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 ocsp->main_cert = NULL; 51 free(ocsp->ocsp_result); 52 ocsp->ocsp_result = NULL; 53 free(ocsp->ocsp_url); 54 ocsp->ocsp_url = NULL; 55 free(ocsp); 56 } 57 58 static int 59 tls_ocsp_asn1_parse_time(struct tls *ctx, ASN1_GENERALIZEDTIME *gt, time_t *gt_time) 60 { 61 struct tm tm; 62 63 if (gt == NULL) 64 return -1; 65 /* RFC 6960 specifies that all times in OCSP must be GENERALIZEDTIME */ 66 if (ASN1_time_parse(gt->data, gt->length, &tm, 67 V_ASN1_GENERALIZEDTIME) == -1) 68 return -1; 69 if ((*gt_time = timegm(&tm)) == -1) 70 return -1; 71 return 0; 72 } 73 74 static int 75 tls_ocsp_fill_info(struct tls *ctx, int response_status, int cert_status, 76 int crl_reason, ASN1_GENERALIZEDTIME *revtime, 77 ASN1_GENERALIZEDTIME *thisupd, ASN1_GENERALIZEDTIME *nextupd) 78 { 79 struct tls_ocsp_result *info = NULL; 80 81 free(ctx->ocsp->ocsp_result); 82 ctx->ocsp->ocsp_result = NULL; 83 84 if ((info = calloc(1, sizeof (struct tls_ocsp_result))) == NULL) { 85 tls_set_error(ctx, "calloc"); 86 return -1; 87 } 88 info->response_status = response_status; 89 info->cert_status = cert_status; 90 info->crl_reason = crl_reason; 91 if (info->response_status != OCSP_RESPONSE_STATUS_SUCCESSFUL) { 92 info->result_msg = 93 OCSP_response_status_str(info->response_status); 94 } else if (info->cert_status != V_OCSP_CERTSTATUS_REVOKED) { 95 info->result_msg = OCSP_cert_status_str(info->cert_status); 96 } else { 97 info->result_msg = OCSP_crl_reason_str(info->crl_reason); 98 } 99 info->revocation_time = info->this_update = info->next_update = -1; 100 if (revtime != NULL && 101 tls_ocsp_asn1_parse_time(ctx, revtime, &info->revocation_time) != 0) { 102 tls_set_error(ctx, 103 "unable to parse revocation time in OCSP reply"); 104 goto error; 105 } 106 if (thisupd != NULL && 107 tls_ocsp_asn1_parse_time(ctx, thisupd, &info->this_update) != 0) { 108 tls_set_error(ctx, 109 "unable to parse this update time in OCSP reply"); 110 goto error; 111 } 112 if (nextupd != NULL && 113 tls_ocsp_asn1_parse_time(ctx, nextupd, &info->next_update) != 0) { 114 tls_set_error(ctx, 115 "unable to parse next update time in OCSP reply"); 116 goto error; 117 } 118 ctx->ocsp->ocsp_result = info; 119 return 0; 120 error: 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 failed; 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 failed; 173 } 174 175 ocsp_urls = X509_get1_ocsp(ocsp->main_cert); 176 if (ocsp_urls == NULL) 177 goto failed; 178 ocsp->ocsp_url = strdup(sk_OPENSSL_STRING_value(ocsp_urls, 0)); 179 if (ocsp->ocsp_url == NULL) { 180 tls_set_errorx(ctx, "out of memory"); 181 goto failed; 182 } 183 184 X509_email_free(ocsp_urls); 185 return ocsp; 186 187 failed: 188 tls_ocsp_free(ocsp); 189 X509_email_free(ocsp_urls); 190 return NULL; 191 } 192 193 static int 194 tls_ocsp_verify_response(struct tls *ctx, OCSP_RESPONSE *resp) 195 { 196 OCSP_BASICRESP *br = NULL; 197 ASN1_GENERALIZEDTIME *revtime = NULL, *thisupd = NULL, *nextupd = NULL; 198 OCSP_CERTID *cid = NULL; 199 STACK_OF(X509) *combined = NULL; 200 int response_status=0, cert_status=0, crl_reason=0; 201 int ret = -1; 202 unsigned long flags; 203 204 if ((br = OCSP_response_get1_basic(resp)) == NULL) { 205 tls_set_errorx(ctx, "cannot load ocsp reply"); 206 goto error; 207 } 208 209 /* 210 * Skip validation of 'extra_certs' as this should be done 211 * already as part of main handshake. 212 */ 213 flags = OCSP_TRUSTOTHER; 214 215 /* now verify */ 216 if (OCSP_basic_verify(br, ctx->ocsp->extra_certs, 217 SSL_CTX_get_cert_store(ctx->ssl_ctx), flags) != 1) { 218 tls_set_error(ctx, "ocsp verify failed"); 219 goto error; 220 } 221 222 /* signature OK, look inside */ 223 response_status = OCSP_response_status(resp); 224 if (response_status != OCSP_RESPONSE_STATUS_SUCCESSFUL) { 225 tls_set_errorx(ctx, "ocsp verify failed: response - %s", 226 OCSP_response_status_str(response_status)); 227 goto error; 228 } 229 230 cid = tls_ocsp_get_certid(ctx->ocsp->main_cert, 231 ctx->ocsp->extra_certs, ctx->ssl_ctx); 232 if (cid == NULL) { 233 tls_set_errorx(ctx, "ocsp verify failed: no issuer cert"); 234 goto error; 235 } 236 237 if (OCSP_resp_find_status(br, cid, &cert_status, &crl_reason, 238 &revtime, &thisupd, &nextupd) != 1) { 239 tls_set_errorx(ctx, "ocsp verify failed: no result for cert"); 240 goto error; 241 } 242 243 if (OCSP_check_validity(thisupd, nextupd, JITTER_SEC, 244 MAXAGE_SEC) != 1) { 245 tls_set_errorx(ctx, 246 "ocsp verify failed: ocsp response not current"); 247 goto error; 248 } 249 250 if (tls_ocsp_fill_info(ctx, response_status, cert_status, 251 crl_reason, revtime, thisupd, nextupd) != 0) 252 goto error; 253 254 /* finally can look at status */ 255 if (cert_status != V_OCSP_CERTSTATUS_GOOD && cert_status != 256 V_OCSP_CERTSTATUS_UNKNOWN) { 257 tls_set_errorx(ctx, "ocsp verify failed: revoked cert - %s", 258 OCSP_crl_reason_str(crl_reason)); 259 goto error; 260 } 261 ret = 0; 262 263 error: 264 sk_X509_free(combined); 265 OCSP_CERTID_free(cid); 266 OCSP_BASICRESP_free(br); 267 return ret; 268 } 269 270 /* 271 * Process a raw OCSP response from an OCSP server request. 272 * OCSP details can then be retrieved with tls_peer_ocsp_* functions. 273 * returns 0 if certificate ok, -1 otherwise. 274 */ 275 static int 276 tls_ocsp_process_response_internal(struct tls *ctx, const unsigned char *response, 277 size_t size) 278 { 279 int ret; 280 OCSP_RESPONSE *resp; 281 282 resp = d2i_OCSP_RESPONSE(NULL, &response, size); 283 if (resp == NULL) { 284 tls_ocsp_free(ctx->ocsp); 285 ctx->ocsp = NULL; 286 tls_set_error(ctx, "unable to parse OCSP response"); 287 return -1; 288 } 289 ret = tls_ocsp_verify_response(ctx, resp); 290 OCSP_RESPONSE_free(resp); 291 return ret; 292 } 293 294 /* TLS handshake verification callback for stapled requests */ 295 int 296 tls_ocsp_verify_cb(SSL *ssl, void *arg) 297 { 298 const unsigned char *raw = NULL; 299 int size, res = -1; 300 struct tls *ctx; 301 302 if ((ctx = SSL_get_app_data(ssl)) == NULL) 303 return -1; 304 305 size = SSL_get_tlsext_status_ocsp_resp(ssl, &raw); 306 if (size <= 0) { 307 if (ctx->config->ocsp_require_stapling) { 308 tls_set_errorx(ctx, "no stapled OCSP response provided"); 309 return 0; 310 } 311 return 1; 312 } 313 314 tls_ocsp_free(ctx->ocsp); 315 ctx->ocsp = tls_ocsp_setup_from_peer(ctx); 316 if (ctx->ocsp != NULL) { 317 if (ctx->config->verify_cert == 0 || ctx->config->verify_time == 0) 318 return 1; 319 res = tls_ocsp_process_response_internal(ctx, raw, size); 320 } 321 322 return (res == 0) ? 1 : 0; 323 } 324 325 326 /* Staple the OCSP information in ctx->ocsp to the server handshake. */ 327 int 328 tls_ocsp_stapling_cb(SSL *ssl, void *arg) 329 { 330 struct tls *ctx; 331 unsigned char *ocsp_staple = NULL; 332 int ret = SSL_TLSEXT_ERR_ALERT_FATAL; 333 334 if ((ctx = SSL_get_app_data(ssl)) == NULL) 335 goto err; 336 337 if (ctx->config->keypair == NULL || 338 ctx->config->keypair->ocsp_staple == NULL || 339 ctx->config->keypair->ocsp_staple_len == 0) 340 return SSL_TLSEXT_ERR_NOACK; 341 342 if ((ocsp_staple = malloc(ctx->config->keypair->ocsp_staple_len)) == 343 NULL) 344 goto err; 345 346 memcpy(ocsp_staple, ctx->config->keypair->ocsp_staple, 347 ctx->config->keypair->ocsp_staple_len); 348 if (SSL_set_tlsext_status_ocsp_resp(ctx->ssl_conn, ocsp_staple, 349 ctx->config->keypair->ocsp_staple_len) != 1) 350 goto err; 351 352 ret = SSL_TLSEXT_ERR_OK; 353 err: 354 if (ret != SSL_TLSEXT_ERR_OK) 355 free(ocsp_staple); 356 return ret; 357 } 358 359 /* 360 * Public API 361 */ 362 363 /* Retrieve OCSP URL from peer certificate, if present */ 364 const char * 365 tls_peer_ocsp_url(struct tls *ctx) 366 { 367 if (ctx->ocsp == NULL) 368 return NULL; 369 return ctx->ocsp->ocsp_url; 370 } 371 372 const char * 373 tls_peer_ocsp_result(struct tls *ctx) 374 { 375 if (ctx->ocsp == NULL) 376 return NULL; 377 if (ctx->ocsp->ocsp_result == NULL) 378 return NULL; 379 return ctx->ocsp->ocsp_result->result_msg; 380 } 381 382 int 383 tls_peer_ocsp_response_status(struct tls *ctx) 384 { 385 if (ctx->ocsp == NULL) 386 return -1; 387 if (ctx->ocsp->ocsp_result == NULL) 388 return -1; 389 return ctx->ocsp->ocsp_result->response_status; 390 } 391 392 int 393 tls_peer_ocsp_cert_status(struct tls *ctx) 394 { 395 if (ctx->ocsp == NULL) 396 return -1; 397 if (ctx->ocsp->ocsp_result == NULL) 398 return -1; 399 return ctx->ocsp->ocsp_result->cert_status; 400 } 401 402 int 403 tls_peer_ocsp_crl_reason(struct tls *ctx) 404 { 405 if (ctx->ocsp == NULL) 406 return -1; 407 if (ctx->ocsp->ocsp_result == NULL) 408 return -1; 409 return ctx->ocsp->ocsp_result->crl_reason; 410 } 411 412 time_t 413 tls_peer_ocsp_this_update(struct tls *ctx) 414 { 415 if (ctx->ocsp == NULL) 416 return -1; 417 if (ctx->ocsp->ocsp_result == NULL) 418 return -1; 419 return ctx->ocsp->ocsp_result->this_update; 420 } 421 422 time_t 423 tls_peer_ocsp_next_update(struct tls *ctx) 424 { 425 if (ctx->ocsp == NULL) 426 return -1; 427 if (ctx->ocsp->ocsp_result == NULL) 428 return -1; 429 return ctx->ocsp->ocsp_result->next_update; 430 } 431 432 time_t 433 tls_peer_ocsp_revocation_time(struct tls *ctx) 434 { 435 if (ctx->ocsp == NULL) 436 return -1; 437 if (ctx->ocsp->ocsp_result == NULL) 438 return -1; 439 return ctx->ocsp->ocsp_result->revocation_time; 440 } 441 442 int 443 tls_ocsp_process_response(struct tls *ctx, const unsigned char *response, 444 size_t size) 445 { 446 if ((ctx->state & TLS_HANDSHAKE_COMPLETE) == 0) 447 return -1; 448 return tls_ocsp_process_response_internal(ctx, response, size); 449 } 450