| 1 | /************************************************* |
| 2 | * Exim - an Internet mail transport agent * |
| 3 | *************************************************/ |
| 4 | |
| 5 | /* Copyright (c) University of Cambridge 1995 - 2018 */ |
| 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 SUPPORT_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 | #if OPENSSL_VERSION_NUMBER >= 0x00908000L |
| 45 | # define EXIM_HAVE_RSA_GENKEY_EX |
| 46 | #endif |
| 47 | #if OPENSSL_VERSION_NUMBER >= 0x10100000L |
| 48 | # define EXIM_HAVE_OCSP_RESP_COUNT |
| 49 | #else |
| 50 | # define EXIM_HAVE_EPHEM_RSA_KEX |
| 51 | # define EXIM_HAVE_RAND_PSEUDO |
| 52 | #endif |
| 53 | #if (OPENSSL_VERSION_NUMBER >= 0x0090800fL) && !defined(OPENSSL_NO_SHA256) |
| 54 | # define EXIM_HAVE_SHA256 /*MMMM*/ |
| 55 | #endif |
| 56 | |
| 57 | /* |
| 58 | * X509_check_host provides sane certificate hostname checking, but was added |
| 59 | * to OpenSSL late, after other projects forked off the code-base. So in |
| 60 | * addition to guarding against the base version number, beware that LibreSSL |
| 61 | * does not (at this time) support this function. |
| 62 | * |
| 63 | * If LibreSSL gains a different API, perhaps via libtls, then we'll probably |
| 64 | * opt to disentangle and ask a LibreSSL user to provide glue for a third |
| 65 | * crypto provider for libtls instead of continuing to tie the OpenSSL glue |
| 66 | * into even twistier knots. If LibreSSL gains the same API, we can just |
| 67 | * change this guard and punt the issue for a while longer. |
| 68 | */ |
| 69 | #ifndef LIBRESSL_VERSION_NUMBER |
| 70 | # if OPENSSL_VERSION_NUMBER >= 0x010100000L |
| 71 | # define EXIM_HAVE_OPENSSL_CHECKHOST |
| 72 | # define EXIM_HAVE_OPENSSL_DH_BITS |
| 73 | # endif |
| 74 | # if OPENSSL_VERSION_NUMBER >= 0x010000000L \ |
| 75 | && (OPENSSL_VERSION_NUMBER & 0x0000ff000L) >= 0x000002000L |
| 76 | # define EXIM_HAVE_OPENSSL_CHECKHOST |
| 77 | # endif |
| 78 | #endif |
| 79 | |
| 80 | #if !defined(LIBRESSL_VERSION_NUMBER) \ |
| 81 | || LIBRESSL_VERSION_NUMBER >= 0x20010000L |
| 82 | # if !defined(OPENSSL_NO_ECDH) |
| 83 | # if OPENSSL_VERSION_NUMBER >= 0x0090800fL |
| 84 | # define EXIM_HAVE_ECDH /*MMMM*/ |
| 85 | # endif |
| 86 | # if OPENSSL_VERSION_NUMBER >= 0x10002000L |
| 87 | # define EXIM_HAVE_OPENSSL_EC_NIST2NID |
| 88 | # endif |
| 89 | # endif |
| 90 | #endif |
| 91 | |
| 92 | #if !defined(EXIM_HAVE_OPENSSL_TLSEXT) && !defined(DISABLE_OCSP) |
| 93 | # warning "OpenSSL library version too old; define DISABLE_OCSP in Makefile" |
| 94 | # define DISABLE_OCSP |
| 95 | #endif |
| 96 | |
| 97 | #ifdef EXIM_HAVE_OPENSSL_CHECKHOST |
| 98 | # include <openssl/x509v3.h> |
| 99 | #endif |
| 100 | |
| 101 | /* Structure for collecting random data for seeding. */ |
| 102 | |
| 103 | typedef struct randstuff { |
| 104 | struct timeval tv; |
| 105 | pid_t p; |
| 106 | } randstuff; |
| 107 | |
| 108 | /* Local static variables */ |
| 109 | |
| 110 | static BOOL client_verify_callback_called = FALSE; |
| 111 | static BOOL server_verify_callback_called = FALSE; |
| 112 | static const uschar *sid_ctx = US"exim"; |
| 113 | |
| 114 | /* We have three different contexts to care about. |
| 115 | |
| 116 | Simple case: client, `client_ctx` |
| 117 | As a client, we can be doing a callout or cut-through delivery while receiving |
| 118 | a message. So we have a client context, which should have options initialised |
| 119 | from the SMTP Transport. |
| 120 | |
| 121 | Server: |
| 122 | There are two cases: with and without ServerNameIndication from the client. |
| 123 | Given TLS SNI, we can be using different keys, certs and various other |
| 124 | configuration settings, because they're re-expanded with $tls_sni set. This |
| 125 | allows vhosting with TLS. This SNI is sent in the handshake. |
| 126 | A client might not send SNI, so we need a fallback, and an initial setup too. |
| 127 | So as a server, we start out using `server_ctx`. |
| 128 | If SNI is sent by the client, then we as server, mid-negotiation, try to clone |
| 129 | `server_sni` from `server_ctx` and then initialise settings by re-expanding |
| 130 | configuration. |
| 131 | */ |
| 132 | |
| 133 | static SSL_CTX *client_ctx = NULL; |
| 134 | static SSL_CTX *server_ctx = NULL; |
| 135 | static SSL *client_ssl = NULL; |
| 136 | static SSL *server_ssl = NULL; |
| 137 | |
| 138 | #ifdef EXIM_HAVE_OPENSSL_TLSEXT |
| 139 | static SSL_CTX *server_sni = NULL; |
| 140 | #endif |
| 141 | |
| 142 | static char ssl_errstring[256]; |
| 143 | |
| 144 | static int ssl_session_timeout = 200; |
| 145 | static BOOL client_verify_optional = FALSE; |
| 146 | static BOOL server_verify_optional = FALSE; |
| 147 | |
| 148 | static BOOL reexpand_tls_files_for_sni = FALSE; |
| 149 | |
| 150 | |
| 151 | typedef struct tls_ext_ctx_cb { |
| 152 | uschar *certificate; |
| 153 | uschar *privatekey; |
| 154 | BOOL is_server; |
| 155 | #ifndef DISABLE_OCSP |
| 156 | STACK_OF(X509) *verify_stack; /* chain for verifying the proof */ |
| 157 | union { |
| 158 | struct { |
| 159 | uschar *file; |
| 160 | uschar *file_expanded; |
| 161 | OCSP_RESPONSE *response; |
| 162 | } server; |
| 163 | struct { |
| 164 | X509_STORE *verify_store; /* non-null if status requested */ |
| 165 | BOOL verify_required; |
| 166 | } client; |
| 167 | } u_ocsp; |
| 168 | #endif |
| 169 | uschar *dhparam; |
| 170 | /* these are cached from first expand */ |
| 171 | uschar *server_cipher_list; |
| 172 | /* only passed down to tls_error: */ |
| 173 | host_item *host; |
| 174 | const uschar * verify_cert_hostnames; |
| 175 | #ifndef DISABLE_EVENT |
| 176 | uschar * event_action; |
| 177 | #endif |
| 178 | } tls_ext_ctx_cb; |
| 179 | |
| 180 | /* should figure out a cleanup of API to handle state preserved per |
| 181 | implementation, for various reasons, which can be void * in the APIs. |
| 182 | For now, we hack around it. */ |
| 183 | tls_ext_ctx_cb *client_static_cbinfo = NULL; |
| 184 | tls_ext_ctx_cb *server_static_cbinfo = NULL; |
| 185 | |
| 186 | static int |
| 187 | setup_certs(SSL_CTX *sctx, uschar *certs, uschar *crl, host_item *host, BOOL optional, |
| 188 | int (*cert_vfy_cb)(int, X509_STORE_CTX *), uschar ** errstr ); |
| 189 | |
| 190 | /* Callbacks */ |
| 191 | #ifdef EXIM_HAVE_OPENSSL_TLSEXT |
| 192 | static int tls_servername_cb(SSL *s, int *ad ARG_UNUSED, void *arg); |
| 193 | #endif |
| 194 | #ifndef DISABLE_OCSP |
| 195 | static int tls_server_stapling_cb(SSL *s, void *arg); |
| 196 | #endif |
| 197 | |
| 198 | |
| 199 | /************************************************* |
| 200 | * Handle TLS error * |
| 201 | *************************************************/ |
| 202 | |
| 203 | /* Called from lots of places when errors occur before actually starting to do |
| 204 | the TLS handshake, that is, while the session is still in clear. Always returns |
| 205 | DEFER for a server and FAIL for a client so that most calls can use "return |
| 206 | tls_error(...)" to do this processing and then give an appropriate return. A |
| 207 | single function is used for both server and client, because it is called from |
| 208 | some shared functions. |
| 209 | |
| 210 | Argument: |
| 211 | prefix text to include in the logged error |
| 212 | host NULL if setting up a server; |
| 213 | the connected host if setting up a client |
| 214 | msg error message or NULL if we should ask OpenSSL |
| 215 | errstr pointer to output error message |
| 216 | |
| 217 | Returns: OK/DEFER/FAIL |
| 218 | */ |
| 219 | |
| 220 | static int |
| 221 | tls_error(uschar * prefix, const host_item * host, uschar * msg, uschar ** errstr) |
| 222 | { |
| 223 | if (!msg) |
| 224 | { |
| 225 | ERR_error_string(ERR_get_error(), ssl_errstring); |
| 226 | msg = US ssl_errstring; |
| 227 | } |
| 228 | |
| 229 | if (errstr) *errstr = string_sprintf("(%s): %s", prefix, msg); |
| 230 | return host ? FAIL : DEFER; |
| 231 | } |
| 232 | |
| 233 | |
| 234 | |
| 235 | /************************************************* |
| 236 | * Callback to generate RSA key * |
| 237 | *************************************************/ |
| 238 | |
| 239 | /* |
| 240 | Arguments: |
| 241 | s SSL connection (not used) |
| 242 | export not used |
| 243 | keylength keylength |
| 244 | |
| 245 | Returns: pointer to generated key |
| 246 | */ |
| 247 | |
| 248 | static RSA * |
| 249 | rsa_callback(SSL *s, int export, int keylength) |
| 250 | { |
| 251 | RSA *rsa_key; |
| 252 | #ifdef EXIM_HAVE_RSA_GENKEY_EX |
| 253 | BIGNUM *bn = BN_new(); |
| 254 | #endif |
| 255 | |
| 256 | export = export; /* Shut picky compilers up */ |
| 257 | DEBUG(D_tls) debug_printf("Generating %d bit RSA key...\n", keylength); |
| 258 | |
| 259 | #ifdef EXIM_HAVE_RSA_GENKEY_EX |
| 260 | if ( !BN_set_word(bn, (unsigned long)RSA_F4) |
| 261 | || !(rsa_key = RSA_new()) |
| 262 | || !RSA_generate_key_ex(rsa_key, keylength, bn, NULL) |
| 263 | ) |
| 264 | #else |
| 265 | if (!(rsa_key = RSA_generate_key(keylength, RSA_F4, NULL, NULL))) |
| 266 | #endif |
| 267 | |
| 268 | { |
| 269 | ERR_error_string(ERR_get_error(), ssl_errstring); |
| 270 | log_write(0, LOG_MAIN|LOG_PANIC, "TLS error (RSA_generate_key): %s", |
| 271 | ssl_errstring); |
| 272 | return NULL; |
| 273 | } |
| 274 | return rsa_key; |
| 275 | } |
| 276 | |
| 277 | |
| 278 | |
| 279 | /* Extreme debug |
| 280 | #ifndef DISABLE_OCSP |
| 281 | void |
| 282 | x509_store_dump_cert_s_names(X509_STORE * store) |
| 283 | { |
| 284 | STACK_OF(X509_OBJECT) * roots= store->objs; |
| 285 | int i; |
| 286 | static uschar name[256]; |
| 287 | |
| 288 | for(i= 0; i<sk_X509_OBJECT_num(roots); i++) |
| 289 | { |
| 290 | X509_OBJECT * tmp_obj= sk_X509_OBJECT_value(roots, i); |
| 291 | if(tmp_obj->type == X509_LU_X509) |
| 292 | { |
| 293 | X509 * current_cert= tmp_obj->data.x509; |
| 294 | X509_NAME_oneline(X509_get_subject_name(current_cert), CS name, sizeof(name)); |
| 295 | name[sizeof(name)-1] = '\0'; |
| 296 | debug_printf(" %s\n", name); |
| 297 | } |
| 298 | } |
| 299 | } |
| 300 | #endif |
| 301 | */ |
| 302 | |
| 303 | |
| 304 | #ifndef DISABLE_EVENT |
| 305 | static int |
| 306 | verify_event(tls_support * tlsp, X509 * cert, int depth, const uschar * dn, |
| 307 | BOOL *calledp, const BOOL *optionalp, const uschar * what) |
| 308 | { |
| 309 | uschar * ev; |
| 310 | uschar * yield; |
| 311 | X509 * old_cert; |
| 312 | |
| 313 | ev = tlsp == &tls_out ? client_static_cbinfo->event_action : event_action; |
| 314 | if (ev) |
| 315 | { |
| 316 | DEBUG(D_tls) debug_printf("verify_event: %s %d\n", what, depth); |
| 317 | old_cert = tlsp->peercert; |
| 318 | tlsp->peercert = X509_dup(cert); |
| 319 | /* NB we do not bother setting peerdn */ |
| 320 | if ((yield = event_raise(ev, US"tls:cert", string_sprintf("%d", depth)))) |
| 321 | { |
| 322 | log_write(0, LOG_MAIN, "[%s] %s verify denied by event-action: " |
| 323 | "depth=%d cert=%s: %s", |
| 324 | tlsp == &tls_out ? deliver_host_address : sender_host_address, |
| 325 | what, depth, dn, yield); |
| 326 | *calledp = TRUE; |
| 327 | if (!*optionalp) |
| 328 | { |
| 329 | if (old_cert) tlsp->peercert = old_cert; /* restore 1st failing cert */ |
| 330 | return 1; /* reject (leaving peercert set) */ |
| 331 | } |
| 332 | DEBUG(D_tls) debug_printf("Event-action verify failure overridden " |
| 333 | "(host in tls_try_verify_hosts)\n"); |
| 334 | } |
| 335 | X509_free(tlsp->peercert); |
| 336 | tlsp->peercert = old_cert; |
| 337 | } |
| 338 | return 0; |
| 339 | } |
| 340 | #endif |
| 341 | |
| 342 | /************************************************* |
| 343 | * Callback for verification * |
| 344 | *************************************************/ |
| 345 | |
| 346 | /* The SSL library does certificate verification if set up to do so. This |
| 347 | callback has the current yes/no state is in "state". If verification succeeded, |
| 348 | we set the certificate-verified flag. If verification failed, what happens |
| 349 | depends on whether the client is required to present a verifiable certificate |
| 350 | or not. |
| 351 | |
| 352 | If verification is optional, we change the state to yes, but still log the |
| 353 | verification error. For some reason (it really would help to have proper |
| 354 | documentation of OpenSSL), this callback function then gets called again, this |
| 355 | time with state = 1. We must take care not to set the private verified flag on |
| 356 | the second time through. |
| 357 | |
| 358 | Note: this function is not called if the client fails to present a certificate |
| 359 | when asked. We get here only if a certificate has been received. Handling of |
| 360 | optional verification for this case is done when requesting SSL to verify, by |
| 361 | setting SSL_VERIFY_FAIL_IF_NO_PEER_CERT in the non-optional case. |
| 362 | |
| 363 | May be called multiple times for different issues with a certificate, even |
| 364 | for a given "depth" in the certificate chain. |
| 365 | |
| 366 | Arguments: |
| 367 | preverify_ok current yes/no state as 1/0 |
| 368 | x509ctx certificate information. |
| 369 | tlsp per-direction (client vs. server) support data |
| 370 | calledp has-been-called flag |
| 371 | optionalp verification-is-optional flag |
| 372 | |
| 373 | Returns: 0 if verification should fail, otherwise 1 |
| 374 | */ |
| 375 | |
| 376 | static int |
| 377 | verify_callback(int preverify_ok, X509_STORE_CTX *x509ctx, |
| 378 | tls_support *tlsp, BOOL *calledp, BOOL *optionalp) |
| 379 | { |
| 380 | X509 * cert = X509_STORE_CTX_get_current_cert(x509ctx); |
| 381 | int depth = X509_STORE_CTX_get_error_depth(x509ctx); |
| 382 | uschar dn[256]; |
| 383 | |
| 384 | X509_NAME_oneline(X509_get_subject_name(cert), CS dn, sizeof(dn)); |
| 385 | dn[sizeof(dn)-1] = '\0'; |
| 386 | |
| 387 | if (preverify_ok == 0) |
| 388 | { |
| 389 | uschar * extra = verify_mode ? string_sprintf(" (during %c-verify for [%s])", |
| 390 | *verify_mode, sender_host_address) |
| 391 | : US""; |
| 392 | log_write(0, LOG_MAIN, "[%s] SSL verify error%s: depth=%d error=%s cert=%s", |
| 393 | tlsp == &tls_out ? deliver_host_address : sender_host_address, |
| 394 | extra, depth, |
| 395 | X509_verify_cert_error_string(X509_STORE_CTX_get_error(x509ctx)), dn); |
| 396 | *calledp = TRUE; |
| 397 | if (!*optionalp) |
| 398 | { |
| 399 | if (!tlsp->peercert) |
| 400 | tlsp->peercert = X509_dup(cert); /* record failing cert */ |
| 401 | return 0; /* reject */ |
| 402 | } |
| 403 | DEBUG(D_tls) debug_printf("SSL verify failure overridden (host in " |
| 404 | "tls_try_verify_hosts)\n"); |
| 405 | } |
| 406 | |
| 407 | else if (depth != 0) |
| 408 | { |
| 409 | DEBUG(D_tls) debug_printf("SSL verify ok: depth=%d SN=%s\n", depth, dn); |
| 410 | #ifndef DISABLE_OCSP |
| 411 | if (tlsp == &tls_out && client_static_cbinfo->u_ocsp.client.verify_store) |
| 412 | { /* client, wanting stapling */ |
| 413 | /* Add the server cert's signing chain as the one |
| 414 | for the verification of the OCSP stapled information. */ |
| 415 | |
| 416 | if (!X509_STORE_add_cert(client_static_cbinfo->u_ocsp.client.verify_store, |
| 417 | cert)) |
| 418 | ERR_clear_error(); |
| 419 | sk_X509_push(client_static_cbinfo->verify_stack, cert); |
| 420 | } |
| 421 | #endif |
| 422 | #ifndef DISABLE_EVENT |
| 423 | if (verify_event(tlsp, cert, depth, dn, calledp, optionalp, US"SSL")) |
| 424 | return 0; /* reject, with peercert set */ |
| 425 | #endif |
| 426 | } |
| 427 | else |
| 428 | { |
| 429 | const uschar * verify_cert_hostnames; |
| 430 | |
| 431 | if ( tlsp == &tls_out |
| 432 | && ((verify_cert_hostnames = client_static_cbinfo->verify_cert_hostnames))) |
| 433 | /* client, wanting hostname check */ |
| 434 | { |
| 435 | |
| 436 | #ifdef EXIM_HAVE_OPENSSL_CHECKHOST |
| 437 | # ifndef X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS |
| 438 | # define X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS 0 |
| 439 | # endif |
| 440 | # ifndef X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS |
| 441 | # define X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS 0 |
| 442 | # endif |
| 443 | int sep = 0; |
| 444 | const uschar * list = verify_cert_hostnames; |
| 445 | uschar * name; |
| 446 | int rc; |
| 447 | while ((name = string_nextinlist(&list, &sep, NULL, 0))) |
| 448 | if ((rc = X509_check_host(cert, CCS name, 0, |
| 449 | X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS |
| 450 | | X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS, |
| 451 | NULL))) |
| 452 | { |
| 453 | if (rc < 0) |
| 454 | { |
| 455 | log_write(0, LOG_MAIN, "[%s] SSL verify error: internal error", |
| 456 | tlsp == &tls_out ? deliver_host_address : sender_host_address); |
| 457 | name = NULL; |
| 458 | } |
| 459 | break; |
| 460 | } |
| 461 | if (!name) |
| 462 | #else |
| 463 | if (!tls_is_name_for_cert(verify_cert_hostnames, cert)) |
| 464 | #endif |
| 465 | { |
| 466 | uschar * extra = verify_mode |
| 467 | ? string_sprintf(" (during %c-verify for [%s])", |
| 468 | *verify_mode, sender_host_address) |
| 469 | : US""; |
| 470 | log_write(0, LOG_MAIN, |
| 471 | "[%s] SSL verify error%s: certificate name mismatch: DN=\"%s\" H=\"%s\"", |
| 472 | tlsp == &tls_out ? deliver_host_address : sender_host_address, |
| 473 | extra, dn, verify_cert_hostnames); |
| 474 | *calledp = TRUE; |
| 475 | if (!*optionalp) |
| 476 | { |
| 477 | if (!tlsp->peercert) |
| 478 | tlsp->peercert = X509_dup(cert); /* record failing cert */ |
| 479 | return 0; /* reject */ |
| 480 | } |
| 481 | DEBUG(D_tls) debug_printf("SSL verify failure overridden (host in " |
| 482 | "tls_try_verify_hosts)\n"); |
| 483 | } |
| 484 | } |
| 485 | |
| 486 | #ifndef DISABLE_EVENT |
| 487 | if (verify_event(tlsp, cert, depth, dn, calledp, optionalp, US"SSL")) |
| 488 | return 0; /* reject, with peercert set */ |
| 489 | #endif |
| 490 | |
| 491 | DEBUG(D_tls) debug_printf("SSL%s verify ok: depth=0 SN=%s\n", |
| 492 | *calledp ? "" : " authenticated", dn); |
| 493 | if (!*calledp) tlsp->certificate_verified = TRUE; |
| 494 | *calledp = TRUE; |
| 495 | } |
| 496 | |
| 497 | return 1; /* accept, at least for this level */ |
| 498 | } |
| 499 | |
| 500 | static int |
| 501 | verify_callback_client(int preverify_ok, X509_STORE_CTX *x509ctx) |
| 502 | { |
| 503 | return verify_callback(preverify_ok, x509ctx, &tls_out, |
| 504 | &client_verify_callback_called, &client_verify_optional); |
| 505 | } |
| 506 | |
| 507 | static int |
| 508 | verify_callback_server(int preverify_ok, X509_STORE_CTX *x509ctx) |
| 509 | { |
| 510 | return verify_callback(preverify_ok, x509ctx, &tls_in, |
| 511 | &server_verify_callback_called, &server_verify_optional); |
| 512 | } |
| 513 | |
| 514 | |
| 515 | #ifdef SUPPORT_DANE |
| 516 | |
| 517 | /* This gets called *by* the dane library verify callback, which interposes |
| 518 | itself. |
| 519 | */ |
| 520 | static int |
| 521 | verify_callback_client_dane(int preverify_ok, X509_STORE_CTX * x509ctx) |
| 522 | { |
| 523 | X509 * cert = X509_STORE_CTX_get_current_cert(x509ctx); |
| 524 | uschar dn[256]; |
| 525 | int depth = X509_STORE_CTX_get_error_depth(x509ctx); |
| 526 | #ifndef DISABLE_EVENT |
| 527 | BOOL dummy_called, optional = FALSE; |
| 528 | #endif |
| 529 | |
| 530 | X509_NAME_oneline(X509_get_subject_name(cert), CS dn, sizeof(dn)); |
| 531 | dn[sizeof(dn)-1] = '\0'; |
| 532 | |
| 533 | DEBUG(D_tls) debug_printf("verify_callback_client_dane: %s depth %d %s\n", |
| 534 | preverify_ok ? "ok":"BAD", depth, dn); |
| 535 | |
| 536 | #ifndef DISABLE_EVENT |
| 537 | if (verify_event(&tls_out, cert, depth, dn, |
| 538 | &dummy_called, &optional, US"DANE")) |
| 539 | return 0; /* reject, with peercert set */ |
| 540 | #endif |
| 541 | |
| 542 | if (preverify_ok == 1) |
| 543 | { |
| 544 | tls_out.dane_verified = tls_out.certificate_verified = TRUE; |
| 545 | #ifndef DISABLE_OCSP |
| 546 | if (client_static_cbinfo->u_ocsp.client.verify_store) |
| 547 | { /* client, wanting stapling */ |
| 548 | /* Add the server cert's signing chain as the one |
| 549 | for the verification of the OCSP stapled information. */ |
| 550 | |
| 551 | if (!X509_STORE_add_cert(client_static_cbinfo->u_ocsp.client.verify_store, |
| 552 | cert)) |
| 553 | ERR_clear_error(); |
| 554 | sk_X509_push(client_static_cbinfo->verify_stack, cert); |
| 555 | } |
| 556 | #endif |
| 557 | } |
| 558 | else |
| 559 | { |
| 560 | int err = X509_STORE_CTX_get_error(x509ctx); |
| 561 | DEBUG(D_tls) |
| 562 | debug_printf(" - err %d '%s'\n", err, X509_verify_cert_error_string(err)); |
| 563 | if (err == X509_V_ERR_APPLICATION_VERIFICATION) |
| 564 | preverify_ok = 1; |
| 565 | } |
| 566 | return preverify_ok; |
| 567 | } |
| 568 | |
| 569 | #endif /*SUPPORT_DANE*/ |
| 570 | |
| 571 | |
| 572 | /************************************************* |
| 573 | * Information callback * |
| 574 | *************************************************/ |
| 575 | |
| 576 | /* The SSL library functions call this from time to time to indicate what they |
| 577 | are doing. We copy the string to the debugging output when TLS debugging has |
| 578 | been requested. |
| 579 | |
| 580 | Arguments: |
| 581 | s the SSL connection |
| 582 | where |
| 583 | ret |
| 584 | |
| 585 | Returns: nothing |
| 586 | */ |
| 587 | |
| 588 | static void |
| 589 | info_callback(SSL *s, int where, int ret) |
| 590 | { |
| 591 | where = where; |
| 592 | ret = ret; |
| 593 | DEBUG(D_tls) debug_printf("SSL info: %s\n", SSL_state_string_long(s)); |
| 594 | } |
| 595 | |
| 596 | |
| 597 | |
| 598 | /************************************************* |
| 599 | * Initialize for DH * |
| 600 | *************************************************/ |
| 601 | |
| 602 | /* If dhparam is set, expand it, and load up the parameters for DH encryption. |
| 603 | |
| 604 | Arguments: |
| 605 | sctx The current SSL CTX (inbound or outbound) |
| 606 | dhparam DH parameter file or fixed parameter identity string |
| 607 | host connected host, if client; NULL if server |
| 608 | errstr error string pointer |
| 609 | |
| 610 | Returns: TRUE if OK (nothing to set up, or setup worked) |
| 611 | */ |
| 612 | |
| 613 | static BOOL |
| 614 | init_dh(SSL_CTX *sctx, uschar *dhparam, const host_item *host, uschar ** errstr) |
| 615 | { |
| 616 | BIO *bio; |
| 617 | DH *dh; |
| 618 | uschar *dhexpanded; |
| 619 | const char *pem; |
| 620 | int dh_bitsize; |
| 621 | |
| 622 | if (!expand_check(dhparam, US"tls_dhparam", &dhexpanded, errstr)) |
| 623 | return FALSE; |
| 624 | |
| 625 | if (!dhexpanded || !*dhexpanded) |
| 626 | bio = BIO_new_mem_buf(CS std_dh_prime_default(), -1); |
| 627 | else if (dhexpanded[0] == '/') |
| 628 | { |
| 629 | if (!(bio = BIO_new_file(CS dhexpanded, "r"))) |
| 630 | { |
| 631 | tls_error(string_sprintf("could not read dhparams file %s", dhexpanded), |
| 632 | host, US strerror(errno), errstr); |
| 633 | return FALSE; |
| 634 | } |
| 635 | } |
| 636 | else |
| 637 | { |
| 638 | if (Ustrcmp(dhexpanded, "none") == 0) |
| 639 | { |
| 640 | DEBUG(D_tls) debug_printf("Requested no DH parameters.\n"); |
| 641 | return TRUE; |
| 642 | } |
| 643 | |
| 644 | if (!(pem = std_dh_prime_named(dhexpanded))) |
| 645 | { |
| 646 | tls_error(string_sprintf("Unknown standard DH prime \"%s\"", dhexpanded), |
| 647 | host, US strerror(errno), errstr); |
| 648 | return FALSE; |
| 649 | } |
| 650 | bio = BIO_new_mem_buf(CS pem, -1); |
| 651 | } |
| 652 | |
| 653 | if (!(dh = PEM_read_bio_DHparams(bio, NULL, NULL, NULL))) |
| 654 | { |
| 655 | BIO_free(bio); |
| 656 | tls_error(string_sprintf("Could not read tls_dhparams \"%s\"", dhexpanded), |
| 657 | host, NULL, errstr); |
| 658 | return FALSE; |
| 659 | } |
| 660 | |
| 661 | /* note: our default limit of 2236 is not a multiple of 8; the limit comes from |
| 662 | * an NSS limit, and the GnuTLS APIs handle bit-sizes fine, so we went with |
| 663 | * 2236. But older OpenSSL can only report in bytes (octets), not bits. |
| 664 | * If someone wants to dance at the edge, then they can raise the limit or use |
| 665 | * current libraries. */ |
| 666 | #ifdef EXIM_HAVE_OPENSSL_DH_BITS |
| 667 | /* Added in commit 26c79d5641d; `git describe --contains` says OpenSSL_1_1_0-pre1~1022 |
| 668 | * This predates OpenSSL_1_1_0 (before a, b, ...) so is in all 1.1.0 */ |
| 669 | dh_bitsize = DH_bits(dh); |
| 670 | #else |
| 671 | dh_bitsize = 8 * DH_size(dh); |
| 672 | #endif |
| 673 | |
| 674 | /* Even if it is larger, we silently return success rather than cause things |
| 675 | * to fail out, so that a too-large DH will not knock out all TLS; it's a |
| 676 | * debatable choice. */ |
| 677 | if (dh_bitsize > tls_dh_max_bits) |
| 678 | { |
| 679 | DEBUG(D_tls) |
| 680 | debug_printf("dhparams file %d bits, is > tls_dh_max_bits limit of %d\n", |
| 681 | dh_bitsize, tls_dh_max_bits); |
| 682 | } |
| 683 | else |
| 684 | { |
| 685 | SSL_CTX_set_tmp_dh(sctx, dh); |
| 686 | DEBUG(D_tls) |
| 687 | debug_printf("Diffie-Hellman initialized from %s with %d-bit prime\n", |
| 688 | dhexpanded ? dhexpanded : US"default", dh_bitsize); |
| 689 | } |
| 690 | |
| 691 | DH_free(dh); |
| 692 | BIO_free(bio); |
| 693 | |
| 694 | return TRUE; |
| 695 | } |
| 696 | |
| 697 | |
| 698 | |
| 699 | |
| 700 | /************************************************* |
| 701 | * Initialize for ECDH * |
| 702 | *************************************************/ |
| 703 | |
| 704 | /* Load parameters for ECDH encryption. |
| 705 | |
| 706 | For now, we stick to NIST P-256 because: it's simple and easy to configure; |
| 707 | it avoids any patent issues that might bite redistributors; despite events in |
| 708 | the news and concerns over curve choices, we're not cryptographers, we're not |
| 709 | pretending to be, and this is "good enough" to be better than no support, |
| 710 | protecting against most adversaries. Given another year or two, there might |
| 711 | be sufficient clarity about a "right" way forward to let us make an informed |
| 712 | decision, instead of a knee-jerk reaction. |
| 713 | |
| 714 | Longer-term, we should look at supporting both various named curves and |
| 715 | external files generated with "openssl ecparam", much as we do for init_dh(). |
| 716 | We should also support "none" as a value, to explicitly avoid initialisation. |
| 717 | |
| 718 | Patches welcome. |
| 719 | |
| 720 | Arguments: |
| 721 | sctx The current SSL CTX (inbound or outbound) |
| 722 | host connected host, if client; NULL if server |
| 723 | errstr error string pointer |
| 724 | |
| 725 | Returns: TRUE if OK (nothing to set up, or setup worked) |
| 726 | */ |
| 727 | |
| 728 | static BOOL |
| 729 | init_ecdh(SSL_CTX * sctx, host_item * host, uschar ** errstr) |
| 730 | { |
| 731 | #ifdef OPENSSL_NO_ECDH |
| 732 | return TRUE; |
| 733 | #else |
| 734 | |
| 735 | EC_KEY * ecdh; |
| 736 | uschar * exp_curve; |
| 737 | int nid; |
| 738 | BOOL rv; |
| 739 | |
| 740 | if (host) /* No ECDH setup for clients, only for servers */ |
| 741 | return TRUE; |
| 742 | |
| 743 | # ifndef EXIM_HAVE_ECDH |
| 744 | DEBUG(D_tls) |
| 745 | debug_printf("No OpenSSL API to define ECDH parameters, skipping\n"); |
| 746 | return TRUE; |
| 747 | # else |
| 748 | |
| 749 | if (!expand_check(tls_eccurve, US"tls_eccurve", &exp_curve, errstr)) |
| 750 | return FALSE; |
| 751 | if (!exp_curve || !*exp_curve) |
| 752 | return TRUE; |
| 753 | |
| 754 | /* "auto" needs to be handled carefully. |
| 755 | * OpenSSL < 1.0.2: we do not select anything, but fallback to prime256v1 |
| 756 | * OpenSSL < 1.1.0: we have to call SSL_CTX_set_ecdh_auto |
| 757 | * (openssl/ssl.h defines SSL_CTRL_SET_ECDH_AUTO) |
| 758 | * OpenSSL >= 1.1.0: we do not set anything, the libray does autoselection |
| 759 | * https://github.com/openssl/openssl/commit/fe6ef2472db933f01b59cad82aa925736935984b |
| 760 | */ |
| 761 | if (Ustrcmp(exp_curve, "auto") == 0) |
| 762 | { |
| 763 | #if OPENSSL_VERSION_NUMBER < 0x10002000L |
| 764 | DEBUG(D_tls) debug_printf( |
| 765 | "ECDH OpenSSL < 1.0.2: temp key parameter settings: overriding \"auto\" with \"prime256v1\"\n"); |
| 766 | exp_curve = US"prime256v1"; |
| 767 | #else |
| 768 | # if defined SSL_CTRL_SET_ECDH_AUTO |
| 769 | DEBUG(D_tls) debug_printf( |
| 770 | "ECDH OpenSSL 1.0.2+ temp key parameter settings: autoselection\n"); |
| 771 | SSL_CTX_set_ecdh_auto(sctx, 1); |
| 772 | return TRUE; |
| 773 | # else |
| 774 | DEBUG(D_tls) debug_printf( |
| 775 | "ECDH OpenSSL 1.1.0+ temp key parameter settings: default selection\n"); |
| 776 | return TRUE; |
| 777 | # endif |
| 778 | #endif |
| 779 | } |
| 780 | |
| 781 | DEBUG(D_tls) debug_printf("ECDH: curve '%s'\n", exp_curve); |
| 782 | if ( (nid = OBJ_sn2nid (CCS exp_curve)) == NID_undef |
| 783 | # ifdef EXIM_HAVE_OPENSSL_EC_NIST2NID |
| 784 | && (nid = EC_curve_nist2nid(CCS exp_curve)) == NID_undef |
| 785 | # endif |
| 786 | ) |
| 787 | { |
| 788 | tls_error(string_sprintf("Unknown curve name tls_eccurve '%s'", exp_curve), |
| 789 | host, NULL, errstr); |
| 790 | return FALSE; |
| 791 | } |
| 792 | |
| 793 | if (!(ecdh = EC_KEY_new_by_curve_name(nid))) |
| 794 | { |
| 795 | tls_error(US"Unable to create ec curve", host, NULL, errstr); |
| 796 | return FALSE; |
| 797 | } |
| 798 | |
| 799 | /* The "tmp" in the name here refers to setting a temporary key |
| 800 | not to the stability of the interface. */ |
| 801 | |
| 802 | if ((rv = SSL_CTX_set_tmp_ecdh(sctx, ecdh) == 0)) |
| 803 | tls_error(string_sprintf("Error enabling '%s' curve", exp_curve), host, NULL, errstr); |
| 804 | else |
| 805 | DEBUG(D_tls) debug_printf("ECDH: enabled '%s' curve\n", exp_curve); |
| 806 | |
| 807 | EC_KEY_free(ecdh); |
| 808 | return !rv; |
| 809 | |
| 810 | # endif /*EXIM_HAVE_ECDH*/ |
| 811 | #endif /*OPENSSL_NO_ECDH*/ |
| 812 | } |
| 813 | |
| 814 | |
| 815 | |
| 816 | |
| 817 | #ifndef DISABLE_OCSP |
| 818 | /************************************************* |
| 819 | * Load OCSP information into state * |
| 820 | *************************************************/ |
| 821 | /* Called to load the server OCSP response from the given file into memory, once |
| 822 | caller has determined this is needed. Checks validity. Debugs a message |
| 823 | if invalid. |
| 824 | |
| 825 | ASSUMES: single response, for single cert. |
| 826 | |
| 827 | Arguments: |
| 828 | sctx the SSL_CTX* to update |
| 829 | cbinfo various parts of session state |
| 830 | expanded the filename putatively holding an OCSP response |
| 831 | |
| 832 | */ |
| 833 | |
| 834 | static void |
| 835 | ocsp_load_response(SSL_CTX *sctx, tls_ext_ctx_cb *cbinfo, const uschar *expanded) |
| 836 | { |
| 837 | BIO * bio; |
| 838 | OCSP_RESPONSE * resp; |
| 839 | OCSP_BASICRESP * basic_response; |
| 840 | OCSP_SINGLERESP * single_response; |
| 841 | ASN1_GENERALIZEDTIME * rev, * thisupd, * nextupd; |
| 842 | STACK_OF(X509) * sk; |
| 843 | unsigned long verify_flags; |
| 844 | int status, reason, i; |
| 845 | |
| 846 | cbinfo->u_ocsp.server.file_expanded = string_copy(expanded); |
| 847 | if (cbinfo->u_ocsp.server.response) |
| 848 | { |
| 849 | OCSP_RESPONSE_free(cbinfo->u_ocsp.server.response); |
| 850 | cbinfo->u_ocsp.server.response = NULL; |
| 851 | } |
| 852 | |
| 853 | if (!(bio = BIO_new_file(CS cbinfo->u_ocsp.server.file_expanded, "rb"))) |
| 854 | { |
| 855 | DEBUG(D_tls) debug_printf("Failed to open OCSP response file \"%s\"\n", |
| 856 | cbinfo->u_ocsp.server.file_expanded); |
| 857 | return; |
| 858 | } |
| 859 | |
| 860 | resp = d2i_OCSP_RESPONSE_bio(bio, NULL); |
| 861 | BIO_free(bio); |
| 862 | if (!resp) |
| 863 | { |
| 864 | DEBUG(D_tls) debug_printf("Error reading OCSP response.\n"); |
| 865 | return; |
| 866 | } |
| 867 | |
| 868 | if ((status = OCSP_response_status(resp)) != OCSP_RESPONSE_STATUS_SUCCESSFUL) |
| 869 | { |
| 870 | DEBUG(D_tls) debug_printf("OCSP response not valid: %s (%d)\n", |
| 871 | OCSP_response_status_str(status), status); |
| 872 | goto bad; |
| 873 | } |
| 874 | |
| 875 | if (!(basic_response = OCSP_response_get1_basic(resp))) |
| 876 | { |
| 877 | DEBUG(D_tls) |
| 878 | debug_printf("OCSP response parse error: unable to extract basic response.\n"); |
| 879 | goto bad; |
| 880 | } |
| 881 | |
| 882 | sk = cbinfo->verify_stack; |
| 883 | verify_flags = OCSP_NOVERIFY; /* check sigs, but not purpose */ |
| 884 | |
| 885 | /* May need to expose ability to adjust those flags? |
| 886 | OCSP_NOSIGS OCSP_NOVERIFY OCSP_NOCHAIN OCSP_NOCHECKS OCSP_NOEXPLICIT |
| 887 | OCSP_TRUSTOTHER OCSP_NOINTERN */ |
| 888 | |
| 889 | /* This does a full verify on the OCSP proof before we load it for serving |
| 890 | up; possibly overkill - just date-checks might be nice enough. |
| 891 | |
| 892 | OCSP_basic_verify takes a "store" arg, but does not |
| 893 | use it for the chain verification, which is all we do |
| 894 | when OCSP_NOVERIFY is set. The content from the wire |
| 895 | "basic_response" and a cert-stack "sk" are all that is used. |
| 896 | |
| 897 | We have a stack, loaded in setup_certs() if tls_verify_certificates |
| 898 | was a file (not a directory, or "system"). It is unfortunate we |
| 899 | cannot used the connection context store, as that would neatly |
| 900 | handle the "system" case too, but there seems to be no library |
| 901 | function for getting a stack from a store. |
| 902 | [ In OpenSSL 1.1 - ? X509_STORE_CTX_get0_chain(ctx) ? ] |
| 903 | We do not free the stack since it could be needed a second time for |
| 904 | SNI handling. |
| 905 | |
| 906 | Separately we might try to replace using OCSP_basic_verify() - which seems to not |
| 907 | be a public interface into the OpenSSL library (there's no manual entry) - |
| 908 | But what with? We also use OCSP_basic_verify in the client stapling callback. |
| 909 | And there we NEED it; we must verify that status... unless the |
| 910 | library does it for us anyway? */ |
| 911 | |
| 912 | if ((i = OCSP_basic_verify(basic_response, sk, NULL, verify_flags)) < 0) |
| 913 | { |
| 914 | DEBUG(D_tls) |
| 915 | { |
| 916 | ERR_error_string(ERR_get_error(), ssl_errstring); |
| 917 | debug_printf("OCSP response verify failure: %s\n", US ssl_errstring); |
| 918 | } |
| 919 | goto bad; |
| 920 | } |
| 921 | |
| 922 | /* Here's the simplifying assumption: there's only one response, for the |
| 923 | one certificate we use, and nothing for anything else in a chain. If this |
| 924 | proves false, we need to extract a cert id from our issued cert |
| 925 | (tls_certificate) and use that for OCSP_resp_find_status() (which finds the |
| 926 | right cert in the stack and then calls OCSP_single_get0_status()). |
| 927 | |
| 928 | I'm hoping to avoid reworking a bunch more of how we handle state here. */ |
| 929 | |
| 930 | if (!(single_response = OCSP_resp_get0(basic_response, 0))) |
| 931 | { |
| 932 | DEBUG(D_tls) |
| 933 | debug_printf("Unable to get first response from OCSP basic response.\n"); |
| 934 | goto bad; |
| 935 | } |
| 936 | |
| 937 | status = OCSP_single_get0_status(single_response, &reason, &rev, &thisupd, &nextupd); |
| 938 | if (status != V_OCSP_CERTSTATUS_GOOD) |
| 939 | { |
| 940 | DEBUG(D_tls) debug_printf("OCSP response bad cert status: %s (%d) %s (%d)\n", |
| 941 | OCSP_cert_status_str(status), status, |
| 942 | OCSP_crl_reason_str(reason), reason); |
| 943 | goto bad; |
| 944 | } |
| 945 | |
| 946 | if (!OCSP_check_validity(thisupd, nextupd, EXIM_OCSP_SKEW_SECONDS, EXIM_OCSP_MAX_AGE)) |
| 947 | { |
| 948 | DEBUG(D_tls) debug_printf("OCSP status invalid times.\n"); |
| 949 | goto bad; |
| 950 | } |
| 951 | |
| 952 | supply_response: |
| 953 | cbinfo->u_ocsp.server.response = resp; /*XXX stack?*/ |
| 954 | return; |
| 955 | |
| 956 | bad: |
| 957 | if (running_in_test_harness) |
| 958 | { |
| 959 | extern char ** environ; |
| 960 | uschar ** p; |
| 961 | if (environ) for (p = USS environ; *p; p++) |
| 962 | if (Ustrncmp(*p, "EXIM_TESTHARNESS_DISABLE_OCSPVALIDITYCHECK", 42) == 0) |
| 963 | { |
| 964 | DEBUG(D_tls) debug_printf("Supplying known bad OCSP response\n"); |
| 965 | goto supply_response; |
| 966 | } |
| 967 | } |
| 968 | return; |
| 969 | } |
| 970 | #endif /*!DISABLE_OCSP*/ |
| 971 | |
| 972 | |
| 973 | |
| 974 | |
| 975 | /* Create and install a selfsigned certificate, for use in server mode */ |
| 976 | |
| 977 | static int |
| 978 | tls_install_selfsign(SSL_CTX * sctx, uschar ** errstr) |
| 979 | { |
| 980 | X509 * x509 = NULL; |
| 981 | EVP_PKEY * pkey; |
| 982 | RSA * rsa; |
| 983 | X509_NAME * name; |
| 984 | uschar * where; |
| 985 | |
| 986 | where = US"allocating pkey"; |
| 987 | if (!(pkey = EVP_PKEY_new())) |
| 988 | goto err; |
| 989 | |
| 990 | where = US"allocating cert"; |
| 991 | if (!(x509 = X509_new())) |
| 992 | goto err; |
| 993 | |
| 994 | where = US"generating pkey"; |
| 995 | if (!(rsa = rsa_callback(NULL, 0, 1024))) |
| 996 | goto err; |
| 997 | |
| 998 | where = US"assigning pkey"; |
| 999 | if (!EVP_PKEY_assign_RSA(pkey, rsa)) |
| 1000 | goto err; |
| 1001 | |
| 1002 | X509_set_version(x509, 2); /* N+1 - version 3 */ |
| 1003 | ASN1_INTEGER_set(X509_get_serialNumber(x509), 0); |
| 1004 | X509_gmtime_adj(X509_get_notBefore(x509), 0); |
| 1005 | X509_gmtime_adj(X509_get_notAfter(x509), (long)60 * 60); /* 1 hour */ |
| 1006 | X509_set_pubkey(x509, pkey); |
| 1007 | |
| 1008 | name = X509_get_subject_name(x509); |
| 1009 | X509_NAME_add_entry_by_txt(name, "C", |
| 1010 | MBSTRING_ASC, CUS "UK", -1, -1, 0); |
| 1011 | X509_NAME_add_entry_by_txt(name, "O", |
| 1012 | MBSTRING_ASC, CUS "Exim Developers", -1, -1, 0); |
| 1013 | X509_NAME_add_entry_by_txt(name, "CN", |
| 1014 | MBSTRING_ASC, CUS smtp_active_hostname, -1, -1, 0); |
| 1015 | X509_set_issuer_name(x509, name); |
| 1016 | |
| 1017 | where = US"signing cert"; |
| 1018 | if (!X509_sign(x509, pkey, EVP_md5())) |
| 1019 | goto err; |
| 1020 | |
| 1021 | where = US"installing selfsign cert"; |
| 1022 | if (!SSL_CTX_use_certificate(sctx, x509)) |
| 1023 | goto err; |
| 1024 | |
| 1025 | where = US"installing selfsign key"; |
| 1026 | if (!SSL_CTX_use_PrivateKey(sctx, pkey)) |
| 1027 | goto err; |
| 1028 | |
| 1029 | return OK; |
| 1030 | |
| 1031 | err: |
| 1032 | (void) tls_error(where, NULL, NULL, errstr); |
| 1033 | if (x509) X509_free(x509); |
| 1034 | if (pkey) EVP_PKEY_free(pkey); |
| 1035 | return DEFER; |
| 1036 | } |
| 1037 | |
| 1038 | |
| 1039 | |
| 1040 | |
| 1041 | static int |
| 1042 | tls_add_certfile(SSL_CTX * sctx, tls_ext_ctx_cb * cbinfo, uschar * file, |
| 1043 | uschar ** errstr) |
| 1044 | { |
| 1045 | DEBUG(D_tls) debug_printf("tls_certificate file %s\n", file); |
| 1046 | if (!SSL_CTX_use_certificate_chain_file(sctx, CS file)) |
| 1047 | return tls_error(string_sprintf( |
| 1048 | "SSL_CTX_use_certificate_chain_file file=%s", file), |
| 1049 | cbinfo->host, NULL, errstr); |
| 1050 | return 0; |
| 1051 | } |
| 1052 | |
| 1053 | static int |
| 1054 | tls_add_pkeyfile(SSL_CTX * sctx, tls_ext_ctx_cb * cbinfo, uschar * file, |
| 1055 | uschar ** errstr) |
| 1056 | { |
| 1057 | DEBUG(D_tls) debug_printf("tls_privatekey file %s\n", file); |
| 1058 | if (!SSL_CTX_use_PrivateKey_file(sctx, CS file, SSL_FILETYPE_PEM)) |
| 1059 | return tls_error(string_sprintf( |
| 1060 | "SSL_CTX_use_PrivateKey_file file=%s", file), cbinfo->host, NULL, errstr); |
| 1061 | return 0; |
| 1062 | } |
| 1063 | |
| 1064 | |
| 1065 | /************************************************* |
| 1066 | * Expand key and cert file specs * |
| 1067 | *************************************************/ |
| 1068 | |
| 1069 | /* Called once during tls_init and possibly again during TLS setup, for a |
| 1070 | new context, if Server Name Indication was used and tls_sni was seen in |
| 1071 | the certificate string. |
| 1072 | |
| 1073 | Arguments: |
| 1074 | sctx the SSL_CTX* to update |
| 1075 | cbinfo various parts of session state |
| 1076 | errstr error string pointer |
| 1077 | |
| 1078 | Returns: OK/DEFER/FAIL |
| 1079 | */ |
| 1080 | |
| 1081 | static int |
| 1082 | tls_expand_session_files(SSL_CTX *sctx, tls_ext_ctx_cb *cbinfo, |
| 1083 | uschar ** errstr) |
| 1084 | { |
| 1085 | uschar *expanded; |
| 1086 | |
| 1087 | if (!cbinfo->certificate) |
| 1088 | { |
| 1089 | if (!cbinfo->is_server) /* client */ |
| 1090 | return OK; |
| 1091 | /* server */ |
| 1092 | if (tls_install_selfsign(sctx, errstr) != OK) |
| 1093 | return DEFER; |
| 1094 | } |
| 1095 | else |
| 1096 | { |
| 1097 | int err; |
| 1098 | |
| 1099 | if (Ustrstr(cbinfo->certificate, US"tls_sni") || |
| 1100 | Ustrstr(cbinfo->certificate, US"tls_in_sni") || |
| 1101 | Ustrstr(cbinfo->certificate, US"tls_out_sni") |
| 1102 | ) |
| 1103 | reexpand_tls_files_for_sni = TRUE; |
| 1104 | |
| 1105 | if (!expand_check(cbinfo->certificate, US"tls_certificate", &expanded, errstr)) |
| 1106 | return DEFER; |
| 1107 | |
| 1108 | if (expanded) |
| 1109 | if (cbinfo->is_server) |
| 1110 | { |
| 1111 | const uschar * file_list = expanded; |
| 1112 | int sep = 0; |
| 1113 | uschar * file; |
| 1114 | |
| 1115 | while (file = string_nextinlist(&file_list, &sep, NULL, 0)) |
| 1116 | if ((err = tls_add_certfile(sctx, cbinfo, file, errstr))) |
| 1117 | return err; |
| 1118 | } |
| 1119 | else /* would there ever be a need for multiple client certs? */ |
| 1120 | if ((err = tls_add_certfile(sctx, cbinfo, expanded, errstr))) |
| 1121 | return err; |
| 1122 | |
| 1123 | if (cbinfo->privatekey != NULL && |
| 1124 | !expand_check(cbinfo->privatekey, US"tls_privatekey", &expanded, errstr)) |
| 1125 | return DEFER; |
| 1126 | |
| 1127 | /* If expansion was forced to fail, key_expanded will be NULL. If the result |
| 1128 | of the expansion is an empty string, ignore it also, and assume the private |
| 1129 | key is in the same file as the certificate. */ |
| 1130 | |
| 1131 | if (expanded && *expanded) |
| 1132 | if (cbinfo->is_server) |
| 1133 | { |
| 1134 | const uschar * file_list = expanded; |
| 1135 | int sep = 0; |
| 1136 | uschar * file; |
| 1137 | |
| 1138 | while (file = string_nextinlist(&file_list, &sep, NULL, 0)) |
| 1139 | if ((err = tls_add_pkeyfile(sctx, cbinfo, file, errstr))) |
| 1140 | return err; |
| 1141 | } |
| 1142 | else /* would there ever be a need for multiple client certs? */ |
| 1143 | if ((err = tls_add_pkeyfile(sctx, cbinfo, expanded, errstr))) |
| 1144 | return err; |
| 1145 | } |
| 1146 | |
| 1147 | #ifndef DISABLE_OCSP |
| 1148 | if (cbinfo->is_server && cbinfo->u_ocsp.server.file) |
| 1149 | { |
| 1150 | /*XXX stack*/ |
| 1151 | if (!expand_check(cbinfo->u_ocsp.server.file, US"tls_ocsp_file", &expanded, errstr)) |
| 1152 | return DEFER; |
| 1153 | |
| 1154 | if (expanded && *expanded) |
| 1155 | { |
| 1156 | DEBUG(D_tls) debug_printf("tls_ocsp_file %s\n", expanded); |
| 1157 | if ( cbinfo->u_ocsp.server.file_expanded |
| 1158 | && (Ustrcmp(expanded, cbinfo->u_ocsp.server.file_expanded) == 0)) |
| 1159 | { |
| 1160 | DEBUG(D_tls) debug_printf(" - value unchanged, using existing values\n"); |
| 1161 | } |
| 1162 | else |
| 1163 | ocsp_load_response(sctx, cbinfo, expanded); |
| 1164 | } |
| 1165 | } |
| 1166 | #endif |
| 1167 | |
| 1168 | return OK; |
| 1169 | } |
| 1170 | |
| 1171 | |
| 1172 | |
| 1173 | |
| 1174 | /************************************************* |
| 1175 | * Callback to handle SNI * |
| 1176 | *************************************************/ |
| 1177 | |
| 1178 | /* Called when acting as server during the TLS session setup if a Server Name |
| 1179 | Indication extension was sent by the client. |
| 1180 | |
| 1181 | API documentation is OpenSSL s_server.c implementation. |
| 1182 | |
| 1183 | Arguments: |
| 1184 | s SSL* of the current session |
| 1185 | ad unknown (part of OpenSSL API) (unused) |
| 1186 | arg Callback of "our" registered data |
| 1187 | |
| 1188 | Returns: SSL_TLSEXT_ERR_{OK,ALERT_WARNING,ALERT_FATAL,NOACK} |
| 1189 | */ |
| 1190 | |
| 1191 | #ifdef EXIM_HAVE_OPENSSL_TLSEXT |
| 1192 | static int |
| 1193 | tls_servername_cb(SSL *s, int *ad ARG_UNUSED, void *arg) |
| 1194 | { |
| 1195 | const char *servername = SSL_get_servername(s, TLSEXT_NAMETYPE_host_name); |
| 1196 | tls_ext_ctx_cb *cbinfo = (tls_ext_ctx_cb *) arg; |
| 1197 | int rc; |
| 1198 | int old_pool = store_pool; |
| 1199 | uschar * dummy_errstr; |
| 1200 | |
| 1201 | if (!servername) |
| 1202 | return SSL_TLSEXT_ERR_OK; |
| 1203 | |
| 1204 | DEBUG(D_tls) debug_printf("Received TLS SNI \"%s\"%s\n", servername, |
| 1205 | reexpand_tls_files_for_sni ? "" : " (unused for certificate selection)"); |
| 1206 | |
| 1207 | /* Make the extension value available for expansion */ |
| 1208 | store_pool = POOL_PERM; |
| 1209 | tls_in.sni = string_copy(US servername); |
| 1210 | store_pool = old_pool; |
| 1211 | |
| 1212 | if (!reexpand_tls_files_for_sni) |
| 1213 | return SSL_TLSEXT_ERR_OK; |
| 1214 | |
| 1215 | /* Can't find an SSL_CTX_clone() or equivalent, so we do it manually; |
| 1216 | not confident that memcpy wouldn't break some internal reference counting. |
| 1217 | Especially since there's a references struct member, which would be off. */ |
| 1218 | |
| 1219 | if (!(server_sni = SSL_CTX_new(SSLv23_server_method()))) |
| 1220 | { |
| 1221 | ERR_error_string(ERR_get_error(), ssl_errstring); |
| 1222 | DEBUG(D_tls) debug_printf("SSL_CTX_new() failed: %s\n", ssl_errstring); |
| 1223 | return SSL_TLSEXT_ERR_NOACK; |
| 1224 | } |
| 1225 | |
| 1226 | /* Not sure how many of these are actually needed, since SSL object |
| 1227 | already exists. Might even need this selfsame callback, for reneg? */ |
| 1228 | |
| 1229 | SSL_CTX_set_info_callback(server_sni, SSL_CTX_get_info_callback(server_ctx)); |
| 1230 | SSL_CTX_set_mode(server_sni, SSL_CTX_get_mode(server_ctx)); |
| 1231 | SSL_CTX_set_options(server_sni, SSL_CTX_get_options(server_ctx)); |
| 1232 | SSL_CTX_set_timeout(server_sni, SSL_CTX_get_timeout(server_ctx)); |
| 1233 | SSL_CTX_set_tlsext_servername_callback(server_sni, tls_servername_cb); |
| 1234 | SSL_CTX_set_tlsext_servername_arg(server_sni, cbinfo); |
| 1235 | |
| 1236 | if ( !init_dh(server_sni, cbinfo->dhparam, NULL, &dummy_errstr) |
| 1237 | || !init_ecdh(server_sni, NULL, &dummy_errstr) |
| 1238 | ) |
| 1239 | return SSL_TLSEXT_ERR_NOACK; |
| 1240 | |
| 1241 | if (cbinfo->server_cipher_list) |
| 1242 | SSL_CTX_set_cipher_list(server_sni, CS cbinfo->server_cipher_list); |
| 1243 | #ifndef DISABLE_OCSP |
| 1244 | if (cbinfo->u_ocsp.server.file) |
| 1245 | { |
| 1246 | SSL_CTX_set_tlsext_status_cb(server_sni, tls_server_stapling_cb); |
| 1247 | SSL_CTX_set_tlsext_status_arg(server_sni, cbinfo); |
| 1248 | } |
| 1249 | #endif |
| 1250 | |
| 1251 | if ((rc = setup_certs(server_sni, tls_verify_certificates, tls_crl, NULL, FALSE, |
| 1252 | verify_callback_server, &dummy_errstr)) != OK) |
| 1253 | return SSL_TLSEXT_ERR_NOACK; |
| 1254 | |
| 1255 | /* do this after setup_certs, because this can require the certs for verifying |
| 1256 | OCSP information. */ |
| 1257 | if ((rc = tls_expand_session_files(server_sni, cbinfo, &dummy_errstr)) != OK) |
| 1258 | return SSL_TLSEXT_ERR_NOACK; |
| 1259 | |
| 1260 | DEBUG(D_tls) debug_printf("Switching SSL context.\n"); |
| 1261 | SSL_set_SSL_CTX(s, server_sni); |
| 1262 | |
| 1263 | return SSL_TLSEXT_ERR_OK; |
| 1264 | } |
| 1265 | #endif /* EXIM_HAVE_OPENSSL_TLSEXT */ |
| 1266 | |
| 1267 | |
| 1268 | |
| 1269 | |
| 1270 | #ifndef DISABLE_OCSP |
| 1271 | |
| 1272 | /************************************************* |
| 1273 | * Callback to handle OCSP Stapling * |
| 1274 | *************************************************/ |
| 1275 | |
| 1276 | /* Called when acting as server during the TLS session setup if the client |
| 1277 | requests OCSP information with a Certificate Status Request. |
| 1278 | |
| 1279 | Documentation via openssl s_server.c and the Apache patch from the OpenSSL |
| 1280 | project. |
| 1281 | |
| 1282 | */ |
| 1283 | |
| 1284 | static int |
| 1285 | tls_server_stapling_cb(SSL *s, void *arg) |
| 1286 | { |
| 1287 | const tls_ext_ctx_cb *cbinfo = (tls_ext_ctx_cb *) arg; |
| 1288 | uschar *response_der; /*XXX blob */ |
| 1289 | int response_der_len; |
| 1290 | |
| 1291 | /*XXX stack: use SSL_get_certificate() to see which cert; from that work |
| 1292 | out which ocsp blob to send. Unfortunately, SSL_get_certificate is known |
| 1293 | buggy in current OpenSSL; it returns the last cert loaded always rather than |
| 1294 | the one actually presented. So we can't support a stack of OCSP proofs at |
| 1295 | this time. */ |
| 1296 | |
| 1297 | DEBUG(D_tls) |
| 1298 | debug_printf("Received TLS status request (OCSP stapling); %s response\n", |
| 1299 | cbinfo->u_ocsp.server.response ? "have" : "lack"); |
| 1300 | |
| 1301 | tls_in.ocsp = OCSP_NOT_RESP; |
| 1302 | if (!cbinfo->u_ocsp.server.response) |
| 1303 | return SSL_TLSEXT_ERR_NOACK; |
| 1304 | |
| 1305 | response_der = NULL; |
| 1306 | response_der_len = i2d_OCSP_RESPONSE(cbinfo->u_ocsp.server.response, /*XXX stack*/ |
| 1307 | &response_der); |
| 1308 | if (response_der_len <= 0) |
| 1309 | return SSL_TLSEXT_ERR_NOACK; |
| 1310 | |
| 1311 | SSL_set_tlsext_status_ocsp_resp(server_ssl, response_der, response_der_len); |
| 1312 | tls_in.ocsp = OCSP_VFIED; |
| 1313 | return SSL_TLSEXT_ERR_OK; |
| 1314 | } |
| 1315 | |
| 1316 | |
| 1317 | static void |
| 1318 | time_print(BIO * bp, const char * str, ASN1_GENERALIZEDTIME * time) |
| 1319 | { |
| 1320 | BIO_printf(bp, "\t%s: ", str); |
| 1321 | ASN1_GENERALIZEDTIME_print(bp, time); |
| 1322 | BIO_puts(bp, "\n"); |
| 1323 | } |
| 1324 | |
| 1325 | static int |
| 1326 | tls_client_stapling_cb(SSL *s, void *arg) |
| 1327 | { |
| 1328 | tls_ext_ctx_cb * cbinfo = arg; |
| 1329 | const unsigned char * p; |
| 1330 | int len; |
| 1331 | OCSP_RESPONSE * rsp; |
| 1332 | OCSP_BASICRESP * bs; |
| 1333 | int i; |
| 1334 | |
| 1335 | DEBUG(D_tls) debug_printf("Received TLS status response (OCSP stapling):"); |
| 1336 | len = SSL_get_tlsext_status_ocsp_resp(s, &p); |
| 1337 | if(!p) |
| 1338 | { |
| 1339 | /* Expect this when we requested ocsp but got none */ |
| 1340 | if (cbinfo->u_ocsp.client.verify_required && LOGGING(tls_cipher)) |
| 1341 | log_write(0, LOG_MAIN, "Received TLS status callback, null content"); |
| 1342 | else |
| 1343 | DEBUG(D_tls) debug_printf(" null\n"); |
| 1344 | return cbinfo->u_ocsp.client.verify_required ? 0 : 1; |
| 1345 | } |
| 1346 | |
| 1347 | if(!(rsp = d2i_OCSP_RESPONSE(NULL, &p, len))) |
| 1348 | { |
| 1349 | tls_out.ocsp = OCSP_FAILED; |
| 1350 | if (LOGGING(tls_cipher)) |
| 1351 | log_write(0, LOG_MAIN, "Received TLS cert status response, parse error"); |
| 1352 | else |
| 1353 | DEBUG(D_tls) debug_printf(" parse error\n"); |
| 1354 | return 0; |
| 1355 | } |
| 1356 | |
| 1357 | if(!(bs = OCSP_response_get1_basic(rsp))) |
| 1358 | { |
| 1359 | tls_out.ocsp = OCSP_FAILED; |
| 1360 | if (LOGGING(tls_cipher)) |
| 1361 | log_write(0, LOG_MAIN, "Received TLS cert status response, error parsing response"); |
| 1362 | else |
| 1363 | DEBUG(D_tls) debug_printf(" error parsing response\n"); |
| 1364 | OCSP_RESPONSE_free(rsp); |
| 1365 | return 0; |
| 1366 | } |
| 1367 | |
| 1368 | /* We'd check the nonce here if we'd put one in the request. */ |
| 1369 | /* However that would defeat cacheability on the server so we don't. */ |
| 1370 | |
| 1371 | /* This section of code reworked from OpenSSL apps source; |
| 1372 | The OpenSSL Project retains copyright: |
| 1373 | Copyright (c) 1999 The OpenSSL Project. All rights reserved. |
| 1374 | */ |
| 1375 | { |
| 1376 | BIO * bp = NULL; |
| 1377 | int status, reason; |
| 1378 | ASN1_GENERALIZEDTIME *rev, *thisupd, *nextupd; |
| 1379 | |
| 1380 | DEBUG(D_tls) bp = BIO_new_fp(debug_file, BIO_NOCLOSE); |
| 1381 | |
| 1382 | /*OCSP_RESPONSE_print(bp, rsp, 0); extreme debug: stapling content */ |
| 1383 | |
| 1384 | /* Use the chain that verified the server cert to verify the stapled info */ |
| 1385 | /* DEBUG(D_tls) x509_store_dump_cert_s_names(cbinfo->u_ocsp.client.verify_store); */ |
| 1386 | |
| 1387 | if ((i = OCSP_basic_verify(bs, cbinfo->verify_stack, |
| 1388 | cbinfo->u_ocsp.client.verify_store, 0)) <= 0) |
| 1389 | { |
| 1390 | tls_out.ocsp = OCSP_FAILED; |
| 1391 | if (LOGGING(tls_cipher)) log_write(0, LOG_MAIN, |
| 1392 | "Received TLS cert status response, itself unverifiable: %s", |
| 1393 | ERR_reason_error_string(ERR_peek_error())); |
| 1394 | BIO_printf(bp, "OCSP response verify failure\n"); |
| 1395 | ERR_print_errors(bp); |
| 1396 | OCSP_RESPONSE_print(bp, rsp, 0); |
| 1397 | goto failed; |
| 1398 | } |
| 1399 | |
| 1400 | BIO_printf(bp, "OCSP response well-formed and signed OK\n"); |
| 1401 | |
| 1402 | /*XXX So we have a good stapled OCSP status. How do we know |
| 1403 | it is for the cert of interest? OpenSSL 1.1.0 has a routine |
| 1404 | OCSP_resp_find_status() which matches on a cert id, which presumably |
| 1405 | we should use. Making an id needs OCSP_cert_id_new(), which takes |
| 1406 | issuerName, issuerKey, serialNumber. Are they all in the cert? |
| 1407 | |
| 1408 | For now, carry on blindly accepting the resp. */ |
| 1409 | |
| 1410 | { |
| 1411 | OCSP_SINGLERESP * single; |
| 1412 | |
| 1413 | #ifdef EXIM_HAVE_OCSP_RESP_COUNT |
| 1414 | if (OCSP_resp_count(bs) != 1) |
| 1415 | #else |
| 1416 | STACK_OF(OCSP_SINGLERESP) * sresp = bs->tbsResponseData->responses; |
| 1417 | if (sk_OCSP_SINGLERESP_num(sresp) != 1) |
| 1418 | #endif |
| 1419 | { |
| 1420 | tls_out.ocsp = OCSP_FAILED; |
| 1421 | log_write(0, LOG_MAIN, "OCSP stapling " |
| 1422 | "with multiple responses not handled"); |
| 1423 | goto failed; |
| 1424 | } |
| 1425 | single = OCSP_resp_get0(bs, 0); |
| 1426 | status = OCSP_single_get0_status(single, &reason, &rev, |
| 1427 | &thisupd, &nextupd); |
| 1428 | } |
| 1429 | |
| 1430 | DEBUG(D_tls) time_print(bp, "This OCSP Update", thisupd); |
| 1431 | DEBUG(D_tls) if(nextupd) time_print(bp, "Next OCSP Update", nextupd); |
| 1432 | if (!OCSP_check_validity(thisupd, nextupd, |
| 1433 | EXIM_OCSP_SKEW_SECONDS, EXIM_OCSP_MAX_AGE)) |
| 1434 | { |
| 1435 | tls_out.ocsp = OCSP_FAILED; |
| 1436 | DEBUG(D_tls) ERR_print_errors(bp); |
| 1437 | log_write(0, LOG_MAIN, "Server OSCP dates invalid"); |
| 1438 | } |
| 1439 | else |
| 1440 | { |
| 1441 | DEBUG(D_tls) BIO_printf(bp, "Certificate status: %s\n", |
| 1442 | OCSP_cert_status_str(status)); |
| 1443 | switch(status) |
| 1444 | { |
| 1445 | case V_OCSP_CERTSTATUS_GOOD: |
| 1446 | tls_out.ocsp = OCSP_VFIED; |
| 1447 | i = 1; |
| 1448 | goto good; |
| 1449 | case V_OCSP_CERTSTATUS_REVOKED: |
| 1450 | tls_out.ocsp = OCSP_FAILED; |
| 1451 | log_write(0, LOG_MAIN, "Server certificate revoked%s%s", |
| 1452 | reason != -1 ? "; reason: " : "", |
| 1453 | reason != -1 ? OCSP_crl_reason_str(reason) : ""); |
| 1454 | DEBUG(D_tls) time_print(bp, "Revocation Time", rev); |
| 1455 | break; |
| 1456 | default: |
| 1457 | tls_out.ocsp = OCSP_FAILED; |
| 1458 | log_write(0, LOG_MAIN, |
| 1459 | "Server certificate status unknown, in OCSP stapling"); |
| 1460 | break; |
| 1461 | } |
| 1462 | } |
| 1463 | failed: |
| 1464 | i = cbinfo->u_ocsp.client.verify_required ? 0 : 1; |
| 1465 | good: |
| 1466 | BIO_free(bp); |
| 1467 | } |
| 1468 | |
| 1469 | OCSP_RESPONSE_free(rsp); |
| 1470 | return i; |
| 1471 | } |
| 1472 | #endif /*!DISABLE_OCSP*/ |
| 1473 | |
| 1474 | |
| 1475 | /************************************************* |
| 1476 | * Initialize for TLS * |
| 1477 | *************************************************/ |
| 1478 | |
| 1479 | /* Called from both server and client code, to do preliminary initialization |
| 1480 | of the library. We allocate and return a context structure. |
| 1481 | |
| 1482 | Arguments: |
| 1483 | ctxp returned SSL context |
| 1484 | host connected host, if client; NULL if server |
| 1485 | dhparam DH parameter file |
| 1486 | certificate certificate file |
| 1487 | privatekey private key |
| 1488 | ocsp_file file of stapling info (server); flag for require ocsp (client) |
| 1489 | addr address if client; NULL if server (for some randomness) |
| 1490 | cbp place to put allocated callback context |
| 1491 | errstr error string pointer |
| 1492 | |
| 1493 | Returns: OK/DEFER/FAIL |
| 1494 | */ |
| 1495 | |
| 1496 | static int |
| 1497 | tls_init(SSL_CTX **ctxp, host_item *host, uschar *dhparam, uschar *certificate, |
| 1498 | uschar *privatekey, |
| 1499 | #ifndef DISABLE_OCSP |
| 1500 | uschar *ocsp_file, /*XXX stack, in server*/ |
| 1501 | #endif |
| 1502 | address_item *addr, tls_ext_ctx_cb ** cbp, uschar ** errstr) |
| 1503 | { |
| 1504 | SSL_CTX * ctx; |
| 1505 | long init_options; |
| 1506 | int rc; |
| 1507 | tls_ext_ctx_cb * cbinfo; |
| 1508 | |
| 1509 | cbinfo = store_malloc(sizeof(tls_ext_ctx_cb)); |
| 1510 | cbinfo->certificate = certificate; |
| 1511 | cbinfo->privatekey = privatekey; |
| 1512 | cbinfo->is_server = host==NULL; |
| 1513 | #ifndef DISABLE_OCSP |
| 1514 | cbinfo->verify_stack = NULL; |
| 1515 | if (!host) |
| 1516 | { |
| 1517 | cbinfo->u_ocsp.server.file = ocsp_file; |
| 1518 | cbinfo->u_ocsp.server.file_expanded = NULL; |
| 1519 | cbinfo->u_ocsp.server.response = NULL; |
| 1520 | } |
| 1521 | else |
| 1522 | cbinfo->u_ocsp.client.verify_store = NULL; |
| 1523 | #endif |
| 1524 | cbinfo->dhparam = dhparam; |
| 1525 | cbinfo->server_cipher_list = NULL; |
| 1526 | cbinfo->host = host; |
| 1527 | #ifndef DISABLE_EVENT |
| 1528 | cbinfo->event_action = NULL; |
| 1529 | #endif |
| 1530 | |
| 1531 | SSL_load_error_strings(); /* basic set up */ |
| 1532 | OpenSSL_add_ssl_algorithms(); |
| 1533 | |
| 1534 | #ifdef EXIM_HAVE_SHA256 |
| 1535 | /* SHA256 is becoming ever more popular. This makes sure it gets added to the |
| 1536 | list of available digests. */ |
| 1537 | EVP_add_digest(EVP_sha256()); |
| 1538 | #endif |
| 1539 | |
| 1540 | /* Create a context. |
| 1541 | The OpenSSL docs in 1.0.1b have not been updated to clarify TLS variant |
| 1542 | negotiation in the different methods; as far as I can tell, the only |
| 1543 | *_{server,client}_method which allows negotiation is SSLv23, which exists even |
| 1544 | when OpenSSL is built without SSLv2 support. |
| 1545 | By disabling with openssl_options, we can let admins re-enable with the |
| 1546 | existing knob. */ |
| 1547 | |
| 1548 | if (!(ctx = SSL_CTX_new(host ? SSLv23_client_method() : SSLv23_server_method()))) |
| 1549 | return tls_error(US"SSL_CTX_new", host, NULL, errstr); |
| 1550 | |
| 1551 | /* It turns out that we need to seed the random number generator this early in |
| 1552 | order to get the full complement of ciphers to work. It took me roughly a day |
| 1553 | of work to discover this by experiment. |
| 1554 | |
| 1555 | On systems that have /dev/urandom, SSL may automatically seed itself from |
| 1556 | there. Otherwise, we have to make something up as best we can. Double check |
| 1557 | afterwards. */ |
| 1558 | |
| 1559 | if (!RAND_status()) |
| 1560 | { |
| 1561 | randstuff r; |
| 1562 | gettimeofday(&r.tv, NULL); |
| 1563 | r.p = getpid(); |
| 1564 | |
| 1565 | RAND_seed(US (&r), sizeof(r)); |
| 1566 | RAND_seed(US big_buffer, big_buffer_size); |
| 1567 | if (addr != NULL) RAND_seed(US addr, sizeof(addr)); |
| 1568 | |
| 1569 | if (!RAND_status()) |
| 1570 | return tls_error(US"RAND_status", host, |
| 1571 | US"unable to seed random number generator", errstr); |
| 1572 | } |
| 1573 | |
| 1574 | /* Set up the information callback, which outputs if debugging is at a suitable |
| 1575 | level. */ |
| 1576 | |
| 1577 | DEBUG(D_tls) SSL_CTX_set_info_callback(ctx, (void (*)())info_callback); |
| 1578 | |
| 1579 | /* Automatically re-try reads/writes after renegotiation. */ |
| 1580 | (void) SSL_CTX_set_mode(ctx, SSL_MODE_AUTO_RETRY); |
| 1581 | |
| 1582 | /* Apply administrator-supplied work-arounds. |
| 1583 | Historically we applied just one requested option, |
| 1584 | SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS, but when bug 994 requested a second, we |
| 1585 | moved to an administrator-controlled list of options to specify and |
| 1586 | grandfathered in the first one as the default value for "openssl_options". |
| 1587 | |
| 1588 | No OpenSSL version number checks: the options we accept depend upon the |
| 1589 | availability of the option value macros from OpenSSL. */ |
| 1590 | |
| 1591 | if (!tls_openssl_options_parse(openssl_options, &init_options)) |
| 1592 | return tls_error(US"openssl_options parsing failed", host, NULL, errstr); |
| 1593 | |
| 1594 | if (init_options) |
| 1595 | { |
| 1596 | DEBUG(D_tls) debug_printf("setting SSL CTX options: %#lx\n", init_options); |
| 1597 | if (!(SSL_CTX_set_options(ctx, init_options))) |
| 1598 | return tls_error(string_sprintf( |
| 1599 | "SSL_CTX_set_option(%#lx)", init_options), host, NULL, errstr); |
| 1600 | } |
| 1601 | else |
| 1602 | DEBUG(D_tls) debug_printf("no SSL CTX options to set\n"); |
| 1603 | |
| 1604 | /* Disable session cache unconditionally */ |
| 1605 | |
| 1606 | (void) SSL_CTX_set_session_cache_mode(ctx, SSL_SESS_CACHE_OFF); |
| 1607 | |
| 1608 | /* Initialize with DH parameters if supplied */ |
| 1609 | /* Initialize ECDH temp key parameter selection */ |
| 1610 | |
| 1611 | if ( !init_dh(ctx, dhparam, host, errstr) |
| 1612 | || !init_ecdh(ctx, host, errstr) |
| 1613 | ) |
| 1614 | return DEFER; |
| 1615 | |
| 1616 | /* Set up certificate and key (and perhaps OCSP info) */ |
| 1617 | |
| 1618 | if ((rc = tls_expand_session_files(ctx, cbinfo, errstr)) != OK) |
| 1619 | return rc; |
| 1620 | |
| 1621 | /* If we need to handle SNI or OCSP, do so */ |
| 1622 | |
| 1623 | #ifdef EXIM_HAVE_OPENSSL_TLSEXT |
| 1624 | # ifndef DISABLE_OCSP |
| 1625 | if (!(cbinfo->verify_stack = sk_X509_new_null())) |
| 1626 | { |
| 1627 | DEBUG(D_tls) debug_printf("failed to create stack for stapling verify\n"); |
| 1628 | return FAIL; |
| 1629 | } |
| 1630 | # endif |
| 1631 | |
| 1632 | if (host == NULL) /* server */ |
| 1633 | { |
| 1634 | # ifndef DISABLE_OCSP |
| 1635 | /* We check u_ocsp.server.file, not server.response, because we care about if |
| 1636 | the option exists, not what the current expansion might be, as SNI might |
| 1637 | change the certificate and OCSP file in use between now and the time the |
| 1638 | callback is invoked. */ |
| 1639 | if (cbinfo->u_ocsp.server.file) |
| 1640 | { |
| 1641 | SSL_CTX_set_tlsext_status_cb(ctx, tls_server_stapling_cb); |
| 1642 | SSL_CTX_set_tlsext_status_arg(ctx, cbinfo); |
| 1643 | } |
| 1644 | # endif |
| 1645 | /* We always do this, so that $tls_sni is available even if not used in |
| 1646 | tls_certificate */ |
| 1647 | SSL_CTX_set_tlsext_servername_callback(ctx, tls_servername_cb); |
| 1648 | SSL_CTX_set_tlsext_servername_arg(ctx, cbinfo); |
| 1649 | } |
| 1650 | # ifndef DISABLE_OCSP |
| 1651 | else /* client */ |
| 1652 | if(ocsp_file) /* wanting stapling */ |
| 1653 | { |
| 1654 | if (!(cbinfo->u_ocsp.client.verify_store = X509_STORE_new())) |
| 1655 | { |
| 1656 | DEBUG(D_tls) debug_printf("failed to create store for stapling verify\n"); |
| 1657 | return FAIL; |
| 1658 | } |
| 1659 | SSL_CTX_set_tlsext_status_cb(ctx, tls_client_stapling_cb); |
| 1660 | SSL_CTX_set_tlsext_status_arg(ctx, cbinfo); |
| 1661 | } |
| 1662 | # endif |
| 1663 | #endif |
| 1664 | |
| 1665 | cbinfo->verify_cert_hostnames = NULL; |
| 1666 | |
| 1667 | #ifdef EXIM_HAVE_EPHEM_RSA_KEX |
| 1668 | /* Set up the RSA callback */ |
| 1669 | SSL_CTX_set_tmp_rsa_callback(ctx, rsa_callback); |
| 1670 | #endif |
| 1671 | |
| 1672 | /* Finally, set the timeout, and we are done */ |
| 1673 | |
| 1674 | SSL_CTX_set_timeout(ctx, ssl_session_timeout); |
| 1675 | DEBUG(D_tls) debug_printf("Initialized TLS\n"); |
| 1676 | |
| 1677 | *cbp = cbinfo; |
| 1678 | *ctxp = ctx; |
| 1679 | |
| 1680 | return OK; |
| 1681 | } |
| 1682 | |
| 1683 | |
| 1684 | |
| 1685 | |
| 1686 | /************************************************* |
| 1687 | * Get name of cipher in use * |
| 1688 | *************************************************/ |
| 1689 | |
| 1690 | /* |
| 1691 | Argument: pointer to an SSL structure for the connection |
| 1692 | buffer to use for answer |
| 1693 | size of buffer |
| 1694 | pointer to number of bits for cipher |
| 1695 | Returns: nothing |
| 1696 | */ |
| 1697 | |
| 1698 | static void |
| 1699 | construct_cipher_name(SSL *ssl, uschar *cipherbuf, int bsize, int *bits) |
| 1700 | { |
| 1701 | /* With OpenSSL 1.0.0a, this needs to be const but the documentation doesn't |
| 1702 | yet reflect that. It should be a safe change anyway, even 0.9.8 versions have |
| 1703 | the accessor functions use const in the prototype. */ |
| 1704 | const SSL_CIPHER *c; |
| 1705 | const uschar *ver; |
| 1706 | |
| 1707 | ver = (const uschar *)SSL_get_version(ssl); |
| 1708 | |
| 1709 | c = (const SSL_CIPHER *) SSL_get_current_cipher(ssl); |
| 1710 | SSL_CIPHER_get_bits(c, bits); |
| 1711 | |
| 1712 | string_format(cipherbuf, bsize, "%s:%s:%u", ver, |
| 1713 | SSL_CIPHER_get_name(c), *bits); |
| 1714 | |
| 1715 | DEBUG(D_tls) debug_printf("Cipher: %s\n", cipherbuf); |
| 1716 | } |
| 1717 | |
| 1718 | |
| 1719 | static void |
| 1720 | peer_cert(SSL * ssl, tls_support * tlsp, uschar * peerdn, unsigned bsize) |
| 1721 | { |
| 1722 | /*XXX we might consider a list-of-certs variable for the cert chain. |
| 1723 | SSL_get_peer_cert_chain(SSL*). We'd need a new variable type and support |
| 1724 | in list-handling functions, also consider the difference between the entire |
| 1725 | chain and the elements sent by the peer. */ |
| 1726 | |
| 1727 | /* Will have already noted peercert on a verify fail; possibly not the leaf */ |
| 1728 | if (!tlsp->peercert) |
| 1729 | tlsp->peercert = SSL_get_peer_certificate(ssl); |
| 1730 | /* Beware anonymous ciphers which lead to server_cert being NULL */ |
| 1731 | if (tlsp->peercert) |
| 1732 | { |
| 1733 | X509_NAME_oneline(X509_get_subject_name(tlsp->peercert), CS peerdn, bsize); |
| 1734 | peerdn[bsize-1] = '\0'; |
| 1735 | tlsp->peerdn = peerdn; /*XXX a static buffer... */ |
| 1736 | } |
| 1737 | else |
| 1738 | tlsp->peerdn = NULL; |
| 1739 | } |
| 1740 | |
| 1741 | |
| 1742 | |
| 1743 | |
| 1744 | |
| 1745 | /************************************************* |
| 1746 | * Set up for verifying certificates * |
| 1747 | *************************************************/ |
| 1748 | |
| 1749 | /* Load certs from file, return TRUE on success */ |
| 1750 | |
| 1751 | static BOOL |
| 1752 | chain_from_pem_file(const uschar * file, STACK_OF(X509) * verify_stack) |
| 1753 | { |
| 1754 | BIO * bp; |
| 1755 | X509 * x; |
| 1756 | |
| 1757 | if (!(bp = BIO_new_file(CS file, "r"))) return FALSE; |
| 1758 | while ((x = PEM_read_bio_X509(bp, NULL, 0, NULL))) |
| 1759 | sk_X509_push(verify_stack, x); |
| 1760 | BIO_free(bp); |
| 1761 | return TRUE; |
| 1762 | } |
| 1763 | |
| 1764 | |
| 1765 | |
| 1766 | /* Called by both client and server startup |
| 1767 | |
| 1768 | Arguments: |
| 1769 | sctx SSL_CTX* to initialise |
| 1770 | certs certs file or NULL |
| 1771 | crl CRL file or NULL |
| 1772 | host NULL in a server; the remote host in a client |
| 1773 | optional TRUE if called from a server for a host in tls_try_verify_hosts; |
| 1774 | otherwise passed as FALSE |
| 1775 | cert_vfy_cb Callback function for certificate verification |
| 1776 | errstr error string pointer |
| 1777 | |
| 1778 | Returns: OK/DEFER/FAIL |
| 1779 | */ |
| 1780 | |
| 1781 | static int |
| 1782 | setup_certs(SSL_CTX *sctx, uschar *certs, uschar *crl, host_item *host, BOOL optional, |
| 1783 | int (*cert_vfy_cb)(int, X509_STORE_CTX *), uschar ** errstr) |
| 1784 | { |
| 1785 | uschar *expcerts, *expcrl; |
| 1786 | |
| 1787 | if (!expand_check(certs, US"tls_verify_certificates", &expcerts, errstr)) |
| 1788 | return DEFER; |
| 1789 | DEBUG(D_tls) debug_printf("tls_verify_certificates: %s\n", expcerts); |
| 1790 | |
| 1791 | if (expcerts && *expcerts) |
| 1792 | { |
| 1793 | /* Tell the library to use its compiled-in location for the system default |
| 1794 | CA bundle. Then add the ones specified in the config, if any. */ |
| 1795 | |
| 1796 | if (!SSL_CTX_set_default_verify_paths(sctx)) |
| 1797 | return tls_error(US"SSL_CTX_set_default_verify_paths", host, NULL, errstr); |
| 1798 | |
| 1799 | if (Ustrcmp(expcerts, "system") != 0) |
| 1800 | { |
| 1801 | struct stat statbuf; |
| 1802 | |
| 1803 | if (Ustat(expcerts, &statbuf) < 0) |
| 1804 | { |
| 1805 | log_write(0, LOG_MAIN|LOG_PANIC, |
| 1806 | "failed to stat %s for certificates", expcerts); |
| 1807 | return DEFER; |
| 1808 | } |
| 1809 | else |
| 1810 | { |
| 1811 | uschar *file, *dir; |
| 1812 | if ((statbuf.st_mode & S_IFMT) == S_IFDIR) |
| 1813 | { file = NULL; dir = expcerts; } |
| 1814 | else |
| 1815 | { |
| 1816 | file = expcerts; dir = NULL; |
| 1817 | #ifndef DISABLE_OCSP |
| 1818 | /* In the server if we will be offering an OCSP proof, load chain from |
| 1819 | file for verifying the OCSP proof at load time. */ |
| 1820 | |
| 1821 | if ( !host |
| 1822 | && statbuf.st_size > 0 |
| 1823 | && server_static_cbinfo->u_ocsp.server.file |
| 1824 | && !chain_from_pem_file(file, server_static_cbinfo->verify_stack) |
| 1825 | ) |
| 1826 | { |
| 1827 | log_write(0, LOG_MAIN|LOG_PANIC, |
| 1828 | "failed to load cert chain from %s", file); |
| 1829 | return DEFER; |
| 1830 | } |
| 1831 | #endif |
| 1832 | } |
| 1833 | |
| 1834 | /* If a certificate file is empty, the next function fails with an |
| 1835 | unhelpful error message. If we skip it, we get the correct behaviour (no |
| 1836 | certificates are recognized, but the error message is still misleading (it |
| 1837 | says no certificate was supplied). But this is better. */ |
| 1838 | |
| 1839 | if ( (!file || statbuf.st_size > 0) |
| 1840 | && !SSL_CTX_load_verify_locations(sctx, CS file, CS dir)) |
| 1841 | return tls_error(US"SSL_CTX_load_verify_locations", host, NULL, errstr); |
| 1842 | |
| 1843 | /* Load the list of CAs for which we will accept certs, for sending |
| 1844 | to the client. This is only for the one-file tls_verify_certificates |
| 1845 | variant. |
| 1846 | If a list isn't loaded into the server, but |
| 1847 | some verify locations are set, the server end appears to make |
| 1848 | a wildcard request for client certs. |
| 1849 | Meanwhile, the client library as default behaviour *ignores* the list |
| 1850 | we send over the wire - see man SSL_CTX_set_client_cert_cb. |
| 1851 | Because of this, and that the dir variant is likely only used for |
| 1852 | the public-CA bundle (not for a private CA), not worth fixing. |
| 1853 | */ |
| 1854 | if (file) |
| 1855 | { |
| 1856 | STACK_OF(X509_NAME) * names = SSL_load_client_CA_file(CS file); |
| 1857 | |
| 1858 | DEBUG(D_tls) debug_printf("Added %d certificate authorities.\n", |
| 1859 | sk_X509_NAME_num(names)); |
| 1860 | SSL_CTX_set_client_CA_list(sctx, names); |
| 1861 | } |
| 1862 | } |
| 1863 | } |
| 1864 | |
| 1865 | /* Handle a certificate revocation list. */ |
| 1866 | |
| 1867 | #if OPENSSL_VERSION_NUMBER > 0x00907000L |
| 1868 | |
| 1869 | /* This bit of code is now the version supplied by Lars Mainka. (I have |
| 1870 | merely reformatted it into the Exim code style.) |
| 1871 | |
| 1872 | "From here I changed the code to add support for multiple crl's |
| 1873 | in pem format in one file or to support hashed directory entries in |
| 1874 | pem format instead of a file. This method now uses the library function |
| 1875 | X509_STORE_load_locations to add the CRL location to the SSL context. |
| 1876 | OpenSSL will then handle the verify against CA certs and CRLs by |
| 1877 | itself in the verify callback." */ |
| 1878 | |
| 1879 | if (!expand_check(crl, US"tls_crl", &expcrl, errstr)) return DEFER; |
| 1880 | if (expcrl && *expcrl) |
| 1881 | { |
| 1882 | struct stat statbufcrl; |
| 1883 | if (Ustat(expcrl, &statbufcrl) < 0) |
| 1884 | { |
| 1885 | log_write(0, LOG_MAIN|LOG_PANIC, |
| 1886 | "failed to stat %s for certificates revocation lists", expcrl); |
| 1887 | return DEFER; |
| 1888 | } |
| 1889 | else |
| 1890 | { |
| 1891 | /* is it a file or directory? */ |
| 1892 | uschar *file, *dir; |
| 1893 | X509_STORE *cvstore = SSL_CTX_get_cert_store(sctx); |
| 1894 | if ((statbufcrl.st_mode & S_IFMT) == S_IFDIR) |
| 1895 | { |
| 1896 | file = NULL; |
| 1897 | dir = expcrl; |
| 1898 | DEBUG(D_tls) debug_printf("SSL CRL value is a directory %s\n", dir); |
| 1899 | } |
| 1900 | else |
| 1901 | { |
| 1902 | file = expcrl; |
| 1903 | dir = NULL; |
| 1904 | DEBUG(D_tls) debug_printf("SSL CRL value is a file %s\n", file); |
| 1905 | } |
| 1906 | if (X509_STORE_load_locations(cvstore, CS file, CS dir) == 0) |
| 1907 | return tls_error(US"X509_STORE_load_locations", host, NULL, errstr); |
| 1908 | |
| 1909 | /* setting the flags to check against the complete crl chain */ |
| 1910 | |
| 1911 | X509_STORE_set_flags(cvstore, |
| 1912 | X509_V_FLAG_CRL_CHECK|X509_V_FLAG_CRL_CHECK_ALL); |
| 1913 | } |
| 1914 | } |
| 1915 | |
| 1916 | #endif /* OPENSSL_VERSION_NUMBER > 0x00907000L */ |
| 1917 | |
| 1918 | /* If verification is optional, don't fail if no certificate */ |
| 1919 | |
| 1920 | SSL_CTX_set_verify(sctx, |
| 1921 | SSL_VERIFY_PEER | (optional? 0 : SSL_VERIFY_FAIL_IF_NO_PEER_CERT), |
| 1922 | cert_vfy_cb); |
| 1923 | } |
| 1924 | |
| 1925 | return OK; |
| 1926 | } |
| 1927 | |
| 1928 | |
| 1929 | |
| 1930 | /************************************************* |
| 1931 | * Start a TLS session in a server * |
| 1932 | *************************************************/ |
| 1933 | |
| 1934 | /* This is called when Exim is running as a server, after having received |
| 1935 | the STARTTLS command. It must respond to that command, and then negotiate |
| 1936 | a TLS session. |
| 1937 | |
| 1938 | Arguments: |
| 1939 | require_ciphers allowed ciphers |
| 1940 | errstr pointer to error message |
| 1941 | |
| 1942 | Returns: OK on success |
| 1943 | DEFER for errors before the start of the negotiation |
| 1944 | FAIL for errors during the negotiation; the server can't |
| 1945 | continue running. |
| 1946 | */ |
| 1947 | |
| 1948 | int |
| 1949 | tls_server_start(const uschar * require_ciphers, uschar ** errstr) |
| 1950 | { |
| 1951 | int rc; |
| 1952 | uschar * expciphers; |
| 1953 | tls_ext_ctx_cb * cbinfo; |
| 1954 | static uschar peerdn[256]; |
| 1955 | static uschar cipherbuf[256]; |
| 1956 | |
| 1957 | /* Check for previous activation */ |
| 1958 | |
| 1959 | if (tls_in.active >= 0) |
| 1960 | { |
| 1961 | tls_error(US"STARTTLS received after TLS started", NULL, US"", errstr); |
| 1962 | smtp_printf("554 Already in TLS\r\n", FALSE); |
| 1963 | return FAIL; |
| 1964 | } |
| 1965 | |
| 1966 | /* Initialize the SSL library. If it fails, it will already have logged |
| 1967 | the error. */ |
| 1968 | |
| 1969 | rc = tls_init(&server_ctx, NULL, tls_dhparam, tls_certificate, tls_privatekey, |
| 1970 | #ifndef DISABLE_OCSP |
| 1971 | tls_ocsp_file, /*XXX stack*/ |
| 1972 | #endif |
| 1973 | NULL, &server_static_cbinfo, errstr); |
| 1974 | if (rc != OK) return rc; |
| 1975 | cbinfo = server_static_cbinfo; |
| 1976 | |
| 1977 | if (!expand_check(require_ciphers, US"tls_require_ciphers", &expciphers, errstr)) |
| 1978 | return FAIL; |
| 1979 | |
| 1980 | /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they |
| 1981 | were historically separated by underscores. So that I can use either form in my |
| 1982 | tests, and also for general convenience, we turn underscores into hyphens here. |
| 1983 | */ |
| 1984 | |
| 1985 | if (expciphers) |
| 1986 | { |
| 1987 | uschar * s = expciphers; |
| 1988 | while (*s != 0) { if (*s == '_') *s = '-'; s++; } |
| 1989 | DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers); |
| 1990 | if (!SSL_CTX_set_cipher_list(server_ctx, CS expciphers)) |
| 1991 | return tls_error(US"SSL_CTX_set_cipher_list", NULL, NULL, errstr); |
| 1992 | cbinfo->server_cipher_list = expciphers; |
| 1993 | } |
| 1994 | |
| 1995 | /* If this is a host for which certificate verification is mandatory or |
| 1996 | optional, set up appropriately. */ |
| 1997 | |
| 1998 | tls_in.certificate_verified = FALSE; |
| 1999 | #ifdef SUPPORT_DANE |
| 2000 | tls_in.dane_verified = FALSE; |
| 2001 | #endif |
| 2002 | server_verify_callback_called = FALSE; |
| 2003 | |
| 2004 | if (verify_check_host(&tls_verify_hosts) == OK) |
| 2005 | { |
| 2006 | rc = setup_certs(server_ctx, tls_verify_certificates, tls_crl, NULL, |
| 2007 | FALSE, verify_callback_server, errstr); |
| 2008 | if (rc != OK) return rc; |
| 2009 | server_verify_optional = FALSE; |
| 2010 | } |
| 2011 | else if (verify_check_host(&tls_try_verify_hosts) == OK) |
| 2012 | { |
| 2013 | rc = setup_certs(server_ctx, tls_verify_certificates, tls_crl, NULL, |
| 2014 | TRUE, verify_callback_server, errstr); |
| 2015 | if (rc != OK) return rc; |
| 2016 | server_verify_optional = TRUE; |
| 2017 | } |
| 2018 | |
| 2019 | /* Prepare for new connection */ |
| 2020 | |
| 2021 | if (!(server_ssl = SSL_new(server_ctx))) |
| 2022 | return tls_error(US"SSL_new", NULL, NULL, errstr); |
| 2023 | |
| 2024 | /* Warning: we used to SSL_clear(ssl) here, it was removed. |
| 2025 | * |
| 2026 | * With the SSL_clear(), we get strange interoperability bugs with |
| 2027 | * OpenSSL 1.0.1b and TLS1.1/1.2. It looks as though this may be a bug in |
| 2028 | * OpenSSL itself, as a clear should not lead to inability to follow protocols. |
| 2029 | * |
| 2030 | * The SSL_clear() call is to let an existing SSL* be reused, typically after |
| 2031 | * session shutdown. In this case, we have a brand new object and there's no |
| 2032 | * obvious reason to immediately clear it. I'm guessing that this was |
| 2033 | * originally added because of incomplete initialisation which the clear fixed, |
| 2034 | * in some historic release. |
| 2035 | */ |
| 2036 | |
| 2037 | /* Set context and tell client to go ahead, except in the case of TLS startup |
| 2038 | on connection, where outputting anything now upsets the clients and tends to |
| 2039 | make them disconnect. We need to have an explicit fflush() here, to force out |
| 2040 | the response. Other smtp_printf() calls do not need it, because in non-TLS |
| 2041 | mode, the fflush() happens when smtp_getc() is called. */ |
| 2042 | |
| 2043 | SSL_set_session_id_context(server_ssl, sid_ctx, Ustrlen(sid_ctx)); |
| 2044 | if (!tls_in.on_connect) |
| 2045 | { |
| 2046 | smtp_printf("220 TLS go ahead\r\n", FALSE); |
| 2047 | fflush(smtp_out); |
| 2048 | } |
| 2049 | |
| 2050 | /* Now negotiate the TLS session. We put our own timer on it, since it seems |
| 2051 | that the OpenSSL library doesn't. */ |
| 2052 | |
| 2053 | SSL_set_wfd(server_ssl, fileno(smtp_out)); |
| 2054 | SSL_set_rfd(server_ssl, fileno(smtp_in)); |
| 2055 | SSL_set_accept_state(server_ssl); |
| 2056 | |
| 2057 | DEBUG(D_tls) debug_printf("Calling SSL_accept\n"); |
| 2058 | |
| 2059 | sigalrm_seen = FALSE; |
| 2060 | if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout); |
| 2061 | rc = SSL_accept(server_ssl); |
| 2062 | alarm(0); |
| 2063 | |
| 2064 | if (rc <= 0) |
| 2065 | { |
| 2066 | (void) tls_error(US"SSL_accept", NULL, sigalrm_seen ? US"timed out" : NULL, errstr); |
| 2067 | return FAIL; |
| 2068 | } |
| 2069 | |
| 2070 | DEBUG(D_tls) debug_printf("SSL_accept was successful\n"); |
| 2071 | |
| 2072 | /* TLS has been set up. Adjust the input functions to read via TLS, |
| 2073 | and initialize things. */ |
| 2074 | |
| 2075 | peer_cert(server_ssl, &tls_in, peerdn, sizeof(peerdn)); |
| 2076 | |
| 2077 | construct_cipher_name(server_ssl, cipherbuf, sizeof(cipherbuf), &tls_in.bits); |
| 2078 | tls_in.cipher = cipherbuf; |
| 2079 | |
| 2080 | DEBUG(D_tls) |
| 2081 | { |
| 2082 | uschar buf[2048]; |
| 2083 | if (SSL_get_shared_ciphers(server_ssl, CS buf, sizeof(buf)) != NULL) |
| 2084 | debug_printf("Shared ciphers: %s\n", buf); |
| 2085 | } |
| 2086 | |
| 2087 | /* Record the certificate we presented */ |
| 2088 | { |
| 2089 | X509 * crt = SSL_get_certificate(server_ssl); |
| 2090 | tls_in.ourcert = crt ? X509_dup(crt) : NULL; |
| 2091 | } |
| 2092 | |
| 2093 | /* Only used by the server-side tls (tls_in), including tls_getc. |
| 2094 | Client-side (tls_out) reads (seem to?) go via |
| 2095 | smtp_read_response()/ip_recv(). |
| 2096 | Hence no need to duplicate for _in and _out. |
| 2097 | */ |
| 2098 | ssl_xfer_buffer = store_malloc(ssl_xfer_buffer_size); |
| 2099 | ssl_xfer_buffer_lwm = ssl_xfer_buffer_hwm = 0; |
| 2100 | ssl_xfer_eof = ssl_xfer_error = 0; |
| 2101 | |
| 2102 | receive_getc = tls_getc; |
| 2103 | receive_getbuf = tls_getbuf; |
| 2104 | receive_get_cache = tls_get_cache; |
| 2105 | receive_ungetc = tls_ungetc; |
| 2106 | receive_feof = tls_feof; |
| 2107 | receive_ferror = tls_ferror; |
| 2108 | receive_smtp_buffered = tls_smtp_buffered; |
| 2109 | |
| 2110 | tls_in.active = fileno(smtp_out); |
| 2111 | return OK; |
| 2112 | } |
| 2113 | |
| 2114 | |
| 2115 | |
| 2116 | |
| 2117 | static int |
| 2118 | tls_client_basic_ctx_init(SSL_CTX * ctx, |
| 2119 | host_item * host, smtp_transport_options_block * ob, tls_ext_ctx_cb * cbinfo, |
| 2120 | uschar ** errstr) |
| 2121 | { |
| 2122 | int rc; |
| 2123 | /* stick to the old behaviour for compatibility if tls_verify_certificates is |
| 2124 | set but both tls_verify_hosts and tls_try_verify_hosts is not set. Check only |
| 2125 | the specified host patterns if one of them is defined */ |
| 2126 | |
| 2127 | if ( ( !ob->tls_verify_hosts |
| 2128 | && (!ob->tls_try_verify_hosts || !*ob->tls_try_verify_hosts) |
| 2129 | ) |
| 2130 | || (verify_check_given_host(&ob->tls_verify_hosts, host) == OK) |
| 2131 | ) |
| 2132 | client_verify_optional = FALSE; |
| 2133 | else if (verify_check_given_host(&ob->tls_try_verify_hosts, host) == OK) |
| 2134 | client_verify_optional = TRUE; |
| 2135 | else |
| 2136 | return OK; |
| 2137 | |
| 2138 | if ((rc = setup_certs(ctx, ob->tls_verify_certificates, |
| 2139 | ob->tls_crl, host, client_verify_optional, verify_callback_client, |
| 2140 | errstr)) != OK) |
| 2141 | return rc; |
| 2142 | |
| 2143 | if (verify_check_given_host(&ob->tls_verify_cert_hostnames, host) == OK) |
| 2144 | { |
| 2145 | cbinfo->verify_cert_hostnames = |
| 2146 | #ifdef SUPPORT_I18N |
| 2147 | string_domain_utf8_to_alabel(host->name, NULL); |
| 2148 | #else |
| 2149 | host->name; |
| 2150 | #endif |
| 2151 | DEBUG(D_tls) debug_printf("Cert hostname to check: \"%s\"\n", |
| 2152 | cbinfo->verify_cert_hostnames); |
| 2153 | } |
| 2154 | return OK; |
| 2155 | } |
| 2156 | |
| 2157 | |
| 2158 | #ifdef SUPPORT_DANE |
| 2159 | static int |
| 2160 | dane_tlsa_load(SSL * ssl, host_item * host, dns_answer * dnsa, uschar ** errstr) |
| 2161 | { |
| 2162 | dns_record * rr; |
| 2163 | dns_scan dnss; |
| 2164 | const char * hostnames[2] = { CS host->name, NULL }; |
| 2165 | int found = 0; |
| 2166 | |
| 2167 | if (DANESSL_init(ssl, NULL, hostnames) != 1) |
| 2168 | return tls_error(US"hostnames load", host, NULL, errstr); |
| 2169 | |
| 2170 | for (rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS); |
| 2171 | rr; |
| 2172 | rr = dns_next_rr(dnsa, &dnss, RESET_NEXT) |
| 2173 | ) if (rr->type == T_TLSA) |
| 2174 | { |
| 2175 | const uschar * p = rr->data; |
| 2176 | uint8_t usage, selector, mtype; |
| 2177 | const char * mdname; |
| 2178 | |
| 2179 | usage = *p++; |
| 2180 | |
| 2181 | /* Only DANE-TA(2) and DANE-EE(3) are supported */ |
| 2182 | if (usage != 2 && usage != 3) continue; |
| 2183 | |
| 2184 | selector = *p++; |
| 2185 | mtype = *p++; |
| 2186 | |
| 2187 | switch (mtype) |
| 2188 | { |
| 2189 | default: continue; /* Only match-types 0, 1, 2 are supported */ |
| 2190 | case 0: mdname = NULL; break; |
| 2191 | case 1: mdname = "sha256"; break; |
| 2192 | case 2: mdname = "sha512"; break; |
| 2193 | } |
| 2194 | |
| 2195 | found++; |
| 2196 | switch (DANESSL_add_tlsa(ssl, usage, selector, mdname, p, rr->size - 3)) |
| 2197 | { |
| 2198 | default: |
| 2199 | return tls_error(US"tlsa load", host, NULL, errstr); |
| 2200 | case 0: /* action not taken */ |
| 2201 | case 1: break; |
| 2202 | } |
| 2203 | |
| 2204 | tls_out.tlsa_usage |= 1<<usage; |
| 2205 | } |
| 2206 | |
| 2207 | if (found) |
| 2208 | return OK; |
| 2209 | |
| 2210 | log_write(0, LOG_MAIN, "DANE error: No usable TLSA records"); |
| 2211 | return DEFER; |
| 2212 | } |
| 2213 | #endif /*SUPPORT_DANE*/ |
| 2214 | |
| 2215 | |
| 2216 | |
| 2217 | /************************************************* |
| 2218 | * Start a TLS session in a client * |
| 2219 | *************************************************/ |
| 2220 | |
| 2221 | /* Called from the smtp transport after STARTTLS has been accepted. |
| 2222 | |
| 2223 | Argument: |
| 2224 | fd the fd of the connection |
| 2225 | host connected host (for messages) |
| 2226 | addr the first address |
| 2227 | tb transport (always smtp) |
| 2228 | tlsa_dnsa tlsa lookup, if DANE, else null |
| 2229 | errstr error string pointer |
| 2230 | |
| 2231 | Returns: OK on success |
| 2232 | FAIL otherwise - note that tls_error() will not give DEFER |
| 2233 | because this is not a server |
| 2234 | */ |
| 2235 | |
| 2236 | int |
| 2237 | tls_client_start(int fd, host_item *host, address_item *addr, |
| 2238 | transport_instance * tb, |
| 2239 | #ifdef SUPPORT_DANE |
| 2240 | dns_answer * tlsa_dnsa, |
| 2241 | #endif |
| 2242 | uschar ** errstr) |
| 2243 | { |
| 2244 | smtp_transport_options_block * ob = |
| 2245 | (smtp_transport_options_block *)tb->options_block; |
| 2246 | static uschar peerdn[256]; |
| 2247 | uschar * expciphers; |
| 2248 | int rc; |
| 2249 | static uschar cipherbuf[256]; |
| 2250 | |
| 2251 | #ifndef DISABLE_OCSP |
| 2252 | BOOL request_ocsp = FALSE; |
| 2253 | BOOL require_ocsp = FALSE; |
| 2254 | #endif |
| 2255 | |
| 2256 | #ifdef SUPPORT_DANE |
| 2257 | tls_out.tlsa_usage = 0; |
| 2258 | #endif |
| 2259 | |
| 2260 | #ifndef DISABLE_OCSP |
| 2261 | { |
| 2262 | # ifdef SUPPORT_DANE |
| 2263 | if ( tlsa_dnsa |
| 2264 | && ob->hosts_request_ocsp[0] == '*' |
| 2265 | && ob->hosts_request_ocsp[1] == '\0' |
| 2266 | ) |
| 2267 | { |
| 2268 | /* Unchanged from default. Use a safer one under DANE */ |
| 2269 | request_ocsp = TRUE; |
| 2270 | ob->hosts_request_ocsp = US"${if or { {= {0}{$tls_out_tlsa_usage}} " |
| 2271 | " {= {4}{$tls_out_tlsa_usage}} } " |
| 2272 | " {*}{}}"; |
| 2273 | } |
| 2274 | # endif |
| 2275 | |
| 2276 | if ((require_ocsp = |
| 2277 | verify_check_given_host(&ob->hosts_require_ocsp, host) == OK)) |
| 2278 | request_ocsp = TRUE; |
| 2279 | else |
| 2280 | # ifdef SUPPORT_DANE |
| 2281 | if (!request_ocsp) |
| 2282 | # endif |
| 2283 | request_ocsp = |
| 2284 | verify_check_given_host(&ob->hosts_request_ocsp, host) == OK; |
| 2285 | } |
| 2286 | #endif |
| 2287 | |
| 2288 | rc = tls_init(&client_ctx, host, NULL, |
| 2289 | ob->tls_certificate, ob->tls_privatekey, |
| 2290 | #ifndef DISABLE_OCSP |
| 2291 | (void *)(long)request_ocsp, |
| 2292 | #endif |
| 2293 | addr, &client_static_cbinfo, errstr); |
| 2294 | if (rc != OK) return rc; |
| 2295 | |
| 2296 | tls_out.certificate_verified = FALSE; |
| 2297 | client_verify_callback_called = FALSE; |
| 2298 | |
| 2299 | if (!expand_check(ob->tls_require_ciphers, US"tls_require_ciphers", |
| 2300 | &expciphers, errstr)) |
| 2301 | return FAIL; |
| 2302 | |
| 2303 | /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they |
| 2304 | are separated by underscores. So that I can use either form in my tests, and |
| 2305 | also for general convenience, we turn underscores into hyphens here. */ |
| 2306 | |
| 2307 | if (expciphers) |
| 2308 | { |
| 2309 | uschar *s = expciphers; |
| 2310 | while (*s) { if (*s == '_') *s = '-'; s++; } |
| 2311 | DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers); |
| 2312 | if (!SSL_CTX_set_cipher_list(client_ctx, CS expciphers)) |
| 2313 | return tls_error(US"SSL_CTX_set_cipher_list", host, NULL, errstr); |
| 2314 | } |
| 2315 | |
| 2316 | #ifdef SUPPORT_DANE |
| 2317 | if (tlsa_dnsa) |
| 2318 | { |
| 2319 | SSL_CTX_set_verify(client_ctx, |
| 2320 | SSL_VERIFY_PEER | SSL_VERIFY_FAIL_IF_NO_PEER_CERT, |
| 2321 | verify_callback_client_dane); |
| 2322 | |
| 2323 | if (!DANESSL_library_init()) |
| 2324 | return tls_error(US"library init", host, NULL, errstr); |
| 2325 | if (DANESSL_CTX_init(client_ctx) <= 0) |
| 2326 | return tls_error(US"context init", host, NULL, errstr); |
| 2327 | } |
| 2328 | else |
| 2329 | |
| 2330 | #endif |
| 2331 | |
| 2332 | if ((rc = tls_client_basic_ctx_init(client_ctx, host, ob, |
| 2333 | client_static_cbinfo, errstr)) != OK) |
| 2334 | return rc; |
| 2335 | |
| 2336 | if ((client_ssl = SSL_new(client_ctx)) == NULL) |
| 2337 | return tls_error(US"SSL_new", host, NULL, errstr); |
| 2338 | SSL_set_session_id_context(client_ssl, sid_ctx, Ustrlen(sid_ctx)); |
| 2339 | SSL_set_fd(client_ssl, fd); |
| 2340 | SSL_set_connect_state(client_ssl); |
| 2341 | |
| 2342 | if (ob->tls_sni) |
| 2343 | { |
| 2344 | if (!expand_check(ob->tls_sni, US"tls_sni", &tls_out.sni, errstr)) |
| 2345 | return FAIL; |
| 2346 | if (!tls_out.sni) |
| 2347 | { |
| 2348 | DEBUG(D_tls) debug_printf("Setting TLS SNI forced to fail, not sending\n"); |
| 2349 | } |
| 2350 | else if (!Ustrlen(tls_out.sni)) |
| 2351 | tls_out.sni = NULL; |
| 2352 | else |
| 2353 | { |
| 2354 | #ifdef EXIM_HAVE_OPENSSL_TLSEXT |
| 2355 | DEBUG(D_tls) debug_printf("Setting TLS SNI \"%s\"\n", tls_out.sni); |
| 2356 | SSL_set_tlsext_host_name(client_ssl, tls_out.sni); |
| 2357 | #else |
| 2358 | log_write(0, LOG_MAIN, "SNI unusable with this OpenSSL library version; ignoring \"%s\"\n", |
| 2359 | tls_out.sni); |
| 2360 | #endif |
| 2361 | } |
| 2362 | } |
| 2363 | |
| 2364 | #ifdef SUPPORT_DANE |
| 2365 | if (tlsa_dnsa) |
| 2366 | if ((rc = dane_tlsa_load(client_ssl, host, tlsa_dnsa, errstr)) != OK) |
| 2367 | return rc; |
| 2368 | #endif |
| 2369 | |
| 2370 | #ifndef DISABLE_OCSP |
| 2371 | /* Request certificate status at connection-time. If the server |
| 2372 | does OCSP stapling we will get the callback (set in tls_init()) */ |
| 2373 | # ifdef SUPPORT_DANE |
| 2374 | if (request_ocsp) |
| 2375 | { |
| 2376 | const uschar * s; |
| 2377 | if ( ((s = ob->hosts_require_ocsp) && Ustrstr(s, US"tls_out_tlsa_usage")) |
| 2378 | || ((s = ob->hosts_request_ocsp) && Ustrstr(s, US"tls_out_tlsa_usage")) |
| 2379 | ) |
| 2380 | { /* Re-eval now $tls_out_tlsa_usage is populated. If |
| 2381 | this means we avoid the OCSP request, we wasted the setup |
| 2382 | cost in tls_init(). */ |
| 2383 | require_ocsp = verify_check_given_host(&ob->hosts_require_ocsp, host) == OK; |
| 2384 | request_ocsp = require_ocsp |
| 2385 | || verify_check_given_host(&ob->hosts_request_ocsp, host) == OK; |
| 2386 | } |
| 2387 | } |
| 2388 | # endif |
| 2389 | |
| 2390 | if (request_ocsp) |
| 2391 | { |
| 2392 | SSL_set_tlsext_status_type(client_ssl, TLSEXT_STATUSTYPE_ocsp); |
| 2393 | client_static_cbinfo->u_ocsp.client.verify_required = require_ocsp; |
| 2394 | tls_out.ocsp = OCSP_NOT_RESP; |
| 2395 | } |
| 2396 | #endif |
| 2397 | |
| 2398 | #ifndef DISABLE_EVENT |
| 2399 | client_static_cbinfo->event_action = tb->event_action; |
| 2400 | #endif |
| 2401 | |
| 2402 | /* There doesn't seem to be a built-in timeout on connection. */ |
| 2403 | |
| 2404 | DEBUG(D_tls) debug_printf("Calling SSL_connect\n"); |
| 2405 | sigalrm_seen = FALSE; |
| 2406 | alarm(ob->command_timeout); |
| 2407 | rc = SSL_connect(client_ssl); |
| 2408 | alarm(0); |
| 2409 | |
| 2410 | #ifdef SUPPORT_DANE |
| 2411 | if (tlsa_dnsa) |
| 2412 | DANESSL_cleanup(client_ssl); |
| 2413 | #endif |
| 2414 | |
| 2415 | if (rc <= 0) |
| 2416 | return tls_error(US"SSL_connect", host, sigalrm_seen ? US"timed out" : NULL, |
| 2417 | errstr); |
| 2418 | |
| 2419 | DEBUG(D_tls) debug_printf("SSL_connect succeeded\n"); |
| 2420 | |
| 2421 | peer_cert(client_ssl, &tls_out, peerdn, sizeof(peerdn)); |
| 2422 | |
| 2423 | construct_cipher_name(client_ssl, cipherbuf, sizeof(cipherbuf), &tls_out.bits); |
| 2424 | tls_out.cipher = cipherbuf; |
| 2425 | |
| 2426 | /* Record the certificate we presented */ |
| 2427 | { |
| 2428 | X509 * crt = SSL_get_certificate(client_ssl); |
| 2429 | tls_out.ourcert = crt ? X509_dup(crt) : NULL; |
| 2430 | } |
| 2431 | |
| 2432 | tls_out.active = fd; |
| 2433 | return OK; |
| 2434 | } |
| 2435 | |
| 2436 | |
| 2437 | |
| 2438 | |
| 2439 | |
| 2440 | static BOOL |
| 2441 | tls_refill(unsigned lim) |
| 2442 | { |
| 2443 | int error; |
| 2444 | int inbytes; |
| 2445 | |
| 2446 | DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", server_ssl, |
| 2447 | ssl_xfer_buffer, ssl_xfer_buffer_size); |
| 2448 | |
| 2449 | if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout); |
| 2450 | inbytes = SSL_read(server_ssl, CS ssl_xfer_buffer, |
| 2451 | MIN(ssl_xfer_buffer_size, lim)); |
| 2452 | error = SSL_get_error(server_ssl, inbytes); |
| 2453 | alarm(0); |
| 2454 | |
| 2455 | /* SSL_ERROR_ZERO_RETURN appears to mean that the SSL session has been |
| 2456 | closed down, not that the socket itself has been closed down. Revert to |
| 2457 | non-SSL handling. */ |
| 2458 | |
| 2459 | if (error == SSL_ERROR_ZERO_RETURN) |
| 2460 | { |
| 2461 | DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n"); |
| 2462 | |
| 2463 | receive_getc = smtp_getc; |
| 2464 | receive_getbuf = smtp_getbuf; |
| 2465 | receive_get_cache = smtp_get_cache; |
| 2466 | receive_ungetc = smtp_ungetc; |
| 2467 | receive_feof = smtp_feof; |
| 2468 | receive_ferror = smtp_ferror; |
| 2469 | receive_smtp_buffered = smtp_buffered; |
| 2470 | |
| 2471 | SSL_free(server_ssl); |
| 2472 | server_ssl = NULL; |
| 2473 | tls_in.active = -1; |
| 2474 | tls_in.bits = 0; |
| 2475 | tls_in.cipher = NULL; |
| 2476 | tls_in.peerdn = NULL; |
| 2477 | tls_in.sni = NULL; |
| 2478 | |
| 2479 | return FALSE; |
| 2480 | } |
| 2481 | |
| 2482 | /* Handle genuine errors */ |
| 2483 | |
| 2484 | else if (error == SSL_ERROR_SSL) |
| 2485 | { |
| 2486 | ERR_error_string(ERR_get_error(), ssl_errstring); |
| 2487 | log_write(0, LOG_MAIN, "TLS error (SSL_read): %s", ssl_errstring); |
| 2488 | ssl_xfer_error = 1; |
| 2489 | return FALSE; |
| 2490 | } |
| 2491 | |
| 2492 | else if (error != SSL_ERROR_NONE) |
| 2493 | { |
| 2494 | DEBUG(D_tls) debug_printf("Got SSL error %d\n", error); |
| 2495 | ssl_xfer_error = 1; |
| 2496 | return FALSE; |
| 2497 | } |
| 2498 | |
| 2499 | #ifndef DISABLE_DKIM |
| 2500 | dkim_exim_verify_feed(ssl_xfer_buffer, inbytes); |
| 2501 | #endif |
| 2502 | ssl_xfer_buffer_hwm = inbytes; |
| 2503 | ssl_xfer_buffer_lwm = 0; |
| 2504 | return TRUE; |
| 2505 | } |
| 2506 | |
| 2507 | |
| 2508 | /************************************************* |
| 2509 | * TLS version of getc * |
| 2510 | *************************************************/ |
| 2511 | |
| 2512 | /* This gets the next byte from the TLS input buffer. If the buffer is empty, |
| 2513 | it refills the buffer via the SSL reading function. |
| 2514 | |
| 2515 | Arguments: lim Maximum amount to read/buffer |
| 2516 | Returns: the next character or EOF |
| 2517 | |
| 2518 | Only used by the server-side TLS. |
| 2519 | */ |
| 2520 | |
| 2521 | int |
| 2522 | tls_getc(unsigned lim) |
| 2523 | { |
| 2524 | if (ssl_xfer_buffer_lwm >= ssl_xfer_buffer_hwm) |
| 2525 | if (!tls_refill(lim)) |
| 2526 | return ssl_xfer_error ? EOF : smtp_getc(lim); |
| 2527 | |
| 2528 | /* Something in the buffer; return next uschar */ |
| 2529 | |
| 2530 | return ssl_xfer_buffer[ssl_xfer_buffer_lwm++]; |
| 2531 | } |
| 2532 | |
| 2533 | uschar * |
| 2534 | tls_getbuf(unsigned * len) |
| 2535 | { |
| 2536 | unsigned size; |
| 2537 | uschar * buf; |
| 2538 | |
| 2539 | if (ssl_xfer_buffer_lwm >= ssl_xfer_buffer_hwm) |
| 2540 | if (!tls_refill(*len)) |
| 2541 | { |
| 2542 | if (!ssl_xfer_error) return smtp_getbuf(len); |
| 2543 | *len = 0; |
| 2544 | return NULL; |
| 2545 | } |
| 2546 | |
| 2547 | if ((size = ssl_xfer_buffer_hwm - ssl_xfer_buffer_lwm) > *len) |
| 2548 | size = *len; |
| 2549 | buf = &ssl_xfer_buffer[ssl_xfer_buffer_lwm]; |
| 2550 | ssl_xfer_buffer_lwm += size; |
| 2551 | *len = size; |
| 2552 | return buf; |
| 2553 | } |
| 2554 | |
| 2555 | |
| 2556 | void |
| 2557 | tls_get_cache() |
| 2558 | { |
| 2559 | #ifndef DISABLE_DKIM |
| 2560 | int n = ssl_xfer_buffer_hwm - ssl_xfer_buffer_lwm; |
| 2561 | if (n > 0) |
| 2562 | dkim_exim_verify_feed(ssl_xfer_buffer+ssl_xfer_buffer_lwm, n); |
| 2563 | #endif |
| 2564 | } |
| 2565 | |
| 2566 | |
| 2567 | BOOL |
| 2568 | tls_could_read(void) |
| 2569 | { |
| 2570 | return ssl_xfer_buffer_lwm < ssl_xfer_buffer_hwm || SSL_pending(server_ssl) > 0; |
| 2571 | } |
| 2572 | |
| 2573 | |
| 2574 | /************************************************* |
| 2575 | * Read bytes from TLS channel * |
| 2576 | *************************************************/ |
| 2577 | |
| 2578 | /* |
| 2579 | Arguments: |
| 2580 | buff buffer of data |
| 2581 | len size of buffer |
| 2582 | |
| 2583 | Returns: the number of bytes read |
| 2584 | -1 after a failed read |
| 2585 | |
| 2586 | Only used by the client-side TLS. |
| 2587 | */ |
| 2588 | |
| 2589 | int |
| 2590 | tls_read(BOOL is_server, uschar *buff, size_t len) |
| 2591 | { |
| 2592 | SSL *ssl = is_server ? server_ssl : client_ssl; |
| 2593 | int inbytes; |
| 2594 | int error; |
| 2595 | |
| 2596 | DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", ssl, |
| 2597 | buff, (unsigned int)len); |
| 2598 | |
| 2599 | inbytes = SSL_read(ssl, CS buff, len); |
| 2600 | error = SSL_get_error(ssl, inbytes); |
| 2601 | |
| 2602 | if (error == SSL_ERROR_ZERO_RETURN) |
| 2603 | { |
| 2604 | DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n"); |
| 2605 | return -1; |
| 2606 | } |
| 2607 | else if (error != SSL_ERROR_NONE) |
| 2608 | return -1; |
| 2609 | |
| 2610 | return inbytes; |
| 2611 | } |
| 2612 | |
| 2613 | |
| 2614 | |
| 2615 | |
| 2616 | |
| 2617 | /************************************************* |
| 2618 | * Write bytes down TLS channel * |
| 2619 | *************************************************/ |
| 2620 | |
| 2621 | /* |
| 2622 | Arguments: |
| 2623 | is_server channel specifier |
| 2624 | buff buffer of data |
| 2625 | len number of bytes |
| 2626 | more further data expected soon |
| 2627 | |
| 2628 | Returns: the number of bytes after a successful write, |
| 2629 | -1 after a failed write |
| 2630 | |
| 2631 | Used by both server-side and client-side TLS. |
| 2632 | */ |
| 2633 | |
| 2634 | int |
| 2635 | tls_write(BOOL is_server, const uschar *buff, size_t len, BOOL more) |
| 2636 | { |
| 2637 | int outbytes, error, left; |
| 2638 | SSL *ssl = is_server ? server_ssl : client_ssl; |
| 2639 | static gstring * corked = NULL; |
| 2640 | |
| 2641 | DEBUG(D_tls) debug_printf("%s(%p, %lu%s)\n", __FUNCTION__, |
| 2642 | buff, (unsigned long)len, more ? ", more" : ""); |
| 2643 | |
| 2644 | /* Lacking a CORK or MSG_MORE facility (such as GnuTLS has) we copy data when |
| 2645 | "more" is notified. This hack is only ok if small amounts are involved AND only |
| 2646 | one stream does it, in one context (i.e. no store reset). Currently it is used |
| 2647 | for the responses to the received SMTP MAIL , RCPT, DATA sequence, only. */ |
| 2648 | |
| 2649 | if (is_server && (more || corked)) |
| 2650 | { |
| 2651 | corked = string_catn(corked, buff, len); |
| 2652 | if (more) |
| 2653 | return len; |
| 2654 | buff = CUS corked->s; |
| 2655 | len = corked->ptr; |
| 2656 | corked = NULL; |
| 2657 | } |
| 2658 | |
| 2659 | for (left = len; left > 0;) |
| 2660 | { |
| 2661 | DEBUG(D_tls) debug_printf("SSL_write(SSL, %p, %d)\n", buff, left); |
| 2662 | outbytes = SSL_write(ssl, CS buff, left); |
| 2663 | error = SSL_get_error(ssl, outbytes); |
| 2664 | DEBUG(D_tls) debug_printf("outbytes=%d error=%d\n", outbytes, error); |
| 2665 | switch (error) |
| 2666 | { |
| 2667 | case SSL_ERROR_SSL: |
| 2668 | ERR_error_string(ERR_get_error(), ssl_errstring); |
| 2669 | log_write(0, LOG_MAIN, "TLS error (SSL_write): %s", ssl_errstring); |
| 2670 | return -1; |
| 2671 | |
| 2672 | case SSL_ERROR_NONE: |
| 2673 | left -= outbytes; |
| 2674 | buff += outbytes; |
| 2675 | break; |
| 2676 | |
| 2677 | case SSL_ERROR_ZERO_RETURN: |
| 2678 | log_write(0, LOG_MAIN, "SSL channel closed on write"); |
| 2679 | return -1; |
| 2680 | |
| 2681 | case SSL_ERROR_SYSCALL: |
| 2682 | log_write(0, LOG_MAIN, "SSL_write: (from %s) syscall: %s", |
| 2683 | sender_fullhost ? sender_fullhost : US"<unknown>", |
| 2684 | strerror(errno)); |
| 2685 | return -1; |
| 2686 | |
| 2687 | default: |
| 2688 | log_write(0, LOG_MAIN, "SSL_write error %d", error); |
| 2689 | return -1; |
| 2690 | } |
| 2691 | } |
| 2692 | return len; |
| 2693 | } |
| 2694 | |
| 2695 | |
| 2696 | |
| 2697 | /************************************************* |
| 2698 | * Close down a TLS session * |
| 2699 | *************************************************/ |
| 2700 | |
| 2701 | /* This is also called from within a delivery subprocess forked from the |
| 2702 | daemon, to shut down the TLS library, without actually doing a shutdown (which |
| 2703 | would tamper with the SSL session in the parent process). |
| 2704 | |
| 2705 | Arguments: TRUE if SSL_shutdown is to be called |
| 2706 | Returns: nothing |
| 2707 | |
| 2708 | Used by both server-side and client-side TLS. |
| 2709 | */ |
| 2710 | |
| 2711 | void |
| 2712 | tls_close(BOOL is_server, BOOL shutdown) |
| 2713 | { |
| 2714 | SSL **sslp = is_server ? &server_ssl : &client_ssl; |
| 2715 | int *fdp = is_server ? &tls_in.active : &tls_out.active; |
| 2716 | |
| 2717 | if (*fdp < 0) return; /* TLS was not active */ |
| 2718 | |
| 2719 | if (shutdown) |
| 2720 | { |
| 2721 | DEBUG(D_tls) debug_printf("tls_close(): shutting down SSL\n"); |
| 2722 | SSL_shutdown(*sslp); |
| 2723 | } |
| 2724 | |
| 2725 | SSL_free(*sslp); |
| 2726 | *sslp = NULL; |
| 2727 | |
| 2728 | *fdp = -1; |
| 2729 | } |
| 2730 | |
| 2731 | |
| 2732 | |
| 2733 | |
| 2734 | /************************************************* |
| 2735 | * Let tls_require_ciphers be checked at startup * |
| 2736 | *************************************************/ |
| 2737 | |
| 2738 | /* The tls_require_ciphers option, if set, must be something which the |
| 2739 | library can parse. |
| 2740 | |
| 2741 | Returns: NULL on success, or error message |
| 2742 | */ |
| 2743 | |
| 2744 | uschar * |
| 2745 | tls_validate_require_cipher(void) |
| 2746 | { |
| 2747 | SSL_CTX *ctx; |
| 2748 | uschar *s, *expciphers, *err; |
| 2749 | |
| 2750 | /* this duplicates from tls_init(), we need a better "init just global |
| 2751 | state, for no specific purpose" singleton function of our own */ |
| 2752 | |
| 2753 | SSL_load_error_strings(); |
| 2754 | OpenSSL_add_ssl_algorithms(); |
| 2755 | #if (OPENSSL_VERSION_NUMBER >= 0x0090800fL) && !defined(OPENSSL_NO_SHA256) |
| 2756 | /* SHA256 is becoming ever more popular. This makes sure it gets added to the |
| 2757 | list of available digests. */ |
| 2758 | EVP_add_digest(EVP_sha256()); |
| 2759 | #endif |
| 2760 | |
| 2761 | if (!(tls_require_ciphers && *tls_require_ciphers)) |
| 2762 | return NULL; |
| 2763 | |
| 2764 | if (!expand_check(tls_require_ciphers, US"tls_require_ciphers", &expciphers, |
| 2765 | &err)) |
| 2766 | return US"failed to expand tls_require_ciphers"; |
| 2767 | |
| 2768 | if (!(expciphers && *expciphers)) |
| 2769 | return NULL; |
| 2770 | |
| 2771 | /* normalisation ripped from above */ |
| 2772 | s = expciphers; |
| 2773 | while (*s != 0) { if (*s == '_') *s = '-'; s++; } |
| 2774 | |
| 2775 | err = NULL; |
| 2776 | |
| 2777 | ctx = SSL_CTX_new(SSLv23_server_method()); |
| 2778 | if (!ctx) |
| 2779 | { |
| 2780 | ERR_error_string(ERR_get_error(), ssl_errstring); |
| 2781 | return string_sprintf("SSL_CTX_new() failed: %s", ssl_errstring); |
| 2782 | } |
| 2783 | |
| 2784 | DEBUG(D_tls) |
| 2785 | debug_printf("tls_require_ciphers expands to \"%s\"\n", expciphers); |
| 2786 | |
| 2787 | if (!SSL_CTX_set_cipher_list(ctx, CS expciphers)) |
| 2788 | { |
| 2789 | ERR_error_string(ERR_get_error(), ssl_errstring); |
| 2790 | err = string_sprintf("SSL_CTX_set_cipher_list(%s) failed: %s", |
| 2791 | expciphers, ssl_errstring); |
| 2792 | } |
| 2793 | |
| 2794 | SSL_CTX_free(ctx); |
| 2795 | |
| 2796 | return err; |
| 2797 | } |
| 2798 | |
| 2799 | |
| 2800 | |
| 2801 | |
| 2802 | /************************************************* |
| 2803 | * Report the library versions. * |
| 2804 | *************************************************/ |
| 2805 | |
| 2806 | /* There have historically been some issues with binary compatibility in |
| 2807 | OpenSSL libraries; if Exim (like many other applications) is built against |
| 2808 | one version of OpenSSL but the run-time linker picks up another version, |
| 2809 | it can result in serious failures, including crashing with a SIGSEGV. So |
| 2810 | report the version found by the compiler and the run-time version. |
| 2811 | |
| 2812 | Note: some OS vendors backport security fixes without changing the version |
| 2813 | number/string, and the version date remains unchanged. The _build_ date |
| 2814 | will change, so we can more usefully assist with version diagnosis by also |
| 2815 | reporting the build date. |
| 2816 | |
| 2817 | Arguments: a FILE* to print the results to |
| 2818 | Returns: nothing |
| 2819 | */ |
| 2820 | |
| 2821 | void |
| 2822 | tls_version_report(FILE *f) |
| 2823 | { |
| 2824 | fprintf(f, "Library version: OpenSSL: Compile: %s\n" |
| 2825 | " Runtime: %s\n" |
| 2826 | " : %s\n", |
| 2827 | OPENSSL_VERSION_TEXT, |
| 2828 | SSLeay_version(SSLEAY_VERSION), |
| 2829 | SSLeay_version(SSLEAY_BUILT_ON)); |
| 2830 | /* third line is 38 characters for the %s and the line is 73 chars long; |
| 2831 | the OpenSSL output includes a "built on: " prefix already. */ |
| 2832 | } |
| 2833 | |
| 2834 | |
| 2835 | |
| 2836 | |
| 2837 | /************************************************* |
| 2838 | * Random number generation * |
| 2839 | *************************************************/ |
| 2840 | |
| 2841 | /* Pseudo-random number generation. The result is not expected to be |
| 2842 | cryptographically strong but not so weak that someone will shoot themselves |
| 2843 | in the foot using it as a nonce in input in some email header scheme or |
| 2844 | whatever weirdness they'll twist this into. The result should handle fork() |
| 2845 | and avoid repeating sequences. OpenSSL handles that for us. |
| 2846 | |
| 2847 | Arguments: |
| 2848 | max range maximum |
| 2849 | Returns a random number in range [0, max-1] |
| 2850 | */ |
| 2851 | |
| 2852 | int |
| 2853 | vaguely_random_number(int max) |
| 2854 | { |
| 2855 | unsigned int r; |
| 2856 | int i, needed_len; |
| 2857 | static pid_t pidlast = 0; |
| 2858 | pid_t pidnow; |
| 2859 | uschar *p; |
| 2860 | uschar smallbuf[sizeof(r)]; |
| 2861 | |
| 2862 | if (max <= 1) |
| 2863 | return 0; |
| 2864 | |
| 2865 | pidnow = getpid(); |
| 2866 | if (pidnow != pidlast) |
| 2867 | { |
| 2868 | /* Although OpenSSL documents that "OpenSSL makes sure that the PRNG state |
| 2869 | is unique for each thread", this doesn't apparently apply across processes, |
| 2870 | so our own warning from vaguely_random_number_fallback() applies here too. |
| 2871 | Fix per PostgreSQL. */ |
| 2872 | if (pidlast != 0) |
| 2873 | RAND_cleanup(); |
| 2874 | pidlast = pidnow; |
| 2875 | } |
| 2876 | |
| 2877 | /* OpenSSL auto-seeds from /dev/random, etc, but this a double-check. */ |
| 2878 | if (!RAND_status()) |
| 2879 | { |
| 2880 | randstuff r; |
| 2881 | gettimeofday(&r.tv, NULL); |
| 2882 | r.p = getpid(); |
| 2883 | |
| 2884 | RAND_seed(US (&r), sizeof(r)); |
| 2885 | } |
| 2886 | /* We're after pseudo-random, not random; if we still don't have enough data |
| 2887 | in the internal PRNG then our options are limited. We could sleep and hope |
| 2888 | for entropy to come along (prayer technique) but if the system is so depleted |
| 2889 | in the first place then something is likely to just keep taking it. Instead, |
| 2890 | we'll just take whatever little bit of pseudo-random we can still manage to |
| 2891 | get. */ |
| 2892 | |
| 2893 | needed_len = sizeof(r); |
| 2894 | /* Don't take 8 times more entropy than needed if int is 8 octets and we were |
| 2895 | asked for a number less than 10. */ |
| 2896 | for (r = max, i = 0; r; ++i) |
| 2897 | r >>= 1; |
| 2898 | i = (i + 7) / 8; |
| 2899 | if (i < needed_len) |
| 2900 | needed_len = i; |
| 2901 | |
| 2902 | #ifdef EXIM_HAVE_RAND_PSEUDO |
| 2903 | /* We do not care if crypto-strong */ |
| 2904 | i = RAND_pseudo_bytes(smallbuf, needed_len); |
| 2905 | #else |
| 2906 | i = RAND_bytes(smallbuf, needed_len); |
| 2907 | #endif |
| 2908 | |
| 2909 | if (i < 0) |
| 2910 | { |
| 2911 | DEBUG(D_all) |
| 2912 | debug_printf("OpenSSL RAND_pseudo_bytes() not supported by RAND method, using fallback.\n"); |
| 2913 | return vaguely_random_number_fallback(max); |
| 2914 | } |
| 2915 | |
| 2916 | r = 0; |
| 2917 | for (p = smallbuf; needed_len; --needed_len, ++p) |
| 2918 | { |
| 2919 | r *= 256; |
| 2920 | r += *p; |
| 2921 | } |
| 2922 | |
| 2923 | /* We don't particularly care about weighted results; if someone wants |
| 2924 | smooth distribution and cares enough then they should submit a patch then. */ |
| 2925 | return r % max; |
| 2926 | } |
| 2927 | |
| 2928 | |
| 2929 | |
| 2930 | |
| 2931 | /************************************************* |
| 2932 | * OpenSSL option parse * |
| 2933 | *************************************************/ |
| 2934 | |
| 2935 | /* Parse one option for tls_openssl_options_parse below |
| 2936 | |
| 2937 | Arguments: |
| 2938 | name one option name |
| 2939 | value place to store a value for it |
| 2940 | Returns success or failure in parsing |
| 2941 | */ |
| 2942 | |
| 2943 | struct exim_openssl_option { |
| 2944 | uschar *name; |
| 2945 | long value; |
| 2946 | }; |
| 2947 | /* We could use a macro to expand, but we need the ifdef and not all the |
| 2948 | options document which version they were introduced in. Policylet: include |
| 2949 | all options unless explicitly for DTLS, let the administrator choose which |
| 2950 | to apply. |
| 2951 | |
| 2952 | This list is current as of: |
| 2953 | ==> 1.0.1b <== |
| 2954 | Plus SSL_OP_SAFARI_ECDHE_ECDSA_BUG from 2013-June patch/discussion on openssl-dev |
| 2955 | */ |
| 2956 | static struct exim_openssl_option exim_openssl_options[] = { |
| 2957 | /* KEEP SORTED ALPHABETICALLY! */ |
| 2958 | #ifdef SSL_OP_ALL |
| 2959 | { US"all", SSL_OP_ALL }, |
| 2960 | #endif |
| 2961 | #ifdef SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION |
| 2962 | { US"allow_unsafe_legacy_renegotiation", SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION }, |
| 2963 | #endif |
| 2964 | #ifdef SSL_OP_CIPHER_SERVER_PREFERENCE |
| 2965 | { US"cipher_server_preference", SSL_OP_CIPHER_SERVER_PREFERENCE }, |
| 2966 | #endif |
| 2967 | #ifdef SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS |
| 2968 | { US"dont_insert_empty_fragments", SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS }, |
| 2969 | #endif |
| 2970 | #ifdef SSL_OP_EPHEMERAL_RSA |
| 2971 | { US"ephemeral_rsa", SSL_OP_EPHEMERAL_RSA }, |
| 2972 | #endif |
| 2973 | #ifdef SSL_OP_LEGACY_SERVER_CONNECT |
| 2974 | { US"legacy_server_connect", SSL_OP_LEGACY_SERVER_CONNECT }, |
| 2975 | #endif |
| 2976 | #ifdef SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER |
| 2977 | { US"microsoft_big_sslv3_buffer", SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER }, |
| 2978 | #endif |
| 2979 | #ifdef SSL_OP_MICROSOFT_SESS_ID_BUG |
| 2980 | { US"microsoft_sess_id_bug", SSL_OP_MICROSOFT_SESS_ID_BUG }, |
| 2981 | #endif |
| 2982 | #ifdef SSL_OP_MSIE_SSLV2_RSA_PADDING |
| 2983 | { US"msie_sslv2_rsa_padding", SSL_OP_MSIE_SSLV2_RSA_PADDING }, |
| 2984 | #endif |
| 2985 | #ifdef SSL_OP_NETSCAPE_CHALLENGE_BUG |
| 2986 | { US"netscape_challenge_bug", SSL_OP_NETSCAPE_CHALLENGE_BUG }, |
| 2987 | #endif |
| 2988 | #ifdef SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG |
| 2989 | { US"netscape_reuse_cipher_change_bug", SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG }, |
| 2990 | #endif |
| 2991 | #ifdef SSL_OP_NO_COMPRESSION |
| 2992 | { US"no_compression", SSL_OP_NO_COMPRESSION }, |
| 2993 | #endif |
| 2994 | #ifdef SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION |
| 2995 | { US"no_session_resumption_on_renegotiation", SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION }, |
| 2996 | #endif |
| 2997 | #ifdef SSL_OP_NO_SSLv2 |
| 2998 | { US"no_sslv2", SSL_OP_NO_SSLv2 }, |
| 2999 | #endif |
| 3000 | #ifdef SSL_OP_NO_SSLv3 |
| 3001 | { US"no_sslv3", SSL_OP_NO_SSLv3 }, |
| 3002 | #endif |
| 3003 | #ifdef SSL_OP_NO_TICKET |
| 3004 | { US"no_ticket", SSL_OP_NO_TICKET }, |
| 3005 | #endif |
| 3006 | #ifdef SSL_OP_NO_TLSv1 |
| 3007 | { US"no_tlsv1", SSL_OP_NO_TLSv1 }, |
| 3008 | #endif |
| 3009 | #ifdef SSL_OP_NO_TLSv1_1 |
| 3010 | #if SSL_OP_NO_TLSv1_1 == 0x00000400L |
| 3011 | /* Error in chosen value in 1.0.1a; see first item in CHANGES for 1.0.1b */ |
| 3012 | #warning OpenSSL 1.0.1a uses a bad value for SSL_OP_NO_TLSv1_1, ignoring |
| 3013 | #else |
| 3014 | { US"no_tlsv1_1", SSL_OP_NO_TLSv1_1 }, |
| 3015 | #endif |
| 3016 | #endif |
| 3017 | #ifdef SSL_OP_NO_TLSv1_2 |
| 3018 | { US"no_tlsv1_2", SSL_OP_NO_TLSv1_2 }, |
| 3019 | #endif |
| 3020 | #ifdef SSL_OP_SAFARI_ECDHE_ECDSA_BUG |
| 3021 | { US"safari_ecdhe_ecdsa_bug", SSL_OP_SAFARI_ECDHE_ECDSA_BUG }, |
| 3022 | #endif |
| 3023 | #ifdef SSL_OP_SINGLE_DH_USE |
| 3024 | { US"single_dh_use", SSL_OP_SINGLE_DH_USE }, |
| 3025 | #endif |
| 3026 | #ifdef SSL_OP_SINGLE_ECDH_USE |
| 3027 | { US"single_ecdh_use", SSL_OP_SINGLE_ECDH_USE }, |
| 3028 | #endif |
| 3029 | #ifdef SSL_OP_SSLEAY_080_CLIENT_DH_BUG |
| 3030 | { US"ssleay_080_client_dh_bug", SSL_OP_SSLEAY_080_CLIENT_DH_BUG }, |
| 3031 | #endif |
| 3032 | #ifdef SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG |
| 3033 | { US"sslref2_reuse_cert_type_bug", SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG }, |
| 3034 | #endif |
| 3035 | #ifdef SSL_OP_TLS_BLOCK_PADDING_BUG |
| 3036 | { US"tls_block_padding_bug", SSL_OP_TLS_BLOCK_PADDING_BUG }, |
| 3037 | #endif |
| 3038 | #ifdef SSL_OP_TLS_D5_BUG |
| 3039 | { US"tls_d5_bug", SSL_OP_TLS_D5_BUG }, |
| 3040 | #endif |
| 3041 | #ifdef SSL_OP_TLS_ROLLBACK_BUG |
| 3042 | { US"tls_rollback_bug", SSL_OP_TLS_ROLLBACK_BUG }, |
| 3043 | #endif |
| 3044 | }; |
| 3045 | static int exim_openssl_options_size = |
| 3046 | sizeof(exim_openssl_options)/sizeof(struct exim_openssl_option); |
| 3047 | |
| 3048 | |
| 3049 | static BOOL |
| 3050 | tls_openssl_one_option_parse(uschar *name, long *value) |
| 3051 | { |
| 3052 | int first = 0; |
| 3053 | int last = exim_openssl_options_size; |
| 3054 | while (last > first) |
| 3055 | { |
| 3056 | int middle = (first + last)/2; |
| 3057 | int c = Ustrcmp(name, exim_openssl_options[middle].name); |
| 3058 | if (c == 0) |
| 3059 | { |
| 3060 | *value = exim_openssl_options[middle].value; |
| 3061 | return TRUE; |
| 3062 | } |
| 3063 | else if (c > 0) |
| 3064 | first = middle + 1; |
| 3065 | else |
| 3066 | last = middle; |
| 3067 | } |
| 3068 | return FALSE; |
| 3069 | } |
| 3070 | |
| 3071 | |
| 3072 | |
| 3073 | |
| 3074 | /************************************************* |
| 3075 | * OpenSSL option parsing logic * |
| 3076 | *************************************************/ |
| 3077 | |
| 3078 | /* OpenSSL has a number of compatibility options which an administrator might |
| 3079 | reasonably wish to set. Interpret a list similarly to decode_bits(), so that |
| 3080 | we look like log_selector. |
| 3081 | |
| 3082 | Arguments: |
| 3083 | option_spec the administrator-supplied string of options |
| 3084 | results ptr to long storage for the options bitmap |
| 3085 | Returns success or failure |
| 3086 | */ |
| 3087 | |
| 3088 | BOOL |
| 3089 | tls_openssl_options_parse(uschar *option_spec, long *results) |
| 3090 | { |
| 3091 | long result, item; |
| 3092 | uschar *s, *end; |
| 3093 | uschar keep_c; |
| 3094 | BOOL adding, item_parsed; |
| 3095 | |
| 3096 | result = SSL_OP_NO_TICKET; |
| 3097 | /* Prior to 4.80 we or'd in SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS; removed |
| 3098 | * from default because it increases BEAST susceptibility. */ |
| 3099 | #ifdef SSL_OP_NO_SSLv2 |
| 3100 | result |= SSL_OP_NO_SSLv2; |
| 3101 | #endif |
| 3102 | #ifdef SSL_OP_SINGLE_DH_USE |
| 3103 | result |= SSL_OP_SINGLE_DH_USE; |
| 3104 | #endif |
| 3105 | |
| 3106 | if (!option_spec) |
| 3107 | { |
| 3108 | *results = result; |
| 3109 | return TRUE; |
| 3110 | } |
| 3111 | |
| 3112 | for (s=option_spec; *s != '\0'; /**/) |
| 3113 | { |
| 3114 | while (isspace(*s)) ++s; |
| 3115 | if (*s == '\0') |
| 3116 | break; |
| 3117 | if (*s != '+' && *s != '-') |
| 3118 | { |
| 3119 | DEBUG(D_tls) debug_printf("malformed openssl option setting: " |
| 3120 | "+ or - expected but found \"%s\"\n", s); |
| 3121 | return FALSE; |
| 3122 | } |
| 3123 | adding = *s++ == '+'; |
| 3124 | for (end = s; (*end != '\0') && !isspace(*end); ++end) /**/ ; |
| 3125 | keep_c = *end; |
| 3126 | *end = '\0'; |
| 3127 | item_parsed = tls_openssl_one_option_parse(s, &item); |
| 3128 | *end = keep_c; |
| 3129 | if (!item_parsed) |
| 3130 | { |
| 3131 | DEBUG(D_tls) debug_printf("openssl option setting unrecognised: \"%s\"\n", s); |
| 3132 | return FALSE; |
| 3133 | } |
| 3134 | DEBUG(D_tls) debug_printf("openssl option, %s from %lx: %lx (%s)\n", |
| 3135 | adding ? "adding" : "removing", result, item, s); |
| 3136 | if (adding) |
| 3137 | result |= item; |
| 3138 | else |
| 3139 | result &= ~item; |
| 3140 | s = end; |
| 3141 | } |
| 3142 | |
| 3143 | *results = result; |
| 3144 | return TRUE; |
| 3145 | } |
| 3146 | |
| 3147 | /* vi: aw ai sw=2 |
| 3148 | */ |
| 3149 | /* End of tls-openssl.c */ |