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