keys.c revision 178825 
1/*
2 * Copyright (c) 1997 - 2001, 2003 - 2004 Kungliga Tekniska H�gskolan
3 * (Royal Institute of Technology, Stockholm, Sweden).
4 * All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 *
10 * 1. Redistributions of source code must retain the above copyright
11 *    notice, this list of conditions and the following disclaimer.
12 *
13 * 2. Redistributions in binary form must reproduce the above copyright
14 *    notice, this list of conditions and the following disclaimer in the
15 *    documentation and/or other materials provided with the distribution.
16 *
17 * 3. Neither the name of the Institute nor the names of its contributors
18 *    may be used to endorse or promote products derived from this software
19 *    without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
32 */
33
34#include "hdb_locl.h"
35
36RCSID("$Id: keys.c 22071 2007-11-14 20:04:50Z lha $");
37
38/*
39 * free all the memory used by (len, keys)
40 */
41
42void
43hdb_free_keys (krb5_context context, int len, Key *keys)
44{
45    int i;
46
47    for (i = 0; i < len; i++) {
48	free(keys[i].mkvno);
49	keys[i].mkvno = NULL;
50	if (keys[i].salt != NULL) {
51	    free_Salt(keys[i].salt);
52	    free(keys[i].salt);
53	    keys[i].salt = NULL;
54	}
55	krb5_free_keyblock_contents(context, &keys[i].key);
56    }
57    free (keys);
58}
59
60/*
61 * for each entry in `default_keys' try to parse it as a sequence
62 * of etype:salttype:salt, syntax of this if something like:
63 * [(des|des3|etype):](pw-salt|afs3)[:string], if etype is omitted it
64 *      means all etypes, and if string is omitted is means the default
65 * string (for that principal). Additional special values:
66 *	v5 == pw-salt, and
67 *	v4 == des:pw-salt:
68 *	afs or afs3 == des:afs3-salt
69 */
70
71/* the 3 DES types must be first */
72static const krb5_enctype all_etypes[] = {
73    ETYPE_DES_CBC_MD5,
74    ETYPE_DES_CBC_MD4,
75    ETYPE_DES_CBC_CRC,
76    ETYPE_AES256_CTS_HMAC_SHA1_96,
77    ETYPE_ARCFOUR_HMAC_MD5,
78    ETYPE_DES3_CBC_SHA1
79};
80
81static krb5_error_code
82parse_key_set(krb5_context context, const char *key,
83	      krb5_enctype **ret_enctypes, size_t *ret_num_enctypes,
84	      krb5_salt *salt, krb5_principal principal)
85{
86    const char *p;
87    char buf[3][256];
88    int num_buf = 0;
89    int i, num_enctypes = 0;
90    krb5_enctype e;
91    const krb5_enctype *enctypes = NULL;
92    krb5_error_code ret;
93
94    p = key;
95
96    *ret_enctypes = NULL;
97    *ret_num_enctypes = 0;
98
99    /* split p in a list of :-separated strings */
100    for(num_buf = 0; num_buf < 3; num_buf++)
101	if(strsep_copy(&p, ":", buf[num_buf], sizeof(buf[num_buf])) == -1)
102	    break;
103
104    salt->saltvalue.data = NULL;
105    salt->saltvalue.length = 0;
106
107    for(i = 0; i < num_buf; i++) {
108	if(enctypes == NULL && num_buf > 1) {
109	    /* this might be a etype specifier */
110	    /* XXX there should be a string_to_etypes handling
111	       special cases like `des' and `all' */
112	    if(strcmp(buf[i], "des") == 0) {
113		enctypes = all_etypes;
114		num_enctypes = 3;
115	    } else if(strcmp(buf[i], "des3") == 0) {
116		e = ETYPE_DES3_CBC_SHA1;
117		enctypes = &e;
118		num_enctypes = 1;
119	    } else {
120		ret = krb5_string_to_enctype(context, buf[i], &e);
121		if (ret == 0) {
122		    enctypes = &e;
123		    num_enctypes = 1;
124		} else
125		    return ret;
126	    }
127	    continue;
128	}
129	if(salt->salttype == 0) {
130	    /* interpret string as a salt specifier, if no etype
131	       is set, this sets default values */
132	    /* XXX should perhaps use string_to_salttype, but that
133	       interface sucks */
134	    if(strcmp(buf[i], "pw-salt") == 0) {
135		if(enctypes == NULL) {
136		    enctypes = all_etypes;
137		    num_enctypes = sizeof(all_etypes)/sizeof(all_etypes[0]);
138		}
139		salt->salttype = KRB5_PW_SALT;
140	    } else if(strcmp(buf[i], "afs3-salt") == 0) {
141		if(enctypes == NULL) {
142		    enctypes = all_etypes;
143		    num_enctypes = 3;
144		}
145		salt->salttype = KRB5_AFS3_SALT;
146	    }
147	    continue;
148	}
149
150	{
151	    /* if there is a final string, use it as the string to
152	       salt with, this is mostly useful with null salt for
153	       v4 compat, and a cell name for afs compat */
154	    salt->saltvalue.data = strdup(buf[i]);
155	    if (salt->saltvalue.data == NULL) {
156		krb5_set_error_string(context, "out of memory");
157		return ENOMEM;
158	    }
159	    salt->saltvalue.length = strlen(buf[i]);
160	}
161    }
162
163    if(enctypes == NULL || salt->salttype == 0) {
164	krb5_set_error_string(context, "bad value for default_keys `%s'", key);
165	return EINVAL;
166    }
167
168    /* if no salt was specified make up default salt */
169    if(salt->saltvalue.data == NULL) {
170	if(salt->salttype == KRB5_PW_SALT)
171	    ret = krb5_get_pw_salt(context, principal, salt);
172	else if(salt->salttype == KRB5_AFS3_SALT) {
173	    krb5_realm *realm = krb5_princ_realm(context, principal);
174	    salt->saltvalue.data = strdup(*realm);
175	    if(salt->saltvalue.data == NULL) {
176		krb5_set_error_string(context, "out of memory while "
177				      "parsing salt specifiers");
178		return ENOMEM;
179	    }
180	    strlwr(salt->saltvalue.data);
181	    salt->saltvalue.length = strlen(*realm);
182	}
183    }
184
185    *ret_enctypes = malloc(sizeof(enctypes[0]) * num_enctypes);
186    if (*ret_enctypes == NULL) {
187	krb5_free_salt(context, *salt);
188	krb5_set_error_string(context, "out of memory");
189	return ENOMEM;
190    }
191    memcpy(*ret_enctypes, enctypes, sizeof(enctypes[0]) * num_enctypes);
192    *ret_num_enctypes = num_enctypes;
193
194    return 0;
195}
196
197static krb5_error_code
198add_enctype_to_key_set(Key **key_set, size_t *nkeyset,
199		       krb5_enctype enctype, krb5_salt *salt)
200{
201    krb5_error_code ret;
202    Key key, *tmp;
203
204    memset(&key, 0, sizeof(key));
205
206    tmp = realloc(*key_set, (*nkeyset + 1) * sizeof((*key_set)[0]));
207    if (tmp == NULL)
208	return ENOMEM;
209
210    *key_set = tmp;
211
212    key.key.keytype = enctype;
213    key.key.keyvalue.length = 0;
214    key.key.keyvalue.data = NULL;
215
216    if (salt) {
217	key.salt = malloc(sizeof(*key.salt));
218	if (key.salt == NULL) {
219	    free_Key(&key);
220	    return ENOMEM;
221	}
222
223	key.salt->type = salt->salttype;
224	krb5_data_zero (&key.salt->salt);
225
226	ret = krb5_data_copy(&key.salt->salt,
227			     salt->saltvalue.data,
228			     salt->saltvalue.length);
229	if (ret) {
230	    free_Key(&key);
231	    return ret;
232	}
233    } else
234	key.salt = NULL;
235
236    (*key_set)[*nkeyset] = key;
237
238    *nkeyset += 1;
239
240    return 0;
241}
242
243
244/*
245 * Generate the `key_set' from the [kadmin]default_keys statement. If
246 * `no_salt' is set, salt is not important (and will not be set) since
247 * it's random keys that is going to be created.
248 */
249
250krb5_error_code
251hdb_generate_key_set(krb5_context context, krb5_principal principal,
252		     Key **ret_key_set, size_t *nkeyset, int no_salt)
253{
254    char **ktypes, **kp;
255    krb5_error_code ret;
256    Key *k, *key_set;
257    int i, j;
258    char *default_keytypes[] = {
259	"des:pw-salt",
260	"aes256-cts-hmac-sha1-96:pw-salt",
261	"des3-cbc-sha1:pw-salt",
262	"arcfour-hmac-md5:pw-salt",
263	NULL
264    };
265
266    ktypes = krb5_config_get_strings(context, NULL, "kadmin",
267				     "default_keys", NULL);
268    if (ktypes == NULL)
269	ktypes = default_keytypes;
270
271    if (ktypes == NULL)
272	abort();
273
274    *ret_key_set = key_set = NULL;
275    *nkeyset = 0;
276
277    ret = 0;
278
279    for(kp = ktypes; kp && *kp; kp++) {
280	const char *p;
281	krb5_salt salt;
282	krb5_enctype *enctypes;
283	size_t num_enctypes;
284
285	p = *kp;
286	/* check alias */
287	if(strcmp(p, "v5") == 0)
288	    p = "pw-salt";
289	else if(strcmp(p, "v4") == 0)
290	    p = "des:pw-salt:";
291	else if(strcmp(p, "afs") == 0 || strcmp(p, "afs3") == 0)
292	    p = "des:afs3-salt";
293	else if (strcmp(p, "arcfour-hmac-md5") == 0)
294	    p = "arcfour-hmac-md5:pw-salt";
295
296	memset(&salt, 0, sizeof(salt));
297
298	ret = parse_key_set(context, p,
299			    &enctypes, &num_enctypes, &salt, principal);
300	if (ret) {
301	    krb5_warn(context, ret, "bad value for default_keys `%s'", *kp);
302	    ret = 0;
303	    continue;
304	}
305
306	for (i = 0; i < num_enctypes; i++) {
307	    /* find duplicates */
308	    for (j = 0; j < *nkeyset; j++) {
309
310		k = &key_set[j];
311
312		if (k->key.keytype == enctypes[i]) {
313		    if (no_salt)
314			break;
315		    if (k->salt == NULL && salt.salttype == KRB5_PW_SALT)
316			break;
317		    if (k->salt->type == salt.salttype &&
318			k->salt->salt.length == salt.saltvalue.length &&
319			memcmp(k->salt->salt.data, salt.saltvalue.data,
320			       salt.saltvalue.length) == 0)
321			break;
322		}
323	    }
324	    /* not a duplicate, lets add it */
325	    if (j == *nkeyset) {
326		ret = add_enctype_to_key_set(&key_set, nkeyset, enctypes[i],
327					     no_salt ? NULL : &salt);
328		if (ret) {
329		    free(enctypes);
330		    krb5_free_salt(context, salt);
331		    goto out;
332		}
333	    }
334	}
335	free(enctypes);
336	krb5_free_salt(context, salt);
337    }
338
339    *ret_key_set = key_set;
340
341 out:
342    if (ktypes != default_keytypes)
343	krb5_config_free_strings(ktypes);
344
345    if (ret) {
346	krb5_warn(context, ret,
347		  "failed to parse the [kadmin]default_keys values");
348
349	for (i = 0; i < *nkeyset; i++)
350	    free_Key(&key_set[i]);
351	free(key_set);
352    } else if (*nkeyset == 0) {
353	krb5_warnx(context,
354		   "failed to parse any of the [kadmin]default_keys values");
355	ret = EINVAL; /* XXX */
356    }
357
358    return ret;
359}
360
361
362krb5_error_code
363hdb_generate_key_set_password(krb5_context context,
364			      krb5_principal principal,
365			      const char *password,
366			      Key **keys, size_t *num_keys)
367{
368    krb5_error_code ret;
369    int i;
370
371    ret = hdb_generate_key_set(context, principal,
372				keys, num_keys, 0);
373    if (ret)
374	return ret;
375
376    for (i = 0; i < (*num_keys); i++) {
377	krb5_salt salt;
378
379	salt.salttype = (*keys)[i].salt->type;
380	salt.saltvalue.length = (*keys)[i].salt->salt.length;
381	salt.saltvalue.data = (*keys)[i].salt->salt.data;
382
383	ret = krb5_string_to_key_salt (context,
384				       (*keys)[i].key.keytype,
385				       password,
386				       salt,
387				       &(*keys)[i].key);
388
389	if(ret)
390	    break;
391    }
392
393    if(ret) {
394	hdb_free_keys (context, *num_keys, *keys);
395	return ret;
396    }
397    return ret;
398}
399