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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>
14#include <linux/slab.h>
15#include <linux/fs.h>
16#include <linux/sched.h>
17#include "smack.h"
18
19struct smack_known smack_known_huh = {
20 .smk_known = "?",
21 .smk_secid = 2,
22};
23
24struct smack_known smack_known_hat = {
25 .smk_known = "^",
26 .smk_secid = 3,
27};
28
29struct smack_known smack_known_star = {
30 .smk_known = "*",
31 .smk_secid = 4,
32};
33
34struct smack_known smack_known_floor = {
35 .smk_known = "_",
36 .smk_secid = 5,
37};
38
39struct smack_known smack_known_invalid = {
40 .smk_known = "",
41 .smk_secid = 6,
42};
43
44struct smack_known smack_known_web = {
45 .smk_known = "@",
46 .smk_secid = 7,
47};
48
49LIST_HEAD(smack_known_list);
50
51/*
52 * The initial value needs to be bigger than any of the
53 * known values above.
54 */
55static u32 smack_next_secid = 10;
56
57/*
58 * what events do we log
59 * can be overwritten at run-time by /smack/logging
60 */
61int log_policy = SMACK_AUDIT_DENIED;
62
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
67 * @rule_list: the list of rules to search
68 *
69 * This function looks up the subject/object pair in the
70 * access rule list and returns the access mode. If no
71 * entry is found returns -ENOENT.
72 *
73 * NOTE:
74 *
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.
87 *
88 * Allowing write access implies allowing locking.
89 */
90int smk_access_entry(char *subject_label, char *object_label,
91 struct list_head *rule_list)
92{
93 int may = -ENOENT;
94 struct smack_rule *srp;
95
96 list_for_each_entry_rcu(srp, rule_list, list) {
97 if (srp->smk_object->smk_known == object_label &&
98 srp->smk_subject->smk_known == subject_label) {
99 may = srp->smk_access;
100 break;
101 }
102 }
103
104 /*
105 * MAY_WRITE implies MAY_LOCK.
106 */
107 if ((may & MAY_WRITE) == MAY_WRITE)
108 may |= MAY_LOCK;
109 return may;
110}
111
112/**
113 * smk_access - determine if a subject has a specific access to an object
114 * @subject: a pointer to the subject's Smack label entry
115 * @object: a pointer to the object's Smack label entry
116 * @request: the access requested, in "MAY" format
117 * @a : a pointer to the audit data
118 *
119 * This function looks up the subject/object pair in the
120 * access rule list and returns 0 if the access is permitted,
121 * non zero otherwise.
122 *
123 * Smack labels are shared on smack_list
124 */
125int smk_access(struct smack_known *subject, struct smack_known *object,
126 int request, struct smk_audit_info *a)
127{
128 int may = MAY_NOT;
129 int rc = 0;
130
131 /*
132 * Hardcoded comparisons.
133 */
134 /*
135 * A star subject can't access any object.
136 */
137 if (subject == &smack_known_star) {
138 rc = -EACCES;
139 goto out_audit;
140 }
141 /*
142 * An internet object can be accessed by any subject.
143 * Tasks cannot be assigned the internet label.
144 * An internet subject can access any object.
145 */
146 if (object == &smack_known_web || subject == &smack_known_web)
147 goto out_audit;
148 /*
149 * A star object can be accessed by any subject.
150 */
151 if (object == &smack_known_star)
152 goto out_audit;
153 /*
154 * An object can be accessed in any way by a subject
155 * with the same label.
156 */
157 if (subject->smk_known == object->smk_known)
158 goto out_audit;
159 /*
160 * A hat subject can read or lock any object.
161 * A floor object can be read or locked by any subject.
162 */
163 if ((request & MAY_ANYREAD) == request ||
164 (request & MAY_LOCK) == request) {
165 if (object == &smack_known_floor)
166 goto out_audit;
167 if (subject == &smack_known_hat)
168 goto out_audit;
169 }
170 /*
171 * Beyond here an explicit relationship is required.
172 * If the requested access is contained in the available
173 * access (e.g. read is included in readwrite) it's
174 * good. A negative response from smk_access_entry()
175 * indicates there is no entry for this pair.
176 */
177 rcu_read_lock();
178 may = smk_access_entry(subject->smk_known, object->smk_known,
179 &subject->smk_rules);
180 rcu_read_unlock();
181
182 if (may <= 0 || (request & may) != request) {
183 rc = -EACCES;
184 goto out_audit;
185 }
186#ifdef CONFIG_SECURITY_SMACK_BRINGUP
187 /*
188 * Return a positive value if using bringup mode.
189 * This allows the hooks to identify checks that
190 * succeed because of "b" rules.
191 */
192 if (may & MAY_BRINGUP)
193 rc = SMACK_BRINGUP_ALLOW;
194#endif
195
196out_audit:
197
198#ifdef CONFIG_SECURITY_SMACK_BRINGUP
199 if (rc < 0) {
200 if (object == smack_unconfined)
201 rc = SMACK_UNCONFINED_OBJECT;
202 if (subject == smack_unconfined)
203 rc = SMACK_UNCONFINED_SUBJECT;
204 }
205#endif
206
207#ifdef CONFIG_AUDIT
208 if (a)
209 smack_log(subject->smk_known, object->smk_known,
210 request, rc, a);
211#endif
212
213 return rc;
214}
215
216/**
217 * smk_tskacc - determine if a task has a specific access to an object
218 * @tsp: a pointer to the subject's task
219 * @obj_known: a pointer to the object's label entry
220 * @mode: the access requested, in "MAY" format
221 * @a : common audit data
222 *
223 * This function checks the subject task's label/object label pair
224 * in the access rule list and returns 0 if the access is permitted,
225 * non zero otherwise. It allows that the task may have the capability
226 * to override the rules.
227 */
228int smk_tskacc(struct task_smack *tsp, struct smack_known *obj_known,
229 u32 mode, struct smk_audit_info *a)
230{
231 struct smack_known *sbj_known = smk_of_task(tsp);
232 int may;
233 int rc;
234
235 /*
236 * Check the global rule list
237 */
238 rc = smk_access(sbj_known, obj_known, mode, NULL);
239 if (rc >= 0) {
240 /*
241 * If there is an entry in the task's rule list
242 * it can further restrict access.
243 */
244 may = smk_access_entry(sbj_known->smk_known,
245 obj_known->smk_known,
246 &tsp->smk_rules);
247 if (may < 0)
248 goto out_audit;
249 if ((mode & may) == mode)
250 goto out_audit;
251 rc = -EACCES;
252 }
253
254 /*
255 * Allow for priviliged to override policy.
256 */
257 if (rc != 0 && smack_privileged(CAP_MAC_OVERRIDE))
258 rc = 0;
259
260out_audit:
261#ifdef CONFIG_AUDIT
262 if (a)
263 smack_log(sbj_known->smk_known, obj_known->smk_known,
264 mode, rc, a);
265#endif
266 return rc;
267}
268
269/**
270 * smk_curacc - determine if current has a specific access to an object
271 * @obj_known: a pointer to the object's Smack label entry
272 * @mode: the access requested, in "MAY" format
273 * @a : common audit data
274 *
275 * This function checks the current subject label/object label pair
276 * in the access rule list and returns 0 if the access is permitted,
277 * non zero otherwise. It allows that current may have the capability
278 * to override the rules.
279 */
280int smk_curacc(struct smack_known *obj_known,
281 u32 mode, struct smk_audit_info *a)
282{
283 struct task_smack *tsp = current_security();
284
285 return smk_tskacc(tsp, obj_known, mode, a);
286}
287
288#ifdef CONFIG_AUDIT
289/**
290 * smack_str_from_perm : helper to transalate an int to a
291 * readable string
292 * @string : the string to fill
293 * @access : the int
294 *
295 */
296static inline void smack_str_from_perm(char *string, int access)
297{
298 int i = 0;
299
300 if (access & MAY_READ)
301 string[i++] = 'r';
302 if (access & MAY_WRITE)
303 string[i++] = 'w';
304 if (access & MAY_EXEC)
305 string[i++] = 'x';
306 if (access & MAY_APPEND)
307 string[i++] = 'a';
308 if (access & MAY_TRANSMUTE)
309 string[i++] = 't';
310 if (access & MAY_LOCK)
311 string[i++] = 'l';
312 string[i] = '\0';
313}
314/**
315 * smack_log_callback - SMACK specific information
316 * will be called by generic audit code
317 * @ab : the audit_buffer
318 * @a : audit_data
319 *
320 */
321static void smack_log_callback(struct audit_buffer *ab, void *a)
322{
323 struct common_audit_data *ad = a;
324 struct smack_audit_data *sad = ad->smack_audit_data;
325 audit_log_format(ab, "lsm=SMACK fn=%s action=%s",
326 ad->smack_audit_data->function,
327 sad->result ? "denied" : "granted");
328 audit_log_format(ab, " subject=");
329 audit_log_untrustedstring(ab, sad->subject);
330 audit_log_format(ab, " object=");
331 audit_log_untrustedstring(ab, sad->object);
332 if (sad->request[0] == '\0')
333 audit_log_format(ab, " labels_differ");
334 else
335 audit_log_format(ab, " requested=%s", sad->request);
336}
337
338/**
339 * smack_log - Audit the granting or denial of permissions.
340 * @subject_label : smack label of the requester
341 * @object_label : smack label of the object being accessed
342 * @request: requested permissions
343 * @result: result from smk_access
344 * @a: auxiliary audit data
345 *
346 * Audit the granting or denial of permissions in accordance
347 * with the policy.
348 */
349void smack_log(char *subject_label, char *object_label, int request,
350 int result, struct smk_audit_info *ad)
351{
352#ifdef CONFIG_SECURITY_SMACK_BRINGUP
353 char request_buffer[SMK_NUM_ACCESS_TYPE + 5];
354#else
355 char request_buffer[SMK_NUM_ACCESS_TYPE + 1];
356#endif
357 struct smack_audit_data *sad;
358 struct common_audit_data *a = &ad->a;
359
360 /* check if we have to log the current event */
361 if (result < 0 && (log_policy & SMACK_AUDIT_DENIED) == 0)
362 return;
363 if (result == 0 && (log_policy & SMACK_AUDIT_ACCEPT) == 0)
364 return;
365
366 sad = a->smack_audit_data;
367
368 if (sad->function == NULL)
369 sad->function = "unknown";
370
371 /* end preparing the audit data */
372 smack_str_from_perm(request_buffer, request);
373 sad->subject = subject_label;
374 sad->object = object_label;
375#ifdef CONFIG_SECURITY_SMACK_BRINGUP
376 /*
377 * The result may be positive in bringup mode.
378 * A positive result is an allow, but not for normal reasons.
379 * Mark it as successful, but don't filter it out even if
380 * the logging policy says to do so.
381 */
382 if (result == SMACK_UNCONFINED_SUBJECT)
383 strcat(request_buffer, "(US)");
384 else if (result == SMACK_UNCONFINED_OBJECT)
385 strcat(request_buffer, "(UO)");
386
387 if (result > 0)
388 result = 0;
389#endif
390 sad->request = request_buffer;
391 sad->result = result;
392
393 common_lsm_audit(a, smack_log_callback, NULL);
394}
395#else /* #ifdef CONFIG_AUDIT */
396void smack_log(char *subject_label, char *object_label, int request,
397 int result, struct smk_audit_info *ad)
398{
399}
400#endif
401
402DEFINE_MUTEX(smack_known_lock);
403
404struct hlist_head smack_known_hash[SMACK_HASH_SLOTS];
405
406/**
407 * smk_insert_entry - insert a smack label into a hash map,
408 *
409 * this function must be called under smack_known_lock
410 */
411void smk_insert_entry(struct smack_known *skp)
412{
413 unsigned int hash;
414 struct hlist_head *head;
415
416 hash = full_name_hash(skp->smk_known, strlen(skp->smk_known));
417 head = &smack_known_hash[hash & (SMACK_HASH_SLOTS - 1)];
418
419 hlist_add_head_rcu(&skp->smk_hashed, head);
420 list_add_rcu(&skp->list, &smack_known_list);
421}
422
423/**
424 * smk_find_entry - find a label on the list, return the list entry
425 * @string: a text string that might be a Smack label
426 *
427 * Returns a pointer to the entry in the label list that
428 * matches the passed string or NULL if not found.
429 */
430struct smack_known *smk_find_entry(const char *string)
431{
432 unsigned int hash;
433 struct hlist_head *head;
434 struct smack_known *skp;
435
436 hash = full_name_hash(string, strlen(string));
437 head = &smack_known_hash[hash & (SMACK_HASH_SLOTS - 1)];
438
439 hlist_for_each_entry_rcu(skp, head, smk_hashed)
440 if (strcmp(skp->smk_known, string) == 0)
441 return skp;
442
443 return NULL;
444}
445
446/**
447 * smk_parse_smack - parse smack label from a text string
448 * @string: a text string that might contain a Smack label
449 * @len: the maximum size, or zero if it is NULL terminated.
450 *
451 * Returns a pointer to the clean label or an error code.
452 */
453char *smk_parse_smack(const char *string, int len)
454{
455 char *smack;
456 int i;
457
458 if (len <= 0)
459 len = strlen(string) + 1;
460
461 /*
462 * Reserve a leading '-' as an indicator that
463 * this isn't a label, but an option to interfaces
464 * including /smack/cipso and /smack/cipso2
465 */
466 if (string[0] == '-')
467 return ERR_PTR(-EINVAL);
468
469 for (i = 0; i < len; i++)
470 if (string[i] > '~' || string[i] <= ' ' || string[i] == '/' ||
471 string[i] == '"' || string[i] == '\\' || string[i] == '\'')
472 break;
473
474 if (i == 0 || i >= SMK_LONGLABEL)
475 return ERR_PTR(-EINVAL);
476
477 smack = kzalloc(i + 1, GFP_KERNEL);
478 if (smack == NULL)
479 return ERR_PTR(-ENOMEM);
480
481 strncpy(smack, string, i);
482
483 return smack;
484}
485
486/**
487 * smk_netlbl_mls - convert a catset to netlabel mls categories
488 * @catset: the Smack categories
489 * @sap: where to put the netlabel categories
490 *
491 * Allocates and fills attr.mls
492 * Returns 0 on success, error code on failure.
493 */
494int smk_netlbl_mls(int level, char *catset, struct netlbl_lsm_secattr *sap,
495 int len)
496{
497 unsigned char *cp;
498 unsigned char m;
499 int cat;
500 int rc;
501 int byte;
502
503 sap->flags |= NETLBL_SECATTR_MLS_CAT;
504 sap->attr.mls.lvl = level;
505 sap->attr.mls.cat = NULL;
506
507 for (cat = 1, cp = catset, byte = 0; byte < len; cp++, byte++)
508 for (m = 0x80; m != 0; m >>= 1, cat++) {
509 if ((m & *cp) == 0)
510 continue;
511 rc = netlbl_catmap_setbit(&sap->attr.mls.cat,
512 cat, GFP_ATOMIC);
513 if (rc < 0) {
514 netlbl_catmap_free(sap->attr.mls.cat);
515 return rc;
516 }
517 }
518
519 return 0;
520}
521
522/**
523 * smk_import_entry - import a label, return the list entry
524 * @string: a text string that might be a Smack label
525 * @len: the maximum size, or zero if it is NULL terminated.
526 *
527 * Returns a pointer to the entry in the label list that
528 * matches the passed string, adding it if necessary,
529 * or an error code.
530 */
531struct smack_known *smk_import_entry(const char *string, int len)
532{
533 struct smack_known *skp;
534 char *smack;
535 int slen;
536 int rc;
537
538 smack = smk_parse_smack(string, len);
539 if (IS_ERR(smack))
540 return ERR_CAST(smack);
541
542 mutex_lock(&smack_known_lock);
543
544 skp = smk_find_entry(smack);
545 if (skp != NULL)
546 goto freeout;
547
548 skp = kzalloc(sizeof(*skp), GFP_KERNEL);
549 if (skp == NULL) {
550 skp = ERR_PTR(-ENOMEM);
551 goto freeout;
552 }
553
554 skp->smk_known = smack;
555 skp->smk_secid = smack_next_secid++;
556 skp->smk_netlabel.domain = skp->smk_known;
557 skp->smk_netlabel.flags =
558 NETLBL_SECATTR_DOMAIN | NETLBL_SECATTR_MLS_LVL;
559 /*
560 * If direct labeling works use it.
561 * Otherwise use mapped labeling.
562 */
563 slen = strlen(smack);
564 if (slen < SMK_CIPSOLEN)
565 rc = smk_netlbl_mls(smack_cipso_direct, skp->smk_known,
566 &skp->smk_netlabel, slen);
567 else
568 rc = smk_netlbl_mls(smack_cipso_mapped, (char *)&skp->smk_secid,
569 &skp->smk_netlabel, sizeof(skp->smk_secid));
570
571 if (rc >= 0) {
572 INIT_LIST_HEAD(&skp->smk_rules);
573 mutex_init(&skp->smk_rules_lock);
574 /*
575 * Make sure that the entry is actually
576 * filled before putting it on the list.
577 */
578 smk_insert_entry(skp);
579 goto unlockout;
580 }
581 /*
582 * smk_netlbl_mls failed.
583 */
584 kfree(skp);
585 skp = ERR_PTR(rc);
586freeout:
587 kfree(smack);
588unlockout:
589 mutex_unlock(&smack_known_lock);
590
591 return skp;
592}
593
594/**
595 * smack_from_secid - find the Smack label associated with a secid
596 * @secid: an integer that might be associated with a Smack label
597 *
598 * Returns a pointer to the appropriate Smack label entry if there is one,
599 * otherwise a pointer to the invalid Smack label.
600 */
601struct smack_known *smack_from_secid(const u32 secid)
602{
603 struct smack_known *skp;
604
605 rcu_read_lock();
606 list_for_each_entry_rcu(skp, &smack_known_list, list) {
607 if (skp->smk_secid == secid) {
608 rcu_read_unlock();
609 return skp;
610 }
611 }
612
613 /*
614 * If we got this far someone asked for the translation
615 * of a secid that is not on the list.
616 */
617 rcu_read_unlock();
618 return &smack_known_invalid;
619}
620
621/*
622 * Unless a process is running with one of these labels
623 * even having CAP_MAC_OVERRIDE isn't enough to grant
624 * privilege to violate MAC policy. If no labels are
625 * designated (the empty list case) capabilities apply to
626 * everyone.
627 */
628LIST_HEAD(smack_onlycap_list);
629DEFINE_MUTEX(smack_onlycap_lock);
630
631/*
632 * Is the task privileged and allowed to be privileged
633 * by the onlycap rule.
634 *
635 * Returns 1 if the task is allowed to be privileged, 0 if it's not.
636 */
637int smack_privileged(int cap)
638{
639 struct smack_known *skp = smk_of_current();
640 struct smack_known_list_elem *sklep;
641
642 /*
643 * All kernel tasks are privileged
644 */
645 if (unlikely(current->flags & PF_KTHREAD))
646 return 1;
647
648 if (!capable(cap))
649 return 0;
650
651 rcu_read_lock();
652 if (list_empty(&smack_onlycap_list)) {
653 rcu_read_unlock();
654 return 1;
655 }
656
657 list_for_each_entry_rcu(sklep, &smack_onlycap_list, list) {
658 if (sklep->smk_label == skp) {
659 rcu_read_unlock();
660 return 1;
661 }
662 }
663 rcu_read_unlock();
664
665 return 0;
666}
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>
14#include <linux/slab.h>
15#include <linux/fs.h>
16#include <linux/sched.h>
17#include "smack.h"
18
19struct smack_known smack_known_huh = {
20 .smk_known = "?",
21 .smk_secid = 2,
22};
23
24struct smack_known smack_known_hat = {
25 .smk_known = "^",
26 .smk_secid = 3,
27};
28
29struct smack_known smack_known_star = {
30 .smk_known = "*",
31 .smk_secid = 4,
32};
33
34struct smack_known smack_known_floor = {
35 .smk_known = "_",
36 .smk_secid = 5,
37};
38
39struct smack_known smack_known_invalid = {
40 .smk_known = "",
41 .smk_secid = 6,
42};
43
44struct smack_known smack_known_web = {
45 .smk_known = "@",
46 .smk_secid = 7,
47};
48
49LIST_HEAD(smack_known_list);
50
51/*
52 * The initial value needs to be bigger than any of the
53 * known values above.
54 */
55static u32 smack_next_secid = 10;
56
57/*
58 * what events do we log
59 * can be overwritten at run-time by /smack/logging
60 */
61int log_policy = SMACK_AUDIT_DENIED;
62
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
67 * @rule_list: the list of rules to search
68 *
69 * This function looks up the subject/object pair in the
70 * access rule list and returns the access mode. If no
71 * entry is found returns -ENOENT.
72 *
73 * NOTE:
74 *
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.
87 *
88 * Allowing write access implies allowing locking.
89 */
90int smk_access_entry(char *subject_label, char *object_label,
91 struct list_head *rule_list)
92{
93 int may = -ENOENT;
94 struct smack_rule *srp;
95
96 list_for_each_entry_rcu(srp, rule_list, list) {
97 if (srp->smk_object == object_label &&
98 srp->smk_subject->smk_known == subject_label) {
99 may = srp->smk_access;
100 break;
101 }
102 }
103
104 /*
105 * MAY_WRITE implies MAY_LOCK.
106 */
107 if ((may & MAY_WRITE) == MAY_WRITE)
108 may |= MAY_LOCK;
109 return may;
110}
111
112/**
113 * smk_access - determine if a subject has a specific access to an object
114 * @subject_known: a pointer to the subject's Smack label entry
115 * @object_label: a pointer to the object's Smack label
116 * @request: the access requested, in "MAY" format
117 * @a : a pointer to the audit data
118 *
119 * This function looks up the subject/object pair in the
120 * access rule list and returns 0 if the access is permitted,
121 * non zero otherwise.
122 *
123 * Smack labels are shared on smack_list
124 */
125int smk_access(struct smack_known *subject_known, char *object_label,
126 int request, struct smk_audit_info *a)
127{
128 int may = MAY_NOT;
129 int rc = 0;
130
131 /*
132 * Hardcoded comparisons.
133 *
134 * A star subject can't access any object.
135 */
136 if (subject_known == &smack_known_star) {
137 rc = -EACCES;
138 goto out_audit;
139 }
140 /*
141 * An internet object can be accessed by any subject.
142 * Tasks cannot be assigned the internet label.
143 * An internet subject can access any object.
144 */
145 if (object_label == smack_known_web.smk_known ||
146 subject_known == &smack_known_web)
147 goto out_audit;
148 /*
149 * A star object can be accessed by any subject.
150 */
151 if (object_label == smack_known_star.smk_known)
152 goto out_audit;
153 /*
154 * An object can be accessed in any way by a subject
155 * with the same label.
156 */
157 if (subject_known->smk_known == object_label)
158 goto out_audit;
159 /*
160 * A hat subject can read any object.
161 * A floor object can be read by any subject.
162 */
163 if ((request & MAY_ANYREAD) == request) {
164 if (object_label == smack_known_floor.smk_known)
165 goto out_audit;
166 if (subject_known == &smack_known_hat)
167 goto out_audit;
168 }
169 /*
170 * Beyond here an explicit relationship is required.
171 * If the requested access is contained in the available
172 * access (e.g. read is included in readwrite) it's
173 * good. A negative response from smk_access_entry()
174 * indicates there is no entry for this pair.
175 */
176 rcu_read_lock();
177 may = smk_access_entry(subject_known->smk_known, object_label,
178 &subject_known->smk_rules);
179 rcu_read_unlock();
180
181 if (may > 0 && (request & may) == request)
182 goto out_audit;
183
184 rc = -EACCES;
185out_audit:
186#ifdef CONFIG_AUDIT
187 if (a)
188 smack_log(subject_known->smk_known, object_label, request,
189 rc, a);
190#endif
191 return rc;
192}
193
194/**
195 * smk_curacc - determine if current has a specific access to an object
196 * @obj_label: a pointer to the object's Smack label
197 * @mode: the access requested, in "MAY" format
198 * @a : common audit data
199 *
200 * This function checks the current subject label/object label pair
201 * in the access rule list and returns 0 if the access is permitted,
202 * non zero otherwise. It allows that current may have the capability
203 * to override the rules.
204 */
205int smk_curacc(char *obj_label, u32 mode, struct smk_audit_info *a)
206{
207 struct task_smack *tsp = current_security();
208 struct smack_known *skp = smk_of_task(tsp);
209 int may;
210 int rc;
211
212 /*
213 * Check the global rule list
214 */
215 rc = smk_access(skp, obj_label, mode, NULL);
216 if (rc == 0) {
217 /*
218 * If there is an entry in the task's rule list
219 * it can further restrict access.
220 */
221 may = smk_access_entry(skp->smk_known, obj_label,
222 &tsp->smk_rules);
223 if (may < 0)
224 goto out_audit;
225 if ((mode & may) == mode)
226 goto out_audit;
227 rc = -EACCES;
228 }
229
230 /*
231 * Allow for priviliged to override policy.
232 */
233 if (rc != 0 && smack_privileged(CAP_MAC_OVERRIDE))
234 rc = 0;
235
236out_audit:
237#ifdef CONFIG_AUDIT
238 if (a)
239 smack_log(skp->smk_known, obj_label, mode, rc, a);
240#endif
241 return rc;
242}
243
244#ifdef CONFIG_AUDIT
245/**
246 * smack_str_from_perm : helper to transalate an int to a
247 * readable string
248 * @string : the string to fill
249 * @access : the int
250 *
251 */
252static inline void smack_str_from_perm(char *string, int access)
253{
254 int i = 0;
255
256 if (access & MAY_READ)
257 string[i++] = 'r';
258 if (access & MAY_WRITE)
259 string[i++] = 'w';
260 if (access & MAY_EXEC)
261 string[i++] = 'x';
262 if (access & MAY_APPEND)
263 string[i++] = 'a';
264 if (access & MAY_TRANSMUTE)
265 string[i++] = 't';
266 if (access & MAY_LOCK)
267 string[i++] = 'l';
268 string[i] = '\0';
269}
270/**
271 * smack_log_callback - SMACK specific information
272 * will be called by generic audit code
273 * @ab : the audit_buffer
274 * @a : audit_data
275 *
276 */
277static void smack_log_callback(struct audit_buffer *ab, void *a)
278{
279 struct common_audit_data *ad = a;
280 struct smack_audit_data *sad = ad->smack_audit_data;
281 audit_log_format(ab, "lsm=SMACK fn=%s action=%s",
282 ad->smack_audit_data->function,
283 sad->result ? "denied" : "granted");
284 audit_log_format(ab, " subject=");
285 audit_log_untrustedstring(ab, sad->subject);
286 audit_log_format(ab, " object=");
287 audit_log_untrustedstring(ab, sad->object);
288 audit_log_format(ab, " requested=%s", sad->request);
289}
290
291/**
292 * smack_log - Audit the granting or denial of permissions.
293 * @subject_label : smack label of the requester
294 * @object_label : smack label of the object being accessed
295 * @request: requested permissions
296 * @result: result from smk_access
297 * @a: auxiliary audit data
298 *
299 * Audit the granting or denial of permissions in accordance
300 * with the policy.
301 */
302void smack_log(char *subject_label, char *object_label, int request,
303 int result, struct smk_audit_info *ad)
304{
305 char request_buffer[SMK_NUM_ACCESS_TYPE + 1];
306 struct smack_audit_data *sad;
307 struct common_audit_data *a = &ad->a;
308
309 /* check if we have to log the current event */
310 if (result != 0 && (log_policy & SMACK_AUDIT_DENIED) == 0)
311 return;
312 if (result == 0 && (log_policy & SMACK_AUDIT_ACCEPT) == 0)
313 return;
314
315 sad = a->smack_audit_data;
316
317 if (sad->function == NULL)
318 sad->function = "unknown";
319
320 /* end preparing the audit data */
321 smack_str_from_perm(request_buffer, request);
322 sad->subject = subject_label;
323 sad->object = object_label;
324 sad->request = request_buffer;
325 sad->result = result;
326
327 common_lsm_audit(a, smack_log_callback, NULL);
328}
329#else /* #ifdef CONFIG_AUDIT */
330void smack_log(char *subject_label, char *object_label, int request,
331 int result, struct smk_audit_info *ad)
332{
333}
334#endif
335
336DEFINE_MUTEX(smack_known_lock);
337
338struct hlist_head smack_known_hash[SMACK_HASH_SLOTS];
339
340/**
341 * smk_insert_entry - insert a smack label into a hash map,
342 *
343 * this function must be called under smack_known_lock
344 */
345void smk_insert_entry(struct smack_known *skp)
346{
347 unsigned int hash;
348 struct hlist_head *head;
349
350 hash = full_name_hash(skp->smk_known, strlen(skp->smk_known));
351 head = &smack_known_hash[hash & (SMACK_HASH_SLOTS - 1)];
352
353 hlist_add_head_rcu(&skp->smk_hashed, head);
354 list_add_rcu(&skp->list, &smack_known_list);
355}
356
357/**
358 * smk_find_entry - find a label on the list, return the list entry
359 * @string: a text string that might be a Smack label
360 *
361 * Returns a pointer to the entry in the label list that
362 * matches the passed string.
363 */
364struct smack_known *smk_find_entry(const char *string)
365{
366 unsigned int hash;
367 struct hlist_head *head;
368 struct smack_known *skp;
369
370 hash = full_name_hash(string, strlen(string));
371 head = &smack_known_hash[hash & (SMACK_HASH_SLOTS - 1)];
372
373 hlist_for_each_entry_rcu(skp, head, smk_hashed)
374 if (strcmp(skp->smk_known, string) == 0)
375 return skp;
376
377 return NULL;
378}
379
380/**
381 * smk_parse_smack - parse smack label from a text string
382 * @string: a text string that might contain a Smack label
383 * @len: the maximum size, or zero if it is NULL terminated.
384 *
385 * Returns a pointer to the clean label, or NULL
386 */
387char *smk_parse_smack(const char *string, int len)
388{
389 char *smack;
390 int i;
391
392 if (len <= 0)
393 len = strlen(string) + 1;
394
395 /*
396 * Reserve a leading '-' as an indicator that
397 * this isn't a label, but an option to interfaces
398 * including /smack/cipso and /smack/cipso2
399 */
400 if (string[0] == '-')
401 return NULL;
402
403 for (i = 0; i < len; i++)
404 if (string[i] > '~' || string[i] <= ' ' || string[i] == '/' ||
405 string[i] == '"' || string[i] == '\\' || string[i] == '\'')
406 break;
407
408 if (i == 0 || i >= SMK_LONGLABEL)
409 return NULL;
410
411 smack = kzalloc(i + 1, GFP_KERNEL);
412 if (smack != NULL) {
413 strncpy(smack, string, i + 1);
414 smack[i] = '\0';
415 }
416 return smack;
417}
418
419/**
420 * smk_netlbl_mls - convert a catset to netlabel mls categories
421 * @catset: the Smack categories
422 * @sap: where to put the netlabel categories
423 *
424 * Allocates and fills attr.mls
425 * Returns 0 on success, error code on failure.
426 */
427int smk_netlbl_mls(int level, char *catset, struct netlbl_lsm_secattr *sap,
428 int len)
429{
430 unsigned char *cp;
431 unsigned char m;
432 int cat;
433 int rc;
434 int byte;
435
436 sap->flags |= NETLBL_SECATTR_MLS_CAT;
437 sap->attr.mls.lvl = level;
438 sap->attr.mls.cat = netlbl_secattr_catmap_alloc(GFP_ATOMIC);
439 if (!sap->attr.mls.cat)
440 return -ENOMEM;
441 sap->attr.mls.cat->startbit = 0;
442
443 for (cat = 1, cp = catset, byte = 0; byte < len; cp++, byte++)
444 for (m = 0x80; m != 0; m >>= 1, cat++) {
445 if ((m & *cp) == 0)
446 continue;
447 rc = netlbl_secattr_catmap_setbit(sap->attr.mls.cat,
448 cat, GFP_ATOMIC);
449 if (rc < 0) {
450 netlbl_secattr_catmap_free(sap->attr.mls.cat);
451 return rc;
452 }
453 }
454
455 return 0;
456}
457
458/**
459 * smk_import_entry - import a label, return the list entry
460 * @string: a text string that might be a Smack label
461 * @len: the maximum size, or zero if it is NULL terminated.
462 *
463 * Returns a pointer to the entry in the label list that
464 * matches the passed string, adding it if necessary.
465 */
466struct smack_known *smk_import_entry(const char *string, int len)
467{
468 struct smack_known *skp;
469 char *smack;
470 int slen;
471 int rc;
472
473 smack = smk_parse_smack(string, len);
474 if (smack == NULL)
475 return NULL;
476
477 mutex_lock(&smack_known_lock);
478
479 skp = smk_find_entry(smack);
480 if (skp != NULL)
481 goto freeout;
482
483 skp = kzalloc(sizeof(*skp), GFP_KERNEL);
484 if (skp == NULL)
485 goto freeout;
486
487 skp->smk_known = smack;
488 skp->smk_secid = smack_next_secid++;
489 skp->smk_netlabel.domain = skp->smk_known;
490 skp->smk_netlabel.flags =
491 NETLBL_SECATTR_DOMAIN | NETLBL_SECATTR_MLS_LVL;
492 /*
493 * If direct labeling works use it.
494 * Otherwise use mapped labeling.
495 */
496 slen = strlen(smack);
497 if (slen < SMK_CIPSOLEN)
498 rc = smk_netlbl_mls(smack_cipso_direct, skp->smk_known,
499 &skp->smk_netlabel, slen);
500 else
501 rc = smk_netlbl_mls(smack_cipso_mapped, (char *)&skp->smk_secid,
502 &skp->smk_netlabel, sizeof(skp->smk_secid));
503
504 if (rc >= 0) {
505 INIT_LIST_HEAD(&skp->smk_rules);
506 mutex_init(&skp->smk_rules_lock);
507 /*
508 * Make sure that the entry is actually
509 * filled before putting it on the list.
510 */
511 smk_insert_entry(skp);
512 goto unlockout;
513 }
514 /*
515 * smk_netlbl_mls failed.
516 */
517 kfree(skp);
518 skp = NULL;
519freeout:
520 kfree(smack);
521unlockout:
522 mutex_unlock(&smack_known_lock);
523
524 return skp;
525}
526
527/**
528 * smk_import - import a smack label
529 * @string: a text string that might be a Smack label
530 * @len: the maximum size, or zero if it is NULL terminated.
531 *
532 * Returns a pointer to the label in the label list that
533 * matches the passed string, adding it if necessary.
534 */
535char *smk_import(const char *string, int len)
536{
537 struct smack_known *skp;
538
539 /* labels cannot begin with a '-' */
540 if (string[0] == '-')
541 return NULL;
542 skp = smk_import_entry(string, len);
543 if (skp == NULL)
544 return NULL;
545 return skp->smk_known;
546}
547
548/**
549 * smack_from_secid - find the Smack label associated with a secid
550 * @secid: an integer that might be associated with a Smack label
551 *
552 * Returns a pointer to the appropriate Smack label entry if there is one,
553 * otherwise a pointer to the invalid Smack label.
554 */
555struct smack_known *smack_from_secid(const u32 secid)
556{
557 struct smack_known *skp;
558
559 rcu_read_lock();
560 list_for_each_entry_rcu(skp, &smack_known_list, list) {
561 if (skp->smk_secid == secid) {
562 rcu_read_unlock();
563 return skp;
564 }
565 }
566
567 /*
568 * If we got this far someone asked for the translation
569 * of a secid that is not on the list.
570 */
571 rcu_read_unlock();
572 return &smack_known_invalid;
573}
574
575/**
576 * smack_to_secid - find the secid associated with a Smack label
577 * @smack: the Smack label
578 *
579 * Returns the appropriate secid if there is one,
580 * otherwise 0
581 */
582u32 smack_to_secid(const char *smack)
583{
584 struct smack_known *skp = smk_find_entry(smack);
585
586 if (skp == NULL)
587 return 0;
588 return skp->smk_secid;
589}