source: branches/samba-3.2.x/source/client/cifs.upcall.c@ 203

Last change on this file since 203 was 203, checked in by Herwig Bauernfeind, 16 years ago

Missing 3.2.2 client and HOWTO files
File size: 9.4 KB
Line 
1/*
2* CIFS user-space helper.
3* Copyright (C) Igor Mammedov (niallain@gmail.com) 2007
4*
5* Used by /sbin/request-key for handling
6* cifs upcall for kerberos authorization of access to share and
7* cifs upcall for DFS srver name resolving (IPv4/IPv6 aware).
8* You should have keyutils installed and add something like the
9* following lines to /etc/request-key.conf file:
10
11create cifs.spnego * * /usr/local/sbin/cifs.upcall %k
12create dns_resolver * * /usr/local/sbin/cifs.upcall %k
13
14* This program is free software; you can redistribute it and/or modify
15* it under the terms of the GNU General Public License as published by
16* the Free Software Foundation; either version 2 of the License, or
17* (at your option) any later version.
18* This program is distributed in the hope that it will be useful,
19* but WITHOUT ANY WARRANTY; without even the implied warranty of
20* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
21* GNU General Public License for more details.
22* You should have received a copy of the GNU General Public License
23* along with this program; if not, write to the Free Software
24* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
25*/
26
27#include "includes.h"
28#include <keyutils.h>
29
30#include "cifs_spnego.h"
31
32const char *CIFSSPNEGO_VERSION = "1.1";
33static const char *prog = "cifs.upcall";
34typedef enum _secType {
35 KRB5,
36 MS_KRB5
37} secType_t;
38
39/*
40 * Prepares AP-REQ data for mechToken and gets session key
41 * Uses credentials from cache. It will not ask for password
42 * you should receive credentials for yuor name manually using
43 * kinit or whatever you wish.
44 *
45 * in:
46 * oid - string with OID/ Could be OID_KERBEROS5
47 * or OID_KERBEROS5_OLD
48 * principal - Service name.
49 * Could be "cifs/FQDN" for KRB5 OID
50 * or for MS_KRB5 OID style server principal
51 * like "pdc$@YOUR.REALM.NAME"
52 *
53 * out:
54 * secblob - pointer for spnego wrapped AP-REQ data to be stored
55 * sess_key- pointer for SessionKey data to be stored
56 *
57 * ret: 0 - success, others - failure
58*/
59int handle_krb5_mech(const char *oid, const char *principal,
60 DATA_BLOB * secblob, DATA_BLOB * sess_key)
61{
62 int retval;
63 DATA_BLOB tkt, tkt_wrapped;
64
65 /* get a kerberos ticket for the service and extract the session key */
66 retval = cli_krb5_get_ticket(principal, 0,
67 &tkt, sess_key, 0, NULL, NULL);
68
69 if (retval)
70 return retval;
71
72 /* wrap that up in a nice GSS-API wrapping */
73 tkt_wrapped = spnego_gen_krb5_wrap(tkt, TOK_ID_KRB_AP_REQ);
74
75 /* and wrap that in a shiny SPNEGO wrapper */
76 *secblob = gen_negTokenInit(OID_KERBEROS5, tkt_wrapped);
77
78 data_blob_free(&tkt_wrapped);
79 data_blob_free(&tkt);
80 return retval;
81}
82
83#define DKD_HAVE_HOSTNAME 1
84#define DKD_HAVE_VERSION 2
85#define DKD_HAVE_SEC 4
86#define DKD_HAVE_IPV4 8
87#define DKD_HAVE_IPV6 16
88#define DKD_HAVE_UID 32
89#define DKD_MUSTHAVE_SET (DKD_HAVE_HOSTNAME|DKD_HAVE_VERSION|DKD_HAVE_SEC)
90
91int decode_key_description(const char *desc, int *ver, secType_t * sec,
92 char **hostname, uid_t * uid)
93{
94 int retval = 0;
95 char *pos;
96 const char *tkn = desc;
97
98 do {
99 pos = index(tkn, ';');
100 if (strncmp(tkn, "host=", 5) == 0) {
101 int len;
102
103 if (pos == NULL) {
104 len = strlen(tkn);
105 } else {
106 len = pos - tkn;
107 }
108 len -= 4;
109 SAFE_FREE(*hostname);
110 *hostname = SMB_XMALLOC_ARRAY(char, len);
111 strlcpy(*hostname, tkn + 5, len);
112 retval |= DKD_HAVE_HOSTNAME;
113 } else if (strncmp(tkn, "ipv4=", 5) == 0) {
114 /* BB: do we need it if we have hostname already? */
115 } else if (strncmp(tkn, "ipv6=", 5) == 0) {
116 /* BB: do we need it if we have hostname already? */
117 } else if (strncmp(tkn, "sec=", 4) == 0) {
118 if (strncmp(tkn + 4, "krb5", 4) == 0) {
119 retval |= DKD_HAVE_SEC;
120 *sec = KRB5;
121 }
122 } else if (strncmp(tkn, "uid=", 4) == 0) {
123 errno = 0;
124 *uid = strtol(tkn + 4, NULL, 16);
125 if (errno != 0) {
126 syslog(LOG_WARNING, "Invalid uid format: %s",
127 strerror(errno));
128 return 1;
129 } else {
130 retval |= DKD_HAVE_UID;
131 }
132 } else if (strncmp(tkn, "ver=", 4) == 0) { /* if version */
133 errno = 0;
134 *ver = strtol(tkn + 4, NULL, 16);
135 if (errno != 0) {
136 syslog(LOG_WARNING,
137 "Invalid version format: %s",
138 strerror(errno));
139 return 1;
140 } else {
141 retval |= DKD_HAVE_VERSION;
142 }
143 }
144 if (pos == NULL)
145 break;
146 tkn = pos + 1;
147 } while (tkn);
148 return retval;
149}
150
151int cifs_resolver(const key_serial_t key, const char *key_descr)
152{
153 int c;
154 struct addrinfo *addr;
155 char ip[INET6_ADDRSTRLEN];
156 void *p;
157 const char *keyend = key_descr;
158 /* skip next 4 ';' delimiters to get to description */
159 for (c = 1; c <= 4; c++) {
160 keyend = index(keyend+1, ';');
161 if (!keyend) {
162 syslog(LOG_WARNING, "invalid key description: %s",
163 key_descr);
164 return 1;
165 }
166 }
167 keyend++;
168
169 /* resolve name to ip */
170 c = getaddrinfo(keyend, NULL, NULL, &addr);
171 if (c) {
172 syslog(LOG_WARNING, "unable to resolve hostname: %s [%s]",
173 keyend, gai_strerror(c));
174 return 1;
175 }
176
177 /* conver ip to string form */
178 if (addr->ai_family == AF_INET) {
179 p = &(((struct sockaddr_in *)addr->ai_addr)->sin_addr);
180 } else {
181 p = &(((struct sockaddr_in6 *)addr->ai_addr)->sin6_addr);
182 }
183 if (!inet_ntop(addr->ai_family, p, ip, sizeof(ip))) {
184 syslog(LOG_WARNING, "%s: inet_ntop: %s",
185 __FUNCTION__, strerror(errno));
186 freeaddrinfo(addr);
187 return 1;
188 }
189
190 /* setup key */
191 c = keyctl_instantiate(key, ip, strlen(ip)+1, 0);
192 if (c == -1) {
193 syslog(LOG_WARNING, "%s: keyctl_instantiate: %s",
194 __FUNCTION__, strerror(errno));
195 freeaddrinfo(addr);
196 return 1;
197 }
198
199 freeaddrinfo(addr);
200 return 0;
201}
202
203void
204usage(void)
205{
206 syslog(LOG_WARNING, "Usage: %s [-c] [-v] key_serial", prog);
207 fprintf(stderr, "Usage: %s [-c] [-v] key_serial\n", prog);
208}
209
210int main(const int argc, char *const argv[])
211{
212 struct cifs_spnego_msg *keydata = NULL;
213 DATA_BLOB secblob = data_blob_null;
214 DATA_BLOB sess_key = data_blob_null;
215 secType_t sectype;
216 key_serial_t key = 0;
217 size_t datalen;
218 long rc = 1;
219 uid_t uid;
220 int kernel_upcall_version;
221 int c, use_cifs_service_prefix = 0;
222 char *buf, *hostname = NULL;
223
224 openlog(prog, 0, LOG_DAEMON);
225
226 while ((c = getopt(argc, argv, "cv")) != -1) {
227 switch (c) {
228 case 'c':{
229 use_cifs_service_prefix = 1;
230 break;
231 }
232 case 'v':{
233 printf("version: %s\n", CIFSSPNEGO_VERSION);
234 goto out;
235 }
236 default:{
237 syslog(LOG_WARNING, "unknown option: %c", c);
238 goto out;
239 }
240 }
241 }
242
243 /* is there a key? */
244 if (argc <= optind) {
245 usage();
246 goto out;
247 }
248
249 /* get key and keyring values */
250 errno = 0;
251 key = strtol(argv[optind], NULL, 10);
252 if (errno != 0) {
253 key = 0;
254 syslog(LOG_WARNING, "Invalid key format: %s", strerror(errno));
255 goto out;
256 }
257
258 rc = keyctl_describe_alloc(key, &buf);
259 if (rc == -1) {
260 syslog(LOG_WARNING, "keyctl_describe_alloc failed: %s",
261 strerror(errno));
262 rc = 1;
263 goto out;
264 }
265
266 if ((strncmp(buf, "cifs.resolver", sizeof("cifs.resolver")-1) == 0) ||
267 (strncmp(buf, "dns_resolver", sizeof("dns_resolver")-1) == 0)) {
268 rc = cifs_resolver(key, buf);
269 goto out;
270 }
271
272 rc = decode_key_description(buf, &kernel_upcall_version, &sectype,
273 &hostname, &uid);
274 if ((rc & DKD_MUSTHAVE_SET) != DKD_MUSTHAVE_SET) {
275 syslog(LOG_WARNING,
276 "unable to get from description necessary params");
277 rc = 1;
278 SAFE_FREE(buf);
279 goto out;
280 }
281 SAFE_FREE(buf);
282
283 if (kernel_upcall_version != CIFS_SPNEGO_UPCALL_VERSION) {
284 syslog(LOG_WARNING,
285 "incompatible kernel upcall version: 0x%x",
286 kernel_upcall_version);
287 rc = 1;
288 goto out;
289 }
290
291 if (rc & DKD_HAVE_UID) {
292 rc = setuid(uid);
293 if (rc == -1) {
294 syslog(LOG_WARNING, "setuid: %s", strerror(errno));
295 goto out;
296 }
297 }
298
299 /* BB: someday upcall SPNEGO blob could be checked here to decide
300 * what mech to use */
301
302 // do mech specific authorization
303 switch (sectype) {
304 case KRB5:{
305 char *princ;
306 size_t len;
307
308 /* for "cifs/" service name + terminating 0 */
309 len = strlen(hostname) + 5 + 1;
310 princ = SMB_XMALLOC_ARRAY(char, len);
311 if (!princ) {
312 rc = 1;
313 break;
314 }
315 if (use_cifs_service_prefix) {
316 strlcpy(princ, "cifs/", len);
317 } else {
318 strlcpy(princ, "host/", len);
319 }
320 strlcpy(princ + 5, hostname, len - 5);
321
322 rc = handle_krb5_mech(OID_KERBEROS5, princ,
323 &secblob, &sess_key);
324 SAFE_FREE(princ);
325 break;
326 }
327 default:{
328 syslog(LOG_WARNING, "sectype: %d is not implemented",
329 sectype);
330 rc = 1;
331 break;
332 }
333 }
334
335 if (rc) {
336 goto out;
337 }
338
339 /* pack SecurityBLob and SessionKey into downcall packet */
340 datalen =
341 sizeof(struct cifs_spnego_msg) + secblob.length + sess_key.length;
342 keydata = (struct cifs_spnego_msg*)SMB_XMALLOC_ARRAY(char, datalen);
343 if (!keydata) {
344 rc = 1;
345 goto out;
346 }
347 keydata->version = CIFS_SPNEGO_UPCALL_VERSION;
348 keydata->flags = 0;
349 keydata->sesskey_len = sess_key.length;
350 keydata->secblob_len = secblob.length;
351 memcpy(&(keydata->data), sess_key.data, sess_key.length);
352 memcpy(&(keydata->data) + keydata->sesskey_len,
353 secblob.data, secblob.length);
354
355 /* setup key */
356 rc = keyctl_instantiate(key, keydata, datalen, 0);
357 if (rc == -1) {
358 syslog(LOG_WARNING, "keyctl_instantiate: %s", strerror(errno));
359 goto out;
360 }
361
362 /* BB: maybe we need use timeout for key: for example no more then
363 * ticket lifietime? */
364 /* keyctl_set_timeout( key, 60); */
365out:
366 /*
367 * on error, negatively instantiate the key ourselves so that we can
368 * make sure the kernel doesn't hang it off of a searchable keyring
369 * and interfere with the next attempt to instantiate the key.
370 */
371 if (rc != 0 && key == 0)
372 keyctl_negate(key, 1, KEY_REQKEY_DEFL_DEFAULT);
373 data_blob_free(&secblob);
374 data_blob_free(&sess_key);
375 SAFE_FREE(hostname);
376 SAFE_FREE(keydata);
377 return rc;
378}
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