Commit | Line | Data |
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420a0d19 CE |
1 | /* |
2 | * Copyright (c) 2004 Andrey Panin <pazke@donpac.ru> | |
2813c06e | 3 | * Copyright (c) 2006-2016 The Exim Maintainers |
420a0d19 CE |
4 | * |
5 | * This program is free software; you can redistribute it and/or modify | |
6 | * it under the terms of the GNU General Public License as published | |
7 | * by the Free Software Foundation; either version 2 of the License, or | |
8 | * (at your option) any later version. | |
9 | */ | |
10 | ||
11 | /* A number of modifications have been made to the original code. Originally I | |
12 | commented them specially, but now they are getting quite extensive, so I have | |
13 | ceased doing that. The biggest change is to use unbuffered I/O on the socket | |
14 | because using C buffered I/O gives problems on some operating systems. PH */ | |
15 | ||
16 | /* Protocol specifications: | |
17 | * Dovecot 1, protocol version 1.1 | |
18 | * http://wiki.dovecot.org/Authentication%20Protocol | |
19 | * | |
20 | * Dovecot 2, protocol version 1.1 | |
21 | * http://wiki2.dovecot.org/Design/AuthProtocol | |
22 | */ | |
23 | ||
24 | #include "../exim.h" | |
25 | #include "dovecot.h" | |
26 | ||
27 | #define VERSION_MAJOR 1 | |
28 | #define VERSION_MINOR 0 | |
29 | ||
30 | /* http://wiki.dovecot.org/Authentication%20Protocol | |
31 | "The maximum line length isn't defined, | |
32 | but it's currently expected to fit into 8192 bytes" | |
33 | */ | |
34 | #define DOVECOT_AUTH_MAXLINELEN 8192 | |
35 | ||
36 | /* This was hard-coded as 8. | |
37 | AUTH req C->S sends {"AUTH", id, mechanism, service } + params, 5 defined for | |
38 | Dovecot 1; Dovecot 2 (same protocol version) defines 9. | |
39 | ||
40 | Master->Server sends {"USER", id, userid} + params, 6 defined. | |
41 | Server->Client only gives {"OK", id} + params, unspecified, only 1 guaranteed. | |
42 | ||
43 | We only define here to accept S->C; max seen is 3+<unspecified>, plus the two | |
44 | for the command and id, where unspecified might include _at least_ user=... | |
45 | ||
46 | So: allow for more fields than we ever expect to see, while aware that count | |
47 | can go up without changing protocol version. | |
48 | The cost is the length of an array of pointers on the stack. | |
49 | */ | |
50 | #define DOVECOT_AUTH_MAXFIELDCOUNT 16 | |
51 | ||
52 | /* Options specific to the authentication mechanism. */ | |
53 | optionlist auth_dovecot_options[] = { | |
54 | { | |
55 | "server_socket", | |
56 | opt_stringptr, | |
57 | (void *)(offsetof(auth_dovecot_options_block, server_socket)) | |
58 | }, | |
59 | }; | |
60 | ||
61 | /* Size of the options list. An extern variable has to be used so that its | |
62 | address can appear in the tables drtables.c. */ | |
63 | ||
64 | int auth_dovecot_options_count = | |
65 | sizeof(auth_dovecot_options) / sizeof(optionlist); | |
66 | ||
67 | /* Default private options block for the authentication method. */ | |
68 | ||
69 | auth_dovecot_options_block auth_dovecot_option_defaults = { | |
70 | NULL, /* server_socket */ | |
71 | }; | |
72 | ||
73 | ||
74 | /* Static variables for reading from the socket */ | |
75 | ||
76 | static uschar sbuffer[256]; | |
77 | static int socket_buffer_left; | |
78 | ||
79 | ||
80 | ||
81 | /************************************************* | |
82 | * Initialization entry point * | |
83 | *************************************************/ | |
84 | ||
85 | /* Called for each instance, after its options have been read, to | |
86 | enable consistency checks to be done, or anything else that needs | |
87 | to be set up. */ | |
88 | ||
89 | void auth_dovecot_init(auth_instance *ablock) | |
90 | { | |
91 | auth_dovecot_options_block *ob = | |
92 | (auth_dovecot_options_block *)(ablock->options_block); | |
93 | ||
94 | if (ablock->public_name == NULL) | |
95 | ablock->public_name = ablock->name; | |
96 | if (ob->server_socket != NULL) | |
97 | ablock->server = TRUE; | |
98 | ablock->client = FALSE; | |
99 | } | |
100 | ||
101 | /************************************************* | |
102 | * "strcut" to split apart server lines * | |
103 | *************************************************/ | |
104 | ||
105 | /* Dovecot auth protocol uses TAB \t as delimiter; a line consists | |
106 | of a command-name, TAB, and then any parameters, each separated by a TAB. | |
107 | A parameter can be param=value or a bool, just param. | |
108 | ||
109 | This function modifies the original str in-place, inserting NUL characters. | |
110 | It initialises ptrs entries, setting all to NULL and only setting | |
111 | non-NULL N entries, where N is the return value, the number of fields seen | |
112 | (one more than the number of tabs). | |
113 | ||
114 | Note that the return value will always be at least 1, is the count of | |
115 | actual fields (so last valid offset into ptrs is one less). | |
116 | */ | |
117 | ||
118 | static int | |
119 | strcut(uschar *str, uschar **ptrs, int nptrs) | |
120 | { | |
121 | uschar *last_sub_start = str; | |
122 | int n; | |
123 | ||
124 | for (n = 0; n < nptrs; n++) | |
125 | ptrs[n] = NULL; | |
126 | n = 1; | |
127 | ||
128 | while (*str) { | |
129 | if (*str == '\t') { | |
130 | if (n <= nptrs) { | |
131 | *ptrs++ = last_sub_start; | |
132 | last_sub_start = str + 1; | |
133 | *str = '\0'; | |
134 | } | |
135 | n++; | |
136 | } | |
137 | str++; | |
138 | } | |
139 | ||
140 | /* It's acceptable for the string to end with a tab character. We see | |
141 | this in AUTH PLAIN without an initial response from the client, which | |
142 | causing us to send "334 " and get the data from the client. */ | |
143 | if (n <= nptrs) { | |
144 | *ptrs = last_sub_start; | |
145 | } else { | |
146 | HDEBUG(D_auth) debug_printf("dovecot: warning: too many results from tab-splitting; saw %d fields, room for %d\n", n, nptrs); | |
147 | n = nptrs; | |
148 | } | |
149 | ||
150 | return n <= nptrs ? n : nptrs; | |
151 | } | |
152 | ||
153 | static void debug_strcut(uschar **ptrs, int nlen, int alen) ARG_UNUSED; | |
154 | static void | |
155 | debug_strcut(uschar **ptrs, int nlen, int alen) | |
156 | { | |
157 | int i; | |
158 | debug_printf("%d read but unreturned bytes; strcut() gave %d results: ", | |
159 | socket_buffer_left, nlen); | |
160 | for (i = 0; i < nlen; i++) { | |
161 | debug_printf(" {%s}", ptrs[i]); | |
162 | } | |
163 | if (nlen < alen) | |
164 | debug_printf(" last is %s\n", ptrs[i] ? ptrs[i] : US"<null>"); | |
165 | else | |
166 | debug_printf(" (max for capacity)\n"); | |
167 | } | |
168 | ||
169 | #define CHECK_COMMAND(str, arg_min, arg_max) do { \ | |
170 | if (strcmpic(US(str), args[0]) != 0) \ | |
171 | goto out; \ | |
172 | if (nargs - 1 < (arg_min)) \ | |
173 | goto out; \ | |
174 | if ( (arg_max != -1) && (nargs - 1 > (arg_max)) ) \ | |
175 | goto out; \ | |
176 | } while (0) | |
177 | ||
178 | #define OUT(msg) do { \ | |
179 | auth_defer_msg = (US msg); \ | |
180 | goto out; \ | |
181 | } while(0) | |
182 | ||
183 | ||
184 | ||
185 | /************************************************* | |
186 | * "fgets" to read directly from socket * | |
187 | *************************************************/ | |
188 | ||
189 | /* Added by PH after a suggestion by Steve Usher because the previous use of | |
190 | C-style buffered I/O gave trouble. */ | |
191 | ||
192 | static uschar * | |
193 | dc_gets(uschar *s, int n, int fd) | |
194 | { | |
195 | int p = 0; | |
196 | int count = 0; | |
197 | ||
198 | for (;;) | |
199 | { | |
200 | if (socket_buffer_left == 0) | |
201 | { | |
202 | socket_buffer_left = read(fd, sbuffer, sizeof(sbuffer)); | |
203 | if (socket_buffer_left == 0) { if (count == 0) return NULL; else break; } | |
204 | p = 0; | |
205 | } | |
206 | ||
207 | while (p < socket_buffer_left) | |
208 | { | |
209 | if (count >= n - 1) break; | |
210 | s[count++] = sbuffer[p]; | |
211 | if (sbuffer[p++] == '\n') break; | |
212 | } | |
213 | ||
214 | memmove(sbuffer, sbuffer + p, socket_buffer_left - p); | |
215 | socket_buffer_left -= p; | |
216 | ||
217 | if (s[count-1] == '\n' || count >= n - 1) break; | |
218 | } | |
219 | ||
220 | s[count] = '\0'; | |
221 | return s; | |
222 | } | |
223 | ||
224 | ||
225 | ||
226 | ||
227 | /************************************************* | |
228 | * Server entry point * | |
229 | *************************************************/ | |
230 | ||
2813c06e CE |
231 | int |
232 | auth_dovecot_server(auth_instance * ablock, uschar * data) | |
420a0d19 | 233 | { |
2813c06e CE |
234 | auth_dovecot_options_block *ob = |
235 | (auth_dovecot_options_block *) ablock->options_block; | |
236 | struct sockaddr_un sa; | |
237 | uschar buffer[DOVECOT_AUTH_MAXLINELEN]; | |
238 | uschar *args[DOVECOT_AUTH_MAXFIELDCOUNT]; | |
239 | uschar *auth_command; | |
240 | uschar *auth_extra_data = US""; | |
241 | uschar *p; | |
242 | int nargs, tmp; | |
243 | int crequid = 1, cont = 1, fd = -1, ret = DEFER; | |
244 | BOOL found = FALSE, have_mech_line = FALSE; | |
245 | ||
246 | HDEBUG(D_auth) debug_printf("dovecot authentication\n"); | |
247 | ||
248 | if (!data) | |
249 | { | |
250 | ret = FAIL; | |
251 | goto out; | |
252 | } | |
420a0d19 | 253 | |
2813c06e CE |
254 | memset(&sa, 0, sizeof(sa)); |
255 | sa.sun_family = AF_UNIX; | |
420a0d19 | 256 | |
2813c06e CE |
257 | /* This was the original code here: it is nonsense because strncpy() |
258 | does not return an integer. I have converted this to use the function | |
259 | that formats and checks length. PH */ | |
420a0d19 | 260 | |
2813c06e CE |
261 | /* |
262 | if (strncpy(sa.sun_path, ob->server_socket, sizeof(sa.sun_path)) < 0) { | |
263 | } | |
264 | */ | |
420a0d19 | 265 | |
2813c06e CE |
266 | if (!string_format(US sa.sun_path, sizeof(sa.sun_path), "%s", |
267 | ob->server_socket)) | |
268 | { | |
269 | auth_defer_msg = US"authentication socket path too long"; | |
270 | return DEFER; | |
271 | } | |
420a0d19 | 272 | |
2813c06e | 273 | auth_defer_msg = US"authentication socket connection error"; |
420a0d19 | 274 | |
2813c06e CE |
275 | if ((fd = socket(PF_UNIX, SOCK_STREAM, 0)) < 0) |
276 | return DEFER; | |
420a0d19 | 277 | |
2813c06e CE |
278 | if (connect(fd, (struct sockaddr *) &sa, sizeof(sa)) < 0) |
279 | goto out; | |
420a0d19 | 280 | |
2813c06e | 281 | auth_defer_msg = US"authentication socket protocol error"; |
420a0d19 | 282 | |
2813c06e CE |
283 | socket_buffer_left = 0; /* Global, used to read more than a line but return by line */ |
284 | while (cont) | |
285 | { | |
286 | if (dc_gets(buffer, sizeof(buffer), fd) == NULL) | |
287 | OUT("authentication socket read error or premature eof"); | |
288 | p = buffer + Ustrlen(buffer) - 1; | |
289 | if (*p != '\n') | |
290 | OUT("authentication socket protocol line too long"); | |
291 | ||
292 | *p = '\0'; | |
293 | HDEBUG(D_auth) debug_printf("received: %s\n", buffer); | |
294 | ||
295 | nargs = strcut(buffer, args, sizeof(args) / sizeof(args[0])); | |
296 | ||
297 | /* HDEBUG(D_auth) debug_strcut(args, nargs, sizeof(args) / sizeof(args[0])); */ | |
298 | ||
299 | /* Code below rewritten by Kirill Miazine (km@krot.org). Only check commands that | |
300 | Exim will need. Original code also failed if Dovecot server sent unknown | |
301 | command. E.g. COOKIE in version 1.1 of the protocol would cause troubles. */ | |
302 | /* pdp: note that CUID is a per-connection identifier sent by the server, | |
303 | which increments at server discretion. | |
304 | By contrast, the "id" field of the protocol is a connection-specific request | |
305 | identifier, which needs to be unique per request from the client and is not | |
306 | connected to the CUID value, so we ignore CUID from server. It's purely for | |
307 | diagnostics. */ | |
308 | ||
309 | if (Ustrcmp(args[0], US"VERSION") == 0) | |
310 | { | |
311 | CHECK_COMMAND("VERSION", 2, 2); | |
312 | if (Uatoi(args[1]) != VERSION_MAJOR) | |
313 | OUT("authentication socket protocol version mismatch"); | |
314 | } | |
315 | else if (Ustrcmp(args[0], US"MECH") == 0) | |
316 | { | |
317 | CHECK_COMMAND("MECH", 1, INT_MAX); | |
318 | have_mech_line = TRUE; | |
319 | if (strcmpic(US args[1], ablock->public_name) == 0) | |
320 | found = TRUE; | |
321 | } | |
322 | else if (Ustrcmp(args[0], US"SPID") == 0) | |
323 | { | |
324 | /* Unfortunately the auth protocol handshake wasn't designed well | |
325 | to differentiate between auth-client/userdb/master. auth-userdb | |
326 | and auth-master send VERSION + SPID lines only and nothing | |
327 | afterwards, while auth-client sends VERSION + MECH + SPID + | |
328 | CUID + more. The simplest way that we can determine if we've | |
329 | connected to the correct socket is to see if MECH line exists or | |
330 | not (alternatively we'd have to have a small timeout after SPID | |
331 | to see if CUID is sent or not). */ | |
332 | ||
333 | if (!have_mech_line) | |
334 | OUT("authentication socket type mismatch" | |
335 | " (connected to auth-master instead of auth-client)"); | |
336 | } | |
337 | else if (Ustrcmp(args[0], US"DONE") == 0) | |
338 | { | |
339 | CHECK_COMMAND("DONE", 0, 0); | |
340 | cont = 0; | |
341 | } | |
342 | } | |
420a0d19 | 343 | |
2813c06e CE |
344 | if (!found) |
345 | { | |
346 | auth_defer_msg = string_sprintf( | |
347 | "Dovecot did not advertise mechanism \"%s\" to us", ablock->public_name); | |
348 | goto out; | |
349 | } | |
420a0d19 | 350 | |
2813c06e CE |
351 | /* Added by PH: data must not contain tab (as it is |
352 | b64 it shouldn't, but check for safety). */ | |
420a0d19 | 353 | |
2813c06e CE |
354 | if (Ustrchr(data, '\t') != NULL) |
355 | { | |
356 | ret = FAIL; | |
357 | goto out; | |
358 | } | |
420a0d19 | 359 | |
2813c06e CE |
360 | /* Added by PH: extra fields when TLS is in use or if the TCP/IP |
361 | connection is local. */ | |
420a0d19 | 362 | |
2813c06e CE |
363 | if (tls_in.cipher != NULL) |
364 | auth_extra_data = string_sprintf("secured\t%s%s", | |
365 | tls_in.certificate_verified? "valid-client-cert" : "", | |
366 | tls_in.certificate_verified? "\t" : ""); | |
420a0d19 | 367 | |
2813c06e CE |
368 | else if ( interface_address != NULL |
369 | && Ustrcmp(sender_host_address, interface_address) == 0) | |
370 | auth_extra_data = US"secured\t"; | |
420a0d19 | 371 | |
420a0d19 | 372 | |
2813c06e CE |
373 | /**************************************************************************** |
374 | The code below was the original code here. It didn't work. A reading of the | |
375 | file auth-protocol.txt.gz that came with Dovecot 1.0_beta8 indicated that | |
376 | this was not right. Maybe something changed. I changed it to move the | |
377 | service indication into the AUTH command, and it seems to be better. PH | |
378 | ||
379 | fprintf(f, "VERSION\t%d\t%d\r\nSERVICE\tSMTP\r\nCPID\t%d\r\n" | |
380 | "AUTH\t%d\t%s\trip=%s\tlip=%s\tresp=%s\r\n", | |
381 | VERSION_MAJOR, VERSION_MINOR, getpid(), cuid, | |
382 | ablock->public_name, sender_host_address, interface_address, | |
383 | data ? (char *) data : ""); | |
384 | ||
385 | Subsequently, the command was modified to add "secured" and "valid-client- | |
386 | cert" when relevant. | |
387 | ****************************************************************************/ | |
420a0d19 | 388 | |
2813c06e CE |
389 | auth_command = string_sprintf("VERSION\t%d\t%d\nCPID\t%d\n" |
390 | "AUTH\t%d\t%s\tservice=smtp\t%srip=%s\tlip=%s\tnologin\tresp=%s\n", | |
391 | VERSION_MAJOR, VERSION_MINOR, getpid(), crequid, | |
392 | ablock->public_name, auth_extra_data, sender_host_address, | |
393 | interface_address, data); | |
420a0d19 | 394 | |
2813c06e CE |
395 | if (write(fd, auth_command, Ustrlen(auth_command)) < 0) |
396 | HDEBUG(D_auth) debug_printf("error sending auth_command: %s\n", | |
397 | strerror(errno)); | |
420a0d19 | 398 | |
2813c06e | 399 | HDEBUG(D_auth) debug_printf("sent: %s", auth_command); |
420a0d19 | 400 | |
2813c06e CE |
401 | while (1) |
402 | { | |
403 | uschar *temp; | |
404 | uschar *auth_id_pre = NULL; | |
405 | int i; | |
420a0d19 | 406 | |
2813c06e CE |
407 | if (dc_gets(buffer, sizeof(buffer), fd) == NULL) |
408 | { | |
409 | auth_defer_msg = US"authentication socket read error or premature eof"; | |
410 | goto out; | |
411 | } | |
420a0d19 | 412 | |
2813c06e CE |
413 | buffer[Ustrlen(buffer) - 1] = 0; |
414 | HDEBUG(D_auth) debug_printf("received: %s\n", buffer); | |
415 | nargs = strcut(buffer, args, sizeof(args) / sizeof(args[0])); | |
420a0d19 | 416 | |
2813c06e CE |
417 | if (Uatoi(args[1]) != crequid) |
418 | OUT("authentication socket connection id mismatch"); | |
420a0d19 | 419 | |
2813c06e CE |
420 | switch (toupper(*args[0])) |
421 | { | |
422 | case 'C': | |
423 | CHECK_COMMAND("CONT", 1, 2); | |
424 | ||
425 | if ((tmp = auth_get_no64_data(&data, US args[2])) != OK) | |
426 | { | |
427 | ret = tmp; | |
428 | goto out; | |
429 | } | |
430 | ||
431 | /* Added by PH: data must not contain tab (as it is | |
432 | b64 it shouldn't, but check for safety). */ | |
433 | ||
434 | if (Ustrchr(data, '\t') != NULL) | |
435 | { | |
436 | ret = FAIL; | |
437 | goto out; | |
438 | } | |
439 | ||
440 | temp = string_sprintf("CONT\t%d\t%s\n", crequid, data); | |
441 | if (write(fd, temp, Ustrlen(temp)) < 0) | |
442 | OUT("authentication socket write error"); | |
443 | break; | |
444 | ||
445 | case 'F': | |
446 | CHECK_COMMAND("FAIL", 1, -1); | |
447 | ||
448 | for (i=2; (i<nargs) && (auth_id_pre == NULL); i++) | |
449 | { | |
450 | if ( Ustrncmp(args[i], US"user=", 5) == 0 ) | |
451 | { | |
452 | auth_id_pre = args[i]+5; | |
453 | expand_nstring[1] = auth_vars[0] = string_copy(auth_id_pre); /* PH */ | |
454 | expand_nlength[1] = Ustrlen(auth_id_pre); | |
455 | expand_nmax = 1; | |
456 | } | |
457 | } | |
458 | ||
459 | ret = FAIL; | |
460 | goto out; | |
461 | ||
462 | case 'O': | |
463 | CHECK_COMMAND("OK", 2, -1); | |
464 | ||
465 | /* Search for the "user=$USER" string in the args array | |
466 | and return the proper value. */ | |
467 | ||
468 | for (i=2; (i<nargs) && (auth_id_pre == NULL); i++) | |
469 | { | |
470 | if ( Ustrncmp(args[i], US"user=", 5) == 0 ) | |
471 | { | |
472 | auth_id_pre = args[i]+5; | |
473 | expand_nstring[1] = auth_vars[0] = string_copy(auth_id_pre); /* PH */ | |
474 | expand_nlength[1] = Ustrlen(auth_id_pre); | |
475 | expand_nmax = 1; | |
476 | } | |
477 | } | |
478 | ||
479 | if (auth_id_pre == NULL) | |
480 | OUT("authentication socket protocol error, username missing"); | |
481 | ||
482 | ret = OK; | |
483 | /* fallthrough */ | |
484 | ||
485 | default: | |
486 | goto out; | |
487 | } | |
488 | } | |
420a0d19 CE |
489 | |
490 | out: | |
2813c06e CE |
491 | /* close the socket used by dovecot */ |
492 | if (fd >= 0) | |
493 | close(fd); | |
420a0d19 | 494 | |
2813c06e CE |
495 | /* Expand server_condition as an authorization check */ |
496 | return ret == OK ? auth_check_serv_cond(ablock) : ret; | |
420a0d19 | 497 | } |