Add hinting to improve ASLR for macos (all allocations) and linux (newly added allocation types).

src/platform-macos.cc

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 74 matching lines @@
   if (-1.0 < x && x < 0.0) {
     return -0.0;
   } else {
     return ceil(x);
   }
 }
 
 
 static Mutex* limit_mutex = NULL;
 
+static void* GetRandomMmapAddr() {

[Vyacheslav Egorov (Chromium), 2011/10/04 09:18:33]

consider moving somewhere (e.g. platfrom-posix.cc) to avoid duplication.

platform can define the range of unpopular addresses which shared implementation
would use.

[Cris Neckar, 2011/10/04 19:20:47]

Done.

+  Isolate* isolate = Isolate::UncheckedCurrent();
+  // Note that the current isolate isn't set up in a call path via
+  // CpuFeatures::Probe. We don't care about randomization in this case because
+  // the code page is immediately freed.
+  if (isolate != NULL) {
+#ifdef V8_TARGET_ARCH_X64
+    uint64_t rnd1 = V8::RandomPrivate(isolate);
+    uint64_t rnd2 = V8::RandomPrivate(isolate);
+    uint64_t rnd2 = V8::RandomPrivate(isolate);
+    raw_addr &= V8_UINT64_C(0x3ffffffff000);
+#else
+    uint32_t raw_addr = V8::RandomPrivate(isolate);
+    // The range 0x20000000 - 0x60000000 is relatively unpopulated on macos
+    // 10.6 and 10.7.
+    raw_addr &= 0x3ffff000;
+    raw_addr += 0x20000000;
+#endif
+    return reinterpret_cast<void*>(raw_addr);
+  }
+  return NULL;
+}
 
 void OS::Setup() {
-  // Seed the random number generator.
-  // Convert the current time to a 64-bit integer first, before converting it
-  // to an unsigned. Going directly will cause an overflow and the seed to be
-  // set to all ones. The seed will be identical for different instances that
-  // call this setup code within the same millisecond.
-  uint64_t seed = static_cast<uint64_t>(TimeCurrentMillis());
+  // Seed the random number generator. We preserve microsecond resolution.
+  uint64_t seed = Ticks() ^ (getpid() << 16);
   srandom(static_cast<unsigned int>(seed));
   limit_mutex = CreateMutex();
 }
 
 
 // We keep the lowest and highest addresses mapped as a quick way of
 // determining that pointers are outside the heap (used mostly in assertions
 // and verification).  The estimate is conservative, ie, not all addresses in
 // 'allocated' space are actually allocated to our heap.  The range is
 // [lowest, highest), inclusive on the low and and exclusive on the high end.
@@ skipping 28 matching lines @@
 // tools like vmmap(1).
 static const int kMmapFd = VM_MAKE_TAG(255);
 static const off_t kMmapFdOffset = 0;
 
 
 void* OS::Allocate(const size_t requested,
                    size_t* allocated,
                    bool is_executable) {
   const size_t msize = RoundUp(requested, getpagesize());
   int prot = PROT_READ | PROT_WRITE | (is_executable ? PROT_EXEC : 0);
-  void* mbase = mmap(NULL, msize, prot,
+  void* mbase = mmap(GetRandomMmapAddr(), msize, prot,

[Vyacheslav Egorov (Chromium), 2011/10/04 09:18:33]

formatting: one argument per line

[Cris Neckar, 2011/10/04 19:20:47]

Done.

                      MAP_PRIVATE | MAP_ANON,
                      kMmapFd, kMmapFdOffset);
   if (mbase == MAP_FAILED) {
     LOG(Isolate::Current(), StringEvent("OS::Allocate", "mmap failed"));
     return NULL;
   }
   *allocated = msize;
   UpdateAllocatedSpaceLimits(mbase, msize);
   return mbase;
 }
@@ skipping 38 matching lines @@
 
 
 OS::MemoryMappedFile* OS::MemoryMappedFile::open(const char* name) {
   FILE* file = fopen(name, "r+");
   if (file == NULL) return NULL;
 
   fseek(file, 0, SEEK_END);
   int size = ftell(file);
 
   void* memory =
-      mmap(0, size, PROT_READ | PROT_WRITE, MAP_SHARED, fileno(file), 0);
+      mmap(GetRandomMmapAddr(), size, PROT_READ | PROT_WRITE,

[Vyacheslav Egorov (Chromium), 2011/10/04 09:18:33]

formatting: one argument per line

[Cris Neckar, 2011/10/04 19:20:47]

Done.

+           MAP_SHARED, fileno(file), 0);
   return new PosixMemoryMappedFile(file, memory, size);
 }
 
 
 OS::MemoryMappedFile* OS::MemoryMappedFile::create(const char* name, int size,
     void* initial) {
   FILE* file = fopen(name, "w+");
   if (file == NULL) return NULL;
   int result = fwrite(initial, size, 1, file);
   if (result < 1) {
     fclose(file);
     return NULL;
   }
   void* memory =
-      mmap(0, size, PROT_READ | PROT_WRITE, MAP_SHARED, fileno(file), 0);
+      mmap(GetRandomMmapAddr(), size, PROT_READ | PROT_WRITE,

[Vyacheslav Egorov (Chromium), 2011/10/04 09:18:33]

formatting: one argument per line

[Cris Neckar, 2011/10/04 19:20:47]

Done.

+           MAP_SHARED, fileno(file), 0);
   return new PosixMemoryMappedFile(file, memory, size);
 }
 
 
 PosixMemoryMappedFile::~PosixMemoryMappedFile() {
   if (memory_) OS::Free(memory_, size_);
   fclose(file_);
 }
 
 
@@ skipping 103 matching lines @@
 
 VirtualMemory::VirtualMemory(size_t size)
     : address_(ReserveRegion(size)), size_(size) { }
 
 
 VirtualMemory::VirtualMemory(size_t size, size_t alignment)
     : address_(NULL), size_(0) {
   ASSERT(IsAligned(alignment, static_cast<intptr_t>(OS::AllocateAlignment())));
   size_t request_size = RoundUp(size + alignment,
                                 static_cast<intptr_t>(OS::AllocateAlignment()));
-  void* reservation = mmap(NULL,
+  void* reservation = mmap(GetRandomMmapAddr(),
                            request_size,
                            PROT_NONE,
                            MAP_PRIVATE | MAP_ANON | MAP_NORESERVE,
                            kMmapFd,
                            kMmapFdOffset);
   if (reservation == MAP_FAILED) return;
 
   Address base = static_cast<Address>(reservation);
   Address aligned_base = RoundUp(base, alignment);
   ASSERT_LE(base, aligned_base);
@@ skipping 30 matching lines @@
 }
 
 
 void VirtualMemory::Reset() {
   address_ = NULL;
   size_ = 0;
 }
 
 
 void* VirtualMemory::ReserveRegion(size_t size) {
-  void* result = mmap(NULL,
+  void* result = mmap(GetRandomMmapAddr(),
                       size,
                       PROT_NONE,
                       MAP_PRIVATE | MAP_ANON | MAP_NORESERVE,
                       kMmapFd,
                       kMmapFdOffset);
 
   if (result == MAP_FAILED) return NULL;
 
   return result;
 }
@@ skipping 468 matching lines @@
 
 
 void Sampler::Stop() {
   ASSERT(IsActive());
   SamplerThread::RemoveActiveSampler(this);
   SetActive(false);
 }
 
 
 } }  // namespace v8::internal