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