| 1 | /* $Cambridge: exim/src/src/tls-gnu.c,v 1.7 2005/06/07 15:20:56 ph10 Exp $ */ |
| 2 | |
| 3 | /************************************************* |
| 4 | * Exim - an Internet mail transport agent * |
| 5 | *************************************************/ |
| 6 | |
| 7 | /* Copyright (c) University of Cambridge 1995 - 2005 */ |
| 8 | /* See the file NOTICE for conditions of use and distribution. */ |
| 9 | |
| 10 | /* This module provides TLS (aka SSL) support for Exim using the GnuTLS |
| 11 | library. It is #included into tls.c when that library is used. The code herein |
| 12 | is based on a patch that was contributed by Nikos Mavroyanopoulos. |
| 13 | |
| 14 | No cryptographic code is included in Exim. All this module does is to call |
| 15 | functions from the GnuTLS library. */ |
| 16 | |
| 17 | |
| 18 | /* Heading stuff for GnuTLS */ |
| 19 | |
| 20 | #include <gnutls/gnutls.h> |
| 21 | #include <gnutls/x509.h> |
| 22 | |
| 23 | |
| 24 | #define UNKNOWN_NAME "unknown" |
| 25 | #define DH_BITS 768 |
| 26 | #define RSA_BITS 512 |
| 27 | #define PARAM_SIZE 2*1024 |
| 28 | |
| 29 | |
| 30 | /* Values for verify_requirment and initialized */ |
| 31 | |
| 32 | enum { VERIFY_NONE, VERIFY_OPTIONAL, VERIFY_REQUIRED }; |
| 33 | enum { INITIALIZED_NOT, INITIALIZED_SERVER, INITIALIZED_CLIENT }; |
| 34 | |
| 35 | /* Local static variables for GNUTLS */ |
| 36 | |
| 37 | static BOOL initialized = INITIALIZED_NOT; |
| 38 | static host_item *client_host; |
| 39 | |
| 40 | static gnutls_rsa_params rsa_params = NULL; |
| 41 | static gnutls_dh_params dh_params = NULL; |
| 42 | |
| 43 | static gnutls_certificate_server_credentials x509_cred = NULL; |
| 44 | static gnutls_session tls_session = NULL; |
| 45 | |
| 46 | static char ssl_errstring[256]; |
| 47 | |
| 48 | static int ssl_session_timeout = 200; |
| 49 | static int verify_requirement; |
| 50 | |
| 51 | /* Priorities for TLS algorithms to use. At present, only the cipher priority |
| 52 | vector can be altered. */ |
| 53 | |
| 54 | static const int protocol_priority[16] = { GNUTLS_TLS1, GNUTLS_SSL3, 0 }; |
| 55 | |
| 56 | static const int kx_priority[16] = { |
| 57 | GNUTLS_KX_RSA, |
| 58 | GNUTLS_KX_DHE_DSS, |
| 59 | GNUTLS_KX_DHE_RSA, |
| 60 | GNUTLS_KX_RSA_EXPORT, |
| 61 | 0 }; |
| 62 | |
| 63 | static int default_cipher_priority[16] = { |
| 64 | GNUTLS_CIPHER_AES_256_CBC, |
| 65 | GNUTLS_CIPHER_AES_128_CBC, |
| 66 | GNUTLS_CIPHER_3DES_CBC, |
| 67 | GNUTLS_CIPHER_ARCFOUR_128, |
| 68 | 0 }; |
| 69 | |
| 70 | static int cipher_priority[16]; |
| 71 | |
| 72 | static const int mac_priority[16] = { |
| 73 | GNUTLS_MAC_SHA, |
| 74 | GNUTLS_MAC_MD5, |
| 75 | 0 }; |
| 76 | |
| 77 | static const int comp_priority[16] = { GNUTLS_COMP_NULL, 0 }; |
| 78 | static const int cert_type_priority[16] = { GNUTLS_CRT_X509, 0 }; |
| 79 | |
| 80 | /* Tables of cipher names and equivalent numbers */ |
| 81 | |
| 82 | typedef struct pri_item { |
| 83 | uschar *name; |
| 84 | int *values; |
| 85 | } pri_item; |
| 86 | |
| 87 | static int arcfour_128_codes[] = { GNUTLS_CIPHER_ARCFOUR_128, 0 }; |
| 88 | static int arcfour_40_codes[] = { GNUTLS_CIPHER_ARCFOUR_40, 0 }; |
| 89 | static int arcfour_codes[] = { GNUTLS_CIPHER_ARCFOUR_128, |
| 90 | GNUTLS_CIPHER_ARCFOUR_40, 0 }; |
| 91 | static int aes_256_codes[] = { GNUTLS_CIPHER_AES_256_CBC, 0 }; |
| 92 | static int aes_128_codes[] = { GNUTLS_CIPHER_AES_128_CBC, 0 }; |
| 93 | static int aes_codes[] = { GNUTLS_CIPHER_AES_256_CBC, |
| 94 | GNUTLS_CIPHER_AES_128_CBC, 0 }; |
| 95 | static int des3_codes[] = { GNUTLS_CIPHER_3DES_CBC, 0 }; |
| 96 | |
| 97 | static pri_item cipher_index[] = { |
| 98 | { US"ARCFOUR_128", arcfour_128_codes }, |
| 99 | { US"ARCFOUR_40", arcfour_40_codes }, |
| 100 | { US"ARCFOUR", arcfour_codes }, |
| 101 | { US"AES_256", aes_256_codes }, |
| 102 | { US"AES_128", aes_128_codes }, |
| 103 | { US"AES", aes_codes }, |
| 104 | { US"3DES", des3_codes } |
| 105 | }; |
| 106 | |
| 107 | |
| 108 | |
| 109 | /************************************************* |
| 110 | * Handle TLS error * |
| 111 | *************************************************/ |
| 112 | |
| 113 | /* Called from lots of places when errors occur before actually starting to do |
| 114 | the TLS handshake, that is, while the session is still in clear. Always returns |
| 115 | DEFER for a server and FAIL for a client so that most calls can use "return |
| 116 | tls_error(...)" to do this processing and then give an appropriate return. A |
| 117 | single function is used for both server and client, because it is called from |
| 118 | some shared functions. |
| 119 | |
| 120 | Argument: |
| 121 | prefix text to include in the logged error |
| 122 | host NULL if setting up a server; |
| 123 | the connected host if setting up a client |
| 124 | err a GnuTLS error number, or 0 if local error |
| 125 | |
| 126 | Returns: OK/DEFER/FAIL |
| 127 | */ |
| 128 | |
| 129 | static int |
| 130 | tls_error(uschar *prefix, host_item *host, int err) |
| 131 | { |
| 132 | uschar *errtext = US""; |
| 133 | if (err != 0) errtext = string_sprintf(": %s", gnutls_strerror(err)); |
| 134 | if (host == NULL) |
| 135 | { |
| 136 | log_write(0, LOG_MAIN, "TLS error on connection from %s (%s)%s", |
| 137 | (sender_fullhost != NULL)? sender_fullhost : US "local process", |
| 138 | prefix, errtext); |
| 139 | return DEFER; |
| 140 | } |
| 141 | else |
| 142 | { |
| 143 | log_write(0, LOG_MAIN, "TLS error on connection to %s [%s] (%s)%s", |
| 144 | host->name, host->address, prefix, errtext); |
| 145 | return FAIL; |
| 146 | } |
| 147 | } |
| 148 | |
| 149 | |
| 150 | |
| 151 | /************************************************* |
| 152 | * Verify certificate * |
| 153 | *************************************************/ |
| 154 | |
| 155 | /* Called after a successful handshake, when certificate verification is |
| 156 | required or optional, for both server and client. |
| 157 | |
| 158 | Arguments: |
| 159 | session GNUTLS session |
| 160 | error where to put text giving a reason for failure |
| 161 | |
| 162 | Returns: TRUE/FALSE |
| 163 | */ |
| 164 | |
| 165 | static BOOL |
| 166 | verify_certificate(gnutls_session session, uschar **error) |
| 167 | { |
| 168 | int verify; |
| 169 | uschar *dn_string = US""; |
| 170 | const gnutls_datum *cert; |
| 171 | unsigned int cert_size = 0; |
| 172 | |
| 173 | *error = NULL; |
| 174 | |
| 175 | /* Get the peer's certificate. If it sent one, extract it's DN, and then |
| 176 | attempt to verify the certificate. If no certificate is supplied, verification |
| 177 | is forced to fail. */ |
| 178 | |
| 179 | cert = gnutls_certificate_get_peers(session, &cert_size); |
| 180 | if (cert != NULL) |
| 181 | { |
| 182 | uschar buff[1024]; |
| 183 | gnutls_x509_crt gcert; |
| 184 | |
| 185 | gnutls_x509_crt_init(&gcert); |
| 186 | dn_string = US"unknown"; |
| 187 | |
| 188 | if (gnutls_x509_crt_import(gcert, cert, GNUTLS_X509_FMT_DER) == 0) |
| 189 | { |
| 190 | size_t bufsize = sizeof(buff); |
| 191 | if (gnutls_x509_crt_get_dn(gcert, CS buff, &bufsize) >= 0) |
| 192 | dn_string = string_copy_malloc(buff); |
| 193 | } |
| 194 | |
| 195 | verify = gnutls_certificate_verify_peers(session); |
| 196 | } |
| 197 | else |
| 198 | { |
| 199 | DEBUG(D_tls) debug_printf("no peer certificate supplied\n"); |
| 200 | verify = GNUTLS_CERT_INVALID; |
| 201 | *error = US"not supplied"; |
| 202 | } |
| 203 | |
| 204 | /* Handle the result of verification. INVALID seems to be set as well |
| 205 | as REVOKED, but leave the test for both. */ |
| 206 | |
| 207 | if ((verify & (GNUTLS_CERT_INVALID|GNUTLS_CERT_REVOKED)) != 0) |
| 208 | { |
| 209 | tls_certificate_verified = FALSE; |
| 210 | if (*error == NULL) *error = ((verify & GNUTLS_CERT_REVOKED) != 0)? |
| 211 | US"revoked" : US"invalid"; |
| 212 | if (verify_requirement == VERIFY_REQUIRED) |
| 213 | { |
| 214 | DEBUG(D_tls) debug_printf("TLS certificate verification failed (%s): " |
| 215 | "peerdn=%s\n", *error, dn_string); |
| 216 | gnutls_alert_send(session, GNUTLS_AL_FATAL, GNUTLS_A_BAD_CERTIFICATE); |
| 217 | return FALSE; /* reject */ |
| 218 | } |
| 219 | DEBUG(D_tls) debug_printf("TLS certificate verify failure (%s) overridden " |
| 220 | "(host in tls_try_verify_hosts): peerdn=%s\n", *error, dn_string); |
| 221 | } |
| 222 | else |
| 223 | { |
| 224 | tls_certificate_verified = TRUE; |
| 225 | DEBUG(D_tls) debug_printf("TLS certificate verified: peerdn=%s\n", |
| 226 | dn_string); |
| 227 | } |
| 228 | |
| 229 | tls_peerdn = dn_string; |
| 230 | return TRUE; /* accept */ |
| 231 | } |
| 232 | |
| 233 | |
| 234 | |
| 235 | /************************************************* |
| 236 | * Setup up RSA and DH parameters * |
| 237 | *************************************************/ |
| 238 | |
| 239 | /* Generating the RSA and D-H parameters takes a long time. They only need to |
| 240 | be re-generated every so often, depending on security policy. What we do is to |
| 241 | keep these parameters in a file in the spool directory. If the file does not |
| 242 | exist, we generate them. This means that it is easy to cause a regeneration. |
| 243 | |
| 244 | The new file is written as a temporary file and renamed, so that an incomplete |
| 245 | file is never present. If two processes both compute some new parameters, you |
| 246 | waste a bit of effort, but it doesn't seem worth messing around with locking to |
| 247 | prevent this. |
| 248 | |
| 249 | Argument: |
| 250 | host NULL for server, server for client (for error handling) |
| 251 | |
| 252 | Returns: OK/DEFER/FAIL |
| 253 | */ |
| 254 | |
| 255 | static int |
| 256 | init_rsa_dh(host_item *host) |
| 257 | { |
| 258 | int fd; |
| 259 | int ret = -1; |
| 260 | gnutls_datum m; |
| 261 | uschar filename[200]; |
| 262 | |
| 263 | /* Initialize the data structures for holding the parameters */ |
| 264 | |
| 265 | ret = gnutls_rsa_params_init(&rsa_params); |
| 266 | if (ret < 0) return tls_error(US"init rsa_params", host, ret); |
| 267 | |
| 268 | ret = gnutls_dh_params_init(&dh_params); |
| 269 | if (ret < 0) return tls_error(US"init dh_params", host, ret); |
| 270 | |
| 271 | /* Set up the name of the cache file */ |
| 272 | |
| 273 | if (!string_format(filename, sizeof(filename), "%s/gnutls-params", |
| 274 | spool_directory)) |
| 275 | return tls_error(US"overlong filename", host, 0); |
| 276 | |
| 277 | /* Open the cache file for reading and if successful, read it and set up the |
| 278 | parameters. If we can't set up the RSA parameters, assume that we are dealing |
| 279 | with an old-style cache file that is in another format, and fall through to |
| 280 | compute new values. However, if we correctly get RSA parameters, a failure to |
| 281 | set up D-H parameters is treated as an error. */ |
| 282 | |
| 283 | fd = Uopen(filename, O_RDONLY, 0); |
| 284 | if (fd >= 0) |
| 285 | { |
| 286 | struct stat statbuf; |
| 287 | if (fstat(fd, &statbuf) < 0) |
| 288 | { |
| 289 | (void)close(fd); |
| 290 | return tls_error(US"TLS cache stat failed", host, 0); |
| 291 | } |
| 292 | |
| 293 | m.size = statbuf.st_size; |
| 294 | m.data = malloc(m.size); |
| 295 | if (m.data == NULL) |
| 296 | return tls_error(US"memory allocation failed", host, 0); |
| 297 | if (read(fd, m.data, m.size) != m.size) |
| 298 | return tls_error(US"TLS cache read failed", host, 0); |
| 299 | (void)close(fd); |
| 300 | |
| 301 | ret = gnutls_rsa_params_import_pkcs1(rsa_params, &m, GNUTLS_X509_FMT_PEM); |
| 302 | if (ret < 0) |
| 303 | { |
| 304 | DEBUG(D_tls) |
| 305 | debug_printf("RSA params import failed: assume old-style cache file\n"); |
| 306 | } |
| 307 | else |
| 308 | { |
| 309 | ret = gnutls_dh_params_import_pkcs3(dh_params, &m, GNUTLS_X509_FMT_PEM); |
| 310 | if (ret < 0) |
| 311 | return tls_error(US"DH params import", host, ret); |
| 312 | DEBUG(D_tls) debug_printf("read RSA and D-H parameters from file\n"); |
| 313 | } |
| 314 | |
| 315 | free(m.data); |
| 316 | } |
| 317 | |
| 318 | /* If the file does not exist, fall through to compute new data and cache it. |
| 319 | If there was any other opening error, it is serious. */ |
| 320 | |
| 321 | else if (errno != ENOENT) |
| 322 | return tls_error(string_open_failed(errno, "%s for reading", filename), |
| 323 | host, 0); |
| 324 | |
| 325 | /* If ret < 0, either the cache file does not exist, or the data it contains |
| 326 | is not useful. One particular case of this is when upgrading from an older |
| 327 | release of Exim in which the data was stored in a different format. We don't |
| 328 | try to be clever and support both formats; we just regenerate new data in this |
| 329 | case. */ |
| 330 | |
| 331 | if (ret < 0) |
| 332 | { |
| 333 | uschar tempfilename[sizeof(filename) + 10]; |
| 334 | |
| 335 | DEBUG(D_tls) debug_printf("generating %d bit RSA key...\n", RSA_BITS); |
| 336 | ret = gnutls_rsa_params_generate2(rsa_params, RSA_BITS); |
| 337 | if (ret < 0) return tls_error(US"RSA key generation", host, ret); |
| 338 | |
| 339 | DEBUG(D_tls) debug_printf("generating %d bit Diffie-Hellman key...\n", |
| 340 | DH_BITS); |
| 341 | ret = gnutls_dh_params_generate2(dh_params, DH_BITS); |
| 342 | if (ret < 0) return tls_error(US"D-H key generation", host, ret); |
| 343 | |
| 344 | /* Write the parameters to a file in the spool directory so that we |
| 345 | can use them from other Exim processes. */ |
| 346 | |
| 347 | sprintf(CS tempfilename, "%s-%d", filename, (int)getpid()); |
| 348 | fd = Uopen(tempfilename, O_WRONLY|O_CREAT, 0400); |
| 349 | if (fd < 0) |
| 350 | return tls_error(string_open_failed(errno, "%s for writing", filename), |
| 351 | host, 0); |
| 352 | (void)fchown(fd, exim_uid, exim_gid); /* Probably not necessary */ |
| 353 | |
| 354 | /* export the parameters in a format that can be generated using GNUTLS' |
| 355 | * certtool or other programs. |
| 356 | * |
| 357 | * The commands for certtool are: |
| 358 | * $ certtool --generate-privkey --bits 512 >params |
| 359 | * $ echo "" >>params |
| 360 | * $ certtool --generate-dh-params --bits 1024 >> params |
| 361 | */ |
| 362 | |
| 363 | m.size = PARAM_SIZE; |
| 364 | m.data = malloc(m.size); |
| 365 | if (m.data == NULL) |
| 366 | return tls_error(US"memory allocation failed", host, 0); |
| 367 | |
| 368 | ret = gnutls_rsa_params_export_pkcs1(rsa_params, GNUTLS_X509_FMT_PEM, |
| 369 | m.data, &m.size); |
| 370 | if (ret < 0) return tls_error(US"RSA params export", host, ret); |
| 371 | |
| 372 | /* Do not write the null termination byte. */ |
| 373 | |
| 374 | m.size = Ustrlen(m.data); |
| 375 | if (write(fd, m.data, m.size) != m.size || write(fd, "\n", 1) != 1) |
| 376 | return tls_error(US"TLS cache write failed", host, 0); |
| 377 | |
| 378 | m.size = PARAM_SIZE; |
| 379 | ret = gnutls_dh_params_export_pkcs3(dh_params, GNUTLS_X509_FMT_PEM, m.data, |
| 380 | &m.size); |
| 381 | if (ret < 0) return tls_error(US"DH params export", host, ret); |
| 382 | |
| 383 | m.size = Ustrlen(m.data); |
| 384 | if (write(fd, m.data, m.size) != m.size || write(fd, "\n", 1) != 1) |
| 385 | return tls_error(US"TLS cache write failed", host, 0); |
| 386 | |
| 387 | free(m.data); |
| 388 | (void)close(fd); |
| 389 | |
| 390 | if (rename(CS tempfilename, CS filename) < 0) |
| 391 | return tls_error(string_sprintf("failed to rename %s as %s: %s", |
| 392 | tempfilename, filename, strerror(errno)), host, 0); |
| 393 | |
| 394 | DEBUG(D_tls) debug_printf("wrote RSA and D-H parameters to file\n"); |
| 395 | } |
| 396 | |
| 397 | DEBUG(D_tls) debug_printf("initialized RSA and D-H parameters\n"); |
| 398 | return OK; |
| 399 | } |
| 400 | |
| 401 | |
| 402 | |
| 403 | |
| 404 | /************************************************* |
| 405 | * Initialize for GnuTLS * |
| 406 | *************************************************/ |
| 407 | |
| 408 | /* Called from both server and client code. In the case of a server, errors |
| 409 | before actual TLS negotiation return DEFER. |
| 410 | |
| 411 | Arguments: |
| 412 | host connected host, if client; NULL if server |
| 413 | certificate certificate file |
| 414 | privatekey private key file |
| 415 | cas CA certs file |
| 416 | crl CRL file |
| 417 | |
| 418 | Returns: OK/DEFER/FAIL |
| 419 | */ |
| 420 | |
| 421 | static int |
| 422 | tls_init(host_item *host, uschar *certificate, uschar *privatekey, uschar *cas, |
| 423 | uschar *crl) |
| 424 | { |
| 425 | int rc; |
| 426 | uschar *cert_expanded, *key_expanded, *cas_expanded, *crl_expanded; |
| 427 | |
| 428 | initialized = (host == NULL)? INITIALIZED_SERVER : INITIALIZED_CLIENT; |
| 429 | |
| 430 | rc = gnutls_global_init(); |
| 431 | if (rc < 0) return tls_error(US"tls-init", host, rc); |
| 432 | |
| 433 | /* Create RSA and D-H parameters, or read them from the cache file. This |
| 434 | function does its own SMTP error messaging. */ |
| 435 | |
| 436 | rc = init_rsa_dh(host); |
| 437 | if (rc != OK) return rc; |
| 438 | |
| 439 | /* Create the credentials structure */ |
| 440 | |
| 441 | rc = gnutls_certificate_allocate_credentials(&x509_cred); |
| 442 | if (rc < 0) return tls_error(US"certificate_allocate_credentials", host, rc); |
| 443 | |
| 444 | /* This stuff must be done for each session, because different certificates |
| 445 | may be required for different sessions. */ |
| 446 | |
| 447 | if (!expand_check(certificate, US"tls_certificate", &cert_expanded)) |
| 448 | return DEFER; |
| 449 | |
| 450 | if (privatekey != NULL) |
| 451 | { |
| 452 | if (!expand_check(privatekey, US"tls_privatekey", &key_expanded)) |
| 453 | return DEFER; |
| 454 | } |
| 455 | else key_expanded = cert_expanded; |
| 456 | |
| 457 | /* Set the certificate and private keys */ |
| 458 | |
| 459 | if (cert_expanded != NULL) |
| 460 | { |
| 461 | DEBUG(D_tls) debug_printf("certificate file = %s\nkey file = %s\n", |
| 462 | cert_expanded, key_expanded); |
| 463 | rc = gnutls_certificate_set_x509_key_file(x509_cred, CS cert_expanded, |
| 464 | CS key_expanded, GNUTLS_X509_FMT_PEM); |
| 465 | if (rc < 0) |
| 466 | { |
| 467 | uschar *msg = string_sprintf("cert/key setup: cert=%s key=%s", |
| 468 | cert_expanded, key_expanded); |
| 469 | return tls_error(msg, host, rc); |
| 470 | } |
| 471 | } |
| 472 | |
| 473 | /* A certificate is mandatory in a server, but not in a client */ |
| 474 | |
| 475 | else |
| 476 | { |
| 477 | if (host == NULL) |
| 478 | return tls_error(US"no TLS server certificate is specified", host, 0); |
| 479 | DEBUG(D_tls) debug_printf("no TLS client certificate is specified\n"); |
| 480 | } |
| 481 | |
| 482 | /* Set the trusted CAs file if one is provided, and then add the CRL if one is |
| 483 | provided. Experiment shows that, if the certificate file is empty, an unhelpful |
| 484 | error message is provided. However, if we just refrain from setting anything up |
| 485 | in that case, certificate verification fails, which seems to be the correct |
| 486 | behaviour. */ |
| 487 | |
| 488 | if (cas != NULL) |
| 489 | { |
| 490 | struct stat statbuf; |
| 491 | |
| 492 | if (!expand_check(cas, US"tls_verify_certificates", &cas_expanded)) |
| 493 | return DEFER; |
| 494 | |
| 495 | if (stat(CS cas_expanded, &statbuf) < 0) |
| 496 | { |
| 497 | log_write(0, LOG_MAIN|LOG_PANIC, "could not stat %s " |
| 498 | "(tls_verify_certificates): %s", cas_expanded, strerror(errno)); |
| 499 | return DEFER; |
| 500 | } |
| 501 | |
| 502 | DEBUG(D_tls) debug_printf("verify certificates = %s size=%.30g\n", |
| 503 | cas_expanded, (double)statbuf.st_size); |
| 504 | |
| 505 | /* If the cert file is empty, there's no point in loading the CRL file. */ |
| 506 | |
| 507 | if (statbuf.st_size > 0) |
| 508 | { |
| 509 | rc = gnutls_certificate_set_x509_trust_file(x509_cred, CS cas_expanded, |
| 510 | GNUTLS_X509_FMT_PEM); |
| 511 | if (rc < 0) return tls_error(US"setup_certs", host, rc); |
| 512 | |
| 513 | if (crl != NULL && *crl != 0) |
| 514 | { |
| 515 | if (!expand_check(crl, US"tls_crl", &crl_expanded)) |
| 516 | return DEFER; |
| 517 | DEBUG(D_tls) debug_printf("loading CRL file = %s\n", crl_expanded); |
| 518 | rc = gnutls_certificate_set_x509_crl_file(x509_cred, CS crl_expanded, |
| 519 | GNUTLS_X509_FMT_PEM); |
| 520 | if (rc < 0) return tls_error(US"CRL setup", host, rc); |
| 521 | } |
| 522 | } |
| 523 | } |
| 524 | |
| 525 | /* Associate the parameters with the x509 credentials structure. */ |
| 526 | |
| 527 | gnutls_certificate_set_dh_params(x509_cred, dh_params); |
| 528 | gnutls_certificate_set_rsa_export_params(x509_cred, rsa_params); |
| 529 | |
| 530 | DEBUG(D_tls) debug_printf("initialized certificate stuff\n"); |
| 531 | return OK; |
| 532 | } |
| 533 | |
| 534 | |
| 535 | |
| 536 | |
| 537 | /************************************************* |
| 538 | * Remove ciphers from priority list * |
| 539 | *************************************************/ |
| 540 | |
| 541 | /* Cautiously written so that it will remove duplicates if present. |
| 542 | |
| 543 | Arguments: |
| 544 | list a zero-terminated list |
| 545 | remove_list a zero-terminated list to be removed |
| 546 | |
| 547 | Returns: nothing |
| 548 | */ |
| 549 | |
| 550 | static void |
| 551 | remove_ciphers(int *list, int *remove_list) |
| 552 | { |
| 553 | for (; *remove_list != 0; remove_list++) |
| 554 | { |
| 555 | int *p = list; |
| 556 | while (*p != 0) |
| 557 | { |
| 558 | if (*p == *remove_list) |
| 559 | { |
| 560 | int *pp = p; |
| 561 | do { pp[0] = pp[1]; pp++; } while (*pp != 0); |
| 562 | } |
| 563 | else p++; |
| 564 | } |
| 565 | } |
| 566 | } |
| 567 | |
| 568 | |
| 569 | |
| 570 | /************************************************* |
| 571 | * Add ciphers to priority list * |
| 572 | *************************************************/ |
| 573 | |
| 574 | /* Cautiously written to check the list size |
| 575 | |
| 576 | Arguments: |
| 577 | list a zero-terminated list |
| 578 | list_max maximum offset in the list |
| 579 | add_list a zero-terminated list to be added |
| 580 | |
| 581 | Returns: TRUE if OK; FALSE if list overflows |
| 582 | */ |
| 583 | |
| 584 | static BOOL |
| 585 | add_ciphers(int *list, int list_max, int *add_list) |
| 586 | { |
| 587 | int next = 0; |
| 588 | while (list[next] != 0) next++; |
| 589 | while (*add_list != 0) |
| 590 | { |
| 591 | if (next >= list_max) return FALSE; |
| 592 | list[next++] = *add_list++; |
| 593 | } |
| 594 | list[next] = 0; |
| 595 | return TRUE; |
| 596 | } |
| 597 | |
| 598 | |
| 599 | |
| 600 | /************************************************* |
| 601 | * Initialize a single GNUTLS session * |
| 602 | *************************************************/ |
| 603 | |
| 604 | /* Set the algorithm, the db backend, whether to request certificates etc. |
| 605 | |
| 606 | TLS in Exim was first implemented using OpenSSL. This has a function to which |
| 607 | you pass a list of cipher suites that are permitted/not permitted. GnuTLS works |
| 608 | differently. It operates using priority lists for the different components of |
| 609 | cipher suites. |
| 610 | |
| 611 | For compatibility of configuration, we scan a list of cipher suites and set |
| 612 | priorities therefrom. However, at the moment, we pay attention only to the bulk |
| 613 | cipher. |
| 614 | |
| 615 | Arguments: |
| 616 | side one of GNUTLS_SERVER, GNUTLS_CLIENT |
| 617 | expciphers expanded ciphers list |
| 618 | |
| 619 | Returns: a gnutls_session, or NULL if there is a problem |
| 620 | */ |
| 621 | |
| 622 | static gnutls_session |
| 623 | tls_session_init(int side, uschar *expciphers) |
| 624 | { |
| 625 | gnutls_session session; |
| 626 | |
| 627 | gnutls_init(&session, side); |
| 628 | |
| 629 | /* Handle the list of permitted ciphers */ |
| 630 | |
| 631 | memcpy(cipher_priority, default_cipher_priority, sizeof(cipher_priority)); |
| 632 | |
| 633 | if (expciphers != NULL) |
| 634 | { |
| 635 | int sep = 0; |
| 636 | BOOL first = TRUE; |
| 637 | uschar *cipher; |
| 638 | |
| 639 | /* The names OpenSSL uses are of the form DES-CBC3-SHA, using hyphen |
| 640 | separators. GnuTLS uses underscore separators. So that I can use either form |
| 641 | in my tests, and also for general convenience, we turn hyphens into |
| 642 | underscores before scanning the list. */ |
| 643 | |
| 644 | uschar *s = expciphers; |
| 645 | while (*s != 0) { if (*s == '-') *s = '_'; s++; } |
| 646 | |
| 647 | while ((cipher = string_nextinlist(&expciphers, &sep, big_buffer, |
| 648 | big_buffer_size)) != NULL) |
| 649 | { |
| 650 | int i; |
| 651 | BOOL exclude = cipher[0] == '!'; |
| 652 | if (first && !exclude) cipher_priority[0] = 0; |
| 653 | first = FALSE; |
| 654 | |
| 655 | for (i = 0; i < sizeof(cipher_index)/sizeof(pri_item); i++) |
| 656 | { |
| 657 | uschar *ss = strstric(cipher, cipher_index[i].name, FALSE); |
| 658 | if (ss != NULL) |
| 659 | { |
| 660 | uschar *endss = ss + Ustrlen(cipher_index[i].name); |
| 661 | if ((ss == cipher || !isalnum(ss[-1])) && !isalnum(*endss)) |
| 662 | { |
| 663 | if (exclude) |
| 664 | remove_ciphers(cipher_priority, cipher_index[i].values); |
| 665 | else |
| 666 | { |
| 667 | if (!add_ciphers(cipher_priority, |
| 668 | sizeof(cipher_priority)/sizeof(pri_item), |
| 669 | cipher_index[i].values)) |
| 670 | { |
| 671 | log_write(0, LOG_MAIN|LOG_PANIC, "GnuTLS init failed: cipher " |
| 672 | "priority table overflow"); |
| 673 | gnutls_deinit(session); |
| 674 | return NULL; |
| 675 | } |
| 676 | } |
| 677 | } |
| 678 | } |
| 679 | } |
| 680 | } |
| 681 | |
| 682 | DEBUG(D_tls) |
| 683 | { |
| 684 | int *ptr = cipher_priority; |
| 685 | debug_printf("adjusted cipher priorities:"); |
| 686 | while (*ptr != 0) debug_printf(" %d", *ptr++); |
| 687 | debug_printf("\n"); |
| 688 | } |
| 689 | } |
| 690 | |
| 691 | /* Define the various priorities */ |
| 692 | |
| 693 | gnutls_cipher_set_priority(session, cipher_priority); |
| 694 | gnutls_compression_set_priority(session, comp_priority); |
| 695 | gnutls_kx_set_priority(session, kx_priority); |
| 696 | gnutls_protocol_set_priority(session, protocol_priority); |
| 697 | gnutls_mac_set_priority(session, mac_priority); |
| 698 | |
| 699 | gnutls_cred_set(session, GNUTLS_CRD_CERTIFICATE, x509_cred); |
| 700 | |
| 701 | gnutls_dh_set_prime_bits(session, DH_BITS); |
| 702 | |
| 703 | /* Request or demand a certificate of the peer, as configured. This will |
| 704 | happen only in a server. */ |
| 705 | |
| 706 | if (verify_requirement != VERIFY_NONE) |
| 707 | gnutls_certificate_server_set_request(session, |
| 708 | (verify_requirement == VERIFY_OPTIONAL)? |
| 709 | GNUTLS_CERT_REQUEST : GNUTLS_CERT_REQUIRE); |
| 710 | |
| 711 | gnutls_db_set_cache_expiration(session, ssl_session_timeout); |
| 712 | |
| 713 | DEBUG(D_tls) debug_printf("initialized GnuTLS session\n"); |
| 714 | return session; |
| 715 | } |
| 716 | |
| 717 | |
| 718 | |
| 719 | /************************************************* |
| 720 | * Get name of cipher in use * |
| 721 | *************************************************/ |
| 722 | |
| 723 | /* The answer is left in a static buffer, and tls_cipher is set to point |
| 724 | to it. |
| 725 | |
| 726 | Argument: pointer to a GnuTLS session |
| 727 | Returns: nothing |
| 728 | */ |
| 729 | |
| 730 | static void |
| 731 | construct_cipher_name(gnutls_session session) |
| 732 | { |
| 733 | static uschar cipherbuf[256]; |
| 734 | uschar *ver; |
| 735 | int bits, c, kx, mac; |
| 736 | |
| 737 | ver = string_copy( |
| 738 | US gnutls_protocol_get_name(gnutls_protocol_get_version(session))); |
| 739 | if (Ustrncmp(ver, "TLS ", 4) == 0) ver[3] = '-'; /* Don't want space */ |
| 740 | |
| 741 | c = gnutls_cipher_get(session); |
| 742 | bits = gnutls_cipher_get_key_size(c); |
| 743 | |
| 744 | mac = gnutls_mac_get(session); |
| 745 | kx = gnutls_kx_get(session); |
| 746 | |
| 747 | string_format(cipherbuf, sizeof(cipherbuf), "%s:%s:%u", ver, |
| 748 | gnutls_cipher_suite_get_name(kx, c, mac), bits); |
| 749 | tls_cipher = cipherbuf; |
| 750 | |
| 751 | DEBUG(D_tls) debug_printf("cipher: %s\n", cipherbuf); |
| 752 | } |
| 753 | |
| 754 | |
| 755 | |
| 756 | /************************************************* |
| 757 | * Start a TLS session in a server * |
| 758 | *************************************************/ |
| 759 | |
| 760 | /* This is called when Exim is running as a server, after having received |
| 761 | the STARTTLS command. It must respond to that command, and then negotiate |
| 762 | a TLS session. |
| 763 | |
| 764 | Arguments: |
| 765 | require_ciphers list of allowed ciphers |
| 766 | |
| 767 | Returns: OK on success |
| 768 | DEFER for errors before the start of the negotiation |
| 769 | FAIL for errors during the negotation; the server can't |
| 770 | continue running. |
| 771 | */ |
| 772 | |
| 773 | int |
| 774 | tls_server_start(uschar *require_ciphers) |
| 775 | { |
| 776 | int rc; |
| 777 | uschar *error; |
| 778 | uschar *expciphers = NULL; |
| 779 | |
| 780 | /* Check for previous activation */ |
| 781 | |
| 782 | if (tls_active >= 0) |
| 783 | { |
| 784 | log_write(0, LOG_MAIN, "STARTTLS received in already encrypted " |
| 785 | "connection from %s", |
| 786 | (sender_fullhost != NULL)? sender_fullhost : US"local process"); |
| 787 | smtp_printf("554 Already in TLS\r\n"); |
| 788 | return FAIL; |
| 789 | } |
| 790 | |
| 791 | /* Initialize the library. If it fails, it will already have logged the error |
| 792 | and sent an SMTP response. */ |
| 793 | |
| 794 | DEBUG(D_tls) debug_printf("initializing GnuTLS as a server\n"); |
| 795 | |
| 796 | rc = tls_init(NULL, tls_certificate, tls_privatekey, tls_verify_certificates, |
| 797 | tls_crl); |
| 798 | if (rc != OK) return rc; |
| 799 | |
| 800 | if (!expand_check(require_ciphers, US"tls_require_ciphers", &expciphers)) |
| 801 | return FAIL; |
| 802 | |
| 803 | /* If this is a host for which certificate verification is mandatory or |
| 804 | optional, set up appropriately. */ |
| 805 | |
| 806 | tls_certificate_verified = FALSE; |
| 807 | verify_requirement = VERIFY_NONE; |
| 808 | |
| 809 | if (verify_check_host(&tls_verify_hosts) == OK) |
| 810 | verify_requirement = VERIFY_REQUIRED; |
| 811 | else if (verify_check_host(&tls_try_verify_hosts) == OK) |
| 812 | verify_requirement = VERIFY_OPTIONAL; |
| 813 | |
| 814 | /* Prepare for new connection */ |
| 815 | |
| 816 | tls_session = tls_session_init(GNUTLS_SERVER, expciphers); |
| 817 | if (tls_session == NULL) |
| 818 | return tls_error(US"tls_session_init", NULL, GNUTLS_E_MEMORY_ERROR); |
| 819 | |
| 820 | /* Set context and tell client to go ahead, except in the case of TLS startup |
| 821 | on connection, where outputting anything now upsets the clients and tends to |
| 822 | make them disconnect. We need to have an explicit fflush() here, to force out |
| 823 | the response. Other smtp_printf() calls do not need it, because in non-TLS |
| 824 | mode, the fflush() happens when smtp_getc() is called. */ |
| 825 | |
| 826 | if (!tls_on_connect) |
| 827 | { |
| 828 | smtp_printf("220 TLS go ahead\r\n"); |
| 829 | fflush(smtp_out); |
| 830 | } |
| 831 | |
| 832 | /* Now negotiate the TLS session. We put our own timer on it, since it seems |
| 833 | that the GnuTLS library doesn't. */ |
| 834 | |
| 835 | gnutls_transport_set_ptr(tls_session, (gnutls_transport_ptr)fileno(smtp_out)); |
| 836 | |
| 837 | sigalrm_seen = FALSE; |
| 838 | if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout); |
| 839 | rc = gnutls_handshake(tls_session); |
| 840 | alarm(0); |
| 841 | |
| 842 | if (rc < 0) |
| 843 | { |
| 844 | if (sigalrm_seen) |
| 845 | Ustrcpy(ssl_errstring, "timed out"); |
| 846 | else |
| 847 | Ustrcpy(ssl_errstring, gnutls_strerror(rc)); |
| 848 | log_write(0, LOG_MAIN, |
| 849 | "TLS error on connection from %s (gnutls_handshake): %s", |
| 850 | (sender_fullhost != NULL)? sender_fullhost : US"local process", |
| 851 | ssl_errstring); |
| 852 | |
| 853 | /* It seems that, except in the case of a timeout, we have to close the |
| 854 | connection right here; otherwise if the other end is running OpenSSL it hangs |
| 855 | until the server times out. */ |
| 856 | |
| 857 | if (!sigalrm_seen) |
| 858 | { |
| 859 | fclose(smtp_out); |
| 860 | fclose(smtp_in); |
| 861 | } |
| 862 | |
| 863 | return FAIL; |
| 864 | } |
| 865 | |
| 866 | DEBUG(D_tls) debug_printf("gnutls_handshake was successful\n"); |
| 867 | |
| 868 | if (verify_requirement != VERIFY_NONE && |
| 869 | !verify_certificate(tls_session, &error)) |
| 870 | { |
| 871 | log_write(0, LOG_MAIN, |
| 872 | "TLS error on connection from %s: certificate verification failed (%s)", |
| 873 | (sender_fullhost != NULL)? sender_fullhost : US"local process", error); |
| 874 | return FAIL; |
| 875 | } |
| 876 | |
| 877 | construct_cipher_name(tls_session); |
| 878 | |
| 879 | /* TLS has been set up. Adjust the input functions to read via TLS, |
| 880 | and initialize appropriately. */ |
| 881 | |
| 882 | ssl_xfer_buffer = store_malloc(ssl_xfer_buffer_size); |
| 883 | ssl_xfer_buffer_lwm = ssl_xfer_buffer_hwm = 0; |
| 884 | ssl_xfer_eof = ssl_xfer_error = 0; |
| 885 | |
| 886 | receive_getc = tls_getc; |
| 887 | receive_ungetc = tls_ungetc; |
| 888 | receive_feof = tls_feof; |
| 889 | receive_ferror = tls_ferror; |
| 890 | |
| 891 | tls_active = fileno(smtp_out); |
| 892 | |
| 893 | return OK; |
| 894 | } |
| 895 | |
| 896 | |
| 897 | |
| 898 | |
| 899 | /************************************************* |
| 900 | * Start a TLS session in a client * |
| 901 | *************************************************/ |
| 902 | |
| 903 | /* Called from the smtp transport after STARTTLS has been accepted. |
| 904 | |
| 905 | Arguments: |
| 906 | fd the fd of the connection |
| 907 | host connected host (for messages) |
| 908 | addr |
| 909 | dhparam DH parameter file |
| 910 | certificate certificate file |
| 911 | privatekey private key file |
| 912 | verify_certs file for certificate verify |
| 913 | verify_crl CRL for verify |
| 914 | require_ciphers list of allowed ciphers |
| 915 | timeout startup timeout |
| 916 | |
| 917 | Returns: OK/DEFER/FAIL (because using common functions), |
| 918 | but for a client, DEFER and FAIL have the same meaning |
| 919 | */ |
| 920 | |
| 921 | int |
| 922 | tls_client_start(int fd, host_item *host, address_item *addr, uschar *dhparam, |
| 923 | uschar *certificate, uschar *privatekey, uschar *verify_certs, |
| 924 | uschar *verify_crl, uschar *require_ciphers, int timeout) |
| 925 | { |
| 926 | const gnutls_datum *server_certs; |
| 927 | uschar *expciphers = NULL; |
| 928 | uschar *error; |
| 929 | unsigned int server_certs_size; |
| 930 | int rc; |
| 931 | |
| 932 | DEBUG(D_tls) debug_printf("initializing GnuTLS as a client\n"); |
| 933 | |
| 934 | client_host = host; |
| 935 | verify_requirement = (verify_certs == NULL)? VERIFY_NONE : VERIFY_REQUIRED; |
| 936 | rc = tls_init(host, certificate, privatekey, verify_certs, verify_crl); |
| 937 | if (rc != OK) return rc; |
| 938 | |
| 939 | if (!expand_check(require_ciphers, US"tls_require_ciphers", &expciphers)) |
| 940 | return FAIL; |
| 941 | |
| 942 | tls_session = tls_session_init(GNUTLS_CLIENT, expciphers); |
| 943 | if (tls_session == NULL) |
| 944 | return tls_error(US "tls_session_init", host, GNUTLS_E_MEMORY_ERROR); |
| 945 | |
| 946 | gnutls_transport_set_ptr(tls_session, (gnutls_transport_ptr)fd); |
| 947 | |
| 948 | /* There doesn't seem to be a built-in timeout on connection. */ |
| 949 | |
| 950 | sigalrm_seen = FALSE; |
| 951 | alarm(timeout); |
| 952 | rc = gnutls_handshake(tls_session); |
| 953 | alarm(0); |
| 954 | |
| 955 | if (rc < 0) |
| 956 | { |
| 957 | if (sigalrm_seen) |
| 958 | { |
| 959 | log_write(0, LOG_MAIN, "TLS error on connection to %s [%s]: " |
| 960 | "gnutls_handshake timed out", host->name, host->address); |
| 961 | return FAIL; |
| 962 | } |
| 963 | else return tls_error(US "gnutls_handshake", host, rc); |
| 964 | } |
| 965 | |
| 966 | server_certs = gnutls_certificate_get_peers(tls_session, &server_certs_size); |
| 967 | |
| 968 | if (server_certs != NULL) |
| 969 | { |
| 970 | uschar buff[1024]; |
| 971 | gnutls_x509_crt gcert; |
| 972 | |
| 973 | gnutls_x509_crt_init(&gcert); |
| 974 | tls_peerdn = US"unknown"; |
| 975 | |
| 976 | if (gnutls_x509_crt_import(gcert, server_certs, GNUTLS_X509_FMT_DER) == 0) |
| 977 | { |
| 978 | size_t bufsize = sizeof(buff); |
| 979 | if (gnutls_x509_crt_get_dn(gcert, CS buff, &bufsize) >= 0) |
| 980 | tls_peerdn = string_copy_malloc(buff); |
| 981 | } |
| 982 | } |
| 983 | |
| 984 | /* Should we also verify the hostname here? */ |
| 985 | |
| 986 | if (verify_requirement != VERIFY_NONE && |
| 987 | !verify_certificate(tls_session, &error)) |
| 988 | { |
| 989 | log_write(0, LOG_MAIN, |
| 990 | "TLS error on connection to %s [%s]: certificate verification failed (%s)", |
| 991 | host->name, host->address, error); |
| 992 | return FAIL; |
| 993 | } |
| 994 | |
| 995 | construct_cipher_name(tls_session); /* Sets tls_cipher */ |
| 996 | tls_active = fd; |
| 997 | return OK; |
| 998 | } |
| 999 | |
| 1000 | |
| 1001 | |
| 1002 | /************************************************* |
| 1003 | * Deal with logging errors during I/O * |
| 1004 | *************************************************/ |
| 1005 | |
| 1006 | /* We have to get the identity of the peer from saved data. |
| 1007 | |
| 1008 | Argument: |
| 1009 | ec the GnuTLS error code, or 0 if it's a local error |
| 1010 | when text identifying read or write |
| 1011 | text local error text when ec is 0 |
| 1012 | |
| 1013 | Returns: nothing |
| 1014 | */ |
| 1015 | |
| 1016 | static void |
| 1017 | record_io_error(int ec, uschar *when, uschar *text) |
| 1018 | { |
| 1019 | uschar *additional = US""; |
| 1020 | |
| 1021 | if (ec == GNUTLS_E_FATAL_ALERT_RECEIVED) |
| 1022 | additional = string_sprintf(": %s", |
| 1023 | gnutls_alert_get_name(gnutls_alert_get(tls_session))); |
| 1024 | |
| 1025 | if (initialized == INITIALIZED_SERVER) |
| 1026 | log_write(0, LOG_MAIN, "TLS %s error on connection from %s: %s%s", when, |
| 1027 | (sender_fullhost != NULL)? sender_fullhost : US "local process", |
| 1028 | (ec == 0)? text : US gnutls_strerror(ec), additional); |
| 1029 | |
| 1030 | else |
| 1031 | log_write(0, LOG_MAIN, "TLS %s error on connection to %s [%s]: %s%s", when, |
| 1032 | client_host->name, client_host->address, |
| 1033 | (ec == 0)? text : US gnutls_strerror(ec), additional); |
| 1034 | } |
| 1035 | |
| 1036 | |
| 1037 | |
| 1038 | /************************************************* |
| 1039 | * TLS version of getc * |
| 1040 | *************************************************/ |
| 1041 | |
| 1042 | /* This gets the next byte from the TLS input buffer. If the buffer is empty, |
| 1043 | it refills the buffer via the GnuTLS reading function. |
| 1044 | |
| 1045 | Arguments: none |
| 1046 | Returns: the next character or EOF |
| 1047 | */ |
| 1048 | |
| 1049 | int |
| 1050 | tls_getc(void) |
| 1051 | { |
| 1052 | if (ssl_xfer_buffer_lwm >= ssl_xfer_buffer_hwm) |
| 1053 | { |
| 1054 | int inbytes; |
| 1055 | |
| 1056 | DEBUG(D_tls) debug_printf("Calling gnutls_record_recv(%lx, %lx, %u)\n", |
| 1057 | (long) tls_session, (long) ssl_xfer_buffer, ssl_xfer_buffer_size); |
| 1058 | |
| 1059 | if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout); |
| 1060 | inbytes = gnutls_record_recv(tls_session, CS ssl_xfer_buffer, |
| 1061 | ssl_xfer_buffer_size); |
| 1062 | alarm(0); |
| 1063 | |
| 1064 | /* A zero-byte return appears to mean that the TLS session has been |
| 1065 | closed down, not that the socket itself has been closed down. Revert to |
| 1066 | non-TLS handling. */ |
| 1067 | |
| 1068 | if (inbytes == 0) |
| 1069 | { |
| 1070 | DEBUG(D_tls) debug_printf("Got TLS_EOF\n"); |
| 1071 | |
| 1072 | receive_getc = smtp_getc; |
| 1073 | receive_ungetc = smtp_ungetc; |
| 1074 | receive_feof = smtp_feof; |
| 1075 | receive_ferror = smtp_ferror; |
| 1076 | |
| 1077 | gnutls_deinit(tls_session); |
| 1078 | tls_session = NULL; |
| 1079 | tls_active = -1; |
| 1080 | tls_cipher = NULL; |
| 1081 | tls_peerdn = NULL; |
| 1082 | |
| 1083 | return smtp_getc(); |
| 1084 | } |
| 1085 | |
| 1086 | /* Handle genuine errors */ |
| 1087 | |
| 1088 | else if (inbytes < 0) |
| 1089 | { |
| 1090 | record_io_error(inbytes, US"recv", NULL); |
| 1091 | ssl_xfer_error = 1; |
| 1092 | return EOF; |
| 1093 | } |
| 1094 | |
| 1095 | ssl_xfer_buffer_hwm = inbytes; |
| 1096 | ssl_xfer_buffer_lwm = 0; |
| 1097 | } |
| 1098 | |
| 1099 | |
| 1100 | /* Something in the buffer; return next uschar */ |
| 1101 | |
| 1102 | return ssl_xfer_buffer[ssl_xfer_buffer_lwm++]; |
| 1103 | } |
| 1104 | |
| 1105 | |
| 1106 | |
| 1107 | /************************************************* |
| 1108 | * Read bytes from TLS channel * |
| 1109 | *************************************************/ |
| 1110 | |
| 1111 | /* |
| 1112 | Arguments: |
| 1113 | buff buffer of data |
| 1114 | len size of buffer |
| 1115 | |
| 1116 | Returns: the number of bytes read |
| 1117 | -1 after a failed read |
| 1118 | */ |
| 1119 | |
| 1120 | int |
| 1121 | tls_read(uschar *buff, size_t len) |
| 1122 | { |
| 1123 | int inbytes; |
| 1124 | |
| 1125 | DEBUG(D_tls) debug_printf("Calling gnutls_record_recv(%lx, %lx, %u)\n", |
| 1126 | (long) tls_session, (long) buff, len); |
| 1127 | |
| 1128 | inbytes = gnutls_record_recv(tls_session, CS buff, len); |
| 1129 | if (inbytes > 0) return inbytes; |
| 1130 | if (inbytes == 0) |
| 1131 | { |
| 1132 | DEBUG(D_tls) debug_printf("Got TLS_EOF\n"); |
| 1133 | } |
| 1134 | else record_io_error(inbytes, US"recv", NULL); |
| 1135 | |
| 1136 | return -1; |
| 1137 | } |
| 1138 | |
| 1139 | |
| 1140 | |
| 1141 | /************************************************* |
| 1142 | * Write bytes down TLS channel * |
| 1143 | *************************************************/ |
| 1144 | |
| 1145 | /* |
| 1146 | Arguments: |
| 1147 | buff buffer of data |
| 1148 | len number of bytes |
| 1149 | |
| 1150 | Returns: the number of bytes after a successful write, |
| 1151 | -1 after a failed write |
| 1152 | */ |
| 1153 | |
| 1154 | int |
| 1155 | tls_write(const uschar *buff, size_t len) |
| 1156 | { |
| 1157 | int outbytes; |
| 1158 | int left = len; |
| 1159 | |
| 1160 | DEBUG(D_tls) debug_printf("tls_do_write(%lx, %d)\n", (long) buff, left); |
| 1161 | while (left > 0) |
| 1162 | { |
| 1163 | DEBUG(D_tls) debug_printf("gnutls_record_send(SSL, %lx, %d)\n", (long)buff, |
| 1164 | left); |
| 1165 | outbytes = gnutls_record_send(tls_session, CS buff, left); |
| 1166 | |
| 1167 | DEBUG(D_tls) debug_printf("outbytes=%d\n", outbytes); |
| 1168 | if (outbytes < 0) |
| 1169 | { |
| 1170 | record_io_error(outbytes, US"send", NULL); |
| 1171 | return -1; |
| 1172 | } |
| 1173 | if (outbytes == 0) |
| 1174 | { |
| 1175 | record_io_error(0, US"send", US"TLS channel closed on write"); |
| 1176 | return -1; |
| 1177 | } |
| 1178 | |
| 1179 | left -= outbytes; |
| 1180 | buff += outbytes; |
| 1181 | } |
| 1182 | |
| 1183 | return len; |
| 1184 | } |
| 1185 | |
| 1186 | |
| 1187 | |
| 1188 | /************************************************* |
| 1189 | * Close down a TLS session * |
| 1190 | *************************************************/ |
| 1191 | |
| 1192 | /* This is also called from within a delivery subprocess forked from the |
| 1193 | daemon, to shut down the TLS library, without actually doing a shutdown (which |
| 1194 | would tamper with the TLS session in the parent process). |
| 1195 | |
| 1196 | Arguments: TRUE if gnutls_bye is to be called |
| 1197 | Returns: nothing |
| 1198 | */ |
| 1199 | |
| 1200 | void |
| 1201 | tls_close(BOOL shutdown) |
| 1202 | { |
| 1203 | if (tls_active < 0) return; /* TLS was not active */ |
| 1204 | |
| 1205 | if (shutdown) |
| 1206 | { |
| 1207 | DEBUG(D_tls) debug_printf("tls_close(): shutting down TLS\n"); |
| 1208 | gnutls_bye(tls_session, GNUTLS_SHUT_WR); |
| 1209 | } |
| 1210 | |
| 1211 | gnutls_deinit(tls_session); |
| 1212 | tls_session = NULL; |
| 1213 | gnutls_global_deinit(); |
| 1214 | |
| 1215 | tls_active = -1; |
| 1216 | } |
| 1217 | |
| 1218 | /* End of tls-gnu.c */ |