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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_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_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}