Loading...
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_web = {
40 .smk_known = "@",
41 .smk_secid = 7,
42};
43
44LIST_HEAD(smack_known_list);
45
46/*
47 * The initial value needs to be bigger than any of the
48 * known values above.
49 */
50static u32 smack_next_secid = 10;
51
52/*
53 * what events do we log
54 * can be overwritten at run-time by /smack/logging
55 */
56int log_policy = SMACK_AUDIT_DENIED;
57
58/**
59 * smk_access_entry - look up matching access rule
60 * @subject_label: a pointer to the subject's Smack label
61 * @object_label: a pointer to the object's Smack label
62 * @rule_list: the list of rules to search
63 *
64 * This function looks up the subject/object pair in the
65 * access rule list and returns the access mode. If no
66 * entry is found returns -ENOENT.
67 *
68 * NOTE:
69 *
70 * Earlier versions of this function allowed for labels that
71 * were not on the label list. This was done to allow for
72 * labels to come over the network that had never been seen
73 * before on this host. Unless the receiving socket has the
74 * star label this will always result in a failure check. The
75 * star labeled socket case is now handled in the networking
76 * hooks so there is no case where the label is not on the
77 * label list. Checking to see if the address of two labels
78 * is the same is now a reliable test.
79 *
80 * Do the object check first because that is more
81 * likely to differ.
82 *
83 * Allowing write access implies allowing locking.
84 */
85int smk_access_entry(char *subject_label, char *object_label,
86 struct list_head *rule_list)
87{
88 int may = -ENOENT;
89 struct smack_rule *srp;
90
91 list_for_each_entry_rcu(srp, rule_list, list) {
92 if (srp->smk_object->smk_known == object_label &&
93 srp->smk_subject->smk_known == subject_label) {
94 may = srp->smk_access;
95 break;
96 }
97 }
98
99 /*
100 * MAY_WRITE implies MAY_LOCK.
101 */
102 if ((may & MAY_WRITE) == MAY_WRITE)
103 may |= MAY_LOCK;
104 return may;
105}
106
107/**
108 * smk_access - determine if a subject has a specific access to an object
109 * @subject: a pointer to the subject's Smack label entry
110 * @object: a pointer to the object's Smack label entry
111 * @request: the access requested, in "MAY" format
112 * @a : a pointer to the audit data
113 *
114 * This function looks up the subject/object pair in the
115 * access rule list and returns 0 if the access is permitted,
116 * non zero otherwise.
117 *
118 * Smack labels are shared on smack_list
119 */
120int smk_access(struct smack_known *subject, struct smack_known *object,
121 int request, struct smk_audit_info *a)
122{
123 int may = MAY_NOT;
124 int rc = 0;
125
126 /*
127 * Hardcoded comparisons.
128 */
129 /*
130 * A star subject can't access any object.
131 */
132 if (subject == &smack_known_star) {
133 rc = -EACCES;
134 goto out_audit;
135 }
136 /*
137 * An internet object can be accessed by any subject.
138 * Tasks cannot be assigned the internet label.
139 * An internet subject can access any object.
140 */
141 if (object == &smack_known_web || subject == &smack_known_web)
142 goto out_audit;
143 /*
144 * A star object can be accessed by any subject.
145 */
146 if (object == &smack_known_star)
147 goto out_audit;
148 /*
149 * An object can be accessed in any way by a subject
150 * with the same label.
151 */
152 if (subject->smk_known == object->smk_known)
153 goto out_audit;
154 /*
155 * A hat subject can read or lock any object.
156 * A floor object can be read or locked by any subject.
157 */
158 if ((request & MAY_ANYREAD) == request ||
159 (request & MAY_LOCK) == request) {
160 if (object == &smack_known_floor)
161 goto out_audit;
162 if (subject == &smack_known_hat)
163 goto out_audit;
164 }
165 /*
166 * Beyond here an explicit relationship is required.
167 * If the requested access is contained in the available
168 * access (e.g. read is included in readwrite) it's
169 * good. A negative response from smk_access_entry()
170 * indicates there is no entry for this pair.
171 */
172 rcu_read_lock();
173 may = smk_access_entry(subject->smk_known, object->smk_known,
174 &subject->smk_rules);
175 rcu_read_unlock();
176
177 if (may <= 0 || (request & may) != request) {
178 rc = -EACCES;
179 goto out_audit;
180 }
181#ifdef CONFIG_SECURITY_SMACK_BRINGUP
182 /*
183 * Return a positive value if using bringup mode.
184 * This allows the hooks to identify checks that
185 * succeed because of "b" rules.
186 */
187 if (may & MAY_BRINGUP)
188 rc = SMACK_BRINGUP_ALLOW;
189#endif
190
191out_audit:
192
193#ifdef CONFIG_SECURITY_SMACK_BRINGUP
194 if (rc < 0) {
195 if (object == smack_unconfined)
196 rc = SMACK_UNCONFINED_OBJECT;
197 if (subject == smack_unconfined)
198 rc = SMACK_UNCONFINED_SUBJECT;
199 }
200#endif
201
202#ifdef CONFIG_AUDIT
203 if (a)
204 smack_log(subject->smk_known, object->smk_known,
205 request, rc, a);
206#endif
207
208 return rc;
209}
210
211/**
212 * smk_tskacc - determine if a task has a specific access to an object
213 * @tsp: a pointer to the subject's task
214 * @obj_known: a pointer to the object's label entry
215 * @mode: the access requested, in "MAY" format
216 * @a : common audit data
217 *
218 * This function checks the subject task's label/object label pair
219 * in the access rule list and returns 0 if the access is permitted,
220 * non zero otherwise. It allows that the task may have the capability
221 * to override the rules.
222 */
223int smk_tskacc(struct task_smack *tsp, struct smack_known *obj_known,
224 u32 mode, struct smk_audit_info *a)
225{
226 struct smack_known *sbj_known = smk_of_task(tsp);
227 int may;
228 int rc;
229
230 /*
231 * Check the global rule list
232 */
233 rc = smk_access(sbj_known, obj_known, mode, NULL);
234 if (rc >= 0) {
235 /*
236 * If there is an entry in the task's rule list
237 * it can further restrict access.
238 */
239 may = smk_access_entry(sbj_known->smk_known,
240 obj_known->smk_known,
241 &tsp->smk_rules);
242 if (may < 0)
243 goto out_audit;
244 if ((mode & may) == mode)
245 goto out_audit;
246 rc = -EACCES;
247 }
248
249 /*
250 * Allow for priviliged to override policy.
251 */
252 if (rc != 0 && smack_privileged(CAP_MAC_OVERRIDE))
253 rc = 0;
254
255out_audit:
256#ifdef CONFIG_AUDIT
257 if (a)
258 smack_log(sbj_known->smk_known, obj_known->smk_known,
259 mode, rc, a);
260#endif
261 return rc;
262}
263
264/**
265 * smk_curacc - determine if current has a specific access to an object
266 * @obj_known: a pointer to the object's Smack label entry
267 * @mode: the access requested, in "MAY" format
268 * @a : common audit data
269 *
270 * This function checks the current subject label/object label pair
271 * in the access rule list and returns 0 if the access is permitted,
272 * non zero otherwise. It allows that current may have the capability
273 * to override the rules.
274 */
275int smk_curacc(struct smack_known *obj_known,
276 u32 mode, struct smk_audit_info *a)
277{
278 struct task_smack *tsp = current_security();
279
280 return smk_tskacc(tsp, obj_known, mode, a);
281}
282
283#ifdef CONFIG_AUDIT
284/**
285 * smack_str_from_perm : helper to transalate an int to a
286 * readable string
287 * @string : the string to fill
288 * @access : the int
289 *
290 */
291static inline void smack_str_from_perm(char *string, int access)
292{
293 int i = 0;
294
295 if (access & MAY_READ)
296 string[i++] = 'r';
297 if (access & MAY_WRITE)
298 string[i++] = 'w';
299 if (access & MAY_EXEC)
300 string[i++] = 'x';
301 if (access & MAY_APPEND)
302 string[i++] = 'a';
303 if (access & MAY_TRANSMUTE)
304 string[i++] = 't';
305 if (access & MAY_LOCK)
306 string[i++] = 'l';
307 string[i] = '\0';
308}
309/**
310 * smack_log_callback - SMACK specific information
311 * will be called by generic audit code
312 * @ab : the audit_buffer
313 * @a : audit_data
314 *
315 */
316static void smack_log_callback(struct audit_buffer *ab, void *a)
317{
318 struct common_audit_data *ad = a;
319 struct smack_audit_data *sad = ad->smack_audit_data;
320 audit_log_format(ab, "lsm=SMACK fn=%s action=%s",
321 ad->smack_audit_data->function,
322 sad->result ? "denied" : "granted");
323 audit_log_format(ab, " subject=");
324 audit_log_untrustedstring(ab, sad->subject);
325 audit_log_format(ab, " object=");
326 audit_log_untrustedstring(ab, sad->object);
327 if (sad->request[0] == '\0')
328 audit_log_format(ab, " labels_differ");
329 else
330 audit_log_format(ab, " requested=%s", sad->request);
331}
332
333/**
334 * smack_log - Audit the granting or denial of permissions.
335 * @subject_label : smack label of the requester
336 * @object_label : smack label of the object being accessed
337 * @request: requested permissions
338 * @result: result from smk_access
339 * @a: auxiliary audit data
340 *
341 * Audit the granting or denial of permissions in accordance
342 * with the policy.
343 */
344void smack_log(char *subject_label, char *object_label, int request,
345 int result, struct smk_audit_info *ad)
346{
347#ifdef CONFIG_SECURITY_SMACK_BRINGUP
348 char request_buffer[SMK_NUM_ACCESS_TYPE + 5];
349#else
350 char request_buffer[SMK_NUM_ACCESS_TYPE + 1];
351#endif
352 struct smack_audit_data *sad;
353 struct common_audit_data *a = &ad->a;
354
355 /* check if we have to log the current event */
356 if (result < 0 && (log_policy & SMACK_AUDIT_DENIED) == 0)
357 return;
358 if (result == 0 && (log_policy & SMACK_AUDIT_ACCEPT) == 0)
359 return;
360
361 sad = a->smack_audit_data;
362
363 if (sad->function == NULL)
364 sad->function = "unknown";
365
366 /* end preparing the audit data */
367 smack_str_from_perm(request_buffer, request);
368 sad->subject = subject_label;
369 sad->object = object_label;
370#ifdef CONFIG_SECURITY_SMACK_BRINGUP
371 /*
372 * The result may be positive in bringup mode.
373 * A positive result is an allow, but not for normal reasons.
374 * Mark it as successful, but don't filter it out even if
375 * the logging policy says to do so.
376 */
377 if (result == SMACK_UNCONFINED_SUBJECT)
378 strcat(request_buffer, "(US)");
379 else if (result == SMACK_UNCONFINED_OBJECT)
380 strcat(request_buffer, "(UO)");
381
382 if (result > 0)
383 result = 0;
384#endif
385 sad->request = request_buffer;
386 sad->result = result;
387
388 common_lsm_audit(a, smack_log_callback, NULL);
389}
390#else /* #ifdef CONFIG_AUDIT */
391void smack_log(char *subject_label, char *object_label, int request,
392 int result, struct smk_audit_info *ad)
393{
394}
395#endif
396
397DEFINE_MUTEX(smack_known_lock);
398
399struct hlist_head smack_known_hash[SMACK_HASH_SLOTS];
400
401/**
402 * smk_insert_entry - insert a smack label into a hash map,
403 *
404 * this function must be called under smack_known_lock
405 */
406void smk_insert_entry(struct smack_known *skp)
407{
408 unsigned int hash;
409 struct hlist_head *head;
410
411 hash = full_name_hash(NULL, skp->smk_known, strlen(skp->smk_known));
412 head = &smack_known_hash[hash & (SMACK_HASH_SLOTS - 1)];
413
414 hlist_add_head_rcu(&skp->smk_hashed, head);
415 list_add_rcu(&skp->list, &smack_known_list);
416}
417
418/**
419 * smk_find_entry - find a label on the list, return the list entry
420 * @string: a text string that might be a Smack label
421 *
422 * Returns a pointer to the entry in the label list that
423 * matches the passed string or NULL if not found.
424 */
425struct smack_known *smk_find_entry(const char *string)
426{
427 unsigned int hash;
428 struct hlist_head *head;
429 struct smack_known *skp;
430
431 hash = full_name_hash(NULL, string, strlen(string));
432 head = &smack_known_hash[hash & (SMACK_HASH_SLOTS - 1)];
433
434 hlist_for_each_entry_rcu(skp, head, smk_hashed)
435 if (strcmp(skp->smk_known, string) == 0)
436 return skp;
437
438 return NULL;
439}
440
441/**
442 * smk_parse_smack - parse smack label from a text string
443 * @string: a text string that might contain a Smack label
444 * @len: the maximum size, or zero if it is NULL terminated.
445 *
446 * Returns a pointer to the clean label or an error code.
447 */
448char *smk_parse_smack(const char *string, int len)
449{
450 char *smack;
451 int i;
452
453 if (len <= 0)
454 len = strlen(string) + 1;
455
456 /*
457 * Reserve a leading '-' as an indicator that
458 * this isn't a label, but an option to interfaces
459 * including /smack/cipso and /smack/cipso2
460 */
461 if (string[0] == '-')
462 return ERR_PTR(-EINVAL);
463
464 for (i = 0; i < len; i++)
465 if (string[i] > '~' || string[i] <= ' ' || string[i] == '/' ||
466 string[i] == '"' || string[i] == '\\' || string[i] == '\'')
467 break;
468
469 if (i == 0 || i >= SMK_LONGLABEL)
470 return ERR_PTR(-EINVAL);
471
472 smack = kzalloc(i + 1, GFP_KERNEL);
473 if (smack == NULL)
474 return ERR_PTR(-ENOMEM);
475
476 strncpy(smack, string, i);
477
478 return smack;
479}
480
481/**
482 * smk_netlbl_mls - convert a catset to netlabel mls categories
483 * @catset: the Smack categories
484 * @sap: where to put the netlabel categories
485 *
486 * Allocates and fills attr.mls
487 * Returns 0 on success, error code on failure.
488 */
489int smk_netlbl_mls(int level, char *catset, struct netlbl_lsm_secattr *sap,
490 int len)
491{
492 unsigned char *cp;
493 unsigned char m;
494 int cat;
495 int rc;
496 int byte;
497
498 sap->flags |= NETLBL_SECATTR_MLS_CAT;
499 sap->attr.mls.lvl = level;
500 sap->attr.mls.cat = NULL;
501
502 for (cat = 1, cp = catset, byte = 0; byte < len; cp++, byte++)
503 for (m = 0x80; m != 0; m >>= 1, cat++) {
504 if ((m & *cp) == 0)
505 continue;
506 rc = netlbl_catmap_setbit(&sap->attr.mls.cat,
507 cat, GFP_KERNEL);
508 if (rc < 0) {
509 netlbl_catmap_free(sap->attr.mls.cat);
510 return rc;
511 }
512 }
513
514 return 0;
515}
516
517/**
518 * smk_import_entry - import a label, return the list entry
519 * @string: a text string that might be a Smack label
520 * @len: the maximum size, or zero if it is NULL terminated.
521 *
522 * Returns a pointer to the entry in the label list that
523 * matches the passed string, adding it if necessary,
524 * or an error code.
525 */
526struct smack_known *smk_import_entry(const char *string, int len)
527{
528 struct smack_known *skp;
529 char *smack;
530 int slen;
531 int rc;
532
533 smack = smk_parse_smack(string, len);
534 if (IS_ERR(smack))
535 return ERR_CAST(smack);
536
537 mutex_lock(&smack_known_lock);
538
539 skp = smk_find_entry(smack);
540 if (skp != NULL)
541 goto freeout;
542
543 skp = kzalloc(sizeof(*skp), GFP_KERNEL);
544 if (skp == NULL) {
545 skp = ERR_PTR(-ENOMEM);
546 goto freeout;
547 }
548
549 skp->smk_known = smack;
550 skp->smk_secid = smack_next_secid++;
551 skp->smk_netlabel.domain = skp->smk_known;
552 skp->smk_netlabel.flags =
553 NETLBL_SECATTR_DOMAIN | NETLBL_SECATTR_MLS_LVL;
554 /*
555 * If direct labeling works use it.
556 * Otherwise use mapped labeling.
557 */
558 slen = strlen(smack);
559 if (slen < SMK_CIPSOLEN)
560 rc = smk_netlbl_mls(smack_cipso_direct, skp->smk_known,
561 &skp->smk_netlabel, slen);
562 else
563 rc = smk_netlbl_mls(smack_cipso_mapped, (char *)&skp->smk_secid,
564 &skp->smk_netlabel, sizeof(skp->smk_secid));
565
566 if (rc >= 0) {
567 INIT_LIST_HEAD(&skp->smk_rules);
568 mutex_init(&skp->smk_rules_lock);
569 /*
570 * Make sure that the entry is actually
571 * filled before putting it on the list.
572 */
573 smk_insert_entry(skp);
574 goto unlockout;
575 }
576 /*
577 * smk_netlbl_mls failed.
578 */
579 kfree(skp);
580 skp = ERR_PTR(rc);
581freeout:
582 kfree(smack);
583unlockout:
584 mutex_unlock(&smack_known_lock);
585
586 return skp;
587}
588
589/**
590 * smack_from_secid - find the Smack label associated with a secid
591 * @secid: an integer that might be associated with a Smack label
592 *
593 * Returns a pointer to the appropriate Smack label entry if there is one,
594 * otherwise a pointer to the invalid Smack label.
595 */
596struct smack_known *smack_from_secid(const u32 secid)
597{
598 struct smack_known *skp;
599
600 rcu_read_lock();
601 list_for_each_entry_rcu(skp, &smack_known_list, list) {
602 if (skp->smk_secid == secid) {
603 rcu_read_unlock();
604 return skp;
605 }
606 }
607
608 /*
609 * If we got this far someone asked for the translation
610 * of a secid that is not on the list.
611 */
612 rcu_read_unlock();
613 return &smack_known_huh;
614}
615
616/*
617 * Unless a process is running with one of these labels
618 * even having CAP_MAC_OVERRIDE isn't enough to grant
619 * privilege to violate MAC policy. If no labels are
620 * designated (the empty list case) capabilities apply to
621 * everyone.
622 */
623LIST_HEAD(smack_onlycap_list);
624DEFINE_MUTEX(smack_onlycap_lock);
625
626/**
627 * smack_privileged_cred - are all privilege requirements met by cred
628 * @cap: The requested capability
629 * @cred: the credential to use
630 *
631 * Is the task privileged and allowed to be privileged
632 * by the onlycap rule.
633 *
634 * Returns true if the task is allowed to be privileged, false if it's not.
635 */
636bool smack_privileged_cred(int cap, const struct cred *cred)
637{
638 struct task_smack *tsp = cred->security;
639 struct smack_known *skp = tsp->smk_task;
640 struct smack_known_list_elem *sklep;
641 int rc;
642
643 rc = cap_capable(cred, &init_user_ns, cap, SECURITY_CAP_AUDIT);
644 if (rc)
645 return false;
646
647 rcu_read_lock();
648 if (list_empty(&smack_onlycap_list)) {
649 rcu_read_unlock();
650 return true;
651 }
652
653 list_for_each_entry_rcu(sklep, &smack_onlycap_list, list) {
654 if (sklep->smk_label == skp) {
655 rcu_read_unlock();
656 return true;
657 }
658 }
659 rcu_read_unlock();
660
661 return false;
662}
663
664/**
665 * smack_privileged - are all privilege requirements met
666 * @cap: The requested capability
667 *
668 * Is the task privileged and allowed to be privileged
669 * by the onlycap rule.
670 *
671 * Returns true if the task is allowed to be privileged, false if it's not.
672 */
673bool smack_privileged(int cap)
674{
675 /*
676 * All kernel tasks are privileged
677 */
678 if (unlikely(current->flags & PF_KTHREAD))
679 return true;
680
681 return smack_privileged_cred(cap, current_cred());
682}
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_web = {
40 .smk_known = "@",
41 .smk_secid = 7,
42};
43
44LIST_HEAD(smack_known_list);
45
46/*
47 * The initial value needs to be bigger than any of the
48 * known values above.
49 */
50static u32 smack_next_secid = 10;
51
52/*
53 * what events do we log
54 * can be overwritten at run-time by /smack/logging
55 */
56int log_policy = SMACK_AUDIT_DENIED;
57
58/**
59 * smk_access_entry - look up matching access rule
60 * @subject_label: a pointer to the subject's Smack label
61 * @object_label: a pointer to the object's Smack label
62 * @rule_list: the list of rules to search
63 *
64 * This function looks up the subject/object pair in the
65 * access rule list and returns the access mode. If no
66 * entry is found returns -ENOENT.
67 *
68 * NOTE:
69 *
70 * Earlier versions of this function allowed for labels that
71 * were not on the label list. This was done to allow for
72 * labels to come over the network that had never been seen
73 * before on this host. Unless the receiving socket has the
74 * star label this will always result in a failure check. The
75 * star labeled socket case is now handled in the networking
76 * hooks so there is no case where the label is not on the
77 * label list. Checking to see if the address of two labels
78 * is the same is now a reliable test.
79 *
80 * Do the object check first because that is more
81 * likely to differ.
82 *
83 * Allowing write access implies allowing locking.
84 */
85int smk_access_entry(char *subject_label, char *object_label,
86 struct list_head *rule_list)
87{
88 int may = -ENOENT;
89 struct smack_rule *srp;
90
91 list_for_each_entry_rcu(srp, rule_list, list) {
92 if (srp->smk_object->smk_known == object_label &&
93 srp->smk_subject->smk_known == subject_label) {
94 may = srp->smk_access;
95 break;
96 }
97 }
98
99 /*
100 * MAY_WRITE implies MAY_LOCK.
101 */
102 if ((may & MAY_WRITE) == MAY_WRITE)
103 may |= MAY_LOCK;
104 return may;
105}
106
107/**
108 * smk_access - determine if a subject has a specific access to an object
109 * @subject: a pointer to the subject's Smack label entry
110 * @object: a pointer to the object's Smack label entry
111 * @request: the access requested, in "MAY" format
112 * @a : a pointer to the audit data
113 *
114 * This function looks up the subject/object pair in the
115 * access rule list and returns 0 if the access is permitted,
116 * non zero otherwise.
117 *
118 * Smack labels are shared on smack_list
119 */
120int smk_access(struct smack_known *subject, struct smack_known *object,
121 int request, struct smk_audit_info *a)
122{
123 int may = MAY_NOT;
124 int rc = 0;
125
126 /*
127 * Hardcoded comparisons.
128 */
129 /*
130 * A star subject can't access any object.
131 */
132 if (subject == &smack_known_star) {
133 rc = -EACCES;
134 goto out_audit;
135 }
136 /*
137 * An internet object can be accessed by any subject.
138 * Tasks cannot be assigned the internet label.
139 * An internet subject can access any object.
140 */
141 if (object == &smack_known_web || subject == &smack_known_web)
142 goto out_audit;
143 /*
144 * A star object can be accessed by any subject.
145 */
146 if (object == &smack_known_star)
147 goto out_audit;
148 /*
149 * An object can be accessed in any way by a subject
150 * with the same label.
151 */
152 if (subject->smk_known == object->smk_known)
153 goto out_audit;
154 /*
155 * A hat subject can read or lock any object.
156 * A floor object can be read or locked by any subject.
157 */
158 if ((request & MAY_ANYREAD) == request ||
159 (request & MAY_LOCK) == request) {
160 if (object == &smack_known_floor)
161 goto out_audit;
162 if (subject == &smack_known_hat)
163 goto out_audit;
164 }
165 /*
166 * Beyond here an explicit relationship is required.
167 * If the requested access is contained in the available
168 * access (e.g. read is included in readwrite) it's
169 * good. A negative response from smk_access_entry()
170 * indicates there is no entry for this pair.
171 */
172 rcu_read_lock();
173 may = smk_access_entry(subject->smk_known, object->smk_known,
174 &subject->smk_rules);
175 rcu_read_unlock();
176
177 if (may <= 0 || (request & may) != request) {
178 rc = -EACCES;
179 goto out_audit;
180 }
181#ifdef CONFIG_SECURITY_SMACK_BRINGUP
182 /*
183 * Return a positive value if using bringup mode.
184 * This allows the hooks to identify checks that
185 * succeed because of "b" rules.
186 */
187 if (may & MAY_BRINGUP)
188 rc = SMACK_BRINGUP_ALLOW;
189#endif
190
191out_audit:
192
193#ifdef CONFIG_SECURITY_SMACK_BRINGUP
194 if (rc < 0) {
195 if (object == smack_unconfined)
196 rc = SMACK_UNCONFINED_OBJECT;
197 if (subject == smack_unconfined)
198 rc = SMACK_UNCONFINED_SUBJECT;
199 }
200#endif
201
202#ifdef CONFIG_AUDIT
203 if (a)
204 smack_log(subject->smk_known, object->smk_known,
205 request, rc, a);
206#endif
207
208 return rc;
209}
210
211/**
212 * smk_tskacc - determine if a task has a specific access to an object
213 * @tsp: a pointer to the subject's task
214 * @obj_known: a pointer to the object's label entry
215 * @mode: the access requested, in "MAY" format
216 * @a : common audit data
217 *
218 * This function checks the subject task's label/object label pair
219 * in the access rule list and returns 0 if the access is permitted,
220 * non zero otherwise. It allows that the task may have the capability
221 * to override the rules.
222 */
223int smk_tskacc(struct task_smack *tsp, struct smack_known *obj_known,
224 u32 mode, struct smk_audit_info *a)
225{
226 struct smack_known *sbj_known = smk_of_task(tsp);
227 int may;
228 int rc;
229
230 /*
231 * Check the global rule list
232 */
233 rc = smk_access(sbj_known, obj_known, mode, NULL);
234 if (rc >= 0) {
235 /*
236 * If there is an entry in the task's rule list
237 * it can further restrict access.
238 */
239 may = smk_access_entry(sbj_known->smk_known,
240 obj_known->smk_known,
241 &tsp->smk_rules);
242 if (may < 0)
243 goto out_audit;
244 if ((mode & may) == mode)
245 goto out_audit;
246 rc = -EACCES;
247 }
248
249 /*
250 * Allow for priviliged to override policy.
251 */
252 if (rc != 0 && smack_privileged(CAP_MAC_OVERRIDE))
253 rc = 0;
254
255out_audit:
256#ifdef CONFIG_AUDIT
257 if (a)
258 smack_log(sbj_known->smk_known, obj_known->smk_known,
259 mode, rc, a);
260#endif
261 return rc;
262}
263
264/**
265 * smk_curacc - determine if current has a specific access to an object
266 * @obj_known: a pointer to the object's Smack label entry
267 * @mode: the access requested, in "MAY" format
268 * @a : common audit data
269 *
270 * This function checks the current subject label/object label pair
271 * in the access rule list and returns 0 if the access is permitted,
272 * non zero otherwise. It allows that current may have the capability
273 * to override the rules.
274 */
275int smk_curacc(struct smack_known *obj_known,
276 u32 mode, struct smk_audit_info *a)
277{
278 struct task_smack *tsp = current_security();
279
280 return smk_tskacc(tsp, obj_known, mode, a);
281}
282
283#ifdef CONFIG_AUDIT
284/**
285 * smack_str_from_perm : helper to transalate an int to a
286 * readable string
287 * @string : the string to fill
288 * @access : the int
289 *
290 */
291static inline void smack_str_from_perm(char *string, int access)
292{
293 int i = 0;
294
295 if (access & MAY_READ)
296 string[i++] = 'r';
297 if (access & MAY_WRITE)
298 string[i++] = 'w';
299 if (access & MAY_EXEC)
300 string[i++] = 'x';
301 if (access & MAY_APPEND)
302 string[i++] = 'a';
303 if (access & MAY_TRANSMUTE)
304 string[i++] = 't';
305 if (access & MAY_LOCK)
306 string[i++] = 'l';
307 string[i] = '\0';
308}
309/**
310 * smack_log_callback - SMACK specific information
311 * will be called by generic audit code
312 * @ab : the audit_buffer
313 * @a : audit_data
314 *
315 */
316static void smack_log_callback(struct audit_buffer *ab, void *a)
317{
318 struct common_audit_data *ad = a;
319 struct smack_audit_data *sad = ad->smack_audit_data;
320 audit_log_format(ab, "lsm=SMACK fn=%s action=%s",
321 ad->smack_audit_data->function,
322 sad->result ? "denied" : "granted");
323 audit_log_format(ab, " subject=");
324 audit_log_untrustedstring(ab, sad->subject);
325 audit_log_format(ab, " object=");
326 audit_log_untrustedstring(ab, sad->object);
327 if (sad->request[0] == '\0')
328 audit_log_format(ab, " labels_differ");
329 else
330 audit_log_format(ab, " requested=%s", sad->request);
331}
332
333/**
334 * smack_log - Audit the granting or denial of permissions.
335 * @subject_label : smack label of the requester
336 * @object_label : smack label of the object being accessed
337 * @request: requested permissions
338 * @result: result from smk_access
339 * @a: auxiliary audit data
340 *
341 * Audit the granting or denial of permissions in accordance
342 * with the policy.
343 */
344void smack_log(char *subject_label, char *object_label, int request,
345 int result, struct smk_audit_info *ad)
346{
347#ifdef CONFIG_SECURITY_SMACK_BRINGUP
348 char request_buffer[SMK_NUM_ACCESS_TYPE + 5];
349#else
350 char request_buffer[SMK_NUM_ACCESS_TYPE + 1];
351#endif
352 struct smack_audit_data *sad;
353 struct common_audit_data *a = &ad->a;
354
355 /* check if we have to log the current event */
356 if (result < 0 && (log_policy & SMACK_AUDIT_DENIED) == 0)
357 return;
358 if (result == 0 && (log_policy & SMACK_AUDIT_ACCEPT) == 0)
359 return;
360
361 sad = a->smack_audit_data;
362
363 if (sad->function == NULL)
364 sad->function = "unknown";
365
366 /* end preparing the audit data */
367 smack_str_from_perm(request_buffer, request);
368 sad->subject = subject_label;
369 sad->object = object_label;
370#ifdef CONFIG_SECURITY_SMACK_BRINGUP
371 /*
372 * The result may be positive in bringup mode.
373 * A positive result is an allow, but not for normal reasons.
374 * Mark it as successful, but don't filter it out even if
375 * the logging policy says to do so.
376 */
377 if (result == SMACK_UNCONFINED_SUBJECT)
378 strcat(request_buffer, "(US)");
379 else if (result == SMACK_UNCONFINED_OBJECT)
380 strcat(request_buffer, "(UO)");
381
382 if (result > 0)
383 result = 0;
384#endif
385 sad->request = request_buffer;
386 sad->result = result;
387
388 common_lsm_audit(a, smack_log_callback, NULL);
389}
390#else /* #ifdef CONFIG_AUDIT */
391void smack_log(char *subject_label, char *object_label, int request,
392 int result, struct smk_audit_info *ad)
393{
394}
395#endif
396
397DEFINE_MUTEX(smack_known_lock);
398
399struct hlist_head smack_known_hash[SMACK_HASH_SLOTS];
400
401/**
402 * smk_insert_entry - insert a smack label into a hash map,
403 *
404 * this function must be called under smack_known_lock
405 */
406void smk_insert_entry(struct smack_known *skp)
407{
408 unsigned int hash;
409 struct hlist_head *head;
410
411 hash = full_name_hash(NULL, skp->smk_known, strlen(skp->smk_known));
412 head = &smack_known_hash[hash & (SMACK_HASH_SLOTS - 1)];
413
414 hlist_add_head_rcu(&skp->smk_hashed, head);
415 list_add_rcu(&skp->list, &smack_known_list);
416}
417
418/**
419 * smk_find_entry - find a label on the list, return the list entry
420 * @string: a text string that might be a Smack label
421 *
422 * Returns a pointer to the entry in the label list that
423 * matches the passed string or NULL if not found.
424 */
425struct smack_known *smk_find_entry(const char *string)
426{
427 unsigned int hash;
428 struct hlist_head *head;
429 struct smack_known *skp;
430
431 hash = full_name_hash(NULL, string, strlen(string));
432 head = &smack_known_hash[hash & (SMACK_HASH_SLOTS - 1)];
433
434 hlist_for_each_entry_rcu(skp, head, smk_hashed)
435 if (strcmp(skp->smk_known, string) == 0)
436 return skp;
437
438 return NULL;
439}
440
441/**
442 * smk_parse_smack - parse smack label from a text string
443 * @string: a text string that might contain a Smack label
444 * @len: the maximum size, or zero if it is NULL terminated.
445 *
446 * Returns a pointer to the clean label or an error code.
447 */
448char *smk_parse_smack(const char *string, int len)
449{
450 char *smack;
451 int i;
452
453 if (len <= 0)
454 len = strlen(string) + 1;
455
456 /*
457 * Reserve a leading '-' as an indicator that
458 * this isn't a label, but an option to interfaces
459 * including /smack/cipso and /smack/cipso2
460 */
461 if (string[0] == '-')
462 return ERR_PTR(-EINVAL);
463
464 for (i = 0; i < len; i++)
465 if (string[i] > '~' || string[i] <= ' ' || string[i] == '/' ||
466 string[i] == '"' || string[i] == '\\' || string[i] == '\'')
467 break;
468
469 if (i == 0 || i >= SMK_LONGLABEL)
470 return ERR_PTR(-EINVAL);
471
472 smack = kzalloc(i + 1, GFP_KERNEL);
473 if (smack == NULL)
474 return ERR_PTR(-ENOMEM);
475
476 strncpy(smack, string, i);
477
478 return smack;
479}
480
481/**
482 * smk_netlbl_mls - convert a catset to netlabel mls categories
483 * @catset: the Smack categories
484 * @sap: where to put the netlabel categories
485 *
486 * Allocates and fills attr.mls
487 * Returns 0 on success, error code on failure.
488 */
489int smk_netlbl_mls(int level, char *catset, struct netlbl_lsm_secattr *sap,
490 int len)
491{
492 unsigned char *cp;
493 unsigned char m;
494 int cat;
495 int rc;
496 int byte;
497
498 sap->flags |= NETLBL_SECATTR_MLS_CAT;
499 sap->attr.mls.lvl = level;
500 sap->attr.mls.cat = NULL;
501
502 for (cat = 1, cp = catset, byte = 0; byte < len; cp++, byte++)
503 for (m = 0x80; m != 0; m >>= 1, cat++) {
504 if ((m & *cp) == 0)
505 continue;
506 rc = netlbl_catmap_setbit(&sap->attr.mls.cat,
507 cat, GFP_ATOMIC);
508 if (rc < 0) {
509 netlbl_catmap_free(sap->attr.mls.cat);
510 return rc;
511 }
512 }
513
514 return 0;
515}
516
517/**
518 * smk_import_entry - import a label, return the list entry
519 * @string: a text string that might be a Smack label
520 * @len: the maximum size, or zero if it is NULL terminated.
521 *
522 * Returns a pointer to the entry in the label list that
523 * matches the passed string, adding it if necessary,
524 * or an error code.
525 */
526struct smack_known *smk_import_entry(const char *string, int len)
527{
528 struct smack_known *skp;
529 char *smack;
530 int slen;
531 int rc;
532
533 smack = smk_parse_smack(string, len);
534 if (IS_ERR(smack))
535 return ERR_CAST(smack);
536
537 mutex_lock(&smack_known_lock);
538
539 skp = smk_find_entry(smack);
540 if (skp != NULL)
541 goto freeout;
542
543 skp = kzalloc(sizeof(*skp), GFP_KERNEL);
544 if (skp == NULL) {
545 skp = ERR_PTR(-ENOMEM);
546 goto freeout;
547 }
548
549 skp->smk_known = smack;
550 skp->smk_secid = smack_next_secid++;
551 skp->smk_netlabel.domain = skp->smk_known;
552 skp->smk_netlabel.flags =
553 NETLBL_SECATTR_DOMAIN | NETLBL_SECATTR_MLS_LVL;
554 /*
555 * If direct labeling works use it.
556 * Otherwise use mapped labeling.
557 */
558 slen = strlen(smack);
559 if (slen < SMK_CIPSOLEN)
560 rc = smk_netlbl_mls(smack_cipso_direct, skp->smk_known,
561 &skp->smk_netlabel, slen);
562 else
563 rc = smk_netlbl_mls(smack_cipso_mapped, (char *)&skp->smk_secid,
564 &skp->smk_netlabel, sizeof(skp->smk_secid));
565
566 if (rc >= 0) {
567 INIT_LIST_HEAD(&skp->smk_rules);
568 mutex_init(&skp->smk_rules_lock);
569 /*
570 * Make sure that the entry is actually
571 * filled before putting it on the list.
572 */
573 smk_insert_entry(skp);
574 goto unlockout;
575 }
576 /*
577 * smk_netlbl_mls failed.
578 */
579 kfree(skp);
580 skp = ERR_PTR(rc);
581freeout:
582 kfree(smack);
583unlockout:
584 mutex_unlock(&smack_known_lock);
585
586 return skp;
587}
588
589/**
590 * smack_from_secid - find the Smack label associated with a secid
591 * @secid: an integer that might be associated with a Smack label
592 *
593 * Returns a pointer to the appropriate Smack label entry if there is one,
594 * otherwise a pointer to the invalid Smack label.
595 */
596struct smack_known *smack_from_secid(const u32 secid)
597{
598 struct smack_known *skp;
599
600 rcu_read_lock();
601 list_for_each_entry_rcu(skp, &smack_known_list, list) {
602 if (skp->smk_secid == secid) {
603 rcu_read_unlock();
604 return skp;
605 }
606 }
607
608 /*
609 * If we got this far someone asked for the translation
610 * of a secid that is not on the list.
611 */
612 rcu_read_unlock();
613 return &smack_known_huh;
614}
615
616/*
617 * Unless a process is running with one of these labels
618 * even having CAP_MAC_OVERRIDE isn't enough to grant
619 * privilege to violate MAC policy. If no labels are
620 * designated (the empty list case) capabilities apply to
621 * everyone.
622 */
623LIST_HEAD(smack_onlycap_list);
624DEFINE_MUTEX(smack_onlycap_lock);
625
626/*
627 * Is the task privileged and allowed to be privileged
628 * by the onlycap rule.
629 *
630 * Returns 1 if the task is allowed to be privileged, 0 if it's not.
631 */
632int smack_privileged(int cap)
633{
634 struct smack_known *skp = smk_of_current();
635 struct smack_known_list_elem *sklep;
636
637 /*
638 * All kernel tasks are privileged
639 */
640 if (unlikely(current->flags & PF_KTHREAD))
641 return 1;
642
643 if (!capable(cap))
644 return 0;
645
646 rcu_read_lock();
647 if (list_empty(&smack_onlycap_list)) {
648 rcu_read_unlock();
649 return 1;
650 }
651
652 list_for_each_entry_rcu(sklep, &smack_onlycap_list, list) {
653 if (sklep->smk_label == skp) {
654 rcu_read_unlock();
655 return 1;
656 }
657 }
658 rcu_read_unlock();
659
660 return 0;
661}