providers/default/kdfs/sshkdf.c

   1 /*
   2  * Copyright 2018-2019 The OpenSSL Project Authors. All Rights Reserved.
   3  *
   4  * Licensed under the OpenSSL license (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 "internal/evp_int.h"
  19 #include "internal/provider_ctx.h"
  20 #include "internal/providercommonerr.h"
  21 #include "internal/provider_algs.h"
  22
  23 /* See RFC 4253, Section 7.2 */
  24 static OSSL_OP_kdf_newctx_fn kdf_sshkdf_new;
  25 static OSSL_OP_kdf_freectx_fn kdf_sshkdf_free;
  26 static OSSL_OP_kdf_reset_fn kdf_sshkdf_reset;
  27 static OSSL_OP_kdf_derive_fn kdf_sshkdf_derive;
  28 static OSSL_OP_kdf_settable_ctx_params_fn kdf_sshkdf_settable_ctx_params;
  29 static OSSL_OP_kdf_set_ctx_params_fn kdf_sshkdf_set_ctx_params;
  30 static OSSL_OP_kdf_gettable_ctx_params_fn kdf_sshkdf_gettable_ctx_params;
  31 static OSSL_OP_kdf_get_ctx_params_fn kdf_sshkdf_get_ctx_params;
  32
  33 static int SSHKDF(const EVP_MD *evp_md,
  34                   const unsigned char *key, size_t key_len,
  35                   const unsigned char *xcghash, size_t xcghash_len,
  36                   const unsigned char *session_id, size_t session_id_len,
  37                   char type, unsigned char *okey, size_t okey_len);
  38
  39 typedef struct {
  40     void *provctx;
  41     EVP_MD *md;
  42     unsigned char *key; /* K */
  43     size_t key_len;
  44     unsigned char *xcghash; /* H */
  45     size_t xcghash_len;
  46     char type; /* X */
  47     unsigned char *session_id;
  48     size_t session_id_len;
  49 } KDF_SSHKDF;
  50
  51 static void *kdf_sshkdf_new(void *provctx)
  52 {
  53     KDF_SSHKDF *ctx;
  54
  55     if ((ctx = OPENSSL_zalloc(sizeof(*ctx))) == NULL)
  56         ERR_raise(ERR_LIB_PROV, ERR_R_MALLOC_FAILURE);
  57     ctx->provctx = provctx;
  58     return ctx;
  59 }
  60
  61 static void kdf_sshkdf_free(void *vctx)
  62 {
  63     KDF_SSHKDF *ctx = (KDF_SSHKDF *)vctx;
  64
  65     kdf_sshkdf_reset(ctx);
  66     OPENSSL_free(ctx);
  67 }
  68
  69 static void kdf_sshkdf_reset(void *vctx)
  70 {
  71     KDF_SSHKDF *ctx = (KDF_SSHKDF *)vctx;
  72
  73     EVP_MD_meth_free(ctx->md);
  74     OPENSSL_clear_free(ctx->key, ctx->key_len);
  75     OPENSSL_clear_free(ctx->xcghash, ctx->xcghash_len);
  76     OPENSSL_clear_free(ctx->session_id, ctx->session_id_len);
  77     memset(ctx, 0, sizeof(*ctx));
  78 }
  79
  80 static int sshkdf_set_membuf(unsigned char **dst, size_t *dst_len,
  81                              const OSSL_PARAM *p)
  82 {
  83     OPENSSL_clear_free(*dst, *dst_len);
  84     *dst = NULL;
  85     return OSSL_PARAM_get_octet_string(p, (void **)dst, 0, dst_len);
  86 }
  87
  88 static int kdf_sshkdf_derive(void *vctx, unsigned char *key,
  89                              size_t keylen)
  90 {
  91     KDF_SSHKDF *ctx = (KDF_SSHKDF *)vctx;
  92
  93     if (ctx->md == NULL) {
  94         ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_MESSAGE_DIGEST);
  95         return 0;
  96     }
  97     if (ctx->key == NULL) {
  98         ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_KEY);
  99         return 0;
 100     }
 101     if (ctx->xcghash == NULL) {
 102         ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_XCGHASH);
 103         return 0;
 104     }
 105     if (ctx->session_id == NULL) {
 106         ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_SESSION_ID);
 107         return 0;
 108     }
 109     if (ctx->type == 0) {
 110         ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_TYPE);
 111         return 0;
 112     }
 113     return SSHKDF(ctx->md, ctx->key, ctx->key_len,
 114                   ctx->xcghash, ctx->xcghash_len,
 115                   ctx->session_id, ctx->session_id_len,
 116                   ctx->type, key, keylen);
 117 }
 118
 119 static int kdf_sshkdf_set_ctx_params(void *vctx, const OSSL_PARAM params[])
 120 {
 121     const OSSL_PARAM *p;
 122     KDF_SSHKDF *ctx = vctx;
 123     EVP_MD *md;
 124     int t;
 125     const char *properties = NULL;
 126
 127     /* Grab search properties, this should be before the digest lookup */
 128     if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_PROPERTIES))
 129         != NULL) {
 130         if (p->data_type != OSSL_PARAM_UTF8_STRING)
 131             return 0;
 132         properties = p->data;
 133     }
 134     /* Handle aliasing of digest parameter names */
 135     if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_DIGEST)) != NULL) {
 136         if (p->data_type != OSSL_PARAM_UTF8_STRING)
 137             return 0;
 138         md = EVP_MD_fetch(PROV_LIBRARY_CONTEXT_OF(ctx->provctx), p->data,
 139                           properties);
 140         if (md == NULL) {
 141             ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_DIGEST);
 142             return 0;
 143         }
 144         EVP_MD_meth_free(ctx->md);
 145         ctx->md = md;
 146     }
 147
 148     if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_KEY)) != NULL)
 149         if (!sshkdf_set_membuf(&ctx->key, &ctx->key_len, p))
 150             return 0;
 151
 152     if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_SSHKDF_XCGHASH))
 153         != NULL)
 154         if (!sshkdf_set_membuf(&ctx->xcghash, &ctx->xcghash_len, p))
 155             return 0;
 156
 157     if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_SSHKDF_SESSION_ID))
 158         != NULL)
 159         if (!sshkdf_set_membuf(&ctx->session_id, &ctx->session_id_len, p))
 160             return 0;
 161
 162     if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_SSHKDF_TYPE))
 163         != NULL) {
 164         if (p->data == NULL || p->data_size == 0)
 165             return 0;
 166         t = *(unsigned char *)p->data;
 167         if (t < 65 || t > 70) {
 168             ERR_raise(ERR_LIB_PROV, PROV_R_VALUE_ERROR);
 169             return 0;
 170         }
 171         ctx->type = (char)t;
 172     }
 173     return 1;
 174 }
 175
 176 static const OSSL_PARAM *kdf_sshkdf_settable_ctx_params(void)
 177 {
 178     static const OSSL_PARAM known_settable_ctx_params[] = {
 179         OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_PROPERTIES, NULL, 0),
 180         OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_DIGEST, NULL, 0),
 181         OSSL_PARAM_octet_string(OSSL_KDF_PARAM_KEY, NULL, 0),
 182         OSSL_PARAM_octet_string(OSSL_KDF_PARAM_SSHKDF_XCGHASH, NULL, 0),
 183         OSSL_PARAM_octet_string(OSSL_KDF_PARAM_SSHKDF_SESSION_ID, NULL, 0),
 184         OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_SSHKDF_TYPE, NULL, 0),
 185         OSSL_PARAM_END
 186     };
 187     return known_settable_ctx_params;
 188 }
 189
 190 static int kdf_sshkdf_get_ctx_params(void *vctx, OSSL_PARAM params[])
 191 {
 192     OSSL_PARAM *p;
 193
 194     if ((p = OSSL_PARAM_locate(params, OSSL_KDF_PARAM_SIZE)) != NULL)
 195         return OSSL_PARAM_set_size_t(p, SIZE_MAX);
 196     return -2;
 197 }
 198
 199 static const OSSL_PARAM *kdf_sshkdf_gettable_ctx_params(void)
 200 {
 201     static const OSSL_PARAM known_gettable_ctx_params[] = {
 202         OSSL_PARAM_size_t(OSSL_KDF_PARAM_SIZE, NULL),
 203         OSSL_PARAM_END
 204     };
 205     return known_gettable_ctx_params;
 206 }
 207
 208 const OSSL_DISPATCH kdf_sshkdf_functions[] = {
 209     { OSSL_FUNC_KDF_NEWCTX, (void(*)(void))kdf_sshkdf_new },
 210     { OSSL_FUNC_KDF_FREECTX, (void(*)(void))kdf_sshkdf_free },
 211     { OSSL_FUNC_KDF_RESET, (void(*)(void))kdf_sshkdf_reset },
 212     { OSSL_FUNC_KDF_DERIVE, (void(*)(void))kdf_sshkdf_derive },
 213     { OSSL_FUNC_KDF_SETTABLE_CTX_PARAMS,
 214       (void(*)(void))kdf_sshkdf_settable_ctx_params },
 215     { OSSL_FUNC_KDF_SET_CTX_PARAMS, (void(*)(void))kdf_sshkdf_set_ctx_params },
 216     { OSSL_FUNC_KDF_GETTABLE_CTX_PARAMS,
 217       (void(*)(void))kdf_sshkdf_gettable_ctx_params },
 218     { OSSL_FUNC_KDF_GET_CTX_PARAMS, (void(*)(void))kdf_sshkdf_get_ctx_params },
 219     { 0, NULL }
 220 };
 221
 222 static int SSHKDF(const EVP_MD *evp_md,
 223                   const unsigned char *key, size_t key_len,
 224                   const unsigned char *xcghash, size_t xcghash_len,
 225                   const unsigned char *session_id, size_t session_id_len,
 226                   char type, unsigned char *okey, size_t okey_len)
 227 {
 228     EVP_MD_CTX *md = NULL;
 229     unsigned char digest[EVP_MAX_MD_SIZE];
 230     unsigned int dsize = 0;
 231     size_t cursize = 0;
 232     int ret = 0;
 233
 234     md = EVP_MD_CTX_new();
 235     if (md == NULL)
 236         return 0;
 237
 238     if (!EVP_DigestInit_ex(md, evp_md, NULL))
 239         goto out;
 240
 241     if (!EVP_DigestUpdate(md, key, key_len))
 242         goto out;
 243
 244     if (!EVP_DigestUpdate(md, xcghash, xcghash_len))
 245         goto out;
 246
 247     if (!EVP_DigestUpdate(md, &type, 1))
 248         goto out;
 249
 250     if (!EVP_DigestUpdate(md, session_id, session_id_len))
 251         goto out;
 252
 253     if (!EVP_DigestFinal_ex(md, digest, &dsize))
 254         goto out;
 255
 256     if (okey_len < dsize) {
 257         memcpy(okey, digest, okey_len);
 258         ret = 1;
 259         goto out;
 260     }
 261
 262     memcpy(okey, digest, dsize);
 263
 264     for (cursize = dsize; cursize < okey_len; cursize += dsize) {
 265
 266         if (!EVP_DigestInit_ex(md, evp_md, NULL))
 267             goto out;
 268
 269         if (!EVP_DigestUpdate(md, key, key_len))
 270             goto out;
 271
 272         if (!EVP_DigestUpdate(md, xcghash, xcghash_len))
 273             goto out;
 274
 275         if (!EVP_DigestUpdate(md, okey, cursize))
 276             goto out;
 277
 278         if (!EVP_DigestFinal_ex(md, digest, &dsize))
 279             goto out;
 280
 281         if (okey_len < cursize + dsize) {
 282             memcpy(okey + cursize, digest, okey_len - cursize);
 283             ret = 1;
 284             goto out;
 285         }
 286
 287         memcpy(okey + cursize, digest, dsize);
 288     }
 289
 290     ret = 1;
 291
 292 out:
 293     EVP_MD_CTX_free(md);
 294     OPENSSL_cleanse(digest, EVP_MAX_MD_SIZE);
 295     return ret;
 296 }
 297