secure.h raw

   1  // Copyright (c) 2009-2010 Satoshi Nakamoto
   2  // Copyright (c) 2009-present The Bitcoin Core developers
   3  // Distributed under the MIT software license, see the accompanying
   4  // file COPYING or http://www.opensource.org/licenses/mit-license.php.
   5  
   6  #ifndef BITCOIN_SUPPORT_ALLOCATORS_SECURE_H
   7  #define BITCOIN_SUPPORT_ALLOCATORS_SECURE_H
   8  
   9  #include <support/lockedpool.h>
  10  #include <support/cleanse.h>
  11  
  12  #include <memory>
  13  #include <string>
  14  
  15  //
  16  // Allocator that locks its contents from being paged
  17  // out of memory and clears its contents before deletion.
  18  //
  19  template <typename T>
  20  struct secure_allocator {
  21      using value_type = T;
  22  
  23      secure_allocator() = default;
  24      template <typename U>
  25      secure_allocator(const secure_allocator<U>&) noexcept {}
  26  
  27      T* allocate(std::size_t n)
  28      {
  29          T* allocation = static_cast<T*>(LockedPoolManager::Instance().alloc(sizeof(T) * n));
  30          if (!allocation) {
  31              throw std::bad_alloc();
  32          }
  33          return allocation;
  34      }
  35  
  36      void deallocate(T* p, std::size_t n)
  37      {
  38          if (p != nullptr) {
  39              memory_cleanse(p, sizeof(T) * n);
  40          }
  41          LockedPoolManager::Instance().free(p);
  42      }
  43  
  44      template <typename U>
  45      friend bool operator==(const secure_allocator&, const secure_allocator<U>&) noexcept
  46      {
  47          return true;
  48      }
  49  };
  50  
  51  // This is exactly like std::string, but with a custom allocator.
  52  // TODO: Consider finding a way to make incoming RPC request.params[i] mlock()ed as well
  53  typedef std::basic_string<char, std::char_traits<char>, secure_allocator<char> > SecureString;
  54  
  55  template<typename T>
  56  struct SecureUniqueDeleter {
  57      void operator()(T* t) noexcept {
  58          secure_allocator<T>().deallocate(t, 1);
  59      }
  60  };
  61  
  62  template<typename T>
  63  using secure_unique_ptr = std::unique_ptr<T, SecureUniqueDeleter<T>>;
  64  
  65  template<typename T, typename... Args>
  66  secure_unique_ptr<T> make_secure_unique(Args&&... as)
  67  {
  68      T* p = secure_allocator<T>().allocate(1);
  69  
  70      // initialize in place, and return as secure_unique_ptr
  71      try {
  72          return secure_unique_ptr<T>(new (p) T(std::forward<Args>(as)...));
  73      } catch (...) {
  74          secure_allocator<T>().deallocate(p, 1);
  75          throw;
  76      }
  77  }
  78  
  79  #endif // BITCOIN_SUPPORT_ALLOCATORS_SECURE_H
  80