1  // Copyright (c) 2009-2010 Satoshi Nakamoto
 2  // Copyright (c) 2009-2021 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      template <typename U>
50      friend bool operator!=(const secure_allocator&, const secure_allocator<U>&) noexcept
51      {
52          return false;
53      }
54  };
55  
56  // This is exactly like std::string, but with a custom allocator.
57  // TODO: Consider finding a way to make incoming RPC request.params[i] mlock()ed as well
58  typedef std::basic_string<char, std::char_traits<char>, secure_allocator<char> > SecureString;
59  
60  template<typename T>
61  struct SecureUniqueDeleter {
62      void operator()(T* t) noexcept {
63          secure_allocator<T>().deallocate(t, 1);
64      }
65  };
66  
67  template<typename T>
68  using secure_unique_ptr = std::unique_ptr<T, SecureUniqueDeleter<T>>;
69  
70  template<typename T, typename... Args>
71  secure_unique_ptr<T> make_secure_unique(Args&&... as)
72  {
73      T* p = secure_allocator<T>().allocate(1);
74  
75      // initialize in place, and return as secure_unique_ptr
76      try {
77          return secure_unique_ptr<T>(new (p) T(std::forward(as)...));
78      } catch (...) {
79          secure_allocator<T>().deallocate(p, 1);
80          throw;
81      }
82  }
83  
84  #endif // BITCOIN_SUPPORT_ALLOCATORS_SECURE_H