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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
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 * @task: task we want to change profile of (NOT NULL)
54 * @to_profile: profile to change to (NOT NULL)
55 *
56 * Check if the task is ptraced and if so if the tracing task is allowed
57 * to trace the new domain
58 *
59 * Returns: %0 or error if change not allowed
60 */
61static int may_change_ptraced_domain(struct task_struct *task,
62 struct aa_profile *to_profile)
63{
64 struct task_struct *tracer;
65 const struct cred *cred = NULL;
66 struct aa_profile *tracerp = NULL;
67 int error = 0;
68
69 rcu_read_lock();
70 tracer = ptrace_parent(task);
71 if (tracer) {
72 /* released below */
73 cred = get_task_cred(tracer);
74 tracerp = aa_cred_profile(cred);
75 }
76
77 /* not ptraced */
78 if (!tracer || unconfined(tracerp))
79 goto out;
80
81 error = aa_may_ptrace(tracer, tracerp, to_profile, PTRACE_MODE_ATTACH);
82
83out:
84 rcu_read_unlock();
85 if (cred)
86 put_cred(cred);
87
88 return error;
89}
90
91/**
92 * change_profile_perms - find permissions for change_profile
93 * @profile: the current profile (NOT NULL)
94 * @ns: the namespace being switched to (NOT NULL)
95 * @name: the name of the profile to change to (NOT NULL)
96 * @request: requested perms
97 * @start: state to start matching in
98 *
99 * Returns: permission set
100 */
101static struct file_perms change_profile_perms(struct aa_profile *profile,
102 struct aa_namespace *ns,
103 const char *name, u32 request,
104 unsigned int start)
105{
106 struct file_perms perms;
107 struct path_cond cond = { };
108 unsigned int state;
109
110 if (unconfined(profile)) {
111 perms.allow = AA_MAY_CHANGE_PROFILE | AA_MAY_ONEXEC;
112 perms.audit = perms.quiet = perms.kill = 0;
113 return perms;
114 } else if (!profile->file.dfa) {
115 return nullperms;
116 } else if ((ns == profile->ns)) {
117 /* try matching against rules with out namespace prepended */
118 aa_str_perms(profile->file.dfa, start, name, &cond, &perms);
119 if (COMBINED_PERM_MASK(perms) & request)
120 return perms;
121 }
122
123 /* try matching with namespace name and then profile */
124 state = aa_dfa_match(profile->file.dfa, start, ns->base.name);
125 state = aa_dfa_match_len(profile->file.dfa, state, ":", 1);
126 aa_str_perms(profile->file.dfa, state, name, &cond, &perms);
127
128 return perms;
129}
130
131/**
132 * __attach_match_ - find an attachment match
133 * @name - to match against (NOT NULL)
134 * @head - profile list to walk (NOT NULL)
135 *
136 * Do a linear search on the profiles in the list. There is a matching
137 * preference where an exact match is preferred over a name which uses
138 * expressions to match, and matching expressions with the greatest
139 * xmatch_len are preferred.
140 *
141 * Requires: @head not be shared or have appropriate locks held
142 *
143 * Returns: profile or NULL if no match found
144 */
145static struct aa_profile *__attach_match(const char *name,
146 struct list_head *head)
147{
148 int len = 0;
149 struct aa_profile *profile, *candidate = NULL;
150
151 list_for_each_entry(profile, head, base.list) {
152 if (profile->flags & PFLAG_NULL)
153 continue;
154 if (profile->xmatch && profile->xmatch_len > len) {
155 unsigned int state = aa_dfa_match(profile->xmatch,
156 DFA_START, name);
157 u32 perm = dfa_user_allow(profile->xmatch, state);
158 /* any accepting state means a valid match. */
159 if (perm & MAY_EXEC) {
160 candidate = profile;
161 len = profile->xmatch_len;
162 }
163 } else if (!strcmp(profile->base.name, name))
164 /* exact non-re match, no more searching required */
165 return profile;
166 }
167
168 return candidate;
169}
170
171/**
172 * find_attach - do attachment search for unconfined processes
173 * @ns: the current namespace (NOT NULL)
174 * @list: list to search (NOT NULL)
175 * @name: the executable name to match against (NOT NULL)
176 *
177 * Returns: profile or NULL if no match found
178 */
179static struct aa_profile *find_attach(struct aa_namespace *ns,
180 struct list_head *list, const char *name)
181{
182 struct aa_profile *profile;
183
184 read_lock(&ns->lock);
185 profile = aa_get_profile(__attach_match(name, list));
186 read_unlock(&ns->lock);
187
188 return profile;
189}
190
191/**
192 * separate_fqname - separate the namespace and profile names
193 * @fqname: the fqname name to split (NOT NULL)
194 * @ns_name: the namespace name if it exists (NOT NULL)
195 *
196 * This is the xtable equivalent routine of aa_split_fqname. It finds the
197 * split in an xtable fqname which contains an embedded \0 instead of a :
198 * if a namespace is specified. This is done so the xtable is constant and
199 * isn't re-split on every lookup.
200 *
201 * Either the profile or namespace name may be optional but if the namespace
202 * is specified the profile name termination must be present. This results
203 * in the following possible encodings:
204 * profile_name\0
205 * :ns_name\0profile_name\0
206 * :ns_name\0\0
207 *
208 * NOTE: the xtable fqname is pre-validated at load time in unpack_trans_table
209 *
210 * Returns: profile name if it is specified else NULL
211 */
212static const char *separate_fqname(const char *fqname, const char **ns_name)
213{
214 const char *name;
215
216 if (fqname[0] == ':') {
217 /* In this case there is guaranteed to be two \0 terminators
218 * in the string. They are verified at load time by
219 * by unpack_trans_table
220 */
221 *ns_name = fqname + 1; /* skip : */
222 name = *ns_name + strlen(*ns_name) + 1;
223 if (!*name)
224 name = NULL;
225 } else {
226 *ns_name = NULL;
227 name = fqname;
228 }
229
230 return name;
231}
232
233static const char *next_name(int xtype, const char *name)
234{
235 return NULL;
236}
237
238/**
239 * x_table_lookup - lookup an x transition name via transition table
240 * @profile: current profile (NOT NULL)
241 * @xindex: index into x transition table
242 *
243 * Returns: refcounted profile, or NULL on failure (MAYBE NULL)
244 */
245static struct aa_profile *x_table_lookup(struct aa_profile *profile, u32 xindex)
246{
247 struct aa_profile *new_profile = NULL;
248 struct aa_namespace *ns = profile->ns;
249 u32 xtype = xindex & AA_X_TYPE_MASK;
250 int index = xindex & AA_X_INDEX_MASK;
251 const char *name;
252
253 /* index is guaranteed to be in range, validated at load time */
254 for (name = profile->file.trans.table[index]; !new_profile && name;
255 name = next_name(xtype, name)) {
256 struct aa_namespace *new_ns;
257 const char *xname = NULL;
258
259 new_ns = NULL;
260 if (xindex & AA_X_CHILD) {
261 /* release by caller */
262 new_profile = aa_find_child(profile, name);
263 continue;
264 } else if (*name == ':') {
265 /* switching namespace */
266 const char *ns_name;
267 xname = name = separate_fqname(name, &ns_name);
268 if (!xname)
269 /* no name so use profile name */
270 xname = profile->base.hname;
271 if (*ns_name == '@') {
272 /* TODO: variable support */
273 ;
274 }
275 /* released below */
276 new_ns = aa_find_namespace(ns, ns_name);
277 if (!new_ns)
278 continue;
279 } else if (*name == '@') {
280 /* TODO: variable support */
281 continue;
282 } else {
283 /* basic namespace lookup */
284 xname = name;
285 }
286
287 /* released by caller */
288 new_profile = aa_lookup_profile(new_ns ? new_ns : ns, xname);
289 aa_put_namespace(new_ns);
290 }
291
292 /* released by caller */
293 return new_profile;
294}
295
296/**
297 * x_to_profile - get target profile for a given xindex
298 * @profile: current profile (NOT NULL)
299 * @name: name to lookup (NOT NULL)
300 * @xindex: index into x transition table
301 *
302 * find profile for a transition index
303 *
304 * Returns: refcounted profile or NULL if not found available
305 */
306static struct aa_profile *x_to_profile(struct aa_profile *profile,
307 const char *name, u32 xindex)
308{
309 struct aa_profile *new_profile = NULL;
310 struct aa_namespace *ns = profile->ns;
311 u32 xtype = xindex & AA_X_TYPE_MASK;
312
313 switch (xtype) {
314 case AA_X_NONE:
315 /* fail exec unless ix || ux fallback - handled by caller */
316 return NULL;
317 case AA_X_NAME:
318 if (xindex & AA_X_CHILD)
319 /* released by caller */
320 new_profile = find_attach(ns, &profile->base.profiles,
321 name);
322 else
323 /* released by caller */
324 new_profile = find_attach(ns, &ns->base.profiles,
325 name);
326 break;
327 case AA_X_TABLE:
328 /* released by caller */
329 new_profile = x_table_lookup(profile, xindex);
330 break;
331 }
332
333 /* released by caller */
334 return new_profile;
335}
336
337/**
338 * apparmor_bprm_set_creds - set the new creds on the bprm struct
339 * @bprm: binprm for the exec (NOT NULL)
340 *
341 * Returns: %0 or error on failure
342 */
343int apparmor_bprm_set_creds(struct linux_binprm *bprm)
344{
345 struct aa_task_cxt *cxt;
346 struct aa_profile *profile, *new_profile = NULL;
347 struct aa_namespace *ns;
348 char *buffer = NULL;
349 unsigned int state;
350 struct file_perms perms = {};
351 struct path_cond cond = {
352 bprm->file->f_path.dentry->d_inode->i_uid,
353 bprm->file->f_path.dentry->d_inode->i_mode
354 };
355 const char *name = NULL, *target = NULL, *info = NULL;
356 int error = cap_bprm_set_creds(bprm);
357 if (error)
358 return error;
359
360 if (bprm->cred_prepared)
361 return 0;
362
363 cxt = bprm->cred->security;
364 BUG_ON(!cxt);
365
366 profile = aa_get_profile(aa_newest_version(cxt->profile));
367 /*
368 * get the namespace from the replacement profile as replacement
369 * can change the namespace
370 */
371 ns = profile->ns;
372 state = profile->file.start;
373
374 /* buffer freed below, name is pointer into buffer */
375 error = aa_path_name(&bprm->file->f_path, profile->path_flags, &buffer,
376 &name, &info);
377 if (error) {
378 if (profile->flags &
379 (PFLAG_IX_ON_NAME_ERROR | PFLAG_UNCONFINED))
380 error = 0;
381 name = bprm->filename;
382 goto audit;
383 }
384
385 /* Test for onexec first as onexec directives override other
386 * x transitions.
387 */
388 if (unconfined(profile)) {
389 /* unconfined task */
390 if (cxt->onexec)
391 /* change_profile on exec already been granted */
392 new_profile = aa_get_profile(cxt->onexec);
393 else
394 new_profile = find_attach(ns, &ns->base.profiles, name);
395 if (!new_profile)
396 goto cleanup;
397 /*
398 * NOTE: Domain transitions from unconfined are allowed
399 * even when no_new_privs is set because this aways results
400 * in a further reduction of permissions.
401 */
402 goto apply;
403 }
404
405 /* find exec permissions for name */
406 state = aa_str_perms(profile->file.dfa, state, name, &cond, &perms);
407 if (cxt->onexec) {
408 struct file_perms cp;
409 info = "change_profile onexec";
410 if (!(perms.allow & AA_MAY_ONEXEC))
411 goto audit;
412
413 /* test if this exec can be paired with change_profile onexec.
414 * onexec permission is linked to exec with a standard pairing
415 * exec\0change_profile
416 */
417 state = aa_dfa_null_transition(profile->file.dfa, state);
418 cp = change_profile_perms(profile, cxt->onexec->ns,
419 cxt->onexec->base.name,
420 AA_MAY_ONEXEC, state);
421
422 if (!(cp.allow & AA_MAY_ONEXEC))
423 goto audit;
424 new_profile = aa_get_profile(aa_newest_version(cxt->onexec));
425 goto apply;
426 }
427
428 if (perms.allow & MAY_EXEC) {
429 /* exec permission determine how to transition */
430 new_profile = x_to_profile(profile, name, perms.xindex);
431 if (!new_profile) {
432 if (perms.xindex & AA_X_INHERIT) {
433 /* (p|c|n)ix - don't change profile but do
434 * use the newest version, which was picked
435 * up above when getting profile
436 */
437 info = "ix fallback";
438 new_profile = aa_get_profile(profile);
439 goto x_clear;
440 } else if (perms.xindex & AA_X_UNCONFINED) {
441 new_profile = aa_get_profile(ns->unconfined);
442 info = "ux fallback";
443 } else {
444 error = -ENOENT;
445 info = "profile not found";
446 }
447 }
448 } else if (COMPLAIN_MODE(profile)) {
449 /* no exec permission - are we in learning mode */
450 new_profile = aa_new_null_profile(profile, 0);
451 if (!new_profile) {
452 error = -ENOMEM;
453 info = "could not create null profile";
454 } else {
455 error = -EACCES;
456 target = new_profile->base.hname;
457 }
458 perms.xindex |= AA_X_UNSAFE;
459 } else
460 /* fail exec */
461 error = -EACCES;
462
463 /*
464 * Policy has specified a domain transition, if no_new_privs then
465 * fail the exec.
466 */
467 if (bprm->unsafe & LSM_UNSAFE_NO_NEW_PRIVS) {
468 aa_put_profile(new_profile);
469 error = -EPERM;
470 goto cleanup;
471 }
472
473 if (!new_profile)
474 goto audit;
475
476 if (bprm->unsafe & LSM_UNSAFE_SHARE) {
477 /* FIXME: currently don't mediate shared state */
478 ;
479 }
480
481 if (bprm->unsafe & (LSM_UNSAFE_PTRACE | LSM_UNSAFE_PTRACE_CAP)) {
482 error = may_change_ptraced_domain(current, new_profile);
483 if (error) {
484 aa_put_profile(new_profile);
485 goto audit;
486 }
487 }
488
489 /* Determine if secure exec is needed.
490 * Can be at this point for the following reasons:
491 * 1. unconfined switching to confined
492 * 2. confined switching to different confinement
493 * 3. confined switching to unconfined
494 *
495 * Cases 2 and 3 are marked as requiring secure exec
496 * (unless policy specified "unsafe exec")
497 *
498 * bprm->unsafe is used to cache the AA_X_UNSAFE permission
499 * to avoid having to recompute in secureexec
500 */
501 if (!(perms.xindex & AA_X_UNSAFE)) {
502 AA_DEBUG("scrubbing environment variables for %s profile=%s\n",
503 name, new_profile->base.hname);
504 bprm->unsafe |= AA_SECURE_X_NEEDED;
505 }
506apply:
507 target = new_profile->base.hname;
508 /* when transitioning profiles clear unsafe personality bits */
509 bprm->per_clear |= PER_CLEAR_ON_SETID;
510
511x_clear:
512 aa_put_profile(cxt->profile);
513 /* transfer new profile reference will be released when cxt is freed */
514 cxt->profile = new_profile;
515
516 /* clear out all temporary/transitional state from the context */
517 aa_put_profile(cxt->previous);
518 aa_put_profile(cxt->onexec);
519 cxt->previous = NULL;
520 cxt->onexec = NULL;
521 cxt->token = 0;
522
523audit:
524 error = aa_audit_file(profile, &perms, GFP_KERNEL, OP_EXEC, MAY_EXEC,
525 name, target, cond.uid, info, error);
526
527cleanup:
528 aa_put_profile(profile);
529 kfree(buffer);
530
531 return error;
532}
533
534/**
535 * apparmor_bprm_secureexec - determine if secureexec is needed
536 * @bprm: binprm for exec (NOT NULL)
537 *
538 * Returns: %1 if secureexec is needed else %0
539 */
540int apparmor_bprm_secureexec(struct linux_binprm *bprm)
541{
542 int ret = cap_bprm_secureexec(bprm);
543
544 /* the decision to use secure exec is computed in set_creds
545 * and stored in bprm->unsafe.
546 */
547 if (!ret && (bprm->unsafe & AA_SECURE_X_NEEDED))
548 ret = 1;
549
550 return ret;
551}
552
553/**
554 * apparmor_bprm_committing_creds - do task cleanup on committing new creds
555 * @bprm: binprm for the exec (NOT NULL)
556 */
557void apparmor_bprm_committing_creds(struct linux_binprm *bprm)
558{
559 struct aa_profile *profile = __aa_current_profile();
560 struct aa_task_cxt *new_cxt = bprm->cred->security;
561
562 /* bail out if unconfined or not changing profile */
563 if ((new_cxt->profile == profile) ||
564 (unconfined(new_cxt->profile)))
565 return;
566
567 current->pdeath_signal = 0;
568
569 /* reset soft limits and set hard limits for the new profile */
570 __aa_transition_rlimits(profile, new_cxt->profile);
571}
572
573/**
574 * apparmor_bprm_commited_cred - do cleanup after new creds committed
575 * @bprm: binprm for the exec (NOT NULL)
576 */
577void apparmor_bprm_committed_creds(struct linux_binprm *bprm)
578{
579 /* TODO: cleanup signals - ipc mediation */
580 return;
581}
582
583/*
584 * Functions for self directed profile change
585 */
586
587/**
588 * new_compound_name - create an hname with @n2 appended to @n1
589 * @n1: base of hname (NOT NULL)
590 * @n2: name to append (NOT NULL)
591 *
592 * Returns: new name or NULL on error
593 */
594static char *new_compound_name(const char *n1, const char *n2)
595{
596 char *name = kmalloc(strlen(n1) + strlen(n2) + 3, GFP_KERNEL);
597 if (name)
598 sprintf(name, "%s//%s", n1, n2);
599 return name;
600}
601
602/**
603 * aa_change_hat - change hat to/from subprofile
604 * @hats: vector of hat names to try changing into (MAYBE NULL if @count == 0)
605 * @count: number of hat names in @hats
606 * @token: magic value to validate the hat change
607 * @permtest: true if this is just a permission test
608 *
609 * Change to the first profile specified in @hats that exists, and store
610 * the @hat_magic in the current task context. If the count == 0 and the
611 * @token matches that stored in the current task context, return to the
612 * top level profile.
613 *
614 * Returns %0 on success, error otherwise.
615 */
616int aa_change_hat(const char *hats[], int count, u64 token, bool permtest)
617{
618 const struct cred *cred;
619 struct aa_task_cxt *cxt;
620 struct aa_profile *profile, *previous_profile, *hat = NULL;
621 char *name = NULL;
622 int i;
623 struct file_perms perms = {};
624 const char *target = NULL, *info = NULL;
625 int error = 0;
626
627 /*
628 * Fail explicitly requested domain transitions if no_new_privs.
629 * There is no exception for unconfined as change_hat is not
630 * available.
631 */
632 if (current->no_new_privs)
633 return -EPERM;
634
635 /* released below */
636 cred = get_current_cred();
637 cxt = cred->security;
638 profile = aa_cred_profile(cred);
639 previous_profile = cxt->previous;
640
641 if (unconfined(profile)) {
642 info = "unconfined";
643 error = -EPERM;
644 goto audit;
645 }
646
647 if (count) {
648 /* attempting to change into a new hat or switch to a sibling */
649 struct aa_profile *root;
650 root = PROFILE_IS_HAT(profile) ? profile->parent : profile;
651
652 /* find first matching hat */
653 for (i = 0; i < count && !hat; i++)
654 /* released below */
655 hat = aa_find_child(root, hats[i]);
656 if (!hat) {
657 if (!COMPLAIN_MODE(root) || permtest) {
658 if (list_empty(&root->base.profiles))
659 error = -ECHILD;
660 else
661 error = -ENOENT;
662 goto out;
663 }
664
665 /*
666 * In complain mode and failed to match any hats.
667 * Audit the failure is based off of the first hat
668 * supplied. This is done due how userspace
669 * interacts with change_hat.
670 *
671 * TODO: Add logging of all failed hats
672 */
673
674 /* freed below */
675 name = new_compound_name(root->base.hname, hats[0]);
676 target = name;
677 /* released below */
678 hat = aa_new_null_profile(profile, 1);
679 if (!hat) {
680 info = "failed null profile create";
681 error = -ENOMEM;
682 goto audit;
683 }
684 } else {
685 target = hat->base.hname;
686 if (!PROFILE_IS_HAT(hat)) {
687 info = "target not hat";
688 error = -EPERM;
689 goto audit;
690 }
691 }
692
693 error = may_change_ptraced_domain(current, hat);
694 if (error) {
695 info = "ptraced";
696 error = -EPERM;
697 goto audit;
698 }
699
700 if (!permtest) {
701 error = aa_set_current_hat(hat, token);
702 if (error == -EACCES)
703 /* kill task in case of brute force attacks */
704 perms.kill = AA_MAY_CHANGEHAT;
705 else if (name && !error)
706 /* reset error for learning of new hats */
707 error = -ENOENT;
708 }
709 } else if (previous_profile) {
710 /* Return to saved profile. Kill task if restore fails
711 * to avoid brute force attacks
712 */
713 target = previous_profile->base.hname;
714 error = aa_restore_previous_profile(token);
715 perms.kill = AA_MAY_CHANGEHAT;
716 } else
717 /* ignore restores when there is no saved profile */
718 goto out;
719
720audit:
721 if (!permtest)
722 error = aa_audit_file(profile, &perms, GFP_KERNEL,
723 OP_CHANGE_HAT, AA_MAY_CHANGEHAT, NULL,
724 target, 0, info, error);
725
726out:
727 aa_put_profile(hat);
728 kfree(name);
729 put_cred(cred);
730
731 return error;
732}
733
734/**
735 * aa_change_profile - perform a one-way profile transition
736 * @ns_name: name of the profile namespace to change to (MAYBE NULL)
737 * @hname: name of profile to change to (MAYBE NULL)
738 * @onexec: whether this transition is to take place immediately or at exec
739 * @permtest: true if this is just a permission test
740 *
741 * Change to new profile @name. Unlike with hats, there is no way
742 * to change back. If @name isn't specified the current profile name is
743 * used.
744 * If @onexec then the transition is delayed until
745 * the next exec.
746 *
747 * Returns %0 on success, error otherwise.
748 */
749int aa_change_profile(const char *ns_name, const char *hname, bool onexec,
750 bool permtest)
751{
752 const struct cred *cred;
753 struct aa_task_cxt *cxt;
754 struct aa_profile *profile, *target = NULL;
755 struct aa_namespace *ns = NULL;
756 struct file_perms perms = {};
757 const char *name = NULL, *info = NULL;
758 int op, error = 0;
759 u32 request;
760
761 if (!hname && !ns_name)
762 return -EINVAL;
763
764 if (onexec) {
765 request = AA_MAY_ONEXEC;
766 op = OP_CHANGE_ONEXEC;
767 } else {
768 request = AA_MAY_CHANGE_PROFILE;
769 op = OP_CHANGE_PROFILE;
770 }
771
772 cred = get_current_cred();
773 cxt = cred->security;
774 profile = aa_cred_profile(cred);
775
776 /*
777 * Fail explicitly requested domain transitions if no_new_privs
778 * and not unconfined.
779 * Domain transitions from unconfined are allowed even when
780 * no_new_privs is set because this aways results in a reduction
781 * of permissions.
782 */
783 if (current->no_new_privs && !unconfined(profile)) {
784 put_cred(cred);
785 return -EPERM;
786 }
787
788 if (ns_name) {
789 /* released below */
790 ns = aa_find_namespace(profile->ns, ns_name);
791 if (!ns) {
792 /* we don't create new namespace in complain mode */
793 name = ns_name;
794 info = "namespace not found";
795 error = -ENOENT;
796 goto audit;
797 }
798 } else
799 /* released below */
800 ns = aa_get_namespace(profile->ns);
801
802 /* if the name was not specified, use the name of the current profile */
803 if (!hname) {
804 if (unconfined(profile))
805 hname = ns->unconfined->base.hname;
806 else
807 hname = profile->base.hname;
808 }
809
810 perms = change_profile_perms(profile, ns, hname, request,
811 profile->file.start);
812 if (!(perms.allow & request)) {
813 error = -EACCES;
814 goto audit;
815 }
816
817 /* released below */
818 target = aa_lookup_profile(ns, hname);
819 if (!target) {
820 info = "profile not found";
821 error = -ENOENT;
822 if (permtest || !COMPLAIN_MODE(profile))
823 goto audit;
824 /* released below */
825 target = aa_new_null_profile(profile, 0);
826 if (!target) {
827 info = "failed null profile create";
828 error = -ENOMEM;
829 goto audit;
830 }
831 }
832
833 /* check if tracing task is allowed to trace target domain */
834 error = may_change_ptraced_domain(current, target);
835 if (error) {
836 info = "ptrace prevents transition";
837 goto audit;
838 }
839
840 if (permtest)
841 goto audit;
842
843 if (onexec)
844 error = aa_set_current_onexec(target);
845 else
846 error = aa_replace_current_profile(target);
847
848audit:
849 if (!permtest)
850 error = aa_audit_file(profile, &perms, GFP_KERNEL, op, request,
851 name, hname, 0, info, error);
852
853 aa_put_namespace(ns);
854 aa_put_profile(target);
855 put_cred(cred);
856
857 return error;
858}
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/fs.h>
14#include <linux/file.h>
15#include <linux/mount.h>
16#include <linux/syscalls.h>
17#include <linux/tracehook.h>
18#include <linux/personality.h>
19#include <linux/xattr.h>
20#include <linux/user_namespace.h>
21
22#include "include/audit.h"
23#include "include/apparmorfs.h"
24#include "include/cred.h"
25#include "include/domain.h"
26#include "include/file.h"
27#include "include/ipc.h"
28#include "include/match.h"
29#include "include/path.h"
30#include "include/policy.h"
31#include "include/policy_ns.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 kfree_sensitive(domain->table[i]);
46 kfree_sensitive(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_label: profile to change to (NOT NULL)
54 * @info: message if there is an error
55 *
56 * Check if current is ptraced and if so if the tracing task is allowed
57 * to trace the new domain
58 *
59 * Returns: %0 or error if change not allowed
60 */
61static int may_change_ptraced_domain(struct aa_label *to_label,
62 const char **info)
63{
64 struct task_struct *tracer;
65 struct aa_label *tracerl = NULL;
66 int error = 0;
67
68 rcu_read_lock();
69 tracer = ptrace_parent(current);
70 if (tracer)
71 /* released below */
72 tracerl = aa_get_task_label(tracer);
73
74 /* not ptraced */
75 if (!tracer || unconfined(tracerl))
76 goto out;
77
78 error = aa_may_ptrace(tracerl, to_label, PTRACE_MODE_ATTACH);
79
80out:
81 rcu_read_unlock();
82 aa_put_label(tracerl);
83
84 if (error)
85 *info = "ptrace prevents transition";
86 return error;
87}
88
89/**** TODO: dedup to aa_label_match - needs perm and dfa, merging
90 * specifically this is an exact copy of aa_label_match except
91 * aa_compute_perms is replaced with aa_compute_fperms
92 * and policy.dfa with file.dfa
93 ****/
94/* match a profile and its associated ns component if needed
95 * Assumes visibility test has already been done.
96 * If a subns profile is not to be matched should be prescreened with
97 * visibility test.
98 */
99static inline unsigned int match_component(struct aa_profile *profile,
100 struct aa_profile *tp,
101 bool stack, unsigned int state)
102{
103 const char *ns_name;
104
105 if (stack)
106 state = aa_dfa_match(profile->file.dfa, state, "&");
107 if (profile->ns == tp->ns)
108 return aa_dfa_match(profile->file.dfa, state, tp->base.hname);
109
110 /* try matching with namespace name and then profile */
111 ns_name = aa_ns_name(profile->ns, tp->ns, true);
112 state = aa_dfa_match_len(profile->file.dfa, state, ":", 1);
113 state = aa_dfa_match(profile->file.dfa, state, ns_name);
114 state = aa_dfa_match_len(profile->file.dfa, state, ":", 1);
115 return aa_dfa_match(profile->file.dfa, state, tp->base.hname);
116}
117
118/**
119 * label_compound_match - find perms for full compound label
120 * @profile: profile to find perms for
121 * @label: label to check access permissions for
122 * @stack: whether this is a stacking request
123 * @start: state to start match in
124 * @subns: whether to do permission checks on components in a subns
125 * @request: permissions to request
126 * @perms: perms struct to set
127 *
128 * Returns: 0 on success else ERROR
129 *
130 * For the label A//&B//&C this does the perm match for A//&B//&C
131 * @perms should be preinitialized with allperms OR a previous permission
132 * check to be stacked.
133 */
134static int label_compound_match(struct aa_profile *profile,
135 struct aa_label *label, bool stack,
136 unsigned int state, bool subns, u32 request,
137 struct aa_perms *perms)
138{
139 struct aa_profile *tp;
140 struct label_it i;
141 struct path_cond cond = { };
142
143 /* find first subcomponent that is visible */
144 label_for_each(i, label, tp) {
145 if (!aa_ns_visible(profile->ns, tp->ns, subns))
146 continue;
147 state = match_component(profile, tp, stack, state);
148 if (!state)
149 goto fail;
150 goto next;
151 }
152
153 /* no component visible */
154 *perms = allperms;
155 return 0;
156
157next:
158 label_for_each_cont(i, label, tp) {
159 if (!aa_ns_visible(profile->ns, tp->ns, subns))
160 continue;
161 state = aa_dfa_match(profile->file.dfa, state, "//&");
162 state = match_component(profile, tp, false, state);
163 if (!state)
164 goto fail;
165 }
166 *perms = aa_compute_fperms(profile->file.dfa, state, &cond);
167 aa_apply_modes_to_perms(profile, perms);
168 if ((perms->allow & request) != request)
169 return -EACCES;
170
171 return 0;
172
173fail:
174 *perms = nullperms;
175 return -EACCES;
176}
177
178/**
179 * label_components_match - find perms for all subcomponents of a label
180 * @profile: profile to find perms for
181 * @label: label to check access permissions for
182 * @stack: whether this is a stacking request
183 * @start: state to start match in
184 * @subns: whether to do permission checks on components in a subns
185 * @request: permissions to request
186 * @perms: an initialized perms struct to add accumulation to
187 *
188 * Returns: 0 on success else ERROR
189 *
190 * For the label A//&B//&C this does the perm match for each of A and B and C
191 * @perms should be preinitialized with allperms OR a previous permission
192 * check to be stacked.
193 */
194static int label_components_match(struct aa_profile *profile,
195 struct aa_label *label, bool stack,
196 unsigned int start, bool subns, u32 request,
197 struct aa_perms *perms)
198{
199 struct aa_profile *tp;
200 struct label_it i;
201 struct aa_perms tmp;
202 struct path_cond cond = { };
203 unsigned int state = 0;
204
205 /* find first subcomponent to test */
206 label_for_each(i, label, tp) {
207 if (!aa_ns_visible(profile->ns, tp->ns, subns))
208 continue;
209 state = match_component(profile, tp, stack, start);
210 if (!state)
211 goto fail;
212 goto next;
213 }
214
215 /* no subcomponents visible - no change in perms */
216 return 0;
217
218next:
219 tmp = aa_compute_fperms(profile->file.dfa, state, &cond);
220 aa_apply_modes_to_perms(profile, &tmp);
221 aa_perms_accum(perms, &tmp);
222 label_for_each_cont(i, label, tp) {
223 if (!aa_ns_visible(profile->ns, tp->ns, subns))
224 continue;
225 state = match_component(profile, tp, stack, start);
226 if (!state)
227 goto fail;
228 tmp = aa_compute_fperms(profile->file.dfa, state, &cond);
229 aa_apply_modes_to_perms(profile, &tmp);
230 aa_perms_accum(perms, &tmp);
231 }
232
233 if ((perms->allow & request) != request)
234 return -EACCES;
235
236 return 0;
237
238fail:
239 *perms = nullperms;
240 return -EACCES;
241}
242
243/**
244 * label_match - do a multi-component label match
245 * @profile: profile to match against (NOT NULL)
246 * @label: label to match (NOT NULL)
247 * @stack: whether this is a stacking request
248 * @state: state to start in
249 * @subns: whether to match subns components
250 * @request: permission request
251 * @perms: Returns computed perms (NOT NULL)
252 *
253 * Returns: the state the match finished in, may be the none matching state
254 */
255static int label_match(struct aa_profile *profile, struct aa_label *label,
256 bool stack, unsigned int state, bool subns, u32 request,
257 struct aa_perms *perms)
258{
259 int error;
260
261 *perms = nullperms;
262 error = label_compound_match(profile, label, stack, state, subns,
263 request, perms);
264 if (!error)
265 return error;
266
267 *perms = allperms;
268 return label_components_match(profile, label, stack, state, subns,
269 request, perms);
270}
271
272/******* end TODO: dedup *****/
273
274/**
275 * change_profile_perms - find permissions for change_profile
276 * @profile: the current profile (NOT NULL)
277 * @target: label to transition to (NOT NULL)
278 * @stack: whether this is a stacking request
279 * @request: requested perms
280 * @start: state to start matching in
281 *
282 *
283 * Returns: permission set
284 *
285 * currently only matches full label A//&B//&C or individual components A, B, C
286 * not arbitrary combinations. Eg. A//&B, C
287 */
288static int change_profile_perms(struct aa_profile *profile,
289 struct aa_label *target, bool stack,
290 u32 request, unsigned int start,
291 struct aa_perms *perms)
292{
293 if (profile_unconfined(profile)) {
294 perms->allow = AA_MAY_CHANGE_PROFILE | AA_MAY_ONEXEC;
295 perms->audit = perms->quiet = perms->kill = 0;
296 return 0;
297 }
298
299 /* TODO: add profile in ns screening */
300 return label_match(profile, target, stack, start, true, request, perms);
301}
302
303/**
304 * aa_xattrs_match - check whether a file matches the xattrs defined in profile
305 * @bprm: binprm struct for the process to validate
306 * @profile: profile to match against (NOT NULL)
307 * @state: state to start match in
308 *
309 * Returns: number of extended attributes that matched, or < 0 on error
310 */
311static int aa_xattrs_match(const struct linux_binprm *bprm,
312 struct aa_profile *profile, unsigned int state)
313{
314 int i;
315 ssize_t size;
316 struct dentry *d;
317 char *value = NULL;
318 int value_size = 0, ret = profile->xattr_count;
319
320 if (!bprm || !profile->xattr_count)
321 return 0;
322 might_sleep();
323
324 /* transition from exec match to xattr set */
325 state = aa_dfa_outofband_transition(profile->xmatch, state);
326 d = bprm->file->f_path.dentry;
327
328 for (i = 0; i < profile->xattr_count; i++) {
329 size = vfs_getxattr_alloc(&init_user_ns, d, profile->xattrs[i],
330 &value, value_size, GFP_KERNEL);
331 if (size >= 0) {
332 u32 perm;
333
334 /*
335 * Check the xattr presence before value. This ensure
336 * that not present xattr can be distinguished from a 0
337 * length value or rule that matches any value
338 */
339 state = aa_dfa_null_transition(profile->xmatch, state);
340 /* Check xattr value */
341 state = aa_dfa_match_len(profile->xmatch, state, value,
342 size);
343 perm = dfa_user_allow(profile->xmatch, state);
344 if (!(perm & MAY_EXEC)) {
345 ret = -EINVAL;
346 goto out;
347 }
348 }
349 /* transition to next element */
350 state = aa_dfa_outofband_transition(profile->xmatch, state);
351 if (size < 0) {
352 /*
353 * No xattr match, so verify if transition to
354 * next element was valid. IFF so the xattr
355 * was optional.
356 */
357 if (!state) {
358 ret = -EINVAL;
359 goto out;
360 }
361 /* don't count missing optional xattr as matched */
362 ret--;
363 }
364 }
365
366out:
367 kfree(value);
368 return ret;
369}
370
371/**
372 * find_attach - do attachment search for unconfined processes
373 * @bprm - binprm structure of transitioning task
374 * @ns: the current namespace (NOT NULL)
375 * @head - profile list to walk (NOT NULL)
376 * @name - to match against (NOT NULL)
377 * @info - info message if there was an error (NOT NULL)
378 *
379 * Do a linear search on the profiles in the list. There is a matching
380 * preference where an exact match is preferred over a name which uses
381 * expressions to match, and matching expressions with the greatest
382 * xmatch_len are preferred.
383 *
384 * Requires: @head not be shared or have appropriate locks held
385 *
386 * Returns: label or NULL if no match found
387 */
388static struct aa_label *find_attach(const struct linux_binprm *bprm,
389 struct aa_ns *ns, struct list_head *head,
390 const char *name, const char **info)
391{
392 int candidate_len = 0, candidate_xattrs = 0;
393 bool conflict = false;
394 struct aa_profile *profile, *candidate = NULL;
395
396 AA_BUG(!name);
397 AA_BUG(!head);
398
399 rcu_read_lock();
400restart:
401 list_for_each_entry_rcu(profile, head, base.list) {
402 if (profile->label.flags & FLAG_NULL &&
403 &profile->label == ns_unconfined(profile->ns))
404 continue;
405
406 /* Find the "best" matching profile. Profiles must
407 * match the path and extended attributes (if any)
408 * associated with the file. A more specific path
409 * match will be preferred over a less specific one,
410 * and a match with more matching extended attributes
411 * will be preferred over one with fewer. If the best
412 * match has both the same level of path specificity
413 * and the same number of matching extended attributes
414 * as another profile, signal a conflict and refuse to
415 * match.
416 */
417 if (profile->xmatch) {
418 unsigned int state, count;
419 u32 perm;
420
421 state = aa_dfa_leftmatch(profile->xmatch, DFA_START,
422 name, &count);
423 perm = dfa_user_allow(profile->xmatch, state);
424 /* any accepting state means a valid match. */
425 if (perm & MAY_EXEC) {
426 int ret = 0;
427
428 if (count < candidate_len)
429 continue;
430
431 if (bprm && profile->xattr_count) {
432 long rev = READ_ONCE(ns->revision);
433
434 if (!aa_get_profile_not0(profile))
435 goto restart;
436 rcu_read_unlock();
437 ret = aa_xattrs_match(bprm, profile,
438 state);
439 rcu_read_lock();
440 aa_put_profile(profile);
441 if (rev !=
442 READ_ONCE(ns->revision))
443 /* policy changed */
444 goto restart;
445 /*
446 * Fail matching if the xattrs don't
447 * match
448 */
449 if (ret < 0)
450 continue;
451 }
452 /*
453 * TODO: allow for more flexible best match
454 *
455 * The new match isn't more specific
456 * than the current best match
457 */
458 if (count == candidate_len &&
459 ret <= candidate_xattrs) {
460 /* Match is equivalent, so conflict */
461 if (ret == candidate_xattrs)
462 conflict = true;
463 continue;
464 }
465
466 /* Either the same length with more matching
467 * xattrs, or a longer match
468 */
469 candidate = profile;
470 candidate_len = profile->xmatch_len;
471 candidate_xattrs = ret;
472 conflict = false;
473 }
474 } else if (!strcmp(profile->base.name, name)) {
475 /*
476 * old exact non-re match, without conditionals such
477 * as xattrs. no more searching required
478 */
479 candidate = profile;
480 goto out;
481 }
482 }
483
484 if (!candidate || conflict) {
485 if (conflict)
486 *info = "conflicting profile attachments";
487 rcu_read_unlock();
488 return NULL;
489 }
490
491out:
492 candidate = aa_get_newest_profile(candidate);
493 rcu_read_unlock();
494
495 return &candidate->label;
496}
497
498static const char *next_name(int xtype, const char *name)
499{
500 return NULL;
501}
502
503/**
504 * x_table_lookup - lookup an x transition name via transition table
505 * @profile: current profile (NOT NULL)
506 * @xindex: index into x transition table
507 * @name: returns: name tested to find label (NOT NULL)
508 *
509 * Returns: refcounted label, or NULL on failure (MAYBE NULL)
510 */
511struct aa_label *x_table_lookup(struct aa_profile *profile, u32 xindex,
512 const char **name)
513{
514 struct aa_label *label = NULL;
515 u32 xtype = xindex & AA_X_TYPE_MASK;
516 int index = xindex & AA_X_INDEX_MASK;
517
518 AA_BUG(!name);
519
520 /* index is guaranteed to be in range, validated at load time */
521 /* TODO: move lookup parsing to unpack time so this is a straight
522 * index into the resultant label
523 */
524 for (*name = profile->file.trans.table[index]; !label && *name;
525 *name = next_name(xtype, *name)) {
526 if (xindex & AA_X_CHILD) {
527 struct aa_profile *new_profile;
528 /* release by caller */
529 new_profile = aa_find_child(profile, *name);
530 if (new_profile)
531 label = &new_profile->label;
532 continue;
533 }
534 label = aa_label_parse(&profile->label, *name, GFP_KERNEL,
535 true, false);
536 if (IS_ERR(label))
537 label = NULL;
538 }
539
540 /* released by caller */
541
542 return label;
543}
544
545/**
546 * x_to_label - get target label for a given xindex
547 * @profile: current profile (NOT NULL)
548 * @bprm: binprm structure of transitioning task
549 * @name: name to lookup (NOT NULL)
550 * @xindex: index into x transition table
551 * @lookupname: returns: name used in lookup if one was specified (NOT NULL)
552 *
553 * find label for a transition index
554 *
555 * Returns: refcounted label or NULL if not found available
556 */
557static struct aa_label *x_to_label(struct aa_profile *profile,
558 const struct linux_binprm *bprm,
559 const char *name, u32 xindex,
560 const char **lookupname,
561 const char **info)
562{
563 struct aa_label *new = NULL;
564 struct aa_ns *ns = profile->ns;
565 u32 xtype = xindex & AA_X_TYPE_MASK;
566 const char *stack = NULL;
567
568 switch (xtype) {
569 case AA_X_NONE:
570 /* fail exec unless ix || ux fallback - handled by caller */
571 *lookupname = NULL;
572 break;
573 case AA_X_TABLE:
574 /* TODO: fix when perm mapping done at unload */
575 stack = profile->file.trans.table[xindex & AA_X_INDEX_MASK];
576 if (*stack != '&') {
577 /* released by caller */
578 new = x_table_lookup(profile, xindex, lookupname);
579 stack = NULL;
580 break;
581 }
582 fallthrough; /* to X_NAME */
583 case AA_X_NAME:
584 if (xindex & AA_X_CHILD)
585 /* released by caller */
586 new = find_attach(bprm, ns, &profile->base.profiles,
587 name, info);
588 else
589 /* released by caller */
590 new = find_attach(bprm, ns, &ns->base.profiles,
591 name, info);
592 *lookupname = name;
593 break;
594 }
595
596 if (!new) {
597 if (xindex & AA_X_INHERIT) {
598 /* (p|c|n)ix - don't change profile but do
599 * use the newest version
600 */
601 *info = "ix fallback";
602 /* no profile && no error */
603 new = aa_get_newest_label(&profile->label);
604 } else if (xindex & AA_X_UNCONFINED) {
605 new = aa_get_newest_label(ns_unconfined(profile->ns));
606 *info = "ux fallback";
607 }
608 }
609
610 if (new && stack) {
611 /* base the stack on post domain transition */
612 struct aa_label *base = new;
613
614 new = aa_label_parse(base, stack, GFP_KERNEL, true, false);
615 if (IS_ERR(new))
616 new = NULL;
617 aa_put_label(base);
618 }
619
620 /* released by caller */
621 return new;
622}
623
624static struct aa_label *profile_transition(struct aa_profile *profile,
625 const struct linux_binprm *bprm,
626 char *buffer, struct path_cond *cond,
627 bool *secure_exec)
628{
629 struct aa_label *new = NULL;
630 const char *info = NULL, *name = NULL, *target = NULL;
631 unsigned int state = profile->file.start;
632 struct aa_perms perms = {};
633 bool nonewprivs = false;
634 int error = 0;
635
636 AA_BUG(!profile);
637 AA_BUG(!bprm);
638 AA_BUG(!buffer);
639
640 error = aa_path_name(&bprm->file->f_path, profile->path_flags, buffer,
641 &name, &info, profile->disconnected);
642 if (error) {
643 if (profile_unconfined(profile) ||
644 (profile->label.flags & FLAG_IX_ON_NAME_ERROR)) {
645 AA_DEBUG("name lookup ix on error");
646 error = 0;
647 new = aa_get_newest_label(&profile->label);
648 }
649 name = bprm->filename;
650 goto audit;
651 }
652
653 if (profile_unconfined(profile)) {
654 new = find_attach(bprm, profile->ns,
655 &profile->ns->base.profiles, name, &info);
656 if (new) {
657 AA_DEBUG("unconfined attached to new label");
658 return new;
659 }
660 AA_DEBUG("unconfined exec no attachment");
661 return aa_get_newest_label(&profile->label);
662 }
663
664 /* find exec permissions for name */
665 state = aa_str_perms(profile->file.dfa, state, name, cond, &perms);
666 if (perms.allow & MAY_EXEC) {
667 /* exec permission determine how to transition */
668 new = x_to_label(profile, bprm, name, perms.xindex, &target,
669 &info);
670 if (new && new->proxy == profile->label.proxy && info) {
671 /* hack ix fallback - improve how this is detected */
672 goto audit;
673 } else if (!new) {
674 error = -EACCES;
675 info = "profile transition not found";
676 /* remove MAY_EXEC to audit as failure */
677 perms.allow &= ~MAY_EXEC;
678 }
679 } else if (COMPLAIN_MODE(profile)) {
680 /* no exec permission - learning mode */
681 struct aa_profile *new_profile = NULL;
682
683 new_profile = aa_new_null_profile(profile, false, name,
684 GFP_KERNEL);
685 if (!new_profile) {
686 error = -ENOMEM;
687 info = "could not create null profile";
688 } else {
689 error = -EACCES;
690 new = &new_profile->label;
691 }
692 perms.xindex |= AA_X_UNSAFE;
693 } else
694 /* fail exec */
695 error = -EACCES;
696
697 if (!new)
698 goto audit;
699
700
701 if (!(perms.xindex & AA_X_UNSAFE)) {
702 if (DEBUG_ON) {
703 dbg_printk("apparmor: scrubbing environment variables"
704 " for %s profile=", name);
705 aa_label_printk(new, GFP_KERNEL);
706 dbg_printk("\n");
707 }
708 *secure_exec = true;
709 }
710
711audit:
712 aa_audit_file(profile, &perms, OP_EXEC, MAY_EXEC, name, target, new,
713 cond->uid, info, error);
714 if (!new || nonewprivs) {
715 aa_put_label(new);
716 return ERR_PTR(error);
717 }
718
719 return new;
720}
721
722static int profile_onexec(struct aa_profile *profile, struct aa_label *onexec,
723 bool stack, const struct linux_binprm *bprm,
724 char *buffer, struct path_cond *cond,
725 bool *secure_exec)
726{
727 unsigned int state = profile->file.start;
728 struct aa_perms perms = {};
729 const char *xname = NULL, *info = "change_profile onexec";
730 int error = -EACCES;
731
732 AA_BUG(!profile);
733 AA_BUG(!onexec);
734 AA_BUG(!bprm);
735 AA_BUG(!buffer);
736
737 if (profile_unconfined(profile)) {
738 /* change_profile on exec already granted */
739 /*
740 * NOTE: Domain transitions from unconfined are allowed
741 * even when no_new_privs is set because this aways results
742 * in a further reduction of permissions.
743 */
744 return 0;
745 }
746
747 error = aa_path_name(&bprm->file->f_path, profile->path_flags, buffer,
748 &xname, &info, profile->disconnected);
749 if (error) {
750 if (profile_unconfined(profile) ||
751 (profile->label.flags & FLAG_IX_ON_NAME_ERROR)) {
752 AA_DEBUG("name lookup ix on error");
753 error = 0;
754 }
755 xname = bprm->filename;
756 goto audit;
757 }
758
759 /* find exec permissions for name */
760 state = aa_str_perms(profile->file.dfa, state, xname, cond, &perms);
761 if (!(perms.allow & AA_MAY_ONEXEC)) {
762 info = "no change_onexec valid for executable";
763 goto audit;
764 }
765 /* test if this exec can be paired with change_profile onexec.
766 * onexec permission is linked to exec with a standard pairing
767 * exec\0change_profile
768 */
769 state = aa_dfa_null_transition(profile->file.dfa, state);
770 error = change_profile_perms(profile, onexec, stack, AA_MAY_ONEXEC,
771 state, &perms);
772 if (error) {
773 perms.allow &= ~AA_MAY_ONEXEC;
774 goto audit;
775 }
776
777 if (!(perms.xindex & AA_X_UNSAFE)) {
778 if (DEBUG_ON) {
779 dbg_printk("apparmor: scrubbing environment "
780 "variables for %s label=", xname);
781 aa_label_printk(onexec, GFP_KERNEL);
782 dbg_printk("\n");
783 }
784 *secure_exec = true;
785 }
786
787audit:
788 return aa_audit_file(profile, &perms, OP_EXEC, AA_MAY_ONEXEC, xname,
789 NULL, onexec, cond->uid, info, error);
790}
791
792/* ensure none ns domain transitions are correctly applied with onexec */
793
794static struct aa_label *handle_onexec(struct aa_label *label,
795 struct aa_label *onexec, bool stack,
796 const struct linux_binprm *bprm,
797 char *buffer, struct path_cond *cond,
798 bool *unsafe)
799{
800 struct aa_profile *profile;
801 struct aa_label *new;
802 int error;
803
804 AA_BUG(!label);
805 AA_BUG(!onexec);
806 AA_BUG(!bprm);
807 AA_BUG(!buffer);
808
809 if (!stack) {
810 error = fn_for_each_in_ns(label, profile,
811 profile_onexec(profile, onexec, stack,
812 bprm, buffer, cond, unsafe));
813 if (error)
814 return ERR_PTR(error);
815 new = fn_label_build_in_ns(label, profile, GFP_KERNEL,
816 aa_get_newest_label(onexec),
817 profile_transition(profile, bprm, buffer,
818 cond, unsafe));
819
820 } else {
821 /* TODO: determine how much we want to loosen this */
822 error = fn_for_each_in_ns(label, profile,
823 profile_onexec(profile, onexec, stack, bprm,
824 buffer, cond, unsafe));
825 if (error)
826 return ERR_PTR(error);
827 new = fn_label_build_in_ns(label, profile, GFP_KERNEL,
828 aa_label_merge(&profile->label, onexec,
829 GFP_KERNEL),
830 profile_transition(profile, bprm, buffer,
831 cond, unsafe));
832 }
833
834 if (new)
835 return new;
836
837 /* TODO: get rid of GLOBAL_ROOT_UID */
838 error = fn_for_each_in_ns(label, profile,
839 aa_audit_file(profile, &nullperms, OP_CHANGE_ONEXEC,
840 AA_MAY_ONEXEC, bprm->filename, NULL,
841 onexec, GLOBAL_ROOT_UID,
842 "failed to build target label", -ENOMEM));
843 return ERR_PTR(error);
844}
845
846/**
847 * apparmor_bprm_creds_for_exec - Update the new creds on the bprm struct
848 * @bprm: binprm for the exec (NOT NULL)
849 *
850 * Returns: %0 or error on failure
851 *
852 * TODO: once the other paths are done see if we can't refactor into a fn
853 */
854int apparmor_bprm_creds_for_exec(struct linux_binprm *bprm)
855{
856 struct aa_task_ctx *ctx;
857 struct aa_label *label, *new = NULL;
858 struct aa_profile *profile;
859 char *buffer = NULL;
860 const char *info = NULL;
861 int error = 0;
862 bool unsafe = false;
863 kuid_t i_uid = i_uid_into_mnt(file_mnt_user_ns(bprm->file),
864 file_inode(bprm->file));
865 struct path_cond cond = {
866 i_uid,
867 file_inode(bprm->file)->i_mode
868 };
869
870 ctx = task_ctx(current);
871 AA_BUG(!cred_label(bprm->cred));
872 AA_BUG(!ctx);
873
874 label = aa_get_newest_label(cred_label(bprm->cred));
875
876 /*
877 * Detect no new privs being set, and store the label it
878 * occurred under. Ideally this would happen when nnp
879 * is set but there isn't a good way to do that yet.
880 *
881 * Testing for unconfined must be done before the subset test
882 */
883 if ((bprm->unsafe & LSM_UNSAFE_NO_NEW_PRIVS) && !unconfined(label) &&
884 !ctx->nnp)
885 ctx->nnp = aa_get_label(label);
886
887 /* buffer freed below, name is pointer into buffer */
888 buffer = aa_get_buffer(false);
889 if (!buffer) {
890 error = -ENOMEM;
891 goto done;
892 }
893
894 /* Test for onexec first as onexec override other x transitions. */
895 if (ctx->onexec)
896 new = handle_onexec(label, ctx->onexec, ctx->token,
897 bprm, buffer, &cond, &unsafe);
898 else
899 new = fn_label_build(label, profile, GFP_KERNEL,
900 profile_transition(profile, bprm, buffer,
901 &cond, &unsafe));
902
903 AA_BUG(!new);
904 if (IS_ERR(new)) {
905 error = PTR_ERR(new);
906 goto done;
907 } else if (!new) {
908 error = -ENOMEM;
909 goto done;
910 }
911
912 /* Policy has specified a domain transitions. If no_new_privs and
913 * confined ensure the transition is to confinement that is subset
914 * of the confinement when the task entered no new privs.
915 *
916 * NOTE: Domain transitions from unconfined and to stacked
917 * subsets are allowed even when no_new_privs is set because this
918 * aways results in a further reduction of permissions.
919 */
920 if ((bprm->unsafe & LSM_UNSAFE_NO_NEW_PRIVS) &&
921 !unconfined(label) &&
922 !aa_label_is_unconfined_subset(new, ctx->nnp)) {
923 error = -EPERM;
924 info = "no new privs";
925 goto audit;
926 }
927
928 if (bprm->unsafe & LSM_UNSAFE_SHARE) {
929 /* FIXME: currently don't mediate shared state */
930 ;
931 }
932
933 if (bprm->unsafe & (LSM_UNSAFE_PTRACE)) {
934 /* TODO: test needs to be profile of label to new */
935 error = may_change_ptraced_domain(new, &info);
936 if (error)
937 goto audit;
938 }
939
940 if (unsafe) {
941 if (DEBUG_ON) {
942 dbg_printk("scrubbing environment variables for %s "
943 "label=", bprm->filename);
944 aa_label_printk(new, GFP_KERNEL);
945 dbg_printk("\n");
946 }
947 bprm->secureexec = 1;
948 }
949
950 if (label->proxy != new->proxy) {
951 /* when transitioning clear unsafe personality bits */
952 if (DEBUG_ON) {
953 dbg_printk("apparmor: clearing unsafe personality "
954 "bits. %s label=", bprm->filename);
955 aa_label_printk(new, GFP_KERNEL);
956 dbg_printk("\n");
957 }
958 bprm->per_clear |= PER_CLEAR_ON_SETID;
959 }
960 aa_put_label(cred_label(bprm->cred));
961 /* transfer reference, released when cred is freed */
962 set_cred_label(bprm->cred, new);
963
964done:
965 aa_put_label(label);
966 aa_put_buffer(buffer);
967
968 return error;
969
970audit:
971 error = fn_for_each(label, profile,
972 aa_audit_file(profile, &nullperms, OP_EXEC, MAY_EXEC,
973 bprm->filename, NULL, new,
974 i_uid, info, error));
975 aa_put_label(new);
976 goto done;
977}
978
979/*
980 * Functions for self directed profile change
981 */
982
983
984/* helper fn for change_hat
985 *
986 * Returns: label for hat transition OR ERR_PTR. Does NOT return NULL
987 */
988static struct aa_label *build_change_hat(struct aa_profile *profile,
989 const char *name, bool sibling)
990{
991 struct aa_profile *root, *hat = NULL;
992 const char *info = NULL;
993 int error = 0;
994
995 if (sibling && PROFILE_IS_HAT(profile)) {
996 root = aa_get_profile_rcu(&profile->parent);
997 } else if (!sibling && !PROFILE_IS_HAT(profile)) {
998 root = aa_get_profile(profile);
999 } else {
1000 info = "conflicting target types";
1001 error = -EPERM;
1002 goto audit;
1003 }
1004
1005 hat = aa_find_child(root, name);
1006 if (!hat) {
1007 error = -ENOENT;
1008 if (COMPLAIN_MODE(profile)) {
1009 hat = aa_new_null_profile(profile, true, name,
1010 GFP_KERNEL);
1011 if (!hat) {
1012 info = "failed null profile create";
1013 error = -ENOMEM;
1014 }
1015 }
1016 }
1017 aa_put_profile(root);
1018
1019audit:
1020 aa_audit_file(profile, &nullperms, OP_CHANGE_HAT, AA_MAY_CHANGEHAT,
1021 name, hat ? hat->base.hname : NULL,
1022 hat ? &hat->label : NULL, GLOBAL_ROOT_UID, info,
1023 error);
1024 if (!hat || (error && error != -ENOENT))
1025 return ERR_PTR(error);
1026 /* if hat && error - complain mode, already audited and we adjust for
1027 * complain mode allow by returning hat->label
1028 */
1029 return &hat->label;
1030}
1031
1032/* helper fn for changing into a hat
1033 *
1034 * Returns: label for hat transition or ERR_PTR. Does not return NULL
1035 */
1036static struct aa_label *change_hat(struct aa_label *label, const char *hats[],
1037 int count, int flags)
1038{
1039 struct aa_profile *profile, *root, *hat = NULL;
1040 struct aa_label *new;
1041 struct label_it it;
1042 bool sibling = false;
1043 const char *name, *info = NULL;
1044 int i, error;
1045
1046 AA_BUG(!label);
1047 AA_BUG(!hats);
1048 AA_BUG(count < 1);
1049
1050 if (PROFILE_IS_HAT(labels_profile(label)))
1051 sibling = true;
1052
1053 /*find first matching hat */
1054 for (i = 0; i < count && !hat; i++) {
1055 name = hats[i];
1056 label_for_each_in_ns(it, labels_ns(label), label, profile) {
1057 if (sibling && PROFILE_IS_HAT(profile)) {
1058 root = aa_get_profile_rcu(&profile->parent);
1059 } else if (!sibling && !PROFILE_IS_HAT(profile)) {
1060 root = aa_get_profile(profile);
1061 } else { /* conflicting change type */
1062 info = "conflicting targets types";
1063 error = -EPERM;
1064 goto fail;
1065 }
1066 hat = aa_find_child(root, name);
1067 aa_put_profile(root);
1068 if (!hat) {
1069 if (!COMPLAIN_MODE(profile))
1070 goto outer_continue;
1071 /* complain mode succeed as if hat */
1072 } else if (!PROFILE_IS_HAT(hat)) {
1073 info = "target not hat";
1074 error = -EPERM;
1075 aa_put_profile(hat);
1076 goto fail;
1077 }
1078 aa_put_profile(hat);
1079 }
1080 /* found a hat for all profiles in ns */
1081 goto build;
1082outer_continue:
1083 ;
1084 }
1085 /* no hats that match, find appropriate error
1086 *
1087 * In complain mode audit of the failure is based off of the first
1088 * hat supplied. This is done due how userspace interacts with
1089 * change_hat.
1090 */
1091 name = NULL;
1092 label_for_each_in_ns(it, labels_ns(label), label, profile) {
1093 if (!list_empty(&profile->base.profiles)) {
1094 info = "hat not found";
1095 error = -ENOENT;
1096 goto fail;
1097 }
1098 }
1099 info = "no hats defined";
1100 error = -ECHILD;
1101
1102fail:
1103 label_for_each_in_ns(it, labels_ns(label), label, profile) {
1104 /*
1105 * no target as it has failed to be found or built
1106 *
1107 * change_hat uses probing and should not log failures
1108 * related to missing hats
1109 */
1110 /* TODO: get rid of GLOBAL_ROOT_UID */
1111 if (count > 1 || COMPLAIN_MODE(profile)) {
1112 aa_audit_file(profile, &nullperms, OP_CHANGE_HAT,
1113 AA_MAY_CHANGEHAT, name, NULL, NULL,
1114 GLOBAL_ROOT_UID, info, error);
1115 }
1116 }
1117 return ERR_PTR(error);
1118
1119build:
1120 new = fn_label_build_in_ns(label, profile, GFP_KERNEL,
1121 build_change_hat(profile, name, sibling),
1122 aa_get_label(&profile->label));
1123 if (!new) {
1124 info = "label build failed";
1125 error = -ENOMEM;
1126 goto fail;
1127 } /* else if (IS_ERR) build_change_hat has logged error so return new */
1128
1129 return new;
1130}
1131
1132/**
1133 * aa_change_hat - change hat to/from subprofile
1134 * @hats: vector of hat names to try changing into (MAYBE NULL if @count == 0)
1135 * @count: number of hat names in @hats
1136 * @token: magic value to validate the hat change
1137 * @flags: flags affecting behavior of the change
1138 *
1139 * Returns %0 on success, error otherwise.
1140 *
1141 * Change to the first profile specified in @hats that exists, and store
1142 * the @hat_magic in the current task context. If the count == 0 and the
1143 * @token matches that stored in the current task context, return to the
1144 * top level profile.
1145 *
1146 * change_hat only applies to profiles in the current ns, and each profile
1147 * in the ns must make the same transition otherwise change_hat will fail.
1148 */
1149int aa_change_hat(const char *hats[], int count, u64 token, int flags)
1150{
1151 const struct cred *cred;
1152 struct aa_task_ctx *ctx = task_ctx(current);
1153 struct aa_label *label, *previous, *new = NULL, *target = NULL;
1154 struct aa_profile *profile;
1155 struct aa_perms perms = {};
1156 const char *info = NULL;
1157 int error = 0;
1158
1159 /* released below */
1160 cred = get_current_cred();
1161 label = aa_get_newest_cred_label(cred);
1162 previous = aa_get_newest_label(ctx->previous);
1163
1164 /*
1165 * Detect no new privs being set, and store the label it
1166 * occurred under. Ideally this would happen when nnp
1167 * is set but there isn't a good way to do that yet.
1168 *
1169 * Testing for unconfined must be done before the subset test
1170 */
1171 if (task_no_new_privs(current) && !unconfined(label) && !ctx->nnp)
1172 ctx->nnp = aa_get_label(label);
1173
1174 if (unconfined(label)) {
1175 info = "unconfined can not change_hat";
1176 error = -EPERM;
1177 goto fail;
1178 }
1179
1180 if (count) {
1181 new = change_hat(label, hats, count, flags);
1182 AA_BUG(!new);
1183 if (IS_ERR(new)) {
1184 error = PTR_ERR(new);
1185 new = NULL;
1186 /* already audited */
1187 goto out;
1188 }
1189
1190 error = may_change_ptraced_domain(new, &info);
1191 if (error)
1192 goto fail;
1193
1194 /*
1195 * no new privs prevents domain transitions that would
1196 * reduce restrictions.
1197 */
1198 if (task_no_new_privs(current) && !unconfined(label) &&
1199 !aa_label_is_unconfined_subset(new, ctx->nnp)) {
1200 /* not an apparmor denial per se, so don't log it */
1201 AA_DEBUG("no_new_privs - change_hat denied");
1202 error = -EPERM;
1203 goto out;
1204 }
1205
1206 if (flags & AA_CHANGE_TEST)
1207 goto out;
1208
1209 target = new;
1210 error = aa_set_current_hat(new, token);
1211 if (error == -EACCES)
1212 /* kill task in case of brute force attacks */
1213 goto kill;
1214 } else if (previous && !(flags & AA_CHANGE_TEST)) {
1215 /*
1216 * no new privs prevents domain transitions that would
1217 * reduce restrictions.
1218 */
1219 if (task_no_new_privs(current) && !unconfined(label) &&
1220 !aa_label_is_unconfined_subset(previous, ctx->nnp)) {
1221 /* not an apparmor denial per se, so don't log it */
1222 AA_DEBUG("no_new_privs - change_hat denied");
1223 error = -EPERM;
1224 goto out;
1225 }
1226
1227 /* Return to saved label. Kill task if restore fails
1228 * to avoid brute force attacks
1229 */
1230 target = previous;
1231 error = aa_restore_previous_label(token);
1232 if (error) {
1233 if (error == -EACCES)
1234 goto kill;
1235 goto fail;
1236 }
1237 } /* else ignore @flags && restores when there is no saved profile */
1238
1239out:
1240 aa_put_label(new);
1241 aa_put_label(previous);
1242 aa_put_label(label);
1243 put_cred(cred);
1244
1245 return error;
1246
1247kill:
1248 info = "failed token match";
1249 perms.kill = AA_MAY_CHANGEHAT;
1250
1251fail:
1252 fn_for_each_in_ns(label, profile,
1253 aa_audit_file(profile, &perms, OP_CHANGE_HAT,
1254 AA_MAY_CHANGEHAT, NULL, NULL, target,
1255 GLOBAL_ROOT_UID, info, error));
1256
1257 goto out;
1258}
1259
1260
1261static int change_profile_perms_wrapper(const char *op, const char *name,
1262 struct aa_profile *profile,
1263 struct aa_label *target, bool stack,
1264 u32 request, struct aa_perms *perms)
1265{
1266 const char *info = NULL;
1267 int error = 0;
1268
1269 if (!error)
1270 error = change_profile_perms(profile, target, stack, request,
1271 profile->file.start, perms);
1272 if (error)
1273 error = aa_audit_file(profile, perms, op, request, name,
1274 NULL, target, GLOBAL_ROOT_UID, info,
1275 error);
1276
1277 return error;
1278}
1279
1280/**
1281 * aa_change_profile - perform a one-way profile transition
1282 * @fqname: name of profile may include namespace (NOT NULL)
1283 * @onexec: whether this transition is to take place immediately or at exec
1284 * @flags: flags affecting change behavior
1285 *
1286 * Change to new profile @name. Unlike with hats, there is no way
1287 * to change back. If @name isn't specified the current profile name is
1288 * used.
1289 * If @onexec then the transition is delayed until
1290 * the next exec.
1291 *
1292 * Returns %0 on success, error otherwise.
1293 */
1294int aa_change_profile(const char *fqname, int flags)
1295{
1296 struct aa_label *label, *new = NULL, *target = NULL;
1297 struct aa_profile *profile;
1298 struct aa_perms perms = {};
1299 const char *info = NULL;
1300 const char *auditname = fqname; /* retain leading & if stack */
1301 bool stack = flags & AA_CHANGE_STACK;
1302 struct aa_task_ctx *ctx = task_ctx(current);
1303 int error = 0;
1304 char *op;
1305 u32 request;
1306
1307 label = aa_get_current_label();
1308
1309 /*
1310 * Detect no new privs being set, and store the label it
1311 * occurred under. Ideally this would happen when nnp
1312 * is set but there isn't a good way to do that yet.
1313 *
1314 * Testing for unconfined must be done before the subset test
1315 */
1316 if (task_no_new_privs(current) && !unconfined(label) && !ctx->nnp)
1317 ctx->nnp = aa_get_label(label);
1318
1319 if (!fqname || !*fqname) {
1320 aa_put_label(label);
1321 AA_DEBUG("no profile name");
1322 return -EINVAL;
1323 }
1324
1325 if (flags & AA_CHANGE_ONEXEC) {
1326 request = AA_MAY_ONEXEC;
1327 if (stack)
1328 op = OP_STACK_ONEXEC;
1329 else
1330 op = OP_CHANGE_ONEXEC;
1331 } else {
1332 request = AA_MAY_CHANGE_PROFILE;
1333 if (stack)
1334 op = OP_STACK;
1335 else
1336 op = OP_CHANGE_PROFILE;
1337 }
1338
1339 if (*fqname == '&') {
1340 stack = true;
1341 /* don't have label_parse() do stacking */
1342 fqname++;
1343 }
1344 target = aa_label_parse(label, fqname, GFP_KERNEL, true, false);
1345 if (IS_ERR(target)) {
1346 struct aa_profile *tprofile;
1347
1348 info = "label not found";
1349 error = PTR_ERR(target);
1350 target = NULL;
1351 /*
1352 * TODO: fixme using labels_profile is not right - do profile
1353 * per complain profile
1354 */
1355 if ((flags & AA_CHANGE_TEST) ||
1356 !COMPLAIN_MODE(labels_profile(label)))
1357 goto audit;
1358 /* released below */
1359 tprofile = aa_new_null_profile(labels_profile(label), false,
1360 fqname, GFP_KERNEL);
1361 if (!tprofile) {
1362 info = "failed null profile create";
1363 error = -ENOMEM;
1364 goto audit;
1365 }
1366 target = &tprofile->label;
1367 goto check;
1368 }
1369
1370 /*
1371 * self directed transitions only apply to current policy ns
1372 * TODO: currently requiring perms for stacking and straight change
1373 * stacking doesn't strictly need this. Determine how much
1374 * we want to loosen this restriction for stacking
1375 *
1376 * if (!stack) {
1377 */
1378 error = fn_for_each_in_ns(label, profile,
1379 change_profile_perms_wrapper(op, auditname,
1380 profile, target, stack,
1381 request, &perms));
1382 if (error)
1383 /* auditing done in change_profile_perms_wrapper */
1384 goto out;
1385
1386 /* } */
1387
1388check:
1389 /* check if tracing task is allowed to trace target domain */
1390 error = may_change_ptraced_domain(target, &info);
1391 if (error && !fn_for_each_in_ns(label, profile,
1392 COMPLAIN_MODE(profile)))
1393 goto audit;
1394
1395 /* TODO: add permission check to allow this
1396 * if ((flags & AA_CHANGE_ONEXEC) && !current_is_single_threaded()) {
1397 * info = "not a single threaded task";
1398 * error = -EACCES;
1399 * goto audit;
1400 * }
1401 */
1402 if (flags & AA_CHANGE_TEST)
1403 goto out;
1404
1405 /* stacking is always a subset, so only check the nonstack case */
1406 if (!stack) {
1407 new = fn_label_build_in_ns(label, profile, GFP_KERNEL,
1408 aa_get_label(target),
1409 aa_get_label(&profile->label));
1410 /*
1411 * no new privs prevents domain transitions that would
1412 * reduce restrictions.
1413 */
1414 if (task_no_new_privs(current) && !unconfined(label) &&
1415 !aa_label_is_unconfined_subset(new, ctx->nnp)) {
1416 /* not an apparmor denial per se, so don't log it */
1417 AA_DEBUG("no_new_privs - change_hat denied");
1418 error = -EPERM;
1419 goto out;
1420 }
1421 }
1422
1423 if (!(flags & AA_CHANGE_ONEXEC)) {
1424 /* only transition profiles in the current ns */
1425 if (stack)
1426 new = aa_label_merge(label, target, GFP_KERNEL);
1427 if (IS_ERR_OR_NULL(new)) {
1428 info = "failed to build target label";
1429 if (!new)
1430 error = -ENOMEM;
1431 else
1432 error = PTR_ERR(new);
1433 new = NULL;
1434 perms.allow = 0;
1435 goto audit;
1436 }
1437 error = aa_replace_current_label(new);
1438 } else {
1439 if (new) {
1440 aa_put_label(new);
1441 new = NULL;
1442 }
1443
1444 /* full transition will be built in exec path */
1445 error = aa_set_current_onexec(target, stack);
1446 }
1447
1448audit:
1449 error = fn_for_each_in_ns(label, profile,
1450 aa_audit_file(profile, &perms, op, request, auditname,
1451 NULL, new ? new : target,
1452 GLOBAL_ROOT_UID, info, error));
1453
1454out:
1455 aa_put_label(new);
1456 aa_put_label(target);
1457 aa_put_label(label);
1458
1459 return error;
1460}