| 1 | /************************************************* |
| 2 | * Exim - an Internet mail transport agent * |
| 3 | *************************************************/ |
| 4 | |
| 5 | /* Copyright (c) University of Cambridge 1995 - 2018 */ |
| 6 | /* See the file NOTICE for conditions of use and distribution. */ |
| 7 | |
| 8 | /* Copyright (c) Phil Pennock 2012 */ |
| 9 | |
| 10 | /* This file provides TLS/SSL support for Exim using the GnuTLS library, |
| 11 | one of the available supported implementations. This file is #included into |
| 12 | tls.c when USE_GNUTLS has been set. |
| 13 | |
| 14 | The code herein is a revamp of GnuTLS integration using the current APIs; the |
| 15 | original tls-gnu.c was based on a patch which was contributed by Nikos |
| 16 | Mavrogiannopoulos. The revamp is partially a rewrite, partially cut&paste as |
| 17 | appropriate. |
| 18 | |
| 19 | APIs current as of GnuTLS 2.12.18; note that the GnuTLS manual is for GnuTLS 3, |
| 20 | which is not widely deployed by OS vendors. Will note issues below, which may |
| 21 | assist in updating the code in the future. Another sources of hints is |
| 22 | mod_gnutls for Apache (SNI callback registration and handling). |
| 23 | |
| 24 | Keeping client and server variables more split than before and is currently |
| 25 | the norm, in anticipation of TLS in ACL callouts. |
| 26 | |
| 27 | I wanted to switch to gnutls_certificate_set_verify_function() so that |
| 28 | certificate rejection could happen during handshake where it belongs, rather |
| 29 | than being dropped afterwards, but that was introduced in 2.10.0 and Debian |
| 30 | (6.0.5) is still on 2.8.6. So for now we have to stick with sub-par behaviour. |
| 31 | |
| 32 | (I wasn't looking for libraries quite that old, when updating to get rid of |
| 33 | compiler warnings of deprecated APIs. If it turns out that a lot of the rest |
| 34 | require current GnuTLS, then we'll drop support for the ancient libraries). |
| 35 | */ |
| 36 | |
| 37 | #include <gnutls/gnutls.h> |
| 38 | /* needed for cert checks in verification and DN extraction: */ |
| 39 | #include <gnutls/x509.h> |
| 40 | /* man-page is incorrect, gnutls_rnd() is not in gnutls.h: */ |
| 41 | #include <gnutls/crypto.h> |
| 42 | |
| 43 | /* needed to disable PKCS11 autoload unless requested */ |
| 44 | #if GNUTLS_VERSION_NUMBER >= 0x020c00 |
| 45 | # include <gnutls/pkcs11.h> |
| 46 | # define SUPPORT_PARAM_TO_PK_BITS |
| 47 | #endif |
| 48 | #if GNUTLS_VERSION_NUMBER < 0x030103 && !defined(DISABLE_OCSP) |
| 49 | # warning "GnuTLS library version too old; define DISABLE_OCSP in Makefile" |
| 50 | # define DISABLE_OCSP |
| 51 | #endif |
| 52 | #if GNUTLS_VERSION_NUMBER < 0x020a00 && !defined(DISABLE_EVENT) |
| 53 | # warning "GnuTLS library version too old; tls:cert event unsupported" |
| 54 | # define DISABLE_EVENT |
| 55 | #endif |
| 56 | #if GNUTLS_VERSION_NUMBER >= 0x030000 |
| 57 | # define SUPPORT_SELFSIGN /* Uncertain what version is first usable but 2.12.23 is not */ |
| 58 | #endif |
| 59 | #if GNUTLS_VERSION_NUMBER >= 0x030306 |
| 60 | # define SUPPORT_CA_DIR |
| 61 | #else |
| 62 | # undef SUPPORT_CA_DIR |
| 63 | #endif |
| 64 | #if GNUTLS_VERSION_NUMBER >= 0x030014 |
| 65 | # define SUPPORT_SYSDEFAULT_CABUNDLE |
| 66 | #endif |
| 67 | #if GNUTLS_VERSION_NUMBER >= 0x030104 |
| 68 | # define GNUTLS_CERT_VFY_STATUS_PRINT |
| 69 | #endif |
| 70 | #if GNUTLS_VERSION_NUMBER >= 0x030109 |
| 71 | # define SUPPORT_CORK |
| 72 | #endif |
| 73 | #if GNUTLS_VERSION_NUMBER >= 0x03010a |
| 74 | # define SUPPORT_GNUTLS_SESS_DESC |
| 75 | #endif |
| 76 | #if GNUTLS_VERSION_NUMBER >= 0x030300 |
| 77 | # define GNUTLS_AUTO_GLOBAL_INIT |
| 78 | # define GNUTLS_AUTO_PKCS11_MANUAL |
| 79 | #endif |
| 80 | #if (GNUTLS_VERSION_NUMBER >= 0x030404) \ |
| 81 | || (GNUTLS_VERSION_NUMBER >= 0x030311) && (GNUTLS_VERSION_NUMBER & 0xffff00 == 0x030300) |
| 82 | # ifndef DISABLE_OCSP |
| 83 | # define EXIM_HAVE_OCSP |
| 84 | # endif |
| 85 | #endif |
| 86 | #if GNUTLS_VERSION_NUMBER >= 0x030500 |
| 87 | # define SUPPORT_GNUTLS_KEYLOG |
| 88 | #endif |
| 89 | #if GNUTLS_VERSION_NUMBER >= 0x030506 && !defined(DISABLE_OCSP) |
| 90 | # define SUPPORT_SRV_OCSP_STACK |
| 91 | #endif |
| 92 | #if GNUTLS_VERSION_NUMBER >= 0x030600 |
| 93 | # define GNUTLS_AUTO_DHPARAMS |
| 94 | #endif |
| 95 | #if GNUTLS_VERSION_NUMBER >= 0x030603 |
| 96 | # define EXIM_HAVE_TLS1_3 |
| 97 | # define SUPPORT_GNUTLS_EXT_RAW_PARSE |
| 98 | # define GNUTLS_OCSP_STATUS_REQUEST_GET2 |
| 99 | #endif |
| 100 | |
| 101 | #ifdef SUPPORT_DANE |
| 102 | # if GNUTLS_VERSION_NUMBER >= 0x030000 |
| 103 | # define DANESSL_USAGE_DANE_TA 2 |
| 104 | # define DANESSL_USAGE_DANE_EE 3 |
| 105 | # else |
| 106 | # error GnuTLS version too early for DANE |
| 107 | # endif |
| 108 | # if GNUTLS_VERSION_NUMBER < 0x999999 |
| 109 | # define GNUTLS_BROKEN_DANE_VALIDATION |
| 110 | # endif |
| 111 | #endif |
| 112 | |
| 113 | #ifdef EXPERIMENTAL_TLS_RESUME |
| 114 | # if GNUTLS_VERSION_NUMBER < 0x030603 |
| 115 | # error GNUTLS version too early for session-resumption |
| 116 | # endif |
| 117 | #endif |
| 118 | |
| 119 | #ifndef DISABLE_OCSP |
| 120 | # include <gnutls/ocsp.h> |
| 121 | #endif |
| 122 | #ifdef SUPPORT_DANE |
| 123 | # include <gnutls/dane.h> |
| 124 | #endif |
| 125 | |
| 126 | #include "tls-cipher-stdname.c" |
| 127 | |
| 128 | |
| 129 | #ifdef MACRO_PREDEF |
| 130 | void |
| 131 | options_tls(void) |
| 132 | { |
| 133 | # ifdef EXPERIMENTAL_TLS_RESUME |
| 134 | builtin_macro_create_var(US"_RESUME_DECODE", RESUME_DECODE_STRING ); |
| 135 | # endif |
| 136 | # ifdef EXIM_HAVE_TLS1_3 |
| 137 | builtin_macro_create(US"_HAVE_TLS1_3"); |
| 138 | # endif |
| 139 | # ifdef EXIM_HAVE_OCSP |
| 140 | builtin_macro_create(US"_HAVE_TLS_OCSP"); |
| 141 | # endif |
| 142 | # ifdef SUPPORT_SRV_OCSP_STACK |
| 143 | builtin_macro_create(US"_HAVE_TLS_OCSP_LIST"); |
| 144 | # endif |
| 145 | } |
| 146 | #else |
| 147 | |
| 148 | |
| 149 | /* GnuTLS 2 vs 3 |
| 150 | |
| 151 | GnuTLS 3 only: |
| 152 | gnutls_global_set_audit_log_function() |
| 153 | |
| 154 | Changes: |
| 155 | gnutls_certificate_verify_peers2(): is new, drop the 2 for old version |
| 156 | */ |
| 157 | |
| 158 | /* Local static variables for GnuTLS */ |
| 159 | |
| 160 | /* Values for verify_requirement */ |
| 161 | |
| 162 | enum peer_verify_requirement |
| 163 | { VERIFY_NONE, VERIFY_OPTIONAL, VERIFY_REQUIRED, VERIFY_DANE }; |
| 164 | |
| 165 | /* This holds most state for server or client; with this, we can set up an |
| 166 | outbound TLS-enabled connection in an ACL callout, while not stomping all |
| 167 | over the TLS variables available for expansion. |
| 168 | |
| 169 | Some of these correspond to variables in globals.c; those variables will |
| 170 | be set to point to content in one of these instances, as appropriate for |
| 171 | the stage of the process lifetime. |
| 172 | |
| 173 | Not handled here: global tlsp->tls_channelbinding. |
| 174 | */ |
| 175 | |
| 176 | typedef struct exim_gnutls_state { |
| 177 | gnutls_session_t session; |
| 178 | gnutls_certificate_credentials_t x509_cred; |
| 179 | gnutls_priority_t priority_cache; |
| 180 | enum peer_verify_requirement verify_requirement; |
| 181 | int fd_in; |
| 182 | int fd_out; |
| 183 | |
| 184 | BOOL peer_cert_verified:1; |
| 185 | BOOL peer_dane_verified:1; |
| 186 | BOOL trigger_sni_changes:1; |
| 187 | BOOL have_set_peerdn:1; |
| 188 | BOOL xfer_eof:1; /*XXX never gets set! */ |
| 189 | BOOL xfer_error:1; |
| 190 | #ifdef SUPPORT_CORK |
| 191 | BOOL corked:1; |
| 192 | #endif |
| 193 | |
| 194 | const struct host_item *host; /* NULL if server */ |
| 195 | gnutls_x509_crt_t peercert; |
| 196 | uschar *peerdn; |
| 197 | uschar *ciphersuite; |
| 198 | uschar *received_sni; |
| 199 | |
| 200 | const uschar *tls_certificate; |
| 201 | const uschar *tls_privatekey; |
| 202 | const uschar *tls_sni; /* client send only, not received */ |
| 203 | const uschar *tls_verify_certificates; |
| 204 | const uschar *tls_crl; |
| 205 | const uschar *tls_require_ciphers; |
| 206 | |
| 207 | uschar *exp_tls_certificate; |
| 208 | uschar *exp_tls_privatekey; |
| 209 | uschar *exp_tls_verify_certificates; |
| 210 | uschar *exp_tls_crl; |
| 211 | uschar *exp_tls_require_ciphers; |
| 212 | const uschar *exp_tls_verify_cert_hostnames; |
| 213 | #ifndef DISABLE_EVENT |
| 214 | uschar *event_action; |
| 215 | #endif |
| 216 | #ifdef SUPPORT_DANE |
| 217 | char * const * dane_data; |
| 218 | const int * dane_data_len; |
| 219 | #endif |
| 220 | |
| 221 | tls_support *tlsp; /* set in tls_init() */ |
| 222 | |
| 223 | uschar *xfer_buffer; |
| 224 | int xfer_buffer_lwm; |
| 225 | int xfer_buffer_hwm; |
| 226 | } exim_gnutls_state_st; |
| 227 | |
| 228 | static const exim_gnutls_state_st exim_gnutls_state_init = { |
| 229 | /* all elements not explicitly intialised here get 0/NULL/FALSE */ |
| 230 | .fd_in = -1, |
| 231 | .fd_out = -1, |
| 232 | }; |
| 233 | |
| 234 | /* Not only do we have our own APIs which don't pass around state, assuming |
| 235 | it's held in globals, GnuTLS doesn't appear to let us register callback data |
| 236 | for callbacks, or as part of the session, so we have to keep a "this is the |
| 237 | context we're currently dealing with" pointer and rely upon being |
| 238 | single-threaded to keep from processing data on an inbound TLS connection while |
| 239 | talking to another TLS connection for an outbound check. This does mean that |
| 240 | there's no way for heart-beats to be responded to, for the duration of the |
| 241 | second connection. |
| 242 | XXX But see gnutls_session_get_ptr() |
| 243 | */ |
| 244 | |
| 245 | static exim_gnutls_state_st state_server; |
| 246 | |
| 247 | #ifndef GNUTLS_AUTO_DHPARAMS |
| 248 | /* dh_params are initialised once within the lifetime of a process using TLS; |
| 249 | if we used TLS in a long-lived daemon, we'd have to reconsider this. But we |
| 250 | don't want to repeat this. */ |
| 251 | |
| 252 | static gnutls_dh_params_t dh_server_params = NULL; |
| 253 | #endif |
| 254 | |
| 255 | static int ssl_session_timeout = 7200; /* Two hours */ |
| 256 | |
| 257 | static const uschar * const exim_default_gnutls_priority = US"NORMAL"; |
| 258 | |
| 259 | /* Guard library core initialisation */ |
| 260 | |
| 261 | static BOOL exim_gnutls_base_init_done = FALSE; |
| 262 | |
| 263 | #ifndef DISABLE_OCSP |
| 264 | static BOOL gnutls_buggy_ocsp = FALSE; |
| 265 | static BOOL exim_testharness_disable_ocsp_validity_check = FALSE; |
| 266 | #endif |
| 267 | |
| 268 | #ifdef EXPERIMENTAL_TLS_RESUME |
| 269 | static gnutls_datum_t server_sessticket_key; |
| 270 | #endif |
| 271 | |
| 272 | /* ------------------------------------------------------------------------ */ |
| 273 | /* macros */ |
| 274 | |
| 275 | #define MAX_HOST_LEN 255 |
| 276 | |
| 277 | /* Set this to control gnutls_global_set_log_level(); values 0 to 9 will setup |
| 278 | the library logging; a value less than 0 disables the calls to set up logging |
| 279 | callbacks. GNuTLS also looks for an environment variable - except not for |
| 280 | setuid binaries, making it useless - "GNUTLS_DEBUG_LEVEL". |
| 281 | Allegedly the testscript line "GNUTLS_DEBUG_LEVEL=9 sudo exim ..." would work, |
| 282 | but the env var must be added to /etc/sudoers too. */ |
| 283 | #ifndef EXIM_GNUTLS_LIBRARY_LOG_LEVEL |
| 284 | # define EXIM_GNUTLS_LIBRARY_LOG_LEVEL -1 |
| 285 | #endif |
| 286 | |
| 287 | #ifndef EXIM_CLIENT_DH_MIN_BITS |
| 288 | # define EXIM_CLIENT_DH_MIN_BITS 1024 |
| 289 | #endif |
| 290 | |
| 291 | /* With GnuTLS 2.12.x+ we have gnutls_sec_param_to_pk_bits() with which we |
| 292 | can ask for a bit-strength. Without that, we stick to the constant we had |
| 293 | before, for now. */ |
| 294 | #ifndef EXIM_SERVER_DH_BITS_PRE2_12 |
| 295 | # define EXIM_SERVER_DH_BITS_PRE2_12 1024 |
| 296 | #endif |
| 297 | |
| 298 | #define expand_check_tlsvar(Varname, errstr) \ |
| 299 | expand_check(state->Varname, US #Varname, &state->exp_##Varname, errstr) |
| 300 | |
| 301 | #if GNUTLS_VERSION_NUMBER >= 0x020c00 |
| 302 | # define HAVE_GNUTLS_SESSION_CHANNEL_BINDING |
| 303 | # define HAVE_GNUTLS_SEC_PARAM_CONSTANTS |
| 304 | # define HAVE_GNUTLS_RND |
| 305 | /* The security fix we provide with the gnutls_allow_auto_pkcs11 option |
| 306 | * (4.82 PP/09) introduces a compatibility regression. The symbol simply |
| 307 | * isn't available sometimes, so this needs to become a conditional |
| 308 | * compilation; the sanest way to deal with this being a problem on |
| 309 | * older OSes is to block it in the Local/Makefile with this compiler |
| 310 | * definition */ |
| 311 | # ifndef AVOID_GNUTLS_PKCS11 |
| 312 | # define HAVE_GNUTLS_PKCS11 |
| 313 | # endif /* AVOID_GNUTLS_PKCS11 */ |
| 314 | #endif |
| 315 | |
| 316 | |
| 317 | |
| 318 | |
| 319 | /* ------------------------------------------------------------------------ */ |
| 320 | /* Callback declarations */ |
| 321 | |
| 322 | #if EXIM_GNUTLS_LIBRARY_LOG_LEVEL >= 0 |
| 323 | static void exim_gnutls_logger_cb(int level, const char *message); |
| 324 | #endif |
| 325 | |
| 326 | static int exim_sni_handling_cb(gnutls_session_t session); |
| 327 | |
| 328 | #ifdef EXPERIMENTAL_TLS_RESUME |
| 329 | static int |
| 330 | tls_server_ticket_cb(gnutls_session_t sess, u_int htype, unsigned when, |
| 331 | unsigned incoming, const gnutls_datum_t * msg); |
| 332 | #endif |
| 333 | |
| 334 | |
| 335 | /* Daemon one-time initialisation */ |
| 336 | void |
| 337 | tls_daemon_init(void) |
| 338 | { |
| 339 | #ifdef EXPERIMENTAL_TLS_RESUME |
| 340 | /* We are dependent on the GnuTLS implementation of the Session Ticket |
| 341 | encryption; both the strength and the key rotation period. We hope that |
| 342 | the strength at least matches that of the ciphersuite (but GnuTLS does not |
| 343 | document this). */ |
| 344 | |
| 345 | static BOOL once = FALSE; |
| 346 | if (once) return; |
| 347 | once = TRUE; |
| 348 | gnutls_session_ticket_key_generate(&server_sessticket_key); /* >= 2.10.0 */ |
| 349 | if (f.running_in_test_harness) ssl_session_timeout = 6; |
| 350 | #endif |
| 351 | } |
| 352 | |
| 353 | /* ------------------------------------------------------------------------ */ |
| 354 | /* Static functions */ |
| 355 | |
| 356 | /************************************************* |
| 357 | * Handle TLS error * |
| 358 | *************************************************/ |
| 359 | |
| 360 | /* Called from lots of places when errors occur before actually starting to do |
| 361 | the TLS handshake, that is, while the session is still in clear. Always returns |
| 362 | DEFER for a server and FAIL for a client so that most calls can use "return |
| 363 | tls_error(...)" to do this processing and then give an appropriate return. A |
| 364 | single function is used for both server and client, because it is called from |
| 365 | some shared functions. |
| 366 | |
| 367 | Argument: |
| 368 | prefix text to include in the logged error |
| 369 | msg additional error string (may be NULL) |
| 370 | usually obtained from gnutls_strerror() |
| 371 | host NULL if setting up a server; |
| 372 | the connected host if setting up a client |
| 373 | errstr pointer to returned error string |
| 374 | |
| 375 | Returns: OK/DEFER/FAIL |
| 376 | */ |
| 377 | |
| 378 | static int |
| 379 | tls_error(const uschar *prefix, const uschar *msg, const host_item *host, |
| 380 | uschar ** errstr) |
| 381 | { |
| 382 | if (errstr) |
| 383 | *errstr = string_sprintf("(%s)%s%s", prefix, msg ? ": " : "", msg ? msg : US""); |
| 384 | return host ? FAIL : DEFER; |
| 385 | } |
| 386 | |
| 387 | |
| 388 | static int |
| 389 | tls_error_gnu(const uschar *prefix, int err, const host_item *host, |
| 390 | uschar ** errstr) |
| 391 | { |
| 392 | return tls_error(prefix, US gnutls_strerror(err), host, errstr); |
| 393 | } |
| 394 | |
| 395 | static int |
| 396 | tls_error_sys(const uschar *prefix, int err, const host_item *host, |
| 397 | uschar ** errstr) |
| 398 | { |
| 399 | return tls_error(prefix, US strerror(err), host, errstr); |
| 400 | } |
| 401 | |
| 402 | |
| 403 | /************************************************* |
| 404 | * Deal with logging errors during I/O * |
| 405 | *************************************************/ |
| 406 | |
| 407 | /* We have to get the identity of the peer from saved data. |
| 408 | |
| 409 | Argument: |
| 410 | state the current GnuTLS exim state container |
| 411 | rc the GnuTLS error code, or 0 if it's a local error |
| 412 | when text identifying read or write |
| 413 | text local error text when rc is 0 |
| 414 | |
| 415 | Returns: nothing |
| 416 | */ |
| 417 | |
| 418 | static void |
| 419 | record_io_error(exim_gnutls_state_st *state, int rc, uschar *when, uschar *text) |
| 420 | { |
| 421 | const uschar * msg; |
| 422 | uschar * errstr; |
| 423 | |
| 424 | if (rc == GNUTLS_E_FATAL_ALERT_RECEIVED) |
| 425 | msg = string_sprintf("A TLS fatal alert has been received: %s", |
| 426 | US gnutls_alert_get_name(gnutls_alert_get(state->session))); |
| 427 | else |
| 428 | msg = US gnutls_strerror(rc); |
| 429 | |
| 430 | (void) tls_error(when, msg, state->host, &errstr); |
| 431 | |
| 432 | if (state->host) |
| 433 | log_write(0, LOG_MAIN, "H=%s [%s] TLS error on connection %s", |
| 434 | state->host->name, state->host->address, errstr); |
| 435 | else |
| 436 | { |
| 437 | uschar * conn_info = smtp_get_connection_info(); |
| 438 | if (Ustrncmp(conn_info, US"SMTP ", 5) == 0) conn_info += 5; |
| 439 | /* I'd like to get separated H= here, but too hard for now */ |
| 440 | log_write(0, LOG_MAIN, "TLS error on %s %s", conn_info, errstr); |
| 441 | } |
| 442 | } |
| 443 | |
| 444 | |
| 445 | |
| 446 | |
| 447 | /************************************************* |
| 448 | * Set various Exim expansion vars * |
| 449 | *************************************************/ |
| 450 | |
| 451 | #define exim_gnutls_cert_err(Label) \ |
| 452 | do \ |
| 453 | { \ |
| 454 | if (rc != GNUTLS_E_SUCCESS) \ |
| 455 | { \ |
| 456 | DEBUG(D_tls) debug_printf("TLS: cert problem: %s: %s\n", \ |
| 457 | (Label), gnutls_strerror(rc)); \ |
| 458 | return rc; \ |
| 459 | } \ |
| 460 | } while (0) |
| 461 | |
| 462 | static int |
| 463 | import_cert(const gnutls_datum_t * cert, gnutls_x509_crt_t * crtp) |
| 464 | { |
| 465 | int rc; |
| 466 | |
| 467 | rc = gnutls_x509_crt_init(crtp); |
| 468 | exim_gnutls_cert_err(US"gnutls_x509_crt_init (crt)"); |
| 469 | |
| 470 | rc = gnutls_x509_crt_import(*crtp, cert, GNUTLS_X509_FMT_DER); |
| 471 | exim_gnutls_cert_err(US"failed to import certificate [gnutls_x509_crt_import(cert)]"); |
| 472 | |
| 473 | return rc; |
| 474 | } |
| 475 | |
| 476 | #undef exim_gnutls_cert_err |
| 477 | |
| 478 | |
| 479 | /* We set various Exim global variables from the state, once a session has |
| 480 | been established. With TLS callouts, may need to change this to stack |
| 481 | variables, or just re-call it with the server state after client callout |
| 482 | has finished. |
| 483 | |
| 484 | Make sure anything set here is unset in tls_getc(). |
| 485 | |
| 486 | Sets: |
| 487 | tls_active fd |
| 488 | tls_bits strength indicator |
| 489 | tls_certificate_verified bool indicator |
| 490 | tls_channelbinding for some SASL mechanisms |
| 491 | tls_ver a string |
| 492 | tls_cipher a string |
| 493 | tls_peercert pointer to library internal |
| 494 | tls_peerdn a string |
| 495 | tls_sni a (UTF-8) string |
| 496 | tls_ourcert pointer to library internal |
| 497 | |
| 498 | Argument: |
| 499 | state the relevant exim_gnutls_state_st * |
| 500 | */ |
| 501 | |
| 502 | static void |
| 503 | extract_exim_vars_from_tls_state(exim_gnutls_state_st * state) |
| 504 | { |
| 505 | #ifdef HAVE_GNUTLS_SESSION_CHANNEL_BINDING |
| 506 | int old_pool; |
| 507 | int rc; |
| 508 | gnutls_datum_t channel; |
| 509 | #endif |
| 510 | tls_support * tlsp = state->tlsp; |
| 511 | |
| 512 | tlsp->active.sock = state->fd_out; |
| 513 | tlsp->active.tls_ctx = state; |
| 514 | |
| 515 | DEBUG(D_tls) debug_printf("cipher: %s\n", state->ciphersuite); |
| 516 | |
| 517 | tlsp->certificate_verified = state->peer_cert_verified; |
| 518 | #ifdef SUPPORT_DANE |
| 519 | tlsp->dane_verified = state->peer_dane_verified; |
| 520 | #endif |
| 521 | |
| 522 | /* note that tls_channelbinding is not saved to the spool file, since it's |
| 523 | only available for use for authenticators while this TLS session is running. */ |
| 524 | |
| 525 | tlsp->channelbinding = NULL; |
| 526 | #ifdef HAVE_GNUTLS_SESSION_CHANNEL_BINDING |
| 527 | channel.data = NULL; |
| 528 | channel.size = 0; |
| 529 | if ((rc = gnutls_session_channel_binding(state->session, GNUTLS_CB_TLS_UNIQUE, &channel))) |
| 530 | { DEBUG(D_tls) debug_printf("Channel binding error: %s\n", gnutls_strerror(rc)); } |
| 531 | else |
| 532 | { |
| 533 | /* Declare the taintedness of the binding info. On server, untainted; on |
| 534 | client, tainted - being the Finish msg from the server. */ |
| 535 | |
| 536 | old_pool = store_pool; |
| 537 | store_pool = POOL_PERM; |
| 538 | tlsp->channelbinding = b64encode_taint(CUS channel.data, (int)channel.size, |
| 539 | !!state->host); |
| 540 | store_pool = old_pool; |
| 541 | DEBUG(D_tls) debug_printf("Have channel bindings cached for possible auth usage\n"); |
| 542 | } |
| 543 | #endif |
| 544 | |
| 545 | /* peercert is set in peer_status() */ |
| 546 | tlsp->peerdn = state->peerdn; |
| 547 | tlsp->sni = state->received_sni; |
| 548 | |
| 549 | /* record our certificate */ |
| 550 | { |
| 551 | const gnutls_datum_t * cert = gnutls_certificate_get_ours(state->session); |
| 552 | gnutls_x509_crt_t crt; |
| 553 | |
| 554 | tlsp->ourcert = cert && import_cert(cert, &crt)==0 ? crt : NULL; |
| 555 | } |
| 556 | } |
| 557 | |
| 558 | |
| 559 | |
| 560 | |
| 561 | #ifndef GNUTLS_AUTO_DHPARAMS |
| 562 | /************************************************* |
| 563 | * Setup up DH parameters * |
| 564 | *************************************************/ |
| 565 | |
| 566 | /* Generating the D-H parameters may take a long time. They only need to |
| 567 | be re-generated every so often, depending on security policy. What we do is to |
| 568 | keep these parameters in a file in the spool directory. If the file does not |
| 569 | exist, we generate them. This means that it is easy to cause a regeneration. |
| 570 | |
| 571 | The new file is written as a temporary file and renamed, so that an incomplete |
| 572 | file is never present. If two processes both compute some new parameters, you |
| 573 | waste a bit of effort, but it doesn't seem worth messing around with locking to |
| 574 | prevent this. |
| 575 | |
| 576 | Returns: OK/DEFER/FAIL |
| 577 | */ |
| 578 | |
| 579 | static int |
| 580 | init_server_dh(uschar ** errstr) |
| 581 | { |
| 582 | int fd, rc; |
| 583 | unsigned int dh_bits; |
| 584 | gnutls_datum_t m = {.data = NULL, .size = 0}; |
| 585 | uschar filename_buf[PATH_MAX]; |
| 586 | uschar *filename = NULL; |
| 587 | size_t sz; |
| 588 | uschar *exp_tls_dhparam; |
| 589 | BOOL use_file_in_spool = FALSE; |
| 590 | host_item *host = NULL; /* dummy for macros */ |
| 591 | |
| 592 | DEBUG(D_tls) debug_printf("Initialising GnuTLS server params.\n"); |
| 593 | |
| 594 | if ((rc = gnutls_dh_params_init(&dh_server_params))) |
| 595 | return tls_error_gnu(US"gnutls_dh_params_init", rc, host, errstr); |
| 596 | |
| 597 | if (!expand_check(tls_dhparam, US"tls_dhparam", &exp_tls_dhparam, errstr)) |
| 598 | return DEFER; |
| 599 | |
| 600 | if (!exp_tls_dhparam) |
| 601 | { |
| 602 | DEBUG(D_tls) debug_printf("Loading default hard-coded DH params\n"); |
| 603 | m.data = US std_dh_prime_default(); |
| 604 | m.size = Ustrlen(m.data); |
| 605 | } |
| 606 | else if (Ustrcmp(exp_tls_dhparam, "historic") == 0) |
| 607 | use_file_in_spool = TRUE; |
| 608 | else if (Ustrcmp(exp_tls_dhparam, "none") == 0) |
| 609 | { |
| 610 | DEBUG(D_tls) debug_printf("Requested no DH parameters.\n"); |
| 611 | return OK; |
| 612 | } |
| 613 | else if (exp_tls_dhparam[0] != '/') |
| 614 | { |
| 615 | if (!(m.data = US std_dh_prime_named(exp_tls_dhparam))) |
| 616 | return tls_error(US"No standard prime named", exp_tls_dhparam, NULL, errstr); |
| 617 | m.size = Ustrlen(m.data); |
| 618 | } |
| 619 | else |
| 620 | filename = exp_tls_dhparam; |
| 621 | |
| 622 | if (m.data) |
| 623 | { |
| 624 | if ((rc = gnutls_dh_params_import_pkcs3(dh_server_params, &m, GNUTLS_X509_FMT_PEM))) |
| 625 | return tls_error_gnu(US"gnutls_dh_params_import_pkcs3", rc, host, errstr); |
| 626 | DEBUG(D_tls) debug_printf("Loaded fixed standard D-H parameters\n"); |
| 627 | return OK; |
| 628 | } |
| 629 | |
| 630 | #ifdef HAVE_GNUTLS_SEC_PARAM_CONSTANTS |
| 631 | /* If you change this constant, also change dh_param_fn_ext so that we can use a |
| 632 | different filename and ensure we have sufficient bits. */ |
| 633 | |
| 634 | if (!(dh_bits = gnutls_sec_param_to_pk_bits(GNUTLS_PK_DH, GNUTLS_SEC_PARAM_NORMAL))) |
| 635 | return tls_error(US"gnutls_sec_param_to_pk_bits() failed", NULL, NULL, errstr); |
| 636 | DEBUG(D_tls) |
| 637 | debug_printf("GnuTLS tells us that for D-H PK, NORMAL is %d bits.\n", |
| 638 | dh_bits); |
| 639 | #else |
| 640 | dh_bits = EXIM_SERVER_DH_BITS_PRE2_12; |
| 641 | DEBUG(D_tls) |
| 642 | debug_printf("GnuTLS lacks gnutls_sec_param_to_pk_bits(), using %d bits.\n", |
| 643 | dh_bits); |
| 644 | #endif |
| 645 | |
| 646 | /* Some clients have hard-coded limits. */ |
| 647 | if (dh_bits > tls_dh_max_bits) |
| 648 | { |
| 649 | DEBUG(D_tls) |
| 650 | debug_printf("tls_dh_max_bits clamping override, using %d bits instead.\n", |
| 651 | tls_dh_max_bits); |
| 652 | dh_bits = tls_dh_max_bits; |
| 653 | } |
| 654 | |
| 655 | if (use_file_in_spool) |
| 656 | { |
| 657 | if (!string_format(filename_buf, sizeof(filename_buf), |
| 658 | "%s/gnutls-params-%d", spool_directory, dh_bits)) |
| 659 | return tls_error(US"overlong filename", NULL, NULL, errstr); |
| 660 | filename = filename_buf; |
| 661 | } |
| 662 | |
| 663 | /* Open the cache file for reading and if successful, read it and set up the |
| 664 | parameters. */ |
| 665 | |
| 666 | if ((fd = Uopen(filename, O_RDONLY, 0)) >= 0) |
| 667 | { |
| 668 | struct stat statbuf; |
| 669 | FILE *fp; |
| 670 | int saved_errno; |
| 671 | |
| 672 | if (fstat(fd, &statbuf) < 0) /* EIO */ |
| 673 | { |
| 674 | saved_errno = errno; |
| 675 | (void)close(fd); |
| 676 | return tls_error_sys(US"TLS cache stat failed", saved_errno, NULL, errstr); |
| 677 | } |
| 678 | if (!S_ISREG(statbuf.st_mode)) |
| 679 | { |
| 680 | (void)close(fd); |
| 681 | return tls_error(US"TLS cache not a file", NULL, NULL, errstr); |
| 682 | } |
| 683 | if (!(fp = fdopen(fd, "rb"))) |
| 684 | { |
| 685 | saved_errno = errno; |
| 686 | (void)close(fd); |
| 687 | return tls_error_sys(US"fdopen(TLS cache stat fd) failed", |
| 688 | saved_errno, NULL, errstr); |
| 689 | } |
| 690 | |
| 691 | m.size = statbuf.st_size; |
| 692 | if (!(m.data = store_malloc(m.size))) |
| 693 | { |
| 694 | fclose(fp); |
| 695 | return tls_error_sys(US"malloc failed", errno, NULL, errstr); |
| 696 | } |
| 697 | if (!(sz = fread(m.data, m.size, 1, fp))) |
| 698 | { |
| 699 | saved_errno = errno; |
| 700 | fclose(fp); |
| 701 | store_free(m.data); |
| 702 | return tls_error_sys(US"fread failed", saved_errno, NULL, errstr); |
| 703 | } |
| 704 | fclose(fp); |
| 705 | |
| 706 | rc = gnutls_dh_params_import_pkcs3(dh_server_params, &m, GNUTLS_X509_FMT_PEM); |
| 707 | store_free(m.data); |
| 708 | if (rc) |
| 709 | return tls_error_gnu(US"gnutls_dh_params_import_pkcs3", rc, host, errstr); |
| 710 | DEBUG(D_tls) debug_printf("read D-H parameters from file \"%s\"\n", filename); |
| 711 | } |
| 712 | |
| 713 | /* If the file does not exist, fall through to compute new data and cache it. |
| 714 | If there was any other opening error, it is serious. */ |
| 715 | |
| 716 | else if (errno == ENOENT) |
| 717 | { |
| 718 | rc = -1; |
| 719 | DEBUG(D_tls) |
| 720 | debug_printf("D-H parameter cache file \"%s\" does not exist\n", filename); |
| 721 | } |
| 722 | else |
| 723 | return tls_error(string_open_failed(errno, "\"%s\" for reading", filename), |
| 724 | NULL, NULL, errstr); |
| 725 | |
| 726 | /* If ret < 0, either the cache file does not exist, or the data it contains |
| 727 | is not useful. One particular case of this is when upgrading from an older |
| 728 | release of Exim in which the data was stored in a different format. We don't |
| 729 | try to be clever and support both formats; we just regenerate new data in this |
| 730 | case. */ |
| 731 | |
| 732 | if (rc < 0) |
| 733 | { |
| 734 | uschar *temp_fn; |
| 735 | unsigned int dh_bits_gen = dh_bits; |
| 736 | |
| 737 | if ((PATH_MAX - Ustrlen(filename)) < 10) |
| 738 | return tls_error(US"Filename too long to generate replacement", |
| 739 | filename, NULL, errstr); |
| 740 | |
| 741 | temp_fn = string_copy(US"%s.XXXXXXX"); |
| 742 | if ((fd = mkstemp(CS temp_fn)) < 0) /* modifies temp_fn */ |
| 743 | return tls_error_sys(US"Unable to open temp file", errno, NULL, errstr); |
| 744 | (void)exim_chown(temp_fn, exim_uid, exim_gid); /* Probably not necessary */ |
| 745 | |
| 746 | /* GnuTLS overshoots! If we ask for 2236, we might get 2237 or more. But |
| 747 | there's no way to ask GnuTLS how many bits there really are. We can ask |
| 748 | how many bits were used in a TLS session, but that's it! The prime itself |
| 749 | is hidden behind too much abstraction. So we ask for less, and proceed on |
| 750 | a wing and a prayer. First attempt, subtracted 3 for 2233 and got 2240. */ |
| 751 | |
| 752 | if (dh_bits >= EXIM_CLIENT_DH_MIN_BITS + 10) |
| 753 | { |
| 754 | dh_bits_gen = dh_bits - 10; |
| 755 | DEBUG(D_tls) |
| 756 | debug_printf("being paranoid about DH generation, make it '%d' bits'\n", |
| 757 | dh_bits_gen); |
| 758 | } |
| 759 | |
| 760 | DEBUG(D_tls) |
| 761 | debug_printf("requesting generation of %d bit Diffie-Hellman prime ...\n", |
| 762 | dh_bits_gen); |
| 763 | if ((rc = gnutls_dh_params_generate2(dh_server_params, dh_bits_gen))) |
| 764 | return tls_error_gnu(US"gnutls_dh_params_generate2", rc, host, errstr); |
| 765 | |
| 766 | /* gnutls_dh_params_export_pkcs3() will tell us the exact size, every time, |
| 767 | and I confirmed that a NULL call to get the size first is how the GnuTLS |
| 768 | sample apps handle this. */ |
| 769 | |
| 770 | sz = 0; |
| 771 | m.data = NULL; |
| 772 | if ( (rc = gnutls_dh_params_export_pkcs3(dh_server_params, |
| 773 | GNUTLS_X509_FMT_PEM, m.data, &sz)) |
| 774 | && rc != GNUTLS_E_SHORT_MEMORY_BUFFER) |
| 775 | return tls_error_gnu(US"gnutls_dh_params_export_pkcs3(NULL) sizing", |
| 776 | rc, host, errstr); |
| 777 | m.size = sz; |
| 778 | if (!(m.data = store_malloc(m.size))) |
| 779 | return tls_error_sys(US"memory allocation failed", errno, NULL, errstr); |
| 780 | |
| 781 | /* this will return a size 1 less than the allocation size above */ |
| 782 | if ((rc = gnutls_dh_params_export_pkcs3(dh_server_params, GNUTLS_X509_FMT_PEM, |
| 783 | m.data, &sz))) |
| 784 | { |
| 785 | store_free(m.data); |
| 786 | return tls_error_gnu(US"gnutls_dh_params_export_pkcs3() real", rc, host, errstr); |
| 787 | } |
| 788 | m.size = sz; /* shrink by 1, probably */ |
| 789 | |
| 790 | if ((sz = write_to_fd_buf(fd, m.data, (size_t) m.size)) != m.size) |
| 791 | { |
| 792 | store_free(m.data); |
| 793 | return tls_error_sys(US"TLS cache write D-H params failed", |
| 794 | errno, NULL, errstr); |
| 795 | } |
| 796 | store_free(m.data); |
| 797 | if ((sz = write_to_fd_buf(fd, US"\n", 1)) != 1) |
| 798 | return tls_error_sys(US"TLS cache write D-H params final newline failed", |
| 799 | errno, NULL, errstr); |
| 800 | |
| 801 | if ((rc = close(fd))) |
| 802 | return tls_error_sys(US"TLS cache write close() failed", errno, NULL, errstr); |
| 803 | |
| 804 | if (Urename(temp_fn, filename) < 0) |
| 805 | return tls_error_sys(string_sprintf("failed to rename \"%s\" as \"%s\"", |
| 806 | temp_fn, filename), errno, NULL, errstr); |
| 807 | |
| 808 | DEBUG(D_tls) debug_printf("wrote D-H parameters to file \"%s\"\n", filename); |
| 809 | } |
| 810 | |
| 811 | DEBUG(D_tls) debug_printf("initialized server D-H parameters\n"); |
| 812 | return OK; |
| 813 | } |
| 814 | #endif |
| 815 | |
| 816 | |
| 817 | |
| 818 | |
| 819 | /* Create and install a selfsigned certificate, for use in server mode */ |
| 820 | |
| 821 | static int |
| 822 | tls_install_selfsign(exim_gnutls_state_st * state, uschar ** errstr) |
| 823 | { |
| 824 | gnutls_x509_crt_t cert = NULL; |
| 825 | time_t now; |
| 826 | gnutls_x509_privkey_t pkey = NULL; |
| 827 | const uschar * where; |
| 828 | int rc; |
| 829 | |
| 830 | #ifndef SUPPORT_SELFSIGN |
| 831 | where = US"library too old"; |
| 832 | rc = GNUTLS_E_NO_CERTIFICATE_FOUND; |
| 833 | if (TRUE) goto err; |
| 834 | #endif |
| 835 | |
| 836 | where = US"initialising pkey"; |
| 837 | if ((rc = gnutls_x509_privkey_init(&pkey))) goto err; |
| 838 | |
| 839 | where = US"initialising cert"; |
| 840 | if ((rc = gnutls_x509_crt_init(&cert))) goto err; |
| 841 | |
| 842 | where = US"generating pkey"; /* Hangs on 2.12.23 */ |
| 843 | if ((rc = gnutls_x509_privkey_generate(pkey, GNUTLS_PK_RSA, |
| 844 | #ifdef SUPPORT_PARAM_TO_PK_BITS |
| 845 | # ifndef GNUTLS_SEC_PARAM_MEDIUM |
| 846 | # define GNUTLS_SEC_PARAM_MEDIUM GNUTLS_SEC_PARAM_HIGH |
| 847 | # endif |
| 848 | gnutls_sec_param_to_pk_bits(GNUTLS_PK_RSA, GNUTLS_SEC_PARAM_MEDIUM), |
| 849 | #else |
| 850 | 2048, |
| 851 | #endif |
| 852 | 0))) |
| 853 | goto err; |
| 854 | |
| 855 | where = US"configuring cert"; |
| 856 | now = 1; |
| 857 | if ( (rc = gnutls_x509_crt_set_version(cert, 3)) |
| 858 | || (rc = gnutls_x509_crt_set_serial(cert, &now, sizeof(now))) |
| 859 | || (rc = gnutls_x509_crt_set_activation_time(cert, now = time(NULL))) |
| 860 | || (rc = gnutls_x509_crt_set_expiration_time(cert, now + 60 * 60)) /* 1 hr */ |
| 861 | || (rc = gnutls_x509_crt_set_key(cert, pkey)) |
| 862 | |
| 863 | || (rc = gnutls_x509_crt_set_dn_by_oid(cert, |
| 864 | GNUTLS_OID_X520_COUNTRY_NAME, 0, "UK", 2)) |
| 865 | || (rc = gnutls_x509_crt_set_dn_by_oid(cert, |
| 866 | GNUTLS_OID_X520_ORGANIZATION_NAME, 0, "Exim Developers", 15)) |
| 867 | || (rc = gnutls_x509_crt_set_dn_by_oid(cert, |
| 868 | GNUTLS_OID_X520_COMMON_NAME, 0, |
| 869 | smtp_active_hostname, Ustrlen(smtp_active_hostname))) |
| 870 | ) |
| 871 | goto err; |
| 872 | |
| 873 | where = US"signing cert"; |
| 874 | if ((rc = gnutls_x509_crt_sign(cert, cert, pkey))) goto err; |
| 875 | |
| 876 | where = US"installing selfsign cert"; |
| 877 | /* Since: 2.4.0 */ |
| 878 | if ((rc = gnutls_certificate_set_x509_key(state->x509_cred, &cert, 1, pkey))) |
| 879 | goto err; |
| 880 | |
| 881 | rc = OK; |
| 882 | |
| 883 | out: |
| 884 | if (cert) gnutls_x509_crt_deinit(cert); |
| 885 | if (pkey) gnutls_x509_privkey_deinit(pkey); |
| 886 | return rc; |
| 887 | |
| 888 | err: |
| 889 | rc = tls_error_gnu(where, rc, NULL, errstr); |
| 890 | goto out; |
| 891 | } |
| 892 | |
| 893 | |
| 894 | |
| 895 | |
| 896 | /* Add certificate and key, from files. |
| 897 | |
| 898 | Return: |
| 899 | Zero or negative: good. Negate value for certificate index if < 0. |
| 900 | Greater than zero: FAIL or DEFER code. |
| 901 | */ |
| 902 | |
| 903 | static int |
| 904 | tls_add_certfile(exim_gnutls_state_st * state, const host_item * host, |
| 905 | uschar * certfile, uschar * keyfile, uschar ** errstr) |
| 906 | { |
| 907 | int rc = gnutls_certificate_set_x509_key_file(state->x509_cred, |
| 908 | CS certfile, CS keyfile, GNUTLS_X509_FMT_PEM); |
| 909 | if (rc < 0) |
| 910 | return tls_error_gnu( |
| 911 | string_sprintf("cert/key setup: cert=%s key=%s", certfile, keyfile), |
| 912 | rc, host, errstr); |
| 913 | return -rc; |
| 914 | } |
| 915 | |
| 916 | |
| 917 | #if !defined(DISABLE_OCSP) && !defined(SUPPORT_GNUTLS_EXT_RAW_PARSE) |
| 918 | /* Load an OCSP proof from file for sending by the server. Called |
| 919 | on getting a status-request handshake message, for earlier versions |
| 920 | of GnuTLS. */ |
| 921 | |
| 922 | static int |
| 923 | server_ocsp_stapling_cb(gnutls_session_t session, void * ptr, |
| 924 | gnutls_datum_t * ocsp_response) |
| 925 | { |
| 926 | int ret; |
| 927 | DEBUG(D_tls) debug_printf("OCSP stapling callback: %s\n", US ptr); |
| 928 | |
| 929 | if ((ret = gnutls_load_file(ptr, ocsp_response)) < 0) |
| 930 | { |
| 931 | DEBUG(D_tls) debug_printf("Failed to load ocsp stapling file %s\n", |
| 932 | CS ptr); |
| 933 | tls_in.ocsp = OCSP_NOT_RESP; |
| 934 | return GNUTLS_E_NO_CERTIFICATE_STATUS; |
| 935 | } |
| 936 | |
| 937 | tls_in.ocsp = OCSP_VFY_NOT_TRIED; |
| 938 | return 0; |
| 939 | } |
| 940 | #endif |
| 941 | |
| 942 | |
| 943 | #ifdef SUPPORT_GNUTLS_EXT_RAW_PARSE |
| 944 | /* Make a note that we saw a status-request */ |
| 945 | static int |
| 946 | tls_server_clienthello_ext(void * ctx, unsigned tls_id, |
| 947 | const unsigned char *data, unsigned size) |
| 948 | { |
| 949 | /* https://www.iana.org/assignments/tls-extensiontype-values/tls-extensiontype-values.xhtml */ |
| 950 | if (tls_id == 5) /* status_request */ |
| 951 | { |
| 952 | DEBUG(D_tls) debug_printf("Seen status_request extension from client\n"); |
| 953 | tls_in.ocsp = OCSP_NOT_RESP; |
| 954 | } |
| 955 | return 0; |
| 956 | } |
| 957 | |
| 958 | /* Callback for client-hello, on server, if we think we might serve stapled-OCSP */ |
| 959 | static int |
| 960 | tls_server_clienthello_cb(gnutls_session_t session, unsigned int htype, |
| 961 | unsigned when, unsigned int incoming, const gnutls_datum_t * msg) |
| 962 | { |
| 963 | /* Call fn for each extension seen. 3.6.3 onwards */ |
| 964 | return gnutls_ext_raw_parse(NULL, tls_server_clienthello_ext, msg, |
| 965 | GNUTLS_EXT_RAW_FLAG_TLS_CLIENT_HELLO); |
| 966 | } |
| 967 | |
| 968 | |
| 969 | /* Make a note that we saw a status-response */ |
| 970 | static int |
| 971 | tls_server_servercerts_ext(void * ctx, unsigned tls_id, |
| 972 | const unsigned char *data, unsigned size) |
| 973 | { |
| 974 | /* debug_printf("%s %u\n", __FUNCTION__, tls_id); */ |
| 975 | /* https://www.iana.org/assignments/tls-extensiontype-values/tls-extensiontype-values.xhtml */ |
| 976 | if (FALSE && tls_id == 5) /* status_request */ |
| 977 | { |
| 978 | DEBUG(D_tls) debug_printf("Seen status_request extension\n"); |
| 979 | tls_in.ocsp = exim_testharness_disable_ocsp_validity_check |
| 980 | ? OCSP_VFY_NOT_TRIED : OCSP_VFIED; /* We know that GnuTLS verifies responses */ |
| 981 | } |
| 982 | return 0; |
| 983 | } |
| 984 | |
| 985 | /* Callback for certificates packet, on server, if we think we might serve stapled-OCSP */ |
| 986 | static int |
| 987 | tls_server_servercerts_cb(gnutls_session_t session, unsigned int htype, |
| 988 | unsigned when, unsigned int incoming, const gnutls_datum_t * msg) |
| 989 | { |
| 990 | /* Call fn for each extension seen. 3.6.3 onwards */ |
| 991 | #ifdef notdef |
| 992 | /*XXX crashes */ |
| 993 | return gnutls_ext_raw_parse(NULL, tls_server_servercerts_ext, msg, 0); |
| 994 | #endif |
| 995 | } |
| 996 | #endif |
| 997 | |
| 998 | /*XXX in tls1.3 the cert-status travel as an extension next to the cert, in the |
| 999 | "Handshake Protocol: Certificate" record. |
| 1000 | So we need to spot the Certificate handshake message, parse it and spot any status_request extension(s) |
| 1001 | |
| 1002 | This is different to tls1.2 - where it is a separate record (wireshake term) / handshake message (gnutls term). |
| 1003 | */ |
| 1004 | |
| 1005 | #if defined(EXPERIMENTAL_TLS_RESUME) || defined(SUPPORT_GNUTLS_EXT_RAW_PARSE) |
| 1006 | /* Callback for certificate-status, on server. We sent stapled OCSP. */ |
| 1007 | static int |
| 1008 | tls_server_certstatus_cb(gnutls_session_t session, unsigned int htype, |
| 1009 | unsigned when, unsigned int incoming, const gnutls_datum_t * msg) |
| 1010 | { |
| 1011 | DEBUG(D_tls) debug_printf("Sending certificate-status\n"); /*XXX we get this for tls1.2 but not for 1.3 */ |
| 1012 | #ifdef SUPPORT_SRV_OCSP_STACK |
| 1013 | tls_in.ocsp = exim_testharness_disable_ocsp_validity_check |
| 1014 | ? OCSP_VFY_NOT_TRIED : OCSP_VFIED; /* We know that GnuTLS verifies responses */ |
| 1015 | #else |
| 1016 | tls_in.ocsp = OCSP_VFY_NOT_TRIED; |
| 1017 | #endif |
| 1018 | return 0; |
| 1019 | } |
| 1020 | |
| 1021 | /* Callback for handshake messages, on server */ |
| 1022 | static int |
| 1023 | tls_server_hook_cb(gnutls_session_t sess, u_int htype, unsigned when, |
| 1024 | unsigned incoming, const gnutls_datum_t * msg) |
| 1025 | { |
| 1026 | /* debug_printf("%s: htype %u\n", __FUNCTION__, htype); */ |
| 1027 | switch (htype) |
| 1028 | { |
| 1029 | # ifdef SUPPORT_GNUTLS_EXT_RAW_PARSE |
| 1030 | case GNUTLS_HANDSHAKE_CLIENT_HELLO: |
| 1031 | return tls_server_clienthello_cb(sess, htype, when, incoming, msg); |
| 1032 | case GNUTLS_HANDSHAKE_CERTIFICATE_PKT: |
| 1033 | return tls_server_servercerts_cb(sess, htype, when, incoming, msg); |
| 1034 | # endif |
| 1035 | case GNUTLS_HANDSHAKE_CERTIFICATE_STATUS: |
| 1036 | return tls_server_certstatus_cb(sess, htype, when, incoming, msg); |
| 1037 | # ifdef EXPERIMENTAL_TLS_RESUME |
| 1038 | case GNUTLS_HANDSHAKE_NEW_SESSION_TICKET: |
| 1039 | return tls_server_ticket_cb(sess, htype, when, incoming, msg); |
| 1040 | # endif |
| 1041 | default: |
| 1042 | return 0; |
| 1043 | } |
| 1044 | } |
| 1045 | #endif |
| 1046 | |
| 1047 | |
| 1048 | #if !defined(DISABLE_OCSP) && defined(SUPPORT_GNUTLS_EXT_RAW_PARSE) |
| 1049 | static void |
| 1050 | tls_server_testharness_ocsp_fiddle(void) |
| 1051 | { |
| 1052 | extern char ** environ; |
| 1053 | if (environ) for (uschar ** p = USS environ; *p; p++) |
| 1054 | if (Ustrncmp(*p, "EXIM_TESTHARNESS_DISABLE_OCSPVALIDITYCHECK", 42) == 0) |
| 1055 | { |
| 1056 | DEBUG(D_tls) debug_printf("Permitting known bad OCSP response\n"); |
| 1057 | exim_testharness_disable_ocsp_validity_check = TRUE; |
| 1058 | } |
| 1059 | } |
| 1060 | #endif |
| 1061 | |
| 1062 | /************************************************* |
| 1063 | * Variables re-expanded post-SNI * |
| 1064 | *************************************************/ |
| 1065 | |
| 1066 | /* Called from both server and client code, via tls_init(), and also from |
| 1067 | the SNI callback after receiving an SNI, if tls_certificate includes "tls_sni". |
| 1068 | |
| 1069 | We can tell the two apart by state->received_sni being non-NULL in callback. |
| 1070 | |
| 1071 | The callback should not call us unless state->trigger_sni_changes is true, |
| 1072 | which we are responsible for setting on the first pass through. |
| 1073 | |
| 1074 | Arguments: |
| 1075 | state exim_gnutls_state_st * |
| 1076 | errstr error string pointer |
| 1077 | |
| 1078 | Returns: OK/DEFER/FAIL |
| 1079 | */ |
| 1080 | |
| 1081 | static int |
| 1082 | tls_expand_session_files(exim_gnutls_state_st * state, uschar ** errstr) |
| 1083 | { |
| 1084 | struct stat statbuf; |
| 1085 | int rc; |
| 1086 | const host_item *host = state->host; /* macro should be reconsidered? */ |
| 1087 | uschar *saved_tls_certificate = NULL; |
| 1088 | uschar *saved_tls_privatekey = NULL; |
| 1089 | uschar *saved_tls_verify_certificates = NULL; |
| 1090 | uschar *saved_tls_crl = NULL; |
| 1091 | int cert_count; |
| 1092 | |
| 1093 | /* We check for tls_sni *before* expansion. */ |
| 1094 | if (!host) /* server */ |
| 1095 | if (!state->received_sni) |
| 1096 | { |
| 1097 | if ( state->tls_certificate |
| 1098 | && ( Ustrstr(state->tls_certificate, US"tls_sni") |
| 1099 | || Ustrstr(state->tls_certificate, US"tls_in_sni") |
| 1100 | || Ustrstr(state->tls_certificate, US"tls_out_sni") |
| 1101 | ) ) |
| 1102 | { |
| 1103 | DEBUG(D_tls) debug_printf("We will re-expand TLS session files if we receive SNI.\n"); |
| 1104 | state->trigger_sni_changes = TRUE; |
| 1105 | } |
| 1106 | } |
| 1107 | else |
| 1108 | { |
| 1109 | /* useful for debugging */ |
| 1110 | saved_tls_certificate = state->exp_tls_certificate; |
| 1111 | saved_tls_privatekey = state->exp_tls_privatekey; |
| 1112 | saved_tls_verify_certificates = state->exp_tls_verify_certificates; |
| 1113 | saved_tls_crl = state->exp_tls_crl; |
| 1114 | } |
| 1115 | |
| 1116 | if ((rc = gnutls_certificate_allocate_credentials(&state->x509_cred))) |
| 1117 | return tls_error_gnu(US"gnutls_certificate_allocate_credentials", |
| 1118 | rc, host, errstr); |
| 1119 | |
| 1120 | #ifdef SUPPORT_SRV_OCSP_STACK |
| 1121 | gnutls_certificate_set_flags(state->x509_cred, GNUTLS_CERTIFICATE_API_V2); |
| 1122 | |
| 1123 | # if !defined(DISABLE_OCSP) && defined(SUPPORT_GNUTLS_EXT_RAW_PARSE) |
| 1124 | if (!host && tls_ocsp_file) |
| 1125 | { |
| 1126 | if (f.running_in_test_harness) |
| 1127 | tls_server_testharness_ocsp_fiddle(); |
| 1128 | |
| 1129 | if (exim_testharness_disable_ocsp_validity_check) |
| 1130 | gnutls_certificate_set_flags(state->x509_cred, |
| 1131 | GNUTLS_CERTIFICATE_API_V2 | GNUTLS_CERTIFICATE_SKIP_OCSP_RESPONSE_CHECK); |
| 1132 | } |
| 1133 | # endif |
| 1134 | #endif |
| 1135 | |
| 1136 | /* remember: expand_check_tlsvar() is expand_check() but fiddling with |
| 1137 | state members, assuming consistent naming; and expand_check() returns |
| 1138 | false if expansion failed, unless expansion was forced to fail. */ |
| 1139 | |
| 1140 | /* check if we at least have a certificate, before doing expensive |
| 1141 | D-H generation. */ |
| 1142 | |
| 1143 | if (!expand_check_tlsvar(tls_certificate, errstr)) |
| 1144 | return DEFER; |
| 1145 | |
| 1146 | /* certificate is mandatory in server, optional in client */ |
| 1147 | |
| 1148 | if ( !state->exp_tls_certificate |
| 1149 | || !*state->exp_tls_certificate |
| 1150 | ) |
| 1151 | if (!host) |
| 1152 | return tls_install_selfsign(state, errstr); |
| 1153 | else |
| 1154 | DEBUG(D_tls) debug_printf("TLS: no client certificate specified; okay\n"); |
| 1155 | |
| 1156 | if (state->tls_privatekey && !expand_check_tlsvar(tls_privatekey, errstr)) |
| 1157 | return DEFER; |
| 1158 | |
| 1159 | /* tls_privatekey is optional, defaulting to same file as certificate */ |
| 1160 | |
| 1161 | if (!state->tls_privatekey || !*state->tls_privatekey) |
| 1162 | { |
| 1163 | state->tls_privatekey = state->tls_certificate; |
| 1164 | state->exp_tls_privatekey = state->exp_tls_certificate; |
| 1165 | } |
| 1166 | |
| 1167 | |
| 1168 | if (state->exp_tls_certificate && *state->exp_tls_certificate) |
| 1169 | { |
| 1170 | DEBUG(D_tls) debug_printf("certificate file = %s\nkey file = %s\n", |
| 1171 | state->exp_tls_certificate, state->exp_tls_privatekey); |
| 1172 | |
| 1173 | if (state->received_sni) |
| 1174 | if ( Ustrcmp(state->exp_tls_certificate, saved_tls_certificate) == 0 |
| 1175 | && Ustrcmp(state->exp_tls_privatekey, saved_tls_privatekey) == 0 |
| 1176 | ) |
| 1177 | { |
| 1178 | DEBUG(D_tls) debug_printf("TLS SNI: cert and key unchanged\n"); |
| 1179 | } |
| 1180 | else |
| 1181 | { |
| 1182 | DEBUG(D_tls) debug_printf("TLS SNI: have a changed cert/key pair.\n"); |
| 1183 | } |
| 1184 | |
| 1185 | if (!host) /* server */ |
| 1186 | { |
| 1187 | const uschar * clist = state->exp_tls_certificate; |
| 1188 | const uschar * klist = state->exp_tls_privatekey; |
| 1189 | const uschar * olist; |
| 1190 | int csep = 0, ksep = 0, osep = 0, cnt = 0; |
| 1191 | uschar * cfile, * kfile, * ofile; |
| 1192 | #ifndef DISABLE_OCSP |
| 1193 | # ifdef SUPPORT_GNUTLS_EXT_RAW_PARSE |
| 1194 | gnutls_x509_crt_fmt_t ocsp_fmt = GNUTLS_X509_FMT_DER; |
| 1195 | # endif |
| 1196 | |
| 1197 | if (!expand_check(tls_ocsp_file, US"tls_ocsp_file", &ofile, errstr)) |
| 1198 | return DEFER; |
| 1199 | olist = ofile; |
| 1200 | #endif |
| 1201 | |
| 1202 | while (cfile = string_nextinlist(&clist, &csep, NULL, 0)) |
| 1203 | |
| 1204 | if (!(kfile = string_nextinlist(&klist, &ksep, NULL, 0))) |
| 1205 | return tls_error(US"cert/key setup: out of keys", NULL, host, errstr); |
| 1206 | else if (0 < (rc = tls_add_certfile(state, host, cfile, kfile, errstr))) |
| 1207 | return rc; |
| 1208 | else |
| 1209 | { |
| 1210 | int gnutls_cert_index = -rc; |
| 1211 | DEBUG(D_tls) debug_printf("TLS: cert/key %d %s registered\n", |
| 1212 | gnutls_cert_index, cfile); |
| 1213 | |
| 1214 | #ifndef DISABLE_OCSP |
| 1215 | if (tls_ocsp_file) |
| 1216 | { |
| 1217 | /* Set the OCSP stapling server info */ |
| 1218 | if (gnutls_buggy_ocsp) |
| 1219 | { |
| 1220 | DEBUG(D_tls) |
| 1221 | debug_printf("GnuTLS library is buggy for OCSP; avoiding\n"); |
| 1222 | } |
| 1223 | else if ((ofile = string_nextinlist(&olist, &osep, NULL, 0))) |
| 1224 | { |
| 1225 | DEBUG(D_tls) debug_printf("OCSP response file %d = %s\n", |
| 1226 | gnutls_cert_index, ofile); |
| 1227 | # ifdef SUPPORT_GNUTLS_EXT_RAW_PARSE |
| 1228 | if (Ustrncmp(ofile, US"PEM ", 4) == 0) |
| 1229 | { |
| 1230 | ocsp_fmt = GNUTLS_X509_FMT_PEM; |
| 1231 | ofile += 4; |
| 1232 | } |
| 1233 | else if (Ustrncmp(ofile, US"DER ", 4) == 0) |
| 1234 | { |
| 1235 | ocsp_fmt = GNUTLS_X509_FMT_DER; |
| 1236 | ofile += 4; |
| 1237 | } |
| 1238 | |
| 1239 | if ((rc = gnutls_certificate_set_ocsp_status_request_file2( |
| 1240 | state->x509_cred, CCS ofile, gnutls_cert_index, |
| 1241 | ocsp_fmt)) < 0) |
| 1242 | return tls_error_gnu( |
| 1243 | US"gnutls_certificate_set_ocsp_status_request_file2", |
| 1244 | rc, host, errstr); |
| 1245 | DEBUG(D_tls) |
| 1246 | debug_printf(" %d response%s loaded\n", rc, rc>1 ? "s":""); |
| 1247 | |
| 1248 | /* Arrange callbacks for OCSP request observability */ |
| 1249 | |
| 1250 | gnutls_handshake_set_hook_function(state->session, |
| 1251 | GNUTLS_HANDSHAKE_ANY, GNUTLS_HOOK_POST, tls_server_hook_cb); |
| 1252 | |
| 1253 | # else |
| 1254 | # if defined(SUPPORT_SRV_OCSP_STACK) |
| 1255 | if ((rc = gnutls_certificate_set_ocsp_status_request_function2( |
| 1256 | state->x509_cred, gnutls_cert_index, |
| 1257 | server_ocsp_stapling_cb, ofile))) |
| 1258 | return tls_error_gnu( |
| 1259 | US"gnutls_certificate_set_ocsp_status_request_function2", |
| 1260 | rc, host, errstr); |
| 1261 | else |
| 1262 | # endif |
| 1263 | { |
| 1264 | if (cnt++ > 0) |
| 1265 | { |
| 1266 | DEBUG(D_tls) |
| 1267 | debug_printf("oops; multiple OCSP files not supported\n"); |
| 1268 | break; |
| 1269 | } |
| 1270 | gnutls_certificate_set_ocsp_status_request_function( |
| 1271 | state->x509_cred, server_ocsp_stapling_cb, ofile); |
| 1272 | } |
| 1273 | # endif /* SUPPORT_GNUTLS_EXT_RAW_PARSE */ |
| 1274 | } |
| 1275 | else |
| 1276 | DEBUG(D_tls) debug_printf("ran out of OCSP response files in list\n"); |
| 1277 | } |
| 1278 | #endif /* DISABLE_OCSP */ |
| 1279 | } |
| 1280 | } |
| 1281 | else /* client */ |
| 1282 | { |
| 1283 | if (0 < (rc = tls_add_certfile(state, host, |
| 1284 | state->exp_tls_certificate, state->exp_tls_privatekey, errstr))) |
| 1285 | return rc; |
| 1286 | DEBUG(D_tls) debug_printf("TLS: cert/key registered\n"); |
| 1287 | } |
| 1288 | |
| 1289 | } /* tls_certificate */ |
| 1290 | |
| 1291 | |
| 1292 | /* Set the trusted CAs file if one is provided, and then add the CRL if one is |
| 1293 | provided. Experiment shows that, if the certificate file is empty, an unhelpful |
| 1294 | error message is provided. However, if we just refrain from setting anything up |
| 1295 | in that case, certificate verification fails, which seems to be the correct |
| 1296 | behaviour. */ |
| 1297 | |
| 1298 | if (state->tls_verify_certificates && *state->tls_verify_certificates) |
| 1299 | { |
| 1300 | if (!expand_check_tlsvar(tls_verify_certificates, errstr)) |
| 1301 | return DEFER; |
| 1302 | #ifndef SUPPORT_SYSDEFAULT_CABUNDLE |
| 1303 | if (Ustrcmp(state->exp_tls_verify_certificates, "system") == 0) |
| 1304 | state->exp_tls_verify_certificates = NULL; |
| 1305 | #endif |
| 1306 | if (state->tls_crl && *state->tls_crl) |
| 1307 | if (!expand_check_tlsvar(tls_crl, errstr)) |
| 1308 | return DEFER; |
| 1309 | |
| 1310 | if (!(state->exp_tls_verify_certificates && |
| 1311 | *state->exp_tls_verify_certificates)) |
| 1312 | { |
| 1313 | DEBUG(D_tls) |
| 1314 | debug_printf("TLS: tls_verify_certificates expanded empty, ignoring\n"); |
| 1315 | /* With no tls_verify_certificates, we ignore tls_crl too */ |
| 1316 | return OK; |
| 1317 | } |
| 1318 | } |
| 1319 | else |
| 1320 | { |
| 1321 | DEBUG(D_tls) |
| 1322 | debug_printf("TLS: tls_verify_certificates not set or empty, ignoring\n"); |
| 1323 | return OK; |
| 1324 | } |
| 1325 | |
| 1326 | #ifdef SUPPORT_SYSDEFAULT_CABUNDLE |
| 1327 | if (Ustrcmp(state->exp_tls_verify_certificates, "system") == 0) |
| 1328 | cert_count = gnutls_certificate_set_x509_system_trust(state->x509_cred); |
| 1329 | else |
| 1330 | #endif |
| 1331 | { |
| 1332 | if (Ustat(state->exp_tls_verify_certificates, &statbuf) < 0) |
| 1333 | { |
| 1334 | log_write(0, LOG_MAIN|LOG_PANIC, "could not stat '%s' " |
| 1335 | "(tls_verify_certificates): %s", state->exp_tls_verify_certificates, |
| 1336 | strerror(errno)); |
| 1337 | return DEFER; |
| 1338 | } |
| 1339 | |
| 1340 | #ifndef SUPPORT_CA_DIR |
| 1341 | /* The test suite passes in /dev/null; we could check for that path explicitly, |
| 1342 | but who knows if someone has some weird FIFO which always dumps some certs, or |
| 1343 | other weirdness. The thing we really want to check is that it's not a |
| 1344 | directory, since while OpenSSL supports that, GnuTLS does not. |
| 1345 | So s/!S_ISREG/S_ISDIR/ and change some messaging ... */ |
| 1346 | if (S_ISDIR(statbuf.st_mode)) |
| 1347 | { |
| 1348 | DEBUG(D_tls) |
| 1349 | debug_printf("verify certificates path is a dir: \"%s\"\n", |
| 1350 | state->exp_tls_verify_certificates); |
| 1351 | log_write(0, LOG_MAIN|LOG_PANIC, |
| 1352 | "tls_verify_certificates \"%s\" is a directory", |
| 1353 | state->exp_tls_verify_certificates); |
| 1354 | return DEFER; |
| 1355 | } |
| 1356 | #endif |
| 1357 | |
| 1358 | DEBUG(D_tls) debug_printf("verify certificates = %s size=" OFF_T_FMT "\n", |
| 1359 | state->exp_tls_verify_certificates, statbuf.st_size); |
| 1360 | |
| 1361 | if (statbuf.st_size == 0) |
| 1362 | { |
| 1363 | DEBUG(D_tls) |
| 1364 | debug_printf("cert file empty, no certs, no verification, ignoring any CRL\n"); |
| 1365 | return OK; |
| 1366 | } |
| 1367 | |
| 1368 | cert_count = |
| 1369 | |
| 1370 | #ifdef SUPPORT_CA_DIR |
| 1371 | (statbuf.st_mode & S_IFMT) == S_IFDIR |
| 1372 | ? |
| 1373 | gnutls_certificate_set_x509_trust_dir(state->x509_cred, |
| 1374 | CS state->exp_tls_verify_certificates, GNUTLS_X509_FMT_PEM) |
| 1375 | : |
| 1376 | #endif |
| 1377 | gnutls_certificate_set_x509_trust_file(state->x509_cred, |
| 1378 | CS state->exp_tls_verify_certificates, GNUTLS_X509_FMT_PEM); |
| 1379 | |
| 1380 | #ifdef SUPPORT_CA_DIR |
| 1381 | /* Mimic the behaviour with OpenSSL of not advertising a usable-cert list |
| 1382 | when using the directory-of-certs config model. */ |
| 1383 | |
| 1384 | if ((statbuf.st_mode & S_IFMT) == S_IFDIR) |
| 1385 | gnutls_certificate_send_x509_rdn_sequence(state->session, 1); |
| 1386 | #endif |
| 1387 | } |
| 1388 | |
| 1389 | if (cert_count < 0) |
| 1390 | return tls_error_gnu(US"setting certificate trust", cert_count, host, errstr); |
| 1391 | DEBUG(D_tls) |
| 1392 | debug_printf("Added %d certificate authorities.\n", cert_count); |
| 1393 | |
| 1394 | if (state->tls_crl && *state->tls_crl && |
| 1395 | state->exp_tls_crl && *state->exp_tls_crl) |
| 1396 | { |
| 1397 | DEBUG(D_tls) debug_printf("loading CRL file = %s\n", state->exp_tls_crl); |
| 1398 | if ((cert_count = gnutls_certificate_set_x509_crl_file(state->x509_cred, |
| 1399 | CS state->exp_tls_crl, GNUTLS_X509_FMT_PEM)) < 0) |
| 1400 | return tls_error_gnu(US"gnutls_certificate_set_x509_crl_file", |
| 1401 | cert_count, host, errstr); |
| 1402 | |
| 1403 | DEBUG(D_tls) debug_printf("Processed %d CRLs.\n", cert_count); |
| 1404 | } |
| 1405 | |
| 1406 | return OK; |
| 1407 | } |
| 1408 | |
| 1409 | |
| 1410 | |
| 1411 | |
| 1412 | /************************************************* |
| 1413 | * Set X.509 state variables * |
| 1414 | *************************************************/ |
| 1415 | |
| 1416 | /* In GnuTLS, the registered cert/key are not replaced by a later |
| 1417 | set of a cert/key, so for SNI support we need a whole new x509_cred |
| 1418 | structure. Which means various other non-re-expanded pieces of state |
| 1419 | need to be re-set in the new struct, so the setting logic is pulled |
| 1420 | out to this. |
| 1421 | |
| 1422 | Arguments: |
| 1423 | state exim_gnutls_state_st * |
| 1424 | errstr error string pointer |
| 1425 | |
| 1426 | Returns: OK/DEFER/FAIL |
| 1427 | */ |
| 1428 | |
| 1429 | static int |
| 1430 | tls_set_remaining_x509(exim_gnutls_state_st *state, uschar ** errstr) |
| 1431 | { |
| 1432 | int rc; |
| 1433 | const host_item *host = state->host; /* macro should be reconsidered? */ |
| 1434 | |
| 1435 | #ifndef GNUTLS_AUTO_DHPARAMS |
| 1436 | /* Create D-H parameters, or read them from the cache file. This function does |
| 1437 | its own SMTP error messaging. This only happens for the server, TLS D-H ignores |
| 1438 | client-side params. */ |
| 1439 | |
| 1440 | if (!state->host) |
| 1441 | { |
| 1442 | if (!dh_server_params) |
| 1443 | if ((rc = init_server_dh(errstr)) != OK) return rc; |
| 1444 | |
| 1445 | /* Unnecessary & discouraged with 3.6.0 or later */ |
| 1446 | gnutls_certificate_set_dh_params(state->x509_cred, dh_server_params); |
| 1447 | } |
| 1448 | #endif |
| 1449 | |
| 1450 | /* Link the credentials to the session. */ |
| 1451 | |
| 1452 | if ((rc = gnutls_credentials_set(state->session, |
| 1453 | GNUTLS_CRD_CERTIFICATE, state->x509_cred))) |
| 1454 | return tls_error_gnu(US"gnutls_credentials_set", rc, host, errstr); |
| 1455 | |
| 1456 | return OK; |
| 1457 | } |
| 1458 | |
| 1459 | /************************************************* |
| 1460 | * Initialize for GnuTLS * |
| 1461 | *************************************************/ |
| 1462 | |
| 1463 | |
| 1464 | #ifndef DISABLE_OCSP |
| 1465 | |
| 1466 | static BOOL |
| 1467 | tls_is_buggy_ocsp(void) |
| 1468 | { |
| 1469 | const uschar * s; |
| 1470 | uschar maj, mid, mic; |
| 1471 | |
| 1472 | s = CUS gnutls_check_version(NULL); |
| 1473 | maj = atoi(CCS s); |
| 1474 | if (maj == 3) |
| 1475 | { |
| 1476 | while (*s && *s != '.') s++; |
| 1477 | mid = atoi(CCS ++s); |
| 1478 | if (mid <= 2) |
| 1479 | return TRUE; |
| 1480 | else if (mid >= 5) |
| 1481 | return FALSE; |
| 1482 | else |
| 1483 | { |
| 1484 | while (*s && *s != '.') s++; |
| 1485 | mic = atoi(CCS ++s); |
| 1486 | return mic <= (mid == 3 ? 16 : 3); |
| 1487 | } |
| 1488 | } |
| 1489 | return FALSE; |
| 1490 | } |
| 1491 | |
| 1492 | #endif |
| 1493 | |
| 1494 | |
| 1495 | /* Called from both server and client code. In the case of a server, errors |
| 1496 | before actual TLS negotiation return DEFER. |
| 1497 | |
| 1498 | Arguments: |
| 1499 | host connected host, if client; NULL if server |
| 1500 | certificate certificate file |
| 1501 | privatekey private key file |
| 1502 | sni TLS SNI to send, sometimes when client; else NULL |
| 1503 | cas CA certs file |
| 1504 | crl CRL file |
| 1505 | require_ciphers tls_require_ciphers setting |
| 1506 | caller_state returned state-info structure |
| 1507 | errstr error string pointer |
| 1508 | |
| 1509 | Returns: OK/DEFER/FAIL |
| 1510 | */ |
| 1511 | |
| 1512 | static int |
| 1513 | tls_init( |
| 1514 | const host_item *host, |
| 1515 | const uschar *certificate, |
| 1516 | const uschar *privatekey, |
| 1517 | const uschar *sni, |
| 1518 | const uschar *cas, |
| 1519 | const uschar *crl, |
| 1520 | const uschar *require_ciphers, |
| 1521 | exim_gnutls_state_st **caller_state, |
| 1522 | tls_support * tlsp, |
| 1523 | uschar ** errstr) |
| 1524 | { |
| 1525 | exim_gnutls_state_st * state; |
| 1526 | int rc; |
| 1527 | size_t sz; |
| 1528 | const char * errpos; |
| 1529 | const uschar * p; |
| 1530 | |
| 1531 | if (!exim_gnutls_base_init_done) |
| 1532 | { |
| 1533 | DEBUG(D_tls) debug_printf("GnuTLS global init required.\n"); |
| 1534 | |
| 1535 | #if defined(HAVE_GNUTLS_PKCS11) && !defined(GNUTLS_AUTO_PKCS11_MANUAL) |
| 1536 | /* By default, gnutls_global_init will init PKCS11 support in auto mode, |
| 1537 | which loads modules from a config file, which sounds good and may be wanted |
| 1538 | by some sysadmin, but also means in common configurations that GNOME keyring |
| 1539 | environment variables are used and so breaks for users calling mailq. |
| 1540 | To prevent this, we init PKCS11 first, which is the documented approach. */ |
| 1541 | if (!gnutls_allow_auto_pkcs11) |
| 1542 | if ((rc = gnutls_pkcs11_init(GNUTLS_PKCS11_FLAG_MANUAL, NULL))) |
| 1543 | return tls_error_gnu(US"gnutls_pkcs11_init", rc, host, errstr); |
| 1544 | #endif |
| 1545 | |
| 1546 | #ifndef GNUTLS_AUTO_GLOBAL_INIT |
| 1547 | if ((rc = gnutls_global_init())) |
| 1548 | return tls_error_gnu(US"gnutls_global_init", rc, host, errstr); |
| 1549 | #endif |
| 1550 | |
| 1551 | #if EXIM_GNUTLS_LIBRARY_LOG_LEVEL >= 0 |
| 1552 | DEBUG(D_tls) |
| 1553 | { |
| 1554 | gnutls_global_set_log_function(exim_gnutls_logger_cb); |
| 1555 | /* arbitrarily chosen level; bump up to 9 for more */ |
| 1556 | gnutls_global_set_log_level(EXIM_GNUTLS_LIBRARY_LOG_LEVEL); |
| 1557 | } |
| 1558 | #endif |
| 1559 | |
| 1560 | #ifndef DISABLE_OCSP |
| 1561 | if (tls_ocsp_file && (gnutls_buggy_ocsp = tls_is_buggy_ocsp())) |
| 1562 | log_write(0, LOG_MAIN, "OCSP unusable with this GnuTLS library version"); |
| 1563 | #endif |
| 1564 | |
| 1565 | exim_gnutls_base_init_done = TRUE; |
| 1566 | } |
| 1567 | |
| 1568 | if (host) |
| 1569 | { |
| 1570 | /* For client-side sessions we allocate a context. This lets us run |
| 1571 | several in parallel. */ |
| 1572 | int old_pool = store_pool; |
| 1573 | store_pool = POOL_PERM; |
| 1574 | state = store_get(sizeof(exim_gnutls_state_st), FALSE); |
| 1575 | store_pool = old_pool; |
| 1576 | |
| 1577 | memcpy(state, &exim_gnutls_state_init, sizeof(exim_gnutls_state_init)); |
| 1578 | state->tlsp = tlsp; |
| 1579 | DEBUG(D_tls) debug_printf("initialising GnuTLS client session\n"); |
| 1580 | rc = gnutls_init(&state->session, GNUTLS_CLIENT); |
| 1581 | } |
| 1582 | else |
| 1583 | { |
| 1584 | state = &state_server; |
| 1585 | memcpy(state, &exim_gnutls_state_init, sizeof(exim_gnutls_state_init)); |
| 1586 | state->tlsp = tlsp; |
| 1587 | DEBUG(D_tls) debug_printf("initialising GnuTLS server session\n"); |
| 1588 | rc = gnutls_init(&state->session, GNUTLS_SERVER); |
| 1589 | } |
| 1590 | if (rc) |
| 1591 | return tls_error_gnu(US"gnutls_init", rc, host, errstr); |
| 1592 | |
| 1593 | state->host = host; |
| 1594 | |
| 1595 | state->tls_certificate = certificate; |
| 1596 | state->tls_privatekey = privatekey; |
| 1597 | state->tls_require_ciphers = require_ciphers; |
| 1598 | state->tls_sni = sni; |
| 1599 | state->tls_verify_certificates = cas; |
| 1600 | state->tls_crl = crl; |
| 1601 | |
| 1602 | /* This handles the variables that might get re-expanded after TLS SNI; |
| 1603 | that's tls_certificate, tls_privatekey, tls_verify_certificates, tls_crl */ |
| 1604 | |
| 1605 | DEBUG(D_tls) |
| 1606 | debug_printf("Expanding various TLS configuration options for session credentials.\n"); |
| 1607 | if ((rc = tls_expand_session_files(state, errstr)) != OK) return rc; |
| 1608 | |
| 1609 | /* These are all other parts of the x509_cred handling, since SNI in GnuTLS |
| 1610 | requires a new structure afterwards. */ |
| 1611 | |
| 1612 | if ((rc = tls_set_remaining_x509(state, errstr)) != OK) return rc; |
| 1613 | |
| 1614 | /* set SNI in client, only */ |
| 1615 | if (host) |
| 1616 | { |
| 1617 | if (!expand_check(sni, US"tls_out_sni", &state->tlsp->sni, errstr)) |
| 1618 | return DEFER; |
| 1619 | if (state->tlsp->sni && *state->tlsp->sni) |
| 1620 | { |
| 1621 | DEBUG(D_tls) |
| 1622 | debug_printf("Setting TLS client SNI to \"%s\"\n", state->tlsp->sni); |
| 1623 | sz = Ustrlen(state->tlsp->sni); |
| 1624 | if ((rc = gnutls_server_name_set(state->session, |
| 1625 | GNUTLS_NAME_DNS, state->tlsp->sni, sz))) |
| 1626 | return tls_error_gnu(US"gnutls_server_name_set", rc, host, errstr); |
| 1627 | } |
| 1628 | } |
| 1629 | else if (state->tls_sni) |
| 1630 | DEBUG(D_tls) debug_printf("*** PROBABLY A BUG *** " \ |
| 1631 | "have an SNI set for a server [%s]\n", state->tls_sni); |
| 1632 | |
| 1633 | /* This is the priority string support, |
| 1634 | http://www.gnutls.org/manual/html_node/Priority-Strings.html |
| 1635 | and replaces gnutls_require_kx, gnutls_require_mac & gnutls_require_protocols. |
| 1636 | This was backwards incompatible, but means Exim no longer needs to track |
| 1637 | all algorithms and provide string forms for them. */ |
| 1638 | |
| 1639 | p = NULL; |
| 1640 | if (state->tls_require_ciphers && *state->tls_require_ciphers) |
| 1641 | { |
| 1642 | if (!expand_check_tlsvar(tls_require_ciphers, errstr)) |
| 1643 | return DEFER; |
| 1644 | if (state->exp_tls_require_ciphers && *state->exp_tls_require_ciphers) |
| 1645 | { |
| 1646 | p = state->exp_tls_require_ciphers; |
| 1647 | DEBUG(D_tls) debug_printf("GnuTLS session cipher/priority \"%s\"\n", p); |
| 1648 | } |
| 1649 | } |
| 1650 | if (!p) |
| 1651 | { |
| 1652 | p = exim_default_gnutls_priority; |
| 1653 | DEBUG(D_tls) |
| 1654 | debug_printf("GnuTLS using default session cipher/priority \"%s\"\n", p); |
| 1655 | } |
| 1656 | |
| 1657 | if ((rc = gnutls_priority_init(&state->priority_cache, CCS p, &errpos))) |
| 1658 | return tls_error_gnu(string_sprintf( |
| 1659 | "gnutls_priority_init(%s) failed at offset %ld, \"%.6s..\"", |
| 1660 | p, errpos - CS p, errpos), |
| 1661 | rc, host, errstr); |
| 1662 | |
| 1663 | if ((rc = gnutls_priority_set(state->session, state->priority_cache))) |
| 1664 | return tls_error_gnu(US"gnutls_priority_set", rc, host, errstr); |
| 1665 | |
| 1666 | /* This also sets the server ticket expiration time to the same, and |
| 1667 | the STEK rotation time to 3x. */ |
| 1668 | |
| 1669 | gnutls_db_set_cache_expiration(state->session, ssl_session_timeout); |
| 1670 | |
| 1671 | /* Reduce security in favour of increased compatibility, if the admin |
| 1672 | decides to make that trade-off. */ |
| 1673 | if (gnutls_compat_mode) |
| 1674 | { |
| 1675 | #if LIBGNUTLS_VERSION_NUMBER >= 0x020104 |
| 1676 | DEBUG(D_tls) debug_printf("lowering GnuTLS security, compatibility mode\n"); |
| 1677 | gnutls_session_enable_compatibility_mode(state->session); |
| 1678 | #else |
| 1679 | DEBUG(D_tls) debug_printf("Unable to set gnutls_compat_mode - GnuTLS version too old\n"); |
| 1680 | #endif |
| 1681 | } |
| 1682 | |
| 1683 | *caller_state = state; |
| 1684 | return OK; |
| 1685 | } |
| 1686 | |
| 1687 | |
| 1688 | |
| 1689 | /************************************************* |
| 1690 | * Extract peer information * |
| 1691 | *************************************************/ |
| 1692 | |
| 1693 | static const uschar * |
| 1694 | cipher_stdname_kcm(gnutls_kx_algorithm_t kx, gnutls_cipher_algorithm_t cipher, |
| 1695 | gnutls_mac_algorithm_t mac) |
| 1696 | { |
| 1697 | uschar cs_id[2]; |
| 1698 | gnutls_kx_algorithm_t kx_i; |
| 1699 | gnutls_cipher_algorithm_t cipher_i; |
| 1700 | gnutls_mac_algorithm_t mac_i; |
| 1701 | |
| 1702 | for (size_t i = 0; |
| 1703 | gnutls_cipher_suite_info(i, cs_id, &kx_i, &cipher_i, &mac_i, NULL); |
| 1704 | i++) |
| 1705 | if (kx_i == kx && cipher_i == cipher && mac_i == mac) |
| 1706 | return cipher_stdname(cs_id[0], cs_id[1]); |
| 1707 | return NULL; |
| 1708 | } |
| 1709 | |
| 1710 | |
| 1711 | |
| 1712 | /* Called from both server and client code. |
| 1713 | Only this is allowed to set state->peerdn and state->have_set_peerdn |
| 1714 | and we use that to detect double-calls. |
| 1715 | |
| 1716 | NOTE: the state blocks last while the TLS connection is up, which is fine |
| 1717 | for logging in the server side, but for the client side, we log after teardown |
| 1718 | in src/deliver.c. While the session is up, we can twist about states and |
| 1719 | repoint tls_* globals, but those variables used for logging or other variable |
| 1720 | expansion that happens _after_ delivery need to have a longer life-time. |
| 1721 | |
| 1722 | So for those, we get the data from POOL_PERM; the re-invoke guard keeps us from |
| 1723 | doing this more than once per generation of a state context. We set them in |
| 1724 | the state context, and repoint tls_* to them. After the state goes away, the |
| 1725 | tls_* copies of the pointers remain valid and client delivery logging is happy. |
| 1726 | |
| 1727 | tls_certificate_verified is a BOOL, so the tls_peerdn and tls_cipher issues |
| 1728 | don't apply. |
| 1729 | |
| 1730 | Arguments: |
| 1731 | state exim_gnutls_state_st * |
| 1732 | errstr pointer to error string |
| 1733 | |
| 1734 | Returns: OK/DEFER/FAIL |
| 1735 | */ |
| 1736 | |
| 1737 | static int |
| 1738 | peer_status(exim_gnutls_state_st * state, uschar ** errstr) |
| 1739 | { |
| 1740 | gnutls_session_t session = state->session; |
| 1741 | const gnutls_datum_t * cert_list; |
| 1742 | int old_pool, rc; |
| 1743 | unsigned int cert_list_size = 0; |
| 1744 | gnutls_protocol_t protocol; |
| 1745 | gnutls_cipher_algorithm_t cipher; |
| 1746 | gnutls_kx_algorithm_t kx; |
| 1747 | gnutls_mac_algorithm_t mac; |
| 1748 | gnutls_certificate_type_t ct; |
| 1749 | gnutls_x509_crt_t crt; |
| 1750 | uschar * dn_buf; |
| 1751 | size_t sz; |
| 1752 | |
| 1753 | if (state->have_set_peerdn) |
| 1754 | return OK; |
| 1755 | state->have_set_peerdn = TRUE; |
| 1756 | |
| 1757 | state->peerdn = NULL; |
| 1758 | |
| 1759 | /* tls_cipher */ |
| 1760 | cipher = gnutls_cipher_get(session); |
| 1761 | protocol = gnutls_protocol_get_version(session); |
| 1762 | mac = gnutls_mac_get(session); |
| 1763 | kx = |
| 1764 | #ifdef GNUTLS_TLS1_3 |
| 1765 | protocol >= GNUTLS_TLS1_3 ? 0 : |
| 1766 | #endif |
| 1767 | gnutls_kx_get(session); |
| 1768 | |
| 1769 | old_pool = store_pool; |
| 1770 | { |
| 1771 | tls_support * tlsp = state->tlsp; |
| 1772 | store_pool = POOL_PERM; |
| 1773 | |
| 1774 | #ifdef SUPPORT_GNUTLS_SESS_DESC |
| 1775 | { |
| 1776 | gstring * g = NULL; |
| 1777 | uschar * s = US gnutls_session_get_desc(session), c; |
| 1778 | |
| 1779 | /* Nikos M suggests we use this by preference. It returns like: |
| 1780 | (TLS1.3)-(ECDHE-SECP256R1)-(RSA-PSS-RSAE-SHA256)-(AES-256-GCM) |
| 1781 | |
| 1782 | For partial back-compat, put a colon after the TLS version, replace the |
| 1783 | )-( grouping with __, replace in-group - with _ and append the :keysize. */ |
| 1784 | |
| 1785 | /* debug_printf("peer_status: gnutls_session_get_desc %s\n", s); */ |
| 1786 | |
| 1787 | for (s++; (c = *s) && c != ')'; s++) g = string_catn(g, s, 1); |
| 1788 | |
| 1789 | tlsp->ver = string_copyn(g->s, g->ptr); |
| 1790 | for (uschar * p = US tlsp->ver; *p; p++) |
| 1791 | if (*p == '-') { *p = '\0'; break; } /* TLS1.0-PKIX -> TLS1.0 */ |
| 1792 | |
| 1793 | g = string_catn(g, US":", 1); |
| 1794 | if (*s) s++; /* now on _ between groups */ |
| 1795 | while ((c = *s)) |
| 1796 | { |
| 1797 | for (*++s && ++s; (c = *s) && c != ')'; s++) |
| 1798 | g = string_catn(g, c == '-' ? US"_" : s, 1); |
| 1799 | /* now on ) closing group */ |
| 1800 | if ((c = *s) && *++s == '-') g = string_catn(g, US"__", 2); |
| 1801 | /* now on _ between groups */ |
| 1802 | } |
| 1803 | g = string_catn(g, US":", 1); |
| 1804 | g = string_cat(g, string_sprintf("%d", (int) gnutls_cipher_get_key_size(cipher) * 8)); |
| 1805 | state->ciphersuite = string_from_gstring(g); |
| 1806 | } |
| 1807 | #else |
| 1808 | state->ciphersuite = string_sprintf("%s:%s:%d", |
| 1809 | gnutls_protocol_get_name(protocol), |
| 1810 | gnutls_cipher_suite_get_name(kx, cipher, mac), |
| 1811 | (int) gnutls_cipher_get_key_size(cipher) * 8); |
| 1812 | |
| 1813 | /* I don't see a way that spaces could occur, in the current GnuTLS |
| 1814 | code base, but it was a concern in the old code and perhaps older GnuTLS |
| 1815 | releases did return "TLS 1.0"; play it safe, just in case. */ |
| 1816 | |
| 1817 | for (uschar * p = state->ciphersuite; *p; p++) if (isspace(*p)) *p = '-'; |
| 1818 | tlsp->ver = string_copyn(state->ciphersuite, |
| 1819 | Ustrchr(state->ciphersuite, ':') - state->ciphersuite); |
| 1820 | #endif |
| 1821 | |
| 1822 | /* debug_printf("peer_status: ciphersuite %s\n", state->ciphersuite); */ |
| 1823 | |
| 1824 | tlsp->cipher = state->ciphersuite; |
| 1825 | tlsp->bits = gnutls_cipher_get_key_size(cipher) * 8; |
| 1826 | |
| 1827 | tlsp->cipher_stdname = cipher_stdname_kcm(kx, cipher, mac); |
| 1828 | } |
| 1829 | store_pool = old_pool; |
| 1830 | |
| 1831 | /* tls_peerdn */ |
| 1832 | cert_list = gnutls_certificate_get_peers(session, &cert_list_size); |
| 1833 | |
| 1834 | if (!cert_list || cert_list_size == 0) |
| 1835 | { |
| 1836 | DEBUG(D_tls) debug_printf("TLS: no certificate from peer (%p & %d)\n", |
| 1837 | cert_list, cert_list_size); |
| 1838 | if (state->verify_requirement >= VERIFY_REQUIRED) |
| 1839 | return tls_error(US"certificate verification failed", |
| 1840 | US"no certificate received from peer", state->host, errstr); |
| 1841 | return OK; |
| 1842 | } |
| 1843 | |
| 1844 | if ((ct = gnutls_certificate_type_get(session)) != GNUTLS_CRT_X509) |
| 1845 | { |
| 1846 | const uschar * ctn = US gnutls_certificate_type_get_name(ct); |
| 1847 | DEBUG(D_tls) |
| 1848 | debug_printf("TLS: peer cert not X.509 but instead \"%s\"\n", ctn); |
| 1849 | if (state->verify_requirement >= VERIFY_REQUIRED) |
| 1850 | return tls_error(US"certificate verification not possible, unhandled type", |
| 1851 | ctn, state->host, errstr); |
| 1852 | return OK; |
| 1853 | } |
| 1854 | |
| 1855 | #define exim_gnutls_peer_err(Label) \ |
| 1856 | do { \ |
| 1857 | if (rc != GNUTLS_E_SUCCESS) \ |
| 1858 | { \ |
| 1859 | DEBUG(D_tls) debug_printf("TLS: peer cert problem: %s: %s\n", \ |
| 1860 | (Label), gnutls_strerror(rc)); \ |
| 1861 | if (state->verify_requirement >= VERIFY_REQUIRED) \ |
| 1862 | return tls_error_gnu((Label), rc, state->host, errstr); \ |
| 1863 | return OK; \ |
| 1864 | } \ |
| 1865 | } while (0) |
| 1866 | |
| 1867 | rc = import_cert(&cert_list[0], &crt); |
| 1868 | exim_gnutls_peer_err(US"cert 0"); |
| 1869 | |
| 1870 | state->tlsp->peercert = state->peercert = crt; |
| 1871 | |
| 1872 | sz = 0; |
| 1873 | rc = gnutls_x509_crt_get_dn(crt, NULL, &sz); |
| 1874 | if (rc != GNUTLS_E_SHORT_MEMORY_BUFFER) |
| 1875 | { |
| 1876 | exim_gnutls_peer_err(US"getting size for cert DN failed"); |
| 1877 | return FAIL; /* should not happen */ |
| 1878 | } |
| 1879 | dn_buf = store_get_perm(sz, TRUE); /* tainted */ |
| 1880 | rc = gnutls_x509_crt_get_dn(crt, CS dn_buf, &sz); |
| 1881 | exim_gnutls_peer_err(US"failed to extract certificate DN [gnutls_x509_crt_get_dn(cert 0)]"); |
| 1882 | |
| 1883 | state->peerdn = dn_buf; |
| 1884 | |
| 1885 | return OK; |
| 1886 | #undef exim_gnutls_peer_err |
| 1887 | } |
| 1888 | |
| 1889 | |
| 1890 | |
| 1891 | |
| 1892 | /************************************************* |
| 1893 | * Verify peer certificate * |
| 1894 | *************************************************/ |
| 1895 | |
| 1896 | /* Called from both server and client code. |
| 1897 | *Should* be using a callback registered with |
| 1898 | gnutls_certificate_set_verify_function() to fail the handshake if we dislike |
| 1899 | the peer information, but that's too new for some OSes. |
| 1900 | |
| 1901 | Arguments: |
| 1902 | state exim_gnutls_state_st * |
| 1903 | errstr where to put an error message |
| 1904 | |
| 1905 | Returns: |
| 1906 | FALSE if the session should be rejected |
| 1907 | TRUE if the cert is okay or we just don't care |
| 1908 | */ |
| 1909 | |
| 1910 | static BOOL |
| 1911 | verify_certificate(exim_gnutls_state_st * state, uschar ** errstr) |
| 1912 | { |
| 1913 | int rc; |
| 1914 | uint verify; |
| 1915 | |
| 1916 | DEBUG(D_tls) debug_printf("TLS: checking peer certificate\n"); |
| 1917 | *errstr = NULL; |
| 1918 | rc = peer_status(state, errstr); |
| 1919 | |
| 1920 | if (state->verify_requirement == VERIFY_NONE) |
| 1921 | return TRUE; |
| 1922 | |
| 1923 | if (rc != OK || !state->peerdn) |
| 1924 | { |
| 1925 | verify = GNUTLS_CERT_INVALID; |
| 1926 | *errstr = US"certificate not supplied"; |
| 1927 | } |
| 1928 | else |
| 1929 | |
| 1930 | { |
| 1931 | #ifdef SUPPORT_DANE |
| 1932 | if (state->verify_requirement == VERIFY_DANE && state->host) |
| 1933 | { |
| 1934 | /* Using dane_verify_session_crt() would be easy, as it does it all for us |
| 1935 | including talking to a DNS resolver. But we want to do that bit ourselves |
| 1936 | as the testsuite intercepts and fakes its own DNS environment. */ |
| 1937 | |
| 1938 | dane_state_t s; |
| 1939 | dane_query_t r; |
| 1940 | uint lsize; |
| 1941 | const gnutls_datum_t * certlist = |
| 1942 | gnutls_certificate_get_peers(state->session, &lsize); |
| 1943 | int usage = tls_out.tlsa_usage; |
| 1944 | |
| 1945 | # ifdef GNUTLS_BROKEN_DANE_VALIDATION |
| 1946 | /* Split the TLSA records into two sets, TA and EE selectors. Run the |
| 1947 | dane-verification separately so that we know which selector verified; |
| 1948 | then we know whether to do name-verification (needed for TA but not EE). */ |
| 1949 | |
| 1950 | if (usage == ((1<<DANESSL_USAGE_DANE_TA) | (1<<DANESSL_USAGE_DANE_EE))) |
| 1951 | { /* a mixed-usage bundle */ |
| 1952 | int i, j, nrec; |
| 1953 | const char ** dd; |
| 1954 | int * ddl; |
| 1955 | |
| 1956 | for (nrec = 0; state->dane_data_len[nrec]; ) nrec++; |
| 1957 | nrec++; |
| 1958 | |
| 1959 | dd = store_get(nrec * sizeof(uschar *), FALSE); |
| 1960 | ddl = store_get(nrec * sizeof(int), FALSE); |
| 1961 | nrec--; |
| 1962 | |
| 1963 | if ((rc = dane_state_init(&s, 0))) |
| 1964 | goto tlsa_prob; |
| 1965 | |
| 1966 | for (usage = DANESSL_USAGE_DANE_EE; |
| 1967 | usage >= DANESSL_USAGE_DANE_TA; usage--) |
| 1968 | { /* take records with this usage */ |
| 1969 | for (j = i = 0; i < nrec; i++) |
| 1970 | if (state->dane_data[i][0] == usage) |
| 1971 | { |
| 1972 | dd[j] = state->dane_data[i]; |
| 1973 | ddl[j++] = state->dane_data_len[i]; |
| 1974 | } |
| 1975 | if (j) |
| 1976 | { |
| 1977 | dd[j] = NULL; |
| 1978 | ddl[j] = 0; |
| 1979 | |
| 1980 | if ((rc = dane_raw_tlsa(s, &r, (char * const *)dd, ddl, 1, 0))) |
| 1981 | goto tlsa_prob; |
| 1982 | |
| 1983 | if ((rc = dane_verify_crt_raw(s, certlist, lsize, |
| 1984 | gnutls_certificate_type_get(state->session), |
| 1985 | r, 0, |
| 1986 | usage == DANESSL_USAGE_DANE_EE |
| 1987 | ? DANE_VFLAG_ONLY_CHECK_EE_USAGE : 0, |
| 1988 | &verify))) |
| 1989 | { |
| 1990 | DEBUG(D_tls) |
| 1991 | debug_printf("TLSA record problem: %s\n", dane_strerror(rc)); |
| 1992 | } |
| 1993 | else if (verify == 0) /* verification passed */ |
| 1994 | { |
| 1995 | usage = 1 << usage; |
| 1996 | break; |
| 1997 | } |
| 1998 | } |
| 1999 | } |
| 2000 | |
| 2001 | if (rc) goto tlsa_prob; |
| 2002 | } |
| 2003 | else |
| 2004 | # endif |
| 2005 | { |
| 2006 | if ( (rc = dane_state_init(&s, 0)) |
| 2007 | || (rc = dane_raw_tlsa(s, &r, state->dane_data, state->dane_data_len, |
| 2008 | 1, 0)) |
| 2009 | || (rc = dane_verify_crt_raw(s, certlist, lsize, |
| 2010 | gnutls_certificate_type_get(state->session), |
| 2011 | r, 0, |
| 2012 | # ifdef GNUTLS_BROKEN_DANE_VALIDATION |
| 2013 | usage == (1 << DANESSL_USAGE_DANE_EE) |
| 2014 | ? DANE_VFLAG_ONLY_CHECK_EE_USAGE : 0, |
| 2015 | # else |
| 2016 | 0, |
| 2017 | # endif |
| 2018 | &verify)) |
| 2019 | ) |
| 2020 | goto tlsa_prob; |
| 2021 | } |
| 2022 | |
| 2023 | if (verify != 0) /* verification failed */ |
| 2024 | { |
| 2025 | gnutls_datum_t str; |
| 2026 | (void) dane_verification_status_print(verify, &str, 0); |
| 2027 | *errstr = US str.data; /* don't bother to free */ |
| 2028 | goto badcert; |
| 2029 | } |
| 2030 | |
| 2031 | # ifdef GNUTLS_BROKEN_DANE_VALIDATION |
| 2032 | /* If a TA-mode TLSA record was used for verification we must additionally |
| 2033 | verify the cert name (but not the CA chain). For EE-mode, skip it. */ |
| 2034 | |
| 2035 | if (usage & (1 << DANESSL_USAGE_DANE_EE)) |
| 2036 | # endif |
| 2037 | { |
| 2038 | state->peer_dane_verified = state->peer_cert_verified = TRUE; |
| 2039 | goto goodcert; |
| 2040 | } |
| 2041 | # ifdef GNUTLS_BROKEN_DANE_VALIDATION |
| 2042 | /* Assume that the name on the A-record is the one that should be matching |
| 2043 | the cert. An alternate view is that the domain part of the email address |
| 2044 | is also permissible. */ |
| 2045 | |
| 2046 | if (gnutls_x509_crt_check_hostname(state->tlsp->peercert, |
| 2047 | CS state->host->name)) |
| 2048 | { |
| 2049 | state->peer_dane_verified = state->peer_cert_verified = TRUE; |
| 2050 | goto goodcert; |
| 2051 | } |
| 2052 | # endif |
| 2053 | } |
| 2054 | #endif /*SUPPORT_DANE*/ |
| 2055 | |
| 2056 | rc = gnutls_certificate_verify_peers2(state->session, &verify); |
| 2057 | } |
| 2058 | |
| 2059 | /* Handle the result of verification. INVALID is set if any others are. */ |
| 2060 | |
| 2061 | if (rc < 0 || verify & (GNUTLS_CERT_INVALID|GNUTLS_CERT_REVOKED)) |
| 2062 | { |
| 2063 | state->peer_cert_verified = FALSE; |
| 2064 | if (!*errstr) |
| 2065 | { |
| 2066 | #ifdef GNUTLS_CERT_VFY_STATUS_PRINT |
| 2067 | DEBUG(D_tls) |
| 2068 | { |
| 2069 | gnutls_datum_t txt; |
| 2070 | |
| 2071 | if (gnutls_certificate_verification_status_print(verify, |
| 2072 | gnutls_certificate_type_get(state->session), &txt, 0) |
| 2073 | == GNUTLS_E_SUCCESS) |
| 2074 | { |
| 2075 | debug_printf("%s\n", txt.data); |
| 2076 | gnutls_free(txt.data); |
| 2077 | } |
| 2078 | } |
| 2079 | #endif |
| 2080 | *errstr = verify & GNUTLS_CERT_REVOKED |
| 2081 | ? US"certificate revoked" : US"certificate invalid"; |
| 2082 | } |
| 2083 | |
| 2084 | DEBUG(D_tls) |
| 2085 | debug_printf("TLS certificate verification failed (%s): peerdn=\"%s\"\n", |
| 2086 | *errstr, state->peerdn ? state->peerdn : US"<unset>"); |
| 2087 | |
| 2088 | if (state->verify_requirement >= VERIFY_REQUIRED) |
| 2089 | goto badcert; |
| 2090 | DEBUG(D_tls) |
| 2091 | debug_printf("TLS verify failure overridden (host in tls_try_verify_hosts)\n"); |
| 2092 | } |
| 2093 | |
| 2094 | else |
| 2095 | { |
| 2096 | /* Client side, check the server's certificate name versus the name on the |
| 2097 | A-record for the connection we made. What to do for server side - what name |
| 2098 | to use for client? We document that there is no such checking for server |
| 2099 | side. */ |
| 2100 | |
| 2101 | if ( state->exp_tls_verify_cert_hostnames |
| 2102 | && !gnutls_x509_crt_check_hostname(state->tlsp->peercert, |
| 2103 | CS state->exp_tls_verify_cert_hostnames) |
| 2104 | ) |
| 2105 | { |
| 2106 | DEBUG(D_tls) |
| 2107 | debug_printf("TLS certificate verification failed: cert name mismatch\n"); |
| 2108 | if (state->verify_requirement >= VERIFY_REQUIRED) |
| 2109 | goto badcert; |
| 2110 | return TRUE; |
| 2111 | } |
| 2112 | |
| 2113 | state->peer_cert_verified = TRUE; |
| 2114 | DEBUG(D_tls) debug_printf("TLS certificate verified: peerdn=\"%s\"\n", |
| 2115 | state->peerdn ? state->peerdn : US"<unset>"); |
| 2116 | } |
| 2117 | |
| 2118 | goodcert: |
| 2119 | state->tlsp->peerdn = state->peerdn; |
| 2120 | return TRUE; |
| 2121 | |
| 2122 | #ifdef SUPPORT_DANE |
| 2123 | tlsa_prob: |
| 2124 | *errstr = string_sprintf("TLSA record problem: %s", |
| 2125 | rc == DANE_E_REQUESTED_DATA_NOT_AVAILABLE ? "none usable" : dane_strerror(rc)); |
| 2126 | #endif |
| 2127 | |
| 2128 | badcert: |
| 2129 | gnutls_alert_send(state->session, GNUTLS_AL_FATAL, GNUTLS_A_BAD_CERTIFICATE); |
| 2130 | return FALSE; |
| 2131 | } |
| 2132 | |
| 2133 | |
| 2134 | |
| 2135 | |
| 2136 | /* ------------------------------------------------------------------------ */ |
| 2137 | /* Callbacks */ |
| 2138 | |
| 2139 | /* Logging function which can be registered with |
| 2140 | * gnutls_global_set_log_function() |
| 2141 | * gnutls_global_set_log_level() 0..9 |
| 2142 | */ |
| 2143 | #if EXIM_GNUTLS_LIBRARY_LOG_LEVEL >= 0 |
| 2144 | static void |
| 2145 | exim_gnutls_logger_cb(int level, const char *message) |
| 2146 | { |
| 2147 | size_t len = strlen(message); |
| 2148 | if (len < 1) |
| 2149 | { |
| 2150 | DEBUG(D_tls) debug_printf("GnuTLS<%d> empty debug message\n", level); |
| 2151 | return; |
| 2152 | } |
| 2153 | DEBUG(D_tls) debug_printf("GnuTLS<%d>: %s%s", level, message, |
| 2154 | message[len-1] == '\n' ? "" : "\n"); |
| 2155 | } |
| 2156 | #endif |
| 2157 | |
| 2158 | |
| 2159 | /* Called after client hello, should handle SNI work. |
| 2160 | This will always set tls_sni (state->received_sni) if available, |
| 2161 | and may trigger presenting different certificates, |
| 2162 | if state->trigger_sni_changes is TRUE. |
| 2163 | |
| 2164 | Should be registered with |
| 2165 | gnutls_handshake_set_post_client_hello_function() |
| 2166 | |
| 2167 | "This callback must return 0 on success or a gnutls error code to terminate the |
| 2168 | handshake.". |
| 2169 | |
| 2170 | For inability to get SNI information, we return 0. |
| 2171 | We only return non-zero if re-setup failed. |
| 2172 | Only used for server-side TLS. |
| 2173 | */ |
| 2174 | |
| 2175 | static int |
| 2176 | exim_sni_handling_cb(gnutls_session_t session) |
| 2177 | { |
| 2178 | char sni_name[MAX_HOST_LEN]; |
| 2179 | size_t data_len = MAX_HOST_LEN; |
| 2180 | exim_gnutls_state_st *state = &state_server; |
| 2181 | unsigned int sni_type; |
| 2182 | int rc, old_pool; |
| 2183 | uschar * dummy_errstr; |
| 2184 | |
| 2185 | rc = gnutls_server_name_get(session, sni_name, &data_len, &sni_type, 0); |
| 2186 | if (rc != GNUTLS_E_SUCCESS) |
| 2187 | { |
| 2188 | DEBUG(D_tls) |
| 2189 | if (rc == GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE) |
| 2190 | debug_printf("TLS: no SNI presented in handshake.\n"); |
| 2191 | else |
| 2192 | debug_printf("TLS failure: gnutls_server_name_get(): %s [%d]\n", |
| 2193 | gnutls_strerror(rc), rc); |
| 2194 | return 0; |
| 2195 | } |
| 2196 | |
| 2197 | if (sni_type != GNUTLS_NAME_DNS) |
| 2198 | { |
| 2199 | DEBUG(D_tls) debug_printf("TLS: ignoring SNI of unhandled type %u\n", sni_type); |
| 2200 | return 0; |
| 2201 | } |
| 2202 | |
| 2203 | /* We now have a UTF-8 string in sni_name */ |
| 2204 | old_pool = store_pool; |
| 2205 | store_pool = POOL_PERM; |
| 2206 | state->received_sni = string_copy_taint(US sni_name, TRUE); |
| 2207 | store_pool = old_pool; |
| 2208 | |
| 2209 | /* We set this one now so that variable expansions below will work */ |
| 2210 | state->tlsp->sni = state->received_sni; |
| 2211 | |
| 2212 | DEBUG(D_tls) debug_printf("Received TLS SNI \"%s\"%s\n", sni_name, |
| 2213 | state->trigger_sni_changes ? "" : " (unused for certificate selection)"); |
| 2214 | |
| 2215 | if (!state->trigger_sni_changes) |
| 2216 | return 0; |
| 2217 | |
| 2218 | if ((rc = tls_expand_session_files(state, &dummy_errstr)) != OK) |
| 2219 | { |
| 2220 | /* If the setup of certs/etc failed before handshake, TLS would not have |
| 2221 | been offered. The best we can do now is abort. */ |
| 2222 | return GNUTLS_E_APPLICATION_ERROR_MIN; |
| 2223 | } |
| 2224 | |
| 2225 | rc = tls_set_remaining_x509(state, &dummy_errstr); |
| 2226 | if (rc != OK) return GNUTLS_E_APPLICATION_ERROR_MIN; |
| 2227 | |
| 2228 | return 0; |
| 2229 | } |
| 2230 | |
| 2231 | |
| 2232 | |
| 2233 | #ifndef DISABLE_EVENT |
| 2234 | /* |
| 2235 | We use this callback to get observability and detail-level control |
| 2236 | for an exim TLS connection (either direction), raising a tls:cert event |
| 2237 | for each cert in the chain presented by the peer. Any event |
| 2238 | can deny verification. |
| 2239 | |
| 2240 | Return 0 for the handshake to continue or non-zero to terminate. |
| 2241 | */ |
| 2242 | |
| 2243 | static int |
| 2244 | verify_cb(gnutls_session_t session) |
| 2245 | { |
| 2246 | const gnutls_datum_t * cert_list; |
| 2247 | unsigned int cert_list_size = 0; |
| 2248 | gnutls_x509_crt_t crt; |
| 2249 | int rc; |
| 2250 | uschar * yield; |
| 2251 | exim_gnutls_state_st * state = gnutls_session_get_ptr(session); |
| 2252 | |
| 2253 | if ((cert_list = gnutls_certificate_get_peers(session, &cert_list_size))) |
| 2254 | while (cert_list_size--) |
| 2255 | { |
| 2256 | if ((rc = import_cert(&cert_list[cert_list_size], &crt)) != GNUTLS_E_SUCCESS) |
| 2257 | { |
| 2258 | DEBUG(D_tls) debug_printf("TLS: peer cert problem: depth %d: %s\n", |
| 2259 | cert_list_size, gnutls_strerror(rc)); |
| 2260 | break; |
| 2261 | } |
| 2262 | |
| 2263 | state->tlsp->peercert = crt; |
| 2264 | if ((yield = event_raise(state->event_action, |
| 2265 | US"tls:cert", string_sprintf("%d", cert_list_size)))) |
| 2266 | { |
| 2267 | log_write(0, LOG_MAIN, |
| 2268 | "SSL verify denied by event-action: depth=%d: %s", |
| 2269 | cert_list_size, yield); |
| 2270 | return 1; /* reject */ |
| 2271 | } |
| 2272 | state->tlsp->peercert = NULL; |
| 2273 | } |
| 2274 | |
| 2275 | return 0; |
| 2276 | } |
| 2277 | |
| 2278 | #endif |
| 2279 | |
| 2280 | |
| 2281 | static gstring * |
| 2282 | ddump(gnutls_datum_t * d) |
| 2283 | { |
| 2284 | gstring * g = string_get((d->size+1) * 2); |
| 2285 | uschar * s = d->data; |
| 2286 | for (unsigned i = d->size; i > 0; i--, s++) |
| 2287 | { |
| 2288 | g = string_catn(g, US "0123456789abcdef" + (*s >> 4), 1); |
| 2289 | g = string_catn(g, US "0123456789abcdef" + (*s & 0xf), 1); |
| 2290 | } |
| 2291 | return g; |
| 2292 | } |
| 2293 | |
| 2294 | static void |
| 2295 | post_handshake_debug(exim_gnutls_state_st * state) |
| 2296 | { |
| 2297 | #ifdef SUPPORT_GNUTLS_SESS_DESC |
| 2298 | debug_printf("%s\n", gnutls_session_get_desc(state->session)); |
| 2299 | #endif |
| 2300 | |
| 2301 | #ifdef SUPPORT_GNUTLS_KEYLOG |
| 2302 | # ifdef EXIM_HAVE_TLS1_3 |
| 2303 | if (gnutls_protocol_get_version(state->session) < GNUTLS_TLS1_3) |
| 2304 | # else |
| 2305 | if (TRUE) |
| 2306 | # endif |
| 2307 | { |
| 2308 | gnutls_datum_t c, s; |
| 2309 | gstring * gc, * gs; |
| 2310 | /* For TLS1.2 we only want the client random and the master secret */ |
| 2311 | gnutls_session_get_random(state->session, &c, &s); |
| 2312 | gnutls_session_get_master_secret(state->session, &s); |
| 2313 | gc = ddump(&c); |
| 2314 | gs = ddump(&s); |
| 2315 | debug_printf("CLIENT_RANDOM %.*s %.*s\n", (int)gc->ptr, gc->s, (int)gs->ptr, gs->s); |
| 2316 | } |
| 2317 | else |
| 2318 | debug_printf("To get keying info for TLS1.3 is hard:\n" |
| 2319 | " Set environment variable SSLKEYLOGFILE to a filename relative to the spool directory,\n" |
| 2320 | " and make sure it is writable by the Exim runtime user.\n" |
| 2321 | " Add SSLKEYLOGFILE to keep_environment in the exim config.\n" |
| 2322 | " Start Exim as root.\n" |
| 2323 | " If using sudo, add SSLKEYLOGFILE to env_keep in /etc/sudoers\n" |
| 2324 | " (works for TLS1.2 also, and saves cut-paste into file).\n" |
| 2325 | " Trying to use add_environment for this will not work\n"); |
| 2326 | #endif |
| 2327 | } |
| 2328 | |
| 2329 | |
| 2330 | #ifdef EXPERIMENTAL_TLS_RESUME |
| 2331 | static int |
| 2332 | tls_server_ticket_cb(gnutls_session_t sess, u_int htype, unsigned when, |
| 2333 | unsigned incoming, const gnutls_datum_t * msg) |
| 2334 | { |
| 2335 | DEBUG(D_tls) debug_printf("newticket cb\n"); |
| 2336 | tls_in.resumption |= RESUME_CLIENT_REQUESTED; |
| 2337 | return 0; |
| 2338 | } |
| 2339 | |
| 2340 | static void |
| 2341 | tls_server_resume_prehandshake(exim_gnutls_state_st * state) |
| 2342 | { |
| 2343 | /* Should the server offer session resumption? */ |
| 2344 | tls_in.resumption = RESUME_SUPPORTED; |
| 2345 | if (verify_check_host(&tls_resumption_hosts) == OK) |
| 2346 | { |
| 2347 | int rc; |
| 2348 | /* GnuTLS appears to not do ticket overlap, but does emit a fresh ticket when |
| 2349 | an offered resumption is unacceptable. We lose one resumption per ticket |
| 2350 | lifetime, and sessions cannot be indefinitely re-used. There seems to be no |
| 2351 | way (3.6.7) of changing the default number of 2 TLS1.3 tickets issued, but at |
| 2352 | least they go out in a single packet. */ |
| 2353 | |
| 2354 | if (!(rc = gnutls_session_ticket_enable_server(state->session, |
| 2355 | &server_sessticket_key))) |
| 2356 | tls_in.resumption |= RESUME_SERVER_TICKET; |
| 2357 | else |
| 2358 | DEBUG(D_tls) |
| 2359 | debug_printf("enabling session tickets: %s\n", US gnutls_strerror(rc)); |
| 2360 | |
| 2361 | /* Try to tell if we see a ticket request */ |
| 2362 | gnutls_handshake_set_hook_function(state->session, |
| 2363 | GNUTLS_HANDSHAKE_ANY, GNUTLS_HOOK_POST, tls_server_hook_cb); |
| 2364 | } |
| 2365 | } |
| 2366 | |
| 2367 | static void |
| 2368 | tls_server_resume_posthandshake(exim_gnutls_state_st * state) |
| 2369 | { |
| 2370 | if (gnutls_session_resumption_requested(state->session)) |
| 2371 | { |
| 2372 | /* This tells us the client sent a full ticket. We use a |
| 2373 | callback on session-ticket request, elsewhere, to tell |
| 2374 | if a client asked for a ticket. */ |
| 2375 | |
| 2376 | tls_in.resumption |= RESUME_CLIENT_SUGGESTED; |
| 2377 | DEBUG(D_tls) debug_printf("client requested resumption\n"); |
| 2378 | } |
| 2379 | if (gnutls_session_is_resumed(state->session)) |
| 2380 | { |
| 2381 | tls_in.resumption |= RESUME_USED; |
| 2382 | DEBUG(D_tls) debug_printf("Session resumed\n"); |
| 2383 | } |
| 2384 | } |
| 2385 | #endif |
| 2386 | /* ------------------------------------------------------------------------ */ |
| 2387 | /* Exported functions */ |
| 2388 | |
| 2389 | |
| 2390 | |
| 2391 | |
| 2392 | /************************************************* |
| 2393 | * Start a TLS session in a server * |
| 2394 | *************************************************/ |
| 2395 | |
| 2396 | /* This is called when Exim is running as a server, after having received |
| 2397 | the STARTTLS command. It must respond to that command, and then negotiate |
| 2398 | a TLS session. |
| 2399 | |
| 2400 | Arguments: |
| 2401 | require_ciphers list of allowed ciphers or NULL |
| 2402 | errstr pointer to error string |
| 2403 | |
| 2404 | Returns: OK on success |
| 2405 | DEFER for errors before the start of the negotiation |
| 2406 | FAIL for errors during the negotiation; the server can't |
| 2407 | continue running. |
| 2408 | */ |
| 2409 | |
| 2410 | int |
| 2411 | tls_server_start(const uschar * require_ciphers, uschar ** errstr) |
| 2412 | { |
| 2413 | int rc; |
| 2414 | exim_gnutls_state_st * state = NULL; |
| 2415 | |
| 2416 | /* Check for previous activation */ |
| 2417 | if (tls_in.active.sock >= 0) |
| 2418 | { |
| 2419 | tls_error(US"STARTTLS received after TLS started", US "", NULL, errstr); |
| 2420 | smtp_printf("554 Already in TLS\r\n", FALSE); |
| 2421 | return FAIL; |
| 2422 | } |
| 2423 | |
| 2424 | /* Initialize the library. If it fails, it will already have logged the error |
| 2425 | and sent an SMTP response. */ |
| 2426 | |
| 2427 | DEBUG(D_tls) debug_printf("initialising GnuTLS as a server\n"); |
| 2428 | |
| 2429 | { |
| 2430 | #ifdef MEASURE_TIMING |
| 2431 | struct timeval t0; |
| 2432 | gettimeofday(&t0, NULL); |
| 2433 | #endif |
| 2434 | |
| 2435 | if ((rc = tls_init(NULL, tls_certificate, tls_privatekey, |
| 2436 | NULL, tls_verify_certificates, tls_crl, |
| 2437 | require_ciphers, &state, &tls_in, errstr)) != OK) return rc; |
| 2438 | |
| 2439 | #ifdef MEASURE_TIMING |
| 2440 | report_time_since(&t0, US"server tls_init (delta)"); |
| 2441 | #endif |
| 2442 | } |
| 2443 | |
| 2444 | #ifdef EXPERIMENTAL_TLS_RESUME |
| 2445 | tls_server_resume_prehandshake(state); |
| 2446 | #endif |
| 2447 | |
| 2448 | /* If this is a host for which certificate verification is mandatory or |
| 2449 | optional, set up appropriately. */ |
| 2450 | |
| 2451 | if (verify_check_host(&tls_verify_hosts) == OK) |
| 2452 | { |
| 2453 | DEBUG(D_tls) |
| 2454 | debug_printf("TLS: a client certificate will be required.\n"); |
| 2455 | state->verify_requirement = VERIFY_REQUIRED; |
| 2456 | gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_REQUIRE); |
| 2457 | } |
| 2458 | else if (verify_check_host(&tls_try_verify_hosts) == OK) |
| 2459 | { |
| 2460 | DEBUG(D_tls) |
| 2461 | debug_printf("TLS: a client certificate will be requested but not required.\n"); |
| 2462 | state->verify_requirement = VERIFY_OPTIONAL; |
| 2463 | gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_REQUEST); |
| 2464 | } |
| 2465 | else |
| 2466 | { |
| 2467 | DEBUG(D_tls) |
| 2468 | debug_printf("TLS: a client certificate will not be requested.\n"); |
| 2469 | state->verify_requirement = VERIFY_NONE; |
| 2470 | gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_IGNORE); |
| 2471 | } |
| 2472 | |
| 2473 | #ifndef DISABLE_EVENT |
| 2474 | if (event_action) |
| 2475 | { |
| 2476 | state->event_action = event_action; |
| 2477 | gnutls_session_set_ptr(state->session, state); |
| 2478 | gnutls_certificate_set_verify_function(state->x509_cred, verify_cb); |
| 2479 | } |
| 2480 | #endif |
| 2481 | |
| 2482 | /* Register SNI handling; always, even if not in tls_certificate, so that the |
| 2483 | expansion variable $tls_sni is always available. */ |
| 2484 | |
| 2485 | gnutls_handshake_set_post_client_hello_function(state->session, |
| 2486 | exim_sni_handling_cb); |
| 2487 | |
| 2488 | /* Set context and tell client to go ahead, except in the case of TLS startup |
| 2489 | on connection, where outputting anything now upsets the clients and tends to |
| 2490 | make them disconnect. We need to have an explicit fflush() here, to force out |
| 2491 | the response. Other smtp_printf() calls do not need it, because in non-TLS |
| 2492 | mode, the fflush() happens when smtp_getc() is called. */ |
| 2493 | |
| 2494 | if (!state->tlsp->on_connect) |
| 2495 | { |
| 2496 | smtp_printf("220 TLS go ahead\r\n", FALSE); |
| 2497 | fflush(smtp_out); |
| 2498 | } |
| 2499 | |
| 2500 | /* Now negotiate the TLS session. We put our own timer on it, since it seems |
| 2501 | that the GnuTLS library doesn't. |
| 2502 | From 3.1.0 there is gnutls_handshake_set_timeout() - but it requires you |
| 2503 | to set (and clear down afterwards) up a pull-timeout callback function that does |
| 2504 | a select, so we're no better off unless avoiding signals becomes an issue. */ |
| 2505 | |
| 2506 | gnutls_transport_set_ptr2(state->session, |
| 2507 | (gnutls_transport_ptr_t)(long) fileno(smtp_in), |
| 2508 | (gnutls_transport_ptr_t)(long) fileno(smtp_out)); |
| 2509 | state->fd_in = fileno(smtp_in); |
| 2510 | state->fd_out = fileno(smtp_out); |
| 2511 | |
| 2512 | sigalrm_seen = FALSE; |
| 2513 | if (smtp_receive_timeout > 0) ALARM(smtp_receive_timeout); |
| 2514 | do |
| 2515 | rc = gnutls_handshake(state->session); |
| 2516 | while (rc == GNUTLS_E_AGAIN || rc == GNUTLS_E_INTERRUPTED && !sigalrm_seen); |
| 2517 | ALARM_CLR(0); |
| 2518 | |
| 2519 | if (rc != GNUTLS_E_SUCCESS) |
| 2520 | { |
| 2521 | /* It seems that, except in the case of a timeout, we have to close the |
| 2522 | connection right here; otherwise if the other end is running OpenSSL it hangs |
| 2523 | until the server times out. */ |
| 2524 | |
| 2525 | if (sigalrm_seen) |
| 2526 | { |
| 2527 | tls_error(US"gnutls_handshake", US"timed out", NULL, errstr); |
| 2528 | gnutls_db_remove_session(state->session); |
| 2529 | } |
| 2530 | else |
| 2531 | { |
| 2532 | tls_error_gnu(US"gnutls_handshake", rc, NULL, errstr); |
| 2533 | (void) gnutls_alert_send_appropriate(state->session, rc); |
| 2534 | gnutls_deinit(state->session); |
| 2535 | gnutls_certificate_free_credentials(state->x509_cred); |
| 2536 | millisleep(500); |
| 2537 | shutdown(state->fd_out, SHUT_WR); |
| 2538 | for (int i = 1024; fgetc(smtp_in) != EOF && i > 0; ) i--; /* drain skt */ |
| 2539 | (void)fclose(smtp_out); |
| 2540 | (void)fclose(smtp_in); |
| 2541 | smtp_out = smtp_in = NULL; |
| 2542 | } |
| 2543 | |
| 2544 | return FAIL; |
| 2545 | } |
| 2546 | |
| 2547 | #ifdef GNUTLS_SFLAGS_EXT_MASTER_SECRET |
| 2548 | if (gnutls_session_get_flags(state->session) & GNUTLS_SFLAGS_EXT_MASTER_SECRET) |
| 2549 | tls_in.ext_master_secret = TRUE; |
| 2550 | #endif |
| 2551 | |
| 2552 | #ifdef EXPERIMENTAL_TLS_RESUME |
| 2553 | tls_server_resume_posthandshake(state); |
| 2554 | #endif |
| 2555 | |
| 2556 | DEBUG(D_tls) post_handshake_debug(state); |
| 2557 | |
| 2558 | /* Verify after the fact */ |
| 2559 | |
| 2560 | if (!verify_certificate(state, errstr)) |
| 2561 | { |
| 2562 | if (state->verify_requirement != VERIFY_OPTIONAL) |
| 2563 | { |
| 2564 | (void) tls_error(US"certificate verification failed", *errstr, NULL, errstr); |
| 2565 | return FAIL; |
| 2566 | } |
| 2567 | DEBUG(D_tls) |
| 2568 | debug_printf("TLS: continuing on only because verification was optional, after: %s\n", |
| 2569 | *errstr); |
| 2570 | } |
| 2571 | |
| 2572 | /* Sets various Exim expansion variables; always safe within server */ |
| 2573 | |
| 2574 | extract_exim_vars_from_tls_state(state); |
| 2575 | |
| 2576 | /* TLS has been set up. Adjust the input functions to read via TLS, |
| 2577 | and initialize appropriately. */ |
| 2578 | |
| 2579 | state->xfer_buffer = store_malloc(ssl_xfer_buffer_size); |
| 2580 | |
| 2581 | receive_getc = tls_getc; |
| 2582 | receive_getbuf = tls_getbuf; |
| 2583 | receive_get_cache = tls_get_cache; |
| 2584 | receive_ungetc = tls_ungetc; |
| 2585 | receive_feof = tls_feof; |
| 2586 | receive_ferror = tls_ferror; |
| 2587 | receive_smtp_buffered = tls_smtp_buffered; |
| 2588 | |
| 2589 | return OK; |
| 2590 | } |
| 2591 | |
| 2592 | |
| 2593 | |
| 2594 | |
| 2595 | static void |
| 2596 | tls_client_setup_hostname_checks(host_item * host, exim_gnutls_state_st * state, |
| 2597 | smtp_transport_options_block * ob) |
| 2598 | { |
| 2599 | if (verify_check_given_host(CUSS &ob->tls_verify_cert_hostnames, host) == OK) |
| 2600 | { |
| 2601 | state->exp_tls_verify_cert_hostnames = |
| 2602 | #ifdef SUPPORT_I18N |
| 2603 | string_domain_utf8_to_alabel(host->name, NULL); |
| 2604 | #else |
| 2605 | host->name; |
| 2606 | #endif |
| 2607 | DEBUG(D_tls) |
| 2608 | debug_printf("TLS: server cert verification includes hostname: \"%s\".\n", |
| 2609 | state->exp_tls_verify_cert_hostnames); |
| 2610 | } |
| 2611 | } |
| 2612 | |
| 2613 | |
| 2614 | |
| 2615 | |
| 2616 | #ifdef SUPPORT_DANE |
| 2617 | /* Given our list of RRs from the TLSA lookup, build a lookup block in |
| 2618 | GnuTLS-DANE's preferred format. Hang it on the state str for later |
| 2619 | use in DANE verification. |
| 2620 | |
| 2621 | We point at the dnsa data not copy it, so it must remain valid until |
| 2622 | after verification is done.*/ |
| 2623 | |
| 2624 | static BOOL |
| 2625 | dane_tlsa_load(exim_gnutls_state_st * state, dns_answer * dnsa) |
| 2626 | { |
| 2627 | dns_scan dnss; |
| 2628 | int i; |
| 2629 | const char ** dane_data; |
| 2630 | int * dane_data_len; |
| 2631 | |
| 2632 | i = 1; |
| 2633 | for (dns_record * rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS); rr; |
| 2634 | rr = dns_next_rr(dnsa, &dnss, RESET_NEXT) |
| 2635 | ) if (rr->type == T_TLSA) i++; |
| 2636 | |
| 2637 | dane_data = store_get(i * sizeof(uschar *), FALSE); |
| 2638 | dane_data_len = store_get(i * sizeof(int), FALSE); |
| 2639 | |
| 2640 | i = 0; |
| 2641 | for (dns_record * rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS); rr; |
| 2642 | rr = dns_next_rr(dnsa, &dnss, RESET_NEXT) |
| 2643 | ) if (rr->type == T_TLSA && rr->size > 3) |
| 2644 | { |
| 2645 | const uschar * p = rr->data; |
| 2646 | /*XXX need somehow to mark rr and its data as tainted. Doues this mean copying it? */ |
| 2647 | uint8_t usage = p[0], sel = p[1], type = p[2]; |
| 2648 | |
| 2649 | DEBUG(D_tls) |
| 2650 | debug_printf("TLSA: %d %d %d size %d\n", usage, sel, type, rr->size); |
| 2651 | |
| 2652 | if ( (usage != DANESSL_USAGE_DANE_TA && usage != DANESSL_USAGE_DANE_EE) |
| 2653 | || (sel != 0 && sel != 1) |
| 2654 | ) |
| 2655 | continue; |
| 2656 | switch(type) |
| 2657 | { |
| 2658 | case 0: /* Full: cannot check at present */ |
| 2659 | break; |
| 2660 | case 1: if (rr->size != 3 + 256/8) continue; /* sha2-256 */ |
| 2661 | break; |
| 2662 | case 2: if (rr->size != 3 + 512/8) continue; /* sha2-512 */ |
| 2663 | break; |
| 2664 | default: continue; |
| 2665 | } |
| 2666 | |
| 2667 | tls_out.tlsa_usage |= 1<<usage; |
| 2668 | dane_data[i] = CS p; |
| 2669 | dane_data_len[i++] = rr->size; |
| 2670 | } |
| 2671 | |
| 2672 | if (!i) return FALSE; |
| 2673 | |
| 2674 | dane_data[i] = NULL; |
| 2675 | dane_data_len[i] = 0; |
| 2676 | |
| 2677 | state->dane_data = (char * const *)dane_data; |
| 2678 | state->dane_data_len = dane_data_len; |
| 2679 | return TRUE; |
| 2680 | } |
| 2681 | #endif |
| 2682 | |
| 2683 | |
| 2684 | |
| 2685 | #ifdef EXPERIMENTAL_TLS_RESUME |
| 2686 | /* On the client, get any stashed session for the given IP from hints db |
| 2687 | and apply it to the ssl-connection for attempted resumption. Although |
| 2688 | there is a gnutls_session_ticket_enable_client() interface it is |
| 2689 | documented as unnecessary (as of 3.6.7) as "session tickets are emabled |
| 2690 | by deafult". There seems to be no way to disable them, so even hosts not |
| 2691 | enabled by the transport option will be sent a ticket request. We will |
| 2692 | however avoid storing and retrieving session information. */ |
| 2693 | |
| 2694 | static void |
| 2695 | tls_retrieve_session(tls_support * tlsp, gnutls_session_t session, |
| 2696 | host_item * host, smtp_transport_options_block * ob) |
| 2697 | { |
| 2698 | tlsp->resumption = RESUME_SUPPORTED; |
| 2699 | if (verify_check_given_host(CUSS &ob->tls_resumption_hosts, host) == OK) |
| 2700 | { |
| 2701 | dbdata_tls_session * dt; |
| 2702 | int len, rc; |
| 2703 | open_db dbblock, * dbm_file; |
| 2704 | |
| 2705 | DEBUG(D_tls) |
| 2706 | debug_printf("check for resumable session for %s\n", host->address); |
| 2707 | tlsp->host_resumable = TRUE; |
| 2708 | tlsp->resumption |= RESUME_CLIENT_REQUESTED; |
| 2709 | if ((dbm_file = dbfn_open(US"tls", O_RDONLY, &dbblock, FALSE, FALSE))) |
| 2710 | { |
| 2711 | /* Key for the db is the IP. We'd like to filter the retrieved session |
| 2712 | for ticket advisory expiry, but 3.6.1 seems to give no access to that */ |
| 2713 | |
| 2714 | if ((dt = dbfn_read_with_length(dbm_file, host->address, &len))) |
| 2715 | if (!(rc = gnutls_session_set_data(session, |
| 2716 | CUS dt->session, (size_t)len - sizeof(dbdata_tls_session)))) |
| 2717 | { |
| 2718 | DEBUG(D_tls) debug_printf("good session\n"); |
| 2719 | tlsp->resumption |= RESUME_CLIENT_SUGGESTED; |
| 2720 | } |
| 2721 | else DEBUG(D_tls) debug_printf("setting session resumption data: %s\n", |
| 2722 | US gnutls_strerror(rc)); |
| 2723 | dbfn_close(dbm_file); |
| 2724 | } |
| 2725 | } |
| 2726 | } |
| 2727 | |
| 2728 | |
| 2729 | static void |
| 2730 | tls_save_session(tls_support * tlsp, gnutls_session_t session, const host_item * host) |
| 2731 | { |
| 2732 | /* TLS 1.2 - we get both the callback and the direct posthandshake call, |
| 2733 | but this flag is not set until the second. TLS 1.3 it's the other way about. |
| 2734 | Keep both calls as the session data cannot be extracted before handshake |
| 2735 | completes. */ |
| 2736 | |
| 2737 | if (gnutls_session_get_flags(session) & GNUTLS_SFLAGS_SESSION_TICKET) |
| 2738 | { |
| 2739 | gnutls_datum_t tkt; |
| 2740 | int rc; |
| 2741 | |
| 2742 | DEBUG(D_tls) debug_printf("server offered session ticket\n"); |
| 2743 | tlsp->ticket_received = TRUE; |
| 2744 | tlsp->resumption |= RESUME_SERVER_TICKET; |
| 2745 | |
| 2746 | if (tlsp->host_resumable) |
| 2747 | if (!(rc = gnutls_session_get_data2(session, &tkt))) |
| 2748 | { |
| 2749 | open_db dbblock, * dbm_file; |
| 2750 | int dlen = sizeof(dbdata_tls_session) + tkt.size; |
| 2751 | dbdata_tls_session * dt = store_get(dlen, TRUE); |
| 2752 | |
| 2753 | DEBUG(D_tls) debug_printf("session data size %u\n", (unsigned)tkt.size); |
| 2754 | memcpy(dt->session, tkt.data, tkt.size); |
| 2755 | gnutls_free(tkt.data); |
| 2756 | |
| 2757 | if ((dbm_file = dbfn_open(US"tls", O_RDWR, &dbblock, FALSE, FALSE))) |
| 2758 | { |
| 2759 | /* key for the db is the IP */ |
| 2760 | dbfn_delete(dbm_file, host->address); |
| 2761 | dbfn_write(dbm_file, host->address, dt, dlen); |
| 2762 | dbfn_close(dbm_file); |
| 2763 | |
| 2764 | DEBUG(D_tls) |
| 2765 | debug_printf("wrote session db (len %u)\n", (unsigned)dlen); |
| 2766 | } |
| 2767 | } |
| 2768 | else DEBUG(D_tls) |
| 2769 | debug_printf("extract session data: %s\n", US gnutls_strerror(rc)); |
| 2770 | } |
| 2771 | } |
| 2772 | |
| 2773 | |
| 2774 | /* With a TLS1.3 session, the ticket(s) are not seen until |
| 2775 | the first data read is attempted. And there's often two of them. |
| 2776 | Pick them up with this callback. We are also called for 1.2 |
| 2777 | but we do nothing. |
| 2778 | */ |
| 2779 | static int |
| 2780 | tls_client_ticket_cb(gnutls_session_t sess, u_int htype, unsigned when, |
| 2781 | unsigned incoming, const gnutls_datum_t * msg) |
| 2782 | { |
| 2783 | exim_gnutls_state_st * state = gnutls_session_get_ptr(sess); |
| 2784 | tls_support * tlsp = state->tlsp; |
| 2785 | |
| 2786 | DEBUG(D_tls) debug_printf("newticket cb\n"); |
| 2787 | |
| 2788 | if (!tlsp->ticket_received) |
| 2789 | tls_save_session(tlsp, sess, state->host); |
| 2790 | return 0; |
| 2791 | } |
| 2792 | |
| 2793 | |
| 2794 | static void |
| 2795 | tls_client_resume_prehandshake(exim_gnutls_state_st * state, |
| 2796 | tls_support * tlsp, host_item * host, |
| 2797 | smtp_transport_options_block * ob) |
| 2798 | { |
| 2799 | gnutls_session_set_ptr(state->session, state); |
| 2800 | gnutls_handshake_set_hook_function(state->session, |
| 2801 | GNUTLS_HANDSHAKE_NEW_SESSION_TICKET, GNUTLS_HOOK_POST, tls_client_ticket_cb); |
| 2802 | |
| 2803 | tls_retrieve_session(tlsp, state->session, host, ob); |
| 2804 | } |
| 2805 | |
| 2806 | static void |
| 2807 | tls_client_resume_posthandshake(exim_gnutls_state_st * state, |
| 2808 | tls_support * tlsp, host_item * host) |
| 2809 | { |
| 2810 | if (gnutls_session_is_resumed(state->session)) |
| 2811 | { |
| 2812 | DEBUG(D_tls) debug_printf("Session resumed\n"); |
| 2813 | tlsp->resumption |= RESUME_USED; |
| 2814 | } |
| 2815 | |
| 2816 | tls_save_session(tlsp, state->session, host); |
| 2817 | } |
| 2818 | #endif /* EXPERIMENTAL_TLS_RESUME */ |
| 2819 | |
| 2820 | |
| 2821 | /************************************************* |
| 2822 | * Start a TLS session in a client * |
| 2823 | *************************************************/ |
| 2824 | |
| 2825 | /* Called from the smtp transport after STARTTLS has been accepted. |
| 2826 | |
| 2827 | Arguments: |
| 2828 | cctx connection context |
| 2829 | conn_args connection details |
| 2830 | cookie datum for randomness (not used) |
| 2831 | tlsp record details of channel configuration here; must be non-NULL |
| 2832 | errstr error string pointer |
| 2833 | |
| 2834 | Returns: TRUE for success with TLS session context set in smtp context, |
| 2835 | FALSE on error |
| 2836 | */ |
| 2837 | |
| 2838 | BOOL |
| 2839 | tls_client_start(client_conn_ctx * cctx, smtp_connect_args * conn_args, |
| 2840 | void * cookie ARG_UNUSED, |
| 2841 | tls_support * tlsp, uschar ** errstr) |
| 2842 | { |
| 2843 | host_item * host = conn_args->host; /* for msgs and option-tests */ |
| 2844 | transport_instance * tb = conn_args->tblock; /* always smtp or NULL */ |
| 2845 | smtp_transport_options_block * ob = tb |
| 2846 | ? (smtp_transport_options_block *)tb->options_block |
| 2847 | : &smtp_transport_option_defaults; |
| 2848 | int rc; |
| 2849 | exim_gnutls_state_st * state = NULL; |
| 2850 | uschar * cipher_list = NULL; |
| 2851 | |
| 2852 | #ifndef DISABLE_OCSP |
| 2853 | BOOL require_ocsp = |
| 2854 | verify_check_given_host(CUSS &ob->hosts_require_ocsp, host) == OK; |
| 2855 | BOOL request_ocsp = require_ocsp ? TRUE |
| 2856 | : verify_check_given_host(CUSS &ob->hosts_request_ocsp, host) == OK; |
| 2857 | #endif |
| 2858 | |
| 2859 | DEBUG(D_tls) debug_printf("initialising GnuTLS as a client on fd %d\n", cctx->sock); |
| 2860 | |
| 2861 | #ifdef SUPPORT_DANE |
| 2862 | /* If dane is flagged, have either request or require dane for this host, and |
| 2863 | a TLSA record found. Therefore, dane verify required. Which implies cert must |
| 2864 | be requested and supplied, dane verify must pass, and cert verify irrelevant |
| 2865 | (incl. hostnames), and (caller handled) require_tls */ |
| 2866 | |
| 2867 | if (conn_args->dane && ob->dane_require_tls_ciphers) |
| 2868 | { |
| 2869 | /* not using expand_check_tlsvar because not yet in state */ |
| 2870 | if (!expand_check(ob->dane_require_tls_ciphers, US"dane_require_tls_ciphers", |
| 2871 | &cipher_list, errstr)) |
| 2872 | return FALSE; |
| 2873 | cipher_list = cipher_list && *cipher_list |
| 2874 | ? ob->dane_require_tls_ciphers : ob->tls_require_ciphers; |
| 2875 | } |
| 2876 | #endif |
| 2877 | |
| 2878 | if (!cipher_list) |
| 2879 | cipher_list = ob->tls_require_ciphers; |
| 2880 | |
| 2881 | { |
| 2882 | #ifdef MEASURE_TIMING |
| 2883 | struct timeval t0; |
| 2884 | gettimeofday(&t0, NULL); |
| 2885 | #endif |
| 2886 | |
| 2887 | if (tls_init(host, ob->tls_certificate, ob->tls_privatekey, |
| 2888 | ob->tls_sni, ob->tls_verify_certificates, ob->tls_crl, |
| 2889 | cipher_list, &state, tlsp, errstr) != OK) |
| 2890 | return FALSE; |
| 2891 | |
| 2892 | #ifdef MEASURE_TIMING |
| 2893 | report_time_since(&t0, US"client tls_init (delta)"); |
| 2894 | #endif |
| 2895 | } |
| 2896 | |
| 2897 | { |
| 2898 | int dh_min_bits = ob->tls_dh_min_bits; |
| 2899 | if (dh_min_bits < EXIM_CLIENT_DH_MIN_MIN_BITS) |
| 2900 | { |
| 2901 | DEBUG(D_tls) |
| 2902 | debug_printf("WARNING: tls_dh_min_bits far too low," |
| 2903 | " clamping %d up to %d\n", |
| 2904 | dh_min_bits, EXIM_CLIENT_DH_MIN_MIN_BITS); |
| 2905 | dh_min_bits = EXIM_CLIENT_DH_MIN_MIN_BITS; |
| 2906 | } |
| 2907 | |
| 2908 | DEBUG(D_tls) debug_printf("Setting D-H prime minimum" |
| 2909 | " acceptable bits to %d\n", |
| 2910 | dh_min_bits); |
| 2911 | gnutls_dh_set_prime_bits(state->session, dh_min_bits); |
| 2912 | } |
| 2913 | |
| 2914 | /* Stick to the old behaviour for compatibility if tls_verify_certificates is |
| 2915 | set but both tls_verify_hosts and tls_try_verify_hosts are unset. Check only |
| 2916 | the specified host patterns if one of them is defined */ |
| 2917 | |
| 2918 | #ifdef SUPPORT_DANE |
| 2919 | if (conn_args->dane && dane_tlsa_load(state, &conn_args->tlsa_dnsa)) |
| 2920 | { |
| 2921 | DEBUG(D_tls) |
| 2922 | debug_printf("TLS: server certificate DANE required.\n"); |
| 2923 | state->verify_requirement = VERIFY_DANE; |
| 2924 | gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_REQUIRE); |
| 2925 | } |
| 2926 | else |
| 2927 | #endif |
| 2928 | if ( ( state->exp_tls_verify_certificates |
| 2929 | && !ob->tls_verify_hosts |
| 2930 | && (!ob->tls_try_verify_hosts || !*ob->tls_try_verify_hosts) |
| 2931 | ) |
| 2932 | || verify_check_given_host(CUSS &ob->tls_verify_hosts, host) == OK |
| 2933 | ) |
| 2934 | { |
| 2935 | tls_client_setup_hostname_checks(host, state, ob); |
| 2936 | DEBUG(D_tls) |
| 2937 | debug_printf("TLS: server certificate verification required.\n"); |
| 2938 | state->verify_requirement = VERIFY_REQUIRED; |
| 2939 | gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_REQUIRE); |
| 2940 | } |
| 2941 | else if (verify_check_given_host(CUSS &ob->tls_try_verify_hosts, host) == OK) |
| 2942 | { |
| 2943 | tls_client_setup_hostname_checks(host, state, ob); |
| 2944 | DEBUG(D_tls) |
| 2945 | debug_printf("TLS: server certificate verification optional.\n"); |
| 2946 | state->verify_requirement = VERIFY_OPTIONAL; |
| 2947 | gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_REQUEST); |
| 2948 | } |
| 2949 | else |
| 2950 | { |
| 2951 | DEBUG(D_tls) |
| 2952 | debug_printf("TLS: server certificate verification not required.\n"); |
| 2953 | state->verify_requirement = VERIFY_NONE; |
| 2954 | gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_IGNORE); |
| 2955 | } |
| 2956 | |
| 2957 | #ifndef DISABLE_OCSP |
| 2958 | /* supported since GnuTLS 3.1.3 */ |
| 2959 | if (request_ocsp) |
| 2960 | { |
| 2961 | DEBUG(D_tls) debug_printf("TLS: will request OCSP stapling\n"); |
| 2962 | if ((rc = gnutls_ocsp_status_request_enable_client(state->session, |
| 2963 | NULL, 0, NULL)) != OK) |
| 2964 | { |
| 2965 | tls_error_gnu(US"cert-status-req", rc, state->host, errstr); |
| 2966 | return FALSE; |
| 2967 | } |
| 2968 | tlsp->ocsp = OCSP_NOT_RESP; |
| 2969 | } |
| 2970 | #endif |
| 2971 | |
| 2972 | #ifdef EXPERIMENTAL_TLS_RESUME |
| 2973 | tls_client_resume_prehandshake(state, tlsp, host, ob); |
| 2974 | #endif |
| 2975 | |
| 2976 | #ifndef DISABLE_EVENT |
| 2977 | if (tb && tb->event_action) |
| 2978 | { |
| 2979 | state->event_action = tb->event_action; |
| 2980 | gnutls_session_set_ptr(state->session, state); |
| 2981 | gnutls_certificate_set_verify_function(state->x509_cred, verify_cb); |
| 2982 | } |
| 2983 | #endif |
| 2984 | |
| 2985 | gnutls_transport_set_ptr(state->session, (gnutls_transport_ptr_t)(long) cctx->sock); |
| 2986 | state->fd_in = cctx->sock; |
| 2987 | state->fd_out = cctx->sock; |
| 2988 | |
| 2989 | DEBUG(D_tls) debug_printf("about to gnutls_handshake\n"); |
| 2990 | /* There doesn't seem to be a built-in timeout on connection. */ |
| 2991 | |
| 2992 | sigalrm_seen = FALSE; |
| 2993 | ALARM(ob->command_timeout); |
| 2994 | do |
| 2995 | rc = gnutls_handshake(state->session); |
| 2996 | while (rc == GNUTLS_E_AGAIN || rc == GNUTLS_E_INTERRUPTED && !sigalrm_seen); |
| 2997 | ALARM_CLR(0); |
| 2998 | |
| 2999 | if (rc != GNUTLS_E_SUCCESS) |
| 3000 | { |
| 3001 | if (sigalrm_seen) |
| 3002 | { |
| 3003 | gnutls_alert_send(state->session, GNUTLS_AL_FATAL, GNUTLS_A_USER_CANCELED); |
| 3004 | tls_error(US"gnutls_handshake", US"timed out", state->host, errstr); |
| 3005 | } |
| 3006 | else |
| 3007 | tls_error_gnu(US"gnutls_handshake", rc, state->host, errstr); |
| 3008 | return FALSE; |
| 3009 | } |
| 3010 | |
| 3011 | DEBUG(D_tls) post_handshake_debug(state); |
| 3012 | |
| 3013 | /* Verify late */ |
| 3014 | |
| 3015 | if (!verify_certificate(state, errstr)) |
| 3016 | { |
| 3017 | tls_error(US"certificate verification failed", *errstr, state->host, errstr); |
| 3018 | return FALSE; |
| 3019 | } |
| 3020 | |
| 3021 | #ifdef GNUTLS_SFLAGS_EXT_MASTER_SECRET |
| 3022 | if (gnutls_session_get_flags(state->session) & GNUTLS_SFLAGS_EXT_MASTER_SECRET) |
| 3023 | tlsp->ext_master_secret = TRUE; |
| 3024 | #endif |
| 3025 | |
| 3026 | #ifndef DISABLE_OCSP |
| 3027 | if (request_ocsp) |
| 3028 | { |
| 3029 | DEBUG(D_tls) |
| 3030 | { |
| 3031 | gnutls_datum_t stapling; |
| 3032 | gnutls_ocsp_resp_t resp; |
| 3033 | gnutls_datum_t printed; |
| 3034 | unsigned idx = 0; |
| 3035 | |
| 3036 | for (; |
| 3037 | # ifdef GNUTLS_OCSP_STATUS_REQUEST_GET2 |
| 3038 | (rc = gnutls_ocsp_status_request_get2(state->session, idx, &stapling)) == 0; |
| 3039 | #else |
| 3040 | (rc = gnutls_ocsp_status_request_get(state->session, &stapling)) == 0; |
| 3041 | #endif |
| 3042 | idx++) |
| 3043 | if ( (rc= gnutls_ocsp_resp_init(&resp)) == 0 |
| 3044 | && (rc= gnutls_ocsp_resp_import(resp, &stapling)) == 0 |
| 3045 | && (rc= gnutls_ocsp_resp_print(resp, GNUTLS_OCSP_PRINT_COMPACT, &printed)) == 0 |
| 3046 | ) |
| 3047 | { |
| 3048 | debug_printf("%.4096s", printed.data); |
| 3049 | gnutls_free(printed.data); |
| 3050 | } |
| 3051 | else |
| 3052 | (void) tls_error_gnu(US"ocsp decode", rc, state->host, errstr); |
| 3053 | if (idx == 0 && rc) |
| 3054 | (void) tls_error_gnu(US"ocsp decode", rc, state->host, errstr); |
| 3055 | } |
| 3056 | |
| 3057 | if (gnutls_ocsp_status_request_is_checked(state->session, 0) == 0) |
| 3058 | { |
| 3059 | tlsp->ocsp = OCSP_FAILED; |
| 3060 | tls_error(US"certificate status check failed", NULL, state->host, errstr); |
| 3061 | if (require_ocsp) |
| 3062 | return FALSE; |
| 3063 | } |
| 3064 | else |
| 3065 | { |
| 3066 | DEBUG(D_tls) debug_printf("Passed OCSP checking\n"); |
| 3067 | tlsp->ocsp = OCSP_VFIED; |
| 3068 | } |
| 3069 | } |
| 3070 | #endif |
| 3071 | |
| 3072 | #ifdef EXPERIMENTAL_TLS_RESUME |
| 3073 | tls_client_resume_posthandshake(state, tlsp, host); |
| 3074 | #endif |
| 3075 | |
| 3076 | /* Sets various Exim expansion variables; may need to adjust for ACL callouts */ |
| 3077 | |
| 3078 | extract_exim_vars_from_tls_state(state); |
| 3079 | |
| 3080 | cctx->tls_ctx = state; |
| 3081 | return TRUE; |
| 3082 | } |
| 3083 | |
| 3084 | |
| 3085 | |
| 3086 | |
| 3087 | /************************************************* |
| 3088 | * Close down a TLS session * |
| 3089 | *************************************************/ |
| 3090 | |
| 3091 | /* This is also called from within a delivery subprocess forked from the |
| 3092 | daemon, to shut down the TLS library, without actually doing a shutdown (which |
| 3093 | would tamper with the TLS session in the parent process). |
| 3094 | |
| 3095 | Arguments: |
| 3096 | ct_ctx client context pointer, or NULL for the one global server context |
| 3097 | shutdown 1 if TLS close-alert is to be sent, |
| 3098 | 2 if also response to be waited for |
| 3099 | |
| 3100 | Returns: nothing |
| 3101 | */ |
| 3102 | |
| 3103 | void |
| 3104 | tls_close(void * ct_ctx, int shutdown) |
| 3105 | { |
| 3106 | exim_gnutls_state_st * state = ct_ctx ? ct_ctx : &state_server; |
| 3107 | tls_support * tlsp = state->tlsp; |
| 3108 | |
| 3109 | if (!tlsp || tlsp->active.sock < 0) return; /* TLS was not active */ |
| 3110 | |
| 3111 | if (shutdown) |
| 3112 | { |
| 3113 | DEBUG(D_tls) debug_printf("tls_close(): shutting down TLS%s\n", |
| 3114 | shutdown > 1 ? " (with response-wait)" : ""); |
| 3115 | |
| 3116 | ALARM(2); |
| 3117 | gnutls_bye(state->session, shutdown > 1 ? GNUTLS_SHUT_RDWR : GNUTLS_SHUT_WR); |
| 3118 | ALARM_CLR(0); |
| 3119 | } |
| 3120 | |
| 3121 | if (!ct_ctx) /* server */ |
| 3122 | { |
| 3123 | receive_getc = smtp_getc; |
| 3124 | receive_getbuf = smtp_getbuf; |
| 3125 | receive_get_cache = smtp_get_cache; |
| 3126 | receive_ungetc = smtp_ungetc; |
| 3127 | receive_feof = smtp_feof; |
| 3128 | receive_ferror = smtp_ferror; |
| 3129 | receive_smtp_buffered = smtp_buffered; |
| 3130 | } |
| 3131 | |
| 3132 | gnutls_deinit(state->session); |
| 3133 | gnutls_certificate_free_credentials(state->x509_cred); |
| 3134 | |
| 3135 | tlsp->active.sock = -1; |
| 3136 | tlsp->active.tls_ctx = NULL; |
| 3137 | /* Leave bits, peercert, cipher, peerdn, certificate_verified set, for logging */ |
| 3138 | tlsp->channelbinding = NULL; |
| 3139 | |
| 3140 | |
| 3141 | if (state->xfer_buffer) store_free(state->xfer_buffer); |
| 3142 | memcpy(state, &exim_gnutls_state_init, sizeof(exim_gnutls_state_init)); |
| 3143 | } |
| 3144 | |
| 3145 | |
| 3146 | |
| 3147 | |
| 3148 | static BOOL |
| 3149 | tls_refill(unsigned lim) |
| 3150 | { |
| 3151 | exim_gnutls_state_st * state = &state_server; |
| 3152 | ssize_t inbytes; |
| 3153 | |
| 3154 | DEBUG(D_tls) debug_printf("Calling gnutls_record_recv(session=%p, buffer=%p, buffersize=%u)\n", |
| 3155 | state->session, state->xfer_buffer, ssl_xfer_buffer_size); |
| 3156 | |
| 3157 | sigalrm_seen = FALSE; |
| 3158 | if (smtp_receive_timeout > 0) ALARM(smtp_receive_timeout); |
| 3159 | |
| 3160 | do |
| 3161 | inbytes = gnutls_record_recv(state->session, state->xfer_buffer, |
| 3162 | MIN(ssl_xfer_buffer_size, lim)); |
| 3163 | while (inbytes == GNUTLS_E_AGAIN); |
| 3164 | |
| 3165 | if (smtp_receive_timeout > 0) ALARM_CLR(0); |
| 3166 | |
| 3167 | if (had_command_timeout) /* set by signal handler */ |
| 3168 | smtp_command_timeout_exit(); /* does not return */ |
| 3169 | if (had_command_sigterm) |
| 3170 | smtp_command_sigterm_exit(); |
| 3171 | if (had_data_timeout) |
| 3172 | smtp_data_timeout_exit(); |
| 3173 | if (had_data_sigint) |
| 3174 | smtp_data_sigint_exit(); |
| 3175 | |
| 3176 | /* Timeouts do not get this far. A zero-byte return appears to mean that the |
| 3177 | TLS session has been closed down, not that the socket itself has been closed |
| 3178 | down. Revert to non-TLS handling. */ |
| 3179 | |
| 3180 | if (sigalrm_seen) |
| 3181 | { |
| 3182 | DEBUG(D_tls) debug_printf("Got tls read timeout\n"); |
| 3183 | state->xfer_error = TRUE; |
| 3184 | return FALSE; |
| 3185 | } |
| 3186 | |
| 3187 | else if (inbytes == 0) |
| 3188 | { |
| 3189 | DEBUG(D_tls) debug_printf("Got TLS_EOF\n"); |
| 3190 | tls_close(NULL, TLS_NO_SHUTDOWN); |
| 3191 | return FALSE; |
| 3192 | } |
| 3193 | |
| 3194 | /* Handle genuine errors */ |
| 3195 | |
| 3196 | else if (inbytes < 0) |
| 3197 | { |
| 3198 | DEBUG(D_tls) debug_printf("%s: err from gnutls_record_recv\n", __FUNCTION__); |
| 3199 | record_io_error(state, (int) inbytes, US"recv", NULL); |
| 3200 | state->xfer_error = TRUE; |
| 3201 | return FALSE; |
| 3202 | } |
| 3203 | #ifndef DISABLE_DKIM |
| 3204 | dkim_exim_verify_feed(state->xfer_buffer, inbytes); |
| 3205 | #endif |
| 3206 | state->xfer_buffer_hwm = (int) inbytes; |
| 3207 | state->xfer_buffer_lwm = 0; |
| 3208 | return TRUE; |
| 3209 | } |
| 3210 | |
| 3211 | /************************************************* |
| 3212 | * TLS version of getc * |
| 3213 | *************************************************/ |
| 3214 | |
| 3215 | /* This gets the next byte from the TLS input buffer. If the buffer is empty, |
| 3216 | it refills the buffer via the GnuTLS reading function. |
| 3217 | Only used by the server-side TLS. |
| 3218 | |
| 3219 | This feeds DKIM and should be used for all message-body reads. |
| 3220 | |
| 3221 | Arguments: lim Maximum amount to read/buffer |
| 3222 | Returns: the next character or EOF |
| 3223 | */ |
| 3224 | |
| 3225 | int |
| 3226 | tls_getc(unsigned lim) |
| 3227 | { |
| 3228 | exim_gnutls_state_st * state = &state_server; |
| 3229 | |
| 3230 | if (state->xfer_buffer_lwm >= state->xfer_buffer_hwm) |
| 3231 | if (!tls_refill(lim)) |
| 3232 | return state->xfer_error ? EOF : smtp_getc(lim); |
| 3233 | |
| 3234 | /* Something in the buffer; return next uschar */ |
| 3235 | |
| 3236 | return state->xfer_buffer[state->xfer_buffer_lwm++]; |
| 3237 | } |
| 3238 | |
| 3239 | uschar * |
| 3240 | tls_getbuf(unsigned * len) |
| 3241 | { |
| 3242 | exim_gnutls_state_st * state = &state_server; |
| 3243 | unsigned size; |
| 3244 | uschar * buf; |
| 3245 | |
| 3246 | if (state->xfer_buffer_lwm >= state->xfer_buffer_hwm) |
| 3247 | if (!tls_refill(*len)) |
| 3248 | { |
| 3249 | if (!state->xfer_error) return smtp_getbuf(len); |
| 3250 | *len = 0; |
| 3251 | return NULL; |
| 3252 | } |
| 3253 | |
| 3254 | if ((size = state->xfer_buffer_hwm - state->xfer_buffer_lwm) > *len) |
| 3255 | size = *len; |
| 3256 | buf = &state->xfer_buffer[state->xfer_buffer_lwm]; |
| 3257 | state->xfer_buffer_lwm += size; |
| 3258 | *len = size; |
| 3259 | return buf; |
| 3260 | } |
| 3261 | |
| 3262 | |
| 3263 | void |
| 3264 | tls_get_cache() |
| 3265 | { |
| 3266 | #ifndef DISABLE_DKIM |
| 3267 | exim_gnutls_state_st * state = &state_server; |
| 3268 | int n = state->xfer_buffer_hwm - state->xfer_buffer_lwm; |
| 3269 | if (n > 0) |
| 3270 | dkim_exim_verify_feed(state->xfer_buffer+state->xfer_buffer_lwm, n); |
| 3271 | #endif |
| 3272 | } |
| 3273 | |
| 3274 | |
| 3275 | BOOL |
| 3276 | tls_could_read(void) |
| 3277 | { |
| 3278 | return state_server.xfer_buffer_lwm < state_server.xfer_buffer_hwm |
| 3279 | || gnutls_record_check_pending(state_server.session) > 0; |
| 3280 | } |
| 3281 | |
| 3282 | |
| 3283 | |
| 3284 | |
| 3285 | /************************************************* |
| 3286 | * Read bytes from TLS channel * |
| 3287 | *************************************************/ |
| 3288 | |
| 3289 | /* This does not feed DKIM, so if the caller uses this for reading message body, |
| 3290 | then the caller must feed DKIM. |
| 3291 | |
| 3292 | Arguments: |
| 3293 | ct_ctx client context pointer, or NULL for the one global server context |
| 3294 | buff buffer of data |
| 3295 | len size of buffer |
| 3296 | |
| 3297 | Returns: the number of bytes read |
| 3298 | -1 after a failed read, including EOF |
| 3299 | */ |
| 3300 | |
| 3301 | int |
| 3302 | tls_read(void * ct_ctx, uschar *buff, size_t len) |
| 3303 | { |
| 3304 | exim_gnutls_state_st * state = ct_ctx ? ct_ctx : &state_server; |
| 3305 | ssize_t inbytes; |
| 3306 | |
| 3307 | if (len > INT_MAX) |
| 3308 | len = INT_MAX; |
| 3309 | |
| 3310 | if (state->xfer_buffer_lwm < state->xfer_buffer_hwm) |
| 3311 | DEBUG(D_tls) |
| 3312 | debug_printf("*** PROBABLY A BUG *** " \ |
| 3313 | "tls_read() called with data in the tls_getc() buffer, %d ignored\n", |
| 3314 | state->xfer_buffer_hwm - state->xfer_buffer_lwm); |
| 3315 | |
| 3316 | DEBUG(D_tls) |
| 3317 | debug_printf("Calling gnutls_record_recv(session=%p, buffer=%p, len=" SIZE_T_FMT ")\n", |
| 3318 | state->session, buff, len); |
| 3319 | |
| 3320 | do |
| 3321 | inbytes = gnutls_record_recv(state->session, buff, len); |
| 3322 | while (inbytes == GNUTLS_E_AGAIN); |
| 3323 | |
| 3324 | if (inbytes > 0) return inbytes; |
| 3325 | if (inbytes == 0) |
| 3326 | { |
| 3327 | DEBUG(D_tls) debug_printf("Got TLS_EOF\n"); |
| 3328 | } |
| 3329 | else |
| 3330 | { |
| 3331 | DEBUG(D_tls) debug_printf("%s: err from gnutls_record_recv\n", __FUNCTION__); |
| 3332 | record_io_error(state, (int)inbytes, US"recv", NULL); |
| 3333 | } |
| 3334 | |
| 3335 | return -1; |
| 3336 | } |
| 3337 | |
| 3338 | |
| 3339 | |
| 3340 | |
| 3341 | /************************************************* |
| 3342 | * Write bytes down TLS channel * |
| 3343 | *************************************************/ |
| 3344 | |
| 3345 | /* |
| 3346 | Arguments: |
| 3347 | ct_ctx client context pointer, or NULL for the one global server context |
| 3348 | buff buffer of data |
| 3349 | len number of bytes |
| 3350 | more more data expected soon |
| 3351 | |
| 3352 | Calling with len zero and more unset will flush buffered writes. The buff |
| 3353 | argument can be null for that case. |
| 3354 | |
| 3355 | Returns: the number of bytes after a successful write, |
| 3356 | -1 after a failed write |
| 3357 | */ |
| 3358 | |
| 3359 | int |
| 3360 | tls_write(void * ct_ctx, const uschar * buff, size_t len, BOOL more) |
| 3361 | { |
| 3362 | ssize_t outbytes; |
| 3363 | size_t left = len; |
| 3364 | exim_gnutls_state_st * state = ct_ctx ? ct_ctx : &state_server; |
| 3365 | |
| 3366 | #ifdef SUPPORT_CORK |
| 3367 | if (more && !state->corked) |
| 3368 | { |
| 3369 | DEBUG(D_tls) debug_printf("gnutls_record_cork(session=%p)\n", state->session); |
| 3370 | gnutls_record_cork(state->session); |
| 3371 | state->corked = TRUE; |
| 3372 | } |
| 3373 | #endif |
| 3374 | |
| 3375 | DEBUG(D_tls) debug_printf("%s(%p, " SIZE_T_FMT "%s)\n", __FUNCTION__, |
| 3376 | buff, left, more ? ", more" : ""); |
| 3377 | |
| 3378 | while (left > 0) |
| 3379 | { |
| 3380 | DEBUG(D_tls) debug_printf("gnutls_record_send(session=%p, buffer=%p, left=" SIZE_T_FMT ")\n", |
| 3381 | state->session, buff, left); |
| 3382 | |
| 3383 | do |
| 3384 | outbytes = gnutls_record_send(state->session, buff, left); |
| 3385 | while (outbytes == GNUTLS_E_AGAIN); |
| 3386 | |
| 3387 | DEBUG(D_tls) debug_printf("outbytes=" SSIZE_T_FMT "\n", outbytes); |
| 3388 | |
| 3389 | if (outbytes < 0) |
| 3390 | { |
| 3391 | DEBUG(D_tls) debug_printf("%s: gnutls_record_send err\n", __FUNCTION__); |
| 3392 | record_io_error(state, outbytes, US"send", NULL); |
| 3393 | return -1; |
| 3394 | } |
| 3395 | if (outbytes == 0) |
| 3396 | { |
| 3397 | record_io_error(state, 0, US"send", US"TLS channel closed on write"); |
| 3398 | return -1; |
| 3399 | } |
| 3400 | |
| 3401 | left -= outbytes; |
| 3402 | buff += outbytes; |
| 3403 | } |
| 3404 | |
| 3405 | if (len > INT_MAX) |
| 3406 | { |
| 3407 | DEBUG(D_tls) |
| 3408 | debug_printf("Whoops! Wrote more bytes (" SIZE_T_FMT ") than INT_MAX\n", |
| 3409 | len); |
| 3410 | len = INT_MAX; |
| 3411 | } |
| 3412 | |
| 3413 | #ifdef SUPPORT_CORK |
| 3414 | if (!more && state->corked) |
| 3415 | { |
| 3416 | DEBUG(D_tls) debug_printf("gnutls_record_uncork(session=%p)\n", state->session); |
| 3417 | do |
| 3418 | /* We can't use GNUTLS_RECORD_WAIT here, as it retries on |
| 3419 | GNUTLS_E_AGAIN || GNUTLS_E_INTR, which would break our timeout set by alarm(). |
| 3420 | The GNUTLS_E_AGAIN should not happen ever, as our sockets are blocking anyway. |
| 3421 | But who knows. (That all relies on the fact that GNUTLS_E_INTR and GNUTLS_E_AGAIN |
| 3422 | match the EINTR and EAGAIN errno values.) */ |
| 3423 | outbytes = gnutls_record_uncork(state->session, 0); |
| 3424 | while (outbytes == GNUTLS_E_AGAIN); |
| 3425 | |
| 3426 | if (outbytes < 0) |
| 3427 | { |
| 3428 | record_io_error(state, len, US"uncork", NULL); |
| 3429 | return -1; |
| 3430 | } |
| 3431 | |
| 3432 | state->corked = FALSE; |
| 3433 | } |
| 3434 | #endif |
| 3435 | |
| 3436 | return (int) len; |
| 3437 | } |
| 3438 | |
| 3439 | |
| 3440 | |
| 3441 | |
| 3442 | /************************************************* |
| 3443 | * Random number generation * |
| 3444 | *************************************************/ |
| 3445 | |
| 3446 | /* Pseudo-random number generation. The result is not expected to be |
| 3447 | cryptographically strong but not so weak that someone will shoot themselves |
| 3448 | in the foot using it as a nonce in input in some email header scheme or |
| 3449 | whatever weirdness they'll twist this into. The result should handle fork() |
| 3450 | and avoid repeating sequences. OpenSSL handles that for us. |
| 3451 | |
| 3452 | Arguments: |
| 3453 | max range maximum |
| 3454 | Returns a random number in range [0, max-1] |
| 3455 | */ |
| 3456 | |
| 3457 | #ifdef HAVE_GNUTLS_RND |
| 3458 | int |
| 3459 | vaguely_random_number(int max) |
| 3460 | { |
| 3461 | unsigned int r; |
| 3462 | int i, needed_len; |
| 3463 | uschar smallbuf[sizeof(r)]; |
| 3464 | |
| 3465 | if (max <= 1) |
| 3466 | return 0; |
| 3467 | |
| 3468 | needed_len = sizeof(r); |
| 3469 | /* Don't take 8 times more entropy than needed if int is 8 octets and we were |
| 3470 | asked for a number less than 10. */ |
| 3471 | |
| 3472 | for (r = max, i = 0; r; ++i) |
| 3473 | r >>= 1; |
| 3474 | i = (i + 7) / 8; |
| 3475 | if (i < needed_len) |
| 3476 | needed_len = i; |
| 3477 | |
| 3478 | i = gnutls_rnd(GNUTLS_RND_NONCE, smallbuf, needed_len); |
| 3479 | if (i < 0) |
| 3480 | { |
| 3481 | DEBUG(D_all) debug_printf("gnutls_rnd() failed, using fallback.\n"); |
| 3482 | return vaguely_random_number_fallback(max); |
| 3483 | } |
| 3484 | r = 0; |
| 3485 | for (uschar * p = smallbuf; needed_len; --needed_len, ++p) |
| 3486 | r = r * 256 + *p; |
| 3487 | |
| 3488 | /* We don't particularly care about weighted results; if someone wants |
| 3489 | * smooth distribution and cares enough then they should submit a patch then. */ |
| 3490 | return r % max; |
| 3491 | } |
| 3492 | #else /* HAVE_GNUTLS_RND */ |
| 3493 | int |
| 3494 | vaguely_random_number(int max) |
| 3495 | { |
| 3496 | return vaguely_random_number_fallback(max); |
| 3497 | } |
| 3498 | #endif /* HAVE_GNUTLS_RND */ |
| 3499 | |
| 3500 | |
| 3501 | |
| 3502 | |
| 3503 | /************************************************* |
| 3504 | * Let tls_require_ciphers be checked at startup * |
| 3505 | *************************************************/ |
| 3506 | |
| 3507 | /* The tls_require_ciphers option, if set, must be something which the |
| 3508 | library can parse. |
| 3509 | |
| 3510 | Returns: NULL on success, or error message |
| 3511 | */ |
| 3512 | |
| 3513 | uschar * |
| 3514 | tls_validate_require_cipher(void) |
| 3515 | { |
| 3516 | int rc; |
| 3517 | uschar *expciphers = NULL; |
| 3518 | gnutls_priority_t priority_cache; |
| 3519 | const char *errpos; |
| 3520 | uschar * dummy_errstr; |
| 3521 | |
| 3522 | #ifdef GNUTLS_AUTO_GLOBAL_INIT |
| 3523 | # define validate_check_rc(Label) do { \ |
| 3524 | if (rc != GNUTLS_E_SUCCESS) { if (exim_gnutls_base_init_done) \ |
| 3525 | return string_sprintf("%s failed: %s", (Label), gnutls_strerror(rc)); } } while (0) |
| 3526 | # define return_deinit(Label) do { return (Label); } while (0) |
| 3527 | #else |
| 3528 | # define validate_check_rc(Label) do { \ |
| 3529 | if (rc != GNUTLS_E_SUCCESS) { if (exim_gnutls_base_init_done) gnutls_global_deinit(); \ |
| 3530 | return string_sprintf("%s failed: %s", (Label), gnutls_strerror(rc)); } } while (0) |
| 3531 | # define return_deinit(Label) do { gnutls_global_deinit(); return (Label); } while (0) |
| 3532 | #endif |
| 3533 | |
| 3534 | if (exim_gnutls_base_init_done) |
| 3535 | log_write(0, LOG_MAIN|LOG_PANIC, |
| 3536 | "already initialised GnuTLS, Exim developer bug"); |
| 3537 | |
| 3538 | #if defined(HAVE_GNUTLS_PKCS11) && !defined(GNUTLS_AUTO_PKCS11_MANUAL) |
| 3539 | if (!gnutls_allow_auto_pkcs11) |
| 3540 | { |
| 3541 | rc = gnutls_pkcs11_init(GNUTLS_PKCS11_FLAG_MANUAL, NULL); |
| 3542 | validate_check_rc(US"gnutls_pkcs11_init"); |
| 3543 | } |
| 3544 | #endif |
| 3545 | #ifndef GNUTLS_AUTO_GLOBAL_INIT |
| 3546 | rc = gnutls_global_init(); |
| 3547 | validate_check_rc(US"gnutls_global_init()"); |
| 3548 | #endif |
| 3549 | exim_gnutls_base_init_done = TRUE; |
| 3550 | |
| 3551 | if (!(tls_require_ciphers && *tls_require_ciphers)) |
| 3552 | return_deinit(NULL); |
| 3553 | |
| 3554 | if (!expand_check(tls_require_ciphers, US"tls_require_ciphers", &expciphers, |
| 3555 | &dummy_errstr)) |
| 3556 | return_deinit(US"failed to expand tls_require_ciphers"); |
| 3557 | |
| 3558 | if (!(expciphers && *expciphers)) |
| 3559 | return_deinit(NULL); |
| 3560 | |
| 3561 | DEBUG(D_tls) |
| 3562 | debug_printf("tls_require_ciphers expands to \"%s\"\n", expciphers); |
| 3563 | |
| 3564 | rc = gnutls_priority_init(&priority_cache, CS expciphers, &errpos); |
| 3565 | validate_check_rc(string_sprintf( |
| 3566 | "gnutls_priority_init(%s) failed at offset %ld, \"%.8s..\"", |
| 3567 | expciphers, errpos - CS expciphers, errpos)); |
| 3568 | |
| 3569 | #undef return_deinit |
| 3570 | #undef validate_check_rc |
| 3571 | #ifndef GNUTLS_AUTO_GLOBAL_INIT |
| 3572 | gnutls_global_deinit(); |
| 3573 | #endif |
| 3574 | |
| 3575 | return NULL; |
| 3576 | } |
| 3577 | |
| 3578 | |
| 3579 | |
| 3580 | |
| 3581 | /************************************************* |
| 3582 | * Report the library versions. * |
| 3583 | *************************************************/ |
| 3584 | |
| 3585 | /* See a description in tls-openssl.c for an explanation of why this exists. |
| 3586 | |
| 3587 | Arguments: a FILE* to print the results to |
| 3588 | Returns: nothing |
| 3589 | */ |
| 3590 | |
| 3591 | void |
| 3592 | tls_version_report(FILE *f) |
| 3593 | { |
| 3594 | fprintf(f, "Library version: GnuTLS: Compile: %s\n" |
| 3595 | " Runtime: %s\n", |
| 3596 | LIBGNUTLS_VERSION, |
| 3597 | gnutls_check_version(NULL)); |
| 3598 | } |
| 3599 | |
| 3600 | #endif /*!MACRO_PREDEF*/ |
| 3601 | /* vi: aw ai sw=2 |
| 3602 | */ |
| 3603 | /* End of tls-gnu.c */ |