providers/implementations/kdfs/sshkdf.c

   1 /*
   2  * Copyright 2018-2022 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 <stdlib.h>
  11 #include <stdarg.h>
  12 #include <string.h>
  13 #include <openssl/evp.h>
  14 #include <openssl/kdf.h>
  15 #include <openssl/core_names.h>
  16 #include <openssl/proverr.h>
  17 #include "internal/cryptlib.h"
  18 #include "internal/numbers.h"
  19 #include "crypto/evp.h"
  20 #include "prov/provider_ctx.h"
  21 #include "prov/providercommon.h"
  22 #include "prov/implementations.h"
  23 #include "prov/provider_util.h"
  24
  25 /* See RFC 4253, Section 7.2 */
  26 static OSSL_FUNC_kdf_newctx_fn kdf_sshkdf_new;
  27 static OSSL_FUNC_kdf_dupctx_fn kdf_sshkdf_dup;
  28 static OSSL_FUNC_kdf_freectx_fn kdf_sshkdf_free;
  29 static OSSL_FUNC_kdf_reset_fn kdf_sshkdf_reset;
  30 static OSSL_FUNC_kdf_derive_fn kdf_sshkdf_derive;
  31 static OSSL_FUNC_kdf_settable_ctx_params_fn kdf_sshkdf_settable_ctx_params;
  32 static OSSL_FUNC_kdf_set_ctx_params_fn kdf_sshkdf_set_ctx_params;
  33 static OSSL_FUNC_kdf_gettable_ctx_params_fn kdf_sshkdf_gettable_ctx_params;
  34 static OSSL_FUNC_kdf_get_ctx_params_fn kdf_sshkdf_get_ctx_params;
  35
  36 static int SSHKDF(const EVP_MD *evp_md,
  37                   const unsigned char *key, size_t key_len,
  38                   const unsigned char *xcghash, size_t xcghash_len,
  39                   const unsigned char *session_id, size_t session_id_len,
  40                   char type, unsigned char *okey, size_t okey_len);
  41
  42 typedef struct {
  43     void *provctx;
  44     PROV_DIGEST digest;
  45     unsigned char *key; /* K */
  46     size_t key_len;
  47     unsigned char *xcghash; /* H */
  48     size_t xcghash_len;
  49     char type; /* X */
  50     unsigned char *session_id;
  51     size_t session_id_len;
  52 } KDF_SSHKDF;
  53
  54 static void *kdf_sshkdf_new(void *provctx)
  55 {
  56     KDF_SSHKDF *ctx;
  57
  58     if (!ossl_prov_is_running())
  59         return NULL;
  60
  61     if ((ctx = OPENSSL_zalloc(sizeof(*ctx))) == NULL)
  62         ERR_raise(ERR_LIB_PROV, ERR_R_MALLOC_FAILURE);
  63     else
  64         ctx->provctx = provctx;
  65     return ctx;
  66 }
  67
  68 static void kdf_sshkdf_free(void *vctx)
  69 {
  70     KDF_SSHKDF *ctx = (KDF_SSHKDF *)vctx;
  71
  72     if (ctx != NULL) {
  73         kdf_sshkdf_reset(ctx);
  74         OPENSSL_free(ctx);
  75     }
  76 }
  77
  78 static void kdf_sshkdf_reset(void *vctx)
  79 {
  80     KDF_SSHKDF *ctx = (KDF_SSHKDF *)vctx;
  81     void *provctx = ctx->provctx;
  82
  83     ossl_prov_digest_reset(&ctx->digest);
  84     OPENSSL_clear_free(ctx->key, ctx->key_len);
  85     OPENSSL_clear_free(ctx->xcghash, ctx->xcghash_len);
  86     OPENSSL_clear_free(ctx->session_id, ctx->session_id_len);
  87     memset(ctx, 0, sizeof(*ctx));
  88     ctx->provctx = provctx;
  89 }
  90
  91 static void *kdf_sshkdf_dup(void *vctx)
  92 {
  93     const KDF_SSHKDF *src = (const KDF_SSHKDF *)vctx;
  94     KDF_SSHKDF *dest;
  95
  96     dest = kdf_sshkdf_new(src->provctx);
  97     if (dest != NULL) {
  98         if (!ossl_prov_memdup(src->key, src->key_len,
  99                               &dest->key, &dest->key_len)
 100                 || !ossl_prov_memdup(src->xcghash, src->xcghash_len,
 101                                      &dest->xcghash , &dest->xcghash_len)
 102                 || !ossl_prov_memdup(src->session_id, src->session_id_len,
 103                                      &dest->session_id , &dest->session_id_len)
 104                 || !ossl_prov_digest_copy(&dest->digest, &src->digest))
 105             goto err;
 106         dest->type = src->type;
 107     }
 108     return dest;
 109
 110  err:
 111     kdf_sshkdf_free(dest);
 112     return NULL;
 113 }
 114
 115 static int sshkdf_set_membuf(unsigned char **dst, size_t *dst_len,
 116                              const OSSL_PARAM *p)
 117 {
 118     OPENSSL_clear_free(*dst, *dst_len);
 119     *dst = NULL;
 120     *dst_len = 0;
 121     return OSSL_PARAM_get_octet_string(p, (void **)dst, 0, dst_len);
 122 }
 123
 124 static int kdf_sshkdf_derive(void *vctx, unsigned char *key, size_t keylen,
 125                              const OSSL_PARAM params[])
 126 {
 127     KDF_SSHKDF *ctx = (KDF_SSHKDF *)vctx;
 128     const EVP_MD *md;
 129
 130     if (!ossl_prov_is_running() || !kdf_sshkdf_set_ctx_params(ctx, params))
 131         return 0;
 132
 133     md = ossl_prov_digest_md(&ctx->digest);
 134     if (md == NULL) {
 135         ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_MESSAGE_DIGEST);
 136         return 0;
 137     }
 138     if (ctx->key == NULL) {
 139         ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_KEY);
 140         return 0;
 141     }
 142     if (ctx->xcghash == NULL) {
 143         ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_XCGHASH);
 144         return 0;
 145     }
 146     if (ctx->session_id == NULL) {
 147         ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_SESSION_ID);
 148         return 0;
 149     }
 150     if (ctx->type == 0) {
 151         ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_TYPE);
 152         return 0;
 153     }
 154     return SSHKDF(md, ctx->key, ctx->key_len,
 155                   ctx->xcghash, ctx->xcghash_len,
 156                   ctx->session_id, ctx->session_id_len,
 157                   ctx->type, key, keylen);
 158 }
 159
 160 static int kdf_sshkdf_set_ctx_params(void *vctx, const OSSL_PARAM params[])
 161 {
 162     const OSSL_PARAM *p;
 163     KDF_SSHKDF *ctx = vctx;
 164     OSSL_LIB_CTX *provctx = PROV_LIBCTX_OF(ctx->provctx);
 165
 166     if (params == NULL)
 167         return 1;
 168
 169     if (!ossl_prov_digest_load_from_params(&ctx->digest, params, provctx))
 170         return 0;
 171
 172     if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_KEY)) != NULL)
 173         if (!sshkdf_set_membuf(&ctx->key, &ctx->key_len, p))
 174             return 0;
 175
 176     if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_SSHKDF_XCGHASH))
 177         != NULL)
 178         if (!sshkdf_set_membuf(&ctx->xcghash, &ctx->xcghash_len, p))
 179             return 0;
 180
 181     if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_SSHKDF_SESSION_ID))
 182         != NULL)
 183         if (!sshkdf_set_membuf(&ctx->session_id, &ctx->session_id_len, p))
 184             return 0;
 185
 186     if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_SSHKDF_TYPE))
 187         != NULL) {
 188         const char *kdftype;
 189
 190         if (!OSSL_PARAM_get_utf8_string_ptr(p, &kdftype))
 191             return 0;
 192         /* Expect one character (byte in this case) */
 193         if (kdftype == NULL || p->data_size != 1)
 194             return 0;
 195         if (kdftype[0] < 65 || kdftype[0] > 70) {
 196             ERR_raise(ERR_LIB_PROV, PROV_R_VALUE_ERROR);
 197             return 0;
 198         }
 199         ctx->type = kdftype[0];
 200     }
 201     return 1;
 202 }
 203
 204 static const OSSL_PARAM *kdf_sshkdf_settable_ctx_params(ossl_unused void *ctx,
 205                                                         ossl_unused void *p_ctx)
 206 {
 207     static const OSSL_PARAM known_settable_ctx_params[] = {
 208         OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_PROPERTIES, NULL, 0),
 209         OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_DIGEST, NULL, 0),
 210         OSSL_PARAM_octet_string(OSSL_KDF_PARAM_KEY, NULL, 0),
 211         OSSL_PARAM_octet_string(OSSL_KDF_PARAM_SSHKDF_XCGHASH, NULL, 0),
 212         OSSL_PARAM_octet_string(OSSL_KDF_PARAM_SSHKDF_SESSION_ID, NULL, 0),
 213         OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_SSHKDF_TYPE, NULL, 0),
 214         OSSL_PARAM_END
 215     };
 216     return known_settable_ctx_params;
 217 }
 218
 219 static int kdf_sshkdf_get_ctx_params(void *vctx, OSSL_PARAM params[])
 220 {
 221     OSSL_PARAM *p;
 222
 223     if ((p = OSSL_PARAM_locate(params, OSSL_KDF_PARAM_SIZE)) != NULL)
 224         return OSSL_PARAM_set_size_t(p, SIZE_MAX);
 225     return -2;
 226 }
 227
 228 static const OSSL_PARAM *kdf_sshkdf_gettable_ctx_params(ossl_unused void *ctx,
 229                                                         ossl_unused void *p_ctx)
 230 {
 231     static const OSSL_PARAM known_gettable_ctx_params[] = {
 232         OSSL_PARAM_size_t(OSSL_KDF_PARAM_SIZE, NULL),
 233         OSSL_PARAM_END
 234     };
 235     return known_gettable_ctx_params;
 236 }
 237
 238 const OSSL_DISPATCH ossl_kdf_sshkdf_functions[] = {
 239     { OSSL_FUNC_KDF_NEWCTX, (void(*)(void))kdf_sshkdf_new },
 240     { OSSL_FUNC_KDF_DUPCTX, (void(*)(void))kdf_sshkdf_dup },
 241     { OSSL_FUNC_KDF_FREECTX, (void(*)(void))kdf_sshkdf_free },
 242     { OSSL_FUNC_KDF_RESET, (void(*)(void))kdf_sshkdf_reset },
 243     { OSSL_FUNC_KDF_DERIVE, (void(*)(void))kdf_sshkdf_derive },
 244     { OSSL_FUNC_KDF_SETTABLE_CTX_PARAMS,
 245       (void(*)(void))kdf_sshkdf_settable_ctx_params },
 246     { OSSL_FUNC_KDF_SET_CTX_PARAMS, (void(*)(void))kdf_sshkdf_set_ctx_params },
 247     { OSSL_FUNC_KDF_GETTABLE_CTX_PARAMS,
 248       (void(*)(void))kdf_sshkdf_gettable_ctx_params },
 249     { OSSL_FUNC_KDF_GET_CTX_PARAMS, (void(*)(void))kdf_sshkdf_get_ctx_params },
 250     { 0, NULL }
 251 };
 252
 253 static int SSHKDF(const EVP_MD *evp_md,
 254                   const unsigned char *key, size_t key_len,
 255                   const unsigned char *xcghash, size_t xcghash_len,
 256                   const unsigned char *session_id, size_t session_id_len,
 257                   char type, unsigned char *okey, size_t okey_len)
 258 {
 259     EVP_MD_CTX *md = NULL;
 260     unsigned char digest[EVP_MAX_MD_SIZE];
 261     unsigned int dsize = 0;
 262     size_t cursize = 0;
 263     int ret = 0;
 264
 265     md = EVP_MD_CTX_new();
 266     if (md == NULL)
 267         return 0;
 268
 269     if (!EVP_DigestInit_ex(md, evp_md, NULL))
 270         goto out;
 271
 272     if (!EVP_DigestUpdate(md, key, key_len))
 273         goto out;
 274
 275     if (!EVP_DigestUpdate(md, xcghash, xcghash_len))
 276         goto out;
 277
 278     if (!EVP_DigestUpdate(md, &type, 1))
 279         goto out;
 280
 281     if (!EVP_DigestUpdate(md, session_id, session_id_len))
 282         goto out;
 283
 284     if (!EVP_DigestFinal_ex(md, digest, &dsize))
 285         goto out;
 286
 287     if (okey_len < dsize) {
 288         memcpy(okey, digest, okey_len);
 289         ret = 1;
 290         goto out;
 291     }
 292
 293     memcpy(okey, digest, dsize);
 294
 295     for (cursize = dsize; cursize < okey_len; cursize += dsize) {
 296
 297         if (!EVP_DigestInit_ex(md, evp_md, NULL))
 298             goto out;
 299
 300         if (!EVP_DigestUpdate(md, key, key_len))
 301             goto out;
 302
 303         if (!EVP_DigestUpdate(md, xcghash, xcghash_len))
 304             goto out;
 305
 306         if (!EVP_DigestUpdate(md, okey, cursize))
 307             goto out;
 308
 309         if (!EVP_DigestFinal_ex(md, digest, &dsize))
 310             goto out;
 311
 312         if (okey_len < cursize + dsize) {
 313             memcpy(okey + cursize, digest, okey_len - cursize);
 314             ret = 1;
 315             goto out;
 316         }
 317
 318         memcpy(okey + cursize, digest, dsize);
 319     }
 320
 321     ret = 1;
 322
 323 out:
 324     EVP_MD_CTX_free(md);
 325     OPENSSL_cleanse(digest, EVP_MAX_MD_SIZE);
 326     return ret;
 327 }
 328