providers/common/exchange/dh_exch.c

   1 /*
   2  * Copyright 2019 The OpenSSL Project Authors. All Rights Reserved.
   3  *
   4  * Licensed under the Apache License 2.0 (the "License").  You may not use
   5  * this file except in compliance with the License.  You can obtain a copy
   6  * in the file LICENSE in the source distribution or at
   7  * https://www.openssl.org/source/license.html
   8  */
   9
  10 #include <openssl/crypto.h>
  11 #include <openssl/core_numbers.h>
  12 #include <openssl/core_names.h>
  13 #include <openssl/dh.h>
  14 #include <openssl/params.h>
  15 #include "internal/provider_algs.h"
  16
  17 static OSSL_OP_keyexch_newctx_fn dh_newctx;
  18 static OSSL_OP_keyexch_init_fn dh_init;
  19 static OSSL_OP_keyexch_set_peer_fn dh_set_peer;
  20 static OSSL_OP_keyexch_derive_fn dh_derive;
  21 static OSSL_OP_keyexch_freectx_fn dh_freectx;
  22 static OSSL_OP_keyexch_dupctx_fn dh_dupctx;
  23
  24 /*
  25  * What's passed as an actual key is defined by the KEYMGMT interface.
  26  * We happen to know that our KEYMGMT simply passes DH structures, so
  27  * we use that here too.
  28  */
  29
  30 typedef struct {
  31     DH *dh;
  32     DH *dhpeer;
  33     int pad;
  34 } PROV_DH_CTX;
  35
  36 static void *dh_newctx(void *provctx)
  37 {
  38     return OPENSSL_zalloc(sizeof(PROV_DH_CTX));
  39 }
  40
  41 static int dh_init(void *vpdhctx, void *vdh)
  42 {
  43     PROV_DH_CTX *pdhctx = (PROV_DH_CTX *)vpdhctx;
  44
  45     DH_free(pdhctx->dh);
  46     pdhctx->dh = vdh;
  47     DH_up_ref(pdhctx->dh);
  48
  49     return pdhctx->dh != NULL;
  50 }
  51
  52 static int dh_set_peer(void *vpdhctx, void *vdh)
  53 {
  54     PROV_DH_CTX *pdhctx = (PROV_DH_CTX *)vpdhctx;
  55
  56     DH_free(pdhctx->dhpeer);
  57     pdhctx->dhpeer = vdh;
  58     DH_up_ref(pdhctx->dhpeer);
  59
  60     return pdhctx->dhpeer != NULL;
  61 }
  62
  63 static int dh_derive(void *vpdhctx, unsigned char *key, size_t *keylen,
  64                      size_t outlen)
  65 {
  66     PROV_DH_CTX *pdhctx = (PROV_DH_CTX *)vpdhctx;
  67     int ret;
  68     size_t dhsize;
  69     const BIGNUM *pub_key = NULL;
  70
  71     /* TODO(3.0): Add errors to stack */
  72     if (pdhctx->dh == NULL || pdhctx->dhpeer == NULL)
  73         return 0;
  74
  75     dhsize = (size_t)DH_size(pdhctx->dh);
  76     if (key == NULL) {
  77         *keylen = dhsize;
  78         return 1;
  79     }
  80     if (outlen < dhsize)
  81         return 0;
  82
  83     DH_get0_key(pdhctx->dhpeer, &pub_key, NULL);
  84     ret = (pdhctx->pad) ? DH_compute_key_padded(key, pub_key, pdhctx->dh)
  85                         : DH_compute_key(key, pub_key, pdhctx->dh);
  86     if (ret <= 0)
  87         return 0;
  88
  89     *keylen = ret;
  90     return 1;
  91 }
  92
  93 static void dh_freectx(void *vpdhctx)
  94 {
  95     PROV_DH_CTX *pdhctx = (PROV_DH_CTX *)vpdhctx;
  96
  97     DH_free(pdhctx->dh);
  98     DH_free(pdhctx->dhpeer);
  99
 100     OPENSSL_free(pdhctx);
 101 }
 102
 103 static void *dh_dupctx(void *vpdhctx)
 104 {
 105     PROV_DH_CTX *srcctx = (PROV_DH_CTX *)vpdhctx;
 106     PROV_DH_CTX *dstctx;
 107
 108     dstctx = OPENSSL_zalloc(sizeof(*srcctx));
 109
 110     *dstctx = *srcctx;
 111     if (dstctx->dh != NULL && !DH_up_ref(dstctx->dh)) {
 112         OPENSSL_free(dstctx);
 113         return NULL;
 114     }
 115
 116     if (dstctx->dhpeer != NULL && !DH_up_ref(dstctx->dhpeer)) {
 117         DH_free(dstctx->dh);
 118         OPENSSL_free(dstctx);
 119         return NULL;
 120     }
 121
 122     return dstctx;
 123 }
 124
 125 static int dh_set_params(void *vpdhctx, const OSSL_PARAM params[])
 126 {
 127     PROV_DH_CTX *pdhctx = (PROV_DH_CTX *)vpdhctx;
 128     const OSSL_PARAM *p;
 129     int pad;
 130
 131     if (pdhctx == NULL || params == NULL)
 132         return 0;
 133
 134     p = OSSL_PARAM_locate_const(params, OSSL_EXCHANGE_PARAM_PAD);
 135     if (p == NULL || !OSSL_PARAM_get_int(p, &pad))
 136         return 0;
 137
 138     pdhctx->pad = pad;
 139
 140     return 1;
 141 }
 142
 143 const OSSL_DISPATCH dh_keyexch_functions[] = {
 144     { OSSL_FUNC_KEYEXCH_NEWCTX, (void (*)(void))dh_newctx },
 145     { OSSL_FUNC_KEYEXCH_INIT, (void (*)(void))dh_init },
 146     { OSSL_FUNC_KEYEXCH_DERIVE, (void (*)(void))dh_derive },
 147     { OSSL_FUNC_KEYEXCH_SET_PEER, (void (*)(void))dh_set_peer },
 148     { OSSL_FUNC_KEYEXCH_FREECTX, (void (*)(void))dh_freectx },
 149     { OSSL_FUNC_KEYEXCH_DUPCTX, (void (*)(void))dh_dupctx },
 150     { OSSL_FUNC_KEYEXCH_SET_PARAMS, (void (*)(void))dh_set_params },
 151     { 0, NULL }
 152 };