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/*
* Copyright (c) 2016, Intel Corporation
* Authors: Salvatore Benedetto <salvatore.benedetto@intel.com>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#include <linux/kernel.h>
#include <linux/export.h>
#include <linux/err.h>
#include <linux/string.h>
#include <crypto/dh.h>
#include <crypto/kpp.h>
#define DH_KPP_SECRET_MIN_SIZE (sizeof(struct kpp_secret) + 4 * sizeof(int))
static inline u8 *dh_pack_data(u8 *dst, u8 *end, const void *src, size_t size)
{
if (!dst || size > end - dst)
return NULL;
memcpy(dst, src, size);
return dst + size;
}
static inline const u8 *dh_unpack_data(void *dst, const void *src, size_t size)
{
memcpy(dst, src, size);
return src + size;
}
static inline unsigned int dh_data_size(const struct dh *p)
{
return p->key_size + p->p_size + p->q_size + p->g_size;
}
unsigned int crypto_dh_key_len(const struct dh *p)
{
return DH_KPP_SECRET_MIN_SIZE + dh_data_size(p);
}
EXPORT_SYMBOL_GPL(crypto_dh_key_len);
int crypto_dh_encode_key(char *buf, unsigned int len, const struct dh *params)
{
u8 *ptr = buf;
u8 * const end = ptr + len;
struct kpp_secret secret = {
.type = CRYPTO_KPP_SECRET_TYPE_DH,
.len = len
};
if (unlikely(!len))
return -EINVAL;
ptr = dh_pack_data(ptr, end, &secret, sizeof(secret));
ptr = dh_pack_data(ptr, end, ¶ms->key_size,
sizeof(params->key_size));
ptr = dh_pack_data(ptr, end, ¶ms->p_size, sizeof(params->p_size));
ptr = dh_pack_data(ptr, end, ¶ms->q_size, sizeof(params->q_size));
ptr = dh_pack_data(ptr, end, ¶ms->g_size, sizeof(params->g_size));
ptr = dh_pack_data(ptr, end, params->key, params->key_size);
ptr = dh_pack_data(ptr, end, params->p, params->p_size);
ptr = dh_pack_data(ptr, end, params->q, params->q_size);
ptr = dh_pack_data(ptr, end, params->g, params->g_size);
if (ptr != end)
return -EINVAL;
return 0;
}
EXPORT_SYMBOL_GPL(crypto_dh_encode_key);
int crypto_dh_decode_key(const char *buf, unsigned int len, struct dh *params)
{
const u8 *ptr = buf;
struct kpp_secret secret;
if (unlikely(!buf || len < DH_KPP_SECRET_MIN_SIZE))
return -EINVAL;
ptr = dh_unpack_data(&secret, ptr, sizeof(secret));
if (secret.type != CRYPTO_KPP_SECRET_TYPE_DH)
return -EINVAL;
ptr = dh_unpack_data(¶ms->key_size, ptr, sizeof(params->key_size));
ptr = dh_unpack_data(¶ms->p_size, ptr, sizeof(params->p_size));
ptr = dh_unpack_data(¶ms->q_size, ptr, sizeof(params->q_size));
ptr = dh_unpack_data(¶ms->g_size, ptr, sizeof(params->g_size));
if (secret.len != crypto_dh_key_len(params))
return -EINVAL;
/*
* Don't permit the buffer for 'key' or 'g' to be larger than 'p', since
* some drivers assume otherwise.
*/
if (params->key_size > params->p_size ||
params->g_size > params->p_size || params->q_size > params->p_size)
return -EINVAL;
/* Don't allocate memory. Set pointers to data within
* the given buffer
*/
params->key = (void *)ptr;
params->p = (void *)(ptr + params->key_size);
params->q = (void *)(ptr + params->key_size + params->p_size);
params->g = (void *)(ptr + params->key_size + params->p_size +
params->q_size);
/*
* Don't permit 'p' to be 0. It's not a prime number, and it's subject
* to corner cases such as 'mod 0' being undefined or
* crypto_kpp_maxsize() returning 0.
*/
if (memchr_inv(params->p, 0, params->p_size) == NULL)
return -EINVAL;
/* It is permissible to not provide Q. */
if (params->q_size == 0)
params->q = NULL;
return 0;
}
EXPORT_SYMBOL_GPL(crypto_dh_decode_key);
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