summaryrefslogtreecommitdiffstats
path: root/source3/client/cifs.spnego.c
blob: caa22276c47b46eb30c1857977207f37ec3b00f0 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
/*
* CIFS SPNEGO user-space helper.
* Copyright (C) Igor Mammedov (niallain@gmail.com) 2007
*
* Used by /sbin/request-key for handling
* cifs upcall for kerberos authorization of access to share.
* You should have keyutils installed and add following line to
* /etc/request-key.conf file

create cifs.spnego * * /usr/local/sbin/cifs.spnego [-v][-c] %k

* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/

#include "includes.h"
#include <keyutils.h>

#include "cifs_spnego.h"

const char* CIFSSPNEGO_VERSION="1.0";
static const char *prog = "cifs.spnego";
typedef enum _secType {
	KRB5,
	MS_KRB5
} secType_t;

/*
 * Prepares AP-REQ data for mechToken and gets session key
 * Uses credentials from cache. It will not ask for password
 * you should receive credentials for yuor name manually using
 * kinit or whatever you wish.
 *
 * in:
 * 	oid -		string with OID/ Could be OID_KERBEROS5
 * 			or OID_KERBEROS5_OLD
 * 	principal -	Service name.
 * 			Could be "cifs/FQDN" for KRB5 OID
 * 			or for MS_KRB5 OID style server principal
 * 			like "pdc$@YOUR.REALM.NAME"
 *
 * out:
 * 	secblob -	pointer for spnego wrapped AP-REQ data to be stored
 * 	sess_key-	pointer for SessionKey data to be stored
 *
 * ret: 0 - success, others - failure
*/
int handle_krb5_mech(const char *oid, const char *principal,
		     DATA_BLOB * secblob, DATA_BLOB * sess_key)
{
	int retval;
	DATA_BLOB tkt, tkt_wrapped;

	/* get a kerberos ticket for the service and extract the session key */
	retval = cli_krb5_get_ticket(principal, 0,
				     &tkt, sess_key, 0, NULL, NULL);

	if (retval)
		return retval;

	/* wrap that up in a nice GSS-API wrapping */
	tkt_wrapped = spnego_gen_krb5_wrap(tkt, TOK_ID_KRB_AP_REQ);

	/* and wrap that in a shiny SPNEGO wrapper */
	*secblob = gen_negTokenInit(OID_KERBEROS5, tkt_wrapped);

	data_blob_free(&tkt_wrapped);
	data_blob_free(&tkt);
	return retval;
}

#define DKD_HAVE_HOSTNAME	1
#define DKD_HAVE_VERSION	2
#define DKD_HAVE_SEC		4
#define DKD_HAVE_IPV4		8
#define DKD_HAVE_IPV6		16
#define DKD_HAVE_UID		32
#define DKD_MUSTHAVE_SET (DKD_HAVE_HOSTNAME|DKD_HAVE_VERSION|DKD_HAVE_SEC)

int decode_key_description(const char *desc, int *ver, secType_t * sec,
			   char **hostname, uid_t * uid)
{
	int retval = 0;
	char *pos;
	const char *tkn = desc;

	do {
		pos = index(tkn, ';');
		if (strncmp(tkn, "host=", 5) == 0) {
			int len;

			if (pos == NULL) {
				len = strlen(tkn);
			} else {
				len = pos - tkn;
			}
			len -= 4;
			SAFE_FREE(*hostname);
			*hostname = SMB_XMALLOC_ARRAY(char, len);
			strlcpy(*hostname, tkn + 5, len);
			retval |= DKD_HAVE_HOSTNAME;
		} else if (strncmp(tkn, "ipv4=", 5) == 0) {
			/* BB: do we need it if we have hostname already? */
		} else if (strncmp(tkn, "ipv6=", 5) == 0) {
			/* BB: do we need it if we have hostname already? */
		} else if (strncmp(tkn, "sec=", 4) == 0) {
			if (strncmp(tkn + 4, "krb5", 4) == 0) {
				retval |= DKD_HAVE_SEC;
				*sec = KRB5;
			}
		} else if (strncmp(tkn, "uid=", 4) == 0) {
			errno = 0;
			*uid = strtol(tkn + 4, NULL, 16);
			if (errno != 0) {
				syslog(LOG_WARNING, "Invalid uid format: %s",
				       strerror(errno));
				return 1;
			} else {
				retval |= DKD_HAVE_UID;
			}
		} else if (strncmp(tkn, "ver=", 4) == 0) {	/* if version */
			errno = 0;
			*ver = strtol(tkn + 4, NULL, 16);
			if (errno != 0) {
				syslog(LOG_WARNING,
				       "Invalid version format: %s",
				       strerror(errno));
				return 1;
			} else {
				retval |= DKD_HAVE_VERSION;
			}
		}
		if (pos == NULL)
			break;
		tkn = pos + 1;
	} while (tkn);
	return retval;
}

int main(const int argc, char *const argv[])
{
	struct cifs_spnego_msg *keydata = NULL;
	DATA_BLOB secblob = data_blob_null;
	DATA_BLOB sess_key = data_blob_null;
	secType_t sectype;
	key_serial_t key;
	size_t datalen;
	long rc = 1;
	uid_t uid;
	int kernel_upcall_version;
	int c, use_cifs_service_prefix = 0;
	char *buf, *hostname = NULL;

	openlog(prog, 0, LOG_DAEMON);
	if (argc < 1) {
		syslog(LOG_WARNING, "Usage: %s [-c] key_serial", prog);
		goto out;
	}

	while ((c = getopt(argc, argv, "cv")) != -1) {
		switch (c) {
		case 'c':{
			use_cifs_service_prefix = 1;
			break;
			}
		case 'v':{
			syslog(LOG_WARNING, "version: %s", CIFSSPNEGO_VERSION);
			fprintf(stderr, "version: %s", CIFSSPNEGO_VERSION);
			break;
			}
		default:{
			syslog(LOG_WARNING, "unknow option: %c", c);
			goto out;
			}
		}
	}
	/* get key and keyring values */
	errno = 0;
	key = strtol(argv[optind], NULL, 10);
	if (errno != 0) {
		syslog(LOG_WARNING, "Invalid key format: %s", strerror(errno));
		goto out;
	}

	rc = keyctl_describe_alloc(key, &buf);
	if (rc == -1) {
		syslog(LOG_WARNING, "keyctl_describe_alloc failed: %s",
		       strerror(errno));
		rc = 1;
		goto out;
	}

	rc = decode_key_description(buf, &kernel_upcall_version, &sectype,
				    &hostname, &uid);
	if ((rc & DKD_MUSTHAVE_SET) != DKD_MUSTHAVE_SET) {
		syslog(LOG_WARNING,
		       "unable to get from description necessary params");
		rc = 1;
		SAFE_FREE(buf);
		goto out;
	}
	SAFE_FREE(buf);

	if (kernel_upcall_version != CIFS_SPNEGO_UPCALL_VERSION) {
		syslog(LOG_WARNING,
		       "incompatible kernel upcall version: 0x%x",
		       kernel_upcall_version);
		rc = 1;
		goto out;
	}

	if (rc & DKD_HAVE_UID) {
		rc = setuid(uid);
		if (rc == -1) {
			syslog(LOG_WARNING, "setuid: %s", strerror(errno));
			goto out;
		}
	}

	/* BB: someday upcall SPNEGO blob could be checked here to decide
	 * what mech to use */

	// do mech specific authorization
	switch (sectype) {
	case KRB5:{
			char *princ;
			size_t len;

			/* for "cifs/" service name + terminating 0 */
			len = strlen(hostname) + 5 + 1;
			princ = SMB_XMALLOC_ARRAY(char, len);
			if (!princ) {
				rc = 1;
				break;
			}
			if (use_cifs_service_prefix) {
				strlcpy(princ, "cifs/", len);
			} else {
				strlcpy(princ, "host/", len);
			}
			strlcpy(princ + 5, hostname, len - 5);

			rc = handle_krb5_mech(OID_KERBEROS5, princ,
					      &secblob, &sess_key);
			SAFE_FREE(princ);
			break;
		}
	default:{
			syslog(LOG_WARNING, "sectype: %d is not implemented",
			       sectype);
			rc = 1;
			break;
		}
	}

	if (rc) {
		goto out;
	}

	/* pack SecurityBLob and SessionKey into downcall packet */
	datalen =
	    sizeof(struct cifs_spnego_msg) + secblob.length + sess_key.length;
	keydata = (struct cifs_spnego_msg*)SMB_XMALLOC_ARRAY(char, datalen);
	if (!keydata) {
		rc = 1;
		goto out;
	}
	keydata->version = CIFS_SPNEGO_UPCALL_VERSION;
	keydata->flags = 0;
	keydata->sesskey_len = sess_key.length;
	keydata->secblob_len = secblob.length;
	memcpy(&(keydata->data), sess_key.data, sess_key.length);
	memcpy(&(keydata->data) + keydata->sesskey_len,
	       secblob.data, secblob.length);

	/* setup key */
	rc = keyctl_instantiate(key, keydata, datalen, 0);
	if (rc == -1) {
		syslog(LOG_WARNING, "keyctl_instantiate: %s", strerror(errno));
		goto out;
	}

	/* BB: maybe we need use timeout for key: for example no more then
	 * ticket lifietime? */
	/* keyctl_set_timeout( key, 60); */
      out:
	data_blob_free(&secblob);
	data_blob_free(&sess_key);
	SAFE_FREE(hostname);
	SAFE_FREE(keydata);
	return rc;
}