Refactor WebCrypto code

content/child/webcrypto/nss/aes_cbc_nss.cc

+// 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 <cryptohi.h>
+
+#include "content/child/webcrypto/crypto_data.h"
+#include "content/child/webcrypto/nss/aes_key_nss.h"
+#include "content/child/webcrypto/nss/key_nss.h"
+#include "content/child/webcrypto/nss/util_nss.h"
+#include "content/child/webcrypto/status.h"
+#include "content/child/webcrypto/webcrypto_util.h"
+#include "crypto/scoped_nss_types.h"
+#include "third_party/WebKit/public/platform/WebCryptoAlgorithmParams.h"
+
+namespace content {
+
+namespace webcrypto {
+
+namespace {
+
+Status AesCbcEncryptDecrypt(EncryptOrDecrypt mode,
+                            const blink::WebCryptoAlgorithm& algorithm,
+                            const blink::WebCryptoKey& key,
+                            const CryptoData& data,
+                            std::vector<uint8>* buffer) {
+  const blink::WebCryptoAesCbcParams* params = algorithm.aesCbcParams();
+  if (!params)
+    return Status::ErrorUnexpected();
+
+  CryptoData iv(params->iv().data(), params->iv().size());
+  if (iv.byte_length() != 16)
+    return Status::ErrorIncorrectSizeAesCbcIv();
+
+  PK11SymKey* sym_key = SymKeyNss::Cast(key)->key();
+
+  CK_ATTRIBUTE_TYPE operation = (mode == ENCRYPT) ? CKA_ENCRYPT : CKA_DECRYPT;
+
+  SECItem iv_item = MakeSECItemForBuffer(iv);
+
+  crypto::ScopedSECItem param(PK11_ParamFromIV(CKM_AES_CBC_PAD, &iv_item));
+  if (!param)
+    return Status::OperationError();
+
+  crypto::ScopedPK11Context context(PK11_CreateContextBySymKey(
+      CKM_AES_CBC_PAD, operation, sym_key, param.get()));
+
+  if (!context.get())
+    return Status::OperationError();
+
+  // Oddly PK11_CipherOp takes input and output lengths as "int" rather than
+  // "unsigned int". Do some checks now to avoid integer overflowing.
+  if (data.byte_length() >= INT_MAX - AES_BLOCK_SIZE) {
+    // TODO(eroman): Handle this by chunking the input fed into NSS. Right now
+    // it doesn't make much difference since the one-shot API would end up
+    // blowing out the memory and crashing anyway.
+    return Status::ErrorDataTooLarge();
+  }
+
+  // PK11_CipherOp does an invalid memory access when given empty decryption
+  // input, or input which is not a multiple of the block size. See also
+  // https://bugzilla.mozilla.com/show_bug.cgi?id=921687.
+  if (operation == CKA_DECRYPT &&
+      (data.byte_length() == 0 || (data.byte_length() % AES_BLOCK_SIZE != 0))) {
+    return Status::OperationError();
+  }
+
+  // TODO(eroman): Refine the output buffer size. It can be computed exactly for
+  //               encryption, and can be smaller for decryption.
+  unsigned int output_max_len = data.byte_length() + AES_BLOCK_SIZE;
+  CHECK_GT(output_max_len, data.byte_length());
+
+  buffer->resize(output_max_len);
+
+  unsigned char* buffer_data = Uint8VectorStart(buffer);
+
+  int output_len;
+  if (SECSuccess != PK11_CipherOp(context.get(),
+                                  buffer_data,
+                                  &output_len,
+                                  buffer->size(),
+                                  data.bytes(),
+                                  data.byte_length())) {
+    return Status::OperationError();
+  }
+
+  unsigned int final_output_chunk_len;
+  if (SECSuccess != PK11_DigestFinal(context.get(),
+                                     buffer_data + output_len,
+                                     &final_output_chunk_len,
+                                     output_max_len - output_len)) {
+    return Status::OperationError();
+  }
+
+  buffer->resize(final_output_chunk_len + output_len);
+  return Status::Success();
+}
+
+class AesCbcImplementation : public AesAlgorithm {
+ public:
+  AesCbcImplementation() : AesAlgorithm(CKM_AES_CBC, "CBC") {}
+
+  virtual Status Encrypt(const blink::WebCryptoAlgorithm& algorithm,
+                         const blink::WebCryptoKey& key,
+                         const CryptoData& data,
+                         std::vector<uint8>* buffer) const OVERRIDE {
+    return AesCbcEncryptDecrypt(ENCRYPT, algorithm, key, data, buffer);
+  }
+
+  virtual Status Decrypt(const blink::WebCryptoAlgorithm& algorithm,
+                         const blink::WebCryptoKey& key,
+                         const CryptoData& data,
+                         std::vector<uint8>* buffer) const OVERRIDE {
+    return AesCbcEncryptDecrypt(DECRYPT, algorithm, key, data, buffer);
+  }
+};
+
+}  // namespace
+
+AlgorithmImplementation* CreatePlatformAesCbcImplementation() {
+  return new AesCbcImplementation;
+}
+
+}  // namespace webcrypto
+
+}  // namespace content