| 1 | /************************************************* |
| 2 | * Exim - an Internet mail transport agent * |
| 3 | *************************************************/ |
| 4 | |
| 5 | /* Copyright (c) University of Cambridge 1995 - 2019 */ |
| 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 |
| 55 | #endif |
| 56 | |
| 57 | /* X509_check_host provides sane certificate hostname checking, but was added |
| 58 | to OpenSSL late, after other projects forked off the code-base. So in |
| 59 | addition to guarding against the base version number, beware that LibreSSL |
| 60 | does not (at this time) support this function. |
| 61 | |
| 62 | If LibreSSL gains a different API, perhaps via libtls, then we'll probably |
| 63 | opt to disentangle and ask a LibreSSL user to provide glue for a third |
| 64 | crypto provider for libtls instead of continuing to tie the OpenSSL glue |
| 65 | into even twistier knots. If LibreSSL gains the same API, we can just |
| 66 | change this guard and punt the issue for a while longer. */ |
| 67 | |
| 68 | #ifndef LIBRESSL_VERSION_NUMBER |
| 69 | # if OPENSSL_VERSION_NUMBER >= 0x010100000L |
| 70 | # define EXIM_HAVE_OPENSSL_CHECKHOST |
| 71 | # define EXIM_HAVE_OPENSSL_DH_BITS |
| 72 | # define EXIM_HAVE_OPENSSL_TLS_METHOD |
| 73 | # define EXIM_HAVE_OPENSSL_KEYLOG |
| 74 | # define EXIM_HAVE_OPENSSL_CIPHER_GET_ID |
| 75 | # define EXIM_HAVE_SESSION_TICKET |
| 76 | # define EXIM_HAVE_OPESSL_TRACE |
| 77 | # else |
| 78 | # define EXIM_NEED_OPENSSL_INIT |
| 79 | # endif |
| 80 | # if OPENSSL_VERSION_NUMBER >= 0x010000000L \ |
| 81 | && (OPENSSL_VERSION_NUMBER & 0x0000ff000L) >= 0x000002000L |
| 82 | # define EXIM_HAVE_OPENSSL_CHECKHOST |
| 83 | # endif |
| 84 | #endif |
| 85 | |
| 86 | #if !defined(LIBRESSL_VERSION_NUMBER) \ |
| 87 | || LIBRESSL_VERSION_NUMBER >= 0x20010000L |
| 88 | # if !defined(OPENSSL_NO_ECDH) |
| 89 | # if OPENSSL_VERSION_NUMBER >= 0x0090800fL |
| 90 | # define EXIM_HAVE_ECDH |
| 91 | # endif |
| 92 | # if OPENSSL_VERSION_NUMBER >= 0x10002000L |
| 93 | # define EXIM_HAVE_OPENSSL_EC_NIST2NID |
| 94 | # endif |
| 95 | # endif |
| 96 | #endif |
| 97 | |
| 98 | #ifndef LIBRESSL_VERSION_NUMBER |
| 99 | # if OPENSSL_VERSION_NUMBER >= 0x010101000L |
| 100 | # define OPENSSL_HAVE_KEYLOG_CB |
| 101 | # define OPENSSL_HAVE_NUM_TICKETS |
| 102 | # define EXIM_HAVE_OPENSSL_CIPHER_STD_NAME |
| 103 | # endif |
| 104 | #endif |
| 105 | |
| 106 | #if !defined(EXIM_HAVE_OPENSSL_TLSEXT) && !defined(DISABLE_OCSP) |
| 107 | # warning "OpenSSL library version too old; define DISABLE_OCSP in Makefile" |
| 108 | # define DISABLE_OCSP |
| 109 | #endif |
| 110 | |
| 111 | #ifdef EXPERIMENTAL_TLS_RESUME |
| 112 | # if OPENSSL_VERSION_NUMBER < 0x0101010L |
| 113 | # error OpenSSL version too old for session-resumption |
| 114 | # endif |
| 115 | #endif |
| 116 | |
| 117 | #ifdef EXIM_HAVE_OPENSSL_CHECKHOST |
| 118 | # include <openssl/x509v3.h> |
| 119 | #endif |
| 120 | |
| 121 | #ifndef EXIM_HAVE_OPENSSL_CIPHER_STD_NAME |
| 122 | # ifndef EXIM_HAVE_OPENSSL_CIPHER_GET_ID |
| 123 | # define SSL_CIPHER_get_id(c) (c->id) |
| 124 | # endif |
| 125 | # ifndef MACRO_PREDEF |
| 126 | # include "tls-cipher-stdname.c" |
| 127 | # endif |
| 128 | #endif |
| 129 | |
| 130 | /************************************************* |
| 131 | * OpenSSL option parse * |
| 132 | *************************************************/ |
| 133 | |
| 134 | typedef struct exim_openssl_option { |
| 135 | uschar *name; |
| 136 | long value; |
| 137 | } exim_openssl_option; |
| 138 | /* We could use a macro to expand, but we need the ifdef and not all the |
| 139 | options document which version they were introduced in. Policylet: include |
| 140 | all options unless explicitly for DTLS, let the administrator choose which |
| 141 | to apply. |
| 142 | |
| 143 | This list is current as of: |
| 144 | ==> 1.0.1b <== |
| 145 | Plus SSL_OP_SAFARI_ECDHE_ECDSA_BUG from 2013-June patch/discussion on openssl-dev |
| 146 | Plus SSL_OP_NO_TLSv1_3 for 1.1.2-dev |
| 147 | */ |
| 148 | static exim_openssl_option exim_openssl_options[] = { |
| 149 | /* KEEP SORTED ALPHABETICALLY! */ |
| 150 | #ifdef SSL_OP_ALL |
| 151 | { US"all", (long) SSL_OP_ALL }, |
| 152 | #endif |
| 153 | #ifdef SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION |
| 154 | { US"allow_unsafe_legacy_renegotiation", SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION }, |
| 155 | #endif |
| 156 | #ifdef SSL_OP_CIPHER_SERVER_PREFERENCE |
| 157 | { US"cipher_server_preference", SSL_OP_CIPHER_SERVER_PREFERENCE }, |
| 158 | #endif |
| 159 | #ifdef SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS |
| 160 | { US"dont_insert_empty_fragments", SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS }, |
| 161 | #endif |
| 162 | #ifdef SSL_OP_EPHEMERAL_RSA |
| 163 | { US"ephemeral_rsa", SSL_OP_EPHEMERAL_RSA }, |
| 164 | #endif |
| 165 | #ifdef SSL_OP_LEGACY_SERVER_CONNECT |
| 166 | { US"legacy_server_connect", SSL_OP_LEGACY_SERVER_CONNECT }, |
| 167 | #endif |
| 168 | #ifdef SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER |
| 169 | { US"microsoft_big_sslv3_buffer", SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER }, |
| 170 | #endif |
| 171 | #ifdef SSL_OP_MICROSOFT_SESS_ID_BUG |
| 172 | { US"microsoft_sess_id_bug", SSL_OP_MICROSOFT_SESS_ID_BUG }, |
| 173 | #endif |
| 174 | #ifdef SSL_OP_MSIE_SSLV2_RSA_PADDING |
| 175 | { US"msie_sslv2_rsa_padding", SSL_OP_MSIE_SSLV2_RSA_PADDING }, |
| 176 | #endif |
| 177 | #ifdef SSL_OP_NETSCAPE_CHALLENGE_BUG |
| 178 | { US"netscape_challenge_bug", SSL_OP_NETSCAPE_CHALLENGE_BUG }, |
| 179 | #endif |
| 180 | #ifdef SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG |
| 181 | { US"netscape_reuse_cipher_change_bug", SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG }, |
| 182 | #endif |
| 183 | #ifdef SSL_OP_NO_COMPRESSION |
| 184 | { US"no_compression", SSL_OP_NO_COMPRESSION }, |
| 185 | #endif |
| 186 | #ifdef SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION |
| 187 | { US"no_session_resumption_on_renegotiation", SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION }, |
| 188 | #endif |
| 189 | #ifdef SSL_OP_NO_SSLv2 |
| 190 | { US"no_sslv2", SSL_OP_NO_SSLv2 }, |
| 191 | #endif |
| 192 | #ifdef SSL_OP_NO_SSLv3 |
| 193 | { US"no_sslv3", SSL_OP_NO_SSLv3 }, |
| 194 | #endif |
| 195 | #ifdef SSL_OP_NO_TICKET |
| 196 | { US"no_ticket", SSL_OP_NO_TICKET }, |
| 197 | #endif |
| 198 | #ifdef SSL_OP_NO_TLSv1 |
| 199 | { US"no_tlsv1", SSL_OP_NO_TLSv1 }, |
| 200 | #endif |
| 201 | #ifdef SSL_OP_NO_TLSv1_1 |
| 202 | #if SSL_OP_NO_TLSv1_1 == 0x00000400L |
| 203 | /* Error in chosen value in 1.0.1a; see first item in CHANGES for 1.0.1b */ |
| 204 | #warning OpenSSL 1.0.1a uses a bad value for SSL_OP_NO_TLSv1_1, ignoring |
| 205 | #else |
| 206 | { US"no_tlsv1_1", SSL_OP_NO_TLSv1_1 }, |
| 207 | #endif |
| 208 | #endif |
| 209 | #ifdef SSL_OP_NO_TLSv1_2 |
| 210 | { US"no_tlsv1_2", SSL_OP_NO_TLSv1_2 }, |
| 211 | #endif |
| 212 | #ifdef SSL_OP_NO_TLSv1_3 |
| 213 | { US"no_tlsv1_3", SSL_OP_NO_TLSv1_3 }, |
| 214 | #endif |
| 215 | #ifdef SSL_OP_SAFARI_ECDHE_ECDSA_BUG |
| 216 | { US"safari_ecdhe_ecdsa_bug", SSL_OP_SAFARI_ECDHE_ECDSA_BUG }, |
| 217 | #endif |
| 218 | #ifdef SSL_OP_SINGLE_DH_USE |
| 219 | { US"single_dh_use", SSL_OP_SINGLE_DH_USE }, |
| 220 | #endif |
| 221 | #ifdef SSL_OP_SINGLE_ECDH_USE |
| 222 | { US"single_ecdh_use", SSL_OP_SINGLE_ECDH_USE }, |
| 223 | #endif |
| 224 | #ifdef SSL_OP_SSLEAY_080_CLIENT_DH_BUG |
| 225 | { US"ssleay_080_client_dh_bug", SSL_OP_SSLEAY_080_CLIENT_DH_BUG }, |
| 226 | #endif |
| 227 | #ifdef SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG |
| 228 | { US"sslref2_reuse_cert_type_bug", SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG }, |
| 229 | #endif |
| 230 | #ifdef SSL_OP_TLS_BLOCK_PADDING_BUG |
| 231 | { US"tls_block_padding_bug", SSL_OP_TLS_BLOCK_PADDING_BUG }, |
| 232 | #endif |
| 233 | #ifdef SSL_OP_TLS_D5_BUG |
| 234 | { US"tls_d5_bug", SSL_OP_TLS_D5_BUG }, |
| 235 | #endif |
| 236 | #ifdef SSL_OP_TLS_ROLLBACK_BUG |
| 237 | { US"tls_rollback_bug", SSL_OP_TLS_ROLLBACK_BUG }, |
| 238 | #endif |
| 239 | }; |
| 240 | |
| 241 | #ifndef MACRO_PREDEF |
| 242 | static int exim_openssl_options_size = nelem(exim_openssl_options); |
| 243 | #endif |
| 244 | |
| 245 | #ifdef MACRO_PREDEF |
| 246 | void |
| 247 | options_tls(void) |
| 248 | { |
| 249 | uschar buf[64]; |
| 250 | |
| 251 | for (struct exim_openssl_option * o = exim_openssl_options; |
| 252 | o < exim_openssl_options + nelem(exim_openssl_options); o++) |
| 253 | { |
| 254 | /* Trailing X is workaround for problem with _OPT_OPENSSL_NO_TLSV1 |
| 255 | being a ".ifdef _OPT_OPENSSL_NO_TLSV1_3" match */ |
| 256 | |
| 257 | spf(buf, sizeof(buf), US"_OPT_OPENSSL_%T_X", o->name); |
| 258 | builtin_macro_create(buf); |
| 259 | } |
| 260 | |
| 261 | # ifdef EXPERIMENTAL_TLS_RESUME |
| 262 | builtin_macro_create_var(US"_RESUME_DECODE", RESUME_DECODE_STRING ); |
| 263 | # endif |
| 264 | # ifdef SSL_OP_NO_TLSv1_3 |
| 265 | builtin_macro_create(US"_HAVE_TLS1_3"); |
| 266 | # endif |
| 267 | } |
| 268 | #else |
| 269 | |
| 270 | /******************************************************************************/ |
| 271 | |
| 272 | /* Structure for collecting random data for seeding. */ |
| 273 | |
| 274 | typedef struct randstuff { |
| 275 | struct timeval tv; |
| 276 | pid_t p; |
| 277 | } randstuff; |
| 278 | |
| 279 | /* Local static variables */ |
| 280 | |
| 281 | static BOOL client_verify_callback_called = FALSE; |
| 282 | static BOOL server_verify_callback_called = FALSE; |
| 283 | static const uschar *sid_ctx = US"exim"; |
| 284 | |
| 285 | /* We have three different contexts to care about. |
| 286 | |
| 287 | Simple case: client, `client_ctx` |
| 288 | As a client, we can be doing a callout or cut-through delivery while receiving |
| 289 | a message. So we have a client context, which should have options initialised |
| 290 | from the SMTP Transport. We may also concurrently want to make TLS connections |
| 291 | to utility daemons, so client-contexts are allocated and passed around in call |
| 292 | args rather than using a gobal. |
| 293 | |
| 294 | Server: |
| 295 | There are two cases: with and without ServerNameIndication from the client. |
| 296 | Given TLS SNI, we can be using different keys, certs and various other |
| 297 | configuration settings, because they're re-expanded with $tls_sni set. This |
| 298 | allows vhosting with TLS. This SNI is sent in the handshake. |
| 299 | A client might not send SNI, so we need a fallback, and an initial setup too. |
| 300 | So as a server, we start out using `server_ctx`. |
| 301 | If SNI is sent by the client, then we as server, mid-negotiation, try to clone |
| 302 | `server_sni` from `server_ctx` and then initialise settings by re-expanding |
| 303 | configuration. |
| 304 | */ |
| 305 | |
| 306 | typedef struct { |
| 307 | SSL_CTX * ctx; |
| 308 | SSL * ssl; |
| 309 | gstring * corked; |
| 310 | } exim_openssl_client_tls_ctx; |
| 311 | |
| 312 | static SSL_CTX *server_ctx = NULL; |
| 313 | static SSL *server_ssl = NULL; |
| 314 | |
| 315 | #ifdef EXIM_HAVE_OPENSSL_TLSEXT |
| 316 | static SSL_CTX *server_sni = NULL; |
| 317 | #endif |
| 318 | |
| 319 | static char ssl_errstring[256]; |
| 320 | |
| 321 | static int ssl_session_timeout = 7200; /* Two hours */ |
| 322 | static BOOL client_verify_optional = FALSE; |
| 323 | static BOOL server_verify_optional = FALSE; |
| 324 | |
| 325 | static BOOL reexpand_tls_files_for_sni = FALSE; |
| 326 | |
| 327 | |
| 328 | typedef struct tls_ext_ctx_cb { |
| 329 | tls_support * tlsp; |
| 330 | uschar *certificate; |
| 331 | uschar *privatekey; |
| 332 | BOOL is_server; |
| 333 | #ifndef DISABLE_OCSP |
| 334 | STACK_OF(X509) *verify_stack; /* chain for verifying the proof */ |
| 335 | union { |
| 336 | struct { |
| 337 | uschar *file; |
| 338 | uschar *file_expanded; |
| 339 | OCSP_RESPONSE *response; |
| 340 | } server; |
| 341 | struct { |
| 342 | X509_STORE *verify_store; /* non-null if status requested */ |
| 343 | BOOL verify_required; |
| 344 | } client; |
| 345 | } u_ocsp; |
| 346 | #endif |
| 347 | uschar *dhparam; |
| 348 | /* these are cached from first expand */ |
| 349 | uschar *server_cipher_list; |
| 350 | /* only passed down to tls_error: */ |
| 351 | host_item *host; |
| 352 | const uschar * verify_cert_hostnames; |
| 353 | #ifndef DISABLE_EVENT |
| 354 | uschar * event_action; |
| 355 | #endif |
| 356 | } tls_ext_ctx_cb; |
| 357 | |
| 358 | /* should figure out a cleanup of API to handle state preserved per |
| 359 | implementation, for various reasons, which can be void * in the APIs. |
| 360 | For now, we hack around it. */ |
| 361 | tls_ext_ctx_cb *client_static_cbinfo = NULL; /*XXX should not use static; multiple concurrent clients! */ |
| 362 | tls_ext_ctx_cb *server_static_cbinfo = NULL; |
| 363 | |
| 364 | static int |
| 365 | setup_certs(SSL_CTX *sctx, uschar *certs, uschar *crl, host_item *host, BOOL optional, |
| 366 | int (*cert_vfy_cb)(int, X509_STORE_CTX *), uschar ** errstr ); |
| 367 | |
| 368 | /* Callbacks */ |
| 369 | #ifdef EXIM_HAVE_OPENSSL_TLSEXT |
| 370 | static int tls_servername_cb(SSL *s, int *ad ARG_UNUSED, void *arg); |
| 371 | #endif |
| 372 | #ifndef DISABLE_OCSP |
| 373 | static int tls_server_stapling_cb(SSL *s, void *arg); |
| 374 | #endif |
| 375 | |
| 376 | |
| 377 | |
| 378 | /* Daemon-called, before every connection, key create/rotate */ |
| 379 | #ifdef EXPERIMENTAL_TLS_RESUME |
| 380 | static void tk_init(void); |
| 381 | static int tls_exdata_idx = -1; |
| 382 | #endif |
| 383 | |
| 384 | void |
| 385 | tls_daemon_init(void) |
| 386 | { |
| 387 | #ifdef EXPERIMENTAL_TLS_RESUME |
| 388 | tk_init(); |
| 389 | #endif |
| 390 | return; |
| 391 | } |
| 392 | |
| 393 | |
| 394 | /************************************************* |
| 395 | * Handle TLS error * |
| 396 | *************************************************/ |
| 397 | |
| 398 | /* Called from lots of places when errors occur before actually starting to do |
| 399 | the TLS handshake, that is, while the session is still in clear. Always returns |
| 400 | DEFER for a server and FAIL for a client so that most calls can use "return |
| 401 | tls_error(...)" to do this processing and then give an appropriate return. A |
| 402 | single function is used for both server and client, because it is called from |
| 403 | some shared functions. |
| 404 | |
| 405 | Argument: |
| 406 | prefix text to include in the logged error |
| 407 | host NULL if setting up a server; |
| 408 | the connected host if setting up a client |
| 409 | msg error message or NULL if we should ask OpenSSL |
| 410 | errstr pointer to output error message |
| 411 | |
| 412 | Returns: OK/DEFER/FAIL |
| 413 | */ |
| 414 | |
| 415 | static int |
| 416 | tls_error(uschar * prefix, const host_item * host, uschar * msg, uschar ** errstr) |
| 417 | { |
| 418 | if (!msg) |
| 419 | { |
| 420 | ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring)); |
| 421 | msg = US ssl_errstring; |
| 422 | } |
| 423 | |
| 424 | msg = string_sprintf("(%s): %s", prefix, msg); |
| 425 | DEBUG(D_tls) debug_printf("TLS error '%s'\n", msg); |
| 426 | if (errstr) *errstr = msg; |
| 427 | return host ? FAIL : DEFER; |
| 428 | } |
| 429 | |
| 430 | |
| 431 | |
| 432 | /************************************************* |
| 433 | * Callback to generate RSA key * |
| 434 | *************************************************/ |
| 435 | |
| 436 | /* |
| 437 | Arguments: |
| 438 | s SSL connection (not used) |
| 439 | export not used |
| 440 | keylength keylength |
| 441 | |
| 442 | Returns: pointer to generated key |
| 443 | */ |
| 444 | |
| 445 | static RSA * |
| 446 | rsa_callback(SSL *s, int export, int keylength) |
| 447 | { |
| 448 | RSA *rsa_key; |
| 449 | #ifdef EXIM_HAVE_RSA_GENKEY_EX |
| 450 | BIGNUM *bn = BN_new(); |
| 451 | #endif |
| 452 | |
| 453 | export = export; /* Shut picky compilers up */ |
| 454 | DEBUG(D_tls) debug_printf("Generating %d bit RSA key...\n", keylength); |
| 455 | |
| 456 | #ifdef EXIM_HAVE_RSA_GENKEY_EX |
| 457 | if ( !BN_set_word(bn, (unsigned long)RSA_F4) |
| 458 | || !(rsa_key = RSA_new()) |
| 459 | || !RSA_generate_key_ex(rsa_key, keylength, bn, NULL) |
| 460 | ) |
| 461 | #else |
| 462 | if (!(rsa_key = RSA_generate_key(keylength, RSA_F4, NULL, NULL))) |
| 463 | #endif |
| 464 | |
| 465 | { |
| 466 | ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring)); |
| 467 | log_write(0, LOG_MAIN|LOG_PANIC, "TLS error (RSA_generate_key): %s", |
| 468 | ssl_errstring); |
| 469 | return NULL; |
| 470 | } |
| 471 | return rsa_key; |
| 472 | } |
| 473 | |
| 474 | |
| 475 | |
| 476 | /* Extreme debug |
| 477 | #ifndef DISABLE_OCSP |
| 478 | void |
| 479 | x509_store_dump_cert_s_names(X509_STORE * store) |
| 480 | { |
| 481 | STACK_OF(X509_OBJECT) * roots= store->objs; |
| 482 | static uschar name[256]; |
| 483 | |
| 484 | for (int i= 0; i < sk_X509_OBJECT_num(roots); i++) |
| 485 | { |
| 486 | X509_OBJECT * tmp_obj= sk_X509_OBJECT_value(roots, i); |
| 487 | if(tmp_obj->type == X509_LU_X509) |
| 488 | { |
| 489 | X509_NAME * sn = X509_get_subject_name(tmp_obj->data.x509); |
| 490 | if (X509_NAME_oneline(sn, CS name, sizeof(name))) |
| 491 | { |
| 492 | name[sizeof(name)-1] = '\0'; |
| 493 | debug_printf(" %s\n", name); |
| 494 | } |
| 495 | } |
| 496 | } |
| 497 | } |
| 498 | #endif |
| 499 | */ |
| 500 | |
| 501 | |
| 502 | #ifndef DISABLE_EVENT |
| 503 | static int |
| 504 | verify_event(tls_support * tlsp, X509 * cert, int depth, const uschar * dn, |
| 505 | BOOL *calledp, const BOOL *optionalp, const uschar * what) |
| 506 | { |
| 507 | uschar * ev; |
| 508 | uschar * yield; |
| 509 | X509 * old_cert; |
| 510 | |
| 511 | ev = tlsp == &tls_out ? client_static_cbinfo->event_action : event_action; |
| 512 | if (ev) |
| 513 | { |
| 514 | DEBUG(D_tls) debug_printf("verify_event: %s %d\n", what, depth); |
| 515 | old_cert = tlsp->peercert; |
| 516 | tlsp->peercert = X509_dup(cert); |
| 517 | /* NB we do not bother setting peerdn */ |
| 518 | if ((yield = event_raise(ev, US"tls:cert", string_sprintf("%d", depth)))) |
| 519 | { |
| 520 | log_write(0, LOG_MAIN, "[%s] %s verify denied by event-action: " |
| 521 | "depth=%d cert=%s: %s", |
| 522 | tlsp == &tls_out ? deliver_host_address : sender_host_address, |
| 523 | what, depth, dn, yield); |
| 524 | *calledp = TRUE; |
| 525 | if (!*optionalp) |
| 526 | { |
| 527 | if (old_cert) tlsp->peercert = old_cert; /* restore 1st failing cert */ |
| 528 | return 1; /* reject (leaving peercert set) */ |
| 529 | } |
| 530 | DEBUG(D_tls) debug_printf("Event-action verify failure overridden " |
| 531 | "(host in tls_try_verify_hosts)\n"); |
| 532 | tlsp->verify_override = TRUE; |
| 533 | } |
| 534 | X509_free(tlsp->peercert); |
| 535 | tlsp->peercert = old_cert; |
| 536 | } |
| 537 | return 0; |
| 538 | } |
| 539 | #endif |
| 540 | |
| 541 | /************************************************* |
| 542 | * Callback for verification * |
| 543 | *************************************************/ |
| 544 | |
| 545 | /* The SSL library does certificate verification if set up to do so. This |
| 546 | callback has the current yes/no state is in "state". If verification succeeded, |
| 547 | we set the certificate-verified flag. If verification failed, what happens |
| 548 | depends on whether the client is required to present a verifiable certificate |
| 549 | or not. |
| 550 | |
| 551 | If verification is optional, we change the state to yes, but still log the |
| 552 | verification error. For some reason (it really would help to have proper |
| 553 | documentation of OpenSSL), this callback function then gets called again, this |
| 554 | time with state = 1. We must take care not to set the private verified flag on |
| 555 | the second time through. |
| 556 | |
| 557 | Note: this function is not called if the client fails to present a certificate |
| 558 | when asked. We get here only if a certificate has been received. Handling of |
| 559 | optional verification for this case is done when requesting SSL to verify, by |
| 560 | setting SSL_VERIFY_FAIL_IF_NO_PEER_CERT in the non-optional case. |
| 561 | |
| 562 | May be called multiple times for different issues with a certificate, even |
| 563 | for a given "depth" in the certificate chain. |
| 564 | |
| 565 | Arguments: |
| 566 | preverify_ok current yes/no state as 1/0 |
| 567 | x509ctx certificate information. |
| 568 | tlsp per-direction (client vs. server) support data |
| 569 | calledp has-been-called flag |
| 570 | optionalp verification-is-optional flag |
| 571 | |
| 572 | Returns: 0 if verification should fail, otherwise 1 |
| 573 | */ |
| 574 | |
| 575 | static int |
| 576 | verify_callback(int preverify_ok, X509_STORE_CTX * x509ctx, |
| 577 | tls_support * tlsp, BOOL * calledp, BOOL * optionalp) |
| 578 | { |
| 579 | X509 * cert = X509_STORE_CTX_get_current_cert(x509ctx); |
| 580 | int depth = X509_STORE_CTX_get_error_depth(x509ctx); |
| 581 | uschar dn[256]; |
| 582 | |
| 583 | if (!X509_NAME_oneline(X509_get_subject_name(cert), CS dn, sizeof(dn))) |
| 584 | { |
| 585 | DEBUG(D_tls) debug_printf("X509_NAME_oneline() error\n"); |
| 586 | log_write(0, LOG_MAIN, "[%s] SSL verify error: internal error", |
| 587 | tlsp == &tls_out ? deliver_host_address : sender_host_address); |
| 588 | return 0; |
| 589 | } |
| 590 | dn[sizeof(dn)-1] = '\0'; |
| 591 | |
| 592 | tlsp->verify_override = FALSE; |
| 593 | if (preverify_ok == 0) |
| 594 | { |
| 595 | uschar * extra = verify_mode ? string_sprintf(" (during %c-verify for [%s])", |
| 596 | *verify_mode, sender_host_address) |
| 597 | : US""; |
| 598 | log_write(0, LOG_MAIN, "[%s] SSL verify error%s: depth=%d error=%s cert=%s", |
| 599 | tlsp == &tls_out ? deliver_host_address : sender_host_address, |
| 600 | extra, depth, |
| 601 | X509_verify_cert_error_string(X509_STORE_CTX_get_error(x509ctx)), dn); |
| 602 | *calledp = TRUE; |
| 603 | if (!*optionalp) |
| 604 | { |
| 605 | if (!tlsp->peercert) |
| 606 | tlsp->peercert = X509_dup(cert); /* record failing cert */ |
| 607 | return 0; /* reject */ |
| 608 | } |
| 609 | DEBUG(D_tls) debug_printf("SSL verify failure overridden (host in " |
| 610 | "tls_try_verify_hosts)\n"); |
| 611 | tlsp->verify_override = TRUE; |
| 612 | } |
| 613 | |
| 614 | else if (depth != 0) |
| 615 | { |
| 616 | DEBUG(D_tls) debug_printf("SSL verify ok: depth=%d SN=%s\n", depth, dn); |
| 617 | #ifndef DISABLE_OCSP |
| 618 | if (tlsp == &tls_out && client_static_cbinfo->u_ocsp.client.verify_store) |
| 619 | { /* client, wanting stapling */ |
| 620 | /* Add the server cert's signing chain as the one |
| 621 | for the verification of the OCSP stapled information. */ |
| 622 | |
| 623 | if (!X509_STORE_add_cert(client_static_cbinfo->u_ocsp.client.verify_store, |
| 624 | cert)) |
| 625 | ERR_clear_error(); |
| 626 | sk_X509_push(client_static_cbinfo->verify_stack, cert); |
| 627 | } |
| 628 | #endif |
| 629 | #ifndef DISABLE_EVENT |
| 630 | if (verify_event(tlsp, cert, depth, dn, calledp, optionalp, US"SSL")) |
| 631 | return 0; /* reject, with peercert set */ |
| 632 | #endif |
| 633 | } |
| 634 | else |
| 635 | { |
| 636 | const uschar * verify_cert_hostnames; |
| 637 | |
| 638 | if ( tlsp == &tls_out |
| 639 | && ((verify_cert_hostnames = client_static_cbinfo->verify_cert_hostnames))) |
| 640 | /* client, wanting hostname check */ |
| 641 | { |
| 642 | |
| 643 | #ifdef EXIM_HAVE_OPENSSL_CHECKHOST |
| 644 | # ifndef X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS |
| 645 | # define X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS 0 |
| 646 | # endif |
| 647 | # ifndef X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS |
| 648 | # define X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS 0 |
| 649 | # endif |
| 650 | int sep = 0; |
| 651 | const uschar * list = verify_cert_hostnames; |
| 652 | uschar * name; |
| 653 | int rc; |
| 654 | while ((name = string_nextinlist(&list, &sep, NULL, 0))) |
| 655 | if ((rc = X509_check_host(cert, CCS name, 0, |
| 656 | X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS |
| 657 | | X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS, |
| 658 | NULL))) |
| 659 | { |
| 660 | if (rc < 0) |
| 661 | { |
| 662 | log_write(0, LOG_MAIN, "[%s] SSL verify error: internal error", |
| 663 | tlsp == &tls_out ? deliver_host_address : sender_host_address); |
| 664 | name = NULL; |
| 665 | } |
| 666 | break; |
| 667 | } |
| 668 | if (!name) |
| 669 | #else |
| 670 | if (!tls_is_name_for_cert(verify_cert_hostnames, cert)) |
| 671 | #endif |
| 672 | { |
| 673 | uschar * extra = verify_mode |
| 674 | ? string_sprintf(" (during %c-verify for [%s])", |
| 675 | *verify_mode, sender_host_address) |
| 676 | : US""; |
| 677 | log_write(0, LOG_MAIN, |
| 678 | "[%s] SSL verify error%s: certificate name mismatch: DN=\"%s\" H=\"%s\"", |
| 679 | tlsp == &tls_out ? deliver_host_address : sender_host_address, |
| 680 | extra, dn, verify_cert_hostnames); |
| 681 | *calledp = TRUE; |
| 682 | if (!*optionalp) |
| 683 | { |
| 684 | if (!tlsp->peercert) |
| 685 | tlsp->peercert = X509_dup(cert); /* record failing cert */ |
| 686 | return 0; /* reject */ |
| 687 | } |
| 688 | DEBUG(D_tls) debug_printf("SSL verify name failure overridden (host in " |
| 689 | "tls_try_verify_hosts)\n"); |
| 690 | tlsp->verify_override = TRUE; |
| 691 | } |
| 692 | } |
| 693 | |
| 694 | #ifndef DISABLE_EVENT |
| 695 | if (verify_event(tlsp, cert, depth, dn, calledp, optionalp, US"SSL")) |
| 696 | return 0; /* reject, with peercert set */ |
| 697 | #endif |
| 698 | |
| 699 | DEBUG(D_tls) debug_printf("SSL%s verify ok: depth=0 SN=%s\n", |
| 700 | *calledp ? "" : " authenticated", dn); |
| 701 | *calledp = TRUE; |
| 702 | } |
| 703 | |
| 704 | return 1; /* accept, at least for this level */ |
| 705 | } |
| 706 | |
| 707 | static int |
| 708 | verify_callback_client(int preverify_ok, X509_STORE_CTX *x509ctx) |
| 709 | { |
| 710 | return verify_callback(preverify_ok, x509ctx, &tls_out, |
| 711 | &client_verify_callback_called, &client_verify_optional); |
| 712 | } |
| 713 | |
| 714 | static int |
| 715 | verify_callback_server(int preverify_ok, X509_STORE_CTX *x509ctx) |
| 716 | { |
| 717 | return verify_callback(preverify_ok, x509ctx, &tls_in, |
| 718 | &server_verify_callback_called, &server_verify_optional); |
| 719 | } |
| 720 | |
| 721 | |
| 722 | #ifdef SUPPORT_DANE |
| 723 | |
| 724 | /* This gets called *by* the dane library verify callback, which interposes |
| 725 | itself. |
| 726 | */ |
| 727 | static int |
| 728 | verify_callback_client_dane(int preverify_ok, X509_STORE_CTX * x509ctx) |
| 729 | { |
| 730 | X509 * cert = X509_STORE_CTX_get_current_cert(x509ctx); |
| 731 | uschar dn[256]; |
| 732 | int depth = X509_STORE_CTX_get_error_depth(x509ctx); |
| 733 | #ifndef DISABLE_EVENT |
| 734 | BOOL dummy_called, optional = FALSE; |
| 735 | #endif |
| 736 | |
| 737 | if (!X509_NAME_oneline(X509_get_subject_name(cert), CS dn, sizeof(dn))) |
| 738 | { |
| 739 | DEBUG(D_tls) debug_printf("X509_NAME_oneline() error\n"); |
| 740 | log_write(0, LOG_MAIN, "[%s] SSL verify error: internal error", |
| 741 | deliver_host_address); |
| 742 | return 0; |
| 743 | } |
| 744 | dn[sizeof(dn)-1] = '\0'; |
| 745 | |
| 746 | DEBUG(D_tls) debug_printf("verify_callback_client_dane: %s depth %d %s\n", |
| 747 | preverify_ok ? "ok":"BAD", depth, dn); |
| 748 | |
| 749 | #ifndef DISABLE_EVENT |
| 750 | if (verify_event(&tls_out, cert, depth, dn, |
| 751 | &dummy_called, &optional, US"DANE")) |
| 752 | return 0; /* reject, with peercert set */ |
| 753 | #endif |
| 754 | |
| 755 | if (preverify_ok == 1) |
| 756 | { |
| 757 | tls_out.dane_verified = TRUE; |
| 758 | #ifndef DISABLE_OCSP |
| 759 | if (client_static_cbinfo->u_ocsp.client.verify_store) |
| 760 | { /* client, wanting stapling */ |
| 761 | /* Add the server cert's signing chain as the one |
| 762 | for the verification of the OCSP stapled information. */ |
| 763 | |
| 764 | if (!X509_STORE_add_cert(client_static_cbinfo->u_ocsp.client.verify_store, |
| 765 | cert)) |
| 766 | ERR_clear_error(); |
| 767 | sk_X509_push(client_static_cbinfo->verify_stack, cert); |
| 768 | } |
| 769 | #endif |
| 770 | } |
| 771 | else |
| 772 | { |
| 773 | int err = X509_STORE_CTX_get_error(x509ctx); |
| 774 | DEBUG(D_tls) |
| 775 | debug_printf(" - err %d '%s'\n", err, X509_verify_cert_error_string(err)); |
| 776 | if (err == X509_V_ERR_APPLICATION_VERIFICATION) |
| 777 | preverify_ok = 1; |
| 778 | } |
| 779 | return preverify_ok; |
| 780 | } |
| 781 | |
| 782 | #endif /*SUPPORT_DANE*/ |
| 783 | |
| 784 | |
| 785 | /************************************************* |
| 786 | * Information callback * |
| 787 | *************************************************/ |
| 788 | |
| 789 | /* The SSL library functions call this from time to time to indicate what they |
| 790 | are doing. We copy the string to the debugging output when TLS debugging has |
| 791 | been requested. |
| 792 | |
| 793 | Arguments: |
| 794 | s the SSL connection |
| 795 | where |
| 796 | ret |
| 797 | |
| 798 | Returns: nothing |
| 799 | */ |
| 800 | |
| 801 | static void |
| 802 | info_callback(SSL *s, int where, int ret) |
| 803 | { |
| 804 | DEBUG(D_tls) |
| 805 | { |
| 806 | const uschar * str; |
| 807 | |
| 808 | if (where & SSL_ST_CONNECT) |
| 809 | str = US"SSL_connect"; |
| 810 | else if (where & SSL_ST_ACCEPT) |
| 811 | str = US"SSL_accept"; |
| 812 | else |
| 813 | str = US"SSL info (undefined)"; |
| 814 | |
| 815 | if (where & SSL_CB_LOOP) |
| 816 | debug_printf("%s: %s\n", str, SSL_state_string_long(s)); |
| 817 | else if (where & SSL_CB_ALERT) |
| 818 | debug_printf("SSL3 alert %s:%s:%s\n", |
| 819 | str = where & SSL_CB_READ ? US"read" : US"write", |
| 820 | SSL_alert_type_string_long(ret), SSL_alert_desc_string_long(ret)); |
| 821 | else if (where & SSL_CB_EXIT) |
| 822 | if (ret == 0) |
| 823 | debug_printf("%s: failed in %s\n", str, SSL_state_string_long(s)); |
| 824 | else if (ret < 0) |
| 825 | debug_printf("%s: error in %s\n", str, SSL_state_string_long(s)); |
| 826 | else if (where & SSL_CB_HANDSHAKE_START) |
| 827 | debug_printf("%s: hshake start: %s\n", str, SSL_state_string_long(s)); |
| 828 | else if (where & SSL_CB_HANDSHAKE_DONE) |
| 829 | debug_printf("%s: hshake done: %s\n", str, SSL_state_string_long(s)); |
| 830 | } |
| 831 | } |
| 832 | |
| 833 | #ifdef OPENSSL_HAVE_KEYLOG_CB |
| 834 | static void |
| 835 | keylog_callback(const SSL *ssl, const char *line) |
| 836 | { |
| 837 | DEBUG(D_tls) debug_printf("%.200s\n", line); |
| 838 | } |
| 839 | #endif |
| 840 | |
| 841 | |
| 842 | #ifdef EXPERIMENTAL_TLS_RESUME |
| 843 | /* Manage the keysets used for encrypting the session tickets, on the server. */ |
| 844 | |
| 845 | typedef struct { /* Session ticket encryption key */ |
| 846 | uschar name[16]; |
| 847 | |
| 848 | const EVP_CIPHER * aes_cipher; |
| 849 | uschar aes_key[32]; /* size needed depends on cipher. aes_128 implies 128/8 = 16? */ |
| 850 | const EVP_MD * hmac_hash; |
| 851 | uschar hmac_key[16]; |
| 852 | time_t renew; |
| 853 | time_t expire; |
| 854 | } exim_stek; |
| 855 | |
| 856 | static exim_stek exim_tk; /* current key */ |
| 857 | static exim_stek exim_tk_old; /* previous key */ |
| 858 | |
| 859 | static void |
| 860 | tk_init(void) |
| 861 | { |
| 862 | time_t t = time(NULL); |
| 863 | |
| 864 | if (exim_tk.name[0]) |
| 865 | { |
| 866 | if (exim_tk.renew >= t) return; |
| 867 | exim_tk_old = exim_tk; |
| 868 | } |
| 869 | |
| 870 | if (f.running_in_test_harness) ssl_session_timeout = 6; |
| 871 | |
| 872 | DEBUG(D_tls) debug_printf("OpenSSL: %s STEK\n", exim_tk.name[0] ? "rotating" : "creating"); |
| 873 | if (RAND_bytes(exim_tk.aes_key, sizeof(exim_tk.aes_key)) <= 0) return; |
| 874 | if (RAND_bytes(exim_tk.hmac_key, sizeof(exim_tk.hmac_key)) <= 0) return; |
| 875 | if (RAND_bytes(exim_tk.name+1, sizeof(exim_tk.name)-1) <= 0) return; |
| 876 | |
| 877 | exim_tk.name[0] = 'E'; |
| 878 | exim_tk.aes_cipher = EVP_aes_256_cbc(); |
| 879 | exim_tk.hmac_hash = EVP_sha256(); |
| 880 | exim_tk.expire = t + ssl_session_timeout; |
| 881 | exim_tk.renew = t + ssl_session_timeout/2; |
| 882 | } |
| 883 | |
| 884 | static exim_stek * |
| 885 | tk_current(void) |
| 886 | { |
| 887 | if (!exim_tk.name[0]) return NULL; |
| 888 | return &exim_tk; |
| 889 | } |
| 890 | |
| 891 | static exim_stek * |
| 892 | tk_find(const uschar * name) |
| 893 | { |
| 894 | return memcmp(name, exim_tk.name, sizeof(exim_tk.name)) == 0 ? &exim_tk |
| 895 | : memcmp(name, exim_tk_old.name, sizeof(exim_tk_old.name)) == 0 ? &exim_tk_old |
| 896 | : NULL; |
| 897 | } |
| 898 | |
| 899 | /* Callback for session tickets, on server */ |
| 900 | static int |
| 901 | ticket_key_callback(SSL * ssl, uschar key_name[16], |
| 902 | uschar * iv, EVP_CIPHER_CTX * ctx, HMAC_CTX * hctx, int enc) |
| 903 | { |
| 904 | tls_support * tlsp = server_static_cbinfo->tlsp; |
| 905 | exim_stek * key; |
| 906 | |
| 907 | if (enc) |
| 908 | { |
| 909 | DEBUG(D_tls) debug_printf("ticket_key_callback: create new session\n"); |
| 910 | tlsp->resumption |= RESUME_CLIENT_REQUESTED; |
| 911 | |
| 912 | if (RAND_bytes(iv, EVP_MAX_IV_LENGTH) <= 0) |
| 913 | return -1; /* insufficient random */ |
| 914 | |
| 915 | if (!(key = tk_current())) /* current key doesn't exist or isn't valid */ |
| 916 | return 0; /* key couldn't be created */ |
| 917 | memcpy(key_name, key->name, 16); |
| 918 | DEBUG(D_tls) debug_printf("STEK expire " TIME_T_FMT "\n", key->expire - time(NULL)); |
| 919 | |
| 920 | /*XXX will want these dependent on the ssl session strength */ |
| 921 | HMAC_Init_ex(hctx, key->hmac_key, sizeof(key->hmac_key), |
| 922 | key->hmac_hash, NULL); |
| 923 | EVP_EncryptInit_ex(ctx, key->aes_cipher, NULL, key->aes_key, iv); |
| 924 | |
| 925 | DEBUG(D_tls) debug_printf("ticket created\n"); |
| 926 | return 1; |
| 927 | } |
| 928 | else |
| 929 | { |
| 930 | time_t now = time(NULL); |
| 931 | |
| 932 | DEBUG(D_tls) debug_printf("ticket_key_callback: retrieve session\n"); |
| 933 | tlsp->resumption |= RESUME_CLIENT_SUGGESTED; |
| 934 | |
| 935 | if (!(key = tk_find(key_name)) || key->expire < now) |
| 936 | { |
| 937 | DEBUG(D_tls) |
| 938 | { |
| 939 | debug_printf("ticket not usable (%s)\n", key ? "expired" : "not found"); |
| 940 | if (key) debug_printf("STEK expire " TIME_T_FMT "\n", key->expire - now); |
| 941 | } |
| 942 | return 0; |
| 943 | } |
| 944 | |
| 945 | HMAC_Init_ex(hctx, key->hmac_key, sizeof(key->hmac_key), |
| 946 | key->hmac_hash, NULL); |
| 947 | EVP_DecryptInit_ex(ctx, key->aes_cipher, NULL, key->aes_key, iv); |
| 948 | |
| 949 | DEBUG(D_tls) debug_printf("ticket usable, STEK expire " TIME_T_FMT "\n", key->expire - now); |
| 950 | |
| 951 | /* The ticket lifetime and renewal are the same as the STEK lifetime and |
| 952 | renewal, which is overenthusiastic. A factor of, say, 3x longer STEK would |
| 953 | be better. To do that we'd have to encode ticket lifetime in the name as |
| 954 | we don't yet see the restored session. Could check posthandshake for TLS1.3 |
| 955 | and trigger a new ticket then, but cannot do that for TLS1.2 */ |
| 956 | return key->renew < now ? 2 : 1; |
| 957 | } |
| 958 | } |
| 959 | #endif |
| 960 | |
| 961 | |
| 962 | |
| 963 | /************************************************* |
| 964 | * Initialize for DH * |
| 965 | *************************************************/ |
| 966 | |
| 967 | /* If dhparam is set, expand it, and load up the parameters for DH encryption. |
| 968 | |
| 969 | Arguments: |
| 970 | sctx The current SSL CTX (inbound or outbound) |
| 971 | dhparam DH parameter file or fixed parameter identity string |
| 972 | host connected host, if client; NULL if server |
| 973 | errstr error string pointer |
| 974 | |
| 975 | Returns: TRUE if OK (nothing to set up, or setup worked) |
| 976 | */ |
| 977 | |
| 978 | static BOOL |
| 979 | init_dh(SSL_CTX *sctx, uschar *dhparam, const host_item *host, uschar ** errstr) |
| 980 | { |
| 981 | BIO *bio; |
| 982 | DH *dh; |
| 983 | uschar *dhexpanded; |
| 984 | const char *pem; |
| 985 | int dh_bitsize; |
| 986 | |
| 987 | if (!expand_check(dhparam, US"tls_dhparam", &dhexpanded, errstr)) |
| 988 | return FALSE; |
| 989 | |
| 990 | if (!dhexpanded || !*dhexpanded) |
| 991 | bio = BIO_new_mem_buf(CS std_dh_prime_default(), -1); |
| 992 | else if (dhexpanded[0] == '/') |
| 993 | { |
| 994 | if (!(bio = BIO_new_file(CS dhexpanded, "r"))) |
| 995 | { |
| 996 | tls_error(string_sprintf("could not read dhparams file %s", dhexpanded), |
| 997 | host, US strerror(errno), errstr); |
| 998 | return FALSE; |
| 999 | } |
| 1000 | } |
| 1001 | else |
| 1002 | { |
| 1003 | if (Ustrcmp(dhexpanded, "none") == 0) |
| 1004 | { |
| 1005 | DEBUG(D_tls) debug_printf("Requested no DH parameters.\n"); |
| 1006 | return TRUE; |
| 1007 | } |
| 1008 | |
| 1009 | if (!(pem = std_dh_prime_named(dhexpanded))) |
| 1010 | { |
| 1011 | tls_error(string_sprintf("Unknown standard DH prime \"%s\"", dhexpanded), |
| 1012 | host, US strerror(errno), errstr); |
| 1013 | return FALSE; |
| 1014 | } |
| 1015 | bio = BIO_new_mem_buf(CS pem, -1); |
| 1016 | } |
| 1017 | |
| 1018 | if (!(dh = PEM_read_bio_DHparams(bio, NULL, NULL, NULL))) |
| 1019 | { |
| 1020 | BIO_free(bio); |
| 1021 | tls_error(string_sprintf("Could not read tls_dhparams \"%s\"", dhexpanded), |
| 1022 | host, NULL, errstr); |
| 1023 | return FALSE; |
| 1024 | } |
| 1025 | |
| 1026 | /* note: our default limit of 2236 is not a multiple of 8; the limit comes from |
| 1027 | * an NSS limit, and the GnuTLS APIs handle bit-sizes fine, so we went with |
| 1028 | * 2236. But older OpenSSL can only report in bytes (octets), not bits. |
| 1029 | * If someone wants to dance at the edge, then they can raise the limit or use |
| 1030 | * current libraries. */ |
| 1031 | #ifdef EXIM_HAVE_OPENSSL_DH_BITS |
| 1032 | /* Added in commit 26c79d5641d; `git describe --contains` says OpenSSL_1_1_0-pre1~1022 |
| 1033 | * This predates OpenSSL_1_1_0 (before a, b, ...) so is in all 1.1.0 */ |
| 1034 | dh_bitsize = DH_bits(dh); |
| 1035 | #else |
| 1036 | dh_bitsize = 8 * DH_size(dh); |
| 1037 | #endif |
| 1038 | |
| 1039 | /* Even if it is larger, we silently return success rather than cause things |
| 1040 | * to fail out, so that a too-large DH will not knock out all TLS; it's a |
| 1041 | * debatable choice. */ |
| 1042 | if (dh_bitsize > tls_dh_max_bits) |
| 1043 | { |
| 1044 | DEBUG(D_tls) |
| 1045 | debug_printf("dhparams file %d bits, is > tls_dh_max_bits limit of %d\n", |
| 1046 | dh_bitsize, tls_dh_max_bits); |
| 1047 | } |
| 1048 | else |
| 1049 | { |
| 1050 | SSL_CTX_set_tmp_dh(sctx, dh); |
| 1051 | DEBUG(D_tls) |
| 1052 | debug_printf("Diffie-Hellman initialized from %s with %d-bit prime\n", |
| 1053 | dhexpanded ? dhexpanded : US"default", dh_bitsize); |
| 1054 | } |
| 1055 | |
| 1056 | DH_free(dh); |
| 1057 | BIO_free(bio); |
| 1058 | |
| 1059 | return TRUE; |
| 1060 | } |
| 1061 | |
| 1062 | |
| 1063 | |
| 1064 | |
| 1065 | /************************************************* |
| 1066 | * Initialize for ECDH * |
| 1067 | *************************************************/ |
| 1068 | |
| 1069 | /* Load parameters for ECDH encryption. |
| 1070 | |
| 1071 | For now, we stick to NIST P-256 because: it's simple and easy to configure; |
| 1072 | it avoids any patent issues that might bite redistributors; despite events in |
| 1073 | the news and concerns over curve choices, we're not cryptographers, we're not |
| 1074 | pretending to be, and this is "good enough" to be better than no support, |
| 1075 | protecting against most adversaries. Given another year or two, there might |
| 1076 | be sufficient clarity about a "right" way forward to let us make an informed |
| 1077 | decision, instead of a knee-jerk reaction. |
| 1078 | |
| 1079 | Longer-term, we should look at supporting both various named curves and |
| 1080 | external files generated with "openssl ecparam", much as we do for init_dh(). |
| 1081 | We should also support "none" as a value, to explicitly avoid initialisation. |
| 1082 | |
| 1083 | Patches welcome. |
| 1084 | |
| 1085 | Arguments: |
| 1086 | sctx The current SSL CTX (inbound or outbound) |
| 1087 | host connected host, if client; NULL if server |
| 1088 | errstr error string pointer |
| 1089 | |
| 1090 | Returns: TRUE if OK (nothing to set up, or setup worked) |
| 1091 | */ |
| 1092 | |
| 1093 | static BOOL |
| 1094 | init_ecdh(SSL_CTX * sctx, host_item * host, uschar ** errstr) |
| 1095 | { |
| 1096 | #ifdef OPENSSL_NO_ECDH |
| 1097 | return TRUE; |
| 1098 | #else |
| 1099 | |
| 1100 | EC_KEY * ecdh; |
| 1101 | uschar * exp_curve; |
| 1102 | int nid; |
| 1103 | BOOL rv; |
| 1104 | |
| 1105 | if (host) /* No ECDH setup for clients, only for servers */ |
| 1106 | return TRUE; |
| 1107 | |
| 1108 | # ifndef EXIM_HAVE_ECDH |
| 1109 | DEBUG(D_tls) |
| 1110 | debug_printf("No OpenSSL API to define ECDH parameters, skipping\n"); |
| 1111 | return TRUE; |
| 1112 | # else |
| 1113 | |
| 1114 | if (!expand_check(tls_eccurve, US"tls_eccurve", &exp_curve, errstr)) |
| 1115 | return FALSE; |
| 1116 | if (!exp_curve || !*exp_curve) |
| 1117 | return TRUE; |
| 1118 | |
| 1119 | /* "auto" needs to be handled carefully. |
| 1120 | * OpenSSL < 1.0.2: we do not select anything, but fallback to prime256v1 |
| 1121 | * OpenSSL < 1.1.0: we have to call SSL_CTX_set_ecdh_auto |
| 1122 | * (openssl/ssl.h defines SSL_CTRL_SET_ECDH_AUTO) |
| 1123 | * OpenSSL >= 1.1.0: we do not set anything, the libray does autoselection |
| 1124 | * https://github.com/openssl/openssl/commit/fe6ef2472db933f01b59cad82aa925736935984b |
| 1125 | */ |
| 1126 | if (Ustrcmp(exp_curve, "auto") == 0) |
| 1127 | { |
| 1128 | #if OPENSSL_VERSION_NUMBER < 0x10002000L |
| 1129 | DEBUG(D_tls) debug_printf( |
| 1130 | "ECDH OpenSSL < 1.0.2: temp key parameter settings: overriding \"auto\" with \"prime256v1\"\n"); |
| 1131 | exp_curve = US"prime256v1"; |
| 1132 | #else |
| 1133 | # if defined SSL_CTRL_SET_ECDH_AUTO |
| 1134 | DEBUG(D_tls) debug_printf( |
| 1135 | "ECDH OpenSSL 1.0.2+ temp key parameter settings: autoselection\n"); |
| 1136 | SSL_CTX_set_ecdh_auto(sctx, 1); |
| 1137 | return TRUE; |
| 1138 | # else |
| 1139 | DEBUG(D_tls) debug_printf( |
| 1140 | "ECDH OpenSSL 1.1.0+ temp key parameter settings: default selection\n"); |
| 1141 | return TRUE; |
| 1142 | # endif |
| 1143 | #endif |
| 1144 | } |
| 1145 | |
| 1146 | DEBUG(D_tls) debug_printf("ECDH: curve '%s'\n", exp_curve); |
| 1147 | if ( (nid = OBJ_sn2nid (CCS exp_curve)) == NID_undef |
| 1148 | # ifdef EXIM_HAVE_OPENSSL_EC_NIST2NID |
| 1149 | && (nid = EC_curve_nist2nid(CCS exp_curve)) == NID_undef |
| 1150 | # endif |
| 1151 | ) |
| 1152 | { |
| 1153 | tls_error(string_sprintf("Unknown curve name tls_eccurve '%s'", exp_curve), |
| 1154 | host, NULL, errstr); |
| 1155 | return FALSE; |
| 1156 | } |
| 1157 | |
| 1158 | if (!(ecdh = EC_KEY_new_by_curve_name(nid))) |
| 1159 | { |
| 1160 | tls_error(US"Unable to create ec curve", host, NULL, errstr); |
| 1161 | return FALSE; |
| 1162 | } |
| 1163 | |
| 1164 | /* The "tmp" in the name here refers to setting a temporary key |
| 1165 | not to the stability of the interface. */ |
| 1166 | |
| 1167 | if ((rv = SSL_CTX_set_tmp_ecdh(sctx, ecdh) == 0)) |
| 1168 | tls_error(string_sprintf("Error enabling '%s' curve", exp_curve), host, NULL, errstr); |
| 1169 | else |
| 1170 | DEBUG(D_tls) debug_printf("ECDH: enabled '%s' curve\n", exp_curve); |
| 1171 | |
| 1172 | EC_KEY_free(ecdh); |
| 1173 | return !rv; |
| 1174 | |
| 1175 | # endif /*EXIM_HAVE_ECDH*/ |
| 1176 | #endif /*OPENSSL_NO_ECDH*/ |
| 1177 | } |
| 1178 | |
| 1179 | |
| 1180 | |
| 1181 | |
| 1182 | #ifndef DISABLE_OCSP |
| 1183 | /************************************************* |
| 1184 | * Load OCSP information into state * |
| 1185 | *************************************************/ |
| 1186 | /* Called to load the server OCSP response from the given file into memory, once |
| 1187 | caller has determined this is needed. Checks validity. Debugs a message |
| 1188 | if invalid. |
| 1189 | |
| 1190 | ASSUMES: single response, for single cert. |
| 1191 | |
| 1192 | Arguments: |
| 1193 | sctx the SSL_CTX* to update |
| 1194 | cbinfo various parts of session state |
| 1195 | expanded the filename putatively holding an OCSP response |
| 1196 | |
| 1197 | */ |
| 1198 | |
| 1199 | static void |
| 1200 | ocsp_load_response(SSL_CTX *sctx, tls_ext_ctx_cb *cbinfo, const uschar *expanded) |
| 1201 | { |
| 1202 | BIO * bio; |
| 1203 | OCSP_RESPONSE * resp; |
| 1204 | OCSP_BASICRESP * basic_response; |
| 1205 | OCSP_SINGLERESP * single_response; |
| 1206 | ASN1_GENERALIZEDTIME * rev, * thisupd, * nextupd; |
| 1207 | STACK_OF(X509) * sk; |
| 1208 | unsigned long verify_flags; |
| 1209 | int status, reason, i; |
| 1210 | |
| 1211 | cbinfo->u_ocsp.server.file_expanded = string_copy(expanded); |
| 1212 | if (cbinfo->u_ocsp.server.response) |
| 1213 | { |
| 1214 | OCSP_RESPONSE_free(cbinfo->u_ocsp.server.response); |
| 1215 | cbinfo->u_ocsp.server.response = NULL; |
| 1216 | } |
| 1217 | |
| 1218 | if (!(bio = BIO_new_file(CS cbinfo->u_ocsp.server.file_expanded, "rb"))) |
| 1219 | { |
| 1220 | DEBUG(D_tls) debug_printf("Failed to open OCSP response file \"%s\"\n", |
| 1221 | cbinfo->u_ocsp.server.file_expanded); |
| 1222 | return; |
| 1223 | } |
| 1224 | |
| 1225 | resp = d2i_OCSP_RESPONSE_bio(bio, NULL); |
| 1226 | BIO_free(bio); |
| 1227 | if (!resp) |
| 1228 | { |
| 1229 | DEBUG(D_tls) debug_printf("Error reading OCSP response.\n"); |
| 1230 | return; |
| 1231 | } |
| 1232 | |
| 1233 | if ((status = OCSP_response_status(resp)) != OCSP_RESPONSE_STATUS_SUCCESSFUL) |
| 1234 | { |
| 1235 | DEBUG(D_tls) debug_printf("OCSP response not valid: %s (%d)\n", |
| 1236 | OCSP_response_status_str(status), status); |
| 1237 | goto bad; |
| 1238 | } |
| 1239 | |
| 1240 | if (!(basic_response = OCSP_response_get1_basic(resp))) |
| 1241 | { |
| 1242 | DEBUG(D_tls) |
| 1243 | debug_printf("OCSP response parse error: unable to extract basic response.\n"); |
| 1244 | goto bad; |
| 1245 | } |
| 1246 | |
| 1247 | sk = cbinfo->verify_stack; |
| 1248 | verify_flags = OCSP_NOVERIFY; /* check sigs, but not purpose */ |
| 1249 | |
| 1250 | /* May need to expose ability to adjust those flags? |
| 1251 | OCSP_NOSIGS OCSP_NOVERIFY OCSP_NOCHAIN OCSP_NOCHECKS OCSP_NOEXPLICIT |
| 1252 | OCSP_TRUSTOTHER OCSP_NOINTERN */ |
| 1253 | |
| 1254 | /* This does a full verify on the OCSP proof before we load it for serving |
| 1255 | up; possibly overkill - just date-checks might be nice enough. |
| 1256 | |
| 1257 | OCSP_basic_verify takes a "store" arg, but does not |
| 1258 | use it for the chain verification, which is all we do |
| 1259 | when OCSP_NOVERIFY is set. The content from the wire |
| 1260 | "basic_response" and a cert-stack "sk" are all that is used. |
| 1261 | |
| 1262 | We have a stack, loaded in setup_certs() if tls_verify_certificates |
| 1263 | was a file (not a directory, or "system"). It is unfortunate we |
| 1264 | cannot used the connection context store, as that would neatly |
| 1265 | handle the "system" case too, but there seems to be no library |
| 1266 | function for getting a stack from a store. |
| 1267 | [ In OpenSSL 1.1 - ? X509_STORE_CTX_get0_chain(ctx) ? ] |
| 1268 | We do not free the stack since it could be needed a second time for |
| 1269 | SNI handling. |
| 1270 | |
| 1271 | Separately we might try to replace using OCSP_basic_verify() - which seems to not |
| 1272 | be a public interface into the OpenSSL library (there's no manual entry) - |
| 1273 | But what with? We also use OCSP_basic_verify in the client stapling callback. |
| 1274 | And there we NEED it; we must verify that status... unless the |
| 1275 | library does it for us anyway? */ |
| 1276 | |
| 1277 | if ((i = OCSP_basic_verify(basic_response, sk, NULL, verify_flags)) < 0) |
| 1278 | { |
| 1279 | DEBUG(D_tls) |
| 1280 | { |
| 1281 | ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring)); |
| 1282 | debug_printf("OCSP response verify failure: %s\n", US ssl_errstring); |
| 1283 | } |
| 1284 | goto bad; |
| 1285 | } |
| 1286 | |
| 1287 | /* Here's the simplifying assumption: there's only one response, for the |
| 1288 | one certificate we use, and nothing for anything else in a chain. If this |
| 1289 | proves false, we need to extract a cert id from our issued cert |
| 1290 | (tls_certificate) and use that for OCSP_resp_find_status() (which finds the |
| 1291 | right cert in the stack and then calls OCSP_single_get0_status()). |
| 1292 | |
| 1293 | I'm hoping to avoid reworking a bunch more of how we handle state here. */ |
| 1294 | |
| 1295 | if (!(single_response = OCSP_resp_get0(basic_response, 0))) |
| 1296 | { |
| 1297 | DEBUG(D_tls) |
| 1298 | debug_printf("Unable to get first response from OCSP basic response.\n"); |
| 1299 | goto bad; |
| 1300 | } |
| 1301 | |
| 1302 | status = OCSP_single_get0_status(single_response, &reason, &rev, &thisupd, &nextupd); |
| 1303 | if (status != V_OCSP_CERTSTATUS_GOOD) |
| 1304 | { |
| 1305 | DEBUG(D_tls) debug_printf("OCSP response bad cert status: %s (%d) %s (%d)\n", |
| 1306 | OCSP_cert_status_str(status), status, |
| 1307 | OCSP_crl_reason_str(reason), reason); |
| 1308 | goto bad; |
| 1309 | } |
| 1310 | |
| 1311 | if (!OCSP_check_validity(thisupd, nextupd, EXIM_OCSP_SKEW_SECONDS, EXIM_OCSP_MAX_AGE)) |
| 1312 | { |
| 1313 | DEBUG(D_tls) debug_printf("OCSP status invalid times.\n"); |
| 1314 | goto bad; |
| 1315 | } |
| 1316 | |
| 1317 | supply_response: |
| 1318 | /*XXX stack? (these tag points are for multiple leaf-cert support for ocsp */ |
| 1319 | cbinfo->u_ocsp.server.response = resp; |
| 1320 | return; |
| 1321 | |
| 1322 | bad: |
| 1323 | if (f.running_in_test_harness) |
| 1324 | { |
| 1325 | extern char ** environ; |
| 1326 | if (environ) for (uschar ** p = USS environ; *p; p++) |
| 1327 | if (Ustrncmp(*p, "EXIM_TESTHARNESS_DISABLE_OCSPVALIDITYCHECK", 42) == 0) |
| 1328 | { |
| 1329 | DEBUG(D_tls) debug_printf("Supplying known bad OCSP response\n"); |
| 1330 | goto supply_response; |
| 1331 | } |
| 1332 | } |
| 1333 | return; |
| 1334 | } |
| 1335 | #endif /*!DISABLE_OCSP*/ |
| 1336 | |
| 1337 | |
| 1338 | |
| 1339 | |
| 1340 | /* Create and install a selfsigned certificate, for use in server mode */ |
| 1341 | |
| 1342 | static int |
| 1343 | tls_install_selfsign(SSL_CTX * sctx, uschar ** errstr) |
| 1344 | { |
| 1345 | X509 * x509 = NULL; |
| 1346 | EVP_PKEY * pkey; |
| 1347 | RSA * rsa; |
| 1348 | X509_NAME * name; |
| 1349 | uschar * where; |
| 1350 | |
| 1351 | where = US"allocating pkey"; |
| 1352 | if (!(pkey = EVP_PKEY_new())) |
| 1353 | goto err; |
| 1354 | |
| 1355 | where = US"allocating cert"; |
| 1356 | if (!(x509 = X509_new())) |
| 1357 | goto err; |
| 1358 | |
| 1359 | where = US"generating pkey"; |
| 1360 | if (!(rsa = rsa_callback(NULL, 0, 2048))) |
| 1361 | goto err; |
| 1362 | |
| 1363 | where = US"assigning pkey"; |
| 1364 | if (!EVP_PKEY_assign_RSA(pkey, rsa)) |
| 1365 | goto err; |
| 1366 | |
| 1367 | X509_set_version(x509, 2); /* N+1 - version 3 */ |
| 1368 | ASN1_INTEGER_set(X509_get_serialNumber(x509), 1); |
| 1369 | X509_gmtime_adj(X509_get_notBefore(x509), 0); |
| 1370 | X509_gmtime_adj(X509_get_notAfter(x509), (long)60 * 60); /* 1 hour */ |
| 1371 | X509_set_pubkey(x509, pkey); |
| 1372 | |
| 1373 | name = X509_get_subject_name(x509); |
| 1374 | X509_NAME_add_entry_by_txt(name, "C", |
| 1375 | MBSTRING_ASC, CUS "UK", -1, -1, 0); |
| 1376 | X509_NAME_add_entry_by_txt(name, "O", |
| 1377 | MBSTRING_ASC, CUS "Exim Developers", -1, -1, 0); |
| 1378 | X509_NAME_add_entry_by_txt(name, "CN", |
| 1379 | MBSTRING_ASC, CUS smtp_active_hostname, -1, -1, 0); |
| 1380 | X509_set_issuer_name(x509, name); |
| 1381 | |
| 1382 | where = US"signing cert"; |
| 1383 | if (!X509_sign(x509, pkey, EVP_md5())) |
| 1384 | goto err; |
| 1385 | |
| 1386 | where = US"installing selfsign cert"; |
| 1387 | if (!SSL_CTX_use_certificate(sctx, x509)) |
| 1388 | goto err; |
| 1389 | |
| 1390 | where = US"installing selfsign key"; |
| 1391 | if (!SSL_CTX_use_PrivateKey(sctx, pkey)) |
| 1392 | goto err; |
| 1393 | |
| 1394 | return OK; |
| 1395 | |
| 1396 | err: |
| 1397 | (void) tls_error(where, NULL, NULL, errstr); |
| 1398 | if (x509) X509_free(x509); |
| 1399 | if (pkey) EVP_PKEY_free(pkey); |
| 1400 | return DEFER; |
| 1401 | } |
| 1402 | |
| 1403 | |
| 1404 | |
| 1405 | |
| 1406 | static int |
| 1407 | tls_add_certfile(SSL_CTX * sctx, tls_ext_ctx_cb * cbinfo, uschar * file, |
| 1408 | uschar ** errstr) |
| 1409 | { |
| 1410 | DEBUG(D_tls) debug_printf("tls_certificate file %s\n", file); |
| 1411 | if (!SSL_CTX_use_certificate_chain_file(sctx, CS file)) |
| 1412 | return tls_error(string_sprintf( |
| 1413 | "SSL_CTX_use_certificate_chain_file file=%s", file), |
| 1414 | cbinfo->host, NULL, errstr); |
| 1415 | return 0; |
| 1416 | } |
| 1417 | |
| 1418 | static int |
| 1419 | tls_add_pkeyfile(SSL_CTX * sctx, tls_ext_ctx_cb * cbinfo, uschar * file, |
| 1420 | uschar ** errstr) |
| 1421 | { |
| 1422 | DEBUG(D_tls) debug_printf("tls_privatekey file %s\n", file); |
| 1423 | if (!SSL_CTX_use_PrivateKey_file(sctx, CS file, SSL_FILETYPE_PEM)) |
| 1424 | return tls_error(string_sprintf( |
| 1425 | "SSL_CTX_use_PrivateKey_file file=%s", file), cbinfo->host, NULL, errstr); |
| 1426 | return 0; |
| 1427 | } |
| 1428 | |
| 1429 | |
| 1430 | /************************************************* |
| 1431 | * Expand key and cert file specs * |
| 1432 | *************************************************/ |
| 1433 | |
| 1434 | /* Called once during tls_init and possibly again during TLS setup, for a |
| 1435 | new context, if Server Name Indication was used and tls_sni was seen in |
| 1436 | the certificate string. |
| 1437 | |
| 1438 | Arguments: |
| 1439 | sctx the SSL_CTX* to update |
| 1440 | cbinfo various parts of session state |
| 1441 | errstr error string pointer |
| 1442 | |
| 1443 | Returns: OK/DEFER/FAIL |
| 1444 | */ |
| 1445 | |
| 1446 | static int |
| 1447 | tls_expand_session_files(SSL_CTX *sctx, tls_ext_ctx_cb *cbinfo, |
| 1448 | uschar ** errstr) |
| 1449 | { |
| 1450 | uschar *expanded; |
| 1451 | |
| 1452 | if (!cbinfo->certificate) |
| 1453 | { |
| 1454 | if (!cbinfo->is_server) /* client */ |
| 1455 | return OK; |
| 1456 | /* server */ |
| 1457 | if (tls_install_selfsign(sctx, errstr) != OK) |
| 1458 | return DEFER; |
| 1459 | } |
| 1460 | else |
| 1461 | { |
| 1462 | int err; |
| 1463 | |
| 1464 | if (Ustrstr(cbinfo->certificate, US"tls_sni") || |
| 1465 | Ustrstr(cbinfo->certificate, US"tls_in_sni") || |
| 1466 | Ustrstr(cbinfo->certificate, US"tls_out_sni") |
| 1467 | ) |
| 1468 | reexpand_tls_files_for_sni = TRUE; |
| 1469 | |
| 1470 | if (!expand_check(cbinfo->certificate, US"tls_certificate", &expanded, errstr)) |
| 1471 | return DEFER; |
| 1472 | |
| 1473 | if (expanded) |
| 1474 | if (cbinfo->is_server) |
| 1475 | { |
| 1476 | const uschar * file_list = expanded; |
| 1477 | int sep = 0; |
| 1478 | uschar * file; |
| 1479 | |
| 1480 | while (file = string_nextinlist(&file_list, &sep, NULL, 0)) |
| 1481 | if ((err = tls_add_certfile(sctx, cbinfo, file, errstr))) |
| 1482 | return err; |
| 1483 | } |
| 1484 | else /* would there ever be a need for multiple client certs? */ |
| 1485 | if ((err = tls_add_certfile(sctx, cbinfo, expanded, errstr))) |
| 1486 | return err; |
| 1487 | |
| 1488 | if ( cbinfo->privatekey |
| 1489 | && !expand_check(cbinfo->privatekey, US"tls_privatekey", &expanded, errstr)) |
| 1490 | return DEFER; |
| 1491 | |
| 1492 | /* If expansion was forced to fail, key_expanded will be NULL. If the result |
| 1493 | of the expansion is an empty string, ignore it also, and assume the private |
| 1494 | key is in the same file as the certificate. */ |
| 1495 | |
| 1496 | if (expanded && *expanded) |
| 1497 | if (cbinfo->is_server) |
| 1498 | { |
| 1499 | const uschar * file_list = expanded; |
| 1500 | int sep = 0; |
| 1501 | uschar * file; |
| 1502 | |
| 1503 | while (file = string_nextinlist(&file_list, &sep, NULL, 0)) |
| 1504 | if ((err = tls_add_pkeyfile(sctx, cbinfo, file, errstr))) |
| 1505 | return err; |
| 1506 | } |
| 1507 | else /* would there ever be a need for multiple client certs? */ |
| 1508 | if ((err = tls_add_pkeyfile(sctx, cbinfo, expanded, errstr))) |
| 1509 | return err; |
| 1510 | } |
| 1511 | |
| 1512 | #ifndef DISABLE_OCSP |
| 1513 | if (cbinfo->is_server && cbinfo->u_ocsp.server.file) |
| 1514 | { |
| 1515 | /*XXX stack*/ |
| 1516 | if (!expand_check(cbinfo->u_ocsp.server.file, US"tls_ocsp_file", &expanded, errstr)) |
| 1517 | return DEFER; |
| 1518 | |
| 1519 | if (expanded && *expanded) |
| 1520 | { |
| 1521 | DEBUG(D_tls) debug_printf("tls_ocsp_file %s\n", expanded); |
| 1522 | if ( cbinfo->u_ocsp.server.file_expanded |
| 1523 | && (Ustrcmp(expanded, cbinfo->u_ocsp.server.file_expanded) == 0)) |
| 1524 | { |
| 1525 | DEBUG(D_tls) debug_printf(" - value unchanged, using existing values\n"); |
| 1526 | } |
| 1527 | else |
| 1528 | ocsp_load_response(sctx, cbinfo, expanded); |
| 1529 | } |
| 1530 | } |
| 1531 | #endif |
| 1532 | |
| 1533 | return OK; |
| 1534 | } |
| 1535 | |
| 1536 | |
| 1537 | |
| 1538 | |
| 1539 | /************************************************* |
| 1540 | * Callback to handle SNI * |
| 1541 | *************************************************/ |
| 1542 | |
| 1543 | /* Called when acting as server during the TLS session setup if a Server Name |
| 1544 | Indication extension was sent by the client. |
| 1545 | |
| 1546 | API documentation is OpenSSL s_server.c implementation. |
| 1547 | |
| 1548 | Arguments: |
| 1549 | s SSL* of the current session |
| 1550 | ad unknown (part of OpenSSL API) (unused) |
| 1551 | arg Callback of "our" registered data |
| 1552 | |
| 1553 | Returns: SSL_TLSEXT_ERR_{OK,ALERT_WARNING,ALERT_FATAL,NOACK} |
| 1554 | |
| 1555 | XXX might need to change to using ClientHello callback, |
| 1556 | per https://www.openssl.org/docs/manmaster/man3/SSL_client_hello_cb_fn.html |
| 1557 | */ |
| 1558 | |
| 1559 | #ifdef EXIM_HAVE_OPENSSL_TLSEXT |
| 1560 | static int |
| 1561 | tls_servername_cb(SSL *s, int *ad ARG_UNUSED, void *arg) |
| 1562 | { |
| 1563 | const char *servername = SSL_get_servername(s, TLSEXT_NAMETYPE_host_name); |
| 1564 | tls_ext_ctx_cb *cbinfo = (tls_ext_ctx_cb *) arg; |
| 1565 | int rc; |
| 1566 | int old_pool = store_pool; |
| 1567 | uschar * dummy_errstr; |
| 1568 | |
| 1569 | if (!servername) |
| 1570 | return SSL_TLSEXT_ERR_OK; |
| 1571 | |
| 1572 | DEBUG(D_tls) debug_printf("Received TLS SNI \"%s\"%s\n", servername, |
| 1573 | reexpand_tls_files_for_sni ? "" : " (unused for certificate selection)"); |
| 1574 | |
| 1575 | /* Make the extension value available for expansion */ |
| 1576 | store_pool = POOL_PERM; |
| 1577 | tls_in.sni = string_copy_taint(US servername, TRUE); |
| 1578 | store_pool = old_pool; |
| 1579 | |
| 1580 | if (!reexpand_tls_files_for_sni) |
| 1581 | return SSL_TLSEXT_ERR_OK; |
| 1582 | |
| 1583 | /* Can't find an SSL_CTX_clone() or equivalent, so we do it manually; |
| 1584 | not confident that memcpy wouldn't break some internal reference counting. |
| 1585 | Especially since there's a references struct member, which would be off. */ |
| 1586 | |
| 1587 | #ifdef EXIM_HAVE_OPENSSL_TLS_METHOD |
| 1588 | if (!(server_sni = SSL_CTX_new(TLS_server_method()))) |
| 1589 | #else |
| 1590 | if (!(server_sni = SSL_CTX_new(SSLv23_server_method()))) |
| 1591 | #endif |
| 1592 | { |
| 1593 | ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring)); |
| 1594 | DEBUG(D_tls) debug_printf("SSL_CTX_new() failed: %s\n", ssl_errstring); |
| 1595 | goto bad; |
| 1596 | } |
| 1597 | |
| 1598 | /* Not sure how many of these are actually needed, since SSL object |
| 1599 | already exists. Might even need this selfsame callback, for reneg? */ |
| 1600 | |
| 1601 | SSL_CTX_set_info_callback(server_sni, SSL_CTX_get_info_callback(server_ctx)); |
| 1602 | SSL_CTX_set_mode(server_sni, SSL_CTX_get_mode(server_ctx)); |
| 1603 | SSL_CTX_set_options(server_sni, SSL_CTX_get_options(server_ctx)); |
| 1604 | SSL_CTX_set_timeout(server_sni, SSL_CTX_get_timeout(server_ctx)); |
| 1605 | SSL_CTX_set_tlsext_servername_callback(server_sni, tls_servername_cb); |
| 1606 | SSL_CTX_set_tlsext_servername_arg(server_sni, cbinfo); |
| 1607 | |
| 1608 | if ( !init_dh(server_sni, cbinfo->dhparam, NULL, &dummy_errstr) |
| 1609 | || !init_ecdh(server_sni, NULL, &dummy_errstr) |
| 1610 | ) |
| 1611 | goto bad; |
| 1612 | |
| 1613 | if ( cbinfo->server_cipher_list |
| 1614 | && !SSL_CTX_set_cipher_list(server_sni, CS cbinfo->server_cipher_list)) |
| 1615 | goto bad; |
| 1616 | |
| 1617 | #ifndef DISABLE_OCSP |
| 1618 | if (cbinfo->u_ocsp.server.file) |
| 1619 | { |
| 1620 | SSL_CTX_set_tlsext_status_cb(server_sni, tls_server_stapling_cb); |
| 1621 | SSL_CTX_set_tlsext_status_arg(server_sni, cbinfo); |
| 1622 | } |
| 1623 | #endif |
| 1624 | |
| 1625 | if ((rc = setup_certs(server_sni, tls_verify_certificates, tls_crl, NULL, FALSE, |
| 1626 | verify_callback_server, &dummy_errstr)) != OK) |
| 1627 | goto bad; |
| 1628 | |
| 1629 | /* do this after setup_certs, because this can require the certs for verifying |
| 1630 | OCSP information. */ |
| 1631 | if ((rc = tls_expand_session_files(server_sni, cbinfo, &dummy_errstr)) != OK) |
| 1632 | goto bad; |
| 1633 | |
| 1634 | DEBUG(D_tls) debug_printf("Switching SSL context.\n"); |
| 1635 | SSL_set_SSL_CTX(s, server_sni); |
| 1636 | return SSL_TLSEXT_ERR_OK; |
| 1637 | |
| 1638 | bad: return SSL_TLSEXT_ERR_ALERT_FATAL; |
| 1639 | } |
| 1640 | #endif /* EXIM_HAVE_OPENSSL_TLSEXT */ |
| 1641 | |
| 1642 | |
| 1643 | |
| 1644 | |
| 1645 | #ifndef DISABLE_OCSP |
| 1646 | |
| 1647 | /************************************************* |
| 1648 | * Callback to handle OCSP Stapling * |
| 1649 | *************************************************/ |
| 1650 | |
| 1651 | /* Called when acting as server during the TLS session setup if the client |
| 1652 | requests OCSP information with a Certificate Status Request. |
| 1653 | |
| 1654 | Documentation via openssl s_server.c and the Apache patch from the OpenSSL |
| 1655 | project. |
| 1656 | |
| 1657 | */ |
| 1658 | |
| 1659 | static int |
| 1660 | tls_server_stapling_cb(SSL *s, void *arg) |
| 1661 | { |
| 1662 | const tls_ext_ctx_cb *cbinfo = (tls_ext_ctx_cb *) arg; |
| 1663 | uschar *response_der; /*XXX blob */ |
| 1664 | int response_der_len; |
| 1665 | |
| 1666 | /*XXX stack: use SSL_get_certificate() to see which cert; from that work |
| 1667 | out which ocsp blob to send. Unfortunately, SSL_get_certificate is known |
| 1668 | buggy in current OpenSSL; it returns the last cert loaded always rather than |
| 1669 | the one actually presented. So we can't support a stack of OCSP proofs at |
| 1670 | this time. */ |
| 1671 | |
| 1672 | DEBUG(D_tls) |
| 1673 | debug_printf("Received TLS status request (OCSP stapling); %s response\n", |
| 1674 | cbinfo->u_ocsp.server.response ? "have" : "lack"); |
| 1675 | |
| 1676 | tls_in.ocsp = OCSP_NOT_RESP; |
| 1677 | if (!cbinfo->u_ocsp.server.response) |
| 1678 | return SSL_TLSEXT_ERR_NOACK; |
| 1679 | |
| 1680 | response_der = NULL; |
| 1681 | response_der_len = i2d_OCSP_RESPONSE(cbinfo->u_ocsp.server.response, /*XXX stack*/ |
| 1682 | &response_der); |
| 1683 | if (response_der_len <= 0) |
| 1684 | return SSL_TLSEXT_ERR_NOACK; |
| 1685 | |
| 1686 | SSL_set_tlsext_status_ocsp_resp(server_ssl, response_der, response_der_len); |
| 1687 | tls_in.ocsp = OCSP_VFIED; |
| 1688 | return SSL_TLSEXT_ERR_OK; |
| 1689 | } |
| 1690 | |
| 1691 | |
| 1692 | static void |
| 1693 | time_print(BIO * bp, const char * str, ASN1_GENERALIZEDTIME * time) |
| 1694 | { |
| 1695 | BIO_printf(bp, "\t%s: ", str); |
| 1696 | ASN1_GENERALIZEDTIME_print(bp, time); |
| 1697 | BIO_puts(bp, "\n"); |
| 1698 | } |
| 1699 | |
| 1700 | static int |
| 1701 | tls_client_stapling_cb(SSL *s, void *arg) |
| 1702 | { |
| 1703 | tls_ext_ctx_cb * cbinfo = arg; |
| 1704 | const unsigned char * p; |
| 1705 | int len; |
| 1706 | OCSP_RESPONSE * rsp; |
| 1707 | OCSP_BASICRESP * bs; |
| 1708 | int i; |
| 1709 | |
| 1710 | DEBUG(D_tls) debug_printf("Received TLS status response (OCSP stapling):"); |
| 1711 | len = SSL_get_tlsext_status_ocsp_resp(s, &p); |
| 1712 | if(!p) |
| 1713 | { |
| 1714 | /* Expect this when we requested ocsp but got none */ |
| 1715 | if (cbinfo->u_ocsp.client.verify_required && LOGGING(tls_cipher)) |
| 1716 | log_write(0, LOG_MAIN, "Received TLS status callback, null content"); |
| 1717 | else |
| 1718 | DEBUG(D_tls) debug_printf(" null\n"); |
| 1719 | return cbinfo->u_ocsp.client.verify_required ? 0 : 1; |
| 1720 | } |
| 1721 | |
| 1722 | if (!(rsp = d2i_OCSP_RESPONSE(NULL, &p, len))) |
| 1723 | { |
| 1724 | tls_out.ocsp = OCSP_FAILED; /*XXX should use tlsp-> to permit concurrent outbound */ |
| 1725 | if (LOGGING(tls_cipher)) |
| 1726 | log_write(0, LOG_MAIN, "Received TLS cert status response, parse error"); |
| 1727 | else |
| 1728 | DEBUG(D_tls) debug_printf(" parse error\n"); |
| 1729 | return 0; |
| 1730 | } |
| 1731 | |
| 1732 | if (!(bs = OCSP_response_get1_basic(rsp))) |
| 1733 | { |
| 1734 | tls_out.ocsp = OCSP_FAILED; |
| 1735 | if (LOGGING(tls_cipher)) |
| 1736 | log_write(0, LOG_MAIN, "Received TLS cert status response, error parsing response"); |
| 1737 | else |
| 1738 | DEBUG(D_tls) debug_printf(" error parsing response\n"); |
| 1739 | OCSP_RESPONSE_free(rsp); |
| 1740 | return 0; |
| 1741 | } |
| 1742 | |
| 1743 | /* We'd check the nonce here if we'd put one in the request. */ |
| 1744 | /* However that would defeat cacheability on the server so we don't. */ |
| 1745 | |
| 1746 | /* This section of code reworked from OpenSSL apps source; |
| 1747 | The OpenSSL Project retains copyright: |
| 1748 | Copyright (c) 1999 The OpenSSL Project. All rights reserved. |
| 1749 | */ |
| 1750 | { |
| 1751 | BIO * bp = NULL; |
| 1752 | int status, reason; |
| 1753 | ASN1_GENERALIZEDTIME *rev, *thisupd, *nextupd; |
| 1754 | |
| 1755 | DEBUG(D_tls) bp = BIO_new_fp(debug_file, BIO_NOCLOSE); |
| 1756 | |
| 1757 | /*OCSP_RESPONSE_print(bp, rsp, 0); extreme debug: stapling content */ |
| 1758 | |
| 1759 | /* Use the chain that verified the server cert to verify the stapled info */ |
| 1760 | /* DEBUG(D_tls) x509_store_dump_cert_s_names(cbinfo->u_ocsp.client.verify_store); */ |
| 1761 | |
| 1762 | if ((i = OCSP_basic_verify(bs, cbinfo->verify_stack, |
| 1763 | cbinfo->u_ocsp.client.verify_store, 0)) <= 0) |
| 1764 | { |
| 1765 | tls_out.ocsp = OCSP_FAILED; |
| 1766 | if (LOGGING(tls_cipher)) log_write(0, LOG_MAIN, |
| 1767 | "Received TLS cert status response, itself unverifiable: %s", |
| 1768 | ERR_reason_error_string(ERR_peek_error())); |
| 1769 | BIO_printf(bp, "OCSP response verify failure\n"); |
| 1770 | ERR_print_errors(bp); |
| 1771 | OCSP_RESPONSE_print(bp, rsp, 0); |
| 1772 | goto failed; |
| 1773 | } |
| 1774 | |
| 1775 | BIO_printf(bp, "OCSP response well-formed and signed OK\n"); |
| 1776 | |
| 1777 | /*XXX So we have a good stapled OCSP status. How do we know |
| 1778 | it is for the cert of interest? OpenSSL 1.1.0 has a routine |
| 1779 | OCSP_resp_find_status() which matches on a cert id, which presumably |
| 1780 | we should use. Making an id needs OCSP_cert_id_new(), which takes |
| 1781 | issuerName, issuerKey, serialNumber. Are they all in the cert? |
| 1782 | |
| 1783 | For now, carry on blindly accepting the resp. */ |
| 1784 | |
| 1785 | { |
| 1786 | OCSP_SINGLERESP * single; |
| 1787 | |
| 1788 | #ifdef EXIM_HAVE_OCSP_RESP_COUNT |
| 1789 | if (OCSP_resp_count(bs) != 1) |
| 1790 | #else |
| 1791 | STACK_OF(OCSP_SINGLERESP) * sresp = bs->tbsResponseData->responses; |
| 1792 | if (sk_OCSP_SINGLERESP_num(sresp) != 1) |
| 1793 | #endif |
| 1794 | { |
| 1795 | tls_out.ocsp = OCSP_FAILED; |
| 1796 | log_write(0, LOG_MAIN, "OCSP stapling " |
| 1797 | "with multiple responses not handled"); |
| 1798 | goto failed; |
| 1799 | } |
| 1800 | single = OCSP_resp_get0(bs, 0); |
| 1801 | status = OCSP_single_get0_status(single, &reason, &rev, |
| 1802 | &thisupd, &nextupd); |
| 1803 | } |
| 1804 | |
| 1805 | DEBUG(D_tls) time_print(bp, "This OCSP Update", thisupd); |
| 1806 | DEBUG(D_tls) if(nextupd) time_print(bp, "Next OCSP Update", nextupd); |
| 1807 | if (!OCSP_check_validity(thisupd, nextupd, |
| 1808 | EXIM_OCSP_SKEW_SECONDS, EXIM_OCSP_MAX_AGE)) |
| 1809 | { |
| 1810 | tls_out.ocsp = OCSP_FAILED; |
| 1811 | DEBUG(D_tls) ERR_print_errors(bp); |
| 1812 | log_write(0, LOG_MAIN, "Server OSCP dates invalid"); |
| 1813 | } |
| 1814 | else |
| 1815 | { |
| 1816 | DEBUG(D_tls) BIO_printf(bp, "Certificate status: %s\n", |
| 1817 | OCSP_cert_status_str(status)); |
| 1818 | switch(status) |
| 1819 | { |
| 1820 | case V_OCSP_CERTSTATUS_GOOD: |
| 1821 | tls_out.ocsp = OCSP_VFIED; |
| 1822 | i = 1; |
| 1823 | goto good; |
| 1824 | case V_OCSP_CERTSTATUS_REVOKED: |
| 1825 | tls_out.ocsp = OCSP_FAILED; |
| 1826 | log_write(0, LOG_MAIN, "Server certificate revoked%s%s", |
| 1827 | reason != -1 ? "; reason: " : "", |
| 1828 | reason != -1 ? OCSP_crl_reason_str(reason) : ""); |
| 1829 | DEBUG(D_tls) time_print(bp, "Revocation Time", rev); |
| 1830 | break; |
| 1831 | default: |
| 1832 | tls_out.ocsp = OCSP_FAILED; |
| 1833 | log_write(0, LOG_MAIN, |
| 1834 | "Server certificate status unknown, in OCSP stapling"); |
| 1835 | break; |
| 1836 | } |
| 1837 | } |
| 1838 | failed: |
| 1839 | i = cbinfo->u_ocsp.client.verify_required ? 0 : 1; |
| 1840 | good: |
| 1841 | BIO_free(bp); |
| 1842 | } |
| 1843 | |
| 1844 | OCSP_RESPONSE_free(rsp); |
| 1845 | return i; |
| 1846 | } |
| 1847 | #endif /*!DISABLE_OCSP*/ |
| 1848 | |
| 1849 | |
| 1850 | /************************************************* |
| 1851 | * Initialize for TLS * |
| 1852 | *************************************************/ |
| 1853 | |
| 1854 | /* Called from both server and client code, to do preliminary initialization |
| 1855 | of the library. We allocate and return a context structure. |
| 1856 | |
| 1857 | Arguments: |
| 1858 | ctxp returned SSL context |
| 1859 | host connected host, if client; NULL if server |
| 1860 | dhparam DH parameter file |
| 1861 | certificate certificate file |
| 1862 | privatekey private key |
| 1863 | ocsp_file file of stapling info (server); flag for require ocsp (client) |
| 1864 | addr address if client; NULL if server (for some randomness) |
| 1865 | cbp place to put allocated callback context |
| 1866 | errstr error string pointer |
| 1867 | |
| 1868 | Returns: OK/DEFER/FAIL |
| 1869 | */ |
| 1870 | |
| 1871 | static int |
| 1872 | tls_init(SSL_CTX **ctxp, host_item *host, uschar *dhparam, uschar *certificate, |
| 1873 | uschar *privatekey, |
| 1874 | #ifndef DISABLE_OCSP |
| 1875 | uschar *ocsp_file, /*XXX stack, in server*/ |
| 1876 | #endif |
| 1877 | address_item *addr, tls_ext_ctx_cb ** cbp, |
| 1878 | tls_support * tlsp, |
| 1879 | uschar ** errstr) |
| 1880 | { |
| 1881 | SSL_CTX * ctx; |
| 1882 | long init_options; |
| 1883 | int rc; |
| 1884 | tls_ext_ctx_cb * cbinfo; |
| 1885 | |
| 1886 | cbinfo = store_malloc(sizeof(tls_ext_ctx_cb)); |
| 1887 | cbinfo->tlsp = tlsp; |
| 1888 | cbinfo->certificate = certificate; |
| 1889 | cbinfo->privatekey = privatekey; |
| 1890 | cbinfo->is_server = host==NULL; |
| 1891 | #ifndef DISABLE_OCSP |
| 1892 | cbinfo->verify_stack = NULL; |
| 1893 | if (!host) |
| 1894 | { |
| 1895 | cbinfo->u_ocsp.server.file = ocsp_file; |
| 1896 | cbinfo->u_ocsp.server.file_expanded = NULL; |
| 1897 | cbinfo->u_ocsp.server.response = NULL; |
| 1898 | } |
| 1899 | else |
| 1900 | cbinfo->u_ocsp.client.verify_store = NULL; |
| 1901 | #endif |
| 1902 | cbinfo->dhparam = dhparam; |
| 1903 | cbinfo->server_cipher_list = NULL; |
| 1904 | cbinfo->host = host; |
| 1905 | #ifndef DISABLE_EVENT |
| 1906 | cbinfo->event_action = NULL; |
| 1907 | #endif |
| 1908 | |
| 1909 | #ifdef EXIM_NEED_OPENSSL_INIT |
| 1910 | SSL_load_error_strings(); /* basic set up */ |
| 1911 | OpenSSL_add_ssl_algorithms(); |
| 1912 | #endif |
| 1913 | |
| 1914 | #ifdef EXIM_HAVE_SHA256 |
| 1915 | /* SHA256 is becoming ever more popular. This makes sure it gets added to the |
| 1916 | list of available digests. */ |
| 1917 | EVP_add_digest(EVP_sha256()); |
| 1918 | #endif |
| 1919 | |
| 1920 | /* Create a context. |
| 1921 | The OpenSSL docs in 1.0.1b have not been updated to clarify TLS variant |
| 1922 | negotiation in the different methods; as far as I can tell, the only |
| 1923 | *_{server,client}_method which allows negotiation is SSLv23, which exists even |
| 1924 | when OpenSSL is built without SSLv2 support. |
| 1925 | By disabling with openssl_options, we can let admins re-enable with the |
| 1926 | existing knob. */ |
| 1927 | |
| 1928 | #ifdef EXIM_HAVE_OPENSSL_TLS_METHOD |
| 1929 | if (!(ctx = SSL_CTX_new(host ? TLS_client_method() : TLS_server_method()))) |
| 1930 | #else |
| 1931 | if (!(ctx = SSL_CTX_new(host ? SSLv23_client_method() : SSLv23_server_method()))) |
| 1932 | #endif |
| 1933 | return tls_error(US"SSL_CTX_new", host, NULL, errstr); |
| 1934 | |
| 1935 | /* It turns out that we need to seed the random number generator this early in |
| 1936 | order to get the full complement of ciphers to work. It took me roughly a day |
| 1937 | of work to discover this by experiment. |
| 1938 | |
| 1939 | On systems that have /dev/urandom, SSL may automatically seed itself from |
| 1940 | there. Otherwise, we have to make something up as best we can. Double check |
| 1941 | afterwards. */ |
| 1942 | |
| 1943 | if (!RAND_status()) |
| 1944 | { |
| 1945 | randstuff r; |
| 1946 | gettimeofday(&r.tv, NULL); |
| 1947 | r.p = getpid(); |
| 1948 | |
| 1949 | RAND_seed(US (&r), sizeof(r)); |
| 1950 | RAND_seed(US big_buffer, big_buffer_size); |
| 1951 | if (addr != NULL) RAND_seed(US addr, sizeof(addr)); |
| 1952 | |
| 1953 | if (!RAND_status()) |
| 1954 | return tls_error(US"RAND_status", host, |
| 1955 | US"unable to seed random number generator", errstr); |
| 1956 | } |
| 1957 | |
| 1958 | /* Set up the information callback, which outputs if debugging is at a suitable |
| 1959 | level. */ |
| 1960 | |
| 1961 | DEBUG(D_tls) |
| 1962 | { |
| 1963 | SSL_CTX_set_info_callback(ctx, (void (*)())info_callback); |
| 1964 | #if defined(EXIM_HAVE_OPESSL_TRACE) && !defined(OPENSSL_NO_SSL_TRACE) |
| 1965 | /* this needs a debug build of OpenSSL */ |
| 1966 | SSL_CTX_set_msg_callback(ctx, (void (*)())SSL_trace); |
| 1967 | #endif |
| 1968 | #ifdef OPENSSL_HAVE_KEYLOG_CB |
| 1969 | SSL_CTX_set_keylog_callback(ctx, (void (*)())keylog_callback); |
| 1970 | #endif |
| 1971 | } |
| 1972 | |
| 1973 | /* Automatically re-try reads/writes after renegotiation. */ |
| 1974 | (void) SSL_CTX_set_mode(ctx, SSL_MODE_AUTO_RETRY); |
| 1975 | |
| 1976 | /* Apply administrator-supplied work-arounds. |
| 1977 | Historically we applied just one requested option, |
| 1978 | SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS, but when bug 994 requested a second, we |
| 1979 | moved to an administrator-controlled list of options to specify and |
| 1980 | grandfathered in the first one as the default value for "openssl_options". |
| 1981 | |
| 1982 | No OpenSSL version number checks: the options we accept depend upon the |
| 1983 | availability of the option value macros from OpenSSL. */ |
| 1984 | |
| 1985 | if (!tls_openssl_options_parse(openssl_options, &init_options)) |
| 1986 | return tls_error(US"openssl_options parsing failed", host, NULL, errstr); |
| 1987 | |
| 1988 | #ifdef EXPERIMENTAL_TLS_RESUME |
| 1989 | tlsp->resumption = RESUME_SUPPORTED; |
| 1990 | #endif |
| 1991 | if (init_options) |
| 1992 | { |
| 1993 | #ifdef EXPERIMENTAL_TLS_RESUME |
| 1994 | /* Should the server offer session resumption? */ |
| 1995 | if (!host && verify_check_host(&tls_resumption_hosts) == OK) |
| 1996 | { |
| 1997 | DEBUG(D_tls) debug_printf("tls_resumption_hosts overrides openssl_options\n"); |
| 1998 | init_options &= ~SSL_OP_NO_TICKET; |
| 1999 | tlsp->resumption |= RESUME_SERVER_TICKET; /* server will give ticket on request */ |
| 2000 | tlsp->host_resumable = TRUE; |
| 2001 | } |
| 2002 | #endif |
| 2003 | |
| 2004 | DEBUG(D_tls) debug_printf("setting SSL CTX options: %#lx\n", init_options); |
| 2005 | if (!(SSL_CTX_set_options(ctx, init_options))) |
| 2006 | return tls_error(string_sprintf( |
| 2007 | "SSL_CTX_set_option(%#lx)", init_options), host, NULL, errstr); |
| 2008 | } |
| 2009 | else |
| 2010 | DEBUG(D_tls) debug_printf("no SSL CTX options to set\n"); |
| 2011 | |
| 2012 | /* We'd like to disable session cache unconditionally, but foolish Outlook |
| 2013 | Express clients then give up the first TLS connection and make a second one |
| 2014 | (which works). Only when there is an IMAP service on the same machine. |
| 2015 | Presumably OE is trying to use the cache for A on B. Leave it enabled for |
| 2016 | now, until we work out a decent way of presenting control to the config. It |
| 2017 | will never be used because we use a new context every time. */ |
| 2018 | #ifdef notdef |
| 2019 | (void) SSL_CTX_set_session_cache_mode(ctx, SSL_SESS_CACHE_OFF); |
| 2020 | #endif |
| 2021 | |
| 2022 | /* Initialize with DH parameters if supplied */ |
| 2023 | /* Initialize ECDH temp key parameter selection */ |
| 2024 | |
| 2025 | if ( !init_dh(ctx, dhparam, host, errstr) |
| 2026 | || !init_ecdh(ctx, host, errstr) |
| 2027 | ) |
| 2028 | return DEFER; |
| 2029 | |
| 2030 | /* Set up certificate and key (and perhaps OCSP info) */ |
| 2031 | |
| 2032 | if ((rc = tls_expand_session_files(ctx, cbinfo, errstr)) != OK) |
| 2033 | return rc; |
| 2034 | |
| 2035 | /* If we need to handle SNI or OCSP, do so */ |
| 2036 | |
| 2037 | #ifdef EXIM_HAVE_OPENSSL_TLSEXT |
| 2038 | # ifndef DISABLE_OCSP |
| 2039 | if (!(cbinfo->verify_stack = sk_X509_new_null())) |
| 2040 | { |
| 2041 | DEBUG(D_tls) debug_printf("failed to create stack for stapling verify\n"); |
| 2042 | return FAIL; |
| 2043 | } |
| 2044 | # endif |
| 2045 | |
| 2046 | if (!host) /* server */ |
| 2047 | { |
| 2048 | # ifndef DISABLE_OCSP |
| 2049 | /* We check u_ocsp.server.file, not server.response, because we care about if |
| 2050 | the option exists, not what the current expansion might be, as SNI might |
| 2051 | change the certificate and OCSP file in use between now and the time the |
| 2052 | callback is invoked. */ |
| 2053 | if (cbinfo->u_ocsp.server.file) |
| 2054 | { |
| 2055 | SSL_CTX_set_tlsext_status_cb(ctx, tls_server_stapling_cb); |
| 2056 | SSL_CTX_set_tlsext_status_arg(ctx, cbinfo); |
| 2057 | } |
| 2058 | # endif |
| 2059 | /* We always do this, so that $tls_sni is available even if not used in |
| 2060 | tls_certificate */ |
| 2061 | SSL_CTX_set_tlsext_servername_callback(ctx, tls_servername_cb); |
| 2062 | SSL_CTX_set_tlsext_servername_arg(ctx, cbinfo); |
| 2063 | } |
| 2064 | # ifndef DISABLE_OCSP |
| 2065 | else /* client */ |
| 2066 | if(ocsp_file) /* wanting stapling */ |
| 2067 | { |
| 2068 | if (!(cbinfo->u_ocsp.client.verify_store = X509_STORE_new())) |
| 2069 | { |
| 2070 | DEBUG(D_tls) debug_printf("failed to create store for stapling verify\n"); |
| 2071 | return FAIL; |
| 2072 | } |
| 2073 | SSL_CTX_set_tlsext_status_cb(ctx, tls_client_stapling_cb); |
| 2074 | SSL_CTX_set_tlsext_status_arg(ctx, cbinfo); |
| 2075 | } |
| 2076 | # endif |
| 2077 | #endif |
| 2078 | |
| 2079 | cbinfo->verify_cert_hostnames = NULL; |
| 2080 | |
| 2081 | #ifdef EXIM_HAVE_EPHEM_RSA_KEX |
| 2082 | /* Set up the RSA callback */ |
| 2083 | SSL_CTX_set_tmp_rsa_callback(ctx, rsa_callback); |
| 2084 | #endif |
| 2085 | |
| 2086 | /* Finally, set the session cache timeout, and we are done. |
| 2087 | The period appears to be also used for (server-generated) session tickets */ |
| 2088 | |
| 2089 | SSL_CTX_set_timeout(ctx, ssl_session_timeout); |
| 2090 | DEBUG(D_tls) debug_printf("Initialized TLS\n"); |
| 2091 | |
| 2092 | *cbp = cbinfo; |
| 2093 | *ctxp = ctx; |
| 2094 | |
| 2095 | return OK; |
| 2096 | } |
| 2097 | |
| 2098 | |
| 2099 | |
| 2100 | |
| 2101 | /************************************************* |
| 2102 | * Get name of cipher in use * |
| 2103 | *************************************************/ |
| 2104 | |
| 2105 | /* |
| 2106 | Argument: pointer to an SSL structure for the connection |
| 2107 | pointer to number of bits for cipher |
| 2108 | Returns: pointer to allocated string in perm-pool |
| 2109 | */ |
| 2110 | |
| 2111 | static uschar * |
| 2112 | construct_cipher_name(SSL * ssl, int * bits) |
| 2113 | { |
| 2114 | int pool = store_pool; |
| 2115 | /* With OpenSSL 1.0.0a, 'c' needs to be const but the documentation doesn't |
| 2116 | yet reflect that. It should be a safe change anyway, even 0.9.8 versions have |
| 2117 | the accessor functions use const in the prototype. */ |
| 2118 | |
| 2119 | const uschar * ver = CUS SSL_get_version(ssl); |
| 2120 | const SSL_CIPHER * c = (const SSL_CIPHER *) SSL_get_current_cipher(ssl); |
| 2121 | uschar * s; |
| 2122 | |
| 2123 | SSL_CIPHER_get_bits(c, bits); |
| 2124 | |
| 2125 | store_pool = POOL_PERM; |
| 2126 | s = string_sprintf("%s:%s:%u", ver, SSL_CIPHER_get_name(c), *bits); |
| 2127 | store_pool = pool; |
| 2128 | DEBUG(D_tls) debug_printf("Cipher: %s\n", s); |
| 2129 | return s; |
| 2130 | } |
| 2131 | |
| 2132 | |
| 2133 | /* Get IETF-standard name for ciphersuite. |
| 2134 | Argument: pointer to an SSL structure for the connection |
| 2135 | Returns: pointer to string |
| 2136 | */ |
| 2137 | |
| 2138 | static const uschar * |
| 2139 | cipher_stdname_ssl(SSL * ssl) |
| 2140 | { |
| 2141 | #ifdef EXIM_HAVE_OPENSSL_CIPHER_STD_NAME |
| 2142 | return CUS SSL_CIPHER_standard_name(SSL_get_current_cipher(ssl)); |
| 2143 | #else |
| 2144 | ushort id = 0xffff & SSL_CIPHER_get_id(SSL_get_current_cipher(ssl)); |
| 2145 | return cipher_stdname(id >> 8, id & 0xff); |
| 2146 | #endif |
| 2147 | } |
| 2148 | |
| 2149 | |
| 2150 | static void |
| 2151 | peer_cert(SSL * ssl, tls_support * tlsp, uschar * peerdn, unsigned siz) |
| 2152 | { |
| 2153 | /*XXX we might consider a list-of-certs variable for the cert chain. |
| 2154 | SSL_get_peer_cert_chain(SSL*). We'd need a new variable type and support |
| 2155 | in list-handling functions, also consider the difference between the entire |
| 2156 | chain and the elements sent by the peer. */ |
| 2157 | |
| 2158 | tlsp->peerdn = NULL; |
| 2159 | |
| 2160 | /* Will have already noted peercert on a verify fail; possibly not the leaf */ |
| 2161 | if (!tlsp->peercert) |
| 2162 | tlsp->peercert = SSL_get_peer_certificate(ssl); |
| 2163 | /* Beware anonymous ciphers which lead to server_cert being NULL */ |
| 2164 | if (tlsp->peercert) |
| 2165 | if (!X509_NAME_oneline(X509_get_subject_name(tlsp->peercert), CS peerdn, siz)) |
| 2166 | { DEBUG(D_tls) debug_printf("X509_NAME_oneline() error\n"); } |
| 2167 | else |
| 2168 | { |
| 2169 | int oldpool = store_pool; |
| 2170 | |
| 2171 | peerdn[siz-1] = '\0'; /* paranoia */ |
| 2172 | store_pool = POOL_PERM; |
| 2173 | tlsp->peerdn = string_copy(peerdn); |
| 2174 | store_pool = oldpool; |
| 2175 | |
| 2176 | /* We used to set CV in the cert-verify callbacks (either plain or dane) |
| 2177 | but they don't get called on session-resumption. So use the official |
| 2178 | interface, which uses the resumed value. Unfortunately this claims verified |
| 2179 | when it actually failed but we're in try-verify mode, due to us wanting the |
| 2180 | knowlege that it failed so needing to have the callback and forcing a |
| 2181 | permissive return. If we don't force it, the TLS startup is failed. |
| 2182 | The extra bit of information is set in verify_override in the cb, stashed |
| 2183 | for resumption next to the TLS session, and used here. */ |
| 2184 | |
| 2185 | if (!tlsp->verify_override) |
| 2186 | tlsp->certificate_verified = SSL_get_verify_result(ssl) == X509_V_OK; |
| 2187 | } |
| 2188 | } |
| 2189 | |
| 2190 | |
| 2191 | |
| 2192 | |
| 2193 | |
| 2194 | /************************************************* |
| 2195 | * Set up for verifying certificates * |
| 2196 | *************************************************/ |
| 2197 | |
| 2198 | #ifndef DISABLE_OCSP |
| 2199 | /* Load certs from file, return TRUE on success */ |
| 2200 | |
| 2201 | static BOOL |
| 2202 | chain_from_pem_file(const uschar * file, STACK_OF(X509) * verify_stack) |
| 2203 | { |
| 2204 | BIO * bp; |
| 2205 | X509 * x; |
| 2206 | |
| 2207 | while (sk_X509_num(verify_stack) > 0) |
| 2208 | X509_free(sk_X509_pop(verify_stack)); |
| 2209 | |
| 2210 | if (!(bp = BIO_new_file(CS file, "r"))) return FALSE; |
| 2211 | while ((x = PEM_read_bio_X509(bp, NULL, 0, NULL))) |
| 2212 | sk_X509_push(verify_stack, x); |
| 2213 | BIO_free(bp); |
| 2214 | return TRUE; |
| 2215 | } |
| 2216 | #endif |
| 2217 | |
| 2218 | |
| 2219 | |
| 2220 | /* Called by both client and server startup; on the server possibly |
| 2221 | repeated after a Server Name Indication. |
| 2222 | |
| 2223 | Arguments: |
| 2224 | sctx SSL_CTX* to initialise |
| 2225 | certs certs file or NULL |
| 2226 | crl CRL file or NULL |
| 2227 | host NULL in a server; the remote host in a client |
| 2228 | optional TRUE if called from a server for a host in tls_try_verify_hosts; |
| 2229 | otherwise passed as FALSE |
| 2230 | cert_vfy_cb Callback function for certificate verification |
| 2231 | errstr error string pointer |
| 2232 | |
| 2233 | Returns: OK/DEFER/FAIL |
| 2234 | */ |
| 2235 | |
| 2236 | static int |
| 2237 | setup_certs(SSL_CTX *sctx, uschar *certs, uschar *crl, host_item *host, BOOL optional, |
| 2238 | int (*cert_vfy_cb)(int, X509_STORE_CTX *), uschar ** errstr) |
| 2239 | { |
| 2240 | uschar *expcerts, *expcrl; |
| 2241 | |
| 2242 | if (!expand_check(certs, US"tls_verify_certificates", &expcerts, errstr)) |
| 2243 | return DEFER; |
| 2244 | DEBUG(D_tls) debug_printf("tls_verify_certificates: %s\n", expcerts); |
| 2245 | |
| 2246 | if (expcerts && *expcerts) |
| 2247 | { |
| 2248 | /* Tell the library to use its compiled-in location for the system default |
| 2249 | CA bundle. Then add the ones specified in the config, if any. */ |
| 2250 | |
| 2251 | if (!SSL_CTX_set_default_verify_paths(sctx)) |
| 2252 | return tls_error(US"SSL_CTX_set_default_verify_paths", host, NULL, errstr); |
| 2253 | |
| 2254 | if (Ustrcmp(expcerts, "system") != 0) |
| 2255 | { |
| 2256 | struct stat statbuf; |
| 2257 | |
| 2258 | if (Ustat(expcerts, &statbuf) < 0) |
| 2259 | { |
| 2260 | log_write(0, LOG_MAIN|LOG_PANIC, |
| 2261 | "failed to stat %s for certificates", expcerts); |
| 2262 | return DEFER; |
| 2263 | } |
| 2264 | else |
| 2265 | { |
| 2266 | uschar *file, *dir; |
| 2267 | if ((statbuf.st_mode & S_IFMT) == S_IFDIR) |
| 2268 | { file = NULL; dir = expcerts; } |
| 2269 | else |
| 2270 | { |
| 2271 | file = expcerts; dir = NULL; |
| 2272 | #ifndef DISABLE_OCSP |
| 2273 | /* In the server if we will be offering an OCSP proof, load chain from |
| 2274 | file for verifying the OCSP proof at load time. */ |
| 2275 | |
| 2276 | if ( !host |
| 2277 | && statbuf.st_size > 0 |
| 2278 | && server_static_cbinfo->u_ocsp.server.file |
| 2279 | && !chain_from_pem_file(file, server_static_cbinfo->verify_stack) |
| 2280 | ) |
| 2281 | { |
| 2282 | log_write(0, LOG_MAIN|LOG_PANIC, |
| 2283 | "failed to load cert chain from %s", file); |
| 2284 | return DEFER; |
| 2285 | } |
| 2286 | #endif |
| 2287 | } |
| 2288 | |
| 2289 | /* If a certificate file is empty, the next function fails with an |
| 2290 | unhelpful error message. If we skip it, we get the correct behaviour (no |
| 2291 | certificates are recognized, but the error message is still misleading (it |
| 2292 | says no certificate was supplied). But this is better. */ |
| 2293 | |
| 2294 | if ( (!file || statbuf.st_size > 0) |
| 2295 | && !SSL_CTX_load_verify_locations(sctx, CS file, CS dir)) |
| 2296 | return tls_error(US"SSL_CTX_load_verify_locations", host, NULL, errstr); |
| 2297 | |
| 2298 | /* Load the list of CAs for which we will accept certs, for sending |
| 2299 | to the client. This is only for the one-file tls_verify_certificates |
| 2300 | variant. |
| 2301 | If a list isn't loaded into the server, but some verify locations are set, |
| 2302 | the server end appears to make a wildcard request for client certs. |
| 2303 | Meanwhile, the client library as default behaviour *ignores* the list |
| 2304 | we send over the wire - see man SSL_CTX_set_client_cert_cb. |
| 2305 | Because of this, and that the dir variant is likely only used for |
| 2306 | the public-CA bundle (not for a private CA), not worth fixing. */ |
| 2307 | |
| 2308 | if (file) |
| 2309 | { |
| 2310 | STACK_OF(X509_NAME) * names = SSL_load_client_CA_file(CS file); |
| 2311 | |
| 2312 | SSL_CTX_set_client_CA_list(sctx, names); |
| 2313 | DEBUG(D_tls) debug_printf("Added %d certificate authorities.\n", |
| 2314 | sk_X509_NAME_num(names)); |
| 2315 | } |
| 2316 | } |
| 2317 | } |
| 2318 | |
| 2319 | /* Handle a certificate revocation list. */ |
| 2320 | |
| 2321 | #if OPENSSL_VERSION_NUMBER > 0x00907000L |
| 2322 | |
| 2323 | /* This bit of code is now the version supplied by Lars Mainka. (I have |
| 2324 | merely reformatted it into the Exim code style.) |
| 2325 | |
| 2326 | "From here I changed the code to add support for multiple crl's |
| 2327 | in pem format in one file or to support hashed directory entries in |
| 2328 | pem format instead of a file. This method now uses the library function |
| 2329 | X509_STORE_load_locations to add the CRL location to the SSL context. |
| 2330 | OpenSSL will then handle the verify against CA certs and CRLs by |
| 2331 | itself in the verify callback." */ |
| 2332 | |
| 2333 | if (!expand_check(crl, US"tls_crl", &expcrl, errstr)) return DEFER; |
| 2334 | if (expcrl && *expcrl) |
| 2335 | { |
| 2336 | struct stat statbufcrl; |
| 2337 | if (Ustat(expcrl, &statbufcrl) < 0) |
| 2338 | { |
| 2339 | log_write(0, LOG_MAIN|LOG_PANIC, |
| 2340 | "failed to stat %s for certificates revocation lists", expcrl); |
| 2341 | return DEFER; |
| 2342 | } |
| 2343 | else |
| 2344 | { |
| 2345 | /* is it a file or directory? */ |
| 2346 | uschar *file, *dir; |
| 2347 | X509_STORE *cvstore = SSL_CTX_get_cert_store(sctx); |
| 2348 | if ((statbufcrl.st_mode & S_IFMT) == S_IFDIR) |
| 2349 | { |
| 2350 | file = NULL; |
| 2351 | dir = expcrl; |
| 2352 | DEBUG(D_tls) debug_printf("SSL CRL value is a directory %s\n", dir); |
| 2353 | } |
| 2354 | else |
| 2355 | { |
| 2356 | file = expcrl; |
| 2357 | dir = NULL; |
| 2358 | DEBUG(D_tls) debug_printf("SSL CRL value is a file %s\n", file); |
| 2359 | } |
| 2360 | if (X509_STORE_load_locations(cvstore, CS file, CS dir) == 0) |
| 2361 | return tls_error(US"X509_STORE_load_locations", host, NULL, errstr); |
| 2362 | |
| 2363 | /* setting the flags to check against the complete crl chain */ |
| 2364 | |
| 2365 | X509_STORE_set_flags(cvstore, |
| 2366 | X509_V_FLAG_CRL_CHECK|X509_V_FLAG_CRL_CHECK_ALL); |
| 2367 | } |
| 2368 | } |
| 2369 | |
| 2370 | #endif /* OPENSSL_VERSION_NUMBER > 0x00907000L */ |
| 2371 | |
| 2372 | /* If verification is optional, don't fail if no certificate */ |
| 2373 | |
| 2374 | SSL_CTX_set_verify(sctx, |
| 2375 | SSL_VERIFY_PEER | (optional ? 0 : SSL_VERIFY_FAIL_IF_NO_PEER_CERT), |
| 2376 | cert_vfy_cb); |
| 2377 | } |
| 2378 | |
| 2379 | return OK; |
| 2380 | } |
| 2381 | |
| 2382 | |
| 2383 | |
| 2384 | /************************************************* |
| 2385 | * Start a TLS session in a server * |
| 2386 | *************************************************/ |
| 2387 | |
| 2388 | /* This is called when Exim is running as a server, after having received |
| 2389 | the STARTTLS command. It must respond to that command, and then negotiate |
| 2390 | a TLS session. |
| 2391 | |
| 2392 | Arguments: |
| 2393 | require_ciphers allowed ciphers |
| 2394 | errstr pointer to error message |
| 2395 | |
| 2396 | Returns: OK on success |
| 2397 | DEFER for errors before the start of the negotiation |
| 2398 | FAIL for errors during the negotiation; the server can't |
| 2399 | continue running. |
| 2400 | */ |
| 2401 | |
| 2402 | int |
| 2403 | tls_server_start(const uschar * require_ciphers, uschar ** errstr) |
| 2404 | { |
| 2405 | int rc; |
| 2406 | uschar * expciphers; |
| 2407 | tls_ext_ctx_cb * cbinfo; |
| 2408 | static uschar peerdn[256]; |
| 2409 | |
| 2410 | /* Check for previous activation */ |
| 2411 | |
| 2412 | if (tls_in.active.sock >= 0) |
| 2413 | { |
| 2414 | tls_error(US"STARTTLS received after TLS started", NULL, US"", errstr); |
| 2415 | smtp_printf("554 Already in TLS\r\n", FALSE); |
| 2416 | return FAIL; |
| 2417 | } |
| 2418 | |
| 2419 | /* Initialize the SSL library. If it fails, it will already have logged |
| 2420 | the error. */ |
| 2421 | |
| 2422 | rc = tls_init(&server_ctx, NULL, tls_dhparam, tls_certificate, tls_privatekey, |
| 2423 | #ifndef DISABLE_OCSP |
| 2424 | tls_ocsp_file, /*XXX stack*/ |
| 2425 | #endif |
| 2426 | NULL, &server_static_cbinfo, &tls_in, errstr); |
| 2427 | if (rc != OK) return rc; |
| 2428 | cbinfo = server_static_cbinfo; |
| 2429 | |
| 2430 | if (!expand_check(require_ciphers, US"tls_require_ciphers", &expciphers, errstr)) |
| 2431 | return FAIL; |
| 2432 | |
| 2433 | /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they |
| 2434 | were historically separated by underscores. So that I can use either form in my |
| 2435 | tests, and also for general convenience, we turn underscores into hyphens here. |
| 2436 | |
| 2437 | XXX SSL_CTX_set_cipher_list() is replaced by SSL_CTX_set_ciphersuites() |
| 2438 | for TLS 1.3 . Since we do not call it at present we get the default list: |
| 2439 | TLS_AES_256_GCM_SHA384:TLS_CHACHA20_POLY1305_SHA256:TLS_AES_128_GCM_SHA256 |
| 2440 | */ |
| 2441 | |
| 2442 | if (expciphers) |
| 2443 | { |
| 2444 | for (uschar * s = expciphers; *s; s++ ) if (*s == '_') *s = '-'; |
| 2445 | DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers); |
| 2446 | if (!SSL_CTX_set_cipher_list(server_ctx, CS expciphers)) |
| 2447 | return tls_error(US"SSL_CTX_set_cipher_list", NULL, NULL, errstr); |
| 2448 | cbinfo->server_cipher_list = expciphers; |
| 2449 | } |
| 2450 | |
| 2451 | /* If this is a host for which certificate verification is mandatory or |
| 2452 | optional, set up appropriately. */ |
| 2453 | |
| 2454 | tls_in.certificate_verified = FALSE; |
| 2455 | #ifdef SUPPORT_DANE |
| 2456 | tls_in.dane_verified = FALSE; |
| 2457 | #endif |
| 2458 | server_verify_callback_called = FALSE; |
| 2459 | |
| 2460 | if (verify_check_host(&tls_verify_hosts) == OK) |
| 2461 | { |
| 2462 | rc = setup_certs(server_ctx, tls_verify_certificates, tls_crl, NULL, |
| 2463 | FALSE, verify_callback_server, errstr); |
| 2464 | if (rc != OK) return rc; |
| 2465 | server_verify_optional = FALSE; |
| 2466 | } |
| 2467 | else if (verify_check_host(&tls_try_verify_hosts) == OK) |
| 2468 | { |
| 2469 | rc = setup_certs(server_ctx, tls_verify_certificates, tls_crl, NULL, |
| 2470 | TRUE, verify_callback_server, errstr); |
| 2471 | if (rc != OK) return rc; |
| 2472 | server_verify_optional = TRUE; |
| 2473 | } |
| 2474 | |
| 2475 | #ifdef EXPERIMENTAL_TLS_RESUME |
| 2476 | SSL_CTX_set_tlsext_ticket_key_cb(server_ctx, ticket_key_callback); |
| 2477 | /* despite working, appears to always return failure, so ignoring */ |
| 2478 | #endif |
| 2479 | #ifdef OPENSSL_HAVE_NUM_TICKETS |
| 2480 | # ifdef EXPERIMENTAL_TLS_RESUME |
| 2481 | SSL_CTX_set_num_tickets(server_ctx, tls_in.host_resumable ? 1 : 0); |
| 2482 | # else |
| 2483 | SSL_CTX_set_num_tickets(server_ctx, 0); /* send no TLS1.3 stateful-tickets */ |
| 2484 | # endif |
| 2485 | #endif |
| 2486 | |
| 2487 | |
| 2488 | /* Prepare for new connection */ |
| 2489 | |
| 2490 | if (!(server_ssl = SSL_new(server_ctx))) |
| 2491 | return tls_error(US"SSL_new", NULL, NULL, errstr); |
| 2492 | |
| 2493 | /* Warning: we used to SSL_clear(ssl) here, it was removed. |
| 2494 | * |
| 2495 | * With the SSL_clear(), we get strange interoperability bugs with |
| 2496 | * OpenSSL 1.0.1b and TLS1.1/1.2. It looks as though this may be a bug in |
| 2497 | * OpenSSL itself, as a clear should not lead to inability to follow protocols. |
| 2498 | * |
| 2499 | * The SSL_clear() call is to let an existing SSL* be reused, typically after |
| 2500 | * session shutdown. In this case, we have a brand new object and there's no |
| 2501 | * obvious reason to immediately clear it. I'm guessing that this was |
| 2502 | * originally added because of incomplete initialisation which the clear fixed, |
| 2503 | * in some historic release. |
| 2504 | */ |
| 2505 | |
| 2506 | /* Set context and tell client to go ahead, except in the case of TLS startup |
| 2507 | on connection, where outputting anything now upsets the clients and tends to |
| 2508 | make them disconnect. We need to have an explicit fflush() here, to force out |
| 2509 | the response. Other smtp_printf() calls do not need it, because in non-TLS |
| 2510 | mode, the fflush() happens when smtp_getc() is called. */ |
| 2511 | |
| 2512 | SSL_set_session_id_context(server_ssl, sid_ctx, Ustrlen(sid_ctx)); |
| 2513 | if (!tls_in.on_connect) |
| 2514 | { |
| 2515 | smtp_printf("220 TLS go ahead\r\n", FALSE); |
| 2516 | fflush(smtp_out); |
| 2517 | } |
| 2518 | |
| 2519 | /* Now negotiate the TLS session. We put our own timer on it, since it seems |
| 2520 | that the OpenSSL library doesn't. */ |
| 2521 | |
| 2522 | SSL_set_wfd(server_ssl, fileno(smtp_out)); |
| 2523 | SSL_set_rfd(server_ssl, fileno(smtp_in)); |
| 2524 | SSL_set_accept_state(server_ssl); |
| 2525 | |
| 2526 | DEBUG(D_tls) debug_printf("Calling SSL_accept\n"); |
| 2527 | |
| 2528 | sigalrm_seen = FALSE; |
| 2529 | if (smtp_receive_timeout > 0) ALARM(smtp_receive_timeout); |
| 2530 | rc = SSL_accept(server_ssl); |
| 2531 | ALARM_CLR(0); |
| 2532 | |
| 2533 | if (rc <= 0) |
| 2534 | { |
| 2535 | (void) tls_error(US"SSL_accept", NULL, sigalrm_seen ? US"timed out" : NULL, errstr); |
| 2536 | return FAIL; |
| 2537 | } |
| 2538 | |
| 2539 | DEBUG(D_tls) debug_printf("SSL_accept was successful\n"); |
| 2540 | ERR_clear_error(); /* Even success can leave errors in the stack. Seen with |
| 2541 | anon-authentication ciphersuite negotiated. */ |
| 2542 | |
| 2543 | #ifdef EXPERIMENTAL_TLS_RESUME |
| 2544 | if (SSL_session_reused(server_ssl)) |
| 2545 | { |
| 2546 | tls_in.resumption |= RESUME_USED; |
| 2547 | DEBUG(D_tls) debug_printf("Session reused\n"); |
| 2548 | } |
| 2549 | #endif |
| 2550 | |
| 2551 | /* TLS has been set up. Adjust the input functions to read via TLS, |
| 2552 | and initialize things. */ |
| 2553 | |
| 2554 | peer_cert(server_ssl, &tls_in, peerdn, sizeof(peerdn)); |
| 2555 | |
| 2556 | tls_in.cipher = construct_cipher_name(server_ssl, &tls_in.bits); |
| 2557 | tls_in.cipher_stdname = cipher_stdname_ssl(server_ssl); |
| 2558 | |
| 2559 | DEBUG(D_tls) |
| 2560 | { |
| 2561 | uschar buf[2048]; |
| 2562 | if (SSL_get_shared_ciphers(server_ssl, CS buf, sizeof(buf))) |
| 2563 | debug_printf("Shared ciphers: %s\n", buf); |
| 2564 | |
| 2565 | #ifdef EXIM_HAVE_OPENSSL_KEYLOG |
| 2566 | { |
| 2567 | BIO * bp = BIO_new_fp(debug_file, BIO_NOCLOSE); |
| 2568 | SSL_SESSION_print_keylog(bp, SSL_get_session(server_ssl)); |
| 2569 | BIO_free(bp); |
| 2570 | } |
| 2571 | #endif |
| 2572 | |
| 2573 | #ifdef EXIM_HAVE_SESSION_TICKET |
| 2574 | { |
| 2575 | SSL_SESSION * ss = SSL_get_session(server_ssl); |
| 2576 | if (SSL_SESSION_has_ticket(ss)) /* 1.1.0 */ |
| 2577 | debug_printf("The session has a ticket, life %lu seconds\n", |
| 2578 | SSL_SESSION_get_ticket_lifetime_hint(ss)); |
| 2579 | } |
| 2580 | #endif |
| 2581 | } |
| 2582 | |
| 2583 | /* Record the certificate we presented */ |
| 2584 | { |
| 2585 | X509 * crt = SSL_get_certificate(server_ssl); |
| 2586 | tls_in.ourcert = crt ? X509_dup(crt) : NULL; |
| 2587 | } |
| 2588 | |
| 2589 | /* Only used by the server-side tls (tls_in), including tls_getc. |
| 2590 | Client-side (tls_out) reads (seem to?) go via |
| 2591 | smtp_read_response()/ip_recv(). |
| 2592 | Hence no need to duplicate for _in and _out. |
| 2593 | */ |
| 2594 | if (!ssl_xfer_buffer) ssl_xfer_buffer = store_malloc(ssl_xfer_buffer_size); |
| 2595 | ssl_xfer_buffer_lwm = ssl_xfer_buffer_hwm = 0; |
| 2596 | ssl_xfer_eof = ssl_xfer_error = FALSE; |
| 2597 | |
| 2598 | receive_getc = tls_getc; |
| 2599 | receive_getbuf = tls_getbuf; |
| 2600 | receive_get_cache = tls_get_cache; |
| 2601 | receive_ungetc = tls_ungetc; |
| 2602 | receive_feof = tls_feof; |
| 2603 | receive_ferror = tls_ferror; |
| 2604 | receive_smtp_buffered = tls_smtp_buffered; |
| 2605 | |
| 2606 | tls_in.active.sock = fileno(smtp_out); |
| 2607 | tls_in.active.tls_ctx = NULL; /* not using explicit ctx for server-side */ |
| 2608 | return OK; |
| 2609 | } |
| 2610 | |
| 2611 | |
| 2612 | |
| 2613 | |
| 2614 | static int |
| 2615 | tls_client_basic_ctx_init(SSL_CTX * ctx, |
| 2616 | host_item * host, smtp_transport_options_block * ob, tls_ext_ctx_cb * cbinfo, |
| 2617 | uschar ** errstr) |
| 2618 | { |
| 2619 | int rc; |
| 2620 | /* stick to the old behaviour for compatibility if tls_verify_certificates is |
| 2621 | set but both tls_verify_hosts and tls_try_verify_hosts is not set. Check only |
| 2622 | the specified host patterns if one of them is defined */ |
| 2623 | |
| 2624 | if ( ( !ob->tls_verify_hosts |
| 2625 | && (!ob->tls_try_verify_hosts || !*ob->tls_try_verify_hosts) |
| 2626 | ) |
| 2627 | || verify_check_given_host(CUSS &ob->tls_verify_hosts, host) == OK |
| 2628 | ) |
| 2629 | client_verify_optional = FALSE; |
| 2630 | else if (verify_check_given_host(CUSS &ob->tls_try_verify_hosts, host) == OK) |
| 2631 | client_verify_optional = TRUE; |
| 2632 | else |
| 2633 | return OK; |
| 2634 | |
| 2635 | if ((rc = setup_certs(ctx, ob->tls_verify_certificates, |
| 2636 | ob->tls_crl, host, client_verify_optional, verify_callback_client, |
| 2637 | errstr)) != OK) |
| 2638 | return rc; |
| 2639 | |
| 2640 | if (verify_check_given_host(CUSS &ob->tls_verify_cert_hostnames, host) == OK) |
| 2641 | { |
| 2642 | cbinfo->verify_cert_hostnames = |
| 2643 | #ifdef SUPPORT_I18N |
| 2644 | string_domain_utf8_to_alabel(host->name, NULL); |
| 2645 | #else |
| 2646 | host->name; |
| 2647 | #endif |
| 2648 | DEBUG(D_tls) debug_printf("Cert hostname to check: \"%s\"\n", |
| 2649 | cbinfo->verify_cert_hostnames); |
| 2650 | } |
| 2651 | return OK; |
| 2652 | } |
| 2653 | |
| 2654 | |
| 2655 | #ifdef SUPPORT_DANE |
| 2656 | static int |
| 2657 | dane_tlsa_load(SSL * ssl, host_item * host, dns_answer * dnsa, uschar ** errstr) |
| 2658 | { |
| 2659 | dns_scan dnss; |
| 2660 | const char * hostnames[2] = { CS host->name, NULL }; |
| 2661 | int found = 0; |
| 2662 | |
| 2663 | if (DANESSL_init(ssl, NULL, hostnames) != 1) |
| 2664 | return tls_error(US"hostnames load", host, NULL, errstr); |
| 2665 | |
| 2666 | for (dns_record * rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS); rr; |
| 2667 | rr = dns_next_rr(dnsa, &dnss, RESET_NEXT) |
| 2668 | ) if (rr->type == T_TLSA && rr->size > 3) |
| 2669 | { |
| 2670 | const uschar * p = rr->data; |
| 2671 | uint8_t usage, selector, mtype; |
| 2672 | const char * mdname; |
| 2673 | |
| 2674 | usage = *p++; |
| 2675 | |
| 2676 | /* Only DANE-TA(2) and DANE-EE(3) are supported */ |
| 2677 | if (usage != 2 && usage != 3) continue; |
| 2678 | |
| 2679 | selector = *p++; |
| 2680 | mtype = *p++; |
| 2681 | |
| 2682 | switch (mtype) |
| 2683 | { |
| 2684 | default: continue; /* Only match-types 0, 1, 2 are supported */ |
| 2685 | case 0: mdname = NULL; break; |
| 2686 | case 1: mdname = "sha256"; break; |
| 2687 | case 2: mdname = "sha512"; break; |
| 2688 | } |
| 2689 | |
| 2690 | found++; |
| 2691 | switch (DANESSL_add_tlsa(ssl, usage, selector, mdname, p, rr->size - 3)) |
| 2692 | { |
| 2693 | default: |
| 2694 | return tls_error(US"tlsa load", host, NULL, errstr); |
| 2695 | case 0: /* action not taken */ |
| 2696 | case 1: break; |
| 2697 | } |
| 2698 | |
| 2699 | tls_out.tlsa_usage |= 1<<usage; |
| 2700 | } |
| 2701 | |
| 2702 | if (found) |
| 2703 | return OK; |
| 2704 | |
| 2705 | log_write(0, LOG_MAIN, "DANE error: No usable TLSA records"); |
| 2706 | return DEFER; |
| 2707 | } |
| 2708 | #endif /*SUPPORT_DANE*/ |
| 2709 | |
| 2710 | |
| 2711 | |
| 2712 | #ifdef EXPERIMENTAL_TLS_RESUME |
| 2713 | /* On the client, get any stashed session for the given IP from hints db |
| 2714 | and apply it to the ssl-connection for attempted resumption. */ |
| 2715 | |
| 2716 | static void |
| 2717 | tls_retrieve_session(tls_support * tlsp, SSL * ssl, const uschar * key) |
| 2718 | { |
| 2719 | tlsp->resumption |= RESUME_SUPPORTED; |
| 2720 | if (tlsp->host_resumable) |
| 2721 | { |
| 2722 | dbdata_tls_session * dt; |
| 2723 | int len; |
| 2724 | open_db dbblock, * dbm_file; |
| 2725 | |
| 2726 | tlsp->resumption |= RESUME_CLIENT_REQUESTED; |
| 2727 | DEBUG(D_tls) debug_printf("checking for resumable session for %s\n", key); |
| 2728 | if ((dbm_file = dbfn_open(US"tls", O_RDONLY, &dbblock, FALSE, FALSE))) |
| 2729 | { |
| 2730 | /* key for the db is the IP */ |
| 2731 | if ((dt = dbfn_read_with_length(dbm_file, key, &len))) |
| 2732 | { |
| 2733 | SSL_SESSION * ss = NULL; |
| 2734 | const uschar * sess_asn1 = dt->session; |
| 2735 | |
| 2736 | len -= sizeof(dbdata_tls_session); |
| 2737 | if (!(d2i_SSL_SESSION(&ss, &sess_asn1, (long)len))) |
| 2738 | { |
| 2739 | DEBUG(D_tls) |
| 2740 | { |
| 2741 | ERR_error_string_n(ERR_get_error(), |
| 2742 | ssl_errstring, sizeof(ssl_errstring)); |
| 2743 | debug_printf("decoding session: %s\n", ssl_errstring); |
| 2744 | } |
| 2745 | } |
| 2746 | #ifdef EXIM_HAVE_SESSION_TICKET |
| 2747 | else if ( SSL_SESSION_get_ticket_lifetime_hint(ss) + dt->time_stamp |
| 2748 | < time(NULL)) |
| 2749 | { |
| 2750 | DEBUG(D_tls) debug_printf("session expired\n"); |
| 2751 | dbfn_delete(dbm_file, key); |
| 2752 | } |
| 2753 | #endif |
| 2754 | else if (!SSL_set_session(ssl, ss)) |
| 2755 | { |
| 2756 | DEBUG(D_tls) |
| 2757 | { |
| 2758 | ERR_error_string_n(ERR_get_error(), |
| 2759 | ssl_errstring, sizeof(ssl_errstring)); |
| 2760 | debug_printf("applying session to ssl: %s\n", ssl_errstring); |
| 2761 | } |
| 2762 | } |
| 2763 | else |
| 2764 | { |
| 2765 | DEBUG(D_tls) debug_printf("good session\n"); |
| 2766 | tlsp->resumption |= RESUME_CLIENT_SUGGESTED; |
| 2767 | tlsp->verify_override = dt->verify_override; |
| 2768 | tlsp->ocsp = dt->ocsp; |
| 2769 | } |
| 2770 | } |
| 2771 | else |
| 2772 | DEBUG(D_tls) debug_printf("no session record\n"); |
| 2773 | dbfn_close(dbm_file); |
| 2774 | } |
| 2775 | } |
| 2776 | } |
| 2777 | |
| 2778 | |
| 2779 | /* On the client, save the session for later resumption */ |
| 2780 | |
| 2781 | static int |
| 2782 | tls_save_session_cb(SSL * ssl, SSL_SESSION * ss) |
| 2783 | { |
| 2784 | tls_ext_ctx_cb * cbinfo = SSL_get_ex_data(ssl, tls_exdata_idx); |
| 2785 | tls_support * tlsp; |
| 2786 | |
| 2787 | DEBUG(D_tls) debug_printf("tls_save_session_cb\n"); |
| 2788 | |
| 2789 | if (!cbinfo || !(tlsp = cbinfo->tlsp)->host_resumable) return 0; |
| 2790 | |
| 2791 | # ifdef OPENSSL_HAVE_NUM_TICKETS |
| 2792 | if (SSL_SESSION_is_resumable(ss)) /* 1.1.1 */ |
| 2793 | # endif |
| 2794 | { |
| 2795 | int len = i2d_SSL_SESSION(ss, NULL); |
| 2796 | int dlen = sizeof(dbdata_tls_session) + len; |
| 2797 | dbdata_tls_session * dt = store_get(dlen, TRUE); |
| 2798 | uschar * s = dt->session; |
| 2799 | open_db dbblock, * dbm_file; |
| 2800 | |
| 2801 | DEBUG(D_tls) debug_printf("session is resumable\n"); |
| 2802 | tlsp->resumption |= RESUME_SERVER_TICKET; /* server gave us a ticket */ |
| 2803 | |
| 2804 | dt->verify_override = tlsp->verify_override; |
| 2805 | dt->ocsp = tlsp->ocsp; |
| 2806 | (void) i2d_SSL_SESSION(ss, &s); /* s gets bumped to end */ |
| 2807 | |
| 2808 | if ((dbm_file = dbfn_open(US"tls", O_RDWR, &dbblock, FALSE, FALSE))) |
| 2809 | { |
| 2810 | const uschar * key = cbinfo->host->address; |
| 2811 | dbfn_delete(dbm_file, key); |
| 2812 | dbfn_write(dbm_file, key, dt, dlen); |
| 2813 | dbfn_close(dbm_file); |
| 2814 | DEBUG(D_tls) debug_printf("wrote session (len %u) to db\n", |
| 2815 | (unsigned)dlen); |
| 2816 | } |
| 2817 | } |
| 2818 | return 1; |
| 2819 | } |
| 2820 | |
| 2821 | |
| 2822 | static void |
| 2823 | tls_client_ctx_resume_prehandshake( |
| 2824 | exim_openssl_client_tls_ctx * exim_client_ctx, tls_support * tlsp, |
| 2825 | smtp_transport_options_block * ob, host_item * host) |
| 2826 | { |
| 2827 | /* Should the client request a session resumption ticket? */ |
| 2828 | if (verify_check_given_host(CUSS &ob->tls_resumption_hosts, host) == OK) |
| 2829 | { |
| 2830 | tlsp->host_resumable = TRUE; |
| 2831 | |
| 2832 | SSL_CTX_set_session_cache_mode(exim_client_ctx->ctx, |
| 2833 | SSL_SESS_CACHE_CLIENT |
| 2834 | | SSL_SESS_CACHE_NO_INTERNAL | SSL_SESS_CACHE_NO_AUTO_CLEAR); |
| 2835 | SSL_CTX_sess_set_new_cb(exim_client_ctx->ctx, tls_save_session_cb); |
| 2836 | } |
| 2837 | } |
| 2838 | |
| 2839 | static BOOL |
| 2840 | tls_client_ssl_resume_prehandshake(SSL * ssl, tls_support * tlsp, |
| 2841 | host_item * host, uschar ** errstr) |
| 2842 | { |
| 2843 | if (tlsp->host_resumable) |
| 2844 | { |
| 2845 | DEBUG(D_tls) |
| 2846 | debug_printf("tls_resumption_hosts overrides openssl_options, enabling tickets\n"); |
| 2847 | SSL_clear_options(ssl, SSL_OP_NO_TICKET); |
| 2848 | |
| 2849 | tls_exdata_idx = SSL_get_ex_new_index(0, 0, 0, 0, 0); |
| 2850 | if (!SSL_set_ex_data(ssl, tls_exdata_idx, client_static_cbinfo)) |
| 2851 | { |
| 2852 | tls_error(US"set ex_data", host, NULL, errstr); |
| 2853 | return FALSE; |
| 2854 | } |
| 2855 | debug_printf("tls_exdata_idx %d cbinfo %p\n", tls_exdata_idx, client_static_cbinfo); |
| 2856 | } |
| 2857 | |
| 2858 | tlsp->resumption = RESUME_SUPPORTED; |
| 2859 | /* Pick up a previous session, saved on an old ticket */ |
| 2860 | tls_retrieve_session(tlsp, ssl, host->address); |
| 2861 | return TRUE; |
| 2862 | } |
| 2863 | |
| 2864 | static void |
| 2865 | tls_client_resume_posthandshake(exim_openssl_client_tls_ctx * exim_client_ctx, |
| 2866 | tls_support * tlsp) |
| 2867 | { |
| 2868 | if (SSL_session_reused(exim_client_ctx->ssl)) |
| 2869 | { |
| 2870 | DEBUG(D_tls) debug_printf("The session was reused\n"); |
| 2871 | tlsp->resumption |= RESUME_USED; |
| 2872 | } |
| 2873 | } |
| 2874 | #endif /* EXPERIMENTAL_TLS_RESUME */ |
| 2875 | |
| 2876 | |
| 2877 | /************************************************* |
| 2878 | * Start a TLS session in a client * |
| 2879 | *************************************************/ |
| 2880 | |
| 2881 | /* Called from the smtp transport after STARTTLS has been accepted. |
| 2882 | |
| 2883 | Arguments: |
| 2884 | cctx connection context |
| 2885 | conn_args connection details |
| 2886 | cookie datum for randomness; can be NULL |
| 2887 | tlsp record details of TLS channel configuration here; must be non-NULL |
| 2888 | errstr error string pointer |
| 2889 | |
| 2890 | Returns: TRUE for success with TLS session context set in connection context, |
| 2891 | FALSE on error |
| 2892 | */ |
| 2893 | |
| 2894 | BOOL |
| 2895 | tls_client_start(client_conn_ctx * cctx, smtp_connect_args * conn_args, |
| 2896 | void * cookie, tls_support * tlsp, uschar ** errstr) |
| 2897 | { |
| 2898 | host_item * host = conn_args->host; /* for msgs and option-tests */ |
| 2899 | transport_instance * tb = conn_args->tblock; /* always smtp or NULL */ |
| 2900 | smtp_transport_options_block * ob = tb |
| 2901 | ? (smtp_transport_options_block *)tb->options_block |
| 2902 | : &smtp_transport_option_defaults; |
| 2903 | exim_openssl_client_tls_ctx * exim_client_ctx; |
| 2904 | uschar * expciphers; |
| 2905 | int rc; |
| 2906 | static uschar peerdn[256]; |
| 2907 | |
| 2908 | #ifndef DISABLE_OCSP |
| 2909 | BOOL request_ocsp = FALSE; |
| 2910 | BOOL require_ocsp = FALSE; |
| 2911 | #endif |
| 2912 | |
| 2913 | rc = store_pool; |
| 2914 | store_pool = POOL_PERM; |
| 2915 | exim_client_ctx = store_get(sizeof(exim_openssl_client_tls_ctx), FALSE); |
| 2916 | exim_client_ctx->corked = NULL; |
| 2917 | store_pool = rc; |
| 2918 | |
| 2919 | #ifdef SUPPORT_DANE |
| 2920 | tlsp->tlsa_usage = 0; |
| 2921 | #endif |
| 2922 | |
| 2923 | #ifndef DISABLE_OCSP |
| 2924 | { |
| 2925 | # ifdef SUPPORT_DANE |
| 2926 | if ( conn_args->dane |
| 2927 | && ob->hosts_request_ocsp[0] == '*' |
| 2928 | && ob->hosts_request_ocsp[1] == '\0' |
| 2929 | ) |
| 2930 | { |
| 2931 | /* Unchanged from default. Use a safer one under DANE */ |
| 2932 | request_ocsp = TRUE; |
| 2933 | ob->hosts_request_ocsp = US"${if or { {= {0}{$tls_out_tlsa_usage}} " |
| 2934 | " {= {4}{$tls_out_tlsa_usage}} } " |
| 2935 | " {*}{}}"; |
| 2936 | } |
| 2937 | # endif |
| 2938 | |
| 2939 | if ((require_ocsp = |
| 2940 | verify_check_given_host(CUSS &ob->hosts_require_ocsp, host) == OK)) |
| 2941 | request_ocsp = TRUE; |
| 2942 | else |
| 2943 | # ifdef SUPPORT_DANE |
| 2944 | if (!request_ocsp) |
| 2945 | # endif |
| 2946 | request_ocsp = |
| 2947 | verify_check_given_host(CUSS &ob->hosts_request_ocsp, host) == OK; |
| 2948 | } |
| 2949 | #endif |
| 2950 | |
| 2951 | rc = tls_init(&exim_client_ctx->ctx, host, NULL, |
| 2952 | ob->tls_certificate, ob->tls_privatekey, |
| 2953 | #ifndef DISABLE_OCSP |
| 2954 | (void *)(long)request_ocsp, |
| 2955 | #endif |
| 2956 | cookie, &client_static_cbinfo, tlsp, errstr); |
| 2957 | if (rc != OK) return FALSE; |
| 2958 | |
| 2959 | tlsp->certificate_verified = FALSE; |
| 2960 | client_verify_callback_called = FALSE; |
| 2961 | |
| 2962 | expciphers = NULL; |
| 2963 | #ifdef SUPPORT_DANE |
| 2964 | if (conn_args->dane) |
| 2965 | { |
| 2966 | /* We fall back to tls_require_ciphers if unset, empty or forced failure, but |
| 2967 | other failures should be treated as problems. */ |
| 2968 | if (ob->dane_require_tls_ciphers && |
| 2969 | !expand_check(ob->dane_require_tls_ciphers, US"dane_require_tls_ciphers", |
| 2970 | &expciphers, errstr)) |
| 2971 | return FALSE; |
| 2972 | if (expciphers && *expciphers == '\0') |
| 2973 | expciphers = NULL; |
| 2974 | } |
| 2975 | #endif |
| 2976 | if (!expciphers && |
| 2977 | !expand_check(ob->tls_require_ciphers, US"tls_require_ciphers", |
| 2978 | &expciphers, errstr)) |
| 2979 | return FALSE; |
| 2980 | |
| 2981 | /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they |
| 2982 | are separated by underscores. So that I can use either form in my tests, and |
| 2983 | also for general convenience, we turn underscores into hyphens here. */ |
| 2984 | |
| 2985 | if (expciphers) |
| 2986 | { |
| 2987 | uschar *s = expciphers; |
| 2988 | while (*s) { if (*s == '_') *s = '-'; s++; } |
| 2989 | DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers); |
| 2990 | if (!SSL_CTX_set_cipher_list(exim_client_ctx->ctx, CS expciphers)) |
| 2991 | { |
| 2992 | tls_error(US"SSL_CTX_set_cipher_list", host, NULL, errstr); |
| 2993 | return FALSE; |
| 2994 | } |
| 2995 | } |
| 2996 | |
| 2997 | #ifdef SUPPORT_DANE |
| 2998 | if (conn_args->dane) |
| 2999 | { |
| 3000 | SSL_CTX_set_verify(exim_client_ctx->ctx, |
| 3001 | SSL_VERIFY_PEER | SSL_VERIFY_FAIL_IF_NO_PEER_CERT, |
| 3002 | verify_callback_client_dane); |
| 3003 | |
| 3004 | if (!DANESSL_library_init()) |
| 3005 | { |
| 3006 | tls_error(US"library init", host, NULL, errstr); |
| 3007 | return FALSE; |
| 3008 | } |
| 3009 | if (DANESSL_CTX_init(exim_client_ctx->ctx) <= 0) |
| 3010 | { |
| 3011 | tls_error(US"context init", host, NULL, errstr); |
| 3012 | return FALSE; |
| 3013 | } |
| 3014 | } |
| 3015 | else |
| 3016 | |
| 3017 | #endif |
| 3018 | |
| 3019 | if (tls_client_basic_ctx_init(exim_client_ctx->ctx, host, ob, |
| 3020 | client_static_cbinfo, errstr) != OK) |
| 3021 | return FALSE; |
| 3022 | |
| 3023 | #ifdef EXPERIMENTAL_TLS_RESUME |
| 3024 | tls_client_ctx_resume_prehandshake(exim_client_ctx, tlsp, ob, host); |
| 3025 | #endif |
| 3026 | |
| 3027 | |
| 3028 | if (!(exim_client_ctx->ssl = SSL_new(exim_client_ctx->ctx))) |
| 3029 | { |
| 3030 | tls_error(US"SSL_new", host, NULL, errstr); |
| 3031 | return FALSE; |
| 3032 | } |
| 3033 | SSL_set_session_id_context(exim_client_ctx->ssl, sid_ctx, Ustrlen(sid_ctx)); |
| 3034 | |
| 3035 | SSL_set_fd(exim_client_ctx->ssl, cctx->sock); |
| 3036 | SSL_set_connect_state(exim_client_ctx->ssl); |
| 3037 | |
| 3038 | if (ob->tls_sni) |
| 3039 | { |
| 3040 | if (!expand_check(ob->tls_sni, US"tls_sni", &tlsp->sni, errstr)) |
| 3041 | return FALSE; |
| 3042 | if (!tlsp->sni) |
| 3043 | { |
| 3044 | DEBUG(D_tls) debug_printf("Setting TLS SNI forced to fail, not sending\n"); |
| 3045 | } |
| 3046 | else if (!Ustrlen(tlsp->sni)) |
| 3047 | tlsp->sni = NULL; |
| 3048 | else |
| 3049 | { |
| 3050 | #ifdef EXIM_HAVE_OPENSSL_TLSEXT |
| 3051 | DEBUG(D_tls) debug_printf("Setting TLS SNI \"%s\"\n", tlsp->sni); |
| 3052 | SSL_set_tlsext_host_name(exim_client_ctx->ssl, tlsp->sni); |
| 3053 | #else |
| 3054 | log_write(0, LOG_MAIN, "SNI unusable with this OpenSSL library version; ignoring \"%s\"\n", |
| 3055 | tlsp->sni); |
| 3056 | #endif |
| 3057 | } |
| 3058 | } |
| 3059 | |
| 3060 | #ifdef SUPPORT_DANE |
| 3061 | if (conn_args->dane) |
| 3062 | if (dane_tlsa_load(exim_client_ctx->ssl, host, &conn_args->tlsa_dnsa, errstr) != OK) |
| 3063 | return FALSE; |
| 3064 | #endif |
| 3065 | |
| 3066 | #ifndef DISABLE_OCSP |
| 3067 | /* Request certificate status at connection-time. If the server |
| 3068 | does OCSP stapling we will get the callback (set in tls_init()) */ |
| 3069 | # ifdef SUPPORT_DANE |
| 3070 | if (request_ocsp) |
| 3071 | { |
| 3072 | const uschar * s; |
| 3073 | if ( ((s = ob->hosts_require_ocsp) && Ustrstr(s, US"tls_out_tlsa_usage")) |
| 3074 | || ((s = ob->hosts_request_ocsp) && Ustrstr(s, US"tls_out_tlsa_usage")) |
| 3075 | ) |
| 3076 | { /* Re-eval now $tls_out_tlsa_usage is populated. If |
| 3077 | this means we avoid the OCSP request, we wasted the setup |
| 3078 | cost in tls_init(). */ |
| 3079 | require_ocsp = verify_check_given_host(CUSS &ob->hosts_require_ocsp, host) == OK; |
| 3080 | request_ocsp = require_ocsp |
| 3081 | || verify_check_given_host(CUSS &ob->hosts_request_ocsp, host) == OK; |
| 3082 | } |
| 3083 | } |
| 3084 | # endif |
| 3085 | |
| 3086 | if (request_ocsp) |
| 3087 | { |
| 3088 | SSL_set_tlsext_status_type(exim_client_ctx->ssl, TLSEXT_STATUSTYPE_ocsp); |
| 3089 | client_static_cbinfo->u_ocsp.client.verify_required = require_ocsp; |
| 3090 | tlsp->ocsp = OCSP_NOT_RESP; |
| 3091 | } |
| 3092 | #endif |
| 3093 | |
| 3094 | #ifdef EXPERIMENTAL_TLS_RESUME |
| 3095 | if (!tls_client_ssl_resume_prehandshake(exim_client_ctx->ssl, tlsp, host, |
| 3096 | errstr)) |
| 3097 | return FALSE; |
| 3098 | #endif |
| 3099 | |
| 3100 | #ifndef DISABLE_EVENT |
| 3101 | client_static_cbinfo->event_action = tb ? tb->event_action : NULL; |
| 3102 | #endif |
| 3103 | |
| 3104 | /* There doesn't seem to be a built-in timeout on connection. */ |
| 3105 | |
| 3106 | DEBUG(D_tls) debug_printf("Calling SSL_connect\n"); |
| 3107 | sigalrm_seen = FALSE; |
| 3108 | ALARM(ob->command_timeout); |
| 3109 | rc = SSL_connect(exim_client_ctx->ssl); |
| 3110 | ALARM_CLR(0); |
| 3111 | |
| 3112 | #ifdef SUPPORT_DANE |
| 3113 | if (conn_args->dane) |
| 3114 | DANESSL_cleanup(exim_client_ctx->ssl); |
| 3115 | #endif |
| 3116 | |
| 3117 | if (rc <= 0) |
| 3118 | { |
| 3119 | tls_error(US"SSL_connect", host, sigalrm_seen ? US"timed out" : NULL, errstr); |
| 3120 | return FALSE; |
| 3121 | } |
| 3122 | |
| 3123 | DEBUG(D_tls) |
| 3124 | { |
| 3125 | debug_printf("SSL_connect succeeded\n"); |
| 3126 | #ifdef EXIM_HAVE_OPENSSL_KEYLOG |
| 3127 | { |
| 3128 | BIO * bp = BIO_new_fp(debug_file, BIO_NOCLOSE); |
| 3129 | SSL_SESSION_print_keylog(bp, SSL_get_session(exim_client_ctx->ssl)); |
| 3130 | BIO_free(bp); |
| 3131 | } |
| 3132 | #endif |
| 3133 | } |
| 3134 | |
| 3135 | #ifdef EXPERIMENTAL_TLS_RESUME |
| 3136 | tls_client_resume_posthandshake(exim_client_ctx, tlsp); |
| 3137 | #endif |
| 3138 | |
| 3139 | peer_cert(exim_client_ctx->ssl, tlsp, peerdn, sizeof(peerdn)); |
| 3140 | |
| 3141 | tlsp->cipher = construct_cipher_name(exim_client_ctx->ssl, &tlsp->bits); |
| 3142 | tlsp->cipher_stdname = cipher_stdname_ssl(exim_client_ctx->ssl); |
| 3143 | |
| 3144 | /* Record the certificate we presented */ |
| 3145 | { |
| 3146 | X509 * crt = SSL_get_certificate(exim_client_ctx->ssl); |
| 3147 | tlsp->ourcert = crt ? X509_dup(crt) : NULL; |
| 3148 | } |
| 3149 | |
| 3150 | tlsp->active.sock = cctx->sock; |
| 3151 | tlsp->active.tls_ctx = exim_client_ctx; |
| 3152 | cctx->tls_ctx = exim_client_ctx; |
| 3153 | return TRUE; |
| 3154 | } |
| 3155 | |
| 3156 | |
| 3157 | |
| 3158 | |
| 3159 | |
| 3160 | static BOOL |
| 3161 | tls_refill(unsigned lim) |
| 3162 | { |
| 3163 | int error; |
| 3164 | int inbytes; |
| 3165 | |
| 3166 | DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", server_ssl, |
| 3167 | ssl_xfer_buffer, ssl_xfer_buffer_size); |
| 3168 | |
| 3169 | if (smtp_receive_timeout > 0) ALARM(smtp_receive_timeout); |
| 3170 | inbytes = SSL_read(server_ssl, CS ssl_xfer_buffer, |
| 3171 | MIN(ssl_xfer_buffer_size, lim)); |
| 3172 | error = SSL_get_error(server_ssl, inbytes); |
| 3173 | if (smtp_receive_timeout > 0) ALARM_CLR(0); |
| 3174 | |
| 3175 | if (had_command_timeout) /* set by signal handler */ |
| 3176 | smtp_command_timeout_exit(); /* does not return */ |
| 3177 | if (had_command_sigterm) |
| 3178 | smtp_command_sigterm_exit(); |
| 3179 | if (had_data_timeout) |
| 3180 | smtp_data_timeout_exit(); |
| 3181 | if (had_data_sigint) |
| 3182 | smtp_data_sigint_exit(); |
| 3183 | |
| 3184 | /* SSL_ERROR_ZERO_RETURN appears to mean that the SSL session has been |
| 3185 | closed down, not that the socket itself has been closed down. Revert to |
| 3186 | non-SSL handling. */ |
| 3187 | |
| 3188 | switch(error) |
| 3189 | { |
| 3190 | case SSL_ERROR_NONE: |
| 3191 | break; |
| 3192 | |
| 3193 | case SSL_ERROR_ZERO_RETURN: |
| 3194 | DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n"); |
| 3195 | |
| 3196 | if (SSL_get_shutdown(server_ssl) == SSL_RECEIVED_SHUTDOWN) |
| 3197 | SSL_shutdown(server_ssl); |
| 3198 | |
| 3199 | tls_close(NULL, TLS_NO_SHUTDOWN); |
| 3200 | return FALSE; |
| 3201 | |
| 3202 | /* Handle genuine errors */ |
| 3203 | case SSL_ERROR_SSL: |
| 3204 | ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring)); |
| 3205 | log_write(0, LOG_MAIN, "TLS error (SSL_read): %s", ssl_errstring); |
| 3206 | ssl_xfer_error = TRUE; |
| 3207 | return FALSE; |
| 3208 | |
| 3209 | default: |
| 3210 | DEBUG(D_tls) debug_printf("Got SSL error %d\n", error); |
| 3211 | DEBUG(D_tls) if (error == SSL_ERROR_SYSCALL) |
| 3212 | debug_printf(" - syscall %s\n", strerror(errno)); |
| 3213 | ssl_xfer_error = TRUE; |
| 3214 | return FALSE; |
| 3215 | } |
| 3216 | |
| 3217 | #ifndef DISABLE_DKIM |
| 3218 | dkim_exim_verify_feed(ssl_xfer_buffer, inbytes); |
| 3219 | #endif |
| 3220 | ssl_xfer_buffer_hwm = inbytes; |
| 3221 | ssl_xfer_buffer_lwm = 0; |
| 3222 | return TRUE; |
| 3223 | } |
| 3224 | |
| 3225 | |
| 3226 | /************************************************* |
| 3227 | * TLS version of getc * |
| 3228 | *************************************************/ |
| 3229 | |
| 3230 | /* This gets the next byte from the TLS input buffer. If the buffer is empty, |
| 3231 | it refills the buffer via the SSL reading function. |
| 3232 | |
| 3233 | Arguments: lim Maximum amount to read/buffer |
| 3234 | Returns: the next character or EOF |
| 3235 | |
| 3236 | Only used by the server-side TLS. |
| 3237 | */ |
| 3238 | |
| 3239 | int |
| 3240 | tls_getc(unsigned lim) |
| 3241 | { |
| 3242 | if (ssl_xfer_buffer_lwm >= ssl_xfer_buffer_hwm) |
| 3243 | if (!tls_refill(lim)) |
| 3244 | return ssl_xfer_error ? EOF : smtp_getc(lim); |
| 3245 | |
| 3246 | /* Something in the buffer; return next uschar */ |
| 3247 | |
| 3248 | return ssl_xfer_buffer[ssl_xfer_buffer_lwm++]; |
| 3249 | } |
| 3250 | |
| 3251 | uschar * |
| 3252 | tls_getbuf(unsigned * len) |
| 3253 | { |
| 3254 | unsigned size; |
| 3255 | uschar * buf; |
| 3256 | |
| 3257 | if (ssl_xfer_buffer_lwm >= ssl_xfer_buffer_hwm) |
| 3258 | if (!tls_refill(*len)) |
| 3259 | { |
| 3260 | if (!ssl_xfer_error) return smtp_getbuf(len); |
| 3261 | *len = 0; |
| 3262 | return NULL; |
| 3263 | } |
| 3264 | |
| 3265 | if ((size = ssl_xfer_buffer_hwm - ssl_xfer_buffer_lwm) > *len) |
| 3266 | size = *len; |
| 3267 | buf = &ssl_xfer_buffer[ssl_xfer_buffer_lwm]; |
| 3268 | ssl_xfer_buffer_lwm += size; |
| 3269 | *len = size; |
| 3270 | return buf; |
| 3271 | } |
| 3272 | |
| 3273 | |
| 3274 | void |
| 3275 | tls_get_cache() |
| 3276 | { |
| 3277 | #ifndef DISABLE_DKIM |
| 3278 | int n = ssl_xfer_buffer_hwm - ssl_xfer_buffer_lwm; |
| 3279 | if (n > 0) |
| 3280 | dkim_exim_verify_feed(ssl_xfer_buffer+ssl_xfer_buffer_lwm, n); |
| 3281 | #endif |
| 3282 | } |
| 3283 | |
| 3284 | |
| 3285 | BOOL |
| 3286 | tls_could_read(void) |
| 3287 | { |
| 3288 | return ssl_xfer_buffer_lwm < ssl_xfer_buffer_hwm || SSL_pending(server_ssl) > 0; |
| 3289 | } |
| 3290 | |
| 3291 | |
| 3292 | /************************************************* |
| 3293 | * Read bytes from TLS channel * |
| 3294 | *************************************************/ |
| 3295 | |
| 3296 | /* |
| 3297 | Arguments: |
| 3298 | ct_ctx client context pointer, or NULL for the one global server context |
| 3299 | buff buffer of data |
| 3300 | len size of buffer |
| 3301 | |
| 3302 | Returns: the number of bytes read |
| 3303 | -1 after a failed read, including EOF |
| 3304 | |
| 3305 | Only used by the client-side TLS. |
| 3306 | */ |
| 3307 | |
| 3308 | int |
| 3309 | tls_read(void * ct_ctx, uschar *buff, size_t len) |
| 3310 | { |
| 3311 | SSL * ssl = ct_ctx ? ((exim_openssl_client_tls_ctx *)ct_ctx)->ssl : server_ssl; |
| 3312 | int inbytes; |
| 3313 | int error; |
| 3314 | |
| 3315 | DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", ssl, |
| 3316 | buff, (unsigned int)len); |
| 3317 | |
| 3318 | inbytes = SSL_read(ssl, CS buff, len); |
| 3319 | error = SSL_get_error(ssl, inbytes); |
| 3320 | |
| 3321 | if (error == SSL_ERROR_ZERO_RETURN) |
| 3322 | { |
| 3323 | DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n"); |
| 3324 | return -1; |
| 3325 | } |
| 3326 | else if (error != SSL_ERROR_NONE) |
| 3327 | return -1; |
| 3328 | |
| 3329 | return inbytes; |
| 3330 | } |
| 3331 | |
| 3332 | |
| 3333 | |
| 3334 | |
| 3335 | |
| 3336 | /************************************************* |
| 3337 | * Write bytes down TLS channel * |
| 3338 | *************************************************/ |
| 3339 | |
| 3340 | /* |
| 3341 | Arguments: |
| 3342 | ct_ctx client context pointer, or NULL for the one global server context |
| 3343 | buff buffer of data |
| 3344 | len number of bytes |
| 3345 | more further data expected soon |
| 3346 | |
| 3347 | Returns: the number of bytes after a successful write, |
| 3348 | -1 after a failed write |
| 3349 | |
| 3350 | Used by both server-side and client-side TLS. |
| 3351 | */ |
| 3352 | |
| 3353 | int |
| 3354 | tls_write(void * ct_ctx, const uschar *buff, size_t len, BOOL more) |
| 3355 | { |
| 3356 | size_t olen = len; |
| 3357 | int outbytes, error; |
| 3358 | SSL * ssl = ct_ctx |
| 3359 | ? ((exim_openssl_client_tls_ctx *)ct_ctx)->ssl : server_ssl; |
| 3360 | static gstring * server_corked = NULL; |
| 3361 | gstring ** corkedp = ct_ctx |
| 3362 | ? &((exim_openssl_client_tls_ctx *)ct_ctx)->corked : &server_corked; |
| 3363 | gstring * corked = *corkedp; |
| 3364 | |
| 3365 | DEBUG(D_tls) debug_printf("%s(%p, %lu%s)\n", __FUNCTION__, |
| 3366 | buff, (unsigned long)len, more ? ", more" : ""); |
| 3367 | |
| 3368 | /* Lacking a CORK or MSG_MORE facility (such as GnuTLS has) we copy data when |
| 3369 | "more" is notified. This hack is only ok if small amounts are involved AND only |
| 3370 | one stream does it, in one context (i.e. no store reset). Currently it is used |
| 3371 | for the responses to the received SMTP MAIL , RCPT, DATA sequence, only. |
| 3372 | We support callouts done by the server process by using a separate client |
| 3373 | context for the stashed information. */ |
| 3374 | /* + if PIPE_COMMAND, banner & ehlo-resp for smmtp-on-connect. Suspect there's |
| 3375 | a store reset there, so use POOL_PERM. */ |
| 3376 | /* + if CHUNKING, cmds EHLO,MAIL,RCPT(s),BDAT */ |
| 3377 | |
| 3378 | if ((more || corked)) |
| 3379 | { |
| 3380 | #ifdef SUPPORT_PIPE_CONNECT |
| 3381 | int save_pool = store_pool; |
| 3382 | store_pool = POOL_PERM; |
| 3383 | #endif |
| 3384 | |
| 3385 | corked = string_catn(corked, buff, len); |
| 3386 | |
| 3387 | #ifdef SUPPORT_PIPE_CONNECT |
| 3388 | store_pool = save_pool; |
| 3389 | #endif |
| 3390 | |
| 3391 | if (more) |
| 3392 | { |
| 3393 | *corkedp = corked; |
| 3394 | return len; |
| 3395 | } |
| 3396 | buff = CUS corked->s; |
| 3397 | len = corked->ptr; |
| 3398 | *corkedp = NULL; |
| 3399 | } |
| 3400 | |
| 3401 | for (int left = len; left > 0;) |
| 3402 | { |
| 3403 | DEBUG(D_tls) debug_printf("SSL_write(%p, %p, %d)\n", ssl, buff, left); |
| 3404 | outbytes = SSL_write(ssl, CS buff, left); |
| 3405 | error = SSL_get_error(ssl, outbytes); |
| 3406 | DEBUG(D_tls) debug_printf("outbytes=%d error=%d\n", outbytes, error); |
| 3407 | switch (error) |
| 3408 | { |
| 3409 | case SSL_ERROR_SSL: |
| 3410 | ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring)); |
| 3411 | log_write(0, LOG_MAIN, "TLS error (SSL_write): %s", ssl_errstring); |
| 3412 | return -1; |
| 3413 | |
| 3414 | case SSL_ERROR_NONE: |
| 3415 | left -= outbytes; |
| 3416 | buff += outbytes; |
| 3417 | break; |
| 3418 | |
| 3419 | case SSL_ERROR_ZERO_RETURN: |
| 3420 | log_write(0, LOG_MAIN, "SSL channel closed on write"); |
| 3421 | return -1; |
| 3422 | |
| 3423 | case SSL_ERROR_SYSCALL: |
| 3424 | log_write(0, LOG_MAIN, "SSL_write: (from %s) syscall: %s", |
| 3425 | sender_fullhost ? sender_fullhost : US"<unknown>", |
| 3426 | strerror(errno)); |
| 3427 | return -1; |
| 3428 | |
| 3429 | default: |
| 3430 | log_write(0, LOG_MAIN, "SSL_write error %d", error); |
| 3431 | return -1; |
| 3432 | } |
| 3433 | } |
| 3434 | return olen; |
| 3435 | } |
| 3436 | |
| 3437 | |
| 3438 | |
| 3439 | /************************************************* |
| 3440 | * Close down a TLS session * |
| 3441 | *************************************************/ |
| 3442 | |
| 3443 | /* This is also called from within a delivery subprocess forked from the |
| 3444 | daemon, to shut down the TLS library, without actually doing a shutdown (which |
| 3445 | would tamper with the SSL session in the parent process). |
| 3446 | |
| 3447 | Arguments: |
| 3448 | ct_ctx client TLS context pointer, or NULL for the one global server context |
| 3449 | shutdown 1 if TLS close-alert is to be sent, |
| 3450 | 2 if also response to be waited for |
| 3451 | |
| 3452 | Returns: nothing |
| 3453 | |
| 3454 | Used by both server-side and client-side TLS. |
| 3455 | */ |
| 3456 | |
| 3457 | void |
| 3458 | tls_close(void * ct_ctx, int shutdown) |
| 3459 | { |
| 3460 | exim_openssl_client_tls_ctx * o_ctx = ct_ctx; |
| 3461 | SSL_CTX **ctxp = o_ctx ? &o_ctx->ctx : &server_ctx; |
| 3462 | SSL **sslp = o_ctx ? &o_ctx->ssl : &server_ssl; |
| 3463 | int *fdp = o_ctx ? &tls_out.active.sock : &tls_in.active.sock; |
| 3464 | |
| 3465 | if (*fdp < 0) return; /* TLS was not active */ |
| 3466 | |
| 3467 | if (shutdown) |
| 3468 | { |
| 3469 | int rc; |
| 3470 | DEBUG(D_tls) debug_printf("tls_close(): shutting down TLS%s\n", |
| 3471 | shutdown > 1 ? " (with response-wait)" : ""); |
| 3472 | |
| 3473 | if ( (rc = SSL_shutdown(*sslp)) == 0 /* send "close notify" alert */ |
| 3474 | && shutdown > 1) |
| 3475 | { |
| 3476 | ALARM(2); |
| 3477 | rc = SSL_shutdown(*sslp); /* wait for response */ |
| 3478 | ALARM_CLR(0); |
| 3479 | } |
| 3480 | |
| 3481 | if (rc < 0) DEBUG(D_tls) |
| 3482 | { |
| 3483 | ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring)); |
| 3484 | debug_printf("SSL_shutdown: %s\n", ssl_errstring); |
| 3485 | } |
| 3486 | } |
| 3487 | |
| 3488 | if (!o_ctx) /* server side */ |
| 3489 | { |
| 3490 | #ifndef DISABLE_OCSP |
| 3491 | sk_X509_pop_free(server_static_cbinfo->verify_stack, X509_free); |
| 3492 | server_static_cbinfo->verify_stack = NULL; |
| 3493 | #endif |
| 3494 | |
| 3495 | receive_getc = smtp_getc; |
| 3496 | receive_getbuf = smtp_getbuf; |
| 3497 | receive_get_cache = smtp_get_cache; |
| 3498 | receive_ungetc = smtp_ungetc; |
| 3499 | receive_feof = smtp_feof; |
| 3500 | receive_ferror = smtp_ferror; |
| 3501 | receive_smtp_buffered = smtp_buffered; |
| 3502 | tls_in.active.tls_ctx = NULL; |
| 3503 | tls_in.sni = NULL; |
| 3504 | /* Leave bits, peercert, cipher, peerdn, certificate_verified set, for logging */ |
| 3505 | } |
| 3506 | |
| 3507 | SSL_CTX_free(*ctxp); |
| 3508 | SSL_free(*sslp); |
| 3509 | *ctxp = NULL; |
| 3510 | *sslp = NULL; |
| 3511 | *fdp = -1; |
| 3512 | } |
| 3513 | |
| 3514 | |
| 3515 | |
| 3516 | |
| 3517 | /************************************************* |
| 3518 | * Let tls_require_ciphers be checked at startup * |
| 3519 | *************************************************/ |
| 3520 | |
| 3521 | /* The tls_require_ciphers option, if set, must be something which the |
| 3522 | library can parse. |
| 3523 | |
| 3524 | Returns: NULL on success, or error message |
| 3525 | */ |
| 3526 | |
| 3527 | uschar * |
| 3528 | tls_validate_require_cipher(void) |
| 3529 | { |
| 3530 | SSL_CTX *ctx; |
| 3531 | uschar *s, *expciphers, *err; |
| 3532 | |
| 3533 | /* this duplicates from tls_init(), we need a better "init just global |
| 3534 | state, for no specific purpose" singleton function of our own */ |
| 3535 | |
| 3536 | #ifdef EXIM_NEED_OPENSSL_INIT |
| 3537 | SSL_load_error_strings(); |
| 3538 | OpenSSL_add_ssl_algorithms(); |
| 3539 | #endif |
| 3540 | #if (OPENSSL_VERSION_NUMBER >= 0x0090800fL) && !defined(OPENSSL_NO_SHA256) |
| 3541 | /* SHA256 is becoming ever more popular. This makes sure it gets added to the |
| 3542 | list of available digests. */ |
| 3543 | EVP_add_digest(EVP_sha256()); |
| 3544 | #endif |
| 3545 | |
| 3546 | if (!(tls_require_ciphers && *tls_require_ciphers)) |
| 3547 | return NULL; |
| 3548 | |
| 3549 | if (!expand_check(tls_require_ciphers, US"tls_require_ciphers", &expciphers, |
| 3550 | &err)) |
| 3551 | return US"failed to expand tls_require_ciphers"; |
| 3552 | |
| 3553 | if (!(expciphers && *expciphers)) |
| 3554 | return NULL; |
| 3555 | |
| 3556 | /* normalisation ripped from above */ |
| 3557 | s = expciphers; |
| 3558 | while (*s != 0) { if (*s == '_') *s = '-'; s++; } |
| 3559 | |
| 3560 | err = NULL; |
| 3561 | |
| 3562 | #ifdef EXIM_HAVE_OPENSSL_TLS_METHOD |
| 3563 | if (!(ctx = SSL_CTX_new(TLS_server_method()))) |
| 3564 | #else |
| 3565 | if (!(ctx = SSL_CTX_new(SSLv23_server_method()))) |
| 3566 | #endif |
| 3567 | { |
| 3568 | ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring)); |
| 3569 | return string_sprintf("SSL_CTX_new() failed: %s", ssl_errstring); |
| 3570 | } |
| 3571 | |
| 3572 | DEBUG(D_tls) |
| 3573 | debug_printf("tls_require_ciphers expands to \"%s\"\n", expciphers); |
| 3574 | |
| 3575 | if (!SSL_CTX_set_cipher_list(ctx, CS expciphers)) |
| 3576 | { |
| 3577 | ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring)); |
| 3578 | err = string_sprintf("SSL_CTX_set_cipher_list(%s) failed: %s", |
| 3579 | expciphers, ssl_errstring); |
| 3580 | } |
| 3581 | |
| 3582 | SSL_CTX_free(ctx); |
| 3583 | |
| 3584 | return err; |
| 3585 | } |
| 3586 | |
| 3587 | |
| 3588 | |
| 3589 | |
| 3590 | /************************************************* |
| 3591 | * Report the library versions. * |
| 3592 | *************************************************/ |
| 3593 | |
| 3594 | /* There have historically been some issues with binary compatibility in |
| 3595 | OpenSSL libraries; if Exim (like many other applications) is built against |
| 3596 | one version of OpenSSL but the run-time linker picks up another version, |
| 3597 | it can result in serious failures, including crashing with a SIGSEGV. So |
| 3598 | report the version found by the compiler and the run-time version. |
| 3599 | |
| 3600 | Note: some OS vendors backport security fixes without changing the version |
| 3601 | number/string, and the version date remains unchanged. The _build_ date |
| 3602 | will change, so we can more usefully assist with version diagnosis by also |
| 3603 | reporting the build date. |
| 3604 | |
| 3605 | Arguments: a FILE* to print the results to |
| 3606 | Returns: nothing |
| 3607 | */ |
| 3608 | |
| 3609 | void |
| 3610 | tls_version_report(FILE *f) |
| 3611 | { |
| 3612 | fprintf(f, "Library version: OpenSSL: Compile: %s\n" |
| 3613 | " Runtime: %s\n" |
| 3614 | " : %s\n", |
| 3615 | OPENSSL_VERSION_TEXT, |
| 3616 | SSLeay_version(SSLEAY_VERSION), |
| 3617 | SSLeay_version(SSLEAY_BUILT_ON)); |
| 3618 | /* third line is 38 characters for the %s and the line is 73 chars long; |
| 3619 | the OpenSSL output includes a "built on: " prefix already. */ |
| 3620 | } |
| 3621 | |
| 3622 | |
| 3623 | |
| 3624 | |
| 3625 | /************************************************* |
| 3626 | * Random number generation * |
| 3627 | *************************************************/ |
| 3628 | |
| 3629 | /* Pseudo-random number generation. The result is not expected to be |
| 3630 | cryptographically strong but not so weak that someone will shoot themselves |
| 3631 | in the foot using it as a nonce in input in some email header scheme or |
| 3632 | whatever weirdness they'll twist this into. The result should handle fork() |
| 3633 | and avoid repeating sequences. OpenSSL handles that for us. |
| 3634 | |
| 3635 | Arguments: |
| 3636 | max range maximum |
| 3637 | Returns a random number in range [0, max-1] |
| 3638 | */ |
| 3639 | |
| 3640 | int |
| 3641 | vaguely_random_number(int max) |
| 3642 | { |
| 3643 | unsigned int r; |
| 3644 | int i, needed_len; |
| 3645 | static pid_t pidlast = 0; |
| 3646 | pid_t pidnow; |
| 3647 | uschar smallbuf[sizeof(r)]; |
| 3648 | |
| 3649 | if (max <= 1) |
| 3650 | return 0; |
| 3651 | |
| 3652 | pidnow = getpid(); |
| 3653 | if (pidnow != pidlast) |
| 3654 | { |
| 3655 | /* Although OpenSSL documents that "OpenSSL makes sure that the PRNG state |
| 3656 | is unique for each thread", this doesn't apparently apply across processes, |
| 3657 | so our own warning from vaguely_random_number_fallback() applies here too. |
| 3658 | Fix per PostgreSQL. */ |
| 3659 | if (pidlast != 0) |
| 3660 | RAND_cleanup(); |
| 3661 | pidlast = pidnow; |
| 3662 | } |
| 3663 | |
| 3664 | /* OpenSSL auto-seeds from /dev/random, etc, but this a double-check. */ |
| 3665 | if (!RAND_status()) |
| 3666 | { |
| 3667 | randstuff r; |
| 3668 | gettimeofday(&r.tv, NULL); |
| 3669 | r.p = getpid(); |
| 3670 | |
| 3671 | RAND_seed(US (&r), sizeof(r)); |
| 3672 | } |
| 3673 | /* We're after pseudo-random, not random; if we still don't have enough data |
| 3674 | in the internal PRNG then our options are limited. We could sleep and hope |
| 3675 | for entropy to come along (prayer technique) but if the system is so depleted |
| 3676 | in the first place then something is likely to just keep taking it. Instead, |
| 3677 | we'll just take whatever little bit of pseudo-random we can still manage to |
| 3678 | get. */ |
| 3679 | |
| 3680 | needed_len = sizeof(r); |
| 3681 | /* Don't take 8 times more entropy than needed if int is 8 octets and we were |
| 3682 | asked for a number less than 10. */ |
| 3683 | for (r = max, i = 0; r; ++i) |
| 3684 | r >>= 1; |
| 3685 | i = (i + 7) / 8; |
| 3686 | if (i < needed_len) |
| 3687 | needed_len = i; |
| 3688 | |
| 3689 | #ifdef EXIM_HAVE_RAND_PSEUDO |
| 3690 | /* We do not care if crypto-strong */ |
| 3691 | i = RAND_pseudo_bytes(smallbuf, needed_len); |
| 3692 | #else |
| 3693 | i = RAND_bytes(smallbuf, needed_len); |
| 3694 | #endif |
| 3695 | |
| 3696 | if (i < 0) |
| 3697 | { |
| 3698 | DEBUG(D_all) |
| 3699 | debug_printf("OpenSSL RAND_pseudo_bytes() not supported by RAND method, using fallback.\n"); |
| 3700 | return vaguely_random_number_fallback(max); |
| 3701 | } |
| 3702 | |
| 3703 | r = 0; |
| 3704 | for (uschar * p = smallbuf; needed_len; --needed_len, ++p) |
| 3705 | r = 256 * r + *p; |
| 3706 | |
| 3707 | /* We don't particularly care about weighted results; if someone wants |
| 3708 | smooth distribution and cares enough then they should submit a patch then. */ |
| 3709 | return r % max; |
| 3710 | } |
| 3711 | |
| 3712 | |
| 3713 | |
| 3714 | |
| 3715 | /************************************************* |
| 3716 | * OpenSSL option parse * |
| 3717 | *************************************************/ |
| 3718 | |
| 3719 | /* Parse one option for tls_openssl_options_parse below |
| 3720 | |
| 3721 | Arguments: |
| 3722 | name one option name |
| 3723 | value place to store a value for it |
| 3724 | Returns success or failure in parsing |
| 3725 | */ |
| 3726 | |
| 3727 | |
| 3728 | |
| 3729 | static BOOL |
| 3730 | tls_openssl_one_option_parse(uschar *name, long *value) |
| 3731 | { |
| 3732 | int first = 0; |
| 3733 | int last = exim_openssl_options_size; |
| 3734 | while (last > first) |
| 3735 | { |
| 3736 | int middle = (first + last)/2; |
| 3737 | int c = Ustrcmp(name, exim_openssl_options[middle].name); |
| 3738 | if (c == 0) |
| 3739 | { |
| 3740 | *value = exim_openssl_options[middle].value; |
| 3741 | return TRUE; |
| 3742 | } |
| 3743 | else if (c > 0) |
| 3744 | first = middle + 1; |
| 3745 | else |
| 3746 | last = middle; |
| 3747 | } |
| 3748 | return FALSE; |
| 3749 | } |
| 3750 | |
| 3751 | |
| 3752 | |
| 3753 | |
| 3754 | /************************************************* |
| 3755 | * OpenSSL option parsing logic * |
| 3756 | *************************************************/ |
| 3757 | |
| 3758 | /* OpenSSL has a number of compatibility options which an administrator might |
| 3759 | reasonably wish to set. Interpret a list similarly to decode_bits(), so that |
| 3760 | we look like log_selector. |
| 3761 | |
| 3762 | Arguments: |
| 3763 | option_spec the administrator-supplied string of options |
| 3764 | results ptr to long storage for the options bitmap |
| 3765 | Returns success or failure |
| 3766 | */ |
| 3767 | |
| 3768 | BOOL |
| 3769 | tls_openssl_options_parse(uschar *option_spec, long *results) |
| 3770 | { |
| 3771 | long result, item; |
| 3772 | uschar *end; |
| 3773 | uschar keep_c; |
| 3774 | BOOL adding, item_parsed; |
| 3775 | |
| 3776 | /* Server: send no (<= TLS1.2) session tickets */ |
| 3777 | result = SSL_OP_NO_TICKET; |
| 3778 | |
| 3779 | /* Prior to 4.80 we or'd in SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS; removed |
| 3780 | * from default because it increases BEAST susceptibility. */ |
| 3781 | #ifdef SSL_OP_NO_SSLv2 |
| 3782 | result |= SSL_OP_NO_SSLv2; |
| 3783 | #endif |
| 3784 | #ifdef SSL_OP_NO_SSLv3 |
| 3785 | result |= SSL_OP_NO_SSLv3; |
| 3786 | #endif |
| 3787 | #ifdef SSL_OP_SINGLE_DH_USE |
| 3788 | result |= SSL_OP_SINGLE_DH_USE; |
| 3789 | #endif |
| 3790 | |
| 3791 | if (!option_spec) |
| 3792 | { |
| 3793 | *results = result; |
| 3794 | return TRUE; |
| 3795 | } |
| 3796 | |
| 3797 | for (uschar * s = option_spec; *s; /**/) |
| 3798 | { |
| 3799 | while (isspace(*s)) ++s; |
| 3800 | if (*s == '\0') |
| 3801 | break; |
| 3802 | if (*s != '+' && *s != '-') |
| 3803 | { |
| 3804 | DEBUG(D_tls) debug_printf("malformed openssl option setting: " |
| 3805 | "+ or - expected but found \"%s\"\n", s); |
| 3806 | return FALSE; |
| 3807 | } |
| 3808 | adding = *s++ == '+'; |
| 3809 | for (end = s; (*end != '\0') && !isspace(*end); ++end) /**/ ; |
| 3810 | keep_c = *end; |
| 3811 | *end = '\0'; |
| 3812 | item_parsed = tls_openssl_one_option_parse(s, &item); |
| 3813 | *end = keep_c; |
| 3814 | if (!item_parsed) |
| 3815 | { |
| 3816 | DEBUG(D_tls) debug_printf("openssl option setting unrecognised: \"%s\"\n", s); |
| 3817 | return FALSE; |
| 3818 | } |
| 3819 | DEBUG(D_tls) debug_printf("openssl option, %s %8lx: %lx (%s)\n", |
| 3820 | adding ? "adding to " : "removing from", result, item, s); |
| 3821 | if (adding) |
| 3822 | result |= item; |
| 3823 | else |
| 3824 | result &= ~item; |
| 3825 | s = end; |
| 3826 | } |
| 3827 | |
| 3828 | *results = result; |
| 3829 | return TRUE; |
| 3830 | } |
| 3831 | |
| 3832 | #endif /*!MACRO_PREDEF*/ |
| 3833 | /* vi: aw ai sw=2 |
| 3834 | */ |
| 3835 | /* End of tls-openssl.c */ |