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don't use memset() in privacy/security relevant code parts

As memset() can be optimized out by a compiler it should not be used in
privacy/security relevant code parts. OpenSSL provides the safe
OPENSSL_cleanse() function in crypto.h, which perfectly does the job of
clean and overwrite data.

For details see: http://www.viva64.com/en/b/0178/

- change memset() to OPENSSL_cleanse() where appropriate
- change a hard-coded number from netbase.cpp into a sizeof()
0.8
Philip Kaufmann 12 years ago
parent
commit
0f8a647782
  1. 5
      src/allocators.h
  2. 6
      src/base58.h
  3. 4
      src/crypter.cpp
  4. 4
      src/crypter.h
  5. 2
      src/netbase.cpp
  6. 2
      src/util.cpp

5
src/allocators.h

@ -9,6 +9,7 @@ @@ -9,6 +9,7 @@
#include <string>
#include <boost/thread/mutex.hpp>
#include <map>
#include <openssl/crypto.h> // for OPENSSL_cleanse()
#ifdef WIN32
#ifdef _WIN32_WINNT
@ -212,7 +213,7 @@ struct secure_allocator : public std::allocator<T> @@ -212,7 +213,7 @@ struct secure_allocator : public std::allocator<T>
{
if (p != NULL)
{
memset(p, 0, sizeof(T) * n);
OPENSSL_cleanse(p, sizeof(T) * n);
LockedPageManager::instance.UnlockRange(p, sizeof(T) * n);
}
std::allocator<T>::deallocate(p, n);
@ -246,7 +247,7 @@ struct zero_after_free_allocator : public std::allocator<T> @@ -246,7 +247,7 @@ struct zero_after_free_allocator : public std::allocator<T>
void deallocate(T* p, std::size_t n)
{
if (p != NULL)
memset(p, 0, sizeof(T) * n);
OPENSSL_cleanse(p, sizeof(T) * n);
std::allocator<T>::deallocate(p, n);
}
};

6
src/base58.h

@ -17,6 +17,8 @@ @@ -17,6 +17,8 @@
#include <string>
#include <vector>
#include <openssl/crypto.h> // for OPENSSL_cleanse()
#include "bignum.h"
#include "key.h"
#include "script.h"
@ -190,7 +192,7 @@ protected: @@ -190,7 +192,7 @@ protected:
{
// zero the memory, as it may contain sensitive data
if (!vchData.empty())
memset(&vchData[0], 0, vchData.size());
OPENSSL_cleanse(&vchData[0], vchData.size());
}
void SetData(int nVersionIn, const void* pdata, size_t nSize)
@ -221,7 +223,7 @@ public: @@ -221,7 +223,7 @@ public:
vchData.resize(vchTemp.size() - 1);
if (!vchData.empty())
memcpy(&vchData[0], &vchTemp[1], vchData.size());
memset(&vchTemp[0], 0, vchTemp.size());
OPENSSL_cleanse(&vchTemp[0], vchData.size());
return true;
}

4
src/crypter.cpp

@ -24,8 +24,8 @@ bool CCrypter::SetKeyFromPassphrase(const SecureString& strKeyData, const std::v @@ -24,8 +24,8 @@ bool CCrypter::SetKeyFromPassphrase(const SecureString& strKeyData, const std::v
if (i != (int)WALLET_CRYPTO_KEY_SIZE)
{
memset(&chKey, 0, sizeof chKey);
memset(&chIV, 0, sizeof chIV);
OPENSSL_cleanse(chKey, sizeof(chKey));
OPENSSL_cleanse(chIV, sizeof(chIV));
return false;
}

4
src/crypter.h

@ -76,8 +76,8 @@ public: @@ -76,8 +76,8 @@ public:
void CleanKey()
{
memset(&chKey, 0, sizeof chKey);
memset(&chIV, 0, sizeof chIV);
OPENSSL_cleanse(chKey, sizeof(chKey));
OPENSSL_cleanse(chIV, sizeof(chIV));
fKeySet = false;
}

2
src/netbase.cpp

@ -545,7 +545,7 @@ bool ConnectSocketByName(CService &addr, SOCKET& hSocketRet, const char *pszDest @@ -545,7 +545,7 @@ bool ConnectSocketByName(CService &addr, SOCKET& hSocketRet, const char *pszDest
void CNetAddr::Init()
{
memset(ip, 0, 16);
memset(ip, 0, sizeof(ip));
}
void CNetAddr::SetIP(const CNetAddr& ipIn)

2
src/util.cpp

@ -156,7 +156,7 @@ void RandAddSeedPerfmon() @@ -156,7 +156,7 @@ void RandAddSeedPerfmon()
if (ret == ERROR_SUCCESS)
{
RAND_add(pdata, nSize, nSize/100.0);
memset(pdata, 0, nSize);
OPENSSL_cleanse(pdata, nSize);
printf("RandAddSeed() %lu bytes\n", nSize);
}
#endif

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