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1// SPDX-License-Identifier: GPL-2.0-or-later2/*3 * Copyright (c) 2016, Intel Corporation4 * 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) + 3 * sizeof(int))14 15static 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 23static 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 29static inline unsigned int dh_data_size(const struct dh *p)30{31 return p->key_size + p->p_size + p->g_size;32}33 34unsigned int crypto_dh_key_len(const struct dh *p)35{36 return DH_KPP_SECRET_MIN_SIZE + dh_data_size(p);37}38EXPORT_SYMBOL_GPL(crypto_dh_key_len);39 40int 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 = len47 };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->g_size, sizeof(params->g_size));57 ptr = dh_pack_data(ptr, end, params->key, params->key_size);58 ptr = dh_pack_data(ptr, end, params->p, params->p_size);59 ptr = dh_pack_data(ptr, end, params->g, params->g_size);60 if (ptr != end)61 return -EINVAL;62 return 0;63}64EXPORT_SYMBOL_GPL(crypto_dh_encode_key);65 66int __crypto_dh_decode_key(const char *buf, unsigned int len, struct dh *params)67{68 const u8 *ptr = buf;69 struct kpp_secret secret;70 71 if (unlikely(!buf || len < DH_KPP_SECRET_MIN_SIZE))72 return -EINVAL;73 74 ptr = dh_unpack_data(&secret, ptr, sizeof(secret));75 if (secret.type != CRYPTO_KPP_SECRET_TYPE_DH)76 return -EINVAL;77 78 ptr = dh_unpack_data(¶ms->key_size, ptr, sizeof(params->key_size));79 ptr = dh_unpack_data(¶ms->p_size, ptr, sizeof(params->p_size));80 ptr = dh_unpack_data(¶ms->g_size, ptr, sizeof(params->g_size));81 if (secret.len != crypto_dh_key_len(params))82 return -EINVAL;83 84 /* Don't allocate memory. Set pointers to data within85 * the given buffer86 */87 params->key = (void *)ptr;88 params->p = (void *)(ptr + params->key_size);89 params->g = (void *)(ptr + params->key_size + params->p_size);90 91 return 0;92}93 94int crypto_dh_decode_key(const char *buf, unsigned int len, struct dh *params)95{96 int err;97 98 err = __crypto_dh_decode_key(buf, len, params);99 if (err)100 return err;101 102 /*103 * Don't permit the buffer for 'key' or 'g' to be larger than 'p', since104 * some drivers assume otherwise.105 */106 if (params->key_size > params->p_size ||107 params->g_size > params->p_size)108 return -EINVAL;109 110 /*111 * Don't permit 'p' to be 0. It's not a prime number, and it's subject112 * to corner cases such as 'mod 0' being undefined or113 * crypto_kpp_maxsize() returning 0.114 */115 if (memchr_inv(params->p, 0, params->p_size) == NULL)116 return -EINVAL;117 118 return 0;119}120EXPORT_SYMBOL_GPL(crypto_dh_decode_key);121