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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright (C) 2007 Casey Schaufler <casey@schaufler-ca.com>
4 *
5 * Author:
6 * Casey Schaufler <casey@schaufler-ca.com>
7 */
8
9#include <linux/types.h>
10#include <linux/slab.h>
11#include <linux/fs.h>
12#include <linux/sched.h>
13#include "smack.h"
14
15struct smack_known smack_known_huh = {
16 .smk_known = "?",
17 .smk_secid = 2,
18};
19
20struct smack_known smack_known_hat = {
21 .smk_known = "^",
22 .smk_secid = 3,
23};
24
25struct smack_known smack_known_star = {
26 .smk_known = "*",
27 .smk_secid = 4,
28};
29
30struct smack_known smack_known_floor = {
31 .smk_known = "_",
32 .smk_secid = 5,
33};
34
35struct smack_known smack_known_web = {
36 .smk_known = "@",
37 .smk_secid = 7,
38};
39
40LIST_HEAD(smack_known_list);
41
42/*
43 * The initial value needs to be bigger than any of the
44 * known values above.
45 */
46static u32 smack_next_secid = 10;
47
48/*
49 * what events do we log
50 * can be overwritten at run-time by /smack/logging
51 */
52int log_policy = SMACK_AUDIT_DENIED;
53
54/**
55 * smk_access_entry - look up matching access rule
56 * @subject_label: a pointer to the subject's Smack label
57 * @object_label: a pointer to the object's Smack label
58 * @rule_list: the list of rules to search
59 *
60 * This function looks up the subject/object pair in the
61 * access rule list and returns the access mode. If no
62 * entry is found returns -ENOENT.
63 *
64 * NOTE:
65 *
66 * Earlier versions of this function allowed for labels that
67 * were not on the label list. This was done to allow for
68 * labels to come over the network that had never been seen
69 * before on this host. Unless the receiving socket has the
70 * star label this will always result in a failure check. The
71 * star labeled socket case is now handled in the networking
72 * hooks so there is no case where the label is not on the
73 * label list. Checking to see if the address of two labels
74 * is the same is now a reliable test.
75 *
76 * Do the object check first because that is more
77 * likely to differ.
78 *
79 * Allowing write access implies allowing locking.
80 */
81int smk_access_entry(char *subject_label, char *object_label,
82 struct list_head *rule_list)
83{
84 struct smack_rule *srp;
85
86 list_for_each_entry_rcu(srp, rule_list, list) {
87 if (srp->smk_object->smk_known == object_label &&
88 srp->smk_subject->smk_known == subject_label) {
89 int may = srp->smk_access;
90 /*
91 * MAY_WRITE implies MAY_LOCK.
92 */
93 if ((may & MAY_WRITE) == MAY_WRITE)
94 may |= MAY_LOCK;
95 return may;
96 }
97 }
98
99 return -ENOENT;
100}
101
102/**
103 * smk_access - determine if a subject has a specific access to an object
104 * @subject: a pointer to the subject's Smack label entry
105 * @object: a pointer to the object's Smack label entry
106 * @request: the access requested, in "MAY" format
107 * @a : a pointer to the audit data
108 *
109 * This function looks up the subject/object pair in the
110 * access rule list and returns 0 if the access is permitted,
111 * non zero otherwise.
112 *
113 * Smack labels are shared on smack_list
114 */
115int smk_access(struct smack_known *subject, struct smack_known *object,
116 int request, struct smk_audit_info *a)
117{
118 int may = MAY_NOT;
119 int rc = 0;
120
121 /*
122 * Hardcoded comparisons.
123 */
124 /*
125 * A star subject can't access any object.
126 */
127 if (subject == &smack_known_star) {
128 rc = -EACCES;
129 goto out_audit;
130 }
131 /*
132 * An internet object can be accessed by any subject.
133 * Tasks cannot be assigned the internet label.
134 * An internet subject can access any object.
135 */
136 if (object == &smack_known_web || subject == &smack_known_web)
137 goto out_audit;
138 /*
139 * A star object can be accessed by any subject.
140 */
141 if (object == &smack_known_star)
142 goto out_audit;
143 /*
144 * An object can be accessed in any way by a subject
145 * with the same label.
146 */
147 if (subject->smk_known == object->smk_known)
148 goto out_audit;
149 /*
150 * A hat subject can read or lock any object.
151 * A floor object can be read or locked by any subject.
152 */
153 if ((request & MAY_ANYREAD) == request ||
154 (request & MAY_LOCK) == request) {
155 if (object == &smack_known_floor)
156 goto out_audit;
157 if (subject == &smack_known_hat)
158 goto out_audit;
159 }
160 /*
161 * Beyond here an explicit relationship is required.
162 * If the requested access is contained in the available
163 * access (e.g. read is included in readwrite) it's
164 * good. A negative response from smk_access_entry()
165 * indicates there is no entry for this pair.
166 */
167 rcu_read_lock();
168 may = smk_access_entry(subject->smk_known, object->smk_known,
169 &subject->smk_rules);
170 rcu_read_unlock();
171
172 if (may <= 0 || (request & may) != request) {
173 rc = -EACCES;
174 goto out_audit;
175 }
176#ifdef CONFIG_SECURITY_SMACK_BRINGUP
177 /*
178 * Return a positive value if using bringup mode.
179 * This allows the hooks to identify checks that
180 * succeed because of "b" rules.
181 */
182 if (may & MAY_BRINGUP)
183 rc = SMACK_BRINGUP_ALLOW;
184#endif
185
186out_audit:
187
188#ifdef CONFIG_SECURITY_SMACK_BRINGUP
189 if (rc < 0) {
190 if (object == smack_unconfined)
191 rc = SMACK_UNCONFINED_OBJECT;
192 if (subject == smack_unconfined)
193 rc = SMACK_UNCONFINED_SUBJECT;
194 }
195#endif
196
197#ifdef CONFIG_AUDIT
198 if (a)
199 smack_log(subject->smk_known, object->smk_known,
200 request, rc, a);
201#endif
202
203 return rc;
204}
205
206/**
207 * smk_tskacc - determine if a task has a specific access to an object
208 * @tsp: a pointer to the subject's task
209 * @obj_known: a pointer to the object's label entry
210 * @mode: the access requested, in "MAY" format
211 * @a : common audit data
212 *
213 * This function checks the subject task's label/object label pair
214 * in the access rule list and returns 0 if the access is permitted,
215 * non zero otherwise. It allows that the task may have the capability
216 * to override the rules.
217 */
218int smk_tskacc(struct task_smack *tsp, struct smack_known *obj_known,
219 u32 mode, struct smk_audit_info *a)
220{
221 struct smack_known *sbj_known = smk_of_task(tsp);
222 int may;
223 int rc;
224
225 /*
226 * Check the global rule list
227 */
228 rc = smk_access(sbj_known, obj_known, mode, NULL);
229 if (rc >= 0) {
230 /*
231 * If there is an entry in the task's rule list
232 * it can further restrict access.
233 */
234 may = smk_access_entry(sbj_known->smk_known,
235 obj_known->smk_known,
236 &tsp->smk_rules);
237 if (may < 0)
238 goto out_audit;
239 if ((mode & may) == mode)
240 goto out_audit;
241 rc = -EACCES;
242 }
243
244 /*
245 * Allow for priviliged to override policy.
246 */
247 if (rc != 0 && smack_privileged(CAP_MAC_OVERRIDE))
248 rc = 0;
249
250out_audit:
251#ifdef CONFIG_AUDIT
252 if (a)
253 smack_log(sbj_known->smk_known, obj_known->smk_known,
254 mode, rc, a);
255#endif
256 return rc;
257}
258
259/**
260 * smk_curacc - determine if current has a specific access to an object
261 * @obj_known: a pointer to the object's Smack label entry
262 * @mode: the access requested, in "MAY" format
263 * @a : common audit data
264 *
265 * This function checks the current subject label/object label pair
266 * in the access rule list and returns 0 if the access is permitted,
267 * non zero otherwise. It allows that current may have the capability
268 * to override the rules.
269 */
270int smk_curacc(struct smack_known *obj_known,
271 u32 mode, struct smk_audit_info *a)
272{
273 struct task_smack *tsp = smack_cred(current_cred());
274
275 return smk_tskacc(tsp, obj_known, mode, a);
276}
277
278#ifdef CONFIG_AUDIT
279/**
280 * smack_str_from_perm : helper to transalate an int to a
281 * readable string
282 * @string : the string to fill
283 * @access : the int
284 *
285 */
286static inline void smack_str_from_perm(char *string, int access)
287{
288 int i = 0;
289
290 if (access & MAY_READ)
291 string[i++] = 'r';
292 if (access & MAY_WRITE)
293 string[i++] = 'w';
294 if (access & MAY_EXEC)
295 string[i++] = 'x';
296 if (access & MAY_APPEND)
297 string[i++] = 'a';
298 if (access & MAY_TRANSMUTE)
299 string[i++] = 't';
300 if (access & MAY_LOCK)
301 string[i++] = 'l';
302 string[i] = '\0';
303}
304/**
305 * smack_log_callback - SMACK specific information
306 * will be called by generic audit code
307 * @ab : the audit_buffer
308 * @a : audit_data
309 *
310 */
311static void smack_log_callback(struct audit_buffer *ab, void *a)
312{
313 struct common_audit_data *ad = a;
314 struct smack_audit_data *sad = ad->smack_audit_data;
315 audit_log_format(ab, "lsm=SMACK fn=%s action=%s",
316 ad->smack_audit_data->function,
317 sad->result ? "denied" : "granted");
318 audit_log_format(ab, " subject=");
319 audit_log_untrustedstring(ab, sad->subject);
320 audit_log_format(ab, " object=");
321 audit_log_untrustedstring(ab, sad->object);
322 if (sad->request[0] == '\0')
323 audit_log_format(ab, " labels_differ");
324 else
325 audit_log_format(ab, " requested=%s", sad->request);
326}
327
328/**
329 * smack_log - Audit the granting or denial of permissions.
330 * @subject_label : smack label of the requester
331 * @object_label : smack label of the object being accessed
332 * @request: requested permissions
333 * @result: result from smk_access
334 * @ad: auxiliary audit data
335 *
336 * Audit the granting or denial of permissions in accordance
337 * with the policy.
338 */
339void smack_log(char *subject_label, char *object_label, int request,
340 int result, struct smk_audit_info *ad)
341{
342#ifdef CONFIG_SECURITY_SMACK_BRINGUP
343 char request_buffer[SMK_NUM_ACCESS_TYPE + 5];
344#else
345 char request_buffer[SMK_NUM_ACCESS_TYPE + 1];
346#endif
347 struct smack_audit_data *sad;
348 struct common_audit_data *a = &ad->a;
349
350 /* check if we have to log the current event */
351 if (result < 0 && (log_policy & SMACK_AUDIT_DENIED) == 0)
352 return;
353 if (result == 0 && (log_policy & SMACK_AUDIT_ACCEPT) == 0)
354 return;
355
356 sad = a->smack_audit_data;
357
358 if (sad->function == NULL)
359 sad->function = "unknown";
360
361 /* end preparing the audit data */
362 smack_str_from_perm(request_buffer, request);
363 sad->subject = subject_label;
364 sad->object = object_label;
365#ifdef CONFIG_SECURITY_SMACK_BRINGUP
366 /*
367 * The result may be positive in bringup mode.
368 * A positive result is an allow, but not for normal reasons.
369 * Mark it as successful, but don't filter it out even if
370 * the logging policy says to do so.
371 */
372 if (result == SMACK_UNCONFINED_SUBJECT)
373 strcat(request_buffer, "(US)");
374 else if (result == SMACK_UNCONFINED_OBJECT)
375 strcat(request_buffer, "(UO)");
376
377 if (result > 0)
378 result = 0;
379#endif
380 sad->request = request_buffer;
381 sad->result = result;
382
383 common_lsm_audit(a, smack_log_callback, NULL);
384}
385#else /* #ifdef CONFIG_AUDIT */
386void smack_log(char *subject_label, char *object_label, int request,
387 int result, struct smk_audit_info *ad)
388{
389}
390#endif
391
392DEFINE_MUTEX(smack_known_lock);
393
394struct hlist_head smack_known_hash[SMACK_HASH_SLOTS];
395
396/**
397 * smk_insert_entry - insert a smack label into a hash map,
398 * @skp: smack label
399 *
400 * this function must be called under smack_known_lock
401 */
402void smk_insert_entry(struct smack_known *skp)
403{
404 unsigned int hash;
405 struct hlist_head *head;
406
407 hash = full_name_hash(NULL, skp->smk_known, strlen(skp->smk_known));
408 head = &smack_known_hash[hash & (SMACK_HASH_SLOTS - 1)];
409
410 hlist_add_head_rcu(&skp->smk_hashed, head);
411 list_add_rcu(&skp->list, &smack_known_list);
412}
413
414/**
415 * smk_find_entry - find a label on the list, return the list entry
416 * @string: a text string that might be a Smack label
417 *
418 * Returns a pointer to the entry in the label list that
419 * matches the passed string or NULL if not found.
420 */
421struct smack_known *smk_find_entry(const char *string)
422{
423 unsigned int hash;
424 struct hlist_head *head;
425 struct smack_known *skp;
426
427 hash = full_name_hash(NULL, string, strlen(string));
428 head = &smack_known_hash[hash & (SMACK_HASH_SLOTS - 1)];
429
430 hlist_for_each_entry_rcu(skp, head, smk_hashed)
431 if (strcmp(skp->smk_known, string) == 0)
432 return skp;
433
434 return NULL;
435}
436
437/**
438 * smk_parse_smack - parse smack label from a text string
439 * @string: a text string that might contain a Smack label
440 * @len: the maximum size, or zero if it is NULL terminated.
441 *
442 * Returns a pointer to the clean label or an error code.
443 */
444char *smk_parse_smack(const char *string, int len)
445{
446 char *smack;
447 int i;
448
449 if (len <= 0)
450 len = strlen(string) + 1;
451
452 /*
453 * Reserve a leading '-' as an indicator that
454 * this isn't a label, but an option to interfaces
455 * including /smack/cipso and /smack/cipso2
456 */
457 if (string[0] == '-')
458 return ERR_PTR(-EINVAL);
459
460 for (i = 0; i < len; i++)
461 if (string[i] > '~' || string[i] <= ' ' || string[i] == '/' ||
462 string[i] == '"' || string[i] == '\\' || string[i] == '\'')
463 break;
464
465 if (i == 0 || i >= SMK_LONGLABEL)
466 return ERR_PTR(-EINVAL);
467
468 smack = kzalloc(i + 1, GFP_NOFS);
469 if (smack == NULL)
470 return ERR_PTR(-ENOMEM);
471
472 strncpy(smack, string, i);
473
474 return smack;
475}
476
477/**
478 * smk_netlbl_mls - convert a catset to netlabel mls categories
479 * @level: MLS sensitivity level
480 * @catset: the Smack categories
481 * @sap: where to put the netlabel categories
482 * @len: number of bytes for the levels in a CIPSO IP option
483 *
484 * Allocates and fills attr.mls
485 * Returns 0 on success, error code on failure.
486 */
487int smk_netlbl_mls(int level, char *catset, struct netlbl_lsm_secattr *sap,
488 int len)
489{
490 unsigned char *cp;
491 unsigned char m;
492 int cat;
493 int rc;
494 int byte;
495
496 sap->flags |= NETLBL_SECATTR_MLS_CAT;
497 sap->attr.mls.lvl = level;
498 sap->attr.mls.cat = NULL;
499
500 for (cat = 1, cp = catset, byte = 0; byte < len; cp++, byte++)
501 for (m = 0x80; m != 0; m >>= 1, cat++) {
502 if ((m & *cp) == 0)
503 continue;
504 rc = netlbl_catmap_setbit(&sap->attr.mls.cat,
505 cat, GFP_NOFS);
506 if (rc < 0) {
507 netlbl_catmap_free(sap->attr.mls.cat);
508 return rc;
509 }
510 }
511
512 return 0;
513}
514
515/**
516 * smack_populate_secattr - fill in the smack_known netlabel information
517 * @skp: pointer to the structure to fill
518 *
519 * Populate the netlabel secattr structure for a Smack label.
520 *
521 * Returns 0 unless creating the category mapping fails
522 */
523int smack_populate_secattr(struct smack_known *skp)
524{
525 int slen;
526
527 skp->smk_netlabel.attr.secid = skp->smk_secid;
528 skp->smk_netlabel.domain = skp->smk_known;
529 skp->smk_netlabel.cache = netlbl_secattr_cache_alloc(GFP_ATOMIC);
530 if (skp->smk_netlabel.cache != NULL) {
531 skp->smk_netlabel.flags |= NETLBL_SECATTR_CACHE;
532 skp->smk_netlabel.cache->free = NULL;
533 skp->smk_netlabel.cache->data = skp;
534 }
535 skp->smk_netlabel.flags |= NETLBL_SECATTR_SECID |
536 NETLBL_SECATTR_MLS_LVL |
537 NETLBL_SECATTR_DOMAIN;
538 /*
539 * If direct labeling works use it.
540 * Otherwise use mapped labeling.
541 */
542 slen = strlen(skp->smk_known);
543 if (slen < SMK_CIPSOLEN)
544 return smk_netlbl_mls(smack_cipso_direct, skp->smk_known,
545 &skp->smk_netlabel, slen);
546
547 return smk_netlbl_mls(smack_cipso_mapped, (char *)&skp->smk_secid,
548 &skp->smk_netlabel, sizeof(skp->smk_secid));
549}
550
551/**
552 * smk_import_entry - import a label, return the list entry
553 * @string: a text string that might be a Smack label
554 * @len: the maximum size, or zero if it is NULL terminated.
555 *
556 * Returns a pointer to the entry in the label list that
557 * matches the passed string, adding it if necessary,
558 * or an error code.
559 */
560struct smack_known *smk_import_entry(const char *string, int len)
561{
562 struct smack_known *skp;
563 char *smack;
564 int rc;
565
566 smack = smk_parse_smack(string, len);
567 if (IS_ERR(smack))
568 return ERR_CAST(smack);
569
570 mutex_lock(&smack_known_lock);
571
572 skp = smk_find_entry(smack);
573 if (skp != NULL)
574 goto freeout;
575
576 skp = kzalloc(sizeof(*skp), GFP_NOFS);
577 if (skp == NULL) {
578 skp = ERR_PTR(-ENOMEM);
579 goto freeout;
580 }
581
582 skp->smk_known = smack;
583 skp->smk_secid = smack_next_secid++;
584
585 rc = smack_populate_secattr(skp);
586 if (rc >= 0) {
587 INIT_LIST_HEAD(&skp->smk_rules);
588 mutex_init(&skp->smk_rules_lock);
589 /*
590 * Make sure that the entry is actually
591 * filled before putting it on the list.
592 */
593 smk_insert_entry(skp);
594 goto unlockout;
595 }
596 kfree(skp);
597 skp = ERR_PTR(rc);
598freeout:
599 kfree(smack);
600unlockout:
601 mutex_unlock(&smack_known_lock);
602
603 return skp;
604}
605
606/**
607 * smack_from_secid - find the Smack label associated with a secid
608 * @secid: an integer that might be associated with a Smack label
609 *
610 * Returns a pointer to the appropriate Smack label entry if there is one,
611 * otherwise a pointer to the invalid Smack label.
612 */
613struct smack_known *smack_from_secid(const u32 secid)
614{
615 struct smack_known *skp;
616
617 rcu_read_lock();
618 list_for_each_entry_rcu(skp, &smack_known_list, list) {
619 if (skp->smk_secid == secid) {
620 rcu_read_unlock();
621 return skp;
622 }
623 }
624
625 /*
626 * If we got this far someone asked for the translation
627 * of a secid that is not on the list.
628 */
629 rcu_read_unlock();
630 return &smack_known_huh;
631}
632
633/*
634 * Unless a process is running with one of these labels
635 * even having CAP_MAC_OVERRIDE isn't enough to grant
636 * privilege to violate MAC policy. If no labels are
637 * designated (the empty list case) capabilities apply to
638 * everyone.
639 */
640LIST_HEAD(smack_onlycap_list);
641DEFINE_MUTEX(smack_onlycap_lock);
642
643/**
644 * smack_privileged_cred - are all privilege requirements met by cred
645 * @cap: The requested capability
646 * @cred: the credential to use
647 *
648 * Is the task privileged and allowed to be privileged
649 * by the onlycap rule.
650 *
651 * Returns true if the task is allowed to be privileged, false if it's not.
652 */
653bool smack_privileged_cred(int cap, const struct cred *cred)
654{
655 struct task_smack *tsp = smack_cred(cred);
656 struct smack_known *skp = tsp->smk_task;
657 struct smack_known_list_elem *sklep;
658 int rc;
659
660 rc = cap_capable(cred, &init_user_ns, cap, CAP_OPT_NONE);
661 if (rc)
662 return false;
663
664 rcu_read_lock();
665 if (list_empty(&smack_onlycap_list)) {
666 rcu_read_unlock();
667 return true;
668 }
669
670 list_for_each_entry_rcu(sklep, &smack_onlycap_list, list) {
671 if (sklep->smk_label == skp) {
672 rcu_read_unlock();
673 return true;
674 }
675 }
676 rcu_read_unlock();
677
678 return false;
679}
680
681/**
682 * smack_privileged - are all privilege requirements met
683 * @cap: The requested capability
684 *
685 * Is the task privileged and allowed to be privileged
686 * by the onlycap rule.
687 *
688 * Returns true if the task is allowed to be privileged, false if it's not.
689 */
690bool smack_privileged(int cap)
691{
692 /*
693 * All kernel tasks are privileged
694 */
695 if (unlikely(current->flags & PF_KTHREAD))
696 return true;
697
698 return smack_privileged_cred(cap, current_cred());
699}
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 */
88int smk_access_entry(char *subject_label, char *object_label,
89 struct list_head *rule_list)
90{
91 int may = -ENOENT;
92 struct smack_rule *srp;
93
94 list_for_each_entry_rcu(srp, rule_list, list) {
95 if (srp->smk_object == object_label &&
96 srp->smk_subject == subject_label) {
97 may = srp->smk_access;
98 break;
99 }
100 }
101
102 return may;
103}
104
105/**
106 * smk_access - determine if a subject has a specific access to an object
107 * @subject_label: a pointer to the subject's Smack label
108 * @object_label: a pointer to the object's Smack label
109 * @request: the access requested, in "MAY" format
110 * @a : a pointer to the audit data
111 *
112 * This function looks up the subject/object pair in the
113 * access rule list and returns 0 if the access is permitted,
114 * non zero otherwise.
115 *
116 * Smack labels are shared on smack_list
117 */
118int smk_access(char *subject_label, char *object_label, int request,
119 struct smk_audit_info *a)
120{
121 struct smack_known *skp;
122 int may = MAY_NOT;
123 int rc = 0;
124
125 /*
126 * Hardcoded comparisons.
127 *
128 * A star subject can't access any object.
129 */
130 if (subject_label == smack_known_star.smk_known) {
131 rc = -EACCES;
132 goto out_audit;
133 }
134 /*
135 * An internet object can be accessed by any subject.
136 * Tasks cannot be assigned the internet label.
137 * An internet subject can access any object.
138 */
139 if (object_label == smack_known_web.smk_known ||
140 subject_label == smack_known_web.smk_known)
141 goto out_audit;
142 /*
143 * A star object can be accessed by any subject.
144 */
145 if (object_label == smack_known_star.smk_known)
146 goto out_audit;
147 /*
148 * An object can be accessed in any way by a subject
149 * with the same label.
150 */
151 if (subject_label == object_label)
152 goto out_audit;
153 /*
154 * A hat subject can read any object.
155 * A floor object can be read by any subject.
156 */
157 if ((request & MAY_ANYREAD) == request) {
158 if (object_label == smack_known_floor.smk_known)
159 goto out_audit;
160 if (subject_label == smack_known_hat.smk_known)
161 goto out_audit;
162 }
163 /*
164 * Beyond here an explicit relationship is required.
165 * If the requested access is contained in the available
166 * access (e.g. read is included in readwrite) it's
167 * good. A negative response from smk_access_entry()
168 * indicates there is no entry for this pair.
169 */
170 skp = smk_find_entry(subject_label);
171 rcu_read_lock();
172 may = smk_access_entry(subject_label, object_label, &skp->smk_rules);
173 rcu_read_unlock();
174
175 if (may > 0 && (request & may) == request)
176 goto out_audit;
177
178 rc = -EACCES;
179out_audit:
180#ifdef CONFIG_AUDIT
181 if (a)
182 smack_log(subject_label, object_label, request, rc, a);
183#endif
184 return rc;
185}
186
187/**
188 * smk_curacc - determine if current has a specific access to an object
189 * @obj_label: a pointer to the object's Smack label
190 * @mode: the access requested, in "MAY" format
191 * @a : common audit data
192 *
193 * This function checks the current subject label/object label pair
194 * in the access rule list and returns 0 if the access is permitted,
195 * non zero otherwise. It allows that current may have the capability
196 * to override the rules.
197 */
198int smk_curacc(char *obj_label, u32 mode, struct smk_audit_info *a)
199{
200 struct task_smack *tsp = current_security();
201 char *sp = smk_of_task(tsp);
202 int may;
203 int rc;
204
205 /*
206 * Check the global rule list
207 */
208 rc = smk_access(sp, obj_label, mode, NULL);
209 if (rc == 0) {
210 /*
211 * If there is an entry in the task's rule list
212 * it can further restrict access.
213 */
214 may = smk_access_entry(sp, obj_label, &tsp->smk_rules);
215 if (may < 0)
216 goto out_audit;
217 if ((mode & may) == mode)
218 goto out_audit;
219 rc = -EACCES;
220 }
221
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 */
227 if (smack_onlycap != NULL && smack_onlycap != sp)
228 goto out_audit;
229
230 if (capable(CAP_MAC_OVERRIDE))
231 rc = 0;
232
233out_audit:
234#ifdef CONFIG_AUDIT
235 if (a)
236 smack_log(sp, obj_label, mode, rc, a);
237#endif
238 return rc;
239}
240
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 */
249static 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 */
269static void smack_log_callback(struct audit_buffer *ab, void *a)
270{
271 struct common_audit_data *ad = a;
272 struct smack_audit_data *sad = ad->smack_audit_data;
273 audit_log_format(ab, "lsm=SMACK fn=%s action=%s",
274 ad->smack_audit_data->function,
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 */
294void 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
307 sad = a->smack_audit_data;
308
309 if (sad->function == NULL)
310 sad->function = "unknown";
311
312 /* end preparing the audit data */
313 smack_str_from_perm(request_buffer, request);
314 sad->subject = subject_label;
315 sad->object = object_label;
316 sad->request = request_buffer;
317 sad->result = result;
318
319 common_lsm_audit(a, smack_log_callback, NULL);
320}
321#else /* #ifdef CONFIG_AUDIT */
322void smack_log(char *subject_label, char *object_label, int request,
323 int result, struct smk_audit_info *ad)
324{
325}
326#endif
327
328DEFINE_MUTEX(smack_known_lock);
329
330/**
331 * smk_find_entry - find a label on the list, return the list entry
332 * @string: a text string that might be a Smack label
333 *
334 * Returns a pointer to the entry in the label list that
335 * matches the passed string.
336 */
337struct smack_known *smk_find_entry(const char *string)
338{
339 struct smack_known *skp;
340
341 list_for_each_entry_rcu(skp, &smack_known_list, list) {
342 if (strcmp(skp->smk_known, string) == 0)
343 return skp;
344 }
345
346 return NULL;
347}
348
349/**
350 * smk_parse_smack - parse smack label from a text string
351 * @string: a text string that might contain a Smack label
352 * @len: the maximum size, or zero if it is NULL terminated.
353 *
354 * Returns a pointer to the clean label, or NULL
355 */
356char *smk_parse_smack(const char *string, int len)
357{
358 char *smack;
359 int i;
360
361 if (len <= 0)
362 len = strlen(string) + 1;
363
364 /*
365 * Reserve a leading '-' as an indicator that
366 * this isn't a label, but an option to interfaces
367 * including /smack/cipso and /smack/cipso2
368 */
369 if (string[0] == '-')
370 return NULL;
371
372 for (i = 0; i < len; i++)
373 if (string[i] > '~' || string[i] <= ' ' || string[i] == '/' ||
374 string[i] == '"' || string[i] == '\\' || string[i] == '\'')
375 break;
376
377 if (i == 0 || i >= SMK_LONGLABEL)
378 return NULL;
379
380 smack = kzalloc(i + 1, GFP_KERNEL);
381 if (smack != NULL) {
382 strncpy(smack, string, i + 1);
383 smack[i] = '\0';
384 }
385 return smack;
386}
387
388/**
389 * smk_netlbl_mls - convert a catset to netlabel mls categories
390 * @catset: the Smack categories
391 * @sap: where to put the netlabel categories
392 *
393 * Allocates and fills attr.mls
394 * Returns 0 on success, error code on failure.
395 */
396int smk_netlbl_mls(int level, char *catset, struct netlbl_lsm_secattr *sap,
397 int len)
398{
399 unsigned char *cp;
400 unsigned char m;
401 int cat;
402 int rc;
403 int byte;
404
405 sap->flags |= NETLBL_SECATTR_MLS_CAT;
406 sap->attr.mls.lvl = level;
407 sap->attr.mls.cat = netlbl_secattr_catmap_alloc(GFP_ATOMIC);
408 sap->attr.mls.cat->startbit = 0;
409
410 for (cat = 1, cp = catset, byte = 0; byte < len; cp++, byte++)
411 for (m = 0x80; m != 0; m >>= 1, cat++) {
412 if ((m & *cp) == 0)
413 continue;
414 rc = netlbl_secattr_catmap_setbit(sap->attr.mls.cat,
415 cat, GFP_ATOMIC);
416 if (rc < 0) {
417 netlbl_secattr_catmap_free(sap->attr.mls.cat);
418 return rc;
419 }
420 }
421
422 return 0;
423}
424
425/**
426 * smk_import_entry - import a label, return the list entry
427 * @string: a text string that might be a Smack label
428 * @len: the maximum size, or zero if it is NULL terminated.
429 *
430 * Returns a pointer to the entry in the label list that
431 * matches the passed string, adding it if necessary.
432 */
433struct smack_known *smk_import_entry(const char *string, int len)
434{
435 struct smack_known *skp;
436 char *smack;
437 int slen;
438 int rc;
439
440 smack = smk_parse_smack(string, len);
441 if (smack == NULL)
442 return NULL;
443
444 mutex_lock(&smack_known_lock);
445
446 skp = smk_find_entry(smack);
447 if (skp != NULL)
448 goto freeout;
449
450 skp = kzalloc(sizeof(*skp), GFP_KERNEL);
451 if (skp == NULL)
452 goto freeout;
453
454 skp->smk_known = smack;
455 skp->smk_secid = smack_next_secid++;
456 skp->smk_netlabel.domain = skp->smk_known;
457 skp->smk_netlabel.flags =
458 NETLBL_SECATTR_DOMAIN | NETLBL_SECATTR_MLS_LVL;
459 /*
460 * If direct labeling works use it.
461 * Otherwise use mapped labeling.
462 */
463 slen = strlen(smack);
464 if (slen < SMK_CIPSOLEN)
465 rc = smk_netlbl_mls(smack_cipso_direct, skp->smk_known,
466 &skp->smk_netlabel, slen);
467 else
468 rc = smk_netlbl_mls(smack_cipso_mapped, (char *)&skp->smk_secid,
469 &skp->smk_netlabel, sizeof(skp->smk_secid));
470
471 if (rc >= 0) {
472 INIT_LIST_HEAD(&skp->smk_rules);
473 mutex_init(&skp->smk_rules_lock);
474 /*
475 * Make sure that the entry is actually
476 * filled before putting it on the list.
477 */
478 list_add_rcu(&skp->list, &smack_known_list);
479 goto unlockout;
480 }
481 /*
482 * smk_netlbl_mls failed.
483 */
484 kfree(skp);
485 skp = NULL;
486freeout:
487 kfree(smack);
488unlockout:
489 mutex_unlock(&smack_known_lock);
490
491 return skp;
492}
493
494/**
495 * smk_import - import a smack label
496 * @string: a text string that might be a Smack label
497 * @len: the maximum size, or zero if it is NULL terminated.
498 *
499 * Returns a pointer to the label in the label list that
500 * matches the passed string, adding it if necessary.
501 */
502char *smk_import(const char *string, int len)
503{
504 struct smack_known *skp;
505
506 /* labels cannot begin with a '-' */
507 if (string[0] == '-')
508 return NULL;
509 skp = smk_import_entry(string, len);
510 if (skp == NULL)
511 return NULL;
512 return skp->smk_known;
513}
514
515/**
516 * smack_from_secid - find the Smack label associated with a secid
517 * @secid: an integer that might be associated with a Smack label
518 *
519 * Returns a pointer to the appropriate Smack label if there is one,
520 * otherwise a pointer to the invalid Smack label.
521 */
522char *smack_from_secid(const u32 secid)
523{
524 struct smack_known *skp;
525
526 rcu_read_lock();
527 list_for_each_entry_rcu(skp, &smack_known_list, list) {
528 if (skp->smk_secid == secid) {
529 rcu_read_unlock();
530 return skp->smk_known;
531 }
532 }
533
534 /*
535 * If we got this far someone asked for the translation
536 * of a secid that is not on the list.
537 */
538 rcu_read_unlock();
539 return smack_known_invalid.smk_known;
540}
541
542/**
543 * smack_to_secid - find the secid associated with a Smack label
544 * @smack: the Smack label
545 *
546 * Returns the appropriate secid if there is one,
547 * otherwise 0
548 */
549u32 smack_to_secid(const char *smack)
550{
551 struct smack_known *skp = smk_find_entry(smack);
552
553 if (skp == NULL)
554 return 0;
555 return skp->smk_secid;
556}