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/*
* Memory Operations
* (C) 1999-2009,2012,2015 Jack Lloyd
*
* Botan is released under the Simplified BSD License (see license.txt)
*/
#ifndef BOTAN_MEMORY_OPS_H_
#define BOTAN_MEMORY_OPS_H_
#include <botan/types.h>
#include <cstring>
#include <type_traits>
#include <vector>
namespace Botan {
/**
* Allocate a memory buffer by some method. This should only be used for
* primitive types (uint8_t, uint32_t, etc).
*
* @param elems the number of elements
* @param elem_size the size of each element
* @return pointer to allocated and zeroed memory, or throw std::bad_alloc on failure
*/
BOTAN_PUBLIC_API(2,3) BOTAN_MALLOC_FN void* allocate_memory(size_t elems, size_t elem_size);
/**
* Free a pointer returned by allocate_memory
* @param p the pointer returned by allocate_memory
* @param elems the number of elements, as passed to allocate_memory
* @param elem_size the size of each element, as passed to allocate_memory
*/
BOTAN_PUBLIC_API(2,3) void deallocate_memory(void* p, size_t elems, size_t elem_size);
/**
* Ensure the allocator is initialized
*/
void initialize_allocator();
class Allocator_Initializer
{
public:
Allocator_Initializer() { initialize_allocator(); }
};
/**
* Scrub memory contents in a way that a compiler should not elide,
* using some system specific technique. Note that this function might
* not zero the memory (for example, in some hypothetical
* implementation it might combine the memory contents with the output
* of a system PRNG), but if you can detect any difference in behavior
* at runtime then the clearing is side-effecting and you can just
* use `clear_mem`.
*
* Use this function to scrub memory just before deallocating it, or on
* a stack buffer before returning from the function.
*
* @param ptr a pointer to memory to scrub
* @param n the number of bytes pointed to by ptr
*/
BOTAN_PUBLIC_API(2,0) void secure_scrub_memory(void* ptr, size_t n);
/**
* Memory comparison, input insensitive
* @param x a pointer to an array
* @param y a pointer to another array
* @param len the number of Ts in x and y
* @return 0xFF iff x[i] == y[i] forall i in [0...n) or 0x00 otherwise
*/
BOTAN_PUBLIC_API(2,9) uint8_t ct_compare_u8(const uint8_t x[],
const uint8_t y[],
size_t len);
/**
* Memory comparison, input insensitive
* @param x a pointer to an array
* @param y a pointer to another array
* @param len the number of Ts in x and y
* @return true iff x[i] == y[i] forall i in [0...n)
*/
inline bool constant_time_compare(const uint8_t x[],
const uint8_t y[],
size_t len)
{
return ct_compare_u8(x, y, len) == 0xFF;
}
/**
* Zero out some bytes
* @param ptr a pointer to memory to zero
* @param bytes the number of bytes to zero in ptr
*/
inline void clear_bytes(void* ptr, size_t bytes)
{
if(bytes > 0)
{
std::memset(ptr, 0, bytes);
}
}
/**
* Zero memory before use. This simply calls memset and should not be
* used in cases where the compiler cannot see the call as a
* side-effecting operation (for example, if calling clear_mem before
* deallocating memory, the compiler would be allowed to omit the call
* to memset entirely under the as-if rule.)
*
* @param ptr a pointer to an array of Ts to zero
* @param n the number of Ts pointed to by ptr
*/
template<typename T> inline void clear_mem(T* ptr, size_t n)
{
clear_bytes(ptr, sizeof(T)*n);
}
// is_trivially_copyable is missing in g++ < 5.0
#if !__clang__ && __GNUG__ && __GNUC__ < 5
#define BOTAN_IS_TRIVIALLY_COPYABLE(T) true
#else
#define BOTAN_IS_TRIVIALLY_COPYABLE(T) std::is_trivially_copyable<T>::value
#endif
/**
* Copy memory
* @param out the destination array
* @param in the source array
* @param n the number of elements of in/out
*/
template<typename T> inline void copy_mem(T* out, const T* in, size_t n)
{
static_assert(std::is_trivial<typename std::decay<T>::type>::value, "");
if(n > 0)
{
std::memmove(out, in, sizeof(T)*n);
}
}
template<typename T> inline void typecast_copy(uint8_t out[], T in[], size_t N)
{
static_assert(BOTAN_IS_TRIVIALLY_COPYABLE(T), "");
std::memcpy(out, in, sizeof(T)*N);
}
template<typename T> inline void typecast_copy(T out[], const uint8_t in[], size_t N)
{
static_assert(std::is_trivial<T>::value, "");
std::memcpy(out, in, sizeof(T)*N);
}
template<typename T> inline void typecast_copy(uint8_t out[], T in)
{
typecast_copy(out, &in, 1);
}
template<typename T> inline void typecast_copy(T& out, const uint8_t in[])
{
static_assert(std::is_trivial<typename std::decay<T>::type>::value, "");
typecast_copy(&out, in, 1);
}
template <class To, class From> inline To typecast_copy(const From *src) noexcept
{
static_assert(BOTAN_IS_TRIVIALLY_COPYABLE(From) && std::is_trivial<To>::value, "");
To dst;
std::memcpy(&dst, src, sizeof(To));
return dst;
}
/**
* Set memory to a fixed value
* @param ptr a pointer to an array of bytes
* @param n the number of Ts pointed to by ptr
* @param val the value to set each byte to
*/
inline void set_mem(uint8_t* ptr, size_t n, uint8_t val)
{
if(n > 0)
{
std::memset(ptr, val, n);
}
}
inline const uint8_t* cast_char_ptr_to_uint8(const char* s)
{
return reinterpret_cast<const uint8_t*>(s);
}
inline const char* cast_uint8_ptr_to_char(const uint8_t* b)
{
return reinterpret_cast<const char*>(b);
}
inline uint8_t* cast_char_ptr_to_uint8(char* s)
{
return reinterpret_cast<uint8_t*>(s);
}
inline char* cast_uint8_ptr_to_char(uint8_t* b)
{
return reinterpret_cast<char*>(b);
}
/**
* Memory comparison, input insensitive
* @param p1 a pointer to an array
* @param p2 a pointer to another array
* @param n the number of Ts in p1 and p2
* @return true iff p1[i] == p2[i] forall i in [0...n)
*/
template<typename T> inline bool same_mem(const T* p1, const T* p2, size_t n)
{
volatile T difference = 0;
for(size_t i = 0; i != n; ++i)
difference |= (p1[i] ^ p2[i]);
return difference == 0;
}
/**
* XOR arrays. Postcondition out[i] = in[i] ^ out[i] forall i = 0...length
* @param out the input/output buffer
* @param in the read-only input buffer
* @param length the length of the buffers
*/
inline void xor_buf(uint8_t out[],
const uint8_t in[],
size_t length)
{
const size_t blocks = length - (length % 32);
for(size_t i = 0; i != blocks; i += 32)
{
uint64_t x[4];
uint64_t y[4];
typecast_copy(x, out + i, 4);
typecast_copy(y, in + i, 4);
x[0] ^= y[0];
x[1] ^= y[1];
x[2] ^= y[2];
x[3] ^= y[3];
typecast_copy(out + i, x, 4);
}
for(size_t i = blocks; i != length; ++i)
{
out[i] ^= in[i];
}
}
/**
* XOR arrays. Postcondition out[i] = in[i] ^ in2[i] forall i = 0...length
* @param out the output buffer
* @param in the first input buffer
* @param in2 the second output buffer
* @param length the length of the three buffers
*/
inline void xor_buf(uint8_t out[],
const uint8_t in[],
const uint8_t in2[],
size_t length)
{
const size_t blocks = length - (length % 32);
for(size_t i = 0; i != blocks; i += 32)
{
uint64_t x[4];
uint64_t y[4];
typecast_copy(x, in + i, 4);
typecast_copy(y, in2 + i, 4);
x[0] ^= y[0];
x[1] ^= y[1];
x[2] ^= y[2];
x[3] ^= y[3];
typecast_copy(out + i, x, 4);
}
for(size_t i = blocks; i != length; ++i)
{
out[i] = in[i] ^ in2[i];
}
}
template<typename Alloc, typename Alloc2>
void xor_buf(std::vector<uint8_t, Alloc>& out,
const std::vector<uint8_t, Alloc2>& in,
size_t n)
{
xor_buf(out.data(), in.data(), n);
}
template<typename Alloc>
void xor_buf(std::vector<uint8_t, Alloc>& out,
const uint8_t* in,
size_t n)
{
xor_buf(out.data(), in, n);
}
template<typename Alloc, typename Alloc2>
void xor_buf(std::vector<uint8_t, Alloc>& out,
const uint8_t* in,
const std::vector<uint8_t, Alloc2>& in2,
size_t n)
{
xor_buf(out.data(), in, in2.data(), n);
}
template<typename Alloc, typename Alloc2>
std::vector<uint8_t, Alloc>&
operator^=(std::vector<uint8_t, Alloc>& out,
const std::vector<uint8_t, Alloc2>& in)
{
if(out.size() < in.size())
out.resize(in.size());
xor_buf(out.data(), in.data(), in.size());
return out;
}
}
#endif
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