net/quic/crypto/aead_base_decrypter_nss.cc

   1 // Copyright (c) 2013 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "net/quic/crypto/aead_base_decrypter.h"
   6
   7 #include <pk11pub.h>
   8
   9 #include "base/memory/scoped_ptr.h"
  10 #include "crypto/scoped_nss_types.h"
  11
  12 using base::StringPiece;
  13
  14 namespace net {
  15
  16 AeadBaseDecrypter::AeadBaseDecrypter(CK_MECHANISM_TYPE aead_mechanism,
  17                                      PK11_DecryptFunction pk11_decrypt,
  18                                      size_t key_size,
  19                                      size_t auth_tag_size,
  20                                      size_t nonce_prefix_size)
  21     : aead_mechanism_(aead_mechanism),
  22       pk11_decrypt_(pk11_decrypt),
  23       key_size_(key_size),
  24       auth_tag_size_(auth_tag_size),
  25       nonce_prefix_size_(nonce_prefix_size) {
  26   DCHECK_LE(key_size_, sizeof(key_));
  27   DCHECK_LE(nonce_prefix_size_, sizeof(nonce_prefix_));
  28 }
  29
  30 AeadBaseDecrypter::~AeadBaseDecrypter() {}
  31
  32 bool AeadBaseDecrypter::SetKey(StringPiece key) {
  33   DCHECK_EQ(key.size(), key_size_);
  34   if (key.size() != key_size_) {
  35     return false;
  36   }
  37   memcpy(key_, key.data(), key.size());
  38   return true;
  39 }
  40
  41 bool AeadBaseDecrypter::SetNoncePrefix(StringPiece nonce_prefix) {
  42   DCHECK_EQ(nonce_prefix.size(), nonce_prefix_size_);
  43   if (nonce_prefix.size() != nonce_prefix_size_) {
  44     return false;
  45   }
  46   memcpy(nonce_prefix_, nonce_prefix.data(), nonce_prefix.size());
  47   return true;
  48 }
  49
  50 bool AeadBaseDecrypter::Decrypt(StringPiece nonce,
  51                                 const StringPiece& associated_data,
  52                                 const StringPiece& ciphertext,
  53                                 uint8* output,
  54                                 size_t* output_length,
  55                                 size_t max_output_length) {
  56   if (ciphertext.length() < auth_tag_size_ ||
  57       nonce.size() != nonce_prefix_size_ + sizeof(QuicPacketSequenceNumber)) {
  58     return false;
  59   }
  60   // NSS 3.14.x incorrectly requires an output buffer at least as long as
  61   // the ciphertext (NSS bug
  62   // https://bugzilla.mozilla.org/show_bug.cgi?id= 853674). Fortunately
  63   // QuicDecrypter::Decrypt() specifies that |output| must be as long as
  64   // |ciphertext| on entry.
  65   size_t plaintext_size = ciphertext.length() - auth_tag_size_;
  66
  67   // Import key_ into NSS.
  68   SECItem key_item;
  69   key_item.type = siBuffer;
  70   key_item.data = key_;
  71   key_item.len = key_size_;
  72   PK11SlotInfo* slot = PK11_GetInternalSlot();
  73
  74   // TODO(wtc): For an AES-GCM key, the correct value for |key_mechanism| is
  75   // CKM_AES_GCM, but because of NSS bug
  76   // https://bugzilla.mozilla.org/show_bug.cgi?id=853285, use CKM_AES_ECB as a
  77   // workaround. Remove this when we require NSS 3.15.
  78   CK_MECHANISM_TYPE key_mechanism = aead_mechanism_;
  79   if (key_mechanism == CKM_AES_GCM) {
  80     key_mechanism = CKM_AES_ECB;
  81   }
  82
  83   // The exact value of the |origin| argument doesn't matter to NSS as long as
  84   // it's not PK11_OriginFortezzaHack, so pass PK11_OriginUnwrap as a
  85   // placeholder.
  86   crypto::ScopedPK11SymKey aead_key(PK11_ImportSymKey(
  87       slot, key_mechanism, PK11_OriginUnwrap, CKA_DECRYPT, &key_item, nullptr));
  88   PK11_FreeSlot(slot);
  89   slot = nullptr;
  90   if (!aead_key) {
  91     DVLOG(1) << "PK11_ImportSymKey failed";
  92     return false;
  93   }
  94
  95   AeadParams aead_params = {0};
  96   FillAeadParams(nonce, associated_data, auth_tag_size_, &aead_params);
  97
  98   SECItem param;
  99   param.type = siBuffer;
 100   param.data = reinterpret_cast<unsigned char*>(&aead_params.data);
 101   param.len = aead_params.len;
 102
 103   unsigned int output_len;
 104   if (pk11_decrypt_(aead_key.get(), aead_mechanism_, &param, output,
 105                     &output_len, max_output_length,
 106                     reinterpret_cast<const unsigned char*>(ciphertext.data()),
 107                     ciphertext.length()) != SECSuccess) {
 108     return false;
 109   }
 110
 111   if (output_len != plaintext_size) {
 112     DVLOG(1) << "Wrong output length";
 113     return false;
 114   }
 115   *output_length = output_len;
 116   return true;
 117 }
 118
 119 bool AeadBaseDecrypter::DecryptPacket(QuicPacketSequenceNumber sequence_number,
 120                                       const StringPiece& associated_data,
 121                                       const StringPiece& ciphertext,
 122                                       char* output,
 123                                       size_t* output_length,
 124                                       size_t max_output_length) {
 125   if (ciphertext.length() < auth_tag_size_) {
 126     return false;
 127   }
 128
 129   uint8 nonce[sizeof(nonce_prefix_) + sizeof(sequence_number)];
 130   const size_t nonce_size = nonce_prefix_size_ + sizeof(sequence_number);
 131   DCHECK_LE(nonce_size, sizeof(nonce));
 132   memcpy(nonce, nonce_prefix_, nonce_prefix_size_);
 133   memcpy(nonce + nonce_prefix_size_, &sequence_number, sizeof(sequence_number));
 134   return Decrypt(StringPiece(reinterpret_cast<char*>(nonce), nonce_size),
 135                  associated_data, ciphertext, reinterpret_cast<uint8*>(output),
 136                  output_length, max_output_length);
 137 }
 138
 139 StringPiece AeadBaseDecrypter::GetKey() const {
 140   return StringPiece(reinterpret_cast<const char*>(key_), key_size_);
 141 }
 142
 143 StringPiece AeadBaseDecrypter::GetNoncePrefix() const {
 144   if (nonce_prefix_size_ == 0) {
 145     return StringPiece();
 146   }
 147   return StringPiece(reinterpret_cast<const char*>(nonce_prefix_),
 148                      nonce_prefix_size_);
 149 }
 150
 151 }  // namespace net