Remove CRYPTOPP_ALLOW_UNALIGNED_DATA_ACCESS support (GH #682)

We were able to gut CRYPTOPP_ALLOW_UNALIGNED_DATA_ACCESS for everything except Rijndael. Rijndael uses unaligned accesses on x86 to harden against timing attacks.
There's a little more to CRYPTOPP_ALLOW_UNALIGNED_DATA_ACCESS and Rijndael. If we remove unaligned access then AliasedWithTable hangs in an endless loop on non-AESNI machines. So care must be taken when trying to remove the vestige from Rijndael.

1 files changed, 8 insertions, 23 deletions

diff --git a/misc.h b/misc.h
index 12529781..a80b3801 100644
--- a/misc.h
+++ b/misc.h
@@ -1043,22 +1043,15 @@ inline T1 RoundUpToMultipleOf(const T1 &n, const T2 &m)
 /// \brief Returns the minimum alignment requirements of a type

 /// \tparam T class or type

 /// \returns the minimum alignment requirements of <tt>T</tt>, in bytes

-/// \details Internally the function calls C++11's <tt>alignof</tt> if available. If not available,

-///   then the function uses compiler specific extensions such as <tt>__alignof</tt> and

-///   <tt>_alignof_</tt>. If an extension is not available, then the function uses

-///   <tt>__BIGGEST_ALIGNMENT__</tt> if <tt>__BIGGEST_ALIGNMENT__</tt> is smaller than <tt>sizeof(T)</tt>.

-///   <tt>sizeof(T)</tt> is used if all others are not available.

-///   In <em>all</em> cases, if <tt>CRYPTOPP_ALLOW_UNALIGNED_DATA_ACCESS</tt> is defined, then the

-///   function returns 1.

+/// \details Internally the function calls C++11's <tt>alignof</tt> if available. If not

+///   available, then the function uses compiler specific extensions such as

+///   <tt>__alignof</tt> and <tt>_alignof_</tt>. If an extension is not available, then

+///   the function uses <tt>__BIGGEST_ALIGNMENT__</tt> if <tt>__BIGGEST_ALIGNMENT__</tt>

+///   is smaller than <tt>sizeof(T)</tt>. <tt>sizeof(T)</tt> is used if all others are

+///   not available.

 template <class T>

 inline unsigned int GetAlignmentOf()

 {

-// GCC 4.6 (circa 2008) and above aggressively uses vectorization.

-#if defined(CRYPTOPP_ALLOW_UNALIGNED_DATA_ACCESS)

-	if (sizeof(T) < 16)

-		return 1;

-#endif

-

 #if defined(CRYPTOPP_CXX11_ALIGNOF)

 	return alignof(T);

 #elif (_MSC_VER >= 1300)

@@ -2113,7 +2106,6 @@ inline void GetUserKey(ByteOrder order, T *out, size_t outlen, const byte *in, s
 	ConditionalByteReverse(order, out, out, RoundUpToMultipleOf(inlen, U));

 }

 

-#ifndef CRYPTOPP_ALLOW_UNALIGNED_DATA_ACCESS

 inline byte UnalignedGetWordNonTemplate(ByteOrder order, const byte *block, const byte *)

 {

 	CRYPTOPP_UNUSED(order);

@@ -2284,7 +2276,6 @@ inline void UnalignedbyteNonTemplate(ByteOrder order, byte *block, word64 value,
 		}

 	}

 }

-#endif	// #ifndef CRYPTOPP_ALLOW_UNALIGNED_DATA_ACCESS

 

 /// \brief Access a block of memory

 /// \tparam T class or type

@@ -2306,13 +2297,10 @@ template <class T>
 inline T GetWord(bool assumeAligned, ByteOrder order, const byte *block)

 {

 	CRYPTOPP_UNUSED(assumeAligned);

-#ifdef CRYPTOPP_ALLOW_UNALIGNED_DATA_ACCESS

-	return ConditionalByteReverse(order, *reinterpret_cast<const T *>((const void *)block));

-#else

+

 	T temp;

 	memcpy(&temp, block, sizeof(T));

 	return ConditionalByteReverse(order, temp);

-#endif

 }

 

 /// \brief Access a block of memory

@@ -2351,14 +2339,11 @@ template <class T>
 inline void PutWord(bool assumeAligned, ByteOrder order, byte *block, T value, const byte *xorBlock = NULLPTR)

 {

 	CRYPTOPP_UNUSED(assumeAligned);

-#ifdef CRYPTOPP_ALLOW_UNALIGNED_DATA_ACCESS

-	*reinterpret_cast<T *>((void *)block) = ConditionalByteReverse(order, value) ^ (xorBlock ? *reinterpret_cast<const T *>((const void *)xorBlock) : 0);

-#else

+

 	T t1, t2;

 	t1 = ConditionalByteReverse(order, value);

 	if (xorBlock) {memcpy(&t2, xorBlock, sizeof(T)); t1 ^= t2;}

 	memcpy(block, &t1, sizeof(T));

-#endif

 }

 

 /// \brief Access a block of memory