components/nacl/loader/nacl_validation_query.cc

   1 // Copyright 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 "components/nacl/loader/nacl_validation_query.h"
   6
   7 #include "base/logging.h"
   8 #include "components/nacl/loader/nacl_validation_db.h"
   9 #include "crypto/nss_util.h"
  10 #include "native_client/src/include/portability.h"
  11 #include "native_client/src/trusted/validator/nacl_file_info.h"
  12 #include "native_client/src/trusted/validator/validation_cache.h"
  13
  14 NaClValidationQueryContext::NaClValidationQueryContext(
  15     NaClValidationDB* db,
  16     const std::string& profile_key,
  17     const std::string& nacl_version)
  18     : db_(db),
  19       profile_key_(profile_key),
  20       nacl_version_(nacl_version) {
  21
  22   // Sanity checks.
  23   CHECK(profile_key.length() >= 8);
  24   CHECK(nacl_version.length() >= 4);
  25 }
  26
  27 NaClValidationQuery* NaClValidationQueryContext::CreateQuery() {
  28   NaClValidationQuery* query = new NaClValidationQuery(db_, profile_key_);
  29   // Changing the version effectively invalidates existing hashes.
  30   query->AddData(nacl_version_);
  31   return query;
  32 }
  33
  34 bool NaClValidationQueryContext::ResolveFileToken(
  35     struct NaClFileToken* file_token,
  36     int32* fd,
  37     std::string* path) {
  38   return db_->ResolveFileToken(file_token, fd, path);
  39 }
  40
  41 NaClValidationQuery::NaClValidationQuery(NaClValidationDB* db,
  42                                          const std::string& profile_key)
  43     : state_(READY),
  44       hasher_(crypto::HMAC::SHA256),
  45       db_(db),
  46       buffer_length_(0) {
  47   // Without this line on Linux, HMAC::Init will instantiate a singleton that
  48   // in turn attempts to open a file.  Disabling this behavior avoids a ~70 ms
  49   // stall the first time HMAC is used.
  50   // This function is also called in nacl_helper_linux.cc, but nacl_helper may
  51   // not be used in all cases.
  52   // TODO(ncbray) remove when nacl_helper becomes the only code path.
  53   // http://code.google.com/p/chromium/issues/detail?id=118263
  54 #if defined(USE_NSS)
  55   crypto::ForceNSSNoDBInit();
  56 #endif
  57   CHECK(hasher_.Init(profile_key));
  58 }
  59
  60 void NaClValidationQuery::AddData(const char* data, size_t length) {
  61   CHECK(state_ == READY);
  62   CHECK(buffer_length_ <= sizeof(buffer_));
  63   // Chrome's HMAC class doesn't support incremental signing.  Work around
  64   // this by using a (small) temporary buffer to accumulate data.
  65   // Check if there is space in the buffer.
  66   if (buffer_length_ + kDigestLength > sizeof(buffer_)) {
  67     // Hash the buffer to make space.
  68     CompressBuffer();
  69   }
  70   // Hash the input data into the buffer.  Assumes that sizeof(buffer_) >=
  71   // kDigestLength * 2 (the buffer can store at least two digests.)
  72   CHECK(hasher_.Sign(base::StringPiece(data, length),
  73                      reinterpret_cast<unsigned char*>(buffer_ + buffer_length_),
  74                      kDigestLength));
  75   buffer_length_ += kDigestLength;
  76 }
  77
  78 void NaClValidationQuery::AddData(const unsigned char* data, size_t length) {
  79   AddData(reinterpret_cast<const char*>(data), length);
  80 }
  81
  82 void NaClValidationQuery::AddData(const base::StringPiece& data) {
  83   AddData(data.data(), data.length());
  84 }
  85
  86 int NaClValidationQuery::QueryKnownToValidate() {
  87   CHECK(state_ == READY);
  88   // It is suspicious if we have less than a digest's worth of data.
  89   CHECK(buffer_length_ >= kDigestLength);
  90   CHECK(buffer_length_ <= sizeof(buffer_));
  91   state_ = GET_CALLED;
  92   // Ensure the buffer contains only one digest worth of data.
  93   CompressBuffer();
  94   return db_->QueryKnownToValidate(std::string(buffer_, buffer_length_));
  95 }
  96
  97 void NaClValidationQuery::SetKnownToValidate() {
  98   CHECK(state_ == GET_CALLED);
  99   CHECK(buffer_length_ == kDigestLength);
 100   state_ = SET_CALLED;
 101   db_->SetKnownToValidate(std::string(buffer_, buffer_length_));
 102 }
 103
 104 // Reduce the size of the data in the buffer by hashing it and writing it back
 105 // to the buffer.
 106 void NaClValidationQuery::CompressBuffer() {
 107   // Calculate the digest into a temp buffer.  It is likely safe to calculate it
 108   // directly back into the buffer, but this is an "accidental" semantic we're
 109   // avoiding depending on.
 110   unsigned char temp[kDigestLength];
 111   CHECK(hasher_.Sign(base::StringPiece(buffer_, buffer_length_), temp,
 112                      kDigestLength));
 113   memcpy(buffer_, temp, kDigestLength);
 114   buffer_length_ = kDigestLength;
 115 }
 116
 117 // OO wrappers
 118
 119 static void* CreateQuery(void* handle) {
 120   return static_cast<NaClValidationQueryContext*>(handle)->CreateQuery();
 121 }
 122
 123 static void AddData(void* query, const uint8* data, size_t length) {
 124   static_cast<NaClValidationQuery*>(query)->AddData(data, length);
 125 }
 126
 127 static int QueryKnownToValidate(void* query) {
 128   return static_cast<NaClValidationQuery*>(query)->QueryKnownToValidate();
 129 }
 130
 131 static void SetKnownToValidate(void* query) {
 132   static_cast<NaClValidationQuery*>(query)->SetKnownToValidate();
 133 }
 134
 135 static void DestroyQuery(void* query) {
 136   delete static_cast<NaClValidationQuery*>(query);
 137 }
 138
 139 static int ResolveFileToken(void* handle, struct NaClFileToken* file_token,
 140                             int32* fd, char** file_path,
 141                             uint32* file_path_length) {
 142   std::string path;
 143   *file_path = NULL;
 144   *file_path_length = 0;
 145   bool ok = static_cast<NaClValidationQueryContext*>(handle)->
 146       ResolveFileToken(file_token, fd, &path);
 147   if (ok) {
 148     *file_path = static_cast<char*>(malloc(path.length() + 1));
 149     CHECK(*file_path);
 150     memcpy(*file_path, path.data(), path.length());
 151     (*file_path)[path.length()] = 0;
 152     *file_path_length = static_cast<uint32>(path.length());
 153   }
 154   return ok;
 155 }
 156
 157 struct NaClValidationCache* CreateValidationCache(
 158     NaClValidationDB* db, const std::string& profile_key,
 159     const std::string& nacl_version) {
 160   NaClValidationCache* cache =
 161       static_cast<NaClValidationCache*>(malloc(sizeof(NaClValidationCache)));
 162   // Make sure any fields introduced in a cross-repo change are zeroed.
 163   memset(cache, 0, sizeof(*cache));
 164   cache->handle = new NaClValidationQueryContext(db, profile_key, nacl_version);
 165   cache->CreateQuery = CreateQuery;
 166   cache->AddData = AddData;
 167   cache->QueryKnownToValidate = QueryKnownToValidate;
 168   cache->SetKnownToValidate = SetKnownToValidate;
 169   cache->DestroyQuery = DestroyQuery;
 170   cache->ResolveFileToken = ResolveFileToken;
 171   return cache;
 172 }