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e114e473 CS |
1 | /* |
2 | * Copyright (C) 2007 Casey Schaufler <casey@schaufler-ca.com> | |
3 | * | |
4 | * This program is free software; you can redistribute it and/or modify | |
5 | * it under the terms of the GNU General Public License as published by | |
6 | * the Free Software Foundation, version 2. | |
7 | * | |
8 | * Author: | |
9 | * Casey Schaufler <casey@schaufler-ca.com> | |
10 | * | |
11 | */ | |
12 | ||
13 | #include <linux/types.h> | |
5a0e3ad6 | 14 | #include <linux/slab.h> |
e114e473 CS |
15 | #include <linux/fs.h> |
16 | #include <linux/sched.h> | |
17 | #include "smack.h" | |
18 | ||
e114e473 | 19 | struct smack_known smack_known_huh = { |
e114e473 CS |
20 | .smk_known = "?", |
21 | .smk_secid = 2, | |
e114e473 CS |
22 | }; |
23 | ||
24 | struct smack_known smack_known_hat = { | |
e114e473 CS |
25 | .smk_known = "^", |
26 | .smk_secid = 3, | |
e114e473 CS |
27 | }; |
28 | ||
29 | struct smack_known smack_known_star = { | |
e114e473 CS |
30 | .smk_known = "*", |
31 | .smk_secid = 4, | |
e114e473 CS |
32 | }; |
33 | ||
34 | struct smack_known smack_known_floor = { | |
e114e473 CS |
35 | .smk_known = "_", |
36 | .smk_secid = 5, | |
e114e473 CS |
37 | }; |
38 | ||
39 | struct smack_known smack_known_invalid = { | |
e114e473 CS |
40 | .smk_known = "", |
41 | .smk_secid = 6, | |
e114e473 CS |
42 | }; |
43 | ||
6d3dc07c | 44 | struct smack_known smack_known_web = { |
6d3dc07c CS |
45 | .smk_known = "@", |
46 | .smk_secid = 7, | |
6d3dc07c CS |
47 | }; |
48 | ||
7198e2ee | 49 | LIST_HEAD(smack_known_list); |
e114e473 CS |
50 | |
51 | /* | |
52 | * The initial value needs to be bigger than any of the | |
53 | * known values above. | |
54 | */ | |
55 | static u32 smack_next_secid = 10; | |
56 | ||
ecfcc53f EB |
57 | /* |
58 | * what events do we log | |
59 | * can be overwritten at run-time by /smack/logging | |
60 | */ | |
61 | int log_policy = SMACK_AUDIT_DENIED; | |
62 | ||
5c6d1125 JS |
63 | /** |
64 | * smk_access_entry - look up matching access rule | |
65 | * @subject_label: a pointer to the subject's Smack label | |
66 | * @object_label: a pointer to the object's Smack label | |
7898e1f8 | 67 | * @rule_list: the list of rules to search |
5c6d1125 JS |
68 | * |
69 | * This function looks up the subject/object pair in the | |
7898e1f8 CS |
70 | * access rule list and returns the access mode. If no |
71 | * entry is found returns -ENOENT. | |
5c6d1125 JS |
72 | * |
73 | * NOTE: | |
5c6d1125 | 74 | * |
272cd7a8 CS |
75 | * Earlier versions of this function allowed for labels that |
76 | * were not on the label list. This was done to allow for | |
77 | * labels to come over the network that had never been seen | |
78 | * before on this host. Unless the receiving socket has the | |
79 | * star label this will always result in a failure check. The | |
80 | * star labeled socket case is now handled in the networking | |
81 | * hooks so there is no case where the label is not on the | |
82 | * label list. Checking to see if the address of two labels | |
83 | * is the same is now a reliable test. | |
84 | * | |
85 | * Do the object check first because that is more | |
86 | * likely to differ. | |
5c6d1125 | 87 | */ |
7898e1f8 CS |
88 | int smk_access_entry(char *subject_label, char *object_label, |
89 | struct list_head *rule_list) | |
5c6d1125 | 90 | { |
7898e1f8 | 91 | int may = -ENOENT; |
5c6d1125 JS |
92 | struct smack_rule *srp; |
93 | ||
7898e1f8 | 94 | list_for_each_entry_rcu(srp, rule_list, list) { |
272cd7a8 CS |
95 | if (srp->smk_object == object_label && |
96 | srp->smk_subject == subject_label) { | |
97 | may = srp->smk_access; | |
98 | break; | |
5c6d1125 JS |
99 | } |
100 | } | |
5c6d1125 JS |
101 | |
102 | return may; | |
103 | } | |
104 | ||
e114e473 CS |
105 | /** |
106 | * smk_access - determine if a subject has a specific access to an object | |
107 | * @subject_label: a pointer to the subject's Smack label | |
108 | * @object_label: a pointer to the object's Smack label | |
109 | * @request: the access requested, in "MAY" format | |
ecfcc53f | 110 | * @a : a pointer to the audit data |
e114e473 CS |
111 | * |
112 | * This function looks up the subject/object pair in the | |
113 | * access rule list and returns 0 if the access is permitted, | |
114 | * non zero otherwise. | |
115 | * | |
272cd7a8 | 116 | * Smack labels are shared on smack_list |
e114e473 | 117 | */ |
ecfcc53f EB |
118 | int smk_access(char *subject_label, char *object_label, int request, |
119 | struct smk_audit_info *a) | |
e114e473 | 120 | { |
272cd7a8 | 121 | struct smack_known *skp; |
7898e1f8 | 122 | int may = MAY_NOT; |
ecfcc53f | 123 | int rc = 0; |
e114e473 CS |
124 | |
125 | /* | |
126 | * Hardcoded comparisons. | |
127 | * | |
128 | * A star subject can't access any object. | |
129 | */ | |
272cd7a8 | 130 | if (subject_label == smack_known_star.smk_known) { |
ecfcc53f EB |
131 | rc = -EACCES; |
132 | goto out_audit; | |
133 | } | |
6d3dc07c CS |
134 | /* |
135 | * An internet object can be accessed by any subject. | |
136 | * Tasks cannot be assigned the internet label. | |
137 | * An internet subject can access any object. | |
138 | */ | |
139 | if (object_label == smack_known_web.smk_known || | |
272cd7a8 | 140 | subject_label == smack_known_web.smk_known) |
ecfcc53f | 141 | goto out_audit; |
e114e473 CS |
142 | /* |
143 | * A star object can be accessed by any subject. | |
144 | */ | |
272cd7a8 | 145 | if (object_label == smack_known_star.smk_known) |
ecfcc53f | 146 | goto out_audit; |
e114e473 CS |
147 | /* |
148 | * An object can be accessed in any way by a subject | |
149 | * with the same label. | |
150 | */ | |
272cd7a8 | 151 | if (subject_label == object_label) |
ecfcc53f | 152 | goto out_audit; |
e114e473 CS |
153 | /* |
154 | * A hat subject can read any object. | |
155 | * A floor object can be read by any subject. | |
156 | */ | |
157 | if ((request & MAY_ANYREAD) == request) { | |
272cd7a8 | 158 | if (object_label == smack_known_floor.smk_known) |
ecfcc53f | 159 | goto out_audit; |
272cd7a8 | 160 | if (subject_label == smack_known_hat.smk_known) |
ecfcc53f | 161 | goto out_audit; |
e114e473 CS |
162 | } |
163 | /* | |
164 | * Beyond here an explicit relationship is required. | |
165 | * If the requested access is contained in the available | |
166 | * access (e.g. read is included in readwrite) it's | |
7898e1f8 CS |
167 | * good. A negative response from smk_access_entry() |
168 | * indicates there is no entry for this pair. | |
e114e473 | 169 | */ |
272cd7a8 | 170 | skp = smk_find_entry(subject_label); |
7898e1f8 | 171 | rcu_read_lock(); |
272cd7a8 | 172 | may = smk_access_entry(subject_label, object_label, &skp->smk_rules); |
7898e1f8 CS |
173 | rcu_read_unlock(); |
174 | ||
175 | if (may > 0 && (request & may) == request) | |
ecfcc53f | 176 | goto out_audit; |
e114e473 | 177 | |
ecfcc53f EB |
178 | rc = -EACCES; |
179 | out_audit: | |
180 | #ifdef CONFIG_AUDIT | |
181 | if (a) | |
182 | smack_log(subject_label, object_label, request, rc, a); | |
183 | #endif | |
184 | return rc; | |
e114e473 CS |
185 | } |
186 | ||
187 | /** | |
188 | * smk_curacc - determine if current has a specific access to an object | |
251a2a95 RD |
189 | * @obj_label: a pointer to the object's Smack label |
190 | * @mode: the access requested, in "MAY" format | |
ecfcc53f | 191 | * @a : common audit data |
e114e473 CS |
192 | * |
193 | * This function checks the current subject label/object label pair | |
194 | * in the access rule list and returns 0 if the access is permitted, | |
15446235 | 195 | * non zero otherwise. It allows that current may have the capability |
e114e473 CS |
196 | * to override the rules. |
197 | */ | |
ecfcc53f | 198 | int smk_curacc(char *obj_label, u32 mode, struct smk_audit_info *a) |
e114e473 | 199 | { |
7898e1f8 CS |
200 | struct task_smack *tsp = current_security(); |
201 | char *sp = smk_of_task(tsp); | |
202 | int may; | |
e114e473 CS |
203 | int rc; |
204 | ||
7898e1f8 CS |
205 | /* |
206 | * Check the global rule list | |
207 | */ | |
ecfcc53f | 208 | rc = smk_access(sp, obj_label, mode, NULL); |
7898e1f8 CS |
209 | if (rc == 0) { |
210 | /* | |
211 | * If there is an entry in the task's rule list | |
212 | * it can further restrict access. | |
213 | */ | |
214 | may = smk_access_entry(sp, obj_label, &tsp->smk_rules); | |
215 | if (may < 0) | |
216 | goto out_audit; | |
217 | if ((mode & may) == mode) | |
218 | goto out_audit; | |
219 | rc = -EACCES; | |
220 | } | |
e114e473 | 221 | |
15446235 CS |
222 | /* |
223 | * Return if a specific label has been designated as the | |
224 | * only one that gets privilege and current does not | |
225 | * have that label. | |
226 | */ | |
676dac4b | 227 | if (smack_onlycap != NULL && smack_onlycap != sp) |
ecfcc53f | 228 | goto out_audit; |
15446235 | 229 | |
e114e473 | 230 | if (capable(CAP_MAC_OVERRIDE)) |
7898e1f8 | 231 | rc = 0; |
e114e473 | 232 | |
ecfcc53f EB |
233 | out_audit: |
234 | #ifdef CONFIG_AUDIT | |
235 | if (a) | |
236 | smack_log(sp, obj_label, mode, rc, a); | |
237 | #endif | |
e114e473 CS |
238 | return rc; |
239 | } | |
240 | ||
ecfcc53f EB |
241 | #ifdef CONFIG_AUDIT |
242 | /** | |
243 | * smack_str_from_perm : helper to transalate an int to a | |
244 | * readable string | |
245 | * @string : the string to fill | |
246 | * @access : the int | |
247 | * | |
248 | */ | |
249 | static inline void smack_str_from_perm(char *string, int access) | |
250 | { | |
251 | int i = 0; | |
252 | if (access & MAY_READ) | |
253 | string[i++] = 'r'; | |
254 | if (access & MAY_WRITE) | |
255 | string[i++] = 'w'; | |
256 | if (access & MAY_EXEC) | |
257 | string[i++] = 'x'; | |
258 | if (access & MAY_APPEND) | |
259 | string[i++] = 'a'; | |
260 | string[i] = '\0'; | |
261 | } | |
262 | /** | |
263 | * smack_log_callback - SMACK specific information | |
264 | * will be called by generic audit code | |
265 | * @ab : the audit_buffer | |
266 | * @a : audit_data | |
267 | * | |
268 | */ | |
269 | static void smack_log_callback(struct audit_buffer *ab, void *a) | |
270 | { | |
271 | struct common_audit_data *ad = a; | |
3b3b0e4f | 272 | struct smack_audit_data *sad = ad->smack_audit_data; |
ed5215a2 | 273 | audit_log_format(ab, "lsm=SMACK fn=%s action=%s", |
3b3b0e4f | 274 | ad->smack_audit_data->function, |
ecfcc53f EB |
275 | sad->result ? "denied" : "granted"); |
276 | audit_log_format(ab, " subject="); | |
277 | audit_log_untrustedstring(ab, sad->subject); | |
278 | audit_log_format(ab, " object="); | |
279 | audit_log_untrustedstring(ab, sad->object); | |
280 | audit_log_format(ab, " requested=%s", sad->request); | |
281 | } | |
282 | ||
283 | /** | |
284 | * smack_log - Audit the granting or denial of permissions. | |
285 | * @subject_label : smack label of the requester | |
286 | * @object_label : smack label of the object being accessed | |
287 | * @request: requested permissions | |
288 | * @result: result from smk_access | |
289 | * @a: auxiliary audit data | |
290 | * | |
291 | * Audit the granting or denial of permissions in accordance | |
292 | * with the policy. | |
293 | */ | |
294 | void smack_log(char *subject_label, char *object_label, int request, | |
295 | int result, struct smk_audit_info *ad) | |
296 | { | |
297 | char request_buffer[SMK_NUM_ACCESS_TYPE + 1]; | |
298 | struct smack_audit_data *sad; | |
299 | struct common_audit_data *a = &ad->a; | |
300 | ||
301 | /* check if we have to log the current event */ | |
302 | if (result != 0 && (log_policy & SMACK_AUDIT_DENIED) == 0) | |
303 | return; | |
304 | if (result == 0 && (log_policy & SMACK_AUDIT_ACCEPT) == 0) | |
305 | return; | |
306 | ||
3b3b0e4f EP |
307 | sad = a->smack_audit_data; |
308 | ||
309 | if (sad->function == NULL) | |
310 | sad->function = "unknown"; | |
ecfcc53f EB |
311 | |
312 | /* end preparing the audit data */ | |
ecfcc53f EB |
313 | smack_str_from_perm(request_buffer, request); |
314 | sad->subject = subject_label; | |
315 | sad->object = object_label; | |
316 | sad->request = request_buffer; | |
317 | sad->result = result; | |
ecfcc53f | 318 | |
b61c37f5 | 319 | common_lsm_audit(a, smack_log_callback, NULL); |
ecfcc53f EB |
320 | } |
321 | #else /* #ifdef CONFIG_AUDIT */ | |
322 | void smack_log(char *subject_label, char *object_label, int request, | |
323 | int result, struct smk_audit_info *ad) | |
324 | { | |
325 | } | |
326 | #endif | |
327 | ||
f7112e6c | 328 | DEFINE_MUTEX(smack_known_lock); |
e114e473 | 329 | |
272cd7a8 CS |
330 | /** |
331 | * smk_find_entry - find a label on the list, return the list entry | |
332 | * @string: a text string that might be a Smack label | |
333 | * | |
334 | * Returns a pointer to the entry in the label list that | |
335 | * matches the passed string. | |
336 | */ | |
337 | struct smack_known *smk_find_entry(const char *string) | |
338 | { | |
339 | struct smack_known *skp; | |
340 | ||
341 | list_for_each_entry_rcu(skp, &smack_known_list, list) { | |
f7112e6c | 342 | if (strcmp(skp->smk_known, string) == 0) |
272cd7a8 CS |
343 | return skp; |
344 | } | |
345 | ||
346 | return NULL; | |
347 | } | |
348 | ||
e114e473 | 349 | /** |
0e94ae17 JS |
350 | * smk_parse_smack - parse smack label from a text string |
351 | * @string: a text string that might contain a Smack label | |
e114e473 | 352 | * @len: the maximum size, or zero if it is NULL terminated. |
f7112e6c CS |
353 | * |
354 | * Returns a pointer to the clean label, or NULL | |
e114e473 | 355 | */ |
f7112e6c | 356 | char *smk_parse_smack(const char *string, int len) |
e114e473 | 357 | { |
f7112e6c | 358 | char *smack; |
e114e473 CS |
359 | int i; |
360 | ||
f7112e6c CS |
361 | if (len <= 0) |
362 | len = strlen(string) + 1; | |
363 | ||
364 | /* | |
365 | * Reserve a leading '-' as an indicator that | |
366 | * this isn't a label, but an option to interfaces | |
367 | * including /smack/cipso and /smack/cipso2 | |
368 | */ | |
369 | if (string[0] == '-') | |
370 | return NULL; | |
371 | ||
372 | for (i = 0; i < len; i++) | |
373 | if (string[i] > '~' || string[i] <= ' ' || string[i] == '/' || | |
374 | string[i] == '"' || string[i] == '\\' || string[i] == '\'') | |
375 | break; | |
376 | ||
377 | if (i == 0 || i >= SMK_LONGLABEL) | |
378 | return NULL; | |
379 | ||
380 | smack = kzalloc(i + 1, GFP_KERNEL); | |
381 | if (smack != NULL) { | |
382 | strncpy(smack, string, i + 1); | |
383 | smack[i] = '\0'; | |
e114e473 | 384 | } |
f7112e6c CS |
385 | return smack; |
386 | } | |
387 | ||
388 | /** | |
389 | * smk_netlbl_mls - convert a catset to netlabel mls categories | |
390 | * @catset: the Smack categories | |
391 | * @sap: where to put the netlabel categories | |
392 | * | |
393 | * Allocates and fills attr.mls | |
394 | * Returns 0 on success, error code on failure. | |
395 | */ | |
396 | int smk_netlbl_mls(int level, char *catset, struct netlbl_lsm_secattr *sap, | |
397 | int len) | |
398 | { | |
399 | unsigned char *cp; | |
400 | unsigned char m; | |
401 | int cat; | |
402 | int rc; | |
403 | int byte; | |
404 | ||
405 | sap->flags |= NETLBL_SECATTR_MLS_CAT; | |
406 | sap->attr.mls.lvl = level; | |
407 | sap->attr.mls.cat = netlbl_secattr_catmap_alloc(GFP_ATOMIC); | |
408 | sap->attr.mls.cat->startbit = 0; | |
409 | ||
410 | for (cat = 1, cp = catset, byte = 0; byte < len; cp++, byte++) | |
411 | for (m = 0x80; m != 0; m >>= 1, cat++) { | |
412 | if ((m & *cp) == 0) | |
413 | continue; | |
414 | rc = netlbl_secattr_catmap_setbit(sap->attr.mls.cat, | |
415 | cat, GFP_ATOMIC); | |
416 | if (rc < 0) { | |
417 | netlbl_secattr_catmap_free(sap->attr.mls.cat); | |
418 | return rc; | |
419 | } | |
420 | } | |
421 | ||
422 | return 0; | |
0e94ae17 JS |
423 | } |
424 | ||
425 | /** | |
426 | * smk_import_entry - import a label, return the list entry | |
427 | * @string: a text string that might be a Smack label | |
428 | * @len: the maximum size, or zero if it is NULL terminated. | |
429 | * | |
430 | * Returns a pointer to the entry in the label list that | |
431 | * matches the passed string, adding it if necessary. | |
432 | */ | |
433 | struct smack_known *smk_import_entry(const char *string, int len) | |
434 | { | |
435 | struct smack_known *skp; | |
f7112e6c CS |
436 | char *smack; |
437 | int slen; | |
438 | int rc; | |
e114e473 | 439 | |
f7112e6c CS |
440 | smack = smk_parse_smack(string, len); |
441 | if (smack == NULL) | |
e114e473 CS |
442 | return NULL; |
443 | ||
444 | mutex_lock(&smack_known_lock); | |
445 | ||
272cd7a8 | 446 | skp = smk_find_entry(smack); |
f7112e6c CS |
447 | if (skp != NULL) |
448 | goto freeout; | |
e114e473 | 449 | |
f7112e6c CS |
450 | skp = kzalloc(sizeof(*skp), GFP_KERNEL); |
451 | if (skp == NULL) | |
452 | goto freeout; | |
e114e473 | 453 | |
f7112e6c CS |
454 | skp->smk_known = smack; |
455 | skp->smk_secid = smack_next_secid++; | |
456 | skp->smk_netlabel.domain = skp->smk_known; | |
457 | skp->smk_netlabel.flags = | |
458 | NETLBL_SECATTR_DOMAIN | NETLBL_SECATTR_MLS_LVL; | |
459 | /* | |
460 | * If direct labeling works use it. | |
461 | * Otherwise use mapped labeling. | |
462 | */ | |
463 | slen = strlen(smack); | |
464 | if (slen < SMK_CIPSOLEN) | |
465 | rc = smk_netlbl_mls(smack_cipso_direct, skp->smk_known, | |
466 | &skp->smk_netlabel, slen); | |
467 | else | |
468 | rc = smk_netlbl_mls(smack_cipso_mapped, (char *)&skp->smk_secid, | |
469 | &skp->smk_netlabel, sizeof(skp->smk_secid)); | |
470 | ||
471 | if (rc >= 0) { | |
472 | INIT_LIST_HEAD(&skp->smk_rules); | |
473 | mutex_init(&skp->smk_rules_lock); | |
474 | /* | |
475 | * Make sure that the entry is actually | |
476 | * filled before putting it on the list. | |
477 | */ | |
478 | list_add_rcu(&skp->list, &smack_known_list); | |
479 | goto unlockout; | |
480 | } | |
481 | /* | |
482 | * smk_netlbl_mls failed. | |
483 | */ | |
484 | kfree(skp); | |
485 | skp = NULL; | |
486 | freeout: | |
487 | kfree(smack); | |
488 | unlockout: | |
e114e473 CS |
489 | mutex_unlock(&smack_known_lock); |
490 | ||
491 | return skp; | |
492 | } | |
493 | ||
494 | /** | |
495 | * smk_import - import a smack label | |
496 | * @string: a text string that might be a Smack label | |
497 | * @len: the maximum size, or zero if it is NULL terminated. | |
498 | * | |
499 | * Returns a pointer to the label in the label list that | |
500 | * matches the passed string, adding it if necessary. | |
501 | */ | |
502 | char *smk_import(const char *string, int len) | |
503 | { | |
504 | struct smack_known *skp; | |
505 | ||
4303154e EB |
506 | /* labels cannot begin with a '-' */ |
507 | if (string[0] == '-') | |
508 | return NULL; | |
e114e473 CS |
509 | skp = smk_import_entry(string, len); |
510 | if (skp == NULL) | |
511 | return NULL; | |
512 | return skp->smk_known; | |
513 | } | |
514 | ||
515 | /** | |
516 | * smack_from_secid - find the Smack label associated with a secid | |
517 | * @secid: an integer that might be associated with a Smack label | |
518 | * | |
25985edc | 519 | * Returns a pointer to the appropriate Smack label if there is one, |
e114e473 CS |
520 | * otherwise a pointer to the invalid Smack label. |
521 | */ | |
522 | char *smack_from_secid(const u32 secid) | |
523 | { | |
524 | struct smack_known *skp; | |
525 | ||
7198e2ee EB |
526 | rcu_read_lock(); |
527 | list_for_each_entry_rcu(skp, &smack_known_list, list) { | |
528 | if (skp->smk_secid == secid) { | |
529 | rcu_read_unlock(); | |
e114e473 | 530 | return skp->smk_known; |
7198e2ee EB |
531 | } |
532 | } | |
e114e473 CS |
533 | |
534 | /* | |
535 | * If we got this far someone asked for the translation | |
536 | * of a secid that is not on the list. | |
537 | */ | |
7198e2ee | 538 | rcu_read_unlock(); |
e114e473 CS |
539 | return smack_known_invalid.smk_known; |
540 | } | |
541 | ||
542 | /** | |
543 | * smack_to_secid - find the secid associated with a Smack label | |
544 | * @smack: the Smack label | |
545 | * | |
546 | * Returns the appropriate secid if there is one, | |
547 | * otherwise 0 | |
548 | */ | |
549 | u32 smack_to_secid(const char *smack) | |
550 | { | |
f7112e6c | 551 | struct smack_known *skp = smk_find_entry(smack); |
e114e473 | 552 | |
f7112e6c CS |
553 | if (skp == NULL) |
554 | return 0; | |
555 | return skp->smk_secid; | |
e114e473 | 556 | } |