1 files changed, 234 insertions, 0 deletions
diff --git a/gfx/ots/RLBoxWOFF2Host.cpp b/gfx/ots/RLBoxWOFF2Host.cpp
new file mode 100644
index 0000000000..172300f8dd
--- /dev/null
+++ b/gfx/ots/RLBoxWOFF2Host.cpp
@@ -0,0 +1,234 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "RLBoxWOFF2Host.h"
+#include "nsPrintfCString.h"
+#include "nsThreadUtils.h"
+#include "mozilla/ClearOnShutdown.h"
+#include "mozilla/RLBoxUtils.h"
+#include "mozilla/ScopeExit.h"
+#include "opentype-sanitiser.h"  // For ots_ntohl
+
+using namespace rlbox;
+using namespace mozilla;
+
+tainted_woff2<BrotliDecoderResult> RLBoxBrotliDecoderDecompressCallback(
+    rlbox_sandbox_woff2& aSandbox, tainted_woff2<unsigned long> aEncodedSize,
+    tainted_woff2<const char*> aEncodedBuffer,
+    tainted_woff2<unsigned long*> aDecodedSize,
+    tainted_woff2<char*> aDecodedBuffer) {
+  if (!aEncodedBuffer || !aDecodedSize || !aDecodedBuffer) {
+    return BROTLI_DECODER_RESULT_ERROR;
+  }
+
+  // We don't create temporary buffers for brotli to operate on. Instead we
+  // pass a pointer to the in (encoded) and out (decoded) buffers. We check
+  // (specifically, unverified_safe_pointer checks) that the buffers are within
+  // the sandbox boundary (for the given sizes).
+
+  size_t encodedSize =
+      aEncodedSize.unverified_safe_because("Any size within sandbox is ok.");
+  const uint8_t* encodedBuffer = reinterpret_cast<const uint8_t*>(
+      aEncodedBuffer.unverified_safe_pointer_because(
+          encodedSize, "Pointer fits within sandbox"));
+
+  size_t decodedSize =
+      (*aDecodedSize).unverified_safe_because("Any size within sandbox is ok.");
+  uint8_t* decodedBuffer =
+      reinterpret_cast<uint8_t*>(aDecodedBuffer.unverified_safe_pointer_because(
+          decodedSize, "Pointer fits within sandbox"));
+
+  BrotliDecoderResult res = BrotliDecoderDecompress(
+      encodedSize, encodedBuffer, &decodedSize, decodedBuffer);
+
+  *aDecodedSize = decodedSize;
+
+  return res;
+}
+
+UniquePtr<RLBoxSandboxDataBase> RLBoxWOFF2SandboxPool::CreateSandboxData(
+    uint64_t aSize) {
+  // Create woff2 sandbox
+  auto sandbox = MakeUnique<rlbox_sandbox_woff2>();
+
+#if defined(MOZ_WASM_SANDBOXING_WOFF2)
+  const w2c_mem_capacity capacity =
+      get_valid_wasm2c_memory_capacity(aSize, true /* 32-bit wasm memory*/);
+  bool createOK = sandbox->create_sandbox(/* infallible = */ false, &capacity);
+#else
+  bool createOK = sandbox->create_sandbox();
+#endif
+  NS_ENSURE_TRUE(createOK, nullptr);
+
+  UniquePtr<RLBoxWOFF2SandboxData> sbxData =
+      MakeUnique<RLBoxWOFF2SandboxData>(aSize, std::move(sandbox));
+
+  // Register brotli callback
+  sbxData->mDecompressCallback = sbxData->Sandbox()->register_callback(
+      RLBoxBrotliDecoderDecompressCallback);
+  sbxData->Sandbox()->invoke_sandbox_function(RegisterWOFF2Callback,
+                                              sbxData->mDecompressCallback);
+
+  return sbxData;
+}
+
+StaticRefPtr<RLBoxWOFF2SandboxPool> RLBoxWOFF2SandboxPool::sSingleton;
+
+void RLBoxWOFF2SandboxPool::Initalize(size_t aDelaySeconds) {
+  AssertIsOnMainThread();
+  RLBoxWOFF2SandboxPool::sSingleton = new RLBoxWOFF2SandboxPool(aDelaySeconds);
+  ClearOnShutdown(&RLBoxWOFF2SandboxPool::sSingleton);
+}
+
+RLBoxWOFF2SandboxData::RLBoxWOFF2SandboxData(
+    uint64_t aSize, mozilla::UniquePtr<rlbox_sandbox_woff2> aSandbox)
+    : mozilla::RLBoxSandboxDataBase(aSize), mSandbox(std::move(aSandbox)) {
+  MOZ_COUNT_CTOR(RLBoxWOFF2SandboxData);
+}
+
+RLBoxWOFF2SandboxData::~RLBoxWOFF2SandboxData() {
+  MOZ_ASSERT(mSandbox);
+  mDecompressCallback.unregister();
+  mSandbox->destroy_sandbox();
+  MOZ_COUNT_DTOR(RLBoxWOFF2SandboxData);
+}
+
+static bool Woff2SizeValidator(size_t aLength, size_t aSize, size_t aLimit) {
+  if (aSize < aLength) {
+    NS_WARNING("Size of decompressed WOFF 2.0 is less than compressed size");
+    return false;
+  } else if (aSize == 0) {
+    NS_WARNING("Size of decompressed WOFF 2.0 is set to 0");
+    return false;
+  } else if (aSize > aLimit) {
+    NS_WARNING(
+        nsPrintfCString("Size of decompressed WOFF 2.0 font exceeds %gMB",
+                        aLimit / (1024.0 * 1024.0))
+            .get());
+    return false;
+  }
+  return true;
+}
+
+// Code replicated from modules/woff2/src/woff2_dec.cc
+// This is used both to compute the expected size of the Woff2 RLBox sandbox
+// as well as internally by WOFF2 as a performance hint
+static uint32_t ComputeWOFF2FinalSize(const uint8_t* aData, size_t aLength,
+                                      size_t aLimit) {
+  // Expected size is stored as a 4 byte value starting from the 17th byte
+  if (aLength < 20) {
+    return 0;
+  }
+
+  uint32_t decompressedSize = 0;
+  const void* location = &(aData[16]);
+  std::memcpy(&decompressedSize, location, sizeof(decompressedSize));
+  decompressedSize = ots_ntohl(decompressedSize);
+
+  if (!Woff2SizeValidator(aLength, decompressedSize, aLimit)) {
+    return 0;
+  }
+
+  return decompressedSize;
+}
+
+template <typename T>
+using TransferBufferToWOFF2 =
+    mozilla::RLBoxTransferBufferToSandbox<T, rlbox_woff2_sandbox_type>;
+template <typename T>
+using WOFF2Alloc = mozilla::RLBoxAllocateInSandbox<T, rlbox_woff2_sandbox_type>;
+
+bool RLBoxProcessWOFF2(ots::FontFile* aHeader, ots::OTSStream* aOutput,
+                       const uint8_t* aData, size_t aLength, uint32_t aIndex,
+                       ProcessTTCFunc* aProcessTTC,
+                       ProcessTTFFunc* aProcessTTF) {
+  MOZ_ASSERT(aProcessTTC);
+  MOZ_ASSERT(aProcessTTF);
+
+  // We index into aData before processing it (very end of this function). Our
+  // validator ensures that the untrusted size is greater than aLength, so we
+  // just need to conservatively ensure that aLength is greater than the highest
+  // index (7).
+  NS_ENSURE_TRUE(aLength >= 8, false);
+
+  size_t limit =
+      std::min(size_t(OTS_MAX_DECOMPRESSED_FILE_SIZE), aOutput->size());
+  uint32_t expectedSize = ComputeWOFF2FinalSize(aData, aLength, limit);
+  NS_ENSURE_TRUE(expectedSize > 0, false);
+
+  // The sandbox should have space for the input, output and misc allocations
+  // To account for misc allocations, we'll set the sandbox size to:
+  // twice the size of (input + output)
+
+  const uint64_t expectedSandboxSize =
+      static_cast<uint64_t>(2 * (aLength + expectedSize));
+  auto sandboxPoolData =
+      RLBoxWOFF2SandboxPool::sSingleton->PopOrCreate(expectedSandboxSize);
+  NS_ENSURE_TRUE(sandboxPoolData, false);
+
+  const auto* sandboxData =
+      static_cast<const RLBoxWOFF2SandboxData*>(sandboxPoolData->SandboxData());
+  MOZ_ASSERT(sandboxData);
+
+  auto* sandbox = sandboxData->Sandbox();
+
+  // Transfer aData into the sandbox.
+
+  auto data = TransferBufferToWOFF2<char>(
+      sandbox, reinterpret_cast<const char*>(aData), aLength);
+  NS_ENSURE_TRUE(*data, false);
+
+  // Perform the actual conversion to TTF.
+
+  auto sizep = WOFF2Alloc<unsigned long>(sandbox);
+  auto bufp = WOFF2Alloc<char*>(sandbox);
+  auto bufOwnerString =
+      WOFF2Alloc<void*>(sandbox);  // pointer to string that owns the bufer
+
+  if (!sandbox
+           ->invoke_sandbox_function(RLBoxConvertWOFF2ToTTF, *data, aLength,
+                                     expectedSize, sizep.get(),
+                                     bufOwnerString.get(), bufp.get())
+           .unverified_safe_because(
+               "The ProcessTT* functions validate the decompressed data.")) {
+    return false;
+  }
+
+  auto bufCleanup = mozilla::MakeScopeExit([&sandbox, &bufOwnerString] {
+    // Delete the string created by RLBoxConvertWOFF2ToTTF.
+    sandbox->invoke_sandbox_function(RLBoxDeleteWOFF2String,
+                                     bufOwnerString.get());
+  });
+
+  // Get the actual decompression size and validate it.
+  // We need to validate the size again. RLBoxConvertWOFF2ToTTF works even if
+  // the computed size (with ComputeWOFF2FinalSize) is wrong, so we can't
+  // trust the expectedSize to be the same as size sizep.
+  bool validateOK = false;
+  unsigned long actualSize =
+      (*sizep.get()).copy_and_verify([&](unsigned long val) {
+        validateOK = Woff2SizeValidator(aLength, val, limit);
+        return val;
+      });
+
+  NS_ENSURE_TRUE(validateOK, false);
+
+  const uint8_t* decompressed = reinterpret_cast<const uint8_t*>(
+      (*bufp.get())
+          .unverified_safe_pointer_because(
+              actualSize,
+              "Only care that the buffer is within sandbox boundary."));
+
+  // Since ProcessTT* memcpy from the buffer, make sure it's not null.
+  NS_ENSURE_TRUE(decompressed, false);
+
+  if (aData[4] == 't' && aData[5] == 't' && aData[6] == 'c' &&
+      aData[7] == 'f') {
+    return aProcessTTC(aHeader, aOutput, decompressed, actualSize, aIndex);
+  }
+  ots::Font font(aHeader);
+  return aProcessTTF(aHeader, &font, aOutput, decompressed, actualSize, 0);
+}