Merge pull request 'fixed build from scratch without OpenSSL leftovers' (#2) from miodrag into dev

configure.ac

@@ -665,7 +665,7 @@ if test x$use_pkgconfig = xyes; then
     [PKG_CHECK_MODULES],
     [
       PKG_CHECK_MODULES([SSL], [wolfssl],, [AC_MSG_ERROR(WolfSSL not found.)])
-      #PKG_CHECK_MODULES([CRYPTO], [libcrypto],,[AC_MSG_ERROR(libcrypto  not found.)])
+      PKG_CHECK_MODULES([CRYPTO], [wolfssl],,[AC_MSG_ERROR(libcrypto  not found.)])
       if test x$build_bitcoin_utils$build_bitcoind$bitcoin_enable_qt$use_tests != xnononono; then
         PKG_CHECK_MODULES([EVENT], [libevent],, [AC_MSG_ERROR(libevent not found.)])
         if test x$TARGET_OS != xwindows; then
@@ -689,7 +689,7 @@ else
   echo 'BUG: configure does not yet check for the following dependencies if pkg-config is not on the system: libcrypto++, gmp'
 
   AC_CHECK_HEADER([wolfssl/openssl/crypto.h],,AC_MSG_ERROR(libcrypto headers missing))
-  AC_CHECK_LIB([crypto],      [main],CRYPTO_LIBS=-lcrypto, AC_MSG_ERROR(libcrypto missing))
+  AC_CHECK_LIB([crypto],      [main],CRYPTO_LIBS=-lwolfssl, AC_MSG_ERROR(libcrypto missing))
 
   AC_CHECK_HEADER([wolfssl/ssl.h],, AC_MSG_ERROR(libssl headers missing),)
   AC_CHECK_LIB([wolfssl],         [main],SSL_LIBS=-lwolfssl, AC_MSG_ERROR(libwolfssl missing))
@@ -764,7 +764,7 @@ AX_CHECK_COMPILE_FLAG([-fwrapv],[CXXFLAGS="$CXXFLAGS -fwrapv"])
 AX_CHECK_COMPILE_FLAG([-fno-strict-aliasing],[CXXFLAGS="$CXXFLAGS -fno-strict-aliasing"])
 AX_CHECK_COMPILE_FLAG([-Wno-builtin-declaration-mismatch],[CXXFLAGS="$CXXFLAGS -Wno-builtin-declaration-mismatch"],,[[$CXXFLAG_WERROR]])
 
-LIBZCASH_LIBS="-lgmp -lgmpxx $BOOST_SYSTEM_LIB -lcrypto -lsodium $RUST_LIBS"
+LIBZCASH_LIBS="-lgmp -lgmpxx $BOOST_SYSTEM_LIB -lwolfssl -lsodium $RUST_LIBS"
 
 AC_MSG_CHECKING([whether to build komodod])
 AM_CONDITIONAL([BUILD_BITCOIND], [test x$build_bitcoind = xyes])

src/support/cleanse.cpp

@@ -3,11 +3,33 @@
 // Distributed under the GPLv3 software license, see the accompanying
 // file COPYING or https://www.gnu.org/licenses/gpl-3.0.en.html
 
-#include "cleanse.h"
+#include <support/cleanse.h>
 
-#include <openssl/crypto.h>
+#include <cstring>
+
+#if defined(_MSC_VER)
+#include <Windows.h> // For SecureZeroMemory.
+#endif
 
 void memory_cleanse(void *ptr, size_t len)
 {
-    OPENSSL_cleanse(ptr, len);
+#if defined(_MSC_VER)
+    /* SecureZeroMemory is guaranteed not to be optimized out by MSVC. */
+    SecureZeroMemory(ptr, len);
+#else
+    std::memset(ptr, 0, len);
+
+    /* Memory barrier that scares the compiler away from optimizing out the memset.
+     *
+     * Quoting Adam Langley <agl@google.com> in commit ad1907fe73334d6c696c8539646c21b11178f20f
+     * in BoringSSL (ISC License):
+     *    As best as we can tell, this is sufficient to break any optimisations that
+     *    might try to eliminate "superfluous" memsets.
+     * This method is used in memzero_explicit() the Linux kernel, too. Its advantage is that it
+     * is pretty efficient because the compiler can still implement the memset() efficiently,
+     * just not remove it entirely. See "Dead Store Elimination (Still) Considered Harmful" by
+     * Yang et al. (USENIX Security 2017) for more background.
+     */
+    __asm__ __volatile__("" : : "r"(ptr) : "memory");
+#endif
 }

src/support/cleanse.h

@@ -8,6 +8,8 @@
 
 #include <stdlib.h>
 
+/** Secure overwrite a buffer (possibly containing secret data) with zero-bytes. The write
+ * operation will not be optimized out by the compiler. */
 void memory_cleanse(void *ptr, size_t len);
 
 #endif // BITCOIN_SUPPORT_CLEANSE_H

src/wallet/crypter.cpp

@@ -28,8 +28,8 @@
 #include <string>
 #include <vector>
 #include <boost/foreach.hpp>
-#include <openssl/aes.h>
+#include <wolfssl/openssl/aes.h>
-#include <openssl/evp.h>
+#include <wolfssl/openssl/evp.h>
 
 using namespace libzcash;