1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * AppArmor security module
4 *
5 * This file contains AppArmor policy attachment and domain transitions
6 *
7 * Copyright (C) 2002-2008 Novell/SUSE
8 * Copyright 2009-2010 Canonical Ltd.
9 */
10
11 #include <linux/errno.h>
12 #include <linux/fdtable.h>
13 #include <linux/file.h>
14 #include <linux/mount.h>
15 #include <linux/syscalls.h>
16 #include <linux/tracehook.h>
17 #include <linux/personality.h>
18 #include <linux/xattr.h>
19
20 #include "include/audit.h"
21 #include "include/apparmorfs.h"
22 #include "include/cred.h"
23 #include "include/domain.h"
24 #include "include/file.h"
25 #include "include/ipc.h"
26 #include "include/match.h"
27 #include "include/path.h"
28 #include "include/policy.h"
29 #include "include/policy_ns.h"
30
31 /**
32 * aa_free_domain_entries - free entries in a domain table
33 * @domain: the domain table to free (MAYBE NULL)
34 */
35 void aa_free_domain_entries(struct aa_domain *domain)
36 {
37 int i;
38 if (domain) {
39 if (!domain->table)
40 return;
41
42 for (i = 0; i < domain->size; i++)
43 kzfree(domain->table[i]);
44 kzfree(domain->table);
45 domain->table = NULL;
46 }
47 }
48
49 /**
50 * may_change_ptraced_domain - check if can change profile on ptraced task
51 * @to_label: profile to change to (NOT NULL)
52 * @info: message if there is an error
53 *
54 * Check if current is ptraced and if so if the tracing task is allowed
55 * to trace the new domain
56 *
57 * Returns: %0 or error if change not allowed
58 */
59 static int may_change_ptraced_domain(struct aa_label *to_label,
60 const char **info)
61 {
62 struct task_struct *tracer;
63 struct aa_label *tracerl = NULL;
64 int error = 0;
65
66 rcu_read_lock();
67 tracer = ptrace_parent(current);
68 if (tracer)
69 /* released below */
70 tracerl = aa_get_task_label(tracer);
71
72 /* not ptraced */
73 if (!tracer || unconfined(tracerl))
74 goto out;
75
76 error = aa_may_ptrace(tracerl, to_label, PTRACE_MODE_ATTACH);
77
78 out:
79 rcu_read_unlock();
80 aa_put_label(tracerl);
81
82 if (error)
83 *info = "ptrace prevents transition";
84 return error;
85 }
86
87 /**** TODO: dedup to aa_label_match - needs perm and dfa, merging
88 * specifically this is an exact copy of aa_label_match except
89 * aa_compute_perms is replaced with aa_compute_fperms
90 * and policy.dfa with file.dfa
91 ****/
92 /* match a profile and its associated ns component if needed
93 * Assumes visibility test has already been done.
94 * If a subns profile is not to be matched should be prescreened with
95 * visibility test.
96 */
97 static inline unsigned int match_component(struct aa_profile *profile,
98 struct aa_profile *tp,
99 bool stack, unsigned int state)
100 {
101 const char *ns_name;
102
103 if (stack)
104 state = aa_dfa_match(profile->file.dfa, state, "&");
105 if (profile->ns == tp->ns)
106 return aa_dfa_match(profile->file.dfa, state, tp->base.hname);
107
108 /* try matching with namespace name and then profile */
109 ns_name = aa_ns_name(profile->ns, tp->ns, true);
110 state = aa_dfa_match_len(profile->file.dfa, state, ":", 1);
111 state = aa_dfa_match(profile->file.dfa, state, ns_name);
112 state = aa_dfa_match_len(profile->file.dfa, state, ":", 1);
113 return aa_dfa_match(profile->file.dfa, state, tp->base.hname);
114 }
115
116 /**
117 * label_compound_match - find perms for full compound label
118 * @profile: profile to find perms for
119 * @label: label to check access permissions for
120 * @stack: whether this is a stacking request
121 * @start: state to start match in
122 * @subns: whether to do permission checks on components in a subns
123 * @request: permissions to request
124 * @perms: perms struct to set
125 *
126 * Returns: 0 on success else ERROR
127 *
128 * For the label A//&B//&C this does the perm match for A//&B//&C
129 * @perms should be preinitialized with allperms OR a previous permission
130 * check to be stacked.
131 */
132 static int label_compound_match(struct aa_profile *profile,
133 struct aa_label *label, bool stack,
134 unsigned int state, bool subns, u32 request,
135 struct aa_perms *perms)
136 {
137 struct aa_profile *tp;
138 struct label_it i;
139 struct path_cond cond = { };
140
141 /* find first subcomponent that is visible */
142 label_for_each(i, label, tp) {
143 if (!aa_ns_visible(profile->ns, tp->ns, subns))
144 continue;
145 state = match_component(profile, tp, stack, state);
146 if (!state)
147 goto fail;
148 goto next;
149 }
150
151 /* no component visible */
152 *perms = allperms;
153 return 0;
154
155 next:
156 label_for_each_cont(i, label, tp) {
157 if (!aa_ns_visible(profile->ns, tp->ns, subns))
158 continue;
159 state = aa_dfa_match(profile->file.dfa, state, "//&");
160 state = match_component(profile, tp, false, state);
161 if (!state)
162 goto fail;
163 }
164 *perms = aa_compute_fperms(profile->file.dfa, state, &cond);
165 aa_apply_modes_to_perms(profile, perms);
166 if ((perms->allow & request) != request)
167 return -EACCES;
168
169 return 0;
170
171 fail:
172 *perms = nullperms;
173 return -EACCES;
174 }
175
176 /**
177 * label_components_match - find perms for all subcomponents of a label
178 * @profile: profile to find perms for
179 * @label: label to check access permissions for
180 * @stack: whether this is a stacking request
181 * @start: state to start match in
182 * @subns: whether to do permission checks on components in a subns
183 * @request: permissions to request
184 * @perms: an initialized perms struct to add accumulation to
185 *
186 * Returns: 0 on success else ERROR
187 *
188 * For the label A//&B//&C this does the perm match for each of A and B and C
189 * @perms should be preinitialized with allperms OR a previous permission
190 * check to be stacked.
191 */
192 static int label_components_match(struct aa_profile *profile,
193 struct aa_label *label, bool stack,
194 unsigned int start, bool subns, u32 request,
195 struct aa_perms *perms)
196 {
197 struct aa_profile *tp;
198 struct label_it i;
199 struct aa_perms tmp;
200 struct path_cond cond = { };
201 unsigned int state = 0;
202
203 /* find first subcomponent to test */
204 label_for_each(i, label, tp) {
205 if (!aa_ns_visible(profile->ns, tp->ns, subns))
206 continue;
207 state = match_component(profile, tp, stack, start);
208 if (!state)
209 goto fail;
210 goto next;
211 }
212
213 /* no subcomponents visible - no change in perms */
214 return 0;
215
216 next:
217 tmp = aa_compute_fperms(profile->file.dfa, state, &cond);
218 aa_apply_modes_to_perms(profile, &tmp);
219 aa_perms_accum(perms, &tmp);
220 label_for_each_cont(i, label, tp) {
221 if (!aa_ns_visible(profile->ns, tp->ns, subns))
222 continue;
223 state = match_component(profile, tp, stack, start);
224 if (!state)
225 goto fail;
226 tmp = aa_compute_fperms(profile->file.dfa, state, &cond);
227 aa_apply_modes_to_perms(profile, &tmp);
228 aa_perms_accum(perms, &tmp);
229 }
230
231 if ((perms->allow & request) != request)
232 return -EACCES;
233
234 return 0;
235
236 fail:
237 *perms = nullperms;
238 return -EACCES;
239 }
240
241 /**
242 * label_match - do a multi-component label match
243 * @profile: profile to match against (NOT NULL)
244 * @label: label to match (NOT NULL)
245 * @stack: whether this is a stacking request
246 * @state: state to start in
247 * @subns: whether to match subns components
248 * @request: permission request
249 * @perms: Returns computed perms (NOT NULL)
250 *
251 * Returns: the state the match finished in, may be the none matching state
252 */
253 static int label_match(struct aa_profile *profile, struct aa_label *label,
254 bool stack, unsigned int state, bool subns, u32 request,
255 struct aa_perms *perms)
256 {
257 int error;
258
259 *perms = nullperms;
260 error = label_compound_match(profile, label, stack, state, subns,
261 request, perms);
262 if (!error)
263 return error;
264
265 *perms = allperms;
266 return label_components_match(profile, label, stack, state, subns,
267 request, perms);
268 }
269
270 /******* end TODO: dedup *****/
271
272 /**
273 * change_profile_perms - find permissions for change_profile
274 * @profile: the current profile (NOT NULL)
275 * @target: label to transition to (NOT NULL)
276 * @stack: whether this is a stacking request
277 * @request: requested perms
278 * @start: state to start matching in
279 *
280 *
281 * Returns: permission set
282 *
283 * currently only matches full label A//&B//&C or individual components A, B, C
284 * not arbitrary combinations. Eg. A//&B, C
285 */
286 static int change_profile_perms(struct aa_profile *profile,
287 struct aa_label *target, bool stack,
288 u32 request, unsigned int start,
289 struct aa_perms *perms)
290 {
291 if (profile_unconfined(profile)) {
292 perms->allow = AA_MAY_CHANGE_PROFILE | AA_MAY_ONEXEC;
293 perms->audit = perms->quiet = perms->kill = 0;
294 return 0;
295 }
296
297 /* TODO: add profile in ns screening */
298 return label_match(profile, target, stack, start, true, request, perms);
299 }
300
301 /**
302 * aa_xattrs_match - check whether a file matches the xattrs defined in profile
303 * @bprm: binprm struct for the process to validate
304 * @profile: profile to match against (NOT NULL)
305 * @state: state to start match in
306 *
307 * Returns: number of extended attributes that matched, or < 0 on error
308 */
309 static int aa_xattrs_match(const struct linux_binprm *bprm,
310 struct aa_profile *profile, unsigned int state)
311 {
312 int i;
313 ssize_t size;
314 struct dentry *d;
315 char *value = NULL;
316 int value_size = 0, ret = profile->xattr_count;
317
318 if (!bprm || !profile->xattr_count)
319 return 0;
320 might_sleep();
321
322 /* transition from exec match to xattr set */
323 state = aa_dfa_null_transition(profile->xmatch, state);
324
325 d = bprm->file->f_path.dentry;
326
327 for (i = 0; i < profile->xattr_count; i++) {
328 size = vfs_getxattr_alloc(d, profile->xattrs[i], &value,
329 value_size, GFP_KERNEL);
330 if (size >= 0) {
331 u32 perm;
332
333 /* Check the xattr value, not just presence */
334 state = aa_dfa_match_len(profile->xmatch, state, value,
335 size);
336 perm = dfa_user_allow(profile->xmatch, state);
337 if (!(perm & MAY_EXEC)) {
338 ret = -EINVAL;
339 goto out;
340 }
341 }
342 /* transition to next element */
343 state = aa_dfa_null_transition(profile->xmatch, state);
344 if (size < 0) {
345 /*
346 * No xattr match, so verify if transition to
347 * next element was valid. IFF so the xattr
348 * was optional.
349 */
350 if (!state) {
351 ret = -EINVAL;
352 goto out;
353 }
354 /* don't count missing optional xattr as matched */
355 ret--;
356 }
357 }
358
359 out:
360 kfree(value);
361 return ret;
362 }
363
364 /**
365 * find_attach - do attachment search for unconfined processes
366 * @bprm - binprm structure of transitioning task
367 * @ns: the current namespace (NOT NULL)
368 * @head - profile list to walk (NOT NULL)
369 * @name - to match against (NOT NULL)
370 * @info - info message if there was an error (NOT NULL)
371 *
372 * Do a linear search on the profiles in the list. There is a matching
373 * preference where an exact match is preferred over a name which uses
374 * expressions to match, and matching expressions with the greatest
375 * xmatch_len are preferred.
376 *
377 * Requires: @head not be shared or have appropriate locks held
378 *
379 * Returns: label or NULL if no match found
380 */
381 static struct aa_label *find_attach(const struct linux_binprm *bprm,
382 struct aa_ns *ns, struct list_head *head,
383 const char *name, const char **info)
384 {
385 int candidate_len = 0, candidate_xattrs = 0;
386 bool conflict = false;
387 struct aa_profile *profile, *candidate = NULL;
388
389 AA_BUG(!name);
390 AA_BUG(!head);
391
392 rcu_read_lock();
393 restart:
394 list_for_each_entry_rcu(profile, head, base.list) {
395 if (profile->label.flags & FLAG_NULL &&
396 &profile->label == ns_unconfined(profile->ns))
397 continue;
398
399 /* Find the "best" matching profile. Profiles must
400 * match the path and extended attributes (if any)
401 * associated with the file. A more specific path
402 * match will be preferred over a less specific one,
403 * and a match with more matching extended attributes
404 * will be preferred over one with fewer. If the best
405 * match has both the same level of path specificity
406 * and the same number of matching extended attributes
407 * as another profile, signal a conflict and refuse to
408 * match.
409 */
410 if (profile->xmatch) {
411 unsigned int state, count;
412 u32 perm;
413
414 state = aa_dfa_leftmatch(profile->xmatch, DFA_START,
415 name, &count);
416 perm = dfa_user_allow(profile->xmatch, state);
417 /* any accepting state means a valid match. */
418 if (perm & MAY_EXEC) {
419 int ret = 0;
420
421 if (count < candidate_len)
422 continue;
423
424 if (bprm && profile->xattr_count) {
425 long rev = READ_ONCE(ns->revision);
426
427 if (!aa_get_profile_not0(profile))
428 goto restart;
429 rcu_read_unlock();
430 ret = aa_xattrs_match(bprm, profile,
431 state);
432 rcu_read_lock();
433 aa_put_profile(profile);
434 if (rev !=
435 READ_ONCE(ns->revision))
436 /* policy changed */
437 goto restart;
438 /*
439 * Fail matching if the xattrs don't
440 * match
441 */
442 if (ret < 0)
443 continue;
444 }
445 /*
446 * TODO: allow for more flexible best match
447 *
448 * The new match isn't more specific
449 * than the current best match
450 */
451 if (count == candidate_len &&
452 ret <= candidate_xattrs) {
453 /* Match is equivalent, so conflict */
454 if (ret == candidate_xattrs)
455 conflict = true;
456 continue;
457 }
458
459 /* Either the same length with more matching
460 * xattrs, or a longer match
461 */
462 candidate = profile;
463 candidate_len = profile->xmatch_len;
464 candidate_xattrs = ret;
465 conflict = false;
466 }
467 } else if (!strcmp(profile->base.name, name)) {
468 /*
469 * old exact non-re match, without conditionals such
470 * as xattrs. no more searching required
471 */
472 candidate = profile;
473 goto out;
474 }
475 }
476
477 if (!candidate || conflict) {
478 if (conflict)
479 *info = "conflicting profile attachments";
480 rcu_read_unlock();
481 return NULL;
482 }
483
484 out:
485 candidate = aa_get_newest_profile(candidate);
486 rcu_read_unlock();
487
488 return &candidate->label;
489 }
490
491 static 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 */
504 struct 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 */
550 static 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
617 static 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
732 audit:
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
743 static 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
808 audit:
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
815 static 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 loosen 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 */
875 int 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 set_cred_label(bprm->cred, new);
979
980 done:
981 aa_put_label(label);
982 put_buffers(buffer);
983
984 return error;
985
986 audit:
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 */
1005 static 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
1036 audit:
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, info,
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 */
1053 static 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;
1099 outer_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
1119 fail:
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
1136 build:
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 */
1166 int 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
1256 out:
1257 aa_put_label(new);
1258 aa_put_label(previous);
1259 aa_put_label(label);
1260 put_cred(cred);
1261
1262 return error;
1263
1264 kill:
1265 info = "failed token match";
1266 perms.kill = AA_MAY_CHANGEHAT;
1267
1268 fail:
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
1278 static 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 */
1311 int 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_put_label(label);
1338 AA_DEBUG("no profile name");
1339 return -EINVAL;
1340 }
1341
1342 if (flags & AA_CHANGE_ONEXEC) {
1343 request = AA_MAY_ONEXEC;
1344 if (stack)
1345 op = OP_STACK_ONEXEC;
1346 else
1347 op = OP_CHANGE_ONEXEC;
1348 } else {
1349 request = AA_MAY_CHANGE_PROFILE;
1350 if (stack)
1351 op = OP_STACK;
1352 else
1353 op = OP_CHANGE_PROFILE;
1354 }
1355
1356 if (*fqname == '&') {
1357 stack = true;
1358 /* don't have label_parse() do stacking */
1359 fqname++;
1360 }
1361 target = aa_label_parse(label, fqname, GFP_KERNEL, true, false);
1362 if (IS_ERR(target)) {
1363 struct aa_profile *tprofile;
1364
1365 info = "label not found";
1366 error = PTR_ERR(target);
1367 target = NULL;
1368 /*
1369 * TODO: fixme using labels_profile is not right - do profile
1370 * per complain profile
1371 */
1372 if ((flags & AA_CHANGE_TEST) ||
1373 !COMPLAIN_MODE(labels_profile(label)))
1374 goto audit;
1375 /* released below */
1376 tprofile = aa_new_null_profile(labels_profile(label), false,
1377 fqname, GFP_KERNEL);
1378 if (!tprofile) {
1379 info = "failed null profile create";
1380 error = -ENOMEM;
1381 goto audit;
1382 }
1383 target = &tprofile->label;
1384 goto check;
1385 }
1386
1387 /*
1388 * self directed transitions only apply to current policy ns
1389 * TODO: currently requiring perms for stacking and straight change
1390 * stacking doesn't strictly need this. Determine how much
1391 * we want to loosen this restriction for stacking
1392 *
1393 * if (!stack) {
1394 */
1395 error = fn_for_each_in_ns(label, profile,
1396 change_profile_perms_wrapper(op, auditname,
1397 profile, target, stack,
1398 request, &perms));
1399 if (error)
1400 /* auditing done in change_profile_perms_wrapper */
1401 goto out;
1402
1403 /* } */
1404
1405 check:
1406 /* check if tracing task is allowed to trace target domain */
1407 error = may_change_ptraced_domain(target, &info);
1408 if (error && !fn_for_each_in_ns(label, profile,
1409 COMPLAIN_MODE(profile)))
1410 goto audit;
1411
1412 /* TODO: add permission check to allow this
1413 * if ((flags & AA_CHANGE_ONEXEC) && !current_is_single_threaded()) {
1414 * info = "not a single threaded task";
1415 * error = -EACCES;
1416 * goto audit;
1417 * }
1418 */
1419 if (flags & AA_CHANGE_TEST)
1420 goto out;
1421
1422 /* stacking is always a subset, so only check the nonstack case */
1423 if (!stack) {
1424 new = fn_label_build_in_ns(label, profile, GFP_KERNEL,
1425 aa_get_label(target),
1426 aa_get_label(&profile->label));
1427 /*
1428 * no new privs prevents domain transitions that would
1429 * reduce restrictions.
1430 */
1431 if (task_no_new_privs(current) && !unconfined(label) &&
1432 !aa_label_is_subset(new, ctx->nnp)) {
1433 /* not an apparmor denial per se, so don't log it */
1434 AA_DEBUG("no_new_privs - change_hat denied");
1435 error = -EPERM;
1436 goto out;
1437 }
1438 }
1439
1440 if (!(flags & AA_CHANGE_ONEXEC)) {
1441 /* only transition profiles in the current ns */
1442 if (stack)
1443 new = aa_label_merge(label, target, GFP_KERNEL);
1444 if (IS_ERR_OR_NULL(new)) {
1445 info = "failed to build target label";
1446 if (!new)
1447 error = -ENOMEM;
1448 else
1449 error = PTR_ERR(new);
1450 new = NULL;
1451 perms.allow = 0;
1452 goto audit;
1453 }
1454 error = aa_replace_current_label(new);
1455 } else {
1456 if (new) {
1457 aa_put_label(new);
1458 new = NULL;
1459 }
1460
1461 /* full transition will be built in exec path */
1462 error = aa_set_current_onexec(target, stack);
1463 }
1464
1465 audit:
1466 error = fn_for_each_in_ns(label, profile,
1467 aa_audit_file(profile, &perms, op, request, auditname,
1468 NULL, new ? new : target,
1469 GLOBAL_ROOT_UID, info, error));
1470
1471 out:
1472 aa_put_label(new);
1473 aa_put_label(target);
1474 aa_put_label(label);
1475
1476 return error;
1477 }