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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>
14#include <linux/fs.h>
15#include <linux/sched.h>
16#include "smack.h"
17
Casey Schauflere114e472008-02-04 22:29:50 -080018struct smack_known smack_known_huh = {
Casey Schauflere114e472008-02-04 22:29:50 -080019 .smk_known = "?",
20 .smk_secid = 2,
21 .smk_cipso = NULL,
22};
23
24struct smack_known smack_known_hat = {
Casey Schauflere114e472008-02-04 22:29:50 -080025 .smk_known = "^",
26 .smk_secid = 3,
27 .smk_cipso = NULL,
28};
29
30struct smack_known smack_known_star = {
Casey Schauflere114e472008-02-04 22:29:50 -080031 .smk_known = "*",
32 .smk_secid = 4,
33 .smk_cipso = NULL,
34};
35
36struct smack_known smack_known_floor = {
Casey Schauflere114e472008-02-04 22:29:50 -080037 .smk_known = "_",
38 .smk_secid = 5,
39 .smk_cipso = NULL,
40};
41
42struct smack_known smack_known_invalid = {
Casey Schauflere114e472008-02-04 22:29:50 -080043 .smk_known = "",
44 .smk_secid = 6,
45 .smk_cipso = NULL,
46};
47
Casey Schaufler6d3dc072008-12-31 12:54:12 -050048struct smack_known smack_known_web = {
Casey Schaufler6d3dc072008-12-31 12:54:12 -050049 .smk_known = "@",
50 .smk_secid = 7,
51 .smk_cipso = NULL,
52};
53
Etienne Basset7198e2e2009-03-24 20:53:24 +010054LIST_HEAD(smack_known_list);
Casey Schauflere114e472008-02-04 22:29:50 -080055
56/*
57 * The initial value needs to be bigger than any of the
58 * known values above.
59 */
60static u32 smack_next_secid = 10;
61
Etienne Bassetecfcc532009-04-08 20:40:06 +020062/*
63 * what events do we log
64 * can be overwritten at run-time by /smack/logging
65 */
66int log_policy = SMACK_AUDIT_DENIED;
67
Casey Schauflere114e472008-02-04 22:29:50 -080068/**
69 * smk_access - determine if a subject has a specific access to an object
70 * @subject_label: a pointer to the subject's Smack label
71 * @object_label: a pointer to the object's Smack label
72 * @request: the access requested, in "MAY" format
Etienne Bassetecfcc532009-04-08 20:40:06 +020073 * @a : a pointer to the audit data
Casey Schauflere114e472008-02-04 22:29:50 -080074 *
75 * This function looks up the subject/object pair in the
76 * access rule list and returns 0 if the access is permitted,
77 * non zero otherwise.
78 *
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 */
Etienne Bassetecfcc532009-04-08 20:40:06 +020088int smk_access(char *subject_label, char *object_label, int request,
89 struct smk_audit_info *a)
Casey Schauflere114e472008-02-04 22:29:50 -080090{
91 u32 may = MAY_NOT;
Casey Schauflere114e472008-02-04 22:29:50 -080092 struct smack_rule *srp;
Etienne Bassetecfcc532009-04-08 20:40:06 +020093 int rc = 0;
Casey Schauflere114e472008-02-04 22:29:50 -080094
95 /*
96 * Hardcoded comparisons.
97 *
98 * A star subject can't access any object.
99 */
100 if (subject_label == smack_known_star.smk_known ||
Etienne Bassetecfcc532009-04-08 20:40:06 +0200101 strcmp(subject_label, smack_known_star.smk_known) == 0) {
102 rc = -EACCES;
103 goto out_audit;
104 }
Casey Schauflere114e472008-02-04 22:29:50 -0800105 /*
Casey Schaufler6d3dc072008-12-31 12:54:12 -0500106 * An internet object can be accessed by any subject.
107 * Tasks cannot be assigned the internet label.
108 * An internet subject can access any object.
109 */
110 if (object_label == smack_known_web.smk_known ||
111 subject_label == smack_known_web.smk_known ||
112 strcmp(object_label, smack_known_web.smk_known) == 0 ||
113 strcmp(subject_label, smack_known_web.smk_known) == 0)
Etienne Bassetecfcc532009-04-08 20:40:06 +0200114 goto out_audit;
Casey Schaufler6d3dc072008-12-31 12:54:12 -0500115 /*
Casey Schauflere114e472008-02-04 22:29:50 -0800116 * A star object can be accessed by any subject.
117 */
118 if (object_label == smack_known_star.smk_known ||
119 strcmp(object_label, smack_known_star.smk_known) == 0)
Etienne Bassetecfcc532009-04-08 20:40:06 +0200120 goto out_audit;
Casey Schauflere114e472008-02-04 22:29:50 -0800121 /*
122 * An object can be accessed in any way by a subject
123 * with the same label.
124 */
125 if (subject_label == object_label ||
126 strcmp(subject_label, object_label) == 0)
Etienne Bassetecfcc532009-04-08 20:40:06 +0200127 goto out_audit;
Casey Schauflere114e472008-02-04 22:29:50 -0800128 /*
129 * A hat subject can read any object.
130 * A floor object can be read by any subject.
131 */
132 if ((request & MAY_ANYREAD) == request) {
133 if (object_label == smack_known_floor.smk_known ||
134 strcmp(object_label, smack_known_floor.smk_known) == 0)
Etienne Bassetecfcc532009-04-08 20:40:06 +0200135 goto out_audit;
Casey Schauflere114e472008-02-04 22:29:50 -0800136 if (subject_label == smack_known_hat.smk_known ||
137 strcmp(subject_label, smack_known_hat.smk_known) == 0)
Etienne Bassetecfcc532009-04-08 20:40:06 +0200138 goto out_audit;
Casey Schauflere114e472008-02-04 22:29:50 -0800139 }
140 /*
141 * Beyond here an explicit relationship is required.
142 * If the requested access is contained in the available
143 * access (e.g. read is included in readwrite) it's
144 * good.
145 */
Etienne Basset7198e2e2009-03-24 20:53:24 +0100146 rcu_read_lock();
147 list_for_each_entry_rcu(srp, &smack_rule_list, list) {
Casey Schauflere114e472008-02-04 22:29:50 -0800148 if (srp->smk_subject == subject_label ||
149 strcmp(srp->smk_subject, subject_label) == 0) {
150 if (srp->smk_object == object_label ||
151 strcmp(srp->smk_object, object_label) == 0) {
152 may = srp->smk_access;
153 break;
154 }
155 }
156 }
Etienne Basset7198e2e2009-03-24 20:53:24 +0100157 rcu_read_unlock();
Casey Schauflere114e472008-02-04 22:29:50 -0800158 /*
159 * This is a bit map operation.
160 */
161 if ((request & may) == request)
Etienne Bassetecfcc532009-04-08 20:40:06 +0200162 goto out_audit;
Casey Schauflere114e472008-02-04 22:29:50 -0800163
Etienne Bassetecfcc532009-04-08 20:40:06 +0200164 rc = -EACCES;
165out_audit:
166#ifdef CONFIG_AUDIT
167 if (a)
168 smack_log(subject_label, object_label, request, rc, a);
169#endif
170 return rc;
Casey Schauflere114e472008-02-04 22:29:50 -0800171}
172
173/**
174 * smk_curacc - determine if current has a specific access to an object
Randy Dunlap251a2a92009-02-18 11:42:33 -0800175 * @obj_label: a pointer to the object's Smack label
176 * @mode: the access requested, in "MAY" format
Etienne Bassetecfcc532009-04-08 20:40:06 +0200177 * @a : common audit data
Casey Schauflere114e472008-02-04 22:29:50 -0800178 *
179 * This function checks the current subject label/object label pair
180 * in the access rule list and returns 0 if the access is permitted,
Casey Schaufler15446232008-07-30 15:37:11 -0700181 * non zero otherwise. It allows that current may have the capability
Casey Schauflere114e472008-02-04 22:29:50 -0800182 * to override the rules.
183 */
Etienne Bassetecfcc532009-04-08 20:40:06 +0200184int smk_curacc(char *obj_label, u32 mode, struct smk_audit_info *a)
Casey Schauflere114e472008-02-04 22:29:50 -0800185{
186 int rc;
Etienne Bassetecfcc532009-04-08 20:40:06 +0200187 char *sp = current_security();
Casey Schauflere114e472008-02-04 22:29:50 -0800188
Etienne Bassetecfcc532009-04-08 20:40:06 +0200189 rc = smk_access(sp, obj_label, mode, NULL);
Casey Schauflere114e472008-02-04 22:29:50 -0800190 if (rc == 0)
Etienne Bassetecfcc532009-04-08 20:40:06 +0200191 goto out_audit;
Casey Schauflere114e472008-02-04 22:29:50 -0800192
Casey Schaufler15446232008-07-30 15:37:11 -0700193 /*
194 * Return if a specific label has been designated as the
195 * only one that gets privilege and current does not
196 * have that label.
197 */
David Howellsb6dff3e2008-11-14 10:39:16 +1100198 if (smack_onlycap != NULL && smack_onlycap != current->cred->security)
Etienne Bassetecfcc532009-04-08 20:40:06 +0200199 goto out_audit;
Casey Schaufler15446232008-07-30 15:37:11 -0700200
Casey Schauflere114e472008-02-04 22:29:50 -0800201 if (capable(CAP_MAC_OVERRIDE))
202 return 0;
203
Etienne Bassetecfcc532009-04-08 20:40:06 +0200204out_audit:
205#ifdef CONFIG_AUDIT
206 if (a)
207 smack_log(sp, obj_label, mode, rc, a);
208#endif
Casey Schauflere114e472008-02-04 22:29:50 -0800209 return rc;
210}
211
Etienne Bassetecfcc532009-04-08 20:40:06 +0200212#ifdef CONFIG_AUDIT
213/**
214 * smack_str_from_perm : helper to transalate an int to a
215 * readable string
216 * @string : the string to fill
217 * @access : the int
218 *
219 */
220static inline void smack_str_from_perm(char *string, int access)
221{
222 int i = 0;
223 if (access & MAY_READ)
224 string[i++] = 'r';
225 if (access & MAY_WRITE)
226 string[i++] = 'w';
227 if (access & MAY_EXEC)
228 string[i++] = 'x';
229 if (access & MAY_APPEND)
230 string[i++] = 'a';
231 string[i] = '\0';
232}
233/**
234 * smack_log_callback - SMACK specific information
235 * will be called by generic audit code
236 * @ab : the audit_buffer
237 * @a : audit_data
238 *
239 */
240static void smack_log_callback(struct audit_buffer *ab, void *a)
241{
242 struct common_audit_data *ad = a;
Thomas Liud4131de2009-07-09 10:00:30 -0400243 struct smack_audit_data *sad = &ad->smack_audit_data;
Thomas Liued5215a2009-07-09 10:00:29 -0400244 audit_log_format(ab, "lsm=SMACK fn=%s action=%s",
Thomas Liud4131de2009-07-09 10:00:30 -0400245 ad->smack_audit_data.function,
Etienne Bassetecfcc532009-04-08 20:40:06 +0200246 sad->result ? "denied" : "granted");
247 audit_log_format(ab, " subject=");
248 audit_log_untrustedstring(ab, sad->subject);
249 audit_log_format(ab, " object=");
250 audit_log_untrustedstring(ab, sad->object);
251 audit_log_format(ab, " requested=%s", sad->request);
252}
253
254/**
255 * smack_log - Audit the granting or denial of permissions.
256 * @subject_label : smack label of the requester
257 * @object_label : smack label of the object being accessed
258 * @request: requested permissions
259 * @result: result from smk_access
260 * @a: auxiliary audit data
261 *
262 * Audit the granting or denial of permissions in accordance
263 * with the policy.
264 */
265void smack_log(char *subject_label, char *object_label, int request,
266 int result, struct smk_audit_info *ad)
267{
268 char request_buffer[SMK_NUM_ACCESS_TYPE + 1];
269 struct smack_audit_data *sad;
270 struct common_audit_data *a = &ad->a;
271
272 /* check if we have to log the current event */
273 if (result != 0 && (log_policy & SMACK_AUDIT_DENIED) == 0)
274 return;
275 if (result == 0 && (log_policy & SMACK_AUDIT_ACCEPT) == 0)
276 return;
277
Thomas Liud4131de2009-07-09 10:00:30 -0400278 if (a->smack_audit_data.function == NULL)
279 a->smack_audit_data.function = "unknown";
Etienne Bassetecfcc532009-04-08 20:40:06 +0200280
281 /* end preparing the audit data */
Thomas Liud4131de2009-07-09 10:00:30 -0400282 sad = &a->smack_audit_data;
Etienne Bassetecfcc532009-04-08 20:40:06 +0200283 smack_str_from_perm(request_buffer, request);
284 sad->subject = subject_label;
285 sad->object = object_label;
286 sad->request = request_buffer;
287 sad->result = result;
288 a->lsm_pre_audit = smack_log_callback;
289
290 common_lsm_audit(a);
291}
292#else /* #ifdef CONFIG_AUDIT */
293void smack_log(char *subject_label, char *object_label, int request,
294 int result, struct smk_audit_info *ad)
295{
296}
297#endif
298
Casey Schauflere114e472008-02-04 22:29:50 -0800299static DEFINE_MUTEX(smack_known_lock);
300
301/**
302 * smk_import_entry - import a label, return the list entry
303 * @string: a text string that might be a Smack label
304 * @len: the maximum size, or zero if it is NULL terminated.
305 *
306 * Returns a pointer to the entry in the label list that
307 * matches the passed string, adding it if necessary.
308 */
309struct smack_known *smk_import_entry(const char *string, int len)
310{
311 struct smack_known *skp;
312 char smack[SMK_LABELLEN];
313 int found;
314 int i;
315
316 if (len <= 0 || len > SMK_MAXLEN)
317 len = SMK_MAXLEN;
318
319 for (i = 0, found = 0; i < SMK_LABELLEN; i++) {
320 if (found)
321 smack[i] = '\0';
322 else if (i >= len || string[i] > '~' || string[i] <= ' ' ||
Etienne Bassetecfcc532009-04-08 20:40:06 +0200323 string[i] == '/' || string[i] == '"' ||
324 string[i] == '\\' || string[i] == '\'') {
Casey Schauflere114e472008-02-04 22:29:50 -0800325 smack[i] = '\0';
326 found = 1;
327 } else
328 smack[i] = string[i];
329 }
330
331 if (smack[0] == '\0')
332 return NULL;
333
334 mutex_lock(&smack_known_lock);
335
Etienne Basset7198e2e2009-03-24 20:53:24 +0100336 found = 0;
337 list_for_each_entry_rcu(skp, &smack_known_list, list) {
338 if (strncmp(skp->smk_known, smack, SMK_MAXLEN) == 0) {
339 found = 1;
Casey Schauflere114e472008-02-04 22:29:50 -0800340 break;
Etienne Basset7198e2e2009-03-24 20:53:24 +0100341 }
342 }
Casey Schauflere114e472008-02-04 22:29:50 -0800343
Etienne Basset7198e2e2009-03-24 20:53:24 +0100344 if (found == 0) {
Casey Schauflere114e472008-02-04 22:29:50 -0800345 skp = kzalloc(sizeof(struct smack_known), GFP_KERNEL);
346 if (skp != NULL) {
Casey Schauflere114e472008-02-04 22:29:50 -0800347 strncpy(skp->smk_known, smack, SMK_MAXLEN);
348 skp->smk_secid = smack_next_secid++;
349 skp->smk_cipso = NULL;
350 spin_lock_init(&skp->smk_cipsolock);
351 /*
352 * Make sure that the entry is actually
353 * filled before putting it on the list.
354 */
Etienne Basset7198e2e2009-03-24 20:53:24 +0100355 list_add_rcu(&skp->list, &smack_known_list);
Casey Schauflere114e472008-02-04 22:29:50 -0800356 }
357 }
358
359 mutex_unlock(&smack_known_lock);
360
361 return skp;
362}
363
364/**
365 * smk_import - import a smack label
366 * @string: a text string that might be a Smack label
367 * @len: the maximum size, or zero if it is NULL terminated.
368 *
369 * Returns a pointer to the label in the label list that
370 * matches the passed string, adding it if necessary.
371 */
372char *smk_import(const char *string, int len)
373{
374 struct smack_known *skp;
375
Etienne Basset43031542009-03-27 17:11:01 -0400376 /* labels cannot begin with a '-' */
377 if (string[0] == '-')
378 return NULL;
Casey Schauflere114e472008-02-04 22:29:50 -0800379 skp = smk_import_entry(string, len);
380 if (skp == NULL)
381 return NULL;
382 return skp->smk_known;
383}
384
385/**
386 * smack_from_secid - find the Smack label associated with a secid
387 * @secid: an integer that might be associated with a Smack label
388 *
389 * Returns a pointer to the appropraite Smack label if there is one,
390 * otherwise a pointer to the invalid Smack label.
391 */
392char *smack_from_secid(const u32 secid)
393{
394 struct smack_known *skp;
395
Etienne Basset7198e2e2009-03-24 20:53:24 +0100396 rcu_read_lock();
397 list_for_each_entry_rcu(skp, &smack_known_list, list) {
398 if (skp->smk_secid == secid) {
399 rcu_read_unlock();
Casey Schauflere114e472008-02-04 22:29:50 -0800400 return skp->smk_known;
Etienne Basset7198e2e2009-03-24 20:53:24 +0100401 }
402 }
Casey Schauflere114e472008-02-04 22:29:50 -0800403
404 /*
405 * If we got this far someone asked for the translation
406 * of a secid that is not on the list.
407 */
Etienne Basset7198e2e2009-03-24 20:53:24 +0100408 rcu_read_unlock();
Casey Schauflere114e472008-02-04 22:29:50 -0800409 return smack_known_invalid.smk_known;
410}
411
412/**
413 * smack_to_secid - find the secid associated with a Smack label
414 * @smack: the Smack label
415 *
416 * Returns the appropriate secid if there is one,
417 * otherwise 0
418 */
419u32 smack_to_secid(const char *smack)
420{
421 struct smack_known *skp;
422
Etienne Basset7198e2e2009-03-24 20:53:24 +0100423 rcu_read_lock();
424 list_for_each_entry_rcu(skp, &smack_known_list, list) {
425 if (strncmp(skp->smk_known, smack, SMK_MAXLEN) == 0) {
426 rcu_read_unlock();
Casey Schauflere114e472008-02-04 22:29:50 -0800427 return skp->smk_secid;
Etienne Basset7198e2e2009-03-24 20:53:24 +0100428 }
429 }
430 rcu_read_unlock();
Casey Schauflere114e472008-02-04 22:29:50 -0800431 return 0;
432}
433
434/**
435 * smack_from_cipso - find the Smack label associated with a CIPSO option
436 * @level: Bell & LaPadula level from the network
437 * @cp: Bell & LaPadula categories from the network
438 * @result: where to put the Smack value
439 *
440 * This is a simple lookup in the label table.
441 *
442 * This is an odd duck as far as smack handling goes in that
443 * it sends back a copy of the smack label rather than a pointer
444 * to the master list. This is done because it is possible for
445 * a foreign host to send a smack label that is new to this
446 * machine and hence not on the list. That would not be an
447 * issue except that adding an entry to the master list can't
448 * be done at that point.
449 */
450void smack_from_cipso(u32 level, char *cp, char *result)
451{
452 struct smack_known *kp;
453 char *final = NULL;
454
Etienne Basset7198e2e2009-03-24 20:53:24 +0100455 rcu_read_lock();
456 list_for_each_entry(kp, &smack_known_list, list) {
Casey Schauflere114e472008-02-04 22:29:50 -0800457 if (kp->smk_cipso == NULL)
458 continue;
459
460 spin_lock_bh(&kp->smk_cipsolock);
461
462 if (kp->smk_cipso->smk_level == level &&
463 memcmp(kp->smk_cipso->smk_catset, cp, SMK_LABELLEN) == 0)
464 final = kp->smk_known;
465
466 spin_unlock_bh(&kp->smk_cipsolock);
467 }
Etienne Basset7198e2e2009-03-24 20:53:24 +0100468 rcu_read_unlock();
Casey Schauflere114e472008-02-04 22:29:50 -0800469 if (final == NULL)
470 final = smack_known_huh.smk_known;
471 strncpy(result, final, SMK_MAXLEN);
472 return;
473}
474
475/**
476 * smack_to_cipso - find the CIPSO option to go with a Smack label
477 * @smack: a pointer to the smack label in question
478 * @cp: where to put the result
479 *
480 * Returns zero if a value is available, non-zero otherwise.
481 */
482int smack_to_cipso(const char *smack, struct smack_cipso *cp)
483{
484 struct smack_known *kp;
Etienne Basset7198e2e2009-03-24 20:53:24 +0100485 int found = 0;
Casey Schauflere114e472008-02-04 22:29:50 -0800486
Etienne Basset7198e2e2009-03-24 20:53:24 +0100487 rcu_read_lock();
488 list_for_each_entry_rcu(kp, &smack_known_list, list) {
Casey Schauflere114e472008-02-04 22:29:50 -0800489 if (kp->smk_known == smack ||
Etienne Basset7198e2e2009-03-24 20:53:24 +0100490 strcmp(kp->smk_known, smack) == 0) {
491 found = 1;
Casey Schauflere114e472008-02-04 22:29:50 -0800492 break;
Etienne Basset7198e2e2009-03-24 20:53:24 +0100493 }
494 }
495 rcu_read_unlock();
Casey Schauflere114e472008-02-04 22:29:50 -0800496
Etienne Basset7198e2e2009-03-24 20:53:24 +0100497 if (found == 0 || kp->smk_cipso == NULL)
Casey Schauflere114e472008-02-04 22:29:50 -0800498 return -ENOENT;
499
500 memcpy(cp, kp->smk_cipso, sizeof(struct smack_cipso));
501 return 0;
502}