providers/implementations/kdfs/sshkdf.c

   1 /*
   2  * Copyright 2018-2020 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 "internal/cryptlib.h"
  17 #include "internal/numbers.h"
  18 #include "crypto/evp.h"
  19 #include "prov/provider_ctx.h"
  20 #include "prov/providercommon.h"
  21 #include "prov/providercommonerr.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_freectx_fn kdf_sshkdf_free;
  28 static OSSL_FUNC_kdf_reset_fn kdf_sshkdf_reset;
  29 static OSSL_FUNC_kdf_derive_fn kdf_sshkdf_derive;
  30 static OSSL_FUNC_kdf_settable_ctx_params_fn kdf_sshkdf_settable_ctx_params;
  31 static OSSL_FUNC_kdf_set_ctx_params_fn kdf_sshkdf_set_ctx_params;
  32 static OSSL_FUNC_kdf_gettable_ctx_params_fn kdf_sshkdf_gettable_ctx_params;
  33 static OSSL_FUNC_kdf_get_ctx_params_fn kdf_sshkdf_get_ctx_params;
  34
  35 static int SSHKDF(const EVP_MD *evp_md,
  36                   const unsigned char *key, size_t key_len,
  37                   const unsigned char *xcghash, size_t xcghash_len,
  38                   const unsigned char *session_id, size_t session_id_len,
  39                   char type, unsigned char *okey, size_t okey_len);
  40
  41 typedef struct {
  42     void *provctx;
  43     PROV_DIGEST digest;
  44     unsigned char *key; /* K */
  45     size_t key_len;
  46     unsigned char *xcghash; /* H */
  47     size_t xcghash_len;
  48     char type; /* X */
  49     unsigned char *session_id;
  50     size_t session_id_len;
  51 } KDF_SSHKDF;
  52
  53 static void *kdf_sshkdf_new(void *provctx)
  54 {
  55     KDF_SSHKDF *ctx;
  56
  57     if (!ossl_prov_is_running())
  58         return NULL;
  59
  60     if ((ctx = OPENSSL_zalloc(sizeof(*ctx))) == NULL)
  61         ERR_raise(ERR_LIB_PROV, ERR_R_MALLOC_FAILURE);
  62     ctx->provctx = provctx;
  63     return ctx;
  64 }
  65
  66 static void kdf_sshkdf_free(void *vctx)
  67 {
  68     KDF_SSHKDF *ctx = (KDF_SSHKDF *)vctx;
  69
  70     if (ctx != NULL) {
  71         kdf_sshkdf_reset(ctx);
  72         OPENSSL_free(ctx);
  73     }
  74 }
  75
  76 static void kdf_sshkdf_reset(void *vctx)
  77 {
  78     KDF_SSHKDF *ctx = (KDF_SSHKDF *)vctx;
  79     void *provctx = ctx->provctx;
  80
  81     ossl_prov_digest_reset(&ctx->digest);
  82     OPENSSL_clear_free(ctx->key, ctx->key_len);
  83     OPENSSL_clear_free(ctx->xcghash, ctx->xcghash_len);
  84     OPENSSL_clear_free(ctx->session_id, ctx->session_id_len);
  85     memset(ctx, 0, sizeof(*ctx));
  86     ctx->provctx = provctx;
  87 }
  88
  89 static int sshkdf_set_membuf(unsigned char **dst, size_t *dst_len,
  90                              const OSSL_PARAM *p)
  91 {
  92     OPENSSL_clear_free(*dst, *dst_len);
  93     *dst = NULL;
  94     return OSSL_PARAM_get_octet_string(p, (void **)dst, 0, dst_len);
  95 }
  96
  97 static int kdf_sshkdf_derive(void *vctx, unsigned char *key,
  98                              size_t keylen)
  99 {
 100     KDF_SSHKDF *ctx = (KDF_SSHKDF *)vctx;
 101     const EVP_MD *md;
 102
 103     if (!ossl_prov_is_running())
 104         return 0;
 105
 106     md = ossl_prov_digest_md(&ctx->digest);
 107     if (md == NULL) {
 108         ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_MESSAGE_DIGEST);
 109         return 0;
 110     }
 111     if (ctx->key == NULL) {
 112         ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_KEY);
 113         return 0;
 114     }
 115     if (ctx->xcghash == NULL) {
 116         ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_XCGHASH);
 117         return 0;
 118     }
 119     if (ctx->session_id == NULL) {
 120         ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_SESSION_ID);
 121         return 0;
 122     }
 123     if (ctx->type == 0) {
 124         ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_TYPE);
 125         return 0;
 126     }
 127     return SSHKDF(md, ctx->key, ctx->key_len,
 128                   ctx->xcghash, ctx->xcghash_len,
 129                   ctx->session_id, ctx->session_id_len,
 130                   ctx->type, key, keylen);
 131 }
 132
 133 static int kdf_sshkdf_set_ctx_params(void *vctx, const OSSL_PARAM params[])
 134 {
 135     const OSSL_PARAM *p;
 136     KDF_SSHKDF *ctx = vctx;
 137     OSSL_LIB_CTX *provctx = PROV_LIBCTX_OF(ctx->provctx);
 138
 139     if (!ossl_prov_digest_load_from_params(&ctx->digest, params, provctx))
 140         return 0;
 141
 142     if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_KEY)) != NULL)
 143         if (!sshkdf_set_membuf(&ctx->key, &ctx->key_len, p))
 144             return 0;
 145
 146     if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_SSHKDF_XCGHASH))
 147         != NULL)
 148         if (!sshkdf_set_membuf(&ctx->xcghash, &ctx->xcghash_len, p))
 149             return 0;
 150
 151     if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_SSHKDF_SESSION_ID))
 152         != NULL)
 153         if (!sshkdf_set_membuf(&ctx->session_id, &ctx->session_id_len, p))
 154             return 0;
 155
 156     if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_SSHKDF_TYPE))
 157         != NULL) {
 158         const char *kdftype;
 159
 160         if (!OSSL_PARAM_get_utf8_string_ptr(p, &kdftype))
 161             return 0;
 162         if (kdftype == NULL || kdftype[0] == '\0' || kdftype[1] != '\0')
 163             return 0;
 164         if (kdftype[0] < 65 || kdftype[0] > 70) {
 165             ERR_raise(ERR_LIB_PROV, PROV_R_VALUE_ERROR);
 166             return 0;
 167         }
 168         ctx->type = kdftype[0];
 169     }
 170     return 1;
 171 }
 172
 173 static const OSSL_PARAM *kdf_sshkdf_settable_ctx_params(ossl_unused void *p_ctx)
 174 {
 175     static const OSSL_PARAM known_settable_ctx_params[] = {
 176         OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_PROPERTIES, NULL, 0),
 177         OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_DIGEST, NULL, 0),
 178         OSSL_PARAM_octet_string(OSSL_KDF_PARAM_KEY, NULL, 0),
 179         OSSL_PARAM_octet_string(OSSL_KDF_PARAM_SSHKDF_XCGHASH, NULL, 0),
 180         OSSL_PARAM_octet_string(OSSL_KDF_PARAM_SSHKDF_SESSION_ID, NULL, 0),
 181         OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_SSHKDF_TYPE, NULL, 0),
 182         OSSL_PARAM_END
 183     };
 184     return known_settable_ctx_params;
 185 }
 186
 187 static int kdf_sshkdf_get_ctx_params(void *vctx, OSSL_PARAM params[])
 188 {
 189     OSSL_PARAM *p;
 190
 191     if ((p = OSSL_PARAM_locate(params, OSSL_KDF_PARAM_SIZE)) != NULL)
 192         return OSSL_PARAM_set_size_t(p, SIZE_MAX);
 193     return -2;
 194 }
 195
 196 static const OSSL_PARAM *kdf_sshkdf_gettable_ctx_params(ossl_unused void *p_ctx)
 197 {
 198     static const OSSL_PARAM known_gettable_ctx_params[] = {
 199         OSSL_PARAM_size_t(OSSL_KDF_PARAM_SIZE, NULL),
 200         OSSL_PARAM_END
 201     };
 202     return known_gettable_ctx_params;
 203 }
 204
 205 const OSSL_DISPATCH ossl_kdf_sshkdf_functions[] = {
 206     { OSSL_FUNC_KDF_NEWCTX, (void(*)(void))kdf_sshkdf_new },
 207     { OSSL_FUNC_KDF_FREECTX, (void(*)(void))kdf_sshkdf_free },
 208     { OSSL_FUNC_KDF_RESET, (void(*)(void))kdf_sshkdf_reset },
 209     { OSSL_FUNC_KDF_DERIVE, (void(*)(void))kdf_sshkdf_derive },
 210     { OSSL_FUNC_KDF_SETTABLE_CTX_PARAMS,
 211       (void(*)(void))kdf_sshkdf_settable_ctx_params },
 212     { OSSL_FUNC_KDF_SET_CTX_PARAMS, (void(*)(void))kdf_sshkdf_set_ctx_params },
 213     { OSSL_FUNC_KDF_GETTABLE_CTX_PARAMS,
 214       (void(*)(void))kdf_sshkdf_gettable_ctx_params },
 215     { OSSL_FUNC_KDF_GET_CTX_PARAMS, (void(*)(void))kdf_sshkdf_get_ctx_params },
 216     { 0, NULL }
 217 };
 218
 219 static int SSHKDF(const EVP_MD *evp_md,
 220                   const unsigned char *key, size_t key_len,
 221                   const unsigned char *xcghash, size_t xcghash_len,
 222                   const unsigned char *session_id, size_t session_id_len,
 223                   char type, unsigned char *okey, size_t okey_len)
 224 {
 225     EVP_MD_CTX *md = NULL;
 226     unsigned char digest[EVP_MAX_MD_SIZE];
 227     unsigned int dsize = 0;
 228     size_t cursize = 0;
 229     int ret = 0;
 230
 231     md = EVP_MD_CTX_new();
 232     if (md == NULL)
 233         return 0;
 234
 235     if (!EVP_DigestInit_ex(md, evp_md, NULL))
 236         goto out;
 237
 238     if (!EVP_DigestUpdate(md, key, key_len))
 239         goto out;
 240
 241     if (!EVP_DigestUpdate(md, xcghash, xcghash_len))
 242         goto out;
 243
 244     if (!EVP_DigestUpdate(md, &type, 1))
 245         goto out;
 246
 247     if (!EVP_DigestUpdate(md, session_id, session_id_len))
 248         goto out;
 249
 250     if (!EVP_DigestFinal_ex(md, digest, &dsize))
 251         goto out;
 252
 253     if (okey_len < dsize) {
 254         memcpy(okey, digest, okey_len);
 255         ret = 1;
 256         goto out;
 257     }
 258
 259     memcpy(okey, digest, dsize);
 260
 261     for (cursize = dsize; cursize < okey_len; cursize += dsize) {
 262
 263         if (!EVP_DigestInit_ex(md, evp_md, NULL))
 264             goto out;
 265
 266         if (!EVP_DigestUpdate(md, key, key_len))
 267             goto out;
 268
 269         if (!EVP_DigestUpdate(md, xcghash, xcghash_len))
 270             goto out;
 271
 272         if (!EVP_DigestUpdate(md, okey, cursize))
 273             goto out;
 274
 275         if (!EVP_DigestFinal_ex(md, digest, &dsize))
 276             goto out;
 277
 278         if (okey_len < cursize + dsize) {
 279             memcpy(okey + cursize, digest, okey_len - cursize);
 280             ret = 1;
 281             goto out;
 282         }
 283
 284         memcpy(okey + cursize, digest, dsize);
 285     }
 286
 287     ret = 1;
 288
 289 out:
 290     EVP_MD_CTX_free(md);
 291     OPENSSL_cleanse(digest, EVP_MAX_MD_SIZE);
 292     return ret;
 293 }
 294