| 1 | /************************************************* |
| 2 | * Exim - an Internet mail transport agent * |
| 3 | *************************************************/ |
| 4 | |
| 5 | /* Copyright (c) University of Cambridge 1995 - 2014 */ |
| 6 | /* See the file NOTICE for conditions of use and distribution. */ |
| 7 | |
| 8 | /* Portions Copyright (c) The OpenSSL Project 1999 */ |
| 9 | |
| 10 | /* This module provides the TLS (aka SSL) support for Exim using the OpenSSL |
| 11 | library. It is #included into the tls.c file when that library is used. The |
| 12 | code herein is based on a patch that was originally contributed by Steve |
| 13 | Haslam. It was adapted from stunnel, a GPL program by Michal Trojnara. |
| 14 | |
| 15 | No cryptographic code is included in Exim. All this module does is to call |
| 16 | functions from the OpenSSL library. */ |
| 17 | |
| 18 | |
| 19 | /* Heading stuff */ |
| 20 | |
| 21 | #include <openssl/lhash.h> |
| 22 | #include <openssl/ssl.h> |
| 23 | #include <openssl/err.h> |
| 24 | #include <openssl/rand.h> |
| 25 | #ifndef DISABLE_OCSP |
| 26 | # include <openssl/ocsp.h> |
| 27 | #endif |
| 28 | |
| 29 | #ifndef DISABLE_OCSP |
| 30 | # define EXIM_OCSP_SKEW_SECONDS (300L) |
| 31 | # define EXIM_OCSP_MAX_AGE (-1L) |
| 32 | #endif |
| 33 | |
| 34 | #if OPENSSL_VERSION_NUMBER >= 0x0090806fL && !defined(OPENSSL_NO_TLSEXT) |
| 35 | # define EXIM_HAVE_OPENSSL_TLSEXT |
| 36 | #endif |
| 37 | |
| 38 | #if !defined(EXIM_HAVE_OPENSSL_TLSEXT) && !defined(DISABLE_OCSP) |
| 39 | # warning "OpenSSL library version too old; define DISABLE_OCSP in Makefile" |
| 40 | # define DISABLE_OCSP |
| 41 | #endif |
| 42 | |
| 43 | /* Structure for collecting random data for seeding. */ |
| 44 | |
| 45 | typedef struct randstuff { |
| 46 | struct timeval tv; |
| 47 | pid_t p; |
| 48 | } randstuff; |
| 49 | |
| 50 | /* Local static variables */ |
| 51 | |
| 52 | static BOOL client_verify_callback_called = FALSE; |
| 53 | static BOOL server_verify_callback_called = FALSE; |
| 54 | static const uschar *sid_ctx = US"exim"; |
| 55 | |
| 56 | /* We have three different contexts to care about. |
| 57 | |
| 58 | Simple case: client, `client_ctx` |
| 59 | As a client, we can be doing a callout or cut-through delivery while receiving |
| 60 | a message. So we have a client context, which should have options initialised |
| 61 | from the SMTP Transport. |
| 62 | |
| 63 | Server: |
| 64 | There are two cases: with and without ServerNameIndication from the client. |
| 65 | Given TLS SNI, we can be using different keys, certs and various other |
| 66 | configuration settings, because they're re-expanded with $tls_sni set. This |
| 67 | allows vhosting with TLS. This SNI is sent in the handshake. |
| 68 | A client might not send SNI, so we need a fallback, and an initial setup too. |
| 69 | So as a server, we start out using `server_ctx`. |
| 70 | If SNI is sent by the client, then we as server, mid-negotiation, try to clone |
| 71 | `server_sni` from `server_ctx` and then initialise settings by re-expanding |
| 72 | configuration. |
| 73 | */ |
| 74 | |
| 75 | static SSL_CTX *client_ctx = NULL; |
| 76 | static SSL_CTX *server_ctx = NULL; |
| 77 | static SSL *client_ssl = NULL; |
| 78 | static SSL *server_ssl = NULL; |
| 79 | |
| 80 | #ifdef EXIM_HAVE_OPENSSL_TLSEXT |
| 81 | static SSL_CTX *server_sni = NULL; |
| 82 | #endif |
| 83 | |
| 84 | static char ssl_errstring[256]; |
| 85 | |
| 86 | static int ssl_session_timeout = 200; |
| 87 | static BOOL client_verify_optional = FALSE; |
| 88 | static BOOL server_verify_optional = FALSE; |
| 89 | |
| 90 | static BOOL reexpand_tls_files_for_sni = FALSE; |
| 91 | |
| 92 | |
| 93 | typedef struct tls_ext_ctx_cb { |
| 94 | uschar *certificate; |
| 95 | uschar *privatekey; |
| 96 | #ifndef DISABLE_OCSP |
| 97 | BOOL is_server; |
| 98 | union { |
| 99 | struct { |
| 100 | uschar *file; |
| 101 | uschar *file_expanded; |
| 102 | OCSP_RESPONSE *response; |
| 103 | } server; |
| 104 | struct { |
| 105 | X509_STORE *verify_store; /* non-null if status requested */ |
| 106 | BOOL verify_required; |
| 107 | } client; |
| 108 | } u_ocsp; |
| 109 | #endif |
| 110 | uschar *dhparam; |
| 111 | /* these are cached from first expand */ |
| 112 | uschar *server_cipher_list; |
| 113 | /* only passed down to tls_error: */ |
| 114 | host_item *host; |
| 115 | |
| 116 | #ifdef EXPERIMENTAL_CERTNAMES |
| 117 | uschar * verify_cert_hostnames; |
| 118 | #endif |
| 119 | } tls_ext_ctx_cb; |
| 120 | |
| 121 | /* should figure out a cleanup of API to handle state preserved per |
| 122 | implementation, for various reasons, which can be void * in the APIs. |
| 123 | For now, we hack around it. */ |
| 124 | tls_ext_ctx_cb *client_static_cbinfo = NULL; |
| 125 | tls_ext_ctx_cb *server_static_cbinfo = NULL; |
| 126 | |
| 127 | static int |
| 128 | setup_certs(SSL_CTX *sctx, uschar *certs, uschar *crl, host_item *host, BOOL optional, |
| 129 | int (*cert_vfy_cb)(int, X509_STORE_CTX *) ); |
| 130 | |
| 131 | /* Callbacks */ |
| 132 | #ifdef EXIM_HAVE_OPENSSL_TLSEXT |
| 133 | static int tls_servername_cb(SSL *s, int *ad ARG_UNUSED, void *arg); |
| 134 | #endif |
| 135 | #ifndef DISABLE_OCSP |
| 136 | static int tls_server_stapling_cb(SSL *s, void *arg); |
| 137 | #endif |
| 138 | |
| 139 | |
| 140 | /************************************************* |
| 141 | * Handle TLS error * |
| 142 | *************************************************/ |
| 143 | |
| 144 | /* Called from lots of places when errors occur before actually starting to do |
| 145 | the TLS handshake, that is, while the session is still in clear. Always returns |
| 146 | DEFER for a server and FAIL for a client so that most calls can use "return |
| 147 | tls_error(...)" to do this processing and then give an appropriate return. A |
| 148 | single function is used for both server and client, because it is called from |
| 149 | some shared functions. |
| 150 | |
| 151 | Argument: |
| 152 | prefix text to include in the logged error |
| 153 | host NULL if setting up a server; |
| 154 | the connected host if setting up a client |
| 155 | msg error message or NULL if we should ask OpenSSL |
| 156 | |
| 157 | Returns: OK/DEFER/FAIL |
| 158 | */ |
| 159 | |
| 160 | static int |
| 161 | tls_error(uschar *prefix, host_item *host, uschar *msg) |
| 162 | { |
| 163 | if (msg == NULL) |
| 164 | { |
| 165 | ERR_error_string(ERR_get_error(), ssl_errstring); |
| 166 | msg = (uschar *)ssl_errstring; |
| 167 | } |
| 168 | |
| 169 | if (host == NULL) |
| 170 | { |
| 171 | uschar *conn_info = smtp_get_connection_info(); |
| 172 | if (Ustrncmp(conn_info, US"SMTP ", 5) == 0) |
| 173 | conn_info += 5; |
| 174 | log_write(0, LOG_MAIN, "TLS error on %s (%s): %s", |
| 175 | conn_info, prefix, msg); |
| 176 | return DEFER; |
| 177 | } |
| 178 | else |
| 179 | { |
| 180 | log_write(0, LOG_MAIN, "TLS error on connection to %s [%s] (%s): %s", |
| 181 | host->name, host->address, prefix, msg); |
| 182 | return FAIL; |
| 183 | } |
| 184 | } |
| 185 | |
| 186 | |
| 187 | |
| 188 | /************************************************* |
| 189 | * Callback to generate RSA key * |
| 190 | *************************************************/ |
| 191 | |
| 192 | /* |
| 193 | Arguments: |
| 194 | s SSL connection |
| 195 | export not used |
| 196 | keylength keylength |
| 197 | |
| 198 | Returns: pointer to generated key |
| 199 | */ |
| 200 | |
| 201 | static RSA * |
| 202 | rsa_callback(SSL *s, int export, int keylength) |
| 203 | { |
| 204 | RSA *rsa_key; |
| 205 | export = export; /* Shut picky compilers up */ |
| 206 | DEBUG(D_tls) debug_printf("Generating %d bit RSA key...\n", keylength); |
| 207 | rsa_key = RSA_generate_key(keylength, RSA_F4, NULL, NULL); |
| 208 | if (rsa_key == NULL) |
| 209 | { |
| 210 | ERR_error_string(ERR_get_error(), ssl_errstring); |
| 211 | log_write(0, LOG_MAIN|LOG_PANIC, "TLS error (RSA_generate_key): %s", |
| 212 | ssl_errstring); |
| 213 | return NULL; |
| 214 | } |
| 215 | return rsa_key; |
| 216 | } |
| 217 | |
| 218 | |
| 219 | |
| 220 | /* Extreme debug |
| 221 | #ifndef DISABLE_OCSP |
| 222 | void |
| 223 | x509_store_dump_cert_s_names(X509_STORE * store) |
| 224 | { |
| 225 | STACK_OF(X509_OBJECT) * roots= store->objs; |
| 226 | int i; |
| 227 | static uschar name[256]; |
| 228 | |
| 229 | for(i= 0; i<sk_X509_OBJECT_num(roots); i++) |
| 230 | { |
| 231 | X509_OBJECT * tmp_obj= sk_X509_OBJECT_value(roots, i); |
| 232 | if(tmp_obj->type == X509_LU_X509) |
| 233 | { |
| 234 | X509 * current_cert= tmp_obj->data.x509; |
| 235 | X509_NAME_oneline(X509_get_subject_name(current_cert), CS name, sizeof(name)); |
| 236 | debug_printf(" %s\n", name); |
| 237 | } |
| 238 | } |
| 239 | } |
| 240 | #endif |
| 241 | */ |
| 242 | |
| 243 | |
| 244 | /************************************************* |
| 245 | * Callback for verification * |
| 246 | *************************************************/ |
| 247 | |
| 248 | /* The SSL library does certificate verification if set up to do so. This |
| 249 | callback has the current yes/no state is in "state". If verification succeeded, |
| 250 | we set up the tls_peerdn string. If verification failed, what happens depends |
| 251 | on whether the client is required to present a verifiable certificate or not. |
| 252 | |
| 253 | If verification is optional, we change the state to yes, but still log the |
| 254 | verification error. For some reason (it really would help to have proper |
| 255 | documentation of OpenSSL), this callback function then gets called again, this |
| 256 | time with state = 1. In fact, that's useful, because we can set up the peerdn |
| 257 | value, but we must take care not to set the private verified flag on the second |
| 258 | time through. |
| 259 | |
| 260 | Note: this function is not called if the client fails to present a certificate |
| 261 | when asked. We get here only if a certificate has been received. Handling of |
| 262 | optional verification for this case is done when requesting SSL to verify, by |
| 263 | setting SSL_VERIFY_FAIL_IF_NO_PEER_CERT in the non-optional case. |
| 264 | |
| 265 | Arguments: |
| 266 | state current yes/no state as 1/0 |
| 267 | x509ctx certificate information. |
| 268 | client TRUE for client startup, FALSE for server startup |
| 269 | |
| 270 | Returns: 1 if verified, 0 if not |
| 271 | */ |
| 272 | |
| 273 | static int |
| 274 | verify_callback(int state, X509_STORE_CTX *x509ctx, |
| 275 | tls_support *tlsp, BOOL *calledp, BOOL *optionalp) |
| 276 | { |
| 277 | X509 * cert = X509_STORE_CTX_get_current_cert(x509ctx); |
| 278 | static uschar txt[256]; |
| 279 | |
| 280 | X509_NAME_oneline(X509_get_subject_name(cert), CS txt, sizeof(txt)); |
| 281 | |
| 282 | if (state == 0) |
| 283 | { |
| 284 | log_write(0, LOG_MAIN, "SSL verify error: depth=%d error=%s cert=%s", |
| 285 | X509_STORE_CTX_get_error_depth(x509ctx), |
| 286 | X509_verify_cert_error_string(X509_STORE_CTX_get_error(x509ctx)), |
| 287 | txt); |
| 288 | tlsp->certificate_verified = FALSE; |
| 289 | *calledp = TRUE; |
| 290 | if (!*optionalp) |
| 291 | { |
| 292 | tlsp->peercert = X509_dup(cert); |
| 293 | return 0; /* reject */ |
| 294 | } |
| 295 | DEBUG(D_tls) debug_printf("SSL verify failure overridden (host in " |
| 296 | "tls_try_verify_hosts)\n"); |
| 297 | } |
| 298 | |
| 299 | else if (X509_STORE_CTX_get_error_depth(x509ctx) != 0) |
| 300 | { |
| 301 | DEBUG(D_tls) debug_printf("SSL verify ok: depth=%d SN=%s\n", |
| 302 | X509_STORE_CTX_get_error_depth(x509ctx), txt); |
| 303 | #ifndef DISABLE_OCSP |
| 304 | if (tlsp == &tls_out && client_static_cbinfo->u_ocsp.client.verify_store) |
| 305 | { /* client, wanting stapling */ |
| 306 | /* Add the server cert's signing chain as the one |
| 307 | for the verification of the OCSP stapled information. */ |
| 308 | |
| 309 | if (!X509_STORE_add_cert(client_static_cbinfo->u_ocsp.client.verify_store, |
| 310 | cert)) |
| 311 | ERR_clear_error(); |
| 312 | } |
| 313 | #endif |
| 314 | } |
| 315 | else |
| 316 | { |
| 317 | #ifdef EXPERIMENTAL_CERTNAMES |
| 318 | uschar * verify_cert_hostnames; |
| 319 | #endif |
| 320 | |
| 321 | tlsp->peerdn = txt; |
| 322 | tlsp->peercert = X509_dup(cert); |
| 323 | |
| 324 | #ifdef EXPERIMENTAL_CERTNAMES |
| 325 | if ( tlsp == &tls_out |
| 326 | && ((verify_cert_hostnames = client_static_cbinfo->verify_cert_hostnames))) |
| 327 | /* client, wanting hostname check */ |
| 328 | |
| 329 | # if OPENSSL_VERSION_NUMBER >= 0x010100000L || OPENSSL_VERSION_NUMBER >= 0x010002000L |
| 330 | # ifndef X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS |
| 331 | # define X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS 0 |
| 332 | # endif |
| 333 | { |
| 334 | int sep = 0; |
| 335 | uschar * list = verify_cert_hostnames; |
| 336 | uschar * name; |
| 337 | int rc; |
| 338 | while ((name = string_nextinlist(&list, &sep, NULL, 0))) |
| 339 | if ((rc = X509_check_host(cert, name, 0, |
| 340 | X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS))) |
| 341 | { |
| 342 | if (rc < 0) |
| 343 | { |
| 344 | log_write(0, LOG_MAIN, "SSL verify error: internal error\n"); |
| 345 | name = NULL; |
| 346 | } |
| 347 | break; |
| 348 | } |
| 349 | if (!name) |
| 350 | { |
| 351 | log_write(0, LOG_MAIN, |
| 352 | "SSL verify error: certificate name mismatch: \"%s\"\n", txt); |
| 353 | return 0; /* reject */ |
| 354 | } |
| 355 | } |
| 356 | # else |
| 357 | if (!tls_is_name_for_cert(verify_cert_hostnames, cert)) |
| 358 | { |
| 359 | log_write(0, LOG_MAIN, |
| 360 | "SSL verify error: certificate name mismatch: \"%s\"\n", txt); |
| 361 | return 0; /* reject */ |
| 362 | } |
| 363 | # endif |
| 364 | #endif |
| 365 | |
| 366 | DEBUG(D_tls) debug_printf("SSL%s verify ok: depth=0 SN=%s\n", |
| 367 | *calledp ? "" : " authenticated", txt); |
| 368 | if (!*calledp) tlsp->certificate_verified = TRUE; |
| 369 | *calledp = TRUE; |
| 370 | } |
| 371 | |
| 372 | return 1; /* accept */ |
| 373 | } |
| 374 | |
| 375 | static int |
| 376 | verify_callback_client(int state, X509_STORE_CTX *x509ctx) |
| 377 | { |
| 378 | return verify_callback(state, x509ctx, &tls_out, &client_verify_callback_called, &client_verify_optional); |
| 379 | } |
| 380 | |
| 381 | static int |
| 382 | verify_callback_server(int state, X509_STORE_CTX *x509ctx) |
| 383 | { |
| 384 | return verify_callback(state, x509ctx, &tls_in, &server_verify_callback_called, &server_verify_optional); |
| 385 | } |
| 386 | |
| 387 | |
| 388 | |
| 389 | /************************************************* |
| 390 | * Information callback * |
| 391 | *************************************************/ |
| 392 | |
| 393 | /* The SSL library functions call this from time to time to indicate what they |
| 394 | are doing. We copy the string to the debugging output when TLS debugging has |
| 395 | been requested. |
| 396 | |
| 397 | Arguments: |
| 398 | s the SSL connection |
| 399 | where |
| 400 | ret |
| 401 | |
| 402 | Returns: nothing |
| 403 | */ |
| 404 | |
| 405 | static void |
| 406 | info_callback(SSL *s, int where, int ret) |
| 407 | { |
| 408 | where = where; |
| 409 | ret = ret; |
| 410 | DEBUG(D_tls) debug_printf("SSL info: %s\n", SSL_state_string_long(s)); |
| 411 | } |
| 412 | |
| 413 | |
| 414 | |
| 415 | /************************************************* |
| 416 | * Initialize for DH * |
| 417 | *************************************************/ |
| 418 | |
| 419 | /* If dhparam is set, expand it, and load up the parameters for DH encryption. |
| 420 | |
| 421 | Arguments: |
| 422 | dhparam DH parameter file or fixed parameter identity string |
| 423 | host connected host, if client; NULL if server |
| 424 | |
| 425 | Returns: TRUE if OK (nothing to set up, or setup worked) |
| 426 | */ |
| 427 | |
| 428 | static BOOL |
| 429 | init_dh(SSL_CTX *sctx, uschar *dhparam, host_item *host) |
| 430 | { |
| 431 | BIO *bio; |
| 432 | DH *dh; |
| 433 | uschar *dhexpanded; |
| 434 | const char *pem; |
| 435 | |
| 436 | if (!expand_check(dhparam, US"tls_dhparam", &dhexpanded)) |
| 437 | return FALSE; |
| 438 | |
| 439 | if (dhexpanded == NULL || *dhexpanded == '\0') |
| 440 | { |
| 441 | bio = BIO_new_mem_buf(CS std_dh_prime_default(), -1); |
| 442 | } |
| 443 | else if (dhexpanded[0] == '/') |
| 444 | { |
| 445 | bio = BIO_new_file(CS dhexpanded, "r"); |
| 446 | if (bio == NULL) |
| 447 | { |
| 448 | tls_error(string_sprintf("could not read dhparams file %s", dhexpanded), |
| 449 | host, US strerror(errno)); |
| 450 | return FALSE; |
| 451 | } |
| 452 | } |
| 453 | else |
| 454 | { |
| 455 | if (Ustrcmp(dhexpanded, "none") == 0) |
| 456 | { |
| 457 | DEBUG(D_tls) debug_printf("Requested no DH parameters.\n"); |
| 458 | return TRUE; |
| 459 | } |
| 460 | |
| 461 | pem = std_dh_prime_named(dhexpanded); |
| 462 | if (!pem) |
| 463 | { |
| 464 | tls_error(string_sprintf("Unknown standard DH prime \"%s\"", dhexpanded), |
| 465 | host, US strerror(errno)); |
| 466 | return FALSE; |
| 467 | } |
| 468 | bio = BIO_new_mem_buf(CS pem, -1); |
| 469 | } |
| 470 | |
| 471 | dh = PEM_read_bio_DHparams(bio, NULL, NULL, NULL); |
| 472 | if (dh == NULL) |
| 473 | { |
| 474 | BIO_free(bio); |
| 475 | tls_error(string_sprintf("Could not read tls_dhparams \"%s\"", dhexpanded), |
| 476 | host, NULL); |
| 477 | return FALSE; |
| 478 | } |
| 479 | |
| 480 | /* Even if it is larger, we silently return success rather than cause things |
| 481 | * to fail out, so that a too-large DH will not knock out all TLS; it's a |
| 482 | * debatable choice. */ |
| 483 | if ((8*DH_size(dh)) > tls_dh_max_bits) |
| 484 | { |
| 485 | DEBUG(D_tls) |
| 486 | debug_printf("dhparams file %d bits, is > tls_dh_max_bits limit of %d", |
| 487 | 8*DH_size(dh), tls_dh_max_bits); |
| 488 | } |
| 489 | else |
| 490 | { |
| 491 | SSL_CTX_set_tmp_dh(sctx, dh); |
| 492 | DEBUG(D_tls) |
| 493 | debug_printf("Diffie-Hellman initialized from %s with %d-bit prime\n", |
| 494 | dhexpanded ? dhexpanded : US"default", 8*DH_size(dh)); |
| 495 | } |
| 496 | |
| 497 | DH_free(dh); |
| 498 | BIO_free(bio); |
| 499 | |
| 500 | return TRUE; |
| 501 | } |
| 502 | |
| 503 | |
| 504 | |
| 505 | |
| 506 | #ifndef DISABLE_OCSP |
| 507 | /************************************************* |
| 508 | * Load OCSP information into state * |
| 509 | *************************************************/ |
| 510 | |
| 511 | /* Called to load the server OCSP response from the given file into memory, once |
| 512 | caller has determined this is needed. Checks validity. Debugs a message |
| 513 | if invalid. |
| 514 | |
| 515 | ASSUMES: single response, for single cert. |
| 516 | |
| 517 | Arguments: |
| 518 | sctx the SSL_CTX* to update |
| 519 | cbinfo various parts of session state |
| 520 | expanded the filename putatively holding an OCSP response |
| 521 | |
| 522 | */ |
| 523 | |
| 524 | static void |
| 525 | ocsp_load_response(SSL_CTX *sctx, tls_ext_ctx_cb *cbinfo, const uschar *expanded) |
| 526 | { |
| 527 | BIO *bio; |
| 528 | OCSP_RESPONSE *resp; |
| 529 | OCSP_BASICRESP *basic_response; |
| 530 | OCSP_SINGLERESP *single_response; |
| 531 | ASN1_GENERALIZEDTIME *rev, *thisupd, *nextupd; |
| 532 | X509_STORE *store; |
| 533 | unsigned long verify_flags; |
| 534 | int status, reason, i; |
| 535 | |
| 536 | cbinfo->u_ocsp.server.file_expanded = string_copy(expanded); |
| 537 | if (cbinfo->u_ocsp.server.response) |
| 538 | { |
| 539 | OCSP_RESPONSE_free(cbinfo->u_ocsp.server.response); |
| 540 | cbinfo->u_ocsp.server.response = NULL; |
| 541 | } |
| 542 | |
| 543 | bio = BIO_new_file(CS cbinfo->u_ocsp.server.file_expanded, "rb"); |
| 544 | if (!bio) |
| 545 | { |
| 546 | DEBUG(D_tls) debug_printf("Failed to open OCSP response file \"%s\"\n", |
| 547 | cbinfo->u_ocsp.server.file_expanded); |
| 548 | return; |
| 549 | } |
| 550 | |
| 551 | resp = d2i_OCSP_RESPONSE_bio(bio, NULL); |
| 552 | BIO_free(bio); |
| 553 | if (!resp) |
| 554 | { |
| 555 | DEBUG(D_tls) debug_printf("Error reading OCSP response.\n"); |
| 556 | return; |
| 557 | } |
| 558 | |
| 559 | status = OCSP_response_status(resp); |
| 560 | if (status != OCSP_RESPONSE_STATUS_SUCCESSFUL) |
| 561 | { |
| 562 | DEBUG(D_tls) debug_printf("OCSP response not valid: %s (%d)\n", |
| 563 | OCSP_response_status_str(status), status); |
| 564 | goto bad; |
| 565 | } |
| 566 | |
| 567 | basic_response = OCSP_response_get1_basic(resp); |
| 568 | if (!basic_response) |
| 569 | { |
| 570 | DEBUG(D_tls) |
| 571 | debug_printf("OCSP response parse error: unable to extract basic response.\n"); |
| 572 | goto bad; |
| 573 | } |
| 574 | |
| 575 | store = SSL_CTX_get_cert_store(sctx); |
| 576 | verify_flags = OCSP_NOVERIFY; /* check sigs, but not purpose */ |
| 577 | |
| 578 | /* May need to expose ability to adjust those flags? |
| 579 | OCSP_NOSIGS OCSP_NOVERIFY OCSP_NOCHAIN OCSP_NOCHECKS OCSP_NOEXPLICIT |
| 580 | OCSP_TRUSTOTHER OCSP_NOINTERN */ |
| 581 | |
| 582 | i = OCSP_basic_verify(basic_response, NULL, store, verify_flags); |
| 583 | if (i <= 0) |
| 584 | { |
| 585 | DEBUG(D_tls) { |
| 586 | ERR_error_string(ERR_get_error(), ssl_errstring); |
| 587 | debug_printf("OCSP response verify failure: %s\n", US ssl_errstring); |
| 588 | } |
| 589 | goto bad; |
| 590 | } |
| 591 | |
| 592 | /* Here's the simplifying assumption: there's only one response, for the |
| 593 | one certificate we use, and nothing for anything else in a chain. If this |
| 594 | proves false, we need to extract a cert id from our issued cert |
| 595 | (tls_certificate) and use that for OCSP_resp_find_status() (which finds the |
| 596 | right cert in the stack and then calls OCSP_single_get0_status()). |
| 597 | |
| 598 | I'm hoping to avoid reworking a bunch more of how we handle state here. */ |
| 599 | single_response = OCSP_resp_get0(basic_response, 0); |
| 600 | if (!single_response) |
| 601 | { |
| 602 | DEBUG(D_tls) |
| 603 | debug_printf("Unable to get first response from OCSP basic response.\n"); |
| 604 | goto bad; |
| 605 | } |
| 606 | |
| 607 | status = OCSP_single_get0_status(single_response, &reason, &rev, &thisupd, &nextupd); |
| 608 | if (status != V_OCSP_CERTSTATUS_GOOD) |
| 609 | { |
| 610 | DEBUG(D_tls) debug_printf("OCSP response bad cert status: %s (%d) %s (%d)\n", |
| 611 | OCSP_cert_status_str(status), status, |
| 612 | OCSP_crl_reason_str(reason), reason); |
| 613 | goto bad; |
| 614 | } |
| 615 | |
| 616 | if (!OCSP_check_validity(thisupd, nextupd, EXIM_OCSP_SKEW_SECONDS, EXIM_OCSP_MAX_AGE)) |
| 617 | { |
| 618 | DEBUG(D_tls) debug_printf("OCSP status invalid times.\n"); |
| 619 | goto bad; |
| 620 | } |
| 621 | |
| 622 | supply_response: |
| 623 | cbinfo->u_ocsp.server.response = resp; |
| 624 | return; |
| 625 | |
| 626 | bad: |
| 627 | if (running_in_test_harness) |
| 628 | { |
| 629 | extern char ** environ; |
| 630 | uschar ** p; |
| 631 | for (p = USS environ; *p != NULL; p++) |
| 632 | if (Ustrncmp(*p, "EXIM_TESTHARNESS_DISABLE_OCSPVALIDITYCHECK", 42) == 0) |
| 633 | { |
| 634 | DEBUG(D_tls) debug_printf("Supplying known bad OCSP response\n"); |
| 635 | goto supply_response; |
| 636 | } |
| 637 | } |
| 638 | return; |
| 639 | } |
| 640 | #endif /*!DISABLE_OCSP*/ |
| 641 | |
| 642 | |
| 643 | |
| 644 | |
| 645 | /************************************************* |
| 646 | * Expand key and cert file specs * |
| 647 | *************************************************/ |
| 648 | |
| 649 | /* Called once during tls_init and possibly again during TLS setup, for a |
| 650 | new context, if Server Name Indication was used and tls_sni was seen in |
| 651 | the certificate string. |
| 652 | |
| 653 | Arguments: |
| 654 | sctx the SSL_CTX* to update |
| 655 | cbinfo various parts of session state |
| 656 | |
| 657 | Returns: OK/DEFER/FAIL |
| 658 | */ |
| 659 | |
| 660 | static int |
| 661 | tls_expand_session_files(SSL_CTX *sctx, tls_ext_ctx_cb *cbinfo) |
| 662 | { |
| 663 | uschar *expanded; |
| 664 | |
| 665 | if (cbinfo->certificate == NULL) |
| 666 | return OK; |
| 667 | |
| 668 | if (Ustrstr(cbinfo->certificate, US"tls_sni") || |
| 669 | Ustrstr(cbinfo->certificate, US"tls_in_sni") || |
| 670 | Ustrstr(cbinfo->certificate, US"tls_out_sni") |
| 671 | ) |
| 672 | reexpand_tls_files_for_sni = TRUE; |
| 673 | |
| 674 | if (!expand_check(cbinfo->certificate, US"tls_certificate", &expanded)) |
| 675 | return DEFER; |
| 676 | |
| 677 | if (expanded != NULL) |
| 678 | { |
| 679 | DEBUG(D_tls) debug_printf("tls_certificate file %s\n", expanded); |
| 680 | if (!SSL_CTX_use_certificate_chain_file(sctx, CS expanded)) |
| 681 | return tls_error(string_sprintf( |
| 682 | "SSL_CTX_use_certificate_chain_file file=%s", expanded), |
| 683 | cbinfo->host, NULL); |
| 684 | } |
| 685 | |
| 686 | if (cbinfo->privatekey != NULL && |
| 687 | !expand_check(cbinfo->privatekey, US"tls_privatekey", &expanded)) |
| 688 | return DEFER; |
| 689 | |
| 690 | /* If expansion was forced to fail, key_expanded will be NULL. If the result |
| 691 | of the expansion is an empty string, ignore it also, and assume the private |
| 692 | key is in the same file as the certificate. */ |
| 693 | |
| 694 | if (expanded != NULL && *expanded != 0) |
| 695 | { |
| 696 | DEBUG(D_tls) debug_printf("tls_privatekey file %s\n", expanded); |
| 697 | if (!SSL_CTX_use_PrivateKey_file(sctx, CS expanded, SSL_FILETYPE_PEM)) |
| 698 | return tls_error(string_sprintf( |
| 699 | "SSL_CTX_use_PrivateKey_file file=%s", expanded), cbinfo->host, NULL); |
| 700 | } |
| 701 | |
| 702 | #ifndef DISABLE_OCSP |
| 703 | if (cbinfo->is_server && cbinfo->u_ocsp.server.file != NULL) |
| 704 | { |
| 705 | if (!expand_check(cbinfo->u_ocsp.server.file, US"tls_ocsp_file", &expanded)) |
| 706 | return DEFER; |
| 707 | |
| 708 | if (expanded != NULL && *expanded != 0) |
| 709 | { |
| 710 | DEBUG(D_tls) debug_printf("tls_ocsp_file %s\n", expanded); |
| 711 | if (cbinfo->u_ocsp.server.file_expanded && |
| 712 | (Ustrcmp(expanded, cbinfo->u_ocsp.server.file_expanded) == 0)) |
| 713 | { |
| 714 | DEBUG(D_tls) |
| 715 | debug_printf("tls_ocsp_file value unchanged, using existing values.\n"); |
| 716 | } else { |
| 717 | ocsp_load_response(sctx, cbinfo, expanded); |
| 718 | } |
| 719 | } |
| 720 | } |
| 721 | #endif |
| 722 | |
| 723 | return OK; |
| 724 | } |
| 725 | |
| 726 | |
| 727 | |
| 728 | |
| 729 | /************************************************* |
| 730 | * Callback to handle SNI * |
| 731 | *************************************************/ |
| 732 | |
| 733 | /* Called when acting as server during the TLS session setup if a Server Name |
| 734 | Indication extension was sent by the client. |
| 735 | |
| 736 | API documentation is OpenSSL s_server.c implementation. |
| 737 | |
| 738 | Arguments: |
| 739 | s SSL* of the current session |
| 740 | ad unknown (part of OpenSSL API) (unused) |
| 741 | arg Callback of "our" registered data |
| 742 | |
| 743 | Returns: SSL_TLSEXT_ERR_{OK,ALERT_WARNING,ALERT_FATAL,NOACK} |
| 744 | */ |
| 745 | |
| 746 | #ifdef EXIM_HAVE_OPENSSL_TLSEXT |
| 747 | static int |
| 748 | tls_servername_cb(SSL *s, int *ad ARG_UNUSED, void *arg) |
| 749 | { |
| 750 | const char *servername = SSL_get_servername(s, TLSEXT_NAMETYPE_host_name); |
| 751 | tls_ext_ctx_cb *cbinfo = (tls_ext_ctx_cb *) arg; |
| 752 | int rc; |
| 753 | int old_pool = store_pool; |
| 754 | |
| 755 | if (!servername) |
| 756 | return SSL_TLSEXT_ERR_OK; |
| 757 | |
| 758 | DEBUG(D_tls) debug_printf("Received TLS SNI \"%s\"%s\n", servername, |
| 759 | reexpand_tls_files_for_sni ? "" : " (unused for certificate selection)"); |
| 760 | |
| 761 | /* Make the extension value available for expansion */ |
| 762 | store_pool = POOL_PERM; |
| 763 | tls_in.sni = string_copy(US servername); |
| 764 | store_pool = old_pool; |
| 765 | |
| 766 | if (!reexpand_tls_files_for_sni) |
| 767 | return SSL_TLSEXT_ERR_OK; |
| 768 | |
| 769 | /* Can't find an SSL_CTX_clone() or equivalent, so we do it manually; |
| 770 | not confident that memcpy wouldn't break some internal reference counting. |
| 771 | Especially since there's a references struct member, which would be off. */ |
| 772 | |
| 773 | server_sni = SSL_CTX_new(SSLv23_server_method()); |
| 774 | if (!server_sni) |
| 775 | { |
| 776 | ERR_error_string(ERR_get_error(), ssl_errstring); |
| 777 | DEBUG(D_tls) debug_printf("SSL_CTX_new() failed: %s\n", ssl_errstring); |
| 778 | return SSL_TLSEXT_ERR_NOACK; |
| 779 | } |
| 780 | |
| 781 | /* Not sure how many of these are actually needed, since SSL object |
| 782 | already exists. Might even need this selfsame callback, for reneg? */ |
| 783 | |
| 784 | SSL_CTX_set_info_callback(server_sni, SSL_CTX_get_info_callback(server_ctx)); |
| 785 | SSL_CTX_set_mode(server_sni, SSL_CTX_get_mode(server_ctx)); |
| 786 | SSL_CTX_set_options(server_sni, SSL_CTX_get_options(server_ctx)); |
| 787 | SSL_CTX_set_timeout(server_sni, SSL_CTX_get_timeout(server_ctx)); |
| 788 | SSL_CTX_set_tlsext_servername_callback(server_sni, tls_servername_cb); |
| 789 | SSL_CTX_set_tlsext_servername_arg(server_sni, cbinfo); |
| 790 | if (cbinfo->server_cipher_list) |
| 791 | SSL_CTX_set_cipher_list(server_sni, CS cbinfo->server_cipher_list); |
| 792 | #ifndef DISABLE_OCSP |
| 793 | if (cbinfo->u_ocsp.server.file) |
| 794 | { |
| 795 | SSL_CTX_set_tlsext_status_cb(server_sni, tls_server_stapling_cb); |
| 796 | SSL_CTX_set_tlsext_status_arg(server_sni, cbinfo); |
| 797 | } |
| 798 | #endif |
| 799 | |
| 800 | rc = setup_certs(server_sni, tls_verify_certificates, tls_crl, NULL, FALSE, verify_callback_server); |
| 801 | if (rc != OK) return SSL_TLSEXT_ERR_NOACK; |
| 802 | |
| 803 | /* do this after setup_certs, because this can require the certs for verifying |
| 804 | OCSP information. */ |
| 805 | rc = tls_expand_session_files(server_sni, cbinfo); |
| 806 | if (rc != OK) return SSL_TLSEXT_ERR_NOACK; |
| 807 | |
| 808 | rc = init_dh(server_sni, cbinfo->dhparam, NULL); |
| 809 | if (rc != OK) return SSL_TLSEXT_ERR_NOACK; |
| 810 | |
| 811 | DEBUG(D_tls) debug_printf("Switching SSL context.\n"); |
| 812 | SSL_set_SSL_CTX(s, server_sni); |
| 813 | |
| 814 | return SSL_TLSEXT_ERR_OK; |
| 815 | } |
| 816 | #endif /* EXIM_HAVE_OPENSSL_TLSEXT */ |
| 817 | |
| 818 | |
| 819 | |
| 820 | |
| 821 | #ifndef DISABLE_OCSP |
| 822 | |
| 823 | /************************************************* |
| 824 | * Callback to handle OCSP Stapling * |
| 825 | *************************************************/ |
| 826 | |
| 827 | /* Called when acting as server during the TLS session setup if the client |
| 828 | requests OCSP information with a Certificate Status Request. |
| 829 | |
| 830 | Documentation via openssl s_server.c and the Apache patch from the OpenSSL |
| 831 | project. |
| 832 | |
| 833 | */ |
| 834 | |
| 835 | static int |
| 836 | tls_server_stapling_cb(SSL *s, void *arg) |
| 837 | { |
| 838 | const tls_ext_ctx_cb *cbinfo = (tls_ext_ctx_cb *) arg; |
| 839 | uschar *response_der; |
| 840 | int response_der_len; |
| 841 | |
| 842 | DEBUG(D_tls) |
| 843 | debug_printf("Received TLS status request (OCSP stapling); %s response.", |
| 844 | cbinfo->u_ocsp.server.response ? "have" : "lack"); |
| 845 | |
| 846 | tls_in.ocsp = OCSP_NOT_RESP; |
| 847 | if (!cbinfo->u_ocsp.server.response) |
| 848 | return SSL_TLSEXT_ERR_NOACK; |
| 849 | |
| 850 | response_der = NULL; |
| 851 | response_der_len = i2d_OCSP_RESPONSE(cbinfo->u_ocsp.server.response, |
| 852 | &response_der); |
| 853 | if (response_der_len <= 0) |
| 854 | return SSL_TLSEXT_ERR_NOACK; |
| 855 | |
| 856 | SSL_set_tlsext_status_ocsp_resp(server_ssl, response_der, response_der_len); |
| 857 | tls_in.ocsp = OCSP_VFIED; |
| 858 | return SSL_TLSEXT_ERR_OK; |
| 859 | } |
| 860 | |
| 861 | |
| 862 | static void |
| 863 | time_print(BIO * bp, const char * str, ASN1_GENERALIZEDTIME * time) |
| 864 | { |
| 865 | BIO_printf(bp, "\t%s: ", str); |
| 866 | ASN1_GENERALIZEDTIME_print(bp, time); |
| 867 | BIO_puts(bp, "\n"); |
| 868 | } |
| 869 | |
| 870 | static int |
| 871 | tls_client_stapling_cb(SSL *s, void *arg) |
| 872 | { |
| 873 | tls_ext_ctx_cb * cbinfo = arg; |
| 874 | const unsigned char * p; |
| 875 | int len; |
| 876 | OCSP_RESPONSE * rsp; |
| 877 | OCSP_BASICRESP * bs; |
| 878 | int i; |
| 879 | |
| 880 | DEBUG(D_tls) debug_printf("Received TLS status response (OCSP stapling):"); |
| 881 | len = SSL_get_tlsext_status_ocsp_resp(s, &p); |
| 882 | if(!p) |
| 883 | { |
| 884 | /* Expect this when we requested ocsp but got none */ |
| 885 | if ( cbinfo->u_ocsp.client.verify_required |
| 886 | && log_extra_selector & LX_tls_cipher) |
| 887 | log_write(0, LOG_MAIN, "Received TLS status callback, null content"); |
| 888 | else |
| 889 | DEBUG(D_tls) debug_printf(" null\n"); |
| 890 | return cbinfo->u_ocsp.client.verify_required ? 0 : 1; |
| 891 | } |
| 892 | |
| 893 | if(!(rsp = d2i_OCSP_RESPONSE(NULL, &p, len))) |
| 894 | { |
| 895 | tls_out.ocsp = OCSP_FAILED; |
| 896 | if (log_extra_selector & LX_tls_cipher) |
| 897 | log_write(0, LOG_MAIN, "Received TLS status response, parse error"); |
| 898 | else |
| 899 | DEBUG(D_tls) debug_printf(" parse error\n"); |
| 900 | return 0; |
| 901 | } |
| 902 | |
| 903 | if(!(bs = OCSP_response_get1_basic(rsp))) |
| 904 | { |
| 905 | tls_out.ocsp = OCSP_FAILED; |
| 906 | if (log_extra_selector & LX_tls_cipher) |
| 907 | log_write(0, LOG_MAIN, "Received TLS status response, error parsing response"); |
| 908 | else |
| 909 | DEBUG(D_tls) debug_printf(" error parsing response\n"); |
| 910 | OCSP_RESPONSE_free(rsp); |
| 911 | return 0; |
| 912 | } |
| 913 | |
| 914 | /* We'd check the nonce here if we'd put one in the request. */ |
| 915 | /* However that would defeat cacheability on the server so we don't. */ |
| 916 | |
| 917 | /* This section of code reworked from OpenSSL apps source; |
| 918 | The OpenSSL Project retains copyright: |
| 919 | Copyright (c) 1999 The OpenSSL Project. All rights reserved. |
| 920 | */ |
| 921 | { |
| 922 | BIO * bp = NULL; |
| 923 | int status, reason; |
| 924 | ASN1_GENERALIZEDTIME *rev, *thisupd, *nextupd; |
| 925 | |
| 926 | DEBUG(D_tls) bp = BIO_new_fp(stderr, BIO_NOCLOSE); |
| 927 | |
| 928 | /*OCSP_RESPONSE_print(bp, rsp, 0); extreme debug: stapling content */ |
| 929 | |
| 930 | /* Use the chain that verified the server cert to verify the stapled info */ |
| 931 | /* DEBUG(D_tls) x509_store_dump_cert_s_names(cbinfo->u_ocsp.client.verify_store); */ |
| 932 | |
| 933 | if ((i = OCSP_basic_verify(bs, NULL, |
| 934 | cbinfo->u_ocsp.client.verify_store, 0)) <= 0) |
| 935 | { |
| 936 | tls_out.ocsp = OCSP_FAILED; |
| 937 | BIO_printf(bp, "OCSP response verify failure\n"); |
| 938 | ERR_print_errors(bp); |
| 939 | i = cbinfo->u_ocsp.client.verify_required ? 0 : 1; |
| 940 | goto out; |
| 941 | } |
| 942 | |
| 943 | BIO_printf(bp, "OCSP response well-formed and signed OK\n"); |
| 944 | |
| 945 | { |
| 946 | STACK_OF(OCSP_SINGLERESP) * sresp = bs->tbsResponseData->responses; |
| 947 | OCSP_SINGLERESP * single; |
| 948 | |
| 949 | if (sk_OCSP_SINGLERESP_num(sresp) != 1) |
| 950 | { |
| 951 | tls_out.ocsp = OCSP_FAILED; |
| 952 | log_write(0, LOG_MAIN, "OCSP stapling " |
| 953 | "with multiple responses not handled"); |
| 954 | i = cbinfo->u_ocsp.client.verify_required ? 0 : 1; |
| 955 | goto out; |
| 956 | } |
| 957 | single = OCSP_resp_get0(bs, 0); |
| 958 | status = OCSP_single_get0_status(single, &reason, &rev, |
| 959 | &thisupd, &nextupd); |
| 960 | } |
| 961 | |
| 962 | DEBUG(D_tls) time_print(bp, "This OCSP Update", thisupd); |
| 963 | DEBUG(D_tls) if(nextupd) time_print(bp, "Next OCSP Update", nextupd); |
| 964 | if (!OCSP_check_validity(thisupd, nextupd, |
| 965 | EXIM_OCSP_SKEW_SECONDS, EXIM_OCSP_MAX_AGE)) |
| 966 | { |
| 967 | tls_out.ocsp = OCSP_FAILED; |
| 968 | DEBUG(D_tls) ERR_print_errors(bp); |
| 969 | log_write(0, LOG_MAIN, "Server OSCP dates invalid"); |
| 970 | i = cbinfo->u_ocsp.client.verify_required ? 0 : 1; |
| 971 | } |
| 972 | else |
| 973 | { |
| 974 | DEBUG(D_tls) BIO_printf(bp, "Certificate status: %s\n", |
| 975 | OCSP_cert_status_str(status)); |
| 976 | switch(status) |
| 977 | { |
| 978 | case V_OCSP_CERTSTATUS_GOOD: |
| 979 | tls_out.ocsp = OCSP_VFIED; |
| 980 | i = 1; |
| 981 | break; |
| 982 | case V_OCSP_CERTSTATUS_REVOKED: |
| 983 | tls_out.ocsp = OCSP_FAILED; |
| 984 | log_write(0, LOG_MAIN, "Server certificate revoked%s%s", |
| 985 | reason != -1 ? "; reason: " : "", |
| 986 | reason != -1 ? OCSP_crl_reason_str(reason) : ""); |
| 987 | DEBUG(D_tls) time_print(bp, "Revocation Time", rev); |
| 988 | i = cbinfo->u_ocsp.client.verify_required ? 0 : 1; |
| 989 | break; |
| 990 | default: |
| 991 | tls_out.ocsp = OCSP_FAILED; |
| 992 | log_write(0, LOG_MAIN, |
| 993 | "Server certificate status unknown, in OCSP stapling"); |
| 994 | i = cbinfo->u_ocsp.client.verify_required ? 0 : 1; |
| 995 | break; |
| 996 | } |
| 997 | } |
| 998 | out: |
| 999 | BIO_free(bp); |
| 1000 | } |
| 1001 | |
| 1002 | OCSP_RESPONSE_free(rsp); |
| 1003 | return i; |
| 1004 | } |
| 1005 | #endif /*!DISABLE_OCSP*/ |
| 1006 | |
| 1007 | |
| 1008 | |
| 1009 | /************************************************* |
| 1010 | * Initialize for TLS * |
| 1011 | *************************************************/ |
| 1012 | |
| 1013 | /* Called from both server and client code, to do preliminary initialization |
| 1014 | of the library. We allocate and return a context structure. |
| 1015 | |
| 1016 | Arguments: |
| 1017 | host connected host, if client; NULL if server |
| 1018 | dhparam DH parameter file |
| 1019 | certificate certificate file |
| 1020 | privatekey private key |
| 1021 | ocsp_file file of stapling info (server); flag for require ocsp (client) |
| 1022 | addr address if client; NULL if server (for some randomness) |
| 1023 | cbp place to put allocated context |
| 1024 | |
| 1025 | Returns: OK/DEFER/FAIL |
| 1026 | */ |
| 1027 | |
| 1028 | static int |
| 1029 | tls_init(SSL_CTX **ctxp, host_item *host, uschar *dhparam, uschar *certificate, |
| 1030 | uschar *privatekey, |
| 1031 | #ifndef DISABLE_OCSP |
| 1032 | uschar *ocsp_file, |
| 1033 | #endif |
| 1034 | address_item *addr, tls_ext_ctx_cb ** cbp) |
| 1035 | { |
| 1036 | long init_options; |
| 1037 | int rc; |
| 1038 | BOOL okay; |
| 1039 | tls_ext_ctx_cb *cbinfo; |
| 1040 | |
| 1041 | cbinfo = store_malloc(sizeof(tls_ext_ctx_cb)); |
| 1042 | cbinfo->certificate = certificate; |
| 1043 | cbinfo->privatekey = privatekey; |
| 1044 | #ifndef DISABLE_OCSP |
| 1045 | if ((cbinfo->is_server = host==NULL)) |
| 1046 | { |
| 1047 | cbinfo->u_ocsp.server.file = ocsp_file; |
| 1048 | cbinfo->u_ocsp.server.file_expanded = NULL; |
| 1049 | cbinfo->u_ocsp.server.response = NULL; |
| 1050 | } |
| 1051 | else |
| 1052 | cbinfo->u_ocsp.client.verify_store = NULL; |
| 1053 | #endif |
| 1054 | cbinfo->dhparam = dhparam; |
| 1055 | cbinfo->host = host; |
| 1056 | |
| 1057 | SSL_load_error_strings(); /* basic set up */ |
| 1058 | OpenSSL_add_ssl_algorithms(); |
| 1059 | |
| 1060 | #if (OPENSSL_VERSION_NUMBER >= 0x0090800fL) && !defined(OPENSSL_NO_SHA256) |
| 1061 | /* SHA256 is becoming ever more popular. This makes sure it gets added to the |
| 1062 | list of available digests. */ |
| 1063 | EVP_add_digest(EVP_sha256()); |
| 1064 | #endif |
| 1065 | |
| 1066 | /* Create a context. |
| 1067 | The OpenSSL docs in 1.0.1b have not been updated to clarify TLS variant |
| 1068 | negotiation in the different methods; as far as I can tell, the only |
| 1069 | *_{server,client}_method which allows negotiation is SSLv23, which exists even |
| 1070 | when OpenSSL is built without SSLv2 support. |
| 1071 | By disabling with openssl_options, we can let admins re-enable with the |
| 1072 | existing knob. */ |
| 1073 | |
| 1074 | *ctxp = SSL_CTX_new((host == NULL)? |
| 1075 | SSLv23_server_method() : SSLv23_client_method()); |
| 1076 | |
| 1077 | if (*ctxp == NULL) return tls_error(US"SSL_CTX_new", host, NULL); |
| 1078 | |
| 1079 | /* It turns out that we need to seed the random number generator this early in |
| 1080 | order to get the full complement of ciphers to work. It took me roughly a day |
| 1081 | of work to discover this by experiment. |
| 1082 | |
| 1083 | On systems that have /dev/urandom, SSL may automatically seed itself from |
| 1084 | there. Otherwise, we have to make something up as best we can. Double check |
| 1085 | afterwards. */ |
| 1086 | |
| 1087 | if (!RAND_status()) |
| 1088 | { |
| 1089 | randstuff r; |
| 1090 | gettimeofday(&r.tv, NULL); |
| 1091 | r.p = getpid(); |
| 1092 | |
| 1093 | RAND_seed((uschar *)(&r), sizeof(r)); |
| 1094 | RAND_seed((uschar *)big_buffer, big_buffer_size); |
| 1095 | if (addr != NULL) RAND_seed((uschar *)addr, sizeof(addr)); |
| 1096 | |
| 1097 | if (!RAND_status()) |
| 1098 | return tls_error(US"RAND_status", host, |
| 1099 | US"unable to seed random number generator"); |
| 1100 | } |
| 1101 | |
| 1102 | /* Set up the information callback, which outputs if debugging is at a suitable |
| 1103 | level. */ |
| 1104 | |
| 1105 | SSL_CTX_set_info_callback(*ctxp, (void (*)())info_callback); |
| 1106 | |
| 1107 | /* Automatically re-try reads/writes after renegotiation. */ |
| 1108 | (void) SSL_CTX_set_mode(*ctxp, SSL_MODE_AUTO_RETRY); |
| 1109 | |
| 1110 | /* Apply administrator-supplied work-arounds. |
| 1111 | Historically we applied just one requested option, |
| 1112 | SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS, but when bug 994 requested a second, we |
| 1113 | moved to an administrator-controlled list of options to specify and |
| 1114 | grandfathered in the first one as the default value for "openssl_options". |
| 1115 | |
| 1116 | No OpenSSL version number checks: the options we accept depend upon the |
| 1117 | availability of the option value macros from OpenSSL. */ |
| 1118 | |
| 1119 | okay = tls_openssl_options_parse(openssl_options, &init_options); |
| 1120 | if (!okay) |
| 1121 | return tls_error(US"openssl_options parsing failed", host, NULL); |
| 1122 | |
| 1123 | if (init_options) |
| 1124 | { |
| 1125 | DEBUG(D_tls) debug_printf("setting SSL CTX options: %#lx\n", init_options); |
| 1126 | if (!(SSL_CTX_set_options(*ctxp, init_options))) |
| 1127 | return tls_error(string_sprintf( |
| 1128 | "SSL_CTX_set_option(%#lx)", init_options), host, NULL); |
| 1129 | } |
| 1130 | else |
| 1131 | DEBUG(D_tls) debug_printf("no SSL CTX options to set\n"); |
| 1132 | |
| 1133 | /* Initialize with DH parameters if supplied */ |
| 1134 | |
| 1135 | if (!init_dh(*ctxp, dhparam, host)) return DEFER; |
| 1136 | |
| 1137 | /* Set up certificate and key (and perhaps OCSP info) */ |
| 1138 | |
| 1139 | rc = tls_expand_session_files(*ctxp, cbinfo); |
| 1140 | if (rc != OK) return rc; |
| 1141 | |
| 1142 | /* If we need to handle SNI, do so */ |
| 1143 | #ifdef EXIM_HAVE_OPENSSL_TLSEXT |
| 1144 | if (host == NULL) /* server */ |
| 1145 | { |
| 1146 | # ifndef DISABLE_OCSP |
| 1147 | /* We check u_ocsp.server.file, not server.response, because we care about if |
| 1148 | the option exists, not what the current expansion might be, as SNI might |
| 1149 | change the certificate and OCSP file in use between now and the time the |
| 1150 | callback is invoked. */ |
| 1151 | if (cbinfo->u_ocsp.server.file) |
| 1152 | { |
| 1153 | SSL_CTX_set_tlsext_status_cb(server_ctx, tls_server_stapling_cb); |
| 1154 | SSL_CTX_set_tlsext_status_arg(server_ctx, cbinfo); |
| 1155 | } |
| 1156 | # endif |
| 1157 | /* We always do this, so that $tls_sni is available even if not used in |
| 1158 | tls_certificate */ |
| 1159 | SSL_CTX_set_tlsext_servername_callback(*ctxp, tls_servername_cb); |
| 1160 | SSL_CTX_set_tlsext_servername_arg(*ctxp, cbinfo); |
| 1161 | } |
| 1162 | # ifndef DISABLE_OCSP |
| 1163 | else /* client */ |
| 1164 | if(ocsp_file) /* wanting stapling */ |
| 1165 | { |
| 1166 | if (!(cbinfo->u_ocsp.client.verify_store = X509_STORE_new())) |
| 1167 | { |
| 1168 | DEBUG(D_tls) debug_printf("failed to create store for stapling verify\n"); |
| 1169 | return FAIL; |
| 1170 | } |
| 1171 | SSL_CTX_set_tlsext_status_cb(*ctxp, tls_client_stapling_cb); |
| 1172 | SSL_CTX_set_tlsext_status_arg(*ctxp, cbinfo); |
| 1173 | } |
| 1174 | # endif |
| 1175 | #endif |
| 1176 | |
| 1177 | #ifdef EXPERIMENTAL_CERTNAMES |
| 1178 | cbinfo->verify_cert_hostnames = NULL; |
| 1179 | #endif |
| 1180 | |
| 1181 | /* Set up the RSA callback */ |
| 1182 | |
| 1183 | SSL_CTX_set_tmp_rsa_callback(*ctxp, rsa_callback); |
| 1184 | |
| 1185 | /* Finally, set the timeout, and we are done */ |
| 1186 | |
| 1187 | SSL_CTX_set_timeout(*ctxp, ssl_session_timeout); |
| 1188 | DEBUG(D_tls) debug_printf("Initialized TLS\n"); |
| 1189 | |
| 1190 | *cbp = cbinfo; |
| 1191 | |
| 1192 | return OK; |
| 1193 | } |
| 1194 | |
| 1195 | |
| 1196 | |
| 1197 | |
| 1198 | /************************************************* |
| 1199 | * Get name of cipher in use * |
| 1200 | *************************************************/ |
| 1201 | |
| 1202 | /* |
| 1203 | Argument: pointer to an SSL structure for the connection |
| 1204 | buffer to use for answer |
| 1205 | size of buffer |
| 1206 | pointer to number of bits for cipher |
| 1207 | Returns: nothing |
| 1208 | */ |
| 1209 | |
| 1210 | static void |
| 1211 | construct_cipher_name(SSL *ssl, uschar *cipherbuf, int bsize, int *bits) |
| 1212 | { |
| 1213 | /* With OpenSSL 1.0.0a, this needs to be const but the documentation doesn't |
| 1214 | yet reflect that. It should be a safe change anyway, even 0.9.8 versions have |
| 1215 | the accessor functions use const in the prototype. */ |
| 1216 | const SSL_CIPHER *c; |
| 1217 | const uschar *ver; |
| 1218 | |
| 1219 | ver = (const uschar *)SSL_get_version(ssl); |
| 1220 | |
| 1221 | c = (const SSL_CIPHER *) SSL_get_current_cipher(ssl); |
| 1222 | SSL_CIPHER_get_bits(c, bits); |
| 1223 | |
| 1224 | string_format(cipherbuf, bsize, "%s:%s:%u", ver, |
| 1225 | SSL_CIPHER_get_name(c), *bits); |
| 1226 | |
| 1227 | DEBUG(D_tls) debug_printf("Cipher: %s\n", cipherbuf); |
| 1228 | } |
| 1229 | |
| 1230 | |
| 1231 | |
| 1232 | |
| 1233 | |
| 1234 | /************************************************* |
| 1235 | * Set up for verifying certificates * |
| 1236 | *************************************************/ |
| 1237 | |
| 1238 | /* Called by both client and server startup |
| 1239 | |
| 1240 | Arguments: |
| 1241 | sctx SSL_CTX* to initialise |
| 1242 | certs certs file or NULL |
| 1243 | crl CRL file or NULL |
| 1244 | host NULL in a server; the remote host in a client |
| 1245 | optional TRUE if called from a server for a host in tls_try_verify_hosts; |
| 1246 | otherwise passed as FALSE |
| 1247 | cert_vfy_cb Callback function for certificate verification |
| 1248 | |
| 1249 | Returns: OK/DEFER/FAIL |
| 1250 | */ |
| 1251 | |
| 1252 | static int |
| 1253 | setup_certs(SSL_CTX *sctx, uschar *certs, uschar *crl, host_item *host, BOOL optional, |
| 1254 | int (*cert_vfy_cb)(int, X509_STORE_CTX *) ) |
| 1255 | { |
| 1256 | uschar *expcerts, *expcrl; |
| 1257 | |
| 1258 | if (!expand_check(certs, US"tls_verify_certificates", &expcerts)) |
| 1259 | return DEFER; |
| 1260 | |
| 1261 | if (expcerts != NULL && *expcerts != '\0') |
| 1262 | { |
| 1263 | struct stat statbuf; |
| 1264 | if (!SSL_CTX_set_default_verify_paths(sctx)) |
| 1265 | return tls_error(US"SSL_CTX_set_default_verify_paths", host, NULL); |
| 1266 | |
| 1267 | if (Ustat(expcerts, &statbuf) < 0) |
| 1268 | { |
| 1269 | log_write(0, LOG_MAIN|LOG_PANIC, |
| 1270 | "failed to stat %s for certificates", expcerts); |
| 1271 | return DEFER; |
| 1272 | } |
| 1273 | else |
| 1274 | { |
| 1275 | uschar *file, *dir; |
| 1276 | if ((statbuf.st_mode & S_IFMT) == S_IFDIR) |
| 1277 | { file = NULL; dir = expcerts; } |
| 1278 | else |
| 1279 | { file = expcerts; dir = NULL; } |
| 1280 | |
| 1281 | /* If a certificate file is empty, the next function fails with an |
| 1282 | unhelpful error message. If we skip it, we get the correct behaviour (no |
| 1283 | certificates are recognized, but the error message is still misleading (it |
| 1284 | says no certificate was supplied.) But this is better. */ |
| 1285 | |
| 1286 | if ((file == NULL || statbuf.st_size > 0) && |
| 1287 | !SSL_CTX_load_verify_locations(sctx, CS file, CS dir)) |
| 1288 | return tls_error(US"SSL_CTX_load_verify_locations", host, NULL); |
| 1289 | |
| 1290 | if (file != NULL) |
| 1291 | { |
| 1292 | SSL_CTX_set_client_CA_list(sctx, SSL_load_client_CA_file(CS file)); |
| 1293 | } |
| 1294 | } |
| 1295 | |
| 1296 | /* Handle a certificate revocation list. */ |
| 1297 | |
| 1298 | #if OPENSSL_VERSION_NUMBER > 0x00907000L |
| 1299 | |
| 1300 | /* This bit of code is now the version supplied by Lars Mainka. (I have |
| 1301 | * merely reformatted it into the Exim code style.) |
| 1302 | |
| 1303 | * "From here I changed the code to add support for multiple crl's |
| 1304 | * in pem format in one file or to support hashed directory entries in |
| 1305 | * pem format instead of a file. This method now uses the library function |
| 1306 | * X509_STORE_load_locations to add the CRL location to the SSL context. |
| 1307 | * OpenSSL will then handle the verify against CA certs and CRLs by |
| 1308 | * itself in the verify callback." */ |
| 1309 | |
| 1310 | if (!expand_check(crl, US"tls_crl", &expcrl)) return DEFER; |
| 1311 | if (expcrl != NULL && *expcrl != 0) |
| 1312 | { |
| 1313 | struct stat statbufcrl; |
| 1314 | if (Ustat(expcrl, &statbufcrl) < 0) |
| 1315 | { |
| 1316 | log_write(0, LOG_MAIN|LOG_PANIC, |
| 1317 | "failed to stat %s for certificates revocation lists", expcrl); |
| 1318 | return DEFER; |
| 1319 | } |
| 1320 | else |
| 1321 | { |
| 1322 | /* is it a file or directory? */ |
| 1323 | uschar *file, *dir; |
| 1324 | X509_STORE *cvstore = SSL_CTX_get_cert_store(sctx); |
| 1325 | if ((statbufcrl.st_mode & S_IFMT) == S_IFDIR) |
| 1326 | { |
| 1327 | file = NULL; |
| 1328 | dir = expcrl; |
| 1329 | DEBUG(D_tls) debug_printf("SSL CRL value is a directory %s\n", dir); |
| 1330 | } |
| 1331 | else |
| 1332 | { |
| 1333 | file = expcrl; |
| 1334 | dir = NULL; |
| 1335 | DEBUG(D_tls) debug_printf("SSL CRL value is a file %s\n", file); |
| 1336 | } |
| 1337 | if (X509_STORE_load_locations(cvstore, CS file, CS dir) == 0) |
| 1338 | return tls_error(US"X509_STORE_load_locations", host, NULL); |
| 1339 | |
| 1340 | /* setting the flags to check against the complete crl chain */ |
| 1341 | |
| 1342 | X509_STORE_set_flags(cvstore, |
| 1343 | X509_V_FLAG_CRL_CHECK|X509_V_FLAG_CRL_CHECK_ALL); |
| 1344 | } |
| 1345 | } |
| 1346 | |
| 1347 | #endif /* OPENSSL_VERSION_NUMBER > 0x00907000L */ |
| 1348 | |
| 1349 | /* If verification is optional, don't fail if no certificate */ |
| 1350 | |
| 1351 | SSL_CTX_set_verify(sctx, |
| 1352 | SSL_VERIFY_PEER | (optional? 0 : SSL_VERIFY_FAIL_IF_NO_PEER_CERT), |
| 1353 | cert_vfy_cb); |
| 1354 | } |
| 1355 | |
| 1356 | return OK; |
| 1357 | } |
| 1358 | |
| 1359 | |
| 1360 | |
| 1361 | /************************************************* |
| 1362 | * Start a TLS session in a server * |
| 1363 | *************************************************/ |
| 1364 | |
| 1365 | /* This is called when Exim is running as a server, after having received |
| 1366 | the STARTTLS command. It must respond to that command, and then negotiate |
| 1367 | a TLS session. |
| 1368 | |
| 1369 | Arguments: |
| 1370 | require_ciphers allowed ciphers |
| 1371 | |
| 1372 | Returns: OK on success |
| 1373 | DEFER for errors before the start of the negotiation |
| 1374 | FAIL for errors during the negotation; the server can't |
| 1375 | continue running. |
| 1376 | */ |
| 1377 | |
| 1378 | int |
| 1379 | tls_server_start(const uschar *require_ciphers) |
| 1380 | { |
| 1381 | int rc; |
| 1382 | uschar *expciphers; |
| 1383 | tls_ext_ctx_cb *cbinfo; |
| 1384 | static uschar cipherbuf[256]; |
| 1385 | |
| 1386 | /* Check for previous activation */ |
| 1387 | |
| 1388 | if (tls_in.active >= 0) |
| 1389 | { |
| 1390 | tls_error(US"STARTTLS received after TLS started", NULL, US""); |
| 1391 | smtp_printf("554 Already in TLS\r\n"); |
| 1392 | return FAIL; |
| 1393 | } |
| 1394 | |
| 1395 | /* Initialize the SSL library. If it fails, it will already have logged |
| 1396 | the error. */ |
| 1397 | |
| 1398 | rc = tls_init(&server_ctx, NULL, tls_dhparam, tls_certificate, tls_privatekey, |
| 1399 | #ifndef DISABLE_OCSP |
| 1400 | tls_ocsp_file, |
| 1401 | #endif |
| 1402 | NULL, &server_static_cbinfo); |
| 1403 | if (rc != OK) return rc; |
| 1404 | cbinfo = server_static_cbinfo; |
| 1405 | |
| 1406 | if (!expand_check(require_ciphers, US"tls_require_ciphers", &expciphers)) |
| 1407 | return FAIL; |
| 1408 | |
| 1409 | /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they |
| 1410 | were historically separated by underscores. So that I can use either form in my |
| 1411 | tests, and also for general convenience, we turn underscores into hyphens here. |
| 1412 | */ |
| 1413 | |
| 1414 | if (expciphers != NULL) |
| 1415 | { |
| 1416 | uschar *s = expciphers; |
| 1417 | while (*s != 0) { if (*s == '_') *s = '-'; s++; } |
| 1418 | DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers); |
| 1419 | if (!SSL_CTX_set_cipher_list(server_ctx, CS expciphers)) |
| 1420 | return tls_error(US"SSL_CTX_set_cipher_list", NULL, NULL); |
| 1421 | cbinfo->server_cipher_list = expciphers; |
| 1422 | } |
| 1423 | |
| 1424 | /* If this is a host for which certificate verification is mandatory or |
| 1425 | optional, set up appropriately. */ |
| 1426 | |
| 1427 | tls_in.certificate_verified = FALSE; |
| 1428 | server_verify_callback_called = FALSE; |
| 1429 | |
| 1430 | if (verify_check_host(&tls_verify_hosts) == OK) |
| 1431 | { |
| 1432 | rc = setup_certs(server_ctx, tls_verify_certificates, tls_crl, NULL, |
| 1433 | FALSE, verify_callback_server); |
| 1434 | if (rc != OK) return rc; |
| 1435 | server_verify_optional = FALSE; |
| 1436 | } |
| 1437 | else if (verify_check_host(&tls_try_verify_hosts) == OK) |
| 1438 | { |
| 1439 | rc = setup_certs(server_ctx, tls_verify_certificates, tls_crl, NULL, |
| 1440 | TRUE, verify_callback_server); |
| 1441 | if (rc != OK) return rc; |
| 1442 | server_verify_optional = TRUE; |
| 1443 | } |
| 1444 | |
| 1445 | /* Prepare for new connection */ |
| 1446 | |
| 1447 | if ((server_ssl = SSL_new(server_ctx)) == NULL) return tls_error(US"SSL_new", NULL, NULL); |
| 1448 | |
| 1449 | /* Warning: we used to SSL_clear(ssl) here, it was removed. |
| 1450 | * |
| 1451 | * With the SSL_clear(), we get strange interoperability bugs with |
| 1452 | * OpenSSL 1.0.1b and TLS1.1/1.2. It looks as though this may be a bug in |
| 1453 | * OpenSSL itself, as a clear should not lead to inability to follow protocols. |
| 1454 | * |
| 1455 | * The SSL_clear() call is to let an existing SSL* be reused, typically after |
| 1456 | * session shutdown. In this case, we have a brand new object and there's no |
| 1457 | * obvious reason to immediately clear it. I'm guessing that this was |
| 1458 | * originally added because of incomplete initialisation which the clear fixed, |
| 1459 | * in some historic release. |
| 1460 | */ |
| 1461 | |
| 1462 | /* Set context and tell client to go ahead, except in the case of TLS startup |
| 1463 | on connection, where outputting anything now upsets the clients and tends to |
| 1464 | make them disconnect. We need to have an explicit fflush() here, to force out |
| 1465 | the response. Other smtp_printf() calls do not need it, because in non-TLS |
| 1466 | mode, the fflush() happens when smtp_getc() is called. */ |
| 1467 | |
| 1468 | SSL_set_session_id_context(server_ssl, sid_ctx, Ustrlen(sid_ctx)); |
| 1469 | if (!tls_in.on_connect) |
| 1470 | { |
| 1471 | smtp_printf("220 TLS go ahead\r\n"); |
| 1472 | fflush(smtp_out); |
| 1473 | } |
| 1474 | |
| 1475 | /* Now negotiate the TLS session. We put our own timer on it, since it seems |
| 1476 | that the OpenSSL library doesn't. */ |
| 1477 | |
| 1478 | SSL_set_wfd(server_ssl, fileno(smtp_out)); |
| 1479 | SSL_set_rfd(server_ssl, fileno(smtp_in)); |
| 1480 | SSL_set_accept_state(server_ssl); |
| 1481 | |
| 1482 | DEBUG(D_tls) debug_printf("Calling SSL_accept\n"); |
| 1483 | |
| 1484 | sigalrm_seen = FALSE; |
| 1485 | if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout); |
| 1486 | rc = SSL_accept(server_ssl); |
| 1487 | alarm(0); |
| 1488 | |
| 1489 | if (rc <= 0) |
| 1490 | { |
| 1491 | tls_error(US"SSL_accept", NULL, sigalrm_seen ? US"timed out" : NULL); |
| 1492 | if (ERR_get_error() == 0) |
| 1493 | log_write(0, LOG_MAIN, |
| 1494 | "TLS client disconnected cleanly (rejected our certificate?)"); |
| 1495 | return FAIL; |
| 1496 | } |
| 1497 | |
| 1498 | DEBUG(D_tls) debug_printf("SSL_accept was successful\n"); |
| 1499 | |
| 1500 | /* TLS has been set up. Adjust the input functions to read via TLS, |
| 1501 | and initialize things. */ |
| 1502 | |
| 1503 | construct_cipher_name(server_ssl, cipherbuf, sizeof(cipherbuf), &tls_in.bits); |
| 1504 | tls_in.cipher = cipherbuf; |
| 1505 | |
| 1506 | DEBUG(D_tls) |
| 1507 | { |
| 1508 | uschar buf[2048]; |
| 1509 | if (SSL_get_shared_ciphers(server_ssl, CS buf, sizeof(buf)) != NULL) |
| 1510 | debug_printf("Shared ciphers: %s\n", buf); |
| 1511 | } |
| 1512 | |
| 1513 | /* Record the certificate we presented */ |
| 1514 | { |
| 1515 | X509 * crt = SSL_get_certificate(server_ssl); |
| 1516 | tls_in.ourcert = crt ? X509_dup(crt) : NULL; |
| 1517 | } |
| 1518 | |
| 1519 | /* Only used by the server-side tls (tls_in), including tls_getc. |
| 1520 | Client-side (tls_out) reads (seem to?) go via |
| 1521 | smtp_read_response()/ip_recv(). |
| 1522 | Hence no need to duplicate for _in and _out. |
| 1523 | */ |
| 1524 | ssl_xfer_buffer = store_malloc(ssl_xfer_buffer_size); |
| 1525 | ssl_xfer_buffer_lwm = ssl_xfer_buffer_hwm = 0; |
| 1526 | ssl_xfer_eof = ssl_xfer_error = 0; |
| 1527 | |
| 1528 | receive_getc = tls_getc; |
| 1529 | receive_ungetc = tls_ungetc; |
| 1530 | receive_feof = tls_feof; |
| 1531 | receive_ferror = tls_ferror; |
| 1532 | receive_smtp_buffered = tls_smtp_buffered; |
| 1533 | |
| 1534 | tls_in.active = fileno(smtp_out); |
| 1535 | return OK; |
| 1536 | } |
| 1537 | |
| 1538 | |
| 1539 | |
| 1540 | |
| 1541 | |
| 1542 | /************************************************* |
| 1543 | * Start a TLS session in a client * |
| 1544 | *************************************************/ |
| 1545 | |
| 1546 | /* Called from the smtp transport after STARTTLS has been accepted. |
| 1547 | |
| 1548 | Argument: |
| 1549 | fd the fd of the connection |
| 1550 | host connected host (for messages) |
| 1551 | addr the first address |
| 1552 | ob smtp transport options |
| 1553 | |
| 1554 | Returns: OK on success |
| 1555 | FAIL otherwise - note that tls_error() will not give DEFER |
| 1556 | because this is not a server |
| 1557 | */ |
| 1558 | |
| 1559 | int |
| 1560 | tls_client_start(int fd, host_item *host, address_item *addr, |
| 1561 | void *v_ob) |
| 1562 | { |
| 1563 | smtp_transport_options_block * ob = v_ob; |
| 1564 | static uschar txt[256]; |
| 1565 | uschar *expciphers; |
| 1566 | X509* server_cert; |
| 1567 | int rc; |
| 1568 | static uschar cipherbuf[256]; |
| 1569 | #ifndef DISABLE_OCSP |
| 1570 | BOOL require_ocsp = verify_check_this_host(&ob->hosts_require_ocsp, |
| 1571 | NULL, host->name, host->address, NULL) == OK; |
| 1572 | BOOL request_ocsp = require_ocsp ? TRUE |
| 1573 | : verify_check_this_host(&ob->hosts_request_ocsp, |
| 1574 | NULL, host->name, host->address, NULL) == OK; |
| 1575 | #endif |
| 1576 | |
| 1577 | rc = tls_init(&client_ctx, host, NULL, |
| 1578 | ob->tls_certificate, ob->tls_privatekey, |
| 1579 | #ifndef DISABLE_OCSP |
| 1580 | (void *)(long)request_ocsp, |
| 1581 | #endif |
| 1582 | addr, &client_static_cbinfo); |
| 1583 | if (rc != OK) return rc; |
| 1584 | |
| 1585 | tls_out.certificate_verified = FALSE; |
| 1586 | client_verify_callback_called = FALSE; |
| 1587 | |
| 1588 | if (!expand_check(ob->tls_require_ciphers, US"tls_require_ciphers", |
| 1589 | &expciphers)) |
| 1590 | return FAIL; |
| 1591 | |
| 1592 | /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they |
| 1593 | are separated by underscores. So that I can use either form in my tests, and |
| 1594 | also for general convenience, we turn underscores into hyphens here. */ |
| 1595 | |
| 1596 | if (expciphers != NULL) |
| 1597 | { |
| 1598 | uschar *s = expciphers; |
| 1599 | while (*s != 0) { if (*s == '_') *s = '-'; s++; } |
| 1600 | DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers); |
| 1601 | if (!SSL_CTX_set_cipher_list(client_ctx, CS expciphers)) |
| 1602 | return tls_error(US"SSL_CTX_set_cipher_list", host, NULL); |
| 1603 | } |
| 1604 | |
| 1605 | /* stick to the old behaviour for compatibility if tls_verify_certificates is |
| 1606 | set but both tls_verify_hosts and tls_try_verify_hosts is not set. Check only |
| 1607 | the specified host patterns if one of them is defined */ |
| 1608 | |
| 1609 | if ((!ob->tls_verify_hosts && !ob->tls_try_verify_hosts) || |
| 1610 | (verify_check_host(&ob->tls_verify_hosts) == OK)) |
| 1611 | { |
| 1612 | if ((rc = setup_certs(client_ctx, ob->tls_verify_certificates, |
| 1613 | ob->tls_crl, host, FALSE, verify_callback_client)) != OK) |
| 1614 | return rc; |
| 1615 | client_verify_optional = FALSE; |
| 1616 | |
| 1617 | #ifdef EXPERIMENTAL_CERTNAMES |
| 1618 | if (ob->tls_verify_cert_hostnames) |
| 1619 | { |
| 1620 | if (!expand_check(ob->tls_verify_cert_hostnames, |
| 1621 | US"tls_verify_cert_hostnames", |
| 1622 | &client_static_cbinfo->verify_cert_hostnames)) |
| 1623 | return FAIL; |
| 1624 | if (client_static_cbinfo->verify_cert_hostnames) |
| 1625 | DEBUG(D_tls) debug_printf("Cert hostname to check: \"%s\"\n", |
| 1626 | client_static_cbinfo->verify_cert_hostnames); |
| 1627 | } |
| 1628 | #endif |
| 1629 | } |
| 1630 | else if (verify_check_host(&ob->tls_try_verify_hosts) == OK) |
| 1631 | { |
| 1632 | if ((rc = setup_certs(client_ctx, ob->tls_verify_certificates, |
| 1633 | ob->tls_crl, host, TRUE, verify_callback_client)) != OK) |
| 1634 | return rc; |
| 1635 | client_verify_optional = TRUE; |
| 1636 | } |
| 1637 | |
| 1638 | if ((client_ssl = SSL_new(client_ctx)) == NULL) |
| 1639 | return tls_error(US"SSL_new", host, NULL); |
| 1640 | SSL_set_session_id_context(client_ssl, sid_ctx, Ustrlen(sid_ctx)); |
| 1641 | SSL_set_fd(client_ssl, fd); |
| 1642 | SSL_set_connect_state(client_ssl); |
| 1643 | |
| 1644 | if (ob->tls_sni) |
| 1645 | { |
| 1646 | if (!expand_check(ob->tls_sni, US"tls_sni", &tls_out.sni)) |
| 1647 | return FAIL; |
| 1648 | if (tls_out.sni == NULL) |
| 1649 | { |
| 1650 | DEBUG(D_tls) debug_printf("Setting TLS SNI forced to fail, not sending\n"); |
| 1651 | } |
| 1652 | else if (!Ustrlen(tls_out.sni)) |
| 1653 | tls_out.sni = NULL; |
| 1654 | else |
| 1655 | { |
| 1656 | #ifdef EXIM_HAVE_OPENSSL_TLSEXT |
| 1657 | DEBUG(D_tls) debug_printf("Setting TLS SNI \"%s\"\n", tls_out.sni); |
| 1658 | SSL_set_tlsext_host_name(client_ssl, tls_out.sni); |
| 1659 | #else |
| 1660 | DEBUG(D_tls) |
| 1661 | debug_printf("OpenSSL at build-time lacked SNI support, ignoring \"%s\"\n", |
| 1662 | tls_out.sni); |
| 1663 | #endif |
| 1664 | } |
| 1665 | } |
| 1666 | |
| 1667 | #ifndef DISABLE_OCSP |
| 1668 | /* Request certificate status at connection-time. If the server |
| 1669 | does OCSP stapling we will get the callback (set in tls_init()) */ |
| 1670 | if (request_ocsp) |
| 1671 | { |
| 1672 | SSL_set_tlsext_status_type(client_ssl, TLSEXT_STATUSTYPE_ocsp); |
| 1673 | client_static_cbinfo->u_ocsp.client.verify_required = require_ocsp; |
| 1674 | tls_out.ocsp = OCSP_NOT_RESP; |
| 1675 | } |
| 1676 | #endif |
| 1677 | |
| 1678 | /* There doesn't seem to be a built-in timeout on connection. */ |
| 1679 | |
| 1680 | DEBUG(D_tls) debug_printf("Calling SSL_connect\n"); |
| 1681 | sigalrm_seen = FALSE; |
| 1682 | alarm(ob->command_timeout); |
| 1683 | rc = SSL_connect(client_ssl); |
| 1684 | alarm(0); |
| 1685 | |
| 1686 | if (rc <= 0) |
| 1687 | return tls_error(US"SSL_connect", host, sigalrm_seen ? US"timed out" : NULL); |
| 1688 | |
| 1689 | DEBUG(D_tls) debug_printf("SSL_connect succeeded\n"); |
| 1690 | |
| 1691 | /* Beware anonymous ciphers which lead to server_cert being NULL */ |
| 1692 | /*XXX server_cert is never freed... use X509_free() */ |
| 1693 | server_cert = SSL_get_peer_certificate (client_ssl); |
| 1694 | if (server_cert) |
| 1695 | { |
| 1696 | tls_out.peerdn = US X509_NAME_oneline(X509_get_subject_name(server_cert), |
| 1697 | CS txt, sizeof(txt)); |
| 1698 | tls_out.peerdn = txt; /*XXX a static buffer... */ |
| 1699 | } |
| 1700 | else |
| 1701 | tls_out.peerdn = NULL; |
| 1702 | |
| 1703 | construct_cipher_name(client_ssl, cipherbuf, sizeof(cipherbuf), &tls_out.bits); |
| 1704 | tls_out.cipher = cipherbuf; |
| 1705 | |
| 1706 | /* Record the certificate we presented */ |
| 1707 | { |
| 1708 | X509 * crt = SSL_get_certificate(client_ssl); |
| 1709 | tls_out.ourcert = crt ? X509_dup(crt) : NULL; |
| 1710 | } |
| 1711 | |
| 1712 | tls_out.active = fd; |
| 1713 | return OK; |
| 1714 | } |
| 1715 | |
| 1716 | |
| 1717 | |
| 1718 | |
| 1719 | |
| 1720 | /************************************************* |
| 1721 | * TLS version of getc * |
| 1722 | *************************************************/ |
| 1723 | |
| 1724 | /* This gets the next byte from the TLS input buffer. If the buffer is empty, |
| 1725 | it refills the buffer via the SSL reading function. |
| 1726 | |
| 1727 | Arguments: none |
| 1728 | Returns: the next character or EOF |
| 1729 | |
| 1730 | Only used by the server-side TLS. |
| 1731 | */ |
| 1732 | |
| 1733 | int |
| 1734 | tls_getc(void) |
| 1735 | { |
| 1736 | if (ssl_xfer_buffer_lwm >= ssl_xfer_buffer_hwm) |
| 1737 | { |
| 1738 | int error; |
| 1739 | int inbytes; |
| 1740 | |
| 1741 | DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", server_ssl, |
| 1742 | ssl_xfer_buffer, ssl_xfer_buffer_size); |
| 1743 | |
| 1744 | if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout); |
| 1745 | inbytes = SSL_read(server_ssl, CS ssl_xfer_buffer, ssl_xfer_buffer_size); |
| 1746 | error = SSL_get_error(server_ssl, inbytes); |
| 1747 | alarm(0); |
| 1748 | |
| 1749 | /* SSL_ERROR_ZERO_RETURN appears to mean that the SSL session has been |
| 1750 | closed down, not that the socket itself has been closed down. Revert to |
| 1751 | non-SSL handling. */ |
| 1752 | |
| 1753 | if (error == SSL_ERROR_ZERO_RETURN) |
| 1754 | { |
| 1755 | DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n"); |
| 1756 | |
| 1757 | receive_getc = smtp_getc; |
| 1758 | receive_ungetc = smtp_ungetc; |
| 1759 | receive_feof = smtp_feof; |
| 1760 | receive_ferror = smtp_ferror; |
| 1761 | receive_smtp_buffered = smtp_buffered; |
| 1762 | |
| 1763 | SSL_free(server_ssl); |
| 1764 | server_ssl = NULL; |
| 1765 | tls_in.active = -1; |
| 1766 | tls_in.bits = 0; |
| 1767 | tls_in.cipher = NULL; |
| 1768 | tls_in.peerdn = NULL; |
| 1769 | tls_in.sni = NULL; |
| 1770 | |
| 1771 | return smtp_getc(); |
| 1772 | } |
| 1773 | |
| 1774 | /* Handle genuine errors */ |
| 1775 | |
| 1776 | else if (error == SSL_ERROR_SSL) |
| 1777 | { |
| 1778 | ERR_error_string(ERR_get_error(), ssl_errstring); |
| 1779 | log_write(0, LOG_MAIN, "TLS error (SSL_read): %s", ssl_errstring); |
| 1780 | ssl_xfer_error = 1; |
| 1781 | return EOF; |
| 1782 | } |
| 1783 | |
| 1784 | else if (error != SSL_ERROR_NONE) |
| 1785 | { |
| 1786 | DEBUG(D_tls) debug_printf("Got SSL error %d\n", error); |
| 1787 | ssl_xfer_error = 1; |
| 1788 | return EOF; |
| 1789 | } |
| 1790 | |
| 1791 | #ifndef DISABLE_DKIM |
| 1792 | dkim_exim_verify_feed(ssl_xfer_buffer, inbytes); |
| 1793 | #endif |
| 1794 | ssl_xfer_buffer_hwm = inbytes; |
| 1795 | ssl_xfer_buffer_lwm = 0; |
| 1796 | } |
| 1797 | |
| 1798 | /* Something in the buffer; return next uschar */ |
| 1799 | |
| 1800 | return ssl_xfer_buffer[ssl_xfer_buffer_lwm++]; |
| 1801 | } |
| 1802 | |
| 1803 | |
| 1804 | |
| 1805 | /************************************************* |
| 1806 | * Read bytes from TLS channel * |
| 1807 | *************************************************/ |
| 1808 | |
| 1809 | /* |
| 1810 | Arguments: |
| 1811 | buff buffer of data |
| 1812 | len size of buffer |
| 1813 | |
| 1814 | Returns: the number of bytes read |
| 1815 | -1 after a failed read |
| 1816 | |
| 1817 | Only used by the client-side TLS. |
| 1818 | */ |
| 1819 | |
| 1820 | int |
| 1821 | tls_read(BOOL is_server, uschar *buff, size_t len) |
| 1822 | { |
| 1823 | SSL *ssl = is_server ? server_ssl : client_ssl; |
| 1824 | int inbytes; |
| 1825 | int error; |
| 1826 | |
| 1827 | DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", ssl, |
| 1828 | buff, (unsigned int)len); |
| 1829 | |
| 1830 | inbytes = SSL_read(ssl, CS buff, len); |
| 1831 | error = SSL_get_error(ssl, inbytes); |
| 1832 | |
| 1833 | if (error == SSL_ERROR_ZERO_RETURN) |
| 1834 | { |
| 1835 | DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n"); |
| 1836 | return -1; |
| 1837 | } |
| 1838 | else if (error != SSL_ERROR_NONE) |
| 1839 | { |
| 1840 | return -1; |
| 1841 | } |
| 1842 | |
| 1843 | return inbytes; |
| 1844 | } |
| 1845 | |
| 1846 | |
| 1847 | |
| 1848 | |
| 1849 | |
| 1850 | /************************************************* |
| 1851 | * Write bytes down TLS channel * |
| 1852 | *************************************************/ |
| 1853 | |
| 1854 | /* |
| 1855 | Arguments: |
| 1856 | is_server channel specifier |
| 1857 | buff buffer of data |
| 1858 | len number of bytes |
| 1859 | |
| 1860 | Returns: the number of bytes after a successful write, |
| 1861 | -1 after a failed write |
| 1862 | |
| 1863 | Used by both server-side and client-side TLS. |
| 1864 | */ |
| 1865 | |
| 1866 | int |
| 1867 | tls_write(BOOL is_server, const uschar *buff, size_t len) |
| 1868 | { |
| 1869 | int outbytes; |
| 1870 | int error; |
| 1871 | int left = len; |
| 1872 | SSL *ssl = is_server ? server_ssl : client_ssl; |
| 1873 | |
| 1874 | DEBUG(D_tls) debug_printf("tls_do_write(%p, %d)\n", buff, left); |
| 1875 | while (left > 0) |
| 1876 | { |
| 1877 | DEBUG(D_tls) debug_printf("SSL_write(SSL, %p, %d)\n", buff, left); |
| 1878 | outbytes = SSL_write(ssl, CS buff, left); |
| 1879 | error = SSL_get_error(ssl, outbytes); |
| 1880 | DEBUG(D_tls) debug_printf("outbytes=%d error=%d\n", outbytes, error); |
| 1881 | switch (error) |
| 1882 | { |
| 1883 | case SSL_ERROR_SSL: |
| 1884 | ERR_error_string(ERR_get_error(), ssl_errstring); |
| 1885 | log_write(0, LOG_MAIN, "TLS error (SSL_write): %s", ssl_errstring); |
| 1886 | return -1; |
| 1887 | |
| 1888 | case SSL_ERROR_NONE: |
| 1889 | left -= outbytes; |
| 1890 | buff += outbytes; |
| 1891 | break; |
| 1892 | |
| 1893 | case SSL_ERROR_ZERO_RETURN: |
| 1894 | log_write(0, LOG_MAIN, "SSL channel closed on write"); |
| 1895 | return -1; |
| 1896 | |
| 1897 | case SSL_ERROR_SYSCALL: |
| 1898 | log_write(0, LOG_MAIN, "SSL_write: (from %s) syscall: %s", |
| 1899 | sender_fullhost ? sender_fullhost : US"<unknown>", |
| 1900 | strerror(errno)); |
| 1901 | |
| 1902 | default: |
| 1903 | log_write(0, LOG_MAIN, "SSL_write error %d", error); |
| 1904 | return -1; |
| 1905 | } |
| 1906 | } |
| 1907 | return len; |
| 1908 | } |
| 1909 | |
| 1910 | |
| 1911 | |
| 1912 | /************************************************* |
| 1913 | * Close down a TLS session * |
| 1914 | *************************************************/ |
| 1915 | |
| 1916 | /* This is also called from within a delivery subprocess forked from the |
| 1917 | daemon, to shut down the TLS library, without actually doing a shutdown (which |
| 1918 | would tamper with the SSL session in the parent process). |
| 1919 | |
| 1920 | Arguments: TRUE if SSL_shutdown is to be called |
| 1921 | Returns: nothing |
| 1922 | |
| 1923 | Used by both server-side and client-side TLS. |
| 1924 | */ |
| 1925 | |
| 1926 | void |
| 1927 | tls_close(BOOL is_server, BOOL shutdown) |
| 1928 | { |
| 1929 | SSL **sslp = is_server ? &server_ssl : &client_ssl; |
| 1930 | int *fdp = is_server ? &tls_in.active : &tls_out.active; |
| 1931 | |
| 1932 | if (*fdp < 0) return; /* TLS was not active */ |
| 1933 | |
| 1934 | if (shutdown) |
| 1935 | { |
| 1936 | DEBUG(D_tls) debug_printf("tls_close(): shutting down SSL\n"); |
| 1937 | SSL_shutdown(*sslp); |
| 1938 | } |
| 1939 | |
| 1940 | SSL_free(*sslp); |
| 1941 | *sslp = NULL; |
| 1942 | |
| 1943 | *fdp = -1; |
| 1944 | } |
| 1945 | |
| 1946 | |
| 1947 | |
| 1948 | |
| 1949 | /************************************************* |
| 1950 | * Let tls_require_ciphers be checked at startup * |
| 1951 | *************************************************/ |
| 1952 | |
| 1953 | /* The tls_require_ciphers option, if set, must be something which the |
| 1954 | library can parse. |
| 1955 | |
| 1956 | Returns: NULL on success, or error message |
| 1957 | */ |
| 1958 | |
| 1959 | uschar * |
| 1960 | tls_validate_require_cipher(void) |
| 1961 | { |
| 1962 | SSL_CTX *ctx; |
| 1963 | uschar *s, *expciphers, *err; |
| 1964 | |
| 1965 | /* this duplicates from tls_init(), we need a better "init just global |
| 1966 | state, for no specific purpose" singleton function of our own */ |
| 1967 | |
| 1968 | SSL_load_error_strings(); |
| 1969 | OpenSSL_add_ssl_algorithms(); |
| 1970 | #if (OPENSSL_VERSION_NUMBER >= 0x0090800fL) && !defined(OPENSSL_NO_SHA256) |
| 1971 | /* SHA256 is becoming ever more popular. This makes sure it gets added to the |
| 1972 | list of available digests. */ |
| 1973 | EVP_add_digest(EVP_sha256()); |
| 1974 | #endif |
| 1975 | |
| 1976 | if (!(tls_require_ciphers && *tls_require_ciphers)) |
| 1977 | return NULL; |
| 1978 | |
| 1979 | if (!expand_check(tls_require_ciphers, US"tls_require_ciphers", &expciphers)) |
| 1980 | return US"failed to expand tls_require_ciphers"; |
| 1981 | |
| 1982 | if (!(expciphers && *expciphers)) |
| 1983 | return NULL; |
| 1984 | |
| 1985 | /* normalisation ripped from above */ |
| 1986 | s = expciphers; |
| 1987 | while (*s != 0) { if (*s == '_') *s = '-'; s++; } |
| 1988 | |
| 1989 | err = NULL; |
| 1990 | |
| 1991 | ctx = SSL_CTX_new(SSLv23_server_method()); |
| 1992 | if (!ctx) |
| 1993 | { |
| 1994 | ERR_error_string(ERR_get_error(), ssl_errstring); |
| 1995 | return string_sprintf("SSL_CTX_new() failed: %s", ssl_errstring); |
| 1996 | } |
| 1997 | |
| 1998 | DEBUG(D_tls) |
| 1999 | debug_printf("tls_require_ciphers expands to \"%s\"\n", expciphers); |
| 2000 | |
| 2001 | if (!SSL_CTX_set_cipher_list(ctx, CS expciphers)) |
| 2002 | { |
| 2003 | ERR_error_string(ERR_get_error(), ssl_errstring); |
| 2004 | err = string_sprintf("SSL_CTX_set_cipher_list(%s) failed", expciphers); |
| 2005 | } |
| 2006 | |
| 2007 | SSL_CTX_free(ctx); |
| 2008 | |
| 2009 | return err; |
| 2010 | } |
| 2011 | |
| 2012 | |
| 2013 | |
| 2014 | |
| 2015 | /************************************************* |
| 2016 | * Report the library versions. * |
| 2017 | *************************************************/ |
| 2018 | |
| 2019 | /* There have historically been some issues with binary compatibility in |
| 2020 | OpenSSL libraries; if Exim (like many other applications) is built against |
| 2021 | one version of OpenSSL but the run-time linker picks up another version, |
| 2022 | it can result in serious failures, including crashing with a SIGSEGV. So |
| 2023 | report the version found by the compiler and the run-time version. |
| 2024 | |
| 2025 | Note: some OS vendors backport security fixes without changing the version |
| 2026 | number/string, and the version date remains unchanged. The _build_ date |
| 2027 | will change, so we can more usefully assist with version diagnosis by also |
| 2028 | reporting the build date. |
| 2029 | |
| 2030 | Arguments: a FILE* to print the results to |
| 2031 | Returns: nothing |
| 2032 | */ |
| 2033 | |
| 2034 | void |
| 2035 | tls_version_report(FILE *f) |
| 2036 | { |
| 2037 | fprintf(f, "Library version: OpenSSL: Compile: %s\n" |
| 2038 | " Runtime: %s\n" |
| 2039 | " : %s\n", |
| 2040 | OPENSSL_VERSION_TEXT, |
| 2041 | SSLeay_version(SSLEAY_VERSION), |
| 2042 | SSLeay_version(SSLEAY_BUILT_ON)); |
| 2043 | /* third line is 38 characters for the %s and the line is 73 chars long; |
| 2044 | the OpenSSL output includes a "built on: " prefix already. */ |
| 2045 | } |
| 2046 | |
| 2047 | |
| 2048 | |
| 2049 | |
| 2050 | /************************************************* |
| 2051 | * Random number generation * |
| 2052 | *************************************************/ |
| 2053 | |
| 2054 | /* Pseudo-random number generation. The result is not expected to be |
| 2055 | cryptographically strong but not so weak that someone will shoot themselves |
| 2056 | in the foot using it as a nonce in input in some email header scheme or |
| 2057 | whatever weirdness they'll twist this into. The result should handle fork() |
| 2058 | and avoid repeating sequences. OpenSSL handles that for us. |
| 2059 | |
| 2060 | Arguments: |
| 2061 | max range maximum |
| 2062 | Returns a random number in range [0, max-1] |
| 2063 | */ |
| 2064 | |
| 2065 | int |
| 2066 | vaguely_random_number(int max) |
| 2067 | { |
| 2068 | unsigned int r; |
| 2069 | int i, needed_len; |
| 2070 | static pid_t pidlast = 0; |
| 2071 | pid_t pidnow; |
| 2072 | uschar *p; |
| 2073 | uschar smallbuf[sizeof(r)]; |
| 2074 | |
| 2075 | if (max <= 1) |
| 2076 | return 0; |
| 2077 | |
| 2078 | pidnow = getpid(); |
| 2079 | if (pidnow != pidlast) |
| 2080 | { |
| 2081 | /* Although OpenSSL documents that "OpenSSL makes sure that the PRNG state |
| 2082 | is unique for each thread", this doesn't apparently apply across processes, |
| 2083 | so our own warning from vaguely_random_number_fallback() applies here too. |
| 2084 | Fix per PostgreSQL. */ |
| 2085 | if (pidlast != 0) |
| 2086 | RAND_cleanup(); |
| 2087 | pidlast = pidnow; |
| 2088 | } |
| 2089 | |
| 2090 | /* OpenSSL auto-seeds from /dev/random, etc, but this a double-check. */ |
| 2091 | if (!RAND_status()) |
| 2092 | { |
| 2093 | randstuff r; |
| 2094 | gettimeofday(&r.tv, NULL); |
| 2095 | r.p = getpid(); |
| 2096 | |
| 2097 | RAND_seed((uschar *)(&r), sizeof(r)); |
| 2098 | } |
| 2099 | /* We're after pseudo-random, not random; if we still don't have enough data |
| 2100 | in the internal PRNG then our options are limited. We could sleep and hope |
| 2101 | for entropy to come along (prayer technique) but if the system is so depleted |
| 2102 | in the first place then something is likely to just keep taking it. Instead, |
| 2103 | we'll just take whatever little bit of pseudo-random we can still manage to |
| 2104 | get. */ |
| 2105 | |
| 2106 | needed_len = sizeof(r); |
| 2107 | /* Don't take 8 times more entropy than needed if int is 8 octets and we were |
| 2108 | asked for a number less than 10. */ |
| 2109 | for (r = max, i = 0; r; ++i) |
| 2110 | r >>= 1; |
| 2111 | i = (i + 7) / 8; |
| 2112 | if (i < needed_len) |
| 2113 | needed_len = i; |
| 2114 | |
| 2115 | /* We do not care if crypto-strong */ |
| 2116 | i = RAND_pseudo_bytes(smallbuf, needed_len); |
| 2117 | if (i < 0) |
| 2118 | { |
| 2119 | DEBUG(D_all) |
| 2120 | debug_printf("OpenSSL RAND_pseudo_bytes() not supported by RAND method, using fallback.\n"); |
| 2121 | return vaguely_random_number_fallback(max); |
| 2122 | } |
| 2123 | |
| 2124 | r = 0; |
| 2125 | for (p = smallbuf; needed_len; --needed_len, ++p) |
| 2126 | { |
| 2127 | r *= 256; |
| 2128 | r += *p; |
| 2129 | } |
| 2130 | |
| 2131 | /* We don't particularly care about weighted results; if someone wants |
| 2132 | smooth distribution and cares enough then they should submit a patch then. */ |
| 2133 | return r % max; |
| 2134 | } |
| 2135 | |
| 2136 | |
| 2137 | |
| 2138 | |
| 2139 | /************************************************* |
| 2140 | * OpenSSL option parse * |
| 2141 | *************************************************/ |
| 2142 | |
| 2143 | /* Parse one option for tls_openssl_options_parse below |
| 2144 | |
| 2145 | Arguments: |
| 2146 | name one option name |
| 2147 | value place to store a value for it |
| 2148 | Returns success or failure in parsing |
| 2149 | */ |
| 2150 | |
| 2151 | struct exim_openssl_option { |
| 2152 | uschar *name; |
| 2153 | long value; |
| 2154 | }; |
| 2155 | /* We could use a macro to expand, but we need the ifdef and not all the |
| 2156 | options document which version they were introduced in. Policylet: include |
| 2157 | all options unless explicitly for DTLS, let the administrator choose which |
| 2158 | to apply. |
| 2159 | |
| 2160 | This list is current as of: |
| 2161 | ==> 1.0.1b <== |
| 2162 | Plus SSL_OP_SAFARI_ECDHE_ECDSA_BUG from 2013-June patch/discussion on openssl-dev |
| 2163 | */ |
| 2164 | static struct exim_openssl_option exim_openssl_options[] = { |
| 2165 | /* KEEP SORTED ALPHABETICALLY! */ |
| 2166 | #ifdef SSL_OP_ALL |
| 2167 | { US"all", SSL_OP_ALL }, |
| 2168 | #endif |
| 2169 | #ifdef SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION |
| 2170 | { US"allow_unsafe_legacy_renegotiation", SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION }, |
| 2171 | #endif |
| 2172 | #ifdef SSL_OP_CIPHER_SERVER_PREFERENCE |
| 2173 | { US"cipher_server_preference", SSL_OP_CIPHER_SERVER_PREFERENCE }, |
| 2174 | #endif |
| 2175 | #ifdef SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS |
| 2176 | { US"dont_insert_empty_fragments", SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS }, |
| 2177 | #endif |
| 2178 | #ifdef SSL_OP_EPHEMERAL_RSA |
| 2179 | { US"ephemeral_rsa", SSL_OP_EPHEMERAL_RSA }, |
| 2180 | #endif |
| 2181 | #ifdef SSL_OP_LEGACY_SERVER_CONNECT |
| 2182 | { US"legacy_server_connect", SSL_OP_LEGACY_SERVER_CONNECT }, |
| 2183 | #endif |
| 2184 | #ifdef SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER |
| 2185 | { US"microsoft_big_sslv3_buffer", SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER }, |
| 2186 | #endif |
| 2187 | #ifdef SSL_OP_MICROSOFT_SESS_ID_BUG |
| 2188 | { US"microsoft_sess_id_bug", SSL_OP_MICROSOFT_SESS_ID_BUG }, |
| 2189 | #endif |
| 2190 | #ifdef SSL_OP_MSIE_SSLV2_RSA_PADDING |
| 2191 | { US"msie_sslv2_rsa_padding", SSL_OP_MSIE_SSLV2_RSA_PADDING }, |
| 2192 | #endif |
| 2193 | #ifdef SSL_OP_NETSCAPE_CHALLENGE_BUG |
| 2194 | { US"netscape_challenge_bug", SSL_OP_NETSCAPE_CHALLENGE_BUG }, |
| 2195 | #endif |
| 2196 | #ifdef SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG |
| 2197 | { US"netscape_reuse_cipher_change_bug", SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG }, |
| 2198 | #endif |
| 2199 | #ifdef SSL_OP_NO_COMPRESSION |
| 2200 | { US"no_compression", SSL_OP_NO_COMPRESSION }, |
| 2201 | #endif |
| 2202 | #ifdef SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION |
| 2203 | { US"no_session_resumption_on_renegotiation", SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION }, |
| 2204 | #endif |
| 2205 | #ifdef SSL_OP_NO_SSLv2 |
| 2206 | { US"no_sslv2", SSL_OP_NO_SSLv2 }, |
| 2207 | #endif |
| 2208 | #ifdef SSL_OP_NO_SSLv3 |
| 2209 | { US"no_sslv3", SSL_OP_NO_SSLv3 }, |
| 2210 | #endif |
| 2211 | #ifdef SSL_OP_NO_TICKET |
| 2212 | { US"no_ticket", SSL_OP_NO_TICKET }, |
| 2213 | #endif |
| 2214 | #ifdef SSL_OP_NO_TLSv1 |
| 2215 | { US"no_tlsv1", SSL_OP_NO_TLSv1 }, |
| 2216 | #endif |
| 2217 | #ifdef SSL_OP_NO_TLSv1_1 |
| 2218 | #if SSL_OP_NO_TLSv1_1 == 0x00000400L |
| 2219 | /* Error in chosen value in 1.0.1a; see first item in CHANGES for 1.0.1b */ |
| 2220 | #warning OpenSSL 1.0.1a uses a bad value for SSL_OP_NO_TLSv1_1, ignoring |
| 2221 | #else |
| 2222 | { US"no_tlsv1_1", SSL_OP_NO_TLSv1_1 }, |
| 2223 | #endif |
| 2224 | #endif |
| 2225 | #ifdef SSL_OP_NO_TLSv1_2 |
| 2226 | { US"no_tlsv1_2", SSL_OP_NO_TLSv1_2 }, |
| 2227 | #endif |
| 2228 | #ifdef SSL_OP_SAFARI_ECDHE_ECDSA_BUG |
| 2229 | { US"safari_ecdhe_ecdsa_bug", SSL_OP_SAFARI_ECDHE_ECDSA_BUG }, |
| 2230 | #endif |
| 2231 | #ifdef SSL_OP_SINGLE_DH_USE |
| 2232 | { US"single_dh_use", SSL_OP_SINGLE_DH_USE }, |
| 2233 | #endif |
| 2234 | #ifdef SSL_OP_SINGLE_ECDH_USE |
| 2235 | { US"single_ecdh_use", SSL_OP_SINGLE_ECDH_USE }, |
| 2236 | #endif |
| 2237 | #ifdef SSL_OP_SSLEAY_080_CLIENT_DH_BUG |
| 2238 | { US"ssleay_080_client_dh_bug", SSL_OP_SSLEAY_080_CLIENT_DH_BUG }, |
| 2239 | #endif |
| 2240 | #ifdef SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG |
| 2241 | { US"sslref2_reuse_cert_type_bug", SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG }, |
| 2242 | #endif |
| 2243 | #ifdef SSL_OP_TLS_BLOCK_PADDING_BUG |
| 2244 | { US"tls_block_padding_bug", SSL_OP_TLS_BLOCK_PADDING_BUG }, |
| 2245 | #endif |
| 2246 | #ifdef SSL_OP_TLS_D5_BUG |
| 2247 | { US"tls_d5_bug", SSL_OP_TLS_D5_BUG }, |
| 2248 | #endif |
| 2249 | #ifdef SSL_OP_TLS_ROLLBACK_BUG |
| 2250 | { US"tls_rollback_bug", SSL_OP_TLS_ROLLBACK_BUG }, |
| 2251 | #endif |
| 2252 | }; |
| 2253 | static int exim_openssl_options_size = |
| 2254 | sizeof(exim_openssl_options)/sizeof(struct exim_openssl_option); |
| 2255 | |
| 2256 | |
| 2257 | static BOOL |
| 2258 | tls_openssl_one_option_parse(uschar *name, long *value) |
| 2259 | { |
| 2260 | int first = 0; |
| 2261 | int last = exim_openssl_options_size; |
| 2262 | while (last > first) |
| 2263 | { |
| 2264 | int middle = (first + last)/2; |
| 2265 | int c = Ustrcmp(name, exim_openssl_options[middle].name); |
| 2266 | if (c == 0) |
| 2267 | { |
| 2268 | *value = exim_openssl_options[middle].value; |
| 2269 | return TRUE; |
| 2270 | } |
| 2271 | else if (c > 0) |
| 2272 | first = middle + 1; |
| 2273 | else |
| 2274 | last = middle; |
| 2275 | } |
| 2276 | return FALSE; |
| 2277 | } |
| 2278 | |
| 2279 | |
| 2280 | |
| 2281 | |
| 2282 | /************************************************* |
| 2283 | * OpenSSL option parsing logic * |
| 2284 | *************************************************/ |
| 2285 | |
| 2286 | /* OpenSSL has a number of compatibility options which an administrator might |
| 2287 | reasonably wish to set. Interpret a list similarly to decode_bits(), so that |
| 2288 | we look like log_selector. |
| 2289 | |
| 2290 | Arguments: |
| 2291 | option_spec the administrator-supplied string of options |
| 2292 | results ptr to long storage for the options bitmap |
| 2293 | Returns success or failure |
| 2294 | */ |
| 2295 | |
| 2296 | BOOL |
| 2297 | tls_openssl_options_parse(uschar *option_spec, long *results) |
| 2298 | { |
| 2299 | long result, item; |
| 2300 | uschar *s, *end; |
| 2301 | uschar keep_c; |
| 2302 | BOOL adding, item_parsed; |
| 2303 | |
| 2304 | result = 0L; |
| 2305 | /* Prior to 4.80 we or'd in SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS; removed |
| 2306 | * from default because it increases BEAST susceptibility. */ |
| 2307 | #ifdef SSL_OP_NO_SSLv2 |
| 2308 | result |= SSL_OP_NO_SSLv2; |
| 2309 | #endif |
| 2310 | |
| 2311 | if (option_spec == NULL) |
| 2312 | { |
| 2313 | *results = result; |
| 2314 | return TRUE; |
| 2315 | } |
| 2316 | |
| 2317 | for (s=option_spec; *s != '\0'; /**/) |
| 2318 | { |
| 2319 | while (isspace(*s)) ++s; |
| 2320 | if (*s == '\0') |
| 2321 | break; |
| 2322 | if (*s != '+' && *s != '-') |
| 2323 | { |
| 2324 | DEBUG(D_tls) debug_printf("malformed openssl option setting: " |
| 2325 | "+ or - expected but found \"%s\"\n", s); |
| 2326 | return FALSE; |
| 2327 | } |
| 2328 | adding = *s++ == '+'; |
| 2329 | for (end = s; (*end != '\0') && !isspace(*end); ++end) /**/ ; |
| 2330 | keep_c = *end; |
| 2331 | *end = '\0'; |
| 2332 | item_parsed = tls_openssl_one_option_parse(s, &item); |
| 2333 | if (!item_parsed) |
| 2334 | { |
| 2335 | DEBUG(D_tls) debug_printf("openssl option setting unrecognised: \"%s\"\n", s); |
| 2336 | return FALSE; |
| 2337 | } |
| 2338 | DEBUG(D_tls) debug_printf("openssl option, %s from %lx: %lx (%s)\n", |
| 2339 | adding ? "adding" : "removing", result, item, s); |
| 2340 | if (adding) |
| 2341 | result |= item; |
| 2342 | else |
| 2343 | result &= ~item; |
| 2344 | *end = keep_c; |
| 2345 | s = end; |
| 2346 | } |
| 2347 | |
| 2348 | *results = result; |
| 2349 | return TRUE; |
| 2350 | } |
| 2351 | |
| 2352 | /* vi: aw ai sw=2 |
| 2353 | */ |
| 2354 | /* End of tls-openssl.c */ |