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