Commit | Line | Data |
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58eb016e | 1 | /* $Cambridge: exim/src/src/tls-gnu.c,v 1.19 2007/04/13 15:13:47 ph10 Exp $ */ |
059ec3d9 PH |
2 | |
3 | /************************************************* | |
4 | * Exim - an Internet mail transport agent * | |
5 | *************************************************/ | |
6 | ||
184e8823 | 7 | /* Copyright (c) University of Cambridge 1995 - 2007 */ |
059ec3d9 PH |
8 | /* See the file NOTICE for conditions of use and distribution. */ |
9 | ||
10 | /* This module provides TLS (aka SSL) support for Exim using the GnuTLS | |
11 | library. It is #included into tls.c when that library is used. The code herein | |
12 | is based on a patch that was contributed by Nikos Mavroyanopoulos. | |
13 | ||
14 | No cryptographic code is included in Exim. All this module does is to call | |
15 | functions from the GnuTLS library. */ | |
16 | ||
17 | ||
18 | /* Heading stuff for GnuTLS */ | |
19 | ||
20 | #include <gnutls/gnutls.h> | |
21 | #include <gnutls/x509.h> | |
22 | ||
23 | ||
24 | #define UNKNOWN_NAME "unknown" | |
87054a31 | 25 | #define DH_BITS 1024 |
b5aea5e1 PH |
26 | #define PARAM_SIZE 2*1024 |
27 | ||
059ec3d9 PH |
28 | |
29 | /* Values for verify_requirment and initialized */ | |
30 | ||
31 | enum { VERIFY_NONE, VERIFY_OPTIONAL, VERIFY_REQUIRED }; | |
32 | enum { INITIALIZED_NOT, INITIALIZED_SERVER, INITIALIZED_CLIENT }; | |
33 | ||
34 | /* Local static variables for GNUTLS */ | |
35 | ||
36 | static BOOL initialized = INITIALIZED_NOT; | |
37 | static host_item *client_host; | |
38 | ||
059ec3d9 PH |
39 | static gnutls_dh_params dh_params = NULL; |
40 | ||
41 | static gnutls_certificate_server_credentials x509_cred = NULL; | |
42 | static gnutls_session tls_session = NULL; | |
43 | ||
44 | static char ssl_errstring[256]; | |
45 | ||
46 | static int ssl_session_timeout = 200; | |
47 | static int verify_requirement; | |
48 | ||
83da1223 PH |
49 | /* Priorities for TLS algorithms to use. In each case there's a default table, |
50 | and space into which it can be copied and altered. */ | |
059ec3d9 | 51 | |
83da1223 PH |
52 | static const int default_proto_priority[16] = { |
53 | GNUTLS_TLS1, | |
54 | GNUTLS_SSL3, | |
55 | 0 }; | |
56 | ||
57 | static int proto_priority[16]; | |
059ec3d9 | 58 | |
83da1223 | 59 | static const int default_kx_priority[16] = { |
059ec3d9 PH |
60 | GNUTLS_KX_RSA, |
61 | GNUTLS_KX_DHE_DSS, | |
62 | GNUTLS_KX_DHE_RSA, | |
059ec3d9 PH |
63 | 0 }; |
64 | ||
83da1223 PH |
65 | static int kx_priority[16]; |
66 | ||
059ec3d9 | 67 | static int default_cipher_priority[16] = { |
26dd5a95 | 68 | GNUTLS_CIPHER_AES_256_CBC, |
059ec3d9 PH |
69 | GNUTLS_CIPHER_AES_128_CBC, |
70 | GNUTLS_CIPHER_3DES_CBC, | |
26dd5a95 | 71 | GNUTLS_CIPHER_ARCFOUR_128, |
059ec3d9 PH |
72 | 0 }; |
73 | ||
74 | static int cipher_priority[16]; | |
75 | ||
83da1223 | 76 | static const int default_mac_priority[16] = { |
059ec3d9 PH |
77 | GNUTLS_MAC_SHA, |
78 | GNUTLS_MAC_MD5, | |
79 | 0 }; | |
80 | ||
83da1223 PH |
81 | static int mac_priority[16]; |
82 | ||
83 | /* These two are currently not changeable. */ | |
84 | ||
059ec3d9 PH |
85 | static const int comp_priority[16] = { GNUTLS_COMP_NULL, 0 }; |
86 | static const int cert_type_priority[16] = { GNUTLS_CRT_X509, 0 }; | |
87 | ||
83da1223 | 88 | /* Tables of priority names and equivalent numbers */ |
059ec3d9 PH |
89 | |
90 | typedef struct pri_item { | |
91 | uschar *name; | |
92 | int *values; | |
93 | } pri_item; | |
94 | ||
83da1223 PH |
95 | |
96 | static int tls1_codes[] = { GNUTLS_TLS1, 0 }; | |
97 | static int ssl3_codes[] = { GNUTLS_SSL3, 0 }; | |
98 | ||
99 | static pri_item proto_index[] = { | |
100 | { US"TLS1", tls1_codes }, | |
101 | { US"SSL3", ssl3_codes } | |
102 | }; | |
103 | ||
104 | ||
105 | static int kx_rsa_codes[] = { GNUTLS_KX_RSA, | |
106 | GNUTLS_KX_DHE_RSA, 0 }; | |
107 | static int kx_dhe_codes[] = { GNUTLS_KX_DHE_DSS, | |
108 | GNUTLS_KX_DHE_RSA, 0 }; | |
109 | static int kx_dhe_dss_codes[] = { GNUTLS_KX_DHE_DSS, 0 }; | |
110 | static int kx_dhe_rsa_codes[] = { GNUTLS_KX_DHE_RSA, 0 }; | |
111 | ||
112 | static pri_item kx_index[] = { | |
113 | { US"DHE_DSS", kx_dhe_dss_codes }, | |
114 | { US"DHE_RSA", kx_dhe_rsa_codes }, | |
115 | { US"RSA", kx_rsa_codes }, | |
116 | { US"DHE", kx_dhe_codes } | |
117 | }; | |
118 | ||
119 | ||
059ec3d9 PH |
120 | static int arcfour_128_codes[] = { GNUTLS_CIPHER_ARCFOUR_128, 0 }; |
121 | static int arcfour_40_codes[] = { GNUTLS_CIPHER_ARCFOUR_40, 0 }; | |
122 | static int arcfour_codes[] = { GNUTLS_CIPHER_ARCFOUR_128, | |
123 | GNUTLS_CIPHER_ARCFOUR_40, 0 }; | |
124 | static int aes_256_codes[] = { GNUTLS_CIPHER_AES_256_CBC, 0 }; | |
125 | static int aes_128_codes[] = { GNUTLS_CIPHER_AES_128_CBC, 0 }; | |
126 | static int aes_codes[] = { GNUTLS_CIPHER_AES_256_CBC, | |
127 | GNUTLS_CIPHER_AES_128_CBC, 0 }; | |
128 | static int des3_codes[] = { GNUTLS_CIPHER_3DES_CBC, 0 }; | |
129 | ||
130 | static pri_item cipher_index[] = { | |
131 | { US"ARCFOUR_128", arcfour_128_codes }, | |
132 | { US"ARCFOUR_40", arcfour_40_codes }, | |
133 | { US"ARCFOUR", arcfour_codes }, | |
134 | { US"AES_256", aes_256_codes }, | |
135 | { US"AES_128", aes_128_codes }, | |
136 | { US"AES", aes_codes }, | |
137 | { US"3DES", des3_codes } | |
138 | }; | |
139 | ||
140 | ||
83da1223 PH |
141 | static int mac_sha_codes[] = { GNUTLS_MAC_SHA, 0 }; |
142 | static int mac_md5_codes[] = { GNUTLS_MAC_MD5, 0 }; | |
143 | ||
144 | static pri_item mac_index[] = { | |
145 | { US"SHA", mac_sha_codes }, | |
146 | { US"SHA1", mac_sha_codes }, | |
147 | { US"MD5", mac_md5_codes } | |
148 | }; | |
149 | ||
150 | ||
059ec3d9 PH |
151 | |
152 | /************************************************* | |
153 | * Handle TLS error * | |
154 | *************************************************/ | |
155 | ||
156 | /* Called from lots of places when errors occur before actually starting to do | |
157 | the TLS handshake, that is, while the session is still in clear. Always returns | |
158 | DEFER for a server and FAIL for a client so that most calls can use "return | |
159 | tls_error(...)" to do this processing and then give an appropriate return. A | |
160 | single function is used for both server and client, because it is called from | |
161 | some shared functions. | |
162 | ||
163 | Argument: | |
164 | prefix text to include in the logged error | |
165 | host NULL if setting up a server; | |
166 | the connected host if setting up a client | |
167 | err a GnuTLS error number, or 0 if local error | |
168 | ||
169 | Returns: OK/DEFER/FAIL | |
170 | */ | |
171 | ||
172 | static int | |
173 | tls_error(uschar *prefix, host_item *host, int err) | |
174 | { | |
175 | uschar *errtext = US""; | |
176 | if (err != 0) errtext = string_sprintf(": %s", gnutls_strerror(err)); | |
177 | if (host == NULL) | |
178 | { | |
179 | log_write(0, LOG_MAIN, "TLS error on connection from %s (%s)%s", | |
180 | (sender_fullhost != NULL)? sender_fullhost : US "local process", | |
181 | prefix, errtext); | |
182 | return DEFER; | |
183 | } | |
184 | else | |
185 | { | |
186 | log_write(0, LOG_MAIN, "TLS error on connection to %s [%s] (%s)%s", | |
187 | host->name, host->address, prefix, errtext); | |
188 | return FAIL; | |
189 | } | |
190 | } | |
191 | ||
192 | ||
193 | ||
194 | /************************************************* | |
195 | * Verify certificate * | |
196 | *************************************************/ | |
197 | ||
198 | /* Called after a successful handshake, when certificate verification is | |
199 | required or optional, for both server and client. | |
200 | ||
201 | Arguments: | |
202 | session GNUTLS session | |
203 | error where to put text giving a reason for failure | |
204 | ||
205 | Returns: TRUE/FALSE | |
206 | */ | |
207 | ||
208 | static BOOL | |
209 | verify_certificate(gnutls_session session, uschar **error) | |
210 | { | |
211 | int verify; | |
212 | uschar *dn_string = US""; | |
213 | const gnutls_datum *cert; | |
214 | unsigned int cert_size = 0; | |
215 | ||
216 | *error = NULL; | |
217 | ||
218 | /* Get the peer's certificate. If it sent one, extract it's DN, and then | |
219 | attempt to verify the certificate. If no certificate is supplied, verification | |
220 | is forced to fail. */ | |
221 | ||
222 | cert = gnutls_certificate_get_peers(session, &cert_size); | |
223 | if (cert != NULL) | |
224 | { | |
225 | uschar buff[1024]; | |
226 | gnutls_x509_crt gcert; | |
227 | ||
228 | gnutls_x509_crt_init(&gcert); | |
229 | dn_string = US"unknown"; | |
230 | ||
231 | if (gnutls_x509_crt_import(gcert, cert, GNUTLS_X509_FMT_DER) == 0) | |
232 | { | |
233 | size_t bufsize = sizeof(buff); | |
234 | if (gnutls_x509_crt_get_dn(gcert, CS buff, &bufsize) >= 0) | |
235 | dn_string = string_copy_malloc(buff); | |
236 | } | |
237 | ||
238 | verify = gnutls_certificate_verify_peers(session); | |
239 | } | |
240 | else | |
241 | { | |
242 | DEBUG(D_tls) debug_printf("no peer certificate supplied\n"); | |
243 | verify = GNUTLS_CERT_INVALID; | |
244 | *error = US"not supplied"; | |
245 | } | |
246 | ||
247 | /* Handle the result of verification. INVALID seems to be set as well | |
248 | as REVOKED, but leave the test for both. */ | |
249 | ||
250 | if ((verify & (GNUTLS_CERT_INVALID|GNUTLS_CERT_REVOKED)) != 0) | |
251 | { | |
252 | tls_certificate_verified = FALSE; | |
253 | if (*error == NULL) *error = ((verify & GNUTLS_CERT_REVOKED) != 0)? | |
254 | US"revoked" : US"invalid"; | |
255 | if (verify_requirement == VERIFY_REQUIRED) | |
256 | { | |
257 | DEBUG(D_tls) debug_printf("TLS certificate verification failed (%s): " | |
258 | "peerdn=%s\n", *error, dn_string); | |
259 | gnutls_alert_send(session, GNUTLS_AL_FATAL, GNUTLS_A_BAD_CERTIFICATE); | |
260 | return FALSE; /* reject */ | |
261 | } | |
262 | DEBUG(D_tls) debug_printf("TLS certificate verify failure (%s) overridden " | |
263 | "(host in tls_try_verify_hosts): peerdn=%s\n", *error, dn_string); | |
264 | } | |
265 | else | |
266 | { | |
267 | tls_certificate_verified = TRUE; | |
268 | DEBUG(D_tls) debug_printf("TLS certificate verified: peerdn=%s\n", | |
269 | dn_string); | |
270 | } | |
271 | ||
272 | tls_peerdn = dn_string; | |
273 | return TRUE; /* accept */ | |
274 | } | |
275 | ||
276 | ||
277 | ||
059ec3d9 | 278 | /************************************************* |
575643cd | 279 | * Setup up DH parameters * |
059ec3d9 PH |
280 | *************************************************/ |
281 | ||
575643cd | 282 | /* Generating the D-H parameters may take a long time. They only need to |
059ec3d9 PH |
283 | be re-generated every so often, depending on security policy. What we do is to |
284 | keep these parameters in a file in the spool directory. If the file does not | |
285 | exist, we generate them. This means that it is easy to cause a regeneration. | |
286 | ||
287 | The new file is written as a temporary file and renamed, so that an incomplete | |
288 | file is never present. If two processes both compute some new parameters, you | |
289 | waste a bit of effort, but it doesn't seem worth messing around with locking to | |
290 | prevent this. | |
291 | ||
292 | Argument: | |
293 | host NULL for server, server for client (for error handling) | |
294 | ||
295 | Returns: OK/DEFER/FAIL | |
296 | */ | |
297 | ||
298 | static int | |
575643cd | 299 | init_dh(host_item *host) |
059ec3d9 | 300 | { |
b5aea5e1 | 301 | int fd; |
182ad5cf | 302 | int ret; |
b5aea5e1 | 303 | gnutls_datum m; |
059ec3d9 PH |
304 | uschar filename[200]; |
305 | ||
306 | /* Initialize the data structures for holding the parameters */ | |
307 | ||
059ec3d9 PH |
308 | ret = gnutls_dh_params_init(&dh_params); |
309 | if (ret < 0) return tls_error(US"init dh_params", host, ret); | |
310 | ||
311 | /* Set up the name of the cache file */ | |
312 | ||
313 | if (!string_format(filename, sizeof(filename), "%s/gnutls-params", | |
314 | spool_directory)) | |
315 | return tls_error(US"overlong filename", host, 0); | |
316 | ||
b5aea5e1 | 317 | /* Open the cache file for reading and if successful, read it and set up the |
575643cd | 318 | parameters. */ |
059ec3d9 PH |
319 | |
320 | fd = Uopen(filename, O_RDONLY, 0); | |
b5aea5e1 | 321 | if (fd >= 0) |
059ec3d9 | 322 | { |
b5aea5e1 PH |
323 | struct stat statbuf; |
324 | if (fstat(fd, &statbuf) < 0) | |
325 | { | |
326 | (void)close(fd); | |
327 | return tls_error(US"TLS cache stat failed", host, 0); | |
328 | } | |
059ec3d9 | 329 | |
b5aea5e1 PH |
330 | m.size = statbuf.st_size; |
331 | m.data = malloc(m.size); | |
332 | if (m.data == NULL) | |
333 | return tls_error(US"memory allocation failed", host, 0); | |
334 | if (read(fd, m.data, m.size) != m.size) | |
335 | return tls_error(US"TLS cache read failed", host, 0); | |
336 | (void)close(fd); | |
337 | ||
411ef850 PH |
338 | ret = gnutls_dh_params_import_pkcs3(dh_params, &m, GNUTLS_X509_FMT_PEM); |
339 | if (ret < 0) return tls_error(US"DH params import", host, ret); | |
575643cd | 340 | DEBUG(D_tls) debug_printf("read D-H parameters from file\n"); |
b5aea5e1 PH |
341 | |
342 | free(m.data); | |
343 | } | |
344 | ||
345 | /* If the file does not exist, fall through to compute new data and cache it. | |
346 | If there was any other opening error, it is serious. */ | |
347 | ||
182ad5cf PH |
348 | else if (errno == ENOENT) |
349 | { | |
350 | ret = -1; | |
351 | DEBUG(D_tls) | |
352 | debug_printf("parameter cache file %s does not exist\n", filename); | |
353 | } | |
354 | else | |
b5aea5e1 PH |
355 | return tls_error(string_open_failed(errno, "%s for reading", filename), |
356 | host, 0); | |
357 | ||
358 | /* If ret < 0, either the cache file does not exist, or the data it contains | |
359 | is not useful. One particular case of this is when upgrading from an older | |
360 | release of Exim in which the data was stored in a different format. We don't | |
361 | try to be clever and support both formats; we just regenerate new data in this | |
362 | case. */ | |
363 | ||
364 | if (ret < 0) | |
365 | { | |
366 | uschar tempfilename[sizeof(filename) + 10]; | |
059ec3d9 | 367 | |
059ec3d9 PH |
368 | DEBUG(D_tls) debug_printf("generating %d bit Diffie-Hellman key...\n", |
369 | DH_BITS); | |
370 | ret = gnutls_dh_params_generate2(dh_params, DH_BITS); | |
371 | if (ret < 0) return tls_error(US"D-H key generation", host, ret); | |
372 | ||
373 | /* Write the parameters to a file in the spool directory so that we | |
374 | can use them from other Exim processes. */ | |
375 | ||
376 | sprintf(CS tempfilename, "%s-%d", filename, (int)getpid()); | |
377 | fd = Uopen(tempfilename, O_WRONLY|O_CREAT, 0400); | |
378 | if (fd < 0) | |
379 | return tls_error(string_open_failed(errno, "%s for writing", filename), | |
380 | host, 0); | |
381 | (void)fchown(fd, exim_uid, exim_gid); /* Probably not necessary */ | |
382 | ||
b5aea5e1 PH |
383 | /* export the parameters in a format that can be generated using GNUTLS' |
384 | * certtool or other programs. | |
385 | * | |
386 | * The commands for certtool are: | |
411ef850 | 387 | * $ certtool --generate-dh-params --bits 1024 > params |
b5aea5e1 PH |
388 | */ |
389 | ||
390 | m.size = PARAM_SIZE; | |
391 | m.data = malloc(m.size); | |
392 | if (m.data == NULL) | |
393 | return tls_error(US"memory allocation failed", host, 0); | |
394 | ||
b5aea5e1 PH |
395 | m.size = PARAM_SIZE; |
396 | ret = gnutls_dh_params_export_pkcs3(dh_params, GNUTLS_X509_FMT_PEM, m.data, | |
397 | &m.size); | |
059ec3d9 PH |
398 | if (ret < 0) return tls_error(US"DH params export", host, ret); |
399 | ||
b5aea5e1 PH |
400 | m.size = Ustrlen(m.data); |
401 | if (write(fd, m.data, m.size) != m.size || write(fd, "\n", 1) != 1) | |
059ec3d9 PH |
402 | return tls_error(US"TLS cache write failed", host, 0); |
403 | ||
b5aea5e1 | 404 | free(m.data); |
059ec3d9 PH |
405 | (void)close(fd); |
406 | ||
407 | if (rename(CS tempfilename, CS filename) < 0) | |
408 | return tls_error(string_sprintf("failed to rename %s as %s: %s", | |
409 | tempfilename, filename, strerror(errno)), host, 0); | |
410 | ||
411ef850 | 411 | DEBUG(D_tls) debug_printf("wrote D-H parameters to file %s\n", filename); |
059ec3d9 PH |
412 | } |
413 | ||
411ef850 | 414 | DEBUG(D_tls) debug_printf("initialized D-H parameters\n"); |
059ec3d9 PH |
415 | return OK; |
416 | } | |
417 | ||
418 | ||
419 | ||
420 | ||
421 | /************************************************* | |
422 | * Initialize for GnuTLS * | |
423 | *************************************************/ | |
424 | ||
425 | /* Called from both server and client code. In the case of a server, errors | |
426 | before actual TLS negotiation return DEFER. | |
427 | ||
428 | Arguments: | |
429 | host connected host, if client; NULL if server | |
430 | certificate certificate file | |
431 | privatekey private key file | |
432 | cas CA certs file | |
433 | crl CRL file | |
434 | ||
435 | Returns: OK/DEFER/FAIL | |
436 | */ | |
437 | ||
438 | static int | |
439 | tls_init(host_item *host, uschar *certificate, uschar *privatekey, uschar *cas, | |
440 | uschar *crl) | |
441 | { | |
442 | int rc; | |
443 | uschar *cert_expanded, *key_expanded, *cas_expanded, *crl_expanded; | |
444 | ||
445 | initialized = (host == NULL)? INITIALIZED_SERVER : INITIALIZED_CLIENT; | |
446 | ||
447 | rc = gnutls_global_init(); | |
448 | if (rc < 0) return tls_error(US"tls-init", host, rc); | |
449 | ||
575643cd PH |
450 | /* Create D-H parameters, or read them from the cache file. This function does |
451 | its own SMTP error messaging. */ | |
059ec3d9 | 452 | |
575643cd | 453 | rc = init_dh(host); |
059ec3d9 PH |
454 | if (rc != OK) return rc; |
455 | ||
456 | /* Create the credentials structure */ | |
457 | ||
458 | rc = gnutls_certificate_allocate_credentials(&x509_cred); | |
459 | if (rc < 0) return tls_error(US"certificate_allocate_credentials", host, rc); | |
460 | ||
461 | /* This stuff must be done for each session, because different certificates | |
462 | may be required for different sessions. */ | |
463 | ||
464 | if (!expand_check(certificate, US"tls_certificate", &cert_expanded)) | |
465 | return DEFER; | |
466 | ||
c91535f3 | 467 | key_expanded = NULL; |
059ec3d9 PH |
468 | if (privatekey != NULL) |
469 | { | |
470 | if (!expand_check(privatekey, US"tls_privatekey", &key_expanded)) | |
471 | return DEFER; | |
472 | } | |
c91535f3 PH |
473 | |
474 | /* If expansion was forced to fail, key_expanded will be NULL. If the result of | |
475 | the expansion is an empty string, ignore it also, and assume that the private | |
476 | key is in the same file as the certificate. */ | |
477 | ||
478 | if (key_expanded == NULL || *key_expanded == 0) | |
479 | key_expanded = cert_expanded; | |
059ec3d9 PH |
480 | |
481 | /* Set the certificate and private keys */ | |
482 | ||
483 | if (cert_expanded != NULL) | |
484 | { | |
485 | DEBUG(D_tls) debug_printf("certificate file = %s\nkey file = %s\n", | |
486 | cert_expanded, key_expanded); | |
487 | rc = gnutls_certificate_set_x509_key_file(x509_cred, CS cert_expanded, | |
488 | CS key_expanded, GNUTLS_X509_FMT_PEM); | |
8e669ac1 | 489 | if (rc < 0) |
de365ded PH |
490 | { |
491 | uschar *msg = string_sprintf("cert/key setup: cert=%s key=%s", | |
8e669ac1 | 492 | cert_expanded, key_expanded); |
de365ded | 493 | return tls_error(msg, host, rc); |
8e669ac1 | 494 | } |
059ec3d9 PH |
495 | } |
496 | ||
497 | /* A certificate is mandatory in a server, but not in a client */ | |
498 | ||
499 | else | |
500 | { | |
501 | if (host == NULL) | |
502 | return tls_error(US"no TLS server certificate is specified", host, 0); | |
503 | DEBUG(D_tls) debug_printf("no TLS client certificate is specified\n"); | |
504 | } | |
505 | ||
506 | /* Set the trusted CAs file if one is provided, and then add the CRL if one is | |
507 | provided. Experiment shows that, if the certificate file is empty, an unhelpful | |
508 | error message is provided. However, if we just refrain from setting anything up | |
509 | in that case, certificate verification fails, which seems to be the correct | |
510 | behaviour. */ | |
511 | ||
512 | if (cas != NULL) | |
513 | { | |
514 | struct stat statbuf; | |
515 | ||
516 | if (!expand_check(cas, US"tls_verify_certificates", &cas_expanded)) | |
517 | return DEFER; | |
518 | ||
519 | if (stat(CS cas_expanded, &statbuf) < 0) | |
520 | { | |
521 | log_write(0, LOG_MAIN|LOG_PANIC, "could not stat %s " | |
522 | "(tls_verify_certificates): %s", cas_expanded, strerror(errno)); | |
523 | return DEFER; | |
524 | } | |
525 | ||
b1c749bb PH |
526 | DEBUG(D_tls) debug_printf("verify certificates = %s size=" OFF_T_FMT "\n", |
527 | cas_expanded, statbuf.st_size); | |
059ec3d9 PH |
528 | |
529 | /* If the cert file is empty, there's no point in loading the CRL file. */ | |
530 | ||
531 | if (statbuf.st_size > 0) | |
532 | { | |
533 | rc = gnutls_certificate_set_x509_trust_file(x509_cred, CS cas_expanded, | |
534 | GNUTLS_X509_FMT_PEM); | |
535 | if (rc < 0) return tls_error(US"setup_certs", host, rc); | |
536 | ||
537 | if (crl != NULL && *crl != 0) | |
538 | { | |
539 | if (!expand_check(crl, US"tls_crl", &crl_expanded)) | |
540 | return DEFER; | |
541 | DEBUG(D_tls) debug_printf("loading CRL file = %s\n", crl_expanded); | |
542 | rc = gnutls_certificate_set_x509_crl_file(x509_cred, CS crl_expanded, | |
543 | GNUTLS_X509_FMT_PEM); | |
544 | if (rc < 0) return tls_error(US"CRL setup", host, rc); | |
545 | } | |
546 | } | |
547 | } | |
548 | ||
549 | /* Associate the parameters with the x509 credentials structure. */ | |
550 | ||
551 | gnutls_certificate_set_dh_params(x509_cred, dh_params); | |
059ec3d9 PH |
552 | |
553 | DEBUG(D_tls) debug_printf("initialized certificate stuff\n"); | |
554 | return OK; | |
555 | } | |
556 | ||
557 | ||
558 | ||
559 | ||
560 | /************************************************* | |
83da1223 | 561 | * Remove from a priority list * |
059ec3d9 PH |
562 | *************************************************/ |
563 | ||
564 | /* Cautiously written so that it will remove duplicates if present. | |
565 | ||
566 | Arguments: | |
567 | list a zero-terminated list | |
568 | remove_list a zero-terminated list to be removed | |
569 | ||
570 | Returns: nothing | |
571 | */ | |
572 | ||
573 | static void | |
83da1223 | 574 | remove_priority(int *list, int *remove_list) |
059ec3d9 PH |
575 | { |
576 | for (; *remove_list != 0; remove_list++) | |
577 | { | |
578 | int *p = list; | |
579 | while (*p != 0) | |
580 | { | |
581 | if (*p == *remove_list) | |
582 | { | |
583 | int *pp = p; | |
584 | do { pp[0] = pp[1]; pp++; } while (*pp != 0); | |
585 | } | |
586 | else p++; | |
587 | } | |
588 | } | |
589 | } | |
590 | ||
591 | ||
592 | ||
593 | /************************************************* | |
83da1223 | 594 | * Add to a priority list * |
059ec3d9 PH |
595 | *************************************************/ |
596 | ||
597 | /* Cautiously written to check the list size | |
598 | ||
599 | Arguments: | |
600 | list a zero-terminated list | |
601 | list_max maximum offset in the list | |
602 | add_list a zero-terminated list to be added | |
603 | ||
604 | Returns: TRUE if OK; FALSE if list overflows | |
605 | */ | |
606 | ||
607 | static BOOL | |
83da1223 | 608 | add_priority(int *list, int list_max, int *add_list) |
059ec3d9 PH |
609 | { |
610 | int next = 0; | |
611 | while (list[next] != 0) next++; | |
612 | while (*add_list != 0) | |
613 | { | |
614 | if (next >= list_max) return FALSE; | |
615 | list[next++] = *add_list++; | |
616 | } | |
617 | list[next] = 0; | |
618 | return TRUE; | |
619 | } | |
620 | ||
621 | ||
622 | ||
83da1223 PH |
623 | /************************************************* |
624 | * Adjust a priority list * | |
625 | *************************************************/ | |
626 | ||
627 | /* This function is called to adjust the lists of cipher algorithms, MAC | |
628 | algorithms, key-exchange methods, and protocols. | |
629 | ||
630 | Arguments: | |
631 | plist the appropriate priority list | |
632 | psize the length of the list | |
633 | s the configuation string | |
634 | index the index of recognized strings | |
635 | isize the length of the index | |
636 | ||
637 | ||
638 | which text for an error message | |
639 | ||
640 | Returns: FALSE if the table overflows, else TRUE | |
641 | */ | |
642 | ||
643 | static BOOL | |
644 | set_priority(int *plist, int psize, uschar *s, pri_item *index, int isize, | |
645 | uschar *which) | |
646 | { | |
647 | int sep = 0; | |
648 | BOOL first = TRUE; | |
649 | uschar *t; | |
650 | ||
651 | while ((t = string_nextinlist(&s, &sep, big_buffer, big_buffer_size)) != NULL) | |
652 | { | |
653 | int i; | |
654 | BOOL exclude = t[0] == '!'; | |
655 | if (first && !exclude) plist[0] = 0; | |
656 | first = FALSE; | |
657 | for (i = 0; i < isize; i++) | |
658 | { | |
659 | uschar *ss = strstric(t, index[i].name, FALSE); | |
660 | if (ss != NULL) | |
661 | { | |
662 | uschar *endss = ss + Ustrlen(index[i].name); | |
663 | if ((ss == t || !isalnum(ss[-1])) && !isalnum(*endss)) | |
664 | { | |
665 | if (exclude) | |
666 | remove_priority(plist, index[i].values); | |
667 | else | |
668 | { | |
669 | if (!add_priority(plist, psize, index[i].values)) | |
670 | { | |
671 | log_write(0, LOG_MAIN|LOG_PANIC, "GnuTLS init failed: %s " | |
672 | "priority table overflow", which); | |
673 | return FALSE; | |
674 | } | |
675 | } | |
676 | } | |
677 | } | |
678 | } | |
679 | } | |
680 | ||
681 | DEBUG(D_tls) | |
682 | { | |
683 | int *ptr = plist; | |
684 | debug_printf("adjusted %s priorities:", which); | |
685 | while (*ptr != 0) debug_printf(" %d", *ptr++); | |
686 | debug_printf("\n"); | |
687 | } | |
688 | ||
689 | return TRUE; | |
690 | } | |
691 | ||
692 | ||
693 | ||
694 | ||
059ec3d9 PH |
695 | /************************************************* |
696 | * Initialize a single GNUTLS session * | |
697 | *************************************************/ | |
698 | ||
699 | /* Set the algorithm, the db backend, whether to request certificates etc. | |
700 | ||
701 | TLS in Exim was first implemented using OpenSSL. This has a function to which | |
702 | you pass a list of cipher suites that are permitted/not permitted. GnuTLS works | |
703 | differently. It operates using priority lists for the different components of | |
704 | cipher suites. | |
705 | ||
706 | For compatibility of configuration, we scan a list of cipher suites and set | |
707 | priorities therefrom. However, at the moment, we pay attention only to the bulk | |
708 | cipher. | |
709 | ||
710 | Arguments: | |
711 | side one of GNUTLS_SERVER, GNUTLS_CLIENT | |
83da1223 PH |
712 | expciphers expanded ciphers list or NULL |
713 | expmac expanded MAC list or NULL | |
714 | expkx expanded key-exchange list or NULL | |
715 | expproto expanded protocol list or NULL | |
059ec3d9 PH |
716 | |
717 | Returns: a gnutls_session, or NULL if there is a problem | |
718 | */ | |
719 | ||
720 | static gnutls_session | |
83da1223 PH |
721 | tls_session_init(int side, uschar *expciphers, uschar *expmac, uschar *expkx, |
722 | uschar *expproto) | |
059ec3d9 PH |
723 | { |
724 | gnutls_session session; | |
725 | ||
726 | gnutls_init(&session, side); | |
727 | ||
83da1223 PH |
728 | /* Initialize the lists of permitted protocols, key-exchange methods, ciphers, |
729 | and MACs. */ | |
059ec3d9 PH |
730 | |
731 | memcpy(cipher_priority, default_cipher_priority, sizeof(cipher_priority)); | |
83da1223 PH |
732 | memcpy(mac_priority, default_mac_priority, sizeof(mac_priority)); |
733 | memcpy(kx_priority, default_kx_priority, sizeof(kx_priority)); | |
734 | memcpy(proto_priority, default_proto_priority, sizeof(proto_priority)); | |
735 | ||
736 | /* The names OpenSSL uses in tls_require_ciphers are of the form DES-CBC3-SHA, | |
737 | using hyphen separators. GnuTLS uses underscore separators. So that I can use | |
738 | either form for tls_require_ciphers in my tests, and also for general | |
739 | convenience, we turn hyphens into underscores before scanning the list. */ | |
059ec3d9 PH |
740 | |
741 | if (expciphers != NULL) | |
742 | { | |
059ec3d9 PH |
743 | uschar *s = expciphers; |
744 | while (*s != 0) { if (*s == '-') *s = '_'; s++; } | |
83da1223 | 745 | } |
059ec3d9 | 746 | |
83da1223 PH |
747 | if ((expciphers != NULL && |
748 | !set_priority(cipher_priority, sizeof(cipher_priority)/sizeof(int), | |
749 | expciphers, cipher_index, sizeof(cipher_index)/sizeof(pri_item), | |
750 | US"cipher")) || | |
751 | (expmac != NULL && | |
752 | !set_priority(mac_priority, sizeof(mac_priority)/sizeof(int), | |
753 | expmac, mac_index, sizeof(mac_index)/sizeof(pri_item), | |
754 | US"MAC")) || | |
755 | (expkx != NULL && | |
756 | !set_priority(kx_priority, sizeof(kx_priority)/sizeof(int), | |
757 | expkx, kx_index, sizeof(kx_index)/sizeof(pri_item), | |
758 | US"key-exchange")) || | |
759 | (expproto != NULL && | |
760 | !set_priority(proto_priority, sizeof(proto_priority)/sizeof(int), | |
761 | expproto, proto_index, sizeof(proto_index)/sizeof(pri_item), | |
762 | US"protocol"))) | |
763 | { | |
764 | gnutls_deinit(session); | |
765 | return NULL; | |
059ec3d9 PH |
766 | } |
767 | ||
768 | /* Define the various priorities */ | |
769 | ||
770 | gnutls_cipher_set_priority(session, cipher_priority); | |
771 | gnutls_compression_set_priority(session, comp_priority); | |
772 | gnutls_kx_set_priority(session, kx_priority); | |
83da1223 | 773 | gnutls_protocol_set_priority(session, proto_priority); |
059ec3d9 PH |
774 | gnutls_mac_set_priority(session, mac_priority); |
775 | ||
776 | gnutls_cred_set(session, GNUTLS_CRD_CERTIFICATE, x509_cred); | |
777 | ||
778 | gnutls_dh_set_prime_bits(session, DH_BITS); | |
779 | ||
780 | /* Request or demand a certificate of the peer, as configured. This will | |
781 | happen only in a server. */ | |
782 | ||
783 | if (verify_requirement != VERIFY_NONE) | |
784 | gnutls_certificate_server_set_request(session, | |
785 | (verify_requirement == VERIFY_OPTIONAL)? | |
786 | GNUTLS_CERT_REQUEST : GNUTLS_CERT_REQUIRE); | |
787 | ||
788 | gnutls_db_set_cache_expiration(session, ssl_session_timeout); | |
789 | ||
790 | DEBUG(D_tls) debug_printf("initialized GnuTLS session\n"); | |
791 | return session; | |
792 | } | |
793 | ||
794 | ||
795 | ||
796 | /************************************************* | |
797 | * Get name of cipher in use * | |
798 | *************************************************/ | |
799 | ||
800 | /* The answer is left in a static buffer, and tls_cipher is set to point | |
801 | to it. | |
802 | ||
803 | Argument: pointer to a GnuTLS session | |
804 | Returns: nothing | |
805 | */ | |
806 | ||
807 | static void | |
808 | construct_cipher_name(gnutls_session session) | |
809 | { | |
810 | static uschar cipherbuf[256]; | |
811 | uschar *ver; | |
812 | int bits, c, kx, mac; | |
813 | ||
814 | ver = string_copy( | |
815 | US gnutls_protocol_get_name(gnutls_protocol_get_version(session))); | |
816 | if (Ustrncmp(ver, "TLS ", 4) == 0) ver[3] = '-'; /* Don't want space */ | |
817 | ||
818 | c = gnutls_cipher_get(session); | |
819 | bits = gnutls_cipher_get_key_size(c); | |
820 | ||
821 | mac = gnutls_mac_get(session); | |
822 | kx = gnutls_kx_get(session); | |
823 | ||
824 | string_format(cipherbuf, sizeof(cipherbuf), "%s:%s:%u", ver, | |
825 | gnutls_cipher_suite_get_name(kx, c, mac), bits); | |
826 | tls_cipher = cipherbuf; | |
827 | ||
828 | DEBUG(D_tls) debug_printf("cipher: %s\n", cipherbuf); | |
829 | } | |
830 | ||
831 | ||
832 | ||
833 | /************************************************* | |
834 | * Start a TLS session in a server * | |
835 | *************************************************/ | |
836 | ||
837 | /* This is called when Exim is running as a server, after having received | |
838 | the STARTTLS command. It must respond to that command, and then negotiate | |
839 | a TLS session. | |
840 | ||
841 | Arguments: | |
83da1223 PH |
842 | require_ciphers list of allowed ciphers or NULL |
843 | require_mac list of allowed MACs or NULL | |
844 | require_kx list of allowed key_exchange methods or NULL | |
845 | require_proto list of allowed protocols or NULL | |
059ec3d9 PH |
846 | |
847 | Returns: OK on success | |
848 | DEFER for errors before the start of the negotiation | |
849 | FAIL for errors during the negotation; the server can't | |
850 | continue running. | |
851 | */ | |
852 | ||
853 | int | |
83da1223 PH |
854 | tls_server_start(uschar *require_ciphers, uschar *require_mac, |
855 | uschar *require_kx, uschar *require_proto) | |
059ec3d9 PH |
856 | { |
857 | int rc; | |
858 | uschar *error; | |
859 | uschar *expciphers = NULL; | |
83da1223 PH |
860 | uschar *expmac = NULL; |
861 | uschar *expkx = NULL; | |
862 | uschar *expproto = NULL; | |
059ec3d9 PH |
863 | |
864 | /* Check for previous activation */ | |
865 | ||
866 | if (tls_active >= 0) | |
867 | { | |
868 | log_write(0, LOG_MAIN, "STARTTLS received in already encrypted " | |
869 | "connection from %s", | |
870 | (sender_fullhost != NULL)? sender_fullhost : US"local process"); | |
871 | smtp_printf("554 Already in TLS\r\n"); | |
872 | return FAIL; | |
873 | } | |
874 | ||
875 | /* Initialize the library. If it fails, it will already have logged the error | |
876 | and sent an SMTP response. */ | |
877 | ||
878 | DEBUG(D_tls) debug_printf("initializing GnuTLS as a server\n"); | |
879 | ||
880 | rc = tls_init(NULL, tls_certificate, tls_privatekey, tls_verify_certificates, | |
881 | tls_crl); | |
882 | if (rc != OK) return rc; | |
883 | ||
83da1223 PH |
884 | if (!expand_check(require_ciphers, US"tls_require_ciphers", &expciphers) || |
885 | !expand_check(require_mac, US"gnutls_require_mac", &expmac) || | |
886 | !expand_check(require_kx, US"gnutls_require_kx", &expkx) || | |
887 | !expand_check(require_proto, US"gnutls_require_proto", &expproto)) | |
059ec3d9 PH |
888 | return FAIL; |
889 | ||
890 | /* If this is a host for which certificate verification is mandatory or | |
891 | optional, set up appropriately. */ | |
892 | ||
893 | tls_certificate_verified = FALSE; | |
894 | verify_requirement = VERIFY_NONE; | |
895 | ||
896 | if (verify_check_host(&tls_verify_hosts) == OK) | |
897 | verify_requirement = VERIFY_REQUIRED; | |
898 | else if (verify_check_host(&tls_try_verify_hosts) == OK) | |
899 | verify_requirement = VERIFY_OPTIONAL; | |
900 | ||
901 | /* Prepare for new connection */ | |
902 | ||
83da1223 PH |
903 | tls_session = tls_session_init(GNUTLS_SERVER, expciphers, expmac, expkx, |
904 | expproto); | |
059ec3d9 PH |
905 | if (tls_session == NULL) |
906 | return tls_error(US"tls_session_init", NULL, GNUTLS_E_MEMORY_ERROR); | |
907 | ||
908 | /* Set context and tell client to go ahead, except in the case of TLS startup | |
909 | on connection, where outputting anything now upsets the clients and tends to | |
910 | make them disconnect. We need to have an explicit fflush() here, to force out | |
911 | the response. Other smtp_printf() calls do not need it, because in non-TLS | |
912 | mode, the fflush() happens when smtp_getc() is called. */ | |
913 | ||
914 | if (!tls_on_connect) | |
915 | { | |
916 | smtp_printf("220 TLS go ahead\r\n"); | |
917 | fflush(smtp_out); | |
918 | } | |
919 | ||
920 | /* Now negotiate the TLS session. We put our own timer on it, since it seems | |
921 | that the GnuTLS library doesn't. */ | |
922 | ||
56f5d9bd PH |
923 | gnutls_transport_set_ptr2(tls_session, (gnutls_transport_ptr)fileno(smtp_in), |
924 | (gnutls_transport_ptr)fileno(smtp_out)); | |
059ec3d9 PH |
925 | |
926 | sigalrm_seen = FALSE; | |
927 | if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout); | |
928 | rc = gnutls_handshake(tls_session); | |
929 | alarm(0); | |
930 | ||
931 | if (rc < 0) | |
932 | { | |
933 | if (sigalrm_seen) | |
934 | Ustrcpy(ssl_errstring, "timed out"); | |
935 | else | |
936 | Ustrcpy(ssl_errstring, gnutls_strerror(rc)); | |
937 | log_write(0, LOG_MAIN, | |
938 | "TLS error on connection from %s (gnutls_handshake): %s", | |
939 | (sender_fullhost != NULL)? sender_fullhost : US"local process", | |
940 | ssl_errstring); | |
941 | ||
942 | /* It seems that, except in the case of a timeout, we have to close the | |
943 | connection right here; otherwise if the other end is running OpenSSL it hangs | |
944 | until the server times out. */ | |
945 | ||
946 | if (!sigalrm_seen) | |
947 | { | |
f1e894f3 PH |
948 | (void)fclose(smtp_out); |
949 | (void)fclose(smtp_in); | |
059ec3d9 PH |
950 | } |
951 | ||
952 | return FAIL; | |
953 | } | |
954 | ||
955 | DEBUG(D_tls) debug_printf("gnutls_handshake was successful\n"); | |
956 | ||
957 | if (verify_requirement != VERIFY_NONE && | |
958 | !verify_certificate(tls_session, &error)) | |
959 | { | |
960 | log_write(0, LOG_MAIN, | |
961 | "TLS error on connection from %s: certificate verification failed (%s)", | |
962 | (sender_fullhost != NULL)? sender_fullhost : US"local process", error); | |
963 | return FAIL; | |
964 | } | |
965 | ||
966 | construct_cipher_name(tls_session); | |
967 | ||
968 | /* TLS has been set up. Adjust the input functions to read via TLS, | |
969 | and initialize appropriately. */ | |
970 | ||
971 | ssl_xfer_buffer = store_malloc(ssl_xfer_buffer_size); | |
972 | ssl_xfer_buffer_lwm = ssl_xfer_buffer_hwm = 0; | |
973 | ssl_xfer_eof = ssl_xfer_error = 0; | |
974 | ||
975 | receive_getc = tls_getc; | |
976 | receive_ungetc = tls_ungetc; | |
977 | receive_feof = tls_feof; | |
978 | receive_ferror = tls_ferror; | |
58eb016e | 979 | receive_smtp_buffered = tls_smtp_buffered; |
059ec3d9 PH |
980 | |
981 | tls_active = fileno(smtp_out); | |
982 | ||
983 | return OK; | |
984 | } | |
985 | ||
986 | ||
987 | ||
988 | ||
989 | /************************************************* | |
990 | * Start a TLS session in a client * | |
991 | *************************************************/ | |
992 | ||
993 | /* Called from the smtp transport after STARTTLS has been accepted. | |
994 | ||
995 | Arguments: | |
996 | fd the fd of the connection | |
997 | host connected host (for messages) | |
83da1223 | 998 | addr the first address (not used) |
059ec3d9 PH |
999 | dhparam DH parameter file |
1000 | certificate certificate file | |
1001 | privatekey private key file | |
1002 | verify_certs file for certificate verify | |
1003 | verify_crl CRL for verify | |
83da1223 PH |
1004 | require_ciphers list of allowed ciphers or NULL |
1005 | require_mac list of allowed MACs or NULL | |
1006 | require_kx list of allowed key_exchange methods or NULL | |
1007 | require_proto list of allowed protocols or NULL | |
059ec3d9 PH |
1008 | timeout startup timeout |
1009 | ||
1010 | Returns: OK/DEFER/FAIL (because using common functions), | |
1011 | but for a client, DEFER and FAIL have the same meaning | |
1012 | */ | |
1013 | ||
1014 | int | |
1015 | tls_client_start(int fd, host_item *host, address_item *addr, uschar *dhparam, | |
1016 | uschar *certificate, uschar *privatekey, uschar *verify_certs, | |
83da1223 PH |
1017 | uschar *verify_crl, uschar *require_ciphers, uschar *require_mac, |
1018 | uschar *require_kx, uschar *require_proto, int timeout) | |
059ec3d9 PH |
1019 | { |
1020 | const gnutls_datum *server_certs; | |
1021 | uschar *expciphers = NULL; | |
83da1223 PH |
1022 | uschar *expmac = NULL; |
1023 | uschar *expkx = NULL; | |
1024 | uschar *expproto = NULL; | |
059ec3d9 PH |
1025 | uschar *error; |
1026 | unsigned int server_certs_size; | |
1027 | int rc; | |
1028 | ||
1029 | DEBUG(D_tls) debug_printf("initializing GnuTLS as a client\n"); | |
1030 | ||
1031 | client_host = host; | |
1032 | verify_requirement = (verify_certs == NULL)? VERIFY_NONE : VERIFY_REQUIRED; | |
1033 | rc = tls_init(host, certificate, privatekey, verify_certs, verify_crl); | |
1034 | if (rc != OK) return rc; | |
1035 | ||
83da1223 PH |
1036 | if (!expand_check(require_ciphers, US"tls_require_ciphers", &expciphers) || |
1037 | !expand_check(require_mac, US"gnutls_require_mac", &expmac) || | |
1038 | !expand_check(require_kx, US"gnutls_require_kx", &expkx) || | |
1039 | !expand_check(require_proto, US"gnutls_require_proto", &expproto)) | |
059ec3d9 PH |
1040 | return FAIL; |
1041 | ||
83da1223 PH |
1042 | tls_session = tls_session_init(GNUTLS_CLIENT, expciphers, expmac, expkx, |
1043 | expproto); | |
1044 | ||
059ec3d9 PH |
1045 | if (tls_session == NULL) |
1046 | return tls_error(US "tls_session_init", host, GNUTLS_E_MEMORY_ERROR); | |
1047 | ||
1048 | gnutls_transport_set_ptr(tls_session, (gnutls_transport_ptr)fd); | |
1049 | ||
1050 | /* There doesn't seem to be a built-in timeout on connection. */ | |
1051 | ||
1052 | sigalrm_seen = FALSE; | |
1053 | alarm(timeout); | |
1054 | rc = gnutls_handshake(tls_session); | |
1055 | alarm(0); | |
1056 | ||
1057 | if (rc < 0) | |
1058 | { | |
1059 | if (sigalrm_seen) | |
1060 | { | |
1061 | log_write(0, LOG_MAIN, "TLS error on connection to %s [%s]: " | |
1062 | "gnutls_handshake timed out", host->name, host->address); | |
1063 | return FAIL; | |
1064 | } | |
1065 | else return tls_error(US "gnutls_handshake", host, rc); | |
1066 | } | |
1067 | ||
1068 | server_certs = gnutls_certificate_get_peers(tls_session, &server_certs_size); | |
1069 | ||
1070 | if (server_certs != NULL) | |
1071 | { | |
1072 | uschar buff[1024]; | |
1073 | gnutls_x509_crt gcert; | |
1074 | ||
1075 | gnutls_x509_crt_init(&gcert); | |
1076 | tls_peerdn = US"unknown"; | |
1077 | ||
1078 | if (gnutls_x509_crt_import(gcert, server_certs, GNUTLS_X509_FMT_DER) == 0) | |
1079 | { | |
1080 | size_t bufsize = sizeof(buff); | |
1081 | if (gnutls_x509_crt_get_dn(gcert, CS buff, &bufsize) >= 0) | |
1082 | tls_peerdn = string_copy_malloc(buff); | |
1083 | } | |
1084 | } | |
1085 | ||
1086 | /* Should we also verify the hostname here? */ | |
1087 | ||
1088 | if (verify_requirement != VERIFY_NONE && | |
1089 | !verify_certificate(tls_session, &error)) | |
1090 | { | |
1091 | log_write(0, LOG_MAIN, | |
1092 | "TLS error on connection to %s [%s]: certificate verification failed (%s)", | |
1093 | host->name, host->address, error); | |
1094 | return FAIL; | |
1095 | } | |
1096 | ||
1097 | construct_cipher_name(tls_session); /* Sets tls_cipher */ | |
1098 | tls_active = fd; | |
1099 | return OK; | |
1100 | } | |
1101 | ||
1102 | ||
1103 | ||
1104 | /************************************************* | |
1105 | * Deal with logging errors during I/O * | |
1106 | *************************************************/ | |
1107 | ||
1108 | /* We have to get the identity of the peer from saved data. | |
1109 | ||
1110 | Argument: | |
1111 | ec the GnuTLS error code, or 0 if it's a local error | |
1112 | when text identifying read or write | |
1113 | text local error text when ec is 0 | |
1114 | ||
1115 | Returns: nothing | |
1116 | */ | |
1117 | ||
1118 | static void | |
1119 | record_io_error(int ec, uschar *when, uschar *text) | |
1120 | { | |
1121 | uschar *additional = US""; | |
1122 | ||
1123 | if (ec == GNUTLS_E_FATAL_ALERT_RECEIVED) | |
1124 | additional = string_sprintf(": %s", | |
1125 | gnutls_alert_get_name(gnutls_alert_get(tls_session))); | |
1126 | ||
1127 | if (initialized == INITIALIZED_SERVER) | |
1128 | log_write(0, LOG_MAIN, "TLS %s error on connection from %s: %s%s", when, | |
1129 | (sender_fullhost != NULL)? sender_fullhost : US "local process", | |
1130 | (ec == 0)? text : US gnutls_strerror(ec), additional); | |
1131 | ||
1132 | else | |
1133 | log_write(0, LOG_MAIN, "TLS %s error on connection to %s [%s]: %s%s", when, | |
1134 | client_host->name, client_host->address, | |
1135 | (ec == 0)? text : US gnutls_strerror(ec), additional); | |
1136 | } | |
1137 | ||
1138 | ||
1139 | ||
1140 | /************************************************* | |
1141 | * TLS version of getc * | |
1142 | *************************************************/ | |
1143 | ||
1144 | /* This gets the next byte from the TLS input buffer. If the buffer is empty, | |
1145 | it refills the buffer via the GnuTLS reading function. | |
1146 | ||
1147 | Arguments: none | |
1148 | Returns: the next character or EOF | |
1149 | */ | |
1150 | ||
1151 | int | |
1152 | tls_getc(void) | |
1153 | { | |
1154 | if (ssl_xfer_buffer_lwm >= ssl_xfer_buffer_hwm) | |
1155 | { | |
1156 | int inbytes; | |
1157 | ||
1158 | DEBUG(D_tls) debug_printf("Calling gnutls_record_recv(%lx, %lx, %u)\n", | |
1159 | (long) tls_session, (long) ssl_xfer_buffer, ssl_xfer_buffer_size); | |
1160 | ||
1161 | if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout); | |
1162 | inbytes = gnutls_record_recv(tls_session, CS ssl_xfer_buffer, | |
1163 | ssl_xfer_buffer_size); | |
1164 | alarm(0); | |
1165 | ||
1166 | /* A zero-byte return appears to mean that the TLS session has been | |
1167 | closed down, not that the socket itself has been closed down. Revert to | |
1168 | non-TLS handling. */ | |
1169 | ||
1170 | if (inbytes == 0) | |
1171 | { | |
1172 | DEBUG(D_tls) debug_printf("Got TLS_EOF\n"); | |
1173 | ||
1174 | receive_getc = smtp_getc; | |
1175 | receive_ungetc = smtp_ungetc; | |
1176 | receive_feof = smtp_feof; | |
1177 | receive_ferror = smtp_ferror; | |
58eb016e | 1178 | receive_smtp_buffered = smtp_buffered; |
059ec3d9 PH |
1179 | |
1180 | gnutls_deinit(tls_session); | |
1181 | tls_session = NULL; | |
1182 | tls_active = -1; | |
1183 | tls_cipher = NULL; | |
1184 | tls_peerdn = NULL; | |
1185 | ||
1186 | return smtp_getc(); | |
1187 | } | |
1188 | ||
1189 | /* Handle genuine errors */ | |
1190 | ||
1191 | else if (inbytes < 0) | |
1192 | { | |
1193 | record_io_error(inbytes, US"recv", NULL); | |
1194 | ssl_xfer_error = 1; | |
1195 | return EOF; | |
1196 | } | |
1197 | ||
1198 | ssl_xfer_buffer_hwm = inbytes; | |
1199 | ssl_xfer_buffer_lwm = 0; | |
1200 | } | |
1201 | ||
1202 | ||
1203 | /* Something in the buffer; return next uschar */ | |
1204 | ||
1205 | return ssl_xfer_buffer[ssl_xfer_buffer_lwm++]; | |
1206 | } | |
1207 | ||
1208 | ||
1209 | ||
1210 | /************************************************* | |
1211 | * Read bytes from TLS channel * | |
1212 | *************************************************/ | |
1213 | ||
1214 | /* | |
1215 | Arguments: | |
1216 | buff buffer of data | |
1217 | len size of buffer | |
1218 | ||
1219 | Returns: the number of bytes read | |
1220 | -1 after a failed read | |
1221 | */ | |
1222 | ||
1223 | int | |
1224 | tls_read(uschar *buff, size_t len) | |
1225 | { | |
1226 | int inbytes; | |
1227 | ||
1228 | DEBUG(D_tls) debug_printf("Calling gnutls_record_recv(%lx, %lx, %u)\n", | |
1229 | (long) tls_session, (long) buff, len); | |
1230 | ||
1231 | inbytes = gnutls_record_recv(tls_session, CS buff, len); | |
1232 | if (inbytes > 0) return inbytes; | |
1233 | if (inbytes == 0) | |
1234 | { | |
1235 | DEBUG(D_tls) debug_printf("Got TLS_EOF\n"); | |
1236 | } | |
1237 | else record_io_error(inbytes, US"recv", NULL); | |
1238 | ||
1239 | return -1; | |
1240 | } | |
1241 | ||
1242 | ||
1243 | ||
1244 | /************************************************* | |
1245 | * Write bytes down TLS channel * | |
1246 | *************************************************/ | |
1247 | ||
1248 | /* | |
1249 | Arguments: | |
1250 | buff buffer of data | |
1251 | len number of bytes | |
1252 | ||
1253 | Returns: the number of bytes after a successful write, | |
1254 | -1 after a failed write | |
1255 | */ | |
1256 | ||
1257 | int | |
1258 | tls_write(const uschar *buff, size_t len) | |
1259 | { | |
1260 | int outbytes; | |
1261 | int left = len; | |
1262 | ||
1263 | DEBUG(D_tls) debug_printf("tls_do_write(%lx, %d)\n", (long) buff, left); | |
1264 | while (left > 0) | |
1265 | { | |
1266 | DEBUG(D_tls) debug_printf("gnutls_record_send(SSL, %lx, %d)\n", (long)buff, | |
1267 | left); | |
1268 | outbytes = gnutls_record_send(tls_session, CS buff, left); | |
1269 | ||
1270 | DEBUG(D_tls) debug_printf("outbytes=%d\n", outbytes); | |
1271 | if (outbytes < 0) | |
1272 | { | |
1273 | record_io_error(outbytes, US"send", NULL); | |
1274 | return -1; | |
1275 | } | |
1276 | if (outbytes == 0) | |
1277 | { | |
1278 | record_io_error(0, US"send", US"TLS channel closed on write"); | |
1279 | return -1; | |
1280 | } | |
1281 | ||
1282 | left -= outbytes; | |
1283 | buff += outbytes; | |
1284 | } | |
1285 | ||
1286 | return len; | |
1287 | } | |
1288 | ||
1289 | ||
1290 | ||
1291 | /************************************************* | |
1292 | * Close down a TLS session * | |
1293 | *************************************************/ | |
1294 | ||
1295 | /* This is also called from within a delivery subprocess forked from the | |
1296 | daemon, to shut down the TLS library, without actually doing a shutdown (which | |
1297 | would tamper with the TLS session in the parent process). | |
1298 | ||
1299 | Arguments: TRUE if gnutls_bye is to be called | |
1300 | Returns: nothing | |
1301 | */ | |
1302 | ||
1303 | void | |
1304 | tls_close(BOOL shutdown) | |
1305 | { | |
1306 | if (tls_active < 0) return; /* TLS was not active */ | |
1307 | ||
1308 | if (shutdown) | |
1309 | { | |
1310 | DEBUG(D_tls) debug_printf("tls_close(): shutting down TLS\n"); | |
1311 | gnutls_bye(tls_session, GNUTLS_SHUT_WR); | |
1312 | } | |
1313 | ||
1314 | gnutls_deinit(tls_session); | |
1315 | tls_session = NULL; | |
1316 | gnutls_global_deinit(); | |
1317 | ||
1318 | tls_active = -1; | |
1319 | } | |
1320 | ||
1321 | /* End of tls-gnu.c */ |