1 /* $NetBSD: tls_client.c,v 1.14 2025/02/25 19:15:50 christos Exp $ */
2
3 /*++
4 /* NAME
5 /* tls_client
6 /* SUMMARY
7 /* client-side TLS engine
8 /* SYNOPSIS
9 /* #include <tls.h>
10 /*
11 /* TLS_APPL_STATE *tls_client_init(init_props)
12 /* const TLS_CLIENT_INIT_PROPS *init_props;
13 /*
14 /* TLS_SESS_STATE *tls_client_start(start_props)
15 /* const TLS_CLIENT_START_PROPS *start_props;
16 /*
17 /* TLS_SESS_STATE *tls_client_post_connect(TLScontext, start_props)
18 /* TLS_SESS_STATE *TLScontext;
19 /* const TLS_CLIENT_START_PROPS *start_props;
20 /*
21 /* void tls_client_stop(app_ctx, stream, failure, TLScontext)
22 /* TLS_APPL_STATE *app_ctx;
23 /* VSTREAM *stream;
24 /* int failure;
25 /* TLS_SESS_STATE *TLScontext;
26 /* DESCRIPTION
27 /* This module is the interface between Postfix TLS clients,
28 /* the OpenSSL library and the TLS entropy and cache manager.
29 /*
30 /* The SMTP client will attempt to verify the server hostname
31 /* against the names listed in the server certificate. When
32 /* a hostname match is required, the verification fails
33 /* on certificate verification or hostname mis-match errors.
34 /* When no hostname match is required, hostname verification
35 /* failures are logged but they do not affect the TLS handshake
36 /* or the SMTP session.
37 /*
38 /* The rules for peer name wild-card matching differ between
39 /* RFC 2818 (HTTP over TLS) and RFC 2830 (LDAP over TLS), while
40 /* RFC RFC3207 (SMTP over TLS) does not specify a rule at all.
41 /* Postfix uses a restrictive match algorithm. One asterisk
42 /* ('*') is allowed as the left-most component of a wild-card
43 /* certificate name; it matches the left-most component of
44 /* the peer hostname.
45 /*
46 /* Another area where RFCs aren't always explicit is the
47 /* handling of dNSNames in peer certificates. RFC 3207 (SMTP
48 /* over TLS) does not mention dNSNames. Postfix follows the
49 /* strict rules in RFC 2818 (HTTP over TLS), section 3.1: The
50 /* Subject Alternative Name/dNSName has precedence over
51 /* CommonName. If at least one dNSName is provided, Postfix
52 /* verifies those against the peer hostname and ignores the
53 /* CommonName, otherwise Postfix verifies the CommonName
54 /* against the peer hostname.
55 /*
56 /* tls_client_init() is called once when the SMTP client
57 /* initializes.
58 /* Certificate details are also decided during this phase,
59 /* so peer-specific certificate selection is not possible.
60 /*
61 /* tls_client_start() activates the TLS session over an established
62 /* stream. We expect that network buffers are flushed and
63 /* the TLS handshake can begin immediately.
64 /*
65 /* tls_client_stop() sends the "close notify" alert via
66 /* SSL_shutdown() to the peer and resets all connection specific
67 /* TLS data. As RFC2487 does not specify a separate shutdown, it
68 /* is assumed that the underlying TCP connection is shut down
69 /* immediately afterwards. Any further writes to the channel will
70 /* be discarded, and any further reads will report end-of-file.
71 /* If the failure flag is set, no SSL_shutdown() handshake is performed.
72 /*
73 /* Once the TLS connection is initiated, information about the TLS
74 /* state is available via the TLScontext structure:
75 /* .IP TLScontext->protocol
76 /* the protocol name (SSLv2, SSLv3, TLSv1),
77 /* .IP TLScontext->cipher_name
78 /* the cipher name (e.g. RC4/MD5),
79 /* .IP TLScontext->cipher_usebits
80 /* the number of bits actually used (e.g. 40),
81 /* .IP TLScontext->cipher_algbits
82 /* the number of bits the algorithm is based on (e.g. 128).
83 /* .PP
84 /* The last two values may differ from each other when export-strength
85 /* encryption is used.
86 /*
87 /* If the peer offered a certificate, part of the certificate data are
88 /* available as:
89 /* .IP TLScontext->peer_status
90 /* A bitmask field that records the status of the peer certificate
91 /* verification. This consists of one or more of TLS_CRED_FLAG_CERT,
92 /* TLS_CRED_FLAG_RPK, TLS_CERT_FLAG_TRUSTED, TLS_CERT_FLAG_MATCHED and
93 /* TLS_CERT_FLAG_SECURED.
94 /* .IP TLScontext->peer_CN
95 /* Extracted CommonName of the peer, or zero-length string if the
96 /* information could not be extracted.
97 /* .IP TLScontext->issuer_CN
98 /* Extracted CommonName of the issuer, or zero-length string if the
99 /* information could not be extracted.
100 /* .IP TLScontext->peer_cert_fprint
101 /* At the fingerprint security level, if the peer presented a certificate
102 /* the fingerprint of the certificate.
103 /* .PP
104 /* If no peer certificate is presented the peer_status is set to 0.
105 /* EVENT_DRIVEN APPLICATIONS
106 /* .ad
107 /* .fi
108 /* Event-driven programs manage multiple I/O channels. Such
109 /* programs cannot use the synchronous VSTREAM-over-TLS
110 /* implementation that the TLS library historically provides,
111 /* including tls_client_stop() and the underlying tls_stream(3)
112 /* and tls_bio_ops(3) routines.
113 /*
114 /* With the current TLS library implementation, this means
115 /* that an event-driven application is responsible for calling
116 /* and retrying SSL_connect(), SSL_read(), SSL_write() and
117 /* SSL_shutdown().
118 /*
119 /* To maintain control over TLS I/O, an event-driven client
120 /* invokes tls_client_start() with a null VSTREAM argument and
121 /* with an fd argument that specifies the I/O file descriptor.
122 /* Then, tls_client_start() performs all the necessary
123 /* preparations before the TLS handshake and returns a partially
124 /* populated TLS context. The event-driven application is then
125 /* responsible for invoking SSL_connect(), and if successful,
126 /* for invoking tls_client_post_connect() to finish the work
127 /* that was started by tls_client_start(). In case of unrecoverable
128 /* failure, tls_client_post_connect() destroys the TLS context
129 /* and returns a null pointer value.
130 /* LICENSE
131 /* .ad
132 /* .fi
133 /* This software is free. You can do with it whatever you want.
134 /* The original author kindly requests that you acknowledge
135 /* the use of his software.
136 /* AUTHOR(S)
137 /* Originally written by:
138 /* Lutz Jaenicke
139 /* BTU Cottbus
140 /* Allgemeine Elektrotechnik
141 /* Universitaetsplatz 3-4
142 /* D-03044 Cottbus, Germany
143 /*
144 /* Updated by:
145 /* Wietse Venema
146 /* IBM T.J. Watson Research
147 /* P.O. Box 704
148 /* Yorktown Heights, NY 10598, USA
149 /*
150 /* Wietse Venema
151 /* Google, Inc.
152 /* 111 8th Avenue
153 /* New York, NY 10011, USA
154 /*
155 /* Victor Duchovni
156 /* Morgan Stanley
157 /*
158 /* Wietse Venema
159 /* porcupine.org
160 /*--*/
161
162 /* System library. */
163
164 #include <sys_defs.h>
165
166 #ifdef USE_TLS
167 #include <string.h>
168 #include <tlsrpt_wrapper.h>
169
170 #ifdef STRCASECMP_IN_STRINGS_H
171 #include <strings.h>
172 #endif
173
174 /* Utility library. */
175
176 #include <argv.h>
177 #include <mymalloc.h>
178 #include <vstring.h>
179 #include <vstream.h>
180 #include <stringops.h>
181 #include <msg.h>
182 #include <iostuff.h> /* non-blocking */
183 #include <midna_domain.h>
184
185 /* Global library. */
186
187 #include <mail_params.h>
188
189 /* TLS library. */
190
191 #include <tls_mgr.h>
192 #define TLS_INTERNAL
193 #include <tls.h>
194
195 /* Application-specific. */
196
197 #define STR vstring_str
198 #define LEN VSTRING_LEN
199
200 /* load_clnt_session - load session from client cache (non-callback) */
201
load_clnt_session(TLS_SESS_STATE * TLScontext)202 static SSL_SESSION *load_clnt_session(TLS_SESS_STATE *TLScontext)
203 {
204 const char *myname = "load_clnt_session";
205 SSL_SESSION *session = 0;
206 VSTRING *session_data = vstring_alloc(2048);
207
208 /*
209 * Prepare the query.
210 */
211 if (TLScontext->log_mask & TLS_LOG_CACHE)
212 /* serverid contains transport:addr:port information */
213 msg_info("looking for session %s in %s cache",
214 TLScontext->serverid, TLScontext->cache_type);
215
216 /*
217 * We only get here if the cache_type is not empty. This code is not
218 * called unless caching is enabled and the cache_type is stored in the
219 * server SSL context.
220 */
221 if (TLScontext->cache_type == 0)
222 msg_panic("%s: null client session cache type in session lookup",
223 myname);
224
225 /*
226 * Look up and activate the SSL_SESSION object. Errors are non-fatal,
227 * since caching is only an optimization.
228 */
229 if (tls_mgr_lookup(TLScontext->cache_type, TLScontext->serverid,
230 session_data) == TLS_MGR_STAT_OK) {
231 session = tls_session_activate(STR(session_data), LEN(session_data));
232 if (session) {
233 if (TLScontext->log_mask & TLS_LOG_CACHE)
234 /* serverid contains transport:addr:port information */
235 msg_info("reloaded session %s from %s cache",
236 TLScontext->serverid, TLScontext->cache_type);
237 }
238 }
239
240 /*
241 * Clean up.
242 */
243 vstring_free(session_data);
244
245 return (session);
246 }
247
248 /* new_client_session_cb - name new session and save it to client cache */
249
new_client_session_cb(SSL * ssl,SSL_SESSION * session)250 static int new_client_session_cb(SSL *ssl, SSL_SESSION *session)
251 {
252 const char *myname = "new_client_session_cb";
253 TLS_SESS_STATE *TLScontext;
254 VSTRING *session_data;
255
256 /*
257 * The cache name (if caching is enabled in tlsmgr(8)) and the cache ID
258 * string for this session are stored in the TLScontext. It cannot be
259 * null at this point.
260 */
261 if ((TLScontext = SSL_get_ex_data(ssl, TLScontext_index)) == 0)
262 msg_panic("%s: null TLScontext in new session callback", myname);
263
264 /*
265 * We only get here if the cache_type is not empty. This callback is not
266 * set unless caching is enabled and the cache_type is stored in the
267 * server SSL context.
268 */
269 if (TLScontext->cache_type == 0)
270 msg_panic("%s: null session cache type in new session callback",
271 myname);
272
273 if (TLScontext->log_mask & TLS_LOG_CACHE)
274 /* serverid contains transport:addr:port information */
275 msg_info("save session %s to %s cache",
276 TLScontext->serverid, TLScontext->cache_type);
277
278 /*
279 * Passivate and save the session object. Errors are non-fatal, since
280 * caching is only an optimization.
281 */
282 if ((session_data = tls_session_passivate(session)) != 0) {
283 tls_mgr_update(TLScontext->cache_type, TLScontext->serverid,
284 STR(session_data), LEN(session_data));
285 vstring_free(session_data);
286 }
287
288 /*
289 * Clean up.
290 */
291 SSL_SESSION_free(session); /* 200502 */
292
293 return (1);
294 }
295
296 /* uncache_session - remove session from the external cache */
297
uncache_session(SSL_CTX * ctx,TLS_SESS_STATE * TLScontext)298 static void uncache_session(SSL_CTX *ctx, TLS_SESS_STATE *TLScontext)
299 {
300 SSL_SESSION *session = SSL_get_session(TLScontext->con);
301
302 SSL_CTX_remove_session(ctx, session);
303 if (TLScontext->cache_type == 0 || TLScontext->serverid == 0)
304 return;
305
306 if (TLScontext->log_mask & TLS_LOG_CACHE)
307 /* serverid contains transport:addr:port information */
308 msg_info("remove session %s from client cache", TLScontext->serverid);
309
310 tls_mgr_delete(TLScontext->cache_type, TLScontext->serverid);
311 }
312
313 /* verify_x509 - process X.509 certificate verification status */
314
verify_x509(TLS_SESS_STATE * TLScontext,X509 * peercert,const TLS_CLIENT_START_PROPS * props)315 static void verify_x509(TLS_SESS_STATE *TLScontext, X509 *peercert,
316 const TLS_CLIENT_START_PROPS *props)
317 {
318
319 /*
320 * On exit both peer_CN and issuer_CN should be set.
321 */
322 TLScontext->issuer_CN = tls_issuer_CN(peercert, TLScontext);
323 TLScontext->peer_CN = tls_peer_CN(peercert, TLScontext);
324
325 /*
326 * Is the certificate trust chain trusted and matched? Any required name
327 * checks are now performed internally in OpenSSL.
328 */
329 if (SSL_get_verify_result(TLScontext->con) == X509_V_OK) {
330 TLScontext->peer_status |= TLS_CERT_FLAG_TRUSTED;
331 if (TLScontext->must_fail) {
332 msg_panic("%s: cert valid despite trust init failure",
333 TLScontext->namaddr);
334 } else if (TLS_MUST_MATCH(TLScontext->level)) {
335
336 /*
337 * Fully secured only if not insecure like half-dane. We use
338 * TLS_CERT_FLAG_MATCHED to satisfy policy, but
339 * TLS_CERT_FLAG_SECURED to log the effective security.
340 *
341 * Would ideally also exclude "verify" (as opposed to "secure")
342 * here, because that can be subject to insecure MX indirection,
343 * but that's rather incompatible (and not even the case with
344 * explicitly chosen non-default match patterns). Users have
345 * been warned.
346 */
347 if (!TLS_NEVER_SECURED(TLScontext->level))
348 TLScontext->peer_status |= TLS_CERT_FLAG_SECURED;
349 TLScontext->peer_status |= TLS_CERT_FLAG_MATCHED;
350
351 if (TLScontext->log_mask &
352 (TLS_LOG_CERTMATCH | TLS_LOG_VERBOSE | TLS_LOG_PEERCERT)) {
353 const char *peername = SSL_get0_peername(TLScontext->con);
354
355 if (peername)
356 msg_info("%s: matched peername: %s",
357 TLScontext->namaddr, peername);
358 tls_dane_log(TLScontext);
359 }
360 }
361 }
362
363 /*
364 * Give them a clue. Problems with trust chain verification are logged
365 * when the session is first negotiated, before the session is stored
366 * into the cache. We don't want mystery failures, so log the fact the
367 * real problem is to be found in the past.
368 */
369 if (!TLS_CERT_IS_MATCHED(TLScontext)
370 && (TLScontext->log_mask & TLS_LOG_UNTRUSTED)) {
371 if (TLScontext->session_reused == 0)
372 tls_log_verify_error(TLScontext, props->tlsrpt);
373 else
374 msg_info("%s: re-using session with untrusted peer credential, "
375 "look for details earlier in the log", props->namaddr);
376 }
377 }
378
379 /* verify_rpk - process RFC7250 raw public key verification status */
380
verify_rpk(TLS_SESS_STATE * TLScontext,EVP_PKEY * peerpkey,const TLS_CLIENT_START_PROPS * props)381 static void verify_rpk(TLS_SESS_STATE *TLScontext, EVP_PKEY *peerpkey,
382 const TLS_CLIENT_START_PROPS *props)
383 {
384 /* Was the raw public key (type of cert) matched? */
385 if (SSL_get_verify_result(TLScontext->con) == X509_V_OK) {
386 TLScontext->peer_status |= TLS_CERT_FLAG_TRUSTED;
387 if (TLScontext->must_fail) {
388 msg_panic("%s: raw public key valid despite trust init failure",
389 TLScontext->namaddr);
390 } else if (TLS_MUST_MATCH(TLScontext->level)) {
391
392 /*
393 * Fully secured only if not insecure like half-dane. We use
394 * TLS_CERT_FLAG_MATCHED to satisfy policy, but
395 * TLS_CERT_FLAG_SECURED to log the effective security.
396 */
397 if (!TLS_NEVER_SECURED(TLScontext->level))
398 TLScontext->peer_status |= TLS_CERT_FLAG_SECURED;
399 TLScontext->peer_status |= TLS_CERT_FLAG_MATCHED;
400
401 if (TLScontext->log_mask &
402 (TLS_LOG_CERTMATCH | TLS_LOG_VERBOSE | TLS_LOG_PEERCERT))
403 tls_dane_log(TLScontext);
404 }
405 }
406
407 /*
408 * Give them a clue. Problems with trust chain verification are logged
409 * when the session is first negotiated, before the session is stored
410 * into the cache. We don't want mystery failures, so log the fact the
411 * real problem is to be found in the past.
412 */
413 if (!TLS_CERT_IS_MATCHED(TLScontext)
414 && (TLScontext->log_mask & TLS_LOG_UNTRUSTED)) {
415 if (TLScontext->session_reused == 0)
416 tls_log_verify_error(TLScontext, props->tlsrpt);
417 else
418 msg_info("%s: re-using session with untrusted certificate, "
419 "look for details earlier in the log", props->namaddr);
420 }
421 }
422
423 /* add_namechecks - tell OpenSSL what names to check */
424
add_namechecks(TLS_SESS_STATE * TLScontext,const TLS_CLIENT_START_PROPS * props)425 static void add_namechecks(TLS_SESS_STATE *TLScontext,
426 const TLS_CLIENT_START_PROPS *props)
427 {
428 SSL *ssl = TLScontext->con;
429 int namechecks_count = 0;
430 int i;
431
432 /* RFC6125: No part-label 'foo*bar.example.com' wildcards for SMTP */
433 SSL_set_hostflags(ssl, X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS);
434
435 for (i = 0; i < props->matchargv->argc; ++i) {
436 const char *name = props->matchargv->argv[i];
437 const char *aname;
438 int match_subdomain = 0;
439
440 if (strcasecmp(name, "nexthop") == 0) {
441 name = props->nexthop;
442 } else if (strcasecmp(name, "dot-nexthop") == 0) {
443 name = props->nexthop;
444 match_subdomain = 1;
445 } else if (strcasecmp(name, "hostname") == 0) {
446 name = props->host;
447 } else {
448 if (*name == '.') {
449 if (*++name == 0) {
450 msg_warn("%s: ignoring invalid match name: \".\"",
451 TLScontext->namaddr);
452 continue;
453 }
454 match_subdomain = 1;
455 }
456 #ifndef NO_EAI
457 else {
458
459 /*
460 * Besides U+002E (full stop) IDNA2003 allows labels to be
461 * separated by any of the Unicode variants U+3002
462 * (ideographic full stop), U+FF0E (fullwidth full stop), and
463 * U+FF61 (halfwidth ideographic full stop). Their respective
464 * UTF-8 encodings are: E38082, EFBC8E and EFBDA1.
465 *
466 * IDNA2008 does not permit (upper) case and other variant
467 * differences in U-labels. The midna_domain_to_ascii()
468 * function, based on UTS46, normalizes such differences
469 * away.
470 *
471 * The IDNA to_ASCII conversion does not allow empty leading
472 * labels, so we handle these explicitly here.
473 */
474 unsigned char *cp = (unsigned char *) name;
475
476 if ((cp[0] == 0xe3 && cp[1] == 0x80 && cp[2] == 0x82)
477 || (cp[0] == 0xef && cp[1] == 0xbc && cp[2] == 0x8e)
478 || (cp[0] == 0xef && cp[1] == 0xbd && cp[2] == 0xa1)) {
479 if (name[3]) {
480 name = name + 3;
481 match_subdomain = 1;
482 }
483 }
484 }
485 #endif
486 }
487
488 /*
489 * DNS subjectAltNames are required to be ASCII.
490 *
491 * Per RFC 6125 Section 6.4.4 Matching the CN-ID, follows the same rules
492 * (6.4.1, 6.4.2 and 6.4.3) that apply to subjectAltNames. In
493 * particular, 6.4.2 says that the reference identifier is coerced to
494 * ASCII, but no conversion is stated or implied for the CN-ID, so it
495 * seems it only matches if it is all ASCII. Otherwise, it is some
496 * other sort of name.
497 */
498 #ifndef NO_EAI
499 if (!allascii(name) && (aname = midna_domain_to_ascii(name)) != 0) {
500 if (msg_verbose)
501 msg_info("%s asciified to %s", name, aname);
502 name = aname;
503 }
504 #endif
505
506 if (!match_subdomain) {
507 if (SSL_add1_host(ssl, name))
508 ++namechecks_count;
509 else
510 msg_warn("%s: error loading match name: \"%s\"",
511 TLScontext->namaddr, name);
512 } else {
513 char *dot_name = concatenate(".", name, (char *) 0);
514
515 if (SSL_add1_host(ssl, dot_name))
516 ++namechecks_count;
517 else
518 msg_warn("%s: error loading match name: \"%s\"",
519 TLScontext->namaddr, dot_name);
520 myfree(dot_name);
521 }
522 }
523
524 /*
525 * If we failed to add any names, OpenSSL will perform no namechecks, so
526 * we set the "must_fail" bit to avoid verification false-positives.
527 */
528 if (namechecks_count == 0) {
529 msg_warn("%s: could not configure peer name checks",
530 TLScontext->namaddr);
531 TLScontext->must_fail = 1;
532 }
533 }
534
535 /* tls_auth_enable - set up TLS authentication */
536
tls_auth_enable(TLS_SESS_STATE * TLScontext,const TLS_CLIENT_START_PROPS * props)537 static int tls_auth_enable(TLS_SESS_STATE *TLScontext,
538 const TLS_CLIENT_START_PROPS *props)
539 {
540 const char *sni = 0;
541
542 if (props->sni && *props->sni) {
543 #ifndef NO_EAI
544 const char *aname;
545
546 #endif
547
548 /*
549 * MTA-STS policy plugin compatibility: with servername=hostname,
550 * Postfix must send the MX hostname (not CNAME expanded).
551 */
552 if (strcmp(props->sni, "hostname") == 0)
553 sni = props->host;
554 else if (strcmp(props->sni, "nexthop") == 0)
555 sni = props->nexthop;
556 else
557 sni = props->sni;
558
559 /*
560 * The SSL_set_tlsext_host_name() documentation does not promise that
561 * every implementation will convert U-label form to A-label form.
562 */
563 #ifndef NO_EAI
564 if (!allascii(sni) && (aname = midna_domain_to_ascii(sni)) != 0) {
565 if (msg_verbose)
566 msg_info("%s asciified to %s", sni, aname);
567 sni = aname;
568 }
569 #endif
570 }
571 switch (TLScontext->level) {
572 case TLS_LEV_HALF_DANE:
573 case TLS_LEV_DANE:
574 case TLS_LEV_DANE_ONLY:
575
576 /*
577 * With DANE sessions, send an SNI hint. We don't care whether the
578 * server reports finding a matching certificate or not, so no
579 * callback is required to process the server response. Our use of
580 * SNI is limited to giving servers that make use of SNI the best
581 * opportunity to find the certificate they promised via the
582 * associated TLSA RRs.
583 *
584 * Since the hostname is DNSSEC-validated, it must be a DNS FQDN and
585 * therefore valid for use with SNI.
586 */
587 if (SSL_dane_enable(TLScontext->con, 0) <= 0) {
588 /* TLSRPT: Local resource error, don't report. */
589 msg_warn("%s: error enabling DANE-based certificate validation",
590 TLScontext->namaddr);
591 tls_print_errors();
592 return (0);
593 }
594 /* RFC7672 Section 3.1.1 specifies no name checks for DANE-EE(3) */
595 SSL_dane_set_flags(TLScontext->con, DANE_FLAG_NO_DANE_EE_NAMECHECKS);
596
597 /* Per RFC7672 the SNI name is the TLSA base domain */
598 sni = props->dane->base_domain;
599 add_namechecks(TLScontext, props);
600 break;
601
602 case TLS_LEV_FPRINT:
603 /* Synthetic DANE for fingerprint security */
604 if (SSL_dane_enable(TLScontext->con, 0) <= 0) {
605 /* TLSRPT: Local resource error, don't report. */
606 msg_warn("%s: error enabling fingerprint certificate validation",
607 props->namaddr);
608 tls_print_errors();
609 return (0);
610 }
611 SSL_dane_set_flags(TLScontext->con, DANE_FLAG_NO_DANE_EE_NAMECHECKS);
612 break;
613
614 case TLS_LEV_SECURE:
615 case TLS_LEV_VERIFY:
616 if (TLScontext->dane != 0 && TLScontext->dane->tlsa != 0) {
617 /* Synthetic DANE for per-destination trust-anchors */
618 if (SSL_dane_enable(TLScontext->con, NULL) <= 0) {
619 /* TLSRPT: Local resource error, don't report. */
620 msg_warn("%s: error configuring local trust anchors",
621 props->namaddr);
622 tls_print_errors();
623 return (0);
624 }
625 }
626 add_namechecks(TLScontext, props);
627 break;
628 default:
629 break;
630 }
631
632 if (sni) {
633 if (strlen(sni) > TLSEXT_MAXLEN_host_name) {
634 /* TLSRPT: Local configuration error, don't report. */
635 msg_warn("%s: ignoring too long SNI hostname: %.100s",
636 props->namaddr, sni);
637 return (0);
638 }
639
640 /*
641 * Failure to set a valid SNI hostname is a memory allocation error,
642 * and thus transient. Since we must not cache the session if we
643 * failed to send the SNI name, we have little choice but to abort.
644 */
645 if (!SSL_set_tlsext_host_name(TLScontext->con, sni)) {
646 /* TLSRPT: Local resource or configuration error, don't report. */
647 msg_warn("%s: error setting SNI hostname to: %s", props->namaddr,
648 sni);
649 return (0);
650 }
651
652 /*
653 * The saved value is not presently used client-side, but could later
654 * be logged if acked by the server (requires new client-side
655 * callback to detect the ack). For now this just maintains symmetry
656 * with the server code, where do record the received SNI for
657 * logging.
658 */
659 TLScontext->peer_sni = mystrdup(sni);
660 if (TLScontext->log_mask & TLS_LOG_DEBUG)
661 msg_info("%s: SNI hostname: %s", props->namaddr, sni);
662 }
663 return (1);
664 }
665
666 /* tls_client_init - initialize client-side TLS engine */
667
tls_client_init(const TLS_CLIENT_INIT_PROPS * props)668 TLS_APPL_STATE *tls_client_init(const TLS_CLIENT_INIT_PROPS *props)
669 {
670 SSL_CTX *client_ctx;
671 TLS_APPL_STATE *app_ctx;
672 const EVP_MD *fpt_alg;
673 long off = 0;
674 int cachable;
675 int scache_timeout;
676 int log_mask;
677
678 /*
679 * Convert user loglevel to internal logmask.
680 */
681 log_mask = tls_log_mask(props->log_param, props->log_level);
682
683 if (log_mask & TLS_LOG_VERBOSE)
684 msg_info("initializing the client-side TLS engine");
685
686 /*
687 * Load (mostly cipher related) TLS-library internal main.cf parameters.
688 */
689 tls_param_init();
690
691 /*
692 * Detect mismatch between compile-time headers and run-time library.
693 */
694 tls_check_version();
695
696 /*
697 * Initialize the OpenSSL library, possibly loading its configuration
698 * file.
699 */
700 if (tls_library_init() == 0)
701 return (0);
702
703 /*
704 * Create an application data index for SSL objects, so that we can
705 * attach TLScontext information; this information is needed inside
706 * tls_verify_certificate_callback().
707 */
708 if (TLScontext_index < 0) {
709 if ((TLScontext_index = SSL_get_ex_new_index(0, 0, 0, 0, 0)) < 0) {
710 msg_warn("Cannot allocate SSL application data index: "
711 "disabling TLS support");
712 return (0);
713 }
714 }
715
716 /*
717 * If the administrator specifies an unsupported digest algorithm, fail
718 * now, rather than in the middle of a TLS handshake.
719 */
720 if ((fpt_alg = tls_validate_digest(props->mdalg)) == 0) {
721 msg_warn("disabling TLS support");
722 return (0);
723 }
724
725 /*
726 * Initialize the PRNG (Pseudo Random Number Generator) with some seed
727 * from external and internal sources. Don't enable TLS without some real
728 * entropy.
729 */
730 if (tls_ext_seed(var_tls_daemon_rand_bytes) < 0) {
731 msg_warn("no entropy for TLS key generation: disabling TLS support");
732 return (0);
733 }
734 tls_int_seed();
735
736 /*
737 * The SSL/TLS specifications require the client to send a message in the
738 * oldest specification it understands with the highest level it
739 * understands in the message. RFC2487 is only specified for TLSv1, but
740 * we want to be as compatible as possible, so we will start off with a
741 * SSLv2 greeting allowing the best we can offer: TLSv1. We can restrict
742 * this with the options setting later, anyhow.
743 */
744 ERR_clear_error();
745 client_ctx = SSL_CTX_new(TLS_client_method());
746 if (client_ctx == 0) {
747 msg_warn("cannot allocate client SSL_CTX: disabling TLS support");
748 tls_print_errors();
749 return (0);
750 }
751 #ifdef SSL_SECOP_PEER
752 /* Backwards compatible security as a base for opportunistic TLS. */
753 SSL_CTX_set_security_level(client_ctx, 0);
754 #endif
755
756 /*
757 * See the verify callback in tls_verify.c
758 */
759 SSL_CTX_set_verify_depth(client_ctx, props->verifydepth + 1);
760
761 /*
762 * This is a prerequisite for enabling DANE support in OpenSSL, but not a
763 * commitment to use DANE, thus suitable for both DANE and non-DANE TLS
764 * connections. Indeed we need this not just for DANE, but aslo for
765 * fingerprint and "tafile" support. Since it just allocates memory, it
766 * should never fail except when we're likely to fail anyway. Rather
767 * than try to run with crippled TLS support, just give up using TLS.
768 */
769 if (SSL_CTX_dane_enable(client_ctx) <= 0) {
770 msg_warn("OpenSSL DANE initialization failed: disabling TLS support");
771 tls_print_errors();
772 return (0);
773 }
774 tls_dane_digest_init(client_ctx, fpt_alg);
775
776 /*
777 * Presently we use TLS only with SMTP where truncation attacks are not
778 * possible as a result of application framing. If we ever use TLS in
779 * some other application protocol where truncation could be relevant,
780 * we'd need to disable truncation detection conditionally, or explicitly
781 * clear the option in that code path.
782 */
783 off |= SSL_OP_IGNORE_UNEXPECTED_EOF;
784
785 /*
786 * Protocol selection is destination dependent, so we delay the protocol
787 * selection options to the per-session SSL object.
788 */
789 off |= tls_bug_bits();
790 SSL_CTX_set_options(client_ctx, off);
791
792 /*
793 * Set the call-back routine for verbose logging.
794 */
795 if (log_mask & TLS_LOG_DEBUG)
796 SSL_CTX_set_info_callback(client_ctx, tls_info_callback);
797
798 /*
799 * Load the CA public key certificates for both the client cert and for
800 * the verification of server certificates. As provided by OpenSSL we
801 * support two types of CA certificate handling: One possibility is to
802 * add all CA certificates to one large CAfile, the other possibility is
803 * a directory pointed to by CApath, containing separate files for each
804 * CA with softlinks named after the hash values of the certificate. The
805 * first alternative has the advantage that the file is opened and read
806 * at startup time, so that you don't have the hassle to maintain another
807 * copy of the CApath directory for chroot-jail.
808 */
809 if (tls_set_ca_certificate_info(client_ctx,
810 props->CAfile, props->CApath) < 0) {
811 /* tls_set_ca_certificate_info() already logs a warning. */
812 SSL_CTX_free(client_ctx); /* 200411 */
813 return (0);
814 }
815
816 /*
817 * We do not need a client certificate, so the certificates are only
818 * loaded (and checked) if supplied. A clever client would handle
819 * multiple client certificates and decide based on the list of
820 * acceptable CAs, sent by the server, which certificate to submit.
821 * OpenSSL does however not do this and also has no call-back hooks to
822 * easily implement it.
823 *
824 * Load the client public key certificate and private key from file and
825 * check whether the cert matches the key. We can use RSA certificates
826 * ("cert") DSA certificates ("dcert") or ECDSA certificates ("eccert").
827 * All three can be made available at the same time. The CA certificates
828 * for all three are handled in the same setup already finished. Which
829 * one is used depends on the cipher negotiated (that is: the first
830 * cipher listed by the client which does match the server). The client
831 * certificate is presented after the server chooses the session cipher,
832 * so we will just present the right cert for the chosen cipher (if it
833 * uses certificates).
834 */
835 if (tls_set_my_certificate_key_info(client_ctx,
836 props->chain_files,
837 props->cert_file,
838 props->key_file,
839 props->dcert_file,
840 props->dkey_file,
841 props->eccert_file,
842 props->eckey_file) < 0) {
843 /* tls_set_my_certificate_key_info() already logs a warning. */
844 SSL_CTX_free(client_ctx); /* 200411 */
845 return (0);
846 }
847
848 /*
849 * Enable support for client->server raw public keys, provided we
850 * actually have keys to send. They'll only be used if the server also
851 * enables client RPKs.
852 *
853 * XXX: When the server requests client auth, the TLS 1.2 protocol does not
854 * provide an unambiguous mechanism for the client to not send an RPK (as
855 * it can with client X.509 certs or TLS 1.3). This is why we don't just
856 * enable client RPK also with no keys in hand.
857 *
858 * A very unlikely scenario is that the server allows clients to not send
859 * keys, but only accepts keys for a set of algorithms we don't have.
860 * Then we still can't send a key, but have agreed to RPK. OpenSSL will
861 * attempt to send an empty RPK even with TLS 1.2 (and will accept such a
862 * message), but other implementations may be more strict.
863 *
864 * We could limit client RPK support to connections that support only TLS
865 * 1.3 and up, but that's practical only decades in the future, and the
866 * risk scenario is contrived and very unlikely.
867 */
868 if (SSL_CTX_get0_certificate(client_ctx) != NULL &&
869 SSL_CTX_get0_privatekey(client_ctx) != NULL)
870 tls_enable_client_rpk(client_ctx, NULL);
871
872 /*
873 * With OpenSSL 1.0.2 and later the client EECDH curve list becomes
874 * configurable with the preferred curve negotiated via the supported
875 * curves extension. With OpenSSL 3.0 and TLS 1.3, the same applies to
876 * the FFDHE groups which become part of a unified "groups" list.
877 */
878 tls_auto_groups(client_ctx, var_tls_eecdh_auto, var_tls_ffdhe_auto);
879
880 /*
881 * Finally, the setup for the server certificate checking, done "by the
882 * book".
883 */
884 SSL_CTX_set_verify(client_ctx, SSL_VERIFY_NONE,
885 tls_verify_certificate_callback);
886
887 /*
888 * Initialize the session cache.
889 *
890 * Since the client does not search an internal cache, we simply disable it.
891 * It is only useful for expiring old sessions, but we do that in the
892 * tlsmgr(8).
893 *
894 * This makes SSL_CTX_remove_session() not useful for flushing broken
895 * sessions from the external cache, so we must delete them directly (not
896 * via a callback).
897 */
898 if (tls_mgr_policy(props->cache_type, &cachable,
899 &scache_timeout) != TLS_MGR_STAT_OK)
900 scache_timeout = 0;
901 if (scache_timeout <= 0)
902 cachable = 0;
903
904 /*
905 * Allocate an application context, and populate with mandatory protocol
906 * and cipher data.
907 */
908 app_ctx = tls_alloc_app_context(client_ctx, 0, log_mask);
909
910 /*
911 * The external session cache is implemented by the tlsmgr(8) process.
912 */
913 if (cachable) {
914
915 app_ctx->cache_type = mystrdup(props->cache_type);
916
917 /*
918 * OpenSSL does not use callbacks to load sessions from a client
919 * cache, so we must invoke that function directly. Apparently,
920 * OpenSSL does not provide a way to pass session names from here to
921 * call-back routines that do session lookup.
922 *
923 * OpenSSL can, however, automatically save newly created sessions for
924 * us by callback (we create the session name in the call-back
925 * function).
926 *
927 * XXX gcc 2.95 can't compile #ifdef .. #endif in the expansion of
928 * SSL_SESS_CACHE_CLIENT | SSL_SESS_CACHE_NO_INTERNAL_STORE |
929 * SSL_SESS_CACHE_NO_AUTO_CLEAR.
930 */
931 #ifndef SSL_SESS_CACHE_NO_INTERNAL_STORE
932 #define SSL_SESS_CACHE_NO_INTERNAL_STORE 0
933 #endif
934
935 SSL_CTX_set_session_cache_mode(client_ctx,
936 SSL_SESS_CACHE_CLIENT |
937 SSL_SESS_CACHE_NO_INTERNAL_STORE |
938 SSL_SESS_CACHE_NO_AUTO_CLEAR);
939 SSL_CTX_sess_set_new_cb(client_ctx, new_client_session_cb);
940
941 /*
942 * OpenSSL ignores timed-out sessions. We need to set the internal
943 * cache timeout at least as high as the external cache timeout. This
944 * applies even if no internal cache is used. We set the session to
945 * twice the cache lifetime. This way a session always lasts longer
946 * than its lifetime in the cache.
947 */
948 SSL_CTX_set_timeout(client_ctx, 2 * scache_timeout);
949 }
950 return (app_ctx);
951 }
952
953 /*
954 * This is the actual startup routine for the connection. We expect that the
955 * buffers are flushed and the "220 Ready to start TLS" was received by us,
956 * so that we can immediately start the TLS handshake process.
957 */
tls_client_start(const TLS_CLIENT_START_PROPS * props)958 TLS_SESS_STATE *tls_client_start(const TLS_CLIENT_START_PROPS *props)
959 {
960 int sts;
961 int protomask;
962 int min_proto;
963 int max_proto;
964 const char *cipher_list;
965 SSL_SESSION *session = 0;
966 TLS_SESS_STATE *TLScontext;
967 TLS_APPL_STATE *app_ctx = props->ctx;
968 int log_mask = app_ctx->log_mask;
969
970 /*
971 * When certificate verification is required, log trust chain validation
972 * errors even when disabled by default for opportunistic sessions. For
973 * DANE this only applies when using trust-anchor associations.
974 */
975 if (TLS_MUST_MATCH(props->tls_level))
976 log_mask |= TLS_LOG_UNTRUSTED;
977
978 if (log_mask & TLS_LOG_VERBOSE)
979 msg_info("setting up TLS connection to %s", props->namaddr);
980
981 /*
982 * First make sure we have valid protocol and cipher parameters
983 *
984 * Per-session protocol restrictions must be applied to the SSL connection,
985 * as restrictions in the global context cannot be cleared.
986 */
987 protomask = tls_proto_mask_lims(props->protocols, &min_proto, &max_proto);
988 if (protomask == TLS_PROTOCOL_INVALID) {
989 /* TLSRPT: Local configuration error, don't report. */
990 /* tls_protocol_mask() logs no warning. */
991 msg_warn("%s: Invalid TLS protocol list \"%s\": aborting TLS session",
992 props->namaddr, props->protocols);
993 return (0);
994 }
995
996 /*
997 * Though RFC7672 set the floor at SSLv3, we really can and should
998 * require TLS 1.0, since e.g. we send SNI, which is a TLS 1.0 extension.
999 * No DANE domains have been observed to support only SSLv3.
1000 *
1001 * XXX: Would be nice to make that TLS 1.2 at some point. Users can choose
1002 * to exclude TLS 1.0 and TLS 1.1 if they find they don't run into any
1003 * problems doing that.
1004 */
1005 if (TLS_DANE_BASED(props->tls_level))
1006 protomask |= TLS_PROTOCOL_SSLv2 | TLS_PROTOCOL_SSLv3;
1007
1008 /*
1009 * Allocate a new TLScontext for the new connection and get an SSL
1010 * structure. Add the location of TLScontext to the SSL to later retrieve
1011 * the information inside the tls_verify_certificate_callback().
1012 *
1013 * If session caching was enabled when TLS was initialized, the cache type
1014 * is stored in the client SSL context.
1015 */
1016 TLScontext = tls_alloc_sess_context(log_mask, props->namaddr);
1017 TLScontext->cache_type = app_ctx->cache_type;
1018 TLScontext->level = props->tls_level;
1019
1020 if ((TLScontext->con = SSL_new(app_ctx->ssl_ctx)) == NULL) {
1021 /* TLSRPT: Local resource error, don't report. */
1022 msg_warn("Could not allocate 'TLScontext->con' with SSL_new()");
1023 tls_print_errors();
1024 tls_free_context(TLScontext);
1025 return (0);
1026 }
1027
1028 /*
1029 * Per session cipher selection for sessions with mandatory encryption
1030 *
1031 * The cipherlist is applied to the global SSL context, since it is likely
1032 * to stay the same between connections, so we make use of a 1-element
1033 * cache to return the same result for identical inputs.
1034 */
1035 cipher_list = tls_set_ciphers(TLScontext, props->cipher_grade,
1036 props->cipher_exclusions);
1037 if (cipher_list == 0) {
1038 /* TLSRPT: Local configuration error, don't report. */
1039 /* already warned */
1040 tls_free_context(TLScontext);
1041 return (0);
1042 }
1043 if (log_mask & TLS_LOG_VERBOSE)
1044 msg_info("%s: TLS cipher list \"%s\"", props->namaddr, cipher_list);
1045
1046 TLScontext->stream = props->stream;
1047 TLScontext->mdalg = props->mdalg;
1048
1049 /* Alias DANE digest info from props */
1050 TLScontext->dane = props->dane;
1051
1052 if (!SSL_set_ex_data(TLScontext->con, TLScontext_index, TLScontext)) {
1053 /* TLSRPT: Local resource error, don't report. */
1054 msg_warn("Could not set application data for 'TLScontext->con'");
1055 tls_print_errors();
1056 tls_free_context(TLScontext);
1057 return (0);
1058 }
1059 #define CARP_VERSION(which) do { \
1060 if (which##_proto != 0) \
1061 msg_warn("%s: error setting %simum TLS version to: 0x%04x", \
1062 TLScontext->namaddr, #which, which##_proto); \
1063 else \
1064 msg_warn("%s: error clearing %simum TLS version", \
1065 TLScontext->namaddr, #which); \
1066 } while (0)
1067
1068 /*
1069 * Apply session protocol restrictions.
1070 */
1071 if (protomask != 0)
1072 SSL_set_options(TLScontext->con, TLS_SSL_OP_PROTOMASK(protomask));
1073 if (!SSL_set_min_proto_version(TLScontext->con, min_proto))
1074 CARP_VERSION(min);
1075 if (!SSL_set_max_proto_version(TLScontext->con, max_proto))
1076 CARP_VERSION(max);
1077
1078 /*
1079 * When applicable, configure DNS-based or synthetic (fingerprint or
1080 * local trust anchor) DANE authentication, enable an appropriate SNI
1081 * name and peer name matching.
1082 *
1083 * NOTE, this can change the effective security level, and needs to happen
1084 * early.
1085 */
1086 if (!tls_auth_enable(TLScontext, props)) {
1087 /* Already warned and reported TLSRPT result. */
1088 tls_free_context(TLScontext);
1089 return (0);
1090 }
1091
1092 /*
1093 * Possibly enable RFC7250 raw public keys in non-DANE/non-PKI levels
1094 * when the fingerprint mask includes only public keys. For "may" and
1095 * "encrypt" this is a heuristic, since we don't use the fingerprints
1096 * beyond reporting them in verbose logging. If you always want certs
1097 * with "may" and "encrypt" you'll have to tolerate them with
1098 * "fingerprint", or use a separate transport.
1099 */
1100 switch (props->tls_level) {
1101 case TLS_LEV_MAY:
1102 case TLS_LEV_ENCRYPT:
1103 case TLS_LEV_FPRINT:
1104 if (props->enable_rpk)
1105 tls_enable_server_rpk(NULL, TLScontext->con);
1106 default:
1107 break;
1108 }
1109
1110 /*
1111 * Try to convey the configured TLSA records for this connection to the
1112 * OpenSSL library. If none are "usable", we'll fall back to "encrypt"
1113 * when authentication is not mandatory, otherwise we must arrange to
1114 * ensure authentication failure.
1115 */
1116 if (TLScontext->dane && TLScontext->dane->tlsa) {
1117 int usable = tls_dane_enable(TLScontext);
1118 int must_fail = usable <= 0;
1119
1120 if (usable == 0) {
1121 switch (TLScontext->level) {
1122 case TLS_LEV_HALF_DANE:
1123 case TLS_LEV_DANE:
1124 #ifdef USE_TLSRPT
1125 if (props->tlsrpt) {
1126 trw_report_failure(props->tlsrpt, TLSRPT_TLSA_INVALID,
1127 /* additional_info= */ (char *) 0,
1128 "all-TLSA-records-unusable");
1129 }
1130 #endif
1131 msg_warn("%s: all TLSA records unusable, fallback to "
1132 "unauthenticated TLS", TLScontext->namaddr);
1133 must_fail = 0;
1134 TLScontext->level = TLS_LEV_ENCRYPT;
1135 break;
1136
1137 case TLS_LEV_FPRINT:
1138 #ifdef USE_TLSRPT
1139 if (props->tlsrpt) {
1140 trw_report_failure(props->tlsrpt, TLSRPT_VALIDATION_FAILURE,
1141 /* additional_info= */ (char *) 0,
1142 "all-fingerprints-unusable");
1143 }
1144 #endif
1145 msg_warn("%s: all fingerprints unusable", TLScontext->namaddr);
1146 break;
1147 case TLS_LEV_DANE_ONLY:
1148 #ifdef USE_TLSRPT
1149 if (props->tlsrpt) {
1150 trw_report_failure(props->tlsrpt, TLSRPT_TLSA_INVALID,
1151 /* additional_info= */ (char *) 0,
1152 "all-TLSA-records-unusable");
1153 }
1154 #endif
1155 msg_warn("%s: all TLSA records unusable", TLScontext->namaddr);
1156 break;
1157 case TLS_LEV_SECURE:
1158 case TLS_LEV_VERIFY:
1159 #ifdef USE_TLSRPT
1160 if (props->tlsrpt) {
1161 trw_report_failure(props->tlsrpt, TLSRPT_VALIDATION_FAILURE,
1162 /* additional_info= */ (char *) 0,
1163 "all-trust-anchors-unusable");
1164 }
1165 #endif
1166 msg_warn("%s: all trust anchors unusable", TLScontext->namaddr);
1167 break;
1168 }
1169 }
1170 TLScontext->must_fail |= must_fail;
1171 }
1172
1173 /*
1174 * We compute the policy digest after we compute the SNI name in
1175 * tls_auth_enable() and possibly update the TLScontext security level.
1176 *
1177 * OpenSSL will ignore cached sessions that use the wrong protocol. So we do
1178 * not need to filter out cached sessions with the "wrong" protocol,
1179 * rather OpenSSL will simply negotiate a new session.
1180 *
1181 * We salt the session lookup key with the protocol list, so that sessions
1182 * found in the cache are plausibly acceptable.
1183 *
1184 * By the time a TLS client is negotiating ciphers it has already offered to
1185 * re-use a session, it is too late to renege on the offer. So we must
1186 * not attempt to re-use sessions whose ciphers are too weak. We salt the
1187 * session lookup key with the cipher list, so that sessions found in the
1188 * cache are always acceptable.
1189 *
1190 * With DANE, (more generally any TLScontext where we specified explicit
1191 * trust-anchor or end-entity certificates) the verification status of
1192 * the SSL session depends on the specified list. Since we verify the
1193 * certificate only during the initial handshake, we must segregate
1194 * sessions with different TA lists. Note, that TA re-verification is
1195 * not possible with cached sessions, since these don't hold the complete
1196 * peer trust chain. Therefore, we compute a digest of the sorted TA
1197 * parameters and append it to the serverid.
1198 */
1199 TLScontext->serverid =
1200 tls_serverid_digest(TLScontext, props, cipher_list);
1201
1202 /*
1203 * When authenticating the peer, use 80-bit plus OpenSSL security level
1204 *
1205 * XXX: We should perhaps use security level 1 also for mandatory
1206 * encryption, with only "may" tolerating weaker algorithms. But that
1207 * could mean no TLS 1.0 with OpenSSL >= 3.0 and encrypt, unless I get my
1208 * patch in on time to conditionally re-enable SHA1 at security level 1,
1209 * and we add code to make it so.
1210 *
1211 * That said, with "encrypt", we could reasonably require TLS 1.2?
1212 */
1213 if (TLS_MUST_MATCH(TLScontext->level))
1214 SSL_set_security_level(TLScontext->con, 1);
1215
1216 /*
1217 * XXX To avoid memory leaks we must always call SSL_SESSION_free() after
1218 * calling SSL_set_session(), regardless of whether or not the session
1219 * will be reused.
1220 */
1221 if (TLScontext->cache_type) {
1222 session = load_clnt_session(TLScontext);
1223 if (session) {
1224 SSL_set_session(TLScontext->con, session);
1225 SSL_SESSION_free(session); /* 200411 */
1226 }
1227 }
1228
1229 /*
1230 * Before really starting anything, try to seed the PRNG a little bit
1231 * more.
1232 */
1233 tls_int_seed();
1234 (void) tls_ext_seed(var_tls_daemon_rand_bytes);
1235
1236 /*
1237 * Connect the SSL connection with the network socket.
1238 */
1239 if (SSL_set_fd(TLScontext->con, props->stream == 0 ? props->fd :
1240 vstream_fileno(props->stream)) != 1) {
1241 /* TLSRPT: Local resource error, don't report. */
1242 msg_info("SSL_set_fd error to %s", props->namaddr);
1243 tls_print_errors();
1244 uncache_session(app_ctx->ssl_ctx, TLScontext);
1245 tls_free_context(TLScontext);
1246 return (0);
1247 }
1248
1249 /*
1250 * If the debug level selected is high enough, all of the data is dumped:
1251 * TLS_LOG_TLSPKTS will dump the SSL negotiation, TLS_LOG_ALLPKTS will
1252 * dump everything.
1253 *
1254 * We do have an SSL_set_fd() and now suddenly a BIO_ routine is called?
1255 * Well there is a BIO below the SSL routines that is automatically
1256 * created for us, so we can use it for debugging purposes.
1257 */
1258 if (log_mask & TLS_LOG_TLSPKTS)
1259 tls_set_bio_callback(SSL_get_rbio(TLScontext->con), tls_bio_dump_cb);
1260
1261 /*
1262 * An external (STS) policy signaled a failure. Prevent false (PKI)
1263 * certificate matches in tls_verify.c. TODO(wietse) how was this handled
1264 * historically?
1265 */
1266 if (props->ffail_type) {
1267 TLScontext->ffail_type = mystrdup(props->ffail_type);
1268 TLScontext->must_fail = 1;
1269 }
1270
1271 /*
1272 * If we don't trigger the handshake in the library, leave control over
1273 * SSL_connect/read/write/etc with the application.
1274 */
1275 if (props->stream == 0)
1276 return (TLScontext);
1277
1278 /*
1279 * Turn on non-blocking I/O so that we can enforce timeouts on network
1280 * I/O.
1281 */
1282 non_blocking(vstream_fileno(props->stream), NON_BLOCKING);
1283
1284 /*
1285 * Start TLS negotiations. This process is a black box that invokes our
1286 * call-backs for certificate verification.
1287 *
1288 * Error handling: If the SSL handshake fails, we print out an error message
1289 * and remove all TLS state concerning this session.
1290 */
1291 sts = tls_bio_connect(vstream_fileno(props->stream), props->timeout,
1292 TLScontext);
1293 if (sts <= 0) {
1294 if (ERR_peek_error() != 0) {
1295 msg_info("SSL_connect error to %s: %d", props->namaddr, sts);
1296 tls_print_errors();
1297 } else if (errno != 0) {
1298 msg_info("SSL_connect error to %s: %m", props->namaddr);
1299 } else {
1300 msg_info("SSL_connect error to %s: lost connection",
1301 props->namaddr);
1302 }
1303 #ifdef USE_TLSRPT
1304 if (props->tlsrpt)
1305 trw_report_failure(props->tlsrpt, TLSRPT_VALIDATION_FAILURE,
1306 /* additional_info= */ (char *) 0,
1307 "tls-handshake-failure");
1308 #endif
1309 uncache_session(app_ctx->ssl_ctx, TLScontext);
1310 tls_free_context(TLScontext);
1311 return (0);
1312 }
1313 return (tls_client_post_connect(TLScontext, props));
1314 }
1315
1316 /* tls_client_post_connect - post-handshake processing */
1317
tls_client_post_connect(TLS_SESS_STATE * TLScontext,const TLS_CLIENT_START_PROPS * props)1318 TLS_SESS_STATE *tls_client_post_connect(TLS_SESS_STATE *TLScontext,
1319 const TLS_CLIENT_START_PROPS *props)
1320 {
1321 const SSL_CIPHER *cipher;
1322 X509 *peercert;
1323 EVP_PKEY *peerpkey = 0;
1324
1325 /* Turn off packet dump if only dumping the handshake */
1326 if ((TLScontext->log_mask & TLS_LOG_ALLPKTS) == 0)
1327 tls_set_bio_callback(SSL_get_rbio(TLScontext->con), 0);
1328
1329 /*
1330 * The caller may want to know if this session was reused or if a new
1331 * session was negotiated.
1332 */
1333 TLScontext->session_reused = SSL_session_reused(TLScontext->con);
1334 if ((TLScontext->log_mask & TLS_LOG_CACHE) && TLScontext->session_reused)
1335 msg_info("%s: Reusing old session", TLScontext->namaddr);
1336
1337 /*
1338 * Do peername verification if requested and extract useful information
1339 * from the certificate for later use.
1340 */
1341 peercert = TLS_PEEK_PEER_CERT(TLScontext->con);
1342 if (peercert != 0) {
1343 peerpkey = X509_get0_pubkey(peercert);
1344 }
1345 #if OPENSSL_VERSION_PREREQ(3,2)
1346 else {
1347 peerpkey = SSL_get0_peer_rpk(TLScontext->con);
1348 }
1349 #endif
1350
1351 if (peercert != 0) {
1352 TLScontext->peer_status |= TLS_CRED_FLAG_CERT;
1353
1354 /*
1355 * Peer name or fingerprint verification as requested.
1356 * Unconditionally set peer_CN, issuer_CN and peer_cert_fprint. Check
1357 * fingerprint first, and avoid logging verified as untrusted in the
1358 * call to verify_x509().
1359 */
1360 TLScontext->peer_cert_fprint =
1361 tls_cert_fprint(peercert, props->mdalg);
1362 TLScontext->peer_pkey_fprint =
1363 tls_pkey_fprint(peerpkey, props->mdalg);
1364 verify_x509(TLScontext, peercert, props);
1365
1366 if (TLScontext->log_mask &
1367 (TLS_LOG_CERTMATCH | TLS_LOG_VERBOSE | TLS_LOG_PEERCERT))
1368 msg_info("%s: subject_CN=%s, issuer=%s%s%s%s%s",
1369 TLScontext->namaddr,
1370 TLScontext->peer_CN, TLScontext->issuer_CN,
1371 *TLScontext->peer_cert_fprint ?
1372 ", cert fingerprint=" : "",
1373 *TLScontext->peer_cert_fprint ?
1374 TLScontext->peer_cert_fprint : "",
1375 *TLScontext->peer_pkey_fprint ?
1376 ", pkey fingerprint=" : "",
1377 *TLScontext->peer_pkey_fprint ?
1378 TLScontext->peer_pkey_fprint : "");
1379 } else {
1380 TLScontext->issuer_CN = mystrdup("");
1381 TLScontext->peer_CN = mystrdup("");
1382 TLScontext->peer_cert_fprint = mystrdup("");
1383
1384 if (!peerpkey) {
1385 TLScontext->peer_pkey_fprint = mystrdup("");
1386 } else {
1387 TLScontext->peer_status |= TLS_CRED_FLAG_RPK;
1388 TLScontext->peer_pkey_fprint =
1389 tls_pkey_fprint(peerpkey, props->mdalg);
1390 if (TLScontext->log_mask &
1391 (TLS_LOG_CERTMATCH | TLS_LOG_VERBOSE | TLS_LOG_PEERCERT))
1392 msg_info("%s: raw public key fingerprint=%s", props->namaddr,
1393 TLScontext->peer_pkey_fprint);
1394 verify_rpk(TLScontext, peerpkey, props);
1395 }
1396 }
1397
1398 /*
1399 * Finally, collect information about protocol and cipher for logging
1400 */
1401 TLScontext->protocol = SSL_get_version(TLScontext->con);
1402 cipher = SSL_get_current_cipher(TLScontext->con);
1403 TLScontext->cipher_name = SSL_CIPHER_get_name(cipher);
1404 TLScontext->cipher_usebits = SSL_CIPHER_get_bits(cipher,
1405 &(TLScontext->cipher_algbits));
1406
1407 /*
1408 * The TLS engine is active. Switch to the tls_timed_read/write()
1409 * functions and make the TLScontext available to those functions.
1410 */
1411 if (TLScontext->stream != 0)
1412 tls_stream_start(props->stream, TLScontext);
1413
1414 /*
1415 * With the handshake done, extract TLS 1.3 signature metadata.
1416 */
1417 tls_get_signature_params(TLScontext);
1418
1419 if (TLScontext->log_mask & TLS_LOG_SUMMARY)
1420 tls_log_summary(TLS_ROLE_CLIENT, TLS_USAGE_NEW, TLScontext);
1421
1422 tls_int_seed();
1423
1424 /*
1425 * Precondition: tls_client_start() is called only for a new TCP
1426 * connection. It is never called for a reused TCP connection.
1427 *
1428 * Inform the caller that they should not generate a TLSRPT 'success' or
1429 * 'failure' event: either this TLS protocol engine has already generated
1430 * a TLSRPT 'failure' event for this session, or this is a reused TLS
1431 * session.
1432 */
1433 #ifdef USE_TLSRPT
1434 TLScontext->rpt_reported = props->tlsrpt != 0
1435 && (trw_is_reported(props->tlsrpt)
1436 || (TLScontext->session_reused
1437 && trw_is_skip_reused_hs(props->tlsrpt)));
1438 #endif
1439
1440 return (TLScontext);
1441 }
1442
1443 #endif /* USE_TLS */
1444