1    :  // Copyright 2011 Google Inc.
   2    :  //
   3    :  // Licensed under the Apache License, Version 2.0 (the "License");
   4    :  // you may not use this file except in compliance with the License.
   5    :  // You may obtain a copy of the License at
   6    :  //
   7    :  //     http://www.apache.org/licenses/LICENSE-2.0
   8    :  //
   9    :  // Unless required by applicable law or agreed to in writing, software
  10    :  // distributed under the License is distributed on an "AS IS" BASIS,
  11    :  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  12    :  // See the License for the specific language governing permissions and
  13    :  // limitations under the License.
  14    :  
  15    :  #include "syzygy/reorder/random_order_generator.h"
  16    :  
  17    :  #include <algorithm>
  18    :  
  19    :  #include "syzygy/core/random_number_generator.h"
  20    :  #include "syzygy/pe/pe_utils.h"
  21    :  
  22    :  namespace reorder {
  23    :  
  24    :  RandomOrderGenerator::RandomOrderGenerator(int seed)
  25    :      : Reorderer::OrderGenerator("Random Order Generator"),
  26  E :        seed_(seed) {
  27  E :  }
  28    :  
  29  E :  RandomOrderGenerator::~RandomOrderGenerator() {
  30  E :  }
  31    :  
  32    :  bool RandomOrderGenerator::OnCodeBlockEntry(const BlockGraph::Block* /*block*/,
  33    :                                              RelativeAddress /*address*/,
  34    :                                              uint32 /*process_id*/,
  35    :                                              uint32 /*thread_id*/,
  36  i :                                              const UniqueTime& /*time*/) {
  37    :    // This is a NOP.
  38  i :    return true;
  39  i :  }
  40    :  
  41    :  bool RandomOrderGenerator::CalculateReordering(const PEFile& pe_file,
  42    :                                                 const ImageLayout& image,
  43    :                                                 bool reorder_code,
  44    :                                                 bool reorder_data,
  45  E :                                                 Order* order) {
  46  E :    DCHECK(order != NULL);
  47    :  
  48  E :    for (size_t i = 0; i < image.sections.size(); ++i) {
  49  E :      const ImageLayout::SectionInfo& section = image.sections[i];
  50    :      if ((!reorder_code && section.characteristics & IMAGE_SCN_CNT_CODE) ||
  51    :          (!reorder_data &&
  52  E :              section.characteristics & pe::kReadOnlyDataCharacteristics))
  53  E :        continue;
  54    :  
  55  E :      LOG(INFO) << "Randomizing section " << i  << " (" << section.name << ").";
  56    :  
  57    :      // Prepare to iterate over all block in the section.
  58  E :      BlockGraph::AddressSpace::Range section_range(section.addr, section.size);
  59    :      AddressSpace::RangeMapConstIterPair section_blocks(
  60    :          image.blocks.GetIntersectingBlocks(
  61  E :              section_range.start(), section_range.size()));
  62    :  
  63    :      // Gather up all blocks within the section.
  64  E :      AddressSpace::RangeMapConstIter& section_it = section_blocks.first;
  65  E :      const AddressSpace::RangeMapConstIter& section_end = section_blocks.second;
  66  E :      Order::BlockList& block_list = order->section_block_lists[i];
  67  E :      for (; section_it != section_end; ++section_it) {
  68  E :        const BlockGraph::Block* block = section_it->second;
  69  E :        block_list.push_back(block);
  70  E :      }
  71    :  
  72  E :      core::RandomNumberGenerator random_number_generator(seed_ + i);
  73    :      std::random_shuffle(block_list.begin(),
  74    :                          block_list.end(),
  75  E :                          random_number_generator);
  76  E :    }
  77    :  
  78  E :    return true;
  79  E :  }
  80    :  
  81    :  }  // namespace reorder