extensions/browser/content_hash_reader.cc

   1 // Copyright 2014 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 "extensions/browser/content_hash_reader.h"
   6
   7 #include "base/base64.h"
   8 #include "base/file_util.h"
   9 #include "base/json/json_reader.h"
  10 #include "base/metrics/histogram.h"
  11 #include "base/strings/string_util.h"
  12 #include "base/timer/elapsed_timer.h"
  13 #include "base/values.h"
  14 #include "crypto/sha2.h"
  15 #include "extensions/browser/computed_hashes.h"
  16 #include "extensions/browser/content_hash_tree.h"
  17 #include "extensions/browser/verified_contents.h"
  18 #include "extensions/common/extension.h"
  19 #include "extensions/common/file_util.h"
  20
  21 using base::DictionaryValue;
  22 using base::ListValue;
  23 using base::Value;
  24
  25 namespace extensions {
  26
  27 ContentHashReader::ContentHashReader(const std::string& extension_id,
  28                                      const base::Version& extension_version,
  29                                      const base::FilePath& extension_root,
  30                                      const base::FilePath& relative_path,
  31                                      const ContentVerifierKey& key)
  32     : extension_id_(extension_id),
  33       extension_version_(extension_version.GetString()),
  34       extension_root_(extension_root),
  35       relative_path_(relative_path),
  36       key_(key),
  37       status_(NOT_INITIALIZED),
  38       have_verified_contents_(false),
  39       have_computed_hashes_(false),
  40       block_size_(0) {
  41 }
  42
  43 ContentHashReader::~ContentHashReader() {
  44 }
  45
  46 bool ContentHashReader::Init() {
  47   base::ElapsedTimer timer;
  48   DCHECK_EQ(status_, NOT_INITIALIZED);
  49   status_ = FAILURE;
  50   base::FilePath verified_contents_path =
  51       file_util::GetVerifiedContentsPath(extension_root_);
  52
  53   if (!base::PathExists(verified_contents_path))
  54     return false;
  55
  56   verified_contents_.reset(new VerifiedContents(key_.data, key_.size));
  57   if (!verified_contents_->InitFrom(verified_contents_path, false) ||
  58       !verified_contents_->valid_signature() ||
  59       !verified_contents_->version().Equals(extension_version_) ||
  60       verified_contents_->extension_id() != extension_id_)
  61     return false;
  62
  63   have_verified_contents_ = true;
  64
  65   base::FilePath computed_hashes_path =
  66       file_util::GetComputedHashesPath(extension_root_);
  67   if (!base::PathExists(computed_hashes_path))
  68     return false;
  69
  70   ComputedHashes::Reader reader;
  71   if (!reader.InitFromFile(computed_hashes_path))
  72     return false;
  73
  74   have_computed_hashes_ = true;
  75
  76   if (!reader.GetHashes(relative_path_, &block_size_, &hashes_) ||
  77       block_size_ % crypto::kSHA256Length != 0)
  78     return false;
  79
  80   const std::string* expected_root =
  81       verified_contents_->GetTreeHashRoot(relative_path_);
  82   if (!expected_root)
  83     return false;
  84
  85   std::string root =
  86       ComputeTreeHashRoot(hashes_, block_size_ / crypto::kSHA256Length);
  87   if (*expected_root != root)
  88     return false;
  89
  90   status_ = SUCCESS;
  91   UMA_HISTOGRAM_TIMES("ExtensionContentHashReader.InitLatency",
  92                       timer.Elapsed());
  93   return true;
  94 }
  95
  96 int ContentHashReader::block_count() const {
  97   DCHECK(status_ != NOT_INITIALIZED);
  98   return hashes_.size();
  99 }
 100
 101 int ContentHashReader::block_size() const {
 102   DCHECK(status_ != NOT_INITIALIZED);
 103   return block_size_;
 104 }
 105
 106 bool ContentHashReader::GetHashForBlock(int block_index,
 107                                         const std::string** result) const {
 108   if (status_ != SUCCESS)
 109     return false;
 110   DCHECK(block_index >= 0);
 111
 112   if (static_cast<unsigned>(block_index) >= hashes_.size())
 113     return false;
 114   *result = &hashes_[block_index];
 115
 116   return true;
 117 }
 118
 119 }  // namespace extensions