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0a49a7a4 | 1 | /* $Cambridge: exim/src/src/tls-gnu.c,v 1.24 2009/11/16 19:50:37 nm4 Exp $ */ |
059ec3d9 PH |
2 | |
3 | /************************************************* | |
4 | * Exim - an Internet mail transport agent * | |
5 | *************************************************/ | |
6 | ||
0a49a7a4 | 7 | /* Copyright (c) University of Cambridge 1995 - 2009 */ |
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 | 28 | |
7199e1ee | 29 | /* Values for verify_requirment */ |
059ec3d9 PH |
30 | |
31 | enum { VERIFY_NONE, VERIFY_OPTIONAL, VERIFY_REQUIRED }; | |
059ec3d9 PH |
32 | |
33 | /* Local static variables for GNUTLS */ | |
34 | ||
059ec3d9 PH |
35 | static host_item *client_host; |
36 | ||
059ec3d9 PH |
37 | static gnutls_dh_params dh_params = NULL; |
38 | ||
39 | static gnutls_certificate_server_credentials x509_cred = NULL; | |
40 | static gnutls_session tls_session = NULL; | |
41 | ||
42 | static char ssl_errstring[256]; | |
43 | ||
44 | static int ssl_session_timeout = 200; | |
45 | static int verify_requirement; | |
46 | ||
83da1223 PH |
47 | /* Priorities for TLS algorithms to use. In each case there's a default table, |
48 | and space into which it can be copied and altered. */ | |
059ec3d9 | 49 | |
83da1223 PH |
50 | static const int default_proto_priority[16] = { |
51 | GNUTLS_TLS1, | |
52 | GNUTLS_SSL3, | |
53 | 0 }; | |
54 | ||
55 | static int proto_priority[16]; | |
059ec3d9 | 56 | |
83da1223 | 57 | static const int default_kx_priority[16] = { |
059ec3d9 PH |
58 | GNUTLS_KX_RSA, |
59 | GNUTLS_KX_DHE_DSS, | |
60 | GNUTLS_KX_DHE_RSA, | |
059ec3d9 PH |
61 | 0 }; |
62 | ||
83da1223 PH |
63 | static int kx_priority[16]; |
64 | ||
059ec3d9 | 65 | static int default_cipher_priority[16] = { |
26dd5a95 | 66 | GNUTLS_CIPHER_AES_256_CBC, |
059ec3d9 PH |
67 | GNUTLS_CIPHER_AES_128_CBC, |
68 | GNUTLS_CIPHER_3DES_CBC, | |
26dd5a95 | 69 | GNUTLS_CIPHER_ARCFOUR_128, |
059ec3d9 PH |
70 | 0 }; |
71 | ||
72 | static int cipher_priority[16]; | |
73 | ||
83da1223 | 74 | static const int default_mac_priority[16] = { |
059ec3d9 PH |
75 | GNUTLS_MAC_SHA, |
76 | GNUTLS_MAC_MD5, | |
77 | 0 }; | |
78 | ||
83da1223 PH |
79 | static int mac_priority[16]; |
80 | ||
81 | /* These two are currently not changeable. */ | |
82 | ||
059ec3d9 PH |
83 | static const int comp_priority[16] = { GNUTLS_COMP_NULL, 0 }; |
84 | static const int cert_type_priority[16] = { GNUTLS_CRT_X509, 0 }; | |
85 | ||
83da1223 | 86 | /* Tables of priority names and equivalent numbers */ |
059ec3d9 PH |
87 | |
88 | typedef struct pri_item { | |
89 | uschar *name; | |
90 | int *values; | |
91 | } pri_item; | |
92 | ||
83da1223 PH |
93 | |
94 | static int tls1_codes[] = { GNUTLS_TLS1, 0 }; | |
95 | static int ssl3_codes[] = { GNUTLS_SSL3, 0 }; | |
96 | ||
97 | static pri_item proto_index[] = { | |
98 | { US"TLS1", tls1_codes }, | |
99 | { US"SSL3", ssl3_codes } | |
100 | }; | |
101 | ||
102 | ||
103 | static int kx_rsa_codes[] = { GNUTLS_KX_RSA, | |
104 | GNUTLS_KX_DHE_RSA, 0 }; | |
105 | static int kx_dhe_codes[] = { GNUTLS_KX_DHE_DSS, | |
106 | GNUTLS_KX_DHE_RSA, 0 }; | |
107 | static int kx_dhe_dss_codes[] = { GNUTLS_KX_DHE_DSS, 0 }; | |
108 | static int kx_dhe_rsa_codes[] = { GNUTLS_KX_DHE_RSA, 0 }; | |
109 | ||
110 | static pri_item kx_index[] = { | |
111 | { US"DHE_DSS", kx_dhe_dss_codes }, | |
112 | { US"DHE_RSA", kx_dhe_rsa_codes }, | |
113 | { US"RSA", kx_rsa_codes }, | |
114 | { US"DHE", kx_dhe_codes } | |
115 | }; | |
116 | ||
117 | ||
059ec3d9 PH |
118 | static int arcfour_128_codes[] = { GNUTLS_CIPHER_ARCFOUR_128, 0 }; |
119 | static int arcfour_40_codes[] = { GNUTLS_CIPHER_ARCFOUR_40, 0 }; | |
120 | static int arcfour_codes[] = { GNUTLS_CIPHER_ARCFOUR_128, | |
121 | GNUTLS_CIPHER_ARCFOUR_40, 0 }; | |
122 | static int aes_256_codes[] = { GNUTLS_CIPHER_AES_256_CBC, 0 }; | |
123 | static int aes_128_codes[] = { GNUTLS_CIPHER_AES_128_CBC, 0 }; | |
124 | static int aes_codes[] = { GNUTLS_CIPHER_AES_256_CBC, | |
125 | GNUTLS_CIPHER_AES_128_CBC, 0 }; | |
126 | static int des3_codes[] = { GNUTLS_CIPHER_3DES_CBC, 0 }; | |
127 | ||
128 | static pri_item cipher_index[] = { | |
129 | { US"ARCFOUR_128", arcfour_128_codes }, | |
130 | { US"ARCFOUR_40", arcfour_40_codes }, | |
131 | { US"ARCFOUR", arcfour_codes }, | |
132 | { US"AES_256", aes_256_codes }, | |
133 | { US"AES_128", aes_128_codes }, | |
134 | { US"AES", aes_codes }, | |
135 | { US"3DES", des3_codes } | |
136 | }; | |
137 | ||
138 | ||
83da1223 PH |
139 | static int mac_sha_codes[] = { GNUTLS_MAC_SHA, 0 }; |
140 | static int mac_md5_codes[] = { GNUTLS_MAC_MD5, 0 }; | |
141 | ||
142 | static pri_item mac_index[] = { | |
143 | { US"SHA", mac_sha_codes }, | |
144 | { US"SHA1", mac_sha_codes }, | |
145 | { US"MD5", mac_md5_codes } | |
146 | }; | |
147 | ||
148 | ||
059ec3d9 PH |
149 | |
150 | /************************************************* | |
151 | * Handle TLS error * | |
152 | *************************************************/ | |
153 | ||
154 | /* Called from lots of places when errors occur before actually starting to do | |
155 | the TLS handshake, that is, while the session is still in clear. Always returns | |
156 | DEFER for a server and FAIL for a client so that most calls can use "return | |
157 | tls_error(...)" to do this processing and then give an appropriate return. A | |
158 | single function is used for both server and client, because it is called from | |
159 | some shared functions. | |
160 | ||
161 | Argument: | |
162 | prefix text to include in the logged error | |
163 | host NULL if setting up a server; | |
164 | the connected host if setting up a client | |
7199e1ee TF |
165 | msg additional error string (may be NULL) |
166 | usually obtained from gnutls_strerror() | |
059ec3d9 PH |
167 | |
168 | Returns: OK/DEFER/FAIL | |
169 | */ | |
170 | ||
171 | static int | |
7199e1ee | 172 | tls_error(uschar *prefix, host_item *host, const char *msg) |
059ec3d9 | 173 | { |
059ec3d9 PH |
174 | if (host == NULL) |
175 | { | |
7199e1ee TF |
176 | uschar *conn_info = smtp_get_connection_info(); |
177 | if (strncmp(conn_info, "SMTP ", 5) == 0) | |
178 | conn_info += 5; | |
179 | log_write(0, LOG_MAIN, "TLS error on %s (%s)%s%s", | |
180 | conn_info, prefix, msg ? ": " : "", msg ? msg : ""); | |
059ec3d9 PH |
181 | return DEFER; |
182 | } | |
183 | else | |
184 | { | |
7199e1ee TF |
185 | log_write(0, LOG_MAIN, "TLS error on connection to %s [%s] (%s)%s%s", |
186 | host->name, host->address, prefix, msg ? ": " : "", msg ? msg : ""); | |
059ec3d9 PH |
187 | return FAIL; |
188 | } | |
189 | } | |
190 | ||
191 | ||
192 | ||
193 | /************************************************* | |
194 | * Verify certificate * | |
195 | *************************************************/ | |
196 | ||
197 | /* Called after a successful handshake, when certificate verification is | |
198 | required or optional, for both server and client. | |
199 | ||
200 | Arguments: | |
201 | session GNUTLS session | |
202 | error where to put text giving a reason for failure | |
203 | ||
204 | Returns: TRUE/FALSE | |
205 | */ | |
206 | ||
207 | static BOOL | |
7199e1ee | 208 | verify_certificate(gnutls_session session, const char **error) |
059ec3d9 PH |
209 | { |
210 | int verify; | |
211 | uschar *dn_string = US""; | |
212 | const gnutls_datum *cert; | |
213 | unsigned int cert_size = 0; | |
214 | ||
215 | *error = NULL; | |
216 | ||
217 | /* Get the peer's certificate. If it sent one, extract it's DN, and then | |
218 | attempt to verify the certificate. If no certificate is supplied, verification | |
219 | is forced to fail. */ | |
220 | ||
221 | cert = gnutls_certificate_get_peers(session, &cert_size); | |
222 | if (cert != NULL) | |
223 | { | |
224 | uschar buff[1024]; | |
225 | gnutls_x509_crt gcert; | |
226 | ||
227 | gnutls_x509_crt_init(&gcert); | |
228 | dn_string = US"unknown"; | |
229 | ||
230 | if (gnutls_x509_crt_import(gcert, cert, GNUTLS_X509_FMT_DER) == 0) | |
231 | { | |
232 | size_t bufsize = sizeof(buff); | |
233 | if (gnutls_x509_crt_get_dn(gcert, CS buff, &bufsize) >= 0) | |
234 | dn_string = string_copy_malloc(buff); | |
235 | } | |
236 | ||
237 | verify = gnutls_certificate_verify_peers(session); | |
238 | } | |
239 | else | |
240 | { | |
241 | DEBUG(D_tls) debug_printf("no peer certificate supplied\n"); | |
242 | verify = GNUTLS_CERT_INVALID; | |
7199e1ee | 243 | *error = "not supplied"; |
059ec3d9 PH |
244 | } |
245 | ||
246 | /* Handle the result of verification. INVALID seems to be set as well | |
247 | as REVOKED, but leave the test for both. */ | |
248 | ||
249 | if ((verify & (GNUTLS_CERT_INVALID|GNUTLS_CERT_REVOKED)) != 0) | |
250 | { | |
251 | tls_certificate_verified = FALSE; | |
252 | if (*error == NULL) *error = ((verify & GNUTLS_CERT_REVOKED) != 0)? | |
7199e1ee | 253 | "revoked" : "invalid"; |
059ec3d9 PH |
254 | if (verify_requirement == VERIFY_REQUIRED) |
255 | { | |
256 | DEBUG(D_tls) debug_printf("TLS certificate verification failed (%s): " | |
257 | "peerdn=%s\n", *error, dn_string); | |
258 | gnutls_alert_send(session, GNUTLS_AL_FATAL, GNUTLS_A_BAD_CERTIFICATE); | |
259 | return FALSE; /* reject */ | |
260 | } | |
261 | DEBUG(D_tls) debug_printf("TLS certificate verify failure (%s) overridden " | |
262 | "(host in tls_try_verify_hosts): peerdn=%s\n", *error, dn_string); | |
263 | } | |
264 | else | |
265 | { | |
266 | tls_certificate_verified = TRUE; | |
267 | DEBUG(D_tls) debug_printf("TLS certificate verified: peerdn=%s\n", | |
268 | dn_string); | |
269 | } | |
270 | ||
271 | tls_peerdn = dn_string; | |
272 | return TRUE; /* accept */ | |
273 | } | |
274 | ||
275 | ||
276 | ||
059ec3d9 | 277 | /************************************************* |
575643cd | 278 | * Setup up DH parameters * |
059ec3d9 PH |
279 | *************************************************/ |
280 | ||
575643cd | 281 | /* Generating the D-H parameters may take a long time. They only need to |
059ec3d9 PH |
282 | be re-generated every so often, depending on security policy. What we do is to |
283 | keep these parameters in a file in the spool directory. If the file does not | |
284 | exist, we generate them. This means that it is easy to cause a regeneration. | |
285 | ||
286 | The new file is written as a temporary file and renamed, so that an incomplete | |
287 | file is never present. If two processes both compute some new parameters, you | |
288 | waste a bit of effort, but it doesn't seem worth messing around with locking to | |
289 | prevent this. | |
290 | ||
291 | Argument: | |
292 | host NULL for server, server for client (for error handling) | |
293 | ||
294 | Returns: OK/DEFER/FAIL | |
295 | */ | |
296 | ||
297 | static int | |
575643cd | 298 | init_dh(host_item *host) |
059ec3d9 | 299 | { |
b5aea5e1 | 300 | int fd; |
182ad5cf | 301 | int ret; |
b5aea5e1 | 302 | gnutls_datum m; |
059ec3d9 PH |
303 | uschar filename[200]; |
304 | ||
305 | /* Initialize the data structures for holding the parameters */ | |
306 | ||
059ec3d9 | 307 | ret = gnutls_dh_params_init(&dh_params); |
7199e1ee | 308 | if (ret < 0) return tls_error(US"init dh_params", host, gnutls_strerror(ret)); |
059ec3d9 PH |
309 | |
310 | /* Set up the name of the cache file */ | |
311 | ||
312 | if (!string_format(filename, sizeof(filename), "%s/gnutls-params", | |
313 | spool_directory)) | |
7199e1ee | 314 | return tls_error(US"overlong filename", host, NULL); |
059ec3d9 | 315 | |
b5aea5e1 | 316 | /* Open the cache file for reading and if successful, read it and set up the |
575643cd | 317 | parameters. */ |
059ec3d9 PH |
318 | |
319 | fd = Uopen(filename, O_RDONLY, 0); | |
b5aea5e1 | 320 | if (fd >= 0) |
059ec3d9 | 321 | { |
b5aea5e1 PH |
322 | struct stat statbuf; |
323 | if (fstat(fd, &statbuf) < 0) | |
324 | { | |
325 | (void)close(fd); | |
7199e1ee | 326 | return tls_error(US"TLS cache stat failed", host, strerror(errno)); |
b5aea5e1 | 327 | } |
059ec3d9 | 328 | |
b5aea5e1 PH |
329 | m.size = statbuf.st_size; |
330 | m.data = malloc(m.size); | |
331 | if (m.data == NULL) | |
7199e1ee TF |
332 | return tls_error(US"memory allocation failed", host, strerror(errno)); |
333 | errno = 0; | |
b5aea5e1 | 334 | if (read(fd, m.data, m.size) != m.size) |
7199e1ee | 335 | return tls_error(US"TLS cache read failed", host, strerror(errno)); |
b5aea5e1 PH |
336 | (void)close(fd); |
337 | ||
411ef850 | 338 | ret = gnutls_dh_params_import_pkcs3(dh_params, &m, GNUTLS_X509_FMT_PEM); |
7199e1ee TF |
339 | if (ret < 0) |
340 | return tls_error(US"DH params import", host, gnutls_strerror(ret)); | |
575643cd | 341 | DEBUG(D_tls) debug_printf("read D-H parameters from file\n"); |
b5aea5e1 PH |
342 | |
343 | free(m.data); | |
344 | } | |
345 | ||
346 | /* If the file does not exist, fall through to compute new data and cache it. | |
347 | If there was any other opening error, it is serious. */ | |
348 | ||
182ad5cf PH |
349 | else if (errno == ENOENT) |
350 | { | |
351 | ret = -1; | |
352 | DEBUG(D_tls) | |
353 | debug_printf("parameter cache file %s does not exist\n", filename); | |
354 | } | |
355 | else | |
b5aea5e1 | 356 | return tls_error(string_open_failed(errno, "%s for reading", filename), |
7199e1ee | 357 | host, NULL); |
b5aea5e1 PH |
358 | |
359 | /* If ret < 0, either the cache file does not exist, or the data it contains | |
360 | is not useful. One particular case of this is when upgrading from an older | |
361 | release of Exim in which the data was stored in a different format. We don't | |
362 | try to be clever and support both formats; we just regenerate new data in this | |
363 | case. */ | |
364 | ||
365 | if (ret < 0) | |
366 | { | |
367 | uschar tempfilename[sizeof(filename) + 10]; | |
059ec3d9 | 368 | |
059ec3d9 PH |
369 | DEBUG(D_tls) debug_printf("generating %d bit Diffie-Hellman key...\n", |
370 | DH_BITS); | |
371 | ret = gnutls_dh_params_generate2(dh_params, DH_BITS); | |
7199e1ee | 372 | if (ret < 0) return tls_error(US"D-H key generation", host, gnutls_strerror(ret)); |
059ec3d9 PH |
373 | |
374 | /* Write the parameters to a file in the spool directory so that we | |
375 | can use them from other Exim processes. */ | |
376 | ||
377 | sprintf(CS tempfilename, "%s-%d", filename, (int)getpid()); | |
378 | fd = Uopen(tempfilename, O_WRONLY|O_CREAT, 0400); | |
379 | if (fd < 0) | |
380 | return tls_error(string_open_failed(errno, "%s for writing", filename), | |
7199e1ee | 381 | host, NULL); |
059ec3d9 PH |
382 | (void)fchown(fd, exim_uid, exim_gid); /* Probably not necessary */ |
383 | ||
b5aea5e1 PH |
384 | /* export the parameters in a format that can be generated using GNUTLS' |
385 | * certtool or other programs. | |
386 | * | |
387 | * The commands for certtool are: | |
411ef850 | 388 | * $ certtool --generate-dh-params --bits 1024 > params |
b5aea5e1 PH |
389 | */ |
390 | ||
391 | m.size = PARAM_SIZE; | |
392 | m.data = malloc(m.size); | |
393 | if (m.data == NULL) | |
7199e1ee | 394 | return tls_error(US"memory allocation failed", host, strerror(errno)); |
b5aea5e1 | 395 | |
b5aea5e1 PH |
396 | m.size = PARAM_SIZE; |
397 | ret = gnutls_dh_params_export_pkcs3(dh_params, GNUTLS_X509_FMT_PEM, m.data, | |
398 | &m.size); | |
7199e1ee TF |
399 | if (ret < 0) |
400 | return tls_error(US"DH params export", host, gnutls_strerror(ret)); | |
059ec3d9 | 401 | |
b5aea5e1 | 402 | m.size = Ustrlen(m.data); |
7199e1ee | 403 | errno = 0; |
b5aea5e1 | 404 | if (write(fd, m.data, m.size) != m.size || write(fd, "\n", 1) != 1) |
7199e1ee | 405 | return tls_error(US"TLS cache write failed", host, strerror(errno)); |
059ec3d9 | 406 | |
b5aea5e1 | 407 | free(m.data); |
059ec3d9 PH |
408 | (void)close(fd); |
409 | ||
410 | if (rename(CS tempfilename, CS filename) < 0) | |
7199e1ee TF |
411 | return tls_error(string_sprintf("failed to rename %s as %s", |
412 | tempfilename, filename), host, strerror(errno)); | |
059ec3d9 | 413 | |
411ef850 | 414 | DEBUG(D_tls) debug_printf("wrote D-H parameters to file %s\n", filename); |
059ec3d9 PH |
415 | } |
416 | ||
411ef850 | 417 | DEBUG(D_tls) debug_printf("initialized D-H parameters\n"); |
059ec3d9 PH |
418 | return OK; |
419 | } | |
420 | ||
421 | ||
422 | ||
423 | ||
424 | /************************************************* | |
425 | * Initialize for GnuTLS * | |
426 | *************************************************/ | |
427 | ||
428 | /* Called from both server and client code. In the case of a server, errors | |
429 | before actual TLS negotiation return DEFER. | |
430 | ||
431 | Arguments: | |
432 | host connected host, if client; NULL if server | |
433 | certificate certificate file | |
434 | privatekey private key file | |
435 | cas CA certs file | |
436 | crl CRL file | |
437 | ||
438 | Returns: OK/DEFER/FAIL | |
439 | */ | |
440 | ||
441 | static int | |
442 | tls_init(host_item *host, uschar *certificate, uschar *privatekey, uschar *cas, | |
443 | uschar *crl) | |
444 | { | |
445 | int rc; | |
446 | uschar *cert_expanded, *key_expanded, *cas_expanded, *crl_expanded; | |
447 | ||
7199e1ee | 448 | client_host = host; |
059ec3d9 PH |
449 | |
450 | rc = gnutls_global_init(); | |
7199e1ee | 451 | if (rc < 0) return tls_error(US"tls-init", host, gnutls_strerror(rc)); |
059ec3d9 | 452 | |
575643cd PH |
453 | /* Create D-H parameters, or read them from the cache file. This function does |
454 | its own SMTP error messaging. */ | |
059ec3d9 | 455 | |
575643cd | 456 | rc = init_dh(host); |
059ec3d9 PH |
457 | if (rc != OK) return rc; |
458 | ||
459 | /* Create the credentials structure */ | |
460 | ||
461 | rc = gnutls_certificate_allocate_credentials(&x509_cred); | |
7199e1ee TF |
462 | if (rc < 0) |
463 | return tls_error(US"certificate_allocate_credentials", | |
464 | host, gnutls_strerror(rc)); | |
059ec3d9 PH |
465 | |
466 | /* This stuff must be done for each session, because different certificates | |
467 | may be required for different sessions. */ | |
468 | ||
469 | if (!expand_check(certificate, US"tls_certificate", &cert_expanded)) | |
470 | return DEFER; | |
471 | ||
c91535f3 | 472 | key_expanded = NULL; |
059ec3d9 PH |
473 | if (privatekey != NULL) |
474 | { | |
475 | if (!expand_check(privatekey, US"tls_privatekey", &key_expanded)) | |
476 | return DEFER; | |
477 | } | |
c91535f3 PH |
478 | |
479 | /* If expansion was forced to fail, key_expanded will be NULL. If the result of | |
480 | the expansion is an empty string, ignore it also, and assume that the private | |
481 | key is in the same file as the certificate. */ | |
482 | ||
483 | if (key_expanded == NULL || *key_expanded == 0) | |
484 | key_expanded = cert_expanded; | |
059ec3d9 PH |
485 | |
486 | /* Set the certificate and private keys */ | |
487 | ||
488 | if (cert_expanded != NULL) | |
489 | { | |
490 | DEBUG(D_tls) debug_printf("certificate file = %s\nkey file = %s\n", | |
491 | cert_expanded, key_expanded); | |
492 | rc = gnutls_certificate_set_x509_key_file(x509_cred, CS cert_expanded, | |
493 | CS key_expanded, GNUTLS_X509_FMT_PEM); | |
8e669ac1 | 494 | if (rc < 0) |
de365ded PH |
495 | { |
496 | uschar *msg = string_sprintf("cert/key setup: cert=%s key=%s", | |
8e669ac1 | 497 | cert_expanded, key_expanded); |
7199e1ee | 498 | return tls_error(msg, host, gnutls_strerror(rc)); |
8e669ac1 | 499 | } |
059ec3d9 PH |
500 | } |
501 | ||
502 | /* A certificate is mandatory in a server, but not in a client */ | |
503 | ||
504 | else | |
505 | { | |
506 | if (host == NULL) | |
7199e1ee | 507 | return tls_error(US"no TLS server certificate is specified", NULL, NULL); |
059ec3d9 PH |
508 | DEBUG(D_tls) debug_printf("no TLS client certificate is specified\n"); |
509 | } | |
510 | ||
511 | /* Set the trusted CAs file if one is provided, and then add the CRL if one is | |
512 | provided. Experiment shows that, if the certificate file is empty, an unhelpful | |
513 | error message is provided. However, if we just refrain from setting anything up | |
514 | in that case, certificate verification fails, which seems to be the correct | |
515 | behaviour. */ | |
516 | ||
517 | if (cas != NULL) | |
518 | { | |
519 | struct stat statbuf; | |
520 | ||
521 | if (!expand_check(cas, US"tls_verify_certificates", &cas_expanded)) | |
522 | return DEFER; | |
523 | ||
524 | if (stat(CS cas_expanded, &statbuf) < 0) | |
525 | { | |
526 | log_write(0, LOG_MAIN|LOG_PANIC, "could not stat %s " | |
527 | "(tls_verify_certificates): %s", cas_expanded, strerror(errno)); | |
528 | return DEFER; | |
529 | } | |
530 | ||
b1c749bb PH |
531 | DEBUG(D_tls) debug_printf("verify certificates = %s size=" OFF_T_FMT "\n", |
532 | cas_expanded, statbuf.st_size); | |
059ec3d9 PH |
533 | |
534 | /* If the cert file is empty, there's no point in loading the CRL file. */ | |
535 | ||
536 | if (statbuf.st_size > 0) | |
537 | { | |
538 | rc = gnutls_certificate_set_x509_trust_file(x509_cred, CS cas_expanded, | |
539 | GNUTLS_X509_FMT_PEM); | |
7199e1ee | 540 | if (rc < 0) return tls_error(US"setup_certs", host, gnutls_strerror(rc)); |
059ec3d9 PH |
541 | |
542 | if (crl != NULL && *crl != 0) | |
543 | { | |
544 | if (!expand_check(crl, US"tls_crl", &crl_expanded)) | |
545 | return DEFER; | |
546 | DEBUG(D_tls) debug_printf("loading CRL file = %s\n", crl_expanded); | |
547 | rc = gnutls_certificate_set_x509_crl_file(x509_cred, CS crl_expanded, | |
548 | GNUTLS_X509_FMT_PEM); | |
7199e1ee | 549 | if (rc < 0) return tls_error(US"CRL setup", host, gnutls_strerror(rc)); |
059ec3d9 PH |
550 | } |
551 | } | |
552 | } | |
553 | ||
554 | /* Associate the parameters with the x509 credentials structure. */ | |
555 | ||
556 | gnutls_certificate_set_dh_params(x509_cred, dh_params); | |
059ec3d9 PH |
557 | |
558 | DEBUG(D_tls) debug_printf("initialized certificate stuff\n"); | |
559 | return OK; | |
560 | } | |
561 | ||
562 | ||
563 | ||
564 | ||
565 | /************************************************* | |
83da1223 | 566 | * Remove from a priority list * |
059ec3d9 PH |
567 | *************************************************/ |
568 | ||
569 | /* Cautiously written so that it will remove duplicates if present. | |
570 | ||
571 | Arguments: | |
572 | list a zero-terminated list | |
573 | remove_list a zero-terminated list to be removed | |
574 | ||
575 | Returns: nothing | |
576 | */ | |
577 | ||
578 | static void | |
83da1223 | 579 | remove_priority(int *list, int *remove_list) |
059ec3d9 PH |
580 | { |
581 | for (; *remove_list != 0; remove_list++) | |
582 | { | |
583 | int *p = list; | |
584 | while (*p != 0) | |
585 | { | |
586 | if (*p == *remove_list) | |
587 | { | |
588 | int *pp = p; | |
589 | do { pp[0] = pp[1]; pp++; } while (*pp != 0); | |
590 | } | |
591 | else p++; | |
592 | } | |
593 | } | |
594 | } | |
595 | ||
596 | ||
597 | ||
598 | /************************************************* | |
83da1223 | 599 | * Add to a priority list * |
059ec3d9 PH |
600 | *************************************************/ |
601 | ||
602 | /* Cautiously written to check the list size | |
603 | ||
604 | Arguments: | |
605 | list a zero-terminated list | |
606 | list_max maximum offset in the list | |
607 | add_list a zero-terminated list to be added | |
608 | ||
609 | Returns: TRUE if OK; FALSE if list overflows | |
610 | */ | |
611 | ||
612 | static BOOL | |
83da1223 | 613 | add_priority(int *list, int list_max, int *add_list) |
059ec3d9 PH |
614 | { |
615 | int next = 0; | |
616 | while (list[next] != 0) next++; | |
617 | while (*add_list != 0) | |
618 | { | |
619 | if (next >= list_max) return FALSE; | |
620 | list[next++] = *add_list++; | |
621 | } | |
622 | list[next] = 0; | |
623 | return TRUE; | |
624 | } | |
625 | ||
626 | ||
627 | ||
83da1223 PH |
628 | /************************************************* |
629 | * Adjust a priority list * | |
630 | *************************************************/ | |
631 | ||
632 | /* This function is called to adjust the lists of cipher algorithms, MAC | |
633 | algorithms, key-exchange methods, and protocols. | |
634 | ||
635 | Arguments: | |
636 | plist the appropriate priority list | |
637 | psize the length of the list | |
638 | s the configuation string | |
639 | index the index of recognized strings | |
640 | isize the length of the index | |
641 | ||
642 | ||
643 | which text for an error message | |
644 | ||
645 | Returns: FALSE if the table overflows, else TRUE | |
646 | */ | |
647 | ||
648 | static BOOL | |
649 | set_priority(int *plist, int psize, uschar *s, pri_item *index, int isize, | |
650 | uschar *which) | |
651 | { | |
652 | int sep = 0; | |
653 | BOOL first = TRUE; | |
654 | uschar *t; | |
655 | ||
656 | while ((t = string_nextinlist(&s, &sep, big_buffer, big_buffer_size)) != NULL) | |
657 | { | |
658 | int i; | |
659 | BOOL exclude = t[0] == '!'; | |
660 | if (first && !exclude) plist[0] = 0; | |
661 | first = FALSE; | |
662 | for (i = 0; i < isize; i++) | |
663 | { | |
664 | uschar *ss = strstric(t, index[i].name, FALSE); | |
665 | if (ss != NULL) | |
666 | { | |
667 | uschar *endss = ss + Ustrlen(index[i].name); | |
668 | if ((ss == t || !isalnum(ss[-1])) && !isalnum(*endss)) | |
669 | { | |
670 | if (exclude) | |
671 | remove_priority(plist, index[i].values); | |
672 | else | |
673 | { | |
674 | if (!add_priority(plist, psize, index[i].values)) | |
675 | { | |
676 | log_write(0, LOG_MAIN|LOG_PANIC, "GnuTLS init failed: %s " | |
677 | "priority table overflow", which); | |
678 | return FALSE; | |
679 | } | |
680 | } | |
681 | } | |
682 | } | |
683 | } | |
684 | } | |
685 | ||
686 | DEBUG(D_tls) | |
687 | { | |
688 | int *ptr = plist; | |
689 | debug_printf("adjusted %s priorities:", which); | |
690 | while (*ptr != 0) debug_printf(" %d", *ptr++); | |
691 | debug_printf("\n"); | |
692 | } | |
693 | ||
694 | return TRUE; | |
695 | } | |
696 | ||
697 | ||
698 | ||
699 | ||
059ec3d9 PH |
700 | /************************************************* |
701 | * Initialize a single GNUTLS session * | |
702 | *************************************************/ | |
703 | ||
704 | /* Set the algorithm, the db backend, whether to request certificates etc. | |
705 | ||
706 | TLS in Exim was first implemented using OpenSSL. This has a function to which | |
707 | you pass a list of cipher suites that are permitted/not permitted. GnuTLS works | |
708 | differently. It operates using priority lists for the different components of | |
709 | cipher suites. | |
710 | ||
711 | For compatibility of configuration, we scan a list of cipher suites and set | |
712 | priorities therefrom. However, at the moment, we pay attention only to the bulk | |
713 | cipher. | |
714 | ||
715 | Arguments: | |
716 | side one of GNUTLS_SERVER, GNUTLS_CLIENT | |
83da1223 PH |
717 | expciphers expanded ciphers list or NULL |
718 | expmac expanded MAC list or NULL | |
719 | expkx expanded key-exchange list or NULL | |
720 | expproto expanded protocol list or NULL | |
059ec3d9 PH |
721 | |
722 | Returns: a gnutls_session, or NULL if there is a problem | |
723 | */ | |
724 | ||
725 | static gnutls_session | |
83da1223 PH |
726 | tls_session_init(int side, uschar *expciphers, uschar *expmac, uschar *expkx, |
727 | uschar *expproto) | |
059ec3d9 PH |
728 | { |
729 | gnutls_session session; | |
730 | ||
731 | gnutls_init(&session, side); | |
732 | ||
83da1223 PH |
733 | /* Initialize the lists of permitted protocols, key-exchange methods, ciphers, |
734 | and MACs. */ | |
059ec3d9 PH |
735 | |
736 | memcpy(cipher_priority, default_cipher_priority, sizeof(cipher_priority)); | |
83da1223 PH |
737 | memcpy(mac_priority, default_mac_priority, sizeof(mac_priority)); |
738 | memcpy(kx_priority, default_kx_priority, sizeof(kx_priority)); | |
739 | memcpy(proto_priority, default_proto_priority, sizeof(proto_priority)); | |
740 | ||
741 | /* The names OpenSSL uses in tls_require_ciphers are of the form DES-CBC3-SHA, | |
742 | using hyphen separators. GnuTLS uses underscore separators. So that I can use | |
743 | either form for tls_require_ciphers in my tests, and also for general | |
744 | convenience, we turn hyphens into underscores before scanning the list. */ | |
059ec3d9 PH |
745 | |
746 | if (expciphers != NULL) | |
747 | { | |
059ec3d9 PH |
748 | uschar *s = expciphers; |
749 | while (*s != 0) { if (*s == '-') *s = '_'; s++; } | |
83da1223 | 750 | } |
059ec3d9 | 751 | |
83da1223 PH |
752 | if ((expciphers != NULL && |
753 | !set_priority(cipher_priority, sizeof(cipher_priority)/sizeof(int), | |
754 | expciphers, cipher_index, sizeof(cipher_index)/sizeof(pri_item), | |
755 | US"cipher")) || | |
756 | (expmac != NULL && | |
757 | !set_priority(mac_priority, sizeof(mac_priority)/sizeof(int), | |
758 | expmac, mac_index, sizeof(mac_index)/sizeof(pri_item), | |
759 | US"MAC")) || | |
760 | (expkx != NULL && | |
761 | !set_priority(kx_priority, sizeof(kx_priority)/sizeof(int), | |
762 | expkx, kx_index, sizeof(kx_index)/sizeof(pri_item), | |
763 | US"key-exchange")) || | |
764 | (expproto != NULL && | |
765 | !set_priority(proto_priority, sizeof(proto_priority)/sizeof(int), | |
766 | expproto, proto_index, sizeof(proto_index)/sizeof(pri_item), | |
767 | US"protocol"))) | |
768 | { | |
769 | gnutls_deinit(session); | |
770 | return NULL; | |
059ec3d9 PH |
771 | } |
772 | ||
773 | /* Define the various priorities */ | |
774 | ||
775 | gnutls_cipher_set_priority(session, cipher_priority); | |
776 | gnutls_compression_set_priority(session, comp_priority); | |
777 | gnutls_kx_set_priority(session, kx_priority); | |
83da1223 | 778 | gnutls_protocol_set_priority(session, proto_priority); |
059ec3d9 PH |
779 | gnutls_mac_set_priority(session, mac_priority); |
780 | ||
781 | gnutls_cred_set(session, GNUTLS_CRD_CERTIFICATE, x509_cred); | |
782 | ||
783 | gnutls_dh_set_prime_bits(session, DH_BITS); | |
784 | ||
785 | /* Request or demand a certificate of the peer, as configured. This will | |
786 | happen only in a server. */ | |
787 | ||
788 | if (verify_requirement != VERIFY_NONE) | |
789 | gnutls_certificate_server_set_request(session, | |
790 | (verify_requirement == VERIFY_OPTIONAL)? | |
791 | GNUTLS_CERT_REQUEST : GNUTLS_CERT_REQUIRE); | |
792 | ||
793 | gnutls_db_set_cache_expiration(session, ssl_session_timeout); | |
794 | ||
e6060e2c NM |
795 | /* Reduce security in favour of increased compatibility, if the admin |
796 | decides to make that trade-off. */ | |
797 | if (gnutls_compat_mode) | |
798 | { | |
799 | #if LIBGNUTLS_VERSION_NUMBER >= 0x020104 | |
800 | DEBUG(D_tls) debug_printf("lowering GnuTLS security, compatibility mode\n"); | |
801 | gnutls_session_enable_compatibility_mode(session); | |
802 | #else | |
803 | DEBUG(D_tls) debug_printf("Unable to set gnutls_compat_mode - GnuTLS version too old\n"); | |
804 | #endif | |
805 | } | |
806 | ||
059ec3d9 PH |
807 | DEBUG(D_tls) debug_printf("initialized GnuTLS session\n"); |
808 | return session; | |
809 | } | |
810 | ||
811 | ||
812 | ||
813 | /************************************************* | |
814 | * Get name of cipher in use * | |
815 | *************************************************/ | |
816 | ||
817 | /* The answer is left in a static buffer, and tls_cipher is set to point | |
818 | to it. | |
819 | ||
820 | Argument: pointer to a GnuTLS session | |
821 | Returns: nothing | |
822 | */ | |
823 | ||
824 | static void | |
825 | construct_cipher_name(gnutls_session session) | |
826 | { | |
827 | static uschar cipherbuf[256]; | |
828 | uschar *ver; | |
829 | int bits, c, kx, mac; | |
830 | ||
831 | ver = string_copy( | |
832 | US gnutls_protocol_get_name(gnutls_protocol_get_version(session))); | |
833 | if (Ustrncmp(ver, "TLS ", 4) == 0) ver[3] = '-'; /* Don't want space */ | |
834 | ||
835 | c = gnutls_cipher_get(session); | |
836 | bits = gnutls_cipher_get_key_size(c); | |
837 | ||
838 | mac = gnutls_mac_get(session); | |
839 | kx = gnutls_kx_get(session); | |
840 | ||
841 | string_format(cipherbuf, sizeof(cipherbuf), "%s:%s:%u", ver, | |
842 | gnutls_cipher_suite_get_name(kx, c, mac), bits); | |
843 | tls_cipher = cipherbuf; | |
844 | ||
845 | DEBUG(D_tls) debug_printf("cipher: %s\n", cipherbuf); | |
846 | } | |
847 | ||
848 | ||
849 | ||
850 | /************************************************* | |
851 | * Start a TLS session in a server * | |
852 | *************************************************/ | |
853 | ||
854 | /* This is called when Exim is running as a server, after having received | |
855 | the STARTTLS command. It must respond to that command, and then negotiate | |
856 | a TLS session. | |
857 | ||
858 | Arguments: | |
83da1223 PH |
859 | require_ciphers list of allowed ciphers or NULL |
860 | require_mac list of allowed MACs or NULL | |
861 | require_kx list of allowed key_exchange methods or NULL | |
862 | require_proto list of allowed protocols or NULL | |
059ec3d9 PH |
863 | |
864 | Returns: OK on success | |
865 | DEFER for errors before the start of the negotiation | |
866 | FAIL for errors during the negotation; the server can't | |
867 | continue running. | |
868 | */ | |
869 | ||
870 | int | |
83da1223 PH |
871 | tls_server_start(uschar *require_ciphers, uschar *require_mac, |
872 | uschar *require_kx, uschar *require_proto) | |
059ec3d9 PH |
873 | { |
874 | int rc; | |
7199e1ee | 875 | const char *error; |
059ec3d9 | 876 | uschar *expciphers = NULL; |
83da1223 PH |
877 | uschar *expmac = NULL; |
878 | uschar *expkx = NULL; | |
879 | uschar *expproto = NULL; | |
059ec3d9 PH |
880 | |
881 | /* Check for previous activation */ | |
882 | ||
883 | if (tls_active >= 0) | |
884 | { | |
7199e1ee | 885 | tls_error("STARTTLS received after TLS started", NULL, ""); |
059ec3d9 PH |
886 | smtp_printf("554 Already in TLS\r\n"); |
887 | return FAIL; | |
888 | } | |
889 | ||
890 | /* Initialize the library. If it fails, it will already have logged the error | |
891 | and sent an SMTP response. */ | |
892 | ||
893 | DEBUG(D_tls) debug_printf("initializing GnuTLS as a server\n"); | |
894 | ||
895 | rc = tls_init(NULL, tls_certificate, tls_privatekey, tls_verify_certificates, | |
896 | tls_crl); | |
897 | if (rc != OK) return rc; | |
898 | ||
83da1223 PH |
899 | if (!expand_check(require_ciphers, US"tls_require_ciphers", &expciphers) || |
900 | !expand_check(require_mac, US"gnutls_require_mac", &expmac) || | |
901 | !expand_check(require_kx, US"gnutls_require_kx", &expkx) || | |
902 | !expand_check(require_proto, US"gnutls_require_proto", &expproto)) | |
059ec3d9 PH |
903 | return FAIL; |
904 | ||
905 | /* If this is a host for which certificate verification is mandatory or | |
906 | optional, set up appropriately. */ | |
907 | ||
908 | tls_certificate_verified = FALSE; | |
909 | verify_requirement = VERIFY_NONE; | |
910 | ||
911 | if (verify_check_host(&tls_verify_hosts) == OK) | |
912 | verify_requirement = VERIFY_REQUIRED; | |
913 | else if (verify_check_host(&tls_try_verify_hosts) == OK) | |
914 | verify_requirement = VERIFY_OPTIONAL; | |
915 | ||
916 | /* Prepare for new connection */ | |
917 | ||
83da1223 PH |
918 | tls_session = tls_session_init(GNUTLS_SERVER, expciphers, expmac, expkx, |
919 | expproto); | |
059ec3d9 | 920 | if (tls_session == NULL) |
7199e1ee TF |
921 | return tls_error(US"tls_session_init", NULL, |
922 | gnutls_strerror(GNUTLS_E_MEMORY_ERROR)); | |
059ec3d9 PH |
923 | |
924 | /* Set context and tell client to go ahead, except in the case of TLS startup | |
925 | on connection, where outputting anything now upsets the clients and tends to | |
926 | make them disconnect. We need to have an explicit fflush() here, to force out | |
927 | the response. Other smtp_printf() calls do not need it, because in non-TLS | |
928 | mode, the fflush() happens when smtp_getc() is called. */ | |
929 | ||
930 | if (!tls_on_connect) | |
931 | { | |
932 | smtp_printf("220 TLS go ahead\r\n"); | |
933 | fflush(smtp_out); | |
934 | } | |
935 | ||
936 | /* Now negotiate the TLS session. We put our own timer on it, since it seems | |
937 | that the GnuTLS library doesn't. */ | |
938 | ||
56f5d9bd PH |
939 | gnutls_transport_set_ptr2(tls_session, (gnutls_transport_ptr)fileno(smtp_in), |
940 | (gnutls_transport_ptr)fileno(smtp_out)); | |
059ec3d9 PH |
941 | |
942 | sigalrm_seen = FALSE; | |
943 | if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout); | |
944 | rc = gnutls_handshake(tls_session); | |
945 | alarm(0); | |
946 | ||
947 | if (rc < 0) | |
948 | { | |
7199e1ee TF |
949 | tls_error(US"gnutls_handshake", NULL, |
950 | sigalrm_seen ? "timed out" : gnutls_strerror(rc)); | |
059ec3d9 PH |
951 | |
952 | /* It seems that, except in the case of a timeout, we have to close the | |
953 | connection right here; otherwise if the other end is running OpenSSL it hangs | |
954 | until the server times out. */ | |
955 | ||
956 | if (!sigalrm_seen) | |
957 | { | |
f1e894f3 PH |
958 | (void)fclose(smtp_out); |
959 | (void)fclose(smtp_in); | |
059ec3d9 PH |
960 | } |
961 | ||
962 | return FAIL; | |
963 | } | |
964 | ||
965 | DEBUG(D_tls) debug_printf("gnutls_handshake was successful\n"); | |
966 | ||
967 | if (verify_requirement != VERIFY_NONE && | |
968 | !verify_certificate(tls_session, &error)) | |
969 | { | |
7199e1ee | 970 | tls_error(US"certificate verification failed", NULL, error); |
059ec3d9 PH |
971 | return FAIL; |
972 | } | |
973 | ||
974 | construct_cipher_name(tls_session); | |
975 | ||
976 | /* TLS has been set up. Adjust the input functions to read via TLS, | |
977 | and initialize appropriately. */ | |
978 | ||
979 | ssl_xfer_buffer = store_malloc(ssl_xfer_buffer_size); | |
980 | ssl_xfer_buffer_lwm = ssl_xfer_buffer_hwm = 0; | |
981 | ssl_xfer_eof = ssl_xfer_error = 0; | |
982 | ||
983 | receive_getc = tls_getc; | |
984 | receive_ungetc = tls_ungetc; | |
985 | receive_feof = tls_feof; | |
986 | receive_ferror = tls_ferror; | |
58eb016e | 987 | receive_smtp_buffered = tls_smtp_buffered; |
059ec3d9 PH |
988 | |
989 | tls_active = fileno(smtp_out); | |
990 | ||
991 | return OK; | |
992 | } | |
993 | ||
994 | ||
995 | ||
996 | ||
997 | /************************************************* | |
998 | * Start a TLS session in a client * | |
999 | *************************************************/ | |
1000 | ||
1001 | /* Called from the smtp transport after STARTTLS has been accepted. | |
1002 | ||
1003 | Arguments: | |
1004 | fd the fd of the connection | |
1005 | host connected host (for messages) | |
83da1223 | 1006 | addr the first address (not used) |
059ec3d9 PH |
1007 | dhparam DH parameter file |
1008 | certificate certificate file | |
1009 | privatekey private key file | |
1010 | verify_certs file for certificate verify | |
1011 | verify_crl CRL for verify | |
83da1223 PH |
1012 | require_ciphers list of allowed ciphers or NULL |
1013 | require_mac list of allowed MACs or NULL | |
1014 | require_kx list of allowed key_exchange methods or NULL | |
1015 | require_proto list of allowed protocols or NULL | |
059ec3d9 PH |
1016 | timeout startup timeout |
1017 | ||
1018 | Returns: OK/DEFER/FAIL (because using common functions), | |
1019 | but for a client, DEFER and FAIL have the same meaning | |
1020 | */ | |
1021 | ||
1022 | int | |
1023 | tls_client_start(int fd, host_item *host, address_item *addr, uschar *dhparam, | |
1024 | uschar *certificate, uschar *privatekey, uschar *verify_certs, | |
83da1223 PH |
1025 | uschar *verify_crl, uschar *require_ciphers, uschar *require_mac, |
1026 | uschar *require_kx, uschar *require_proto, int timeout) | |
059ec3d9 PH |
1027 | { |
1028 | const gnutls_datum *server_certs; | |
1029 | uschar *expciphers = NULL; | |
83da1223 PH |
1030 | uschar *expmac = NULL; |
1031 | uschar *expkx = NULL; | |
1032 | uschar *expproto = NULL; | |
7199e1ee | 1033 | const char *error; |
059ec3d9 PH |
1034 | unsigned int server_certs_size; |
1035 | int rc; | |
1036 | ||
1037 | DEBUG(D_tls) debug_printf("initializing GnuTLS as a client\n"); | |
1038 | ||
059ec3d9 PH |
1039 | verify_requirement = (verify_certs == NULL)? VERIFY_NONE : VERIFY_REQUIRED; |
1040 | rc = tls_init(host, certificate, privatekey, verify_certs, verify_crl); | |
1041 | if (rc != OK) return rc; | |
1042 | ||
83da1223 PH |
1043 | if (!expand_check(require_ciphers, US"tls_require_ciphers", &expciphers) || |
1044 | !expand_check(require_mac, US"gnutls_require_mac", &expmac) || | |
1045 | !expand_check(require_kx, US"gnutls_require_kx", &expkx) || | |
1046 | !expand_check(require_proto, US"gnutls_require_proto", &expproto)) | |
059ec3d9 PH |
1047 | return FAIL; |
1048 | ||
83da1223 PH |
1049 | tls_session = tls_session_init(GNUTLS_CLIENT, expciphers, expmac, expkx, |
1050 | expproto); | |
1051 | ||
059ec3d9 | 1052 | if (tls_session == NULL) |
7199e1ee TF |
1053 | return tls_error(US "tls_session_init", host, |
1054 | gnutls_strerror(GNUTLS_E_MEMORY_ERROR)); | |
059ec3d9 PH |
1055 | |
1056 | gnutls_transport_set_ptr(tls_session, (gnutls_transport_ptr)fd); | |
1057 | ||
1058 | /* There doesn't seem to be a built-in timeout on connection. */ | |
1059 | ||
1060 | sigalrm_seen = FALSE; | |
1061 | alarm(timeout); | |
1062 | rc = gnutls_handshake(tls_session); | |
1063 | alarm(0); | |
1064 | ||
1065 | if (rc < 0) | |
7199e1ee TF |
1066 | return tls_error(US "gnutls_handshake", host, |
1067 | sigalrm_seen ? "timed out" : gnutls_strerror(rc)); | |
059ec3d9 PH |
1068 | |
1069 | server_certs = gnutls_certificate_get_peers(tls_session, &server_certs_size); | |
1070 | ||
1071 | if (server_certs != NULL) | |
1072 | { | |
1073 | uschar buff[1024]; | |
1074 | gnutls_x509_crt gcert; | |
1075 | ||
1076 | gnutls_x509_crt_init(&gcert); | |
1077 | tls_peerdn = US"unknown"; | |
1078 | ||
1079 | if (gnutls_x509_crt_import(gcert, server_certs, GNUTLS_X509_FMT_DER) == 0) | |
1080 | { | |
1081 | size_t bufsize = sizeof(buff); | |
1082 | if (gnutls_x509_crt_get_dn(gcert, CS buff, &bufsize) >= 0) | |
1083 | tls_peerdn = string_copy_malloc(buff); | |
1084 | } | |
1085 | } | |
1086 | ||
1087 | /* Should we also verify the hostname here? */ | |
1088 | ||
1089 | if (verify_requirement != VERIFY_NONE && | |
1090 | !verify_certificate(tls_session, &error)) | |
7199e1ee | 1091 | return tls_error(US"certificate verification failed", host, error); |
059ec3d9 PH |
1092 | |
1093 | construct_cipher_name(tls_session); /* Sets tls_cipher */ | |
1094 | tls_active = fd; | |
1095 | return OK; | |
1096 | } | |
1097 | ||
1098 | ||
1099 | ||
1100 | /************************************************* | |
1101 | * Deal with logging errors during I/O * | |
1102 | *************************************************/ | |
1103 | ||
1104 | /* We have to get the identity of the peer from saved data. | |
1105 | ||
1106 | Argument: | |
1107 | ec the GnuTLS error code, or 0 if it's a local error | |
1108 | when text identifying read or write | |
1109 | text local error text when ec is 0 | |
1110 | ||
1111 | Returns: nothing | |
1112 | */ | |
1113 | ||
1114 | static void | |
1115 | record_io_error(int ec, uschar *when, uschar *text) | |
1116 | { | |
7199e1ee | 1117 | const char *msg; |
059ec3d9 PH |
1118 | |
1119 | if (ec == GNUTLS_E_FATAL_ALERT_RECEIVED) | |
7199e1ee | 1120 | msg = string_sprintf("%s: %s", gnutls_strerror(ec), |
059ec3d9 | 1121 | gnutls_alert_get_name(gnutls_alert_get(tls_session))); |
059ec3d9 | 1122 | else |
7199e1ee TF |
1123 | msg = gnutls_strerror(ec); |
1124 | ||
1125 | tls_error(when, client_host, msg); | |
059ec3d9 PH |
1126 | } |
1127 | ||
1128 | ||
1129 | ||
1130 | /************************************************* | |
1131 | * TLS version of getc * | |
1132 | *************************************************/ | |
1133 | ||
1134 | /* This gets the next byte from the TLS input buffer. If the buffer is empty, | |
1135 | it refills the buffer via the GnuTLS reading function. | |
1136 | ||
1137 | Arguments: none | |
1138 | Returns: the next character or EOF | |
1139 | */ | |
1140 | ||
1141 | int | |
1142 | tls_getc(void) | |
1143 | { | |
1144 | if (ssl_xfer_buffer_lwm >= ssl_xfer_buffer_hwm) | |
1145 | { | |
1146 | int inbytes; | |
1147 | ||
1148 | DEBUG(D_tls) debug_printf("Calling gnutls_record_recv(%lx, %lx, %u)\n", | |
1149 | (long) tls_session, (long) ssl_xfer_buffer, ssl_xfer_buffer_size); | |
1150 | ||
1151 | if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout); | |
1152 | inbytes = gnutls_record_recv(tls_session, CS ssl_xfer_buffer, | |
1153 | ssl_xfer_buffer_size); | |
1154 | alarm(0); | |
1155 | ||
1156 | /* A zero-byte return appears to mean that the TLS session has been | |
1157 | closed down, not that the socket itself has been closed down. Revert to | |
1158 | non-TLS handling. */ | |
1159 | ||
1160 | if (inbytes == 0) | |
1161 | { | |
1162 | DEBUG(D_tls) debug_printf("Got TLS_EOF\n"); | |
1163 | ||
1164 | receive_getc = smtp_getc; | |
1165 | receive_ungetc = smtp_ungetc; | |
1166 | receive_feof = smtp_feof; | |
1167 | receive_ferror = smtp_ferror; | |
58eb016e | 1168 | receive_smtp_buffered = smtp_buffered; |
059ec3d9 PH |
1169 | |
1170 | gnutls_deinit(tls_session); | |
1171 | tls_session = NULL; | |
1172 | tls_active = -1; | |
1173 | tls_cipher = NULL; | |
1174 | tls_peerdn = NULL; | |
1175 | ||
1176 | return smtp_getc(); | |
1177 | } | |
1178 | ||
1179 | /* Handle genuine errors */ | |
1180 | ||
1181 | else if (inbytes < 0) | |
1182 | { | |
1183 | record_io_error(inbytes, US"recv", NULL); | |
1184 | ssl_xfer_error = 1; | |
1185 | return EOF; | |
1186 | } | |
80a47a2c TK |
1187 | #ifndef DISABLE_DKIM |
1188 | dkim_exim_verify_feed(ssl_xfer_buffer, inbytes); | |
1189 | #endif | |
059ec3d9 PH |
1190 | ssl_xfer_buffer_hwm = inbytes; |
1191 | ssl_xfer_buffer_lwm = 0; | |
1192 | } | |
1193 | ||
1194 | ||
1195 | /* Something in the buffer; return next uschar */ | |
1196 | ||
1197 | return ssl_xfer_buffer[ssl_xfer_buffer_lwm++]; | |
1198 | } | |
1199 | ||
1200 | ||
1201 | ||
1202 | /************************************************* | |
1203 | * Read bytes from TLS channel * | |
1204 | *************************************************/ | |
1205 | ||
1206 | /* | |
1207 | Arguments: | |
1208 | buff buffer of data | |
1209 | len size of buffer | |
1210 | ||
1211 | Returns: the number of bytes read | |
1212 | -1 after a failed read | |
1213 | */ | |
1214 | ||
1215 | int | |
1216 | tls_read(uschar *buff, size_t len) | |
1217 | { | |
1218 | int inbytes; | |
1219 | ||
1220 | DEBUG(D_tls) debug_printf("Calling gnutls_record_recv(%lx, %lx, %u)\n", | |
1221 | (long) tls_session, (long) buff, len); | |
1222 | ||
1223 | inbytes = gnutls_record_recv(tls_session, CS buff, len); | |
1224 | if (inbytes > 0) return inbytes; | |
1225 | if (inbytes == 0) | |
1226 | { | |
1227 | DEBUG(D_tls) debug_printf("Got TLS_EOF\n"); | |
1228 | } | |
1229 | else record_io_error(inbytes, US"recv", NULL); | |
1230 | ||
1231 | return -1; | |
1232 | } | |
1233 | ||
1234 | ||
1235 | ||
1236 | /************************************************* | |
1237 | * Write bytes down TLS channel * | |
1238 | *************************************************/ | |
1239 | ||
1240 | /* | |
1241 | Arguments: | |
1242 | buff buffer of data | |
1243 | len number of bytes | |
1244 | ||
1245 | Returns: the number of bytes after a successful write, | |
1246 | -1 after a failed write | |
1247 | */ | |
1248 | ||
1249 | int | |
1250 | tls_write(const uschar *buff, size_t len) | |
1251 | { | |
1252 | int outbytes; | |
1253 | int left = len; | |
1254 | ||
1255 | DEBUG(D_tls) debug_printf("tls_do_write(%lx, %d)\n", (long) buff, left); | |
1256 | while (left > 0) | |
1257 | { | |
1258 | DEBUG(D_tls) debug_printf("gnutls_record_send(SSL, %lx, %d)\n", (long)buff, | |
1259 | left); | |
1260 | outbytes = gnutls_record_send(tls_session, CS buff, left); | |
1261 | ||
1262 | DEBUG(D_tls) debug_printf("outbytes=%d\n", outbytes); | |
1263 | if (outbytes < 0) | |
1264 | { | |
1265 | record_io_error(outbytes, US"send", NULL); | |
1266 | return -1; | |
1267 | } | |
1268 | if (outbytes == 0) | |
1269 | { | |
1270 | record_io_error(0, US"send", US"TLS channel closed on write"); | |
1271 | return -1; | |
1272 | } | |
1273 | ||
1274 | left -= outbytes; | |
1275 | buff += outbytes; | |
1276 | } | |
1277 | ||
1278 | return len; | |
1279 | } | |
1280 | ||
1281 | ||
1282 | ||
1283 | /************************************************* | |
1284 | * Close down a TLS session * | |
1285 | *************************************************/ | |
1286 | ||
1287 | /* This is also called from within a delivery subprocess forked from the | |
1288 | daemon, to shut down the TLS library, without actually doing a shutdown (which | |
1289 | would tamper with the TLS session in the parent process). | |
1290 | ||
1291 | Arguments: TRUE if gnutls_bye is to be called | |
1292 | Returns: nothing | |
1293 | */ | |
1294 | ||
1295 | void | |
1296 | tls_close(BOOL shutdown) | |
1297 | { | |
1298 | if (tls_active < 0) return; /* TLS was not active */ | |
1299 | ||
1300 | if (shutdown) | |
1301 | { | |
1302 | DEBUG(D_tls) debug_printf("tls_close(): shutting down TLS\n"); | |
1303 | gnutls_bye(tls_session, GNUTLS_SHUT_WR); | |
1304 | } | |
1305 | ||
1306 | gnutls_deinit(tls_session); | |
1307 | tls_session = NULL; | |
1308 | gnutls_global_deinit(); | |
1309 | ||
1310 | tls_active = -1; | |
1311 | } | |
1312 | ||
36f12725 NM |
1313 | |
1314 | ||
1315 | ||
1316 | /************************************************* | |
1317 | * Report the library versions. * | |
1318 | *************************************************/ | |
1319 | ||
1320 | /* See a description in tls-openssl.c for an explanation of why this exists. | |
1321 | ||
1322 | Arguments: a FILE* to print the results to | |
1323 | Returns: nothing | |
1324 | */ | |
1325 | ||
1326 | void | |
1327 | tls_version_report(FILE *f) | |
1328 | { | |
1329 | fprintf(f, "GnuTLS compile-time version: %s\n", LIBGNUTLS_VERSION); | |
1330 | fprintf(f, "GnuTLS runtime version: %s\n", gnutls_check_version(NULL)); | |
1331 | } | |
1332 | ||
059ec3d9 | 1333 | /* End of tls-gnu.c */ |