1 /* 2 * Copyright (c) 2016, Intel Corporation 3 * Authors: Salvatore Benedetto <salvatore.benedetto@intel.com> 4 * 5 * This program is free software; you can redistribute it and/or 6 * modify it under the terms of the GNU General Public Licence 7 * as published by the Free Software Foundation; either version 8 * 2 of the Licence, or (at your option) any later version. 9 */ 10 #include <linux/kernel.h> 11 #include <linux/export.h> 12 #include <linux/err.h> 13 #include <linux/string.h> 14 #include <crypto/dh.h> 15 #include <crypto/kpp.h> 16 17 #define DH_KPP_SECRET_MIN_SIZE (sizeof(struct kpp_secret) + 3 * sizeof(int)) 18 19 static inline u8 *dh_pack_data(void *dst, const void *src, size_t size) 20 { 21 memcpy(dst, src, size); 22 return dst + size; 23 } 24 25 static inline const u8 *dh_unpack_data(void *dst, const void *src, size_t size) 26 { 27 memcpy(dst, src, size); 28 return src + size; 29 } 30 31 static inline int dh_data_size(const struct dh *p) 32 { 33 return p->key_size + p->p_size + p->g_size; 34 } 35 36 int crypto_dh_key_len(const struct dh *p) 37 { 38 return DH_KPP_SECRET_MIN_SIZE + dh_data_size(p); 39 } 40 EXPORT_SYMBOL_GPL(crypto_dh_key_len); 41 42 int crypto_dh_encode_key(char *buf, unsigned int len, const struct dh *params) 43 { 44 u8 *ptr = buf; 45 struct kpp_secret secret = { 46 .type = CRYPTO_KPP_SECRET_TYPE_DH, 47 .len = len 48 }; 49 50 if (unlikely(!buf)) 51 return -EINVAL; 52 53 if (len != crypto_dh_key_len(params)) 54 return -EINVAL; 55 56 ptr = dh_pack_data(ptr, &secret, sizeof(secret)); 57 ptr = dh_pack_data(ptr, ¶ms->key_size, sizeof(params->key_size)); 58 ptr = dh_pack_data(ptr, ¶ms->p_size, sizeof(params->p_size)); 59 ptr = dh_pack_data(ptr, ¶ms->g_size, sizeof(params->g_size)); 60 ptr = dh_pack_data(ptr, params->key, params->key_size); 61 ptr = dh_pack_data(ptr, params->p, params->p_size); 62 dh_pack_data(ptr, params->g, params->g_size); 63 64 return 0; 65 } 66 EXPORT_SYMBOL_GPL(crypto_dh_encode_key); 67 68 int crypto_dh_decode_key(const char *buf, unsigned int len, struct dh *params) 69 { 70 const u8 *ptr = buf; 71 struct kpp_secret secret; 72 73 if (unlikely(!buf || len < DH_KPP_SECRET_MIN_SIZE)) 74 return -EINVAL; 75 76 ptr = dh_unpack_data(&secret, ptr, sizeof(secret)); 77 if (secret.type != CRYPTO_KPP_SECRET_TYPE_DH) 78 return -EINVAL; 79 80 ptr = dh_unpack_data(¶ms->key_size, ptr, sizeof(params->key_size)); 81 ptr = dh_unpack_data(¶ms->p_size, ptr, sizeof(params->p_size)); 82 ptr = dh_unpack_data(¶ms->g_size, ptr, sizeof(params->g_size)); 83 if (secret.len != crypto_dh_key_len(params)) 84 return -EINVAL; 85 86 /* Don't allocate memory. Set pointers to data within 87 * the given buffer 88 */ 89 params->key = (void *)ptr; 90 params->p = (void *)(ptr + params->key_size); 91 params->g = (void *)(ptr + params->key_size + params->p_size); 92 93 return 0; 94 } 95 EXPORT_SYMBOL_GPL(crypto_dh_decode_key); 96