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 // - OS_WIN does not use tcmalloc crbug.com/242304
  50 #if !defined(NO_TCMALLOC) && !defined(ADDRESS_SANITIZER) && \
  51     !defined(OS_IOS) && !defined(OS_MACOSX) && !defined(OS_WIN)
  52   #define TCMALLOC_TEST(function) function
  53 #else
  54   #define TCMALLOC_TEST(function) DISABLED_##function
  55 #endif
  56
  57 // TODO(jln): switch to std::numeric_limits<int>::max() when we switch to
  58 // C++11.
  59 const size_t kTooBigAllocSize = INT_MAX;
  60
  61 // Detect runtime TCMalloc bypasses.
  62 bool IsTcMallocBypassed() {
  63 #if defined(OS_LINUX) || defined(OS_CHROMEOS)
  64   // This should detect a TCMalloc bypass from Valgrind.
  65   char* g_slice = getenv("G_SLICE");
  66   if (g_slice && !strcmp(g_slice, "always-malloc"))
  67     return true;
  68 #endif
  69   return false;
  70 }
  71
  72 bool CallocDiesOnOOM() {
  73 // The wrapper function in base/process_util_linux.cc that is used when we
  74 // compile without TCMalloc will just die on OOM instead of returning NULL.
  75 // This function is explicitly disabled if we compile with AddressSanitizer,
  76 // MemorySanitizer or ThreadSanitizer.
  77 #if defined(OS_LINUX) && defined(NO_TCMALLOC) && \
  78     (!defined(ADDRESS_SANITIZER) && \
  79      !defined(MEMORY_SANITIZER) && \
  80      !defined(THREAD_SANITIZER))
  81   return true;
  82 #else
  83   return false;
  84 #endif
  85 }
  86
  87 // Fake test that allow to know the state of TCMalloc by looking at bots.
  88 TEST(SecurityTest, TCMALLOC_TEST(IsTCMallocDynamicallyBypassed)) {
  89   printf("Malloc is dynamically bypassed: %s\n",
  90          IsTcMallocBypassed() ? "yes." : "no.");
  91 }
  92
  93 // The MemoryAllocationRestrictions* tests test that we can not allocate a
  94 // memory range that cannot be indexed via an int. This is used to mitigate
  95 // vulnerabilities in libraries that use int instead of size_t.  See
  96 // crbug.com/169327.
  97
  98 TEST(SecurityTest, TCMALLOC_TEST(MemoryAllocationRestrictionsMalloc)) {
  99   if (!IsTcMallocBypassed()) {
 100     scoped_ptr<char, base::FreeDeleter> ptr(static_cast<char*>(
 101         HideValueFromCompiler(malloc(kTooBigAllocSize))));
 102     ASSERT_TRUE(!ptr);
 103   }
 104 }
 105
 106 TEST(SecurityTest, TCMALLOC_TEST(MemoryAllocationRestrictionsCalloc)) {
 107   if (!IsTcMallocBypassed()) {
 108     scoped_ptr<char, base::FreeDeleter> ptr(static_cast<char*>(
 109         HideValueFromCompiler(calloc(kTooBigAllocSize, 1))));
 110     ASSERT_TRUE(!ptr);
 111   }
 112 }
 113
 114 TEST(SecurityTest, TCMALLOC_TEST(MemoryAllocationRestrictionsRealloc)) {
 115   if (!IsTcMallocBypassed()) {
 116     char* orig_ptr = static_cast<char*>(malloc(1));
 117     ASSERT_TRUE(orig_ptr);
 118     scoped_ptr<char, base::FreeDeleter> ptr(static_cast<char*>(
 119         HideValueFromCompiler(realloc(orig_ptr, kTooBigAllocSize))));
 120     ASSERT_TRUE(!ptr);
 121     // If realloc() did not succeed, we need to free orig_ptr.
 122     free(orig_ptr);
 123   }
 124 }
 125
 126 typedef struct {
 127   char large_array[kTooBigAllocSize];
 128 } VeryLargeStruct;
 129
 130 TEST(SecurityTest, TCMALLOC_TEST(MemoryAllocationRestrictionsNew)) {
 131   if (!IsTcMallocBypassed()) {
 132     scoped_ptr<VeryLargeStruct> ptr(
 133         HideValueFromCompiler(new (nothrow) VeryLargeStruct));
 134     ASSERT_TRUE(!ptr);
 135   }
 136 }
 137
 138 TEST(SecurityTest, TCMALLOC_TEST(MemoryAllocationRestrictionsNewArray)) {
 139   if (!IsTcMallocBypassed()) {
 140     scoped_ptr<char[]> ptr(
 141         HideValueFromCompiler(new (nothrow) char[kTooBigAllocSize]));
 142     ASSERT_TRUE(!ptr);
 143   }
 144 }
 145
 146 // The tests bellow check for overflows in new[] and calloc().
 147
 148 #if defined(OS_IOS) || defined(OS_WIN)
 149   #define DISABLE_ON_IOS_AND_WIN(function) DISABLED_##function
 150 #else
 151   #define DISABLE_ON_IOS_AND_WIN(function) function
 152 #endif
 153
 154 // There are platforms where these tests are known to fail. We would like to
 155 // be able to easily check the status on the bots, but marking tests as
 156 // FAILS_ is too clunky.
 157 void OverflowTestsSoftExpectTrue(bool overflow_detected) {
 158   if (!overflow_detected) {
 159 #if defined(OS_LINUX) || defined(OS_ANDROID) || defined(OS_MACOSX)
 160     // Sadly, on Linux, Android, and OSX we don't have a good story yet. Don't
 161     // fail the test, but report.
 162     printf("Platform has overflow: %s\n",
 163            !overflow_detected ? "yes." : "no.");
 164 #else
 165     // Otherwise, fail the test. (Note: EXPECT are ok in subfunctions, ASSERT
 166     // aren't).
 167     EXPECT_TRUE(overflow_detected);
 168 #endif
 169   }
 170 }
 171
 172 // Test array[TooBig][X] and array[X][TooBig] allocations for int overflows.
 173 // IOS doesn't honor nothrow, so disable the test there.
 174 // Crashes on Windows Dbg builds, disable there as well.
 175 TEST(SecurityTest, DISABLE_ON_IOS_AND_WIN(NewOverflow)) {
 176   const size_t kArraySize = 4096;
 177   // We want something "dynamic" here, so that the compiler doesn't
 178   // immediately reject crazy arrays.
 179   const size_t kDynamicArraySize = HideValueFromCompiler(kArraySize);
 180   // numeric_limits are still not constexpr until we switch to C++11, so we
 181   // use an ugly cast.
 182   const size_t kMaxSizeT = ~static_cast<size_t>(0);
 183   ASSERT_EQ(numeric_limits<size_t>::max(), kMaxSizeT);
 184   const size_t kArraySize2 = kMaxSizeT / kArraySize + 10;
 185   const size_t kDynamicArraySize2 = HideValueFromCompiler(kArraySize2);
 186   {
 187     scoped_ptr<char[][kArraySize]> array_pointer(new (nothrow)
 188         char[kDynamicArraySize2][kArraySize]);
 189     OverflowTestsSoftExpectTrue(!array_pointer);
 190   }
 191   // On windows, the compiler prevents static array sizes of more than
 192   // 0x7fffffff (error C2148).
 193 #if !defined(OS_WIN) || !defined(ARCH_CPU_64_BITS)
 194   {
 195     scoped_ptr<char[][kArraySize2]> array_pointer(new (nothrow)
 196         char[kDynamicArraySize][kArraySize2]);
 197     OverflowTestsSoftExpectTrue(!array_pointer);
 198   }
 199 #endif  // !defined(OS_WIN) || !defined(ARCH_CPU_64_BITS)
 200 }
 201
 202 // Call calloc(), eventually free the memory and return whether or not
 203 // calloc() did succeed.
 204 bool CallocReturnsNull(size_t nmemb, size_t size) {
 205   scoped_ptr<char, base::FreeDeleter> array_pointer(
 206       static_cast<char*>(calloc(nmemb, size)));
 207   // We need the call to HideValueFromCompiler(): we have seen LLVM
 208   // optimize away the call to calloc() entirely and assume
 209   // the pointer to not be NULL.
 210   return HideValueFromCompiler(array_pointer.get()) == NULL;
 211 }
 212
 213 // Test if calloc() can overflow.
 214 TEST(SecurityTest, CallocOverflow) {
 215   const size_t kArraySize = 4096;
 216   const size_t kMaxSizeT = numeric_limits<size_t>::max();
 217   const size_t kArraySize2 = kMaxSizeT / kArraySize + 10;
 218   if (!CallocDiesOnOOM()) {
 219     EXPECT_TRUE(CallocReturnsNull(kArraySize, kArraySize2));
 220     EXPECT_TRUE(CallocReturnsNull(kArraySize2, kArraySize));
 221   } else {
 222     // It's also ok for calloc to just terminate the process.
 223 #if defined(GTEST_HAS_DEATH_TEST)
 224     EXPECT_DEATH(CallocReturnsNull(kArraySize, kArraySize2), "");
 225     EXPECT_DEATH(CallocReturnsNull(kArraySize2, kArraySize), "");
 226 #endif  // GTEST_HAS_DEATH_TEST
 227   }
 228 }
 229
 230 #if (defined(OS_LINUX) || defined(OS_CHROMEOS)) && defined(__x86_64__)
 231 // Useful for debugging.
 232 void PrintProcSelfMaps() {
 233   int fd = open("/proc/self/maps", O_RDONLY);
 234   file_util::ScopedFD fd_closer(&fd);
 235   ASSERT_GE(fd, 0);
 236   char buffer[1<<13];
 237   int ret;
 238   ret = read(fd, buffer, sizeof(buffer) - 1);
 239   ASSERT_GT(ret, 0);
 240   buffer[ret - 1] = 0;
 241   fprintf(stdout, "%s\n", buffer);
 242 }
 243
 244 // Check if ptr1 and ptr2 are separated by less than size chars.
 245 bool ArePointersToSameArea(void* ptr1, void* ptr2, size_t size) {
 246   ptrdiff_t ptr_diff = reinterpret_cast<char*>(std::max(ptr1, ptr2)) -
 247                        reinterpret_cast<char*>(std::min(ptr1, ptr2));
 248   return static_cast<size_t>(ptr_diff) <= size;
 249 }
 250
 251 // Check if TCMalloc uses an underlying random memory allocator.
 252 TEST(SecurityTest, TCMALLOC_TEST(RandomMemoryAllocations)) {
 253   if (IsTcMallocBypassed())
 254     return;
 255   size_t kPageSize = 4096;  // We support x86_64 only.
 256   // Check that malloc() returns an address that is neither the kernel's
 257   // un-hinted mmap area, nor the current brk() area. The first malloc() may
 258   // not be at a random address because TCMalloc will first exhaust any memory
 259   // that it has allocated early on, before starting the sophisticated
 260   // allocators.
 261   void* default_mmap_heap_address =
 262       mmap(0, kPageSize, PROT_READ|PROT_WRITE,
 263            MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
 264   ASSERT_NE(default_mmap_heap_address,
 265             static_cast<void*>(MAP_FAILED));
 266   ASSERT_EQ(munmap(default_mmap_heap_address, kPageSize), 0);
 267   void* brk_heap_address = sbrk(0);
 268   ASSERT_NE(brk_heap_address, reinterpret_cast<void*>(-1));
 269   ASSERT_TRUE(brk_heap_address != NULL);
 270   // 1 MB should get us past what TCMalloc pre-allocated before initializing
 271   // the sophisticated allocators.
 272   size_t kAllocSize = 1<<20;
 273   scoped_ptr<char, base::FreeDeleter> ptr(
 274       static_cast<char*>(malloc(kAllocSize)));
 275   ASSERT_TRUE(ptr != NULL);
 276   // If two pointers are separated by less than 512MB, they are considered
 277   // to be in the same area.
 278   // Our random pointer could be anywhere within 0x3fffffffffff (46bits),
 279   // and we are checking that it's not withing 1GB (30 bits) from two
 280   // addresses (brk and mmap heap). We have roughly one chance out of
 281   // 2^15 to flake.
 282   const size_t kAreaRadius = 1<<29;
 283   bool in_default_mmap_heap = ArePointersToSameArea(
 284       ptr.get(), default_mmap_heap_address, kAreaRadius);
 285   EXPECT_FALSE(in_default_mmap_heap);
 286
 287   bool in_default_brk_heap = ArePointersToSameArea(
 288       ptr.get(), brk_heap_address, kAreaRadius);
 289   EXPECT_FALSE(in_default_brk_heap);
 290
 291   // In the implementation, we always mask our random addresses with
 292   // kRandomMask, so we use it as an additional detection mechanism.
 293   const uintptr_t kRandomMask = 0x3fffffffffffULL;
 294   bool impossible_random_address =
 295       reinterpret_cast<uintptr_t>(ptr.get()) & ~kRandomMask;
 296   EXPECT_FALSE(impossible_random_address);
 297 }
 298
 299 #endif  // (defined(OS_LINUX) || defined(OS_CHROMEOS)) && defined(__x86_64__)
 300
 301 }  // namespace