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44bbabb5 PP |
1 | /************************************************* |
2 | * Exim - an Internet mail transport agent * | |
3 | *************************************************/ | |
4 | ||
5 | /* Copyright (c) University of Cambridge 1995 - 2012 */ | |
6 | /* See the file NOTICE for conditions of use and distribution. */ | |
7 | ||
df6303fa PP |
8 | /* Copyright (c) Twitter Inc 2012 |
9 | Author: Phil Pennock <pdp@exim.org> */ | |
10 | /* Copyright (c) Phil Pennock 2012 */ | |
44bbabb5 PP |
11 | |
12 | /* Interface to GNU SASL library for generic authentication. */ | |
13 | ||
14 | /* Trade-offs: | |
15 | ||
16 | GNU SASL does not provide authentication data itself, so we have to expose | |
17 | that decision to configuration. For some mechanisms, we need to act much | |
18 | like plaintext. For others, we only need to be able to provide some | |
19 | evaluated data on demand. There's no abstracted way (ie, without hardcoding | |
20 | knowledge of authenticators here) to know which need what properties; we | |
21 | can't query a session or the library for "we will need these for mechanism X". | |
22 | ||
23 | So: we always require server_condition, even if sometimes it will just be | |
24 | set as "yes". We do provide a number of other hooks, which might not make | |
25 | sense in all contexts. For some, we can do checks at init time. | |
26 | */ | |
27 | ||
28 | #include "../exim.h" | |
29 | ||
30 | #ifndef AUTH_GSASL | |
31 | /* dummy function to satisfy compilers when we link in an "empty" file. */ | |
32 | static void dummy(int x) { dummy(x-1); } | |
33 | #else | |
34 | ||
35 | #include <gsasl.h> | |
36 | #include "gsasl_exim.h" | |
37 | ||
38 | /* Authenticator-specific options. */ | |
39 | /* I did have server_*_condition options for various mechanisms, but since | |
40 | we only ever handle one mechanism at a time, I didn't see the point in keeping | |
41 | that. In case someone sees a point, I've left the condition_check() API | |
42 | alone. */ | |
43 | optionlist auth_gsasl_options[] = { | |
44 | { "server_channelbinding", opt_bool, | |
45 | (void *)(offsetof(auth_gsasl_options_block, server_channelbinding)) }, | |
46 | { "server_hostname", opt_stringptr, | |
47 | (void *)(offsetof(auth_gsasl_options_block, server_hostname)) }, | |
48 | { "server_mech", opt_stringptr, | |
49 | (void *)(offsetof(auth_gsasl_options_block, server_mech)) }, | |
50 | { "server_password", opt_stringptr, | |
51 | (void *)(offsetof(auth_gsasl_options_block, server_password)) }, | |
52 | { "server_realm", opt_stringptr, | |
53 | (void *)(offsetof(auth_gsasl_options_block, server_realm)) }, | |
54 | { "server_scram_iter", opt_stringptr, | |
55 | (void *)(offsetof(auth_gsasl_options_block, server_scram_iter)) }, | |
56 | { "server_scram_salt", opt_stringptr, | |
57 | (void *)(offsetof(auth_gsasl_options_block, server_scram_salt)) }, | |
58 | { "server_service", opt_stringptr, | |
59 | (void *)(offsetof(auth_gsasl_options_block, server_service)) } | |
60 | }; | |
61 | /* GSASL_SCRAM_SALTED_PASSWORD documented only for client, so not implementing | |
62 | hooks to avoid cleartext passwords in the Exim server. */ | |
63 | ||
64 | int auth_gsasl_options_count = | |
65 | sizeof(auth_gsasl_options)/sizeof(optionlist); | |
66 | ||
67 | /* Defaults for the authenticator-specific options. */ | |
68 | auth_gsasl_options_block auth_gsasl_option_defaults = { | |
69 | US"smtp", /* server_service */ | |
70 | US"$primary_hostname", /* server_hostname */ | |
71 | NULL, /* server_realm */ | |
72 | NULL, /* server_mech */ | |
73 | NULL, /* server_password */ | |
74 | NULL, /* server_scram_iter */ | |
75 | NULL, /* server_scram_salt */ | |
76 | FALSE /* server_channelbinding */ | |
77 | }; | |
78 | ||
79 | /* "Globals" for managing the gsasl interface. */ | |
80 | ||
81 | static Gsasl *gsasl_ctx = NULL; | |
82 | static int | |
83 | main_callback(Gsasl *ctx, Gsasl_session *sctx, Gsasl_property prop); | |
84 | static int | |
85 | server_callback(Gsasl *ctx, Gsasl_session *sctx, Gsasl_property prop, auth_instance *ablock); | |
86 | static int | |
87 | client_callback(Gsasl *ctx, Gsasl_session *sctx, Gsasl_property prop, auth_instance *ablock); | |
88 | ||
89 | static BOOL sasl_error_should_defer = FALSE; | |
90 | static Gsasl_property callback_loop = 0; | |
91 | static BOOL checked_server_condition = FALSE; | |
92 | ||
93 | enum { CURRENTLY_SERVER = 1, CURRENTLY_CLIENT = 2 }; | |
94 | ||
95 | struct callback_exim_state { | |
96 | auth_instance *ablock; | |
97 | int currently; | |
98 | }; | |
99 | ||
100 | ||
101 | /************************************************* | |
102 | * Initialization entry point * | |
103 | *************************************************/ | |
104 | ||
105 | /* Called for each instance, after its options have been read, to | |
106 | enable consistency checks to be done, or anything else that needs | |
107 | to be set up. */ | |
108 | ||
109 | void | |
110 | auth_gsasl_init(auth_instance *ablock) | |
111 | { | |
112 | char *p; | |
113 | int rc, supported; | |
114 | auth_gsasl_options_block *ob = | |
115 | (auth_gsasl_options_block *)(ablock->options_block); | |
116 | ||
117 | /* As per existing Cyrus glue, use the authenticator's public name as | |
118 | the default for the mechanism name; we don't handle multiple mechanisms | |
119 | in one authenticator, but the same driver can be used multiple times. */ | |
120 | ||
121 | if (ob->server_mech == NULL) | |
122 | ob->server_mech = string_copy(ablock->public_name); | |
123 | ||
124 | /* Can get multiple session contexts from one library context, so just | |
125 | initialise the once. */ | |
126 | if (gsasl_ctx == NULL) { | |
127 | rc = gsasl_init(&gsasl_ctx); | |
128 | if (rc != GSASL_OK) { | |
129 | log_write(0, LOG_PANIC_DIE|LOG_CONFIG_FOR, "%s authenticator: " | |
130 | "couldn't initialise GNU SASL library: %s (%s)", | |
131 | ablock->name, gsasl_strerror_name(rc), gsasl_strerror(rc)); | |
132 | } | |
133 | gsasl_callback_set(gsasl_ctx, main_callback); | |
134 | } | |
135 | ||
136 | /* We don't need this except to log it for debugging. */ | |
137 | rc = gsasl_server_mechlist(gsasl_ctx, &p); | |
138 | if (rc != GSASL_OK) | |
139 | log_write(0, LOG_PANIC_DIE|LOG_CONFIG_FOR, "%s authenticator: " | |
140 | "failed to retrieve list of mechanisms: %s (%s)", | |
141 | ablock->name, gsasl_strerror_name(rc), gsasl_strerror(rc)); | |
142 | HDEBUG(D_auth) debug_printf("GNU SASL supports: %s\n", p); | |
143 | ||
144 | supported = gsasl_client_support_p(gsasl_ctx, (const char *)ob->server_mech); | |
145 | if (!supported) | |
146 | log_write(0, LOG_PANIC_DIE|LOG_CONFIG_FOR, "%s authenticator: " | |
147 | "GNU SASL does not support mechanism \"%s\"", | |
148 | ablock->name, ob->server_mech); | |
149 | ||
150 | if ((ablock->server_condition == NULL) && | |
ce52b325 PP |
151 | (streqic(ob->server_mech, US"EXTERNAL") || |
152 | streqic(ob->server_mech, US"ANONYMOUS") || | |
153 | streqic(ob->server_mech, US"PLAIN") || | |
154 | streqic(ob->server_mech, US"LOGIN"))) | |
44bbabb5 PP |
155 | log_write(0, LOG_PANIC_DIE|LOG_CONFIG_FOR, "%s authenticator: " |
156 | "Need server_condition for %s mechanism", | |
157 | ablock->name, ob->server_mech); | |
158 | ||
ce52b325 PP |
159 | /* This does *not* scale to new SASL mechanisms. Need a better way to ask |
160 | which properties will be needed. */ | |
161 | if ((ob->server_realm == NULL) && | |
162 | streqic(ob->server_mech, US"DIGEST-MD5")) | |
163 | log_write(0, LOG_PANIC_DIE|LOG_CONFIG_FOR, "%s authenticator: " | |
164 | "Need server_realm for %s mechanism", | |
165 | ablock->name, ob->server_mech); | |
166 | ||
44bbabb5 PP |
167 | /* At present, for mechanisms we don't panic on absence of server_condition; |
168 | need to figure out the most generically correct approach to deciding when | |
169 | it's critical and when it isn't. Eg, for simple validation (PLAIN mechanism, | |
170 | etc) it clearly is critical. | |
171 | ||
172 | So don't activate without server_condition, this might be relaxed in the future. | |
173 | */ | |
174 | if (ablock->server_condition != NULL) ablock->server = TRUE; | |
175 | ablock->client = FALSE; | |
176 | } | |
177 | ||
178 | ||
179 | /* GNU SASL uses one top-level callback, registered at library level. | |
180 | We dispatch to client and server functions instead. */ | |
181 | ||
182 | static int | |
183 | main_callback(Gsasl *ctx, Gsasl_session *sctx, Gsasl_property prop) | |
184 | { | |
185 | int rc = 0; | |
186 | struct callback_exim_state *cb_state = | |
187 | (struct callback_exim_state *)gsasl_session_hook_get(sctx); | |
188 | ||
ce52b325 PP |
189 | HDEBUG(D_auth) |
190 | debug_printf("GNU SASL Callback entered, prop=%d (loop prop=%d)\n", | |
191 | prop, callback_loop); | |
44bbabb5 PP |
192 | |
193 | if (cb_state == NULL) { | |
194 | HDEBUG(D_auth) debug_printf(" not from our server/client processing.\n"); | |
195 | return GSASL_NO_CALLBACK; | |
196 | } | |
197 | ||
198 | if (callback_loop > 0) { | |
199 | /* Most likely is that we were asked for property foo, and to | |
200 | expand the string we asked for property bar to put into an auth | |
201 | variable, but property bar is not supplied for this mechanism. */ | |
202 | HDEBUG(D_auth) | |
203 | debug_printf("Loop, asked for property %d while handling property %d\n", | |
204 | prop, callback_loop); | |
205 | return GSASL_NO_CALLBACK; | |
206 | } | |
207 | callback_loop = prop; | |
208 | ||
209 | if (cb_state->currently == CURRENTLY_CLIENT) | |
210 | rc = client_callback(ctx, sctx, prop, cb_state->ablock); | |
211 | else if (cb_state->currently == CURRENTLY_SERVER) | |
212 | rc = server_callback(ctx, sctx, prop, cb_state->ablock); | |
213 | else { | |
214 | log_write(0, LOG_PANIC_DIE|LOG_CONFIG_FOR, "%s authenticator: " | |
215 | "unhandled callback state, bug in Exim", cb_state->ablock->name); | |
216 | /* NOTREACHED */ | |
217 | } | |
218 | ||
219 | callback_loop = 0; | |
220 | return rc; | |
221 | } | |
222 | ||
223 | ||
224 | /************************************************* | |
225 | * Server entry point * | |
226 | *************************************************/ | |
227 | ||
228 | /* For interface, see auths/README */ | |
229 | ||
230 | int | |
231 | auth_gsasl_server(auth_instance *ablock, uschar *initial_data) | |
232 | { | |
233 | char *tmps; | |
234 | char *to_send, *received; | |
235 | Gsasl_session *sctx = NULL; | |
236 | auth_gsasl_options_block *ob = | |
237 | (auth_gsasl_options_block *)(ablock->options_block); | |
238 | struct callback_exim_state cb_state; | |
239 | int rc, auth_result, exim_error, exim_error_override; | |
240 | ||
241 | HDEBUG(D_auth) | |
242 | debug_printf("GNU SASL: initialising session for %s, mechanism %s.\n", | |
243 | ablock->name, ob->server_mech); | |
244 | ||
245 | rc = gsasl_server_start(gsasl_ctx, (const char *)ob->server_mech, &sctx); | |
246 | if (rc != GSASL_OK) { | |
247 | auth_defer_msg = string_sprintf("GNU SASL: session start failure: %s (%s)", | |
248 | gsasl_strerror_name(rc), gsasl_strerror(rc)); | |
249 | HDEBUG(D_auth) debug_printf("%s\n", auth_defer_msg); | |
250 | return DEFER; | |
251 | } | |
252 | /* Hereafter: gsasl_finish(sctx) please */ | |
253 | ||
254 | gsasl_session_hook_set(sctx, (void *)ablock); | |
255 | cb_state.ablock = ablock; | |
256 | cb_state.currently = CURRENTLY_SERVER; | |
257 | gsasl_session_hook_set(sctx, (void *)&cb_state); | |
258 | ||
259 | tmps = CS expand_string(ob->server_service); | |
260 | gsasl_property_set(sctx, GSASL_SERVICE, tmps); | |
261 | tmps = CS expand_string(ob->server_hostname); | |
262 | gsasl_property_set(sctx, GSASL_HOSTNAME, tmps); | |
263 | if (ob->server_realm) { | |
264 | tmps = CS expand_string(ob->server_realm); | |
265 | if (tmps && *tmps) { | |
266 | gsasl_property_set(sctx, GSASL_REALM, tmps); | |
267 | } | |
268 | } | |
269 | /* We don't support protection layers. */ | |
270 | gsasl_property_set(sctx, GSASL_QOPS, "qop-auth"); | |
271 | #ifdef SUPPORT_TLS | |
272 | if (tls_channelbinding_b64) { | |
273 | /* Some auth mechanisms can ensure that both sides are talking withing the | |
274 | same security context; for TLS, this means that even if a bad certificate | |
275 | has been accepted, they remain MitM-proof because both sides must be within | |
276 | the same negotiated session; if someone is terminating one sesson and | |
277 | proxying data on within a second, authentication will fail. | |
278 | ||
279 | We might not have this available, depending upon TLS implementation, | |
280 | ciphersuite, phase of moon ... | |
281 | ||
282 | If we do, it results in extra SASL mechanisms being available; here, | |
283 | Exim's one-mechanism-per-authenticator potentially causes problems. | |
284 | It depends upon how GNU SASL will implement the PLUS variants of GS2 | |
285 | and whether it automatically mandates a switch to the bound PLUS | |
286 | if the data is available. Since default-on, despite being more secure, | |
287 | would then result in mechanism name changes on a library update, we | |
288 | have little choice but to default it off and let the admin choose to | |
289 | enable it. *sigh* | |
290 | */ | |
291 | if (ob->server_channelbinding) { | |
292 | HDEBUG(D_auth) debug_printf("Auth %s: Enabling channel-binding\n", | |
293 | ablock->name); | |
294 | gsasl_property_set(sctx, GSASL_CB_TLS_UNIQUE, | |
295 | (const char *) tls_channelbinding_b64); | |
296 | } else { | |
297 | HDEBUG(D_auth) | |
298 | debug_printf("Auth %s: Not enabling channel-binding (data available)\n", | |
299 | ablock->name); | |
300 | } | |
301 | } else { | |
302 | HDEBUG(D_auth) | |
303 | debug_printf("Auth %s: no channel-binding data available\n", | |
304 | ablock->name); | |
305 | } | |
306 | #endif | |
307 | ||
308 | checked_server_condition = FALSE; | |
309 | ||
310 | received = CS initial_data; | |
311 | to_send = NULL; | |
312 | exim_error = exim_error_override = OK; | |
313 | ||
314 | do { | |
315 | rc = gsasl_step64(sctx, received, &to_send); | |
316 | ||
317 | switch (rc) { | |
318 | case GSASL_OK: | |
ce52b325 PP |
319 | if (!to_send) |
320 | goto STOP_INTERACTION; | |
321 | break; | |
44bbabb5 PP |
322 | |
323 | case GSASL_NEEDS_MORE: | |
324 | break; | |
325 | ||
326 | case GSASL_AUTHENTICATION_ERROR: | |
327 | case GSASL_INTEGRITY_ERROR: | |
328 | case GSASL_NO_AUTHID: | |
329 | case GSASL_NO_ANONYMOUS_TOKEN: | |
330 | case GSASL_NO_AUTHZID: | |
331 | case GSASL_NO_PASSWORD: | |
332 | case GSASL_NO_PASSCODE: | |
333 | case GSASL_NO_PIN: | |
334 | case GSASL_BASE64_ERROR: | |
335 | HDEBUG(D_auth) debug_printf("GNU SASL permanent error: %s (%s)\n", | |
336 | gsasl_strerror_name(rc), gsasl_strerror(rc)); | |
337 | log_write(0, LOG_REJECT, "%s authenticator (%s):\n " | |
338 | "GNU SASL permanent failure: %s (%s)", | |
339 | ablock->name, ob->server_mech, | |
340 | gsasl_strerror_name(rc), gsasl_strerror(rc)); | |
341 | if (rc == GSASL_BASE64_ERROR) | |
342 | exim_error_override = BAD64; | |
343 | goto STOP_INTERACTION; | |
344 | ||
345 | default: | |
346 | auth_defer_msg = string_sprintf("GNU SASL temporary error: %s (%s)", | |
347 | gsasl_strerror_name(rc), gsasl_strerror(rc)); | |
348 | HDEBUG(D_auth) debug_printf("%s\n", auth_defer_msg); | |
349 | exim_error_override = DEFER; | |
350 | goto STOP_INTERACTION; | |
351 | } | |
352 | ||
ce52b325 PP |
353 | if ((rc == GSASL_NEEDS_MORE) || |
354 | (to_send && *to_send)) | |
355 | exim_error = | |
356 | auth_get_no64_data((uschar **)&received, (uschar *)to_send); | |
357 | ||
358 | if (to_send) { | |
359 | free(to_send); | |
360 | to_send = NULL; | |
361 | } | |
362 | ||
44bbabb5 PP |
363 | if (exim_error) |
364 | break; /* handles * cancelled check */ | |
365 | ||
366 | } while (rc == GSASL_NEEDS_MORE); | |
367 | ||
368 | STOP_INTERACTION: | |
369 | auth_result = rc; | |
370 | ||
371 | gsasl_finish(sctx); | |
372 | ||
373 | /* Can return: OK DEFER FAIL CANCELLED BAD64 UNEXPECTED */ | |
374 | ||
375 | if (exim_error != OK) | |
376 | return exim_error; | |
377 | ||
378 | if (auth_result != GSASL_OK) { | |
379 | HDEBUG(D_auth) debug_printf("authentication returned %s (%s)\n", | |
380 | gsasl_strerror_name(auth_result), gsasl_strerror(auth_result)); | |
381 | if (exim_error_override != OK) | |
382 | return exim_error_override; /* might be DEFER */ | |
383 | if (sasl_error_should_defer) /* overriding auth failure SASL error */ | |
384 | return DEFER; | |
385 | return FAIL; | |
386 | } | |
387 | ||
388 | /* Auth succeeded, check server_condition unless already done in callback */ | |
389 | return checked_server_condition ? OK : auth_check_serv_cond(ablock); | |
390 | } | |
391 | ||
392 | /* returns the GSASL status of expanding the Exim string given */ | |
393 | static int | |
394 | condition_check(auth_instance *ablock, uschar *label, uschar *condition_string) | |
395 | { | |
396 | int exim_rc; | |
397 | ||
398 | exim_rc = auth_check_some_cond(ablock, label, condition_string, FAIL); | |
399 | ||
400 | if (exim_rc == OK) { | |
401 | return GSASL_OK; | |
402 | } else if (exim_rc == DEFER) { | |
403 | sasl_error_should_defer = TRUE; | |
404 | return GSASL_AUTHENTICATION_ERROR; | |
405 | } else if (exim_rc == FAIL) { | |
406 | return GSASL_AUTHENTICATION_ERROR; | |
407 | } | |
408 | ||
409 | log_write(0, LOG_PANIC_DIE|LOG_CONFIG_FOR, "%s authenticator: " | |
410 | "Unhandled return from checking %s: %d", | |
411 | ablock->name, label, exim_rc); | |
412 | /* NOTREACHED */ | |
413 | return GSASL_AUTHENTICATION_ERROR; | |
414 | } | |
415 | ||
416 | static int | |
417 | server_callback(Gsasl *ctx, Gsasl_session *sctx, Gsasl_property prop, auth_instance *ablock) | |
418 | { | |
419 | char *tmps; | |
420 | uschar *propval; | |
421 | int cbrc = GSASL_NO_CALLBACK; | |
422 | int i; | |
423 | auth_gsasl_options_block *ob = | |
424 | (auth_gsasl_options_block *)(ablock->options_block); | |
425 | ||
426 | HDEBUG(D_auth) | |
427 | debug_printf("GNU SASL callback %d for %s/%s as server\n", | |
428 | prop, ablock->name, ablock->public_name); | |
429 | ||
430 | for (i = 0; i < AUTH_VARS; i++) auth_vars[i] = NULL; | |
431 | expand_nmax = 0; | |
432 | ||
433 | switch (prop) { | |
434 | case GSASL_VALIDATE_SIMPLE: | |
435 | /* GSASL_AUTHID, GSASL_AUTHZID, and GSASL_PASSWORD */ | |
ba96c15a | 436 | propval = (uschar *) gsasl_property_fast(sctx, GSASL_AUTHID); |
44bbabb5 | 437 | auth_vars[0] = expand_nstring[1] = propval ? propval : US""; |
ba96c15a | 438 | propval = (uschar *) gsasl_property_fast(sctx, GSASL_AUTHZID); |
44bbabb5 | 439 | auth_vars[1] = expand_nstring[2] = propval ? propval : US""; |
ba96c15a | 440 | propval = (uschar *) gsasl_property_fast(sctx, GSASL_PASSWORD); |
44bbabb5 PP |
441 | auth_vars[2] = expand_nstring[3] = propval ? propval : US""; |
442 | expand_nmax = 3; | |
443 | for (i = 1; i <= 3; ++i) | |
444 | expand_nlength[i] = Ustrlen(expand_nstring[i]); | |
445 | ||
446 | cbrc = condition_check(ablock, US"server_condition", ablock->server_condition); | |
447 | checked_server_condition = TRUE; | |
448 | break; | |
449 | ||
450 | case GSASL_VALIDATE_EXTERNAL: | |
451 | if (ablock->server_condition == NULL) { | |
452 | HDEBUG(D_auth) debug_printf("No server_condition supplied, to validate EXTERNAL.\n"); | |
453 | cbrc = GSASL_AUTHENTICATION_ERROR; | |
454 | break; | |
455 | } | |
ba96c15a | 456 | propval = (uschar *) gsasl_property_fast(sctx, GSASL_AUTHZID); |
44bbabb5 PP |
457 | /* We always set $auth1, even if only to empty string. */ |
458 | auth_vars[0] = expand_nstring[1] = propval ? propval : US""; | |
459 | expand_nlength[1] = Ustrlen(expand_nstring[1]); | |
460 | expand_nmax = 1; | |
461 | ||
462 | cbrc = condition_check(ablock, | |
463 | US"server_condition (EXTERNAL)", ablock->server_condition); | |
464 | checked_server_condition = TRUE; | |
465 | break; | |
466 | ||
467 | case GSASL_VALIDATE_ANONYMOUS: | |
468 | if (ablock->server_condition == NULL) { | |
469 | HDEBUG(D_auth) debug_printf("No server_condition supplied, to validate ANONYMOUS.\n"); | |
470 | cbrc = GSASL_AUTHENTICATION_ERROR; | |
471 | break; | |
472 | } | |
ba96c15a | 473 | propval = (uschar *) gsasl_property_fast(sctx, GSASL_ANONYMOUS_TOKEN); |
44bbabb5 PP |
474 | /* We always set $auth1, even if only to empty string. */ |
475 | auth_vars[0] = expand_nstring[1] = propval ? propval : US""; | |
476 | expand_nlength[1] = Ustrlen(expand_nstring[1]); | |
477 | expand_nmax = 1; | |
478 | ||
479 | cbrc = condition_check(ablock, | |
480 | US"server_condition (ANONYMOUS)", ablock->server_condition); | |
481 | checked_server_condition = TRUE; | |
482 | break; | |
483 | ||
484 | case GSASL_VALIDATE_GSSAPI: | |
df6303fa PP |
485 | /* GSASL_AUTHZID and GSASL_GSSAPI_DISPLAY_NAME |
486 | The display-name is authenticated as part of GSS, the authzid is claimed | |
487 | by the SASL integration after authentication; protected against tampering | |
488 | (if the SASL mechanism supports that, which Kerberos does) but is | |
489 | unverified, same as normal for other mechanisms. | |
490 | ||
491 | First coding, we had these values swapped, but for consistency and prior | |
492 | to the first release of Exim with this authenticator, they've been | |
493 | switched to match the ordering of GSASL_VALIDATE_SIMPLE. */ | |
ba96c15a | 494 | propval = (uschar *) gsasl_property_fast(sctx, GSASL_GSSAPI_DISPLAY_NAME); |
df6303fa | 495 | auth_vars[0] = expand_nstring[1] = propval ? propval : US""; |
ba96c15a | 496 | propval = (uschar *) gsasl_property_fast(sctx, GSASL_AUTHZID); |
44bbabb5 PP |
497 | auth_vars[1] = expand_nstring[2] = propval ? propval : US""; |
498 | expand_nmax = 2; | |
499 | for (i = 1; i <= 2; ++i) | |
500 | expand_nlength[i] = Ustrlen(expand_nstring[i]); | |
501 | ||
502 | /* In this one case, it perhaps makes sense to default back open? | |
503 | But for consistency, let's just mandate server_condition here too. */ | |
504 | cbrc = condition_check(ablock, | |
505 | US"server_condition (GSSAPI family)", ablock->server_condition); | |
506 | checked_server_condition = TRUE; | |
507 | break; | |
508 | ||
509 | case GSASL_PASSWORD: | |
510 | /* DIGEST-MD5: GSASL_AUTHID, GSASL_AUTHZID and GSASL_REALM | |
511 | CRAM-MD5: GSASL_AUTHID | |
512 | PLAIN: GSASL_AUTHID and GSASL_AUTHZID | |
513 | LOGIN: GSASL_AUTHID | |
514 | */ | |
515 | if (ob->server_scram_iter) { | |
516 | tmps = CS expand_string(ob->server_scram_iter); | |
517 | gsasl_property_set(sctx, GSASL_SCRAM_ITER, tmps); | |
518 | } | |
519 | if (ob->server_scram_salt) { | |
520 | tmps = CS expand_string(ob->server_scram_salt); | |
521 | gsasl_property_set(sctx, GSASL_SCRAM_SALT, tmps); | |
522 | } | |
ba96c15a PP |
523 | /* Asking for GSASL_AUTHZID calls back into us if we use |
524 | gsasl_property_get(), thus the use of gsasl_property_fast(). | |
44bbabb5 PP |
525 | Do we really want to hardcode limits per mechanism? What happens when |
526 | a new mechanism is added to the library. It *shouldn't* result in us | |
527 | needing to add more glue, since avoiding that is a large part of the | |
528 | point of SASL. */ | |
ba96c15a | 529 | propval = (uschar *) gsasl_property_fast(sctx, GSASL_AUTHID); |
44bbabb5 | 530 | auth_vars[0] = expand_nstring[1] = propval ? propval : US""; |
ba96c15a | 531 | propval = (uschar *) gsasl_property_fast(sctx, GSASL_AUTHZID); |
44bbabb5 | 532 | auth_vars[1] = expand_nstring[2] = propval ? propval : US""; |
ba96c15a | 533 | propval = (uschar *) gsasl_property_fast(sctx, GSASL_REALM); |
44bbabb5 PP |
534 | auth_vars[2] = expand_nstring[3] = propval ? propval : US""; |
535 | expand_nmax = 3; | |
536 | for (i = 1; i <= 3; ++i) | |
537 | expand_nlength[i] = Ustrlen(expand_nstring[i]); | |
538 | ||
539 | tmps = CS expand_string(ob->server_password); | |
540 | if (tmps == NULL) { | |
541 | sasl_error_should_defer = expand_string_forcedfail ? FALSE : TRUE; | |
542 | HDEBUG(D_auth) debug_printf("server_password expansion failed, so " | |
543 | "can't tell GNU SASL library the password for %s\n", auth_vars[0]); | |
544 | return GSASL_AUTHENTICATION_ERROR; | |
545 | } | |
546 | gsasl_property_set(sctx, GSASL_PASSWORD, tmps); | |
547 | /* This is inadequate; don't think Exim's store stacks are geared | |
548 | for memory wiping, so expanding strings will leave stuff laying around. | |
549 | But no need to compound the problem, so get rid of the one we can. */ | |
550 | memset(tmps, '\0', strlen(tmps)); | |
551 | cbrc = GSASL_OK; | |
552 | break; | |
553 | ||
554 | default: | |
555 | HDEBUG(D_auth) debug_printf("Unrecognised callback: %d\n", prop); | |
556 | cbrc = GSASL_NO_CALLBACK; | |
557 | } | |
558 | ||
559 | HDEBUG(D_auth) debug_printf("Returning %s (%s)\n", | |
560 | gsasl_strerror_name(cbrc), gsasl_strerror(cbrc)); | |
561 | ||
562 | return cbrc; | |
563 | } | |
564 | ||
565 | ||
566 | /************************************************* | |
567 | * Client entry point * | |
568 | *************************************************/ | |
569 | ||
570 | /* For interface, see auths/README */ | |
571 | ||
572 | int | |
573 | auth_gsasl_client( | |
574 | auth_instance *ablock, /* authenticator block */ | |
575 | smtp_inblock *inblock, /* connection inblock */ | |
576 | smtp_outblock *outblock, /* connection outblock */ | |
577 | int timeout, /* command timeout */ | |
578 | uschar *buffer, /* buffer for reading response */ | |
579 | int buffsize) /* size of buffer */ | |
580 | { | |
581 | HDEBUG(D_auth) | |
582 | debug_printf("Client side NOT IMPLEMENTED: you should not see this!\n"); | |
583 | /* NOT IMPLEMENTED */ | |
584 | return FAIL; | |
585 | } | |
586 | ||
587 | static int | |
588 | client_callback(Gsasl *ctx, Gsasl_session *sctx, Gsasl_property prop, auth_instance *ablock) | |
589 | { | |
590 | int cbrc = GSASL_NO_CALLBACK; | |
591 | HDEBUG(D_auth) | |
592 | debug_printf("GNU SASL callback %d for %s/%s as client\n", | |
593 | prop, ablock->name, ablock->public_name); | |
594 | ||
595 | HDEBUG(D_auth) | |
596 | debug_printf("Client side NOT IMPLEMENTED: you should not see this!\n"); | |
597 | ||
598 | return cbrc; | |
599 | } | |
600 | ||
601 | /************************************************* | |
602 | * Diagnostic API * | |
603 | *************************************************/ | |
604 | ||
605 | void | |
606 | auth_gsasl_version_report(FILE *f) | |
607 | { | |
608 | const char *runtime; | |
609 | runtime = gsasl_check_version(NULL); | |
610 | fprintf(f, "Library version: GNU SASL: Compile: %s\n" | |
611 | " Runtime: %s\n", | |
612 | GSASL_VERSION, runtime); | |
613 | } | |
614 | ||
615 | #endif /* AUTH_GSASL */ | |
616 | ||
617 | /* End of gsasl_exim.c */ |