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_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 else 63 ctx->provctx = provctx; 64 return ctx; 65 } 66 67 static void kdf_sshkdf_free(void *vctx) 68 { 69 KDF_SSHKDF *ctx = (KDF_SSHKDF *)vctx; 70 71 if (ctx != NULL) { 72 kdf_sshkdf_reset(ctx); 73 OPENSSL_free(ctx); 74 } 75 } 76 77 static void kdf_sshkdf_reset(void *vctx) 78 { 79 KDF_SSHKDF *ctx = (KDF_SSHKDF *)vctx; 80 void *provctx = ctx->provctx; 81 82 ossl_prov_digest_reset(&ctx->digest); 83 OPENSSL_clear_free(ctx->key, ctx->key_len); 84 OPENSSL_clear_free(ctx->xcghash, ctx->xcghash_len); 85 OPENSSL_clear_free(ctx->session_id, ctx->session_id_len); 86 memset(ctx, 0, sizeof(*ctx)); 87 ctx->provctx = provctx; 88 } 89 90 static int sshkdf_set_membuf(unsigned char **dst, size_t *dst_len, 91 const OSSL_PARAM *p) 92 { 93 OPENSSL_clear_free(*dst, *dst_len); 94 *dst = NULL; 95 *dst_len = 0; 96 return OSSL_PARAM_get_octet_string(p, (void **)dst, 0, dst_len); 97 } 98 99 static int kdf_sshkdf_derive(void *vctx, unsigned char *key, size_t keylen, 100 const OSSL_PARAM params[]) 101 { 102 KDF_SSHKDF *ctx = (KDF_SSHKDF *)vctx; 103 const EVP_MD *md; 104 105 if (!ossl_prov_is_running() || !kdf_sshkdf_set_ctx_params(ctx, params)) 106 return 0; 107 108 md = ossl_prov_digest_md(&ctx->digest); 109 if (md == NULL) { 110 ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_MESSAGE_DIGEST); 111 return 0; 112 } 113 if (ctx->key == NULL) { 114 ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_KEY); 115 return 0; 116 } 117 if (ctx->xcghash == NULL) { 118 ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_XCGHASH); 119 return 0; 120 } 121 if (ctx->session_id == NULL) { 122 ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_SESSION_ID); 123 return 0; 124 } 125 if (ctx->type == 0) { 126 ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_TYPE); 127 return 0; 128 } 129 return SSHKDF(md, ctx->key, ctx->key_len, 130 ctx->xcghash, ctx->xcghash_len, 131 ctx->session_id, ctx->session_id_len, 132 ctx->type, key, keylen); 133 } 134 135 static int kdf_sshkdf_set_ctx_params(void *vctx, const OSSL_PARAM params[]) 136 { 137 const OSSL_PARAM *p; 138 KDF_SSHKDF *ctx = vctx; 139 OSSL_LIB_CTX *provctx = PROV_LIBCTX_OF(ctx->provctx); 140 141 if (params == NULL) 142 return 1; 143 144 if (!ossl_prov_digest_load_from_params(&ctx->digest, params, provctx)) 145 return 0; 146 147 if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_KEY)) != NULL) 148 if (!sshkdf_set_membuf(&ctx->key, &ctx->key_len, p)) 149 return 0; 150 151 if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_SSHKDF_XCGHASH)) 152 != NULL) 153 if (!sshkdf_set_membuf(&ctx->xcghash, &ctx->xcghash_len, p)) 154 return 0; 155 156 if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_SSHKDF_SESSION_ID)) 157 != NULL) 158 if (!sshkdf_set_membuf(&ctx->session_id, &ctx->session_id_len, p)) 159 return 0; 160 161 if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_SSHKDF_TYPE)) 162 != NULL) { 163 const char *kdftype; 164 165 if (!OSSL_PARAM_get_utf8_string_ptr(p, &kdftype)) 166 return 0; 167 /* Expect one character (byte in this case) */ 168 if (kdftype == NULL || p->data_size != 1) 169 return 0; 170 if (kdftype[0] < 65 || kdftype[0] > 70) { 171 ERR_raise(ERR_LIB_PROV, PROV_R_VALUE_ERROR); 172 return 0; 173 } 174 ctx->type = kdftype[0]; 175 } 176 return 1; 177 } 178 179 static const OSSL_PARAM *kdf_sshkdf_settable_ctx_params(ossl_unused void *ctx, 180 ossl_unused void *p_ctx) 181 { 182 static const OSSL_PARAM known_settable_ctx_params[] = { 183 OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_PROPERTIES, NULL, 0), 184 OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_DIGEST, NULL, 0), 185 OSSL_PARAM_octet_string(OSSL_KDF_PARAM_KEY, NULL, 0), 186 OSSL_PARAM_octet_string(OSSL_KDF_PARAM_SSHKDF_XCGHASH, NULL, 0), 187 OSSL_PARAM_octet_string(OSSL_KDF_PARAM_SSHKDF_SESSION_ID, NULL, 0), 188 OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_SSHKDF_TYPE, NULL, 0), 189 OSSL_PARAM_END 190 }; 191 return known_settable_ctx_params; 192 } 193 194 static int kdf_sshkdf_get_ctx_params(void *vctx, OSSL_PARAM params[]) 195 { 196 OSSL_PARAM *p; 197 198 if ((p = OSSL_PARAM_locate(params, OSSL_KDF_PARAM_SIZE)) != NULL) 199 return OSSL_PARAM_set_size_t(p, SIZE_MAX); 200 return -2; 201 } 202 203 static const OSSL_PARAM *kdf_sshkdf_gettable_ctx_params(ossl_unused void *ctx, 204 ossl_unused void *p_ctx) 205 { 206 static const OSSL_PARAM known_gettable_ctx_params[] = { 207 OSSL_PARAM_size_t(OSSL_KDF_PARAM_SIZE, NULL), 208 OSSL_PARAM_END 209 }; 210 return known_gettable_ctx_params; 211 } 212 213 const OSSL_DISPATCH ossl_kdf_sshkdf_functions[] = { 214 { OSSL_FUNC_KDF_NEWCTX, (void(*)(void))kdf_sshkdf_new }, 215 { OSSL_FUNC_KDF_FREECTX, (void(*)(void))kdf_sshkdf_free }, 216 { OSSL_FUNC_KDF_RESET, (void(*)(void))kdf_sshkdf_reset }, 217 { OSSL_FUNC_KDF_DERIVE, (void(*)(void))kdf_sshkdf_derive }, 218 { OSSL_FUNC_KDF_SETTABLE_CTX_PARAMS, 219 (void(*)(void))kdf_sshkdf_settable_ctx_params }, 220 { OSSL_FUNC_KDF_SET_CTX_PARAMS, (void(*)(void))kdf_sshkdf_set_ctx_params }, 221 { OSSL_FUNC_KDF_GETTABLE_CTX_PARAMS, 222 (void(*)(void))kdf_sshkdf_gettable_ctx_params }, 223 { OSSL_FUNC_KDF_GET_CTX_PARAMS, (void(*)(void))kdf_sshkdf_get_ctx_params }, 224 { 0, NULL } 225 }; 226 227 static int SSHKDF(const EVP_MD *evp_md, 228 const unsigned char *key, size_t key_len, 229 const unsigned char *xcghash, size_t xcghash_len, 230 const unsigned char *session_id, size_t session_id_len, 231 char type, unsigned char *okey, size_t okey_len) 232 { 233 EVP_MD_CTX *md = NULL; 234 unsigned char digest[EVP_MAX_MD_SIZE]; 235 unsigned int dsize = 0; 236 size_t cursize = 0; 237 int ret = 0; 238 239 md = EVP_MD_CTX_new(); 240 if (md == NULL) 241 return 0; 242 243 if (!EVP_DigestInit_ex(md, evp_md, NULL)) 244 goto out; 245 246 if (!EVP_DigestUpdate(md, key, key_len)) 247 goto out; 248 249 if (!EVP_DigestUpdate(md, xcghash, xcghash_len)) 250 goto out; 251 252 if (!EVP_DigestUpdate(md, &type, 1)) 253 goto out; 254 255 if (!EVP_DigestUpdate(md, session_id, session_id_len)) 256 goto out; 257 258 if (!EVP_DigestFinal_ex(md, digest, &dsize)) 259 goto out; 260 261 if (okey_len < dsize) { 262 memcpy(okey, digest, okey_len); 263 ret = 1; 264 goto out; 265 } 266 267 memcpy(okey, digest, dsize); 268 269 for (cursize = dsize; cursize < okey_len; cursize += dsize) { 270 271 if (!EVP_DigestInit_ex(md, evp_md, NULL)) 272 goto out; 273 274 if (!EVP_DigestUpdate(md, key, key_len)) 275 goto out; 276 277 if (!EVP_DigestUpdate(md, xcghash, xcghash_len)) 278 goto out; 279 280 if (!EVP_DigestUpdate(md, okey, cursize)) 281 goto out; 282 283 if (!EVP_DigestFinal_ex(md, digest, &dsize)) 284 goto out; 285 286 if (okey_len < cursize + dsize) { 287 memcpy(okey + cursize, digest, okey_len - cursize); 288 ret = 1; 289 goto out; 290 } 291 292 memcpy(okey + cursize, digest, dsize); 293 } 294 295 ret = 1; 296 297 out: 298 EVP_MD_CTX_free(md); 299 OPENSSL_cleanse(digest, EVP_MAX_MD_SIZE); 300 return ret; 301 } 302 303