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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 | |
73 | * | |
74 | * This function looks up the subject/object pair in the | |
75 | * access rule list and returns pointer to the matching rule if found, | |
76 | * NULL otherwise. | |
77 | * | |
78 | * NOTE: | |
79 | * Even though Smack labels are usually shared on smack_list | |
80 | * labels that come in off the network can't be imported | |
81 | * and added to the list for locking reasons. | |
82 | * | |
83 | * Therefore, it is necessary to check the contents of the labels, | |
84 | * not just the pointer values. Of course, in most cases the labels | |
85 | * will be on the list, so checking the pointers may be a worthwhile | |
86 | * optimization. | |
87 | */ | |
88 | int smk_access_entry(char *subject_label, char *object_label) | |
89 | { | |
90 | u32 may = MAY_NOT; | |
91 | struct smack_rule *srp; | |
92 | ||
93 | rcu_read_lock(); | |
94 | list_for_each_entry_rcu(srp, &smack_rule_list, list) { | |
95 | if (srp->smk_subject == subject_label || | |
96 | strcmp(srp->smk_subject, subject_label) == 0) { | |
97 | if (srp->smk_object == object_label || | |
98 | strcmp(srp->smk_object, object_label) == 0) { | |
99 | may = srp->smk_access; | |
100 | break; | |
101 | } | |
102 | } | |
103 | } | |
104 | rcu_read_unlock(); | |
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 CS |
131 | { |
132 | u32 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 | |
184 | * good. | |
185 | */ | |
5c6d1125 | 186 | may = smk_access_entry(subject_label, object_label); |
e114e473 CS |
187 | /* |
188 | * This is a bit map operation. | |
189 | */ | |
190 | if ((request & may) == request) | |
ecfcc53f | 191 | goto out_audit; |
e114e473 | 192 | |
ecfcc53f EB |
193 | rc = -EACCES; |
194 | out_audit: | |
195 | #ifdef CONFIG_AUDIT | |
196 | if (a) | |
197 | smack_log(subject_label, object_label, request, rc, a); | |
198 | #endif | |
199 | return rc; | |
e114e473 CS |
200 | } |
201 | ||
202 | /** | |
203 | * smk_curacc - determine if current has a specific access to an object | |
251a2a95 RD |
204 | * @obj_label: a pointer to the object's Smack label |
205 | * @mode: the access requested, in "MAY" format | |
ecfcc53f | 206 | * @a : common audit data |
e114e473 CS |
207 | * |
208 | * This function checks the current subject label/object label pair | |
209 | * in the access rule list and returns 0 if the access is permitted, | |
15446235 | 210 | * non zero otherwise. It allows that current may have the capability |
e114e473 CS |
211 | * to override the rules. |
212 | */ | |
ecfcc53f | 213 | int smk_curacc(char *obj_label, u32 mode, struct smk_audit_info *a) |
e114e473 CS |
214 | { |
215 | int rc; | |
676dac4b | 216 | char *sp = smk_of_current(); |
e114e473 | 217 | |
ecfcc53f | 218 | rc = smk_access(sp, obj_label, mode, NULL); |
e114e473 | 219 | if (rc == 0) |
ecfcc53f | 220 | goto out_audit; |
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 CS |
230 | if (capable(CAP_MAC_OVERRIDE)) |
231 | return 0; | |
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; | |
d4131ded | 272 | struct smack_audit_data *sad = &ad->smack_audit_data; |
ed5215a2 | 273 | audit_log_format(ab, "lsm=SMACK fn=%s action=%s", |
d4131ded | 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 | ||
d4131ded TL |
307 | if (a->smack_audit_data.function == NULL) |
308 | a->smack_audit_data.function = "unknown"; | |
ecfcc53f EB |
309 | |
310 | /* end preparing the audit data */ | |
d4131ded | 311 | sad = &a->smack_audit_data; |
ecfcc53f EB |
312 | smack_str_from_perm(request_buffer, request); |
313 | sad->subject = subject_label; | |
314 | sad->object = object_label; | |
315 | sad->request = request_buffer; | |
316 | sad->result = result; | |
317 | a->lsm_pre_audit = smack_log_callback; | |
318 | ||
319 | common_lsm_audit(a); | |
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 | ||
e114e473 CS |
328 | static DEFINE_MUTEX(smack_known_lock); |
329 | ||
330 | /** | |
331 | * smk_import_entry - import a label, return the list entry | |
332 | * @string: a text string that might be a Smack label | |
333 | * @len: the maximum size, or zero if it is NULL terminated. | |
334 | * | |
335 | * Returns a pointer to the entry in the label list that | |
336 | * matches the passed string, adding it if necessary. | |
337 | */ | |
338 | struct smack_known *smk_import_entry(const char *string, int len) | |
339 | { | |
340 | struct smack_known *skp; | |
341 | char smack[SMK_LABELLEN]; | |
342 | int found; | |
343 | int i; | |
344 | ||
345 | if (len <= 0 || len > SMK_MAXLEN) | |
346 | len = SMK_MAXLEN; | |
347 | ||
348 | for (i = 0, found = 0; i < SMK_LABELLEN; i++) { | |
349 | if (found) | |
350 | smack[i] = '\0'; | |
351 | else if (i >= len || string[i] > '~' || string[i] <= ' ' || | |
ecfcc53f EB |
352 | string[i] == '/' || string[i] == '"' || |
353 | string[i] == '\\' || string[i] == '\'') { | |
e114e473 CS |
354 | smack[i] = '\0'; |
355 | found = 1; | |
356 | } else | |
357 | smack[i] = string[i]; | |
358 | } | |
359 | ||
360 | if (smack[0] == '\0') | |
361 | return NULL; | |
362 | ||
363 | mutex_lock(&smack_known_lock); | |
364 | ||
7198e2ee EB |
365 | found = 0; |
366 | list_for_each_entry_rcu(skp, &smack_known_list, list) { | |
367 | if (strncmp(skp->smk_known, smack, SMK_MAXLEN) == 0) { | |
368 | found = 1; | |
e114e473 | 369 | break; |
7198e2ee EB |
370 | } |
371 | } | |
e114e473 | 372 | |
7198e2ee | 373 | if (found == 0) { |
e114e473 CS |
374 | skp = kzalloc(sizeof(struct smack_known), GFP_KERNEL); |
375 | if (skp != NULL) { | |
e114e473 CS |
376 | strncpy(skp->smk_known, smack, SMK_MAXLEN); |
377 | skp->smk_secid = smack_next_secid++; | |
378 | skp->smk_cipso = NULL; | |
379 | spin_lock_init(&skp->smk_cipsolock); | |
380 | /* | |
381 | * Make sure that the entry is actually | |
382 | * filled before putting it on the list. | |
383 | */ | |
7198e2ee | 384 | list_add_rcu(&skp->list, &smack_known_list); |
e114e473 CS |
385 | } |
386 | } | |
387 | ||
388 | mutex_unlock(&smack_known_lock); | |
389 | ||
390 | return skp; | |
391 | } | |
392 | ||
393 | /** | |
394 | * smk_import - import a smack label | |
395 | * @string: a text string that might be a Smack label | |
396 | * @len: the maximum size, or zero if it is NULL terminated. | |
397 | * | |
398 | * Returns a pointer to the label in the label list that | |
399 | * matches the passed string, adding it if necessary. | |
400 | */ | |
401 | char *smk_import(const char *string, int len) | |
402 | { | |
403 | struct smack_known *skp; | |
404 | ||
4303154e EB |
405 | /* labels cannot begin with a '-' */ |
406 | if (string[0] == '-') | |
407 | return NULL; | |
e114e473 CS |
408 | skp = smk_import_entry(string, len); |
409 | if (skp == NULL) | |
410 | return NULL; | |
411 | return skp->smk_known; | |
412 | } | |
413 | ||
414 | /** | |
415 | * smack_from_secid - find the Smack label associated with a secid | |
416 | * @secid: an integer that might be associated with a Smack label | |
417 | * | |
418 | * Returns a pointer to the appropraite Smack label if there is one, | |
419 | * otherwise a pointer to the invalid Smack label. | |
420 | */ | |
421 | char *smack_from_secid(const u32 secid) | |
422 | { | |
423 | struct smack_known *skp; | |
424 | ||
7198e2ee EB |
425 | rcu_read_lock(); |
426 | list_for_each_entry_rcu(skp, &smack_known_list, list) { | |
427 | if (skp->smk_secid == secid) { | |
428 | rcu_read_unlock(); | |
e114e473 | 429 | return skp->smk_known; |
7198e2ee EB |
430 | } |
431 | } | |
e114e473 CS |
432 | |
433 | /* | |
434 | * If we got this far someone asked for the translation | |
435 | * of a secid that is not on the list. | |
436 | */ | |
7198e2ee | 437 | rcu_read_unlock(); |
e114e473 CS |
438 | return smack_known_invalid.smk_known; |
439 | } | |
440 | ||
441 | /** | |
442 | * smack_to_secid - find the secid associated with a Smack label | |
443 | * @smack: the Smack label | |
444 | * | |
445 | * Returns the appropriate secid if there is one, | |
446 | * otherwise 0 | |
447 | */ | |
448 | u32 smack_to_secid(const char *smack) | |
449 | { | |
450 | struct smack_known *skp; | |
451 | ||
7198e2ee EB |
452 | rcu_read_lock(); |
453 | list_for_each_entry_rcu(skp, &smack_known_list, list) { | |
454 | if (strncmp(skp->smk_known, smack, SMK_MAXLEN) == 0) { | |
455 | rcu_read_unlock(); | |
e114e473 | 456 | return skp->smk_secid; |
7198e2ee EB |
457 | } |
458 | } | |
459 | rcu_read_unlock(); | |
e114e473 CS |
460 | return 0; |
461 | } | |
462 | ||
463 | /** | |
464 | * smack_from_cipso - find the Smack label associated with a CIPSO option | |
465 | * @level: Bell & LaPadula level from the network | |
466 | * @cp: Bell & LaPadula categories from the network | |
467 | * @result: where to put the Smack value | |
468 | * | |
469 | * This is a simple lookup in the label table. | |
470 | * | |
471 | * This is an odd duck as far as smack handling goes in that | |
472 | * it sends back a copy of the smack label rather than a pointer | |
473 | * to the master list. This is done because it is possible for | |
474 | * a foreign host to send a smack label that is new to this | |
475 | * machine and hence not on the list. That would not be an | |
476 | * issue except that adding an entry to the master list can't | |
477 | * be done at that point. | |
478 | */ | |
479 | void smack_from_cipso(u32 level, char *cp, char *result) | |
480 | { | |
481 | struct smack_known *kp; | |
482 | char *final = NULL; | |
483 | ||
7198e2ee EB |
484 | rcu_read_lock(); |
485 | list_for_each_entry(kp, &smack_known_list, list) { | |
e114e473 CS |
486 | if (kp->smk_cipso == NULL) |
487 | continue; | |
488 | ||
489 | spin_lock_bh(&kp->smk_cipsolock); | |
490 | ||
491 | if (kp->smk_cipso->smk_level == level && | |
492 | memcmp(kp->smk_cipso->smk_catset, cp, SMK_LABELLEN) == 0) | |
493 | final = kp->smk_known; | |
494 | ||
495 | spin_unlock_bh(&kp->smk_cipsolock); | |
496 | } | |
7198e2ee | 497 | rcu_read_unlock(); |
e114e473 CS |
498 | if (final == NULL) |
499 | final = smack_known_huh.smk_known; | |
500 | strncpy(result, final, SMK_MAXLEN); | |
501 | return; | |
502 | } | |
503 | ||
504 | /** | |
505 | * smack_to_cipso - find the CIPSO option to go with a Smack label | |
506 | * @smack: a pointer to the smack label in question | |
507 | * @cp: where to put the result | |
508 | * | |
509 | * Returns zero if a value is available, non-zero otherwise. | |
510 | */ | |
511 | int smack_to_cipso(const char *smack, struct smack_cipso *cp) | |
512 | { | |
513 | struct smack_known *kp; | |
7198e2ee | 514 | int found = 0; |
e114e473 | 515 | |
7198e2ee EB |
516 | rcu_read_lock(); |
517 | list_for_each_entry_rcu(kp, &smack_known_list, list) { | |
e114e473 | 518 | if (kp->smk_known == smack || |
7198e2ee EB |
519 | strcmp(kp->smk_known, smack) == 0) { |
520 | found = 1; | |
e114e473 | 521 | break; |
7198e2ee EB |
522 | } |
523 | } | |
524 | rcu_read_unlock(); | |
e114e473 | 525 | |
7198e2ee | 526 | if (found == 0 || kp->smk_cipso == NULL) |
e114e473 CS |
527 | return -ENOENT; |
528 | ||
529 | memcpy(cp, kp->smk_cipso, sizeof(struct smack_cipso)); | |
530 | return 0; | |
531 | } |