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