| 1 | /************************************************* |
| 2 | * Exim - an Internet mail transport agent * |
| 3 | *************************************************/ |
| 4 | |
| 5 | /* Copyright (c) University of Cambridge 1995 - 2015 */ |
| 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 OPENSSL_NO_ECDH |
| 26 | # include <openssl/ec.h> |
| 27 | #endif |
| 28 | #ifndef DISABLE_OCSP |
| 29 | # include <openssl/ocsp.h> |
| 30 | #endif |
| 31 | #ifdef EXPERIMENTAL_DANE |
| 32 | # include <danessl.h> |
| 33 | #endif |
| 34 | |
| 35 | |
| 36 | #ifndef DISABLE_OCSP |
| 37 | # define EXIM_OCSP_SKEW_SECONDS (300L) |
| 38 | # define EXIM_OCSP_MAX_AGE (-1L) |
| 39 | #endif |
| 40 | |
| 41 | #if OPENSSL_VERSION_NUMBER >= 0x0090806fL && !defined(OPENSSL_NO_TLSEXT) |
| 42 | # define EXIM_HAVE_OPENSSL_TLSEXT |
| 43 | #endif |
| 44 | |
| 45 | /* |
| 46 | * X509_check_host provides sane certificate hostname checking, but was added |
| 47 | * to OpenSSL late, after other projects forked off the code-base. So in |
| 48 | * addition to guarding against the base version number, beware that LibreSSL |
| 49 | * does not (at this time) support this function. |
| 50 | * |
| 51 | * If LibreSSL gains a different API, perhaps via libtls, then we'll probably |
| 52 | * opt to disentangle and ask a LibreSSL user to provide glue for a third |
| 53 | * crypto provider for libtls instead of continuing to tie the OpenSSL glue |
| 54 | * into even twistier knots. If LibreSSL gains the same API, we can just |
| 55 | * change this guard and punt the issue for a while longer. |
| 56 | */ |
| 57 | #ifndef LIBRESSL_VERSION_NUMBER |
| 58 | # if OPENSSL_VERSION_NUMBER >= 0x010100000L |
| 59 | # define EXIM_HAVE_OPENSSL_CHECKHOST |
| 60 | # endif |
| 61 | # if OPENSSL_VERSION_NUMBER >= 0x010000000L \ |
| 62 | && (OPENSSL_VERSION_NUMBER & 0x0000ff000L) >= 0x000002000L |
| 63 | # define EXIM_HAVE_OPENSSL_CHECKHOST |
| 64 | # endif |
| 65 | |
| 66 | # if !defined(OPENSSL_NO_ECDH) |
| 67 | # if OPENSSL_VERSION_NUMBER >= 0x0090800fL |
| 68 | # define EXIM_HAVE_ECDH |
| 69 | # endif |
| 70 | # if OPENSSL_VERSION_NUMBER >= 0x10002000L |
| 71 | # define EXIM_HAVE_OPENSSL_ECDH_AUTO |
| 72 | # define EXIM_HAVE_OPENSSL_EC_NIST2NID |
| 73 | # endif |
| 74 | # endif |
| 75 | #endif |
| 76 | |
| 77 | #if !defined(EXIM_HAVE_OPENSSL_TLSEXT) && !defined(DISABLE_OCSP) |
| 78 | # warning "OpenSSL library version too old; define DISABLE_OCSP in Makefile" |
| 79 | # define DISABLE_OCSP |
| 80 | #endif |
| 81 | |
| 82 | /* Structure for collecting random data for seeding. */ |
| 83 | |
| 84 | typedef struct randstuff { |
| 85 | struct timeval tv; |
| 86 | pid_t p; |
| 87 | } randstuff; |
| 88 | |
| 89 | /* Local static variables */ |
| 90 | |
| 91 | static BOOL client_verify_callback_called = FALSE; |
| 92 | static BOOL server_verify_callback_called = FALSE; |
| 93 | static const uschar *sid_ctx = US"exim"; |
| 94 | |
| 95 | /* We have three different contexts to care about. |
| 96 | |
| 97 | Simple case: client, `client_ctx` |
| 98 | As a client, we can be doing a callout or cut-through delivery while receiving |
| 99 | a message. So we have a client context, which should have options initialised |
| 100 | from the SMTP Transport. |
| 101 | |
| 102 | Server: |
| 103 | There are two cases: with and without ServerNameIndication from the client. |
| 104 | Given TLS SNI, we can be using different keys, certs and various other |
| 105 | configuration settings, because they're re-expanded with $tls_sni set. This |
| 106 | allows vhosting with TLS. This SNI is sent in the handshake. |
| 107 | A client might not send SNI, so we need a fallback, and an initial setup too. |
| 108 | So as a server, we start out using `server_ctx`. |
| 109 | If SNI is sent by the client, then we as server, mid-negotiation, try to clone |
| 110 | `server_sni` from `server_ctx` and then initialise settings by re-expanding |
| 111 | configuration. |
| 112 | */ |
| 113 | |
| 114 | static SSL_CTX *client_ctx = NULL; |
| 115 | static SSL_CTX *server_ctx = NULL; |
| 116 | static SSL *client_ssl = NULL; |
| 117 | static SSL *server_ssl = NULL; |
| 118 | |
| 119 | #ifdef EXIM_HAVE_OPENSSL_TLSEXT |
| 120 | static SSL_CTX *server_sni = NULL; |
| 121 | #endif |
| 122 | |
| 123 | static char ssl_errstring[256]; |
| 124 | |
| 125 | static int ssl_session_timeout = 200; |
| 126 | static BOOL client_verify_optional = FALSE; |
| 127 | static BOOL server_verify_optional = FALSE; |
| 128 | |
| 129 | static BOOL reexpand_tls_files_for_sni = FALSE; |
| 130 | |
| 131 | |
| 132 | typedef struct tls_ext_ctx_cb { |
| 133 | uschar *certificate; |
| 134 | uschar *privatekey; |
| 135 | #ifndef DISABLE_OCSP |
| 136 | BOOL is_server; |
| 137 | union { |
| 138 | struct { |
| 139 | uschar *file; |
| 140 | uschar *file_expanded; |
| 141 | OCSP_RESPONSE *response; |
| 142 | } server; |
| 143 | struct { |
| 144 | X509_STORE *verify_store; /* non-null if status requested */ |
| 145 | BOOL verify_required; |
| 146 | } client; |
| 147 | } u_ocsp; |
| 148 | #endif |
| 149 | uschar *dhparam; |
| 150 | /* these are cached from first expand */ |
| 151 | uschar *server_cipher_list; |
| 152 | /* only passed down to tls_error: */ |
| 153 | host_item *host; |
| 154 | const uschar * verify_cert_hostnames; |
| 155 | #ifdef EXPERIMENTAL_EVENT |
| 156 | uschar * event_action; |
| 157 | #endif |
| 158 | } tls_ext_ctx_cb; |
| 159 | |
| 160 | /* should figure out a cleanup of API to handle state preserved per |
| 161 | implementation, for various reasons, which can be void * in the APIs. |
| 162 | For now, we hack around it. */ |
| 163 | tls_ext_ctx_cb *client_static_cbinfo = NULL; |
| 164 | tls_ext_ctx_cb *server_static_cbinfo = NULL; |
| 165 | |
| 166 | static int |
| 167 | setup_certs(SSL_CTX *sctx, uschar *certs, uschar *crl, host_item *host, BOOL optional, |
| 168 | int (*cert_vfy_cb)(int, X509_STORE_CTX *) ); |
| 169 | |
| 170 | /* Callbacks */ |
| 171 | #ifdef EXIM_HAVE_OPENSSL_TLSEXT |
| 172 | static int tls_servername_cb(SSL *s, int *ad ARG_UNUSED, void *arg); |
| 173 | #endif |
| 174 | #ifndef DISABLE_OCSP |
| 175 | static int tls_server_stapling_cb(SSL *s, void *arg); |
| 176 | #endif |
| 177 | |
| 178 | |
| 179 | /************************************************* |
| 180 | * Handle TLS error * |
| 181 | *************************************************/ |
| 182 | |
| 183 | /* Called from lots of places when errors occur before actually starting to do |
| 184 | the TLS handshake, that is, while the session is still in clear. Always returns |
| 185 | DEFER for a server and FAIL for a client so that most calls can use "return |
| 186 | tls_error(...)" to do this processing and then give an appropriate return. A |
| 187 | single function is used for both server and client, because it is called from |
| 188 | some shared functions. |
| 189 | |
| 190 | Argument: |
| 191 | prefix text to include in the logged error |
| 192 | host NULL if setting up a server; |
| 193 | the connected host if setting up a client |
| 194 | msg error message or NULL if we should ask OpenSSL |
| 195 | |
| 196 | Returns: OK/DEFER/FAIL |
| 197 | */ |
| 198 | |
| 199 | static int |
| 200 | tls_error(uschar * prefix, const host_item * host, uschar * msg) |
| 201 | { |
| 202 | if (!msg) |
| 203 | { |
| 204 | ERR_error_string(ERR_get_error(), ssl_errstring); |
| 205 | msg = (uschar *)ssl_errstring; |
| 206 | } |
| 207 | |
| 208 | if (host) |
| 209 | { |
| 210 | log_write(0, LOG_MAIN, "H=%s [%s] TLS error on connection (%s): %s", |
| 211 | host->name, host->address, prefix, msg); |
| 212 | return FAIL; |
| 213 | } |
| 214 | else |
| 215 | { |
| 216 | uschar *conn_info = smtp_get_connection_info(); |
| 217 | if (Ustrncmp(conn_info, US"SMTP ", 5) == 0) |
| 218 | conn_info += 5; |
| 219 | /* I'd like to get separated H= here, but too hard for now */ |
| 220 | log_write(0, LOG_MAIN, "TLS error on %s (%s): %s", |
| 221 | conn_info, prefix, msg); |
| 222 | return DEFER; |
| 223 | } |
| 224 | } |
| 225 | |
| 226 | |
| 227 | |
| 228 | /************************************************* |
| 229 | * Callback to generate RSA key * |
| 230 | *************************************************/ |
| 231 | |
| 232 | /* |
| 233 | Arguments: |
| 234 | s SSL connection |
| 235 | export not used |
| 236 | keylength keylength |
| 237 | |
| 238 | Returns: pointer to generated key |
| 239 | */ |
| 240 | |
| 241 | static RSA * |
| 242 | rsa_callback(SSL *s, int export, int keylength) |
| 243 | { |
| 244 | RSA *rsa_key; |
| 245 | export = export; /* Shut picky compilers up */ |
| 246 | DEBUG(D_tls) debug_printf("Generating %d bit RSA key...\n", keylength); |
| 247 | rsa_key = RSA_generate_key(keylength, RSA_F4, NULL, NULL); |
| 248 | if (rsa_key == NULL) |
| 249 | { |
| 250 | ERR_error_string(ERR_get_error(), ssl_errstring); |
| 251 | log_write(0, LOG_MAIN|LOG_PANIC, "TLS error (RSA_generate_key): %s", |
| 252 | ssl_errstring); |
| 253 | return NULL; |
| 254 | } |
| 255 | return rsa_key; |
| 256 | } |
| 257 | |
| 258 | |
| 259 | |
| 260 | /* Extreme debug |
| 261 | #ifndef DISABLE_OCSP |
| 262 | void |
| 263 | x509_store_dump_cert_s_names(X509_STORE * store) |
| 264 | { |
| 265 | STACK_OF(X509_OBJECT) * roots= store->objs; |
| 266 | int i; |
| 267 | static uschar name[256]; |
| 268 | |
| 269 | for(i= 0; i<sk_X509_OBJECT_num(roots); i++) |
| 270 | { |
| 271 | X509_OBJECT * tmp_obj= sk_X509_OBJECT_value(roots, i); |
| 272 | if(tmp_obj->type == X509_LU_X509) |
| 273 | { |
| 274 | X509 * current_cert= tmp_obj->data.x509; |
| 275 | X509_NAME_oneline(X509_get_subject_name(current_cert), CS name, sizeof(name)); |
| 276 | name[sizeof(name)-1] = '\0'; |
| 277 | debug_printf(" %s\n", name); |
| 278 | } |
| 279 | } |
| 280 | } |
| 281 | #endif |
| 282 | */ |
| 283 | |
| 284 | |
| 285 | #ifdef EXPERIMENTAL_EVENT |
| 286 | static int |
| 287 | verify_event(tls_support * tlsp, X509 * cert, int depth, const uschar * dn, |
| 288 | BOOL *calledp, const BOOL *optionalp, const uschar * what) |
| 289 | { |
| 290 | uschar * ev; |
| 291 | uschar * yield; |
| 292 | X509 * old_cert; |
| 293 | |
| 294 | ev = tlsp == &tls_out ? client_static_cbinfo->event_action : event_action; |
| 295 | if (ev) |
| 296 | { |
| 297 | old_cert = tlsp->peercert; |
| 298 | tlsp->peercert = X509_dup(cert); |
| 299 | /* NB we do not bother setting peerdn */ |
| 300 | if ((yield = event_raise(ev, US"tls:cert", string_sprintf("%d", depth)))) |
| 301 | { |
| 302 | log_write(0, LOG_MAIN, "[%s] %s verify denied by event-action: " |
| 303 | "depth=%d cert=%s: %s", |
| 304 | tlsp == &tls_out ? deliver_host_address : sender_host_address, |
| 305 | what, depth, dn, yield); |
| 306 | *calledp = TRUE; |
| 307 | if (!*optionalp) |
| 308 | { |
| 309 | if (old_cert) tlsp->peercert = old_cert; /* restore 1st failing cert */ |
| 310 | return 1; /* reject (leaving peercert set) */ |
| 311 | } |
| 312 | DEBUG(D_tls) debug_printf("Event-action verify failure overridden " |
| 313 | "(host in tls_try_verify_hosts)\n"); |
| 314 | } |
| 315 | X509_free(tlsp->peercert); |
| 316 | tlsp->peercert = old_cert; |
| 317 | } |
| 318 | return 0; |
| 319 | } |
| 320 | #endif |
| 321 | |
| 322 | /************************************************* |
| 323 | * Callback for verification * |
| 324 | *************************************************/ |
| 325 | |
| 326 | /* The SSL library does certificate verification if set up to do so. This |
| 327 | callback has the current yes/no state is in "state". If verification succeeded, |
| 328 | we set the certificate-verified flag. If verification failed, what happens |
| 329 | depends on whether the client is required to present a verifiable certificate |
| 330 | or not. |
| 331 | |
| 332 | If verification is optional, we change the state to yes, but still log the |
| 333 | verification error. For some reason (it really would help to have proper |
| 334 | documentation of OpenSSL), this callback function then gets called again, this |
| 335 | time with state = 1. We must take care not to set the private verified flag on |
| 336 | the second time through. |
| 337 | |
| 338 | Note: this function is not called if the client fails to present a certificate |
| 339 | when asked. We get here only if a certificate has been received. Handling of |
| 340 | optional verification for this case is done when requesting SSL to verify, by |
| 341 | setting SSL_VERIFY_FAIL_IF_NO_PEER_CERT in the non-optional case. |
| 342 | |
| 343 | May be called multiple times for different issues with a certificate, even |
| 344 | for a given "depth" in the certificate chain. |
| 345 | |
| 346 | Arguments: |
| 347 | state current yes/no state as 1/0 |
| 348 | x509ctx certificate information. |
| 349 | client TRUE for client startup, FALSE for server startup |
| 350 | |
| 351 | Returns: 1 if verified, 0 if not |
| 352 | */ |
| 353 | |
| 354 | static int |
| 355 | verify_callback(int state, X509_STORE_CTX *x509ctx, |
| 356 | tls_support *tlsp, BOOL *calledp, BOOL *optionalp) |
| 357 | { |
| 358 | X509 * cert = X509_STORE_CTX_get_current_cert(x509ctx); |
| 359 | int depth = X509_STORE_CTX_get_error_depth(x509ctx); |
| 360 | uschar dn[256]; |
| 361 | |
| 362 | X509_NAME_oneline(X509_get_subject_name(cert), CS dn, sizeof(dn)); |
| 363 | dn[sizeof(dn)-1] = '\0'; |
| 364 | |
| 365 | if (state == 0) |
| 366 | { |
| 367 | log_write(0, LOG_MAIN, "[%s] SSL verify error: depth=%d error=%s cert=%s", |
| 368 | tlsp == &tls_out ? deliver_host_address : sender_host_address, |
| 369 | depth, |
| 370 | X509_verify_cert_error_string(X509_STORE_CTX_get_error(x509ctx)), |
| 371 | dn); |
| 372 | *calledp = TRUE; |
| 373 | if (!*optionalp) |
| 374 | { |
| 375 | if (!tlsp->peercert) |
| 376 | tlsp->peercert = X509_dup(cert); /* record failing cert */ |
| 377 | return 0; /* reject */ |
| 378 | } |
| 379 | DEBUG(D_tls) debug_printf("SSL verify failure overridden (host in " |
| 380 | "tls_try_verify_hosts)\n"); |
| 381 | } |
| 382 | |
| 383 | else if (depth != 0) |
| 384 | { |
| 385 | DEBUG(D_tls) debug_printf("SSL verify ok: depth=%d SN=%s\n", depth, dn); |
| 386 | #ifndef DISABLE_OCSP |
| 387 | if (tlsp == &tls_out && client_static_cbinfo->u_ocsp.client.verify_store) |
| 388 | { /* client, wanting stapling */ |
| 389 | /* Add the server cert's signing chain as the one |
| 390 | for the verification of the OCSP stapled information. */ |
| 391 | |
| 392 | if (!X509_STORE_add_cert(client_static_cbinfo->u_ocsp.client.verify_store, |
| 393 | cert)) |
| 394 | ERR_clear_error(); |
| 395 | } |
| 396 | #endif |
| 397 | #ifdef EXPERIMENTAL_EVENT |
| 398 | if (verify_event(tlsp, cert, depth, dn, calledp, optionalp, US"SSL")) |
| 399 | return 0; /* reject, with peercert set */ |
| 400 | #endif |
| 401 | } |
| 402 | else |
| 403 | { |
| 404 | const uschar * verify_cert_hostnames; |
| 405 | |
| 406 | if ( tlsp == &tls_out |
| 407 | && ((verify_cert_hostnames = client_static_cbinfo->verify_cert_hostnames))) |
| 408 | /* client, wanting hostname check */ |
| 409 | { |
| 410 | |
| 411 | #ifdef EXIM_HAVE_OPENSSL_CHECKHOST |
| 412 | # ifndef X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS |
| 413 | # define X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS 0 |
| 414 | # endif |
| 415 | # ifndef X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS |
| 416 | # define X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS 0 |
| 417 | # endif |
| 418 | int sep = 0; |
| 419 | const uschar * list = verify_cert_hostnames; |
| 420 | uschar * name; |
| 421 | int rc; |
| 422 | while ((name = string_nextinlist(&list, &sep, NULL, 0))) |
| 423 | if ((rc = X509_check_host(cert, name, 0, |
| 424 | X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS |
| 425 | | X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS, |
| 426 | NULL))) |
| 427 | { |
| 428 | if (rc < 0) |
| 429 | { |
| 430 | log_write(0, LOG_MAIN, "[%s] SSL verify error: internal error", |
| 431 | tlsp == &tls_out ? deliver_host_address : sender_host_address); |
| 432 | name = NULL; |
| 433 | } |
| 434 | break; |
| 435 | } |
| 436 | if (!name) |
| 437 | #else |
| 438 | if (!tls_is_name_for_cert(verify_cert_hostnames, cert)) |
| 439 | #endif |
| 440 | { |
| 441 | log_write(0, LOG_MAIN, |
| 442 | "[%s] SSL verify error: certificate name mismatch: \"%s\"", |
| 443 | tlsp == &tls_out ? deliver_host_address : sender_host_address, |
| 444 | dn); |
| 445 | *calledp = TRUE; |
| 446 | if (!*optionalp) |
| 447 | { |
| 448 | if (!tlsp->peercert) |
| 449 | tlsp->peercert = X509_dup(cert); /* record failing cert */ |
| 450 | return 0; /* reject */ |
| 451 | } |
| 452 | DEBUG(D_tls) debug_printf("SSL verify failure overridden (host in " |
| 453 | "tls_try_verify_hosts)\n"); |
| 454 | } |
| 455 | } |
| 456 | |
| 457 | #ifdef EXPERIMENTAL_EVENT |
| 458 | if (verify_event(tlsp, cert, depth, dn, calledp, optionalp, US"SSL")) |
| 459 | return 0; /* reject, with peercert set */ |
| 460 | #endif |
| 461 | |
| 462 | DEBUG(D_tls) debug_printf("SSL%s verify ok: depth=0 SN=%s\n", |
| 463 | *calledp ? "" : " authenticated", dn); |
| 464 | if (!*calledp) tlsp->certificate_verified = TRUE; |
| 465 | *calledp = TRUE; |
| 466 | } |
| 467 | |
| 468 | return 1; /* accept, at least for this level */ |
| 469 | } |
| 470 | |
| 471 | static int |
| 472 | verify_callback_client(int state, X509_STORE_CTX *x509ctx) |
| 473 | { |
| 474 | return verify_callback(state, x509ctx, &tls_out, &client_verify_callback_called, &client_verify_optional); |
| 475 | } |
| 476 | |
| 477 | static int |
| 478 | verify_callback_server(int state, X509_STORE_CTX *x509ctx) |
| 479 | { |
| 480 | return verify_callback(state, x509ctx, &tls_in, &server_verify_callback_called, &server_verify_optional); |
| 481 | } |
| 482 | |
| 483 | |
| 484 | #ifdef EXPERIMENTAL_DANE |
| 485 | |
| 486 | /* This gets called *by* the dane library verify callback, which interposes |
| 487 | itself. |
| 488 | */ |
| 489 | static int |
| 490 | verify_callback_client_dane(int state, X509_STORE_CTX * x509ctx) |
| 491 | { |
| 492 | X509 * cert = X509_STORE_CTX_get_current_cert(x509ctx); |
| 493 | uschar dn[256]; |
| 494 | #ifdef EXPERIMENTAL_EVENT |
| 495 | int depth = X509_STORE_CTX_get_error_depth(x509ctx); |
| 496 | BOOL dummy_called, optional = FALSE; |
| 497 | #endif |
| 498 | |
| 499 | X509_NAME_oneline(X509_get_subject_name(cert), CS dn, sizeof(dn)); |
| 500 | dn[sizeof(dn)-1] = '\0'; |
| 501 | |
| 502 | DEBUG(D_tls) debug_printf("verify_callback_client_dane: %s\n", dn); |
| 503 | |
| 504 | #ifdef EXPERIMENTAL_EVENT |
| 505 | if (verify_event(&tls_out, cert, depth, dn, |
| 506 | &dummy_called, &optional, US"DANE")) |
| 507 | return 0; /* reject, with peercert set */ |
| 508 | #endif |
| 509 | |
| 510 | if (state == 1) |
| 511 | tls_out.dane_verified = |
| 512 | tls_out.certificate_verified = TRUE; |
| 513 | return 1; |
| 514 | } |
| 515 | |
| 516 | #endif /*EXPERIMENTAL_DANE*/ |
| 517 | |
| 518 | |
| 519 | /************************************************* |
| 520 | * Information callback * |
| 521 | *************************************************/ |
| 522 | |
| 523 | /* The SSL library functions call this from time to time to indicate what they |
| 524 | are doing. We copy the string to the debugging output when TLS debugging has |
| 525 | been requested. |
| 526 | |
| 527 | Arguments: |
| 528 | s the SSL connection |
| 529 | where |
| 530 | ret |
| 531 | |
| 532 | Returns: nothing |
| 533 | */ |
| 534 | |
| 535 | static void |
| 536 | info_callback(SSL *s, int where, int ret) |
| 537 | { |
| 538 | where = where; |
| 539 | ret = ret; |
| 540 | DEBUG(D_tls) debug_printf("SSL info: %s\n", SSL_state_string_long(s)); |
| 541 | } |
| 542 | |
| 543 | |
| 544 | |
| 545 | /************************************************* |
| 546 | * Initialize for DH * |
| 547 | *************************************************/ |
| 548 | |
| 549 | /* If dhparam is set, expand it, and load up the parameters for DH encryption. |
| 550 | |
| 551 | Arguments: |
| 552 | sctx The current SSL CTX (inbound or outbound) |
| 553 | dhparam DH parameter file or fixed parameter identity string |
| 554 | host connected host, if client; NULL if server |
| 555 | |
| 556 | Returns: TRUE if OK (nothing to set up, or setup worked) |
| 557 | */ |
| 558 | |
| 559 | static BOOL |
| 560 | init_dh(SSL_CTX *sctx, uschar *dhparam, const host_item *host) |
| 561 | { |
| 562 | BIO *bio; |
| 563 | DH *dh; |
| 564 | uschar *dhexpanded; |
| 565 | const char *pem; |
| 566 | |
| 567 | if (!expand_check(dhparam, US"tls_dhparam", &dhexpanded)) |
| 568 | return FALSE; |
| 569 | |
| 570 | if (!dhexpanded || !*dhexpanded) |
| 571 | bio = BIO_new_mem_buf(CS std_dh_prime_default(), -1); |
| 572 | else if (dhexpanded[0] == '/') |
| 573 | { |
| 574 | if (!(bio = BIO_new_file(CS dhexpanded, "r"))) |
| 575 | { |
| 576 | tls_error(string_sprintf("could not read dhparams file %s", dhexpanded), |
| 577 | host, US strerror(errno)); |
| 578 | return FALSE; |
| 579 | } |
| 580 | } |
| 581 | else |
| 582 | { |
| 583 | if (Ustrcmp(dhexpanded, "none") == 0) |
| 584 | { |
| 585 | DEBUG(D_tls) debug_printf("Requested no DH parameters.\n"); |
| 586 | return TRUE; |
| 587 | } |
| 588 | |
| 589 | if (!(pem = std_dh_prime_named(dhexpanded))) |
| 590 | { |
| 591 | tls_error(string_sprintf("Unknown standard DH prime \"%s\"", dhexpanded), |
| 592 | host, US strerror(errno)); |
| 593 | return FALSE; |
| 594 | } |
| 595 | bio = BIO_new_mem_buf(CS pem, -1); |
| 596 | } |
| 597 | |
| 598 | if (!(dh = PEM_read_bio_DHparams(bio, NULL, NULL, NULL))) |
| 599 | { |
| 600 | BIO_free(bio); |
| 601 | tls_error(string_sprintf("Could not read tls_dhparams \"%s\"", dhexpanded), |
| 602 | host, NULL); |
| 603 | return FALSE; |
| 604 | } |
| 605 | |
| 606 | /* Even if it is larger, we silently return success rather than cause things |
| 607 | * to fail out, so that a too-large DH will not knock out all TLS; it's a |
| 608 | * debatable choice. */ |
| 609 | if ((8*DH_size(dh)) > tls_dh_max_bits) |
| 610 | { |
| 611 | DEBUG(D_tls) |
| 612 | debug_printf("dhparams file %d bits, is > tls_dh_max_bits limit of %d", |
| 613 | 8*DH_size(dh), tls_dh_max_bits); |
| 614 | } |
| 615 | else |
| 616 | { |
| 617 | SSL_CTX_set_tmp_dh(sctx, dh); |
| 618 | DEBUG(D_tls) |
| 619 | debug_printf("Diffie-Hellman initialized from %s with %d-bit prime\n", |
| 620 | dhexpanded ? dhexpanded : US"default", 8*DH_size(dh)); |
| 621 | } |
| 622 | |
| 623 | DH_free(dh); |
| 624 | BIO_free(bio); |
| 625 | |
| 626 | return TRUE; |
| 627 | } |
| 628 | |
| 629 | |
| 630 | |
| 631 | |
| 632 | /************************************************* |
| 633 | * Initialize for ECDH * |
| 634 | *************************************************/ |
| 635 | |
| 636 | /* Load parameters for ECDH encryption. |
| 637 | |
| 638 | For now, we stick to NIST P-256 because: it's simple and easy to configure; |
| 639 | it avoids any patent issues that might bite redistributors; despite events in |
| 640 | the news and concerns over curve choices, we're not cryptographers, we're not |
| 641 | pretending to be, and this is "good enough" to be better than no support, |
| 642 | protecting against most adversaries. Given another year or two, there might |
| 643 | be sufficient clarity about a "right" way forward to let us make an informed |
| 644 | decision, instead of a knee-jerk reaction. |
| 645 | |
| 646 | Longer-term, we should look at supporting both various named curves and |
| 647 | external files generated with "openssl ecparam", much as we do for init_dh(). |
| 648 | We should also support "none" as a value, to explicitly avoid initialisation. |
| 649 | |
| 650 | Patches welcome. |
| 651 | |
| 652 | Arguments: |
| 653 | sctx The current SSL CTX (inbound or outbound) |
| 654 | host connected host, if client; NULL if server |
| 655 | |
| 656 | Returns: TRUE if OK (nothing to set up, or setup worked) |
| 657 | */ |
| 658 | |
| 659 | static BOOL |
| 660 | init_ecdh(SSL_CTX * sctx, host_item * host) |
| 661 | { |
| 662 | #ifdef OPENSSL_NO_ECDH |
| 663 | return TRUE; |
| 664 | #else |
| 665 | |
| 666 | EC_KEY * ecdh; |
| 667 | uschar * exp_curve; |
| 668 | int nid; |
| 669 | BOOL rv; |
| 670 | |
| 671 | if (host) /* No ECDH setup for clients, only for servers */ |
| 672 | return TRUE; |
| 673 | |
| 674 | # ifndef EXIM_HAVE_ECDH |
| 675 | DEBUG(D_tls) |
| 676 | debug_printf("No OpenSSL API to define ECDH parameters, skipping\n"); |
| 677 | return TRUE; |
| 678 | # else |
| 679 | |
| 680 | if (!expand_check(tls_eccurve, US"tls_eccurve", &exp_curve)) |
| 681 | return FALSE; |
| 682 | if (!exp_curve || !*exp_curve) |
| 683 | return TRUE; |
| 684 | |
| 685 | # ifdef EXIM_HAVE_OPENSSL_ECDH_AUTO |
| 686 | /* check if new enough library to support auto ECDH temp key parameter selection */ |
| 687 | if (Ustrcmp(exp_curve, "auto") == 0) |
| 688 | { |
| 689 | DEBUG(D_tls) debug_printf( |
| 690 | "ECDH temp key parameter settings: OpenSSL 1.2+ autoselection\n"); |
| 691 | SSL_CTX_set_ecdh_auto(sctx, 1); |
| 692 | return TRUE; |
| 693 | } |
| 694 | # endif |
| 695 | |
| 696 | DEBUG(D_tls) debug_printf("ECDH: curve '%s'\n", exp_curve); |
| 697 | if ( (nid = OBJ_sn2nid (CCS exp_curve)) == NID_undef |
| 698 | # ifdef EXIM_HAVE_OPENSSL_EC_NIST2NID |
| 699 | && (nid = EC_curve_nist2nid(CCS exp_curve)) == NID_undef |
| 700 | # endif |
| 701 | ) |
| 702 | { |
| 703 | tls_error(string_sprintf("Unknown curve name tls_eccurve '%s'", |
| 704 | exp_curve), |
| 705 | host, NULL); |
| 706 | return FALSE; |
| 707 | } |
| 708 | |
| 709 | if (!(ecdh = EC_KEY_new_by_curve_name(nid))) |
| 710 | { |
| 711 | tls_error(US"Unable to create ec curve", host, NULL); |
| 712 | return FALSE; |
| 713 | } |
| 714 | |
| 715 | /* The "tmp" in the name here refers to setting a temporary key |
| 716 | not to the stability of the interface. */ |
| 717 | |
| 718 | if ((rv = SSL_CTX_set_tmp_ecdh(sctx, ecdh) == 0)) |
| 719 | tls_error(string_sprintf("Error enabling '%s' curve", exp_curve), host, NULL); |
| 720 | else |
| 721 | DEBUG(D_tls) debug_printf("ECDH: enabled '%s' curve\n", exp_curve); |
| 722 | |
| 723 | EC_KEY_free(ecdh); |
| 724 | return !rv; |
| 725 | |
| 726 | # endif /*EXIM_HAVE_ECDH*/ |
| 727 | #endif /*OPENSSL_NO_ECDH*/ |
| 728 | } |
| 729 | |
| 730 | |
| 731 | |
| 732 | |
| 733 | #ifndef DISABLE_OCSP |
| 734 | /************************************************* |
| 735 | * Load OCSP information into state * |
| 736 | *************************************************/ |
| 737 | |
| 738 | /* Called to load the server OCSP response from the given file into memory, once |
| 739 | caller has determined this is needed. Checks validity. Debugs a message |
| 740 | if invalid. |
| 741 | |
| 742 | ASSUMES: single response, for single cert. |
| 743 | |
| 744 | Arguments: |
| 745 | sctx the SSL_CTX* to update |
| 746 | cbinfo various parts of session state |
| 747 | expanded the filename putatively holding an OCSP response |
| 748 | |
| 749 | */ |
| 750 | |
| 751 | static void |
| 752 | ocsp_load_response(SSL_CTX *sctx, tls_ext_ctx_cb *cbinfo, const uschar *expanded) |
| 753 | { |
| 754 | BIO *bio; |
| 755 | OCSP_RESPONSE *resp; |
| 756 | OCSP_BASICRESP *basic_response; |
| 757 | OCSP_SINGLERESP *single_response; |
| 758 | ASN1_GENERALIZEDTIME *rev, *thisupd, *nextupd; |
| 759 | X509_STORE *store; |
| 760 | unsigned long verify_flags; |
| 761 | int status, reason, i; |
| 762 | |
| 763 | cbinfo->u_ocsp.server.file_expanded = string_copy(expanded); |
| 764 | if (cbinfo->u_ocsp.server.response) |
| 765 | { |
| 766 | OCSP_RESPONSE_free(cbinfo->u_ocsp.server.response); |
| 767 | cbinfo->u_ocsp.server.response = NULL; |
| 768 | } |
| 769 | |
| 770 | bio = BIO_new_file(CS cbinfo->u_ocsp.server.file_expanded, "rb"); |
| 771 | if (!bio) |
| 772 | { |
| 773 | DEBUG(D_tls) debug_printf("Failed to open OCSP response file \"%s\"\n", |
| 774 | cbinfo->u_ocsp.server.file_expanded); |
| 775 | return; |
| 776 | } |
| 777 | |
| 778 | resp = d2i_OCSP_RESPONSE_bio(bio, NULL); |
| 779 | BIO_free(bio); |
| 780 | if (!resp) |
| 781 | { |
| 782 | DEBUG(D_tls) debug_printf("Error reading OCSP response.\n"); |
| 783 | return; |
| 784 | } |
| 785 | |
| 786 | status = OCSP_response_status(resp); |
| 787 | if (status != OCSP_RESPONSE_STATUS_SUCCESSFUL) |
| 788 | { |
| 789 | DEBUG(D_tls) debug_printf("OCSP response not valid: %s (%d)\n", |
| 790 | OCSP_response_status_str(status), status); |
| 791 | goto bad; |
| 792 | } |
| 793 | |
| 794 | basic_response = OCSP_response_get1_basic(resp); |
| 795 | if (!basic_response) |
| 796 | { |
| 797 | DEBUG(D_tls) |
| 798 | debug_printf("OCSP response parse error: unable to extract basic response.\n"); |
| 799 | goto bad; |
| 800 | } |
| 801 | |
| 802 | store = SSL_CTX_get_cert_store(sctx); |
| 803 | verify_flags = OCSP_NOVERIFY; /* check sigs, but not purpose */ |
| 804 | |
| 805 | /* May need to expose ability to adjust those flags? |
| 806 | OCSP_NOSIGS OCSP_NOVERIFY OCSP_NOCHAIN OCSP_NOCHECKS OCSP_NOEXPLICIT |
| 807 | OCSP_TRUSTOTHER OCSP_NOINTERN */ |
| 808 | |
| 809 | i = OCSP_basic_verify(basic_response, NULL, store, verify_flags); |
| 810 | if (i <= 0) |
| 811 | { |
| 812 | DEBUG(D_tls) { |
| 813 | ERR_error_string(ERR_get_error(), ssl_errstring); |
| 814 | debug_printf("OCSP response verify failure: %s\n", US ssl_errstring); |
| 815 | } |
| 816 | goto bad; |
| 817 | } |
| 818 | |
| 819 | /* Here's the simplifying assumption: there's only one response, for the |
| 820 | one certificate we use, and nothing for anything else in a chain. If this |
| 821 | proves false, we need to extract a cert id from our issued cert |
| 822 | (tls_certificate) and use that for OCSP_resp_find_status() (which finds the |
| 823 | right cert in the stack and then calls OCSP_single_get0_status()). |
| 824 | |
| 825 | I'm hoping to avoid reworking a bunch more of how we handle state here. */ |
| 826 | single_response = OCSP_resp_get0(basic_response, 0); |
| 827 | if (!single_response) |
| 828 | { |
| 829 | DEBUG(D_tls) |
| 830 | debug_printf("Unable to get first response from OCSP basic response.\n"); |
| 831 | goto bad; |
| 832 | } |
| 833 | |
| 834 | status = OCSP_single_get0_status(single_response, &reason, &rev, &thisupd, &nextupd); |
| 835 | if (status != V_OCSP_CERTSTATUS_GOOD) |
| 836 | { |
| 837 | DEBUG(D_tls) debug_printf("OCSP response bad cert status: %s (%d) %s (%d)\n", |
| 838 | OCSP_cert_status_str(status), status, |
| 839 | OCSP_crl_reason_str(reason), reason); |
| 840 | goto bad; |
| 841 | } |
| 842 | |
| 843 | if (!OCSP_check_validity(thisupd, nextupd, EXIM_OCSP_SKEW_SECONDS, EXIM_OCSP_MAX_AGE)) |
| 844 | { |
| 845 | DEBUG(D_tls) debug_printf("OCSP status invalid times.\n"); |
| 846 | goto bad; |
| 847 | } |
| 848 | |
| 849 | supply_response: |
| 850 | cbinfo->u_ocsp.server.response = resp; |
| 851 | return; |
| 852 | |
| 853 | bad: |
| 854 | if (running_in_test_harness) |
| 855 | { |
| 856 | extern char ** environ; |
| 857 | uschar ** p; |
| 858 | for (p = USS environ; *p != NULL; p++) |
| 859 | if (Ustrncmp(*p, "EXIM_TESTHARNESS_DISABLE_OCSPVALIDITYCHECK", 42) == 0) |
| 860 | { |
| 861 | DEBUG(D_tls) debug_printf("Supplying known bad OCSP response\n"); |
| 862 | goto supply_response; |
| 863 | } |
| 864 | } |
| 865 | return; |
| 866 | } |
| 867 | #endif /*!DISABLE_OCSP*/ |
| 868 | |
| 869 | |
| 870 | |
| 871 | |
| 872 | /************************************************* |
| 873 | * Expand key and cert file specs * |
| 874 | *************************************************/ |
| 875 | |
| 876 | /* Called once during tls_init and possibly again during TLS setup, for a |
| 877 | new context, if Server Name Indication was used and tls_sni was seen in |
| 878 | the certificate string. |
| 879 | |
| 880 | Arguments: |
| 881 | sctx the SSL_CTX* to update |
| 882 | cbinfo various parts of session state |
| 883 | |
| 884 | Returns: OK/DEFER/FAIL |
| 885 | */ |
| 886 | |
| 887 | static int |
| 888 | tls_expand_session_files(SSL_CTX *sctx, tls_ext_ctx_cb *cbinfo) |
| 889 | { |
| 890 | uschar *expanded; |
| 891 | |
| 892 | if (cbinfo->certificate == NULL) |
| 893 | return OK; |
| 894 | |
| 895 | if (Ustrstr(cbinfo->certificate, US"tls_sni") || |
| 896 | Ustrstr(cbinfo->certificate, US"tls_in_sni") || |
| 897 | Ustrstr(cbinfo->certificate, US"tls_out_sni") |
| 898 | ) |
| 899 | reexpand_tls_files_for_sni = TRUE; |
| 900 | |
| 901 | if (!expand_check(cbinfo->certificate, US"tls_certificate", &expanded)) |
| 902 | return DEFER; |
| 903 | |
| 904 | if (expanded != NULL) |
| 905 | { |
| 906 | DEBUG(D_tls) debug_printf("tls_certificate file %s\n", expanded); |
| 907 | if (!SSL_CTX_use_certificate_chain_file(sctx, CS expanded)) |
| 908 | return tls_error(string_sprintf( |
| 909 | "SSL_CTX_use_certificate_chain_file file=%s", expanded), |
| 910 | cbinfo->host, NULL); |
| 911 | } |
| 912 | |
| 913 | if (cbinfo->privatekey != NULL && |
| 914 | !expand_check(cbinfo->privatekey, US"tls_privatekey", &expanded)) |
| 915 | return DEFER; |
| 916 | |
| 917 | /* If expansion was forced to fail, key_expanded will be NULL. If the result |
| 918 | of the expansion is an empty string, ignore it also, and assume the private |
| 919 | key is in the same file as the certificate. */ |
| 920 | |
| 921 | if (expanded != NULL && *expanded != 0) |
| 922 | { |
| 923 | DEBUG(D_tls) debug_printf("tls_privatekey file %s\n", expanded); |
| 924 | if (!SSL_CTX_use_PrivateKey_file(sctx, CS expanded, SSL_FILETYPE_PEM)) |
| 925 | return tls_error(string_sprintf( |
| 926 | "SSL_CTX_use_PrivateKey_file file=%s", expanded), cbinfo->host, NULL); |
| 927 | } |
| 928 | |
| 929 | #ifndef DISABLE_OCSP |
| 930 | if (cbinfo->is_server && cbinfo->u_ocsp.server.file != NULL) |
| 931 | { |
| 932 | if (!expand_check(cbinfo->u_ocsp.server.file, US"tls_ocsp_file", &expanded)) |
| 933 | return DEFER; |
| 934 | |
| 935 | if (expanded != NULL && *expanded != 0) |
| 936 | { |
| 937 | DEBUG(D_tls) debug_printf("tls_ocsp_file %s\n", expanded); |
| 938 | if (cbinfo->u_ocsp.server.file_expanded && |
| 939 | (Ustrcmp(expanded, cbinfo->u_ocsp.server.file_expanded) == 0)) |
| 940 | { |
| 941 | DEBUG(D_tls) |
| 942 | debug_printf("tls_ocsp_file value unchanged, using existing values.\n"); |
| 943 | } else { |
| 944 | ocsp_load_response(sctx, cbinfo, expanded); |
| 945 | } |
| 946 | } |
| 947 | } |
| 948 | #endif |
| 949 | |
| 950 | return OK; |
| 951 | } |
| 952 | |
| 953 | |
| 954 | |
| 955 | |
| 956 | /************************************************* |
| 957 | * Callback to handle SNI * |
| 958 | *************************************************/ |
| 959 | |
| 960 | /* Called when acting as server during the TLS session setup if a Server Name |
| 961 | Indication extension was sent by the client. |
| 962 | |
| 963 | API documentation is OpenSSL s_server.c implementation. |
| 964 | |
| 965 | Arguments: |
| 966 | s SSL* of the current session |
| 967 | ad unknown (part of OpenSSL API) (unused) |
| 968 | arg Callback of "our" registered data |
| 969 | |
| 970 | Returns: SSL_TLSEXT_ERR_{OK,ALERT_WARNING,ALERT_FATAL,NOACK} |
| 971 | */ |
| 972 | |
| 973 | #ifdef EXIM_HAVE_OPENSSL_TLSEXT |
| 974 | static int |
| 975 | tls_servername_cb(SSL *s, int *ad ARG_UNUSED, void *arg) |
| 976 | { |
| 977 | const char *servername = SSL_get_servername(s, TLSEXT_NAMETYPE_host_name); |
| 978 | tls_ext_ctx_cb *cbinfo = (tls_ext_ctx_cb *) arg; |
| 979 | int rc; |
| 980 | int old_pool = store_pool; |
| 981 | |
| 982 | if (!servername) |
| 983 | return SSL_TLSEXT_ERR_OK; |
| 984 | |
| 985 | DEBUG(D_tls) debug_printf("Received TLS SNI \"%s\"%s\n", servername, |
| 986 | reexpand_tls_files_for_sni ? "" : " (unused for certificate selection)"); |
| 987 | |
| 988 | /* Make the extension value available for expansion */ |
| 989 | store_pool = POOL_PERM; |
| 990 | tls_in.sni = string_copy(US servername); |
| 991 | store_pool = old_pool; |
| 992 | |
| 993 | if (!reexpand_tls_files_for_sni) |
| 994 | return SSL_TLSEXT_ERR_OK; |
| 995 | |
| 996 | /* Can't find an SSL_CTX_clone() or equivalent, so we do it manually; |
| 997 | not confident that memcpy wouldn't break some internal reference counting. |
| 998 | Especially since there's a references struct member, which would be off. */ |
| 999 | |
| 1000 | if (!(server_sni = SSL_CTX_new(SSLv23_server_method()))) |
| 1001 | { |
| 1002 | ERR_error_string(ERR_get_error(), ssl_errstring); |
| 1003 | DEBUG(D_tls) debug_printf("SSL_CTX_new() failed: %s\n", ssl_errstring); |
| 1004 | return SSL_TLSEXT_ERR_NOACK; |
| 1005 | } |
| 1006 | |
| 1007 | /* Not sure how many of these are actually needed, since SSL object |
| 1008 | already exists. Might even need this selfsame callback, for reneg? */ |
| 1009 | |
| 1010 | SSL_CTX_set_info_callback(server_sni, SSL_CTX_get_info_callback(server_ctx)); |
| 1011 | SSL_CTX_set_mode(server_sni, SSL_CTX_get_mode(server_ctx)); |
| 1012 | SSL_CTX_set_options(server_sni, SSL_CTX_get_options(server_ctx)); |
| 1013 | SSL_CTX_set_timeout(server_sni, SSL_CTX_get_timeout(server_ctx)); |
| 1014 | SSL_CTX_set_tlsext_servername_callback(server_sni, tls_servername_cb); |
| 1015 | SSL_CTX_set_tlsext_servername_arg(server_sni, cbinfo); |
| 1016 | |
| 1017 | if ( !init_dh(server_sni, cbinfo->dhparam, NULL) |
| 1018 | || !init_ecdh(server_sni, NULL) |
| 1019 | ) |
| 1020 | return SSL_TLSEXT_ERR_NOACK; |
| 1021 | |
| 1022 | if (cbinfo->server_cipher_list) |
| 1023 | SSL_CTX_set_cipher_list(server_sni, CS cbinfo->server_cipher_list); |
| 1024 | #ifndef DISABLE_OCSP |
| 1025 | if (cbinfo->u_ocsp.server.file) |
| 1026 | { |
| 1027 | SSL_CTX_set_tlsext_status_cb(server_sni, tls_server_stapling_cb); |
| 1028 | SSL_CTX_set_tlsext_status_arg(server_sni, cbinfo); |
| 1029 | } |
| 1030 | #endif |
| 1031 | |
| 1032 | rc = setup_certs(server_sni, tls_verify_certificates, tls_crl, NULL, FALSE, verify_callback_server); |
| 1033 | if (rc != OK) return SSL_TLSEXT_ERR_NOACK; |
| 1034 | |
| 1035 | /* do this after setup_certs, because this can require the certs for verifying |
| 1036 | OCSP information. */ |
| 1037 | if ((rc = tls_expand_session_files(server_sni, cbinfo)) != OK) |
| 1038 | return SSL_TLSEXT_ERR_NOACK; |
| 1039 | |
| 1040 | DEBUG(D_tls) debug_printf("Switching SSL context.\n"); |
| 1041 | SSL_set_SSL_CTX(s, server_sni); |
| 1042 | |
| 1043 | return SSL_TLSEXT_ERR_OK; |
| 1044 | } |
| 1045 | #endif /* EXIM_HAVE_OPENSSL_TLSEXT */ |
| 1046 | |
| 1047 | |
| 1048 | |
| 1049 | |
| 1050 | #ifndef DISABLE_OCSP |
| 1051 | |
| 1052 | /************************************************* |
| 1053 | * Callback to handle OCSP Stapling * |
| 1054 | *************************************************/ |
| 1055 | |
| 1056 | /* Called when acting as server during the TLS session setup if the client |
| 1057 | requests OCSP information with a Certificate Status Request. |
| 1058 | |
| 1059 | Documentation via openssl s_server.c and the Apache patch from the OpenSSL |
| 1060 | project. |
| 1061 | |
| 1062 | */ |
| 1063 | |
| 1064 | static int |
| 1065 | tls_server_stapling_cb(SSL *s, void *arg) |
| 1066 | { |
| 1067 | const tls_ext_ctx_cb *cbinfo = (tls_ext_ctx_cb *) arg; |
| 1068 | uschar *response_der; |
| 1069 | int response_der_len; |
| 1070 | |
| 1071 | DEBUG(D_tls) |
| 1072 | debug_printf("Received TLS status request (OCSP stapling); %s response\n", |
| 1073 | cbinfo->u_ocsp.server.response ? "have" : "lack"); |
| 1074 | |
| 1075 | tls_in.ocsp = OCSP_NOT_RESP; |
| 1076 | if (!cbinfo->u_ocsp.server.response) |
| 1077 | return SSL_TLSEXT_ERR_NOACK; |
| 1078 | |
| 1079 | response_der = NULL; |
| 1080 | response_der_len = i2d_OCSP_RESPONSE(cbinfo->u_ocsp.server.response, |
| 1081 | &response_der); |
| 1082 | if (response_der_len <= 0) |
| 1083 | return SSL_TLSEXT_ERR_NOACK; |
| 1084 | |
| 1085 | SSL_set_tlsext_status_ocsp_resp(server_ssl, response_der, response_der_len); |
| 1086 | tls_in.ocsp = OCSP_VFIED; |
| 1087 | return SSL_TLSEXT_ERR_OK; |
| 1088 | } |
| 1089 | |
| 1090 | |
| 1091 | static void |
| 1092 | time_print(BIO * bp, const char * str, ASN1_GENERALIZEDTIME * time) |
| 1093 | { |
| 1094 | BIO_printf(bp, "\t%s: ", str); |
| 1095 | ASN1_GENERALIZEDTIME_print(bp, time); |
| 1096 | BIO_puts(bp, "\n"); |
| 1097 | } |
| 1098 | |
| 1099 | static int |
| 1100 | tls_client_stapling_cb(SSL *s, void *arg) |
| 1101 | { |
| 1102 | tls_ext_ctx_cb * cbinfo = arg; |
| 1103 | const unsigned char * p; |
| 1104 | int len; |
| 1105 | OCSP_RESPONSE * rsp; |
| 1106 | OCSP_BASICRESP * bs; |
| 1107 | int i; |
| 1108 | |
| 1109 | DEBUG(D_tls) debug_printf("Received TLS status response (OCSP stapling):"); |
| 1110 | len = SSL_get_tlsext_status_ocsp_resp(s, &p); |
| 1111 | if(!p) |
| 1112 | { |
| 1113 | /* Expect this when we requested ocsp but got none */ |
| 1114 | if ( cbinfo->u_ocsp.client.verify_required |
| 1115 | && log_extra_selector & LX_tls_cipher) |
| 1116 | log_write(0, LOG_MAIN, "Received TLS status callback, null content"); |
| 1117 | else |
| 1118 | DEBUG(D_tls) debug_printf(" null\n"); |
| 1119 | return cbinfo->u_ocsp.client.verify_required ? 0 : 1; |
| 1120 | } |
| 1121 | |
| 1122 | if(!(rsp = d2i_OCSP_RESPONSE(NULL, &p, len))) |
| 1123 | { |
| 1124 | tls_out.ocsp = OCSP_FAILED; |
| 1125 | if (log_extra_selector & LX_tls_cipher) |
| 1126 | log_write(0, LOG_MAIN, "Received TLS cert status response, parse error"); |
| 1127 | else |
| 1128 | DEBUG(D_tls) debug_printf(" parse error\n"); |
| 1129 | return 0; |
| 1130 | } |
| 1131 | |
| 1132 | if(!(bs = OCSP_response_get1_basic(rsp))) |
| 1133 | { |
| 1134 | tls_out.ocsp = OCSP_FAILED; |
| 1135 | if (log_extra_selector & LX_tls_cipher) |
| 1136 | log_write(0, LOG_MAIN, "Received TLS cert status response, error parsing response"); |
| 1137 | else |
| 1138 | DEBUG(D_tls) debug_printf(" error parsing response\n"); |
| 1139 | OCSP_RESPONSE_free(rsp); |
| 1140 | return 0; |
| 1141 | } |
| 1142 | |
| 1143 | /* We'd check the nonce here if we'd put one in the request. */ |
| 1144 | /* However that would defeat cacheability on the server so we don't. */ |
| 1145 | |
| 1146 | /* This section of code reworked from OpenSSL apps source; |
| 1147 | The OpenSSL Project retains copyright: |
| 1148 | Copyright (c) 1999 The OpenSSL Project. All rights reserved. |
| 1149 | */ |
| 1150 | { |
| 1151 | BIO * bp = NULL; |
| 1152 | int status, reason; |
| 1153 | ASN1_GENERALIZEDTIME *rev, *thisupd, *nextupd; |
| 1154 | |
| 1155 | DEBUG(D_tls) bp = BIO_new_fp(stderr, BIO_NOCLOSE); |
| 1156 | |
| 1157 | /*OCSP_RESPONSE_print(bp, rsp, 0); extreme debug: stapling content */ |
| 1158 | |
| 1159 | /* Use the chain that verified the server cert to verify the stapled info */ |
| 1160 | /* DEBUG(D_tls) x509_store_dump_cert_s_names(cbinfo->u_ocsp.client.verify_store); */ |
| 1161 | |
| 1162 | if ((i = OCSP_basic_verify(bs, NULL, |
| 1163 | cbinfo->u_ocsp.client.verify_store, 0)) <= 0) |
| 1164 | { |
| 1165 | tls_out.ocsp = OCSP_FAILED; |
| 1166 | if (log_extra_selector & LX_tls_cipher) |
| 1167 | log_write(0, LOG_MAIN, "Received TLS cert status response, itself unverifiable"); |
| 1168 | BIO_printf(bp, "OCSP response verify failure\n"); |
| 1169 | ERR_print_errors(bp); |
| 1170 | i = cbinfo->u_ocsp.client.verify_required ? 0 : 1; |
| 1171 | goto out; |
| 1172 | } |
| 1173 | |
| 1174 | BIO_printf(bp, "OCSP response well-formed and signed OK\n"); |
| 1175 | |
| 1176 | { |
| 1177 | STACK_OF(OCSP_SINGLERESP) * sresp = bs->tbsResponseData->responses; |
| 1178 | OCSP_SINGLERESP * single; |
| 1179 | |
| 1180 | if (sk_OCSP_SINGLERESP_num(sresp) != 1) |
| 1181 | { |
| 1182 | tls_out.ocsp = OCSP_FAILED; |
| 1183 | log_write(0, LOG_MAIN, "OCSP stapling " |
| 1184 | "with multiple responses not handled"); |
| 1185 | i = cbinfo->u_ocsp.client.verify_required ? 0 : 1; |
| 1186 | goto out; |
| 1187 | } |
| 1188 | single = OCSP_resp_get0(bs, 0); |
| 1189 | status = OCSP_single_get0_status(single, &reason, &rev, |
| 1190 | &thisupd, &nextupd); |
| 1191 | } |
| 1192 | |
| 1193 | DEBUG(D_tls) time_print(bp, "This OCSP Update", thisupd); |
| 1194 | DEBUG(D_tls) if(nextupd) time_print(bp, "Next OCSP Update", nextupd); |
| 1195 | if (!OCSP_check_validity(thisupd, nextupd, |
| 1196 | EXIM_OCSP_SKEW_SECONDS, EXIM_OCSP_MAX_AGE)) |
| 1197 | { |
| 1198 | tls_out.ocsp = OCSP_FAILED; |
| 1199 | DEBUG(D_tls) ERR_print_errors(bp); |
| 1200 | log_write(0, LOG_MAIN, "Server OSCP dates invalid"); |
| 1201 | i = cbinfo->u_ocsp.client.verify_required ? 0 : 1; |
| 1202 | } |
| 1203 | else |
| 1204 | { |
| 1205 | DEBUG(D_tls) BIO_printf(bp, "Certificate status: %s\n", |
| 1206 | OCSP_cert_status_str(status)); |
| 1207 | switch(status) |
| 1208 | { |
| 1209 | case V_OCSP_CERTSTATUS_GOOD: |
| 1210 | tls_out.ocsp = OCSP_VFIED; |
| 1211 | i = 1; |
| 1212 | break; |
| 1213 | case V_OCSP_CERTSTATUS_REVOKED: |
| 1214 | tls_out.ocsp = OCSP_FAILED; |
| 1215 | log_write(0, LOG_MAIN, "Server certificate revoked%s%s", |
| 1216 | reason != -1 ? "; reason: " : "", |
| 1217 | reason != -1 ? OCSP_crl_reason_str(reason) : ""); |
| 1218 | DEBUG(D_tls) time_print(bp, "Revocation Time", rev); |
| 1219 | i = cbinfo->u_ocsp.client.verify_required ? 0 : 1; |
| 1220 | break; |
| 1221 | default: |
| 1222 | tls_out.ocsp = OCSP_FAILED; |
| 1223 | log_write(0, LOG_MAIN, |
| 1224 | "Server certificate status unknown, in OCSP stapling"); |
| 1225 | i = cbinfo->u_ocsp.client.verify_required ? 0 : 1; |
| 1226 | break; |
| 1227 | } |
| 1228 | } |
| 1229 | out: |
| 1230 | BIO_free(bp); |
| 1231 | } |
| 1232 | |
| 1233 | OCSP_RESPONSE_free(rsp); |
| 1234 | return i; |
| 1235 | } |
| 1236 | #endif /*!DISABLE_OCSP*/ |
| 1237 | |
| 1238 | |
| 1239 | /************************************************* |
| 1240 | * Initialize for TLS * |
| 1241 | *************************************************/ |
| 1242 | |
| 1243 | /* Called from both server and client code, to do preliminary initialization |
| 1244 | of the library. We allocate and return a context structure. |
| 1245 | |
| 1246 | Arguments: |
| 1247 | ctxp returned SSL context |
| 1248 | host connected host, if client; NULL if server |
| 1249 | dhparam DH parameter file |
| 1250 | certificate certificate file |
| 1251 | privatekey private key |
| 1252 | ocsp_file file of stapling info (server); flag for require ocsp (client) |
| 1253 | addr address if client; NULL if server (for some randomness) |
| 1254 | cbp place to put allocated callback context |
| 1255 | |
| 1256 | Returns: OK/DEFER/FAIL |
| 1257 | */ |
| 1258 | |
| 1259 | static int |
| 1260 | tls_init(SSL_CTX **ctxp, host_item *host, uschar *dhparam, uschar *certificate, |
| 1261 | uschar *privatekey, |
| 1262 | #ifndef DISABLE_OCSP |
| 1263 | uschar *ocsp_file, |
| 1264 | #endif |
| 1265 | address_item *addr, tls_ext_ctx_cb ** cbp) |
| 1266 | { |
| 1267 | long init_options; |
| 1268 | int rc; |
| 1269 | BOOL okay; |
| 1270 | tls_ext_ctx_cb * cbinfo; |
| 1271 | |
| 1272 | cbinfo = store_malloc(sizeof(tls_ext_ctx_cb)); |
| 1273 | cbinfo->certificate = certificate; |
| 1274 | cbinfo->privatekey = privatekey; |
| 1275 | #ifndef DISABLE_OCSP |
| 1276 | if ((cbinfo->is_server = host==NULL)) |
| 1277 | { |
| 1278 | cbinfo->u_ocsp.server.file = ocsp_file; |
| 1279 | cbinfo->u_ocsp.server.file_expanded = NULL; |
| 1280 | cbinfo->u_ocsp.server.response = NULL; |
| 1281 | } |
| 1282 | else |
| 1283 | cbinfo->u_ocsp.client.verify_store = NULL; |
| 1284 | #endif |
| 1285 | cbinfo->dhparam = dhparam; |
| 1286 | cbinfo->server_cipher_list = NULL; |
| 1287 | cbinfo->host = host; |
| 1288 | #ifdef EXPERIMENTAL_EVENT |
| 1289 | cbinfo->event_action = NULL; |
| 1290 | #endif |
| 1291 | |
| 1292 | SSL_load_error_strings(); /* basic set up */ |
| 1293 | OpenSSL_add_ssl_algorithms(); |
| 1294 | |
| 1295 | #if (OPENSSL_VERSION_NUMBER >= 0x0090800fL) && !defined(OPENSSL_NO_SHA256) |
| 1296 | /* SHA256 is becoming ever more popular. This makes sure it gets added to the |
| 1297 | list of available digests. */ |
| 1298 | EVP_add_digest(EVP_sha256()); |
| 1299 | #endif |
| 1300 | |
| 1301 | /* Create a context. |
| 1302 | The OpenSSL docs in 1.0.1b have not been updated to clarify TLS variant |
| 1303 | negotiation in the different methods; as far as I can tell, the only |
| 1304 | *_{server,client}_method which allows negotiation is SSLv23, which exists even |
| 1305 | when OpenSSL is built without SSLv2 support. |
| 1306 | By disabling with openssl_options, we can let admins re-enable with the |
| 1307 | existing knob. */ |
| 1308 | |
| 1309 | *ctxp = SSL_CTX_new((host == NULL)? |
| 1310 | SSLv23_server_method() : SSLv23_client_method()); |
| 1311 | |
| 1312 | if (*ctxp == NULL) return tls_error(US"SSL_CTX_new", host, NULL); |
| 1313 | |
| 1314 | /* It turns out that we need to seed the random number generator this early in |
| 1315 | order to get the full complement of ciphers to work. It took me roughly a day |
| 1316 | of work to discover this by experiment. |
| 1317 | |
| 1318 | On systems that have /dev/urandom, SSL may automatically seed itself from |
| 1319 | there. Otherwise, we have to make something up as best we can. Double check |
| 1320 | afterwards. */ |
| 1321 | |
| 1322 | if (!RAND_status()) |
| 1323 | { |
| 1324 | randstuff r; |
| 1325 | gettimeofday(&r.tv, NULL); |
| 1326 | r.p = getpid(); |
| 1327 | |
| 1328 | RAND_seed((uschar *)(&r), sizeof(r)); |
| 1329 | RAND_seed((uschar *)big_buffer, big_buffer_size); |
| 1330 | if (addr != NULL) RAND_seed((uschar *)addr, sizeof(addr)); |
| 1331 | |
| 1332 | if (!RAND_status()) |
| 1333 | return tls_error(US"RAND_status", host, |
| 1334 | US"unable to seed random number generator"); |
| 1335 | } |
| 1336 | |
| 1337 | /* Set up the information callback, which outputs if debugging is at a suitable |
| 1338 | level. */ |
| 1339 | |
| 1340 | DEBUG(D_tls) SSL_CTX_set_info_callback(*ctxp, (void (*)())info_callback); |
| 1341 | |
| 1342 | /* Automatically re-try reads/writes after renegotiation. */ |
| 1343 | (void) SSL_CTX_set_mode(*ctxp, SSL_MODE_AUTO_RETRY); |
| 1344 | |
| 1345 | /* Apply administrator-supplied work-arounds. |
| 1346 | Historically we applied just one requested option, |
| 1347 | SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS, but when bug 994 requested a second, we |
| 1348 | moved to an administrator-controlled list of options to specify and |
| 1349 | grandfathered in the first one as the default value for "openssl_options". |
| 1350 | |
| 1351 | No OpenSSL version number checks: the options we accept depend upon the |
| 1352 | availability of the option value macros from OpenSSL. */ |
| 1353 | |
| 1354 | okay = tls_openssl_options_parse(openssl_options, &init_options); |
| 1355 | if (!okay) |
| 1356 | return tls_error(US"openssl_options parsing failed", host, NULL); |
| 1357 | |
| 1358 | if (init_options) |
| 1359 | { |
| 1360 | DEBUG(D_tls) debug_printf("setting SSL CTX options: %#lx\n", init_options); |
| 1361 | if (!(SSL_CTX_set_options(*ctxp, init_options))) |
| 1362 | return tls_error(string_sprintf( |
| 1363 | "SSL_CTX_set_option(%#lx)", init_options), host, NULL); |
| 1364 | } |
| 1365 | else |
| 1366 | DEBUG(D_tls) debug_printf("no SSL CTX options to set\n"); |
| 1367 | |
| 1368 | /* Initialize with DH parameters if supplied */ |
| 1369 | /* Initialize ECDH temp key parameter selection */ |
| 1370 | |
| 1371 | if ( !init_dh(*ctxp, dhparam, host) |
| 1372 | || !init_ecdh(*ctxp, host) |
| 1373 | ) |
| 1374 | return DEFER; |
| 1375 | |
| 1376 | /* Set up certificate and key (and perhaps OCSP info) */ |
| 1377 | |
| 1378 | rc = tls_expand_session_files(*ctxp, cbinfo); |
| 1379 | if (rc != OK) return rc; |
| 1380 | |
| 1381 | /* If we need to handle SNI, do so */ |
| 1382 | #ifdef EXIM_HAVE_OPENSSL_TLSEXT |
| 1383 | if (host == NULL) /* server */ |
| 1384 | { |
| 1385 | # ifndef DISABLE_OCSP |
| 1386 | /* We check u_ocsp.server.file, not server.response, because we care about if |
| 1387 | the option exists, not what the current expansion might be, as SNI might |
| 1388 | change the certificate and OCSP file in use between now and the time the |
| 1389 | callback is invoked. */ |
| 1390 | if (cbinfo->u_ocsp.server.file) |
| 1391 | { |
| 1392 | SSL_CTX_set_tlsext_status_cb(server_ctx, tls_server_stapling_cb); |
| 1393 | SSL_CTX_set_tlsext_status_arg(server_ctx, cbinfo); |
| 1394 | } |
| 1395 | # endif |
| 1396 | /* We always do this, so that $tls_sni is available even if not used in |
| 1397 | tls_certificate */ |
| 1398 | SSL_CTX_set_tlsext_servername_callback(*ctxp, tls_servername_cb); |
| 1399 | SSL_CTX_set_tlsext_servername_arg(*ctxp, cbinfo); |
| 1400 | } |
| 1401 | # ifndef DISABLE_OCSP |
| 1402 | else /* client */ |
| 1403 | if(ocsp_file) /* wanting stapling */ |
| 1404 | { |
| 1405 | if (!(cbinfo->u_ocsp.client.verify_store = X509_STORE_new())) |
| 1406 | { |
| 1407 | DEBUG(D_tls) debug_printf("failed to create store for stapling verify\n"); |
| 1408 | return FAIL; |
| 1409 | } |
| 1410 | SSL_CTX_set_tlsext_status_cb(*ctxp, tls_client_stapling_cb); |
| 1411 | SSL_CTX_set_tlsext_status_arg(*ctxp, cbinfo); |
| 1412 | } |
| 1413 | # endif |
| 1414 | #endif |
| 1415 | |
| 1416 | cbinfo->verify_cert_hostnames = NULL; |
| 1417 | |
| 1418 | /* Set up the RSA callback */ |
| 1419 | |
| 1420 | SSL_CTX_set_tmp_rsa_callback(*ctxp, rsa_callback); |
| 1421 | |
| 1422 | /* Finally, set the timeout, and we are done */ |
| 1423 | |
| 1424 | SSL_CTX_set_timeout(*ctxp, ssl_session_timeout); |
| 1425 | DEBUG(D_tls) debug_printf("Initialized TLS\n"); |
| 1426 | |
| 1427 | *cbp = cbinfo; |
| 1428 | |
| 1429 | return OK; |
| 1430 | } |
| 1431 | |
| 1432 | |
| 1433 | |
| 1434 | |
| 1435 | /************************************************* |
| 1436 | * Get name of cipher in use * |
| 1437 | *************************************************/ |
| 1438 | |
| 1439 | /* |
| 1440 | Argument: pointer to an SSL structure for the connection |
| 1441 | buffer to use for answer |
| 1442 | size of buffer |
| 1443 | pointer to number of bits for cipher |
| 1444 | Returns: nothing |
| 1445 | */ |
| 1446 | |
| 1447 | static void |
| 1448 | construct_cipher_name(SSL *ssl, uschar *cipherbuf, int bsize, int *bits) |
| 1449 | { |
| 1450 | /* With OpenSSL 1.0.0a, this needs to be const but the documentation doesn't |
| 1451 | yet reflect that. It should be a safe change anyway, even 0.9.8 versions have |
| 1452 | the accessor functions use const in the prototype. */ |
| 1453 | const SSL_CIPHER *c; |
| 1454 | const uschar *ver; |
| 1455 | |
| 1456 | ver = (const uschar *)SSL_get_version(ssl); |
| 1457 | |
| 1458 | c = (const SSL_CIPHER *) SSL_get_current_cipher(ssl); |
| 1459 | SSL_CIPHER_get_bits(c, bits); |
| 1460 | |
| 1461 | string_format(cipherbuf, bsize, "%s:%s:%u", ver, |
| 1462 | SSL_CIPHER_get_name(c), *bits); |
| 1463 | |
| 1464 | DEBUG(D_tls) debug_printf("Cipher: %s\n", cipherbuf); |
| 1465 | } |
| 1466 | |
| 1467 | |
| 1468 | static void |
| 1469 | peer_cert(SSL * ssl, tls_support * tlsp, uschar * peerdn, unsigned bsize) |
| 1470 | { |
| 1471 | /*XXX we might consider a list-of-certs variable for the cert chain. |
| 1472 | SSL_get_peer_cert_chain(SSL*). We'd need a new variable type and support |
| 1473 | in list-handling functions, also consider the difference between the entire |
| 1474 | chain and the elements sent by the peer. */ |
| 1475 | |
| 1476 | /* Will have already noted peercert on a verify fail; possibly not the leaf */ |
| 1477 | if (!tlsp->peercert) |
| 1478 | tlsp->peercert = SSL_get_peer_certificate(ssl); |
| 1479 | /* Beware anonymous ciphers which lead to server_cert being NULL */ |
| 1480 | if (tlsp->peercert) |
| 1481 | { |
| 1482 | X509_NAME_oneline(X509_get_subject_name(tlsp->peercert), CS peerdn, bsize); |
| 1483 | peerdn[bsize-1] = '\0'; |
| 1484 | tlsp->peerdn = peerdn; /*XXX a static buffer... */ |
| 1485 | } |
| 1486 | else |
| 1487 | tlsp->peerdn = NULL; |
| 1488 | } |
| 1489 | |
| 1490 | |
| 1491 | |
| 1492 | |
| 1493 | |
| 1494 | /************************************************* |
| 1495 | * Set up for verifying certificates * |
| 1496 | *************************************************/ |
| 1497 | |
| 1498 | /* Called by both client and server startup |
| 1499 | |
| 1500 | Arguments: |
| 1501 | sctx SSL_CTX* to initialise |
| 1502 | certs certs file or NULL |
| 1503 | crl CRL file or NULL |
| 1504 | host NULL in a server; the remote host in a client |
| 1505 | optional TRUE if called from a server for a host in tls_try_verify_hosts; |
| 1506 | otherwise passed as FALSE |
| 1507 | cert_vfy_cb Callback function for certificate verification |
| 1508 | |
| 1509 | Returns: OK/DEFER/FAIL |
| 1510 | */ |
| 1511 | |
| 1512 | static int |
| 1513 | setup_certs(SSL_CTX *sctx, uschar *certs, uschar *crl, host_item *host, BOOL optional, |
| 1514 | int (*cert_vfy_cb)(int, X509_STORE_CTX *) ) |
| 1515 | { |
| 1516 | uschar *expcerts, *expcrl; |
| 1517 | |
| 1518 | if (!expand_check(certs, US"tls_verify_certificates", &expcerts)) |
| 1519 | return DEFER; |
| 1520 | |
| 1521 | if (expcerts != NULL && *expcerts != '\0') |
| 1522 | { |
| 1523 | if (Ustrcmp(expcerts, "system") == 0) |
| 1524 | { |
| 1525 | /* Tell the library to use its compiled-in location for the system default |
| 1526 | CA bundle, only */ |
| 1527 | |
| 1528 | if (!SSL_CTX_set_default_verify_paths(sctx)) |
| 1529 | return tls_error(US"SSL_CTX_set_default_verify_paths", host, NULL); |
| 1530 | } |
| 1531 | else |
| 1532 | { |
| 1533 | struct stat statbuf; |
| 1534 | |
| 1535 | /* Tell the library to use its compiled-in location for the system default |
| 1536 | CA bundle. Those given by the exim config are additional to these */ |
| 1537 | |
| 1538 | if (!SSL_CTX_set_default_verify_paths(sctx)) |
| 1539 | return tls_error(US"SSL_CTX_set_default_verify_paths", host, NULL); |
| 1540 | |
| 1541 | if (Ustat(expcerts, &statbuf) < 0) |
| 1542 | { |
| 1543 | log_write(0, LOG_MAIN|LOG_PANIC, |
| 1544 | "failed to stat %s for certificates", expcerts); |
| 1545 | return DEFER; |
| 1546 | } |
| 1547 | else |
| 1548 | { |
| 1549 | uschar *file, *dir; |
| 1550 | if ((statbuf.st_mode & S_IFMT) == S_IFDIR) |
| 1551 | { file = NULL; dir = expcerts; } |
| 1552 | else |
| 1553 | { file = expcerts; dir = NULL; } |
| 1554 | |
| 1555 | /* If a certificate file is empty, the next function fails with an |
| 1556 | unhelpful error message. If we skip it, we get the correct behaviour (no |
| 1557 | certificates are recognized, but the error message is still misleading (it |
| 1558 | says no certificate was supplied.) But this is better. */ |
| 1559 | |
| 1560 | if ((file == NULL || statbuf.st_size > 0) && |
| 1561 | !SSL_CTX_load_verify_locations(sctx, CS file, CS dir)) |
| 1562 | return tls_error(US"SSL_CTX_load_verify_locations", host, NULL); |
| 1563 | |
| 1564 | /* Load the list of CAs for which we will accept certs, for sending |
| 1565 | to the client. This is only for the one-file tls_verify_certificates |
| 1566 | variant. |
| 1567 | If a list isn't loaded into the server, but |
| 1568 | some verify locations are set, the server end appears to make |
| 1569 | a wildcard reqest for client certs. |
| 1570 | Meanwhile, the client library as deafult behaviour *ignores* the list |
| 1571 | we send over the wire - see man SSL_CTX_set_client_cert_cb. |
| 1572 | Because of this, and that the dir variant is likely only used for |
| 1573 | the public-CA bundle (not for a private CA), not worth fixing. |
| 1574 | */ |
| 1575 | if (file != NULL) |
| 1576 | { |
| 1577 | STACK_OF(X509_NAME) * names = SSL_load_client_CA_file(CS file); |
| 1578 | DEBUG(D_tls) debug_printf("Added %d certificate authorities.\n", |
| 1579 | sk_X509_NAME_num(names)); |
| 1580 | SSL_CTX_set_client_CA_list(sctx, names); |
| 1581 | } |
| 1582 | } |
| 1583 | } |
| 1584 | |
| 1585 | /* Handle a certificate revocation list. */ |
| 1586 | |
| 1587 | #if OPENSSL_VERSION_NUMBER > 0x00907000L |
| 1588 | |
| 1589 | /* This bit of code is now the version supplied by Lars Mainka. (I have |
| 1590 | * merely reformatted it into the Exim code style.) |
| 1591 | |
| 1592 | * "From here I changed the code to add support for multiple crl's |
| 1593 | * in pem format in one file or to support hashed directory entries in |
| 1594 | * pem format instead of a file. This method now uses the library function |
| 1595 | * X509_STORE_load_locations to add the CRL location to the SSL context. |
| 1596 | * OpenSSL will then handle the verify against CA certs and CRLs by |
| 1597 | * itself in the verify callback." */ |
| 1598 | |
| 1599 | if (!expand_check(crl, US"tls_crl", &expcrl)) return DEFER; |
| 1600 | if (expcrl != NULL && *expcrl != 0) |
| 1601 | { |
| 1602 | struct stat statbufcrl; |
| 1603 | if (Ustat(expcrl, &statbufcrl) < 0) |
| 1604 | { |
| 1605 | log_write(0, LOG_MAIN|LOG_PANIC, |
| 1606 | "failed to stat %s for certificates revocation lists", expcrl); |
| 1607 | return DEFER; |
| 1608 | } |
| 1609 | else |
| 1610 | { |
| 1611 | /* is it a file or directory? */ |
| 1612 | uschar *file, *dir; |
| 1613 | X509_STORE *cvstore = SSL_CTX_get_cert_store(sctx); |
| 1614 | if ((statbufcrl.st_mode & S_IFMT) == S_IFDIR) |
| 1615 | { |
| 1616 | file = NULL; |
| 1617 | dir = expcrl; |
| 1618 | DEBUG(D_tls) debug_printf("SSL CRL value is a directory %s\n", dir); |
| 1619 | } |
| 1620 | else |
| 1621 | { |
| 1622 | file = expcrl; |
| 1623 | dir = NULL; |
| 1624 | DEBUG(D_tls) debug_printf("SSL CRL value is a file %s\n", file); |
| 1625 | } |
| 1626 | if (X509_STORE_load_locations(cvstore, CS file, CS dir) == 0) |
| 1627 | return tls_error(US"X509_STORE_load_locations", host, NULL); |
| 1628 | |
| 1629 | /* setting the flags to check against the complete crl chain */ |
| 1630 | |
| 1631 | X509_STORE_set_flags(cvstore, |
| 1632 | X509_V_FLAG_CRL_CHECK|X509_V_FLAG_CRL_CHECK_ALL); |
| 1633 | } |
| 1634 | } |
| 1635 | |
| 1636 | #endif /* OPENSSL_VERSION_NUMBER > 0x00907000L */ |
| 1637 | |
| 1638 | /* If verification is optional, don't fail if no certificate */ |
| 1639 | |
| 1640 | SSL_CTX_set_verify(sctx, |
| 1641 | SSL_VERIFY_PEER | (optional? 0 : SSL_VERIFY_FAIL_IF_NO_PEER_CERT), |
| 1642 | cert_vfy_cb); |
| 1643 | } |
| 1644 | |
| 1645 | return OK; |
| 1646 | } |
| 1647 | |
| 1648 | |
| 1649 | |
| 1650 | /************************************************* |
| 1651 | * Start a TLS session in a server * |
| 1652 | *************************************************/ |
| 1653 | |
| 1654 | /* This is called when Exim is running as a server, after having received |
| 1655 | the STARTTLS command. It must respond to that command, and then negotiate |
| 1656 | a TLS session. |
| 1657 | |
| 1658 | Arguments: |
| 1659 | require_ciphers allowed ciphers |
| 1660 | |
| 1661 | Returns: OK on success |
| 1662 | DEFER for errors before the start of the negotiation |
| 1663 | FAIL for errors during the negotation; the server can't |
| 1664 | continue running. |
| 1665 | */ |
| 1666 | |
| 1667 | int |
| 1668 | tls_server_start(const uschar *require_ciphers) |
| 1669 | { |
| 1670 | int rc; |
| 1671 | uschar *expciphers; |
| 1672 | tls_ext_ctx_cb *cbinfo; |
| 1673 | static uschar peerdn[256]; |
| 1674 | static uschar cipherbuf[256]; |
| 1675 | |
| 1676 | /* Check for previous activation */ |
| 1677 | |
| 1678 | if (tls_in.active >= 0) |
| 1679 | { |
| 1680 | tls_error(US"STARTTLS received after TLS started", NULL, US""); |
| 1681 | smtp_printf("554 Already in TLS\r\n"); |
| 1682 | return FAIL; |
| 1683 | } |
| 1684 | |
| 1685 | /* Initialize the SSL library. If it fails, it will already have logged |
| 1686 | the error. */ |
| 1687 | |
| 1688 | rc = tls_init(&server_ctx, NULL, tls_dhparam, tls_certificate, tls_privatekey, |
| 1689 | #ifndef DISABLE_OCSP |
| 1690 | tls_ocsp_file, |
| 1691 | #endif |
| 1692 | NULL, &server_static_cbinfo); |
| 1693 | if (rc != OK) return rc; |
| 1694 | cbinfo = server_static_cbinfo; |
| 1695 | |
| 1696 | if (!expand_check(require_ciphers, US"tls_require_ciphers", &expciphers)) |
| 1697 | return FAIL; |
| 1698 | |
| 1699 | /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they |
| 1700 | were historically separated by underscores. So that I can use either form in my |
| 1701 | tests, and also for general convenience, we turn underscores into hyphens here. |
| 1702 | */ |
| 1703 | |
| 1704 | if (expciphers != NULL) |
| 1705 | { |
| 1706 | uschar *s = expciphers; |
| 1707 | while (*s != 0) { if (*s == '_') *s = '-'; s++; } |
| 1708 | DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers); |
| 1709 | if (!SSL_CTX_set_cipher_list(server_ctx, CS expciphers)) |
| 1710 | return tls_error(US"SSL_CTX_set_cipher_list", NULL, NULL); |
| 1711 | cbinfo->server_cipher_list = expciphers; |
| 1712 | } |
| 1713 | |
| 1714 | /* If this is a host for which certificate verification is mandatory or |
| 1715 | optional, set up appropriately. */ |
| 1716 | |
| 1717 | tls_in.certificate_verified = FALSE; |
| 1718 | #ifdef EXPERIMENTAL_DANE |
| 1719 | tls_in.dane_verified = FALSE; |
| 1720 | #endif |
| 1721 | server_verify_callback_called = FALSE; |
| 1722 | |
| 1723 | if (verify_check_host(&tls_verify_hosts) == OK) |
| 1724 | { |
| 1725 | rc = setup_certs(server_ctx, tls_verify_certificates, tls_crl, NULL, |
| 1726 | FALSE, verify_callback_server); |
| 1727 | if (rc != OK) return rc; |
| 1728 | server_verify_optional = FALSE; |
| 1729 | } |
| 1730 | else if (verify_check_host(&tls_try_verify_hosts) == OK) |
| 1731 | { |
| 1732 | rc = setup_certs(server_ctx, tls_verify_certificates, tls_crl, NULL, |
| 1733 | TRUE, verify_callback_server); |
| 1734 | if (rc != OK) return rc; |
| 1735 | server_verify_optional = TRUE; |
| 1736 | } |
| 1737 | |
| 1738 | /* Prepare for new connection */ |
| 1739 | |
| 1740 | if ((server_ssl = SSL_new(server_ctx)) == NULL) return tls_error(US"SSL_new", NULL, NULL); |
| 1741 | |
| 1742 | /* Warning: we used to SSL_clear(ssl) here, it was removed. |
| 1743 | * |
| 1744 | * With the SSL_clear(), we get strange interoperability bugs with |
| 1745 | * OpenSSL 1.0.1b and TLS1.1/1.2. It looks as though this may be a bug in |
| 1746 | * OpenSSL itself, as a clear should not lead to inability to follow protocols. |
| 1747 | * |
| 1748 | * The SSL_clear() call is to let an existing SSL* be reused, typically after |
| 1749 | * session shutdown. In this case, we have a brand new object and there's no |
| 1750 | * obvious reason to immediately clear it. I'm guessing that this was |
| 1751 | * originally added because of incomplete initialisation which the clear fixed, |
| 1752 | * in some historic release. |
| 1753 | */ |
| 1754 | |
| 1755 | /* Set context and tell client to go ahead, except in the case of TLS startup |
| 1756 | on connection, where outputting anything now upsets the clients and tends to |
| 1757 | make them disconnect. We need to have an explicit fflush() here, to force out |
| 1758 | the response. Other smtp_printf() calls do not need it, because in non-TLS |
| 1759 | mode, the fflush() happens when smtp_getc() is called. */ |
| 1760 | |
| 1761 | SSL_set_session_id_context(server_ssl, sid_ctx, Ustrlen(sid_ctx)); |
| 1762 | if (!tls_in.on_connect) |
| 1763 | { |
| 1764 | smtp_printf("220 TLS go ahead\r\n"); |
| 1765 | fflush(smtp_out); |
| 1766 | } |
| 1767 | |
| 1768 | /* Now negotiate the TLS session. We put our own timer on it, since it seems |
| 1769 | that the OpenSSL library doesn't. */ |
| 1770 | |
| 1771 | SSL_set_wfd(server_ssl, fileno(smtp_out)); |
| 1772 | SSL_set_rfd(server_ssl, fileno(smtp_in)); |
| 1773 | SSL_set_accept_state(server_ssl); |
| 1774 | |
| 1775 | DEBUG(D_tls) debug_printf("Calling SSL_accept\n"); |
| 1776 | |
| 1777 | sigalrm_seen = FALSE; |
| 1778 | if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout); |
| 1779 | rc = SSL_accept(server_ssl); |
| 1780 | alarm(0); |
| 1781 | |
| 1782 | if (rc <= 0) |
| 1783 | { |
| 1784 | tls_error(US"SSL_accept", NULL, sigalrm_seen ? US"timed out" : NULL); |
| 1785 | if (ERR_get_error() == 0) |
| 1786 | log_write(0, LOG_MAIN, |
| 1787 | "TLS client disconnected cleanly (rejected our certificate?)"); |
| 1788 | return FAIL; |
| 1789 | } |
| 1790 | |
| 1791 | DEBUG(D_tls) debug_printf("SSL_accept was successful\n"); |
| 1792 | |
| 1793 | /* TLS has been set up. Adjust the input functions to read via TLS, |
| 1794 | and initialize things. */ |
| 1795 | |
| 1796 | peer_cert(server_ssl, &tls_in, peerdn, sizeof(peerdn)); |
| 1797 | |
| 1798 | construct_cipher_name(server_ssl, cipherbuf, sizeof(cipherbuf), &tls_in.bits); |
| 1799 | tls_in.cipher = cipherbuf; |
| 1800 | |
| 1801 | DEBUG(D_tls) |
| 1802 | { |
| 1803 | uschar buf[2048]; |
| 1804 | if (SSL_get_shared_ciphers(server_ssl, CS buf, sizeof(buf)) != NULL) |
| 1805 | debug_printf("Shared ciphers: %s\n", buf); |
| 1806 | } |
| 1807 | |
| 1808 | /* Record the certificate we presented */ |
| 1809 | { |
| 1810 | X509 * crt = SSL_get_certificate(server_ssl); |
| 1811 | tls_in.ourcert = crt ? X509_dup(crt) : NULL; |
| 1812 | } |
| 1813 | |
| 1814 | /* Only used by the server-side tls (tls_in), including tls_getc. |
| 1815 | Client-side (tls_out) reads (seem to?) go via |
| 1816 | smtp_read_response()/ip_recv(). |
| 1817 | Hence no need to duplicate for _in and _out. |
| 1818 | */ |
| 1819 | ssl_xfer_buffer = store_malloc(ssl_xfer_buffer_size); |
| 1820 | ssl_xfer_buffer_lwm = ssl_xfer_buffer_hwm = 0; |
| 1821 | ssl_xfer_eof = ssl_xfer_error = 0; |
| 1822 | |
| 1823 | receive_getc = tls_getc; |
| 1824 | receive_ungetc = tls_ungetc; |
| 1825 | receive_feof = tls_feof; |
| 1826 | receive_ferror = tls_ferror; |
| 1827 | receive_smtp_buffered = tls_smtp_buffered; |
| 1828 | |
| 1829 | tls_in.active = fileno(smtp_out); |
| 1830 | return OK; |
| 1831 | } |
| 1832 | |
| 1833 | |
| 1834 | |
| 1835 | |
| 1836 | static int |
| 1837 | tls_client_basic_ctx_init(SSL_CTX * ctx, |
| 1838 | host_item * host, smtp_transport_options_block * ob, tls_ext_ctx_cb * cbinfo |
| 1839 | ) |
| 1840 | { |
| 1841 | int rc; |
| 1842 | /* stick to the old behaviour for compatibility if tls_verify_certificates is |
| 1843 | set but both tls_verify_hosts and tls_try_verify_hosts is not set. Check only |
| 1844 | the specified host patterns if one of them is defined */ |
| 1845 | |
| 1846 | if ( ( !ob->tls_verify_hosts |
| 1847 | && (!ob->tls_try_verify_hosts || !*ob->tls_try_verify_hosts) |
| 1848 | ) |
| 1849 | || (verify_check_given_host(&ob->tls_verify_hosts, host) == OK) |
| 1850 | ) |
| 1851 | client_verify_optional = FALSE; |
| 1852 | else if (verify_check_given_host(&ob->tls_try_verify_hosts, host) == OK) |
| 1853 | client_verify_optional = TRUE; |
| 1854 | else |
| 1855 | return OK; |
| 1856 | |
| 1857 | if ((rc = setup_certs(ctx, ob->tls_verify_certificates, |
| 1858 | ob->tls_crl, host, client_verify_optional, verify_callback_client)) != OK) |
| 1859 | return rc; |
| 1860 | |
| 1861 | if (verify_check_given_host(&ob->tls_verify_cert_hostnames, host) == OK) |
| 1862 | { |
| 1863 | cbinfo->verify_cert_hostnames = |
| 1864 | #ifdef EXPERIMENTAL_INTERNATIONAL |
| 1865 | string_domain_utf8_to_alabel(host->name, NULL); |
| 1866 | #else |
| 1867 | host->name; |
| 1868 | #endif |
| 1869 | DEBUG(D_tls) debug_printf("Cert hostname to check: \"%s\"\n", |
| 1870 | cbinfo->verify_cert_hostnames); |
| 1871 | } |
| 1872 | return OK; |
| 1873 | } |
| 1874 | |
| 1875 | |
| 1876 | #ifdef EXPERIMENTAL_DANE |
| 1877 | static int |
| 1878 | dane_tlsa_load(SSL * ssl, host_item * host, dns_answer * dnsa) |
| 1879 | { |
| 1880 | dns_record * rr; |
| 1881 | dns_scan dnss; |
| 1882 | const char * hostnames[2] = { CS host->name, NULL }; |
| 1883 | int found = 0; |
| 1884 | |
| 1885 | if (DANESSL_init(ssl, NULL, hostnames) != 1) |
| 1886 | return tls_error(US"hostnames load", host, NULL); |
| 1887 | |
| 1888 | for (rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS); |
| 1889 | rr; |
| 1890 | rr = dns_next_rr(dnsa, &dnss, RESET_NEXT) |
| 1891 | ) if (rr->type == T_TLSA) |
| 1892 | { |
| 1893 | uschar * p = rr->data; |
| 1894 | uint8_t usage, selector, mtype; |
| 1895 | const char * mdname; |
| 1896 | |
| 1897 | usage = *p++; |
| 1898 | |
| 1899 | /* Only DANE-TA(2) and DANE-EE(3) are supported */ |
| 1900 | if (usage != 2 && usage != 3) continue; |
| 1901 | |
| 1902 | selector = *p++; |
| 1903 | mtype = *p++; |
| 1904 | |
| 1905 | switch (mtype) |
| 1906 | { |
| 1907 | default: continue; /* Only match-types 0, 1, 2 are supported */ |
| 1908 | case 0: mdname = NULL; break; |
| 1909 | case 1: mdname = "sha256"; break; |
| 1910 | case 2: mdname = "sha512"; break; |
| 1911 | } |
| 1912 | |
| 1913 | found++; |
| 1914 | switch (DANESSL_add_tlsa(ssl, usage, selector, mdname, p, rr->size - 3)) |
| 1915 | { |
| 1916 | default: |
| 1917 | case 0: /* action not taken */ |
| 1918 | return tls_error(US"tlsa load", host, NULL); |
| 1919 | case 1: break; |
| 1920 | } |
| 1921 | |
| 1922 | tls_out.tlsa_usage |= 1<<usage; |
| 1923 | } |
| 1924 | |
| 1925 | if (found) |
| 1926 | return OK; |
| 1927 | |
| 1928 | log_write(0, LOG_MAIN, "DANE error: No usable TLSA records"); |
| 1929 | return DEFER; |
| 1930 | } |
| 1931 | #endif /*EXPERIMENTAL_DANE*/ |
| 1932 | |
| 1933 | |
| 1934 | |
| 1935 | /************************************************* |
| 1936 | * Start a TLS session in a client * |
| 1937 | *************************************************/ |
| 1938 | |
| 1939 | /* Called from the smtp transport after STARTTLS has been accepted. |
| 1940 | |
| 1941 | Argument: |
| 1942 | fd the fd of the connection |
| 1943 | host connected host (for messages) |
| 1944 | addr the first address |
| 1945 | tb transport (always smtp) |
| 1946 | tlsa_dnsa tlsa lookup, if DANE, else null |
| 1947 | |
| 1948 | Returns: OK on success |
| 1949 | FAIL otherwise - note that tls_error() will not give DEFER |
| 1950 | because this is not a server |
| 1951 | */ |
| 1952 | |
| 1953 | int |
| 1954 | tls_client_start(int fd, host_item *host, address_item *addr, |
| 1955 | transport_instance *tb |
| 1956 | #ifdef EXPERIMENTAL_DANE |
| 1957 | , dns_answer * tlsa_dnsa |
| 1958 | #endif |
| 1959 | ) |
| 1960 | { |
| 1961 | smtp_transport_options_block * ob = |
| 1962 | (smtp_transport_options_block *)tb->options_block; |
| 1963 | static uschar peerdn[256]; |
| 1964 | uschar * expciphers; |
| 1965 | int rc; |
| 1966 | static uschar cipherbuf[256]; |
| 1967 | |
| 1968 | #ifndef DISABLE_OCSP |
| 1969 | BOOL request_ocsp = FALSE; |
| 1970 | BOOL require_ocsp = FALSE; |
| 1971 | #endif |
| 1972 | |
| 1973 | #ifdef EXPERIMENTAL_DANE |
| 1974 | tls_out.tlsa_usage = 0; |
| 1975 | #endif |
| 1976 | |
| 1977 | #ifndef DISABLE_OCSP |
| 1978 | { |
| 1979 | # ifdef EXPERIMENTAL_DANE |
| 1980 | if ( tlsa_dnsa |
| 1981 | && ob->hosts_request_ocsp[0] == '*' |
| 1982 | && ob->hosts_request_ocsp[1] == '\0' |
| 1983 | ) |
| 1984 | { |
| 1985 | /* Unchanged from default. Use a safer one under DANE */ |
| 1986 | request_ocsp = TRUE; |
| 1987 | ob->hosts_request_ocsp = US"${if or { {= {0}{$tls_out_tlsa_usage}} " |
| 1988 | " {= {4}{$tls_out_tlsa_usage}} } " |
| 1989 | " {*}{}}"; |
| 1990 | } |
| 1991 | # endif |
| 1992 | |
| 1993 | if ((require_ocsp = |
| 1994 | verify_check_given_host(&ob->hosts_require_ocsp, host) == OK)) |
| 1995 | request_ocsp = TRUE; |
| 1996 | else |
| 1997 | # ifdef EXPERIMENTAL_DANE |
| 1998 | if (!request_ocsp) |
| 1999 | # endif |
| 2000 | request_ocsp = |
| 2001 | verify_check_given_host(&ob->hosts_request_ocsp, host) == OK; |
| 2002 | } |
| 2003 | #endif |
| 2004 | |
| 2005 | rc = tls_init(&client_ctx, host, NULL, |
| 2006 | ob->tls_certificate, ob->tls_privatekey, |
| 2007 | #ifndef DISABLE_OCSP |
| 2008 | (void *)(long)request_ocsp, |
| 2009 | #endif |
| 2010 | addr, &client_static_cbinfo); |
| 2011 | if (rc != OK) return rc; |
| 2012 | |
| 2013 | tls_out.certificate_verified = FALSE; |
| 2014 | client_verify_callback_called = FALSE; |
| 2015 | |
| 2016 | if (!expand_check(ob->tls_require_ciphers, US"tls_require_ciphers", |
| 2017 | &expciphers)) |
| 2018 | return FAIL; |
| 2019 | |
| 2020 | /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they |
| 2021 | are separated by underscores. So that I can use either form in my tests, and |
| 2022 | also for general convenience, we turn underscores into hyphens here. */ |
| 2023 | |
| 2024 | if (expciphers != NULL) |
| 2025 | { |
| 2026 | uschar *s = expciphers; |
| 2027 | while (*s != 0) { if (*s == '_') *s = '-'; s++; } |
| 2028 | DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers); |
| 2029 | if (!SSL_CTX_set_cipher_list(client_ctx, CS expciphers)) |
| 2030 | return tls_error(US"SSL_CTX_set_cipher_list", host, NULL); |
| 2031 | } |
| 2032 | |
| 2033 | #ifdef EXPERIMENTAL_DANE |
| 2034 | if (tlsa_dnsa) |
| 2035 | { |
| 2036 | SSL_CTX_set_verify(client_ctx, |
| 2037 | SSL_VERIFY_PEER | SSL_VERIFY_FAIL_IF_NO_PEER_CERT, |
| 2038 | verify_callback_client_dane); |
| 2039 | |
| 2040 | if (!DANESSL_library_init()) |
| 2041 | return tls_error(US"library init", host, NULL); |
| 2042 | if (DANESSL_CTX_init(client_ctx) <= 0) |
| 2043 | return tls_error(US"context init", host, NULL); |
| 2044 | } |
| 2045 | else |
| 2046 | |
| 2047 | #endif |
| 2048 | |
| 2049 | if ((rc = tls_client_basic_ctx_init(client_ctx, host, ob, client_static_cbinfo)) |
| 2050 | != OK) |
| 2051 | return rc; |
| 2052 | |
| 2053 | if ((client_ssl = SSL_new(client_ctx)) == NULL) |
| 2054 | return tls_error(US"SSL_new", host, NULL); |
| 2055 | SSL_set_session_id_context(client_ssl, sid_ctx, Ustrlen(sid_ctx)); |
| 2056 | SSL_set_fd(client_ssl, fd); |
| 2057 | SSL_set_connect_state(client_ssl); |
| 2058 | |
| 2059 | if (ob->tls_sni) |
| 2060 | { |
| 2061 | if (!expand_check(ob->tls_sni, US"tls_sni", &tls_out.sni)) |
| 2062 | return FAIL; |
| 2063 | if (tls_out.sni == NULL) |
| 2064 | { |
| 2065 | DEBUG(D_tls) debug_printf("Setting TLS SNI forced to fail, not sending\n"); |
| 2066 | } |
| 2067 | else if (!Ustrlen(tls_out.sni)) |
| 2068 | tls_out.sni = NULL; |
| 2069 | else |
| 2070 | { |
| 2071 | #ifdef EXIM_HAVE_OPENSSL_TLSEXT |
| 2072 | DEBUG(D_tls) debug_printf("Setting TLS SNI \"%s\"\n", tls_out.sni); |
| 2073 | SSL_set_tlsext_host_name(client_ssl, tls_out.sni); |
| 2074 | #else |
| 2075 | DEBUG(D_tls) |
| 2076 | debug_printf("OpenSSL at build-time lacked SNI support, ignoring \"%s\"\n", |
| 2077 | tls_out.sni); |
| 2078 | #endif |
| 2079 | } |
| 2080 | } |
| 2081 | |
| 2082 | #ifdef EXPERIMENTAL_DANE |
| 2083 | if (tlsa_dnsa) |
| 2084 | if ((rc = dane_tlsa_load(client_ssl, host, tlsa_dnsa)) != OK) |
| 2085 | return rc; |
| 2086 | #endif |
| 2087 | |
| 2088 | #ifndef DISABLE_OCSP |
| 2089 | /* Request certificate status at connection-time. If the server |
| 2090 | does OCSP stapling we will get the callback (set in tls_init()) */ |
| 2091 | # ifdef EXPERIMENTAL_DANE |
| 2092 | if (request_ocsp) |
| 2093 | { |
| 2094 | const uschar * s; |
| 2095 | if ( ((s = ob->hosts_require_ocsp) && Ustrstr(s, US"tls_out_tlsa_usage")) |
| 2096 | || ((s = ob->hosts_request_ocsp) && Ustrstr(s, US"tls_out_tlsa_usage")) |
| 2097 | ) |
| 2098 | { /* Re-eval now $tls_out_tlsa_usage is populated. If |
| 2099 | this means we avoid the OCSP request, we wasted the setup |
| 2100 | cost in tls_init(). */ |
| 2101 | require_ocsp = verify_check_given_host(&ob->hosts_require_ocsp, host) == OK; |
| 2102 | request_ocsp = require_ocsp |
| 2103 | || verify_check_given_host(&ob->hosts_request_ocsp, host) == OK; |
| 2104 | } |
| 2105 | } |
| 2106 | # endif |
| 2107 | |
| 2108 | if (request_ocsp) |
| 2109 | { |
| 2110 | SSL_set_tlsext_status_type(client_ssl, TLSEXT_STATUSTYPE_ocsp); |
| 2111 | client_static_cbinfo->u_ocsp.client.verify_required = require_ocsp; |
| 2112 | tls_out.ocsp = OCSP_NOT_RESP; |
| 2113 | } |
| 2114 | #endif |
| 2115 | |
| 2116 | #ifdef EXPERIMENTAL_EVENT |
| 2117 | client_static_cbinfo->event_action = tb->event_action; |
| 2118 | #endif |
| 2119 | |
| 2120 | /* There doesn't seem to be a built-in timeout on connection. */ |
| 2121 | |
| 2122 | DEBUG(D_tls) debug_printf("Calling SSL_connect\n"); |
| 2123 | sigalrm_seen = FALSE; |
| 2124 | alarm(ob->command_timeout); |
| 2125 | rc = SSL_connect(client_ssl); |
| 2126 | alarm(0); |
| 2127 | |
| 2128 | #ifdef EXPERIMENTAL_DANE |
| 2129 | if (tlsa_dnsa) |
| 2130 | DANESSL_cleanup(client_ssl); |
| 2131 | #endif |
| 2132 | |
| 2133 | if (rc <= 0) |
| 2134 | return tls_error(US"SSL_connect", host, sigalrm_seen ? US"timed out" : NULL); |
| 2135 | |
| 2136 | DEBUG(D_tls) debug_printf("SSL_connect succeeded\n"); |
| 2137 | |
| 2138 | peer_cert(client_ssl, &tls_out, peerdn, sizeof(peerdn)); |
| 2139 | |
| 2140 | construct_cipher_name(client_ssl, cipherbuf, sizeof(cipherbuf), &tls_out.bits); |
| 2141 | tls_out.cipher = cipherbuf; |
| 2142 | |
| 2143 | /* Record the certificate we presented */ |
| 2144 | { |
| 2145 | X509 * crt = SSL_get_certificate(client_ssl); |
| 2146 | tls_out.ourcert = crt ? X509_dup(crt) : NULL; |
| 2147 | } |
| 2148 | |
| 2149 | tls_out.active = fd; |
| 2150 | return OK; |
| 2151 | } |
| 2152 | |
| 2153 | |
| 2154 | |
| 2155 | |
| 2156 | |
| 2157 | /************************************************* |
| 2158 | * TLS version of getc * |
| 2159 | *************************************************/ |
| 2160 | |
| 2161 | /* This gets the next byte from the TLS input buffer. If the buffer is empty, |
| 2162 | it refills the buffer via the SSL reading function. |
| 2163 | |
| 2164 | Arguments: none |
| 2165 | Returns: the next character or EOF |
| 2166 | |
| 2167 | Only used by the server-side TLS. |
| 2168 | */ |
| 2169 | |
| 2170 | int |
| 2171 | tls_getc(void) |
| 2172 | { |
| 2173 | if (ssl_xfer_buffer_lwm >= ssl_xfer_buffer_hwm) |
| 2174 | { |
| 2175 | int error; |
| 2176 | int inbytes; |
| 2177 | |
| 2178 | DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", server_ssl, |
| 2179 | ssl_xfer_buffer, ssl_xfer_buffer_size); |
| 2180 | |
| 2181 | if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout); |
| 2182 | inbytes = SSL_read(server_ssl, CS ssl_xfer_buffer, ssl_xfer_buffer_size); |
| 2183 | error = SSL_get_error(server_ssl, inbytes); |
| 2184 | alarm(0); |
| 2185 | |
| 2186 | /* SSL_ERROR_ZERO_RETURN appears to mean that the SSL session has been |
| 2187 | closed down, not that the socket itself has been closed down. Revert to |
| 2188 | non-SSL handling. */ |
| 2189 | |
| 2190 | if (error == SSL_ERROR_ZERO_RETURN) |
| 2191 | { |
| 2192 | DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n"); |
| 2193 | |
| 2194 | receive_getc = smtp_getc; |
| 2195 | receive_ungetc = smtp_ungetc; |
| 2196 | receive_feof = smtp_feof; |
| 2197 | receive_ferror = smtp_ferror; |
| 2198 | receive_smtp_buffered = smtp_buffered; |
| 2199 | |
| 2200 | SSL_free(server_ssl); |
| 2201 | server_ssl = NULL; |
| 2202 | tls_in.active = -1; |
| 2203 | tls_in.bits = 0; |
| 2204 | tls_in.cipher = NULL; |
| 2205 | tls_in.peerdn = NULL; |
| 2206 | tls_in.sni = NULL; |
| 2207 | |
| 2208 | return smtp_getc(); |
| 2209 | } |
| 2210 | |
| 2211 | /* Handle genuine errors */ |
| 2212 | |
| 2213 | else if (error == SSL_ERROR_SSL) |
| 2214 | { |
| 2215 | ERR_error_string(ERR_get_error(), ssl_errstring); |
| 2216 | log_write(0, LOG_MAIN, "TLS error (SSL_read): %s", ssl_errstring); |
| 2217 | ssl_xfer_error = 1; |
| 2218 | return EOF; |
| 2219 | } |
| 2220 | |
| 2221 | else if (error != SSL_ERROR_NONE) |
| 2222 | { |
| 2223 | DEBUG(D_tls) debug_printf("Got SSL error %d\n", error); |
| 2224 | ssl_xfer_error = 1; |
| 2225 | return EOF; |
| 2226 | } |
| 2227 | |
| 2228 | #ifndef DISABLE_DKIM |
| 2229 | dkim_exim_verify_feed(ssl_xfer_buffer, inbytes); |
| 2230 | #endif |
| 2231 | ssl_xfer_buffer_hwm = inbytes; |
| 2232 | ssl_xfer_buffer_lwm = 0; |
| 2233 | } |
| 2234 | |
| 2235 | /* Something in the buffer; return next uschar */ |
| 2236 | |
| 2237 | return ssl_xfer_buffer[ssl_xfer_buffer_lwm++]; |
| 2238 | } |
| 2239 | |
| 2240 | |
| 2241 | |
| 2242 | /************************************************* |
| 2243 | * Read bytes from TLS channel * |
| 2244 | *************************************************/ |
| 2245 | |
| 2246 | /* |
| 2247 | Arguments: |
| 2248 | buff buffer of data |
| 2249 | len size of buffer |
| 2250 | |
| 2251 | Returns: the number of bytes read |
| 2252 | -1 after a failed read |
| 2253 | |
| 2254 | Only used by the client-side TLS. |
| 2255 | */ |
| 2256 | |
| 2257 | int |
| 2258 | tls_read(BOOL is_server, uschar *buff, size_t len) |
| 2259 | { |
| 2260 | SSL *ssl = is_server ? server_ssl : client_ssl; |
| 2261 | int inbytes; |
| 2262 | int error; |
| 2263 | |
| 2264 | DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", ssl, |
| 2265 | buff, (unsigned int)len); |
| 2266 | |
| 2267 | inbytes = SSL_read(ssl, CS buff, len); |
| 2268 | error = SSL_get_error(ssl, inbytes); |
| 2269 | |
| 2270 | if (error == SSL_ERROR_ZERO_RETURN) |
| 2271 | { |
| 2272 | DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n"); |
| 2273 | return -1; |
| 2274 | } |
| 2275 | else if (error != SSL_ERROR_NONE) |
| 2276 | { |
| 2277 | return -1; |
| 2278 | } |
| 2279 | |
| 2280 | return inbytes; |
| 2281 | } |
| 2282 | |
| 2283 | |
| 2284 | |
| 2285 | |
| 2286 | |
| 2287 | /************************************************* |
| 2288 | * Write bytes down TLS channel * |
| 2289 | *************************************************/ |
| 2290 | |
| 2291 | /* |
| 2292 | Arguments: |
| 2293 | is_server channel specifier |
| 2294 | buff buffer of data |
| 2295 | len number of bytes |
| 2296 | |
| 2297 | Returns: the number of bytes after a successful write, |
| 2298 | -1 after a failed write |
| 2299 | |
| 2300 | Used by both server-side and client-side TLS. |
| 2301 | */ |
| 2302 | |
| 2303 | int |
| 2304 | tls_write(BOOL is_server, const uschar *buff, size_t len) |
| 2305 | { |
| 2306 | int outbytes; |
| 2307 | int error; |
| 2308 | int left = len; |
| 2309 | SSL *ssl = is_server ? server_ssl : client_ssl; |
| 2310 | |
| 2311 | DEBUG(D_tls) debug_printf("tls_do_write(%p, %d)\n", buff, left); |
| 2312 | while (left > 0) |
| 2313 | { |
| 2314 | DEBUG(D_tls) debug_printf("SSL_write(SSL, %p, %d)\n", buff, left); |
| 2315 | outbytes = SSL_write(ssl, CS buff, left); |
| 2316 | error = SSL_get_error(ssl, outbytes); |
| 2317 | DEBUG(D_tls) debug_printf("outbytes=%d error=%d\n", outbytes, error); |
| 2318 | switch (error) |
| 2319 | { |
| 2320 | case SSL_ERROR_SSL: |
| 2321 | ERR_error_string(ERR_get_error(), ssl_errstring); |
| 2322 | log_write(0, LOG_MAIN, "TLS error (SSL_write): %s", ssl_errstring); |
| 2323 | return -1; |
| 2324 | |
| 2325 | case SSL_ERROR_NONE: |
| 2326 | left -= outbytes; |
| 2327 | buff += outbytes; |
| 2328 | break; |
| 2329 | |
| 2330 | case SSL_ERROR_ZERO_RETURN: |
| 2331 | log_write(0, LOG_MAIN, "SSL channel closed on write"); |
| 2332 | return -1; |
| 2333 | |
| 2334 | case SSL_ERROR_SYSCALL: |
| 2335 | log_write(0, LOG_MAIN, "SSL_write: (from %s) syscall: %s", |
| 2336 | sender_fullhost ? sender_fullhost : US"<unknown>", |
| 2337 | strerror(errno)); |
| 2338 | |
| 2339 | default: |
| 2340 | log_write(0, LOG_MAIN, "SSL_write error %d", error); |
| 2341 | return -1; |
| 2342 | } |
| 2343 | } |
| 2344 | return len; |
| 2345 | } |
| 2346 | |
| 2347 | |
| 2348 | |
| 2349 | /************************************************* |
| 2350 | * Close down a TLS session * |
| 2351 | *************************************************/ |
| 2352 | |
| 2353 | /* This is also called from within a delivery subprocess forked from the |
| 2354 | daemon, to shut down the TLS library, without actually doing a shutdown (which |
| 2355 | would tamper with the SSL session in the parent process). |
| 2356 | |
| 2357 | Arguments: TRUE if SSL_shutdown is to be called |
| 2358 | Returns: nothing |
| 2359 | |
| 2360 | Used by both server-side and client-side TLS. |
| 2361 | */ |
| 2362 | |
| 2363 | void |
| 2364 | tls_close(BOOL is_server, BOOL shutdown) |
| 2365 | { |
| 2366 | SSL **sslp = is_server ? &server_ssl : &client_ssl; |
| 2367 | int *fdp = is_server ? &tls_in.active : &tls_out.active; |
| 2368 | |
| 2369 | if (*fdp < 0) return; /* TLS was not active */ |
| 2370 | |
| 2371 | if (shutdown) |
| 2372 | { |
| 2373 | DEBUG(D_tls) debug_printf("tls_close(): shutting down SSL\n"); |
| 2374 | SSL_shutdown(*sslp); |
| 2375 | } |
| 2376 | |
| 2377 | SSL_free(*sslp); |
| 2378 | *sslp = NULL; |
| 2379 | |
| 2380 | *fdp = -1; |
| 2381 | } |
| 2382 | |
| 2383 | |
| 2384 | |
| 2385 | |
| 2386 | /************************************************* |
| 2387 | * Let tls_require_ciphers be checked at startup * |
| 2388 | *************************************************/ |
| 2389 | |
| 2390 | /* The tls_require_ciphers option, if set, must be something which the |
| 2391 | library can parse. |
| 2392 | |
| 2393 | Returns: NULL on success, or error message |
| 2394 | */ |
| 2395 | |
| 2396 | uschar * |
| 2397 | tls_validate_require_cipher(void) |
| 2398 | { |
| 2399 | SSL_CTX *ctx; |
| 2400 | uschar *s, *expciphers, *err; |
| 2401 | |
| 2402 | /* this duplicates from tls_init(), we need a better "init just global |
| 2403 | state, for no specific purpose" singleton function of our own */ |
| 2404 | |
| 2405 | SSL_load_error_strings(); |
| 2406 | OpenSSL_add_ssl_algorithms(); |
| 2407 | #if (OPENSSL_VERSION_NUMBER >= 0x0090800fL) && !defined(OPENSSL_NO_SHA256) |
| 2408 | /* SHA256 is becoming ever more popular. This makes sure it gets added to the |
| 2409 | list of available digests. */ |
| 2410 | EVP_add_digest(EVP_sha256()); |
| 2411 | #endif |
| 2412 | |
| 2413 | if (!(tls_require_ciphers && *tls_require_ciphers)) |
| 2414 | return NULL; |
| 2415 | |
| 2416 | if (!expand_check(tls_require_ciphers, US"tls_require_ciphers", &expciphers)) |
| 2417 | return US"failed to expand tls_require_ciphers"; |
| 2418 | |
| 2419 | if (!(expciphers && *expciphers)) |
| 2420 | return NULL; |
| 2421 | |
| 2422 | /* normalisation ripped from above */ |
| 2423 | s = expciphers; |
| 2424 | while (*s != 0) { if (*s == '_') *s = '-'; s++; } |
| 2425 | |
| 2426 | err = NULL; |
| 2427 | |
| 2428 | ctx = SSL_CTX_new(SSLv23_server_method()); |
| 2429 | if (!ctx) |
| 2430 | { |
| 2431 | ERR_error_string(ERR_get_error(), ssl_errstring); |
| 2432 | return string_sprintf("SSL_CTX_new() failed: %s", ssl_errstring); |
| 2433 | } |
| 2434 | |
| 2435 | DEBUG(D_tls) |
| 2436 | debug_printf("tls_require_ciphers expands to \"%s\"\n", expciphers); |
| 2437 | |
| 2438 | if (!SSL_CTX_set_cipher_list(ctx, CS expciphers)) |
| 2439 | { |
| 2440 | ERR_error_string(ERR_get_error(), ssl_errstring); |
| 2441 | err = string_sprintf("SSL_CTX_set_cipher_list(%s) failed", expciphers); |
| 2442 | } |
| 2443 | |
| 2444 | SSL_CTX_free(ctx); |
| 2445 | |
| 2446 | return err; |
| 2447 | } |
| 2448 | |
| 2449 | |
| 2450 | |
| 2451 | |
| 2452 | /************************************************* |
| 2453 | * Report the library versions. * |
| 2454 | *************************************************/ |
| 2455 | |
| 2456 | /* There have historically been some issues with binary compatibility in |
| 2457 | OpenSSL libraries; if Exim (like many other applications) is built against |
| 2458 | one version of OpenSSL but the run-time linker picks up another version, |
| 2459 | it can result in serious failures, including crashing with a SIGSEGV. So |
| 2460 | report the version found by the compiler and the run-time version. |
| 2461 | |
| 2462 | Note: some OS vendors backport security fixes without changing the version |
| 2463 | number/string, and the version date remains unchanged. The _build_ date |
| 2464 | will change, so we can more usefully assist with version diagnosis by also |
| 2465 | reporting the build date. |
| 2466 | |
| 2467 | Arguments: a FILE* to print the results to |
| 2468 | Returns: nothing |
| 2469 | */ |
| 2470 | |
| 2471 | void |
| 2472 | tls_version_report(FILE *f) |
| 2473 | { |
| 2474 | fprintf(f, "Library version: OpenSSL: Compile: %s\n" |
| 2475 | " Runtime: %s\n" |
| 2476 | " : %s\n", |
| 2477 | OPENSSL_VERSION_TEXT, |
| 2478 | SSLeay_version(SSLEAY_VERSION), |
| 2479 | SSLeay_version(SSLEAY_BUILT_ON)); |
| 2480 | /* third line is 38 characters for the %s and the line is 73 chars long; |
| 2481 | the OpenSSL output includes a "built on: " prefix already. */ |
| 2482 | } |
| 2483 | |
| 2484 | |
| 2485 | |
| 2486 | |
| 2487 | /************************************************* |
| 2488 | * Random number generation * |
| 2489 | *************************************************/ |
| 2490 | |
| 2491 | /* Pseudo-random number generation. The result is not expected to be |
| 2492 | cryptographically strong but not so weak that someone will shoot themselves |
| 2493 | in the foot using it as a nonce in input in some email header scheme or |
| 2494 | whatever weirdness they'll twist this into. The result should handle fork() |
| 2495 | and avoid repeating sequences. OpenSSL handles that for us. |
| 2496 | |
| 2497 | Arguments: |
| 2498 | max range maximum |
| 2499 | Returns a random number in range [0, max-1] |
| 2500 | */ |
| 2501 | |
| 2502 | int |
| 2503 | vaguely_random_number(int max) |
| 2504 | { |
| 2505 | unsigned int r; |
| 2506 | int i, needed_len; |
| 2507 | static pid_t pidlast = 0; |
| 2508 | pid_t pidnow; |
| 2509 | uschar *p; |
| 2510 | uschar smallbuf[sizeof(r)]; |
| 2511 | |
| 2512 | if (max <= 1) |
| 2513 | return 0; |
| 2514 | |
| 2515 | pidnow = getpid(); |
| 2516 | if (pidnow != pidlast) |
| 2517 | { |
| 2518 | /* Although OpenSSL documents that "OpenSSL makes sure that the PRNG state |
| 2519 | is unique for each thread", this doesn't apparently apply across processes, |
| 2520 | so our own warning from vaguely_random_number_fallback() applies here too. |
| 2521 | Fix per PostgreSQL. */ |
| 2522 | if (pidlast != 0) |
| 2523 | RAND_cleanup(); |
| 2524 | pidlast = pidnow; |
| 2525 | } |
| 2526 | |
| 2527 | /* OpenSSL auto-seeds from /dev/random, etc, but this a double-check. */ |
| 2528 | if (!RAND_status()) |
| 2529 | { |
| 2530 | randstuff r; |
| 2531 | gettimeofday(&r.tv, NULL); |
| 2532 | r.p = getpid(); |
| 2533 | |
| 2534 | RAND_seed((uschar *)(&r), sizeof(r)); |
| 2535 | } |
| 2536 | /* We're after pseudo-random, not random; if we still don't have enough data |
| 2537 | in the internal PRNG then our options are limited. We could sleep and hope |
| 2538 | for entropy to come along (prayer technique) but if the system is so depleted |
| 2539 | in the first place then something is likely to just keep taking it. Instead, |
| 2540 | we'll just take whatever little bit of pseudo-random we can still manage to |
| 2541 | get. */ |
| 2542 | |
| 2543 | needed_len = sizeof(r); |
| 2544 | /* Don't take 8 times more entropy than needed if int is 8 octets and we were |
| 2545 | asked for a number less than 10. */ |
| 2546 | for (r = max, i = 0; r; ++i) |
| 2547 | r >>= 1; |
| 2548 | i = (i + 7) / 8; |
| 2549 | if (i < needed_len) |
| 2550 | needed_len = i; |
| 2551 | |
| 2552 | /* We do not care if crypto-strong */ |
| 2553 | i = RAND_pseudo_bytes(smallbuf, needed_len); |
| 2554 | if (i < 0) |
| 2555 | { |
| 2556 | DEBUG(D_all) |
| 2557 | debug_printf("OpenSSL RAND_pseudo_bytes() not supported by RAND method, using fallback.\n"); |
| 2558 | return vaguely_random_number_fallback(max); |
| 2559 | } |
| 2560 | |
| 2561 | r = 0; |
| 2562 | for (p = smallbuf; needed_len; --needed_len, ++p) |
| 2563 | { |
| 2564 | r *= 256; |
| 2565 | r += *p; |
| 2566 | } |
| 2567 | |
| 2568 | /* We don't particularly care about weighted results; if someone wants |
| 2569 | smooth distribution and cares enough then they should submit a patch then. */ |
| 2570 | return r % max; |
| 2571 | } |
| 2572 | |
| 2573 | |
| 2574 | |
| 2575 | |
| 2576 | /************************************************* |
| 2577 | * OpenSSL option parse * |
| 2578 | *************************************************/ |
| 2579 | |
| 2580 | /* Parse one option for tls_openssl_options_parse below |
| 2581 | |
| 2582 | Arguments: |
| 2583 | name one option name |
| 2584 | value place to store a value for it |
| 2585 | Returns success or failure in parsing |
| 2586 | */ |
| 2587 | |
| 2588 | struct exim_openssl_option { |
| 2589 | uschar *name; |
| 2590 | long value; |
| 2591 | }; |
| 2592 | /* We could use a macro to expand, but we need the ifdef and not all the |
| 2593 | options document which version they were introduced in. Policylet: include |
| 2594 | all options unless explicitly for DTLS, let the administrator choose which |
| 2595 | to apply. |
| 2596 | |
| 2597 | This list is current as of: |
| 2598 | ==> 1.0.1b <== |
| 2599 | Plus SSL_OP_SAFARI_ECDHE_ECDSA_BUG from 2013-June patch/discussion on openssl-dev |
| 2600 | */ |
| 2601 | static struct exim_openssl_option exim_openssl_options[] = { |
| 2602 | /* KEEP SORTED ALPHABETICALLY! */ |
| 2603 | #ifdef SSL_OP_ALL |
| 2604 | { US"all", SSL_OP_ALL }, |
| 2605 | #endif |
| 2606 | #ifdef SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION |
| 2607 | { US"allow_unsafe_legacy_renegotiation", SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION }, |
| 2608 | #endif |
| 2609 | #ifdef SSL_OP_CIPHER_SERVER_PREFERENCE |
| 2610 | { US"cipher_server_preference", SSL_OP_CIPHER_SERVER_PREFERENCE }, |
| 2611 | #endif |
| 2612 | #ifdef SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS |
| 2613 | { US"dont_insert_empty_fragments", SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS }, |
| 2614 | #endif |
| 2615 | #ifdef SSL_OP_EPHEMERAL_RSA |
| 2616 | { US"ephemeral_rsa", SSL_OP_EPHEMERAL_RSA }, |
| 2617 | #endif |
| 2618 | #ifdef SSL_OP_LEGACY_SERVER_CONNECT |
| 2619 | { US"legacy_server_connect", SSL_OP_LEGACY_SERVER_CONNECT }, |
| 2620 | #endif |
| 2621 | #ifdef SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER |
| 2622 | { US"microsoft_big_sslv3_buffer", SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER }, |
| 2623 | #endif |
| 2624 | #ifdef SSL_OP_MICROSOFT_SESS_ID_BUG |
| 2625 | { US"microsoft_sess_id_bug", SSL_OP_MICROSOFT_SESS_ID_BUG }, |
| 2626 | #endif |
| 2627 | #ifdef SSL_OP_MSIE_SSLV2_RSA_PADDING |
| 2628 | { US"msie_sslv2_rsa_padding", SSL_OP_MSIE_SSLV2_RSA_PADDING }, |
| 2629 | #endif |
| 2630 | #ifdef SSL_OP_NETSCAPE_CHALLENGE_BUG |
| 2631 | { US"netscape_challenge_bug", SSL_OP_NETSCAPE_CHALLENGE_BUG }, |
| 2632 | #endif |
| 2633 | #ifdef SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG |
| 2634 | { US"netscape_reuse_cipher_change_bug", SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG }, |
| 2635 | #endif |
| 2636 | #ifdef SSL_OP_NO_COMPRESSION |
| 2637 | { US"no_compression", SSL_OP_NO_COMPRESSION }, |
| 2638 | #endif |
| 2639 | #ifdef SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION |
| 2640 | { US"no_session_resumption_on_renegotiation", SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION }, |
| 2641 | #endif |
| 2642 | #ifdef SSL_OP_NO_SSLv2 |
| 2643 | { US"no_sslv2", SSL_OP_NO_SSLv2 }, |
| 2644 | #endif |
| 2645 | #ifdef SSL_OP_NO_SSLv3 |
| 2646 | { US"no_sslv3", SSL_OP_NO_SSLv3 }, |
| 2647 | #endif |
| 2648 | #ifdef SSL_OP_NO_TICKET |
| 2649 | { US"no_ticket", SSL_OP_NO_TICKET }, |
| 2650 | #endif |
| 2651 | #ifdef SSL_OP_NO_TLSv1 |
| 2652 | { US"no_tlsv1", SSL_OP_NO_TLSv1 }, |
| 2653 | #endif |
| 2654 | #ifdef SSL_OP_NO_TLSv1_1 |
| 2655 | #if SSL_OP_NO_TLSv1_1 == 0x00000400L |
| 2656 | /* Error in chosen value in 1.0.1a; see first item in CHANGES for 1.0.1b */ |
| 2657 | #warning OpenSSL 1.0.1a uses a bad value for SSL_OP_NO_TLSv1_1, ignoring |
| 2658 | #else |
| 2659 | { US"no_tlsv1_1", SSL_OP_NO_TLSv1_1 }, |
| 2660 | #endif |
| 2661 | #endif |
| 2662 | #ifdef SSL_OP_NO_TLSv1_2 |
| 2663 | { US"no_tlsv1_2", SSL_OP_NO_TLSv1_2 }, |
| 2664 | #endif |
| 2665 | #ifdef SSL_OP_SAFARI_ECDHE_ECDSA_BUG |
| 2666 | { US"safari_ecdhe_ecdsa_bug", SSL_OP_SAFARI_ECDHE_ECDSA_BUG }, |
| 2667 | #endif |
| 2668 | #ifdef SSL_OP_SINGLE_DH_USE |
| 2669 | { US"single_dh_use", SSL_OP_SINGLE_DH_USE }, |
| 2670 | #endif |
| 2671 | #ifdef SSL_OP_SINGLE_ECDH_USE |
| 2672 | { US"single_ecdh_use", SSL_OP_SINGLE_ECDH_USE }, |
| 2673 | #endif |
| 2674 | #ifdef SSL_OP_SSLEAY_080_CLIENT_DH_BUG |
| 2675 | { US"ssleay_080_client_dh_bug", SSL_OP_SSLEAY_080_CLIENT_DH_BUG }, |
| 2676 | #endif |
| 2677 | #ifdef SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG |
| 2678 | { US"sslref2_reuse_cert_type_bug", SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG }, |
| 2679 | #endif |
| 2680 | #ifdef SSL_OP_TLS_BLOCK_PADDING_BUG |
| 2681 | { US"tls_block_padding_bug", SSL_OP_TLS_BLOCK_PADDING_BUG }, |
| 2682 | #endif |
| 2683 | #ifdef SSL_OP_TLS_D5_BUG |
| 2684 | { US"tls_d5_bug", SSL_OP_TLS_D5_BUG }, |
| 2685 | #endif |
| 2686 | #ifdef SSL_OP_TLS_ROLLBACK_BUG |
| 2687 | { US"tls_rollback_bug", SSL_OP_TLS_ROLLBACK_BUG }, |
| 2688 | #endif |
| 2689 | }; |
| 2690 | static int exim_openssl_options_size = |
| 2691 | sizeof(exim_openssl_options)/sizeof(struct exim_openssl_option); |
| 2692 | |
| 2693 | |
| 2694 | static BOOL |
| 2695 | tls_openssl_one_option_parse(uschar *name, long *value) |
| 2696 | { |
| 2697 | int first = 0; |
| 2698 | int last = exim_openssl_options_size; |
| 2699 | while (last > first) |
| 2700 | { |
| 2701 | int middle = (first + last)/2; |
| 2702 | int c = Ustrcmp(name, exim_openssl_options[middle].name); |
| 2703 | if (c == 0) |
| 2704 | { |
| 2705 | *value = exim_openssl_options[middle].value; |
| 2706 | return TRUE; |
| 2707 | } |
| 2708 | else if (c > 0) |
| 2709 | first = middle + 1; |
| 2710 | else |
| 2711 | last = middle; |
| 2712 | } |
| 2713 | return FALSE; |
| 2714 | } |
| 2715 | |
| 2716 | |
| 2717 | |
| 2718 | |
| 2719 | /************************************************* |
| 2720 | * OpenSSL option parsing logic * |
| 2721 | *************************************************/ |
| 2722 | |
| 2723 | /* OpenSSL has a number of compatibility options which an administrator might |
| 2724 | reasonably wish to set. Interpret a list similarly to decode_bits(), so that |
| 2725 | we look like log_selector. |
| 2726 | |
| 2727 | Arguments: |
| 2728 | option_spec the administrator-supplied string of options |
| 2729 | results ptr to long storage for the options bitmap |
| 2730 | Returns success or failure |
| 2731 | */ |
| 2732 | |
| 2733 | BOOL |
| 2734 | tls_openssl_options_parse(uschar *option_spec, long *results) |
| 2735 | { |
| 2736 | long result, item; |
| 2737 | uschar *s, *end; |
| 2738 | uschar keep_c; |
| 2739 | BOOL adding, item_parsed; |
| 2740 | |
| 2741 | result = 0L; |
| 2742 | /* Prior to 4.80 we or'd in SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS; removed |
| 2743 | * from default because it increases BEAST susceptibility. */ |
| 2744 | #ifdef SSL_OP_NO_SSLv2 |
| 2745 | result |= SSL_OP_NO_SSLv2; |
| 2746 | #endif |
| 2747 | |
| 2748 | if (option_spec == NULL) |
| 2749 | { |
| 2750 | *results = result; |
| 2751 | return TRUE; |
| 2752 | } |
| 2753 | |
| 2754 | for (s=option_spec; *s != '\0'; /**/) |
| 2755 | { |
| 2756 | while (isspace(*s)) ++s; |
| 2757 | if (*s == '\0') |
| 2758 | break; |
| 2759 | if (*s != '+' && *s != '-') |
| 2760 | { |
| 2761 | DEBUG(D_tls) debug_printf("malformed openssl option setting: " |
| 2762 | "+ or - expected but found \"%s\"\n", s); |
| 2763 | return FALSE; |
| 2764 | } |
| 2765 | adding = *s++ == '+'; |
| 2766 | for (end = s; (*end != '\0') && !isspace(*end); ++end) /**/ ; |
| 2767 | keep_c = *end; |
| 2768 | *end = '\0'; |
| 2769 | item_parsed = tls_openssl_one_option_parse(s, &item); |
| 2770 | if (!item_parsed) |
| 2771 | { |
| 2772 | DEBUG(D_tls) debug_printf("openssl option setting unrecognised: \"%s\"\n", s); |
| 2773 | return FALSE; |
| 2774 | } |
| 2775 | DEBUG(D_tls) debug_printf("openssl option, %s from %lx: %lx (%s)\n", |
| 2776 | adding ? "adding" : "removing", result, item, s); |
| 2777 | if (adding) |
| 2778 | result |= item; |
| 2779 | else |
| 2780 | result &= ~item; |
| 2781 | *end = keep_c; |
| 2782 | s = end; |
| 2783 | } |
| 2784 | |
| 2785 | *results = result; |
| 2786 | return TRUE; |
| 2787 | } |
| 2788 | |
| 2789 | /* vi: aw ai sw=2 |
| 2790 | */ |
| 2791 | /* End of tls-openssl.c */ |