Commit | Line | Data |
---|---|---|
059ec3d9 PH |
1 | /************************************************* |
2 | * Exim - an Internet mail transport agent * | |
3 | *************************************************/ | |
4 | ||
0a49a7a4 | 5 | /* Copyright (c) University of Cambridge 1995 - 2009 */ |
059ec3d9 PH |
6 | /* See the file NOTICE for conditions of use and distribution. */ |
7 | ||
8 | /* This module provides TLS (aka SSL) support for Exim using the GnuTLS | |
9 | library. It is #included into tls.c when that library is used. The code herein | |
10 | is based on a patch that was contributed by Nikos Mavroyanopoulos. | |
11 | ||
12 | No cryptographic code is included in Exim. All this module does is to call | |
13 | functions from the GnuTLS library. */ | |
14 | ||
15 | ||
16 | /* Heading stuff for GnuTLS */ | |
17 | ||
18 | #include <gnutls/gnutls.h> | |
19 | #include <gnutls/x509.h> | |
20 | ||
21 | ||
22 | #define UNKNOWN_NAME "unknown" | |
87054a31 | 23 | #define DH_BITS 1024 |
b5aea5e1 PH |
24 | #define PARAM_SIZE 2*1024 |
25 | ||
059ec3d9 | 26 | |
7199e1ee | 27 | /* Values for verify_requirment */ |
059ec3d9 PH |
28 | |
29 | enum { VERIFY_NONE, VERIFY_OPTIONAL, VERIFY_REQUIRED }; | |
059ec3d9 PH |
30 | |
31 | /* Local static variables for GNUTLS */ | |
32 | ||
059ec3d9 PH |
33 | static host_item *client_host; |
34 | ||
059ec3d9 PH |
35 | static gnutls_dh_params dh_params = NULL; |
36 | ||
37 | static gnutls_certificate_server_credentials x509_cred = NULL; | |
38 | static gnutls_session tls_session = NULL; | |
39 | ||
40 | static char ssl_errstring[256]; | |
41 | ||
42 | static int ssl_session_timeout = 200; | |
43 | static int verify_requirement; | |
44 | ||
83da1223 PH |
45 | /* Priorities for TLS algorithms to use. In each case there's a default table, |
46 | and space into which it can be copied and altered. */ | |
059ec3d9 | 47 | |
83da1223 PH |
48 | static const int default_proto_priority[16] = { |
49 | GNUTLS_TLS1, | |
50 | GNUTLS_SSL3, | |
51 | 0 }; | |
52 | ||
53 | static int proto_priority[16]; | |
059ec3d9 | 54 | |
83da1223 | 55 | static const int default_kx_priority[16] = { |
059ec3d9 PH |
56 | GNUTLS_KX_RSA, |
57 | GNUTLS_KX_DHE_DSS, | |
58 | GNUTLS_KX_DHE_RSA, | |
059ec3d9 PH |
59 | 0 }; |
60 | ||
83da1223 PH |
61 | static int kx_priority[16]; |
62 | ||
059ec3d9 | 63 | static int default_cipher_priority[16] = { |
26dd5a95 | 64 | GNUTLS_CIPHER_AES_256_CBC, |
059ec3d9 PH |
65 | GNUTLS_CIPHER_AES_128_CBC, |
66 | GNUTLS_CIPHER_3DES_CBC, | |
26dd5a95 | 67 | GNUTLS_CIPHER_ARCFOUR_128, |
059ec3d9 PH |
68 | 0 }; |
69 | ||
70 | static int cipher_priority[16]; | |
71 | ||
83da1223 | 72 | static const int default_mac_priority[16] = { |
059ec3d9 PH |
73 | GNUTLS_MAC_SHA, |
74 | GNUTLS_MAC_MD5, | |
75 | 0 }; | |
76 | ||
83da1223 PH |
77 | static int mac_priority[16]; |
78 | ||
79 | /* These two are currently not changeable. */ | |
80 | ||
059ec3d9 PH |
81 | static const int comp_priority[16] = { GNUTLS_COMP_NULL, 0 }; |
82 | static const int cert_type_priority[16] = { GNUTLS_CRT_X509, 0 }; | |
83 | ||
83da1223 | 84 | /* Tables of priority names and equivalent numbers */ |
059ec3d9 PH |
85 | |
86 | typedef struct pri_item { | |
87 | uschar *name; | |
88 | int *values; | |
89 | } pri_item; | |
90 | ||
83da1223 PH |
91 | |
92 | static int tls1_codes[] = { GNUTLS_TLS1, 0 }; | |
93 | static int ssl3_codes[] = { GNUTLS_SSL3, 0 }; | |
94 | ||
95 | static pri_item proto_index[] = { | |
96 | { US"TLS1", tls1_codes }, | |
97 | { US"SSL3", ssl3_codes } | |
98 | }; | |
99 | ||
100 | ||
101 | static int kx_rsa_codes[] = { GNUTLS_KX_RSA, | |
102 | GNUTLS_KX_DHE_RSA, 0 }; | |
103 | static int kx_dhe_codes[] = { GNUTLS_KX_DHE_DSS, | |
104 | GNUTLS_KX_DHE_RSA, 0 }; | |
105 | static int kx_dhe_dss_codes[] = { GNUTLS_KX_DHE_DSS, 0 }; | |
106 | static int kx_dhe_rsa_codes[] = { GNUTLS_KX_DHE_RSA, 0 }; | |
107 | ||
108 | static pri_item kx_index[] = { | |
109 | { US"DHE_DSS", kx_dhe_dss_codes }, | |
110 | { US"DHE_RSA", kx_dhe_rsa_codes }, | |
111 | { US"RSA", kx_rsa_codes }, | |
112 | { US"DHE", kx_dhe_codes } | |
113 | }; | |
114 | ||
115 | ||
059ec3d9 PH |
116 | static int arcfour_128_codes[] = { GNUTLS_CIPHER_ARCFOUR_128, 0 }; |
117 | static int arcfour_40_codes[] = { GNUTLS_CIPHER_ARCFOUR_40, 0 }; | |
118 | static int arcfour_codes[] = { GNUTLS_CIPHER_ARCFOUR_128, | |
119 | GNUTLS_CIPHER_ARCFOUR_40, 0 }; | |
120 | static int aes_256_codes[] = { GNUTLS_CIPHER_AES_256_CBC, 0 }; | |
121 | static int aes_128_codes[] = { GNUTLS_CIPHER_AES_128_CBC, 0 }; | |
122 | static int aes_codes[] = { GNUTLS_CIPHER_AES_256_CBC, | |
123 | GNUTLS_CIPHER_AES_128_CBC, 0 }; | |
124 | static int des3_codes[] = { GNUTLS_CIPHER_3DES_CBC, 0 }; | |
125 | ||
126 | static pri_item cipher_index[] = { | |
127 | { US"ARCFOUR_128", arcfour_128_codes }, | |
128 | { US"ARCFOUR_40", arcfour_40_codes }, | |
129 | { US"ARCFOUR", arcfour_codes }, | |
130 | { US"AES_256", aes_256_codes }, | |
131 | { US"AES_128", aes_128_codes }, | |
132 | { US"AES", aes_codes }, | |
133 | { US"3DES", des3_codes } | |
134 | }; | |
135 | ||
136 | ||
83da1223 PH |
137 | static int mac_sha_codes[] = { GNUTLS_MAC_SHA, 0 }; |
138 | static int mac_md5_codes[] = { GNUTLS_MAC_MD5, 0 }; | |
139 | ||
140 | static pri_item mac_index[] = { | |
141 | { US"SHA", mac_sha_codes }, | |
142 | { US"SHA1", mac_sha_codes }, | |
143 | { US"MD5", mac_md5_codes } | |
144 | }; | |
145 | ||
146 | ||
059ec3d9 PH |
147 | |
148 | /************************************************* | |
149 | * Handle TLS error * | |
150 | *************************************************/ | |
151 | ||
152 | /* Called from lots of places when errors occur before actually starting to do | |
153 | the TLS handshake, that is, while the session is still in clear. Always returns | |
154 | DEFER for a server and FAIL for a client so that most calls can use "return | |
155 | tls_error(...)" to do this processing and then give an appropriate return. A | |
156 | single function is used for both server and client, because it is called from | |
157 | some shared functions. | |
158 | ||
159 | Argument: | |
160 | prefix text to include in the logged error | |
161 | host NULL if setting up a server; | |
162 | the connected host if setting up a client | |
7199e1ee TF |
163 | msg additional error string (may be NULL) |
164 | usually obtained from gnutls_strerror() | |
059ec3d9 PH |
165 | |
166 | Returns: OK/DEFER/FAIL | |
167 | */ | |
168 | ||
169 | static int | |
7199e1ee | 170 | tls_error(uschar *prefix, host_item *host, const char *msg) |
059ec3d9 | 171 | { |
059ec3d9 PH |
172 | if (host == NULL) |
173 | { | |
7199e1ee TF |
174 | uschar *conn_info = smtp_get_connection_info(); |
175 | if (strncmp(conn_info, "SMTP ", 5) == 0) | |
176 | conn_info += 5; | |
177 | log_write(0, LOG_MAIN, "TLS error on %s (%s)%s%s", | |
178 | conn_info, prefix, msg ? ": " : "", msg ? msg : ""); | |
059ec3d9 PH |
179 | return DEFER; |
180 | } | |
181 | else | |
182 | { | |
7199e1ee TF |
183 | log_write(0, LOG_MAIN, "TLS error on connection to %s [%s] (%s)%s%s", |
184 | host->name, host->address, prefix, msg ? ": " : "", msg ? msg : ""); | |
059ec3d9 PH |
185 | return FAIL; |
186 | } | |
187 | } | |
188 | ||
189 | ||
190 | ||
191 | /************************************************* | |
192 | * Verify certificate * | |
193 | *************************************************/ | |
194 | ||
195 | /* Called after a successful handshake, when certificate verification is | |
196 | required or optional, for both server and client. | |
197 | ||
198 | Arguments: | |
199 | session GNUTLS session | |
200 | error where to put text giving a reason for failure | |
201 | ||
202 | Returns: TRUE/FALSE | |
203 | */ | |
204 | ||
205 | static BOOL | |
7199e1ee | 206 | verify_certificate(gnutls_session session, const char **error) |
059ec3d9 PH |
207 | { |
208 | int verify; | |
209 | uschar *dn_string = US""; | |
210 | const gnutls_datum *cert; | |
211 | unsigned int cert_size = 0; | |
212 | ||
213 | *error = NULL; | |
214 | ||
215 | /* Get the peer's certificate. If it sent one, extract it's DN, and then | |
216 | attempt to verify the certificate. If no certificate is supplied, verification | |
217 | is forced to fail. */ | |
218 | ||
219 | cert = gnutls_certificate_get_peers(session, &cert_size); | |
220 | if (cert != NULL) | |
221 | { | |
222 | uschar buff[1024]; | |
223 | gnutls_x509_crt gcert; | |
224 | ||
225 | gnutls_x509_crt_init(&gcert); | |
226 | dn_string = US"unknown"; | |
227 | ||
228 | if (gnutls_x509_crt_import(gcert, cert, GNUTLS_X509_FMT_DER) == 0) | |
229 | { | |
230 | size_t bufsize = sizeof(buff); | |
231 | if (gnutls_x509_crt_get_dn(gcert, CS buff, &bufsize) >= 0) | |
232 | dn_string = string_copy_malloc(buff); | |
233 | } | |
234 | ||
235 | verify = gnutls_certificate_verify_peers(session); | |
236 | } | |
237 | else | |
238 | { | |
239 | DEBUG(D_tls) debug_printf("no peer certificate supplied\n"); | |
240 | verify = GNUTLS_CERT_INVALID; | |
7199e1ee | 241 | *error = "not supplied"; |
059ec3d9 PH |
242 | } |
243 | ||
244 | /* Handle the result of verification. INVALID seems to be set as well | |
245 | as REVOKED, but leave the test for both. */ | |
246 | ||
247 | if ((verify & (GNUTLS_CERT_INVALID|GNUTLS_CERT_REVOKED)) != 0) | |
248 | { | |
249 | tls_certificate_verified = FALSE; | |
250 | if (*error == NULL) *error = ((verify & GNUTLS_CERT_REVOKED) != 0)? | |
7199e1ee | 251 | "revoked" : "invalid"; |
059ec3d9 PH |
252 | if (verify_requirement == VERIFY_REQUIRED) |
253 | { | |
254 | DEBUG(D_tls) debug_printf("TLS certificate verification failed (%s): " | |
255 | "peerdn=%s\n", *error, dn_string); | |
256 | gnutls_alert_send(session, GNUTLS_AL_FATAL, GNUTLS_A_BAD_CERTIFICATE); | |
257 | return FALSE; /* reject */ | |
258 | } | |
259 | DEBUG(D_tls) debug_printf("TLS certificate verify failure (%s) overridden " | |
260 | "(host in tls_try_verify_hosts): peerdn=%s\n", *error, dn_string); | |
261 | } | |
262 | else | |
263 | { | |
264 | tls_certificate_verified = TRUE; | |
265 | DEBUG(D_tls) debug_printf("TLS certificate verified: peerdn=%s\n", | |
266 | dn_string); | |
267 | } | |
268 | ||
269 | tls_peerdn = dn_string; | |
270 | return TRUE; /* accept */ | |
271 | } | |
272 | ||
273 | ||
274 | ||
059ec3d9 | 275 | /************************************************* |
575643cd | 276 | * Setup up DH parameters * |
059ec3d9 PH |
277 | *************************************************/ |
278 | ||
575643cd | 279 | /* Generating the D-H parameters may take a long time. They only need to |
059ec3d9 PH |
280 | be re-generated every so often, depending on security policy. What we do is to |
281 | keep these parameters in a file in the spool directory. If the file does not | |
282 | exist, we generate them. This means that it is easy to cause a regeneration. | |
283 | ||
284 | The new file is written as a temporary file and renamed, so that an incomplete | |
285 | file is never present. If two processes both compute some new parameters, you | |
286 | waste a bit of effort, but it doesn't seem worth messing around with locking to | |
287 | prevent this. | |
288 | ||
289 | Argument: | |
290 | host NULL for server, server for client (for error handling) | |
291 | ||
292 | Returns: OK/DEFER/FAIL | |
293 | */ | |
294 | ||
295 | static int | |
575643cd | 296 | init_dh(host_item *host) |
059ec3d9 | 297 | { |
b5aea5e1 | 298 | int fd; |
182ad5cf | 299 | int ret; |
b5aea5e1 | 300 | gnutls_datum m; |
059ec3d9 PH |
301 | uschar filename[200]; |
302 | ||
303 | /* Initialize the data structures for holding the parameters */ | |
304 | ||
059ec3d9 | 305 | ret = gnutls_dh_params_init(&dh_params); |
7199e1ee | 306 | if (ret < 0) return tls_error(US"init dh_params", host, gnutls_strerror(ret)); |
059ec3d9 PH |
307 | |
308 | /* Set up the name of the cache file */ | |
309 | ||
310 | if (!string_format(filename, sizeof(filename), "%s/gnutls-params", | |
311 | spool_directory)) | |
7199e1ee | 312 | return tls_error(US"overlong filename", host, NULL); |
059ec3d9 | 313 | |
b5aea5e1 | 314 | /* Open the cache file for reading and if successful, read it and set up the |
575643cd | 315 | parameters. */ |
059ec3d9 PH |
316 | |
317 | fd = Uopen(filename, O_RDONLY, 0); | |
b5aea5e1 | 318 | if (fd >= 0) |
059ec3d9 | 319 | { |
b5aea5e1 PH |
320 | struct stat statbuf; |
321 | if (fstat(fd, &statbuf) < 0) | |
322 | { | |
323 | (void)close(fd); | |
7199e1ee | 324 | return tls_error(US"TLS cache stat failed", host, strerror(errno)); |
b5aea5e1 | 325 | } |
059ec3d9 | 326 | |
b5aea5e1 PH |
327 | m.size = statbuf.st_size; |
328 | m.data = malloc(m.size); | |
329 | if (m.data == NULL) | |
7199e1ee TF |
330 | return tls_error(US"memory allocation failed", host, strerror(errno)); |
331 | errno = 0; | |
b5aea5e1 | 332 | if (read(fd, m.data, m.size) != m.size) |
7199e1ee | 333 | return tls_error(US"TLS cache read failed", host, strerror(errno)); |
b5aea5e1 PH |
334 | (void)close(fd); |
335 | ||
411ef850 | 336 | ret = gnutls_dh_params_import_pkcs3(dh_params, &m, GNUTLS_X509_FMT_PEM); |
7199e1ee TF |
337 | if (ret < 0) |
338 | return tls_error(US"DH params import", host, gnutls_strerror(ret)); | |
575643cd | 339 | DEBUG(D_tls) debug_printf("read D-H parameters from file\n"); |
b5aea5e1 PH |
340 | |
341 | free(m.data); | |
342 | } | |
343 | ||
344 | /* If the file does not exist, fall through to compute new data and cache it. | |
345 | If there was any other opening error, it is serious. */ | |
346 | ||
182ad5cf PH |
347 | else if (errno == ENOENT) |
348 | { | |
349 | ret = -1; | |
350 | DEBUG(D_tls) | |
351 | debug_printf("parameter cache file %s does not exist\n", filename); | |
352 | } | |
353 | else | |
b5aea5e1 | 354 | return tls_error(string_open_failed(errno, "%s for reading", filename), |
7199e1ee | 355 | host, NULL); |
b5aea5e1 PH |
356 | |
357 | /* If ret < 0, either the cache file does not exist, or the data it contains | |
358 | is not useful. One particular case of this is when upgrading from an older | |
359 | release of Exim in which the data was stored in a different format. We don't | |
360 | try to be clever and support both formats; we just regenerate new data in this | |
361 | case. */ | |
362 | ||
363 | if (ret < 0) | |
364 | { | |
365 | uschar tempfilename[sizeof(filename) + 10]; | |
059ec3d9 | 366 | |
059ec3d9 PH |
367 | DEBUG(D_tls) debug_printf("generating %d bit Diffie-Hellman key...\n", |
368 | DH_BITS); | |
369 | ret = gnutls_dh_params_generate2(dh_params, DH_BITS); | |
7199e1ee | 370 | if (ret < 0) return tls_error(US"D-H key generation", host, gnutls_strerror(ret)); |
059ec3d9 PH |
371 | |
372 | /* Write the parameters to a file in the spool directory so that we | |
373 | can use them from other Exim processes. */ | |
374 | ||
375 | sprintf(CS tempfilename, "%s-%d", filename, (int)getpid()); | |
376 | fd = Uopen(tempfilename, O_WRONLY|O_CREAT, 0400); | |
377 | if (fd < 0) | |
378 | return tls_error(string_open_failed(errno, "%s for writing", filename), | |
7199e1ee | 379 | host, NULL); |
059ec3d9 PH |
380 | (void)fchown(fd, exim_uid, exim_gid); /* Probably not necessary */ |
381 | ||
b5aea5e1 PH |
382 | /* export the parameters in a format that can be generated using GNUTLS' |
383 | * certtool or other programs. | |
384 | * | |
385 | * The commands for certtool are: | |
411ef850 | 386 | * $ certtool --generate-dh-params --bits 1024 > params |
b5aea5e1 PH |
387 | */ |
388 | ||
389 | m.size = PARAM_SIZE; | |
390 | m.data = malloc(m.size); | |
391 | if (m.data == NULL) | |
7199e1ee | 392 | return tls_error(US"memory allocation failed", host, strerror(errno)); |
b5aea5e1 | 393 | |
b5aea5e1 PH |
394 | m.size = PARAM_SIZE; |
395 | ret = gnutls_dh_params_export_pkcs3(dh_params, GNUTLS_X509_FMT_PEM, m.data, | |
396 | &m.size); | |
7199e1ee TF |
397 | if (ret < 0) |
398 | return tls_error(US"DH params export", host, gnutls_strerror(ret)); | |
059ec3d9 | 399 | |
b5aea5e1 | 400 | m.size = Ustrlen(m.data); |
7199e1ee | 401 | errno = 0; |
b5aea5e1 | 402 | if (write(fd, m.data, m.size) != m.size || write(fd, "\n", 1) != 1) |
7199e1ee | 403 | return tls_error(US"TLS cache write failed", host, strerror(errno)); |
059ec3d9 | 404 | |
b5aea5e1 | 405 | free(m.data); |
059ec3d9 PH |
406 | (void)close(fd); |
407 | ||
408 | if (rename(CS tempfilename, CS filename) < 0) | |
7199e1ee TF |
409 | return tls_error(string_sprintf("failed to rename %s as %s", |
410 | tempfilename, filename), host, strerror(errno)); | |
059ec3d9 | 411 | |
411ef850 | 412 | DEBUG(D_tls) debug_printf("wrote D-H parameters to file %s\n", filename); |
059ec3d9 PH |
413 | } |
414 | ||
411ef850 | 415 | DEBUG(D_tls) debug_printf("initialized D-H parameters\n"); |
059ec3d9 PH |
416 | return OK; |
417 | } | |
418 | ||
419 | ||
420 | ||
421 | ||
422 | /************************************************* | |
423 | * Initialize for GnuTLS * | |
424 | *************************************************/ | |
425 | ||
426 | /* Called from both server and client code. In the case of a server, errors | |
427 | before actual TLS negotiation return DEFER. | |
428 | ||
429 | Arguments: | |
430 | host connected host, if client; NULL if server | |
431 | certificate certificate file | |
432 | privatekey private key file | |
433 | cas CA certs file | |
434 | crl CRL file | |
435 | ||
436 | Returns: OK/DEFER/FAIL | |
437 | */ | |
438 | ||
439 | static int | |
440 | tls_init(host_item *host, uschar *certificate, uschar *privatekey, uschar *cas, | |
441 | uschar *crl) | |
442 | { | |
443 | int rc; | |
444 | uschar *cert_expanded, *key_expanded, *cas_expanded, *crl_expanded; | |
445 | ||
7199e1ee | 446 | client_host = host; |
059ec3d9 PH |
447 | |
448 | rc = gnutls_global_init(); | |
7199e1ee | 449 | if (rc < 0) return tls_error(US"tls-init", host, gnutls_strerror(rc)); |
059ec3d9 | 450 | |
575643cd PH |
451 | /* Create D-H parameters, or read them from the cache file. This function does |
452 | its own SMTP error messaging. */ | |
059ec3d9 | 453 | |
575643cd | 454 | rc = init_dh(host); |
059ec3d9 PH |
455 | if (rc != OK) return rc; |
456 | ||
457 | /* Create the credentials structure */ | |
458 | ||
459 | rc = gnutls_certificate_allocate_credentials(&x509_cred); | |
7199e1ee TF |
460 | if (rc < 0) |
461 | return tls_error(US"certificate_allocate_credentials", | |
462 | host, gnutls_strerror(rc)); | |
059ec3d9 PH |
463 | |
464 | /* This stuff must be done for each session, because different certificates | |
465 | may be required for different sessions. */ | |
466 | ||
467 | if (!expand_check(certificate, US"tls_certificate", &cert_expanded)) | |
468 | return DEFER; | |
469 | ||
c91535f3 | 470 | key_expanded = NULL; |
059ec3d9 PH |
471 | if (privatekey != NULL) |
472 | { | |
473 | if (!expand_check(privatekey, US"tls_privatekey", &key_expanded)) | |
474 | return DEFER; | |
475 | } | |
c91535f3 PH |
476 | |
477 | /* If expansion was forced to fail, key_expanded will be NULL. If the result of | |
478 | the expansion is an empty string, ignore it also, and assume that the private | |
479 | key is in the same file as the certificate. */ | |
480 | ||
481 | if (key_expanded == NULL || *key_expanded == 0) | |
482 | key_expanded = cert_expanded; | |
059ec3d9 PH |
483 | |
484 | /* Set the certificate and private keys */ | |
485 | ||
486 | if (cert_expanded != NULL) | |
487 | { | |
488 | DEBUG(D_tls) debug_printf("certificate file = %s\nkey file = %s\n", | |
489 | cert_expanded, key_expanded); | |
490 | rc = gnutls_certificate_set_x509_key_file(x509_cred, CS cert_expanded, | |
491 | CS key_expanded, GNUTLS_X509_FMT_PEM); | |
8e669ac1 | 492 | if (rc < 0) |
de365ded PH |
493 | { |
494 | uschar *msg = string_sprintf("cert/key setup: cert=%s key=%s", | |
8e669ac1 | 495 | cert_expanded, key_expanded); |
7199e1ee | 496 | return tls_error(msg, host, gnutls_strerror(rc)); |
8e669ac1 | 497 | } |
059ec3d9 PH |
498 | } |
499 | ||
500 | /* A certificate is mandatory in a server, but not in a client */ | |
501 | ||
502 | else | |
503 | { | |
504 | if (host == NULL) | |
7199e1ee | 505 | return tls_error(US"no TLS server certificate is specified", NULL, NULL); |
059ec3d9 PH |
506 | DEBUG(D_tls) debug_printf("no TLS client certificate is specified\n"); |
507 | } | |
508 | ||
509 | /* Set the trusted CAs file if one is provided, and then add the CRL if one is | |
510 | provided. Experiment shows that, if the certificate file is empty, an unhelpful | |
511 | error message is provided. However, if we just refrain from setting anything up | |
512 | in that case, certificate verification fails, which seems to be the correct | |
513 | behaviour. */ | |
514 | ||
515 | if (cas != NULL) | |
516 | { | |
517 | struct stat statbuf; | |
518 | ||
519 | if (!expand_check(cas, US"tls_verify_certificates", &cas_expanded)) | |
520 | return DEFER; | |
521 | ||
522 | if (stat(CS cas_expanded, &statbuf) < 0) | |
523 | { | |
524 | log_write(0, LOG_MAIN|LOG_PANIC, "could not stat %s " | |
525 | "(tls_verify_certificates): %s", cas_expanded, strerror(errno)); | |
526 | return DEFER; | |
527 | } | |
528 | ||
b1c749bb PH |
529 | DEBUG(D_tls) debug_printf("verify certificates = %s size=" OFF_T_FMT "\n", |
530 | cas_expanded, statbuf.st_size); | |
059ec3d9 PH |
531 | |
532 | /* If the cert file is empty, there's no point in loading the CRL file. */ | |
533 | ||
534 | if (statbuf.st_size > 0) | |
535 | { | |
536 | rc = gnutls_certificate_set_x509_trust_file(x509_cred, CS cas_expanded, | |
537 | GNUTLS_X509_FMT_PEM); | |
7199e1ee | 538 | if (rc < 0) return tls_error(US"setup_certs", host, gnutls_strerror(rc)); |
059ec3d9 PH |
539 | |
540 | if (crl != NULL && *crl != 0) | |
541 | { | |
542 | if (!expand_check(crl, US"tls_crl", &crl_expanded)) | |
543 | return DEFER; | |
544 | DEBUG(D_tls) debug_printf("loading CRL file = %s\n", crl_expanded); | |
545 | rc = gnutls_certificate_set_x509_crl_file(x509_cred, CS crl_expanded, | |
546 | GNUTLS_X509_FMT_PEM); | |
7199e1ee | 547 | if (rc < 0) return tls_error(US"CRL setup", host, gnutls_strerror(rc)); |
059ec3d9 PH |
548 | } |
549 | } | |
550 | } | |
551 | ||
552 | /* Associate the parameters with the x509 credentials structure. */ | |
553 | ||
554 | gnutls_certificate_set_dh_params(x509_cred, dh_params); | |
059ec3d9 PH |
555 | |
556 | DEBUG(D_tls) debug_printf("initialized certificate stuff\n"); | |
557 | return OK; | |
558 | } | |
559 | ||
560 | ||
561 | ||
562 | ||
563 | /************************************************* | |
83da1223 | 564 | * Remove from a priority list * |
059ec3d9 PH |
565 | *************************************************/ |
566 | ||
567 | /* Cautiously written so that it will remove duplicates if present. | |
568 | ||
569 | Arguments: | |
570 | list a zero-terminated list | |
571 | remove_list a zero-terminated list to be removed | |
572 | ||
573 | Returns: nothing | |
574 | */ | |
575 | ||
576 | static void | |
83da1223 | 577 | remove_priority(int *list, int *remove_list) |
059ec3d9 PH |
578 | { |
579 | for (; *remove_list != 0; remove_list++) | |
580 | { | |
581 | int *p = list; | |
582 | while (*p != 0) | |
583 | { | |
584 | if (*p == *remove_list) | |
585 | { | |
586 | int *pp = p; | |
587 | do { pp[0] = pp[1]; pp++; } while (*pp != 0); | |
588 | } | |
589 | else p++; | |
590 | } | |
591 | } | |
592 | } | |
593 | ||
594 | ||
595 | ||
596 | /************************************************* | |
83da1223 | 597 | * Add to a priority list * |
059ec3d9 PH |
598 | *************************************************/ |
599 | ||
600 | /* Cautiously written to check the list size | |
601 | ||
602 | Arguments: | |
603 | list a zero-terminated list | |
604 | list_max maximum offset in the list | |
605 | add_list a zero-terminated list to be added | |
606 | ||
607 | Returns: TRUE if OK; FALSE if list overflows | |
608 | */ | |
609 | ||
610 | static BOOL | |
83da1223 | 611 | add_priority(int *list, int list_max, int *add_list) |
059ec3d9 PH |
612 | { |
613 | int next = 0; | |
614 | while (list[next] != 0) next++; | |
615 | while (*add_list != 0) | |
616 | { | |
617 | if (next >= list_max) return FALSE; | |
618 | list[next++] = *add_list++; | |
619 | } | |
620 | list[next] = 0; | |
621 | return TRUE; | |
622 | } | |
623 | ||
624 | ||
625 | ||
83da1223 PH |
626 | /************************************************* |
627 | * Adjust a priority list * | |
628 | *************************************************/ | |
629 | ||
630 | /* This function is called to adjust the lists of cipher algorithms, MAC | |
631 | algorithms, key-exchange methods, and protocols. | |
632 | ||
633 | Arguments: | |
634 | plist the appropriate priority list | |
635 | psize the length of the list | |
636 | s the configuation string | |
637 | index the index of recognized strings | |
638 | isize the length of the index | |
639 | ||
640 | ||
641 | which text for an error message | |
642 | ||
643 | Returns: FALSE if the table overflows, else TRUE | |
644 | */ | |
645 | ||
646 | static BOOL | |
647 | set_priority(int *plist, int psize, uschar *s, pri_item *index, int isize, | |
648 | uschar *which) | |
649 | { | |
650 | int sep = 0; | |
651 | BOOL first = TRUE; | |
652 | uschar *t; | |
653 | ||
654 | while ((t = string_nextinlist(&s, &sep, big_buffer, big_buffer_size)) != NULL) | |
655 | { | |
656 | int i; | |
657 | BOOL exclude = t[0] == '!'; | |
658 | if (first && !exclude) plist[0] = 0; | |
659 | first = FALSE; | |
660 | for (i = 0; i < isize; i++) | |
661 | { | |
662 | uschar *ss = strstric(t, index[i].name, FALSE); | |
663 | if (ss != NULL) | |
664 | { | |
665 | uschar *endss = ss + Ustrlen(index[i].name); | |
666 | if ((ss == t || !isalnum(ss[-1])) && !isalnum(*endss)) | |
667 | { | |
668 | if (exclude) | |
669 | remove_priority(plist, index[i].values); | |
670 | else | |
671 | { | |
672 | if (!add_priority(plist, psize, index[i].values)) | |
673 | { | |
674 | log_write(0, LOG_MAIN|LOG_PANIC, "GnuTLS init failed: %s " | |
675 | "priority table overflow", which); | |
676 | return FALSE; | |
677 | } | |
678 | } | |
679 | } | |
680 | } | |
681 | } | |
682 | } | |
683 | ||
684 | DEBUG(D_tls) | |
685 | { | |
686 | int *ptr = plist; | |
687 | debug_printf("adjusted %s priorities:", which); | |
688 | while (*ptr != 0) debug_printf(" %d", *ptr++); | |
689 | debug_printf("\n"); | |
690 | } | |
691 | ||
692 | return TRUE; | |
693 | } | |
694 | ||
695 | ||
696 | ||
697 | ||
059ec3d9 PH |
698 | /************************************************* |
699 | * Initialize a single GNUTLS session * | |
700 | *************************************************/ | |
701 | ||
702 | /* Set the algorithm, the db backend, whether to request certificates etc. | |
703 | ||
704 | TLS in Exim was first implemented using OpenSSL. This has a function to which | |
705 | you pass a list of cipher suites that are permitted/not permitted. GnuTLS works | |
706 | differently. It operates using priority lists for the different components of | |
707 | cipher suites. | |
708 | ||
709 | For compatibility of configuration, we scan a list of cipher suites and set | |
710 | priorities therefrom. However, at the moment, we pay attention only to the bulk | |
711 | cipher. | |
712 | ||
713 | Arguments: | |
714 | side one of GNUTLS_SERVER, GNUTLS_CLIENT | |
83da1223 PH |
715 | expciphers expanded ciphers list or NULL |
716 | expmac expanded MAC list or NULL | |
717 | expkx expanded key-exchange list or NULL | |
718 | expproto expanded protocol list or NULL | |
059ec3d9 PH |
719 | |
720 | Returns: a gnutls_session, or NULL if there is a problem | |
721 | */ | |
722 | ||
723 | static gnutls_session | |
83da1223 PH |
724 | tls_session_init(int side, uschar *expciphers, uschar *expmac, uschar *expkx, |
725 | uschar *expproto) | |
059ec3d9 PH |
726 | { |
727 | gnutls_session session; | |
728 | ||
729 | gnutls_init(&session, side); | |
730 | ||
83da1223 PH |
731 | /* Initialize the lists of permitted protocols, key-exchange methods, ciphers, |
732 | and MACs. */ | |
059ec3d9 PH |
733 | |
734 | memcpy(cipher_priority, default_cipher_priority, sizeof(cipher_priority)); | |
83da1223 PH |
735 | memcpy(mac_priority, default_mac_priority, sizeof(mac_priority)); |
736 | memcpy(kx_priority, default_kx_priority, sizeof(kx_priority)); | |
737 | memcpy(proto_priority, default_proto_priority, sizeof(proto_priority)); | |
738 | ||
739 | /* The names OpenSSL uses in tls_require_ciphers are of the form DES-CBC3-SHA, | |
740 | using hyphen separators. GnuTLS uses underscore separators. So that I can use | |
741 | either form for tls_require_ciphers in my tests, and also for general | |
742 | convenience, we turn hyphens into underscores before scanning the list. */ | |
059ec3d9 PH |
743 | |
744 | if (expciphers != NULL) | |
745 | { | |
059ec3d9 PH |
746 | uschar *s = expciphers; |
747 | while (*s != 0) { if (*s == '-') *s = '_'; s++; } | |
83da1223 | 748 | } |
059ec3d9 | 749 | |
83da1223 PH |
750 | if ((expciphers != NULL && |
751 | !set_priority(cipher_priority, sizeof(cipher_priority)/sizeof(int), | |
752 | expciphers, cipher_index, sizeof(cipher_index)/sizeof(pri_item), | |
753 | US"cipher")) || | |
754 | (expmac != NULL && | |
755 | !set_priority(mac_priority, sizeof(mac_priority)/sizeof(int), | |
756 | expmac, mac_index, sizeof(mac_index)/sizeof(pri_item), | |
757 | US"MAC")) || | |
758 | (expkx != NULL && | |
759 | !set_priority(kx_priority, sizeof(kx_priority)/sizeof(int), | |
760 | expkx, kx_index, sizeof(kx_index)/sizeof(pri_item), | |
761 | US"key-exchange")) || | |
762 | (expproto != NULL && | |
763 | !set_priority(proto_priority, sizeof(proto_priority)/sizeof(int), | |
764 | expproto, proto_index, sizeof(proto_index)/sizeof(pri_item), | |
765 | US"protocol"))) | |
766 | { | |
767 | gnutls_deinit(session); | |
768 | return NULL; | |
059ec3d9 PH |
769 | } |
770 | ||
771 | /* Define the various priorities */ | |
772 | ||
773 | gnutls_cipher_set_priority(session, cipher_priority); | |
774 | gnutls_compression_set_priority(session, comp_priority); | |
775 | gnutls_kx_set_priority(session, kx_priority); | |
83da1223 | 776 | gnutls_protocol_set_priority(session, proto_priority); |
059ec3d9 PH |
777 | gnutls_mac_set_priority(session, mac_priority); |
778 | ||
779 | gnutls_cred_set(session, GNUTLS_CRD_CERTIFICATE, x509_cred); | |
780 | ||
781 | gnutls_dh_set_prime_bits(session, DH_BITS); | |
782 | ||
783 | /* Request or demand a certificate of the peer, as configured. This will | |
784 | happen only in a server. */ | |
785 | ||
786 | if (verify_requirement != VERIFY_NONE) | |
787 | gnutls_certificate_server_set_request(session, | |
788 | (verify_requirement == VERIFY_OPTIONAL)? | |
789 | GNUTLS_CERT_REQUEST : GNUTLS_CERT_REQUIRE); | |
790 | ||
791 | gnutls_db_set_cache_expiration(session, ssl_session_timeout); | |
792 | ||
e6060e2c NM |
793 | /* Reduce security in favour of increased compatibility, if the admin |
794 | decides to make that trade-off. */ | |
795 | if (gnutls_compat_mode) | |
796 | { | |
797 | #if LIBGNUTLS_VERSION_NUMBER >= 0x020104 | |
798 | DEBUG(D_tls) debug_printf("lowering GnuTLS security, compatibility mode\n"); | |
799 | gnutls_session_enable_compatibility_mode(session); | |
800 | #else | |
801 | DEBUG(D_tls) debug_printf("Unable to set gnutls_compat_mode - GnuTLS version too old\n"); | |
802 | #endif | |
803 | } | |
804 | ||
059ec3d9 PH |
805 | DEBUG(D_tls) debug_printf("initialized GnuTLS session\n"); |
806 | return session; | |
807 | } | |
808 | ||
809 | ||
810 | ||
811 | /************************************************* | |
812 | * Get name of cipher in use * | |
813 | *************************************************/ | |
814 | ||
815 | /* The answer is left in a static buffer, and tls_cipher is set to point | |
816 | to it. | |
817 | ||
818 | Argument: pointer to a GnuTLS session | |
819 | Returns: nothing | |
820 | */ | |
821 | ||
822 | static void | |
823 | construct_cipher_name(gnutls_session session) | |
824 | { | |
825 | static uschar cipherbuf[256]; | |
826 | uschar *ver; | |
827 | int bits, c, kx, mac; | |
828 | ||
829 | ver = string_copy( | |
830 | US gnutls_protocol_get_name(gnutls_protocol_get_version(session))); | |
831 | if (Ustrncmp(ver, "TLS ", 4) == 0) ver[3] = '-'; /* Don't want space */ | |
832 | ||
833 | c = gnutls_cipher_get(session); | |
834 | bits = gnutls_cipher_get_key_size(c); | |
835 | ||
836 | mac = gnutls_mac_get(session); | |
837 | kx = gnutls_kx_get(session); | |
838 | ||
839 | string_format(cipherbuf, sizeof(cipherbuf), "%s:%s:%u", ver, | |
840 | gnutls_cipher_suite_get_name(kx, c, mac), bits); | |
841 | tls_cipher = cipherbuf; | |
842 | ||
843 | DEBUG(D_tls) debug_printf("cipher: %s\n", cipherbuf); | |
844 | } | |
845 | ||
846 | ||
847 | ||
848 | /************************************************* | |
849 | * Start a TLS session in a server * | |
850 | *************************************************/ | |
851 | ||
852 | /* This is called when Exim is running as a server, after having received | |
853 | the STARTTLS command. It must respond to that command, and then negotiate | |
854 | a TLS session. | |
855 | ||
856 | Arguments: | |
83da1223 PH |
857 | require_ciphers list of allowed ciphers or NULL |
858 | require_mac list of allowed MACs or NULL | |
859 | require_kx list of allowed key_exchange methods or NULL | |
860 | require_proto list of allowed protocols or NULL | |
059ec3d9 PH |
861 | |
862 | Returns: OK on success | |
863 | DEFER for errors before the start of the negotiation | |
864 | FAIL for errors during the negotation; the server can't | |
865 | continue running. | |
866 | */ | |
867 | ||
868 | int | |
83da1223 PH |
869 | tls_server_start(uschar *require_ciphers, uschar *require_mac, |
870 | uschar *require_kx, uschar *require_proto) | |
059ec3d9 PH |
871 | { |
872 | int rc; | |
7199e1ee | 873 | const char *error; |
059ec3d9 | 874 | uschar *expciphers = NULL; |
83da1223 PH |
875 | uschar *expmac = NULL; |
876 | uschar *expkx = NULL; | |
877 | uschar *expproto = NULL; | |
059ec3d9 PH |
878 | |
879 | /* Check for previous activation */ | |
880 | ||
881 | if (tls_active >= 0) | |
882 | { | |
7199e1ee | 883 | tls_error("STARTTLS received after TLS started", NULL, ""); |
059ec3d9 PH |
884 | smtp_printf("554 Already in TLS\r\n"); |
885 | return FAIL; | |
886 | } | |
887 | ||
888 | /* Initialize the library. If it fails, it will already have logged the error | |
889 | and sent an SMTP response. */ | |
890 | ||
891 | DEBUG(D_tls) debug_printf("initializing GnuTLS as a server\n"); | |
892 | ||
893 | rc = tls_init(NULL, tls_certificate, tls_privatekey, tls_verify_certificates, | |
894 | tls_crl); | |
895 | if (rc != OK) return rc; | |
896 | ||
83da1223 PH |
897 | if (!expand_check(require_ciphers, US"tls_require_ciphers", &expciphers) || |
898 | !expand_check(require_mac, US"gnutls_require_mac", &expmac) || | |
899 | !expand_check(require_kx, US"gnutls_require_kx", &expkx) || | |
900 | !expand_check(require_proto, US"gnutls_require_proto", &expproto)) | |
059ec3d9 PH |
901 | return FAIL; |
902 | ||
903 | /* If this is a host for which certificate verification is mandatory or | |
904 | optional, set up appropriately. */ | |
905 | ||
906 | tls_certificate_verified = FALSE; | |
907 | verify_requirement = VERIFY_NONE; | |
908 | ||
909 | if (verify_check_host(&tls_verify_hosts) == OK) | |
910 | verify_requirement = VERIFY_REQUIRED; | |
911 | else if (verify_check_host(&tls_try_verify_hosts) == OK) | |
912 | verify_requirement = VERIFY_OPTIONAL; | |
913 | ||
914 | /* Prepare for new connection */ | |
915 | ||
83da1223 PH |
916 | tls_session = tls_session_init(GNUTLS_SERVER, expciphers, expmac, expkx, |
917 | expproto); | |
059ec3d9 | 918 | if (tls_session == NULL) |
7199e1ee TF |
919 | return tls_error(US"tls_session_init", NULL, |
920 | gnutls_strerror(GNUTLS_E_MEMORY_ERROR)); | |
059ec3d9 PH |
921 | |
922 | /* Set context and tell client to go ahead, except in the case of TLS startup | |
923 | on connection, where outputting anything now upsets the clients and tends to | |
924 | make them disconnect. We need to have an explicit fflush() here, to force out | |
925 | the response. Other smtp_printf() calls do not need it, because in non-TLS | |
926 | mode, the fflush() happens when smtp_getc() is called. */ | |
927 | ||
928 | if (!tls_on_connect) | |
929 | { | |
930 | smtp_printf("220 TLS go ahead\r\n"); | |
931 | fflush(smtp_out); | |
932 | } | |
933 | ||
934 | /* Now negotiate the TLS session. We put our own timer on it, since it seems | |
935 | that the GnuTLS library doesn't. */ | |
936 | ||
56f5d9bd PH |
937 | gnutls_transport_set_ptr2(tls_session, (gnutls_transport_ptr)fileno(smtp_in), |
938 | (gnutls_transport_ptr)fileno(smtp_out)); | |
059ec3d9 PH |
939 | |
940 | sigalrm_seen = FALSE; | |
941 | if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout); | |
942 | rc = gnutls_handshake(tls_session); | |
943 | alarm(0); | |
944 | ||
945 | if (rc < 0) | |
946 | { | |
7199e1ee TF |
947 | tls_error(US"gnutls_handshake", NULL, |
948 | sigalrm_seen ? "timed out" : gnutls_strerror(rc)); | |
059ec3d9 PH |
949 | |
950 | /* It seems that, except in the case of a timeout, we have to close the | |
951 | connection right here; otherwise if the other end is running OpenSSL it hangs | |
952 | until the server times out. */ | |
953 | ||
954 | if (!sigalrm_seen) | |
955 | { | |
f1e894f3 PH |
956 | (void)fclose(smtp_out); |
957 | (void)fclose(smtp_in); | |
059ec3d9 PH |
958 | } |
959 | ||
960 | return FAIL; | |
961 | } | |
962 | ||
963 | DEBUG(D_tls) debug_printf("gnutls_handshake was successful\n"); | |
964 | ||
965 | if (verify_requirement != VERIFY_NONE && | |
966 | !verify_certificate(tls_session, &error)) | |
967 | { | |
7199e1ee | 968 | tls_error(US"certificate verification failed", NULL, error); |
059ec3d9 PH |
969 | return FAIL; |
970 | } | |
971 | ||
972 | construct_cipher_name(tls_session); | |
973 | ||
974 | /* TLS has been set up. Adjust the input functions to read via TLS, | |
975 | and initialize appropriately. */ | |
976 | ||
977 | ssl_xfer_buffer = store_malloc(ssl_xfer_buffer_size); | |
978 | ssl_xfer_buffer_lwm = ssl_xfer_buffer_hwm = 0; | |
979 | ssl_xfer_eof = ssl_xfer_error = 0; | |
980 | ||
981 | receive_getc = tls_getc; | |
982 | receive_ungetc = tls_ungetc; | |
983 | receive_feof = tls_feof; | |
984 | receive_ferror = tls_ferror; | |
58eb016e | 985 | receive_smtp_buffered = tls_smtp_buffered; |
059ec3d9 PH |
986 | |
987 | tls_active = fileno(smtp_out); | |
988 | ||
989 | return OK; | |
990 | } | |
991 | ||
992 | ||
993 | ||
994 | ||
995 | /************************************************* | |
996 | * Start a TLS session in a client * | |
997 | *************************************************/ | |
998 | ||
999 | /* Called from the smtp transport after STARTTLS has been accepted. | |
1000 | ||
1001 | Arguments: | |
1002 | fd the fd of the connection | |
1003 | host connected host (for messages) | |
83da1223 | 1004 | addr the first address (not used) |
059ec3d9 PH |
1005 | dhparam DH parameter file |
1006 | certificate certificate file | |
1007 | privatekey private key file | |
1008 | verify_certs file for certificate verify | |
1009 | verify_crl CRL for verify | |
83da1223 PH |
1010 | require_ciphers list of allowed ciphers or NULL |
1011 | require_mac list of allowed MACs or NULL | |
1012 | require_kx list of allowed key_exchange methods or NULL | |
1013 | require_proto list of allowed protocols or NULL | |
059ec3d9 PH |
1014 | timeout startup timeout |
1015 | ||
1016 | Returns: OK/DEFER/FAIL (because using common functions), | |
1017 | but for a client, DEFER and FAIL have the same meaning | |
1018 | */ | |
1019 | ||
1020 | int | |
1021 | tls_client_start(int fd, host_item *host, address_item *addr, uschar *dhparam, | |
1022 | uschar *certificate, uschar *privatekey, uschar *verify_certs, | |
83da1223 PH |
1023 | uschar *verify_crl, uschar *require_ciphers, uschar *require_mac, |
1024 | uschar *require_kx, uschar *require_proto, int timeout) | |
059ec3d9 PH |
1025 | { |
1026 | const gnutls_datum *server_certs; | |
1027 | uschar *expciphers = NULL; | |
83da1223 PH |
1028 | uschar *expmac = NULL; |
1029 | uschar *expkx = NULL; | |
1030 | uschar *expproto = NULL; | |
7199e1ee | 1031 | const char *error; |
059ec3d9 PH |
1032 | unsigned int server_certs_size; |
1033 | int rc; | |
1034 | ||
1035 | DEBUG(D_tls) debug_printf("initializing GnuTLS as a client\n"); | |
1036 | ||
059ec3d9 PH |
1037 | verify_requirement = (verify_certs == NULL)? VERIFY_NONE : VERIFY_REQUIRED; |
1038 | rc = tls_init(host, certificate, privatekey, verify_certs, verify_crl); | |
1039 | if (rc != OK) return rc; | |
1040 | ||
83da1223 PH |
1041 | if (!expand_check(require_ciphers, US"tls_require_ciphers", &expciphers) || |
1042 | !expand_check(require_mac, US"gnutls_require_mac", &expmac) || | |
1043 | !expand_check(require_kx, US"gnutls_require_kx", &expkx) || | |
1044 | !expand_check(require_proto, US"gnutls_require_proto", &expproto)) | |
059ec3d9 PH |
1045 | return FAIL; |
1046 | ||
83da1223 PH |
1047 | tls_session = tls_session_init(GNUTLS_CLIENT, expciphers, expmac, expkx, |
1048 | expproto); | |
1049 | ||
059ec3d9 | 1050 | if (tls_session == NULL) |
7199e1ee TF |
1051 | return tls_error(US "tls_session_init", host, |
1052 | gnutls_strerror(GNUTLS_E_MEMORY_ERROR)); | |
059ec3d9 PH |
1053 | |
1054 | gnutls_transport_set_ptr(tls_session, (gnutls_transport_ptr)fd); | |
1055 | ||
1056 | /* There doesn't seem to be a built-in timeout on connection. */ | |
1057 | ||
1058 | sigalrm_seen = FALSE; | |
1059 | alarm(timeout); | |
1060 | rc = gnutls_handshake(tls_session); | |
1061 | alarm(0); | |
1062 | ||
1063 | if (rc < 0) | |
7199e1ee TF |
1064 | return tls_error(US "gnutls_handshake", host, |
1065 | sigalrm_seen ? "timed out" : gnutls_strerror(rc)); | |
059ec3d9 PH |
1066 | |
1067 | server_certs = gnutls_certificate_get_peers(tls_session, &server_certs_size); | |
1068 | ||
1069 | if (server_certs != NULL) | |
1070 | { | |
1071 | uschar buff[1024]; | |
1072 | gnutls_x509_crt gcert; | |
1073 | ||
1074 | gnutls_x509_crt_init(&gcert); | |
1075 | tls_peerdn = US"unknown"; | |
1076 | ||
1077 | if (gnutls_x509_crt_import(gcert, server_certs, GNUTLS_X509_FMT_DER) == 0) | |
1078 | { | |
1079 | size_t bufsize = sizeof(buff); | |
1080 | if (gnutls_x509_crt_get_dn(gcert, CS buff, &bufsize) >= 0) | |
1081 | tls_peerdn = string_copy_malloc(buff); | |
1082 | } | |
1083 | } | |
1084 | ||
1085 | /* Should we also verify the hostname here? */ | |
1086 | ||
1087 | if (verify_requirement != VERIFY_NONE && | |
1088 | !verify_certificate(tls_session, &error)) | |
7199e1ee | 1089 | return tls_error(US"certificate verification failed", host, error); |
059ec3d9 PH |
1090 | |
1091 | construct_cipher_name(tls_session); /* Sets tls_cipher */ | |
1092 | tls_active = fd; | |
1093 | return OK; | |
1094 | } | |
1095 | ||
1096 | ||
1097 | ||
1098 | /************************************************* | |
1099 | * Deal with logging errors during I/O * | |
1100 | *************************************************/ | |
1101 | ||
1102 | /* We have to get the identity of the peer from saved data. | |
1103 | ||
1104 | Argument: | |
1105 | ec the GnuTLS error code, or 0 if it's a local error | |
1106 | when text identifying read or write | |
1107 | text local error text when ec is 0 | |
1108 | ||
1109 | Returns: nothing | |
1110 | */ | |
1111 | ||
1112 | static void | |
1113 | record_io_error(int ec, uschar *when, uschar *text) | |
1114 | { | |
7199e1ee | 1115 | const char *msg; |
059ec3d9 PH |
1116 | |
1117 | if (ec == GNUTLS_E_FATAL_ALERT_RECEIVED) | |
7199e1ee | 1118 | msg = string_sprintf("%s: %s", gnutls_strerror(ec), |
059ec3d9 | 1119 | gnutls_alert_get_name(gnutls_alert_get(tls_session))); |
059ec3d9 | 1120 | else |
7199e1ee TF |
1121 | msg = gnutls_strerror(ec); |
1122 | ||
1123 | tls_error(when, client_host, msg); | |
059ec3d9 PH |
1124 | } |
1125 | ||
1126 | ||
1127 | ||
1128 | /************************************************* | |
1129 | * TLS version of getc * | |
1130 | *************************************************/ | |
1131 | ||
1132 | /* This gets the next byte from the TLS input buffer. If the buffer is empty, | |
1133 | it refills the buffer via the GnuTLS reading function. | |
1134 | ||
1135 | Arguments: none | |
1136 | Returns: the next character or EOF | |
1137 | */ | |
1138 | ||
1139 | int | |
1140 | tls_getc(void) | |
1141 | { | |
1142 | if (ssl_xfer_buffer_lwm >= ssl_xfer_buffer_hwm) | |
1143 | { | |
1144 | int inbytes; | |
1145 | ||
1146 | DEBUG(D_tls) debug_printf("Calling gnutls_record_recv(%lx, %lx, %u)\n", | |
1147 | (long) tls_session, (long) ssl_xfer_buffer, ssl_xfer_buffer_size); | |
1148 | ||
1149 | if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout); | |
1150 | inbytes = gnutls_record_recv(tls_session, CS ssl_xfer_buffer, | |
1151 | ssl_xfer_buffer_size); | |
1152 | alarm(0); | |
1153 | ||
1154 | /* A zero-byte return appears to mean that the TLS session has been | |
1155 | closed down, not that the socket itself has been closed down. Revert to | |
1156 | non-TLS handling. */ | |
1157 | ||
1158 | if (inbytes == 0) | |
1159 | { | |
1160 | DEBUG(D_tls) debug_printf("Got TLS_EOF\n"); | |
1161 | ||
1162 | receive_getc = smtp_getc; | |
1163 | receive_ungetc = smtp_ungetc; | |
1164 | receive_feof = smtp_feof; | |
1165 | receive_ferror = smtp_ferror; | |
58eb016e | 1166 | receive_smtp_buffered = smtp_buffered; |
059ec3d9 PH |
1167 | |
1168 | gnutls_deinit(tls_session); | |
1169 | tls_session = NULL; | |
1170 | tls_active = -1; | |
1171 | tls_cipher = NULL; | |
1172 | tls_peerdn = NULL; | |
1173 | ||
1174 | return smtp_getc(); | |
1175 | } | |
1176 | ||
1177 | /* Handle genuine errors */ | |
1178 | ||
1179 | else if (inbytes < 0) | |
1180 | { | |
1181 | record_io_error(inbytes, US"recv", NULL); | |
1182 | ssl_xfer_error = 1; | |
1183 | return EOF; | |
1184 | } | |
80a47a2c TK |
1185 | #ifndef DISABLE_DKIM |
1186 | dkim_exim_verify_feed(ssl_xfer_buffer, inbytes); | |
1187 | #endif | |
059ec3d9 PH |
1188 | ssl_xfer_buffer_hwm = inbytes; |
1189 | ssl_xfer_buffer_lwm = 0; | |
1190 | } | |
1191 | ||
1192 | ||
1193 | /* Something in the buffer; return next uschar */ | |
1194 | ||
1195 | return ssl_xfer_buffer[ssl_xfer_buffer_lwm++]; | |
1196 | } | |
1197 | ||
1198 | ||
1199 | ||
1200 | /************************************************* | |
1201 | * Read bytes from TLS channel * | |
1202 | *************************************************/ | |
1203 | ||
1204 | /* | |
1205 | Arguments: | |
1206 | buff buffer of data | |
1207 | len size of buffer | |
1208 | ||
1209 | Returns: the number of bytes read | |
1210 | -1 after a failed read | |
1211 | */ | |
1212 | ||
1213 | int | |
1214 | tls_read(uschar *buff, size_t len) | |
1215 | { | |
1216 | int inbytes; | |
1217 | ||
1218 | DEBUG(D_tls) debug_printf("Calling gnutls_record_recv(%lx, %lx, %u)\n", | |
1219 | (long) tls_session, (long) buff, len); | |
1220 | ||
1221 | inbytes = gnutls_record_recv(tls_session, CS buff, len); | |
1222 | if (inbytes > 0) return inbytes; | |
1223 | if (inbytes == 0) | |
1224 | { | |
1225 | DEBUG(D_tls) debug_printf("Got TLS_EOF\n"); | |
1226 | } | |
1227 | else record_io_error(inbytes, US"recv", NULL); | |
1228 | ||
1229 | return -1; | |
1230 | } | |
1231 | ||
1232 | ||
1233 | ||
1234 | /************************************************* | |
1235 | * Write bytes down TLS channel * | |
1236 | *************************************************/ | |
1237 | ||
1238 | /* | |
1239 | Arguments: | |
1240 | buff buffer of data | |
1241 | len number of bytes | |
1242 | ||
1243 | Returns: the number of bytes after a successful write, | |
1244 | -1 after a failed write | |
1245 | */ | |
1246 | ||
1247 | int | |
1248 | tls_write(const uschar *buff, size_t len) | |
1249 | { | |
1250 | int outbytes; | |
1251 | int left = len; | |
1252 | ||
1253 | DEBUG(D_tls) debug_printf("tls_do_write(%lx, %d)\n", (long) buff, left); | |
1254 | while (left > 0) | |
1255 | { | |
1256 | DEBUG(D_tls) debug_printf("gnutls_record_send(SSL, %lx, %d)\n", (long)buff, | |
1257 | left); | |
1258 | outbytes = gnutls_record_send(tls_session, CS buff, left); | |
1259 | ||
1260 | DEBUG(D_tls) debug_printf("outbytes=%d\n", outbytes); | |
1261 | if (outbytes < 0) | |
1262 | { | |
1263 | record_io_error(outbytes, US"send", NULL); | |
1264 | return -1; | |
1265 | } | |
1266 | if (outbytes == 0) | |
1267 | { | |
1268 | record_io_error(0, US"send", US"TLS channel closed on write"); | |
1269 | return -1; | |
1270 | } | |
1271 | ||
1272 | left -= outbytes; | |
1273 | buff += outbytes; | |
1274 | } | |
1275 | ||
1276 | return len; | |
1277 | } | |
1278 | ||
1279 | ||
1280 | ||
1281 | /************************************************* | |
1282 | * Close down a TLS session * | |
1283 | *************************************************/ | |
1284 | ||
1285 | /* This is also called from within a delivery subprocess forked from the | |
1286 | daemon, to shut down the TLS library, without actually doing a shutdown (which | |
1287 | would tamper with the TLS session in the parent process). | |
1288 | ||
1289 | Arguments: TRUE if gnutls_bye is to be called | |
1290 | Returns: nothing | |
1291 | */ | |
1292 | ||
1293 | void | |
1294 | tls_close(BOOL shutdown) | |
1295 | { | |
1296 | if (tls_active < 0) return; /* TLS was not active */ | |
1297 | ||
1298 | if (shutdown) | |
1299 | { | |
1300 | DEBUG(D_tls) debug_printf("tls_close(): shutting down TLS\n"); | |
1301 | gnutls_bye(tls_session, GNUTLS_SHUT_WR); | |
1302 | } | |
1303 | ||
1304 | gnutls_deinit(tls_session); | |
1305 | tls_session = NULL; | |
1306 | gnutls_global_deinit(); | |
1307 | ||
1308 | tls_active = -1; | |
1309 | } | |
1310 | ||
36f12725 NM |
1311 | |
1312 | ||
1313 | ||
1314 | /************************************************* | |
1315 | * Report the library versions. * | |
1316 | *************************************************/ | |
1317 | ||
1318 | /* See a description in tls-openssl.c for an explanation of why this exists. | |
1319 | ||
1320 | Arguments: a FILE* to print the results to | |
1321 | Returns: nothing | |
1322 | */ | |
1323 | ||
1324 | void | |
1325 | tls_version_report(FILE *f) | |
1326 | { | |
754a0503 PP |
1327 | fprintf(f, "Library version: GnuTLS: Compile: %s\n" |
1328 | " Runtime: %s\n", | |
1329 | LIBGNUTLS_VERSION, | |
1330 | gnutls_check_version(NULL)); | |
36f12725 NM |
1331 | } |
1332 | ||
059ec3d9 | 1333 | /* End of tls-gnu.c */ |