new wipeable_string class to replace std::string passphrases

src/common/password.cpp

@@ -56,7 +56,7 @@ namespace
     return 0 != _isatty(_fileno(stdin));
   }
 
-  bool read_from_tty(std::string& pass)
+  bool read_from_tty(epee::wipeable_string& pass)
   {
     static constexpr const char BACKSPACE = 8;
 
@@ -88,8 +88,7 @@ namespace
       {
         if (!pass.empty())
         {
-          pass.back() = '\0';
-          pass.resize(pass.size() - 1);
+          pass.pop_back();
         }
       }
       else
@@ -127,7 +126,7 @@ namespace
     return ch;
   }
 
-  bool read_from_tty(std::string& aPass)
+  bool read_from_tty(epee::wipeable_string& aPass)
   {
     static constexpr const char BACKSPACE = 127;
 
@@ -148,8 +147,7 @@ namespace
       {
         if (!aPass.empty())
         {
-          aPass.back() = '\0';
-          aPass.resize(aPass.size() - 1);
+          aPass.pop_back();
         }
       }
       else
@@ -163,15 +161,7 @@ namespace
 
 #endif // end !WIN32
 
-  void clear(std::string& pass) noexcept
-  {
-    // technically, the std::string documentation says the data should not be modified,
-    // but there seems to be no way to get a non const raw pointer to the data
-    memwipe((void*)pass.data(), pass.size());
-    pass.clear();
-  }
-
-  bool read_from_tty(const bool verify, const char *message, std::string& pass1, std::string& pass2)
+  bool read_from_tty(const bool verify, const char *message, epee::wipeable_string& pass1, epee::wipeable_string& pass2)
   {
     while (true)
     {
@@ -187,8 +177,8 @@ namespace
         if(pass1!=pass2)
         {
           std::cout << "Passwords do not match! Please try again." << std::endl;
-          clear(pass1);
-          clear(pass2);
+          pass1.clear();
+          pass2.clear();
         }
         else //new password matches
           return true;
@@ -201,7 +191,7 @@ namespace
     return false;
   }
 
-  bool read_from_file(std::string& pass)
+  bool read_from_file(epee::wipeable_string& pass)
   {
     pass.reserve(tools::password_container::max_password_size);
     for (size_t i = 0; i < tools::password_container::max_password_size; ++i)
@@ -236,7 +226,7 @@ namespace tools
 
   password_container::~password_container() noexcept
   {
-    clear(m_password);
+    m_password.clear();
   }
 
   boost::optional<password_container> password_container::prompt(const bool verify, const char *message)
@@ -252,9 +242,8 @@ namespace tools
   boost::optional<login> login::parse(std::string&& userpass, bool verify, const std::function<boost::optional<password_container>(bool)> &prompt)
   {
     login out{};
-    password_container wipe{std::move(userpass)};
 
-    const auto loc = wipe.password().find(':');
+    const auto loc = userpass.find(':');
     if (loc == std::string::npos)
     {
       auto result = prompt(verify);
@@ -265,10 +254,11 @@ namespace tools
     }
     else
     {
-      out.password = password_container{wipe.password().substr(loc + 1)};
+      out.password = password_container{userpass.substr(loc + 1)};
     }
 
-    out.username = wipe.password().substr(0, loc);
+    out.username = userpass.substr(0, loc);
+    password_container wipe{std::move(userpass)};
     return {std::move(out)};
   }
 } 

src/common/password.h

@@ -32,6 +32,7 @@
 
 #include <string>
 #include <boost/optional/optional.hpp>
+#include "wipeable_string.h"
 
 namespace tools
 {
@@ -58,11 +59,10 @@ namespace tools
     password_container& operator=(const password_container&) = delete;
     password_container& operator=(password_container&&) = default;
 
-    const std::string& password() const noexcept { return m_password; }
+    const epee::wipeable_string &password() const noexcept { return m_password; }
 
   private:
-    //! TODO Custom allocator that locks to RAM?
-    std::string m_password;
+    epee::wipeable_string m_password;
   };
 
   struct login

src/common/util.cpp

@@ -36,9 +36,11 @@
 
 #include "include_base_utils.h"
 #include "file_io_utils.h"
+#include "wipeable_string.h"
 using namespace epee;
 
 #include "util.h"
+#include "memwipe.h"
 #include "cryptonote_config.h"
 #include "net/http_client.h"                        // epee::net_utils::...
 
@@ -542,6 +544,8 @@ std::string get_nix_version_display_string()
   }
   bool on_startup()
   {
+    wipeable_string::set_wipe(&memwipe);
+
     mlog_configure("", true);
 
     sanitize_locale();