mmap_mem.cpp

QT安全系统

/*
Copyright (C) 1999-2007 The Botan Project. All rights reserved.

Redistribution and use in source and binary forms, for any use, with or without
modification, is permitted provided that the following conditions are met:

1. Redistributions of source code must retain the above copyright notice, this
list of conditions, and the following disclaimer.

2. Redistributions in binary form must reproduce the above copyright notice,
this list of conditions, and the following disclaimer in the documentation
and/or other materials provided with the distribution.

THIS SOFTWARE IS PROVIDED BY THE AUTHOR(S) "AS IS" AND ANY EXPRESS OR IMPLIED
WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, ARE DISCLAIMED.

IN NO EVENT SHALL THE AUTHOR(S) OR CONTRIBUTOR(S) BE LIABLE FOR ANY DIRECT,
INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
// LICENSEHEADER_END
namespace QCA { // WRAPNS_LINE
/*************************************************
* Memory Mapping Allocator Source File           *
* (C) 1999-2007 The Botan Project                *
*************************************************/

} // WRAPNS_LINE
#include <botan/mmap_mem.h>
namespace QCA { // WRAPNS_LINE
} // WRAPNS_LINE
#include <cstring>
namespace QCA { // WRAPNS_LINE

#ifndef _XOPEN_SOURCE
  #define _XOPEN_SOURCE 500
#endif

#ifndef _XOPEN_SOURCE_EXTENDED
  #define _XOPEN_SOURCE_EXTENDED 1
#endif

} // WRAPNS_LINE
#include <sys/types.h>
namespace QCA { // WRAPNS_LINE
} // WRAPNS_LINE
#include <sys/mman.h>
namespace QCA { // WRAPNS_LINE
} // WRAPNS_LINE
#include <sys/stat.h>
namespace QCA { // WRAPNS_LINE
} // WRAPNS_LINE
#include <unistd.h>
namespace QCA { // WRAPNS_LINE
} // WRAPNS_LINE
#include <stdlib.h>
namespace QCA { // WRAPNS_LINE
} // WRAPNS_LINE
#include <fcntl.h>
namespace QCA { // WRAPNS_LINE

#ifndef MAP_FAILED
   #define MAP_FAILED -1
#endif

namespace Botan {

namespace {

/*************************************************
* MemoryMapping_Allocator Exception              *
*************************************************/
class MemoryMapping_Failed : public Exception
   {
   public:
      MemoryMapping_Failed(const std::string& msg) :
         Exception("MemoryMapping_Allocator: " + msg) {}
   };

}

/*************************************************
* Memory Map a File into Memory                  *
*************************************************/
void* MemoryMapping_Allocator::alloc_block(u32bit n)
   {
   class TemporaryFile
      {
      public:
         int get_fd() const { return fd; }
         const std::string path() const { return filepath; }

         TemporaryFile(const std::string& base)
            {
            const std::string path = base + "XXXXXX";

            filepath = new char[path.length() + 1];
            std::strcpy(filepath, path.c_str());

            mode_t old_umask = umask(077);
            fd = mkstemp(filepath);
            umask(old_umask);
            }

         ~TemporaryFile()
            {
            delete[] filepath;
            if(fd != -1 && close(fd) == -1)
               throw MemoryMapping_Failed("Could not close file");
            }
      private:
         int fd;
         char* filepath;
      };

   TemporaryFile file("/tmp/botan_");

   if(file.get_fd() == -1)
      throw MemoryMapping_Failed("Could not create file");

   if(unlink(file.path().c_str()))
      throw MemoryMapping_Failed("Could not unlink file " + file.path());

   lseek(file.get_fd(), n-1, SEEK_SET);
   if(write(file.get_fd(), "\0", 1) != 1)
      throw MemoryMapping_Failed("Could not write to file");

   void* ptr = mmap(0, n, PROT_READ | PROT_WRITE, MAP_SHARED,
                    file.get_fd(), 0);

   if(ptr == (void*)MAP_FAILED)
      throw MemoryMapping_Failed("Could not map file");

   return ptr;
   }

/*************************************************
* Remove a Memory Mapping                        *
*************************************************/
void MemoryMapping_Allocator::dealloc_block(void* ptr, u32bit n)
   {
   if(ptr == 0) return;
#ifdef MLOCK_NOT_VOID_PTR
# define MLOCK_TYPE_CAST (char *)
#else
# define MLOCK_TYPE_CAST
#endif

   const u32bit OVERWRITE_PASSES = 12;
   const byte PATTERNS[] = { 0x00, 0xFF, 0xAA, 0x55, 0x73, 0x8C, 0x5F, 0xA0,
                             0x6E, 0x91, 0x30, 0xCF, 0xD3, 0x2C, 0xAC, 0x53 };

   for(u32bit j = 0; j != OVERWRITE_PASSES; j++)
      {
      std::memset(ptr, PATTERNS[j % sizeof(PATTERNS)], n);
      if(msync(MLOCK_TYPE_CAST ptr, n, MS_SYNC))
         throw MemoryMapping_Failed("Sync operation failed");
      }
   std::memset(ptr, 0, n);
   if(msync(MLOCK_TYPE_CAST ptr, n, MS_SYNC))
      throw MemoryMapping_Failed("Sync operation failed");

   if(munmap(MLOCK_TYPE_CAST ptr, n))
      throw MemoryMapping_Failed("Could not unmap file");
   }

}
} // WRAPNS_LINE