Commit | Line | Data |
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059ec3d9 PH |
1 | /************************************************* |
2 | * Exim - an Internet mail transport agent * | |
3 | *************************************************/ | |
4 | ||
c4ceed07 | 5 | /* Copyright (c) University of Cambridge 1995 - 2012 */ |
059ec3d9 PH |
6 | /* See the file NOTICE for conditions of use and distribution. */ |
7 | ||
8 | /* This module provides the TLS (aka SSL) support for Exim using the OpenSSL | |
9 | library. It is #included into the tls.c file when that library is used. The | |
10 | code herein is based on a patch that was originally contributed by Steve | |
11 | Haslam. It was adapted from stunnel, a GPL program by Michal Trojnara. | |
12 | ||
13 | No cryptographic code is included in Exim. All this module does is to call | |
14 | functions from the OpenSSL library. */ | |
15 | ||
16 | ||
17 | /* Heading stuff */ | |
18 | ||
19 | #include <openssl/lhash.h> | |
20 | #include <openssl/ssl.h> | |
21 | #include <openssl/err.h> | |
22 | #include <openssl/rand.h> | |
3f7eeb86 PP |
23 | #ifdef EXPERIMENTAL_OCSP |
24 | #include <openssl/ocsp.h> | |
25 | #endif | |
26 | ||
27 | #ifdef EXPERIMENTAL_OCSP | |
28 | #define EXIM_OCSP_SKEW_SECONDS (300L) | |
29 | #define EXIM_OCSP_MAX_AGE (-1L) | |
30 | #endif | |
059ec3d9 | 31 | |
3bcbbbe2 PP |
32 | #if OPENSSL_VERSION_NUMBER >= 0x0090806fL && !defined(OPENSSL_NO_TLSEXT) |
33 | #define EXIM_HAVE_OPENSSL_TLSEXT | |
34 | #endif | |
35 | ||
059ec3d9 PH |
36 | /* Structure for collecting random data for seeding. */ |
37 | ||
38 | typedef struct randstuff { | |
9e3331ea TK |
39 | struct timeval tv; |
40 | pid_t p; | |
059ec3d9 PH |
41 | } randstuff; |
42 | ||
43 | /* Local static variables */ | |
44 | ||
45 | static BOOL verify_callback_called = FALSE; | |
46 | static const uschar *sid_ctx = US"exim"; | |
47 | ||
48 | static SSL_CTX *ctx = NULL; | |
35731706 | 49 | #ifdef EXIM_HAVE_OPENSSL_TLSEXT |
7be682ca | 50 | static SSL_CTX *ctx_sni = NULL; |
35731706 | 51 | #endif |
059ec3d9 PH |
52 | static SSL *ssl = NULL; |
53 | ||
54 | static char ssl_errstring[256]; | |
55 | ||
56 | static int ssl_session_timeout = 200; | |
57 | static BOOL verify_optional = FALSE; | |
58 | ||
7be682ca | 59 | static BOOL reexpand_tls_files_for_sni = FALSE; |
059ec3d9 PH |
60 | |
61 | ||
7be682ca PP |
62 | typedef struct tls_ext_ctx_cb { |
63 | uschar *certificate; | |
64 | uschar *privatekey; | |
3f7eeb86 PP |
65 | #ifdef EXPERIMENTAL_OCSP |
66 | uschar *ocsp_file; | |
67 | uschar *ocsp_file_expanded; | |
68 | OCSP_RESPONSE *ocsp_response; | |
69 | #endif | |
7be682ca PP |
70 | uschar *dhparam; |
71 | /* these are cached from first expand */ | |
72 | uschar *server_cipher_list; | |
73 | /* only passed down to tls_error: */ | |
74 | host_item *host; | |
75 | } tls_ext_ctx_cb; | |
76 | ||
77 | /* should figure out a cleanup of API to handle state preserved per | |
78 | implementation, for various reasons, which can be void * in the APIs. | |
79 | For now, we hack around it. */ | |
80 | tls_ext_ctx_cb *static_cbinfo = NULL; | |
81 | ||
82 | static int | |
83 | setup_certs(SSL_CTX *sctx, uschar *certs, uschar *crl, host_item *host, BOOL optional); | |
059ec3d9 | 84 | |
3f7eeb86 | 85 | /* Callbacks */ |
3bcbbbe2 | 86 | #ifdef EXIM_HAVE_OPENSSL_TLSEXT |
3f7eeb86 | 87 | static int tls_servername_cb(SSL *s, int *ad ARG_UNUSED, void *arg); |
3bcbbbe2 | 88 | #endif |
3f7eeb86 PP |
89 | #ifdef EXPERIMENTAL_OCSP |
90 | static int tls_stapling_cb(SSL *s, void *arg); | |
91 | #endif | |
92 | ||
059ec3d9 PH |
93 | |
94 | /************************************************* | |
95 | * Handle TLS error * | |
96 | *************************************************/ | |
97 | ||
98 | /* Called from lots of places when errors occur before actually starting to do | |
99 | the TLS handshake, that is, while the session is still in clear. Always returns | |
100 | DEFER for a server and FAIL for a client so that most calls can use "return | |
101 | tls_error(...)" to do this processing and then give an appropriate return. A | |
102 | single function is used for both server and client, because it is called from | |
103 | some shared functions. | |
104 | ||
105 | Argument: | |
106 | prefix text to include in the logged error | |
107 | host NULL if setting up a server; | |
108 | the connected host if setting up a client | |
7199e1ee | 109 | msg error message or NULL if we should ask OpenSSL |
059ec3d9 PH |
110 | |
111 | Returns: OK/DEFER/FAIL | |
112 | */ | |
113 | ||
114 | static int | |
7199e1ee | 115 | tls_error(uschar *prefix, host_item *host, uschar *msg) |
059ec3d9 | 116 | { |
7199e1ee TF |
117 | if (msg == NULL) |
118 | { | |
119 | ERR_error_string(ERR_get_error(), ssl_errstring); | |
5ca6d115 | 120 | msg = (uschar *)ssl_errstring; |
7199e1ee TF |
121 | } |
122 | ||
059ec3d9 PH |
123 | if (host == NULL) |
124 | { | |
7199e1ee | 125 | uschar *conn_info = smtp_get_connection_info(); |
5ca6d115 | 126 | if (Ustrncmp(conn_info, US"SMTP ", 5) == 0) |
7199e1ee TF |
127 | conn_info += 5; |
128 | log_write(0, LOG_MAIN, "TLS error on %s (%s): %s", | |
129 | conn_info, prefix, msg); | |
059ec3d9 PH |
130 | return DEFER; |
131 | } | |
132 | else | |
133 | { | |
134 | log_write(0, LOG_MAIN, "TLS error on connection to %s [%s] (%s): %s", | |
7199e1ee | 135 | host->name, host->address, prefix, msg); |
059ec3d9 PH |
136 | return FAIL; |
137 | } | |
138 | } | |
139 | ||
140 | ||
141 | ||
142 | /************************************************* | |
143 | * Callback to generate RSA key * | |
144 | *************************************************/ | |
145 | ||
146 | /* | |
147 | Arguments: | |
148 | s SSL connection | |
149 | export not used | |
150 | keylength keylength | |
151 | ||
152 | Returns: pointer to generated key | |
153 | */ | |
154 | ||
155 | static RSA * | |
156 | rsa_callback(SSL *s, int export, int keylength) | |
157 | { | |
158 | RSA *rsa_key; | |
159 | export = export; /* Shut picky compilers up */ | |
160 | DEBUG(D_tls) debug_printf("Generating %d bit RSA key...\n", keylength); | |
161 | rsa_key = RSA_generate_key(keylength, RSA_F4, NULL, NULL); | |
162 | if (rsa_key == NULL) | |
163 | { | |
164 | ERR_error_string(ERR_get_error(), ssl_errstring); | |
165 | log_write(0, LOG_MAIN|LOG_PANIC, "TLS error (RSA_generate_key): %s", | |
166 | ssl_errstring); | |
167 | return NULL; | |
168 | } | |
169 | return rsa_key; | |
170 | } | |
171 | ||
172 | ||
173 | ||
174 | ||
175 | /************************************************* | |
176 | * Callback for verification * | |
177 | *************************************************/ | |
178 | ||
179 | /* The SSL library does certificate verification if set up to do so. This | |
180 | callback has the current yes/no state is in "state". If verification succeeded, | |
181 | we set up the tls_peerdn string. If verification failed, what happens depends | |
182 | on whether the client is required to present a verifiable certificate or not. | |
183 | ||
184 | If verification is optional, we change the state to yes, but still log the | |
185 | verification error. For some reason (it really would help to have proper | |
186 | documentation of OpenSSL), this callback function then gets called again, this | |
187 | time with state = 1. In fact, that's useful, because we can set up the peerdn | |
188 | value, but we must take care not to set the private verified flag on the second | |
189 | time through. | |
190 | ||
191 | Note: this function is not called if the client fails to present a certificate | |
192 | when asked. We get here only if a certificate has been received. Handling of | |
193 | optional verification for this case is done when requesting SSL to verify, by | |
194 | setting SSL_VERIFY_FAIL_IF_NO_PEER_CERT in the non-optional case. | |
195 | ||
196 | Arguments: | |
197 | state current yes/no state as 1/0 | |
198 | x509ctx certificate information. | |
199 | ||
200 | Returns: 1 if verified, 0 if not | |
201 | */ | |
202 | ||
203 | static int | |
204 | verify_callback(int state, X509_STORE_CTX *x509ctx) | |
205 | { | |
206 | static uschar txt[256]; | |
207 | ||
208 | X509_NAME_oneline(X509_get_subject_name(x509ctx->current_cert), | |
209 | CS txt, sizeof(txt)); | |
210 | ||
211 | if (state == 0) | |
212 | { | |
213 | log_write(0, LOG_MAIN, "SSL verify error: depth=%d error=%s cert=%s", | |
214 | x509ctx->error_depth, | |
215 | X509_verify_cert_error_string(x509ctx->error), | |
216 | txt); | |
217 | tls_certificate_verified = FALSE; | |
218 | verify_callback_called = TRUE; | |
219 | if (!verify_optional) return 0; /* reject */ | |
220 | DEBUG(D_tls) debug_printf("SSL verify failure overridden (host in " | |
221 | "tls_try_verify_hosts)\n"); | |
222 | return 1; /* accept */ | |
223 | } | |
224 | ||
225 | if (x509ctx->error_depth != 0) | |
226 | { | |
227 | DEBUG(D_tls) debug_printf("SSL verify ok: depth=%d cert=%s\n", | |
228 | x509ctx->error_depth, txt); | |
229 | } | |
230 | else | |
231 | { | |
232 | DEBUG(D_tls) debug_printf("SSL%s peer: %s\n", | |
233 | verify_callback_called? "" : " authenticated", txt); | |
234 | tls_peerdn = txt; | |
235 | } | |
236 | ||
059ec3d9 PH |
237 | if (!verify_callback_called) tls_certificate_verified = TRUE; |
238 | verify_callback_called = TRUE; | |
239 | ||
240 | return 1; /* accept */ | |
241 | } | |
242 | ||
243 | ||
244 | ||
245 | /************************************************* | |
246 | * Information callback * | |
247 | *************************************************/ | |
248 | ||
249 | /* The SSL library functions call this from time to time to indicate what they | |
7be682ca PP |
250 | are doing. We copy the string to the debugging output when TLS debugging has |
251 | been requested. | |
059ec3d9 PH |
252 | |
253 | Arguments: | |
254 | s the SSL connection | |
255 | where | |
256 | ret | |
257 | ||
258 | Returns: nothing | |
259 | */ | |
260 | ||
261 | static void | |
262 | info_callback(SSL *s, int where, int ret) | |
263 | { | |
264 | where = where; | |
265 | ret = ret; | |
266 | DEBUG(D_tls) debug_printf("SSL info: %s\n", SSL_state_string_long(s)); | |
267 | } | |
268 | ||
269 | ||
270 | ||
271 | /************************************************* | |
272 | * Initialize for DH * | |
273 | *************************************************/ | |
274 | ||
275 | /* If dhparam is set, expand it, and load up the parameters for DH encryption. | |
276 | ||
277 | Arguments: | |
a799883d | 278 | dhparam DH parameter file or fixed parameter identity string |
7199e1ee | 279 | host connected host, if client; NULL if server |
059ec3d9 PH |
280 | |
281 | Returns: TRUE if OK (nothing to set up, or setup worked) | |
282 | */ | |
283 | ||
284 | static BOOL | |
a799883d | 285 | init_dh(SSL_CTX *sctx, uschar *dhparam, host_item *host) |
059ec3d9 | 286 | { |
059ec3d9 PH |
287 | BIO *bio; |
288 | DH *dh; | |
289 | uschar *dhexpanded; | |
a799883d | 290 | const char *pem; |
059ec3d9 PH |
291 | |
292 | if (!expand_check(dhparam, US"tls_dhparam", &dhexpanded)) | |
293 | return FALSE; | |
294 | ||
a799883d | 295 | if (dhexpanded == NULL || *dhexpanded == '\0') |
059ec3d9 | 296 | { |
a799883d | 297 | bio = BIO_new_mem_buf(CS std_dh_prime_default(), -1); |
059ec3d9 | 298 | } |
a799883d | 299 | else if (dhexpanded[0] == '/') |
059ec3d9 | 300 | { |
a799883d PP |
301 | bio = BIO_new_file(CS dhexpanded, "r"); |
302 | if (bio == NULL) | |
059ec3d9 | 303 | { |
7199e1ee | 304 | tls_error(string_sprintf("could not read dhparams file %s", dhexpanded), |
a799883d PP |
305 | host, US strerror(errno)); |
306 | return FALSE; | |
059ec3d9 | 307 | } |
a799883d PP |
308 | } |
309 | else | |
310 | { | |
311 | if (Ustrcmp(dhexpanded, "none") == 0) | |
059ec3d9 | 312 | { |
a799883d PP |
313 | DEBUG(D_tls) debug_printf("Requested no DH parameters.\n"); |
314 | return TRUE; | |
059ec3d9 | 315 | } |
a799883d PP |
316 | |
317 | pem = std_dh_prime_named(dhexpanded); | |
318 | if (!pem) | |
319 | { | |
320 | tls_error(string_sprintf("Unknown standard DH prime \"%s\"", dhexpanded), | |
321 | host, US strerror(errno)); | |
322 | return FALSE; | |
323 | } | |
324 | bio = BIO_new_mem_buf(CS pem, -1); | |
325 | } | |
326 | ||
327 | dh = PEM_read_bio_DHparams(bio, NULL, NULL, NULL); | |
328 | if (dh == NULL) | |
329 | { | |
059ec3d9 | 330 | BIO_free(bio); |
a799883d PP |
331 | tls_error(string_sprintf("Could not read tls_dhparams \"%s\"", dhexpanded), |
332 | host, NULL); | |
333 | return FALSE; | |
334 | } | |
335 | ||
336 | /* Even if it is larger, we silently return success rather than cause things | |
337 | * to fail out, so that a too-large DH will not knock out all TLS; it's a | |
338 | * debatable choice. */ | |
339 | if ((8*DH_size(dh)) > tls_dh_max_bits) | |
340 | { | |
341 | DEBUG(D_tls) | |
342 | debug_printf("dhparams file %d bits, is > tls_dh_max_bits limit of %d", | |
343 | 8*DH_size(dh), tls_dh_max_bits); | |
344 | } | |
345 | else | |
346 | { | |
347 | SSL_CTX_set_tmp_dh(sctx, dh); | |
348 | DEBUG(D_tls) | |
349 | debug_printf("Diffie-Hellman initialized from %s with %d-bit prime\n", | |
350 | dhexpanded ? dhexpanded : US"default", 8*DH_size(dh)); | |
059ec3d9 PH |
351 | } |
352 | ||
a799883d PP |
353 | DH_free(dh); |
354 | BIO_free(bio); | |
355 | ||
356 | return TRUE; | |
059ec3d9 PH |
357 | } |
358 | ||
359 | ||
360 | ||
361 | ||
3f7eeb86 PP |
362 | #ifdef EXPERIMENTAL_OCSP |
363 | /************************************************* | |
364 | * Load OCSP information into state * | |
365 | *************************************************/ | |
366 | ||
367 | /* Called to load the OCSP response from the given file into memory, once | |
368 | caller has determined this is needed. Checks validity. Debugs a message | |
369 | if invalid. | |
370 | ||
371 | ASSUMES: single response, for single cert. | |
372 | ||
373 | Arguments: | |
374 | sctx the SSL_CTX* to update | |
375 | cbinfo various parts of session state | |
376 | expanded the filename putatively holding an OCSP response | |
377 | ||
378 | */ | |
379 | ||
380 | static void | |
381 | ocsp_load_response(SSL_CTX *sctx, | |
382 | tls_ext_ctx_cb *cbinfo, | |
383 | const uschar *expanded) | |
384 | { | |
385 | BIO *bio; | |
386 | OCSP_RESPONSE *resp; | |
387 | OCSP_BASICRESP *basic_response; | |
388 | OCSP_SINGLERESP *single_response; | |
389 | ASN1_GENERALIZEDTIME *rev, *thisupd, *nextupd; | |
390 | X509_STORE *store; | |
391 | unsigned long verify_flags; | |
392 | int status, reason, i; | |
393 | ||
394 | cbinfo->ocsp_file_expanded = string_copy(expanded); | |
395 | if (cbinfo->ocsp_response) | |
396 | { | |
397 | OCSP_RESPONSE_free(cbinfo->ocsp_response); | |
398 | cbinfo->ocsp_response = NULL; | |
399 | } | |
400 | ||
401 | bio = BIO_new_file(CS cbinfo->ocsp_file_expanded, "rb"); | |
402 | if (!bio) | |
403 | { | |
404 | DEBUG(D_tls) debug_printf("Failed to open OCSP response file \"%s\"\n", | |
405 | cbinfo->ocsp_file_expanded); | |
406 | return; | |
407 | } | |
408 | ||
409 | resp = d2i_OCSP_RESPONSE_bio(bio, NULL); | |
410 | BIO_free(bio); | |
411 | if (!resp) | |
412 | { | |
413 | DEBUG(D_tls) debug_printf("Error reading OCSP response.\n"); | |
414 | return; | |
415 | } | |
416 | ||
417 | status = OCSP_response_status(resp); | |
418 | if (status != OCSP_RESPONSE_STATUS_SUCCESSFUL) | |
419 | { | |
420 | DEBUG(D_tls) debug_printf("OCSP response not valid: %s (%d)\n", | |
421 | OCSP_response_status_str(status), status); | |
422 | return; | |
423 | } | |
424 | ||
425 | basic_response = OCSP_response_get1_basic(resp); | |
426 | if (!basic_response) | |
427 | { | |
428 | DEBUG(D_tls) | |
429 | debug_printf("OCSP response parse error: unable to extract basic response.\n"); | |
430 | return; | |
431 | } | |
432 | ||
433 | store = SSL_CTX_get_cert_store(sctx); | |
434 | verify_flags = OCSP_NOVERIFY; /* check sigs, but not purpose */ | |
435 | ||
436 | /* May need to expose ability to adjust those flags? | |
437 | OCSP_NOSIGS OCSP_NOVERIFY OCSP_NOCHAIN OCSP_NOCHECKS OCSP_NOEXPLICIT | |
438 | OCSP_TRUSTOTHER OCSP_NOINTERN */ | |
439 | ||
440 | i = OCSP_basic_verify(basic_response, NULL, store, verify_flags); | |
441 | if (i <= 0) | |
442 | { | |
443 | DEBUG(D_tls) { | |
444 | ERR_error_string(ERR_get_error(), ssl_errstring); | |
445 | debug_printf("OCSP response verify failure: %s\n", US ssl_errstring); | |
446 | } | |
447 | return; | |
448 | } | |
449 | ||
450 | /* Here's the simplifying assumption: there's only one response, for the | |
451 | one certificate we use, and nothing for anything else in a chain. If this | |
452 | proves false, we need to extract a cert id from our issued cert | |
453 | (tls_certificate) and use that for OCSP_resp_find_status() (which finds the | |
454 | right cert in the stack and then calls OCSP_single_get0_status()). | |
455 | ||
456 | I'm hoping to avoid reworking a bunch more of how we handle state here. */ | |
457 | single_response = OCSP_resp_get0(basic_response, 0); | |
458 | if (!single_response) | |
459 | { | |
460 | DEBUG(D_tls) | |
461 | debug_printf("Unable to get first response from OCSP basic response.\n"); | |
462 | return; | |
463 | } | |
464 | ||
465 | status = OCSP_single_get0_status(single_response, &reason, &rev, &thisupd, &nextupd); | |
466 | /* how does this status differ from the one above? */ | |
467 | if (status != OCSP_RESPONSE_STATUS_SUCCESSFUL) | |
468 | { | |
469 | DEBUG(D_tls) debug_printf("OCSP response not valid (take 2): %s (%d)\n", | |
470 | OCSP_response_status_str(status), status); | |
471 | return; | |
472 | } | |
473 | ||
474 | if (!OCSP_check_validity(thisupd, nextupd, EXIM_OCSP_SKEW_SECONDS, EXIM_OCSP_MAX_AGE)) | |
475 | { | |
476 | DEBUG(D_tls) debug_printf("OCSP status invalid times.\n"); | |
477 | return; | |
478 | } | |
479 | ||
480 | cbinfo->ocsp_response = resp; | |
481 | } | |
482 | #endif | |
483 | ||
484 | ||
485 | ||
486 | ||
7be682ca PP |
487 | /************************************************* |
488 | * Expand key and cert file specs * | |
489 | *************************************************/ | |
490 | ||
491 | /* Called once during tls_init and possibly againt during TLS setup, for a | |
492 | new context, if Server Name Indication was used and tls_sni was seen in | |
493 | the certificate string. | |
494 | ||
495 | Arguments: | |
496 | sctx the SSL_CTX* to update | |
497 | cbinfo various parts of session state | |
498 | ||
499 | Returns: OK/DEFER/FAIL | |
500 | */ | |
501 | ||
502 | static int | |
3f7eeb86 | 503 | tls_expand_session_files(SSL_CTX *sctx, tls_ext_ctx_cb *cbinfo) |
7be682ca PP |
504 | { |
505 | uschar *expanded; | |
506 | ||
507 | if (cbinfo->certificate == NULL) | |
508 | return OK; | |
509 | ||
510 | if (Ustrstr(cbinfo->certificate, US"tls_sni")) | |
511 | reexpand_tls_files_for_sni = TRUE; | |
512 | ||
513 | if (!expand_check(cbinfo->certificate, US"tls_certificate", &expanded)) | |
514 | return DEFER; | |
515 | ||
516 | if (expanded != NULL) | |
517 | { | |
518 | DEBUG(D_tls) debug_printf("tls_certificate file %s\n", expanded); | |
519 | if (!SSL_CTX_use_certificate_chain_file(sctx, CS expanded)) | |
520 | return tls_error(string_sprintf( | |
521 | "SSL_CTX_use_certificate_chain_file file=%s", expanded), | |
522 | cbinfo->host, NULL); | |
523 | } | |
524 | ||
525 | if (cbinfo->privatekey != NULL && | |
526 | !expand_check(cbinfo->privatekey, US"tls_privatekey", &expanded)) | |
527 | return DEFER; | |
528 | ||
529 | /* If expansion was forced to fail, key_expanded will be NULL. If the result | |
530 | of the expansion is an empty string, ignore it also, and assume the private | |
531 | key is in the same file as the certificate. */ | |
532 | ||
533 | if (expanded != NULL && *expanded != 0) | |
534 | { | |
535 | DEBUG(D_tls) debug_printf("tls_privatekey file %s\n", expanded); | |
536 | if (!SSL_CTX_use_PrivateKey_file(sctx, CS expanded, SSL_FILETYPE_PEM)) | |
537 | return tls_error(string_sprintf( | |
538 | "SSL_CTX_use_PrivateKey_file file=%s", expanded), cbinfo->host, NULL); | |
539 | } | |
540 | ||
3f7eeb86 PP |
541 | #ifdef EXPERIMENTAL_OCSP |
542 | if (cbinfo->ocsp_file != NULL) | |
543 | { | |
544 | if (!expand_check(cbinfo->ocsp_file, US"tls_ocsp_file", &expanded)) | |
545 | return DEFER; | |
546 | ||
547 | if (expanded != NULL && *expanded != 0) | |
548 | { | |
549 | DEBUG(D_tls) debug_printf("tls_ocsp_file %s\n", expanded); | |
550 | if (cbinfo->ocsp_file_expanded && | |
551 | (Ustrcmp(expanded, cbinfo->ocsp_file_expanded) == 0)) | |
552 | { | |
553 | DEBUG(D_tls) | |
554 | debug_printf("tls_ocsp_file value unchanged, using existing values.\n"); | |
555 | } else { | |
556 | ocsp_load_response(sctx, cbinfo, expanded); | |
557 | } | |
558 | } | |
559 | } | |
560 | #endif | |
561 | ||
7be682ca PP |
562 | return OK; |
563 | } | |
564 | ||
565 | ||
566 | ||
567 | ||
568 | /************************************************* | |
569 | * Callback to handle SNI * | |
570 | *************************************************/ | |
571 | ||
572 | /* Called when acting as server during the TLS session setup if a Server Name | |
573 | Indication extension was sent by the client. | |
574 | ||
575 | API documentation is OpenSSL s_server.c implementation. | |
576 | ||
577 | Arguments: | |
578 | s SSL* of the current session | |
579 | ad unknown (part of OpenSSL API) (unused) | |
580 | arg Callback of "our" registered data | |
581 | ||
582 | Returns: SSL_TLSEXT_ERR_{OK,ALERT_WARNING,ALERT_FATAL,NOACK} | |
583 | */ | |
584 | ||
3bcbbbe2 | 585 | #ifdef EXIM_HAVE_OPENSSL_TLSEXT |
7be682ca PP |
586 | static int |
587 | tls_servername_cb(SSL *s, int *ad ARG_UNUSED, void *arg) | |
588 | { | |
589 | const char *servername = SSL_get_servername(s, TLSEXT_NAMETYPE_host_name); | |
3f7eeb86 | 590 | tls_ext_ctx_cb *cbinfo = (tls_ext_ctx_cb *) arg; |
7be682ca | 591 | int rc; |
3f0945ff | 592 | int old_pool = store_pool; |
7be682ca PP |
593 | |
594 | if (!servername) | |
595 | return SSL_TLSEXT_ERR_OK; | |
596 | ||
3f0945ff | 597 | DEBUG(D_tls) debug_printf("Received TLS SNI \"%s\"%s\n", servername, |
7be682ca PP |
598 | reexpand_tls_files_for_sni ? "" : " (unused for certificate selection)"); |
599 | ||
600 | /* Make the extension value available for expansion */ | |
3f0945ff PP |
601 | store_pool = POOL_PERM; |
602 | tls_sni = string_copy(US servername); | |
603 | store_pool = old_pool; | |
7be682ca PP |
604 | |
605 | if (!reexpand_tls_files_for_sni) | |
606 | return SSL_TLSEXT_ERR_OK; | |
607 | ||
608 | /* Can't find an SSL_CTX_clone() or equivalent, so we do it manually; | |
609 | not confident that memcpy wouldn't break some internal reference counting. | |
610 | Especially since there's a references struct member, which would be off. */ | |
611 | ||
612 | ctx_sni = SSL_CTX_new(SSLv23_server_method()); | |
613 | if (!ctx_sni) | |
614 | { | |
615 | ERR_error_string(ERR_get_error(), ssl_errstring); | |
616 | DEBUG(D_tls) debug_printf("SSL_CTX_new() failed: %s\n", ssl_errstring); | |
617 | return SSL_TLSEXT_ERR_NOACK; | |
618 | } | |
619 | ||
620 | /* Not sure how many of these are actually needed, since SSL object | |
621 | already exists. Might even need this selfsame callback, for reneg? */ | |
622 | ||
623 | SSL_CTX_set_info_callback(ctx_sni, SSL_CTX_get_info_callback(ctx)); | |
624 | SSL_CTX_set_mode(ctx_sni, SSL_CTX_get_mode(ctx)); | |
625 | SSL_CTX_set_options(ctx_sni, SSL_CTX_get_options(ctx)); | |
626 | SSL_CTX_set_timeout(ctx_sni, SSL_CTX_get_timeout(ctx)); | |
627 | SSL_CTX_set_tlsext_servername_callback(ctx_sni, tls_servername_cb); | |
628 | SSL_CTX_set_tlsext_servername_arg(ctx_sni, cbinfo); | |
629 | if (cbinfo->server_cipher_list) | |
630 | SSL_CTX_set_cipher_list(ctx_sni, CS cbinfo->server_cipher_list); | |
3f7eeb86 PP |
631 | #ifdef EXPERIMENTAL_OCSP |
632 | if (cbinfo->ocsp_file) | |
633 | { | |
634 | SSL_CTX_set_tlsext_status_cb(ctx_sni, tls_stapling_cb); | |
635 | SSL_CTX_set_tlsext_status_arg(ctx, cbinfo); | |
636 | } | |
637 | #endif | |
7be682ca | 638 | |
3f7eeb86 | 639 | rc = setup_certs(ctx_sni, tls_verify_certificates, tls_crl, NULL, FALSE); |
7be682ca PP |
640 | if (rc != OK) return SSL_TLSEXT_ERR_NOACK; |
641 | ||
3f7eeb86 PP |
642 | /* do this after setup_certs, because this can require the certs for verifying |
643 | OCSP information. */ | |
644 | rc = tls_expand_session_files(ctx_sni, cbinfo); | |
7be682ca PP |
645 | if (rc != OK) return SSL_TLSEXT_ERR_NOACK; |
646 | ||
a799883d PP |
647 | rc = init_dh(ctx_sni, cbinfo->dhparam, NULL); |
648 | if (rc != OK) return SSL_TLSEXT_ERR_NOACK; | |
649 | ||
7be682ca PP |
650 | DEBUG(D_tls) debug_printf("Switching SSL context.\n"); |
651 | SSL_set_SSL_CTX(s, ctx_sni); | |
652 | ||
653 | return SSL_TLSEXT_ERR_OK; | |
654 | } | |
3bcbbbe2 | 655 | #endif /* EXIM_HAVE_OPENSSL_TLSEXT */ |
7be682ca PP |
656 | |
657 | ||
658 | ||
659 | ||
3f7eeb86 PP |
660 | #ifdef EXPERIMENTAL_OCSP |
661 | /************************************************* | |
662 | * Callback to handle OCSP Stapling * | |
663 | *************************************************/ | |
664 | ||
665 | /* Called when acting as server during the TLS session setup if the client | |
666 | requests OCSP information with a Certificate Status Request. | |
667 | ||
668 | Documentation via openssl s_server.c and the Apache patch from the OpenSSL | |
669 | project. | |
670 | ||
671 | */ | |
672 | ||
673 | static int | |
674 | tls_stapling_cb(SSL *s, void *arg) | |
675 | { | |
676 | const tls_ext_ctx_cb *cbinfo = (tls_ext_ctx_cb *) arg; | |
677 | uschar *response_der; | |
678 | int response_der_len; | |
679 | ||
680 | DEBUG(D_tls) debug_printf("Received TLS status request (OCSP stapling); %s response.\n", | |
681 | cbinfo->ocsp_response ? "have" : "lack"); | |
682 | if (!cbinfo->ocsp_response) | |
683 | return SSL_TLSEXT_ERR_NOACK; | |
684 | ||
685 | response_der = NULL; | |
686 | response_der_len = i2d_OCSP_RESPONSE(cbinfo->ocsp_response, &response_der); | |
687 | if (response_der_len <= 0) | |
688 | return SSL_TLSEXT_ERR_NOACK; | |
689 | ||
690 | SSL_set_tlsext_status_ocsp_resp(ssl, response_der, response_der_len); | |
691 | return SSL_TLSEXT_ERR_OK; | |
692 | } | |
693 | ||
694 | #endif /* EXPERIMENTAL_OCSP */ | |
695 | ||
696 | ||
697 | ||
698 | ||
059ec3d9 PH |
699 | /************************************************* |
700 | * Initialize for TLS * | |
701 | *************************************************/ | |
702 | ||
703 | /* Called from both server and client code, to do preliminary initialization of | |
704 | the library. | |
705 | ||
706 | Arguments: | |
707 | host connected host, if client; NULL if server | |
708 | dhparam DH parameter file | |
709 | certificate certificate file | |
710 | privatekey private key | |
711 | addr address if client; NULL if server (for some randomness) | |
712 | ||
713 | Returns: OK/DEFER/FAIL | |
714 | */ | |
715 | ||
716 | static int | |
c91535f3 | 717 | tls_init(host_item *host, uschar *dhparam, uschar *certificate, |
3f7eeb86 PP |
718 | uschar *privatekey, |
719 | #ifdef EXPERIMENTAL_OCSP | |
720 | uschar *ocsp_file, | |
721 | #endif | |
722 | address_item *addr) | |
059ec3d9 | 723 | { |
77bb000f | 724 | long init_options; |
7be682ca | 725 | int rc; |
77bb000f | 726 | BOOL okay; |
7be682ca PP |
727 | tls_ext_ctx_cb *cbinfo; |
728 | ||
729 | cbinfo = store_malloc(sizeof(tls_ext_ctx_cb)); | |
730 | cbinfo->certificate = certificate; | |
731 | cbinfo->privatekey = privatekey; | |
3f7eeb86 PP |
732 | #ifdef EXPERIMENTAL_OCSP |
733 | cbinfo->ocsp_file = ocsp_file; | |
734 | #endif | |
7be682ca PP |
735 | cbinfo->dhparam = dhparam; |
736 | cbinfo->host = host; | |
77bb000f | 737 | |
059ec3d9 PH |
738 | SSL_load_error_strings(); /* basic set up */ |
739 | OpenSSL_add_ssl_algorithms(); | |
740 | ||
388d6564 | 741 | #if (OPENSSL_VERSION_NUMBER >= 0x0090800fL) && !defined(OPENSSL_NO_SHA256) |
77bb000f | 742 | /* SHA256 is becoming ever more popular. This makes sure it gets added to the |
a0475b69 TK |
743 | list of available digests. */ |
744 | EVP_add_digest(EVP_sha256()); | |
cf1ef1a9 | 745 | #endif |
a0475b69 | 746 | |
f0f5a555 PP |
747 | /* Create a context. |
748 | The OpenSSL docs in 1.0.1b have not been updated to clarify TLS variant | |
749 | negotiation in the different methods; as far as I can tell, the only | |
750 | *_{server,client}_method which allows negotiation is SSLv23, which exists even | |
751 | when OpenSSL is built without SSLv2 support. | |
752 | By disabling with openssl_options, we can let admins re-enable with the | |
753 | existing knob. */ | |
059ec3d9 PH |
754 | |
755 | ctx = SSL_CTX_new((host == NULL)? | |
756 | SSLv23_server_method() : SSLv23_client_method()); | |
757 | ||
7199e1ee | 758 | if (ctx == NULL) return tls_error(US"SSL_CTX_new", host, NULL); |
059ec3d9 PH |
759 | |
760 | /* It turns out that we need to seed the random number generator this early in | |
761 | order to get the full complement of ciphers to work. It took me roughly a day | |
762 | of work to discover this by experiment. | |
763 | ||
764 | On systems that have /dev/urandom, SSL may automatically seed itself from | |
765 | there. Otherwise, we have to make something up as best we can. Double check | |
766 | afterwards. */ | |
767 | ||
768 | if (!RAND_status()) | |
769 | { | |
770 | randstuff r; | |
9e3331ea | 771 | gettimeofday(&r.tv, NULL); |
059ec3d9 PH |
772 | r.p = getpid(); |
773 | ||
774 | RAND_seed((uschar *)(&r), sizeof(r)); | |
775 | RAND_seed((uschar *)big_buffer, big_buffer_size); | |
776 | if (addr != NULL) RAND_seed((uschar *)addr, sizeof(addr)); | |
777 | ||
778 | if (!RAND_status()) | |
7199e1ee | 779 | return tls_error(US"RAND_status", host, |
5ca6d115 | 780 | US"unable to seed random number generator"); |
059ec3d9 PH |
781 | } |
782 | ||
783 | /* Set up the information callback, which outputs if debugging is at a suitable | |
784 | level. */ | |
785 | ||
58c01c94 | 786 | SSL_CTX_set_info_callback(ctx, (void (*)())info_callback); |
059ec3d9 | 787 | |
c80c5570 PP |
788 | /* Automatically re-try reads/writes after renegotiation. */ |
789 | (void) SSL_CTX_set_mode(ctx, SSL_MODE_AUTO_RETRY); | |
790 | ||
77bb000f PP |
791 | /* Apply administrator-supplied work-arounds. |
792 | Historically we applied just one requested option, | |
793 | SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS, but when bug 994 requested a second, we | |
794 | moved to an administrator-controlled list of options to specify and | |
795 | grandfathered in the first one as the default value for "openssl_options". | |
059ec3d9 | 796 | |
77bb000f PP |
797 | No OpenSSL version number checks: the options we accept depend upon the |
798 | availability of the option value macros from OpenSSL. */ | |
059ec3d9 | 799 | |
77bb000f PP |
800 | okay = tls_openssl_options_parse(openssl_options, &init_options); |
801 | if (!okay) | |
73a46702 | 802 | return tls_error(US"openssl_options parsing failed", host, NULL); |
77bb000f PP |
803 | |
804 | if (init_options) | |
805 | { | |
806 | DEBUG(D_tls) debug_printf("setting SSL CTX options: %#lx\n", init_options); | |
807 | if (!(SSL_CTX_set_options(ctx, init_options))) | |
808 | return tls_error(string_sprintf( | |
809 | "SSL_CTX_set_option(%#lx)", init_options), host, NULL); | |
810 | } | |
811 | else | |
812 | DEBUG(D_tls) debug_printf("no SSL CTX options to set\n"); | |
059ec3d9 PH |
813 | |
814 | /* Initialize with DH parameters if supplied */ | |
815 | ||
a799883d | 816 | if (!init_dh(ctx, dhparam, host)) return DEFER; |
059ec3d9 | 817 | |
3f7eeb86 | 818 | /* Set up certificate and key (and perhaps OCSP info) */ |
059ec3d9 | 819 | |
7be682ca PP |
820 | rc = tls_expand_session_files(ctx, cbinfo); |
821 | if (rc != OK) return rc; | |
c91535f3 | 822 | |
7be682ca | 823 | /* If we need to handle SNI, do so */ |
3bcbbbe2 | 824 | #ifdef EXIM_HAVE_OPENSSL_TLSEXT |
3f0945ff PP |
825 | if (host == NULL) |
826 | { | |
3f7eeb86 PP |
827 | #ifdef EXPERIMENTAL_OCSP |
828 | /* We check ocsp_file, not ocsp_response, because we care about if | |
829 | the option exists, not what the current expansion might be, as SNI might | |
830 | change the certificate and OCSP file in use between now and the time the | |
831 | callback is invoked. */ | |
832 | if (cbinfo->ocsp_file) | |
833 | { | |
834 | SSL_CTX_set_tlsext_status_cb(ctx, tls_stapling_cb); | |
835 | SSL_CTX_set_tlsext_status_arg(ctx, cbinfo); | |
836 | } | |
837 | #endif | |
3f0945ff PP |
838 | /* We always do this, so that $tls_sni is available even if not used in |
839 | tls_certificate */ | |
840 | SSL_CTX_set_tlsext_servername_callback(ctx, tls_servername_cb); | |
841 | SSL_CTX_set_tlsext_servername_arg(ctx, cbinfo); | |
842 | } | |
7be682ca | 843 | #endif |
059ec3d9 PH |
844 | |
845 | /* Set up the RSA callback */ | |
846 | ||
847 | SSL_CTX_set_tmp_rsa_callback(ctx, rsa_callback); | |
848 | ||
849 | /* Finally, set the timeout, and we are done */ | |
850 | ||
851 | SSL_CTX_set_timeout(ctx, ssl_session_timeout); | |
852 | DEBUG(D_tls) debug_printf("Initialized TLS\n"); | |
7be682ca PP |
853 | |
854 | static_cbinfo = cbinfo; | |
855 | ||
059ec3d9 PH |
856 | return OK; |
857 | } | |
858 | ||
859 | ||
860 | ||
861 | ||
862 | /************************************************* | |
863 | * Get name of cipher in use * | |
864 | *************************************************/ | |
865 | ||
866 | /* The answer is left in a static buffer, and tls_cipher is set to point | |
867 | to it. | |
868 | ||
869 | Argument: pointer to an SSL structure for the connection | |
870 | Returns: nothing | |
871 | */ | |
872 | ||
873 | static void | |
874 | construct_cipher_name(SSL *ssl) | |
875 | { | |
876 | static uschar cipherbuf[256]; | |
57b3a7f5 PP |
877 | /* With OpenSSL 1.0.0a, this needs to be const but the documentation doesn't |
878 | yet reflect that. It should be a safe change anyway, even 0.9.8 versions have | |
879 | the accessor functions use const in the prototype. */ | |
880 | const SSL_CIPHER *c; | |
059ec3d9 | 881 | uschar *ver; |
059ec3d9 PH |
882 | |
883 | switch (ssl->session->ssl_version) | |
884 | { | |
885 | case SSL2_VERSION: | |
886 | ver = US"SSLv2"; | |
887 | break; | |
888 | ||
889 | case SSL3_VERSION: | |
890 | ver = US"SSLv3"; | |
891 | break; | |
892 | ||
893 | case TLS1_VERSION: | |
894 | ver = US"TLSv1"; | |
895 | break; | |
896 | ||
c80c5570 PP |
897 | #ifdef TLS1_1_VERSION |
898 | case TLS1_1_VERSION: | |
899 | ver = US"TLSv1.1"; | |
900 | break; | |
901 | #endif | |
902 | ||
903 | #ifdef TLS1_2_VERSION | |
904 | case TLS1_2_VERSION: | |
905 | ver = US"TLSv1.2"; | |
906 | break; | |
907 | #endif | |
908 | ||
059ec3d9 PH |
909 | default: |
910 | ver = US"UNKNOWN"; | |
911 | } | |
912 | ||
57b3a7f5 | 913 | c = (const SSL_CIPHER *) SSL_get_current_cipher(ssl); |
edc33b5f | 914 | SSL_CIPHER_get_bits(c, &tls_bits); |
059ec3d9 PH |
915 | |
916 | string_format(cipherbuf, sizeof(cipherbuf), "%s:%s:%u", ver, | |
edc33b5f | 917 | SSL_CIPHER_get_name(c), tls_bits); |
059ec3d9 PH |
918 | tls_cipher = cipherbuf; |
919 | ||
920 | DEBUG(D_tls) debug_printf("Cipher: %s\n", cipherbuf); | |
921 | } | |
922 | ||
923 | ||
924 | ||
925 | ||
926 | ||
927 | /************************************************* | |
928 | * Set up for verifying certificates * | |
929 | *************************************************/ | |
930 | ||
931 | /* Called by both client and server startup | |
932 | ||
933 | Arguments: | |
7be682ca | 934 | sctx SSL_CTX* to initialise |
059ec3d9 PH |
935 | certs certs file or NULL |
936 | crl CRL file or NULL | |
937 | host NULL in a server; the remote host in a client | |
938 | optional TRUE if called from a server for a host in tls_try_verify_hosts; | |
939 | otherwise passed as FALSE | |
940 | ||
941 | Returns: OK/DEFER/FAIL | |
942 | */ | |
943 | ||
944 | static int | |
7be682ca | 945 | setup_certs(SSL_CTX *sctx, uschar *certs, uschar *crl, host_item *host, BOOL optional) |
059ec3d9 PH |
946 | { |
947 | uschar *expcerts, *expcrl; | |
948 | ||
949 | if (!expand_check(certs, US"tls_verify_certificates", &expcerts)) | |
950 | return DEFER; | |
951 | ||
952 | if (expcerts != NULL) | |
953 | { | |
954 | struct stat statbuf; | |
7be682ca | 955 | if (!SSL_CTX_set_default_verify_paths(sctx)) |
7199e1ee | 956 | return tls_error(US"SSL_CTX_set_default_verify_paths", host, NULL); |
059ec3d9 PH |
957 | |
958 | if (Ustat(expcerts, &statbuf) < 0) | |
959 | { | |
960 | log_write(0, LOG_MAIN|LOG_PANIC, | |
961 | "failed to stat %s for certificates", expcerts); | |
962 | return DEFER; | |
963 | } | |
964 | else | |
965 | { | |
966 | uschar *file, *dir; | |
967 | if ((statbuf.st_mode & S_IFMT) == S_IFDIR) | |
968 | { file = NULL; dir = expcerts; } | |
969 | else | |
970 | { file = expcerts; dir = NULL; } | |
971 | ||
972 | /* If a certificate file is empty, the next function fails with an | |
973 | unhelpful error message. If we skip it, we get the correct behaviour (no | |
974 | certificates are recognized, but the error message is still misleading (it | |
975 | says no certificate was supplied.) But this is better. */ | |
976 | ||
977 | if ((file == NULL || statbuf.st_size > 0) && | |
7be682ca | 978 | !SSL_CTX_load_verify_locations(sctx, CS file, CS dir)) |
7199e1ee | 979 | return tls_error(US"SSL_CTX_load_verify_locations", host, NULL); |
059ec3d9 PH |
980 | |
981 | if (file != NULL) | |
982 | { | |
7be682ca | 983 | SSL_CTX_set_client_CA_list(sctx, SSL_load_client_CA_file(CS file)); |
059ec3d9 PH |
984 | } |
985 | } | |
986 | ||
987 | /* Handle a certificate revocation list. */ | |
988 | ||
989 | #if OPENSSL_VERSION_NUMBER > 0x00907000L | |
990 | ||
8b417f2c PH |
991 | /* This bit of code is now the version supplied by Lars Mainka. (I have |
992 | * merely reformatted it into the Exim code style.) | |
993 | ||
994 | * "From here I changed the code to add support for multiple crl's | |
995 | * in pem format in one file or to support hashed directory entries in | |
996 | * pem format instead of a file. This method now uses the library function | |
997 | * X509_STORE_load_locations to add the CRL location to the SSL context. | |
998 | * OpenSSL will then handle the verify against CA certs and CRLs by | |
999 | * itself in the verify callback." */ | |
1000 | ||
059ec3d9 PH |
1001 | if (!expand_check(crl, US"tls_crl", &expcrl)) return DEFER; |
1002 | if (expcrl != NULL && *expcrl != 0) | |
1003 | { | |
8b417f2c PH |
1004 | struct stat statbufcrl; |
1005 | if (Ustat(expcrl, &statbufcrl) < 0) | |
1006 | { | |
1007 | log_write(0, LOG_MAIN|LOG_PANIC, | |
1008 | "failed to stat %s for certificates revocation lists", expcrl); | |
1009 | return DEFER; | |
1010 | } | |
1011 | else | |
059ec3d9 | 1012 | { |
8b417f2c PH |
1013 | /* is it a file or directory? */ |
1014 | uschar *file, *dir; | |
7be682ca | 1015 | X509_STORE *cvstore = SSL_CTX_get_cert_store(sctx); |
8b417f2c | 1016 | if ((statbufcrl.st_mode & S_IFMT) == S_IFDIR) |
059ec3d9 | 1017 | { |
8b417f2c PH |
1018 | file = NULL; |
1019 | dir = expcrl; | |
1020 | DEBUG(D_tls) debug_printf("SSL CRL value is a directory %s\n", dir); | |
059ec3d9 PH |
1021 | } |
1022 | else | |
1023 | { | |
8b417f2c PH |
1024 | file = expcrl; |
1025 | dir = NULL; | |
1026 | DEBUG(D_tls) debug_printf("SSL CRL value is a file %s\n", file); | |
059ec3d9 | 1027 | } |
8b417f2c | 1028 | if (X509_STORE_load_locations(cvstore, CS file, CS dir) == 0) |
7199e1ee | 1029 | return tls_error(US"X509_STORE_load_locations", host, NULL); |
8b417f2c PH |
1030 | |
1031 | /* setting the flags to check against the complete crl chain */ | |
1032 | ||
1033 | X509_STORE_set_flags(cvstore, | |
1034 | X509_V_FLAG_CRL_CHECK|X509_V_FLAG_CRL_CHECK_ALL); | |
059ec3d9 | 1035 | } |
059ec3d9 PH |
1036 | } |
1037 | ||
1038 | #endif /* OPENSSL_VERSION_NUMBER > 0x00907000L */ | |
1039 | ||
1040 | /* If verification is optional, don't fail if no certificate */ | |
1041 | ||
7be682ca | 1042 | SSL_CTX_set_verify(sctx, |
059ec3d9 PH |
1043 | SSL_VERIFY_PEER | (optional? 0 : SSL_VERIFY_FAIL_IF_NO_PEER_CERT), |
1044 | verify_callback); | |
1045 | } | |
1046 | ||
1047 | return OK; | |
1048 | } | |
1049 | ||
1050 | ||
1051 | ||
1052 | /************************************************* | |
1053 | * Start a TLS session in a server * | |
1054 | *************************************************/ | |
1055 | ||
1056 | /* This is called when Exim is running as a server, after having received | |
1057 | the STARTTLS command. It must respond to that command, and then negotiate | |
1058 | a TLS session. | |
1059 | ||
1060 | Arguments: | |
1061 | require_ciphers allowed ciphers | |
1062 | ||
1063 | Returns: OK on success | |
1064 | DEFER for errors before the start of the negotiation | |
1065 | FAIL for errors during the negotation; the server can't | |
1066 | continue running. | |
1067 | */ | |
1068 | ||
1069 | int | |
17c76198 | 1070 | tls_server_start(const uschar *require_ciphers) |
059ec3d9 PH |
1071 | { |
1072 | int rc; | |
1073 | uschar *expciphers; | |
7be682ca | 1074 | tls_ext_ctx_cb *cbinfo; |
059ec3d9 PH |
1075 | |
1076 | /* Check for previous activation */ | |
1077 | ||
1078 | if (tls_active >= 0) | |
1079 | { | |
5ca6d115 | 1080 | tls_error(US"STARTTLS received after TLS started", NULL, US""); |
059ec3d9 PH |
1081 | smtp_printf("554 Already in TLS\r\n"); |
1082 | return FAIL; | |
1083 | } | |
1084 | ||
1085 | /* Initialize the SSL library. If it fails, it will already have logged | |
1086 | the error. */ | |
1087 | ||
3f7eeb86 PP |
1088 | rc = tls_init(NULL, tls_dhparam, tls_certificate, tls_privatekey, |
1089 | #ifdef EXPERIMENTAL_OCSP | |
1090 | tls_ocsp_file, | |
1091 | #endif | |
1092 | NULL); | |
059ec3d9 | 1093 | if (rc != OK) return rc; |
7be682ca | 1094 | cbinfo = static_cbinfo; |
059ec3d9 PH |
1095 | |
1096 | if (!expand_check(require_ciphers, US"tls_require_ciphers", &expciphers)) | |
1097 | return FAIL; | |
1098 | ||
1099 | /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they | |
17c76198 PP |
1100 | were historically separated by underscores. So that I can use either form in my |
1101 | tests, and also for general convenience, we turn underscores into hyphens here. | |
1102 | */ | |
059ec3d9 PH |
1103 | |
1104 | if (expciphers != NULL) | |
1105 | { | |
1106 | uschar *s = expciphers; | |
1107 | while (*s != 0) { if (*s == '_') *s = '-'; s++; } | |
1108 | DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers); | |
1109 | if (!SSL_CTX_set_cipher_list(ctx, CS expciphers)) | |
7199e1ee | 1110 | return tls_error(US"SSL_CTX_set_cipher_list", NULL, NULL); |
7be682ca | 1111 | cbinfo->server_cipher_list = expciphers; |
059ec3d9 PH |
1112 | } |
1113 | ||
1114 | /* If this is a host for which certificate verification is mandatory or | |
1115 | optional, set up appropriately. */ | |
1116 | ||
1117 | tls_certificate_verified = FALSE; | |
1118 | verify_callback_called = FALSE; | |
1119 | ||
1120 | if (verify_check_host(&tls_verify_hosts) == OK) | |
1121 | { | |
7be682ca | 1122 | rc = setup_certs(ctx, tls_verify_certificates, tls_crl, NULL, FALSE); |
059ec3d9 PH |
1123 | if (rc != OK) return rc; |
1124 | verify_optional = FALSE; | |
1125 | } | |
1126 | else if (verify_check_host(&tls_try_verify_hosts) == OK) | |
1127 | { | |
7be682ca | 1128 | rc = setup_certs(ctx, tls_verify_certificates, tls_crl, NULL, TRUE); |
059ec3d9 PH |
1129 | if (rc != OK) return rc; |
1130 | verify_optional = TRUE; | |
1131 | } | |
1132 | ||
1133 | /* Prepare for new connection */ | |
1134 | ||
7199e1ee | 1135 | if ((ssl = SSL_new(ctx)) == NULL) return tls_error(US"SSL_new", NULL, NULL); |
da3ad30d PP |
1136 | |
1137 | /* Warning: we used to SSL_clear(ssl) here, it was removed. | |
1138 | * | |
1139 | * With the SSL_clear(), we get strange interoperability bugs with | |
1140 | * OpenSSL 1.0.1b and TLS1.1/1.2. It looks as though this may be a bug in | |
1141 | * OpenSSL itself, as a clear should not lead to inability to follow protocols. | |
1142 | * | |
1143 | * The SSL_clear() call is to let an existing SSL* be reused, typically after | |
1144 | * session shutdown. In this case, we have a brand new object and there's no | |
1145 | * obvious reason to immediately clear it. I'm guessing that this was | |
1146 | * originally added because of incomplete initialisation which the clear fixed, | |
1147 | * in some historic release. | |
1148 | */ | |
059ec3d9 PH |
1149 | |
1150 | /* Set context and tell client to go ahead, except in the case of TLS startup | |
1151 | on connection, where outputting anything now upsets the clients and tends to | |
1152 | make them disconnect. We need to have an explicit fflush() here, to force out | |
1153 | the response. Other smtp_printf() calls do not need it, because in non-TLS | |
1154 | mode, the fflush() happens when smtp_getc() is called. */ | |
1155 | ||
1156 | SSL_set_session_id_context(ssl, sid_ctx, Ustrlen(sid_ctx)); | |
1157 | if (!tls_on_connect) | |
1158 | { | |
1159 | smtp_printf("220 TLS go ahead\r\n"); | |
1160 | fflush(smtp_out); | |
1161 | } | |
1162 | ||
1163 | /* Now negotiate the TLS session. We put our own timer on it, since it seems | |
1164 | that the OpenSSL library doesn't. */ | |
1165 | ||
56f5d9bd PH |
1166 | SSL_set_wfd(ssl, fileno(smtp_out)); |
1167 | SSL_set_rfd(ssl, fileno(smtp_in)); | |
059ec3d9 PH |
1168 | SSL_set_accept_state(ssl); |
1169 | ||
1170 | DEBUG(D_tls) debug_printf("Calling SSL_accept\n"); | |
1171 | ||
1172 | sigalrm_seen = FALSE; | |
1173 | if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout); | |
1174 | rc = SSL_accept(ssl); | |
1175 | alarm(0); | |
1176 | ||
1177 | if (rc <= 0) | |
1178 | { | |
7199e1ee | 1179 | tls_error(US"SSL_accept", NULL, sigalrm_seen ? US"timed out" : NULL); |
77bb000f PP |
1180 | if (ERR_get_error() == 0) |
1181 | log_write(0, LOG_MAIN, | |
a053d125 | 1182 | "TLS client disconnected cleanly (rejected our certificate?)"); |
059ec3d9 PH |
1183 | return FAIL; |
1184 | } | |
1185 | ||
1186 | DEBUG(D_tls) debug_printf("SSL_accept was successful\n"); | |
1187 | ||
1188 | /* TLS has been set up. Adjust the input functions to read via TLS, | |
1189 | and initialize things. */ | |
1190 | ||
1191 | construct_cipher_name(ssl); | |
1192 | ||
1193 | DEBUG(D_tls) | |
1194 | { | |
1195 | uschar buf[2048]; | |
1196 | if (SSL_get_shared_ciphers(ssl, CS buf, sizeof(buf)) != NULL) | |
1197 | debug_printf("Shared ciphers: %s\n", buf); | |
1198 | } | |
1199 | ||
1200 | ||
1201 | ssl_xfer_buffer = store_malloc(ssl_xfer_buffer_size); | |
1202 | ssl_xfer_buffer_lwm = ssl_xfer_buffer_hwm = 0; | |
1203 | ssl_xfer_eof = ssl_xfer_error = 0; | |
1204 | ||
1205 | receive_getc = tls_getc; | |
1206 | receive_ungetc = tls_ungetc; | |
1207 | receive_feof = tls_feof; | |
1208 | receive_ferror = tls_ferror; | |
58eb016e | 1209 | receive_smtp_buffered = tls_smtp_buffered; |
059ec3d9 PH |
1210 | |
1211 | tls_active = fileno(smtp_out); | |
1212 | return OK; | |
1213 | } | |
1214 | ||
1215 | ||
1216 | ||
1217 | ||
1218 | ||
1219 | /************************************************* | |
1220 | * Start a TLS session in a client * | |
1221 | *************************************************/ | |
1222 | ||
1223 | /* Called from the smtp transport after STARTTLS has been accepted. | |
1224 | ||
1225 | Argument: | |
1226 | fd the fd of the connection | |
1227 | host connected host (for messages) | |
83da1223 | 1228 | addr the first address |
059ec3d9 PH |
1229 | dhparam DH parameter file |
1230 | certificate certificate file | |
1231 | privatekey private key file | |
3f0945ff | 1232 | sni TLS SNI to send to remote host |
059ec3d9 PH |
1233 | verify_certs file for certificate verify |
1234 | crl file containing CRL | |
1235 | require_ciphers list of allowed ciphers | |
83da1223 | 1236 | timeout startup timeout |
059ec3d9 PH |
1237 | |
1238 | Returns: OK on success | |
1239 | FAIL otherwise - note that tls_error() will not give DEFER | |
1240 | because this is not a server | |
1241 | */ | |
1242 | ||
1243 | int | |
1244 | tls_client_start(int fd, host_item *host, address_item *addr, uschar *dhparam, | |
3f0945ff PP |
1245 | uschar *certificate, uschar *privatekey, uschar *sni, |
1246 | uschar *verify_certs, uschar *crl, | |
17c76198 | 1247 | uschar *require_ciphers, int timeout) |
059ec3d9 PH |
1248 | { |
1249 | static uschar txt[256]; | |
1250 | uschar *expciphers; | |
1251 | X509* server_cert; | |
1252 | int rc; | |
1253 | ||
3f7eeb86 PP |
1254 | rc = tls_init(host, dhparam, certificate, privatekey, |
1255 | #ifdef EXPERIMENTAL_OCSP | |
1256 | NULL, | |
1257 | #endif | |
1258 | addr); | |
059ec3d9 PH |
1259 | if (rc != OK) return rc; |
1260 | ||
1261 | tls_certificate_verified = FALSE; | |
1262 | verify_callback_called = FALSE; | |
1263 | ||
1264 | if (!expand_check(require_ciphers, US"tls_require_ciphers", &expciphers)) | |
1265 | return FAIL; | |
1266 | ||
1267 | /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they | |
1268 | are separated by underscores. So that I can use either form in my tests, and | |
1269 | also for general convenience, we turn underscores into hyphens here. */ | |
1270 | ||
1271 | if (expciphers != NULL) | |
1272 | { | |
1273 | uschar *s = expciphers; | |
1274 | while (*s != 0) { if (*s == '_') *s = '-'; s++; } | |
1275 | DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers); | |
1276 | if (!SSL_CTX_set_cipher_list(ctx, CS expciphers)) | |
7199e1ee | 1277 | return tls_error(US"SSL_CTX_set_cipher_list", host, NULL); |
059ec3d9 PH |
1278 | } |
1279 | ||
7be682ca | 1280 | rc = setup_certs(ctx, verify_certs, crl, host, FALSE); |
059ec3d9 PH |
1281 | if (rc != OK) return rc; |
1282 | ||
7199e1ee | 1283 | if ((ssl = SSL_new(ctx)) == NULL) return tls_error(US"SSL_new", host, NULL); |
059ec3d9 PH |
1284 | SSL_set_session_id_context(ssl, sid_ctx, Ustrlen(sid_ctx)); |
1285 | SSL_set_fd(ssl, fd); | |
1286 | SSL_set_connect_state(ssl); | |
1287 | ||
3f0945ff PP |
1288 | if (sni) |
1289 | { | |
1290 | if (!expand_check(sni, US"tls_sni", &tls_sni)) | |
1291 | return FAIL; | |
1292 | if (!Ustrlen(tls_sni)) | |
1293 | tls_sni = NULL; | |
1294 | else | |
1295 | { | |
35731706 | 1296 | #ifdef EXIM_HAVE_OPENSSL_TLSEXT |
3f0945ff PP |
1297 | DEBUG(D_tls) debug_printf("Setting TLS SNI \"%s\"\n", tls_sni); |
1298 | SSL_set_tlsext_host_name(ssl, tls_sni); | |
35731706 PP |
1299 | #else |
1300 | DEBUG(D_tls) | |
1301 | debug_printf("OpenSSL at build-time lacked SNI support, ignoring \"%s\"\n", | |
1302 | tls_sni); | |
1303 | #endif | |
3f0945ff PP |
1304 | } |
1305 | } | |
1306 | ||
059ec3d9 PH |
1307 | /* There doesn't seem to be a built-in timeout on connection. */ |
1308 | ||
1309 | DEBUG(D_tls) debug_printf("Calling SSL_connect\n"); | |
1310 | sigalrm_seen = FALSE; | |
1311 | alarm(timeout); | |
1312 | rc = SSL_connect(ssl); | |
1313 | alarm(0); | |
1314 | ||
1315 | if (rc <= 0) | |
7199e1ee | 1316 | return tls_error(US"SSL_connect", host, sigalrm_seen ? US"timed out" : NULL); |
059ec3d9 PH |
1317 | |
1318 | DEBUG(D_tls) debug_printf("SSL_connect succeeded\n"); | |
1319 | ||
453a6645 | 1320 | /* Beware anonymous ciphers which lead to server_cert being NULL */ |
059ec3d9 | 1321 | server_cert = SSL_get_peer_certificate (ssl); |
453a6645 PP |
1322 | if (server_cert) |
1323 | { | |
1324 | tls_peerdn = US X509_NAME_oneline(X509_get_subject_name(server_cert), | |
1325 | CS txt, sizeof(txt)); | |
1326 | tls_peerdn = txt; | |
1327 | } | |
1328 | else | |
1329 | tls_peerdn = NULL; | |
059ec3d9 PH |
1330 | |
1331 | construct_cipher_name(ssl); /* Sets tls_cipher */ | |
1332 | ||
1333 | tls_active = fd; | |
1334 | return OK; | |
1335 | } | |
1336 | ||
1337 | ||
1338 | ||
1339 | ||
1340 | ||
1341 | /************************************************* | |
1342 | * TLS version of getc * | |
1343 | *************************************************/ | |
1344 | ||
1345 | /* This gets the next byte from the TLS input buffer. If the buffer is empty, | |
1346 | it refills the buffer via the SSL reading function. | |
1347 | ||
1348 | Arguments: none | |
1349 | Returns: the next character or EOF | |
1350 | */ | |
1351 | ||
1352 | int | |
1353 | tls_getc(void) | |
1354 | { | |
1355 | if (ssl_xfer_buffer_lwm >= ssl_xfer_buffer_hwm) | |
1356 | { | |
1357 | int error; | |
1358 | int inbytes; | |
1359 | ||
c80c5570 PP |
1360 | DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", ssl, |
1361 | ssl_xfer_buffer, ssl_xfer_buffer_size); | |
059ec3d9 PH |
1362 | |
1363 | if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout); | |
1364 | inbytes = SSL_read(ssl, CS ssl_xfer_buffer, ssl_xfer_buffer_size); | |
1365 | error = SSL_get_error(ssl, inbytes); | |
1366 | alarm(0); | |
1367 | ||
1368 | /* SSL_ERROR_ZERO_RETURN appears to mean that the SSL session has been | |
1369 | closed down, not that the socket itself has been closed down. Revert to | |
1370 | non-SSL handling. */ | |
1371 | ||
1372 | if (error == SSL_ERROR_ZERO_RETURN) | |
1373 | { | |
1374 | DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n"); | |
1375 | ||
1376 | receive_getc = smtp_getc; | |
1377 | receive_ungetc = smtp_ungetc; | |
1378 | receive_feof = smtp_feof; | |
1379 | receive_ferror = smtp_ferror; | |
58eb016e | 1380 | receive_smtp_buffered = smtp_buffered; |
059ec3d9 PH |
1381 | |
1382 | SSL_free(ssl); | |
1383 | ssl = NULL; | |
1384 | tls_active = -1; | |
3f0945ff | 1385 | tls_bits = 0; |
059ec3d9 PH |
1386 | tls_cipher = NULL; |
1387 | tls_peerdn = NULL; | |
3f0945ff | 1388 | tls_sni = NULL; |
059ec3d9 PH |
1389 | |
1390 | return smtp_getc(); | |
1391 | } | |
1392 | ||
1393 | /* Handle genuine errors */ | |
1394 | ||
ba084640 PP |
1395 | else if (error == SSL_ERROR_SSL) |
1396 | { | |
1397 | ERR_error_string(ERR_get_error(), ssl_errstring); | |
89dd51cd | 1398 | log_write(0, LOG_MAIN, "TLS error (SSL_read): %s", ssl_errstring); |
ba084640 PP |
1399 | ssl_xfer_error = 1; |
1400 | return EOF; | |
1401 | } | |
1402 | ||
059ec3d9 PH |
1403 | else if (error != SSL_ERROR_NONE) |
1404 | { | |
1405 | DEBUG(D_tls) debug_printf("Got SSL error %d\n", error); | |
1406 | ssl_xfer_error = 1; | |
1407 | return EOF; | |
1408 | } | |
c80c5570 | 1409 | |
80a47a2c TK |
1410 | #ifndef DISABLE_DKIM |
1411 | dkim_exim_verify_feed(ssl_xfer_buffer, inbytes); | |
1412 | #endif | |
059ec3d9 PH |
1413 | ssl_xfer_buffer_hwm = inbytes; |
1414 | ssl_xfer_buffer_lwm = 0; | |
1415 | } | |
1416 | ||
1417 | /* Something in the buffer; return next uschar */ | |
1418 | ||
1419 | return ssl_xfer_buffer[ssl_xfer_buffer_lwm++]; | |
1420 | } | |
1421 | ||
1422 | ||
1423 | ||
1424 | /************************************************* | |
1425 | * Read bytes from TLS channel * | |
1426 | *************************************************/ | |
1427 | ||
1428 | /* | |
1429 | Arguments: | |
1430 | buff buffer of data | |
1431 | len size of buffer | |
1432 | ||
1433 | Returns: the number of bytes read | |
1434 | -1 after a failed read | |
1435 | */ | |
1436 | ||
1437 | int | |
1438 | tls_read(uschar *buff, size_t len) | |
1439 | { | |
1440 | int inbytes; | |
1441 | int error; | |
1442 | ||
c80c5570 PP |
1443 | DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", ssl, |
1444 | buff, (unsigned int)len); | |
059ec3d9 PH |
1445 | |
1446 | inbytes = SSL_read(ssl, CS buff, len); | |
1447 | error = SSL_get_error(ssl, inbytes); | |
1448 | ||
1449 | if (error == SSL_ERROR_ZERO_RETURN) | |
1450 | { | |
1451 | DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n"); | |
1452 | return -1; | |
1453 | } | |
1454 | else if (error != SSL_ERROR_NONE) | |
1455 | { | |
1456 | return -1; | |
1457 | } | |
1458 | ||
1459 | return inbytes; | |
1460 | } | |
1461 | ||
1462 | ||
1463 | ||
1464 | ||
1465 | ||
1466 | /************************************************* | |
1467 | * Write bytes down TLS channel * | |
1468 | *************************************************/ | |
1469 | ||
1470 | /* | |
1471 | Arguments: | |
1472 | buff buffer of data | |
1473 | len number of bytes | |
1474 | ||
1475 | Returns: the number of bytes after a successful write, | |
1476 | -1 after a failed write | |
1477 | */ | |
1478 | ||
1479 | int | |
1480 | tls_write(const uschar *buff, size_t len) | |
1481 | { | |
1482 | int outbytes; | |
1483 | int error; | |
1484 | int left = len; | |
1485 | ||
c80c5570 | 1486 | DEBUG(D_tls) debug_printf("tls_do_write(%p, %d)\n", buff, left); |
059ec3d9 PH |
1487 | while (left > 0) |
1488 | { | |
c80c5570 | 1489 | DEBUG(D_tls) debug_printf("SSL_write(SSL, %p, %d)\n", buff, left); |
059ec3d9 PH |
1490 | outbytes = SSL_write(ssl, CS buff, left); |
1491 | error = SSL_get_error(ssl, outbytes); | |
1492 | DEBUG(D_tls) debug_printf("outbytes=%d error=%d\n", outbytes, error); | |
1493 | switch (error) | |
1494 | { | |
1495 | case SSL_ERROR_SSL: | |
1496 | ERR_error_string(ERR_get_error(), ssl_errstring); | |
1497 | log_write(0, LOG_MAIN, "TLS error (SSL_write): %s", ssl_errstring); | |
1498 | return -1; | |
1499 | ||
1500 | case SSL_ERROR_NONE: | |
1501 | left -= outbytes; | |
1502 | buff += outbytes; | |
1503 | break; | |
1504 | ||
1505 | case SSL_ERROR_ZERO_RETURN: | |
1506 | log_write(0, LOG_MAIN, "SSL channel closed on write"); | |
1507 | return -1; | |
1508 | ||
1509 | default: | |
1510 | log_write(0, LOG_MAIN, "SSL_write error %d", error); | |
1511 | return -1; | |
1512 | } | |
1513 | } | |
1514 | return len; | |
1515 | } | |
1516 | ||
1517 | ||
1518 | ||
1519 | /************************************************* | |
1520 | * Close down a TLS session * | |
1521 | *************************************************/ | |
1522 | ||
1523 | /* This is also called from within a delivery subprocess forked from the | |
1524 | daemon, to shut down the TLS library, without actually doing a shutdown (which | |
1525 | would tamper with the SSL session in the parent process). | |
1526 | ||
1527 | Arguments: TRUE if SSL_shutdown is to be called | |
1528 | Returns: nothing | |
1529 | */ | |
1530 | ||
1531 | void | |
1532 | tls_close(BOOL shutdown) | |
1533 | { | |
1534 | if (tls_active < 0) return; /* TLS was not active */ | |
1535 | ||
1536 | if (shutdown) | |
1537 | { | |
1538 | DEBUG(D_tls) debug_printf("tls_close(): shutting down SSL\n"); | |
1539 | SSL_shutdown(ssl); | |
1540 | } | |
1541 | ||
1542 | SSL_free(ssl); | |
1543 | ssl = NULL; | |
1544 | ||
1545 | tls_active = -1; | |
1546 | } | |
1547 | ||
36f12725 NM |
1548 | |
1549 | ||
1550 | ||
3375e053 PP |
1551 | /************************************************* |
1552 | * Let tls_require_ciphers be checked at startup * | |
1553 | *************************************************/ | |
1554 | ||
1555 | /* The tls_require_ciphers option, if set, must be something which the | |
1556 | library can parse. | |
1557 | ||
1558 | Returns: NULL on success, or error message | |
1559 | */ | |
1560 | ||
1561 | uschar * | |
1562 | tls_validate_require_cipher(void) | |
1563 | { | |
1564 | SSL_CTX *ctx; | |
1565 | uschar *s, *expciphers, *err; | |
1566 | ||
1567 | /* this duplicates from tls_init(), we need a better "init just global | |
1568 | state, for no specific purpose" singleton function of our own */ | |
1569 | ||
1570 | SSL_load_error_strings(); | |
1571 | OpenSSL_add_ssl_algorithms(); | |
1572 | #if (OPENSSL_VERSION_NUMBER >= 0x0090800fL) && !defined(OPENSSL_NO_SHA256) | |
1573 | /* SHA256 is becoming ever more popular. This makes sure it gets added to the | |
1574 | list of available digests. */ | |
1575 | EVP_add_digest(EVP_sha256()); | |
1576 | #endif | |
1577 | ||
1578 | if (!(tls_require_ciphers && *tls_require_ciphers)) | |
1579 | return NULL; | |
1580 | ||
1581 | if (!expand_check(tls_require_ciphers, US"tls_require_ciphers", &expciphers)) | |
1582 | return US"failed to expand tls_require_ciphers"; | |
1583 | ||
1584 | if (!(expciphers && *expciphers)) | |
1585 | return NULL; | |
1586 | ||
1587 | /* normalisation ripped from above */ | |
1588 | s = expciphers; | |
1589 | while (*s != 0) { if (*s == '_') *s = '-'; s++; } | |
1590 | ||
1591 | err = NULL; | |
1592 | ||
1593 | ctx = SSL_CTX_new(SSLv23_server_method()); | |
1594 | if (!ctx) | |
1595 | { | |
1596 | ERR_error_string(ERR_get_error(), ssl_errstring); | |
1597 | return string_sprintf("SSL_CTX_new() failed: %s", ssl_errstring); | |
1598 | } | |
1599 | ||
1600 | DEBUG(D_tls) | |
1601 | debug_printf("tls_require_ciphers expands to \"%s\"\n", expciphers); | |
1602 | ||
1603 | if (!SSL_CTX_set_cipher_list(ctx, CS expciphers)) | |
1604 | { | |
1605 | ERR_error_string(ERR_get_error(), ssl_errstring); | |
1606 | err = string_sprintf("SSL_CTX_set_cipher_list(%s) failed", expciphers); | |
1607 | } | |
1608 | ||
1609 | SSL_CTX_free(ctx); | |
1610 | ||
1611 | return err; | |
1612 | } | |
1613 | ||
1614 | ||
1615 | ||
1616 | ||
36f12725 NM |
1617 | /************************************************* |
1618 | * Report the library versions. * | |
1619 | *************************************************/ | |
1620 | ||
1621 | /* There have historically been some issues with binary compatibility in | |
1622 | OpenSSL libraries; if Exim (like many other applications) is built against | |
1623 | one version of OpenSSL but the run-time linker picks up another version, | |
1624 | it can result in serious failures, including crashing with a SIGSEGV. So | |
1625 | report the version found by the compiler and the run-time version. | |
1626 | ||
1627 | Arguments: a FILE* to print the results to | |
1628 | Returns: nothing | |
1629 | */ | |
1630 | ||
1631 | void | |
1632 | tls_version_report(FILE *f) | |
1633 | { | |
754a0503 PP |
1634 | fprintf(f, "Library version: OpenSSL: Compile: %s\n" |
1635 | " Runtime: %s\n", | |
1636 | OPENSSL_VERSION_TEXT, | |
1637 | SSLeay_version(SSLEAY_VERSION)); | |
36f12725 NM |
1638 | } |
1639 | ||
9e3331ea TK |
1640 | |
1641 | ||
1642 | ||
1643 | /************************************************* | |
17c76198 | 1644 | * Random number generation * |
9e3331ea TK |
1645 | *************************************************/ |
1646 | ||
1647 | /* Pseudo-random number generation. The result is not expected to be | |
1648 | cryptographically strong but not so weak that someone will shoot themselves | |
1649 | in the foot using it as a nonce in input in some email header scheme or | |
1650 | whatever weirdness they'll twist this into. The result should handle fork() | |
1651 | and avoid repeating sequences. OpenSSL handles that for us. | |
1652 | ||
1653 | Arguments: | |
1654 | max range maximum | |
1655 | Returns a random number in range [0, max-1] | |
1656 | */ | |
1657 | ||
1658 | int | |
17c76198 | 1659 | vaguely_random_number(int max) |
9e3331ea TK |
1660 | { |
1661 | unsigned int r; | |
1662 | int i, needed_len; | |
1663 | uschar *p; | |
1664 | uschar smallbuf[sizeof(r)]; | |
1665 | ||
1666 | if (max <= 1) | |
1667 | return 0; | |
1668 | ||
1669 | /* OpenSSL auto-seeds from /dev/random, etc, but this a double-check. */ | |
1670 | if (!RAND_status()) | |
1671 | { | |
1672 | randstuff r; | |
1673 | gettimeofday(&r.tv, NULL); | |
1674 | r.p = getpid(); | |
1675 | ||
1676 | RAND_seed((uschar *)(&r), sizeof(r)); | |
1677 | } | |
1678 | /* We're after pseudo-random, not random; if we still don't have enough data | |
1679 | in the internal PRNG then our options are limited. We could sleep and hope | |
1680 | for entropy to come along (prayer technique) but if the system is so depleted | |
1681 | in the first place then something is likely to just keep taking it. Instead, | |
1682 | we'll just take whatever little bit of pseudo-random we can still manage to | |
1683 | get. */ | |
1684 | ||
1685 | needed_len = sizeof(r); | |
1686 | /* Don't take 8 times more entropy than needed if int is 8 octets and we were | |
1687 | asked for a number less than 10. */ | |
1688 | for (r = max, i = 0; r; ++i) | |
1689 | r >>= 1; | |
1690 | i = (i + 7) / 8; | |
1691 | if (i < needed_len) | |
1692 | needed_len = i; | |
1693 | ||
1694 | /* We do not care if crypto-strong */ | |
17c76198 PP |
1695 | i = RAND_pseudo_bytes(smallbuf, needed_len); |
1696 | if (i < 0) | |
1697 | { | |
1698 | DEBUG(D_all) | |
1699 | debug_printf("OpenSSL RAND_pseudo_bytes() not supported by RAND method, using fallback.\n"); | |
1700 | return vaguely_random_number_fallback(max); | |
1701 | } | |
1702 | ||
9e3331ea TK |
1703 | r = 0; |
1704 | for (p = smallbuf; needed_len; --needed_len, ++p) | |
1705 | { | |
1706 | r *= 256; | |
1707 | r += *p; | |
1708 | } | |
1709 | ||
1710 | /* We don't particularly care about weighted results; if someone wants | |
1711 | smooth distribution and cares enough then they should submit a patch then. */ | |
1712 | return r % max; | |
1713 | } | |
1714 | ||
77bb000f PP |
1715 | |
1716 | ||
1717 | ||
1718 | /************************************************* | |
1719 | * OpenSSL option parse * | |
1720 | *************************************************/ | |
1721 | ||
1722 | /* Parse one option for tls_openssl_options_parse below | |
1723 | ||
1724 | Arguments: | |
1725 | name one option name | |
1726 | value place to store a value for it | |
1727 | Returns success or failure in parsing | |
1728 | */ | |
1729 | ||
1730 | struct exim_openssl_option { | |
1731 | uschar *name; | |
1732 | long value; | |
1733 | }; | |
1734 | /* We could use a macro to expand, but we need the ifdef and not all the | |
1735 | options document which version they were introduced in. Policylet: include | |
1736 | all options unless explicitly for DTLS, let the administrator choose which | |
1737 | to apply. | |
1738 | ||
1739 | This list is current as of: | |
c80c5570 | 1740 | ==> 1.0.1b <== */ |
77bb000f PP |
1741 | static struct exim_openssl_option exim_openssl_options[] = { |
1742 | /* KEEP SORTED ALPHABETICALLY! */ | |
1743 | #ifdef SSL_OP_ALL | |
73a46702 | 1744 | { US"all", SSL_OP_ALL }, |
77bb000f PP |
1745 | #endif |
1746 | #ifdef SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION | |
73a46702 | 1747 | { US"allow_unsafe_legacy_renegotiation", SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION }, |
77bb000f PP |
1748 | #endif |
1749 | #ifdef SSL_OP_CIPHER_SERVER_PREFERENCE | |
73a46702 | 1750 | { US"cipher_server_preference", SSL_OP_CIPHER_SERVER_PREFERENCE }, |
77bb000f PP |
1751 | #endif |
1752 | #ifdef SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS | |
73a46702 | 1753 | { US"dont_insert_empty_fragments", SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS }, |
77bb000f PP |
1754 | #endif |
1755 | #ifdef SSL_OP_EPHEMERAL_RSA | |
73a46702 | 1756 | { US"ephemeral_rsa", SSL_OP_EPHEMERAL_RSA }, |
77bb000f PP |
1757 | #endif |
1758 | #ifdef SSL_OP_LEGACY_SERVER_CONNECT | |
73a46702 | 1759 | { US"legacy_server_connect", SSL_OP_LEGACY_SERVER_CONNECT }, |
77bb000f PP |
1760 | #endif |
1761 | #ifdef SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER | |
73a46702 | 1762 | { US"microsoft_big_sslv3_buffer", SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER }, |
77bb000f PP |
1763 | #endif |
1764 | #ifdef SSL_OP_MICROSOFT_SESS_ID_BUG | |
73a46702 | 1765 | { US"microsoft_sess_id_bug", SSL_OP_MICROSOFT_SESS_ID_BUG }, |
77bb000f PP |
1766 | #endif |
1767 | #ifdef SSL_OP_MSIE_SSLV2_RSA_PADDING | |
73a46702 | 1768 | { US"msie_sslv2_rsa_padding", SSL_OP_MSIE_SSLV2_RSA_PADDING }, |
77bb000f PP |
1769 | #endif |
1770 | #ifdef SSL_OP_NETSCAPE_CHALLENGE_BUG | |
73a46702 | 1771 | { US"netscape_challenge_bug", SSL_OP_NETSCAPE_CHALLENGE_BUG }, |
77bb000f PP |
1772 | #endif |
1773 | #ifdef SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG | |
73a46702 | 1774 | { US"netscape_reuse_cipher_change_bug", SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG }, |
77bb000f | 1775 | #endif |
c80c5570 PP |
1776 | #ifdef SSL_OP_NO_COMPRESSION |
1777 | { US"no_compression", SSL_OP_NO_COMPRESSION }, | |
1778 | #endif | |
77bb000f | 1779 | #ifdef SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION |
73a46702 | 1780 | { US"no_session_resumption_on_renegotiation", SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION }, |
77bb000f | 1781 | #endif |
c0c7b2da PP |
1782 | #ifdef SSL_OP_NO_SSLv2 |
1783 | { US"no_sslv2", SSL_OP_NO_SSLv2 }, | |
1784 | #endif | |
1785 | #ifdef SSL_OP_NO_SSLv3 | |
1786 | { US"no_sslv3", SSL_OP_NO_SSLv3 }, | |
1787 | #endif | |
1788 | #ifdef SSL_OP_NO_TICKET | |
1789 | { US"no_ticket", SSL_OP_NO_TICKET }, | |
1790 | #endif | |
1791 | #ifdef SSL_OP_NO_TLSv1 | |
1792 | { US"no_tlsv1", SSL_OP_NO_TLSv1 }, | |
1793 | #endif | |
c80c5570 PP |
1794 | #ifdef SSL_OP_NO_TLSv1_1 |
1795 | #if SSL_OP_NO_TLSv1_1 == 0x00000400L | |
1796 | /* Error in chosen value in 1.0.1a; see first item in CHANGES for 1.0.1b */ | |
1797 | #warning OpenSSL 1.0.1a uses a bad value for SSL_OP_NO_TLSv1_1, ignoring | |
1798 | #else | |
1799 | { US"no_tlsv1_1", SSL_OP_NO_TLSv1_1 }, | |
1800 | #endif | |
1801 | #endif | |
1802 | #ifdef SSL_OP_NO_TLSv1_2 | |
1803 | { US"no_tlsv1_2", SSL_OP_NO_TLSv1_2 }, | |
1804 | #endif | |
77bb000f | 1805 | #ifdef SSL_OP_SINGLE_DH_USE |
73a46702 | 1806 | { US"single_dh_use", SSL_OP_SINGLE_DH_USE }, |
77bb000f PP |
1807 | #endif |
1808 | #ifdef SSL_OP_SINGLE_ECDH_USE | |
73a46702 | 1809 | { US"single_ecdh_use", SSL_OP_SINGLE_ECDH_USE }, |
77bb000f PP |
1810 | #endif |
1811 | #ifdef SSL_OP_SSLEAY_080_CLIENT_DH_BUG | |
73a46702 | 1812 | { US"ssleay_080_client_dh_bug", SSL_OP_SSLEAY_080_CLIENT_DH_BUG }, |
77bb000f PP |
1813 | #endif |
1814 | #ifdef SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG | |
73a46702 | 1815 | { US"sslref2_reuse_cert_type_bug", SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG }, |
77bb000f PP |
1816 | #endif |
1817 | #ifdef SSL_OP_TLS_BLOCK_PADDING_BUG | |
73a46702 | 1818 | { US"tls_block_padding_bug", SSL_OP_TLS_BLOCK_PADDING_BUG }, |
77bb000f PP |
1819 | #endif |
1820 | #ifdef SSL_OP_TLS_D5_BUG | |
73a46702 | 1821 | { US"tls_d5_bug", SSL_OP_TLS_D5_BUG }, |
77bb000f PP |
1822 | #endif |
1823 | #ifdef SSL_OP_TLS_ROLLBACK_BUG | |
73a46702 | 1824 | { US"tls_rollback_bug", SSL_OP_TLS_ROLLBACK_BUG }, |
77bb000f PP |
1825 | #endif |
1826 | }; | |
1827 | static int exim_openssl_options_size = | |
1828 | sizeof(exim_openssl_options)/sizeof(struct exim_openssl_option); | |
1829 | ||
c80c5570 | 1830 | |
77bb000f PP |
1831 | static BOOL |
1832 | tls_openssl_one_option_parse(uschar *name, long *value) | |
1833 | { | |
1834 | int first = 0; | |
1835 | int last = exim_openssl_options_size; | |
1836 | while (last > first) | |
1837 | { | |
1838 | int middle = (first + last)/2; | |
1839 | int c = Ustrcmp(name, exim_openssl_options[middle].name); | |
1840 | if (c == 0) | |
1841 | { | |
1842 | *value = exim_openssl_options[middle].value; | |
1843 | return TRUE; | |
1844 | } | |
1845 | else if (c > 0) | |
1846 | first = middle + 1; | |
1847 | else | |
1848 | last = middle; | |
1849 | } | |
1850 | return FALSE; | |
1851 | } | |
1852 | ||
1853 | ||
1854 | ||
1855 | ||
1856 | /************************************************* | |
1857 | * OpenSSL option parsing logic * | |
1858 | *************************************************/ | |
1859 | ||
1860 | /* OpenSSL has a number of compatibility options which an administrator might | |
1861 | reasonably wish to set. Interpret a list similarly to decode_bits(), so that | |
1862 | we look like log_selector. | |
1863 | ||
1864 | Arguments: | |
1865 | option_spec the administrator-supplied string of options | |
1866 | results ptr to long storage for the options bitmap | |
1867 | Returns success or failure | |
1868 | */ | |
1869 | ||
1870 | BOOL | |
1871 | tls_openssl_options_parse(uschar *option_spec, long *results) | |
1872 | { | |
1873 | long result, item; | |
1874 | uschar *s, *end; | |
1875 | uschar keep_c; | |
1876 | BOOL adding, item_parsed; | |
1877 | ||
0e944a0d | 1878 | result = 0L; |
b1770b6e | 1879 | /* Prior to 4.80 we or'd in SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS; removed |
da3ad30d | 1880 | * from default because it increases BEAST susceptibility. */ |
f0f5a555 PP |
1881 | #ifdef SSL_OP_NO_SSLv2 |
1882 | result |= SSL_OP_NO_SSLv2; | |
1883 | #endif | |
77bb000f PP |
1884 | |
1885 | if (option_spec == NULL) | |
1886 | { | |
1887 | *results = result; | |
1888 | return TRUE; | |
1889 | } | |
1890 | ||
1891 | for (s=option_spec; *s != '\0'; /**/) | |
1892 | { | |
1893 | while (isspace(*s)) ++s; | |
1894 | if (*s == '\0') | |
1895 | break; | |
1896 | if (*s != '+' && *s != '-') | |
1897 | { | |
1898 | DEBUG(D_tls) debug_printf("malformed openssl option setting: " | |
0e944a0d | 1899 | "+ or - expected but found \"%s\"\n", s); |
77bb000f PP |
1900 | return FALSE; |
1901 | } | |
1902 | adding = *s++ == '+'; | |
1903 | for (end = s; (*end != '\0') && !isspace(*end); ++end) /**/ ; | |
1904 | keep_c = *end; | |
1905 | *end = '\0'; | |
1906 | item_parsed = tls_openssl_one_option_parse(s, &item); | |
1907 | if (!item_parsed) | |
1908 | { | |
0e944a0d | 1909 | DEBUG(D_tls) debug_printf("openssl option setting unrecognised: \"%s\"\n", s); |
77bb000f PP |
1910 | return FALSE; |
1911 | } | |
1912 | DEBUG(D_tls) debug_printf("openssl option, %s from %lx: %lx (%s)\n", | |
1913 | adding ? "adding" : "removing", result, item, s); | |
1914 | if (adding) | |
1915 | result |= item; | |
1916 | else | |
1917 | result &= ~item; | |
1918 | *end = keep_c; | |
1919 | s = end; | |
1920 | } | |
1921 | ||
1922 | *results = result; | |
1923 | return TRUE; | |
1924 | } | |
1925 | ||
059ec3d9 | 1926 | /* End of tls-openssl.c */ |