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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 int may = -ENOENT;
85 struct smack_rule *srp;
86
87 list_for_each_entry_rcu(srp, rule_list, list) {
88 if (srp->smk_object->smk_known == object_label &&
89 srp->smk_subject->smk_known == subject_label) {
90 may = srp->smk_access;
91 break;
92 }
93 }
94
95 /*
96 * MAY_WRITE implies MAY_LOCK.
97 */
98 if ((may & MAY_WRITE) == MAY_WRITE)
99 may |= MAY_LOCK;
100 return may;
101}
102
103/**
104 * smk_access - determine if a subject has a specific access to an object
105 * @subject: a pointer to the subject's Smack label entry
106 * @object: a pointer to the object's Smack label entry
107 * @request: the access requested, in "MAY" format
108 * @a : a pointer to the audit data
109 *
110 * This function looks up the subject/object pair in the
111 * access rule list and returns 0 if the access is permitted,
112 * non zero otherwise.
113 *
114 * Smack labels are shared on smack_list
115 */
116int smk_access(struct smack_known *subject, struct smack_known *object,
117 int request, struct smk_audit_info *a)
118{
119 int may = MAY_NOT;
120 int rc = 0;
121
122 /*
123 * Hardcoded comparisons.
124 */
125 /*
126 * A star subject can't access any object.
127 */
128 if (subject == &smack_known_star) {
129 rc = -EACCES;
130 goto out_audit;
131 }
132 /*
133 * An internet object can be accessed by any subject.
134 * Tasks cannot be assigned the internet label.
135 * An internet subject can access any object.
136 */
137 if (object == &smack_known_web || subject == &smack_known_web)
138 goto out_audit;
139 /*
140 * A star object can be accessed by any subject.
141 */
142 if (object == &smack_known_star)
143 goto out_audit;
144 /*
145 * An object can be accessed in any way by a subject
146 * with the same label.
147 */
148 if (subject->smk_known == object->smk_known)
149 goto out_audit;
150 /*
151 * A hat subject can read or lock any object.
152 * A floor object can be read or locked by any subject.
153 */
154 if ((request & MAY_ANYREAD) == request ||
155 (request & MAY_LOCK) == request) {
156 if (object == &smack_known_floor)
157 goto out_audit;
158 if (subject == &smack_known_hat)
159 goto out_audit;
160 }
161 /*
162 * Beyond here an explicit relationship is required.
163 * If the requested access is contained in the available
164 * access (e.g. read is included in readwrite) it's
165 * good. A negative response from smk_access_entry()
166 * indicates there is no entry for this pair.
167 */
168 rcu_read_lock();
169 may = smk_access_entry(subject->smk_known, object->smk_known,
170 &subject->smk_rules);
171 rcu_read_unlock();
172
173 if (may <= 0 || (request & may) != request) {
174 rc = -EACCES;
175 goto out_audit;
176 }
177#ifdef CONFIG_SECURITY_SMACK_BRINGUP
178 /*
179 * Return a positive value if using bringup mode.
180 * This allows the hooks to identify checks that
181 * succeed because of "b" rules.
182 */
183 if (may & MAY_BRINGUP)
184 rc = SMACK_BRINGUP_ALLOW;
185#endif
186
187out_audit:
188
189#ifdef CONFIG_SECURITY_SMACK_BRINGUP
190 if (rc < 0) {
191 if (object == smack_unconfined)
192 rc = SMACK_UNCONFINED_OBJECT;
193 if (subject == smack_unconfined)
194 rc = SMACK_UNCONFINED_SUBJECT;
195 }
196#endif
197
198#ifdef CONFIG_AUDIT
199 if (a)
200 smack_log(subject->smk_known, object->smk_known,
201 request, rc, a);
202#endif
203
204 return rc;
205}
206
207/**
208 * smk_tskacc - determine if a task has a specific access to an object
209 * @tsp: a pointer to the subject's task
210 * @obj_known: a pointer to the object's label entry
211 * @mode: the access requested, in "MAY" format
212 * @a : common audit data
213 *
214 * This function checks the subject task's label/object label pair
215 * in the access rule list and returns 0 if the access is permitted,
216 * non zero otherwise. It allows that the task may have the capability
217 * to override the rules.
218 */
219int smk_tskacc(struct task_smack *tsp, struct smack_known *obj_known,
220 u32 mode, struct smk_audit_info *a)
221{
222 struct smack_known *sbj_known = smk_of_task(tsp);
223 int may;
224 int rc;
225
226 /*
227 * Check the global rule list
228 */
229 rc = smk_access(sbj_known, obj_known, mode, NULL);
230 if (rc >= 0) {
231 /*
232 * If there is an entry in the task's rule list
233 * it can further restrict access.
234 */
235 may = smk_access_entry(sbj_known->smk_known,
236 obj_known->smk_known,
237 &tsp->smk_rules);
238 if (may < 0)
239 goto out_audit;
240 if ((mode & may) == mode)
241 goto out_audit;
242 rc = -EACCES;
243 }
244
245 /*
246 * Allow for priviliged to override policy.
247 */
248 if (rc != 0 && smack_privileged(CAP_MAC_OVERRIDE))
249 rc = 0;
250
251out_audit:
252#ifdef CONFIG_AUDIT
253 if (a)
254 smack_log(sbj_known->smk_known, obj_known->smk_known,
255 mode, rc, a);
256#endif
257 return rc;
258}
259
260/**
261 * smk_curacc - determine if current has a specific access to an object
262 * @obj_known: a pointer to the object's Smack label entry
263 * @mode: the access requested, in "MAY" format
264 * @a : common audit data
265 *
266 * This function checks the current subject label/object label pair
267 * in the access rule list and returns 0 if the access is permitted,
268 * non zero otherwise. It allows that current may have the capability
269 * to override the rules.
270 */
271int smk_curacc(struct smack_known *obj_known,
272 u32 mode, struct smk_audit_info *a)
273{
274 struct task_smack *tsp = smack_cred(current_cred());
275
276 return smk_tskacc(tsp, obj_known, mode, a);
277}
278
279#ifdef CONFIG_AUDIT
280/**
281 * smack_str_from_perm : helper to transalate an int to a
282 * readable string
283 * @string : the string to fill
284 * @access : the int
285 *
286 */
287static inline void smack_str_from_perm(char *string, int access)
288{
289 int i = 0;
290
291 if (access & MAY_READ)
292 string[i++] = 'r';
293 if (access & MAY_WRITE)
294 string[i++] = 'w';
295 if (access & MAY_EXEC)
296 string[i++] = 'x';
297 if (access & MAY_APPEND)
298 string[i++] = 'a';
299 if (access & MAY_TRANSMUTE)
300 string[i++] = 't';
301 if (access & MAY_LOCK)
302 string[i++] = 'l';
303 string[i] = '\0';
304}
305/**
306 * smack_log_callback - SMACK specific information
307 * will be called by generic audit code
308 * @ab : the audit_buffer
309 * @a : audit_data
310 *
311 */
312static void smack_log_callback(struct audit_buffer *ab, void *a)
313{
314 struct common_audit_data *ad = a;
315 struct smack_audit_data *sad = ad->smack_audit_data;
316 audit_log_format(ab, "lsm=SMACK fn=%s action=%s",
317 ad->smack_audit_data->function,
318 sad->result ? "denied" : "granted");
319 audit_log_format(ab, " subject=");
320 audit_log_untrustedstring(ab, sad->subject);
321 audit_log_format(ab, " object=");
322 audit_log_untrustedstring(ab, sad->object);
323 if (sad->request[0] == '\0')
324 audit_log_format(ab, " labels_differ");
325 else
326 audit_log_format(ab, " requested=%s", sad->request);
327}
328
329/**
330 * smack_log - Audit the granting or denial of permissions.
331 * @subject_label : smack label of the requester
332 * @object_label : smack label of the object being accessed
333 * @request: requested permissions
334 * @result: result from smk_access
335 * @a: auxiliary audit data
336 *
337 * Audit the granting or denial of permissions in accordance
338 * with the policy.
339 */
340void smack_log(char *subject_label, char *object_label, int request,
341 int result, struct smk_audit_info *ad)
342{
343#ifdef CONFIG_SECURITY_SMACK_BRINGUP
344 char request_buffer[SMK_NUM_ACCESS_TYPE + 5];
345#else
346 char request_buffer[SMK_NUM_ACCESS_TYPE + 1];
347#endif
348 struct smack_audit_data *sad;
349 struct common_audit_data *a = &ad->a;
350
351 /* check if we have to log the current event */
352 if (result < 0 && (log_policy & SMACK_AUDIT_DENIED) == 0)
353 return;
354 if (result == 0 && (log_policy & SMACK_AUDIT_ACCEPT) == 0)
355 return;
356
357 sad = a->smack_audit_data;
358
359 if (sad->function == NULL)
360 sad->function = "unknown";
361
362 /* end preparing the audit data */
363 smack_str_from_perm(request_buffer, request);
364 sad->subject = subject_label;
365 sad->object = object_label;
366#ifdef CONFIG_SECURITY_SMACK_BRINGUP
367 /*
368 * The result may be positive in bringup mode.
369 * A positive result is an allow, but not for normal reasons.
370 * Mark it as successful, but don't filter it out even if
371 * the logging policy says to do so.
372 */
373 if (result == SMACK_UNCONFINED_SUBJECT)
374 strcat(request_buffer, "(US)");
375 else if (result == SMACK_UNCONFINED_OBJECT)
376 strcat(request_buffer, "(UO)");
377
378 if (result > 0)
379 result = 0;
380#endif
381 sad->request = request_buffer;
382 sad->result = result;
383
384 common_lsm_audit(a, smack_log_callback, NULL);
385}
386#else /* #ifdef CONFIG_AUDIT */
387void smack_log(char *subject_label, char *object_label, int request,
388 int result, struct smk_audit_info *ad)
389{
390}
391#endif
392
393DEFINE_MUTEX(smack_known_lock);
394
395struct hlist_head smack_known_hash[SMACK_HASH_SLOTS];
396
397/**
398 * smk_insert_entry - insert a smack label into a hash map,
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 * @catset: the Smack categories
480 * @sap: where to put the netlabel categories
481 *
482 * Allocates and fills attr.mls
483 * Returns 0 on success, error code on failure.
484 */
485int smk_netlbl_mls(int level, char *catset, struct netlbl_lsm_secattr *sap,
486 int len)
487{
488 unsigned char *cp;
489 unsigned char m;
490 int cat;
491 int rc;
492 int byte;
493
494 sap->flags |= NETLBL_SECATTR_MLS_CAT;
495 sap->attr.mls.lvl = level;
496 sap->attr.mls.cat = NULL;
497
498 for (cat = 1, cp = catset, byte = 0; byte < len; cp++, byte++)
499 for (m = 0x80; m != 0; m >>= 1, cat++) {
500 if ((m & *cp) == 0)
501 continue;
502 rc = netlbl_catmap_setbit(&sap->attr.mls.cat,
503 cat, GFP_NOFS);
504 if (rc < 0) {
505 netlbl_catmap_free(sap->attr.mls.cat);
506 return rc;
507 }
508 }
509
510 return 0;
511}
512
513/**
514 * smk_import_entry - import a label, return the list entry
515 * @string: a text string that might be a Smack label
516 * @len: the maximum size, or zero if it is NULL terminated.
517 *
518 * Returns a pointer to the entry in the label list that
519 * matches the passed string, adding it if necessary,
520 * or an error code.
521 */
522struct smack_known *smk_import_entry(const char *string, int len)
523{
524 struct smack_known *skp;
525 char *smack;
526 int slen;
527 int rc;
528
529 smack = smk_parse_smack(string, len);
530 if (IS_ERR(smack))
531 return ERR_CAST(smack);
532
533 mutex_lock(&smack_known_lock);
534
535 skp = smk_find_entry(smack);
536 if (skp != NULL)
537 goto freeout;
538
539 skp = kzalloc(sizeof(*skp), GFP_NOFS);
540 if (skp == NULL) {
541 skp = ERR_PTR(-ENOMEM);
542 goto freeout;
543 }
544
545 skp->smk_known = smack;
546 skp->smk_secid = smack_next_secid++;
547 skp->smk_netlabel.domain = skp->smk_known;
548 skp->smk_netlabel.flags =
549 NETLBL_SECATTR_DOMAIN | NETLBL_SECATTR_MLS_LVL;
550 /*
551 * If direct labeling works use it.
552 * Otherwise use mapped labeling.
553 */
554 slen = strlen(smack);
555 if (slen < SMK_CIPSOLEN)
556 rc = smk_netlbl_mls(smack_cipso_direct, skp->smk_known,
557 &skp->smk_netlabel, slen);
558 else
559 rc = smk_netlbl_mls(smack_cipso_mapped, (char *)&skp->smk_secid,
560 &skp->smk_netlabel, sizeof(skp->smk_secid));
561
562 if (rc >= 0) {
563 INIT_LIST_HEAD(&skp->smk_rules);
564 mutex_init(&skp->smk_rules_lock);
565 /*
566 * Make sure that the entry is actually
567 * filled before putting it on the list.
568 */
569 smk_insert_entry(skp);
570 goto unlockout;
571 }
572 /*
573 * smk_netlbl_mls failed.
574 */
575 kfree(skp);
576 skp = ERR_PTR(rc);
577freeout:
578 kfree(smack);
579unlockout:
580 mutex_unlock(&smack_known_lock);
581
582 return skp;
583}
584
585/**
586 * smack_from_secid - find the Smack label associated with a secid
587 * @secid: an integer that might be associated with a Smack label
588 *
589 * Returns a pointer to the appropriate Smack label entry if there is one,
590 * otherwise a pointer to the invalid Smack label.
591 */
592struct smack_known *smack_from_secid(const u32 secid)
593{
594 struct smack_known *skp;
595
596 rcu_read_lock();
597 list_for_each_entry_rcu(skp, &smack_known_list, list) {
598 if (skp->smk_secid == secid) {
599 rcu_read_unlock();
600 return skp;
601 }
602 }
603
604 /*
605 * If we got this far someone asked for the translation
606 * of a secid that is not on the list.
607 */
608 rcu_read_unlock();
609 return &smack_known_huh;
610}
611
612/*
613 * Unless a process is running with one of these labels
614 * even having CAP_MAC_OVERRIDE isn't enough to grant
615 * privilege to violate MAC policy. If no labels are
616 * designated (the empty list case) capabilities apply to
617 * everyone.
618 */
619LIST_HEAD(smack_onlycap_list);
620DEFINE_MUTEX(smack_onlycap_lock);
621
622/**
623 * smack_privileged_cred - are all privilege requirements met by cred
624 * @cap: The requested capability
625 * @cred: the credential to use
626 *
627 * Is the task privileged and allowed to be privileged
628 * by the onlycap rule.
629 *
630 * Returns true if the task is allowed to be privileged, false if it's not.
631 */
632bool smack_privileged_cred(int cap, const struct cred *cred)
633{
634 struct task_smack *tsp = smack_cred(cred);
635 struct smack_known *skp = tsp->smk_task;
636 struct smack_known_list_elem *sklep;
637 int rc;
638
639 rc = cap_capable(cred, &init_user_ns, cap, CAP_OPT_NONE);
640 if (rc)
641 return false;
642
643 rcu_read_lock();
644 if (list_empty(&smack_onlycap_list)) {
645 rcu_read_unlock();
646 return true;
647 }
648
649 list_for_each_entry_rcu(sklep, &smack_onlycap_list, list) {
650 if (sklep->smk_label == skp) {
651 rcu_read_unlock();
652 return true;
653 }
654 }
655 rcu_read_unlock();
656
657 return false;
658}
659
660/**
661 * smack_privileged - are all privilege requirements met
662 * @cap: The requested capability
663 *
664 * Is the task privileged and allowed to be privileged
665 * by the onlycap rule.
666 *
667 * Returns true if the task is allowed to be privileged, false if it's not.
668 */
669bool smack_privileged(int cap)
670{
671 /*
672 * All kernel tasks are privileged
673 */
674 if (unlikely(current->flags & PF_KTHREAD))
675 return true;
676
677 return smack_privileged_cred(cap, current_cred());
678}
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 = kstrndup(string, i, GFP_NOFS);
469 if (!smack)
470 return ERR_PTR(-ENOMEM);
471 return smack;
472}
473
474/**
475 * smk_netlbl_mls - convert a catset to netlabel mls categories
476 * @level: MLS sensitivity level
477 * @catset: the Smack categories
478 * @sap: where to put the netlabel categories
479 * @len: number of bytes for the levels in a CIPSO IP option
480 *
481 * Allocates and fills attr.mls
482 * Returns 0 on success, error code on failure.
483 */
484int smk_netlbl_mls(int level, char *catset, struct netlbl_lsm_secattr *sap,
485 int len)
486{
487 unsigned char *cp;
488 unsigned char m;
489 int cat;
490 int rc;
491 int byte;
492
493 sap->flags |= NETLBL_SECATTR_MLS_CAT;
494 sap->attr.mls.lvl = level;
495 sap->attr.mls.cat = NULL;
496
497 for (cat = 1, cp = catset, byte = 0; byte < len; cp++, byte++)
498 for (m = 0x80; m != 0; m >>= 1, cat++) {
499 if ((m & *cp) == 0)
500 continue;
501 rc = netlbl_catmap_setbit(&sap->attr.mls.cat,
502 cat, GFP_NOFS);
503 if (rc < 0) {
504 netlbl_catmap_free(sap->attr.mls.cat);
505 return rc;
506 }
507 }
508
509 return 0;
510}
511
512/**
513 * smack_populate_secattr - fill in the smack_known netlabel information
514 * @skp: pointer to the structure to fill
515 *
516 * Populate the netlabel secattr structure for a Smack label.
517 *
518 * Returns 0 unless creating the category mapping fails
519 */
520int smack_populate_secattr(struct smack_known *skp)
521{
522 int slen;
523
524 skp->smk_netlabel.attr.secid = skp->smk_secid;
525 skp->smk_netlabel.domain = skp->smk_known;
526 skp->smk_netlabel.cache = netlbl_secattr_cache_alloc(GFP_ATOMIC);
527 if (skp->smk_netlabel.cache != NULL) {
528 skp->smk_netlabel.flags |= NETLBL_SECATTR_CACHE;
529 skp->smk_netlabel.cache->free = NULL;
530 skp->smk_netlabel.cache->data = skp;
531 }
532 skp->smk_netlabel.flags |= NETLBL_SECATTR_SECID |
533 NETLBL_SECATTR_MLS_LVL |
534 NETLBL_SECATTR_DOMAIN;
535 /*
536 * If direct labeling works use it.
537 * Otherwise use mapped labeling.
538 */
539 slen = strlen(skp->smk_known);
540 if (slen < SMK_CIPSOLEN)
541 return smk_netlbl_mls(smack_cipso_direct, skp->smk_known,
542 &skp->smk_netlabel, slen);
543
544 return smk_netlbl_mls(smack_cipso_mapped, (char *)&skp->smk_secid,
545 &skp->smk_netlabel, sizeof(skp->smk_secid));
546}
547
548/**
549 * smk_import_entry - import a label, return the list entry
550 * @string: a text string that might be a Smack label
551 * @len: the maximum size, or zero if it is NULL terminated.
552 *
553 * Returns a pointer to the entry in the label list that
554 * matches the passed string, adding it if necessary,
555 * or an error code.
556 */
557struct smack_known *smk_import_entry(const char *string, int len)
558{
559 struct smack_known *skp;
560 char *smack;
561 int rc;
562
563 smack = smk_parse_smack(string, len);
564 if (IS_ERR(smack))
565 return ERR_CAST(smack);
566
567 mutex_lock(&smack_known_lock);
568
569 skp = smk_find_entry(smack);
570 if (skp != NULL)
571 goto freeout;
572
573 skp = kzalloc(sizeof(*skp), GFP_NOFS);
574 if (skp == NULL) {
575 skp = ERR_PTR(-ENOMEM);
576 goto freeout;
577 }
578
579 skp->smk_known = smack;
580 skp->smk_secid = smack_next_secid++;
581
582 rc = smack_populate_secattr(skp);
583 if (rc >= 0) {
584 INIT_LIST_HEAD(&skp->smk_rules);
585 mutex_init(&skp->smk_rules_lock);
586 /*
587 * Make sure that the entry is actually
588 * filled before putting it on the list.
589 */
590 smk_insert_entry(skp);
591 goto unlockout;
592 }
593 kfree(skp);
594 skp = ERR_PTR(rc);
595freeout:
596 kfree(smack);
597unlockout:
598 mutex_unlock(&smack_known_lock);
599
600 return skp;
601}
602
603/**
604 * smack_from_secid - find the Smack label associated with a secid
605 * @secid: an integer that might be associated with a Smack label
606 *
607 * Returns a pointer to the appropriate Smack label entry if there is one,
608 * otherwise a pointer to the invalid Smack label.
609 */
610struct smack_known *smack_from_secid(const u32 secid)
611{
612 struct smack_known *skp;
613
614 rcu_read_lock();
615 list_for_each_entry_rcu(skp, &smack_known_list, list) {
616 if (skp->smk_secid == secid) {
617 rcu_read_unlock();
618 return skp;
619 }
620 }
621
622 /*
623 * If we got this far someone asked for the translation
624 * of a secid that is not on the list.
625 */
626 rcu_read_unlock();
627 return &smack_known_huh;
628}
629
630/*
631 * Unless a process is running with one of these labels
632 * even having CAP_MAC_OVERRIDE isn't enough to grant
633 * privilege to violate MAC policy. If no labels are
634 * designated (the empty list case) capabilities apply to
635 * everyone.
636 */
637LIST_HEAD(smack_onlycap_list);
638DEFINE_MUTEX(smack_onlycap_lock);
639
640/**
641 * smack_privileged_cred - are all privilege requirements met by cred
642 * @cap: The requested capability
643 * @cred: the credential to use
644 *
645 * Is the task privileged and allowed to be privileged
646 * by the onlycap rule.
647 *
648 * Returns true if the task is allowed to be privileged, false if it's not.
649 */
650bool smack_privileged_cred(int cap, const struct cred *cred)
651{
652 struct task_smack *tsp = smack_cred(cred);
653 struct smack_known *skp = tsp->smk_task;
654 struct smack_known_list_elem *sklep;
655 int rc;
656
657 rc = cap_capable(cred, &init_user_ns, cap, CAP_OPT_NONE);
658 if (rc)
659 return false;
660
661 rcu_read_lock();
662 if (list_empty(&smack_onlycap_list)) {
663 rcu_read_unlock();
664 return true;
665 }
666
667 list_for_each_entry_rcu(sklep, &smack_onlycap_list, list) {
668 if (sklep->smk_label == skp) {
669 rcu_read_unlock();
670 return true;
671 }
672 }
673 rcu_read_unlock();
674
675 return false;
676}
677
678/**
679 * smack_privileged - are all privilege requirements met
680 * @cap: The requested capability
681 *
682 * Is the task privileged and allowed to be privileged
683 * by the onlycap rule.
684 *
685 * Returns true if the task is allowed to be privileged, false if it's not.
686 */
687bool smack_privileged(int cap)
688{
689 /*
690 * All kernel tasks are privileged
691 */
692 if (unlikely(current->flags & PF_KTHREAD))
693 return true;
694
695 return smack_privileged_cred(cap, current_cred());
696}