| blob | 3e0f03dceef4f7868b95cee6d6a71a0ca14d6d26 |
1 /*\r
2 * Platform-independent bits of X11 forwarding.\r
3 */\r
4 \r
5 #include <stdio.h>\r
6 #include <stdlib.h>\r
7 #include <assert.h>\r
8 #include <time.h>\r
9 \r
10 #include "putty.h"\r
11 #include "ssh.h"\r
12 #include "tree234.h"\r
13 \r
14 #define GET_16BIT(endian, cp) \\r
15 (endian=='B' ? GET_16BIT_MSB_FIRST(cp) : GET_16BIT_LSB_FIRST(cp))\r
16 \r
17 #define PUT_16BIT(endian, cp, val) \\r
18 (endian=='B' ? PUT_16BIT_MSB_FIRST(cp, val) : PUT_16BIT_LSB_FIRST(cp, val))\r
19 \r
20 const char *const x11_authnames[] = {\r
21 "", "MIT-MAGIC-COOKIE-1", "XDM-AUTHORIZATION-1"\r
22 };\r
23 \r
24 struct XDMSeen {\r
25 unsigned int time;\r
26 unsigned char clientid[6];\r
27 };\r
28 \r
29 struct X11Connection {\r
30 const struct plug_function_table *fn;\r
31 /* the above variable absolutely *must* be the first in this structure */\r
32 unsigned char firstpkt[12]; /* first X data packet */\r
33 tree234 *authtree;\r
34 struct X11Display *disp;\r
35 char *auth_protocol;\r
36 unsigned char *auth_data;\r
37 int data_read, auth_plen, auth_psize, auth_dlen, auth_dsize;\r
38 int verified;\r
39 int throttled, throttle_override;\r
40 int no_data_sent_to_x_client;\r
41 char *peer_addr;\r
42 int peer_port;\r
43 struct ssh_channel *c; /* channel structure held by ssh.c */\r
44 Socket s;\r
45 };\r
46 \r
47 static int xdmseen_cmp(void *a, void *b)\r
48 {\r
49 struct XDMSeen *sa = a, *sb = b;\r
50 return sa->time > sb->time ? 1 :\r
51 sa->time < sb->time ? -1 :\r
52 memcmp(sa->clientid, sb->clientid, sizeof(sa->clientid));\r
53 }\r
54 \r
55 /* Do-nothing "plug" implementation, used by x11_setup_display() when it\r
56 * creates a trial connection (and then immediately closes it).\r
57 * XXX: bit out of place here, could in principle live in a platform-\r
58 * independent network.c or something */\r
59 static void dummy_plug_log(Plug p, int type, SockAddr addr, int port,\r
60 const char *error_msg, int error_code) { }\r
61 static int dummy_plug_closing\r
62 (Plug p, const char *error_msg, int error_code, int calling_back)\r
63 { return 1; }\r
64 static int dummy_plug_receive(Plug p, int urgent, char *data, int len)\r
65 { return 1; }\r
66 static void dummy_plug_sent(Plug p, int bufsize) { }\r
67 static int dummy_plug_accepting(Plug p, accept_fn_t constructor, accept_ctx_t ctx) { return 1; }\r
68 static const struct plug_function_table dummy_plug = {\r
69 dummy_plug_log, dummy_plug_closing, dummy_plug_receive,\r
70 dummy_plug_sent, dummy_plug_accepting\r
71 };\r
72 \r
73 struct X11FakeAuth *x11_invent_fake_auth(tree234 *authtree, int authtype)\r
74 {\r
75 struct X11FakeAuth *auth = snew(struct X11FakeAuth);\r
76 int i;\r
77 \r
78 /*\r
79 * This function has the job of inventing a set of X11 fake auth\r
80 * data, and adding it to 'authtree'. We must preserve the\r
81 * property that for any given actual authorisation attempt, _at\r
82 * most one_ thing in the tree can possibly match it.\r
83 *\r
84 * For MIT-MAGIC-COOKIE-1, that's not too difficult: the match\r
85 * criterion is simply that the entire cookie is correct, so we\r
86 * just have to make sure we don't make up two cookies the same.\r
87 * (Vanishingly unlikely, but we check anyway to be sure, and go\r
88 * round again inventing a new cookie if add234 tells us the one\r
89 * we thought of is already in use.)\r
90 *\r
91 * For XDM-AUTHORIZATION-1, it's a little more fiddly. The setup\r
92 * with XA1 is that half the cookie is used as a DES key with\r
93 * which to CBC-encrypt an assortment of stuff. Happily, the stuff\r
94 * encrypted _begins_ with the other half of the cookie, and the\r
95 * IV is always zero, which means that any valid XA1 authorisation\r
96 * attempt for a given cookie must begin with the same cipher\r
97 * block, consisting of the DES ECB encryption of the first half\r
98 * of the cookie using the second half as a key. So we compute\r
99 * that cipher block here and now, and use it as the sorting key\r
100 * for distinguishing XA1 entries in the tree.\r
101 */\r
102 \r
103 if (authtype == X11_MIT) {\r
104 auth->proto = X11_MIT;\r
105 \r
106 /* MIT-MAGIC-COOKIE-1. Cookie size is 128 bits (16 bytes). */\r
107 auth->datalen = 16;\r
108 auth->data = snewn(auth->datalen, unsigned char);\r
109 auth->xa1_firstblock = NULL;\r
110 \r
111 while (1) {\r
112 for (i = 0; i < auth->datalen; i++)\r
113 auth->data[i] = random_byte();\r
114 if (add234(authtree, auth) == auth)\r
115 break;\r
116 }\r
117 \r
118 auth->xdmseen = NULL;\r
119 } else {\r
120 assert(authtype == X11_XDM);\r
121 auth->proto = X11_XDM;\r
122 \r
123 /* XDM-AUTHORIZATION-1. Cookie size is 16 bytes; byte 8 is zero. */\r
124 auth->datalen = 16;\r
125 auth->data = snewn(auth->datalen, unsigned char);\r
126 auth->xa1_firstblock = snewn(8, unsigned char);\r
127 memset(auth->xa1_firstblock, 0, 8);\r
128 \r
129 while (1) {\r
130 for (i = 0; i < auth->datalen; i++)\r
131 auth->data[i] = (i == 8 ? 0 : random_byte());\r
132 memcpy(auth->xa1_firstblock, auth->data, 8);\r
133 des_encrypt_xdmauth(auth->data + 9, auth->xa1_firstblock, 8);\r
134 if (add234(authtree, auth) == auth)\r
135 break;\r
136 }\r
137 \r
138 auth->xdmseen = newtree234(xdmseen_cmp);\r
139 }\r
140 auth->protoname = dupstr(x11_authnames[auth->proto]);\r
141 auth->datastring = snewn(auth->datalen * 2 + 1, char);\r
142 for (i = 0; i < auth->datalen; i++)\r
143 sprintf(auth->datastring + i*2, "%02x",\r
144 auth->data[i]);\r
145 \r
146 auth->disp = NULL;\r
147 auth->share_cs = auth->share_chan = NULL;\r
148 \r
149 return auth;\r
150 }\r
151 \r
152 void x11_free_fake_auth(struct X11FakeAuth *auth)\r
153 {\r
154 if (auth->data)\r
155 smemclr(auth->data, auth->datalen);\r
156 sfree(auth->data);\r
157 sfree(auth->protoname);\r
158 sfree(auth->datastring);\r
159 sfree(auth->xa1_firstblock);\r
160 if (auth->xdmseen != NULL) {\r
161 struct XDMSeen *seen;\r
162 while ((seen = delpos234(auth->xdmseen, 0)) != NULL)\r
163 sfree(seen);\r
164 freetree234(auth->xdmseen);\r
165 }\r
166 sfree(auth);\r
167 }\r
168 \r
169 int x11_authcmp(void *av, void *bv)\r
170 {\r
171 struct X11FakeAuth *a = (struct X11FakeAuth *)av;\r
172 struct X11FakeAuth *b = (struct X11FakeAuth *)bv;\r
173 \r
174 if (a->proto < b->proto)\r
175 return -1;\r
176 else if (a->proto > b->proto)\r
177 return +1;\r
178 \r
179 if (a->proto == X11_MIT) {\r
180 if (a->datalen < b->datalen)\r
181 return -1;\r
182 else if (a->datalen > b->datalen)\r
183 return +1;\r
184 \r
185 return memcmp(a->data, b->data, a->datalen);\r
186 } else {\r
187 assert(a->proto == X11_XDM);\r
188 \r
189 return memcmp(a->xa1_firstblock, b->xa1_firstblock, 8);\r
190 }\r
191 }\r
192 \r
193 struct X11Display *x11_setup_display(char *display, Conf *conf)\r
194 {\r
195 struct X11Display *disp = snew(struct X11Display);\r
196 char *localcopy;\r
197 \r
198 if (!display || !*display) {\r
199 localcopy = platform_get_x_display();\r
200 if (!localcopy || !*localcopy) {\r
201 sfree(localcopy);\r
202 localcopy = dupstr(":0"); /* plausible default for any platform */\r
203 }\r
204 } else\r
205 localcopy = dupstr(display);\r
206 \r
207 /*\r
208 * Parse the display name.\r
209 *\r
210 * We expect this to have one of the following forms:\r
211 * \r
212 * - the standard X format which looks like\r
213 * [ [ protocol '/' ] host ] ':' displaynumber [ '.' screennumber ]\r
214 * (X11 also permits a double colon to indicate DECnet, but\r
215 * that's not our problem, thankfully!)\r
216 *\r
217 * - only seen in the wild on MacOS (so far): a pathname to a\r
218 * Unix-domain socket, which will typically and confusingly\r
219 * end in ":0", and which I'm currently distinguishing from\r
220 * the standard scheme by noting that it starts with '/'.\r
221 */\r
222 if (localcopy[0] == '/') {\r
223 disp->unixsocketpath = localcopy;\r
224 disp->unixdomain = TRUE;\r
225 disp->hostname = NULL;\r
226 disp->displaynum = -1;\r
227 disp->screennum = 0;\r
228 disp->addr = NULL;\r
229 } else {\r
230 char *colon, *dot, *slash;\r
231 char *protocol, *hostname;\r
232 \r
233 colon = host_strrchr(localcopy, ':');\r
234 if (!colon) {\r
235 sfree(disp);\r
236 sfree(localcopy);\r
237 return NULL; /* FIXME: report a specific error? */\r
238 }\r
239 \r
240 *colon++ = '\0';\r
241 dot = strchr(colon, '.');\r
242 if (dot)\r
243 *dot++ = '\0';\r
244 \r
245 disp->displaynum = atoi(colon);\r
246 if (dot)\r
247 disp->screennum = atoi(dot);\r
248 else\r
249 disp->screennum = 0;\r
250 \r
251 protocol = NULL;\r
252 hostname = localcopy;\r
253 if (colon > localcopy) {\r
254 slash = strchr(localcopy, '/');\r
255 if (slash) {\r
256 *slash++ = '\0';\r
257 protocol = localcopy;\r
258 hostname = slash;\r
259 }\r
260 }\r
261 \r
262 disp->hostname = *hostname ? dupstr(hostname) : NULL;\r
263 \r
264 if (protocol)\r
265 disp->unixdomain = (!strcmp(protocol, "local") ||\r
266 !strcmp(protocol, "unix"));\r
267 else if (!*hostname || !strcmp(hostname, "unix"))\r
268 disp->unixdomain = platform_uses_x11_unix_by_default;\r
269 else\r
270 disp->unixdomain = FALSE;\r
271 \r
272 if (!disp->hostname && !disp->unixdomain)\r
273 disp->hostname = dupstr("localhost");\r
274 \r
275 disp->unixsocketpath = NULL;\r
276 disp->addr = NULL;\r
277 \r
278 sfree(localcopy);\r
279 }\r
280 \r
281 /*\r
282 * Look up the display hostname, if we need to.\r
283 */\r
284 if (!disp->unixdomain) {\r
285 const char *err;\r
286 \r
287 disp->port = 6000 + disp->displaynum;\r
288 disp->addr = name_lookup(disp->hostname, disp->port,\r
289 &disp->realhost, conf, ADDRTYPE_UNSPEC);\r
290 \r
291 if ((err = sk_addr_error(disp->addr)) != NULL) {\r
292 sk_addr_free(disp->addr);\r
293 sfree(disp->hostname);\r
294 sfree(disp->unixsocketpath);\r
295 sfree(disp);\r
296 return NULL; /* FIXME: report an error */\r
297 }\r
298 }\r
299 \r
300 /*\r
301 * Try upgrading an IP-style localhost display to a Unix-socket\r
302 * display (as the standard X connection libraries do).\r
303 */\r
304 if (!disp->unixdomain && sk_address_is_local(disp->addr)) {\r
305 SockAddr ux = platform_get_x11_unix_address(NULL, disp->displaynum);\r
306 const char *err = sk_addr_error(ux);\r
307 if (!err) {\r
308 /* Create trial connection to see if there is a useful Unix-domain\r
309 * socket */\r
310 const struct plug_function_table *dummy = &dummy_plug;\r
311 Socket s = sk_new(sk_addr_dup(ux), 0, 0, 0, 0, 0, (Plug)&dummy);\r
312 err = sk_socket_error(s);\r
313 sk_close(s);\r
314 }\r
315 if (err) {\r
316 sk_addr_free(ux);\r
317 } else {\r
318 sk_addr_free(disp->addr);\r
319 disp->unixdomain = TRUE;\r
320 disp->addr = ux;\r
321 /* Fill in the rest in a moment */\r
322 }\r
323 }\r
324 \r
325 if (disp->unixdomain) {\r
326 if (!disp->addr)\r
327 disp->addr = platform_get_x11_unix_address(disp->unixsocketpath,\r
328 disp->displaynum);\r
329 if (disp->unixsocketpath)\r
330 disp->realhost = dupstr(disp->unixsocketpath);\r
331 else\r
332 disp->realhost = dupprintf("unix:%d", disp->displaynum);\r
333 disp->port = 0;\r
334 }\r
335 \r
336 /*\r
337 * Fetch the local authorisation details.\r
338 */\r
339 disp->localauthproto = X11_NO_AUTH;\r
340 disp->localauthdata = NULL;\r
341 disp->localauthdatalen = 0;\r
342 platform_get_x11_auth(disp, conf);\r
343 \r
344 return disp;\r
345 }\r
346 \r
347 void x11_free_display(struct X11Display *disp)\r
348 {\r
349 sfree(disp->hostname);\r
350 sfree(disp->unixsocketpath);\r
351 if (disp->localauthdata)\r
352 smemclr(disp->localauthdata, disp->localauthdatalen);\r
353 sfree(disp->localauthdata);\r
354 sk_addr_free(disp->addr);\r
355 sfree(disp);\r
356 }\r
357 \r
358 #define XDM_MAXSKEW 20*60 /* 20 minute clock skew should be OK */\r
359 \r
360 static char *x11_verify(unsigned long peer_ip, int peer_port,\r
361 tree234 *authtree, char *proto,\r
362 unsigned char *data, int dlen,\r
363 struct X11FakeAuth **auth_ret)\r
364 {\r
365 struct X11FakeAuth match_dummy; /* for passing to find234 */\r
366 struct X11FakeAuth *auth;\r
367 \r
368 /*\r
369 * First, do a lookup in our tree to find the only authorisation\r
370 * record that _might_ match.\r
371 */\r
372 if (!strcmp(proto, x11_authnames[X11_MIT])) {\r
373 /*\r
374 * Just look up the whole cookie that was presented to us,\r
375 * which x11_authcmp will compare against the cookies we\r
376 * currently believe in.\r
377 */\r
378 match_dummy.proto = X11_MIT;\r
379 match_dummy.datalen = dlen;\r
380 match_dummy.data = data;\r
381 } else if (!strcmp(proto, x11_authnames[X11_XDM])) {\r
382 /*\r
383 * Look up the first cipher block, against the stored first\r
384 * cipher blocks for the XDM-AUTHORIZATION-1 cookies we\r
385 * currently know. (See comment in x11_invent_fake_auth.)\r
386 */\r
387 match_dummy.proto = X11_XDM;\r
388 match_dummy.xa1_firstblock = data;\r
389 } else {\r
390 return "Unsupported authorisation protocol";\r
391 }\r
392 \r
393 if ((auth = find234(authtree, &match_dummy, 0)) == NULL)\r
394 return "Authorisation not recognised";\r
395 \r
396 /*\r
397 * If we're using MIT-MAGIC-COOKIE-1, that was all we needed. If\r
398 * we're doing XDM-AUTHORIZATION-1, though, we have to check the\r
399 * rest of the auth data.\r
400 */\r
401 if (auth->proto == X11_XDM) {\r
402 unsigned long t;\r
403 time_t tim;\r
404 int i;\r
405 struct XDMSeen *seen, *ret;\r
406 \r
407 if (dlen != 24)\r
408 return "XDM-AUTHORIZATION-1 data was wrong length";\r
409 if (peer_port == -1)\r
410 return "cannot do XDM-AUTHORIZATION-1 without remote address data";\r
411 des_decrypt_xdmauth(auth->data+9, data, 24);\r
412 if (memcmp(auth->data, data, 8) != 0)\r
413 return "XDM-AUTHORIZATION-1 data failed check"; /* cookie wrong */\r
414 if (GET_32BIT_MSB_FIRST(data+8) != peer_ip)\r
415 return "XDM-AUTHORIZATION-1 data failed check"; /* IP wrong */\r
416 if ((int)GET_16BIT_MSB_FIRST(data+12) != peer_port)\r
417 return "XDM-AUTHORIZATION-1 data failed check"; /* port wrong */\r
418 t = GET_32BIT_MSB_FIRST(data+14);\r
419 for (i = 18; i < 24; i++)\r
420 if (data[i] != 0) /* zero padding wrong */\r
421 return "XDM-AUTHORIZATION-1 data failed check";\r
422 tim = time(NULL);\r
423 if (abs(t - tim) > XDM_MAXSKEW)\r
424 return "XDM-AUTHORIZATION-1 time stamp was too far out";\r
425 seen = snew(struct XDMSeen);\r
426 seen->time = t;\r
427 memcpy(seen->clientid, data+8, 6);\r
428 assert(auth->xdmseen != NULL);\r
429 ret = add234(auth->xdmseen, seen);\r
430 if (ret != seen) {\r
431 sfree(seen);\r
432 return "XDM-AUTHORIZATION-1 data replayed";\r
433 }\r
434 /* While we're here, purge entries too old to be replayed. */\r
435 for (;;) {\r
436 seen = index234(auth->xdmseen, 0);\r
437 assert(seen != NULL);\r
438 if (t - seen->time <= XDM_MAXSKEW)\r
439 break;\r
440 sfree(delpos234(auth->xdmseen, 0));\r
441 }\r
442 }\r
443 /* implement other protocols here if ever required */\r
444 \r
445 *auth_ret = auth;\r
446 return NULL;\r
447 }\r
448 \r
449 void x11_get_auth_from_authfile(struct X11Display *disp,\r
450 const char *authfilename)\r
451 {\r
452 FILE *authfp;\r
453 char *buf, *ptr, *str[4];\r
454 int len[4];\r
455 int family, protocol;\r
456 int ideal_match = FALSE;\r
457 char *ourhostname;\r
458 \r
459 /*\r
460 * Normally we should look for precisely the details specified in\r
461 * `disp'. However, there's an oddity when the display is local:\r
462 * displays like "localhost:0" usually have their details stored\r
463 * in a Unix-domain-socket record (even if there isn't actually a\r
464 * real Unix-domain socket available, as with OpenSSH's proxy X11\r
465 * server).\r
466 *\r
467 * This is apparently a fudge to get round the meaninglessness of\r
468 * "localhost" in a shared-home-directory context -- xauth entries\r
469 * for Unix-domain sockets already disambiguate this by storing\r
470 * the *local* hostname in the conveniently-blank hostname field,\r
471 * but IP "localhost" records couldn't do this. So, typically, an\r
472 * IP "localhost" entry in the auth database isn't present and if\r
473 * it were it would be ignored.\r
474 *\r
475 * However, we don't entirely trust that (say) Windows X servers\r
476 * won't rely on a straight "localhost" entry, bad idea though\r
477 * that is; so if we can't find a Unix-domain-socket entry we'll\r
478 * fall back to an IP-based entry if we can find one.\r
479 */\r
480 int localhost = !disp->unixdomain && sk_address_is_local(disp->addr);\r
481 \r
482 authfp = fopen(authfilename, "rb");\r
483 if (!authfp)\r
484 return;\r
485 \r
486 ourhostname = get_hostname();\r
487 \r
488 /* Records in .Xauthority contain four strings of up to 64K each */\r
489 buf = snewn(65537 * 4, char);\r
490 \r
491 while (!ideal_match) {\r
492 int c, i, j, match = FALSE;\r
493 \r
494 #define GET do { c = fgetc(authfp); if (c == EOF) goto done; c = (unsigned char)c; } while (0)\r
495 /* Expect a big-endian 2-byte number giving address family */\r
496 GET; family = c;\r
497 GET; family = (family << 8) | c;\r
498 /* Then expect four strings, each composed of a big-endian 2-byte\r
499 * length field followed by that many bytes of data */\r
500 ptr = buf;\r
501 for (i = 0; i < 4; i++) {\r
502 GET; len[i] = c;\r
503 GET; len[i] = (len[i] << 8) | c;\r
504 str[i] = ptr;\r
505 for (j = 0; j < len[i]; j++) {\r
506 GET; *ptr++ = c;\r
507 }\r
508 *ptr++ = '\0';\r
509 }\r
510 #undef GET\r
511 \r
512 /*\r
513 * Now we have a full X authority record in memory. See\r
514 * whether it matches the display we're trying to\r
515 * authenticate to.\r
516 *\r
517 * The details we've just read should be interpreted as\r
518 * follows:\r
519 * \r
520 * - 'family' is the network address family used to\r
521 * connect to the display. 0 means IPv4; 6 means IPv6;\r
522 * 256 means Unix-domain sockets.\r
523 * \r
524 * - str[0] is the network address itself. For IPv4 and\r
525 * IPv6, this is a string of binary data of the\r
526 * appropriate length (respectively 4 and 16 bytes)\r
527 * representing the address in big-endian format, e.g.\r
528 * 7F 00 00 01 means IPv4 localhost. For Unix-domain\r
529 * sockets, this is the host name of the machine on\r
530 * which the Unix-domain display resides (so that an\r
531 * .Xauthority file on a shared file system can contain\r
532 * authority entries for Unix-domain displays on\r
533 * several machines without them clashing).\r
534 * \r
535 * - str[1] is the display number. I've no idea why\r
536 * .Xauthority stores this as a string when it has a\r
537 * perfectly good integer format, but there we go.\r
538 * \r
539 * - str[2] is the authorisation method, encoded as its\r
540 * canonical string name (i.e. "MIT-MAGIC-COOKIE-1",\r
541 * "XDM-AUTHORIZATION-1" or something we don't\r
542 * recognise).\r
543 * \r
544 * - str[3] is the actual authorisation data, stored in\r
545 * binary form.\r
546 */\r
547 \r
548 if (disp->displaynum < 0 || disp->displaynum != atoi(str[1]))\r
549 continue; /* not the one */\r
550 \r
551 for (protocol = 1; protocol < lenof(x11_authnames); protocol++)\r
552 if (!strcmp(str[2], x11_authnames[protocol]))\r
553 break;\r
554 if (protocol == lenof(x11_authnames))\r
555 continue; /* don't recognise this protocol, look for another */\r
556 \r
557 switch (family) {\r
558 case 0: /* IPv4 */\r
559 if (!disp->unixdomain &&\r
560 sk_addrtype(disp->addr) == ADDRTYPE_IPV4) {\r
561 char buf[4];\r
562 sk_addrcopy(disp->addr, buf);\r
563 if (len[0] == 4 && !memcmp(str[0], buf, 4)) {\r
564 match = TRUE;\r
565 /* If this is a "localhost" entry, note it down\r
566 * but carry on looking for a Unix-domain entry. */\r
567 ideal_match = !localhost;\r
568 }\r
569 }\r
570 break;\r
571 case 6: /* IPv6 */\r
572 if (!disp->unixdomain &&\r
573 sk_addrtype(disp->addr) == ADDRTYPE_IPV6) {\r
574 char buf[16];\r
575 sk_addrcopy(disp->addr, buf);\r
576 if (len[0] == 16 && !memcmp(str[0], buf, 16)) {\r
577 match = TRUE;\r
578 ideal_match = !localhost;\r
579 }\r
580 }\r
581 break;\r
582 case 256: /* Unix-domain / localhost */\r
583 if ((disp->unixdomain || localhost)\r
584 && ourhostname && !strcmp(ourhostname, str[0]))\r
585 /* A matching Unix-domain socket is always the best\r
586 * match. */\r
587 match = ideal_match = TRUE;\r
588 break;\r
589 }\r
590 \r
591 if (match) {\r
592 /* Current best guess -- may be overridden if !ideal_match */\r
593 disp->localauthproto = protocol;\r
594 sfree(disp->localauthdata); /* free previous guess, if any */\r
595 disp->localauthdata = snewn(len[3], unsigned char);\r
596 memcpy(disp->localauthdata, str[3], len[3]);\r
597 disp->localauthdatalen = len[3];\r
598 }\r
599 }\r
600 \r
601 done:\r
602 fclose(authfp);\r
603 smemclr(buf, 65537 * 4);\r
604 sfree(buf);\r
605 sfree(ourhostname);\r
606 }\r
607 \r
608 static void x11_log(Plug p, int type, SockAddr addr, int port,\r
609 const char *error_msg, int error_code)\r
610 {\r
611 /* We have no interface to the logging module here, so we drop these. */\r
612 }\r
613 \r
614 static void x11_send_init_error(struct X11Connection *conn,\r
615 const char *err_message);\r
616 \r
617 static int x11_closing(Plug plug, const char *error_msg, int error_code,\r
618 int calling_back)\r
619 {\r
620 struct X11Connection *xconn = (struct X11Connection *) plug;\r
621 \r
622 if (error_msg) {\r
623 /*\r
624 * Socket error. If we're still at the connection setup stage,\r
625 * construct an X11 error packet passing on the problem.\r
626 */\r
627 if (xconn->no_data_sent_to_x_client) {\r
628 char *err_message = dupprintf("unable to connect to forwarded "\r
629 "X server: %s", error_msg);\r
630 x11_send_init_error(xconn, err_message);\r
631 sfree(err_message);\r
632 }\r
633 \r
634 /*\r
635 * Whether we did that or not, now we slam the connection\r
636 * shut.\r
637 */\r
638 sshfwd_unclean_close(xconn->c, error_msg);\r
639 } else {\r
640 /*\r
641 * Ordinary EOF received on socket. Send an EOF on the SSH\r
642 * channel.\r
643 */\r
644 if (xconn->c)\r
645 sshfwd_write_eof(xconn->c);\r
646 }\r
647 \r
648 return 1;\r
649 }\r
650 \r
651 static int x11_receive(Plug plug, int urgent, char *data, int len)\r
652 {\r
653 struct X11Connection *xconn = (struct X11Connection *) plug;\r
654 \r
655 if (sshfwd_write(xconn->c, data, len) > 0) {\r
656 xconn->throttled = 1;\r
657 xconn->no_data_sent_to_x_client = FALSE;\r
658 sk_set_frozen(xconn->s, 1);\r
659 }\r
660 \r
661 return 1;\r
662 }\r
663 \r
664 static void x11_sent(Plug plug, int bufsize)\r
665 {\r
666 struct X11Connection *xconn = (struct X11Connection *) plug;\r
667 \r
668 sshfwd_unthrottle(xconn->c, bufsize);\r
669 }\r
670 \r
671 /*\r
672 * When setting up X forwarding, we should send the screen number\r
673 * from the specified local display. This function extracts it from\r
674 * the display string.\r
675 */\r
676 int x11_get_screen_number(char *display)\r
677 {\r
678 int n;\r
679 \r
680 n = host_strcspn(display, ":");\r
681 if (!display[n])\r
682 return 0;\r
683 n = strcspn(display, ".");\r
684 if (!display[n])\r
685 return 0;\r
686 return atoi(display + n + 1);\r
687 }\r
688 \r
689 /*\r
690 * Called to set up the X11Connection structure, though this does not\r
691 * yet connect to an actual server.\r
692 */\r
693 struct X11Connection *x11_init(tree234 *authtree, void *c,\r
694 const char *peeraddr, int peerport)\r
695 {\r
696 static const struct plug_function_table fn_table = {\r
697 x11_log,\r
698 x11_closing,\r
699 x11_receive,\r
700 x11_sent,\r
701 NULL\r
702 };\r
703 \r
704 struct X11Connection *xconn;\r
705 \r
706 /*\r
707 * Open socket.\r
708 */\r
709 xconn = snew(struct X11Connection);\r
710 xconn->fn = &fn_table;\r
711 xconn->auth_protocol = NULL;\r
712 xconn->authtree = authtree;\r
713 xconn->verified = 0;\r
714 xconn->data_read = 0;\r
715 xconn->throttled = xconn->throttle_override = 0;\r
716 xconn->no_data_sent_to_x_client = TRUE;\r
717 xconn->c = c;\r
718 \r
719 /*\r
720 * We don't actually open a local socket to the X server just yet,\r
721 * because we don't know which one it is. Instead, we'll wait\r
722 * until we see the incoming authentication data, which may tell\r
723 * us what display to connect to, or whether we have to divert\r
724 * this X forwarding channel to a connection-sharing downstream\r
725 * rather than handling it ourself.\r
726 */\r
727 xconn->disp = NULL;\r
728 xconn->s = NULL;\r
729 \r
730 /*\r
731 * Stash the peer address we were given in its original text form.\r
732 */\r
733 xconn->peer_addr = peeraddr ? dupstr(peeraddr) : NULL;\r
734 xconn->peer_port = peerport;\r
735 \r
736 return xconn;\r
737 }\r
738 \r
739 void x11_close(struct X11Connection *xconn)\r
740 {\r
741 if (!xconn)\r
742 return;\r
743 \r
744 if (xconn->auth_protocol) {\r
745 sfree(xconn->auth_protocol);\r
746 sfree(xconn->auth_data);\r
747 }\r
748 \r
749 if (xconn->s)\r
750 sk_close(xconn->s);\r
751 \r
752 sfree(xconn->peer_addr);\r
753 sfree(xconn);\r
754 }\r
755 \r
756 void x11_unthrottle(struct X11Connection *xconn)\r
757 {\r
758 if (!xconn)\r
759 return;\r
760 \r
761 xconn->throttled = 0;\r
762 if (xconn->s)\r
763 sk_set_frozen(xconn->s, xconn->throttled || xconn->throttle_override);\r
764 }\r
765 \r
766 void x11_override_throttle(struct X11Connection *xconn, int enable)\r
767 {\r
768 if (!xconn)\r
769 return;\r
770 \r
771 xconn->throttle_override = enable;\r
772 if (xconn->s)\r
773 sk_set_frozen(xconn->s, xconn->throttled || xconn->throttle_override);\r
774 }\r
775 \r
776 static void x11_send_init_error(struct X11Connection *xconn,\r
777 const char *err_message)\r
778 {\r
779 char *full_message;\r
780 int msglen, msgsize;\r
781 unsigned char *reply;\r
782 \r
783 full_message = dupprintf("%s X11 proxy: %s\n", appname, err_message);\r
784 \r
785 msglen = strlen(full_message);\r
786 reply = snewn(8 + msglen+1 + 4, unsigned char); /* include zero */\r
787 msgsize = (msglen + 3) & ~3;\r
788 reply[0] = 0; /* failure */\r
789 reply[1] = msglen; /* length of reason string */\r
790 memcpy(reply + 2, xconn->firstpkt + 2, 4); /* major/minor proto vsn */\r
791 PUT_16BIT(xconn->firstpkt[0], reply + 6, msgsize >> 2);/* data len */\r
792 memset(reply + 8, 0, msgsize);\r
793 memcpy(reply + 8, full_message, msglen);\r
794 sshfwd_write(xconn->c, (char *)reply, 8 + msgsize);\r
795 sshfwd_write_eof(xconn->c);\r
796 xconn->no_data_sent_to_x_client = FALSE;\r
797 sfree(reply);\r
798 sfree(full_message);\r
799 }\r
800 \r
801 static int x11_parse_ip(const char *addr_string, unsigned long *ip)\r
802 {\r
803 \r
804 /*\r
805 * See if we can make sense of this string as an IPv4 address, for\r
806 * XDM-AUTHORIZATION-1 purposes.\r
807 */\r
808 int i[4];\r
809 if (addr_string &&\r
810 4 == sscanf(addr_string, "%d.%d.%d.%d", i+0, i+1, i+2, i+3)) {\r
811 *ip = (i[0] << 24) | (i[1] << 16) | (i[2] << 8) | i[3];\r
812 return TRUE;\r
813 } else {\r
814 return FALSE;\r
815 }\r
816 }\r
817 \r
818 /*\r
819 * Called to send data down the raw connection.\r
820 */\r
821 int x11_send(struct X11Connection *xconn, char *data, int len)\r
822 {\r
823 if (!xconn)\r
824 return 0;\r
825 \r
826 /*\r
827 * Read the first packet.\r
828 */\r
829 while (len > 0 && xconn->data_read < 12)\r
830 xconn->firstpkt[xconn->data_read++] = (unsigned char) (len--, *data++);\r
831 if (xconn->data_read < 12)\r
832 return 0;\r
833 \r
834 /*\r
835 * If we have not allocated the auth_protocol and auth_data\r
836 * strings, do so now.\r
837 */\r
838 if (!xconn->auth_protocol) {\r
839 xconn->auth_plen = GET_16BIT(xconn->firstpkt[0], xconn->firstpkt + 6);\r
840 xconn->auth_dlen = GET_16BIT(xconn->firstpkt[0], xconn->firstpkt + 8);\r
841 xconn->auth_psize = (xconn->auth_plen + 3) & ~3;\r
842 xconn->auth_dsize = (xconn->auth_dlen + 3) & ~3;\r
843 /* Leave room for a terminating zero, to make our lives easier. */\r
844 xconn->auth_protocol = snewn(xconn->auth_psize + 1, char);\r
845 xconn->auth_data = snewn(xconn->auth_dsize, unsigned char);\r
846 }\r
847 \r
848 /*\r
849 * Read the auth_protocol and auth_data strings.\r
850 */\r
851 while (len > 0 &&\r
852 xconn->data_read < 12 + xconn->auth_psize)\r
853 xconn->auth_protocol[xconn->data_read++ - 12] = (len--, *data++);\r
854 while (len > 0 &&\r
855 xconn->data_read < 12 + xconn->auth_psize + xconn->auth_dsize)\r
856 xconn->auth_data[xconn->data_read++ - 12 -\r
857 xconn->auth_psize] = (unsigned char) (len--, *data++);\r
858 if (xconn->data_read < 12 + xconn->auth_psize + xconn->auth_dsize)\r
859 return 0;\r
860 \r
861 /*\r
862 * If we haven't verified the authorisation, do so now.\r
863 */\r
864 if (!xconn->verified) {\r
865 const char *err;\r
866 struct X11FakeAuth *auth_matched = NULL;\r
867 unsigned long peer_ip;\r
868 int peer_port;\r
869 int protomajor, protominor;\r
870 void *greeting;\r
871 int greeting_len;\r
872 unsigned char *socketdata;\r
873 int socketdatalen;\r
874 char new_peer_addr[32];\r
875 int new_peer_port;\r
876 \r
877 protomajor = GET_16BIT(xconn->firstpkt[0], xconn->firstpkt + 2);\r
878 protominor = GET_16BIT(xconn->firstpkt[0], xconn->firstpkt + 4);\r
879 \r
880 assert(!xconn->s);\r
881 \r
882 xconn->auth_protocol[xconn->auth_plen] = '\0'; /* ASCIZ */\r
883 \r
884 peer_ip = 0; /* placate optimiser */\r
885 if (x11_parse_ip(xconn->peer_addr, &peer_ip))\r
886 peer_port = xconn->peer_port;\r
887 else\r
888 peer_port = -1; /* signal no peer address data available */\r
889 \r
890 err = x11_verify(peer_ip, peer_port,\r
891 xconn->authtree, xconn->auth_protocol,\r
892 xconn->auth_data, xconn->auth_dlen, &auth_matched);\r
893 if (err) {\r
894 x11_send_init_error(xconn, err);\r
895 return 0;\r
896 }\r
897 assert(auth_matched);\r
898 \r
899 /*\r
900 * If this auth points to a connection-sharing downstream\r
901 * rather than an X display we know how to connect to\r
902 * directly, pass it off to the sharing module now.\r
903 */\r
904 if (auth_matched->share_cs) {\r
905 sshfwd_x11_sharing_handover(xconn->c, auth_matched->share_cs,\r
906 auth_matched->share_chan,\r
907 xconn->peer_addr, xconn->peer_port,\r
908 xconn->firstpkt[0],\r
909 protomajor, protominor, data, len);\r
910 return 0;\r
911 }\r
912 \r
913 /*\r
914 * Now we know we're going to accept the connection, and what\r
915 * X display to connect to. Actually connect to it.\r
916 */\r
917 sshfwd_x11_is_local(xconn->c);\r
918 xconn->disp = auth_matched->disp;\r
919 xconn->s = new_connection(sk_addr_dup(xconn->disp->addr),\r
920 xconn->disp->realhost, xconn->disp->port, \r
921 0, 1, 0, 0, (Plug) xconn,\r
922 sshfwd_get_conf(xconn->c));\r
923 if ((err = sk_socket_error(xconn->s)) != NULL) {\r
924 char *err_message = dupprintf("unable to connect to"\r
925 " forwarded X server: %s", err);\r
926 x11_send_init_error(xconn, err_message);\r
927 sfree(err_message);\r
928 return 0;\r
929 }\r
930 \r
931 /*\r
932 * Write a new connection header containing our replacement\r
933 * auth data.\r
934 */\r
935 \r
936 socketdata = sk_getxdmdata(xconn->s, &socketdatalen);\r
937 if (socketdata && socketdatalen==6) {\r
938 sprintf(new_peer_addr, "%d.%d.%d.%d", socketdata[0],\r
939 socketdata[1], socketdata[2], socketdata[3]);\r
940 new_peer_port = GET_16BIT_MSB_FIRST(socketdata + 4);\r
941 } else {\r
942 strcpy(new_peer_addr, "0.0.0.0");\r
943 new_peer_port = 0;\r
944 }\r
945 \r
946 greeting = x11_make_greeting(xconn->firstpkt[0],\r
947 protomajor, protominor,\r
948 xconn->disp->localauthproto,\r
949 xconn->disp->localauthdata,\r
950 xconn->disp->localauthdatalen,\r
951 new_peer_addr, new_peer_port,\r
952 &greeting_len);\r
953 \r
954 sk_write(xconn->s, greeting, greeting_len);\r
955 \r
956 smemclr(greeting, greeting_len);\r
957 sfree(greeting);\r
958 \r
959 /*\r
960 * Now we're done.\r
961 */\r
962 xconn->verified = 1;\r
963 }\r
964 \r
965 /*\r
966 * After initialisation, just copy data simply.\r
967 */\r
968 \r
969 return sk_write(xconn->s, data, len);\r
970 }\r
971 \r
972 void x11_send_eof(struct X11Connection *xconn)\r
973 {\r
974 if (xconn->s) {\r
975 sk_write_eof(xconn->s);\r
976 } else {\r
977 /*\r
978 * If EOF is received from the X client before we've got to\r
979 * the point of actually connecting to an X server, then we\r
980 * should send an EOF back to the client so that the\r
981 * forwarded channel will be terminated.\r
982 */\r
983 if (xconn->c)\r
984 sshfwd_write_eof(xconn->c);\r
985 }\r
986 }\r
987 \r
988 /*\r
989 * Utility functions used by connection sharing to convert textual\r
990 * representations of an X11 auth protocol name + hex cookie into our\r
991 * usual integer protocol id and binary auth data.\r
992 */\r
993 int x11_identify_auth_proto(const char *protoname)\r
994 {\r
995 int protocol;\r
996 \r
997 for (protocol = 1; protocol < lenof(x11_authnames); protocol++)\r
998 if (!strcmp(protoname, x11_authnames[protocol]))\r
999 return protocol;\r
1000 return -1;\r
1001 }\r
1002 \r
1003 void *x11_dehexify(const char *hex, int *outlen)\r
1004 {\r
1005 int len, i;\r
1006 unsigned char *ret;\r
1007 \r
1008 len = strlen(hex) / 2;\r
1009 ret = snewn(len, unsigned char);\r
1010 \r
1011 for (i = 0; i < len; i++) {\r
1012 char bytestr[3];\r
1013 unsigned val = 0;\r
1014 bytestr[0] = hex[2*i];\r
1015 bytestr[1] = hex[2*i+1];\r
1016 bytestr[2] = '\0';\r
1017 sscanf(bytestr, "%x", &val);\r
1018 ret[i] = val;\r
1019 }\r
1020 \r
1021 *outlen = len;\r
1022 return ret;\r
1023 }\r
1024 \r
1025 /*\r
1026 * Construct an X11 greeting packet, including making up the right\r
1027 * authorisation data.\r
1028 */\r
1029 void *x11_make_greeting(int endian, int protomajor, int protominor,\r
1030 int auth_proto, const void *auth_data, int auth_len,\r
1031 const char *peer_addr, int peer_port,\r
1032 int *outlen)\r
1033 {\r
1034 unsigned char *greeting;\r
1035 unsigned char realauthdata[64];\r
1036 const char *authname;\r
1037 const unsigned char *authdata;\r
1038 int authnamelen, authnamelen_pad;\r
1039 int authdatalen, authdatalen_pad;\r
1040 int greeting_len;\r
1041 \r
1042 authname = x11_authnames[auth_proto];\r
1043 authnamelen = strlen(authname);\r
1044 authnamelen_pad = (authnamelen + 3) & ~3;\r
1045 \r
1046 if (auth_proto == X11_MIT) {\r
1047 authdata = auth_data;\r
1048 authdatalen = auth_len;\r
1049 } else if (auth_proto == X11_XDM && auth_len == 16) {\r
1050 time_t t;\r
1051 unsigned long peer_ip = 0;\r
1052 \r
1053 x11_parse_ip(peer_addr, &peer_ip);\r
1054 \r
1055 authdata = realauthdata;\r
1056 authdatalen = 24;\r
1057 memset(realauthdata, 0, authdatalen);\r
1058 memcpy(realauthdata, auth_data, 8);\r
1059 PUT_32BIT_MSB_FIRST(realauthdata+8, peer_ip);\r
1060 PUT_16BIT_MSB_FIRST(realauthdata+12, peer_port);\r
1061 t = time(NULL);\r
1062 PUT_32BIT_MSB_FIRST(realauthdata+14, t);\r
1063 \r
1064 des_encrypt_xdmauth((const unsigned char *)auth_data + 9,\r
1065 realauthdata, authdatalen);\r
1066 } else {\r
1067 authdata = realauthdata;\r
1068 authdatalen = 0;\r
1069 }\r
1070 \r
1071 authdatalen_pad = (authdatalen + 3) & ~3;\r
1072 greeting_len = 12 + authnamelen_pad + authdatalen_pad;\r
1073 \r
1074 greeting = snewn(greeting_len, unsigned char);\r
1075 memset(greeting, 0, greeting_len);\r
1076 greeting[0] = endian;\r
1077 PUT_16BIT(endian, greeting+2, protomajor);\r
1078 PUT_16BIT(endian, greeting+4, protominor);\r
1079 PUT_16BIT(endian, greeting+6, authnamelen);\r
1080 PUT_16BIT(endian, greeting+8, authdatalen);\r
1081 memcpy(greeting+12, authname, authnamelen);\r
1082 memcpy(greeting+12+authnamelen_pad, authdata, authdatalen);\r
1083 \r
1084 smemclr(realauthdata, sizeof(realauthdata));\r
1085 \r
1086 *outlen = greeting_len;\r
1087 return greeting;\r
1088 }\r