Refactor WebCrypto code

content/child/webcrypto/nss/hmac_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 <pk11pub.h>
+#include <secerr.h>
+#include <sechash.h>
+
+#include "base/logging.h"
+#include "content/child/webcrypto/crypto_data.h"
+#include "content/child/webcrypto/jwk.h"
+#include "content/child/webcrypto/nss/key_nss.h"
+#include "content/child/webcrypto/nss/sym_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/secure_util.h"
+#include "third_party/WebKit/public/platform/WebCryptoAlgorithmParams.h"
+#include "third_party/WebKit/public/platform/WebCryptoKeyAlgorithm.h"
+
+namespace content {
+
+namespace webcrypto {
+
+namespace {
+
+const blink::WebCryptoKeyUsageMask kAllKeyUsages =
+    blink::WebCryptoKeyUsageSign | blink::WebCryptoKeyUsageVerify;
+
+bool WebCryptoHashToHMACMechanism(const blink::WebCryptoAlgorithm& algorithm,
+                                  CK_MECHANISM_TYPE* mechanism) {
+  switch (algorithm.id()) {
+    case blink::WebCryptoAlgorithmIdSha1:
+      *mechanism = CKM_SHA_1_HMAC;
+      return true;
+    case blink::WebCryptoAlgorithmIdSha256:
+      *mechanism = CKM_SHA256_HMAC;
+      return true;
+    case blink::WebCryptoAlgorithmIdSha384:
+      *mechanism = CKM_SHA384_HMAC;
+      return true;
+    case blink::WebCryptoAlgorithmIdSha512:
+      *mechanism = CKM_SHA512_HMAC;
+      return true;
+    default:
+      return false;
+  }
+}
+
+class HmacImplementation : public AlgorithmImplementation {
+ public:
+  HmacImplementation() {}
+
+  virtual Status GenerateSecretKey(const blink::WebCryptoAlgorithm& algorithm,
+                                   bool extractable,
+                                   blink::WebCryptoKeyUsageMask usage_mask,
+                                   blink::WebCryptoKey* key) const OVERRIDE {
+    const blink::WebCryptoHmacKeyGenParams* params =
+        algorithm.hmacKeyGenParams();
+
+    const blink::WebCryptoAlgorithm& hash = params->hash();
+    CK_MECHANISM_TYPE mechanism = CKM_INVALID_MECHANISM;
+    if (!WebCryptoHashToHMACMechanism(hash, &mechanism))
+      return Status::ErrorUnsupported();
+
+    unsigned int keylen_bits = 0;
+    Status status = GetHmacKeyGenLength(params, &keylen_bits);
+    if (status.IsError())
+      return status;
+
+    return GenerateSecretKeyNss(
+        blink::WebCryptoKeyAlgorithm::createHmac(hash.id(), keylen_bits),
+        extractable,
+        usage_mask,
+        keylen_bits / 8,
+        mechanism,
+        key);
+  }
+
+  virtual Status VerifyKeyUsagesBeforeImportKey(
+      blink::WebCryptoKeyFormat format,
+      blink::WebCryptoKeyUsageMask usage_mask) const OVERRIDE {
+    switch (format) {
+      case blink::WebCryptoKeyFormatRaw:
+      case blink::WebCryptoKeyFormatJwk:
+        return CheckKeyCreationUsages(kAllKeyUsages, usage_mask);
+      default:
+        return Status::ErrorUnsupportedImportKeyFormat();
+    }
+  }
+
+  virtual Status VerifyKeyUsagesBeforeGenerateKey(
+      blink::WebCryptoKeyUsageMask usage_mask) const OVERRIDE {
+    return CheckKeyCreationUsages(kAllKeyUsages, usage_mask);
+  }
+
+  virtual Status ImportKeyRaw(const CryptoData& key_data,
+                              const blink::WebCryptoAlgorithm& algorithm,
+                              bool extractable,
+                              blink::WebCryptoKeyUsageMask usage_mask,
+                              blink::WebCryptoKey* key) const OVERRIDE {
+    const blink::WebCryptoAlgorithm& hash =
+        algorithm.hmacImportParams()->hash();
+
+    CK_MECHANISM_TYPE mechanism = CKM_INVALID_MECHANISM;
+    if (!WebCryptoHashToHMACMechanism(hash, &mechanism))
+      return Status::ErrorUnsupported();
+
+    // TODO(eroman): check for overflow.
+    unsigned int keylen_bits = key_data.byte_length() * 8;
+    return ImportKeyRawNss(
+        key_data,
+        blink::WebCryptoKeyAlgorithm::createHmac(hash.id(), keylen_bits),
+        extractable,
+        usage_mask,
+        mechanism,
+        CKF_SIGN | CKF_VERIFY,
+        key);
+  }
+
+  virtual Status ImportKeyJwk(const CryptoData& key_data,
+                              const blink::WebCryptoAlgorithm& algorithm,
+                              bool extractable,
+                              blink::WebCryptoKeyUsageMask usage_mask,
+                              blink::WebCryptoKey* key) const OVERRIDE {
+    const char* algorithm_name =
+        GetJwkHmacAlgorithmName(algorithm.hmacImportParams()->hash().id());
+    if (!algorithm_name)
+      return Status::ErrorUnexpected();
+
+    std::vector<uint8> raw_data;
+    Status status = ReadSecretKeyJwk(
+        key_data, algorithm_name, extractable, usage_mask, &raw_data);
+    if (status.IsError())
+      return status;
+
+    return ImportKeyRaw(
+        CryptoData(raw_data), algorithm, extractable, usage_mask, key);
+  }
+
+  virtual Status ExportKeyRaw(const blink::WebCryptoKey& key,
+                              std::vector<uint8>* buffer) const OVERRIDE {
+    *buffer = SymKeyNss::Cast(key)->raw_key_data();
+    return Status::Success();
+  }
+
+  virtual Status ExportKeyJwk(const blink::WebCryptoKey& key,
+                              std::vector<uint8>* buffer) const OVERRIDE {
+    SymKeyNss* sym_key = SymKeyNss::Cast(key);
+    const std::vector<uint8>& raw_data = sym_key->raw_key_data();
+
+    const char* algorithm_name =
+        GetJwkHmacAlgorithmName(key.algorithm().hmacParams()->hash().id());
+    if (!algorithm_name)
+      return Status::ErrorUnexpected();
+
+    WriteSecretKeyJwk(CryptoData(raw_data),
+                      algorithm_name,
+                      key.extractable(),
+                      key.usages(),
+                      buffer);
+
+    return Status::Success();
+  }
+
+  virtual Status Sign(const blink::WebCryptoAlgorithm& algorithm,
+                      const blink::WebCryptoKey& key,
+                      const CryptoData& data,
+                      std::vector<uint8>* buffer) const OVERRIDE {
+    const blink::WebCryptoAlgorithm& hash =
+        key.algorithm().hmacParams()->hash();
+    PK11SymKey* sym_key = SymKeyNss::Cast(key)->key();
+
+    CK_MECHANISM_TYPE mechanism = CKM_INVALID_MECHANISM;
+    if (!WebCryptoHashToHMACMechanism(hash, &mechanism))
+      return Status::ErrorUnexpected();
+
+    SECItem param_item = {siBuffer, NULL, 0};
+    SECItem data_item = MakeSECItemForBuffer(data);
+    // First call is to figure out the length.
+    SECItem signature_item = {siBuffer, NULL, 0};
+
+    if (PK11_SignWithSymKey(
+            sym_key, mechanism, &param_item, &signature_item, &data_item) !=
+        SECSuccess) {
+      return Status::OperationError();
+    }
+
+    DCHECK_NE(0u, signature_item.len);
+
+    buffer->resize(signature_item.len);
+    signature_item.data = Uint8VectorStart(buffer);
+
+    if (PK11_SignWithSymKey(
+            sym_key, mechanism, &param_item, &signature_item, &data_item) !=
+        SECSuccess) {
+      return Status::OperationError();
+    }
+
+    DCHECK_EQ(buffer->size(), signature_item.len);

[Ryan Sleevi, 2014/07/17 00:06:54]

What is this DCHECK measuring? The caller of this function doesn't affect this.
It seems like you're trying ot (rightly) defend against NSS bugs, in which case,
should this be a CHECK()? Seems it'd be security relevant if the two weren't
equal.

[eroman, 2014/07/17 20:37:25]

Done, changed to CHECK().

+    return Status::Success();
+  }
+
+  virtual Status Verify(const blink::WebCryptoAlgorithm& algorithm,
+                        const blink::WebCryptoKey& key,
+                        const CryptoData& signature,
+                        const CryptoData& data,
+                        bool* signature_match) const OVERRIDE {
+    std::vector<uint8> result;
+    Status status = Sign(algorithm, key, data, &result);
+
+    if (status.IsError())
+      return status;
+
+    // Do not allow verification of truncated MACs.
+    *signature_match = result.size() == signature.byte_length() &&
+                       crypto::SecureMemEqual(Uint8VectorStart(result),
+                                              signature.bytes(),
+                                              signature.byte_length());
+
+    return Status::Success();
+  }
+};
+
+}  // namespace
+
+AlgorithmImplementation* CreatePlatformHmacImplementation() {
+  return new HmacImplementation;
+}
+
+}  // namespace webcrypto
+
+}  // namespace content