1 files changed, 167 insertions, 0 deletions
diff --git a/security/sandbox/chromium/base/hash/hash.cc b/security/sandbox/chromium/base/hash/hash.cc
new file mode 100644
index 0000000000..c96f8bc843
--- /dev/null
+++ b/security/sandbox/chromium/base/hash/hash.cc
@@ -0,0 +1,167 @@
+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "base/hash/hash.h"
+
+#include "base/rand_util.h"
+#include "base/third_party/cityhash/city.h"
+#include "build/build_config.h"
+
+// Definition in base/third_party/superfasthash/superfasthash.c. (Third-party
+// code did not come with its own header file, so declaring the function here.)
+// Note: This algorithm is also in Blink under Source/wtf/StringHasher.h.
+extern "C" uint32_t SuperFastHash(const char* data, int len);
+
+namespace base {
+
+namespace {
+
+size_t FastHashImpl(base::span<const uint8_t> data) {
+  // We use the updated CityHash within our namespace (not the deprecated
+  // version from third_party/smhasher).
+#if defined(ARCH_CPU_64_BITS)
+  return base::internal::cityhash_v111::CityHash64(
+      reinterpret_cast<const char*>(data.data()), data.size());
+#else
+  return base::internal::cityhash_v111::CityHash32(
+      reinterpret_cast<const char*>(data.data()), data.size());
+#endif
+}
+
+// Implement hashing for pairs of at-most 32 bit integer values.
+// When size_t is 32 bits, we turn the 64-bit hash code into 32 bits by using
+// multiply-add hashing. This algorithm, as described in
+// Theorem 4.3.3 of the thesis "Über die Komplexität der Multiplikation in
+// eingeschränkten Branchingprogrammmodellen" by Woelfel, is:
+//
+//   h32(x32, y32) = (h64(x32, y32) * rand_odd64 + rand16 * 2^16) % 2^64 / 2^32
+//
+// Contact danakj@chromium.org for any questions.
+size_t HashInts32Impl(uint32_t value1, uint32_t value2) {
+  uint64_t value1_64 = value1;
+  uint64_t hash64 = (value1_64 << 32) | value2;
+
+  if (sizeof(size_t) >= sizeof(uint64_t))
+    return static_cast<size_t>(hash64);
+
+  uint64_t odd_random = 481046412LL << 32 | 1025306955LL;
+  uint32_t shift_random = 10121U << 16;
+
+  hash64 = hash64 * odd_random + shift_random;
+  size_t high_bits =
+      static_cast<size_t>(hash64 >> (8 * (sizeof(uint64_t) - sizeof(size_t))));
+  return high_bits;
+}
+
+// Implement hashing for pairs of up-to 64-bit integer values.
+// We use the compound integer hash method to produce a 64-bit hash code, by
+// breaking the two 64-bit inputs into 4 32-bit values:
+// http://opendatastructures.org/versions/edition-0.1d/ods-java/node33.html#SECTION00832000000000000000
+// Then we reduce our result to 32 bits if required, similar to above.
+size_t HashInts64Impl(uint64_t value1, uint64_t value2) {
+  uint32_t short_random1 = 842304669U;
+  uint32_t short_random2 = 619063811U;
+  uint32_t short_random3 = 937041849U;
+  uint32_t short_random4 = 3309708029U;
+
+  uint32_t value1a = static_cast<uint32_t>(value1 & 0xffffffff);
+  uint32_t value1b = static_cast<uint32_t>((value1 >> 32) & 0xffffffff);
+  uint32_t value2a = static_cast<uint32_t>(value2 & 0xffffffff);
+  uint32_t value2b = static_cast<uint32_t>((value2 >> 32) & 0xffffffff);
+
+  uint64_t product1 = static_cast<uint64_t>(value1a) * short_random1;
+  uint64_t product2 = static_cast<uint64_t>(value1b) * short_random2;
+  uint64_t product3 = static_cast<uint64_t>(value2a) * short_random3;
+  uint64_t product4 = static_cast<uint64_t>(value2b) * short_random4;
+
+  uint64_t hash64 = product1 + product2 + product3 + product4;
+
+  if (sizeof(size_t) >= sizeof(uint64_t))
+    return static_cast<size_t>(hash64);
+
+  uint64_t odd_random = 1578233944LL << 32 | 194370989LL;
+  uint32_t shift_random = 20591U << 16;
+
+  hash64 = hash64 * odd_random + shift_random;
+  size_t high_bits =
+      static_cast<size_t>(hash64 >> (8 * (sizeof(uint64_t) - sizeof(size_t))));
+  return high_bits;
+}
+
+// The random seed is used to perturb the output of base::FastHash() and
+// base::HashInts() so that it is only deterministic within the lifetime of a
+// process. This prevents inadvertent dependencies on the underlying
+// implementation, e.g. anything that persists the hash value and expects it to
+// be unchanging will break.
+//
+// Note: this is the same trick absl uses to generate a random seed. This is
+// more robust than using base::RandBytes(), which can fail inside a sandboxed
+// environment. Note that without ASLR, the seed won't be quite as random...
+#if DCHECK_IS_ON()
+constexpr const void* kSeed = &kSeed;
+#endif
+
+template <typename T>
+T Scramble(T input) {
+#if DCHECK_IS_ON()
+  return HashInts64Impl(input, reinterpret_cast<uintptr_t>(kSeed));
+#else
+  return input;
+#endif
+}
+
+}  // namespace
+
+size_t FastHash(base::span<const uint8_t> data) {
+  return Scramble(FastHashImpl(data));
+}
+
+uint32_t Hash(const void* data, size_t length) {
+  // Currently our in-memory hash is the same as the persistent hash. The
+  // split between in-memory and persistent hash functions is maintained to
+  // allow the in-memory hash function to be updated in the future.
+  return PersistentHash(data, length);
+}
+
+uint32_t Hash(const std::string& str) {
+  return PersistentHash(as_bytes(make_span(str)));
+}
+
+uint32_t Hash(const string16& str) {
+  return PersistentHash(as_bytes(make_span(str)));
+}
+
+uint32_t PersistentHash(span<const uint8_t> data) {
+  // This hash function must not change, since it is designed to be persistable
+  // to disk.
+  if (data.size() > static_cast<size_t>(std::numeric_limits<int>::max())) {
+    NOTREACHED();
+    return 0;
+  }
+  return ::SuperFastHash(reinterpret_cast<const char*>(data.data()),
+                         static_cast<int>(data.size()));
+}
+
+uint32_t PersistentHash(const void* data, size_t length) {
+  return PersistentHash(make_span(static_cast<const uint8_t*>(data), length));
+}
+
+uint32_t PersistentHash(const std::string& str) {
+  return PersistentHash(str.data(), str.size());
+}
+
+size_t HashInts32(uint32_t value1, uint32_t value2) {
+  return Scramble(HashInts32Impl(value1, value2));
+}
+
+// Implement hashing for pairs of up-to 64-bit integer values.
+// We use the compound integer hash method to produce a 64-bit hash code, by
+// breaking the two 64-bit inputs into 4 32-bit values:
+// http://opendatastructures.org/versions/edition-0.1d/ods-java/node33.html#SECTION00832000000000000000
+// Then we reduce our result to 32 bits if required, similar to above.
+size_t HashInts64(uint64_t value1, uint64_t value2) {
+  return Scramble(HashInts64Impl(value1, value2));
+}
+
+}  // namespace base