source: branches/samba-3.2.x/source/client/cifs.upcall.c@ 621

Last change on this file since 621 was 204, checked in by Herwig Bauernfeind, 16 years ago

Update 3.2 branch to 3.2.4
File size: 10.0 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 = "1.2";
33static const char *prog = "cifs.upcall";
34typedef enum _secType {
35 NONE = 0,
36 KRB5,
37 MS_KRB5
38} secType_t;
39
40/*
41 * Prepares AP-REQ data for mechToken and gets session key
42 * Uses credentials from cache. It will not ask for password
43 * you should receive credentials for yuor name manually using
44 * kinit or whatever you wish.
45 *
46 * in:
47 * oid - string with OID/ Could be OID_KERBEROS5
48 * or OID_KERBEROS5_OLD
49 * principal - Service name.
50 * Could be "cifs/FQDN" for KRB5 OID
51 * or for MS_KRB5 OID style server principal
52 * like "pdc$@YOUR.REALM.NAME"
53 *
54 * out:
55 * secblob - pointer for spnego wrapped AP-REQ data to be stored
56 * sess_key- pointer for SessionKey data to be stored
57 *
58 * ret: 0 - success, others - failure
59*/
60static int
61handle_krb5_mech(const char *oid, const char *principal,
62 DATA_BLOB * secblob, DATA_BLOB * sess_key)
63{
64 int retval;
65 DATA_BLOB tkt, tkt_wrapped;
66
67 /* get a kerberos ticket for the service and extract the session key */
68 retval = cli_krb5_get_ticket(principal, 0,
69 &tkt, sess_key, 0, NULL, NULL);
70
71 if (retval)
72 return retval;
73
74 /* wrap that up in a nice GSS-API wrapping */
75 tkt_wrapped = spnego_gen_krb5_wrap(tkt, TOK_ID_KRB_AP_REQ);
76
77 /* and wrap that in a shiny SPNEGO wrapper */
78 *secblob = gen_negTokenInit(oid, tkt_wrapped);
79
80 data_blob_free(&tkt_wrapped);
81 data_blob_free(&tkt);
82 return retval;
83}
84
85#define DKD_HAVE_HOSTNAME 1
86#define DKD_HAVE_VERSION 2
87#define DKD_HAVE_SEC 4
88#define DKD_HAVE_IPV4 8
89#define DKD_HAVE_IPV6 16
90#define DKD_HAVE_UID 32
91#define DKD_MUSTHAVE_SET (DKD_HAVE_HOSTNAME|DKD_HAVE_VERSION|DKD_HAVE_SEC)
92
93static int
94decode_key_description(const char *desc, int *ver, secType_t * sec,
95 char **hostname, uid_t * uid)
96{
97 int retval = 0;
98 char *pos;
99 const char *tkn = desc;
100
101 do {
102 pos = index(tkn, ';');
103 if (strncmp(tkn, "host=", 5) == 0) {
104 int len;
105
106 if (pos == NULL) {
107 len = strlen(tkn);
108 } else {
109 len = pos - tkn;
110 }
111 len -= 4;
112 SAFE_FREE(*hostname);
113 *hostname = SMB_XMALLOC_ARRAY(char, len);
114 strlcpy(*hostname, tkn + 5, len);
115 retval |= DKD_HAVE_HOSTNAME;
116 } else if (strncmp(tkn, "ipv4=", 5) == 0) {
117 /* BB: do we need it if we have hostname already? */
118 } else if (strncmp(tkn, "ipv6=", 5) == 0) {
119 /* BB: do we need it if we have hostname already? */
120 } else if (strncmp(tkn, "sec=", 4) == 0) {
121 if (strncmp(tkn + 4, "krb5", 4) == 0) {
122 retval |= DKD_HAVE_SEC;
123 *sec = KRB5;
124 } else if (strncmp(tkn + 4, "mskrb5", 6) == 0) {
125 retval |= DKD_HAVE_SEC;
126 *sec = MS_KRB5;
127 }
128 } else if (strncmp(tkn, "uid=", 4) == 0) {
129 errno = 0;
130 *uid = strtol(tkn + 4, NULL, 16);
131 if (errno != 0) {
132 syslog(LOG_WARNING, "Invalid uid format: %s",
133 strerror(errno));
134 return 1;
135 } else {
136 retval |= DKD_HAVE_UID;
137 }
138 } else if (strncmp(tkn, "ver=", 4) == 0) { /* if version */
139 errno = 0;
140 *ver = strtol(tkn + 4, NULL, 16);
141 if (errno != 0) {
142 syslog(LOG_WARNING,
143 "Invalid version format: %s",
144 strerror(errno));
145 return 1;
146 } else {
147 retval |= DKD_HAVE_VERSION;
148 }
149 }
150 if (pos == NULL)
151 break;
152 tkn = pos + 1;
153 } while (tkn);
154 return retval;
155}
156
157static int
158cifs_resolver(const key_serial_t key, const char *key_descr)
159{
160 int c;
161 struct addrinfo *addr;
162 char ip[INET6_ADDRSTRLEN];
163 void *p;
164 const char *keyend = key_descr;
165 /* skip next 4 ';' delimiters to get to description */
166 for (c = 1; c <= 4; c++) {
167 keyend = index(keyend+1, ';');
168 if (!keyend) {
169 syslog(LOG_WARNING, "invalid key description: %s",
170 key_descr);
171 return 1;
172 }
173 }
174 keyend++;
175
176 /* resolve name to ip */
177 c = getaddrinfo(keyend, NULL, NULL, &addr);
178 if (c) {
179 syslog(LOG_WARNING, "unable to resolve hostname: %s [%s]",
180 keyend, gai_strerror(c));
181 return 1;
182 }
183
184 /* conver ip to string form */
185 if (addr->ai_family == AF_INET) {
186 p = &(((struct sockaddr_in *)addr->ai_addr)->sin_addr);
187 } else {
188 p = &(((struct sockaddr_in6 *)addr->ai_addr)->sin6_addr);
189 }
190 if (!inet_ntop(addr->ai_family, p, ip, sizeof(ip))) {
191 syslog(LOG_WARNING, "%s: inet_ntop: %s",
192 __FUNCTION__, strerror(errno));
193 freeaddrinfo(addr);
194 return 1;
195 }
196
197 /* setup key */
198 c = keyctl_instantiate(key, ip, strlen(ip)+1, 0);
199 if (c == -1) {
200 syslog(LOG_WARNING, "%s: keyctl_instantiate: %s",
201 __FUNCTION__, strerror(errno));
202 freeaddrinfo(addr);
203 return 1;
204 }
205
206 freeaddrinfo(addr);
207 return 0;
208}
209
210static void
211usage(void)
212{
213 syslog(LOG_WARNING, "Usage: %s [-c] [-v] key_serial", prog);
214 fprintf(stderr, "Usage: %s [-c] [-v] key_serial\n", prog);
215}
216
217int main(const int argc, char *const argv[])
218{
219 struct cifs_spnego_msg *keydata = NULL;
220 DATA_BLOB secblob = data_blob_null;
221 DATA_BLOB sess_key = data_blob_null;
222 secType_t sectype = NONE;
223 key_serial_t key = 0;
224 size_t datalen;
225 long rc = 1;
226 uid_t uid = 0;
227 int kernel_upcall_version = 0;
228 int c, use_cifs_service_prefix = 0;
229 char *buf, *hostname = NULL;
230 const char *oid;
231
232 openlog(prog, 0, LOG_DAEMON);
233
234 while ((c = getopt(argc, argv, "cv")) != -1) {
235 switch (c) {
236 case 'c':{
237 use_cifs_service_prefix = 1;
238 break;
239 }
240 case 'v':{
241 printf("version: %s\n", CIFSSPNEGO_VERSION);
242 goto out;
243 }
244 default:{
245 syslog(LOG_WARNING, "unknown option: %c", c);
246 goto out;
247 }
248 }
249 }
250
251 /* is there a key? */
252 if (argc <= optind) {
253 usage();
254 goto out;
255 }
256
257 /* get key and keyring values */
258 errno = 0;
259 key = strtol(argv[optind], NULL, 10);
260 if (errno != 0) {
261 key = 0;
262 syslog(LOG_WARNING, "Invalid key format: %s", strerror(errno));
263 goto out;
264 }
265
266 rc = keyctl_describe_alloc(key, &buf);
267 if (rc == -1) {
268 syslog(LOG_WARNING, "keyctl_describe_alloc failed: %s",
269 strerror(errno));
270 rc = 1;
271 goto out;
272 }
273
274 if ((strncmp(buf, "cifs.resolver", sizeof("cifs.resolver")-1) == 0) ||
275 (strncmp(buf, "dns_resolver", sizeof("dns_resolver")-1) == 0)) {
276 rc = cifs_resolver(key, buf);
277 goto out;
278 }
279
280 rc = decode_key_description(buf, &kernel_upcall_version, &sectype,
281 &hostname, &uid);
282 if ((rc & DKD_MUSTHAVE_SET) != DKD_MUSTHAVE_SET) {
283 syslog(LOG_WARNING,
284 "unable to get from description necessary params");
285 rc = 1;
286 SAFE_FREE(buf);
287 goto out;
288 }
289 SAFE_FREE(buf);
290
291 if (kernel_upcall_version > CIFS_SPNEGO_UPCALL_VERSION) {
292 syslog(LOG_WARNING,
293 "incompatible kernel upcall version: 0x%x",
294 kernel_upcall_version);
295 rc = 1;
296 goto out;
297 }
298
299 if (rc & DKD_HAVE_UID) {
300 rc = setuid(uid);
301 if (rc == -1) {
302 syslog(LOG_WARNING, "setuid: %s", strerror(errno));
303 goto out;
304 }
305 }
306
307 /* BB: someday upcall SPNEGO blob could be checked here to decide
308 * what mech to use */
309
310 // do mech specific authorization
311 switch (sectype) {
312 case MS_KRB5:
313 case KRB5:{
314 char *princ;
315 size_t len;
316
317 /* for "cifs/" service name + terminating 0 */
318 len = strlen(hostname) + 5 + 1;
319 princ = SMB_XMALLOC_ARRAY(char, len);
320 if (!princ) {
321 rc = 1;
322 break;
323 }
324 if (use_cifs_service_prefix) {
325 strlcpy(princ, "cifs/", len);
326 } else {
327 strlcpy(princ, "host/", len);
328 }
329 strlcpy(princ + 5, hostname, len - 5);
330
331 if (sectype == MS_KRB5)
332 oid = OID_KERBEROS5_OLD;
333 else
334 oid = OID_KERBEROS5;
335
336 rc = handle_krb5_mech(oid, princ, &secblob, &sess_key);
337 SAFE_FREE(princ);
338 break;
339 }
340 default:{
341 syslog(LOG_WARNING, "sectype: %d is not implemented",
342 sectype);
343 rc = 1;
344 break;
345 }
346 }
347
348 if (rc) {
349 goto out;
350 }
351
352 /* pack SecurityBLob and SessionKey into downcall packet */
353 datalen =
354 sizeof(struct cifs_spnego_msg) + secblob.length + sess_key.length;
355 keydata = (struct cifs_spnego_msg*)SMB_XMALLOC_ARRAY(char, datalen);
356 if (!keydata) {
357 rc = 1;
358 goto out;
359 }
360 keydata->version = kernel_upcall_version;
361 keydata->flags = 0;
362 keydata->sesskey_len = sess_key.length;
363 keydata->secblob_len = secblob.length;
364 memcpy(&(keydata->data), sess_key.data, sess_key.length);
365 memcpy(&(keydata->data) + keydata->sesskey_len,
366 secblob.data, secblob.length);
367
368 /* setup key */
369 rc = keyctl_instantiate(key, keydata, datalen, 0);
370 if (rc == -1) {
371 syslog(LOG_WARNING, "keyctl_instantiate: %s", strerror(errno));
372 goto out;
373 }
374
375 /* BB: maybe we need use timeout for key: for example no more then
376 * ticket lifietime? */
377 /* keyctl_set_timeout( key, 60); */
378out:
379 /*
380 * on error, negatively instantiate the key ourselves so that we can
381 * make sure the kernel doesn't hang it off of a searchable keyring
382 * and interfere with the next attempt to instantiate the key.
383 */
384 if (rc != 0 && key == 0)
385 keyctl_negate(key, 1, KEY_REQKEY_DEFL_DEFAULT);
386 data_blob_free(&secblob);
387 data_blob_free(&sess_key);
388 SAFE_FREE(hostname);
389 SAFE_FREE(keydata);
390 return rc;
391}
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