1/***************************************************************************
2 * _ _ ____ _
3 * Project ___| | | | _ \| |
4 * / __| | | | |_) | |
5 * | (__| |_| | _ <| |___
6 * \___|\___/|_| \_\_____|
7 *
8 * Copyright (C) 2012 - 2022, Daniel Stenberg, <[email protected]>, et al.
9 * Copyright (C) 2012, Markus Moeller, <[email protected]>
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 "connect.h"
34#include "timeval.h"
35#include "socks.h"
36#include "warnless.h"
37
38/* The last 3 #include files should be in this order */
39#include "curl_printf.h"
40#include "curl_memory.h"
41#include "memdebug.h"
42
43static gss_ctx_id_t gss_context = GSS_C_NO_CONTEXT;
44
45/*
46 * Helper GSS-API error functions.
47 */
48static int check_gss_err(struct Curl_easy *data,
49 OM_uint32 major_status,
50 OM_uint32 minor_status,
51 const char *function)
52{
53 if(GSS_ERROR(major_status)) {
54 OM_uint32 maj_stat, min_stat;
55 OM_uint32 msg_ctx = 0;
56 gss_buffer_desc status_string = GSS_C_EMPTY_BUFFER;
57 char buf[1024];
58 size_t len;
59
60 len = 0;
61 msg_ctx = 0;
62 while(!msg_ctx) {
63 /* convert major status code (GSS-API error) to text */
64 maj_stat = gss_display_status(&min_stat, major_status,
65 GSS_C_GSS_CODE,
66 GSS_C_NULL_OID,
67 &msg_ctx, &status_string);
68 if(maj_stat == GSS_S_COMPLETE) {
69 if(sizeof(buf) > len + status_string.length + 1) {
70 strcpy(buf + len, (char *) status_string.value);
71 len += status_string.length;
72 }
73 gss_release_buffer(&min_stat, &status_string);
74 break;
75 }
76 gss_release_buffer(&min_stat, &status_string);
77 }
78 if(sizeof(buf) > len + 3) {
79 strcpy(buf + len, ".\n");
80 len += 2;
81 }
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(sizeof(buf) > len + status_string.length)
91 strcpy(buf + len, (char *) status_string.value);
92 gss_release_buffer(&min_stat, &status_string);
93 break;
94 }
95 gss_release_buffer(&min_stat, &status_string);
96 }
97 failf(data, "GSS-API error: %s failed: %s", function, buf);
98 return 1;
99 }
100
101 return 0;
102}
103
104CURLcode Curl_SOCKS5_gssapi_negotiate(int sockindex,
105 struct Curl_easy *data)
106{
107 struct connectdata *conn = data->conn;
108 curl_socket_t sock = conn->sock[sockindex];
109 CURLcode code;
110 ssize_t actualread;
111 ssize_t written;
112 int result;
113 OM_uint32 gss_major_status, gss_minor_status, gss_status;
114 OM_uint32 gss_ret_flags;
115 int gss_conf_state, gss_enc;
116 gss_buffer_desc service = GSS_C_EMPTY_BUFFER;
117 gss_buffer_desc gss_send_token = GSS_C_EMPTY_BUFFER;
118 gss_buffer_desc gss_recv_token = GSS_C_EMPTY_BUFFER;
119 gss_buffer_desc gss_w_token = GSS_C_EMPTY_BUFFER;
120 gss_buffer_desc *gss_token = GSS_C_NO_BUFFER;
121 gss_name_t server = GSS_C_NO_NAME;
122 gss_name_t gss_client_name = GSS_C_NO_NAME;
123 unsigned short us_length;
124 char *user = NULL;
125 unsigned char socksreq[4]; /* room for GSS-API exchange header only */
126 const char *serviceptr = data->set.str[STRING_PROXY_SERVICE_NAME] ?
127 data->set.str[STRING_PROXY_SERVICE_NAME] : "rcmd";
128 const size_t serviceptr_length = strlen(serviceptr);
129
130 /* GSS-API request looks like
131 * +----+------+-----+----------------+
132 * |VER | MTYP | LEN | TOKEN |
133 * +----+------+----------------------+
134 * | 1 | 1 | 2 | up to 2^16 - 1 |
135 * +----+------+-----+----------------+
136 */
137
138 /* prepare service name */
139 if(strchr(serviceptr, '/')) {
140 service.length = serviceptr_length;
141 service.value = malloc(service.length);
142 if(!service.value)
143 return CURLE_OUT_OF_MEMORY;
144 memcpy(service.value, serviceptr, service.length);
145
146 gss_major_status = gss_import_name(&gss_minor_status, &service,
147 (gss_OID) GSS_C_NULL_OID, &server);
148 }
149 else {
150 service.value = malloc(serviceptr_length +
151 strlen(conn->socks_proxy.host.name) + 2);
152 if(!service.value)
153 return CURLE_OUT_OF_MEMORY;
154 service.length = serviceptr_length +
155 strlen(conn->socks_proxy.host.name) + 1;
156 msnprintf(service.value, service.length + 1, "%s@%s",
157 serviceptr, conn->socks_proxy.host.name);
158
159 gss_major_status = gss_import_name(&gss_minor_status, &service,
160 GSS_C_NT_HOSTBASED_SERVICE, &server);
161 }
162
163 gss_release_buffer(&gss_status, &service); /* clear allocated memory */
164
165 if(check_gss_err(data, gss_major_status,
166 gss_minor_status, "gss_import_name()")) {
167 failf(data, "Failed to create service name.");
168 gss_release_name(&gss_status, &server);
169 return CURLE_COULDNT_CONNECT;
170 }
171
172 (void)curlx_nonblock(sock, FALSE);
173
174 /* As long as we need to keep sending some context info, and there's no */
175 /* errors, keep sending it... */
176 for(;;) {
177 gss_major_status = Curl_gss_init_sec_context(data,
178 &gss_minor_status,
179 &gss_context,
180 server,
181 &Curl_krb5_mech_oid,
182 NULL,
183 gss_token,
184 &gss_send_token,
185 TRUE,
186 &gss_ret_flags);
187
188 if(gss_token != GSS_C_NO_BUFFER)
189 gss_release_buffer(&gss_status, &gss_recv_token);
190 if(check_gss_err(data, gss_major_status,
191 gss_minor_status, "gss_init_sec_context")) {
192 gss_release_name(&gss_status, &server);
193 gss_release_buffer(&gss_status, &gss_recv_token);
194 gss_release_buffer(&gss_status, &gss_send_token);
195 gss_delete_sec_context(&gss_status, &gss_context, NULL);
196 failf(data, "Failed to initial GSS-API token.");
197 return CURLE_COULDNT_CONNECT;
198 }
199
200 if(gss_send_token.length) {
201 socksreq[0] = 1; /* GSS-API subnegotiation version */
202 socksreq[1] = 1; /* authentication message type */
203 us_length = htons((short)gss_send_token.length);
204 memcpy(socksreq + 2, &us_length, sizeof(short));
205
206 code = Curl_write_plain(data, sock, (char *)socksreq, 4, &written);
207 if(code || (4 != written)) {
208 failf(data, "Failed to send GSS-API authentication request.");
209 gss_release_name(&gss_status, &server);
210 gss_release_buffer(&gss_status, &gss_recv_token);
211 gss_release_buffer(&gss_status, &gss_send_token);
212 gss_delete_sec_context(&gss_status, &gss_context, NULL);
213 return CURLE_COULDNT_CONNECT;
214 }
215
216 code = Curl_write_plain(data, sock, (char *)gss_send_token.value,
217 gss_send_token.length, &written);
218
219 if(code || ((ssize_t)gss_send_token.length != written)) {
220 failf(data, "Failed to send GSS-API authentication token.");
221 gss_release_name(&gss_status, &server);
222 gss_release_buffer(&gss_status, &gss_recv_token);
223 gss_release_buffer(&gss_status, &gss_send_token);
224 gss_delete_sec_context(&gss_status, &gss_context, NULL);
225 return CURLE_COULDNT_CONNECT;
226 }
227
228 }
229
230 gss_release_buffer(&gss_status, &gss_send_token);
231 gss_release_buffer(&gss_status, &gss_recv_token);
232 if(gss_major_status != GSS_S_CONTINUE_NEEDED)
233 break;
234
235 /* analyse response */
236
237 /* GSS-API response looks like
238 * +----+------+-----+----------------+
239 * |VER | MTYP | LEN | TOKEN |
240 * +----+------+----------------------+
241 * | 1 | 1 | 2 | up to 2^16 - 1 |
242 * +----+------+-----+----------------+
243 */
244
245 result = Curl_blockread_all(data, sock, (char *)socksreq, 4, &actualread);
246 if(result || (actualread != 4)) {
247 failf(data, "Failed to receive GSS-API authentication response.");
248 gss_release_name(&gss_status, &server);
249 gss_delete_sec_context(&gss_status, &gss_context, NULL);
250 return CURLE_COULDNT_CONNECT;
251 }
252
253 /* ignore the first (VER) byte */
254 if(socksreq[1] == 255) { /* status / message type */
255 failf(data, "User was rejected by the SOCKS5 server (%d %d).",
256 socksreq[0], socksreq[1]);
257 gss_release_name(&gss_status, &server);
258 gss_delete_sec_context(&gss_status, &gss_context, NULL);
259 return CURLE_COULDNT_CONNECT;
260 }
261
262 if(socksreq[1] != 1) { /* status / message type */
263 failf(data, "Invalid GSS-API authentication response type (%d %d).",
264 socksreq[0], socksreq[1]);
265 gss_release_name(&gss_status, &server);
266 gss_delete_sec_context(&gss_status, &gss_context, NULL);
267 return CURLE_COULDNT_CONNECT;
268 }
269
270 memcpy(&us_length, socksreq + 2, sizeof(short));
271 us_length = ntohs(us_length);
272
273 gss_recv_token.length = us_length;
274 gss_recv_token.value = malloc(us_length);
275 if(!gss_recv_token.value) {
276 failf(data,
277 "Could not allocate memory for GSS-API authentication "
278 "response token.");
279 gss_release_name(&gss_status, &server);
280 gss_delete_sec_context(&gss_status, &gss_context, NULL);
281 return CURLE_OUT_OF_MEMORY;
282 }
283
284 result = Curl_blockread_all(data, sock, (char *)gss_recv_token.value,
285 gss_recv_token.length, &actualread);
286
287 if(result || (actualread != us_length)) {
288 failf(data, "Failed to receive GSS-API authentication token.");
289 gss_release_name(&gss_status, &server);
290 gss_release_buffer(&gss_status, &gss_recv_token);
291 gss_delete_sec_context(&gss_status, &gss_context, NULL);
292 return CURLE_COULDNT_CONNECT;
293 }
294
295 gss_token = &gss_recv_token;
296 }
297
298 gss_release_name(&gss_status, &server);
299
300 /* Everything is good so far, user was authenticated! */
301 gss_major_status = gss_inquire_context(&gss_minor_status, gss_context,
302 &gss_client_name, NULL, NULL, NULL,
303 NULL, NULL, NULL);
304 if(check_gss_err(data, gss_major_status,
305 gss_minor_status, "gss_inquire_context")) {
306 gss_delete_sec_context(&gss_status, &gss_context, NULL);
307 gss_release_name(&gss_status, &gss_client_name);
308 failf(data, "Failed to determine user name.");
309 return CURLE_COULDNT_CONNECT;
310 }
311 gss_major_status = gss_display_name(&gss_minor_status, gss_client_name,
312 &gss_send_token, NULL);
313 if(check_gss_err(data, gss_major_status,
314 gss_minor_status, "gss_display_name")) {
315 gss_delete_sec_context(&gss_status, &gss_context, NULL);
316 gss_release_name(&gss_status, &gss_client_name);
317 gss_release_buffer(&gss_status, &gss_send_token);
318 failf(data, "Failed to determine user name.");
319 return CURLE_COULDNT_CONNECT;
320 }
321 user = malloc(gss_send_token.length + 1);
322 if(!user) {
323 gss_delete_sec_context(&gss_status, &gss_context, NULL);
324 gss_release_name(&gss_status, &gss_client_name);
325 gss_release_buffer(&gss_status, &gss_send_token);
326 return CURLE_OUT_OF_MEMORY;
327 }
328
329 memcpy(user, gss_send_token.value, gss_send_token.length);
330 user[gss_send_token.length] = '\0';
331 gss_release_name(&gss_status, &gss_client_name);
332 gss_release_buffer(&gss_status, &gss_send_token);
333 infof(data, "SOCKS5 server authenticated user %s with GSS-API.",user);
334 free(user);
335 user = NULL;
336
337 /* Do encryption */
338 socksreq[0] = 1; /* GSS-API subnegotiation version */
339 socksreq[1] = 2; /* encryption message type */
340
341 gss_enc = 0; /* no data protection */
342 /* do confidentiality protection if supported */
343 if(gss_ret_flags & GSS_C_CONF_FLAG)
344 gss_enc = 2;
345 /* else do integrity protection */
346 else if(gss_ret_flags & GSS_C_INTEG_FLAG)
347 gss_enc = 1;
348
349 infof(data, "SOCKS5 server supports GSS-API %s data protection.",
350 (gss_enc == 0)?"no":((gss_enc==1)?"integrity":"confidentiality"));
351 /* force for the moment to no data protection */
352 gss_enc = 0;
353 /*
354 * Sending the encryption type in clear seems wrong. It should be
355 * protected with gss_seal()/gss_wrap(). See RFC1961 extract below
356 * The NEC reference implementations on which this is based is
357 * therefore at fault
358 *
359 * +------+------+------+.......................+
360 * + ver | mtyp | len | token |
361 * +------+------+------+.......................+
362 * + 0x01 | 0x02 | 0x02 | up to 2^16 - 1 octets |
363 * +------+------+------+.......................+
364 *
365 * Where:
366 *
367 * - "ver" is the protocol version number, here 1 to represent the
368 * first version of the SOCKS/GSS-API protocol
369 *
370 * - "mtyp" is the message type, here 2 to represent a protection
371 * -level negotiation message
372 *
373 * - "len" is the length of the "token" field in octets
374 *
375 * - "token" is the GSS-API encapsulated protection level
376 *
377 * The token is produced by encapsulating an octet containing the
378 * required protection level using gss_seal()/gss_wrap() with conf_req
379 * set to FALSE. The token is verified using gss_unseal()/
380 * gss_unwrap().
381 *
382 */
383 if(data->set.socks5_gssapi_nec) {
384 us_length = htons((short)1);
385 memcpy(socksreq + 2, &us_length, sizeof(short));
386 }
387 else {
388 gss_send_token.length = 1;
389 gss_send_token.value = malloc(1);
390 if(!gss_send_token.value) {
391 gss_delete_sec_context(&gss_status, &gss_context, NULL);
392 return CURLE_OUT_OF_MEMORY;
393 }
394 memcpy(gss_send_token.value, &gss_enc, 1);
395
396 gss_major_status = gss_wrap(&gss_minor_status, gss_context, 0,
397 GSS_C_QOP_DEFAULT, &gss_send_token,
398 &gss_conf_state, &gss_w_token);
399
400 if(check_gss_err(data, gss_major_status, gss_minor_status, "gss_wrap")) {
401 gss_release_buffer(&gss_status, &gss_send_token);
402 gss_release_buffer(&gss_status, &gss_w_token);
403 gss_delete_sec_context(&gss_status, &gss_context, NULL);
404 failf(data, "Failed to wrap GSS-API encryption value into token.");
405 return CURLE_COULDNT_CONNECT;
406 }
407 gss_release_buffer(&gss_status, &gss_send_token);
408
409 us_length = htons((short)gss_w_token.length);
410 memcpy(socksreq + 2, &us_length, sizeof(short));
411 }
412
413 code = Curl_write_plain(data, sock, (char *)socksreq, 4, &written);
414 if(code || (4 != written)) {
415 failf(data, "Failed to send GSS-API encryption request.");
416 gss_release_buffer(&gss_status, &gss_w_token);
417 gss_delete_sec_context(&gss_status, &gss_context, NULL);
418 return CURLE_COULDNT_CONNECT;
419 }
420
421 if(data->set.socks5_gssapi_nec) {
422 memcpy(socksreq, &gss_enc, 1);
423 code = Curl_write_plain(data, sock, socksreq, 1, &written);
424 if(code || ( 1 != written)) {
425 failf(data, "Failed to send GSS-API encryption type.");
426 gss_delete_sec_context(&gss_status, &gss_context, NULL);
427 return CURLE_COULDNT_CONNECT;
428 }
429 }
430 else {
431 code = Curl_write_plain(data, sock, (char *)gss_w_token.value,
432 gss_w_token.length, &written);
433 if(code || ((ssize_t)gss_w_token.length != written)) {
434 failf(data, "Failed to send GSS-API encryption type.");
435 gss_release_buffer(&gss_status, &gss_w_token);
436 gss_delete_sec_context(&gss_status, &gss_context, NULL);
437 return CURLE_COULDNT_CONNECT;
438 }
439 gss_release_buffer(&gss_status, &gss_w_token);
440 }
441
442 result = Curl_blockread_all(data, sock, (char *)socksreq, 4, &actualread);
443 if(result || (actualread != 4)) {
444 failf(data, "Failed to receive GSS-API encryption response.");
445 gss_delete_sec_context(&gss_status, &gss_context, NULL);
446 return CURLE_COULDNT_CONNECT;
447 }
448
449 /* ignore the first (VER) byte */
450 if(socksreq[1] == 255) { /* status / message type */
451 failf(data, "User was rejected by the SOCKS5 server (%d %d).",
452 socksreq[0], socksreq[1]);
453 gss_delete_sec_context(&gss_status, &gss_context, NULL);
454 return CURLE_COULDNT_CONNECT;
455 }
456
457 if(socksreq[1] != 2) { /* status / message type */
458 failf(data, "Invalid GSS-API encryption response type (%d %d).",
459 socksreq[0], socksreq[1]);
460 gss_delete_sec_context(&gss_status, &gss_context, NULL);
461 return CURLE_COULDNT_CONNECT;
462 }
463
464 memcpy(&us_length, socksreq + 2, sizeof(short));
465 us_length = ntohs(us_length);
466
467 gss_recv_token.length = us_length;
468 gss_recv_token.value = malloc(gss_recv_token.length);
469 if(!gss_recv_token.value) {
470 gss_delete_sec_context(&gss_status, &gss_context, NULL);
471 return CURLE_OUT_OF_MEMORY;
472 }
473 result = Curl_blockread_all(data, sock, (char *)gss_recv_token.value,
474 gss_recv_token.length, &actualread);
475
476 if(result || (actualread != us_length)) {
477 failf(data, "Failed to receive GSS-API encryptrion type.");
478 gss_release_buffer(&gss_status, &gss_recv_token);
479 gss_delete_sec_context(&gss_status, &gss_context, NULL);
480 return CURLE_COULDNT_CONNECT;
481 }
482
483 if(!data->set.socks5_gssapi_nec) {
484 gss_major_status = gss_unwrap(&gss_minor_status, gss_context,
485 &gss_recv_token, &gss_w_token,
486 0, GSS_C_QOP_DEFAULT);
487
488 if(check_gss_err(data, gss_major_status, gss_minor_status, "gss_unwrap")) {
489 gss_release_buffer(&gss_status, &gss_recv_token);
490 gss_release_buffer(&gss_status, &gss_w_token);
491 gss_delete_sec_context(&gss_status, &gss_context, NULL);
492 failf(data, "Failed to unwrap GSS-API encryption value into token.");
493 return CURLE_COULDNT_CONNECT;
494 }
495 gss_release_buffer(&gss_status, &gss_recv_token);
496
497 if(gss_w_token.length != 1) {
498 failf(data, "Invalid GSS-API encryption response length (%zu).",
499 gss_w_token.length);
500 gss_release_buffer(&gss_status, &gss_w_token);
501 gss_delete_sec_context(&gss_status, &gss_context, NULL);
502 return CURLE_COULDNT_CONNECT;
503 }
504
505 memcpy(socksreq, gss_w_token.value, gss_w_token.length);
506 gss_release_buffer(&gss_status, &gss_w_token);
507 }
508 else {
509 if(gss_recv_token.length != 1) {
510 failf(data, "Invalid GSS-API encryption response length (%zu).",
511 gss_recv_token.length);
512 gss_release_buffer(&gss_status, &gss_recv_token);
513 gss_delete_sec_context(&gss_status, &gss_context, NULL);
514 return CURLE_COULDNT_CONNECT;
515 }
516
517 memcpy(socksreq, gss_recv_token.value, gss_recv_token.length);
518 gss_release_buffer(&gss_status, &gss_recv_token);
519 }
520
521 (void)curlx_nonblock(sock, TRUE);
522
523 infof(data, "SOCKS5 access with%s protection granted.",
524 (socksreq[0] == 0)?"out GSS-API data":
525 ((socksreq[0] == 1)?" GSS-API integrity":" GSS-API confidentiality"));
526
527 conn->socks5_gssapi_enctype = socksreq[0];
528 if(socksreq[0] == 0)
529 gss_delete_sec_context(&gss_status, &gss_context, NULL);
530
531 return CURLE_OK;
532}
533
534#endif /* HAVE_GSSAPI && !CURL_DISABLE_PROXY */
535