1 /***************************************************************************
2 * _ _ ____ _
3 * Project ___| | | | _ \| |
4 * / __| | | | |_) | |
5 * | (__| |_| | _ <| |___
6 * \___|\___/|_| \_\_____|
7 *
8 * Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
9 * Copyright (C) Markus Moeller, <markus_moeller@compuserve.com>
10 *
11 * This software is licensed as described in the file COPYING, which
12 * you should have received as part of this distribution. The terms
13 * are also available at https://curl.se/docs/copyright.html.
14 *
15 * You may opt to use, copy, modify, merge, publish, distribute and/or sell
16 * copies of the Software, and permit persons to whom the Software is
17 * furnished to do so, under the terms of the COPYING file.
18 *
19 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
20 * KIND, either express or implied.
21 *
22 * SPDX-License-Identifier: curl
23 *
24 ***************************************************************************/
25
26 #include "curl_setup.h"
27
28 #if defined(HAVE_GSSAPI) && !defined(CURL_DISABLE_PROXY)
29
30 #include "curl_gssapi.h"
31 #include "urldata.h"
32 #include "sendf.h"
33 #include "cfilters.h"
34 #include "connect.h"
35 #include "timeval.h"
36 #include "socks.h"
37 #include "warnless.h"
38 #include "strdup.h"
39
40 /* The last 3 #include files should be in this order */
41 #include "curl_printf.h"
42 #include "curl_memory.h"
43 #include "memdebug.h"
44
45 #define MAX_GSS_LEN 1024
46
47 static gss_ctx_id_t gss_context = GSS_C_NO_CONTEXT;
48
49 /*
50 * Helper GSS-API error functions.
51 */
check_gss_err(struct Curl_easy * data,OM_uint32 major_status,OM_uint32 minor_status,const char * function)52 static int check_gss_err(struct Curl_easy *data,
53 OM_uint32 major_status,
54 OM_uint32 minor_status,
55 const char *function)
56 {
57 if(GSS_ERROR(major_status)) {
58 OM_uint32 maj_stat, min_stat;
59 OM_uint32 msg_ctx = 0;
60 gss_buffer_desc status_string = GSS_C_EMPTY_BUFFER;
61 struct dynbuf dbuf;
62
63 Curl_dyn_init(&dbuf, MAX_GSS_LEN);
64 msg_ctx = 0;
65 while(!msg_ctx) {
66 /* convert major status code (GSS-API error) to text */
67 maj_stat = gss_display_status(&min_stat, major_status,
68 GSS_C_GSS_CODE,
69 GSS_C_NULL_OID,
70 &msg_ctx, &status_string);
71 if(maj_stat == GSS_S_COMPLETE) {
72 if(Curl_dyn_addn(&dbuf, status_string.value,
73 status_string.length))
74 return 1; /* error */
75 gss_release_buffer(&min_stat, &status_string);
76 break;
77 }
78 gss_release_buffer(&min_stat, &status_string);
79 }
80 if(Curl_dyn_addn(&dbuf, ".\n", 2))
81 return 1; /* error */
82 msg_ctx = 0;
83 while(!msg_ctx) {
84 /* convert minor status code (underlying routine error) to text */
85 maj_stat = gss_display_status(&min_stat, minor_status,
86 GSS_C_MECH_CODE,
87 GSS_C_NULL_OID,
88 &msg_ctx, &status_string);
89 if(maj_stat == GSS_S_COMPLETE) {
90 if(Curl_dyn_addn(&dbuf, status_string.value,
91 status_string.length))
92 return 1; /* error */
93 gss_release_buffer(&min_stat, &status_string);
94 break;
95 }
96 gss_release_buffer(&min_stat, &status_string);
97 }
98 failf(data, "GSS-API error: %s failed: %s", function, Curl_dyn_ptr(&dbuf));
99 Curl_dyn_free(&dbuf);
100 return 1;
101 }
102
103 return 0;
104 }
105
Curl_SOCKS5_gssapi_negotiate(struct Curl_cfilter * cf,struct Curl_easy * data)106 CURLcode Curl_SOCKS5_gssapi_negotiate(struct Curl_cfilter *cf,
107 struct Curl_easy *data)
108 {
109 struct connectdata *conn = cf->conn;
110 curl_socket_t sock = conn->sock[cf->sockindex];
111 CURLcode code;
112 ssize_t actualread;
113 ssize_t nwritten;
114 int result;
115 OM_uint32 gss_major_status, gss_minor_status, gss_status;
116 OM_uint32 gss_ret_flags;
117 int gss_conf_state, gss_enc;
118 gss_buffer_desc service = GSS_C_EMPTY_BUFFER;
119 gss_buffer_desc gss_send_token = GSS_C_EMPTY_BUFFER;
120 gss_buffer_desc gss_recv_token = GSS_C_EMPTY_BUFFER;
121 gss_buffer_desc gss_w_token = GSS_C_EMPTY_BUFFER;
122 gss_buffer_desc *gss_token = GSS_C_NO_BUFFER;
123 gss_name_t server = GSS_C_NO_NAME;
124 gss_name_t gss_client_name = GSS_C_NO_NAME;
125 unsigned short us_length;
126 char *user = NULL;
127 unsigned char socksreq[4]; /* room for GSS-API exchange header only */
128 const char *serviceptr = data->set.str[STRING_PROXY_SERVICE_NAME] ?
129 data->set.str[STRING_PROXY_SERVICE_NAME] : "rcmd";
130 const size_t serviceptr_length = strlen(serviceptr);
131
132 /* GSS-API request looks like
133 * +----+------+-----+----------------+
134 * |VER | MTYP | LEN | TOKEN |
135 * +----+------+----------------------+
136 * | 1 | 1 | 2 | up to 2^16 - 1 |
137 * +----+------+-----+----------------+
138 */
139
140 /* prepare service name */
141 if(strchr(serviceptr, '/')) {
142 service.length = serviceptr_length;
143 service.value = Curl_memdup(serviceptr, service.length);
144 if(!service.value)
145 return CURLE_OUT_OF_MEMORY;
146
147 gss_major_status = gss_import_name(&gss_minor_status, &service,
148 (gss_OID) GSS_C_NULL_OID, &server);
149 }
150 else {
151 service.value = malloc(serviceptr_length +
152 strlen(conn->socks_proxy.host.name) + 2);
153 if(!service.value)
154 return CURLE_OUT_OF_MEMORY;
155 service.length = serviceptr_length +
156 strlen(conn->socks_proxy.host.name) + 1;
157 msnprintf(service.value, service.length + 1, "%s@%s",
158 serviceptr, conn->socks_proxy.host.name);
159
160 gss_major_status = gss_import_name(&gss_minor_status, &service,
161 GSS_C_NT_HOSTBASED_SERVICE, &server);
162 }
163
164 gss_release_buffer(&gss_status, &service); /* clear allocated memory */
165
166 if(check_gss_err(data, gss_major_status,
167 gss_minor_status, "gss_import_name()")) {
168 failf(data, "Failed to create service name.");
169 gss_release_name(&gss_status, &server);
170 return CURLE_COULDNT_CONNECT;
171 }
172
173 (void)curlx_nonblock(sock, FALSE);
174
175 /* As long as we need to keep sending some context info, and there is no */
176 /* errors, keep sending it... */
177 for(;;) {
178 gss_major_status = Curl_gss_init_sec_context(data,
179 &gss_minor_status,
180 &gss_context,
181 server,
182 &Curl_krb5_mech_oid,
183 NULL,
184 gss_token,
185 &gss_send_token,
186 TRUE,
187 &gss_ret_flags);
188
189 if(gss_token != GSS_C_NO_BUFFER)
190 gss_release_buffer(&gss_status, &gss_recv_token);
191 if(check_gss_err(data, gss_major_status,
192 gss_minor_status, "gss_init_sec_context")) {
193 gss_release_name(&gss_status, &server);
194 gss_release_buffer(&gss_status, &gss_recv_token);
195 gss_release_buffer(&gss_status, &gss_send_token);
196 gss_delete_sec_context(&gss_status, &gss_context, NULL);
197 failf(data, "Failed to initial GSS-API token.");
198 return CURLE_COULDNT_CONNECT;
199 }
200
201 if(gss_send_token.length) {
202 socksreq[0] = 1; /* GSS-API subnegotiation version */
203 socksreq[1] = 1; /* authentication message type */
204 us_length = htons((unsigned short)gss_send_token.length);
205 memcpy(socksreq + 2, &us_length, sizeof(short));
206
207 nwritten = Curl_conn_cf_send(cf->next, data, (char *)socksreq, 4,
208 FALSE, &code);
209 if(code || (4 != nwritten)) {
210 failf(data, "Failed to send GSS-API authentication request.");
211 gss_release_name(&gss_status, &server);
212 gss_release_buffer(&gss_status, &gss_recv_token);
213 gss_release_buffer(&gss_status, &gss_send_token);
214 gss_delete_sec_context(&gss_status, &gss_context, NULL);
215 return CURLE_COULDNT_CONNECT;
216 }
217
218 nwritten = Curl_conn_cf_send(cf->next, data,
219 (char *)gss_send_token.value,
220 gss_send_token.length, FALSE, &code);
221 if(code || ((ssize_t)gss_send_token.length != nwritten)) {
222 failf(data, "Failed to send GSS-API authentication token.");
223 gss_release_name(&gss_status, &server);
224 gss_release_buffer(&gss_status, &gss_recv_token);
225 gss_release_buffer(&gss_status, &gss_send_token);
226 gss_delete_sec_context(&gss_status, &gss_context, NULL);
227 return CURLE_COULDNT_CONNECT;
228 }
229
230 }
231
232 gss_release_buffer(&gss_status, &gss_send_token);
233 gss_release_buffer(&gss_status, &gss_recv_token);
234 if(gss_major_status != GSS_S_CONTINUE_NEEDED)
235 break;
236
237 /* analyse response */
238
239 /* GSS-API response looks like
240 * +----+------+-----+----------------+
241 * |VER | MTYP | LEN | TOKEN |
242 * +----+------+----------------------+
243 * | 1 | 1 | 2 | up to 2^16 - 1 |
244 * +----+------+-----+----------------+
245 */
246
247 result = Curl_blockread_all(cf, data, (char *)socksreq, 4, &actualread);
248 if(result || (actualread != 4)) {
249 failf(data, "Failed to receive GSS-API authentication response.");
250 gss_release_name(&gss_status, &server);
251 gss_delete_sec_context(&gss_status, &gss_context, NULL);
252 return CURLE_COULDNT_CONNECT;
253 }
254
255 /* ignore the first (VER) byte */
256 if(socksreq[1] == 255) { /* status / message type */
257 failf(data, "User was rejected by the SOCKS5 server (%d %d).",
258 socksreq[0], socksreq[1]);
259 gss_release_name(&gss_status, &server);
260 gss_delete_sec_context(&gss_status, &gss_context, NULL);
261 return CURLE_COULDNT_CONNECT;
262 }
263
264 if(socksreq[1] != 1) { /* status / message type */
265 failf(data, "Invalid GSS-API authentication response type (%d %d).",
266 socksreq[0], socksreq[1]);
267 gss_release_name(&gss_status, &server);
268 gss_delete_sec_context(&gss_status, &gss_context, NULL);
269 return CURLE_COULDNT_CONNECT;
270 }
271
272 memcpy(&us_length, socksreq + 2, sizeof(short));
273 us_length = ntohs(us_length);
274
275 gss_recv_token.length = us_length;
276 gss_recv_token.value = malloc(us_length);
277 if(!gss_recv_token.value) {
278 failf(data,
279 "Could not allocate memory for GSS-API authentication "
280 "response token.");
281 gss_release_name(&gss_status, &server);
282 gss_delete_sec_context(&gss_status, &gss_context, NULL);
283 return CURLE_OUT_OF_MEMORY;
284 }
285
286 result = Curl_blockread_all(cf, data, (char *)gss_recv_token.value,
287 gss_recv_token.length, &actualread);
288
289 if(result || (actualread != us_length)) {
290 failf(data, "Failed to receive GSS-API authentication token.");
291 gss_release_name(&gss_status, &server);
292 gss_release_buffer(&gss_status, &gss_recv_token);
293 gss_delete_sec_context(&gss_status, &gss_context, NULL);
294 return CURLE_COULDNT_CONNECT;
295 }
296
297 gss_token = &gss_recv_token;
298 }
299
300 gss_release_name(&gss_status, &server);
301
302 /* Everything is good so far, user was authenticated! */
303 gss_major_status = gss_inquire_context(&gss_minor_status, gss_context,
304 &gss_client_name, NULL, NULL, NULL,
305 NULL, NULL, NULL);
306 if(check_gss_err(data, gss_major_status,
307 gss_minor_status, "gss_inquire_context")) {
308 gss_delete_sec_context(&gss_status, &gss_context, NULL);
309 gss_release_name(&gss_status, &gss_client_name);
310 failf(data, "Failed to determine username.");
311 return CURLE_COULDNT_CONNECT;
312 }
313 gss_major_status = gss_display_name(&gss_minor_status, gss_client_name,
314 &gss_send_token, NULL);
315 if(check_gss_err(data, gss_major_status,
316 gss_minor_status, "gss_display_name")) {
317 gss_delete_sec_context(&gss_status, &gss_context, NULL);
318 gss_release_name(&gss_status, &gss_client_name);
319 gss_release_buffer(&gss_status, &gss_send_token);
320 failf(data, "Failed to determine username.");
321 return CURLE_COULDNT_CONNECT;
322 }
323 user = malloc(gss_send_token.length + 1);
324 if(!user) {
325 gss_delete_sec_context(&gss_status, &gss_context, NULL);
326 gss_release_name(&gss_status, &gss_client_name);
327 gss_release_buffer(&gss_status, &gss_send_token);
328 return CURLE_OUT_OF_MEMORY;
329 }
330
331 memcpy(user, gss_send_token.value, gss_send_token.length);
332 user[gss_send_token.length] = '\0';
333 gss_release_name(&gss_status, &gss_client_name);
334 gss_release_buffer(&gss_status, &gss_send_token);
335 infof(data, "SOCKS5 server authenticated user %s with GSS-API.",user);
336 free(user);
337 user = NULL;
338
339 /* Do encryption */
340 socksreq[0] = 1; /* GSS-API subnegotiation version */
341 socksreq[1] = 2; /* encryption message type */
342
343 gss_enc = 0; /* no data protection */
344 /* do confidentiality protection if supported */
345 if(gss_ret_flags & GSS_C_CONF_FLAG)
346 gss_enc = 2;
347 /* else do integrity protection */
348 else if(gss_ret_flags & GSS_C_INTEG_FLAG)
349 gss_enc = 1;
350
351 infof(data, "SOCKS5 server supports GSS-API %s data protection.",
352 (gss_enc == 0) ? "no" :
353 ((gss_enc == 1) ? "integrity" : "confidentiality"));
354 /* force for the moment to no data protection */
355 gss_enc = 0;
356 /*
357 * Sending the encryption type in clear seems wrong. It should be
358 * protected with gss_seal()/gss_wrap(). See RFC1961 extract below
359 * The NEC reference implementations on which this is based is
360 * therefore at fault
361 *
362 * +------+------+------+.......................+
363 * + ver | mtyp | len | token |
364 * +------+------+------+.......................+
365 * + 0x01 | 0x02 | 0x02 | up to 2^16 - 1 octets |
366 * +------+------+------+.......................+
367 *
368 * Where:
369 *
370 * - "ver" is the protocol version number, here 1 to represent the
371 * first version of the SOCKS/GSS-API protocol
372 *
373 * - "mtyp" is the message type, here 2 to represent a protection
374 * -level negotiation message
375 *
376 * - "len" is the length of the "token" field in octets
377 *
378 * - "token" is the GSS-API encapsulated protection level
379 *
380 * The token is produced by encapsulating an octet containing the
381 * required protection level using gss_seal()/gss_wrap() with conf_req
382 * set to FALSE. The token is verified using gss_unseal()/
383 * gss_unwrap().
384 *
385 */
386 if(data->set.socks5_gssapi_nec) {
387 us_length = htons((short)1);
388 memcpy(socksreq + 2, &us_length, sizeof(short));
389 }
390 else {
391 gss_send_token.length = 1;
392 gss_send_token.value = Curl_memdup(&gss_enc, 1);
393 if(!gss_send_token.value) {
394 gss_delete_sec_context(&gss_status, &gss_context, NULL);
395 return CURLE_OUT_OF_MEMORY;
396 }
397
398 gss_major_status = gss_wrap(&gss_minor_status, gss_context, 0,
399 GSS_C_QOP_DEFAULT, &gss_send_token,
400 &gss_conf_state, &gss_w_token);
401
402 if(check_gss_err(data, gss_major_status, gss_minor_status, "gss_wrap")) {
403 gss_release_buffer(&gss_status, &gss_send_token);
404 gss_release_buffer(&gss_status, &gss_w_token);
405 gss_delete_sec_context(&gss_status, &gss_context, NULL);
406 failf(data, "Failed to wrap GSS-API encryption value into token.");
407 return CURLE_COULDNT_CONNECT;
408 }
409 gss_release_buffer(&gss_status, &gss_send_token);
410
411 us_length = htons((unsigned short)gss_w_token.length);
412 memcpy(socksreq + 2, &us_length, sizeof(short));
413 }
414
415 nwritten = Curl_conn_cf_send(cf->next, data, (char *)socksreq, 4, FALSE,
416 &code);
417 if(code || (4 != nwritten)) {
418 failf(data, "Failed to send GSS-API encryption request.");
419 gss_release_buffer(&gss_status, &gss_w_token);
420 gss_delete_sec_context(&gss_status, &gss_context, NULL);
421 return CURLE_COULDNT_CONNECT;
422 }
423
424 if(data->set.socks5_gssapi_nec) {
425 memcpy(socksreq, &gss_enc, 1);
426 nwritten = Curl_conn_cf_send(cf->next, data, (char *)socksreq, 1, FALSE,
427 &code);
428 if(code || ( 1 != nwritten)) {
429 failf(data, "Failed to send GSS-API encryption type.");
430 gss_delete_sec_context(&gss_status, &gss_context, NULL);
431 return CURLE_COULDNT_CONNECT;
432 }
433 }
434 else {
435 nwritten = Curl_conn_cf_send(cf->next, data,
436 (char *)gss_w_token.value,
437 gss_w_token.length, FALSE, &code);
438 if(code || ((ssize_t)gss_w_token.length != nwritten)) {
439 failf(data, "Failed to send GSS-API encryption type.");
440 gss_release_buffer(&gss_status, &gss_w_token);
441 gss_delete_sec_context(&gss_status, &gss_context, NULL);
442 return CURLE_COULDNT_CONNECT;
443 }
444 gss_release_buffer(&gss_status, &gss_w_token);
445 }
446
447 result = Curl_blockread_all(cf, data, (char *)socksreq, 4, &actualread);
448 if(result || (actualread != 4)) {
449 failf(data, "Failed to receive GSS-API encryption response.");
450 gss_delete_sec_context(&gss_status, &gss_context, NULL);
451 return CURLE_COULDNT_CONNECT;
452 }
453
454 /* ignore the first (VER) byte */
455 if(socksreq[1] == 255) { /* status / message type */
456 failf(data, "User was rejected by the SOCKS5 server (%d %d).",
457 socksreq[0], socksreq[1]);
458 gss_delete_sec_context(&gss_status, &gss_context, NULL);
459 return CURLE_COULDNT_CONNECT;
460 }
461
462 if(socksreq[1] != 2) { /* status / message type */
463 failf(data, "Invalid GSS-API encryption response type (%d %d).",
464 socksreq[0], socksreq[1]);
465 gss_delete_sec_context(&gss_status, &gss_context, NULL);
466 return CURLE_COULDNT_CONNECT;
467 }
468
469 memcpy(&us_length, socksreq + 2, sizeof(short));
470 us_length = ntohs(us_length);
471
472 gss_recv_token.length = us_length;
473 gss_recv_token.value = malloc(gss_recv_token.length);
474 if(!gss_recv_token.value) {
475 gss_delete_sec_context(&gss_status, &gss_context, NULL);
476 return CURLE_OUT_OF_MEMORY;
477 }
478 result = Curl_blockread_all(cf, data, (char *)gss_recv_token.value,
479 gss_recv_token.length, &actualread);
480
481 if(result || (actualread != us_length)) {
482 failf(data, "Failed to receive GSS-API encryption type.");
483 gss_release_buffer(&gss_status, &gss_recv_token);
484 gss_delete_sec_context(&gss_status, &gss_context, NULL);
485 return CURLE_COULDNT_CONNECT;
486 }
487
488 if(!data->set.socks5_gssapi_nec) {
489 gss_major_status = gss_unwrap(&gss_minor_status, gss_context,
490 &gss_recv_token, &gss_w_token,
491 0, GSS_C_QOP_DEFAULT);
492
493 if(check_gss_err(data, gss_major_status, gss_minor_status, "gss_unwrap")) {
494 gss_release_buffer(&gss_status, &gss_recv_token);
495 gss_release_buffer(&gss_status, &gss_w_token);
496 gss_delete_sec_context(&gss_status, &gss_context, NULL);
497 failf(data, "Failed to unwrap GSS-API encryption value into token.");
498 return CURLE_COULDNT_CONNECT;
499 }
500 gss_release_buffer(&gss_status, &gss_recv_token);
501
502 if(gss_w_token.length != 1) {
503 failf(data, "Invalid GSS-API encryption response length (%zu).",
504 gss_w_token.length);
505 gss_release_buffer(&gss_status, &gss_w_token);
506 gss_delete_sec_context(&gss_status, &gss_context, NULL);
507 return CURLE_COULDNT_CONNECT;
508 }
509
510 memcpy(socksreq, gss_w_token.value, gss_w_token.length);
511 gss_release_buffer(&gss_status, &gss_w_token);
512 }
513 else {
514 if(gss_recv_token.length != 1) {
515 failf(data, "Invalid GSS-API encryption response length (%zu).",
516 gss_recv_token.length);
517 gss_release_buffer(&gss_status, &gss_recv_token);
518 gss_delete_sec_context(&gss_status, &gss_context, NULL);
519 return CURLE_COULDNT_CONNECT;
520 }
521
522 memcpy(socksreq, gss_recv_token.value, gss_recv_token.length);
523 gss_release_buffer(&gss_status, &gss_recv_token);
524 }
525
526 (void)curlx_nonblock(sock, TRUE);
527
528 infof(data, "SOCKS5 access with%s protection granted.",
529 (socksreq[0] == 0) ? "out GSS-API data":
530 ((socksreq[0] == 1) ? " GSS-API integrity" :
531 " GSS-API confidentiality"));
532
533 conn->socks5_gssapi_enctype = socksreq[0];
534 if(socksreq[0] == 0)
535 gss_delete_sec_context(&gss_status, &gss_context, NULL);
536
537 return CURLE_OK;
538 }
539
540 #endif /* HAVE_GSSAPI && !CURL_DISABLE_PROXY */
541
