1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * Copyright (c) 2016, Intel Corporation 4 * Authors: Salvatore Benedetto <salvatore.benedetto@intel.com> 5 */ 6 #include <linux/kernel.h> 7 #include <linux/export.h> 8 #include <linux/err.h> 9 #include <linux/string.h> 10 #include <crypto/dh.h> 11 #include <crypto/kpp.h> 12 13 #define DH_KPP_SECRET_MIN_SIZE (sizeof(struct kpp_secret) + 4 * sizeof(int)) 14 15 static inline u8 *dh_pack_data(u8 *dst, u8 *end, const void *src, size_t size) 16 { 17 if (!dst || size > end - dst) 18 return NULL; 19 memcpy(dst, src, size); 20 return dst + size; 21 } 22 23 static inline const u8 *dh_unpack_data(void *dst, const void *src, size_t size) 24 { 25 memcpy(dst, src, size); 26 return src + size; 27 } 28 29 static inline unsigned int dh_data_size(const struct dh *p) 30 { 31 return p->key_size + p->p_size + p->q_size + p->g_size; 32 } 33 34 unsigned int crypto_dh_key_len(const struct dh *p) 35 { 36 return DH_KPP_SECRET_MIN_SIZE + dh_data_size(p); 37 } 38 EXPORT_SYMBOL_GPL(crypto_dh_key_len); 39 40 int crypto_dh_encode_key(char *buf, unsigned int len, const struct dh *params) 41 { 42 u8 *ptr = buf; 43 u8 * const end = ptr + len; 44 struct kpp_secret secret = { 45 .type = CRYPTO_KPP_SECRET_TYPE_DH, 46 .len = len 47 }; 48 49 if (unlikely(!len)) 50 return -EINVAL; 51 52 ptr = dh_pack_data(ptr, end, &secret, sizeof(secret)); 53 ptr = dh_pack_data(ptr, end, ¶ms->key_size, 54 sizeof(params->key_size)); 55 ptr = dh_pack_data(ptr, end, ¶ms->p_size, sizeof(params->p_size)); 56 ptr = dh_pack_data(ptr, end, ¶ms->q_size, sizeof(params->q_size)); 57 ptr = dh_pack_data(ptr, end, ¶ms->g_size, sizeof(params->g_size)); 58 ptr = dh_pack_data(ptr, end, params->key, params->key_size); 59 ptr = dh_pack_data(ptr, end, params->p, params->p_size); 60 ptr = dh_pack_data(ptr, end, params->q, params->q_size); 61 ptr = dh_pack_data(ptr, end, params->g, params->g_size); 62 if (ptr != end) 63 return -EINVAL; 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->q_size, ptr, sizeof(params->q_size)); 83 ptr = dh_unpack_data(¶ms->g_size, ptr, sizeof(params->g_size)); 84 if (secret.len != crypto_dh_key_len(params)) 85 return -EINVAL; 86 87 /* 88 * Don't permit the buffer for 'key' or 'g' to be larger than 'p', since 89 * some drivers assume otherwise. 90 */ 91 if (params->key_size > params->p_size || 92 params->g_size > params->p_size || params->q_size > params->p_size) 93 return -EINVAL; 94 95 /* Don't allocate memory. Set pointers to data within 96 * the given buffer 97 */ 98 params->key = (void *)ptr; 99 params->p = (void *)(ptr + params->key_size); 100 params->q = (void *)(ptr + params->key_size + params->p_size); 101 params->g = (void *)(ptr + params->key_size + params->p_size + 102 params->q_size); 103 104 /* 105 * Don't permit 'p' to be 0. It's not a prime number, and it's subject 106 * to corner cases such as 'mod 0' being undefined or 107 * crypto_kpp_maxsize() returning 0. 108 */ 109 if (memchr_inv(params->p, 0, params->p_size) == NULL) 110 return -EINVAL; 111 112 /* It is permissible to not provide Q. */ 113 if (params->q_size == 0) 114 params->q = NULL; 115 116 return 0; 117 } 118 EXPORT_SYMBOL_GPL(crypto_dh_decode_key); 119