1 /* 2 * Copyright (c) 2015 Marko Kreen <markokr@gmail.com> 3 * Copyright (c) 2016 Bob Beck <beck@openbsd.org> 4 * 5 * Permission to use, copy, modify, and distribute this software for any 6 * purpose with or without fee is hereby granted, provided that the above 7 * copyright notice and this permission notice appear in all copies. 8 * 9 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 10 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 11 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 12 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 13 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 14 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 15 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 16 */ 17 18 #include <sys/types.h> 19 20 #include <arpa/inet.h> 21 #include <netinet/in.h> 22 23 #include <openssl/err.h> 24 #include <openssl/ocsp.h> 25 #include <openssl/x509.h> 26 27 #include <tls.h> 28 #include "tls_internal.h" 29 30 #define MAXAGE_SEC (14*24*60*60) 31 #define JITTER_SEC (60) 32 33 /* 34 * State for request. 35 */ 36 37 static struct tls_ocsp * 38 tls_ocsp_new(void) 39 { 40 return (calloc(1, sizeof(struct tls_ocsp))); 41 } 42 43 void 44 tls_ocsp_free(struct tls_ocsp *ocsp) 45 { 46 if (ocsp == NULL) 47 return; 48 49 X509_free(ocsp->main_cert); 50 free(ocsp->ocsp_result); 51 free(ocsp->ocsp_url); 52 53 free(ocsp); 54 } 55 56 static int 57 tls_ocsp_asn1_parse_time(struct tls *ctx, ASN1_GENERALIZEDTIME *gt, time_t *gt_time) 58 { 59 struct tm tm; 60 61 if (gt == NULL) 62 return -1; 63 /* RFC 6960 specifies that all times in OCSP must be GENERALIZEDTIME */ 64 if (ASN1_time_parse(gt->data, gt->length, &tm, 65 V_ASN1_GENERALIZEDTIME) == -1) 66 return -1; 67 if ((*gt_time = timegm(&tm)) == -1) 68 return -1; 69 return 0; 70 } 71 72 static int 73 tls_ocsp_fill_info(struct tls *ctx, int response_status, int cert_status, 74 int crl_reason, ASN1_GENERALIZEDTIME *revtime, 75 ASN1_GENERALIZEDTIME *thisupd, ASN1_GENERALIZEDTIME *nextupd) 76 { 77 struct tls_ocsp_result *info = NULL; 78 79 free(ctx->ocsp->ocsp_result); 80 ctx->ocsp->ocsp_result = NULL; 81 82 if ((info = calloc(1, sizeof (struct tls_ocsp_result))) == NULL) { 83 tls_set_error(ctx, "calloc"); 84 return -1; 85 } 86 info->response_status = response_status; 87 info->cert_status = cert_status; 88 info->crl_reason = crl_reason; 89 if (info->response_status != OCSP_RESPONSE_STATUS_SUCCESSFUL) { 90 info->result_msg = 91 OCSP_response_status_str(info->response_status); 92 } else if (info->cert_status != V_OCSP_CERTSTATUS_REVOKED) { 93 info->result_msg = OCSP_cert_status_str(info->cert_status); 94 } else { 95 info->result_msg = OCSP_crl_reason_str(info->crl_reason); 96 } 97 info->revocation_time = info->this_update = info->next_update = -1; 98 if (revtime != NULL && 99 tls_ocsp_asn1_parse_time(ctx, revtime, &info->revocation_time) != 0) { 100 tls_set_error(ctx, 101 "unable to parse revocation time in OCSP reply"); 102 goto err; 103 } 104 if (thisupd != NULL && 105 tls_ocsp_asn1_parse_time(ctx, thisupd, &info->this_update) != 0) { 106 tls_set_error(ctx, 107 "unable to parse this update time in OCSP reply"); 108 goto err; 109 } 110 if (nextupd != NULL && 111 tls_ocsp_asn1_parse_time(ctx, nextupd, &info->next_update) != 0) { 112 tls_set_error(ctx, 113 "unable to parse next update time in OCSP reply"); 114 goto err; 115 } 116 ctx->ocsp->ocsp_result = info; 117 return 0; 118 119 err: 120 free(info); 121 return -1; 122 } 123 124 static OCSP_CERTID * 125 tls_ocsp_get_certid(X509 *main_cert, STACK_OF(X509) *extra_certs, 126 SSL_CTX *ssl_ctx) 127 { 128 X509_NAME *issuer_name; 129 X509 *issuer; 130 X509_STORE_CTX storectx; 131 X509_OBJECT tmpobj; 132 OCSP_CERTID *cid = NULL; 133 X509_STORE *store; 134 135 if ((issuer_name = X509_get_issuer_name(main_cert)) == NULL) 136 return NULL; 137 138 if (extra_certs != NULL) { 139 issuer = X509_find_by_subject(extra_certs, issuer_name); 140 if (issuer != NULL) 141 return OCSP_cert_to_id(NULL, main_cert, issuer); 142 } 143 144 if ((store = SSL_CTX_get_cert_store(ssl_ctx)) == NULL) 145 return NULL; 146 if (X509_STORE_CTX_init(&storectx, store, main_cert, extra_certs) != 1) 147 return NULL; 148 if (X509_STORE_get_by_subject(&storectx, X509_LU_X509, issuer_name, 149 &tmpobj) == 1) { 150 cid = OCSP_cert_to_id(NULL, main_cert, tmpobj.data.x509); 151 X509_OBJECT_free_contents(&tmpobj); 152 } 153 X509_STORE_CTX_cleanup(&storectx); 154 return cid; 155 } 156 157 struct tls_ocsp * 158 tls_ocsp_setup_from_peer(struct tls *ctx) 159 { 160 struct tls_ocsp *ocsp = NULL; 161 STACK_OF(OPENSSL_STRING) *ocsp_urls = NULL; 162 163 if ((ocsp = tls_ocsp_new()) == NULL) 164 goto err; 165 166 /* steal state from ctx struct */ 167 ocsp->main_cert = SSL_get_peer_certificate(ctx->ssl_conn); 168 ocsp->extra_certs = SSL_get_peer_cert_chain(ctx->ssl_conn); 169 if (ocsp->main_cert == NULL) { 170 tls_set_errorx(ctx, "no peer certificate for OCSP"); 171 goto err; 172 } 173 174 ocsp_urls = X509_get1_ocsp(ocsp->main_cert); 175 if (ocsp_urls == NULL) { 176 tls_set_errorx(ctx, "no OCSP URLs in peer certificate"); 177 goto err; 178 } 179 180 ocsp->ocsp_url = strdup(sk_OPENSSL_STRING_value(ocsp_urls, 0)); 181 if (ocsp->ocsp_url == NULL) { 182 tls_set_errorx(ctx, "out of memory"); 183 goto err; 184 } 185 186 X509_email_free(ocsp_urls); 187 return ocsp; 188 189 err: 190 tls_ocsp_free(ocsp); 191 X509_email_free(ocsp_urls); 192 return NULL; 193 } 194 195 static int 196 tls_ocsp_verify_response(struct tls *ctx, OCSP_RESPONSE *resp) 197 { 198 OCSP_BASICRESP *br = NULL; 199 ASN1_GENERALIZEDTIME *revtime = NULL, *thisupd = NULL, *nextupd = NULL; 200 OCSP_CERTID *cid = NULL; 201 STACK_OF(X509) *combined = NULL; 202 int response_status=0, cert_status=0, crl_reason=0; 203 int ret = -1; 204 unsigned long flags; 205 206 if ((br = OCSP_response_get1_basic(resp)) == NULL) { 207 tls_set_errorx(ctx, "cannot load ocsp reply"); 208 goto err; 209 } 210 211 /* 212 * Skip validation of 'extra_certs' as this should be done 213 * already as part of main handshake. 214 */ 215 flags = OCSP_TRUSTOTHER; 216 217 /* now verify */ 218 if (OCSP_basic_verify(br, ctx->ocsp->extra_certs, 219 SSL_CTX_get_cert_store(ctx->ssl_ctx), flags) != 1) { 220 tls_set_error(ctx, "ocsp verify failed"); 221 goto err; 222 } 223 224 /* signature OK, look inside */ 225 response_status = OCSP_response_status(resp); 226 if (response_status != OCSP_RESPONSE_STATUS_SUCCESSFUL) { 227 tls_set_errorx(ctx, "ocsp verify failed: response - %s", 228 OCSP_response_status_str(response_status)); 229 goto err; 230 } 231 232 cid = tls_ocsp_get_certid(ctx->ocsp->main_cert, 233 ctx->ocsp->extra_certs, ctx->ssl_ctx); 234 if (cid == NULL) { 235 tls_set_errorx(ctx, "ocsp verify failed: no issuer cert"); 236 goto err; 237 } 238 239 if (OCSP_resp_find_status(br, cid, &cert_status, &crl_reason, 240 &revtime, &thisupd, &nextupd) != 1) { 241 tls_set_errorx(ctx, "ocsp verify failed: no result for cert"); 242 goto err; 243 } 244 245 if (OCSP_check_validity(thisupd, nextupd, JITTER_SEC, 246 MAXAGE_SEC) != 1) { 247 tls_set_errorx(ctx, 248 "ocsp verify failed: ocsp response not current"); 249 goto err; 250 } 251 252 if (tls_ocsp_fill_info(ctx, response_status, cert_status, 253 crl_reason, revtime, thisupd, nextupd) != 0) 254 goto err; 255 256 /* finally can look at status */ 257 if (cert_status != V_OCSP_CERTSTATUS_GOOD && cert_status != 258 V_OCSP_CERTSTATUS_UNKNOWN) { 259 tls_set_errorx(ctx, "ocsp verify failed: revoked cert - %s", 260 OCSP_crl_reason_str(crl_reason)); 261 goto err; 262 } 263 ret = 0; 264 265 err: 266 sk_X509_free(combined); 267 OCSP_CERTID_free(cid); 268 OCSP_BASICRESP_free(br); 269 return ret; 270 } 271 272 /* 273 * Process a raw OCSP response from an OCSP server request. 274 * OCSP details can then be retrieved with tls_peer_ocsp_* functions. 275 * returns 0 if certificate ok, -1 otherwise. 276 */ 277 static int 278 tls_ocsp_process_response_internal(struct tls *ctx, const unsigned char *response, 279 size_t size) 280 { 281 int ret; 282 OCSP_RESPONSE *resp; 283 284 resp = d2i_OCSP_RESPONSE(NULL, &response, size); 285 if (resp == NULL) { 286 tls_ocsp_free(ctx->ocsp); 287 ctx->ocsp = NULL; 288 tls_set_error(ctx, "unable to parse OCSP response"); 289 return -1; 290 } 291 ret = tls_ocsp_verify_response(ctx, resp); 292 OCSP_RESPONSE_free(resp); 293 return ret; 294 } 295 296 /* TLS handshake verification callback for stapled requests */ 297 int 298 tls_ocsp_verify_cb(SSL *ssl, void *arg) 299 { 300 const unsigned char *raw = NULL; 301 int size, res = -1; 302 struct tls *ctx; 303 304 if ((ctx = SSL_get_app_data(ssl)) == NULL) 305 return -1; 306 307 size = SSL_get_tlsext_status_ocsp_resp(ssl, &raw); 308 if (size <= 0) { 309 if (ctx->config->ocsp_require_stapling) { 310 tls_set_errorx(ctx, "no stapled OCSP response provided"); 311 return 0; 312 } 313 return 1; 314 } 315 316 tls_ocsp_free(ctx->ocsp); 317 if ((ctx->ocsp = tls_ocsp_setup_from_peer(ctx)) == NULL) 318 return 0; 319 320 if (ctx->config->verify_cert == 0 || ctx->config->verify_time == 0) 321 return 1; 322 323 res = tls_ocsp_process_response_internal(ctx, raw, size); 324 325 return (res == 0) ? 1 : 0; 326 } 327 328 329 /* Staple the OCSP information in ctx->ocsp to the server handshake. */ 330 int 331 tls_ocsp_stapling_cb(SSL *ssl, void *arg) 332 { 333 int ret = SSL_TLSEXT_ERR_ALERT_FATAL; 334 unsigned char *ocsp_staple = NULL; 335 struct tls *ctx; 336 337 if ((ctx = SSL_get_app_data(ssl)) == NULL) 338 goto err; 339 340 if (ctx->keypair == NULL || ctx->keypair->ocsp_staple == NULL || 341 ctx->keypair->ocsp_staple_len == 0) 342 return SSL_TLSEXT_ERR_NOACK; 343 344 if ((ocsp_staple = malloc(ctx->keypair->ocsp_staple_len)) == NULL) 345 goto err; 346 347 memcpy(ocsp_staple, ctx->keypair->ocsp_staple, 348 ctx->keypair->ocsp_staple_len); 349 350 if (SSL_set_tlsext_status_ocsp_resp(ctx->ssl_conn, ocsp_staple, 351 ctx->keypair->ocsp_staple_len) != 1) 352 goto err; 353 354 ret = SSL_TLSEXT_ERR_OK; 355 err: 356 if (ret != SSL_TLSEXT_ERR_OK) 357 free(ocsp_staple); 358 359 return ret; 360 } 361 362 /* 363 * Public API 364 */ 365 366 /* Retrieve OCSP URL from peer certificate, if present. */ 367 const char * 368 tls_peer_ocsp_url(struct tls *ctx) 369 { 370 if (ctx->ocsp == NULL) 371 return NULL; 372 return ctx->ocsp->ocsp_url; 373 } 374 375 const char * 376 tls_peer_ocsp_result(struct tls *ctx) 377 { 378 if (ctx->ocsp == NULL) 379 return NULL; 380 if (ctx->ocsp->ocsp_result == NULL) 381 return NULL; 382 return ctx->ocsp->ocsp_result->result_msg; 383 } 384 385 int 386 tls_peer_ocsp_response_status(struct tls *ctx) 387 { 388 if (ctx->ocsp == NULL) 389 return -1; 390 if (ctx->ocsp->ocsp_result == NULL) 391 return -1; 392 return ctx->ocsp->ocsp_result->response_status; 393 } 394 395 int 396 tls_peer_ocsp_cert_status(struct tls *ctx) 397 { 398 if (ctx->ocsp == NULL) 399 return -1; 400 if (ctx->ocsp->ocsp_result == NULL) 401 return -1; 402 return ctx->ocsp->ocsp_result->cert_status; 403 } 404 405 int 406 tls_peer_ocsp_crl_reason(struct tls *ctx) 407 { 408 if (ctx->ocsp == NULL) 409 return -1; 410 if (ctx->ocsp->ocsp_result == NULL) 411 return -1; 412 return ctx->ocsp->ocsp_result->crl_reason; 413 } 414 415 time_t 416 tls_peer_ocsp_this_update(struct tls *ctx) 417 { 418 if (ctx->ocsp == NULL) 419 return -1; 420 if (ctx->ocsp->ocsp_result == NULL) 421 return -1; 422 return ctx->ocsp->ocsp_result->this_update; 423 } 424 425 time_t 426 tls_peer_ocsp_next_update(struct tls *ctx) 427 { 428 if (ctx->ocsp == NULL) 429 return -1; 430 if (ctx->ocsp->ocsp_result == NULL) 431 return -1; 432 return ctx->ocsp->ocsp_result->next_update; 433 } 434 435 time_t 436 tls_peer_ocsp_revocation_time(struct tls *ctx) 437 { 438 if (ctx->ocsp == NULL) 439 return -1; 440 if (ctx->ocsp->ocsp_result == NULL) 441 return -1; 442 return ctx->ocsp->ocsp_result->revocation_time; 443 } 444 445 int 446 tls_ocsp_process_response(struct tls *ctx, const unsigned char *response, 447 size_t size) 448 { 449 if ((ctx->state & TLS_HANDSHAKE_COMPLETE) == 0) 450 return -1; 451 return tls_ocsp_process_response_internal(ctx, response, size); 452 } 453