size) {
 321   ptrdiff_t ptr_diff = reinterpret_cast<char*>(std::max(ptr1, ptr2)) -
 322                        reinterpret_cast<char*>(std::min(ptr1, ptr2));
 323   return static_cast<size_t>(ptr_diff) <= size;
 324 }
 325
 326 // Check if TCMalloc uses an underlying random memory allocator.
 327 TEST(SecurityTest, MALLOC_OVERFLOW_TEST(RandomMemoryAllocations)) {
 328   if (IsTcMallocBypassed())
 329     return;
 330   size_t kPageSize = 4096;  // We support x86_64 only.
 331   // Check that malloc() returns an address that is neither the kernel's
 332   // un-hinted mmap area, nor the current brk() area. The first malloc() may
 333   // not be at a random address because TCMalloc will first exhaust any memory
 334   // that it has allocated early on, before starting the sophisticated
 335   // allocators.
 336   void* default_mmap_heap_address =
 337       mmap(0, kPageSize, PROT_READ|PROT_WRITE,
 338            MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
 339   ASSERT_NE(default_mmap_heap_address,
 340             static_cast<void*>(MAP_FAILED));
 341   ASSERT_EQ(munmap(default_mmap_heap_address, kPageSize), 0);
 342   void* brk_heap_address = sbrk(0);
 343   ASSERT_NE(brk_heap_address, reinterpret_cast<void*>(-1));
 344   ASSERT_TRUE(brk_heap_address != NULL);
 345   // 1 MB should get us past what TCMalloc pre-allocated before initializing
 346   // the sophisticated allocators.
 347   size_t kAllocSize = 1<<20;
 348   scoped_ptr<char, base::FreeDeleter> ptr(
 349       static_cast<char*>(malloc(kAllocSize)));
 350   ASSERT_TRUE(ptr != NULL);
 351   // If two pointers are separated by less than 512MB, they are considered
 352   // to be in the same area.
 353   // Our random pointer could be anywhere within 0x3fffffffffff (46bits),
 354   // and we are checking that it's not withing 1GB (30 bits) from two
 355   // addresses (brk and mmap heap). We have roughly one chance out of
 356   // 2^15 to flake.
 357   const size_t kAreaRadius = 1<<29;
 358   bool in_default_mmap_heap = ArePointersToSameArea(
 359       ptr.get(), default_mmap_heap_address, kAreaRadius);
 360   EXPECT_FALSE(in_default_mmap_heap);
 361
 362   bool in_default_brk_heap = ArePointersToSameArea(
 363       ptr.get(), brk_heap_address, kAreaRadius);
 364   EXPECT_FALSE(in_default_brk_heap);
 365
 366   // In the implementation, we always mask our random addresses with
 367   // kRandomMask, so we use it as an additional detection mechanism.
 368   const uintptr_t kRandomMask = 0x3fffffffffffULL;
 369   bool impossible_random_address =
 370       reinterpret_cast<uintptr_t>(ptr.get()) & ~kRandomMask;
 371   EXPECT_FALSE(impossible_random_address);
 372 }
 373
 374 #endif  // defined(OS_LINUX) && defined(__x86_64__)
 375
 376 }  // namespace