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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 | ||
e114e473 CS |
69 | /** |
70 | * smk_access - determine if a subject has a specific access to an object | |
71 | * @subject_label: a pointer to the subject's Smack label | |
72 | * @object_label: a pointer to the object's Smack label | |
73 | * @request: the access requested, in "MAY" format | |
ecfcc53f | 74 | * @a : a pointer to the audit data |
e114e473 CS |
75 | * |
76 | * This function looks up the subject/object pair in the | |
77 | * access rule list and returns 0 if the access is permitted, | |
78 | * non zero otherwise. | |
79 | * | |
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 | */ | |
ecfcc53f EB |
89 | int smk_access(char *subject_label, char *object_label, int request, |
90 | struct smk_audit_info *a) | |
e114e473 CS |
91 | { |
92 | u32 may = MAY_NOT; | |
e114e473 | 93 | struct smack_rule *srp; |
ecfcc53f | 94 | int rc = 0; |
e114e473 CS |
95 | |
96 | /* | |
97 | * Hardcoded comparisons. | |
98 | * | |
99 | * A star subject can't access any object. | |
100 | */ | |
101 | if (subject_label == smack_known_star.smk_known || | |
ecfcc53f EB |
102 | strcmp(subject_label, smack_known_star.smk_known) == 0) { |
103 | rc = -EACCES; | |
104 | goto out_audit; | |
105 | } | |
6d3dc07c CS |
106 | /* |
107 | * An internet object can be accessed by any subject. | |
108 | * Tasks cannot be assigned the internet label. | |
109 | * An internet subject can access any object. | |
110 | */ | |
111 | if (object_label == smack_known_web.smk_known || | |
112 | subject_label == smack_known_web.smk_known || | |
113 | strcmp(object_label, smack_known_web.smk_known) == 0 || | |
114 | strcmp(subject_label, smack_known_web.smk_known) == 0) | |
ecfcc53f | 115 | goto out_audit; |
e114e473 CS |
116 | /* |
117 | * A star object can be accessed by any subject. | |
118 | */ | |
119 | if (object_label == smack_known_star.smk_known || | |
120 | strcmp(object_label, smack_known_star.smk_known) == 0) | |
ecfcc53f | 121 | goto out_audit; |
e114e473 CS |
122 | /* |
123 | * An object can be accessed in any way by a subject | |
124 | * with the same label. | |
125 | */ | |
126 | if (subject_label == object_label || | |
127 | strcmp(subject_label, object_label) == 0) | |
ecfcc53f | 128 | goto out_audit; |
e114e473 CS |
129 | /* |
130 | * A hat subject can read any object. | |
131 | * A floor object can be read by any subject. | |
132 | */ | |
133 | if ((request & MAY_ANYREAD) == request) { | |
134 | if (object_label == smack_known_floor.smk_known || | |
135 | strcmp(object_label, smack_known_floor.smk_known) == 0) | |
ecfcc53f | 136 | goto out_audit; |
e114e473 CS |
137 | if (subject_label == smack_known_hat.smk_known || |
138 | strcmp(subject_label, smack_known_hat.smk_known) == 0) | |
ecfcc53f | 139 | goto out_audit; |
e114e473 CS |
140 | } |
141 | /* | |
142 | * Beyond here an explicit relationship is required. | |
143 | * If the requested access is contained in the available | |
144 | * access (e.g. read is included in readwrite) it's | |
145 | * good. | |
146 | */ | |
7198e2ee EB |
147 | rcu_read_lock(); |
148 | list_for_each_entry_rcu(srp, &smack_rule_list, list) { | |
e114e473 CS |
149 | if (srp->smk_subject == subject_label || |
150 | strcmp(srp->smk_subject, subject_label) == 0) { | |
151 | if (srp->smk_object == object_label || | |
152 | strcmp(srp->smk_object, object_label) == 0) { | |
153 | may = srp->smk_access; | |
154 | break; | |
155 | } | |
156 | } | |
157 | } | |
7198e2ee | 158 | rcu_read_unlock(); |
e114e473 CS |
159 | /* |
160 | * This is a bit map operation. | |
161 | */ | |
162 | if ((request & may) == request) | |
ecfcc53f | 163 | goto out_audit; |
e114e473 | 164 | |
ecfcc53f EB |
165 | rc = -EACCES; |
166 | out_audit: | |
167 | #ifdef CONFIG_AUDIT | |
168 | if (a) | |
169 | smack_log(subject_label, object_label, request, rc, a); | |
170 | #endif | |
171 | return rc; | |
e114e473 CS |
172 | } |
173 | ||
174 | /** | |
175 | * smk_curacc - determine if current has a specific access to an object | |
251a2a95 RD |
176 | * @obj_label: a pointer to the object's Smack label |
177 | * @mode: the access requested, in "MAY" format | |
ecfcc53f | 178 | * @a : common audit data |
e114e473 CS |
179 | * |
180 | * This function checks the current subject label/object label pair | |
181 | * in the access rule list and returns 0 if the access is permitted, | |
15446235 | 182 | * non zero otherwise. It allows that current may have the capability |
e114e473 CS |
183 | * to override the rules. |
184 | */ | |
ecfcc53f | 185 | int smk_curacc(char *obj_label, u32 mode, struct smk_audit_info *a) |
e114e473 CS |
186 | { |
187 | int rc; | |
ecfcc53f | 188 | char *sp = current_security(); |
e114e473 | 189 | |
ecfcc53f | 190 | rc = smk_access(sp, obj_label, mode, NULL); |
e114e473 | 191 | if (rc == 0) |
ecfcc53f | 192 | goto out_audit; |
e114e473 | 193 | |
15446235 CS |
194 | /* |
195 | * Return if a specific label has been designated as the | |
196 | * only one that gets privilege and current does not | |
197 | * have that label. | |
198 | */ | |
b6dff3ec | 199 | if (smack_onlycap != NULL && smack_onlycap != current->cred->security) |
ecfcc53f | 200 | goto out_audit; |
15446235 | 201 | |
e114e473 CS |
202 | if (capable(CAP_MAC_OVERRIDE)) |
203 | return 0; | |
204 | ||
ecfcc53f EB |
205 | out_audit: |
206 | #ifdef CONFIG_AUDIT | |
207 | if (a) | |
208 | smack_log(sp, obj_label, mode, rc, a); | |
209 | #endif | |
e114e473 CS |
210 | return rc; |
211 | } | |
212 | ||
ecfcc53f EB |
213 | #ifdef CONFIG_AUDIT |
214 | /** | |
215 | * smack_str_from_perm : helper to transalate an int to a | |
216 | * readable string | |
217 | * @string : the string to fill | |
218 | * @access : the int | |
219 | * | |
220 | */ | |
221 | static inline void smack_str_from_perm(char *string, int access) | |
222 | { | |
223 | int i = 0; | |
224 | if (access & MAY_READ) | |
225 | string[i++] = 'r'; | |
226 | if (access & MAY_WRITE) | |
227 | string[i++] = 'w'; | |
228 | if (access & MAY_EXEC) | |
229 | string[i++] = 'x'; | |
230 | if (access & MAY_APPEND) | |
231 | string[i++] = 'a'; | |
232 | string[i] = '\0'; | |
233 | } | |
234 | /** | |
235 | * smack_log_callback - SMACK specific information | |
236 | * will be called by generic audit code | |
237 | * @ab : the audit_buffer | |
238 | * @a : audit_data | |
239 | * | |
240 | */ | |
241 | static void smack_log_callback(struct audit_buffer *ab, void *a) | |
242 | { | |
243 | struct common_audit_data *ad = a; | |
d4131ded | 244 | struct smack_audit_data *sad = &ad->smack_audit_data; |
ed5215a2 | 245 | audit_log_format(ab, "lsm=SMACK fn=%s action=%s", |
d4131ded | 246 | ad->smack_audit_data.function, |
ecfcc53f EB |
247 | sad->result ? "denied" : "granted"); |
248 | audit_log_format(ab, " subject="); | |
249 | audit_log_untrustedstring(ab, sad->subject); | |
250 | audit_log_format(ab, " object="); | |
251 | audit_log_untrustedstring(ab, sad->object); | |
252 | audit_log_format(ab, " requested=%s", sad->request); | |
253 | } | |
254 | ||
255 | /** | |
256 | * smack_log - Audit the granting or denial of permissions. | |
257 | * @subject_label : smack label of the requester | |
258 | * @object_label : smack label of the object being accessed | |
259 | * @request: requested permissions | |
260 | * @result: result from smk_access | |
261 | * @a: auxiliary audit data | |
262 | * | |
263 | * Audit the granting or denial of permissions in accordance | |
264 | * with the policy. | |
265 | */ | |
266 | void smack_log(char *subject_label, char *object_label, int request, | |
267 | int result, struct smk_audit_info *ad) | |
268 | { | |
269 | char request_buffer[SMK_NUM_ACCESS_TYPE + 1]; | |
270 | struct smack_audit_data *sad; | |
271 | struct common_audit_data *a = &ad->a; | |
272 | ||
273 | /* check if we have to log the current event */ | |
274 | if (result != 0 && (log_policy & SMACK_AUDIT_DENIED) == 0) | |
275 | return; | |
276 | if (result == 0 && (log_policy & SMACK_AUDIT_ACCEPT) == 0) | |
277 | return; | |
278 | ||
d4131ded TL |
279 | if (a->smack_audit_data.function == NULL) |
280 | a->smack_audit_data.function = "unknown"; | |
ecfcc53f EB |
281 | |
282 | /* end preparing the audit data */ | |
d4131ded | 283 | sad = &a->smack_audit_data; |
ecfcc53f EB |
284 | smack_str_from_perm(request_buffer, request); |
285 | sad->subject = subject_label; | |
286 | sad->object = object_label; | |
287 | sad->request = request_buffer; | |
288 | sad->result = result; | |
289 | a->lsm_pre_audit = smack_log_callback; | |
290 | ||
291 | common_lsm_audit(a); | |
292 | } | |
293 | #else /* #ifdef CONFIG_AUDIT */ | |
294 | void smack_log(char *subject_label, char *object_label, int request, | |
295 | int result, struct smk_audit_info *ad) | |
296 | { | |
297 | } | |
298 | #endif | |
299 | ||
e114e473 CS |
300 | static DEFINE_MUTEX(smack_known_lock); |
301 | ||
302 | /** | |
303 | * smk_import_entry - import a label, return the list entry | |
304 | * @string: a text string that might be a Smack label | |
305 | * @len: the maximum size, or zero if it is NULL terminated. | |
306 | * | |
307 | * Returns a pointer to the entry in the label list that | |
308 | * matches the passed string, adding it if necessary. | |
309 | */ | |
310 | struct smack_known *smk_import_entry(const char *string, int len) | |
311 | { | |
312 | struct smack_known *skp; | |
313 | char smack[SMK_LABELLEN]; | |
314 | int found; | |
315 | int i; | |
316 | ||
317 | if (len <= 0 || len > SMK_MAXLEN) | |
318 | len = SMK_MAXLEN; | |
319 | ||
320 | for (i = 0, found = 0; i < SMK_LABELLEN; i++) { | |
321 | if (found) | |
322 | smack[i] = '\0'; | |
323 | else if (i >= len || string[i] > '~' || string[i] <= ' ' || | |
ecfcc53f EB |
324 | string[i] == '/' || string[i] == '"' || |
325 | string[i] == '\\' || string[i] == '\'') { | |
e114e473 CS |
326 | smack[i] = '\0'; |
327 | found = 1; | |
328 | } else | |
329 | smack[i] = string[i]; | |
330 | } | |
331 | ||
332 | if (smack[0] == '\0') | |
333 | return NULL; | |
334 | ||
335 | mutex_lock(&smack_known_lock); | |
336 | ||
7198e2ee EB |
337 | found = 0; |
338 | list_for_each_entry_rcu(skp, &smack_known_list, list) { | |
339 | if (strncmp(skp->smk_known, smack, SMK_MAXLEN) == 0) { | |
340 | found = 1; | |
e114e473 | 341 | break; |
7198e2ee EB |
342 | } |
343 | } | |
e114e473 | 344 | |
7198e2ee | 345 | if (found == 0) { |
e114e473 CS |
346 | skp = kzalloc(sizeof(struct smack_known), GFP_KERNEL); |
347 | if (skp != NULL) { | |
e114e473 CS |
348 | strncpy(skp->smk_known, smack, SMK_MAXLEN); |
349 | skp->smk_secid = smack_next_secid++; | |
350 | skp->smk_cipso = NULL; | |
351 | spin_lock_init(&skp->smk_cipsolock); | |
352 | /* | |
353 | * Make sure that the entry is actually | |
354 | * filled before putting it on the list. | |
355 | */ | |
7198e2ee | 356 | list_add_rcu(&skp->list, &smack_known_list); |
e114e473 CS |
357 | } |
358 | } | |
359 | ||
360 | mutex_unlock(&smack_known_lock); | |
361 | ||
362 | return skp; | |
363 | } | |
364 | ||
365 | /** | |
366 | * smk_import - import a smack label | |
367 | * @string: a text string that might be a Smack label | |
368 | * @len: the maximum size, or zero if it is NULL terminated. | |
369 | * | |
370 | * Returns a pointer to the label in the label list that | |
371 | * matches the passed string, adding it if necessary. | |
372 | */ | |
373 | char *smk_import(const char *string, int len) | |
374 | { | |
375 | struct smack_known *skp; | |
376 | ||
4303154e EB |
377 | /* labels cannot begin with a '-' */ |
378 | if (string[0] == '-') | |
379 | return NULL; | |
e114e473 CS |
380 | skp = smk_import_entry(string, len); |
381 | if (skp == NULL) | |
382 | return NULL; | |
383 | return skp->smk_known; | |
384 | } | |
385 | ||
386 | /** | |
387 | * smack_from_secid - find the Smack label associated with a secid | |
388 | * @secid: an integer that might be associated with a Smack label | |
389 | * | |
390 | * Returns a pointer to the appropraite Smack label if there is one, | |
391 | * otherwise a pointer to the invalid Smack label. | |
392 | */ | |
393 | char *smack_from_secid(const u32 secid) | |
394 | { | |
395 | struct smack_known *skp; | |
396 | ||
7198e2ee EB |
397 | rcu_read_lock(); |
398 | list_for_each_entry_rcu(skp, &smack_known_list, list) { | |
399 | if (skp->smk_secid == secid) { | |
400 | rcu_read_unlock(); | |
e114e473 | 401 | return skp->smk_known; |
7198e2ee EB |
402 | } |
403 | } | |
e114e473 CS |
404 | |
405 | /* | |
406 | * If we got this far someone asked for the translation | |
407 | * of a secid that is not on the list. | |
408 | */ | |
7198e2ee | 409 | rcu_read_unlock(); |
e114e473 CS |
410 | return smack_known_invalid.smk_known; |
411 | } | |
412 | ||
413 | /** | |
414 | * smack_to_secid - find the secid associated with a Smack label | |
415 | * @smack: the Smack label | |
416 | * | |
417 | * Returns the appropriate secid if there is one, | |
418 | * otherwise 0 | |
419 | */ | |
420 | u32 smack_to_secid(const char *smack) | |
421 | { | |
422 | struct smack_known *skp; | |
423 | ||
7198e2ee EB |
424 | rcu_read_lock(); |
425 | list_for_each_entry_rcu(skp, &smack_known_list, list) { | |
426 | if (strncmp(skp->smk_known, smack, SMK_MAXLEN) == 0) { | |
427 | rcu_read_unlock(); | |
e114e473 | 428 | return skp->smk_secid; |
7198e2ee EB |
429 | } |
430 | } | |
431 | rcu_read_unlock(); | |
e114e473 CS |
432 | return 0; |
433 | } | |
434 | ||
435 | /** | |
436 | * smack_from_cipso - find the Smack label associated with a CIPSO option | |
437 | * @level: Bell & LaPadula level from the network | |
438 | * @cp: Bell & LaPadula categories from the network | |
439 | * @result: where to put the Smack value | |
440 | * | |
441 | * This is a simple lookup in the label table. | |
442 | * | |
443 | * This is an odd duck as far as smack handling goes in that | |
444 | * it sends back a copy of the smack label rather than a pointer | |
445 | * to the master list. This is done because it is possible for | |
446 | * a foreign host to send a smack label that is new to this | |
447 | * machine and hence not on the list. That would not be an | |
448 | * issue except that adding an entry to the master list can't | |
449 | * be done at that point. | |
450 | */ | |
451 | void smack_from_cipso(u32 level, char *cp, char *result) | |
452 | { | |
453 | struct smack_known *kp; | |
454 | char *final = NULL; | |
455 | ||
7198e2ee EB |
456 | rcu_read_lock(); |
457 | list_for_each_entry(kp, &smack_known_list, list) { | |
e114e473 CS |
458 | if (kp->smk_cipso == NULL) |
459 | continue; | |
460 | ||
461 | spin_lock_bh(&kp->smk_cipsolock); | |
462 | ||
463 | if (kp->smk_cipso->smk_level == level && | |
464 | memcmp(kp->smk_cipso->smk_catset, cp, SMK_LABELLEN) == 0) | |
465 | final = kp->smk_known; | |
466 | ||
467 | spin_unlock_bh(&kp->smk_cipsolock); | |
468 | } | |
7198e2ee | 469 | rcu_read_unlock(); |
e114e473 CS |
470 | if (final == NULL) |
471 | final = smack_known_huh.smk_known; | |
472 | strncpy(result, final, SMK_MAXLEN); | |
473 | return; | |
474 | } | |
475 | ||
476 | /** | |
477 | * smack_to_cipso - find the CIPSO option to go with a Smack label | |
478 | * @smack: a pointer to the smack label in question | |
479 | * @cp: where to put the result | |
480 | * | |
481 | * Returns zero if a value is available, non-zero otherwise. | |
482 | */ | |
483 | int smack_to_cipso(const char *smack, struct smack_cipso *cp) | |
484 | { | |
485 | struct smack_known *kp; | |
7198e2ee | 486 | int found = 0; |
e114e473 | 487 | |
7198e2ee EB |
488 | rcu_read_lock(); |
489 | list_for_each_entry_rcu(kp, &smack_known_list, list) { | |
e114e473 | 490 | if (kp->smk_known == smack || |
7198e2ee EB |
491 | strcmp(kp->smk_known, smack) == 0) { |
492 | found = 1; | |
e114e473 | 493 | break; |
7198e2ee EB |
494 | } |
495 | } | |
496 | rcu_read_unlock(); | |
e114e473 | 497 | |
7198e2ee | 498 | if (found == 0 || kp->smk_cipso == NULL) |
e114e473 CS |
499 | return -ENOENT; |
500 | ||
501 | memcpy(cp, kp->smk_cipso, sizeof(struct smack_cipso)); | |
502 | return 0; | |
503 | } |