providers/implementations/kdfs/sshkdf.c

   1 /*
   2  * Copyright 2018-2023 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         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 void *kdf_sshkdf_dup(void *vctx)
  90 {
  91     const KDF_SSHKDF *src = (const KDF_SSHKDF *)vctx;
  92     KDF_SSHKDF *dest;
  93
  94     dest = kdf_sshkdf_new(src->provctx);
  95     if (dest != NULL) {
  96         if (!ossl_prov_memdup(src->key, src->key_len,
  97                               &dest->key, &dest->key_len)
  98                 || !ossl_prov_memdup(src->xcghash, src->xcghash_len,
  99                                      &dest->xcghash , &dest->xcghash_len)
 100                 || !ossl_prov_memdup(src->session_id, src->session_id_len,
 101                                      &dest->session_id , &dest->session_id_len)
 102                 || !ossl_prov_digest_copy(&dest->digest, &src->digest))
 103             goto err;
 104         dest->type = src->type;
 105     }
 106     return dest;
 107
 108  err:
 109     kdf_sshkdf_free(dest);
 110     return NULL;
 111 }
 112
 113 static int sshkdf_set_membuf(unsigned char **dst, size_t *dst_len,
 114                              const OSSL_PARAM *p)
 115 {
 116     OPENSSL_clear_free(*dst, *dst_len);
 117     *dst = NULL;
 118     *dst_len = 0;
 119     return OSSL_PARAM_get_octet_string(p, (void **)dst, 0, dst_len);
 120 }
 121
 122 static int kdf_sshkdf_derive(void *vctx, unsigned char *key, size_t keylen,
 123                              const OSSL_PARAM params[])
 124 {
 125     KDF_SSHKDF *ctx = (KDF_SSHKDF *)vctx;
 126     const EVP_MD *md;
 127
 128     if (!ossl_prov_is_running() || !kdf_sshkdf_set_ctx_params(ctx, params))
 129         return 0;
 130
 131     md = ossl_prov_digest_md(&ctx->digest);
 132     if (md == NULL) {
 133         ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_MESSAGE_DIGEST);
 134         return 0;
 135     }
 136     if (ctx->key == NULL) {
 137         ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_KEY);
 138         return 0;
 139     }
 140     if (ctx->xcghash == NULL) {
 141         ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_XCGHASH);
 142         return 0;
 143     }
 144     if (ctx->session_id == NULL) {
 145         ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_SESSION_ID);
 146         return 0;
 147     }
 148     if (ctx->type == 0) {
 149         ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_TYPE);
 150         return 0;
 151     }
 152     return SSHKDF(md, ctx->key, ctx->key_len,
 153                   ctx->xcghash, ctx->xcghash_len,
 154                   ctx->session_id, ctx->session_id_len,
 155                   ctx->type, key, keylen);
 156 }
 157
 158 static int kdf_sshkdf_set_ctx_params(void *vctx, const OSSL_PARAM params[])
 159 {
 160     const OSSL_PARAM *p;
 161     KDF_SSHKDF *ctx = vctx;
 162     OSSL_LIB_CTX *provctx = PROV_LIBCTX_OF(ctx->provctx);
 163
 164     if (params == NULL)
 165         return 1;
 166
 167     if (!ossl_prov_digest_load_from_params(&ctx->digest, params, provctx))
 168         return 0;
 169
 170     if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_KEY)) != NULL)
 171         if (!sshkdf_set_membuf(&ctx->key, &ctx->key_len, p))
 172             return 0;
 173
 174     if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_SSHKDF_XCGHASH))
 175         != NULL)
 176         if (!sshkdf_set_membuf(&ctx->xcghash, &ctx->xcghash_len, p))
 177             return 0;
 178
 179     if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_SSHKDF_SESSION_ID))
 180         != NULL)
 181         if (!sshkdf_set_membuf(&ctx->session_id, &ctx->session_id_len, p))
 182             return 0;
 183
 184     if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_SSHKDF_TYPE))
 185         != NULL) {
 186         const char *kdftype;
 187
 188         if (!OSSL_PARAM_get_utf8_string_ptr(p, &kdftype))
 189             return 0;
 190         /* Expect one character (byte in this case) */
 191         if (kdftype == NULL || p->data_size != 1)
 192             return 0;
 193         if (kdftype[0] < 65 || kdftype[0] > 70) {
 194             ERR_raise(ERR_LIB_PROV, PROV_R_VALUE_ERROR);
 195             return 0;
 196         }
 197         ctx->type = kdftype[0];
 198     }
 199     return 1;
 200 }
 201
 202 static const OSSL_PARAM *kdf_sshkdf_settable_ctx_params(ossl_unused void *ctx,
 203                                                         ossl_unused void *p_ctx)
 204 {
 205     static const OSSL_PARAM known_settable_ctx_params[] = {
 206         OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_PROPERTIES, NULL, 0),
 207         OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_DIGEST, NULL, 0),
 208         OSSL_PARAM_octet_string(OSSL_KDF_PARAM_KEY, NULL, 0),
 209         OSSL_PARAM_octet_string(OSSL_KDF_PARAM_SSHKDF_XCGHASH, NULL, 0),
 210         OSSL_PARAM_octet_string(OSSL_KDF_PARAM_SSHKDF_SESSION_ID, NULL, 0),
 211         OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_SSHKDF_TYPE, NULL, 0),
 212         OSSL_PARAM_END
 213     };
 214     return known_settable_ctx_params;
 215 }
 216
 217 static int kdf_sshkdf_get_ctx_params(void *vctx, OSSL_PARAM params[])
 218 {
 219     OSSL_PARAM *p;
 220
 221     if ((p = OSSL_PARAM_locate(params, OSSL_KDF_PARAM_SIZE)) != NULL)
 222         return OSSL_PARAM_set_size_t(p, SIZE_MAX);
 223     return -2;
 224 }
 225
 226 static const OSSL_PARAM *kdf_sshkdf_gettable_ctx_params(ossl_unused void *ctx,
 227                                                         ossl_unused void *p_ctx)
 228 {
 229     static const OSSL_PARAM known_gettable_ctx_params[] = {
 230         OSSL_PARAM_size_t(OSSL_KDF_PARAM_SIZE, NULL),
 231         OSSL_PARAM_END
 232     };
 233     return known_gettable_ctx_params;
 234 }
 235
 236 const OSSL_DISPATCH ossl_kdf_sshkdf_functions[] = {
 237     { OSSL_FUNC_KDF_NEWCTX, (void(*)(void))kdf_sshkdf_new },
 238     { OSSL_FUNC_KDF_DUPCTX, (void(*)(void))kdf_sshkdf_dup },
 239     { OSSL_FUNC_KDF_FREECTX, (void(*)(void))kdf_sshkdf_free },
 240     { OSSL_FUNC_KDF_RESET, (void(*)(void))kdf_sshkdf_reset },
 241     { OSSL_FUNC_KDF_DERIVE, (void(*)(void))kdf_sshkdf_derive },
 242     { OSSL_FUNC_KDF_SETTABLE_CTX_PARAMS,
 243       (void(*)(void))kdf_sshkdf_settable_ctx_params },
 244     { OSSL_FUNC_KDF_SET_CTX_PARAMS, (void(*)(void))kdf_sshkdf_set_ctx_params },
 245     { OSSL_FUNC_KDF_GETTABLE_CTX_PARAMS,
 246       (void(*)(void))kdf_sshkdf_gettable_ctx_params },
 247     { OSSL_FUNC_KDF_GET_CTX_PARAMS, (void(*)(void))kdf_sshkdf_get_ctx_params },
 248     OSSL_DISPATCH_END
 249 };
 250
 251 static int SSHKDF(const EVP_MD *evp_md,
 252                   const unsigned char *key, size_t key_len,
 253                   const unsigned char *xcghash, size_t xcghash_len,
 254                   const unsigned char *session_id, size_t session_id_len,
 255                   char type, unsigned char *okey, size_t okey_len)
 256 {
 257     EVP_MD_CTX *md = NULL;
 258     unsigned char digest[EVP_MAX_MD_SIZE];
 259     unsigned int dsize = 0;
 260     size_t cursize = 0;
 261     int ret = 0;
 262
 263     md = EVP_MD_CTX_new();
 264     if (md == NULL)
 265         return 0;
 266
 267     if (!EVP_DigestInit_ex(md, evp_md, NULL))
 268         goto out;
 269
 270     if (!EVP_DigestUpdate(md, key, key_len))
 271         goto out;
 272
 273     if (!EVP_DigestUpdate(md, xcghash, xcghash_len))
 274         goto out;
 275
 276     if (!EVP_DigestUpdate(md, &type, 1))
 277         goto out;
 278
 279     if (!EVP_DigestUpdate(md, session_id, session_id_len))
 280         goto out;
 281
 282     if (!EVP_DigestFinal_ex(md, digest, &dsize))
 283         goto out;
 284
 285     if (okey_len < dsize) {
 286         memcpy(okey, digest, okey_len);
 287         ret = 1;
 288         goto out;
 289     }
 290
 291     memcpy(okey, digest, dsize);
 292
 293     for (cursize = dsize; cursize < okey_len; cursize += dsize) {
 294
 295         if (!EVP_DigestInit_ex(md, evp_md, NULL))
 296             goto out;
 297
 298         if (!EVP_DigestUpdate(md, key, key_len))
 299             goto out;
 300
 301         if (!EVP_DigestUpdate(md, xcghash, xcghash_len))
 302             goto out;
 303
 304         if (!EVP_DigestUpdate(md, okey, cursize))
 305             goto out;
 306
 307         if (!EVP_DigestFinal_ex(md, digest, &dsize))
 308             goto out;
 309
 310         if (okey_len < cursize + dsize) {
 311             memcpy(okey + cursize, digest, okey_len - cursize);
 312             ret = 1;
 313             goto out;
 314         }
 315
 316         memcpy(okey + cursize, digest, dsize);
 317     }
 318
 319     ret = 1;
 320
 321 out:
 322     EVP_MD_CTX_free(md);
 323     OPENSSL_cleanse(digest, EVP_MAX_MD_SIZE);
 324     return ret;
 325 }
 326