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1/*
2 * AppArmor security module
3 *
4 * This file contains AppArmor policy attachment and domain transitions
5 *
6 * Copyright (C) 2002-2008 Novell/SUSE
7 * Copyright 2009-2010 Canonical Ltd.
8 *
9 * This program is free software; you can redistribute it and/or
10 * modify it under the terms of the GNU General Public License as
11 * published by the Free Software Foundation, version 2 of the
12 * License.
13 */
14
15#include <linux/errno.h>
16#include <linux/fdtable.h>
17#include <linux/file.h>
18#include <linux/mount.h>
19#include <linux/syscalls.h>
20#include <linux/tracehook.h>
21#include <linux/personality.h>
22#include <linux/xattr.h>
23
24#include "include/audit.h"
25#include "include/apparmorfs.h"
26#include "include/cred.h"
27#include "include/domain.h"
28#include "include/file.h"
29#include "include/ipc.h"
30#include "include/match.h"
31#include "include/path.h"
32#include "include/policy.h"
33#include "include/policy_ns.h"
34
35/**
36 * aa_free_domain_entries - free entries in a domain table
37 * @domain: the domain table to free (MAYBE NULL)
38 */
39void aa_free_domain_entries(struct aa_domain *domain)
40{
41 int i;
42 if (domain) {
43 if (!domain->table)
44 return;
45
46 for (i = 0; i < domain->size; i++)
47 kzfree(domain->table[i]);
48 kzfree(domain->table);
49 domain->table = NULL;
50 }
51}
52
53/**
54 * may_change_ptraced_domain - check if can change profile on ptraced task
55 * @to_label: profile to change to (NOT NULL)
56 * @info: message if there is an error
57 *
58 * Check if current is ptraced and if so if the tracing task is allowed
59 * to trace the new domain
60 *
61 * Returns: %0 or error if change not allowed
62 */
63static int may_change_ptraced_domain(struct aa_label *to_label,
64 const char **info)
65{
66 struct task_struct *tracer;
67 struct aa_label *tracerl = NULL;
68 int error = 0;
69
70 rcu_read_lock();
71 tracer = ptrace_parent(current);
72 if (tracer)
73 /* released below */
74 tracerl = aa_get_task_label(tracer);
75
76 /* not ptraced */
77 if (!tracer || unconfined(tracerl))
78 goto out;
79
80 error = aa_may_ptrace(tracerl, to_label, PTRACE_MODE_ATTACH);
81
82out:
83 rcu_read_unlock();
84 aa_put_label(tracerl);
85
86 if (error)
87 *info = "ptrace prevents transition";
88 return error;
89}
90
91/**** TODO: dedup to aa_label_match - needs perm and dfa, merging
92 * specifically this is an exact copy of aa_label_match except
93 * aa_compute_perms is replaced with aa_compute_fperms
94 * and policy.dfa with file.dfa
95 ****/
96/* match a profile and its associated ns component if needed
97 * Assumes visibility test has already been done.
98 * If a subns profile is not to be matched should be prescreened with
99 * visibility test.
100 */
101static inline unsigned int match_component(struct aa_profile *profile,
102 struct aa_profile *tp,
103 bool stack, unsigned int state)
104{
105 const char *ns_name;
106
107 if (stack)
108 state = aa_dfa_match(profile->file.dfa, state, "&");
109 if (profile->ns == tp->ns)
110 return aa_dfa_match(profile->file.dfa, state, tp->base.hname);
111
112 /* try matching with namespace name and then profile */
113 ns_name = aa_ns_name(profile->ns, tp->ns, true);
114 state = aa_dfa_match_len(profile->file.dfa, state, ":", 1);
115 state = aa_dfa_match(profile->file.dfa, state, ns_name);
116 state = aa_dfa_match_len(profile->file.dfa, state, ":", 1);
117 return aa_dfa_match(profile->file.dfa, state, tp->base.hname);
118}
119
120/**
121 * label_compound_match - find perms for full compound label
122 * @profile: profile to find perms for
123 * @label: label to check access permissions for
124 * @stack: whether this is a stacking request
125 * @start: state to start match in
126 * @subns: whether to do permission checks on components in a subns
127 * @request: permissions to request
128 * @perms: perms struct to set
129 *
130 * Returns: 0 on success else ERROR
131 *
132 * For the label A//&B//&C this does the perm match for A//&B//&C
133 * @perms should be preinitialized with allperms OR a previous permission
134 * check to be stacked.
135 */
136static int label_compound_match(struct aa_profile *profile,
137 struct aa_label *label, bool stack,
138 unsigned int state, bool subns, u32 request,
139 struct aa_perms *perms)
140{
141 struct aa_profile *tp;
142 struct label_it i;
143 struct path_cond cond = { };
144
145 /* find first subcomponent that is visible */
146 label_for_each(i, label, tp) {
147 if (!aa_ns_visible(profile->ns, tp->ns, subns))
148 continue;
149 state = match_component(profile, tp, stack, state);
150 if (!state)
151 goto fail;
152 goto next;
153 }
154
155 /* no component visible */
156 *perms = allperms;
157 return 0;
158
159next:
160 label_for_each_cont(i, label, tp) {
161 if (!aa_ns_visible(profile->ns, tp->ns, subns))
162 continue;
163 state = aa_dfa_match(profile->file.dfa, state, "//&");
164 state = match_component(profile, tp, false, state);
165 if (!state)
166 goto fail;
167 }
168 *perms = aa_compute_fperms(profile->file.dfa, state, &cond);
169 aa_apply_modes_to_perms(profile, perms);
170 if ((perms->allow & request) != request)
171 return -EACCES;
172
173 return 0;
174
175fail:
176 *perms = nullperms;
177 return -EACCES;
178}
179
180/**
181 * label_components_match - find perms for all subcomponents of a label
182 * @profile: profile to find perms for
183 * @label: label to check access permissions for
184 * @stack: whether this is a stacking request
185 * @start: state to start match in
186 * @subns: whether to do permission checks on components in a subns
187 * @request: permissions to request
188 * @perms: an initialized perms struct to add accumulation to
189 *
190 * Returns: 0 on success else ERROR
191 *
192 * For the label A//&B//&C this does the perm match for each of A and B and C
193 * @perms should be preinitialized with allperms OR a previous permission
194 * check to be stacked.
195 */
196static int label_components_match(struct aa_profile *profile,
197 struct aa_label *label, bool stack,
198 unsigned int start, bool subns, u32 request,
199 struct aa_perms *perms)
200{
201 struct aa_profile *tp;
202 struct label_it i;
203 struct aa_perms tmp;
204 struct path_cond cond = { };
205 unsigned int state = 0;
206
207 /* find first subcomponent to test */
208 label_for_each(i, label, tp) {
209 if (!aa_ns_visible(profile->ns, tp->ns, subns))
210 continue;
211 state = match_component(profile, tp, stack, start);
212 if (!state)
213 goto fail;
214 goto next;
215 }
216
217 /* no subcomponents visible - no change in perms */
218 return 0;
219
220next:
221 tmp = aa_compute_fperms(profile->file.dfa, state, &cond);
222 aa_apply_modes_to_perms(profile, &tmp);
223 aa_perms_accum(perms, &tmp);
224 label_for_each_cont(i, label, tp) {
225 if (!aa_ns_visible(profile->ns, tp->ns, subns))
226 continue;
227 state = match_component(profile, tp, stack, start);
228 if (!state)
229 goto fail;
230 tmp = aa_compute_fperms(profile->file.dfa, state, &cond);
231 aa_apply_modes_to_perms(profile, &tmp);
232 aa_perms_accum(perms, &tmp);
233 }
234
235 if ((perms->allow & request) != request)
236 return -EACCES;
237
238 return 0;
239
240fail:
241 *perms = nullperms;
242 return -EACCES;
243}
244
245/**
246 * label_match - do a multi-component label match
247 * @profile: profile to match against (NOT NULL)
248 * @label: label to match (NOT NULL)
249 * @stack: whether this is a stacking request
250 * @state: state to start in
251 * @subns: whether to match subns components
252 * @request: permission request
253 * @perms: Returns computed perms (NOT NULL)
254 *
255 * Returns: the state the match finished in, may be the none matching state
256 */
257static int label_match(struct aa_profile *profile, struct aa_label *label,
258 bool stack, unsigned int state, bool subns, u32 request,
259 struct aa_perms *perms)
260{
261 int error;
262
263 *perms = nullperms;
264 error = label_compound_match(profile, label, stack, state, subns,
265 request, perms);
266 if (!error)
267 return error;
268
269 *perms = allperms;
270 return label_components_match(profile, label, stack, state, subns,
271 request, perms);
272}
273
274/******* end TODO: dedup *****/
275
276/**
277 * change_profile_perms - find permissions for change_profile
278 * @profile: the current profile (NOT NULL)
279 * @target: label to transition to (NOT NULL)
280 * @stack: whether this is a stacking request
281 * @request: requested perms
282 * @start: state to start matching in
283 *
284 *
285 * Returns: permission set
286 *
287 * currently only matches full label A//&B//&C or individual components A, B, C
288 * not arbitrary combinations. Eg. A//&B, C
289 */
290static int change_profile_perms(struct aa_profile *profile,
291 struct aa_label *target, bool stack,
292 u32 request, unsigned int start,
293 struct aa_perms *perms)
294{
295 if (profile_unconfined(profile)) {
296 perms->allow = AA_MAY_CHANGE_PROFILE | AA_MAY_ONEXEC;
297 perms->audit = perms->quiet = perms->kill = 0;
298 return 0;
299 }
300
301 /* TODO: add profile in ns screening */
302 return label_match(profile, target, stack, start, true, request, perms);
303}
304
305/**
306 * aa_xattrs_match - check whether a file matches the xattrs defined in profile
307 * @bprm: binprm struct for the process to validate
308 * @profile: profile to match against (NOT NULL)
309 * @state: state to start match in
310 *
311 * Returns: number of extended attributes that matched, or < 0 on error
312 */
313static int aa_xattrs_match(const struct linux_binprm *bprm,
314 struct aa_profile *profile, unsigned int state)
315{
316 int i;
317 ssize_t size;
318 struct dentry *d;
319 char *value = NULL;
320 int value_size = 0, ret = profile->xattr_count;
321
322 if (!bprm || !profile->xattr_count)
323 return 0;
324
325 /* transition from exec match to xattr set */
326 state = aa_dfa_null_transition(profile->xmatch, state);
327
328 d = bprm->file->f_path.dentry;
329
330 for (i = 0; i < profile->xattr_count; i++) {
331 size = vfs_getxattr_alloc(d, profile->xattrs[i], &value,
332 value_size, GFP_KERNEL);
333 if (size >= 0) {
334 u32 perm;
335
336 /* Check the xattr value, not just presence */
337 state = aa_dfa_match_len(profile->xmatch, state, value,
338 size);
339 perm = dfa_user_allow(profile->xmatch, state);
340 if (!(perm & MAY_EXEC)) {
341 ret = -EINVAL;
342 goto out;
343 }
344 }
345 /* transition to next element */
346 state = aa_dfa_null_transition(profile->xmatch, state);
347 if (size < 0) {
348 /*
349 * No xattr match, so verify if transition to
350 * next element was valid. IFF so the xattr
351 * was optional.
352 */
353 if (!state) {
354 ret = -EINVAL;
355 goto out;
356 }
357 /* don't count missing optional xattr as matched */
358 ret--;
359 }
360 }
361
362out:
363 kfree(value);
364 return ret;
365}
366
367/**
368 * __attach_match_ - find an attachment match
369 * @bprm - binprm structure of transitioning task
370 * @name - to match against (NOT NULL)
371 * @head - profile list to walk (NOT NULL)
372 * @info - info message if there was an error (NOT NULL)
373 *
374 * Do a linear search on the profiles in the list. There is a matching
375 * preference where an exact match is preferred over a name which uses
376 * expressions to match, and matching expressions with the greatest
377 * xmatch_len are preferred.
378 *
379 * Requires: @head not be shared or have appropriate locks held
380 *
381 * Returns: profile or NULL if no match found
382 */
383static struct aa_profile *__attach_match(const struct linux_binprm *bprm,
384 const char *name,
385 struct list_head *head,
386 const char **info)
387{
388 int candidate_len = 0, candidate_xattrs = 0;
389 bool conflict = false;
390 struct aa_profile *profile, *candidate = NULL;
391
392 AA_BUG(!name);
393 AA_BUG(!head);
394
395 list_for_each_entry_rcu(profile, head, base.list) {
396 if (profile->label.flags & FLAG_NULL &&
397 &profile->label == ns_unconfined(profile->ns))
398 continue;
399
400 /* Find the "best" matching profile. Profiles must
401 * match the path and extended attributes (if any)
402 * associated with the file. A more specific path
403 * match will be preferred over a less specific one,
404 * and a match with more matching extended attributes
405 * will be preferred over one with fewer. If the best
406 * match has both the same level of path specificity
407 * and the same number of matching extended attributes
408 * as another profile, signal a conflict and refuse to
409 * match.
410 */
411 if (profile->xmatch) {
412 unsigned int state, count;
413 u32 perm;
414
415 state = aa_dfa_leftmatch(profile->xmatch, DFA_START,
416 name, &count);
417 perm = dfa_user_allow(profile->xmatch, state);
418 /* any accepting state means a valid match. */
419 if (perm & MAY_EXEC) {
420 int ret;
421
422 if (count < candidate_len)
423 continue;
424
425 ret = aa_xattrs_match(bprm, profile, state);
426 /* Fail matching if the xattrs don't match */
427 if (ret < 0)
428 continue;
429
430 /*
431 * TODO: allow for more flexible best match
432 *
433 * The new match isn't more specific
434 * than the current best match
435 */
436 if (count == candidate_len &&
437 ret <= candidate_xattrs) {
438 /* Match is equivalent, so conflict */
439 if (ret == candidate_xattrs)
440 conflict = true;
441 continue;
442 }
443
444 /* Either the same length with more matching
445 * xattrs, or a longer match
446 */
447 candidate = profile;
448 candidate_len = profile->xmatch_len;
449 candidate_xattrs = ret;
450 conflict = false;
451 }
452 } else if (!strcmp(profile->base.name, name))
453 /*
454 * old exact non-re match, without conditionals such
455 * as xattrs. no more searching required
456 */
457 return profile;
458 }
459
460 if (conflict) {
461 *info = "conflicting profile attachments";
462 return NULL;
463 }
464
465 return candidate;
466}
467
468/**
469 * find_attach - do attachment search for unconfined processes
470 * @bprm - binprm structure of transitioning task
471 * @ns: the current namespace (NOT NULL)
472 * @list: list to search (NOT NULL)
473 * @name: the executable name to match against (NOT NULL)
474 * @info: info message if there was an error
475 *
476 * Returns: label or NULL if no match found
477 */
478static struct aa_label *find_attach(const struct linux_binprm *bprm,
479 struct aa_ns *ns, struct list_head *list,
480 const char *name, const char **info)
481{
482 struct aa_profile *profile;
483
484 rcu_read_lock();
485 profile = aa_get_profile(__attach_match(bprm, name, list, info));
486 rcu_read_unlock();
487
488 return profile ? &profile->label : NULL;
489}
490
491static const char *next_name(int xtype, const char *name)
492{
493 return NULL;
494}
495
496/**
497 * x_table_lookup - lookup an x transition name via transition table
498 * @profile: current profile (NOT NULL)
499 * @xindex: index into x transition table
500 * @name: returns: name tested to find label (NOT NULL)
501 *
502 * Returns: refcounted label, or NULL on failure (MAYBE NULL)
503 */
504struct aa_label *x_table_lookup(struct aa_profile *profile, u32 xindex,
505 const char **name)
506{
507 struct aa_label *label = NULL;
508 u32 xtype = xindex & AA_X_TYPE_MASK;
509 int index = xindex & AA_X_INDEX_MASK;
510
511 AA_BUG(!name);
512
513 /* index is guaranteed to be in range, validated at load time */
514 /* TODO: move lookup parsing to unpack time so this is a straight
515 * index into the resultant label
516 */
517 for (*name = profile->file.trans.table[index]; !label && *name;
518 *name = next_name(xtype, *name)) {
519 if (xindex & AA_X_CHILD) {
520 struct aa_profile *new_profile;
521 /* release by caller */
522 new_profile = aa_find_child(profile, *name);
523 if (new_profile)
524 label = &new_profile->label;
525 continue;
526 }
527 label = aa_label_parse(&profile->label, *name, GFP_ATOMIC,
528 true, false);
529 if (IS_ERR(label))
530 label = NULL;
531 }
532
533 /* released by caller */
534
535 return label;
536}
537
538/**
539 * x_to_label - get target label for a given xindex
540 * @profile: current profile (NOT NULL)
541 * @bprm: binprm structure of transitioning task
542 * @name: name to lookup (NOT NULL)
543 * @xindex: index into x transition table
544 * @lookupname: returns: name used in lookup if one was specified (NOT NULL)
545 *
546 * find label for a transition index
547 *
548 * Returns: refcounted label or NULL if not found available
549 */
550static struct aa_label *x_to_label(struct aa_profile *profile,
551 const struct linux_binprm *bprm,
552 const char *name, u32 xindex,
553 const char **lookupname,
554 const char **info)
555{
556 struct aa_label *new = NULL;
557 struct aa_ns *ns = profile->ns;
558 u32 xtype = xindex & AA_X_TYPE_MASK;
559 const char *stack = NULL;
560
561 switch (xtype) {
562 case AA_X_NONE:
563 /* fail exec unless ix || ux fallback - handled by caller */
564 *lookupname = NULL;
565 break;
566 case AA_X_TABLE:
567 /* TODO: fix when perm mapping done at unload */
568 stack = profile->file.trans.table[xindex & AA_X_INDEX_MASK];
569 if (*stack != '&') {
570 /* released by caller */
571 new = x_table_lookup(profile, xindex, lookupname);
572 stack = NULL;
573 break;
574 }
575 /* fall through to X_NAME */
576 case AA_X_NAME:
577 if (xindex & AA_X_CHILD)
578 /* released by caller */
579 new = find_attach(bprm, ns, &profile->base.profiles,
580 name, info);
581 else
582 /* released by caller */
583 new = find_attach(bprm, ns, &ns->base.profiles,
584 name, info);
585 *lookupname = name;
586 break;
587 }
588
589 if (!new) {
590 if (xindex & AA_X_INHERIT) {
591 /* (p|c|n)ix - don't change profile but do
592 * use the newest version
593 */
594 *info = "ix fallback";
595 /* no profile && no error */
596 new = aa_get_newest_label(&profile->label);
597 } else if (xindex & AA_X_UNCONFINED) {
598 new = aa_get_newest_label(ns_unconfined(profile->ns));
599 *info = "ux fallback";
600 }
601 }
602
603 if (new && stack) {
604 /* base the stack on post domain transition */
605 struct aa_label *base = new;
606
607 new = aa_label_parse(base, stack, GFP_ATOMIC, true, false);
608 if (IS_ERR(new))
609 new = NULL;
610 aa_put_label(base);
611 }
612
613 /* released by caller */
614 return new;
615}
616
617static struct aa_label *profile_transition(struct aa_profile *profile,
618 const struct linux_binprm *bprm,
619 char *buffer, struct path_cond *cond,
620 bool *secure_exec)
621{
622 struct aa_label *new = NULL;
623 struct aa_profile *component;
624 struct label_it i;
625 const char *info = NULL, *name = NULL, *target = NULL;
626 unsigned int state = profile->file.start;
627 struct aa_perms perms = {};
628 bool nonewprivs = false;
629 int error = 0;
630
631 AA_BUG(!profile);
632 AA_BUG(!bprm);
633 AA_BUG(!buffer);
634
635 error = aa_path_name(&bprm->file->f_path, profile->path_flags, buffer,
636 &name, &info, profile->disconnected);
637 if (error) {
638 if (profile_unconfined(profile) ||
639 (profile->label.flags & FLAG_IX_ON_NAME_ERROR)) {
640 AA_DEBUG("name lookup ix on error");
641 error = 0;
642 new = aa_get_newest_label(&profile->label);
643 }
644 name = bprm->filename;
645 goto audit;
646 }
647
648 if (profile_unconfined(profile)) {
649 new = find_attach(bprm, profile->ns,
650 &profile->ns->base.profiles, name, &info);
651 if (new) {
652 AA_DEBUG("unconfined attached to new label");
653 return new;
654 }
655 AA_DEBUG("unconfined exec no attachment");
656 return aa_get_newest_label(&profile->label);
657 }
658
659 /* find exec permissions for name */
660 state = aa_str_perms(profile->file.dfa, state, name, cond, &perms);
661 if (perms.allow & MAY_EXEC) {
662 /* exec permission determine how to transition */
663 new = x_to_label(profile, bprm, name, perms.xindex, &target,
664 &info);
665 if (new && new->proxy == profile->label.proxy && info) {
666 /* hack ix fallback - improve how this is detected */
667 goto audit;
668 } else if (!new) {
669 error = -EACCES;
670 info = "profile transition not found";
671 /* remove MAY_EXEC to audit as failure */
672 perms.allow &= ~MAY_EXEC;
673 } else {
674 /* verify that each component's xattr requirements are
675 * met, and fail execution otherwise
676 */
677 label_for_each(i, new, component) {
678 if (aa_xattrs_match(bprm, component, state) <
679 0) {
680 error = -EACCES;
681 info = "required xattrs not present";
682 perms.allow &= ~MAY_EXEC;
683 aa_put_label(new);
684 new = NULL;
685 goto audit;
686 }
687 }
688 }
689 } else if (COMPLAIN_MODE(profile)) {
690 /* no exec permission - learning mode */
691 struct aa_profile *new_profile = NULL;
692 char *n = kstrdup(name, GFP_ATOMIC);
693
694 if (n) {
695 /* name is ptr into buffer */
696 long pos = name - buffer;
697 /* break per cpu buffer hold */
698 put_buffers(buffer);
699 new_profile = aa_new_null_profile(profile, false, n,
700 GFP_KERNEL);
701 get_buffers(buffer);
702 name = buffer + pos;
703 strcpy((char *)name, n);
704 kfree(n);
705 }
706 if (!new_profile) {
707 error = -ENOMEM;
708 info = "could not create null profile";
709 } else {
710 error = -EACCES;
711 new = &new_profile->label;
712 }
713 perms.xindex |= AA_X_UNSAFE;
714 } else
715 /* fail exec */
716 error = -EACCES;
717
718 if (!new)
719 goto audit;
720
721
722 if (!(perms.xindex & AA_X_UNSAFE)) {
723 if (DEBUG_ON) {
724 dbg_printk("apparmor: scrubbing environment variables"
725 " for %s profile=", name);
726 aa_label_printk(new, GFP_ATOMIC);
727 dbg_printk("\n");
728 }
729 *secure_exec = true;
730 }
731
732audit:
733 aa_audit_file(profile, &perms, OP_EXEC, MAY_EXEC, name, target, new,
734 cond->uid, info, error);
735 if (!new || nonewprivs) {
736 aa_put_label(new);
737 return ERR_PTR(error);
738 }
739
740 return new;
741}
742
743static int profile_onexec(struct aa_profile *profile, struct aa_label *onexec,
744 bool stack, const struct linux_binprm *bprm,
745 char *buffer, struct path_cond *cond,
746 bool *secure_exec)
747{
748 unsigned int state = profile->file.start;
749 struct aa_perms perms = {};
750 const char *xname = NULL, *info = "change_profile onexec";
751 int error = -EACCES;
752
753 AA_BUG(!profile);
754 AA_BUG(!onexec);
755 AA_BUG(!bprm);
756 AA_BUG(!buffer);
757
758 if (profile_unconfined(profile)) {
759 /* change_profile on exec already granted */
760 /*
761 * NOTE: Domain transitions from unconfined are allowed
762 * even when no_new_privs is set because this aways results
763 * in a further reduction of permissions.
764 */
765 return 0;
766 }
767
768 error = aa_path_name(&bprm->file->f_path, profile->path_flags, buffer,
769 &xname, &info, profile->disconnected);
770 if (error) {
771 if (profile_unconfined(profile) ||
772 (profile->label.flags & FLAG_IX_ON_NAME_ERROR)) {
773 AA_DEBUG("name lookup ix on error");
774 error = 0;
775 }
776 xname = bprm->filename;
777 goto audit;
778 }
779
780 /* find exec permissions for name */
781 state = aa_str_perms(profile->file.dfa, state, xname, cond, &perms);
782 if (!(perms.allow & AA_MAY_ONEXEC)) {
783 info = "no change_onexec valid for executable";
784 goto audit;
785 }
786 /* test if this exec can be paired with change_profile onexec.
787 * onexec permission is linked to exec with a standard pairing
788 * exec\0change_profile
789 */
790 state = aa_dfa_null_transition(profile->file.dfa, state);
791 error = change_profile_perms(profile, onexec, stack, AA_MAY_ONEXEC,
792 state, &perms);
793 if (error) {
794 perms.allow &= ~AA_MAY_ONEXEC;
795 goto audit;
796 }
797
798 if (!(perms.xindex & AA_X_UNSAFE)) {
799 if (DEBUG_ON) {
800 dbg_printk("apparmor: scrubbing environment "
801 "variables for %s label=", xname);
802 aa_label_printk(onexec, GFP_ATOMIC);
803 dbg_printk("\n");
804 }
805 *secure_exec = true;
806 }
807
808audit:
809 return aa_audit_file(profile, &perms, OP_EXEC, AA_MAY_ONEXEC, xname,
810 NULL, onexec, cond->uid, info, error);
811}
812
813/* ensure none ns domain transitions are correctly applied with onexec */
814
815static struct aa_label *handle_onexec(struct aa_label *label,
816 struct aa_label *onexec, bool stack,
817 const struct linux_binprm *bprm,
818 char *buffer, struct path_cond *cond,
819 bool *unsafe)
820{
821 struct aa_profile *profile;
822 struct aa_label *new;
823 int error;
824
825 AA_BUG(!label);
826 AA_BUG(!onexec);
827 AA_BUG(!bprm);
828 AA_BUG(!buffer);
829
830 if (!stack) {
831 error = fn_for_each_in_ns(label, profile,
832 profile_onexec(profile, onexec, stack,
833 bprm, buffer, cond, unsafe));
834 if (error)
835 return ERR_PTR(error);
836 new = fn_label_build_in_ns(label, profile, GFP_ATOMIC,
837 aa_get_newest_label(onexec),
838 profile_transition(profile, bprm, buffer,
839 cond, unsafe));
840
841 } else {
842 /* TODO: determine how much we want to losen this */
843 error = fn_for_each_in_ns(label, profile,
844 profile_onexec(profile, onexec, stack, bprm,
845 buffer, cond, unsafe));
846 if (error)
847 return ERR_PTR(error);
848 new = fn_label_build_in_ns(label, profile, GFP_ATOMIC,
849 aa_label_merge(&profile->label, onexec,
850 GFP_ATOMIC),
851 profile_transition(profile, bprm, buffer,
852 cond, unsafe));
853 }
854
855 if (new)
856 return new;
857
858 /* TODO: get rid of GLOBAL_ROOT_UID */
859 error = fn_for_each_in_ns(label, profile,
860 aa_audit_file(profile, &nullperms, OP_CHANGE_ONEXEC,
861 AA_MAY_ONEXEC, bprm->filename, NULL,
862 onexec, GLOBAL_ROOT_UID,
863 "failed to build target label", -ENOMEM));
864 return ERR_PTR(error);
865}
866
867/**
868 * apparmor_bprm_set_creds - set the new creds on the bprm struct
869 * @bprm: binprm for the exec (NOT NULL)
870 *
871 * Returns: %0 or error on failure
872 *
873 * TODO: once the other paths are done see if we can't refactor into a fn
874 */
875int apparmor_bprm_set_creds(struct linux_binprm *bprm)
876{
877 struct aa_task_ctx *ctx;
878 struct aa_label *label, *new = NULL;
879 struct aa_profile *profile;
880 char *buffer = NULL;
881 const char *info = NULL;
882 int error = 0;
883 bool unsafe = false;
884 struct path_cond cond = {
885 file_inode(bprm->file)->i_uid,
886 file_inode(bprm->file)->i_mode
887 };
888
889 if (bprm->called_set_creds)
890 return 0;
891
892 ctx = task_ctx(current);
893 AA_BUG(!cred_label(bprm->cred));
894 AA_BUG(!ctx);
895
896 label = aa_get_newest_label(cred_label(bprm->cred));
897
898 /*
899 * Detect no new privs being set, and store the label it
900 * occurred under. Ideally this would happen when nnp
901 * is set but there isn't a good way to do that yet.
902 *
903 * Testing for unconfined must be done before the subset test
904 */
905 if ((bprm->unsafe & LSM_UNSAFE_NO_NEW_PRIVS) && !unconfined(label) &&
906 !ctx->nnp)
907 ctx->nnp = aa_get_label(label);
908
909 /* buffer freed below, name is pointer into buffer */
910 get_buffers(buffer);
911 /* Test for onexec first as onexec override other x transitions. */
912 if (ctx->onexec)
913 new = handle_onexec(label, ctx->onexec, ctx->token,
914 bprm, buffer, &cond, &unsafe);
915 else
916 new = fn_label_build(label, profile, GFP_ATOMIC,
917 profile_transition(profile, bprm, buffer,
918 &cond, &unsafe));
919
920 AA_BUG(!new);
921 if (IS_ERR(new)) {
922 error = PTR_ERR(new);
923 goto done;
924 } else if (!new) {
925 error = -ENOMEM;
926 goto done;
927 }
928
929 /* Policy has specified a domain transitions. If no_new_privs and
930 * confined ensure the transition is to confinement that is subset
931 * of the confinement when the task entered no new privs.
932 *
933 * NOTE: Domain transitions from unconfined and to stacked
934 * subsets are allowed even when no_new_privs is set because this
935 * aways results in a further reduction of permissions.
936 */
937 if ((bprm->unsafe & LSM_UNSAFE_NO_NEW_PRIVS) &&
938 !unconfined(label) && !aa_label_is_subset(new, ctx->nnp)) {
939 error = -EPERM;
940 info = "no new privs";
941 goto audit;
942 }
943
944 if (bprm->unsafe & LSM_UNSAFE_SHARE) {
945 /* FIXME: currently don't mediate shared state */
946 ;
947 }
948
949 if (bprm->unsafe & (LSM_UNSAFE_PTRACE)) {
950 /* TODO: test needs to be profile of label to new */
951 error = may_change_ptraced_domain(new, &info);
952 if (error)
953 goto audit;
954 }
955
956 if (unsafe) {
957 if (DEBUG_ON) {
958 dbg_printk("scrubbing environment variables for %s "
959 "label=", bprm->filename);
960 aa_label_printk(new, GFP_ATOMIC);
961 dbg_printk("\n");
962 }
963 bprm->secureexec = 1;
964 }
965
966 if (label->proxy != new->proxy) {
967 /* when transitioning clear unsafe personality bits */
968 if (DEBUG_ON) {
969 dbg_printk("apparmor: clearing unsafe personality "
970 "bits. %s label=", bprm->filename);
971 aa_label_printk(new, GFP_ATOMIC);
972 dbg_printk("\n");
973 }
974 bprm->per_clear |= PER_CLEAR_ON_SETID;
975 }
976 aa_put_label(cred_label(bprm->cred));
977 /* transfer reference, released when cred is freed */
978 cred_label(bprm->cred) = new;
979
980done:
981 aa_put_label(label);
982 put_buffers(buffer);
983
984 return error;
985
986audit:
987 error = fn_for_each(label, profile,
988 aa_audit_file(profile, &nullperms, OP_EXEC, MAY_EXEC,
989 bprm->filename, NULL, new,
990 file_inode(bprm->file)->i_uid, info,
991 error));
992 aa_put_label(new);
993 goto done;
994}
995
996/*
997 * Functions for self directed profile change
998 */
999
1000
1001/* helper fn for change_hat
1002 *
1003 * Returns: label for hat transition OR ERR_PTR. Does NOT return NULL
1004 */
1005static struct aa_label *build_change_hat(struct aa_profile *profile,
1006 const char *name, bool sibling)
1007{
1008 struct aa_profile *root, *hat = NULL;
1009 const char *info = NULL;
1010 int error = 0;
1011
1012 if (sibling && PROFILE_IS_HAT(profile)) {
1013 root = aa_get_profile_rcu(&profile->parent);
1014 } else if (!sibling && !PROFILE_IS_HAT(profile)) {
1015 root = aa_get_profile(profile);
1016 } else {
1017 info = "conflicting target types";
1018 error = -EPERM;
1019 goto audit;
1020 }
1021
1022 hat = aa_find_child(root, name);
1023 if (!hat) {
1024 error = -ENOENT;
1025 if (COMPLAIN_MODE(profile)) {
1026 hat = aa_new_null_profile(profile, true, name,
1027 GFP_KERNEL);
1028 if (!hat) {
1029 info = "failed null profile create";
1030 error = -ENOMEM;
1031 }
1032 }
1033 }
1034 aa_put_profile(root);
1035
1036audit:
1037 aa_audit_file(profile, &nullperms, OP_CHANGE_HAT, AA_MAY_CHANGEHAT,
1038 name, hat ? hat->base.hname : NULL,
1039 hat ? &hat->label : NULL, GLOBAL_ROOT_UID, NULL,
1040 error);
1041 if (!hat || (error && error != -ENOENT))
1042 return ERR_PTR(error);
1043 /* if hat && error - complain mode, already audited and we adjust for
1044 * complain mode allow by returning hat->label
1045 */
1046 return &hat->label;
1047}
1048
1049/* helper fn for changing into a hat
1050 *
1051 * Returns: label for hat transition or ERR_PTR. Does not return NULL
1052 */
1053static struct aa_label *change_hat(struct aa_label *label, const char *hats[],
1054 int count, int flags)
1055{
1056 struct aa_profile *profile, *root, *hat = NULL;
1057 struct aa_label *new;
1058 struct label_it it;
1059 bool sibling = false;
1060 const char *name, *info = NULL;
1061 int i, error;
1062
1063 AA_BUG(!label);
1064 AA_BUG(!hats);
1065 AA_BUG(count < 1);
1066
1067 if (PROFILE_IS_HAT(labels_profile(label)))
1068 sibling = true;
1069
1070 /*find first matching hat */
1071 for (i = 0; i < count && !hat; i++) {
1072 name = hats[i];
1073 label_for_each_in_ns(it, labels_ns(label), label, profile) {
1074 if (sibling && PROFILE_IS_HAT(profile)) {
1075 root = aa_get_profile_rcu(&profile->parent);
1076 } else if (!sibling && !PROFILE_IS_HAT(profile)) {
1077 root = aa_get_profile(profile);
1078 } else { /* conflicting change type */
1079 info = "conflicting targets types";
1080 error = -EPERM;
1081 goto fail;
1082 }
1083 hat = aa_find_child(root, name);
1084 aa_put_profile(root);
1085 if (!hat) {
1086 if (!COMPLAIN_MODE(profile))
1087 goto outer_continue;
1088 /* complain mode succeed as if hat */
1089 } else if (!PROFILE_IS_HAT(hat)) {
1090 info = "target not hat";
1091 error = -EPERM;
1092 aa_put_profile(hat);
1093 goto fail;
1094 }
1095 aa_put_profile(hat);
1096 }
1097 /* found a hat for all profiles in ns */
1098 goto build;
1099outer_continue:
1100 ;
1101 }
1102 /* no hats that match, find appropriate error
1103 *
1104 * In complain mode audit of the failure is based off of the first
1105 * hat supplied. This is done due how userspace interacts with
1106 * change_hat.
1107 */
1108 name = NULL;
1109 label_for_each_in_ns(it, labels_ns(label), label, profile) {
1110 if (!list_empty(&profile->base.profiles)) {
1111 info = "hat not found";
1112 error = -ENOENT;
1113 goto fail;
1114 }
1115 }
1116 info = "no hats defined";
1117 error = -ECHILD;
1118
1119fail:
1120 label_for_each_in_ns(it, labels_ns(label), label, profile) {
1121 /*
1122 * no target as it has failed to be found or built
1123 *
1124 * change_hat uses probing and should not log failures
1125 * related to missing hats
1126 */
1127 /* TODO: get rid of GLOBAL_ROOT_UID */
1128 if (count > 1 || COMPLAIN_MODE(profile)) {
1129 aa_audit_file(profile, &nullperms, OP_CHANGE_HAT,
1130 AA_MAY_CHANGEHAT, name, NULL, NULL,
1131 GLOBAL_ROOT_UID, info, error);
1132 }
1133 }
1134 return ERR_PTR(error);
1135
1136build:
1137 new = fn_label_build_in_ns(label, profile, GFP_KERNEL,
1138 build_change_hat(profile, name, sibling),
1139 aa_get_label(&profile->label));
1140 if (!new) {
1141 info = "label build failed";
1142 error = -ENOMEM;
1143 goto fail;
1144 } /* else if (IS_ERR) build_change_hat has logged error so return new */
1145
1146 return new;
1147}
1148
1149/**
1150 * aa_change_hat - change hat to/from subprofile
1151 * @hats: vector of hat names to try changing into (MAYBE NULL if @count == 0)
1152 * @count: number of hat names in @hats
1153 * @token: magic value to validate the hat change
1154 * @flags: flags affecting behavior of the change
1155 *
1156 * Returns %0 on success, error otherwise.
1157 *
1158 * Change to the first profile specified in @hats that exists, and store
1159 * the @hat_magic in the current task context. If the count == 0 and the
1160 * @token matches that stored in the current task context, return to the
1161 * top level profile.
1162 *
1163 * change_hat only applies to profiles in the current ns, and each profile
1164 * in the ns must make the same transition otherwise change_hat will fail.
1165 */
1166int aa_change_hat(const char *hats[], int count, u64 token, int flags)
1167{
1168 const struct cred *cred;
1169 struct aa_task_ctx *ctx = task_ctx(current);
1170 struct aa_label *label, *previous, *new = NULL, *target = NULL;
1171 struct aa_profile *profile;
1172 struct aa_perms perms = {};
1173 const char *info = NULL;
1174 int error = 0;
1175
1176 /* released below */
1177 cred = get_current_cred();
1178 label = aa_get_newest_cred_label(cred);
1179 previous = aa_get_newest_label(ctx->previous);
1180
1181 /*
1182 * Detect no new privs being set, and store the label it
1183 * occurred under. Ideally this would happen when nnp
1184 * is set but there isn't a good way to do that yet.
1185 *
1186 * Testing for unconfined must be done before the subset test
1187 */
1188 if (task_no_new_privs(current) && !unconfined(label) && !ctx->nnp)
1189 ctx->nnp = aa_get_label(label);
1190
1191 if (unconfined(label)) {
1192 info = "unconfined can not change_hat";
1193 error = -EPERM;
1194 goto fail;
1195 }
1196
1197 if (count) {
1198 new = change_hat(label, hats, count, flags);
1199 AA_BUG(!new);
1200 if (IS_ERR(new)) {
1201 error = PTR_ERR(new);
1202 new = NULL;
1203 /* already audited */
1204 goto out;
1205 }
1206
1207 error = may_change_ptraced_domain(new, &info);
1208 if (error)
1209 goto fail;
1210
1211 /*
1212 * no new privs prevents domain transitions that would
1213 * reduce restrictions.
1214 */
1215 if (task_no_new_privs(current) && !unconfined(label) &&
1216 !aa_label_is_subset(new, ctx->nnp)) {
1217 /* not an apparmor denial per se, so don't log it */
1218 AA_DEBUG("no_new_privs - change_hat denied");
1219 error = -EPERM;
1220 goto out;
1221 }
1222
1223 if (flags & AA_CHANGE_TEST)
1224 goto out;
1225
1226 target = new;
1227 error = aa_set_current_hat(new, token);
1228 if (error == -EACCES)
1229 /* kill task in case of brute force attacks */
1230 goto kill;
1231 } else if (previous && !(flags & AA_CHANGE_TEST)) {
1232 /*
1233 * no new privs prevents domain transitions that would
1234 * reduce restrictions.
1235 */
1236 if (task_no_new_privs(current) && !unconfined(label) &&
1237 !aa_label_is_subset(previous, ctx->nnp)) {
1238 /* not an apparmor denial per se, so don't log it */
1239 AA_DEBUG("no_new_privs - change_hat denied");
1240 error = -EPERM;
1241 goto out;
1242 }
1243
1244 /* Return to saved label. Kill task if restore fails
1245 * to avoid brute force attacks
1246 */
1247 target = previous;
1248 error = aa_restore_previous_label(token);
1249 if (error) {
1250 if (error == -EACCES)
1251 goto kill;
1252 goto fail;
1253 }
1254 } /* else ignore @flags && restores when there is no saved profile */
1255
1256out:
1257 aa_put_label(new);
1258 aa_put_label(previous);
1259 aa_put_label(label);
1260 put_cred(cred);
1261
1262 return error;
1263
1264kill:
1265 info = "failed token match";
1266 perms.kill = AA_MAY_CHANGEHAT;
1267
1268fail:
1269 fn_for_each_in_ns(label, profile,
1270 aa_audit_file(profile, &perms, OP_CHANGE_HAT,
1271 AA_MAY_CHANGEHAT, NULL, NULL, target,
1272 GLOBAL_ROOT_UID, info, error));
1273
1274 goto out;
1275}
1276
1277
1278static int change_profile_perms_wrapper(const char *op, const char *name,
1279 struct aa_profile *profile,
1280 struct aa_label *target, bool stack,
1281 u32 request, struct aa_perms *perms)
1282{
1283 const char *info = NULL;
1284 int error = 0;
1285
1286 if (!error)
1287 error = change_profile_perms(profile, target, stack, request,
1288 profile->file.start, perms);
1289 if (error)
1290 error = aa_audit_file(profile, perms, op, request, name,
1291 NULL, target, GLOBAL_ROOT_UID, info,
1292 error);
1293
1294 return error;
1295}
1296
1297/**
1298 * aa_change_profile - perform a one-way profile transition
1299 * @fqname: name of profile may include namespace (NOT NULL)
1300 * @onexec: whether this transition is to take place immediately or at exec
1301 * @flags: flags affecting change behavior
1302 *
1303 * Change to new profile @name. Unlike with hats, there is no way
1304 * to change back. If @name isn't specified the current profile name is
1305 * used.
1306 * If @onexec then the transition is delayed until
1307 * the next exec.
1308 *
1309 * Returns %0 on success, error otherwise.
1310 */
1311int aa_change_profile(const char *fqname, int flags)
1312{
1313 struct aa_label *label, *new = NULL, *target = NULL;
1314 struct aa_profile *profile;
1315 struct aa_perms perms = {};
1316 const char *info = NULL;
1317 const char *auditname = fqname; /* retain leading & if stack */
1318 bool stack = flags & AA_CHANGE_STACK;
1319 struct aa_task_ctx *ctx = task_ctx(current);
1320 int error = 0;
1321 char *op;
1322 u32 request;
1323
1324 label = aa_get_current_label();
1325
1326 /*
1327 * Detect no new privs being set, and store the label it
1328 * occurred under. Ideally this would happen when nnp
1329 * is set but there isn't a good way to do that yet.
1330 *
1331 * Testing for unconfined must be done before the subset test
1332 */
1333 if (task_no_new_privs(current) && !unconfined(label) && !ctx->nnp)
1334 ctx->nnp = aa_get_label(label);
1335
1336 if (!fqname || !*fqname) {
1337 AA_DEBUG("no profile name");
1338 return -EINVAL;
1339 }
1340
1341 if (flags & AA_CHANGE_ONEXEC) {
1342 request = AA_MAY_ONEXEC;
1343 if (stack)
1344 op = OP_STACK_ONEXEC;
1345 else
1346 op = OP_CHANGE_ONEXEC;
1347 } else {
1348 request = AA_MAY_CHANGE_PROFILE;
1349 if (stack)
1350 op = OP_STACK;
1351 else
1352 op = OP_CHANGE_PROFILE;
1353 }
1354
1355 label = aa_get_current_label();
1356
1357 if (*fqname == '&') {
1358 stack = true;
1359 /* don't have label_parse() do stacking */
1360 fqname++;
1361 }
1362 target = aa_label_parse(label, fqname, GFP_KERNEL, true, false);
1363 if (IS_ERR(target)) {
1364 struct aa_profile *tprofile;
1365
1366 info = "label not found";
1367 error = PTR_ERR(target);
1368 target = NULL;
1369 /*
1370 * TODO: fixme using labels_profile is not right - do profile
1371 * per complain profile
1372 */
1373 if ((flags & AA_CHANGE_TEST) ||
1374 !COMPLAIN_MODE(labels_profile(label)))
1375 goto audit;
1376 /* released below */
1377 tprofile = aa_new_null_profile(labels_profile(label), false,
1378 fqname, GFP_KERNEL);
1379 if (!tprofile) {
1380 info = "failed null profile create";
1381 error = -ENOMEM;
1382 goto audit;
1383 }
1384 target = &tprofile->label;
1385 goto check;
1386 }
1387
1388 /*
1389 * self directed transitions only apply to current policy ns
1390 * TODO: currently requiring perms for stacking and straight change
1391 * stacking doesn't strictly need this. Determine how much
1392 * we want to loosen this restriction for stacking
1393 *
1394 * if (!stack) {
1395 */
1396 error = fn_for_each_in_ns(label, profile,
1397 change_profile_perms_wrapper(op, auditname,
1398 profile, target, stack,
1399 request, &perms));
1400 if (error)
1401 /* auditing done in change_profile_perms_wrapper */
1402 goto out;
1403
1404 /* } */
1405
1406check:
1407 /* check if tracing task is allowed to trace target domain */
1408 error = may_change_ptraced_domain(target, &info);
1409 if (error && !fn_for_each_in_ns(label, profile,
1410 COMPLAIN_MODE(profile)))
1411 goto audit;
1412
1413 /* TODO: add permission check to allow this
1414 * if ((flags & AA_CHANGE_ONEXEC) && !current_is_single_threaded()) {
1415 * info = "not a single threaded task";
1416 * error = -EACCES;
1417 * goto audit;
1418 * }
1419 */
1420 if (flags & AA_CHANGE_TEST)
1421 goto out;
1422
1423 /* stacking is always a subset, so only check the nonstack case */
1424 if (!stack) {
1425 new = fn_label_build_in_ns(label, profile, GFP_KERNEL,
1426 aa_get_label(target),
1427 aa_get_label(&profile->label));
1428 /*
1429 * no new privs prevents domain transitions that would
1430 * reduce restrictions.
1431 */
1432 if (task_no_new_privs(current) && !unconfined(label) &&
1433 !aa_label_is_subset(new, ctx->nnp)) {
1434 /* not an apparmor denial per se, so don't log it */
1435 AA_DEBUG("no_new_privs - change_hat denied");
1436 error = -EPERM;
1437 goto out;
1438 }
1439 }
1440
1441 if (!(flags & AA_CHANGE_ONEXEC)) {
1442 /* only transition profiles in the current ns */
1443 if (stack)
1444 new = aa_label_merge(label, target, GFP_KERNEL);
1445 if (IS_ERR_OR_NULL(new)) {
1446 info = "failed to build target label";
1447 error = PTR_ERR(new);
1448 new = NULL;
1449 perms.allow = 0;
1450 goto audit;
1451 }
1452 error = aa_replace_current_label(new);
1453 } else {
1454 if (new) {
1455 aa_put_label(new);
1456 new = NULL;
1457 }
1458
1459 /* full transition will be built in exec path */
1460 error = aa_set_current_onexec(target, stack);
1461 }
1462
1463audit:
1464 error = fn_for_each_in_ns(label, profile,
1465 aa_audit_file(profile, &perms, op, request, auditname,
1466 NULL, new ? new : target,
1467 GLOBAL_ROOT_UID, info, error));
1468
1469out:
1470 aa_put_label(new);
1471 aa_put_label(target);
1472 aa_put_label(label);
1473
1474 return error;
1475}
1/*
2 * AppArmor security module
3 *
4 * This file contains AppArmor policy attachment and domain transitions
5 *
6 * Copyright (C) 2002-2008 Novell/SUSE
7 * Copyright 2009-2010 Canonical Ltd.
8 *
9 * This program is free software; you can redistribute it and/or
10 * modify it under the terms of the GNU General Public License as
11 * published by the Free Software Foundation, version 2 of the
12 * License.
13 */
14
15#include <linux/errno.h>
16#include <linux/fdtable.h>
17#include <linux/file.h>
18#include <linux/mount.h>
19#include <linux/syscalls.h>
20#include <linux/tracehook.h>
21#include <linux/personality.h>
22
23#include "include/audit.h"
24#include "include/apparmorfs.h"
25#include "include/context.h"
26#include "include/domain.h"
27#include "include/file.h"
28#include "include/ipc.h"
29#include "include/match.h"
30#include "include/path.h"
31#include "include/policy.h"
32
33/**
34 * aa_free_domain_entries - free entries in a domain table
35 * @domain: the domain table to free (MAYBE NULL)
36 */
37void aa_free_domain_entries(struct aa_domain *domain)
38{
39 int i;
40 if (domain) {
41 if (!domain->table)
42 return;
43
44 for (i = 0; i < domain->size; i++)
45 kzfree(domain->table[i]);
46 kzfree(domain->table);
47 domain->table = NULL;
48 }
49}
50
51/**
52 * may_change_ptraced_domain - check if can change profile on ptraced task
53 * @to_profile: profile to change to (NOT NULL)
54 *
55 * Check if current is ptraced and if so if the tracing task is allowed
56 * to trace the new domain
57 *
58 * Returns: %0 or error if change not allowed
59 */
60static int may_change_ptraced_domain(struct aa_profile *to_profile)
61{
62 struct task_struct *tracer;
63 struct aa_profile *tracerp = NULL;
64 int error = 0;
65
66 rcu_read_lock();
67 tracer = ptrace_parent(current);
68 if (tracer)
69 /* released below */
70 tracerp = aa_get_task_profile(tracer);
71
72 /* not ptraced */
73 if (!tracer || unconfined(tracerp))
74 goto out;
75
76 error = aa_may_ptrace(tracerp, to_profile, PTRACE_MODE_ATTACH);
77
78out:
79 rcu_read_unlock();
80 aa_put_profile(tracerp);
81
82 return error;
83}
84
85/**
86 * change_profile_perms - find permissions for change_profile
87 * @profile: the current profile (NOT NULL)
88 * @ns: the namespace being switched to (NOT NULL)
89 * @name: the name of the profile to change to (NOT NULL)
90 * @request: requested perms
91 * @start: state to start matching in
92 *
93 * Returns: permission set
94 */
95static struct file_perms change_profile_perms(struct aa_profile *profile,
96 struct aa_namespace *ns,
97 const char *name, u32 request,
98 unsigned int start)
99{
100 struct file_perms perms;
101 struct path_cond cond = { };
102 unsigned int state;
103
104 if (unconfined(profile)) {
105 perms.allow = AA_MAY_CHANGE_PROFILE | AA_MAY_ONEXEC;
106 perms.audit = perms.quiet = perms.kill = 0;
107 return perms;
108 } else if (!profile->file.dfa) {
109 return nullperms;
110 } else if ((ns == profile->ns)) {
111 /* try matching against rules with out namespace prepended */
112 aa_str_perms(profile->file.dfa, start, name, &cond, &perms);
113 if (COMBINED_PERM_MASK(perms) & request)
114 return perms;
115 }
116
117 /* try matching with namespace name and then profile */
118 state = aa_dfa_match(profile->file.dfa, start, ns->base.name);
119 state = aa_dfa_match_len(profile->file.dfa, state, ":", 1);
120 aa_str_perms(profile->file.dfa, state, name, &cond, &perms);
121
122 return perms;
123}
124
125/**
126 * __attach_match_ - find an attachment match
127 * @name - to match against (NOT NULL)
128 * @head - profile list to walk (NOT NULL)
129 *
130 * Do a linear search on the profiles in the list. There is a matching
131 * preference where an exact match is preferred over a name which uses
132 * expressions to match, and matching expressions with the greatest
133 * xmatch_len are preferred.
134 *
135 * Requires: @head not be shared or have appropriate locks held
136 *
137 * Returns: profile or NULL if no match found
138 */
139static struct aa_profile *__attach_match(const char *name,
140 struct list_head *head)
141{
142 int len = 0;
143 struct aa_profile *profile, *candidate = NULL;
144
145 list_for_each_entry_rcu(profile, head, base.list) {
146 if (profile->flags & PFLAG_NULL)
147 continue;
148 if (profile->xmatch && profile->xmatch_len > len) {
149 unsigned int state = aa_dfa_match(profile->xmatch,
150 DFA_START, name);
151 u32 perm = dfa_user_allow(profile->xmatch, state);
152 /* any accepting state means a valid match. */
153 if (perm & MAY_EXEC) {
154 candidate = profile;
155 len = profile->xmatch_len;
156 }
157 } else if (!strcmp(profile->base.name, name))
158 /* exact non-re match, no more searching required */
159 return profile;
160 }
161
162 return candidate;
163}
164
165/**
166 * find_attach - do attachment search for unconfined processes
167 * @ns: the current namespace (NOT NULL)
168 * @list: list to search (NOT NULL)
169 * @name: the executable name to match against (NOT NULL)
170 *
171 * Returns: profile or NULL if no match found
172 */
173static struct aa_profile *find_attach(struct aa_namespace *ns,
174 struct list_head *list, const char *name)
175{
176 struct aa_profile *profile;
177
178 rcu_read_lock();
179 profile = aa_get_profile(__attach_match(name, list));
180 rcu_read_unlock();
181
182 return profile;
183}
184
185/**
186 * separate_fqname - separate the namespace and profile names
187 * @fqname: the fqname name to split (NOT NULL)
188 * @ns_name: the namespace name if it exists (NOT NULL)
189 *
190 * This is the xtable equivalent routine of aa_split_fqname. It finds the
191 * split in an xtable fqname which contains an embedded \0 instead of a :
192 * if a namespace is specified. This is done so the xtable is constant and
193 * isn't re-split on every lookup.
194 *
195 * Either the profile or namespace name may be optional but if the namespace
196 * is specified the profile name termination must be present. This results
197 * in the following possible encodings:
198 * profile_name\0
199 * :ns_name\0profile_name\0
200 * :ns_name\0\0
201 *
202 * NOTE: the xtable fqname is pre-validated at load time in unpack_trans_table
203 *
204 * Returns: profile name if it is specified else NULL
205 */
206static const char *separate_fqname(const char *fqname, const char **ns_name)
207{
208 const char *name;
209
210 if (fqname[0] == ':') {
211 /* In this case there is guaranteed to be two \0 terminators
212 * in the string. They are verified at load time by
213 * by unpack_trans_table
214 */
215 *ns_name = fqname + 1; /* skip : */
216 name = *ns_name + strlen(*ns_name) + 1;
217 if (!*name)
218 name = NULL;
219 } else {
220 *ns_name = NULL;
221 name = fqname;
222 }
223
224 return name;
225}
226
227static const char *next_name(int xtype, const char *name)
228{
229 return NULL;
230}
231
232/**
233 * x_table_lookup - lookup an x transition name via transition table
234 * @profile: current profile (NOT NULL)
235 * @xindex: index into x transition table
236 *
237 * Returns: refcounted profile, or NULL on failure (MAYBE NULL)
238 */
239static struct aa_profile *x_table_lookup(struct aa_profile *profile, u32 xindex)
240{
241 struct aa_profile *new_profile = NULL;
242 struct aa_namespace *ns = profile->ns;
243 u32 xtype = xindex & AA_X_TYPE_MASK;
244 int index = xindex & AA_X_INDEX_MASK;
245 const char *name;
246
247 /* index is guaranteed to be in range, validated at load time */
248 for (name = profile->file.trans.table[index]; !new_profile && name;
249 name = next_name(xtype, name)) {
250 struct aa_namespace *new_ns;
251 const char *xname = NULL;
252
253 new_ns = NULL;
254 if (xindex & AA_X_CHILD) {
255 /* release by caller */
256 new_profile = aa_find_child(profile, name);
257 continue;
258 } else if (*name == ':') {
259 /* switching namespace */
260 const char *ns_name;
261 xname = name = separate_fqname(name, &ns_name);
262 if (!xname)
263 /* no name so use profile name */
264 xname = profile->base.hname;
265 if (*ns_name == '@') {
266 /* TODO: variable support */
267 ;
268 }
269 /* released below */
270 new_ns = aa_find_namespace(ns, ns_name);
271 if (!new_ns)
272 continue;
273 } else if (*name == '@') {
274 /* TODO: variable support */
275 continue;
276 } else {
277 /* basic namespace lookup */
278 xname = name;
279 }
280
281 /* released by caller */
282 new_profile = aa_lookup_profile(new_ns ? new_ns : ns, xname);
283 aa_put_namespace(new_ns);
284 }
285
286 /* released by caller */
287 return new_profile;
288}
289
290/**
291 * x_to_profile - get target profile for a given xindex
292 * @profile: current profile (NOT NULL)
293 * @name: name to lookup (NOT NULL)
294 * @xindex: index into x transition table
295 *
296 * find profile for a transition index
297 *
298 * Returns: refcounted profile or NULL if not found available
299 */
300static struct aa_profile *x_to_profile(struct aa_profile *profile,
301 const char *name, u32 xindex)
302{
303 struct aa_profile *new_profile = NULL;
304 struct aa_namespace *ns = profile->ns;
305 u32 xtype = xindex & AA_X_TYPE_MASK;
306
307 switch (xtype) {
308 case AA_X_NONE:
309 /* fail exec unless ix || ux fallback - handled by caller */
310 return NULL;
311 case AA_X_NAME:
312 if (xindex & AA_X_CHILD)
313 /* released by caller */
314 new_profile = find_attach(ns, &profile->base.profiles,
315 name);
316 else
317 /* released by caller */
318 new_profile = find_attach(ns, &ns->base.profiles,
319 name);
320 break;
321 case AA_X_TABLE:
322 /* released by caller */
323 new_profile = x_table_lookup(profile, xindex);
324 break;
325 }
326
327 /* released by caller */
328 return new_profile;
329}
330
331/**
332 * apparmor_bprm_set_creds - set the new creds on the bprm struct
333 * @bprm: binprm for the exec (NOT NULL)
334 *
335 * Returns: %0 or error on failure
336 */
337int apparmor_bprm_set_creds(struct linux_binprm *bprm)
338{
339 struct aa_task_cxt *cxt;
340 struct aa_profile *profile, *new_profile = NULL;
341 struct aa_namespace *ns;
342 char *buffer = NULL;
343 unsigned int state;
344 struct file_perms perms = {};
345 struct path_cond cond = {
346 file_inode(bprm->file)->i_uid,
347 file_inode(bprm->file)->i_mode
348 };
349 const char *name = NULL, *target = NULL, *info = NULL;
350 int error = 0;
351
352 if (bprm->cred_prepared)
353 return 0;
354
355 cxt = cred_cxt(bprm->cred);
356 BUG_ON(!cxt);
357
358 profile = aa_get_newest_profile(cxt->profile);
359 /*
360 * get the namespace from the replacement profile as replacement
361 * can change the namespace
362 */
363 ns = profile->ns;
364 state = profile->file.start;
365
366 /* buffer freed below, name is pointer into buffer */
367 error = aa_path_name(&bprm->file->f_path, profile->path_flags, &buffer,
368 &name, &info);
369 if (error) {
370 if (unconfined(profile) ||
371 (profile->flags & PFLAG_IX_ON_NAME_ERROR))
372 error = 0;
373 name = bprm->filename;
374 goto audit;
375 }
376
377 /* Test for onexec first as onexec directives override other
378 * x transitions.
379 */
380 if (unconfined(profile)) {
381 /* unconfined task */
382 if (cxt->onexec)
383 /* change_profile on exec already been granted */
384 new_profile = aa_get_profile(cxt->onexec);
385 else
386 new_profile = find_attach(ns, &ns->base.profiles, name);
387 if (!new_profile)
388 goto cleanup;
389 /*
390 * NOTE: Domain transitions from unconfined are allowed
391 * even when no_new_privs is set because this aways results
392 * in a further reduction of permissions.
393 */
394 goto apply;
395 }
396
397 /* find exec permissions for name */
398 state = aa_str_perms(profile->file.dfa, state, name, &cond, &perms);
399 if (cxt->onexec) {
400 struct file_perms cp;
401 info = "change_profile onexec";
402 if (!(perms.allow & AA_MAY_ONEXEC))
403 goto audit;
404
405 /* test if this exec can be paired with change_profile onexec.
406 * onexec permission is linked to exec with a standard pairing
407 * exec\0change_profile
408 */
409 state = aa_dfa_null_transition(profile->file.dfa, state);
410 cp = change_profile_perms(profile, cxt->onexec->ns,
411 cxt->onexec->base.name,
412 AA_MAY_ONEXEC, state);
413
414 if (!(cp.allow & AA_MAY_ONEXEC))
415 goto audit;
416 new_profile = aa_get_newest_profile(cxt->onexec);
417 goto apply;
418 }
419
420 if (perms.allow & MAY_EXEC) {
421 /* exec permission determine how to transition */
422 new_profile = x_to_profile(profile, name, perms.xindex);
423 if (!new_profile) {
424 if (perms.xindex & AA_X_INHERIT) {
425 /* (p|c|n)ix - don't change profile but do
426 * use the newest version, which was picked
427 * up above when getting profile
428 */
429 info = "ix fallback";
430 new_profile = aa_get_profile(profile);
431 goto x_clear;
432 } else if (perms.xindex & AA_X_UNCONFINED) {
433 new_profile = aa_get_newest_profile(ns->unconfined);
434 info = "ux fallback";
435 } else {
436 error = -ENOENT;
437 info = "profile not found";
438 /* remove MAY_EXEC to audit as failure */
439 perms.allow &= ~MAY_EXEC;
440 }
441 }
442 } else if (COMPLAIN_MODE(profile)) {
443 /* no exec permission - are we in learning mode */
444 new_profile = aa_new_null_profile(profile, 0);
445 if (!new_profile) {
446 error = -ENOMEM;
447 info = "could not create null profile";
448 } else {
449 error = -EACCES;
450 target = new_profile->base.hname;
451 }
452 perms.xindex |= AA_X_UNSAFE;
453 } else
454 /* fail exec */
455 error = -EACCES;
456
457 /*
458 * Policy has specified a domain transition, if no_new_privs then
459 * fail the exec.
460 */
461 if (bprm->unsafe & LSM_UNSAFE_NO_NEW_PRIVS) {
462 aa_put_profile(new_profile);
463 error = -EPERM;
464 goto cleanup;
465 }
466
467 if (!new_profile)
468 goto audit;
469
470 if (bprm->unsafe & LSM_UNSAFE_SHARE) {
471 /* FIXME: currently don't mediate shared state */
472 ;
473 }
474
475 if (bprm->unsafe & (LSM_UNSAFE_PTRACE | LSM_UNSAFE_PTRACE_CAP)) {
476 error = may_change_ptraced_domain(new_profile);
477 if (error) {
478 aa_put_profile(new_profile);
479 goto audit;
480 }
481 }
482
483 /* Determine if secure exec is needed.
484 * Can be at this point for the following reasons:
485 * 1. unconfined switching to confined
486 * 2. confined switching to different confinement
487 * 3. confined switching to unconfined
488 *
489 * Cases 2 and 3 are marked as requiring secure exec
490 * (unless policy specified "unsafe exec")
491 *
492 * bprm->unsafe is used to cache the AA_X_UNSAFE permission
493 * to avoid having to recompute in secureexec
494 */
495 if (!(perms.xindex & AA_X_UNSAFE)) {
496 AA_DEBUG("scrubbing environment variables for %s profile=%s\n",
497 name, new_profile->base.hname);
498 bprm->unsafe |= AA_SECURE_X_NEEDED;
499 }
500apply:
501 target = new_profile->base.hname;
502 /* when transitioning profiles clear unsafe personality bits */
503 bprm->per_clear |= PER_CLEAR_ON_SETID;
504
505x_clear:
506 aa_put_profile(cxt->profile);
507 /* transfer new profile reference will be released when cxt is freed */
508 cxt->profile = new_profile;
509
510 /* clear out all temporary/transitional state from the context */
511 aa_clear_task_cxt_trans(cxt);
512
513audit:
514 error = aa_audit_file(profile, &perms, GFP_KERNEL, OP_EXEC, MAY_EXEC,
515 name, target, cond.uid, info, error);
516
517cleanup:
518 aa_put_profile(profile);
519 kfree(buffer);
520
521 return error;
522}
523
524/**
525 * apparmor_bprm_secureexec - determine if secureexec is needed
526 * @bprm: binprm for exec (NOT NULL)
527 *
528 * Returns: %1 if secureexec is needed else %0
529 */
530int apparmor_bprm_secureexec(struct linux_binprm *bprm)
531{
532 /* the decision to use secure exec is computed in set_creds
533 * and stored in bprm->unsafe.
534 */
535 if (bprm->unsafe & AA_SECURE_X_NEEDED)
536 return 1;
537
538 return 0;
539}
540
541/**
542 * apparmor_bprm_committing_creds - do task cleanup on committing new creds
543 * @bprm: binprm for the exec (NOT NULL)
544 */
545void apparmor_bprm_committing_creds(struct linux_binprm *bprm)
546{
547 struct aa_profile *profile = __aa_current_profile();
548 struct aa_task_cxt *new_cxt = cred_cxt(bprm->cred);
549
550 /* bail out if unconfined or not changing profile */
551 if ((new_cxt->profile == profile) ||
552 (unconfined(new_cxt->profile)))
553 return;
554
555 current->pdeath_signal = 0;
556
557 /* reset soft limits and set hard limits for the new profile */
558 __aa_transition_rlimits(profile, new_cxt->profile);
559}
560
561/**
562 * apparmor_bprm_commited_cred - do cleanup after new creds committed
563 * @bprm: binprm for the exec (NOT NULL)
564 */
565void apparmor_bprm_committed_creds(struct linux_binprm *bprm)
566{
567 /* TODO: cleanup signals - ipc mediation */
568 return;
569}
570
571/*
572 * Functions for self directed profile change
573 */
574
575/**
576 * new_compound_name - create an hname with @n2 appended to @n1
577 * @n1: base of hname (NOT NULL)
578 * @n2: name to append (NOT NULL)
579 *
580 * Returns: new name or NULL on error
581 */
582static char *new_compound_name(const char *n1, const char *n2)
583{
584 char *name = kmalloc(strlen(n1) + strlen(n2) + 3, GFP_KERNEL);
585 if (name)
586 sprintf(name, "%s//%s", n1, n2);
587 return name;
588}
589
590/**
591 * aa_change_hat - change hat to/from subprofile
592 * @hats: vector of hat names to try changing into (MAYBE NULL if @count == 0)
593 * @count: number of hat names in @hats
594 * @token: magic value to validate the hat change
595 * @permtest: true if this is just a permission test
596 *
597 * Change to the first profile specified in @hats that exists, and store
598 * the @hat_magic in the current task context. If the count == 0 and the
599 * @token matches that stored in the current task context, return to the
600 * top level profile.
601 *
602 * Returns %0 on success, error otherwise.
603 */
604int aa_change_hat(const char *hats[], int count, u64 token, bool permtest)
605{
606 const struct cred *cred;
607 struct aa_task_cxt *cxt;
608 struct aa_profile *profile, *previous_profile, *hat = NULL;
609 char *name = NULL;
610 int i;
611 struct file_perms perms = {};
612 const char *target = NULL, *info = NULL;
613 int error = 0;
614
615 /*
616 * Fail explicitly requested domain transitions if no_new_privs.
617 * There is no exception for unconfined as change_hat is not
618 * available.
619 */
620 if (task_no_new_privs(current))
621 return -EPERM;
622
623 /* released below */
624 cred = get_current_cred();
625 cxt = cred_cxt(cred);
626 profile = aa_cred_profile(cred);
627 previous_profile = cxt->previous;
628
629 if (unconfined(profile)) {
630 info = "unconfined";
631 error = -EPERM;
632 goto audit;
633 }
634
635 if (count) {
636 /* attempting to change into a new hat or switch to a sibling */
637 struct aa_profile *root;
638 if (PROFILE_IS_HAT(profile))
639 root = aa_get_profile_rcu(&profile->parent);
640 else
641 root = aa_get_profile(profile);
642
643 /* find first matching hat */
644 for (i = 0; i < count && !hat; i++)
645 /* released below */
646 hat = aa_find_child(root, hats[i]);
647 if (!hat) {
648 if (!COMPLAIN_MODE(root) || permtest) {
649 if (list_empty(&root->base.profiles))
650 error = -ECHILD;
651 else
652 error = -ENOENT;
653 aa_put_profile(root);
654 goto out;
655 }
656
657 /*
658 * In complain mode and failed to match any hats.
659 * Audit the failure is based off of the first hat
660 * supplied. This is done due how userspace
661 * interacts with change_hat.
662 *
663 * TODO: Add logging of all failed hats
664 */
665
666 /* freed below */
667 name = new_compound_name(root->base.hname, hats[0]);
668 aa_put_profile(root);
669 target = name;
670 /* released below */
671 hat = aa_new_null_profile(profile, 1);
672 if (!hat) {
673 info = "failed null profile create";
674 error = -ENOMEM;
675 goto audit;
676 }
677 } else {
678 aa_put_profile(root);
679 target = hat->base.hname;
680 if (!PROFILE_IS_HAT(hat)) {
681 info = "target not hat";
682 error = -EPERM;
683 goto audit;
684 }
685 }
686
687 error = may_change_ptraced_domain(hat);
688 if (error) {
689 info = "ptraced";
690 error = -EPERM;
691 goto audit;
692 }
693
694 if (!permtest) {
695 error = aa_set_current_hat(hat, token);
696 if (error == -EACCES)
697 /* kill task in case of brute force attacks */
698 perms.kill = AA_MAY_CHANGEHAT;
699 else if (name && !error)
700 /* reset error for learning of new hats */
701 error = -ENOENT;
702 }
703 } else if (previous_profile) {
704 /* Return to saved profile. Kill task if restore fails
705 * to avoid brute force attacks
706 */
707 target = previous_profile->base.hname;
708 error = aa_restore_previous_profile(token);
709 perms.kill = AA_MAY_CHANGEHAT;
710 } else
711 /* ignore restores when there is no saved profile */
712 goto out;
713
714audit:
715 if (!permtest)
716 error = aa_audit_file(profile, &perms, GFP_KERNEL,
717 OP_CHANGE_HAT, AA_MAY_CHANGEHAT, NULL,
718 target, GLOBAL_ROOT_UID, info, error);
719
720out:
721 aa_put_profile(hat);
722 kfree(name);
723 put_cred(cred);
724
725 return error;
726}
727
728/**
729 * aa_change_profile - perform a one-way profile transition
730 * @ns_name: name of the profile namespace to change to (MAYBE NULL)
731 * @hname: name of profile to change to (MAYBE NULL)
732 * @onexec: whether this transition is to take place immediately or at exec
733 * @permtest: true if this is just a permission test
734 *
735 * Change to new profile @name. Unlike with hats, there is no way
736 * to change back. If @name isn't specified the current profile name is
737 * used.
738 * If @onexec then the transition is delayed until
739 * the next exec.
740 *
741 * Returns %0 on success, error otherwise.
742 */
743int aa_change_profile(const char *ns_name, const char *hname, bool onexec,
744 bool permtest)
745{
746 const struct cred *cred;
747 struct aa_profile *profile, *target = NULL;
748 struct aa_namespace *ns = NULL;
749 struct file_perms perms = {};
750 const char *name = NULL, *info = NULL;
751 int op, error = 0;
752 u32 request;
753
754 if (!hname && !ns_name)
755 return -EINVAL;
756
757 if (onexec) {
758 request = AA_MAY_ONEXEC;
759 op = OP_CHANGE_ONEXEC;
760 } else {
761 request = AA_MAY_CHANGE_PROFILE;
762 op = OP_CHANGE_PROFILE;
763 }
764
765 cred = get_current_cred();
766 profile = aa_cred_profile(cred);
767
768 /*
769 * Fail explicitly requested domain transitions if no_new_privs
770 * and not unconfined.
771 * Domain transitions from unconfined are allowed even when
772 * no_new_privs is set because this aways results in a reduction
773 * of permissions.
774 */
775 if (task_no_new_privs(current) && !unconfined(profile)) {
776 put_cred(cred);
777 return -EPERM;
778 }
779
780 if (ns_name) {
781 /* released below */
782 ns = aa_find_namespace(profile->ns, ns_name);
783 if (!ns) {
784 /* we don't create new namespace in complain mode */
785 name = ns_name;
786 info = "namespace not found";
787 error = -ENOENT;
788 goto audit;
789 }
790 } else
791 /* released below */
792 ns = aa_get_namespace(profile->ns);
793
794 /* if the name was not specified, use the name of the current profile */
795 if (!hname) {
796 if (unconfined(profile))
797 hname = ns->unconfined->base.hname;
798 else
799 hname = profile->base.hname;
800 }
801
802 perms = change_profile_perms(profile, ns, hname, request,
803 profile->file.start);
804 if (!(perms.allow & request)) {
805 error = -EACCES;
806 goto audit;
807 }
808
809 /* released below */
810 target = aa_lookup_profile(ns, hname);
811 if (!target) {
812 info = "profile not found";
813 error = -ENOENT;
814 if (permtest || !COMPLAIN_MODE(profile))
815 goto audit;
816 /* released below */
817 target = aa_new_null_profile(profile, 0);
818 if (!target) {
819 info = "failed null profile create";
820 error = -ENOMEM;
821 goto audit;
822 }
823 }
824
825 /* check if tracing task is allowed to trace target domain */
826 error = may_change_ptraced_domain(target);
827 if (error) {
828 info = "ptrace prevents transition";
829 goto audit;
830 }
831
832 if (permtest)
833 goto audit;
834
835 if (onexec)
836 error = aa_set_current_onexec(target);
837 else
838 error = aa_replace_current_profile(target);
839
840audit:
841 if (!permtest)
842 error = aa_audit_file(profile, &perms, GFP_KERNEL, op, request,
843 name, hname, GLOBAL_ROOT_UID, info, error);
844
845 aa_put_namespace(ns);
846 aa_put_profile(target);
847 put_cred(cred);
848
849 return error;
850}