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Casey Schauflere114e472008-02-04 22:29:50 -08001/*
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>
Tejun Heo5a0e3ad2010-03-24 17:04:11 +090014#include <linux/slab.h>
Casey Schauflere114e472008-02-04 22:29:50 -080015#include <linux/fs.h>
16#include <linux/sched.h>
17#include "smack.h"
18
Casey Schauflere114e472008-02-04 22:29:50 -080019struct smack_known smack_known_huh = {
Casey Schauflere114e472008-02-04 22:29:50 -080020 .smk_known = "?",
21 .smk_secid = 2,
22 .smk_cipso = NULL,
23};
24
25struct smack_known smack_known_hat = {
Casey Schauflere114e472008-02-04 22:29:50 -080026 .smk_known = "^",
27 .smk_secid = 3,
28 .smk_cipso = NULL,
29};
30
31struct smack_known smack_known_star = {
Casey Schauflere114e472008-02-04 22:29:50 -080032 .smk_known = "*",
33 .smk_secid = 4,
34 .smk_cipso = NULL,
35};
36
37struct smack_known smack_known_floor = {
Casey Schauflere114e472008-02-04 22:29:50 -080038 .smk_known = "_",
39 .smk_secid = 5,
40 .smk_cipso = NULL,
41};
42
43struct smack_known smack_known_invalid = {
Casey Schauflere114e472008-02-04 22:29:50 -080044 .smk_known = "",
45 .smk_secid = 6,
46 .smk_cipso = NULL,
47};
48
Casey Schaufler6d3dc072008-12-31 12:54:12 -050049struct smack_known smack_known_web = {
Casey Schaufler6d3dc072008-12-31 12:54:12 -050050 .smk_known = "@",
51 .smk_secid = 7,
52 .smk_cipso = NULL,
53};
54
Etienne Basset7198e2e2009-03-24 20:53:24 +010055LIST_HEAD(smack_known_list);
Casey Schauflere114e472008-02-04 22:29:50 -080056
57/*
58 * The initial value needs to be bigger than any of the
59 * known values above.
60 */
61static u32 smack_next_secid = 10;
62
Etienne Bassetecfcc532009-04-08 20:40:06 +020063/*
64 * what events do we log
65 * can be overwritten at run-time by /smack/logging
66 */
67int log_policy = SMACK_AUDIT_DENIED;
68
Casey Schauflere114e472008-02-04 22:29:50 -080069/**
Jarkko Sakkinen5c6d1122010-12-07 13:34:01 +020070 * smk_access_entry - look up matching access rule
71 * @subject_label: a pointer to the subject's Smack label
72 * @object_label: a pointer to the object's Smack label
73 *
74 * This function looks up the subject/object pair in the
75 * access rule list and returns pointer to the matching rule if found,
76 * NULL otherwise.
77 *
78 * NOTE:
79 * Even though Smack labels are usually shared on smack_list
80 * labels that come in off the network can't be imported
81 * and added to the list for locking reasons.
82 *
83 * Therefore, it is necessary to check the contents of the labels,
84 * not just the pointer values. Of course, in most cases the labels
85 * will be on the list, so checking the pointers may be a worthwhile
86 * optimization.
87 */
88int smk_access_entry(char *subject_label, char *object_label)
89{
90 u32 may = MAY_NOT;
91 struct smack_rule *srp;
92
93 rcu_read_lock();
94 list_for_each_entry_rcu(srp, &smack_rule_list, list) {
95 if (srp->smk_subject == subject_label ||
96 strcmp(srp->smk_subject, subject_label) == 0) {
97 if (srp->smk_object == object_label ||
98 strcmp(srp->smk_object, object_label) == 0) {
99 may = srp->smk_access;
100 break;
101 }
102 }
103 }
104 rcu_read_unlock();
105
106 return may;
107}
108
109/**
Casey Schauflere114e472008-02-04 22:29:50 -0800110 * smk_access - determine if a subject has a specific access to an object
111 * @subject_label: a pointer to the subject's Smack label
112 * @object_label: a pointer to the object's Smack label
113 * @request: the access requested, in "MAY" format
Etienne Bassetecfcc532009-04-08 20:40:06 +0200114 * @a : a pointer to the audit data
Casey Schauflere114e472008-02-04 22:29:50 -0800115 *
116 * This function looks up the subject/object pair in the
117 * access rule list and returns 0 if the access is permitted,
118 * non zero otherwise.
119 *
120 * Even though Smack labels are usually shared on smack_list
121 * labels that come in off the network can't be imported
122 * and added to the list for locking reasons.
123 *
124 * Therefore, it is necessary to check the contents of the labels,
125 * not just the pointer values. Of course, in most cases the labels
126 * will be on the list, so checking the pointers may be a worthwhile
127 * optimization.
128 */
Etienne Bassetecfcc532009-04-08 20:40:06 +0200129int smk_access(char *subject_label, char *object_label, int request,
130 struct smk_audit_info *a)
Casey Schauflere114e472008-02-04 22:29:50 -0800131{
132 u32 may = MAY_NOT;
Etienne Bassetecfcc532009-04-08 20:40:06 +0200133 int rc = 0;
Casey Schauflere114e472008-02-04 22:29:50 -0800134
135 /*
136 * Hardcoded comparisons.
137 *
138 * A star subject can't access any object.
139 */
140 if (subject_label == smack_known_star.smk_known ||
Etienne Bassetecfcc532009-04-08 20:40:06 +0200141 strcmp(subject_label, smack_known_star.smk_known) == 0) {
142 rc = -EACCES;
143 goto out_audit;
144 }
Casey Schauflere114e472008-02-04 22:29:50 -0800145 /*
Casey Schaufler6d3dc072008-12-31 12:54:12 -0500146 * An internet object can be accessed by any subject.
147 * Tasks cannot be assigned the internet label.
148 * An internet subject can access any object.
149 */
150 if (object_label == smack_known_web.smk_known ||
151 subject_label == smack_known_web.smk_known ||
152 strcmp(object_label, smack_known_web.smk_known) == 0 ||
153 strcmp(subject_label, smack_known_web.smk_known) == 0)
Etienne Bassetecfcc532009-04-08 20:40:06 +0200154 goto out_audit;
Casey Schaufler6d3dc072008-12-31 12:54:12 -0500155 /*
Casey Schauflere114e472008-02-04 22:29:50 -0800156 * A star object can be accessed by any subject.
157 */
158 if (object_label == smack_known_star.smk_known ||
159 strcmp(object_label, smack_known_star.smk_known) == 0)
Etienne Bassetecfcc532009-04-08 20:40:06 +0200160 goto out_audit;
Casey Schauflere114e472008-02-04 22:29:50 -0800161 /*
162 * An object can be accessed in any way by a subject
163 * with the same label.
164 */
165 if (subject_label == object_label ||
166 strcmp(subject_label, object_label) == 0)
Etienne Bassetecfcc532009-04-08 20:40:06 +0200167 goto out_audit;
Casey Schauflere114e472008-02-04 22:29:50 -0800168 /*
169 * A hat subject can read any object.
170 * A floor object can be read by any subject.
171 */
172 if ((request & MAY_ANYREAD) == request) {
173 if (object_label == smack_known_floor.smk_known ||
174 strcmp(object_label, smack_known_floor.smk_known) == 0)
Etienne Bassetecfcc532009-04-08 20:40:06 +0200175 goto out_audit;
Casey Schauflere114e472008-02-04 22:29:50 -0800176 if (subject_label == smack_known_hat.smk_known ||
177 strcmp(subject_label, smack_known_hat.smk_known) == 0)
Etienne Bassetecfcc532009-04-08 20:40:06 +0200178 goto out_audit;
Casey Schauflere114e472008-02-04 22:29:50 -0800179 }
180 /*
181 * Beyond here an explicit relationship is required.
182 * If the requested access is contained in the available
183 * access (e.g. read is included in readwrite) it's
184 * good.
185 */
Jarkko Sakkinen5c6d1122010-12-07 13:34:01 +0200186 may = smk_access_entry(subject_label, object_label);
Casey Schauflere114e472008-02-04 22:29:50 -0800187 /*
188 * This is a bit map operation.
189 */
190 if ((request & may) == request)
Etienne Bassetecfcc532009-04-08 20:40:06 +0200191 goto out_audit;
Casey Schauflere114e472008-02-04 22:29:50 -0800192
Etienne Bassetecfcc532009-04-08 20:40:06 +0200193 rc = -EACCES;
194out_audit:
195#ifdef CONFIG_AUDIT
196 if (a)
197 smack_log(subject_label, object_label, request, rc, a);
198#endif
199 return rc;
Casey Schauflere114e472008-02-04 22:29:50 -0800200}
201
202/**
203 * smk_curacc - determine if current has a specific access to an object
Randy Dunlap251a2a92009-02-18 11:42:33 -0800204 * @obj_label: a pointer to the object's Smack label
205 * @mode: the access requested, in "MAY" format
Etienne Bassetecfcc532009-04-08 20:40:06 +0200206 * @a : common audit data
Casey Schauflere114e472008-02-04 22:29:50 -0800207 *
208 * This function checks the current subject label/object label pair
209 * in the access rule list and returns 0 if the access is permitted,
Casey Schaufler15446232008-07-30 15:37:11 -0700210 * non zero otherwise. It allows that current may have the capability
Casey Schauflere114e472008-02-04 22:29:50 -0800211 * to override the rules.
212 */
Etienne Bassetecfcc532009-04-08 20:40:06 +0200213int smk_curacc(char *obj_label, u32 mode, struct smk_audit_info *a)
Casey Schauflere114e472008-02-04 22:29:50 -0800214{
215 int rc;
Casey Schaufler676dac42010-12-02 06:43:39 -0800216 char *sp = smk_of_current();
Casey Schauflere114e472008-02-04 22:29:50 -0800217
Etienne Bassetecfcc532009-04-08 20:40:06 +0200218 rc = smk_access(sp, obj_label, mode, NULL);
Casey Schauflere114e472008-02-04 22:29:50 -0800219 if (rc == 0)
Etienne Bassetecfcc532009-04-08 20:40:06 +0200220 goto out_audit;
Casey Schauflere114e472008-02-04 22:29:50 -0800221
Casey Schaufler15446232008-07-30 15:37:11 -0700222 /*
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 */
Casey Schaufler676dac42010-12-02 06:43:39 -0800227 if (smack_onlycap != NULL && smack_onlycap != sp)
Etienne Bassetecfcc532009-04-08 20:40:06 +0200228 goto out_audit;
Casey Schaufler15446232008-07-30 15:37:11 -0700229
Casey Schauflere114e472008-02-04 22:29:50 -0800230 if (capable(CAP_MAC_OVERRIDE))
231 return 0;
232
Etienne Bassetecfcc532009-04-08 20:40:06 +0200233out_audit:
234#ifdef CONFIG_AUDIT
235 if (a)
236 smack_log(sp, obj_label, mode, rc, a);
237#endif
Casey Schauflere114e472008-02-04 22:29:50 -0800238 return rc;
239}
240
Etienne Bassetecfcc532009-04-08 20:40:06 +0200241#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;
Thomas Liud4131de2009-07-09 10:00:30 -0400272 struct smack_audit_data *sad = &ad->smack_audit_data;
Thomas Liued5215a2009-07-09 10:00:29 -0400273 audit_log_format(ab, "lsm=SMACK fn=%s action=%s",
Thomas Liud4131de2009-07-09 10:00:30 -0400274 ad->smack_audit_data.function,
Etienne Bassetecfcc532009-04-08 20:40:06 +0200275 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
Thomas Liud4131de2009-07-09 10:00:30 -0400307 if (a->smack_audit_data.function == NULL)
308 a->smack_audit_data.function = "unknown";
Etienne Bassetecfcc532009-04-08 20:40:06 +0200309
310 /* end preparing the audit data */
Thomas Liud4131de2009-07-09 10:00:30 -0400311 sad = &a->smack_audit_data;
Etienne Bassetecfcc532009-04-08 20:40:06 +0200312 smack_str_from_perm(request_buffer, request);
313 sad->subject = subject_label;
314 sad->object = object_label;
315 sad->request = request_buffer;
316 sad->result = result;
317 a->lsm_pre_audit = smack_log_callback;
318
319 common_lsm_audit(a);
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
Casey Schauflere114e472008-02-04 22:29:50 -0800328static DEFINE_MUTEX(smack_known_lock);
329
330/**
331 * smk_import_entry - import a label, return the list entry
332 * @string: a text string that might be a Smack label
333 * @len: the maximum size, or zero if it is NULL terminated.
334 *
335 * Returns a pointer to the entry in the label list that
336 * matches the passed string, adding it if necessary.
337 */
338struct smack_known *smk_import_entry(const char *string, int len)
339{
340 struct smack_known *skp;
341 char smack[SMK_LABELLEN];
342 int found;
343 int i;
344
345 if (len <= 0 || len > SMK_MAXLEN)
346 len = SMK_MAXLEN;
347
348 for (i = 0, found = 0; i < SMK_LABELLEN; i++) {
349 if (found)
350 smack[i] = '\0';
351 else if (i >= len || string[i] > '~' || string[i] <= ' ' ||
Etienne Bassetecfcc532009-04-08 20:40:06 +0200352 string[i] == '/' || string[i] == '"' ||
353 string[i] == '\\' || string[i] == '\'') {
Casey Schauflere114e472008-02-04 22:29:50 -0800354 smack[i] = '\0';
355 found = 1;
356 } else
357 smack[i] = string[i];
358 }
359
360 if (smack[0] == '\0')
361 return NULL;
362
363 mutex_lock(&smack_known_lock);
364
Etienne Basset7198e2e2009-03-24 20:53:24 +0100365 found = 0;
366 list_for_each_entry_rcu(skp, &smack_known_list, list) {
367 if (strncmp(skp->smk_known, smack, SMK_MAXLEN) == 0) {
368 found = 1;
Casey Schauflere114e472008-02-04 22:29:50 -0800369 break;
Etienne Basset7198e2e2009-03-24 20:53:24 +0100370 }
371 }
Casey Schauflere114e472008-02-04 22:29:50 -0800372
Etienne Basset7198e2e2009-03-24 20:53:24 +0100373 if (found == 0) {
Casey Schauflere114e472008-02-04 22:29:50 -0800374 skp = kzalloc(sizeof(struct smack_known), GFP_KERNEL);
375 if (skp != NULL) {
Casey Schauflere114e472008-02-04 22:29:50 -0800376 strncpy(skp->smk_known, smack, SMK_MAXLEN);
377 skp->smk_secid = smack_next_secid++;
378 skp->smk_cipso = NULL;
379 spin_lock_init(&skp->smk_cipsolock);
380 /*
381 * Make sure that the entry is actually
382 * filled before putting it on the list.
383 */
Etienne Basset7198e2e2009-03-24 20:53:24 +0100384 list_add_rcu(&skp->list, &smack_known_list);
Casey Schauflere114e472008-02-04 22:29:50 -0800385 }
386 }
387
388 mutex_unlock(&smack_known_lock);
389
390 return skp;
391}
392
393/**
394 * smk_import - import a smack label
395 * @string: a text string that might be a Smack label
396 * @len: the maximum size, or zero if it is NULL terminated.
397 *
398 * Returns a pointer to the label in the label list that
399 * matches the passed string, adding it if necessary.
400 */
401char *smk_import(const char *string, int len)
402{
403 struct smack_known *skp;
404
Etienne Basset43031542009-03-27 17:11:01 -0400405 /* labels cannot begin with a '-' */
406 if (string[0] == '-')
407 return NULL;
Casey Schauflere114e472008-02-04 22:29:50 -0800408 skp = smk_import_entry(string, len);
409 if (skp == NULL)
410 return NULL;
411 return skp->smk_known;
412}
413
414/**
415 * smack_from_secid - find the Smack label associated with a secid
416 * @secid: an integer that might be associated with a Smack label
417 *
418 * Returns a pointer to the appropraite Smack label if there is one,
419 * otherwise a pointer to the invalid Smack label.
420 */
421char *smack_from_secid(const u32 secid)
422{
423 struct smack_known *skp;
424
Etienne Basset7198e2e2009-03-24 20:53:24 +0100425 rcu_read_lock();
426 list_for_each_entry_rcu(skp, &smack_known_list, list) {
427 if (skp->smk_secid == secid) {
428 rcu_read_unlock();
Casey Schauflere114e472008-02-04 22:29:50 -0800429 return skp->smk_known;
Etienne Basset7198e2e2009-03-24 20:53:24 +0100430 }
431 }
Casey Schauflere114e472008-02-04 22:29:50 -0800432
433 /*
434 * If we got this far someone asked for the translation
435 * of a secid that is not on the list.
436 */
Etienne Basset7198e2e2009-03-24 20:53:24 +0100437 rcu_read_unlock();
Casey Schauflere114e472008-02-04 22:29:50 -0800438 return smack_known_invalid.smk_known;
439}
440
441/**
442 * smack_to_secid - find the secid associated with a Smack label
443 * @smack: the Smack label
444 *
445 * Returns the appropriate secid if there is one,
446 * otherwise 0
447 */
448u32 smack_to_secid(const char *smack)
449{
450 struct smack_known *skp;
451
Etienne Basset7198e2e2009-03-24 20:53:24 +0100452 rcu_read_lock();
453 list_for_each_entry_rcu(skp, &smack_known_list, list) {
454 if (strncmp(skp->smk_known, smack, SMK_MAXLEN) == 0) {
455 rcu_read_unlock();
Casey Schauflere114e472008-02-04 22:29:50 -0800456 return skp->smk_secid;
Etienne Basset7198e2e2009-03-24 20:53:24 +0100457 }
458 }
459 rcu_read_unlock();
Casey Schauflere114e472008-02-04 22:29:50 -0800460 return 0;
461}
462
463/**
464 * smack_from_cipso - find the Smack label associated with a CIPSO option
465 * @level: Bell & LaPadula level from the network
466 * @cp: Bell & LaPadula categories from the network
467 * @result: where to put the Smack value
468 *
469 * This is a simple lookup in the label table.
470 *
471 * This is an odd duck as far as smack handling goes in that
472 * it sends back a copy of the smack label rather than a pointer
473 * to the master list. This is done because it is possible for
474 * a foreign host to send a smack label that is new to this
475 * machine and hence not on the list. That would not be an
476 * issue except that adding an entry to the master list can't
477 * be done at that point.
478 */
479void smack_from_cipso(u32 level, char *cp, char *result)
480{
481 struct smack_known *kp;
482 char *final = NULL;
483
Etienne Basset7198e2e2009-03-24 20:53:24 +0100484 rcu_read_lock();
485 list_for_each_entry(kp, &smack_known_list, list) {
Casey Schauflere114e472008-02-04 22:29:50 -0800486 if (kp->smk_cipso == NULL)
487 continue;
488
489 spin_lock_bh(&kp->smk_cipsolock);
490
491 if (kp->smk_cipso->smk_level == level &&
492 memcmp(kp->smk_cipso->smk_catset, cp, SMK_LABELLEN) == 0)
493 final = kp->smk_known;
494
495 spin_unlock_bh(&kp->smk_cipsolock);
496 }
Etienne Basset7198e2e2009-03-24 20:53:24 +0100497 rcu_read_unlock();
Casey Schauflere114e472008-02-04 22:29:50 -0800498 if (final == NULL)
499 final = smack_known_huh.smk_known;
500 strncpy(result, final, SMK_MAXLEN);
501 return;
502}
503
504/**
505 * smack_to_cipso - find the CIPSO option to go with a Smack label
506 * @smack: a pointer to the smack label in question
507 * @cp: where to put the result
508 *
509 * Returns zero if a value is available, non-zero otherwise.
510 */
511int smack_to_cipso(const char *smack, struct smack_cipso *cp)
512{
513 struct smack_known *kp;
Etienne Basset7198e2e2009-03-24 20:53:24 +0100514 int found = 0;
Casey Schauflere114e472008-02-04 22:29:50 -0800515
Etienne Basset7198e2e2009-03-24 20:53:24 +0100516 rcu_read_lock();
517 list_for_each_entry_rcu(kp, &smack_known_list, list) {
Casey Schauflere114e472008-02-04 22:29:50 -0800518 if (kp->smk_known == smack ||
Etienne Basset7198e2e2009-03-24 20:53:24 +0100519 strcmp(kp->smk_known, smack) == 0) {
520 found = 1;
Casey Schauflere114e472008-02-04 22:29:50 -0800521 break;
Etienne Basset7198e2e2009-03-24 20:53:24 +0100522 }
523 }
524 rcu_read_unlock();
Casey Schauflere114e472008-02-04 22:29:50 -0800525
Etienne Basset7198e2e2009-03-24 20:53:24 +0100526 if (found == 0 || kp->smk_cipso == NULL)
Casey Schauflere114e472008-02-04 22:29:50 -0800527 return -ENOENT;
528
529 memcpy(cp, kp->smk_cipso, sizeof(struct smack_cipso));
530 return 0;
531}