1 /* $OpenBSD: tls_ocsp.c,v 1.19 2019/12/03 14:56:42 tb Exp $ */ 2 /* 3 * Copyright (c) 2015 Marko Kreen <markokr@gmail.com> 4 * Copyright (c) 2016 Bob Beck <beck@openbsd.org> 5 * 6 * Permission to use, copy, modify, and distribute this software for any 7 * purpose with or without fee is hereby granted, provided that the above 8 * copyright notice and this permission notice appear in all copies. 9 * 10 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 11 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 12 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 13 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 14 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 15 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 16 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 17 */ 18 19 #include <sys/types.h> 20 21 #include <arpa/inet.h> 22 #include <netinet/in.h> 23 24 #include <openssl/err.h> 25 #include <openssl/ocsp.h> 26 #include <openssl/x509.h> 27 28 #include <tls.h> 29 #include "tls_internal.h" 30 31 #define MAXAGE_SEC (14*24*60*60) 32 #define JITTER_SEC (60) 33 34 /* 35 * State for request. 36 */ 37 38 static struct tls_ocsp * 39 tls_ocsp_new(void) 40 { 41 return (calloc(1, sizeof(struct tls_ocsp))); 42 } 43 44 void 45 tls_ocsp_free(struct tls_ocsp *ocsp) 46 { 47 if (ocsp == NULL) 48 return; 49 50 X509_free(ocsp->main_cert); 51 free(ocsp->ocsp_result); 52 free(ocsp->ocsp_url); 53 54 free(ocsp); 55 } 56 57 static int 58 tls_ocsp_asn1_parse_time(struct tls *ctx, ASN1_GENERALIZEDTIME *gt, time_t *gt_time) 59 { 60 struct tm tm; 61 62 if (gt == NULL) 63 return -1; 64 /* RFC 6960 specifies that all times in OCSP must be GENERALIZEDTIME */ 65 if (ASN1_time_parse(gt->data, gt->length, &tm, 66 V_ASN1_GENERALIZEDTIME) == -1) 67 return -1; 68 if ((*gt_time = timegm(&tm)) == -1) 69 return -1; 70 return 0; 71 } 72 73 static int 74 tls_ocsp_fill_info(struct tls *ctx, int response_status, int cert_status, 75 int crl_reason, ASN1_GENERALIZEDTIME *revtime, 76 ASN1_GENERALIZEDTIME *thisupd, ASN1_GENERALIZEDTIME *nextupd) 77 { 78 struct tls_ocsp_result *info = NULL; 79 80 free(ctx->ocsp->ocsp_result); 81 ctx->ocsp->ocsp_result = NULL; 82 83 if ((info = calloc(1, sizeof (struct tls_ocsp_result))) == NULL) { 84 tls_set_error(ctx, "calloc"); 85 return -1; 86 } 87 info->response_status = response_status; 88 info->cert_status = cert_status; 89 info->crl_reason = crl_reason; 90 if (info->response_status != OCSP_RESPONSE_STATUS_SUCCESSFUL) { 91 info->result_msg = 92 OCSP_response_status_str(info->response_status); 93 } else if (info->cert_status != V_OCSP_CERTSTATUS_REVOKED) { 94 info->result_msg = OCSP_cert_status_str(info->cert_status); 95 } else { 96 info->result_msg = OCSP_crl_reason_str(info->crl_reason); 97 } 98 info->revocation_time = info->this_update = info->next_update = -1; 99 if (revtime != NULL && 100 tls_ocsp_asn1_parse_time(ctx, revtime, &info->revocation_time) != 0) { 101 tls_set_error(ctx, 102 "unable to parse revocation time in OCSP reply"); 103 goto err; 104 } 105 if (thisupd != NULL && 106 tls_ocsp_asn1_parse_time(ctx, thisupd, &info->this_update) != 0) { 107 tls_set_error(ctx, 108 "unable to parse this update time in OCSP reply"); 109 goto err; 110 } 111 if (nextupd != NULL && 112 tls_ocsp_asn1_parse_time(ctx, nextupd, &info->next_update) != 0) { 113 tls_set_error(ctx, 114 "unable to parse next update time in OCSP reply"); 115 goto err; 116 } 117 ctx->ocsp->ocsp_result = info; 118 return 0; 119 120 err: 121 free(info); 122 return -1; 123 } 124 125 static OCSP_CERTID * 126 tls_ocsp_get_certid(X509 *main_cert, STACK_OF(X509) *extra_certs, 127 SSL_CTX *ssl_ctx) 128 { 129 X509_NAME *issuer_name; 130 X509 *issuer; 131 X509_STORE_CTX storectx; 132 X509_OBJECT tmpobj; 133 OCSP_CERTID *cid = NULL; 134 X509_STORE *store; 135 136 if ((issuer_name = X509_get_issuer_name(main_cert)) == NULL) 137 return NULL; 138 139 if (extra_certs != NULL) { 140 issuer = X509_find_by_subject(extra_certs, issuer_name); 141 if (issuer != NULL) 142 return OCSP_cert_to_id(NULL, main_cert, issuer); 143 } 144 145 if ((store = SSL_CTX_get_cert_store(ssl_ctx)) == NULL) 146 return NULL; 147 if (X509_STORE_CTX_init(&storectx, store, main_cert, extra_certs) != 1) 148 return NULL; 149 if (X509_STORE_get_by_subject(&storectx, X509_LU_X509, issuer_name, 150 &tmpobj) == 1) { 151 cid = OCSP_cert_to_id(NULL, main_cert, tmpobj.data.x509); 152 X509_OBJECT_free_contents(&tmpobj); 153 } 154 X509_STORE_CTX_cleanup(&storectx); 155 return cid; 156 } 157 158 struct tls_ocsp * 159 tls_ocsp_setup_from_peer(struct tls *ctx) 160 { 161 struct tls_ocsp *ocsp = NULL; 162 STACK_OF(OPENSSL_STRING) *ocsp_urls = NULL; 163 164 if ((ocsp = tls_ocsp_new()) == NULL) 165 goto err; 166 167 /* steal state from ctx struct */ 168 ocsp->main_cert = SSL_get_peer_certificate(ctx->ssl_conn); 169 ocsp->extra_certs = SSL_get_peer_cert_chain(ctx->ssl_conn); 170 if (ocsp->main_cert == NULL) { 171 tls_set_errorx(ctx, "no peer certificate for OCSP"); 172 goto err; 173 } 174 175 ocsp_urls = X509_get1_ocsp(ocsp->main_cert); 176 if (ocsp_urls == NULL) { 177 tls_set_errorx(ctx, "no OCSP URLs in peer certificate"); 178 goto err; 179 } 180 181 ocsp->ocsp_url = strdup(sk_OPENSSL_STRING_value(ocsp_urls, 0)); 182 if (ocsp->ocsp_url == NULL) { 183 tls_set_errorx(ctx, "out of memory"); 184 goto err; 185 } 186 187 X509_email_free(ocsp_urls); 188 return ocsp; 189 190 err: 191 tls_ocsp_free(ocsp); 192 X509_email_free(ocsp_urls); 193 return NULL; 194 } 195 196 static int 197 tls_ocsp_verify_response(struct tls *ctx, OCSP_RESPONSE *resp) 198 { 199 OCSP_BASICRESP *br = NULL; 200 ASN1_GENERALIZEDTIME *revtime = NULL, *thisupd = NULL, *nextupd = NULL; 201 OCSP_CERTID *cid = NULL; 202 STACK_OF(X509) *combined = NULL; 203 int response_status=0, cert_status=0, crl_reason=0; 204 int ret = -1; 205 unsigned long flags; 206 207 if ((br = OCSP_response_get1_basic(resp)) == NULL) { 208 tls_set_errorx(ctx, "cannot load ocsp reply"); 209 goto err; 210 } 211 212 /* 213 * Skip validation of 'extra_certs' as this should be done 214 * already as part of main handshake. 215 */ 216 flags = OCSP_TRUSTOTHER; 217 218 /* now verify */ 219 if (OCSP_basic_verify(br, ctx->ocsp->extra_certs, 220 SSL_CTX_get_cert_store(ctx->ssl_ctx), flags) != 1) { 221 tls_set_error(ctx, "ocsp verify failed"); 222 goto err; 223 } 224 225 /* signature OK, look inside */ 226 response_status = OCSP_response_status(resp); 227 if (response_status != OCSP_RESPONSE_STATUS_SUCCESSFUL) { 228 tls_set_errorx(ctx, "ocsp verify failed: response - %s", 229 OCSP_response_status_str(response_status)); 230 goto err; 231 } 232 233 cid = tls_ocsp_get_certid(ctx->ocsp->main_cert, 234 ctx->ocsp->extra_certs, ctx->ssl_ctx); 235 if (cid == NULL) { 236 tls_set_errorx(ctx, "ocsp verify failed: no issuer cert"); 237 goto err; 238 } 239 240 if (OCSP_resp_find_status(br, cid, &cert_status, &crl_reason, 241 &revtime, &thisupd, &nextupd) != 1) { 242 tls_set_errorx(ctx, "ocsp verify failed: no result for cert"); 243 goto err; 244 } 245 246 if (OCSP_check_validity(thisupd, nextupd, JITTER_SEC, 247 MAXAGE_SEC) != 1) { 248 tls_set_errorx(ctx, 249 "ocsp verify failed: ocsp response not current"); 250 goto err; 251 } 252 253 if (tls_ocsp_fill_info(ctx, response_status, cert_status, 254 crl_reason, revtime, thisupd, nextupd) != 0) 255 goto err; 256 257 /* finally can look at status */ 258 if (cert_status != V_OCSP_CERTSTATUS_GOOD && cert_status != 259 V_OCSP_CERTSTATUS_UNKNOWN) { 260 tls_set_errorx(ctx, "ocsp verify failed: revoked cert - %s", 261 OCSP_crl_reason_str(crl_reason)); 262 goto err; 263 } 264 ret = 0; 265 266 err: 267 sk_X509_free(combined); 268 OCSP_CERTID_free(cid); 269 OCSP_BASICRESP_free(br); 270 return ret; 271 } 272 273 /* 274 * Process a raw OCSP response from an OCSP server request. 275 * OCSP details can then be retrieved with tls_peer_ocsp_* functions. 276 * returns 0 if certificate ok, -1 otherwise. 277 */ 278 static int 279 tls_ocsp_process_response_internal(struct tls *ctx, const unsigned char *response, 280 size_t size) 281 { 282 int ret; 283 OCSP_RESPONSE *resp; 284 285 resp = d2i_OCSP_RESPONSE(NULL, &response, size); 286 if (resp == NULL) { 287 tls_ocsp_free(ctx->ocsp); 288 ctx->ocsp = NULL; 289 tls_set_error(ctx, "unable to parse OCSP response"); 290 return -1; 291 } 292 ret = tls_ocsp_verify_response(ctx, resp); 293 OCSP_RESPONSE_free(resp); 294 return ret; 295 } 296 297 /* TLS handshake verification callback for stapled requests */ 298 int 299 tls_ocsp_verify_cb(SSL *ssl, void *arg) 300 { 301 const unsigned char *raw = NULL; 302 int size, res = -1; 303 struct tls *ctx; 304 305 if ((ctx = SSL_get_app_data(ssl)) == NULL) 306 return -1; 307 308 size = SSL_get_tlsext_status_ocsp_resp(ssl, &raw); 309 if (size <= 0) { 310 if (ctx->config->ocsp_require_stapling) { 311 tls_set_errorx(ctx, "no stapled OCSP response provided"); 312 return 0; 313 } 314 return 1; 315 } 316 317 tls_ocsp_free(ctx->ocsp); 318 if ((ctx->ocsp = tls_ocsp_setup_from_peer(ctx)) == NULL) 319 return 0; 320 321 if (ctx->config->verify_cert == 0 || ctx->config->verify_time == 0) 322 return 1; 323 324 res = tls_ocsp_process_response_internal(ctx, raw, size); 325 326 return (res == 0) ? 1 : 0; 327 } 328 329 330 /* Staple the OCSP information in ctx->ocsp to the server handshake. */ 331 int 332 tls_ocsp_stapling_cb(SSL *ssl, void *arg) 333 { 334 int ret = SSL_TLSEXT_ERR_ALERT_FATAL; 335 unsigned char *ocsp_staple = NULL; 336 struct tls *ctx; 337 338 if ((ctx = SSL_get_app_data(ssl)) == NULL) 339 goto err; 340 341 if (ctx->keypair == NULL || ctx->keypair->ocsp_staple == NULL || 342 ctx->keypair->ocsp_staple_len == 0) 343 return SSL_TLSEXT_ERR_NOACK; 344 345 if ((ocsp_staple = malloc(ctx->keypair->ocsp_staple_len)) == NULL) 346 goto err; 347 348 memcpy(ocsp_staple, ctx->keypair->ocsp_staple, 349 ctx->keypair->ocsp_staple_len); 350 351 if (SSL_set_tlsext_status_ocsp_resp(ctx->ssl_conn, ocsp_staple, 352 ctx->keypair->ocsp_staple_len) != 1) 353 goto err; 354 355 ret = SSL_TLSEXT_ERR_OK; 356 err: 357 if (ret != SSL_TLSEXT_ERR_OK) 358 free(ocsp_staple); 359 360 return ret; 361 } 362 363 /* 364 * Public API 365 */ 366 367 /* Retrieve OCSP URL from peer certificate, if present. */ 368 const char * 369 tls_peer_ocsp_url(struct tls *ctx) 370 { 371 if (ctx->ocsp == NULL) 372 return NULL; 373 return ctx->ocsp->ocsp_url; 374 } 375 376 const char * 377 tls_peer_ocsp_result(struct tls *ctx) 378 { 379 if (ctx->ocsp == NULL) 380 return NULL; 381 if (ctx->ocsp->ocsp_result == NULL) 382 return NULL; 383 return ctx->ocsp->ocsp_result->result_msg; 384 } 385 386 int 387 tls_peer_ocsp_response_status(struct tls *ctx) 388 { 389 if (ctx->ocsp == NULL) 390 return -1; 391 if (ctx->ocsp->ocsp_result == NULL) 392 return -1; 393 return ctx->ocsp->ocsp_result->response_status; 394 } 395 396 int 397 tls_peer_ocsp_cert_status(struct tls *ctx) 398 { 399 if (ctx->ocsp == NULL) 400 return -1; 401 if (ctx->ocsp->ocsp_result == NULL) 402 return -1; 403 return ctx->ocsp->ocsp_result->cert_status; 404 } 405 406 int 407 tls_peer_ocsp_crl_reason(struct tls *ctx) 408 { 409 if (ctx->ocsp == NULL) 410 return -1; 411 if (ctx->ocsp->ocsp_result == NULL) 412 return -1; 413 return ctx->ocsp->ocsp_result->crl_reason; 414 } 415 416 time_t 417 tls_peer_ocsp_this_update(struct tls *ctx) 418 { 419 if (ctx->ocsp == NULL) 420 return -1; 421 if (ctx->ocsp->ocsp_result == NULL) 422 return -1; 423 return ctx->ocsp->ocsp_result->this_update; 424 } 425 426 time_t 427 tls_peer_ocsp_next_update(struct tls *ctx) 428 { 429 if (ctx->ocsp == NULL) 430 return -1; 431 if (ctx->ocsp->ocsp_result == NULL) 432 return -1; 433 return ctx->ocsp->ocsp_result->next_update; 434 } 435 436 time_t 437 tls_peer_ocsp_revocation_time(struct tls *ctx) 438 { 439 if (ctx->ocsp == NULL) 440 return -1; 441 if (ctx->ocsp->ocsp_result == NULL) 442 return -1; 443 return ctx->ocsp->ocsp_result->revocation_time; 444 } 445 446 int 447 tls_ocsp_process_response(struct tls *ctx, const unsigned char *response, 448 size_t size) 449 { 450 if ((ctx->state & TLS_HANDSHAKE_COMPLETE) == 0) 451 return -1; 452 return tls_ocsp_process_response_internal(ctx, response, size); 453 } 454