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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, | |
22 | .smk_cipso = NULL, | |
23 | }; | |
24 | ||
25 | struct smack_known smack_known_hat = { | |
e114e473 CS |
26 | .smk_known = "^", |
27 | .smk_secid = 3, | |
28 | .smk_cipso = NULL, | |
29 | }; | |
30 | ||
31 | struct smack_known smack_known_star = { | |
e114e473 CS |
32 | .smk_known = "*", |
33 | .smk_secid = 4, | |
34 | .smk_cipso = NULL, | |
35 | }; | |
36 | ||
37 | struct smack_known smack_known_floor = { | |
e114e473 CS |
38 | .smk_known = "_", |
39 | .smk_secid = 5, | |
40 | .smk_cipso = NULL, | |
41 | }; | |
42 | ||
43 | struct smack_known smack_known_invalid = { | |
e114e473 CS |
44 | .smk_known = "", |
45 | .smk_secid = 6, | |
46 | .smk_cipso = NULL, | |
47 | }; | |
48 | ||
6d3dc07c | 49 | struct smack_known smack_known_web = { |
6d3dc07c CS |
50 | .smk_known = "@", |
51 | .smk_secid = 7, | |
52 | .smk_cipso = NULL, | |
53 | }; | |
54 | ||
7198e2ee | 55 | LIST_HEAD(smack_known_list); |
e114e473 CS |
56 | |
57 | /* | |
58 | * The initial value needs to be bigger than any of the | |
59 | * known values above. | |
60 | */ | |
61 | static u32 smack_next_secid = 10; | |
62 | ||
ecfcc53f EB |
63 | /* |
64 | * what events do we log | |
65 | * can be overwritten at run-time by /smack/logging | |
66 | */ | |
67 | int log_policy = SMACK_AUDIT_DENIED; | |
68 | ||
5c6d1125 JS |
69 | /** |
70 | * smk_access_entry - look up matching access rule | |
71 | * @subject_label: a pointer to the subject's Smack label | |
72 | * @object_label: a pointer to the object's Smack label | |
7898e1f8 | 73 | * @rule_list: the list of rules to search |
5c6d1125 JS |
74 | * |
75 | * This function looks up the subject/object pair in the | |
7898e1f8 CS |
76 | * access rule list and returns the access mode. If no |
77 | * entry is found returns -ENOENT. | |
5c6d1125 JS |
78 | * |
79 | * NOTE: | |
80 | * Even though Smack labels are usually shared on smack_list | |
81 | * labels that come in off the network can't be imported | |
82 | * and added to the list for locking reasons. | |
83 | * | |
84 | * Therefore, it is necessary to check the contents of the labels, | |
85 | * not just the pointer values. Of course, in most cases the labels | |
86 | * will be on the list, so checking the pointers may be a worthwhile | |
87 | * optimization. | |
88 | */ | |
7898e1f8 CS |
89 | int smk_access_entry(char *subject_label, char *object_label, |
90 | struct list_head *rule_list) | |
5c6d1125 | 91 | { |
7898e1f8 | 92 | int may = -ENOENT; |
5c6d1125 JS |
93 | struct smack_rule *srp; |
94 | ||
7898e1f8 | 95 | list_for_each_entry_rcu(srp, rule_list, list) { |
5c6d1125 JS |
96 | if (srp->smk_subject == subject_label || |
97 | strcmp(srp->smk_subject, subject_label) == 0) { | |
98 | if (srp->smk_object == object_label || | |
99 | strcmp(srp->smk_object, object_label) == 0) { | |
100 | may = srp->smk_access; | |
101 | break; | |
102 | } | |
103 | } | |
104 | } | |
5c6d1125 JS |
105 | |
106 | return may; | |
107 | } | |
108 | ||
e114e473 CS |
109 | /** |
110 | * smk_access - determine if a subject has a specific access to an object | |
111 | * @subject_label: a pointer to the subject's Smack label | |
112 | * @object_label: a pointer to the object's Smack label | |
113 | * @request: the access requested, in "MAY" format | |
ecfcc53f | 114 | * @a : a pointer to the audit data |
e114e473 CS |
115 | * |
116 | * This function looks up the subject/object pair in the | |
117 | * access rule list and returns 0 if the access is permitted, | |
118 | * non zero otherwise. | |
119 | * | |
120 | * Even though Smack labels are usually shared on smack_list | |
121 | * labels that come in off the network can't be imported | |
122 | * and added to the list for locking reasons. | |
123 | * | |
124 | * Therefore, it is necessary to check the contents of the labels, | |
125 | * not just the pointer values. Of course, in most cases the labels | |
126 | * will be on the list, so checking the pointers may be a worthwhile | |
127 | * optimization. | |
128 | */ | |
ecfcc53f EB |
129 | int smk_access(char *subject_label, char *object_label, int request, |
130 | struct smk_audit_info *a) | |
e114e473 | 131 | { |
7898e1f8 | 132 | int may = MAY_NOT; |
ecfcc53f | 133 | int rc = 0; |
e114e473 CS |
134 | |
135 | /* | |
136 | * Hardcoded comparisons. | |
137 | * | |
138 | * A star subject can't access any object. | |
139 | */ | |
140 | if (subject_label == smack_known_star.smk_known || | |
ecfcc53f EB |
141 | strcmp(subject_label, smack_known_star.smk_known) == 0) { |
142 | rc = -EACCES; | |
143 | goto out_audit; | |
144 | } | |
6d3dc07c CS |
145 | /* |
146 | * An internet object can be accessed by any subject. | |
147 | * Tasks cannot be assigned the internet label. | |
148 | * An internet subject can access any object. | |
149 | */ | |
150 | if (object_label == smack_known_web.smk_known || | |
151 | subject_label == smack_known_web.smk_known || | |
152 | strcmp(object_label, smack_known_web.smk_known) == 0 || | |
153 | strcmp(subject_label, smack_known_web.smk_known) == 0) | |
ecfcc53f | 154 | goto out_audit; |
e114e473 CS |
155 | /* |
156 | * A star object can be accessed by any subject. | |
157 | */ | |
158 | if (object_label == smack_known_star.smk_known || | |
159 | strcmp(object_label, smack_known_star.smk_known) == 0) | |
ecfcc53f | 160 | goto out_audit; |
e114e473 CS |
161 | /* |
162 | * An object can be accessed in any way by a subject | |
163 | * with the same label. | |
164 | */ | |
165 | if (subject_label == object_label || | |
166 | strcmp(subject_label, object_label) == 0) | |
ecfcc53f | 167 | goto out_audit; |
e114e473 CS |
168 | /* |
169 | * A hat subject can read any object. | |
170 | * A floor object can be read by any subject. | |
171 | */ | |
172 | if ((request & MAY_ANYREAD) == request) { | |
173 | if (object_label == smack_known_floor.smk_known || | |
174 | strcmp(object_label, smack_known_floor.smk_known) == 0) | |
ecfcc53f | 175 | goto out_audit; |
e114e473 CS |
176 | if (subject_label == smack_known_hat.smk_known || |
177 | strcmp(subject_label, smack_known_hat.smk_known) == 0) | |
ecfcc53f | 178 | goto out_audit; |
e114e473 CS |
179 | } |
180 | /* | |
181 | * Beyond here an explicit relationship is required. | |
182 | * If the requested access is contained in the available | |
183 | * access (e.g. read is included in readwrite) it's | |
7898e1f8 CS |
184 | * good. A negative response from smk_access_entry() |
185 | * indicates there is no entry for this pair. | |
e114e473 | 186 | */ |
7898e1f8 CS |
187 | rcu_read_lock(); |
188 | may = smk_access_entry(subject_label, object_label, &smack_rule_list); | |
189 | rcu_read_unlock(); | |
190 | ||
191 | if (may > 0 && (request & may) == request) | |
ecfcc53f | 192 | goto out_audit; |
e114e473 | 193 | |
ecfcc53f EB |
194 | rc = -EACCES; |
195 | out_audit: | |
196 | #ifdef CONFIG_AUDIT | |
197 | if (a) | |
198 | smack_log(subject_label, object_label, request, rc, a); | |
199 | #endif | |
200 | return rc; | |
e114e473 CS |
201 | } |
202 | ||
203 | /** | |
204 | * smk_curacc - determine if current has a specific access to an object | |
251a2a95 RD |
205 | * @obj_label: a pointer to the object's Smack label |
206 | * @mode: the access requested, in "MAY" format | |
ecfcc53f | 207 | * @a : common audit data |
e114e473 CS |
208 | * |
209 | * This function checks the current subject label/object label pair | |
210 | * in the access rule list and returns 0 if the access is permitted, | |
15446235 | 211 | * non zero otherwise. It allows that current may have the capability |
e114e473 CS |
212 | * to override the rules. |
213 | */ | |
ecfcc53f | 214 | int smk_curacc(char *obj_label, u32 mode, struct smk_audit_info *a) |
e114e473 | 215 | { |
7898e1f8 CS |
216 | struct task_smack *tsp = current_security(); |
217 | char *sp = smk_of_task(tsp); | |
218 | int may; | |
e114e473 CS |
219 | int rc; |
220 | ||
7898e1f8 CS |
221 | /* |
222 | * Check the global rule list | |
223 | */ | |
ecfcc53f | 224 | rc = smk_access(sp, obj_label, mode, NULL); |
7898e1f8 CS |
225 | if (rc == 0) { |
226 | /* | |
227 | * If there is an entry in the task's rule list | |
228 | * it can further restrict access. | |
229 | */ | |
230 | may = smk_access_entry(sp, obj_label, &tsp->smk_rules); | |
231 | if (may < 0) | |
232 | goto out_audit; | |
233 | if ((mode & may) == mode) | |
234 | goto out_audit; | |
235 | rc = -EACCES; | |
236 | } | |
e114e473 | 237 | |
15446235 CS |
238 | /* |
239 | * Return if a specific label has been designated as the | |
240 | * only one that gets privilege and current does not | |
241 | * have that label. | |
242 | */ | |
676dac4b | 243 | if (smack_onlycap != NULL && smack_onlycap != sp) |
ecfcc53f | 244 | goto out_audit; |
15446235 | 245 | |
e114e473 | 246 | if (capable(CAP_MAC_OVERRIDE)) |
7898e1f8 | 247 | rc = 0; |
e114e473 | 248 | |
ecfcc53f EB |
249 | out_audit: |
250 | #ifdef CONFIG_AUDIT | |
251 | if (a) | |
252 | smack_log(sp, obj_label, mode, rc, a); | |
253 | #endif | |
e114e473 CS |
254 | return rc; |
255 | } | |
256 | ||
ecfcc53f EB |
257 | #ifdef CONFIG_AUDIT |
258 | /** | |
259 | * smack_str_from_perm : helper to transalate an int to a | |
260 | * readable string | |
261 | * @string : the string to fill | |
262 | * @access : the int | |
263 | * | |
264 | */ | |
265 | static inline void smack_str_from_perm(char *string, int access) | |
266 | { | |
267 | int i = 0; | |
268 | if (access & MAY_READ) | |
269 | string[i++] = 'r'; | |
270 | if (access & MAY_WRITE) | |
271 | string[i++] = 'w'; | |
272 | if (access & MAY_EXEC) | |
273 | string[i++] = 'x'; | |
274 | if (access & MAY_APPEND) | |
275 | string[i++] = 'a'; | |
276 | string[i] = '\0'; | |
277 | } | |
278 | /** | |
279 | * smack_log_callback - SMACK specific information | |
280 | * will be called by generic audit code | |
281 | * @ab : the audit_buffer | |
282 | * @a : audit_data | |
283 | * | |
284 | */ | |
285 | static void smack_log_callback(struct audit_buffer *ab, void *a) | |
286 | { | |
287 | struct common_audit_data *ad = a; | |
d4131ded | 288 | struct smack_audit_data *sad = &ad->smack_audit_data; |
ed5215a2 | 289 | audit_log_format(ab, "lsm=SMACK fn=%s action=%s", |
d4131ded | 290 | ad->smack_audit_data.function, |
ecfcc53f EB |
291 | sad->result ? "denied" : "granted"); |
292 | audit_log_format(ab, " subject="); | |
293 | audit_log_untrustedstring(ab, sad->subject); | |
294 | audit_log_format(ab, " object="); | |
295 | audit_log_untrustedstring(ab, sad->object); | |
296 | audit_log_format(ab, " requested=%s", sad->request); | |
297 | } | |
298 | ||
299 | /** | |
300 | * smack_log - Audit the granting or denial of permissions. | |
301 | * @subject_label : smack label of the requester | |
302 | * @object_label : smack label of the object being accessed | |
303 | * @request: requested permissions | |
304 | * @result: result from smk_access | |
305 | * @a: auxiliary audit data | |
306 | * | |
307 | * Audit the granting or denial of permissions in accordance | |
308 | * with the policy. | |
309 | */ | |
310 | void smack_log(char *subject_label, char *object_label, int request, | |
311 | int result, struct smk_audit_info *ad) | |
312 | { | |
313 | char request_buffer[SMK_NUM_ACCESS_TYPE + 1]; | |
314 | struct smack_audit_data *sad; | |
315 | struct common_audit_data *a = &ad->a; | |
316 | ||
317 | /* check if we have to log the current event */ | |
318 | if (result != 0 && (log_policy & SMACK_AUDIT_DENIED) == 0) | |
319 | return; | |
320 | if (result == 0 && (log_policy & SMACK_AUDIT_ACCEPT) == 0) | |
321 | return; | |
322 | ||
d4131ded TL |
323 | if (a->smack_audit_data.function == NULL) |
324 | a->smack_audit_data.function = "unknown"; | |
ecfcc53f EB |
325 | |
326 | /* end preparing the audit data */ | |
d4131ded | 327 | sad = &a->smack_audit_data; |
ecfcc53f EB |
328 | smack_str_from_perm(request_buffer, request); |
329 | sad->subject = subject_label; | |
330 | sad->object = object_label; | |
331 | sad->request = request_buffer; | |
332 | sad->result = result; | |
333 | a->lsm_pre_audit = smack_log_callback; | |
334 | ||
335 | common_lsm_audit(a); | |
336 | } | |
337 | #else /* #ifdef CONFIG_AUDIT */ | |
338 | void smack_log(char *subject_label, char *object_label, int request, | |
339 | int result, struct smk_audit_info *ad) | |
340 | { | |
341 | } | |
342 | #endif | |
343 | ||
e114e473 CS |
344 | static DEFINE_MUTEX(smack_known_lock); |
345 | ||
346 | /** | |
347 | * smk_import_entry - import a label, return the list entry | |
348 | * @string: a text string that might be a Smack label | |
349 | * @len: the maximum size, or zero if it is NULL terminated. | |
350 | * | |
351 | * Returns a pointer to the entry in the label list that | |
352 | * matches the passed string, adding it if necessary. | |
353 | */ | |
354 | struct smack_known *smk_import_entry(const char *string, int len) | |
355 | { | |
356 | struct smack_known *skp; | |
357 | char smack[SMK_LABELLEN]; | |
358 | int found; | |
359 | int i; | |
360 | ||
361 | if (len <= 0 || len > SMK_MAXLEN) | |
362 | len = SMK_MAXLEN; | |
363 | ||
364 | for (i = 0, found = 0; i < SMK_LABELLEN; i++) { | |
365 | if (found) | |
366 | smack[i] = '\0'; | |
367 | else if (i >= len || string[i] > '~' || string[i] <= ' ' || | |
ecfcc53f EB |
368 | string[i] == '/' || string[i] == '"' || |
369 | string[i] == '\\' || string[i] == '\'') { | |
e114e473 CS |
370 | smack[i] = '\0'; |
371 | found = 1; | |
372 | } else | |
373 | smack[i] = string[i]; | |
374 | } | |
375 | ||
376 | if (smack[0] == '\0') | |
377 | return NULL; | |
378 | ||
379 | mutex_lock(&smack_known_lock); | |
380 | ||
7198e2ee EB |
381 | found = 0; |
382 | list_for_each_entry_rcu(skp, &smack_known_list, list) { | |
383 | if (strncmp(skp->smk_known, smack, SMK_MAXLEN) == 0) { | |
384 | found = 1; | |
e114e473 | 385 | break; |
7198e2ee EB |
386 | } |
387 | } | |
e114e473 | 388 | |
7198e2ee | 389 | if (found == 0) { |
e114e473 CS |
390 | skp = kzalloc(sizeof(struct smack_known), GFP_KERNEL); |
391 | if (skp != NULL) { | |
e114e473 CS |
392 | strncpy(skp->smk_known, smack, SMK_MAXLEN); |
393 | skp->smk_secid = smack_next_secid++; | |
394 | skp->smk_cipso = NULL; | |
395 | spin_lock_init(&skp->smk_cipsolock); | |
396 | /* | |
397 | * Make sure that the entry is actually | |
398 | * filled before putting it on the list. | |
399 | */ | |
7198e2ee | 400 | list_add_rcu(&skp->list, &smack_known_list); |
e114e473 CS |
401 | } |
402 | } | |
403 | ||
404 | mutex_unlock(&smack_known_lock); | |
405 | ||
406 | return skp; | |
407 | } | |
408 | ||
409 | /** | |
410 | * smk_import - import a smack label | |
411 | * @string: a text string that might be a Smack label | |
412 | * @len: the maximum size, or zero if it is NULL terminated. | |
413 | * | |
414 | * Returns a pointer to the label in the label list that | |
415 | * matches the passed string, adding it if necessary. | |
416 | */ | |
417 | char *smk_import(const char *string, int len) | |
418 | { | |
419 | struct smack_known *skp; | |
420 | ||
4303154e EB |
421 | /* labels cannot begin with a '-' */ |
422 | if (string[0] == '-') | |
423 | return NULL; | |
e114e473 CS |
424 | skp = smk_import_entry(string, len); |
425 | if (skp == NULL) | |
426 | return NULL; | |
427 | return skp->smk_known; | |
428 | } | |
429 | ||
430 | /** | |
431 | * smack_from_secid - find the Smack label associated with a secid | |
432 | * @secid: an integer that might be associated with a Smack label | |
433 | * | |
25985edc | 434 | * Returns a pointer to the appropriate Smack label if there is one, |
e114e473 CS |
435 | * otherwise a pointer to the invalid Smack label. |
436 | */ | |
437 | char *smack_from_secid(const u32 secid) | |
438 | { | |
439 | struct smack_known *skp; | |
440 | ||
7198e2ee EB |
441 | rcu_read_lock(); |
442 | list_for_each_entry_rcu(skp, &smack_known_list, list) { | |
443 | if (skp->smk_secid == secid) { | |
444 | rcu_read_unlock(); | |
e114e473 | 445 | return skp->smk_known; |
7198e2ee EB |
446 | } |
447 | } | |
e114e473 CS |
448 | |
449 | /* | |
450 | * If we got this far someone asked for the translation | |
451 | * of a secid that is not on the list. | |
452 | */ | |
7198e2ee | 453 | rcu_read_unlock(); |
e114e473 CS |
454 | return smack_known_invalid.smk_known; |
455 | } | |
456 | ||
457 | /** | |
458 | * smack_to_secid - find the secid associated with a Smack label | |
459 | * @smack: the Smack label | |
460 | * | |
461 | * Returns the appropriate secid if there is one, | |
462 | * otherwise 0 | |
463 | */ | |
464 | u32 smack_to_secid(const char *smack) | |
465 | { | |
466 | struct smack_known *skp; | |
467 | ||
7198e2ee EB |
468 | rcu_read_lock(); |
469 | list_for_each_entry_rcu(skp, &smack_known_list, list) { | |
470 | if (strncmp(skp->smk_known, smack, SMK_MAXLEN) == 0) { | |
471 | rcu_read_unlock(); | |
e114e473 | 472 | return skp->smk_secid; |
7198e2ee EB |
473 | } |
474 | } | |
475 | rcu_read_unlock(); | |
e114e473 CS |
476 | return 0; |
477 | } | |
478 | ||
479 | /** | |
480 | * smack_from_cipso - find the Smack label associated with a CIPSO option | |
481 | * @level: Bell & LaPadula level from the network | |
482 | * @cp: Bell & LaPadula categories from the network | |
483 | * @result: where to put the Smack value | |
484 | * | |
485 | * This is a simple lookup in the label table. | |
486 | * | |
487 | * This is an odd duck as far as smack handling goes in that | |
488 | * it sends back a copy of the smack label rather than a pointer | |
489 | * to the master list. This is done because it is possible for | |
490 | * a foreign host to send a smack label that is new to this | |
491 | * machine and hence not on the list. That would not be an | |
492 | * issue except that adding an entry to the master list can't | |
493 | * be done at that point. | |
494 | */ | |
495 | void smack_from_cipso(u32 level, char *cp, char *result) | |
496 | { | |
497 | struct smack_known *kp; | |
498 | char *final = NULL; | |
499 | ||
7198e2ee EB |
500 | rcu_read_lock(); |
501 | list_for_each_entry(kp, &smack_known_list, list) { | |
e114e473 CS |
502 | if (kp->smk_cipso == NULL) |
503 | continue; | |
504 | ||
505 | spin_lock_bh(&kp->smk_cipsolock); | |
506 | ||
507 | if (kp->smk_cipso->smk_level == level && | |
508 | memcmp(kp->smk_cipso->smk_catset, cp, SMK_LABELLEN) == 0) | |
509 | final = kp->smk_known; | |
510 | ||
511 | spin_unlock_bh(&kp->smk_cipsolock); | |
512 | } | |
7198e2ee | 513 | rcu_read_unlock(); |
e114e473 CS |
514 | if (final == NULL) |
515 | final = smack_known_huh.smk_known; | |
516 | strncpy(result, final, SMK_MAXLEN); | |
517 | return; | |
518 | } | |
519 | ||
520 | /** | |
521 | * smack_to_cipso - find the CIPSO option to go with a Smack label | |
522 | * @smack: a pointer to the smack label in question | |
523 | * @cp: where to put the result | |
524 | * | |
525 | * Returns zero if a value is available, non-zero otherwise. | |
526 | */ | |
527 | int smack_to_cipso(const char *smack, struct smack_cipso *cp) | |
528 | { | |
529 | struct smack_known *kp; | |
7198e2ee | 530 | int found = 0; |
e114e473 | 531 | |
7198e2ee EB |
532 | rcu_read_lock(); |
533 | list_for_each_entry_rcu(kp, &smack_known_list, list) { | |
e114e473 | 534 | if (kp->smk_known == smack || |
7198e2ee EB |
535 | strcmp(kp->smk_known, smack) == 0) { |
536 | found = 1; | |
e114e473 | 537 | break; |
7198e2ee EB |
538 | } |
539 | } | |
540 | rcu_read_unlock(); | |
e114e473 | 541 | |
7198e2ee | 542 | if (found == 0 || kp->smk_cipso == NULL) |
e114e473 CS |
543 | return -ENOENT; |
544 | ||
545 | memcpy(cp, kp->smk_cipso, sizeof(struct smack_cipso)); | |
546 | return 0; | |
547 | } |