LXR linux/crypto/dh

   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) + 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 = 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, &params->key_size,
  54                           sizeof(params->key_size));
  55        ptr = dh_pack_data(ptr, end, &params->p_size, sizeof(params->p_size));
  56        ptr = dh_pack_data(ptr, end, &params->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(&params->key_size, ptr, sizeof(params->key_size));
  79        ptr = dh_unpack_data(&params->p_size, ptr, sizeof(params->p_size));
  80        ptr = dh_unpack_data(&params->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 within
  85         * the given buffer
  86         */
  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', since
 104         * 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 subject
 112         * to corner cases such as 'mod 0' being undefined or
 113         * 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