Commit | Line | Data |
---|---|---|
059ec3d9 PH |
1 | /************************************************* |
2 | * Exim - an Internet mail transport agent * | |
3 | *************************************************/ | |
4 | ||
bc338899 | 5 | /* Copyright (c) University of Cambridge 1995 - 2013 */ |
059ec3d9 PH |
6 | /* See the file NOTICE for conditions of use and distribution. */ |
7 | ||
17c76198 | 8 | /* Copyright (c) Phil Pennock 2012 */ |
059ec3d9 | 9 | |
17c76198 PP |
10 | /* This file provides TLS/SSL support for Exim using the GnuTLS library, |
11 | one of the available supported implementations. This file is #included into | |
12 | tls.c when USE_GNUTLS has been set. | |
059ec3d9 | 13 | |
17c76198 PP |
14 | The code herein is a revamp of GnuTLS integration using the current APIs; the |
15 | original tls-gnu.c was based on a patch which was contributed by Nikos | |
16 | Mavroyanopoulos. The revamp is partially a rewrite, partially cut&paste as | |
17 | appropriate. | |
059ec3d9 | 18 | |
17c76198 PP |
19 | APIs current as of GnuTLS 2.12.18; note that the GnuTLS manual is for GnuTLS 3, |
20 | which is not widely deployed by OS vendors. Will note issues below, which may | |
21 | assist in updating the code in the future. Another sources of hints is | |
22 | mod_gnutls for Apache (SNI callback registration and handling). | |
059ec3d9 | 23 | |
17c76198 PP |
24 | Keeping client and server variables more split than before and is currently |
25 | the norm, in anticipation of TLS in ACL callouts. | |
059ec3d9 | 26 | |
17c76198 PP |
27 | I wanted to switch to gnutls_certificate_set_verify_function() so that |
28 | certificate rejection could happen during handshake where it belongs, rather | |
29 | than being dropped afterwards, but that was introduced in 2.10.0 and Debian | |
30 | (6.0.5) is still on 2.8.6. So for now we have to stick with sub-par behaviour. | |
059ec3d9 | 31 | |
17c76198 PP |
32 | (I wasn't looking for libraries quite that old, when updating to get rid of |
33 | compiler warnings of deprecated APIs. If it turns out that a lot of the rest | |
34 | require current GnuTLS, then we'll drop support for the ancient libraries). | |
35 | */ | |
b5aea5e1 | 36 | |
17c76198 PP |
37 | #include <gnutls/gnutls.h> |
38 | /* needed for cert checks in verification and DN extraction: */ | |
39 | #include <gnutls/x509.h> | |
40 | /* man-page is incorrect, gnutls_rnd() is not in gnutls.h: */ | |
41 | #include <gnutls/crypto.h> | |
a5f239e4 PP |
42 | /* needed to disable PKCS11 autoload unless requested */ |
43 | #if GNUTLS_VERSION_NUMBER >= 0x020c00 | |
44 | # include <gnutls/pkcs11.h> | |
45 | #endif | |
059ec3d9 | 46 | |
17c76198 | 47 | /* GnuTLS 2 vs 3 |
059ec3d9 | 48 | |
17c76198 PP |
49 | GnuTLS 3 only: |
50 | gnutls_global_set_audit_log_function() | |
059ec3d9 | 51 | |
17c76198 PP |
52 | Changes: |
53 | gnutls_certificate_verify_peers2(): is new, drop the 2 for old version | |
54 | */ | |
059ec3d9 | 55 | |
17c76198 | 56 | /* Local static variables for GnuTLS */ |
059ec3d9 | 57 | |
17c76198 | 58 | /* Values for verify_requirement */ |
059ec3d9 | 59 | |
17c76198 | 60 | enum peer_verify_requirement { VERIFY_NONE, VERIFY_OPTIONAL, VERIFY_REQUIRED }; |
059ec3d9 | 61 | |
17c76198 PP |
62 | /* This holds most state for server or client; with this, we can set up an |
63 | outbound TLS-enabled connection in an ACL callout, while not stomping all | |
64 | over the TLS variables available for expansion. | |
059ec3d9 | 65 | |
17c76198 PP |
66 | Some of these correspond to variables in globals.c; those variables will |
67 | be set to point to content in one of these instances, as appropriate for | |
68 | the stage of the process lifetime. | |
059ec3d9 | 69 | |
389ca47a | 70 | Not handled here: global tls_channelbinding_b64. |
17c76198 | 71 | */ |
059ec3d9 | 72 | |
17c76198 PP |
73 | typedef struct exim_gnutls_state { |
74 | gnutls_session_t session; | |
75 | gnutls_certificate_credentials_t x509_cred; | |
76 | gnutls_priority_t priority_cache; | |
77 | enum peer_verify_requirement verify_requirement; | |
78 | int fd_in; | |
79 | int fd_out; | |
80 | BOOL peer_cert_verified; | |
81 | BOOL trigger_sni_changes; | |
4fe99a6c | 82 | BOOL have_set_peerdn; |
17c76198 PP |
83 | const struct host_item *host; |
84 | uschar *peerdn; | |
75fe387d | 85 | uschar *ciphersuite; |
17c76198 PP |
86 | uschar *received_sni; |
87 | ||
88 | const uschar *tls_certificate; | |
89 | const uschar *tls_privatekey; | |
90 | const uschar *tls_sni; /* client send only, not received */ | |
91 | const uschar *tls_verify_certificates; | |
92 | const uschar *tls_crl; | |
93 | const uschar *tls_require_ciphers; | |
94 | uschar *exp_tls_certificate; | |
95 | uschar *exp_tls_privatekey; | |
96 | uschar *exp_tls_sni; | |
97 | uschar *exp_tls_verify_certificates; | |
98 | uschar *exp_tls_crl; | |
99 | uschar *exp_tls_require_ciphers; | |
100 | ||
389ca47a | 101 | tls_support *tlsp; /* set in tls_init() */ |
817d9f57 | 102 | |
17c76198 PP |
103 | uschar *xfer_buffer; |
104 | int xfer_buffer_lwm; | |
105 | int xfer_buffer_hwm; | |
106 | int xfer_eof; | |
107 | int xfer_error; | |
17c76198 PP |
108 | } exim_gnutls_state_st; |
109 | ||
110 | static const exim_gnutls_state_st exim_gnutls_state_init = { | |
4fe99a6c | 111 | NULL, NULL, NULL, VERIFY_NONE, -1, -1, FALSE, FALSE, FALSE, |
75fe387d | 112 | NULL, NULL, NULL, NULL, |
17c76198 PP |
113 | NULL, NULL, NULL, NULL, NULL, NULL, |
114 | NULL, NULL, NULL, NULL, NULL, NULL, | |
817d9f57 | 115 | NULL, |
17c76198 | 116 | NULL, 0, 0, 0, 0, |
17c76198 | 117 | }; |
83da1223 | 118 | |
17c76198 PP |
119 | /* Not only do we have our own APIs which don't pass around state, assuming |
120 | it's held in globals, GnuTLS doesn't appear to let us register callback data | |
121 | for callbacks, or as part of the session, so we have to keep a "this is the | |
122 | context we're currently dealing with" pointer and rely upon being | |
123 | single-threaded to keep from processing data on an inbound TLS connection while | |
124 | talking to another TLS connection for an outbound check. This does mean that | |
125 | there's no way for heart-beats to be responded to, for the duration of the | |
126 | second connection. */ | |
059ec3d9 | 127 | |
17c76198 | 128 | static exim_gnutls_state_st state_server, state_client; |
059ec3d9 | 129 | |
17c76198 PP |
130 | /* dh_params are initialised once within the lifetime of a process using TLS; |
131 | if we used TLS in a long-lived daemon, we'd have to reconsider this. But we | |
132 | don't want to repeat this. */ | |
83da1223 | 133 | |
17c76198 | 134 | static gnutls_dh_params_t dh_server_params = NULL; |
059ec3d9 | 135 | |
17c76198 | 136 | /* No idea how this value was chosen; preserving it. Default is 3600. */ |
059ec3d9 | 137 | |
17c76198 | 138 | static const int ssl_session_timeout = 200; |
059ec3d9 | 139 | |
17c76198 | 140 | static const char * const exim_default_gnutls_priority = "NORMAL"; |
83da1223 | 141 | |
17c76198 | 142 | /* Guard library core initialisation */ |
83da1223 | 143 | |
17c76198 | 144 | static BOOL exim_gnutls_base_init_done = FALSE; |
059ec3d9 | 145 | |
059ec3d9 | 146 | |
17c76198 PP |
147 | /* ------------------------------------------------------------------------ */ |
148 | /* macros */ | |
83da1223 | 149 | |
17c76198 | 150 | #define MAX_HOST_LEN 255 |
83da1223 | 151 | |
17c76198 PP |
152 | /* Set this to control gnutls_global_set_log_level(); values 0 to 9 will setup |
153 | the library logging; a value less than 0 disables the calls to set up logging | |
154 | callbacks. */ | |
2c17bb02 | 155 | #ifndef EXIM_GNUTLS_LIBRARY_LOG_LEVEL |
17c76198 | 156 | #define EXIM_GNUTLS_LIBRARY_LOG_LEVEL -1 |
2c17bb02 | 157 | #endif |
83da1223 | 158 | |
2c17bb02 | 159 | #ifndef EXIM_CLIENT_DH_MIN_BITS |
bba74fc6 | 160 | #define EXIM_CLIENT_DH_MIN_BITS 1024 |
2c17bb02 | 161 | #endif |
83da1223 | 162 | |
af3498d6 PP |
163 | /* With GnuTLS 2.12.x+ we have gnutls_sec_param_to_pk_bits() with which we |
164 | can ask for a bit-strength. Without that, we stick to the constant we had | |
165 | before, for now. */ | |
2c17bb02 | 166 | #ifndef EXIM_SERVER_DH_BITS_PRE2_12 |
af3498d6 | 167 | #define EXIM_SERVER_DH_BITS_PRE2_12 1024 |
2c17bb02 | 168 | #endif |
af3498d6 | 169 | |
17c76198 PP |
170 | #define exim_gnutls_err_check(Label) do { \ |
171 | if (rc != GNUTLS_E_SUCCESS) { return tls_error((Label), gnutls_strerror(rc), host); } } while (0) | |
059ec3d9 | 172 | |
17c76198 | 173 | #define expand_check_tlsvar(Varname) expand_check(state->Varname, US #Varname, &state->exp_##Varname) |
83da1223 | 174 | |
17c76198 PP |
175 | #if GNUTLS_VERSION_NUMBER >= 0x020c00 |
176 | #define HAVE_GNUTLS_SESSION_CHANNEL_BINDING | |
af3498d6 PP |
177 | #define HAVE_GNUTLS_SEC_PARAM_CONSTANTS |
178 | #define HAVE_GNUTLS_RND | |
2519e60d TL |
179 | /* The security fix we provide with the gnutls_allow_auto_pkcs11 option |
180 | * (4.82 PP/09) introduces a compatibility regression. The symbol simply | |
181 | * isn't available sometimes, so this needs to become a conditional | |
182 | * compilation; the sanest way to deal with this being a problem on | |
183 | * older OSes is to block it in the Local/Makefile with this compiler | |
184 | * definition */ | |
185 | #ifndef AVOID_GNUTLS_PKCS11 | |
a5f239e4 | 186 | #define HAVE_GNUTLS_PKCS11 |
2519e60d | 187 | #endif /* AVOID_GNUTLS_PKCS11 */ |
17c76198 | 188 | #endif |
83da1223 | 189 | |
af3498d6 PP |
190 | |
191 | ||
192 | ||
193 | /* ------------------------------------------------------------------------ */ | |
194 | /* Callback declarations */ | |
195 | ||
196 | #if EXIM_GNUTLS_LIBRARY_LOG_LEVEL >= 0 | |
197 | static void exim_gnutls_logger_cb(int level, const char *message); | |
198 | #endif | |
199 | ||
200 | static int exim_sni_handling_cb(gnutls_session_t session); | |
201 | ||
202 | ||
203 | ||
204 | ||
17c76198 PP |
205 | /* ------------------------------------------------------------------------ */ |
206 | /* Static functions */ | |
059ec3d9 PH |
207 | |
208 | /************************************************* | |
209 | * Handle TLS error * | |
210 | *************************************************/ | |
211 | ||
212 | /* Called from lots of places when errors occur before actually starting to do | |
213 | the TLS handshake, that is, while the session is still in clear. Always returns | |
214 | DEFER for a server and FAIL for a client so that most calls can use "return | |
215 | tls_error(...)" to do this processing and then give an appropriate return. A | |
216 | single function is used for both server and client, because it is called from | |
217 | some shared functions. | |
218 | ||
219 | Argument: | |
220 | prefix text to include in the logged error | |
7199e1ee TF |
221 | msg additional error string (may be NULL) |
222 | usually obtained from gnutls_strerror() | |
17c76198 PP |
223 | host NULL if setting up a server; |
224 | the connected host if setting up a client | |
059ec3d9 PH |
225 | |
226 | Returns: OK/DEFER/FAIL | |
227 | */ | |
228 | ||
229 | static int | |
17c76198 | 230 | tls_error(const uschar *prefix, const char *msg, const host_item *host) |
059ec3d9 | 231 | { |
17c76198 PP |
232 | if (host) |
233 | { | |
234 | log_write(0, LOG_MAIN, "TLS error on connection to %s [%s] (%s)%s%s", | |
235 | host->name, host->address, prefix, msg ? ": " : "", msg ? msg : ""); | |
236 | return FAIL; | |
237 | } | |
238 | else | |
059ec3d9 | 239 | { |
7199e1ee | 240 | uschar *conn_info = smtp_get_connection_info(); |
17c76198 | 241 | if (Ustrncmp(conn_info, US"SMTP ", 5) == 0) |
7199e1ee TF |
242 | conn_info += 5; |
243 | log_write(0, LOG_MAIN, "TLS error on %s (%s)%s%s", | |
17c76198 | 244 | conn_info, prefix, msg ? ": " : "", msg ? msg : ""); |
059ec3d9 PH |
245 | return DEFER; |
246 | } | |
059ec3d9 PH |
247 | } |
248 | ||
249 | ||
250 | ||
17c76198 | 251 | |
059ec3d9 | 252 | /************************************************* |
17c76198 | 253 | * Deal with logging errors during I/O * |
059ec3d9 PH |
254 | *************************************************/ |
255 | ||
17c76198 | 256 | /* We have to get the identity of the peer from saved data. |
059ec3d9 | 257 | |
17c76198 PP |
258 | Argument: |
259 | state the current GnuTLS exim state container | |
260 | rc the GnuTLS error code, or 0 if it's a local error | |
261 | when text identifying read or write | |
262 | text local error text when ec is 0 | |
059ec3d9 | 263 | |
17c76198 | 264 | Returns: nothing |
059ec3d9 PH |
265 | */ |
266 | ||
17c76198 PP |
267 | static void |
268 | record_io_error(exim_gnutls_state_st *state, int rc, uschar *when, uschar *text) | |
059ec3d9 | 269 | { |
17c76198 | 270 | const char *msg; |
059ec3d9 | 271 | |
17c76198 PP |
272 | if (rc == GNUTLS_E_FATAL_ALERT_RECEIVED) |
273 | msg = CS string_sprintf("%s: %s", US gnutls_strerror(rc), | |
274 | US gnutls_alert_get_name(gnutls_alert_get(state->session))); | |
275 | else | |
276 | msg = gnutls_strerror(rc); | |
059ec3d9 | 277 | |
17c76198 PP |
278 | tls_error(when, msg, state->host); |
279 | } | |
059ec3d9 | 280 | |
059ec3d9 | 281 | |
059ec3d9 | 282 | |
059ec3d9 | 283 | |
17c76198 PP |
284 | /************************************************* |
285 | * Set various Exim expansion vars * | |
286 | *************************************************/ | |
059ec3d9 | 287 | |
17c76198 PP |
288 | /* We set various Exim global variables from the state, once a session has |
289 | been established. With TLS callouts, may need to change this to stack | |
290 | variables, or just re-call it with the server state after client callout | |
291 | has finished. | |
059ec3d9 | 292 | |
17c76198 PP |
293 | Make sure anything set here is inset in tls_getc(). |
294 | ||
295 | Sets: | |
296 | tls_active fd | |
297 | tls_bits strength indicator | |
298 | tls_certificate_verified bool indicator | |
299 | tls_channelbinding_b64 for some SASL mechanisms | |
300 | tls_cipher a string | |
301 | tls_peerdn a string | |
302 | tls_sni a (UTF-8) string | |
17c76198 PP |
303 | |
304 | Argument: | |
305 | state the relevant exim_gnutls_state_st * | |
306 | */ | |
307 | ||
308 | static void | |
817d9f57 | 309 | extract_exim_vars_from_tls_state(exim_gnutls_state_st *state, BOOL is_server) |
17c76198 | 310 | { |
17c76198 | 311 | gnutls_cipher_algorithm_t cipher; |
17c76198 PP |
312 | #ifdef HAVE_GNUTLS_SESSION_CHANNEL_BINDING |
313 | int old_pool; | |
314 | int rc; | |
315 | gnutls_datum_t channel; | |
316 | #endif | |
317 | ||
817d9f57 | 318 | state->tlsp->active = state->fd_out; |
17c76198 PP |
319 | |
320 | cipher = gnutls_cipher_get(state->session); | |
321 | /* returns size in "bytes" */ | |
817d9f57 | 322 | state->tlsp->bits = gnutls_cipher_get_key_size(cipher) * 8; |
17c76198 | 323 | |
817d9f57 | 324 | state->tlsp->cipher = state->ciphersuite; |
17c76198 | 325 | |
817d9f57 | 326 | DEBUG(D_tls) debug_printf("cipher: %s\n", state->ciphersuite); |
17c76198 | 327 | |
817d9f57 | 328 | state->tlsp->certificate_verified = state->peer_cert_verified; |
059ec3d9 | 329 | |
17c76198 PP |
330 | /* note that tls_channelbinding_b64 is not saved to the spool file, since it's |
331 | only available for use for authenticators while this TLS session is running. */ | |
332 | ||
333 | tls_channelbinding_b64 = NULL; | |
334 | #ifdef HAVE_GNUTLS_SESSION_CHANNEL_BINDING | |
335 | channel.data = NULL; | |
336 | channel.size = 0; | |
337 | rc = gnutls_session_channel_binding(state->session, GNUTLS_CB_TLS_UNIQUE, &channel); | |
338 | if (rc) { | |
339 | DEBUG(D_tls) debug_printf("Channel binding error: %s\n", gnutls_strerror(rc)); | |
340 | } else { | |
341 | old_pool = store_pool; | |
342 | store_pool = POOL_PERM; | |
343 | tls_channelbinding_b64 = auth_b64encode(channel.data, (int)channel.size); | |
344 | store_pool = old_pool; | |
345 | DEBUG(D_tls) debug_printf("Have channel bindings cached for possible auth usage.\n"); | |
346 | } | |
347 | #endif | |
348 | ||
817d9f57 JH |
349 | state->tlsp->peerdn = state->peerdn; |
350 | state->tlsp->sni = state->received_sni; | |
059ec3d9 PH |
351 | } |
352 | ||
353 | ||
354 | ||
17c76198 | 355 | |
059ec3d9 | 356 | /************************************************* |
575643cd | 357 | * Setup up DH parameters * |
059ec3d9 PH |
358 | *************************************************/ |
359 | ||
575643cd | 360 | /* Generating the D-H parameters may take a long time. They only need to |
059ec3d9 PH |
361 | be re-generated every so often, depending on security policy. What we do is to |
362 | keep these parameters in a file in the spool directory. If the file does not | |
363 | exist, we generate them. This means that it is easy to cause a regeneration. | |
364 | ||
365 | The new file is written as a temporary file and renamed, so that an incomplete | |
366 | file is never present. If two processes both compute some new parameters, you | |
367 | waste a bit of effort, but it doesn't seem worth messing around with locking to | |
368 | prevent this. | |
369 | ||
059ec3d9 PH |
370 | Returns: OK/DEFER/FAIL |
371 | */ | |
372 | ||
373 | static int | |
17c76198 | 374 | init_server_dh(void) |
059ec3d9 | 375 | { |
17c76198 PP |
376 | int fd, rc; |
377 | unsigned int dh_bits; | |
b5aea5e1 | 378 | gnutls_datum m; |
a799883d PP |
379 | uschar filename_buf[PATH_MAX]; |
380 | uschar *filename = NULL; | |
17c76198 | 381 | size_t sz; |
a799883d PP |
382 | uschar *exp_tls_dhparam; |
383 | BOOL use_file_in_spool = FALSE; | |
384 | BOOL use_fixed_file = FALSE; | |
17c76198 | 385 | host_item *host = NULL; /* dummy for macros */ |
059ec3d9 | 386 | |
17c76198 | 387 | DEBUG(D_tls) debug_printf("Initialising GnuTLS server params.\n"); |
059ec3d9 | 388 | |
17c76198 PP |
389 | rc = gnutls_dh_params_init(&dh_server_params); |
390 | exim_gnutls_err_check(US"gnutls_dh_params_init"); | |
059ec3d9 | 391 | |
a799883d PP |
392 | m.data = NULL; |
393 | m.size = 0; | |
394 | ||
395 | if (!expand_check(tls_dhparam, US"tls_dhparam", &exp_tls_dhparam)) | |
396 | return DEFER; | |
397 | ||
398 | if (!exp_tls_dhparam) | |
399 | { | |
400 | DEBUG(D_tls) debug_printf("Loading default hard-coded DH params\n"); | |
401 | m.data = US std_dh_prime_default(); | |
402 | m.size = Ustrlen(m.data); | |
403 | } | |
404 | else if (Ustrcmp(exp_tls_dhparam, "historic") == 0) | |
405 | use_file_in_spool = TRUE; | |
406 | else if (Ustrcmp(exp_tls_dhparam, "none") == 0) | |
407 | { | |
408 | DEBUG(D_tls) debug_printf("Requested no DH parameters.\n"); | |
409 | return OK; | |
410 | } | |
411 | else if (exp_tls_dhparam[0] != '/') | |
412 | { | |
413 | m.data = US std_dh_prime_named(exp_tls_dhparam); | |
414 | if (m.data == NULL) | |
415 | return tls_error(US"No standard prime named", CS exp_tls_dhparam, NULL); | |
416 | m.size = Ustrlen(m.data); | |
417 | } | |
418 | else | |
419 | { | |
420 | use_fixed_file = TRUE; | |
421 | filename = exp_tls_dhparam; | |
422 | } | |
423 | ||
424 | if (m.data) | |
425 | { | |
426 | rc = gnutls_dh_params_import_pkcs3(dh_server_params, &m, GNUTLS_X509_FMT_PEM); | |
427 | exim_gnutls_err_check(US"gnutls_dh_params_import_pkcs3"); | |
428 | DEBUG(D_tls) debug_printf("Loaded fixed standard D-H parameters\n"); | |
429 | return OK; | |
430 | } | |
431 | ||
af3498d6 PP |
432 | #ifdef HAVE_GNUTLS_SEC_PARAM_CONSTANTS |
433 | /* If you change this constant, also change dh_param_fn_ext so that we can use a | |
17c76198 PP |
434 | different filename and ensure we have sufficient bits. */ |
435 | dh_bits = gnutls_sec_param_to_pk_bits(GNUTLS_PK_DH, GNUTLS_SEC_PARAM_NORMAL); | |
436 | if (!dh_bits) | |
437 | return tls_error(US"gnutls_sec_param_to_pk_bits() failed", NULL, NULL); | |
af3498d6 | 438 | DEBUG(D_tls) |
b34fc30c | 439 | debug_printf("GnuTLS tells us that for D-H PK, NORMAL is %d bits.\n", |
af3498d6 PP |
440 | dh_bits); |
441 | #else | |
442 | dh_bits = EXIM_SERVER_DH_BITS_PRE2_12; | |
443 | DEBUG(D_tls) | |
444 | debug_printf("GnuTLS lacks gnutls_sec_param_to_pk_bits(), using %d bits.\n", | |
445 | dh_bits); | |
446 | #endif | |
059ec3d9 | 447 | |
3375e053 PP |
448 | /* Some clients have hard-coded limits. */ |
449 | if (dh_bits > tls_dh_max_bits) | |
450 | { | |
451 | DEBUG(D_tls) | |
452 | debug_printf("tls_dh_max_bits clamping override, using %d bits instead.\n", | |
453 | tls_dh_max_bits); | |
454 | dh_bits = tls_dh_max_bits; | |
455 | } | |
456 | ||
a799883d PP |
457 | if (use_file_in_spool) |
458 | { | |
459 | if (!string_format(filename_buf, sizeof(filename_buf), | |
460 | "%s/gnutls-params-%d", spool_directory, dh_bits)) | |
461 | return tls_error(US"overlong filename", NULL, NULL); | |
462 | filename = filename_buf; | |
463 | } | |
059ec3d9 | 464 | |
b5aea5e1 | 465 | /* Open the cache file for reading and if successful, read it and set up the |
575643cd | 466 | parameters. */ |
059ec3d9 PH |
467 | |
468 | fd = Uopen(filename, O_RDONLY, 0); | |
b5aea5e1 | 469 | if (fd >= 0) |
059ec3d9 | 470 | { |
b5aea5e1 | 471 | struct stat statbuf; |
17c76198 PP |
472 | FILE *fp; |
473 | int saved_errno; | |
474 | ||
475 | if (fstat(fd, &statbuf) < 0) /* EIO */ | |
476 | { | |
477 | saved_errno = errno; | |
478 | (void)close(fd); | |
479 | return tls_error(US"TLS cache stat failed", strerror(saved_errno), NULL); | |
480 | } | |
481 | if (!S_ISREG(statbuf.st_mode)) | |
b5aea5e1 PH |
482 | { |
483 | (void)close(fd); | |
17c76198 PP |
484 | return tls_error(US"TLS cache not a file", NULL, NULL); |
485 | } | |
486 | fp = fdopen(fd, "rb"); | |
487 | if (!fp) | |
488 | { | |
489 | saved_errno = errno; | |
490 | (void)close(fd); | |
491 | return tls_error(US"fdopen(TLS cache stat fd) failed", | |
492 | strerror(saved_errno), NULL); | |
b5aea5e1 | 493 | } |
059ec3d9 | 494 | |
b5aea5e1 PH |
495 | m.size = statbuf.st_size; |
496 | m.data = malloc(m.size); | |
497 | if (m.data == NULL) | |
17c76198 PP |
498 | { |
499 | fclose(fp); | |
500 | return tls_error(US"malloc failed", strerror(errno), NULL); | |
501 | } | |
502 | sz = fread(m.data, m.size, 1, fp); | |
503 | if (!sz) | |
504 | { | |
505 | saved_errno = errno; | |
506 | fclose(fp); | |
507 | free(m.data); | |
508 | return tls_error(US"fread failed", strerror(saved_errno), NULL); | |
509 | } | |
510 | fclose(fp); | |
b5aea5e1 | 511 | |
17c76198 | 512 | rc = gnutls_dh_params_import_pkcs3(dh_server_params, &m, GNUTLS_X509_FMT_PEM); |
b5aea5e1 | 513 | free(m.data); |
17c76198 PP |
514 | exim_gnutls_err_check(US"gnutls_dh_params_import_pkcs3"); |
515 | DEBUG(D_tls) debug_printf("read D-H parameters from file \"%s\"\n", filename); | |
b5aea5e1 PH |
516 | } |
517 | ||
518 | /* If the file does not exist, fall through to compute new data and cache it. | |
519 | If there was any other opening error, it is serious. */ | |
520 | ||
182ad5cf PH |
521 | else if (errno == ENOENT) |
522 | { | |
17c76198 | 523 | rc = -1; |
182ad5cf | 524 | DEBUG(D_tls) |
17c76198 | 525 | debug_printf("D-H parameter cache file \"%s\" does not exist\n", filename); |
182ad5cf PH |
526 | } |
527 | else | |
17c76198 PP |
528 | return tls_error(string_open_failed(errno, "\"%s\" for reading", filename), |
529 | NULL, NULL); | |
b5aea5e1 PH |
530 | |
531 | /* If ret < 0, either the cache file does not exist, or the data it contains | |
532 | is not useful. One particular case of this is when upgrading from an older | |
533 | release of Exim in which the data was stored in a different format. We don't | |
534 | try to be clever and support both formats; we just regenerate new data in this | |
535 | case. */ | |
536 | ||
17c76198 | 537 | if (rc < 0) |
b5aea5e1 | 538 | { |
17c76198 | 539 | uschar *temp_fn; |
201f5254 | 540 | unsigned int dh_bits_gen = dh_bits; |
059ec3d9 | 541 | |
17c76198 PP |
542 | if ((PATH_MAX - Ustrlen(filename)) < 10) |
543 | return tls_error(US"Filename too long to generate replacement", | |
544 | CS filename, NULL); | |
059ec3d9 | 545 | |
17c76198 PP |
546 | temp_fn = string_copy(US "%s.XXXXXXX"); |
547 | fd = mkstemp(CS temp_fn); /* modifies temp_fn */ | |
059ec3d9 | 548 | if (fd < 0) |
17c76198 | 549 | return tls_error(US"Unable to open temp file", strerror(errno), NULL); |
059ec3d9 PH |
550 | (void)fchown(fd, exim_uid, exim_gid); /* Probably not necessary */ |
551 | ||
201f5254 PP |
552 | /* GnuTLS overshoots! |
553 | * If we ask for 2236, we might get 2237 or more. | |
554 | * But there's no way to ask GnuTLS how many bits there really are. | |
555 | * We can ask how many bits were used in a TLS session, but that's it! | |
556 | * The prime itself is hidden behind too much abstraction. | |
557 | * So we ask for less, and proceed on a wing and a prayer. | |
558 | * First attempt, subtracted 3 for 2233 and got 2240. | |
559 | */ | |
cae6e576 | 560 | if (dh_bits >= EXIM_CLIENT_DH_MIN_BITS + 10) |
201f5254 PP |
561 | { |
562 | dh_bits_gen = dh_bits - 10; | |
563 | DEBUG(D_tls) | |
564 | debug_printf("being paranoid about DH generation, make it '%d' bits'\n", | |
565 | dh_bits_gen); | |
566 | } | |
567 | ||
568 | DEBUG(D_tls) | |
569 | debug_printf("requesting generation of %d bit Diffie-Hellman prime ...\n", | |
570 | dh_bits_gen); | |
571 | rc = gnutls_dh_params_generate2(dh_server_params, dh_bits_gen); | |
17c76198 PP |
572 | exim_gnutls_err_check(US"gnutls_dh_params_generate2"); |
573 | ||
574 | /* gnutls_dh_params_export_pkcs3() will tell us the exact size, every time, | |
575 | and I confirmed that a NULL call to get the size first is how the GnuTLS | |
576 | sample apps handle this. */ | |
577 | ||
578 | sz = 0; | |
579 | m.data = NULL; | |
580 | rc = gnutls_dh_params_export_pkcs3(dh_server_params, GNUTLS_X509_FMT_PEM, | |
581 | m.data, &sz); | |
582 | if (rc != GNUTLS_E_SHORT_MEMORY_BUFFER) | |
583 | exim_gnutls_err_check(US"gnutls_dh_params_export_pkcs3(NULL) sizing"); | |
584 | m.size = sz; | |
b5aea5e1 PH |
585 | m.data = malloc(m.size); |
586 | if (m.data == NULL) | |
17c76198 | 587 | return tls_error(US"memory allocation failed", strerror(errno), NULL); |
1f00591e | 588 | /* this will return a size 1 less than the allocation size above */ |
17c76198 | 589 | rc = gnutls_dh_params_export_pkcs3(dh_server_params, GNUTLS_X509_FMT_PEM, |
1f00591e | 590 | m.data, &sz); |
17c76198 PP |
591 | if (rc != GNUTLS_E_SUCCESS) |
592 | { | |
593 | free(m.data); | |
594 | exim_gnutls_err_check(US"gnutls_dh_params_export_pkcs3() real"); | |
595 | } | |
1f00591e | 596 | m.size = sz; /* shrink by 1, probably */ |
059ec3d9 | 597 | |
17c76198 PP |
598 | sz = write_to_fd_buf(fd, m.data, (size_t) m.size); |
599 | if (sz != m.size) | |
600 | { | |
601 | free(m.data); | |
602 | return tls_error(US"TLS cache write D-H params failed", | |
603 | strerror(errno), NULL); | |
604 | } | |
b5aea5e1 | 605 | free(m.data); |
17c76198 PP |
606 | sz = write_to_fd_buf(fd, US"\n", 1); |
607 | if (sz != 1) | |
608 | return tls_error(US"TLS cache write D-H params final newline failed", | |
609 | strerror(errno), NULL); | |
610 | ||
611 | rc = close(fd); | |
612 | if (rc) | |
613 | return tls_error(US"TLS cache write close() failed", | |
614 | strerror(errno), NULL); | |
059ec3d9 | 615 | |
17c76198 PP |
616 | if (Urename(temp_fn, filename) < 0) |
617 | return tls_error(string_sprintf("failed to rename \"%s\" as \"%s\"", | |
618 | temp_fn, filename), strerror(errno), NULL); | |
059ec3d9 | 619 | |
17c76198 | 620 | DEBUG(D_tls) debug_printf("wrote D-H parameters to file \"%s\"\n", filename); |
059ec3d9 PH |
621 | } |
622 | ||
17c76198 | 623 | DEBUG(D_tls) debug_printf("initialized server D-H parameters\n"); |
059ec3d9 PH |
624 | return OK; |
625 | } | |
626 | ||
627 | ||
628 | ||
629 | ||
630 | /************************************************* | |
17c76198 | 631 | * Variables re-expanded post-SNI * |
059ec3d9 PH |
632 | *************************************************/ |
633 | ||
17c76198 PP |
634 | /* Called from both server and client code, via tls_init(), and also from |
635 | the SNI callback after receiving an SNI, if tls_certificate includes "tls_sni". | |
636 | ||
637 | We can tell the two apart by state->received_sni being non-NULL in callback. | |
638 | ||
639 | The callback should not call us unless state->trigger_sni_changes is true, | |
640 | which we are responsible for setting on the first pass through. | |
059ec3d9 PH |
641 | |
642 | Arguments: | |
17c76198 | 643 | state exim_gnutls_state_st * |
059ec3d9 PH |
644 | |
645 | Returns: OK/DEFER/FAIL | |
646 | */ | |
647 | ||
648 | static int | |
17c76198 | 649 | tls_expand_session_files(exim_gnutls_state_st *state) |
059ec3d9 | 650 | { |
1365611d | 651 | struct stat statbuf; |
059ec3d9 | 652 | int rc; |
17c76198 PP |
653 | const host_item *host = state->host; /* macro should be reconsidered? */ |
654 | uschar *saved_tls_certificate = NULL; | |
655 | uschar *saved_tls_privatekey = NULL; | |
656 | uschar *saved_tls_verify_certificates = NULL; | |
657 | uschar *saved_tls_crl = NULL; | |
658 | int cert_count; | |
659 | ||
660 | /* We check for tls_sni *before* expansion. */ | |
661 | if (!state->host) | |
662 | { | |
663 | if (!state->received_sni) | |
664 | { | |
d9b2312b JH |
665 | if (state->tls_certificate && |
666 | (Ustrstr(state->tls_certificate, US"tls_sni") || | |
667 | Ustrstr(state->tls_certificate, US"tls_in_sni") || | |
668 | Ustrstr(state->tls_certificate, US"tls_out_sni") | |
669 | )) | |
17c76198 PP |
670 | { |
671 | DEBUG(D_tls) debug_printf("We will re-expand TLS session files if we receive SNI.\n"); | |
672 | state->trigger_sni_changes = TRUE; | |
673 | } | |
674 | } | |
675 | else | |
676 | { | |
1365611d | 677 | /* useful for debugging */ |
17c76198 PP |
678 | saved_tls_certificate = state->exp_tls_certificate; |
679 | saved_tls_privatekey = state->exp_tls_privatekey; | |
680 | saved_tls_verify_certificates = state->exp_tls_verify_certificates; | |
681 | saved_tls_crl = state->exp_tls_crl; | |
682 | } | |
683 | } | |
059ec3d9 | 684 | |
1365611d PP |
685 | rc = gnutls_certificate_allocate_credentials(&state->x509_cred); |
686 | exim_gnutls_err_check(US"gnutls_certificate_allocate_credentials"); | |
687 | ||
17c76198 PP |
688 | /* remember: expand_check_tlsvar() is expand_check() but fiddling with |
689 | state members, assuming consistent naming; and expand_check() returns | |
690 | false if expansion failed, unless expansion was forced to fail. */ | |
059ec3d9 | 691 | |
17c76198 PP |
692 | /* check if we at least have a certificate, before doing expensive |
693 | D-H generation. */ | |
059ec3d9 | 694 | |
17c76198 PP |
695 | if (!expand_check_tlsvar(tls_certificate)) |
696 | return DEFER; | |
059ec3d9 | 697 | |
17c76198 | 698 | /* certificate is mandatory in server, optional in client */ |
059ec3d9 | 699 | |
17c76198 PP |
700 | if ((state->exp_tls_certificate == NULL) || |
701 | (*state->exp_tls_certificate == '\0')) | |
702 | { | |
703 | if (state->host == NULL) | |
704 | return tls_error(US"no TLS server certificate is specified", NULL, NULL); | |
705 | else | |
706 | DEBUG(D_tls) debug_printf("TLS: no client certificate specified; okay\n"); | |
707 | } | |
059ec3d9 | 708 | |
17c76198 | 709 | if (state->tls_privatekey && !expand_check_tlsvar(tls_privatekey)) |
059ec3d9 PH |
710 | return DEFER; |
711 | ||
17c76198 PP |
712 | /* tls_privatekey is optional, defaulting to same file as certificate */ |
713 | ||
714 | if (state->tls_privatekey == NULL || *state->tls_privatekey == '\0') | |
059ec3d9 | 715 | { |
17c76198 PP |
716 | state->tls_privatekey = state->tls_certificate; |
717 | state->exp_tls_privatekey = state->exp_tls_certificate; | |
059ec3d9 | 718 | } |
c91535f3 | 719 | |
059ec3d9 | 720 | |
17c76198 | 721 | if (state->exp_tls_certificate && *state->exp_tls_certificate) |
059ec3d9 PH |
722 | { |
723 | DEBUG(D_tls) debug_printf("certificate file = %s\nkey file = %s\n", | |
17c76198 PP |
724 | state->exp_tls_certificate, state->exp_tls_privatekey); |
725 | ||
726 | if (state->received_sni) | |
de365ded | 727 | { |
17c76198 PP |
728 | if ((Ustrcmp(state->exp_tls_certificate, saved_tls_certificate) == 0) && |
729 | (Ustrcmp(state->exp_tls_privatekey, saved_tls_privatekey) == 0)) | |
730 | { | |
b34fc30c | 731 | DEBUG(D_tls) debug_printf("TLS SNI: cert and key unchanged\n"); |
17c76198 PP |
732 | } |
733 | else | |
734 | { | |
b34fc30c | 735 | DEBUG(D_tls) debug_printf("TLS SNI: have a changed cert/key pair.\n"); |
17c76198 | 736 | } |
8e669ac1 | 737 | } |
059ec3d9 | 738 | |
1365611d PP |
739 | rc = gnutls_certificate_set_x509_key_file(state->x509_cred, |
740 | CS state->exp_tls_certificate, CS state->exp_tls_privatekey, | |
741 | GNUTLS_X509_FMT_PEM); | |
742 | exim_gnutls_err_check( | |
743 | string_sprintf("cert/key setup: cert=%s key=%s", | |
744 | state->exp_tls_certificate, state->exp_tls_privatekey)); | |
745 | DEBUG(D_tls) debug_printf("TLS: cert/key registered\n"); | |
b34fc30c | 746 | } /* tls_certificate */ |
059ec3d9 PH |
747 | |
748 | /* Set the trusted CAs file if one is provided, and then add the CRL if one is | |
749 | provided. Experiment shows that, if the certificate file is empty, an unhelpful | |
750 | error message is provided. However, if we just refrain from setting anything up | |
751 | in that case, certificate verification fails, which seems to be the correct | |
752 | behaviour. */ | |
753 | ||
17c76198 | 754 | if (state->tls_verify_certificates && *state->tls_verify_certificates) |
059ec3d9 | 755 | { |
17c76198 | 756 | if (!expand_check_tlsvar(tls_verify_certificates)) |
059ec3d9 | 757 | return DEFER; |
17c76198 PP |
758 | if (state->tls_crl && *state->tls_crl) |
759 | if (!expand_check_tlsvar(tls_crl)) | |
760 | return DEFER; | |
059ec3d9 | 761 | |
1365611d PP |
762 | if (!(state->exp_tls_verify_certificates && |
763 | *state->exp_tls_verify_certificates)) | |
b34fc30c PP |
764 | { |
765 | DEBUG(D_tls) | |
1365611d PP |
766 | debug_printf("TLS: tls_verify_certificates expanded empty, ignoring\n"); |
767 | /* With no tls_verify_certificates, we ignore tls_crl too */ | |
17c76198 | 768 | return OK; |
b34fc30c | 769 | } |
1365611d | 770 | } |
83e2f8a2 PP |
771 | else |
772 | { | |
773 | DEBUG(D_tls) | |
774 | debug_printf("TLS: tls_verify_certificates not set or empty, ignoring\n"); | |
775 | return OK; | |
776 | } | |
17c76198 | 777 | |
1365611d PP |
778 | if (Ustat(state->exp_tls_verify_certificates, &statbuf) < 0) |
779 | { | |
780 | log_write(0, LOG_MAIN|LOG_PANIC, "could not stat %s " | |
781 | "(tls_verify_certificates): %s", state->exp_tls_verify_certificates, | |
782 | strerror(errno)); | |
783 | return DEFER; | |
784 | } | |
17c76198 | 785 | |
619b2b25 PP |
786 | /* The test suite passes in /dev/null; we could check for that path explicitly, |
787 | but who knows if someone has some weird FIFO which always dumps some certs, or | |
788 | other weirdness. The thing we really want to check is that it's not a | |
789 | directory, since while OpenSSL supports that, GnuTLS does not. | |
790 | So s/!S_ISREG/S_ISDIR/ and change some messsaging ... */ | |
791 | if (S_ISDIR(statbuf.st_mode)) | |
1365611d PP |
792 | { |
793 | DEBUG(D_tls) | |
619b2b25 PP |
794 | debug_printf("verify certificates path is a dir: \"%s\"\n", |
795 | state->exp_tls_verify_certificates); | |
1365611d | 796 | log_write(0, LOG_MAIN|LOG_PANIC, |
619b2b25 | 797 | "tls_verify_certificates \"%s\" is a directory", |
1365611d PP |
798 | state->exp_tls_verify_certificates); |
799 | return DEFER; | |
800 | } | |
059ec3d9 | 801 | |
1365611d PP |
802 | DEBUG(D_tls) debug_printf("verify certificates = %s size=" OFF_T_FMT "\n", |
803 | state->exp_tls_verify_certificates, statbuf.st_size); | |
059ec3d9 | 804 | |
1365611d PP |
805 | if (statbuf.st_size == 0) |
806 | { | |
807 | DEBUG(D_tls) | |
808 | debug_printf("cert file empty, no certs, no verification, ignoring any CRL\n"); | |
809 | return OK; | |
810 | } | |
059ec3d9 | 811 | |
1365611d PP |
812 | cert_count = gnutls_certificate_set_x509_trust_file(state->x509_cred, |
813 | CS state->exp_tls_verify_certificates, GNUTLS_X509_FMT_PEM); | |
814 | if (cert_count < 0) | |
815 | { | |
816 | rc = cert_count; | |
817 | exim_gnutls_err_check(US"gnutls_certificate_set_x509_trust_file"); | |
818 | } | |
819 | DEBUG(D_tls) debug_printf("Added %d certificate authorities.\n", cert_count); | |
059ec3d9 | 820 | |
5c8cda3a PP |
821 | if (state->tls_crl && *state->tls_crl && |
822 | state->exp_tls_crl && *state->exp_tls_crl) | |
1365611d | 823 | { |
5c8cda3a PP |
824 | DEBUG(D_tls) debug_printf("loading CRL file = %s\n", state->exp_tls_crl); |
825 | cert_count = gnutls_certificate_set_x509_crl_file(state->x509_cred, | |
826 | CS state->exp_tls_crl, GNUTLS_X509_FMT_PEM); | |
827 | if (cert_count < 0) | |
1365611d | 828 | { |
5c8cda3a | 829 | rc = cert_count; |
1365611d PP |
830 | exim_gnutls_err_check(US"gnutls_certificate_set_x509_crl_file"); |
831 | } | |
5c8cda3a | 832 | DEBUG(D_tls) debug_printf("Processed %d CRLs.\n", cert_count); |
1365611d | 833 | } |
059ec3d9 | 834 | |
059ec3d9 PH |
835 | return OK; |
836 | } | |
837 | ||
838 | ||
839 | ||
840 | ||
1365611d PP |
841 | /************************************************* |
842 | * Set X.509 state variables * | |
843 | *************************************************/ | |
844 | ||
845 | /* In GnuTLS, the registered cert/key are not replaced by a later | |
846 | set of a cert/key, so for SNI support we need a whole new x509_cred | |
847 | structure. Which means various other non-re-expanded pieces of state | |
848 | need to be re-set in the new struct, so the setting logic is pulled | |
849 | out to this. | |
850 | ||
851 | Arguments: | |
852 | state exim_gnutls_state_st * | |
853 | ||
854 | Returns: OK/DEFER/FAIL | |
855 | */ | |
856 | ||
857 | static int | |
858 | tls_set_remaining_x509(exim_gnutls_state_st *state) | |
859 | { | |
860 | int rc; | |
861 | const host_item *host = state->host; /* macro should be reconsidered? */ | |
862 | ||
863 | /* Create D-H parameters, or read them from the cache file. This function does | |
864 | its own SMTP error messaging. This only happens for the server, TLS D-H ignores | |
865 | client-side params. */ | |
866 | ||
867 | if (!state->host) | |
868 | { | |
869 | if (!dh_server_params) | |
870 | { | |
871 | rc = init_server_dh(); | |
872 | if (rc != OK) return rc; | |
873 | } | |
874 | gnutls_certificate_set_dh_params(state->x509_cred, dh_server_params); | |
875 | } | |
876 | ||
877 | /* Link the credentials to the session. */ | |
878 | ||
879 | rc = gnutls_credentials_set(state->session, GNUTLS_CRD_CERTIFICATE, state->x509_cred); | |
880 | exim_gnutls_err_check(US"gnutls_credentials_set"); | |
881 | ||
882 | return OK; | |
883 | } | |
884 | ||
059ec3d9 | 885 | /************************************************* |
17c76198 | 886 | * Initialize for GnuTLS * |
059ec3d9 PH |
887 | *************************************************/ |
888 | ||
17c76198 PP |
889 | /* Called from both server and client code. In the case of a server, errors |
890 | before actual TLS negotiation return DEFER. | |
059ec3d9 PH |
891 | |
892 | Arguments: | |
17c76198 PP |
893 | host connected host, if client; NULL if server |
894 | certificate certificate file | |
895 | privatekey private key file | |
896 | sni TLS SNI to send, sometimes when client; else NULL | |
897 | cas CA certs file | |
898 | crl CRL file | |
899 | require_ciphers tls_require_ciphers setting | |
817d9f57 | 900 | caller_state returned state-info structure |
059ec3d9 | 901 | |
17c76198 | 902 | Returns: OK/DEFER/FAIL |
059ec3d9 PH |
903 | */ |
904 | ||
17c76198 PP |
905 | static int |
906 | tls_init( | |
907 | const host_item *host, | |
908 | const uschar *certificate, | |
909 | const uschar *privatekey, | |
910 | const uschar *sni, | |
911 | const uschar *cas, | |
912 | const uschar *crl, | |
913 | const uschar *require_ciphers, | |
914 | exim_gnutls_state_st **caller_state) | |
059ec3d9 | 915 | { |
17c76198 PP |
916 | exim_gnutls_state_st *state; |
917 | int rc; | |
918 | size_t sz; | |
919 | const char *errpos; | |
920 | uschar *p; | |
921 | BOOL want_default_priorities; | |
922 | ||
923 | if (!exim_gnutls_base_init_done) | |
059ec3d9 | 924 | { |
17c76198 PP |
925 | DEBUG(D_tls) debug_printf("GnuTLS global init required.\n"); |
926 | ||
a5f239e4 PP |
927 | #ifdef HAVE_GNUTLS_PKCS11 |
928 | /* By default, gnutls_global_init will init PKCS11 support in auto mode, | |
929 | which loads modules from a config file, which sounds good and may be wanted | |
930 | by some sysadmin, but also means in common configurations that GNOME keyring | |
931 | environment variables are used and so breaks for users calling mailq. | |
932 | To prevent this, we init PKCS11 first, which is the documented approach. */ | |
2519e60d | 933 | if (!gnutls_allow_auto_pkcs11) |
a5f239e4 PP |
934 | { |
935 | rc = gnutls_pkcs11_init(GNUTLS_PKCS11_FLAG_MANUAL, NULL); | |
936 | exim_gnutls_err_check(US"gnutls_pkcs11_init"); | |
937 | } | |
938 | #endif | |
939 | ||
17c76198 PP |
940 | rc = gnutls_global_init(); |
941 | exim_gnutls_err_check(US"gnutls_global_init"); | |
942 | ||
943 | #if EXIM_GNUTLS_LIBRARY_LOG_LEVEL >= 0 | |
944 | DEBUG(D_tls) | |
059ec3d9 | 945 | { |
17c76198 PP |
946 | gnutls_global_set_log_function(exim_gnutls_logger_cb); |
947 | /* arbitrarily chosen level; bump upto 9 for more */ | |
948 | gnutls_global_set_log_level(EXIM_GNUTLS_LIBRARY_LOG_LEVEL); | |
059ec3d9 | 949 | } |
17c76198 PP |
950 | #endif |
951 | ||
952 | exim_gnutls_base_init_done = TRUE; | |
059ec3d9 | 953 | } |
059ec3d9 | 954 | |
17c76198 PP |
955 | if (host) |
956 | { | |
957 | state = &state_client; | |
958 | memcpy(state, &exim_gnutls_state_init, sizeof(exim_gnutls_state_init)); | |
817d9f57 | 959 | state->tlsp = &tls_out; |
17c76198 PP |
960 | DEBUG(D_tls) debug_printf("initialising GnuTLS client session\n"); |
961 | rc = gnutls_init(&state->session, GNUTLS_CLIENT); | |
962 | } | |
963 | else | |
964 | { | |
965 | state = &state_server; | |
966 | memcpy(state, &exim_gnutls_state_init, sizeof(exim_gnutls_state_init)); | |
817d9f57 | 967 | state->tlsp = &tls_in; |
17c76198 PP |
968 | DEBUG(D_tls) debug_printf("initialising GnuTLS server session\n"); |
969 | rc = gnutls_init(&state->session, GNUTLS_SERVER); | |
970 | } | |
971 | exim_gnutls_err_check(US"gnutls_init"); | |
059ec3d9 | 972 | |
17c76198 | 973 | state->host = host; |
059ec3d9 | 974 | |
17c76198 PP |
975 | state->tls_certificate = certificate; |
976 | state->tls_privatekey = privatekey; | |
5779e6aa | 977 | state->tls_require_ciphers = require_ciphers; |
17c76198 PP |
978 | state->tls_sni = sni; |
979 | state->tls_verify_certificates = cas; | |
980 | state->tls_crl = crl; | |
059ec3d9 | 981 | |
17c76198 PP |
982 | /* This handles the variables that might get re-expanded after TLS SNI; |
983 | that's tls_certificate, tls_privatekey, tls_verify_certificates, tls_crl */ | |
059ec3d9 | 984 | |
17c76198 PP |
985 | DEBUG(D_tls) |
986 | debug_printf("Expanding various TLS configuration options for session credentials.\n"); | |
987 | rc = tls_expand_session_files(state); | |
988 | if (rc != OK) return rc; | |
059ec3d9 | 989 | |
1365611d PP |
990 | /* These are all other parts of the x509_cred handling, since SNI in GnuTLS |
991 | requires a new structure afterwards. */ | |
83da1223 | 992 | |
1365611d PP |
993 | rc = tls_set_remaining_x509(state); |
994 | if (rc != OK) return rc; | |
83da1223 | 995 | |
17c76198 PP |
996 | /* set SNI in client, only */ |
997 | if (host) | |
998 | { | |
a5f239e4 | 999 | if (!expand_check(state->tlsp->sni, US"tls_out_sni", &state->exp_tls_sni)) |
17c76198 PP |
1000 | return DEFER; |
1001 | if (state->exp_tls_sni && *state->exp_tls_sni) | |
1002 | { | |
1003 | DEBUG(D_tls) | |
1004 | debug_printf("Setting TLS client SNI to \"%s\"\n", state->exp_tls_sni); | |
1005 | sz = Ustrlen(state->exp_tls_sni); | |
1006 | rc = gnutls_server_name_set(state->session, | |
1007 | GNUTLS_NAME_DNS, state->exp_tls_sni, sz); | |
1008 | exim_gnutls_err_check(US"gnutls_server_name_set"); | |
1009 | } | |
1010 | } | |
1011 | else if (state->tls_sni) | |
1012 | DEBUG(D_tls) debug_printf("*** PROBABLY A BUG *** " \ | |
1013 | "have an SNI set for a client [%s]\n", state->tls_sni); | |
83da1223 | 1014 | |
17c76198 | 1015 | /* This is the priority string support, |
42bfef1e | 1016 | http://www.gnutls.org/manual/html_node/Priority-Strings.html |
17c76198 PP |
1017 | and replaces gnutls_require_kx, gnutls_require_mac & gnutls_require_protocols. |
1018 | This was backwards incompatible, but means Exim no longer needs to track | |
1019 | all algorithms and provide string forms for them. */ | |
83da1223 | 1020 | |
17c76198 | 1021 | want_default_priorities = TRUE; |
83da1223 | 1022 | |
17c76198 | 1023 | if (state->tls_require_ciphers && *state->tls_require_ciphers) |
83da1223 | 1024 | { |
17c76198 PP |
1025 | if (!expand_check_tlsvar(tls_require_ciphers)) |
1026 | return DEFER; | |
1027 | if (state->exp_tls_require_ciphers && *state->exp_tls_require_ciphers) | |
83da1223 | 1028 | { |
17c76198 PP |
1029 | DEBUG(D_tls) debug_printf("GnuTLS session cipher/priority \"%s\"\n", |
1030 | state->exp_tls_require_ciphers); | |
1031 | ||
1032 | rc = gnutls_priority_init(&state->priority_cache, | |
1033 | CS state->exp_tls_require_ciphers, &errpos); | |
1034 | want_default_priorities = FALSE; | |
1035 | p = state->exp_tls_require_ciphers; | |
83da1223 PH |
1036 | } |
1037 | } | |
17c76198 PP |
1038 | if (want_default_priorities) |
1039 | { | |
83e2f8a2 PP |
1040 | DEBUG(D_tls) |
1041 | debug_printf("GnuTLS using default session cipher/priority \"%s\"\n", | |
1042 | exim_default_gnutls_priority); | |
17c76198 PP |
1043 | rc = gnutls_priority_init(&state->priority_cache, |
1044 | exim_default_gnutls_priority, &errpos); | |
1045 | p = US exim_default_gnutls_priority; | |
1046 | } | |
83da1223 | 1047 | |
17c76198 PP |
1048 | exim_gnutls_err_check(string_sprintf( |
1049 | "gnutls_priority_init(%s) failed at offset %ld, \"%.6s..\"", | |
1050 | p, errpos - CS p, errpos)); | |
1051 | ||
1052 | rc = gnutls_priority_set(state->session, state->priority_cache); | |
1053 | exim_gnutls_err_check(US"gnutls_priority_set"); | |
1054 | ||
1055 | gnutls_db_set_cache_expiration(state->session, ssl_session_timeout); | |
1056 | ||
1057 | /* Reduce security in favour of increased compatibility, if the admin | |
1058 | decides to make that trade-off. */ | |
1059 | if (gnutls_compat_mode) | |
83da1223 | 1060 | { |
17c76198 PP |
1061 | #if LIBGNUTLS_VERSION_NUMBER >= 0x020104 |
1062 | DEBUG(D_tls) debug_printf("lowering GnuTLS security, compatibility mode\n"); | |
1063 | gnutls_session_enable_compatibility_mode(state->session); | |
1064 | #else | |
1065 | DEBUG(D_tls) debug_printf("Unable to set gnutls_compat_mode - GnuTLS version too old\n"); | |
1066 | #endif | |
83da1223 PH |
1067 | } |
1068 | ||
17c76198 | 1069 | *caller_state = state; |
17c76198 | 1070 | return OK; |
83da1223 PH |
1071 | } |
1072 | ||
1073 | ||
1074 | ||
1075 | ||
059ec3d9 | 1076 | /************************************************* |
17c76198 | 1077 | * Extract peer information * |
059ec3d9 PH |
1078 | *************************************************/ |
1079 | ||
17c76198 | 1080 | /* Called from both server and client code. |
4fe99a6c PP |
1081 | Only this is allowed to set state->peerdn and state->have_set_peerdn |
1082 | and we use that to detect double-calls. | |
059ec3d9 | 1083 | |
75fe387d PP |
1084 | NOTE: the state blocks last while the TLS connection is up, which is fine |
1085 | for logging in the server side, but for the client side, we log after teardown | |
1086 | in src/deliver.c. While the session is up, we can twist about states and | |
1087 | repoint tls_* globals, but those variables used for logging or other variable | |
1088 | expansion that happens _after_ delivery need to have a longer life-time. | |
1089 | ||
1090 | So for those, we get the data from POOL_PERM; the re-invoke guard keeps us from | |
1091 | doing this more than once per generation of a state context. We set them in | |
1092 | the state context, and repoint tls_* to them. After the state goes away, the | |
1093 | tls_* copies of the pointers remain valid and client delivery logging is happy. | |
1094 | ||
1095 | tls_certificate_verified is a BOOL, so the tls_peerdn and tls_cipher issues | |
1096 | don't apply. | |
1097 | ||
059ec3d9 | 1098 | Arguments: |
17c76198 | 1099 | state exim_gnutls_state_st * |
059ec3d9 | 1100 | |
17c76198 | 1101 | Returns: OK/DEFER/FAIL |
059ec3d9 PH |
1102 | */ |
1103 | ||
17c76198 PP |
1104 | static int |
1105 | peer_status(exim_gnutls_state_st *state) | |
059ec3d9 | 1106 | { |
75fe387d | 1107 | uschar cipherbuf[256]; |
17c76198 | 1108 | const gnutls_datum *cert_list; |
75fe387d | 1109 | int old_pool, rc; |
17c76198 | 1110 | unsigned int cert_list_size = 0; |
4fe99a6c PP |
1111 | gnutls_protocol_t protocol; |
1112 | gnutls_cipher_algorithm_t cipher; | |
1113 | gnutls_kx_algorithm_t kx; | |
1114 | gnutls_mac_algorithm_t mac; | |
17c76198 PP |
1115 | gnutls_certificate_type_t ct; |
1116 | gnutls_x509_crt_t crt; | |
4fe99a6c | 1117 | uschar *p, *dn_buf; |
17c76198 | 1118 | size_t sz; |
059ec3d9 | 1119 | |
4fe99a6c | 1120 | if (state->have_set_peerdn) |
17c76198 | 1121 | return OK; |
4fe99a6c | 1122 | state->have_set_peerdn = TRUE; |
059ec3d9 | 1123 | |
4fe99a6c | 1124 | state->peerdn = NULL; |
059ec3d9 | 1125 | |
4fe99a6c PP |
1126 | /* tls_cipher */ |
1127 | cipher = gnutls_cipher_get(state->session); | |
1128 | protocol = gnutls_protocol_get_version(state->session); | |
1129 | mac = gnutls_mac_get(state->session); | |
1130 | kx = gnutls_kx_get(state->session); | |
1131 | ||
75fe387d | 1132 | string_format(cipherbuf, sizeof(cipherbuf), |
4fe99a6c PP |
1133 | "%s:%s:%d", |
1134 | gnutls_protocol_get_name(protocol), | |
1135 | gnutls_cipher_suite_get_name(kx, cipher, mac), | |
1136 | (int) gnutls_cipher_get_key_size(cipher) * 8); | |
1137 | ||
1138 | /* I don't see a way that spaces could occur, in the current GnuTLS | |
1139 | code base, but it was a concern in the old code and perhaps older GnuTLS | |
1140 | releases did return "TLS 1.0"; play it safe, just in case. */ | |
75fe387d | 1141 | for (p = cipherbuf; *p != '\0'; ++p) |
4fe99a6c PP |
1142 | if (isspace(*p)) |
1143 | *p = '-'; | |
75fe387d PP |
1144 | old_pool = store_pool; |
1145 | store_pool = POOL_PERM; | |
1146 | state->ciphersuite = string_copy(cipherbuf); | |
1147 | store_pool = old_pool; | |
817d9f57 | 1148 | state->tlsp->cipher = state->ciphersuite; |
4fe99a6c PP |
1149 | |
1150 | /* tls_peerdn */ | |
17c76198 | 1151 | cert_list = gnutls_certificate_get_peers(state->session, &cert_list_size); |
83da1223 | 1152 | |
17c76198 PP |
1153 | if (cert_list == NULL || cert_list_size == 0) |
1154 | { | |
17c76198 PP |
1155 | DEBUG(D_tls) debug_printf("TLS: no certificate from peer (%p & %d)\n", |
1156 | cert_list, cert_list_size); | |
1157 | if (state->verify_requirement == VERIFY_REQUIRED) | |
1158 | return tls_error(US"certificate verification failed", | |
1159 | "no certificate received from peer", state->host); | |
1160 | return OK; | |
1161 | } | |
059ec3d9 | 1162 | |
17c76198 PP |
1163 | ct = gnutls_certificate_type_get(state->session); |
1164 | if (ct != GNUTLS_CRT_X509) | |
059ec3d9 | 1165 | { |
17c76198 | 1166 | const char *ctn = gnutls_certificate_type_get_name(ct); |
17c76198 PP |
1167 | DEBUG(D_tls) |
1168 | debug_printf("TLS: peer cert not X.509 but instead \"%s\"\n", ctn); | |
1169 | if (state->verify_requirement == VERIFY_REQUIRED) | |
1170 | return tls_error(US"certificate verification not possible, unhandled type", | |
1171 | ctn, state->host); | |
1172 | return OK; | |
83da1223 | 1173 | } |
059ec3d9 | 1174 | |
17c76198 PP |
1175 | #define exim_gnutls_peer_err(Label) do { \ |
1176 | if (rc != GNUTLS_E_SUCCESS) { \ | |
1177 | DEBUG(D_tls) debug_printf("TLS: peer cert problem: %s: %s\n", (Label), gnutls_strerror(rc)); \ | |
1178 | if (state->verify_requirement == VERIFY_REQUIRED) { return tls_error((Label), gnutls_strerror(rc), state->host); } \ | |
1179 | return OK; } } while (0) | |
1180 | ||
1181 | rc = gnutls_x509_crt_init(&crt); | |
1182 | exim_gnutls_peer_err(US"gnutls_x509_crt_init (crt)"); | |
1183 | ||
1184 | rc = gnutls_x509_crt_import(crt, &cert_list[0], GNUTLS_X509_FMT_DER); | |
1185 | exim_gnutls_peer_err(US"failed to import certificate [gnutls_x509_crt_import(cert 0)]"); | |
1186 | sz = 0; | |
1187 | rc = gnutls_x509_crt_get_dn(crt, NULL, &sz); | |
1188 | if (rc != GNUTLS_E_SHORT_MEMORY_BUFFER) | |
83da1223 | 1189 | { |
17c76198 PP |
1190 | exim_gnutls_peer_err(US"getting size for cert DN failed"); |
1191 | return FAIL; /* should not happen */ | |
059ec3d9 | 1192 | } |
17c76198 PP |
1193 | dn_buf = store_get_perm(sz); |
1194 | rc = gnutls_x509_crt_get_dn(crt, CS dn_buf, &sz); | |
1195 | exim_gnutls_peer_err(US"failed to extract certificate DN [gnutls_x509_crt_get_dn(cert 0)]"); | |
1196 | state->peerdn = dn_buf; | |
1197 | ||
1198 | return OK; | |
1199 | #undef exim_gnutls_peer_err | |
1200 | } | |
059ec3d9 | 1201 | |
059ec3d9 | 1202 | |
059ec3d9 | 1203 | |
059ec3d9 | 1204 | |
17c76198 PP |
1205 | /************************************************* |
1206 | * Verify peer certificate * | |
1207 | *************************************************/ | |
059ec3d9 | 1208 | |
17c76198 PP |
1209 | /* Called from both server and client code. |
1210 | *Should* be using a callback registered with | |
1211 | gnutls_certificate_set_verify_function() to fail the handshake if we dislike | |
1212 | the peer information, but that's too new for some OSes. | |
059ec3d9 | 1213 | |
17c76198 PP |
1214 | Arguments: |
1215 | state exim_gnutls_state_st * | |
1216 | error where to put an error message | |
059ec3d9 | 1217 | |
17c76198 PP |
1218 | Returns: |
1219 | FALSE if the session should be rejected | |
1220 | TRUE if the cert is okay or we just don't care | |
1221 | */ | |
059ec3d9 | 1222 | |
17c76198 PP |
1223 | static BOOL |
1224 | verify_certificate(exim_gnutls_state_st *state, const char **error) | |
1225 | { | |
1226 | int rc; | |
1227 | unsigned int verify; | |
1228 | ||
1229 | *error = NULL; | |
1230 | ||
1231 | rc = peer_status(state); | |
1232 | if (rc != OK) | |
e6060e2c | 1233 | { |
17c76198 PP |
1234 | verify = GNUTLS_CERT_INVALID; |
1235 | *error = "not supplied"; | |
1236 | } | |
1237 | else | |
1238 | { | |
1239 | rc = gnutls_certificate_verify_peers2(state->session, &verify); | |
e6060e2c NM |
1240 | } |
1241 | ||
17c76198 PP |
1242 | /* Handle the result of verification. INVALID seems to be set as well |
1243 | as REVOKED, but leave the test for both. */ | |
059ec3d9 | 1244 | |
17c76198 PP |
1245 | if ((rc < 0) || (verify & (GNUTLS_CERT_INVALID|GNUTLS_CERT_REVOKED)) != 0) |
1246 | { | |
1247 | state->peer_cert_verified = FALSE; | |
1248 | if (*error == NULL) | |
1249 | *error = ((verify & GNUTLS_CERT_REVOKED) != 0) ? "revoked" : "invalid"; | |
059ec3d9 | 1250 | |
17c76198 PP |
1251 | DEBUG(D_tls) |
1252 | debug_printf("TLS certificate verification failed (%s): peerdn=%s\n", | |
4fe99a6c | 1253 | *error, state->peerdn ? state->peerdn : US"<unset>"); |
059ec3d9 | 1254 | |
17c76198 PP |
1255 | if (state->verify_requirement == VERIFY_REQUIRED) |
1256 | { | |
1257 | gnutls_alert_send(state->session, GNUTLS_AL_FATAL, GNUTLS_A_BAD_CERTIFICATE); | |
1258 | return FALSE; | |
1259 | } | |
1260 | DEBUG(D_tls) | |
4789da3a | 1261 | debug_printf("TLS verify failure overridden (host in tls_try_verify_hosts)\n"); |
17c76198 PP |
1262 | } |
1263 | else | |
1264 | { | |
1265 | state->peer_cert_verified = TRUE; | |
4fe99a6c PP |
1266 | DEBUG(D_tls) debug_printf("TLS certificate verified: peerdn=%s\n", |
1267 | state->peerdn ? state->peerdn : US"<unset>"); | |
17c76198 | 1268 | } |
059ec3d9 | 1269 | |
817d9f57 | 1270 | state->tlsp->peerdn = state->peerdn; |
059ec3d9 | 1271 | |
17c76198 PP |
1272 | return TRUE; |
1273 | } | |
059ec3d9 | 1274 | |
17c76198 PP |
1275 | |
1276 | ||
1277 | ||
1278 | /* ------------------------------------------------------------------------ */ | |
1279 | /* Callbacks */ | |
1280 | ||
1281 | /* Logging function which can be registered with | |
1282 | * gnutls_global_set_log_function() | |
1283 | * gnutls_global_set_log_level() 0..9 | |
1284 | */ | |
af3498d6 | 1285 | #if EXIM_GNUTLS_LIBRARY_LOG_LEVEL >= 0 |
059ec3d9 | 1286 | static void |
17c76198 | 1287 | exim_gnutls_logger_cb(int level, const char *message) |
059ec3d9 | 1288 | { |
8c79eebf PP |
1289 | size_t len = strlen(message); |
1290 | if (len < 1) | |
1291 | { | |
1292 | DEBUG(D_tls) debug_printf("GnuTLS<%d> empty debug message\n", level); | |
1293 | return; | |
1294 | } | |
1295 | DEBUG(D_tls) debug_printf("GnuTLS<%d>: %s%s", level, message, | |
1296 | message[len-1] == '\n' ? "" : "\n"); | |
17c76198 | 1297 | } |
af3498d6 | 1298 | #endif |
059ec3d9 | 1299 | |
059ec3d9 | 1300 | |
17c76198 PP |
1301 | /* Called after client hello, should handle SNI work. |
1302 | This will always set tls_sni (state->received_sni) if available, | |
1303 | and may trigger presenting different certificates, | |
1304 | if state->trigger_sni_changes is TRUE. | |
059ec3d9 | 1305 | |
17c76198 PP |
1306 | Should be registered with |
1307 | gnutls_handshake_set_post_client_hello_function() | |
059ec3d9 | 1308 | |
17c76198 PP |
1309 | "This callback must return 0 on success or a gnutls error code to terminate the |
1310 | handshake.". | |
059ec3d9 | 1311 | |
17c76198 PP |
1312 | For inability to get SNI information, we return 0. |
1313 | We only return non-zero if re-setup failed. | |
817d9f57 | 1314 | Only used for server-side TLS. |
17c76198 | 1315 | */ |
44bbabb5 | 1316 | |
17c76198 PP |
1317 | static int |
1318 | exim_sni_handling_cb(gnutls_session_t session) | |
1319 | { | |
1320 | char sni_name[MAX_HOST_LEN]; | |
1321 | size_t data_len = MAX_HOST_LEN; | |
817d9f57 | 1322 | exim_gnutls_state_st *state = &state_server; |
17c76198 PP |
1323 | unsigned int sni_type; |
1324 | int rc, old_pool; | |
1325 | ||
1326 | rc = gnutls_server_name_get(session, sni_name, &data_len, &sni_type, 0); | |
b34fc30c PP |
1327 | if (rc != GNUTLS_E_SUCCESS) |
1328 | { | |
1329 | DEBUG(D_tls) { | |
1330 | if (rc == GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE) | |
1331 | debug_printf("TLS: no SNI presented in handshake.\n"); | |
1332 | else | |
1333 | debug_printf("TLS failure: gnutls_server_name_get(): %s [%d]\n", | |
1334 | gnutls_strerror(rc), rc); | |
1335 | }; | |
1336 | return 0; | |
1337 | } | |
1338 | ||
17c76198 PP |
1339 | if (sni_type != GNUTLS_NAME_DNS) |
1340 | { | |
1341 | DEBUG(D_tls) debug_printf("TLS: ignoring SNI of unhandled type %u\n", sni_type); | |
1342 | return 0; | |
1343 | } | |
44bbabb5 | 1344 | |
17c76198 PP |
1345 | /* We now have a UTF-8 string in sni_name */ |
1346 | old_pool = store_pool; | |
1347 | store_pool = POOL_PERM; | |
1348 | state->received_sni = string_copyn(US sni_name, data_len); | |
1349 | store_pool = old_pool; | |
1350 | ||
1351 | /* We set this one now so that variable expansions below will work */ | |
817d9f57 | 1352 | state->tlsp->sni = state->received_sni; |
17c76198 PP |
1353 | |
1354 | DEBUG(D_tls) debug_printf("Received TLS SNI \"%s\"%s\n", sni_name, | |
1355 | state->trigger_sni_changes ? "" : " (unused for certificate selection)"); | |
1356 | ||
1357 | if (!state->trigger_sni_changes) | |
1358 | return 0; | |
1359 | ||
1360 | rc = tls_expand_session_files(state); | |
1361 | if (rc != OK) | |
1362 | { | |
1363 | /* If the setup of certs/etc failed before handshake, TLS would not have | |
1364 | been offered. The best we can do now is abort. */ | |
1365 | return GNUTLS_E_APPLICATION_ERROR_MIN; | |
1366 | } | |
1367 | ||
1365611d PP |
1368 | rc = tls_set_remaining_x509(state); |
1369 | if (rc != OK) return GNUTLS_E_APPLICATION_ERROR_MIN; | |
1370 | ||
1371 | return 0; | |
059ec3d9 PH |
1372 | } |
1373 | ||
1374 | ||
1375 | ||
17c76198 PP |
1376 | |
1377 | /* ------------------------------------------------------------------------ */ | |
1378 | /* Exported functions */ | |
1379 | ||
1380 | ||
1381 | ||
1382 | ||
059ec3d9 PH |
1383 | /************************************************* |
1384 | * Start a TLS session in a server * | |
1385 | *************************************************/ | |
1386 | ||
1387 | /* This is called when Exim is running as a server, after having received | |
1388 | the STARTTLS command. It must respond to that command, and then negotiate | |
1389 | a TLS session. | |
1390 | ||
1391 | Arguments: | |
83da1223 | 1392 | require_ciphers list of allowed ciphers or NULL |
059ec3d9 PH |
1393 | |
1394 | Returns: OK on success | |
1395 | DEFER for errors before the start of the negotiation | |
1396 | FAIL for errors during the negotation; the server can't | |
1397 | continue running. | |
1398 | */ | |
1399 | ||
1400 | int | |
17c76198 | 1401 | tls_server_start(const uschar *require_ciphers) |
059ec3d9 PH |
1402 | { |
1403 | int rc; | |
7199e1ee | 1404 | const char *error; |
17c76198 | 1405 | exim_gnutls_state_st *state = NULL; |
059ec3d9 PH |
1406 | |
1407 | /* Check for previous activation */ | |
817d9f57 | 1408 | if (tls_in.active >= 0) |
059ec3d9 | 1409 | { |
17c76198 | 1410 | tls_error(US"STARTTLS received after TLS started", "", NULL); |
059ec3d9 PH |
1411 | smtp_printf("554 Already in TLS\r\n"); |
1412 | return FAIL; | |
1413 | } | |
1414 | ||
1415 | /* Initialize the library. If it fails, it will already have logged the error | |
1416 | and sent an SMTP response. */ | |
1417 | ||
17c76198 | 1418 | DEBUG(D_tls) debug_printf("initialising GnuTLS as a server\n"); |
059ec3d9 | 1419 | |
17c76198 PP |
1420 | rc = tls_init(NULL, tls_certificate, tls_privatekey, |
1421 | NULL, tls_verify_certificates, tls_crl, | |
1422 | require_ciphers, &state); | |
059ec3d9 PH |
1423 | if (rc != OK) return rc; |
1424 | ||
059ec3d9 PH |
1425 | /* If this is a host for which certificate verification is mandatory or |
1426 | optional, set up appropriately. */ | |
1427 | ||
059ec3d9 | 1428 | if (verify_check_host(&tls_verify_hosts) == OK) |
17c76198 PP |
1429 | { |
1430 | DEBUG(D_tls) debug_printf("TLS: a client certificate will be required.\n"); | |
1431 | state->verify_requirement = VERIFY_REQUIRED; | |
1432 | gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_REQUIRE); | |
1433 | } | |
059ec3d9 | 1434 | else if (verify_check_host(&tls_try_verify_hosts) == OK) |
17c76198 PP |
1435 | { |
1436 | DEBUG(D_tls) debug_printf("TLS: a client certificate will be requested but not required.\n"); | |
1437 | state->verify_requirement = VERIFY_OPTIONAL; | |
1438 | gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_REQUEST); | |
1439 | } | |
1440 | else | |
1441 | { | |
1442 | DEBUG(D_tls) debug_printf("TLS: a client certificate will not be requested.\n"); | |
1443 | state->verify_requirement = VERIFY_NONE; | |
1444 | gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_IGNORE); | |
1445 | } | |
059ec3d9 | 1446 | |
17c76198 PP |
1447 | /* Register SNI handling; always, even if not in tls_certificate, so that the |
1448 | expansion variable $tls_sni is always available. */ | |
059ec3d9 | 1449 | |
17c76198 PP |
1450 | gnutls_handshake_set_post_client_hello_function(state->session, |
1451 | exim_sni_handling_cb); | |
059ec3d9 PH |
1452 | |
1453 | /* Set context and tell client to go ahead, except in the case of TLS startup | |
1454 | on connection, where outputting anything now upsets the clients and tends to | |
1455 | make them disconnect. We need to have an explicit fflush() here, to force out | |
1456 | the response. Other smtp_printf() calls do not need it, because in non-TLS | |
1457 | mode, the fflush() happens when smtp_getc() is called. */ | |
1458 | ||
817d9f57 | 1459 | if (!state->tlsp->on_connect) |
059ec3d9 PH |
1460 | { |
1461 | smtp_printf("220 TLS go ahead\r\n"); | |
817d9f57 | 1462 | fflush(smtp_out); /*XXX JGH */ |
059ec3d9 PH |
1463 | } |
1464 | ||
1465 | /* Now negotiate the TLS session. We put our own timer on it, since it seems | |
1466 | that the GnuTLS library doesn't. */ | |
1467 | ||
17c76198 PP |
1468 | gnutls_transport_set_ptr2(state->session, |
1469 | (gnutls_transport_ptr)fileno(smtp_in), | |
1470 | (gnutls_transport_ptr)fileno(smtp_out)); | |
1471 | state->fd_in = fileno(smtp_in); | |
1472 | state->fd_out = fileno(smtp_out); | |
059ec3d9 PH |
1473 | |
1474 | sigalrm_seen = FALSE; | |
1475 | if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout); | |
17c76198 PP |
1476 | do |
1477 | { | |
1478 | rc = gnutls_handshake(state->session); | |
619b2b25 PP |
1479 | } while ((rc == GNUTLS_E_AGAIN) || |
1480 | (rc == GNUTLS_E_INTERRUPTED && !sigalrm_seen)); | |
059ec3d9 PH |
1481 | alarm(0); |
1482 | ||
17c76198 | 1483 | if (rc != GNUTLS_E_SUCCESS) |
059ec3d9 | 1484 | { |
17c76198 PP |
1485 | tls_error(US"gnutls_handshake", |
1486 | sigalrm_seen ? "timed out" : gnutls_strerror(rc), NULL); | |
059ec3d9 PH |
1487 | /* It seems that, except in the case of a timeout, we have to close the |
1488 | connection right here; otherwise if the other end is running OpenSSL it hangs | |
1489 | until the server times out. */ | |
1490 | ||
1491 | if (!sigalrm_seen) | |
1492 | { | |
f1e894f3 PH |
1493 | (void)fclose(smtp_out); |
1494 | (void)fclose(smtp_in); | |
059ec3d9 PH |
1495 | } |
1496 | ||
1497 | return FAIL; | |
1498 | } | |
1499 | ||
1500 | DEBUG(D_tls) debug_printf("gnutls_handshake was successful\n"); | |
1501 | ||
17c76198 PP |
1502 | /* Verify after the fact */ |
1503 | ||
1504 | if (state->verify_requirement != VERIFY_NONE) | |
059ec3d9 | 1505 | { |
17c76198 PP |
1506 | if (!verify_certificate(state, &error)) |
1507 | { | |
1508 | if (state->verify_requirement == VERIFY_OPTIONAL) | |
1509 | { | |
1510 | DEBUG(D_tls) | |
1511 | debug_printf("TLS: continuing on only because verification was optional, after: %s\n", | |
1512 | error); | |
1513 | } | |
1514 | else | |
1515 | { | |
1516 | tls_error(US"certificate verification failed", error, NULL); | |
1517 | return FAIL; | |
1518 | } | |
1519 | } | |
059ec3d9 PH |
1520 | } |
1521 | ||
17c76198 PP |
1522 | /* Figure out peer DN, and if authenticated, etc. */ |
1523 | ||
1524 | rc = peer_status(state); | |
1525 | if (rc != OK) return rc; | |
1526 | ||
1527 | /* Sets various Exim expansion variables; always safe within server */ | |
1528 | ||
817d9f57 | 1529 | extract_exim_vars_from_tls_state(state, TRUE); |
059ec3d9 PH |
1530 | |
1531 | /* TLS has been set up. Adjust the input functions to read via TLS, | |
1532 | and initialize appropriately. */ | |
1533 | ||
17c76198 | 1534 | state->xfer_buffer = store_malloc(ssl_xfer_buffer_size); |
059ec3d9 PH |
1535 | |
1536 | receive_getc = tls_getc; | |
1537 | receive_ungetc = tls_ungetc; | |
1538 | receive_feof = tls_feof; | |
1539 | receive_ferror = tls_ferror; | |
58eb016e | 1540 | receive_smtp_buffered = tls_smtp_buffered; |
059ec3d9 | 1541 | |
059ec3d9 PH |
1542 | return OK; |
1543 | } | |
1544 | ||
1545 | ||
1546 | ||
1547 | ||
1548 | /************************************************* | |
1549 | * Start a TLS session in a client * | |
1550 | *************************************************/ | |
1551 | ||
1552 | /* Called from the smtp transport after STARTTLS has been accepted. | |
1553 | ||
1554 | Arguments: | |
1555 | fd the fd of the connection | |
1556 | host connected host (for messages) | |
83da1223 | 1557 | addr the first address (not used) |
059ec3d9 PH |
1558 | certificate certificate file |
1559 | privatekey private key file | |
3f0945ff | 1560 | sni TLS SNI to send to remote host |
059ec3d9 PH |
1561 | verify_certs file for certificate verify |
1562 | verify_crl CRL for verify | |
83da1223 | 1563 | require_ciphers list of allowed ciphers or NULL |
54c90be1 | 1564 | dh_min_bits minimum number of bits acceptable in server's DH prime |
059ec3d9 PH |
1565 | timeout startup timeout |
1566 | ||
1567 | Returns: OK/DEFER/FAIL (because using common functions), | |
1568 | but for a client, DEFER and FAIL have the same meaning | |
1569 | */ | |
1570 | ||
1571 | int | |
17c76198 | 1572 | tls_client_start(int fd, host_item *host, |
f5d78688 | 1573 | address_item *addr ARG_UNUSED, |
17c76198 PP |
1574 | uschar *certificate, uschar *privatekey, uschar *sni, |
1575 | uschar *verify_certs, uschar *verify_crl, | |
f5d78688 JH |
1576 | uschar *require_ciphers, |
1577 | #ifdef EXPERIMENTAL_OCSP | |
1578 | uschar *require_ocsp ARG_UNUSED, | |
1579 | #endif | |
1580 | int dh_min_bits, int timeout) | |
059ec3d9 | 1581 | { |
059ec3d9 | 1582 | int rc; |
17c76198 PP |
1583 | const char *error; |
1584 | exim_gnutls_state_st *state = NULL; | |
059ec3d9 | 1585 | |
17c76198 | 1586 | DEBUG(D_tls) debug_printf("initialising GnuTLS as a client on fd %d\n", fd); |
059ec3d9 | 1587 | |
17c76198 PP |
1588 | rc = tls_init(host, certificate, privatekey, |
1589 | sni, verify_certs, verify_crl, require_ciphers, &state); | |
059ec3d9 PH |
1590 | if (rc != OK) return rc; |
1591 | ||
54c90be1 PP |
1592 | if (dh_min_bits < EXIM_CLIENT_DH_MIN_MIN_BITS) |
1593 | { | |
1594 | DEBUG(D_tls) | |
1595 | debug_printf("WARNING: tls_dh_min_bits far too low, clamping %d up to %d\n", | |
1596 | dh_min_bits, EXIM_CLIENT_DH_MIN_MIN_BITS); | |
1597 | dh_min_bits = EXIM_CLIENT_DH_MIN_MIN_BITS; | |
1598 | } | |
1599 | ||
1600 | DEBUG(D_tls) debug_printf("Setting D-H prime minimum acceptable bits to %d\n", | |
1601 | dh_min_bits); | |
1602 | gnutls_dh_set_prime_bits(state->session, dh_min_bits); | |
83da1223 | 1603 | |
b26a34e4 | 1604 | if (state->exp_tls_verify_certificates == NULL) |
17c76198 PP |
1605 | { |
1606 | DEBUG(D_tls) debug_printf("TLS: server certificate verification not required\n"); | |
1607 | state->verify_requirement = VERIFY_NONE; | |
1608 | /* we still ask for it, to log it, etc */ | |
1609 | gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_REQUEST); | |
1610 | } | |
1611 | else | |
1612 | { | |
1613 | DEBUG(D_tls) debug_printf("TLS: server certificate verification required\n"); | |
1614 | state->verify_requirement = VERIFY_REQUIRED; | |
1615 | gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_REQUIRE); | |
1616 | } | |
059ec3d9 | 1617 | |
17c76198 PP |
1618 | gnutls_transport_set_ptr(state->session, (gnutls_transport_ptr)fd); |
1619 | state->fd_in = fd; | |
1620 | state->fd_out = fd; | |
059ec3d9 PH |
1621 | |
1622 | /* There doesn't seem to be a built-in timeout on connection. */ | |
1623 | ||
1624 | sigalrm_seen = FALSE; | |
1625 | alarm(timeout); | |
17c76198 PP |
1626 | do |
1627 | { | |
1628 | rc = gnutls_handshake(state->session); | |
619b2b25 PP |
1629 | } while ((rc == GNUTLS_E_AGAIN) || |
1630 | (rc == GNUTLS_E_INTERRUPTED && !sigalrm_seen)); | |
059ec3d9 PH |
1631 | alarm(0); |
1632 | ||
4fe99a6c PP |
1633 | if (rc != GNUTLS_E_SUCCESS) |
1634 | return tls_error(US"gnutls_handshake", | |
1635 | sigalrm_seen ? "timed out" : gnutls_strerror(rc), state->host); | |
1636 | ||
17c76198 | 1637 | DEBUG(D_tls) debug_printf("gnutls_handshake was successful\n"); |
059ec3d9 | 1638 | |
17c76198 | 1639 | /* Verify late */ |
059ec3d9 | 1640 | |
17c76198 PP |
1641 | if (state->verify_requirement != VERIFY_NONE && |
1642 | !verify_certificate(state, &error)) | |
1643 | return tls_error(US"certificate verification failed", error, state->host); | |
059ec3d9 | 1644 | |
17c76198 | 1645 | /* Figure out peer DN, and if authenticated, etc. */ |
059ec3d9 | 1646 | |
17c76198 PP |
1647 | rc = peer_status(state); |
1648 | if (rc != OK) return rc; | |
059ec3d9 | 1649 | |
4fe99a6c | 1650 | /* Sets various Exim expansion variables; may need to adjust for ACL callouts */ |
059ec3d9 | 1651 | |
817d9f57 | 1652 | extract_exim_vars_from_tls_state(state, FALSE); |
059ec3d9 | 1653 | |
059ec3d9 PH |
1654 | return OK; |
1655 | } | |
1656 | ||
1657 | ||
1658 | ||
17c76198 | 1659 | |
059ec3d9 | 1660 | /************************************************* |
17c76198 | 1661 | * Close down a TLS session * |
059ec3d9 PH |
1662 | *************************************************/ |
1663 | ||
17c76198 PP |
1664 | /* This is also called from within a delivery subprocess forked from the |
1665 | daemon, to shut down the TLS library, without actually doing a shutdown (which | |
1666 | would tamper with the TLS session in the parent process). | |
059ec3d9 | 1667 | |
17c76198 PP |
1668 | Arguments: TRUE if gnutls_bye is to be called |
1669 | Returns: nothing | |
059ec3d9 PH |
1670 | */ |
1671 | ||
17c76198 | 1672 | void |
817d9f57 | 1673 | tls_close(BOOL is_server, BOOL shutdown) |
059ec3d9 | 1674 | { |
817d9f57 | 1675 | exim_gnutls_state_st *state = is_server ? &state_server : &state_client; |
059ec3d9 | 1676 | |
389ca47a | 1677 | if (!state->tlsp || state->tlsp->active < 0) return; /* TLS was not active */ |
17c76198 PP |
1678 | |
1679 | if (shutdown) | |
1680 | { | |
1681 | DEBUG(D_tls) debug_printf("tls_close(): shutting down TLS\n"); | |
1682 | gnutls_bye(state->session, GNUTLS_SHUT_WR); | |
1683 | } | |
1684 | ||
1685 | gnutls_deinit(state->session); | |
1686 | ||
389ca47a | 1687 | state->tlsp->active = -1; |
17c76198 PP |
1688 | memcpy(state, &exim_gnutls_state_init, sizeof(exim_gnutls_state_init)); |
1689 | ||
1690 | if ((state_server.session == NULL) && (state_client.session == NULL)) | |
1691 | { | |
1692 | gnutls_global_deinit(); | |
1693 | exim_gnutls_base_init_done = FALSE; | |
1694 | } | |
7199e1ee | 1695 | |
059ec3d9 PH |
1696 | } |
1697 | ||
1698 | ||
1699 | ||
17c76198 | 1700 | |
059ec3d9 PH |
1701 | /************************************************* |
1702 | * TLS version of getc * | |
1703 | *************************************************/ | |
1704 | ||
1705 | /* This gets the next byte from the TLS input buffer. If the buffer is empty, | |
1706 | it refills the buffer via the GnuTLS reading function. | |
817d9f57 | 1707 | Only used by the server-side TLS. |
059ec3d9 | 1708 | |
17c76198 PP |
1709 | This feeds DKIM and should be used for all message-body reads. |
1710 | ||
059ec3d9 PH |
1711 | Arguments: none |
1712 | Returns: the next character or EOF | |
1713 | */ | |
1714 | ||
1715 | int | |
1716 | tls_getc(void) | |
1717 | { | |
817d9f57 | 1718 | exim_gnutls_state_st *state = &state_server; |
17c76198 | 1719 | if (state->xfer_buffer_lwm >= state->xfer_buffer_hwm) |
059ec3d9 | 1720 | { |
17c76198 | 1721 | ssize_t inbytes; |
059ec3d9 | 1722 | |
17c76198 PP |
1723 | DEBUG(D_tls) debug_printf("Calling gnutls_record_recv(%p, %p, %u)\n", |
1724 | state->session, state->xfer_buffer, ssl_xfer_buffer_size); | |
059ec3d9 PH |
1725 | |
1726 | if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout); | |
17c76198 | 1727 | inbytes = gnutls_record_recv(state->session, state->xfer_buffer, |
059ec3d9 PH |
1728 | ssl_xfer_buffer_size); |
1729 | alarm(0); | |
1730 | ||
1731 | /* A zero-byte return appears to mean that the TLS session has been | |
1732 | closed down, not that the socket itself has been closed down. Revert to | |
1733 | non-TLS handling. */ | |
1734 | ||
1735 | if (inbytes == 0) | |
1736 | { | |
1737 | DEBUG(D_tls) debug_printf("Got TLS_EOF\n"); | |
1738 | ||
1739 | receive_getc = smtp_getc; | |
1740 | receive_ungetc = smtp_ungetc; | |
1741 | receive_feof = smtp_feof; | |
1742 | receive_ferror = smtp_ferror; | |
58eb016e | 1743 | receive_smtp_buffered = smtp_buffered; |
059ec3d9 | 1744 | |
17c76198 PP |
1745 | gnutls_deinit(state->session); |
1746 | state->session = NULL; | |
817d9f57 JH |
1747 | state->tlsp->active = -1; |
1748 | state->tlsp->bits = 0; | |
1749 | state->tlsp->certificate_verified = FALSE; | |
1750 | tls_channelbinding_b64 = NULL; /*XXX JGH */ | |
1751 | state->tlsp->cipher = NULL; | |
1752 | state->tlsp->peerdn = NULL; | |
059ec3d9 PH |
1753 | |
1754 | return smtp_getc(); | |
1755 | } | |
1756 | ||
1757 | /* Handle genuine errors */ | |
1758 | ||
1759 | else if (inbytes < 0) | |
1760 | { | |
17c76198 PP |
1761 | record_io_error(state, (int) inbytes, US"recv", NULL); |
1762 | state->xfer_error = 1; | |
059ec3d9 PH |
1763 | return EOF; |
1764 | } | |
80a47a2c | 1765 | #ifndef DISABLE_DKIM |
17c76198 | 1766 | dkim_exim_verify_feed(state->xfer_buffer, inbytes); |
80a47a2c | 1767 | #endif |
17c76198 PP |
1768 | state->xfer_buffer_hwm = (int) inbytes; |
1769 | state->xfer_buffer_lwm = 0; | |
059ec3d9 PH |
1770 | } |
1771 | ||
059ec3d9 PH |
1772 | /* Something in the buffer; return next uschar */ |
1773 | ||
17c76198 | 1774 | return state->xfer_buffer[state->xfer_buffer_lwm++]; |
059ec3d9 PH |
1775 | } |
1776 | ||
1777 | ||
1778 | ||
17c76198 | 1779 | |
059ec3d9 PH |
1780 | /************************************************* |
1781 | * Read bytes from TLS channel * | |
1782 | *************************************************/ | |
1783 | ||
17c76198 PP |
1784 | /* This does not feed DKIM, so if the caller uses this for reading message body, |
1785 | then the caller must feed DKIM. | |
817d9f57 | 1786 | |
059ec3d9 PH |
1787 | Arguments: |
1788 | buff buffer of data | |
1789 | len size of buffer | |
1790 | ||
1791 | Returns: the number of bytes read | |
1792 | -1 after a failed read | |
1793 | */ | |
1794 | ||
1795 | int | |
817d9f57 | 1796 | tls_read(BOOL is_server, uschar *buff, size_t len) |
059ec3d9 | 1797 | { |
817d9f57 | 1798 | exim_gnutls_state_st *state = is_server ? &state_server : &state_client; |
17c76198 | 1799 | ssize_t inbytes; |
059ec3d9 | 1800 | |
17c76198 PP |
1801 | if (len > INT_MAX) |
1802 | len = INT_MAX; | |
059ec3d9 | 1803 | |
17c76198 PP |
1804 | if (state->xfer_buffer_lwm < state->xfer_buffer_hwm) |
1805 | DEBUG(D_tls) | |
1806 | debug_printf("*** PROBABLY A BUG *** " \ | |
1807 | "tls_read() called with data in the tls_getc() buffer, %d ignored\n", | |
1808 | state->xfer_buffer_hwm - state->xfer_buffer_lwm); | |
1809 | ||
1810 | DEBUG(D_tls) | |
1811 | debug_printf("Calling gnutls_record_recv(%p, %p, " SIZE_T_FMT ")\n", | |
1812 | state->session, buff, len); | |
1813 | ||
1814 | inbytes = gnutls_record_recv(state->session, buff, len); | |
059ec3d9 PH |
1815 | if (inbytes > 0) return inbytes; |
1816 | if (inbytes == 0) | |
1817 | { | |
1818 | DEBUG(D_tls) debug_printf("Got TLS_EOF\n"); | |
1819 | } | |
17c76198 | 1820 | else record_io_error(state, (int)inbytes, US"recv", NULL); |
059ec3d9 PH |
1821 | |
1822 | return -1; | |
1823 | } | |
1824 | ||
1825 | ||
1826 | ||
17c76198 | 1827 | |
059ec3d9 PH |
1828 | /************************************************* |
1829 | * Write bytes down TLS channel * | |
1830 | *************************************************/ | |
1831 | ||
1832 | /* | |
1833 | Arguments: | |
817d9f57 | 1834 | is_server channel specifier |
059ec3d9 PH |
1835 | buff buffer of data |
1836 | len number of bytes | |
1837 | ||
1838 | Returns: the number of bytes after a successful write, | |
1839 | -1 after a failed write | |
1840 | */ | |
1841 | ||
1842 | int | |
817d9f57 | 1843 | tls_write(BOOL is_server, const uschar *buff, size_t len) |
059ec3d9 | 1844 | { |
17c76198 PP |
1845 | ssize_t outbytes; |
1846 | size_t left = len; | |
817d9f57 | 1847 | exim_gnutls_state_st *state = is_server ? &state_server : &state_client; |
059ec3d9 | 1848 | |
17c76198 | 1849 | DEBUG(D_tls) debug_printf("tls_do_write(%p, " SIZE_T_FMT ")\n", buff, left); |
059ec3d9 PH |
1850 | while (left > 0) |
1851 | { | |
17c76198 PP |
1852 | DEBUG(D_tls) debug_printf("gnutls_record_send(SSL, %p, " SIZE_T_FMT ")\n", |
1853 | buff, left); | |
1854 | outbytes = gnutls_record_send(state->session, buff, left); | |
059ec3d9 | 1855 | |
17c76198 | 1856 | DEBUG(D_tls) debug_printf("outbytes=" SSIZE_T_FMT "\n", outbytes); |
059ec3d9 PH |
1857 | if (outbytes < 0) |
1858 | { | |
17c76198 | 1859 | record_io_error(state, outbytes, US"send", NULL); |
059ec3d9 PH |
1860 | return -1; |
1861 | } | |
1862 | if (outbytes == 0) | |
1863 | { | |
17c76198 | 1864 | record_io_error(state, 0, US"send", US"TLS channel closed on write"); |
059ec3d9 PH |
1865 | return -1; |
1866 | } | |
1867 | ||
1868 | left -= outbytes; | |
1869 | buff += outbytes; | |
1870 | } | |
1871 | ||
17c76198 PP |
1872 | if (len > INT_MAX) |
1873 | { | |
1874 | DEBUG(D_tls) | |
1875 | debug_printf("Whoops! Wrote more bytes (" SIZE_T_FMT ") than INT_MAX\n", | |
1876 | len); | |
1877 | len = INT_MAX; | |
1878 | } | |
1879 | ||
1880 | return (int) len; | |
059ec3d9 PH |
1881 | } |
1882 | ||
1883 | ||
1884 | ||
17c76198 | 1885 | |
059ec3d9 | 1886 | /************************************************* |
17c76198 | 1887 | * Random number generation * |
059ec3d9 PH |
1888 | *************************************************/ |
1889 | ||
17c76198 PP |
1890 | /* Pseudo-random number generation. The result is not expected to be |
1891 | cryptographically strong but not so weak that someone will shoot themselves | |
1892 | in the foot using it as a nonce in input in some email header scheme or | |
1893 | whatever weirdness they'll twist this into. The result should handle fork() | |
1894 | and avoid repeating sequences. OpenSSL handles that for us. | |
059ec3d9 | 1895 | |
17c76198 PP |
1896 | Arguments: |
1897 | max range maximum | |
1898 | Returns a random number in range [0, max-1] | |
059ec3d9 PH |
1899 | */ |
1900 | ||
af3498d6 | 1901 | #ifdef HAVE_GNUTLS_RND |
17c76198 PP |
1902 | int |
1903 | vaguely_random_number(int max) | |
059ec3d9 | 1904 | { |
17c76198 PP |
1905 | unsigned int r; |
1906 | int i, needed_len; | |
1907 | uschar *p; | |
1908 | uschar smallbuf[sizeof(r)]; | |
1909 | ||
1910 | if (max <= 1) | |
1911 | return 0; | |
1912 | ||
1913 | needed_len = sizeof(r); | |
1914 | /* Don't take 8 times more entropy than needed if int is 8 octets and we were | |
1915 | * asked for a number less than 10. */ | |
1916 | for (r = max, i = 0; r; ++i) | |
1917 | r >>= 1; | |
1918 | i = (i + 7) / 8; | |
1919 | if (i < needed_len) | |
1920 | needed_len = i; | |
1921 | ||
1922 | i = gnutls_rnd(GNUTLS_RND_NONCE, smallbuf, needed_len); | |
1923 | if (i < 0) | |
059ec3d9 | 1924 | { |
17c76198 PP |
1925 | DEBUG(D_all) debug_printf("gnutls_rnd() failed, using fallback.\n"); |
1926 | return vaguely_random_number_fallback(max); | |
1927 | } | |
1928 | r = 0; | |
1929 | for (p = smallbuf; needed_len; --needed_len, ++p) | |
1930 | { | |
1931 | r *= 256; | |
1932 | r += *p; | |
059ec3d9 PH |
1933 | } |
1934 | ||
17c76198 PP |
1935 | /* We don't particularly care about weighted results; if someone wants |
1936 | * smooth distribution and cares enough then they should submit a patch then. */ | |
1937 | return r % max; | |
059ec3d9 | 1938 | } |
af3498d6 PP |
1939 | #else /* HAVE_GNUTLS_RND */ |
1940 | int | |
1941 | vaguely_random_number(int max) | |
1942 | { | |
1943 | return vaguely_random_number_fallback(max); | |
1944 | } | |
1945 | #endif /* HAVE_GNUTLS_RND */ | |
059ec3d9 | 1946 | |
36f12725 NM |
1947 | |
1948 | ||
1949 | ||
3375e053 PP |
1950 | /************************************************* |
1951 | * Let tls_require_ciphers be checked at startup * | |
1952 | *************************************************/ | |
1953 | ||
1954 | /* The tls_require_ciphers option, if set, must be something which the | |
1955 | library can parse. | |
1956 | ||
1957 | Returns: NULL on success, or error message | |
1958 | */ | |
1959 | ||
1960 | uschar * | |
1961 | tls_validate_require_cipher(void) | |
1962 | { | |
1963 | int rc; | |
1964 | uschar *expciphers = NULL; | |
1965 | gnutls_priority_t priority_cache; | |
1966 | const char *errpos; | |
1967 | ||
1968 | #define validate_check_rc(Label) do { \ | |
1969 | if (rc != GNUTLS_E_SUCCESS) { if (exim_gnutls_base_init_done) gnutls_global_deinit(); \ | |
1970 | return string_sprintf("%s failed: %s", (Label), gnutls_strerror(rc)); } } while (0) | |
1971 | #define return_deinit(Label) do { gnutls_global_deinit(); return (Label); } while (0) | |
1972 | ||
1973 | if (exim_gnutls_base_init_done) | |
1974 | log_write(0, LOG_MAIN|LOG_PANIC, | |
1975 | "already initialised GnuTLS, Exim developer bug"); | |
1976 | ||
a5f239e4 | 1977 | #ifdef HAVE_GNUTLS_PKCS11 |
2519e60d | 1978 | if (!gnutls_allow_auto_pkcs11) |
a5f239e4 PP |
1979 | { |
1980 | rc = gnutls_pkcs11_init(GNUTLS_PKCS11_FLAG_MANUAL, NULL); | |
1981 | validate_check_rc(US"gnutls_pkcs11_init"); | |
1982 | } | |
1983 | #endif | |
3375e053 PP |
1984 | rc = gnutls_global_init(); |
1985 | validate_check_rc(US"gnutls_global_init()"); | |
1986 | exim_gnutls_base_init_done = TRUE; | |
1987 | ||
1988 | if (!(tls_require_ciphers && *tls_require_ciphers)) | |
1989 | return_deinit(NULL); | |
1990 | ||
1991 | if (!expand_check(tls_require_ciphers, US"tls_require_ciphers", &expciphers)) | |
1992 | return_deinit(US"failed to expand tls_require_ciphers"); | |
1993 | ||
1994 | if (!(expciphers && *expciphers)) | |
1995 | return_deinit(NULL); | |
1996 | ||
1997 | DEBUG(D_tls) | |
1998 | debug_printf("tls_require_ciphers expands to \"%s\"\n", expciphers); | |
1999 | ||
2000 | rc = gnutls_priority_init(&priority_cache, CS expciphers, &errpos); | |
2001 | validate_check_rc(string_sprintf( | |
2002 | "gnutls_priority_init(%s) failed at offset %ld, \"%.8s..\"", | |
2003 | expciphers, errpos - CS expciphers, errpos)); | |
2004 | ||
2005 | #undef return_deinit | |
2006 | #undef validate_check_rc | |
2007 | gnutls_global_deinit(); | |
2008 | ||
2009 | return NULL; | |
2010 | } | |
2011 | ||
2012 | ||
2013 | ||
2014 | ||
36f12725 NM |
2015 | /************************************************* |
2016 | * Report the library versions. * | |
2017 | *************************************************/ | |
2018 | ||
2019 | /* See a description in tls-openssl.c for an explanation of why this exists. | |
2020 | ||
2021 | Arguments: a FILE* to print the results to | |
2022 | Returns: nothing | |
2023 | */ | |
2024 | ||
2025 | void | |
2026 | tls_version_report(FILE *f) | |
2027 | { | |
754a0503 PP |
2028 | fprintf(f, "Library version: GnuTLS: Compile: %s\n" |
2029 | " Runtime: %s\n", | |
2030 | LIBGNUTLS_VERSION, | |
2031 | gnutls_check_version(NULL)); | |
36f12725 NM |
2032 | } |
2033 | ||
059ec3d9 | 2034 | /* End of tls-gnu.c */ |