net/ssl/ssl_platform_key_win.cc

// Copyright 2015 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifdef UNSAFE_BUFFERS_BUILD
// TODO(crbug.com/40284755): Remove this and spanify to fix the errors.
#pragma allow_unsafe_buffers
#endif

#include "net/ssl/ssl_platform_key_win.h"

#include <memory>
#include <string>
#include <utility>
#include <vector>

#include "base/logging.h"
#include "base/ranges/algorithm.h"
#include "base/strings/utf_string_conversions.h"
#include "crypto/openssl_util.h"
#include "crypto/scoped_capi_types.h"
#include "crypto/scoped_cng_types.h"
#include "crypto/unexportable_key_win.h"
#include "net/base/net_errors.h"
#include "net/cert/x509_certificate.h"
#include "net/ssl/ssl_platform_key_util.h"
#include "net/ssl/ssl_private_key.h"
#include "net/ssl/threaded_ssl_private_key.h"
#include "third_party/boringssl/src/include/openssl/bn.h"
#include "third_party/boringssl/src/include/openssl/ecdsa.h"
#include "third_party/boringssl/src/include/openssl/evp.h"
#include "third_party/boringssl/src/include/openssl/ssl.h"

namespace net {

namespace {

bool ProbeSHA256(ThreadedSSLPrivateKey::Delegate* delegate) {
  // This input is chosen to avoid colliding with other signing inputs used in
  // TLS 1.2 or TLS 1.3. We use the construct in RFC 8446, section 4.4.3, but
  // change the context string. The context string ensures we don't collide with
  // TLS 1.3 and any future version. The 0x20 (space) prefix ensures we don't
  // collide with TLS 1.2 ServerKeyExchange or CertificateVerify.
  static const uint8_t kSHA256ProbeInput[] = {
      0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20,
      0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20,
      0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20,
      0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20,
      0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20,
      0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 'C',  'h',
      'r',  'o',  'm',  'i',  'u',  'm',  ',',  ' ',  'S',  'H',  'A',
      '2',  ' ',  'P',  'r',  'o',  'b',  'e',  0x00,
  };
  std::vector<uint8_t> signature;
  return delegate->Sign(SSL_SIGN_RSA_PKCS1_SHA256, kSHA256ProbeInput,
                        &signature) == OK;
}

std::string GetCAPIProviderName(HCRYPTPROV provider) {
  DWORD name_len;
  if (!CryptGetProvParam(provider, PP_NAME, nullptr, &name_len, 0)) {
    return "(error getting name)";
  }
  std::vector<BYTE> name(name_len);
  if (!CryptGetProvParam(provider, PP_NAME, name.data(), &name_len, 0)) {
    return "(error getting name)";
  }
  // Per Microsoft's documentation, PP_NAME is NUL-terminated. However,
  // smartcard drivers are notoriously buggy, so check this.
  auto nul = base::ranges::find(name, 0);
  if (nul != name.end()) {
    name_len = nul - name.begin();
  }
  return std::string(reinterpret_cast<const char*>(name.data()), name_len);
}

class SSLPlatformKeyCAPI : public ThreadedSSLPrivateKey::Delegate {
 public:
  // Takes ownership of |provider|.
  SSLPlatformKeyCAPI(crypto::ScopedHCRYPTPROV provider, DWORD key_spec)
      : provider_name_(GetCAPIProviderName(provider.get())),
        provider_(std::move(provider)),
        key_spec_(key_spec) {
    // Check for SHA-256 support. The CAPI service provider may only be able to
    // sign pre-TLS-1.2 and SHA-1 hashes. If SHA-256 doesn't work, prioritize
    // SHA-1 as a workaround. See https://crbug.com/278370.
    prefer_sha1_ = !ProbeSHA256(this);
  }

  SSLPlatformKeyCAPI(const SSLPlatformKeyCAPI&) = delete;
  SSLPlatformKeyCAPI& operator=(const SSLPlatformKeyCAPI&) = delete;

  ~SSLPlatformKeyCAPI() override = default;

  std::string GetProviderName() override { return "CAPI: " + provider_name_; }

  std::vector<uint16_t> GetAlgorithmPreferences() override {
    if (prefer_sha1_) {
      return {SSL_SIGN_RSA_PKCS1_SHA1, SSL_SIGN_RSA_PKCS1_SHA256,
              SSL_SIGN_RSA_PKCS1_SHA384, SSL_SIGN_RSA_PKCS1_SHA512};
    }
    return {SSL_SIGN_RSA_PKCS1_SHA256, SSL_SIGN_RSA_PKCS1_SHA384,
            SSL_SIGN_RSA_PKCS1_SHA512, SSL_SIGN_RSA_PKCS1_SHA1};
  }

  Error Sign(uint16_t algorithm,
             base::span<const uint8_t> input,
             std::vector<uint8_t>* signature) override {
    const EVP_MD* md = SSL_get_signature_algorithm_digest(algorithm);
    uint8_t digest[EVP_MAX_MD_SIZE];
    unsigned digest_len;
    if (!md || !EVP_Digest(input.data(), input.size(), digest, &digest_len, md,
                           nullptr)) {
      return ERR_SSL_CLIENT_AUTH_SIGNATURE_FAILED;
    }

    ALG_ID hash_alg;
    switch (EVP_MD_type(md)) {
      case NID_md5_sha1:
        hash_alg = CALG_SSL3_SHAMD5;
        break;
      case NID_sha1:
        hash_alg = CALG_SHA1;
        break;
      case NID_sha256:
        hash_alg = CALG_SHA_256;
        break;
      case NID_sha384:
        hash_alg = CALG_SHA_384;
        break;
      case NID_sha512:
        hash_alg = CALG_SHA_512;
        break;
      default:
        NOTREACHED();
    }

    crypto::ScopedHCRYPTHASH hash_handle;
    if (!CryptCreateHash(
            provider_.get(), hash_alg, 0, 0,
            crypto::ScopedHCRYPTHASH::Receiver(hash_handle).get())) {
      PLOG(ERROR) << "CreateCreateHash failed";
      return ERR_SSL_CLIENT_AUTH_SIGNATURE_FAILED;
    }
    DWORD hash_len;
    DWORD arg_len = sizeof(hash_len);
    if (!CryptGetHashParam(hash_handle.get(), HP_HASHSIZE,
                           reinterpret_cast<BYTE*>(&hash_len), &arg_len, 0)) {
      PLOG(ERROR) << "CryptGetHashParam HP_HASHSIZE failed";
      return ERR_SSL_CLIENT_AUTH_SIGNATURE_FAILED;
    }
    if (hash_len != digest_len)
      return ERR_SSL_CLIENT_AUTH_SIGNATURE_FAILED;
    if (!CryptSetHashParam(hash_handle.get(), HP_HASHVAL,
                           const_cast<BYTE*>(digest), 0)) {
      PLOG(ERROR) << "CryptSetHashParam HP_HASHVAL failed";
      return ERR_SSL_CLIENT_AUTH_SIGNATURE_FAILED;
    }
    DWORD signature_len = 0;
    if (!CryptSignHash(hash_handle.get(), key_spec_, nullptr, 0, nullptr,
                       &signature_len)) {
      PLOG(ERROR) << "CryptSignHash failed";
      return ERR_SSL_CLIENT_AUTH_SIGNATURE_FAILED;
    }
    signature->resize(signature_len);
    if (!CryptSignHash(hash_handle.get(), key_spec_, nullptr, 0,
                       signature->data(), &signature_len)) {
      PLOG(ERROR) << "CryptSignHash failed";
      return ERR_SSL_CLIENT_AUTH_SIGNATURE_FAILED;
    }
    signature->resize(signature_len);

    // CryptoAPI signs in little-endian, so reverse it.
    std::reverse(signature->begin(), signature->end());
    return OK;
  }

 private:
  std::string provider_name_;
  crypto::ScopedHCRYPTPROV provider_;
  DWORD key_spec_;
  bool prefer_sha1_ = false;
};

std::wstring GetCNGProviderName(NCRYPT_KEY_HANDLE key) {
  crypto::ScopedNCryptProvider prov;
  DWORD prov_len = 0;
  SECURITY_STATUS status = NCryptGetProperty(
      key, NCRYPT_PROVIDER_HANDLE_PROPERTY,
      reinterpret_cast<BYTE*>(
          crypto::ScopedNCryptProvider::Receiver(prov).get()),
      sizeof(NCRYPT_PROV_HANDLE), &prov_len, NCRYPT_SILENT_FLAG);
  if (FAILED(status)) {
    return L"(error getting provider)";
  }
  DCHECK_EQ(sizeof(NCRYPT_PROV_HANDLE), prov_len);

  // NCRYPT_NAME_PROPERTY is a NUL-terminated Unicode string, which means an
  // array of wchar_t, however NCryptGetProperty works in bytes, so lengths must
  // be converted.
  DWORD name_len = 0;
  status = NCryptGetProperty(prov.get(), NCRYPT_NAME_PROPERTY, nullptr, 0,
                             &name_len, NCRYPT_SILENT_FLAG);
  if (FAILED(status) || name_len % sizeof(wchar_t) != 0) {
    return L"(error getting provider name)";
  }
  std::vector<wchar_t> name;
  name.reserve(name_len / sizeof(wchar_t));
  status = NCryptGetProperty(
      prov.get(), NCRYPT_NAME_PROPERTY, reinterpret_cast<BYTE*>(name.data()),
      name.size() * sizeof(wchar_t), &name_len, NCRYPT_SILENT_FLAG);
  if (FAILED(status)) {
    return L"(error getting provider name)";
  }
  name.resize(name_len / sizeof(wchar_t));

  // Per Microsoft's documentation, the name is NUL-terminated. However,
  // smartcard drivers are notoriously buggy, so check this.
  auto nul = base::ranges::find(name, 0);
  if (nul != name.end()) {
    name.erase(nul, name.end());
  }
  return std::wstring(name.begin(), name.end());
}

class SSLPlatformKeyCNG : public ThreadedSSLPrivateKey::Delegate {
 public:
  // Takes ownership of |key|.
  SSLPlatformKeyCNG(crypto::ScopedNCryptKey key, int type, size_t max_length)
      : provider_name_(GetCNGProviderName(key.get())),
        key_(std::move(key)),
        type_(type),
        max_length_(max_length) {
    // If this is a 1024-bit RSA key or below, check for SHA-256 support. Older
    // Estonian ID cards can only sign SHA-1 hashes. If SHA-256 does not work,
    // prioritize SHA-1 as a workaround. See https://crbug.com/278370.
    prefer_sha1_ =
        type_ == EVP_PKEY_RSA && max_length_ <= 1024 / 8 && !ProbeSHA256(this);
  }

  SSLPlatformKeyCNG(const SSLPlatformKeyCNG&) = delete;
  SSLPlatformKeyCNG& operator=(const SSLPlatformKeyCNG&) = delete;

  std::string GetProviderName() override {
    return "CNG: " + base::WideToUTF8(provider_name_);
  }

  std::vector<uint16_t> GetAlgorithmPreferences() override {
    // Per TLS 1.3 (RFC 8446), the RSA-PSS code points in TLS correspond to
    // RSA-PSS with salt length equal to the digest length. TPM 2.0's
    // TPM_ALG_RSAPSS algorithm, however, uses the maximum possible salt length.
    // The TPM provider will fail signing requests for other salt lengths and
    // thus cannot generate TLS-compatible PSS signatures.
    //
    // However, as of TPM revision 1.16, TPMs which follow FIPS 186-4 will
    // instead interpret TPM_ALG_RSAPSS using salt length equal to the digest
    // length. Those TPMs can generate TLS-compatible PSS signatures. As a
    // result, if this is a TPM-based key, we only report PSS as supported if
    // the salt length will match the digest length.
    bool supports_pss = true;
    if (provider_name_ == MS_PLATFORM_KEY_STORAGE_PROVIDER) {
      DWORD salt_size = 0;
      DWORD size_of_salt_size = sizeof(salt_size);
      HRESULT status =
          NCryptGetProperty(key_.get(), NCRYPT_PCP_PSS_SALT_SIZE_PROPERTY,
                            reinterpret_cast<PBYTE>(&salt_size),
                            size_of_salt_size, &size_of_salt_size, 0);
      if (FAILED(status) || salt_size != NCRYPT_TPM_PSS_SALT_SIZE_HASHSIZE) {
        supports_pss = false;
      }
    }
    if (prefer_sha1_) {
      std::vector<uint16_t> ret = {
          SSL_SIGN_RSA_PKCS1_SHA1,
          SSL_SIGN_RSA_PKCS1_SHA256,
          SSL_SIGN_RSA_PKCS1_SHA384,
          SSL_SIGN_RSA_PKCS1_SHA512,
      };
      if (supports_pss) {
        ret.push_back(SSL_SIGN_RSA_PSS_SHA256);
        ret.push_back(SSL_SIGN_RSA_PSS_SHA384);
        ret.push_back(SSL_SIGN_RSA_PSS_SHA512);
      }
      return ret;
    }
    return SSLPrivateKey::DefaultAlgorithmPreferences(type_, supports_pss);
  }

  Error Sign(uint16_t algorithm,
             base::span<const uint8_t> input,
             std::vector<uint8_t>* signature) override {
    crypto::OpenSSLErrStackTracer tracer(FROM_HERE);

    const EVP_MD* md = SSL_get_signature_algorithm_digest(algorithm);
    uint8_t digest[EVP_MAX_MD_SIZE];
    unsigned digest_len;
    if (!md || !EVP_Digest(input.data(), input.size(), digest, &digest_len, md,
                           nullptr)) {
      return ERR_SSL_CLIENT_AUTH_SIGNATURE_FAILED;
    }

    BCRYPT_PKCS1_PADDING_INFO pkcs1_padding_info = {nullptr};
    BCRYPT_PSS_PADDING_INFO pss_padding_info = {nullptr};
    void* padding_info = nullptr;
    DWORD flags = 0;
    if (SSL_get_signature_algorithm_key_type(algorithm) == EVP_PKEY_RSA) {
      const WCHAR* hash_alg;
      switch (EVP_MD_type(md)) {
        case NID_md5_sha1:
          hash_alg = nullptr;
          break;
        case NID_sha1:
          hash_alg = BCRYPT_SHA1_ALGORITHM;
          break;
        case NID_sha256:
          hash_alg = BCRYPT_SHA256_ALGORITHM;
          break;
        case NID_sha384:
          hash_alg = BCRYPT_SHA384_ALGORITHM;
          break;
        case NID_sha512:
          hash_alg = BCRYPT_SHA512_ALGORITHM;
          break;
        default:
          NOTREACHED();
      }
      if (SSL_is_signature_algorithm_rsa_pss(algorithm)) {
        pss_padding_info.pszAlgId = hash_alg;
        pss_padding_info.cbSalt = EVP_MD_size(md);
        padding_info = &pss_padding_info;
        flags |= BCRYPT_PAD_PSS;
      } else {
        pkcs1_padding_info.pszAlgId = hash_alg;
        padding_info = &pkcs1_padding_info;
        flags |= BCRYPT_PAD_PKCS1;
      }
    }

    DWORD signature_len;
    SECURITY_STATUS status =
        NCryptSignHash(key_.get(), padding_info, const_cast<BYTE*>(digest),
                       digest_len, nullptr, 0, &signature_len, flags);
    if (FAILED(status)) {
      LOG(ERROR) << "NCryptSignHash failed: " << status;
      return ERR_SSL_CLIENT_AUTH_SIGNATURE_FAILED;
    }
    signature->resize(signature_len);
    status = NCryptSignHash(key_.get(), padding_info, const_cast<BYTE*>(digest),
                            digest_len, signature->data(), signature_len,
                            &signature_len, flags);
    if (FAILED(status)) {
      LOG(ERROR) << "NCryptSignHash failed: " << status;
      return ERR_SSL_CLIENT_AUTH_SIGNATURE_FAILED;
    }
    signature->resize(signature_len);

    // CNG emits raw ECDSA signatures, but BoringSSL expects a DER-encoded
    // ECDSA-Sig-Value.
    if (type_ == EVP_PKEY_EC) {
      if (signature->size() % 2 != 0) {
        LOG(ERROR) << "Bad signature length";
        return ERR_SSL_CLIENT_AUTH_SIGNATURE_FAILED;
      }
      size_t order_len = signature->size() / 2;

      // Convert the RAW ECDSA signature to a DER-encoded ECDSA-Sig-Value.
      bssl::UniquePtr<ECDSA_SIG> sig(ECDSA_SIG_new());
      if (!sig || !BN_bin2bn(signature->data(), order_len, sig->r) ||
          !BN_bin2bn(signature->data() + order_len, order_len, sig->s)) {
        return ERR_SSL_CLIENT_AUTH_SIGNATURE_FAILED;
      }

      int len = i2d_ECDSA_SIG(sig.get(), nullptr);
      if (len <= 0)
        return ERR_SSL_CLIENT_AUTH_SIGNATURE_FAILED;
      signature->resize(len);
      uint8_t* ptr = signature->data();
      len = i2d_ECDSA_SIG(sig.get(), &ptr);
      if (len <= 0)
        return ERR_SSL_CLIENT_AUTH_SIGNATURE_FAILED;
      signature->resize(len);
    }

    return OK;
  }

 private:
  std::wstring provider_name_;
  crypto::ScopedNCryptKey key_;
  int type_;
  size_t max_length_;
  bool prefer_sha1_ = false;
};

}  // namespace

scoped_refptr<SSLPrivateKey> WrapCAPIPrivateKey(
    const X509Certificate* certificate,
    crypto::ScopedHCRYPTPROV prov,
    DWORD key_spec) {
  return base::MakeRefCounted<ThreadedSSLPrivateKey>(
      std::make_unique<SSLPlatformKeyCAPI>(std::move(prov), key_spec),
      GetSSLPlatformKeyTaskRunner());
}

scoped_refptr<SSLPrivateKey> WrapCNGPrivateKey(
    const X509Certificate* certificate,
    crypto::ScopedNCryptKey key) {
  // Rather than query the private key for metadata, extract the public key from
  // the certificate without using Windows APIs. CNG does not consistently work
  // depending on the system. See https://crbug.com/468345.
  int key_type;
  size_t max_length;
  if (!GetClientCertInfo(certificate, &key_type, &max_length)) {
    return nullptr;
  }

  return base::MakeRefCounted<ThreadedSSLPrivateKey>(
      std::make_unique<SSLPlatformKeyCNG>(std::move(key), key_type, max_length),
      GetSSLPlatformKeyTaskRunner());
}

scoped_refptr<SSLPrivateKey> FetchClientCertPrivateKey(
    const X509Certificate* certificate,
    PCCERT_CONTEXT cert_context) {
  HCRYPTPROV_OR_NCRYPT_KEY_HANDLE prov_or_key = 0;
  DWORD key_spec = 0;
  BOOL must_free = FALSE;
  DWORD flags = CRYPT_ACQUIRE_PREFER_NCRYPT_KEY_FLAG;

  if (!CryptAcquireCertificatePrivateKey(cert_context, flags, nullptr,
                                         &prov_or_key, &key_spec, &must_free)) {
    PLOG(WARNING) << "Could not acquire private key";
    return nullptr;
  }

  // Should never get a cached handle back - ownership must always be
  // transferred.
  CHECK_EQ(must_free, TRUE);

  if (key_spec == CERT_NCRYPT_KEY_SPEC) {
    return WrapCNGPrivateKey(certificate, crypto::ScopedNCryptKey(prov_or_key));
  } else {
    return WrapCAPIPrivateKey(certificate,
                              crypto::ScopedHCRYPTPROV(prov_or_key), key_spec);
  }
}

scoped_refptr<SSLPrivateKey> WrapUnexportableKeySlowly(
    const crypto::UnexportableSigningKey& key) {
  // Load NCRYPT_KEY_HANDLE from wrapped.
  auto wrapped = key.GetWrappedKey();
  crypto::ScopedNCryptProvider provider;
  crypto::ScopedNCryptKey key_handle;
  if (!crypto::LoadWrappedTPMKey(wrapped, provider, key_handle)) {
    return nullptr;
  }

  int key_type;
  size_t max_length;
  if (!GetPublicKeyInfo(key.GetSubjectPublicKeyInfo(), &key_type,
                        &max_length)) {
    return nullptr;
  }

  return base::MakeRefCounted<ThreadedSSLPrivateKey>(
      std::make_unique<SSLPlatformKeyCNG>(std::move(key_handle), key_type,
                                          max_length),
      GetSSLPlatformKeyTaskRunner());
}

}  // namespace net