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1/*
2 * AppArmor security module
3 *
4 * This file contains AppArmor mediation of files
5 *
6 * Copyright (C) 1998-2008 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/tty.h>
16#include <linux/fdtable.h>
17#include <linux/file.h>
18
19#include "include/apparmor.h"
20#include "include/audit.h"
21#include "include/cred.h"
22#include "include/file.h"
23#include "include/match.h"
24#include "include/net.h"
25#include "include/path.h"
26#include "include/policy.h"
27#include "include/label.h"
28
29static u32 map_mask_to_chr_mask(u32 mask)
30{
31 u32 m = mask & PERMS_CHRS_MASK;
32
33 if (mask & AA_MAY_GETATTR)
34 m |= MAY_READ;
35 if (mask & (AA_MAY_SETATTR | AA_MAY_CHMOD | AA_MAY_CHOWN))
36 m |= MAY_WRITE;
37
38 return m;
39}
40
41/**
42 * audit_file_mask - convert mask to permission string
43 * @buffer: buffer to write string to (NOT NULL)
44 * @mask: permission mask to convert
45 */
46static void audit_file_mask(struct audit_buffer *ab, u32 mask)
47{
48 char str[10];
49
50 aa_perm_mask_to_str(str, aa_file_perm_chrs, map_mask_to_chr_mask(mask));
51 audit_log_string(ab, str);
52}
53
54/**
55 * file_audit_cb - call back for file specific audit fields
56 * @ab: audit_buffer (NOT NULL)
57 * @va: audit struct to audit values of (NOT NULL)
58 */
59static void file_audit_cb(struct audit_buffer *ab, void *va)
60{
61 struct common_audit_data *sa = va;
62 kuid_t fsuid = current_fsuid();
63
64 if (aad(sa)->request & AA_AUDIT_FILE_MASK) {
65 audit_log_format(ab, " requested_mask=");
66 audit_file_mask(ab, aad(sa)->request);
67 }
68 if (aad(sa)->denied & AA_AUDIT_FILE_MASK) {
69 audit_log_format(ab, " denied_mask=");
70 audit_file_mask(ab, aad(sa)->denied);
71 }
72 if (aad(sa)->request & AA_AUDIT_FILE_MASK) {
73 audit_log_format(ab, " fsuid=%d",
74 from_kuid(&init_user_ns, fsuid));
75 audit_log_format(ab, " ouid=%d",
76 from_kuid(&init_user_ns, aad(sa)->fs.ouid));
77 }
78
79 if (aad(sa)->peer) {
80 audit_log_format(ab, " target=");
81 aa_label_xaudit(ab, labels_ns(aad(sa)->label), aad(sa)->peer,
82 FLAG_VIEW_SUBNS, GFP_ATOMIC);
83 } else if (aad(sa)->fs.target) {
84 audit_log_format(ab, " target=");
85 audit_log_untrustedstring(ab, aad(sa)->fs.target);
86 }
87}
88
89/**
90 * aa_audit_file - handle the auditing of file operations
91 * @profile: the profile being enforced (NOT NULL)
92 * @perms: the permissions computed for the request (NOT NULL)
93 * @op: operation being mediated
94 * @request: permissions requested
95 * @name: name of object being mediated (MAYBE NULL)
96 * @target: name of target (MAYBE NULL)
97 * @tlabel: target label (MAY BE NULL)
98 * @ouid: object uid
99 * @info: extra information message (MAYBE NULL)
100 * @error: 0 if operation allowed else failure error code
101 *
102 * Returns: %0 or error on failure
103 */
104int aa_audit_file(struct aa_profile *profile, struct aa_perms *perms,
105 const char *op, u32 request, const char *name,
106 const char *target, struct aa_label *tlabel,
107 kuid_t ouid, const char *info, int error)
108{
109 int type = AUDIT_APPARMOR_AUTO;
110 DEFINE_AUDIT_DATA(sa, LSM_AUDIT_DATA_TASK, op);
111
112 sa.u.tsk = NULL;
113 aad(&sa)->request = request;
114 aad(&sa)->name = name;
115 aad(&sa)->fs.target = target;
116 aad(&sa)->peer = tlabel;
117 aad(&sa)->fs.ouid = ouid;
118 aad(&sa)->info = info;
119 aad(&sa)->error = error;
120 sa.u.tsk = NULL;
121
122 if (likely(!aad(&sa)->error)) {
123 u32 mask = perms->audit;
124
125 if (unlikely(AUDIT_MODE(profile) == AUDIT_ALL))
126 mask = 0xffff;
127
128 /* mask off perms that are not being force audited */
129 aad(&sa)->request &= mask;
130
131 if (likely(!aad(&sa)->request))
132 return 0;
133 type = AUDIT_APPARMOR_AUDIT;
134 } else {
135 /* only report permissions that were denied */
136 aad(&sa)->request = aad(&sa)->request & ~perms->allow;
137 AA_BUG(!aad(&sa)->request);
138
139 if (aad(&sa)->request & perms->kill)
140 type = AUDIT_APPARMOR_KILL;
141
142 /* quiet known rejects, assumes quiet and kill do not overlap */
143 if ((aad(&sa)->request & perms->quiet) &&
144 AUDIT_MODE(profile) != AUDIT_NOQUIET &&
145 AUDIT_MODE(profile) != AUDIT_ALL)
146 aad(&sa)->request &= ~perms->quiet;
147
148 if (!aad(&sa)->request)
149 return aad(&sa)->error;
150 }
151
152 aad(&sa)->denied = aad(&sa)->request & ~perms->allow;
153 return aa_audit(type, profile, &sa, file_audit_cb);
154}
155
156/**
157 * is_deleted - test if a file has been completely unlinked
158 * @dentry: dentry of file to test for deletion (NOT NULL)
159 *
160 * Returns: %1 if deleted else %0
161 */
162static inline bool is_deleted(struct dentry *dentry)
163{
164 if (d_unlinked(dentry) && d_backing_inode(dentry)->i_nlink == 0)
165 return 1;
166 return 0;
167}
168
169static int path_name(const char *op, struct aa_label *label,
170 const struct path *path, int flags, char *buffer,
171 const char **name, struct path_cond *cond, u32 request)
172{
173 struct aa_profile *profile;
174 const char *info = NULL;
175 int error;
176
177 error = aa_path_name(path, flags, buffer, name, &info,
178 labels_profile(label)->disconnected);
179 if (error) {
180 fn_for_each_confined(label, profile,
181 aa_audit_file(profile, &nullperms, op, request, *name,
182 NULL, NULL, cond->uid, info, error));
183 return error;
184 }
185
186 return 0;
187}
188
189/**
190 * map_old_perms - map old file perms layout to the new layout
191 * @old: permission set in old mapping
192 *
193 * Returns: new permission mapping
194 */
195static u32 map_old_perms(u32 old)
196{
197 u32 new = old & 0xf;
198 if (old & MAY_READ)
199 new |= AA_MAY_GETATTR | AA_MAY_OPEN;
200 if (old & MAY_WRITE)
201 new |= AA_MAY_SETATTR | AA_MAY_CREATE | AA_MAY_DELETE |
202 AA_MAY_CHMOD | AA_MAY_CHOWN | AA_MAY_OPEN;
203 if (old & 0x10)
204 new |= AA_MAY_LINK;
205 /* the old mapping lock and link_subset flags where overlaid
206 * and use was determined by part of a pair that they were in
207 */
208 if (old & 0x20)
209 new |= AA_MAY_LOCK | AA_LINK_SUBSET;
210 if (old & 0x40) /* AA_EXEC_MMAP */
211 new |= AA_EXEC_MMAP;
212
213 return new;
214}
215
216/**
217 * aa_compute_fperms - convert dfa compressed perms to internal perms
218 * @dfa: dfa to compute perms for (NOT NULL)
219 * @state: state in dfa
220 * @cond: conditions to consider (NOT NULL)
221 *
222 * TODO: convert from dfa + state to permission entry, do computation conversion
223 * at load time.
224 *
225 * Returns: computed permission set
226 */
227struct aa_perms aa_compute_fperms(struct aa_dfa *dfa, unsigned int state,
228 struct path_cond *cond)
229{
230 /* FIXME: change over to new dfa format
231 * currently file perms are encoded in the dfa, new format
232 * splits the permissions from the dfa. This mapping can be
233 * done at profile load
234 */
235 struct aa_perms perms = { };
236
237 if (uid_eq(current_fsuid(), cond->uid)) {
238 perms.allow = map_old_perms(dfa_user_allow(dfa, state));
239 perms.audit = map_old_perms(dfa_user_audit(dfa, state));
240 perms.quiet = map_old_perms(dfa_user_quiet(dfa, state));
241 perms.xindex = dfa_user_xindex(dfa, state);
242 } else {
243 perms.allow = map_old_perms(dfa_other_allow(dfa, state));
244 perms.audit = map_old_perms(dfa_other_audit(dfa, state));
245 perms.quiet = map_old_perms(dfa_other_quiet(dfa, state));
246 perms.xindex = dfa_other_xindex(dfa, state);
247 }
248 perms.allow |= AA_MAY_GETATTR;
249
250 /* change_profile wasn't determined by ownership in old mapping */
251 if (ACCEPT_TABLE(dfa)[state] & 0x80000000)
252 perms.allow |= AA_MAY_CHANGE_PROFILE;
253 if (ACCEPT_TABLE(dfa)[state] & 0x40000000)
254 perms.allow |= AA_MAY_ONEXEC;
255
256 return perms;
257}
258
259/**
260 * aa_str_perms - find permission that match @name
261 * @dfa: to match against (MAYBE NULL)
262 * @state: state to start matching in
263 * @name: string to match against dfa (NOT NULL)
264 * @cond: conditions to consider for permission set computation (NOT NULL)
265 * @perms: Returns - the permissions found when matching @name
266 *
267 * Returns: the final state in @dfa when beginning @start and walking @name
268 */
269unsigned int aa_str_perms(struct aa_dfa *dfa, unsigned int start,
270 const char *name, struct path_cond *cond,
271 struct aa_perms *perms)
272{
273 unsigned int state;
274 state = aa_dfa_match(dfa, start, name);
275 *perms = aa_compute_fperms(dfa, state, cond);
276
277 return state;
278}
279
280int __aa_path_perm(const char *op, struct aa_profile *profile, const char *name,
281 u32 request, struct path_cond *cond, int flags,
282 struct aa_perms *perms)
283{
284 int e = 0;
285
286 if (profile_unconfined(profile))
287 return 0;
288 aa_str_perms(profile->file.dfa, profile->file.start, name, cond, perms);
289 if (request & ~perms->allow)
290 e = -EACCES;
291 return aa_audit_file(profile, perms, op, request, name, NULL, NULL,
292 cond->uid, NULL, e);
293}
294
295
296static int profile_path_perm(const char *op, struct aa_profile *profile,
297 const struct path *path, char *buffer, u32 request,
298 struct path_cond *cond, int flags,
299 struct aa_perms *perms)
300{
301 const char *name;
302 int error;
303
304 if (profile_unconfined(profile))
305 return 0;
306
307 error = path_name(op, &profile->label, path,
308 flags | profile->path_flags, buffer, &name, cond,
309 request);
310 if (error)
311 return error;
312 return __aa_path_perm(op, profile, name, request, cond, flags,
313 perms);
314}
315
316/**
317 * aa_path_perm - do permissions check & audit for @path
318 * @op: operation being checked
319 * @label: profile being enforced (NOT NULL)
320 * @path: path to check permissions of (NOT NULL)
321 * @flags: any additional path flags beyond what the profile specifies
322 * @request: requested permissions
323 * @cond: conditional info for this request (NOT NULL)
324 *
325 * Returns: %0 else error if access denied or other error
326 */
327int aa_path_perm(const char *op, struct aa_label *label,
328 const struct path *path, int flags, u32 request,
329 struct path_cond *cond)
330{
331 struct aa_perms perms = {};
332 struct aa_profile *profile;
333 char *buffer = NULL;
334 int error;
335
336 flags |= PATH_DELEGATE_DELETED | (S_ISDIR(cond->mode) ? PATH_IS_DIR :
337 0);
338 get_buffers(buffer);
339 error = fn_for_each_confined(label, profile,
340 profile_path_perm(op, profile, path, buffer, request,
341 cond, flags, &perms));
342
343 put_buffers(buffer);
344
345 return error;
346}
347
348/**
349 * xindex_is_subset - helper for aa_path_link
350 * @link: link permission set
351 * @target: target permission set
352 *
353 * test target x permissions are equal OR a subset of link x permissions
354 * this is done as part of the subset test, where a hardlink must have
355 * a subset of permissions that the target has.
356 *
357 * Returns: %1 if subset else %0
358 */
359static inline bool xindex_is_subset(u32 link, u32 target)
360{
361 if (((link & ~AA_X_UNSAFE) != (target & ~AA_X_UNSAFE)) ||
362 ((link & AA_X_UNSAFE) && !(target & AA_X_UNSAFE)))
363 return 0;
364
365 return 1;
366}
367
368static int profile_path_link(struct aa_profile *profile,
369 const struct path *link, char *buffer,
370 const struct path *target, char *buffer2,
371 struct path_cond *cond)
372{
373 const char *lname, *tname = NULL;
374 struct aa_perms lperms = {}, perms;
375 const char *info = NULL;
376 u32 request = AA_MAY_LINK;
377 unsigned int state;
378 int error;
379
380 error = path_name(OP_LINK, &profile->label, link, profile->path_flags,
381 buffer, &lname, cond, AA_MAY_LINK);
382 if (error)
383 goto audit;
384
385 /* buffer2 freed below, tname is pointer in buffer2 */
386 error = path_name(OP_LINK, &profile->label, target, profile->path_flags,
387 buffer2, &tname, cond, AA_MAY_LINK);
388 if (error)
389 goto audit;
390
391 error = -EACCES;
392 /* aa_str_perms - handles the case of the dfa being NULL */
393 state = aa_str_perms(profile->file.dfa, profile->file.start, lname,
394 cond, &lperms);
395
396 if (!(lperms.allow & AA_MAY_LINK))
397 goto audit;
398
399 /* test to see if target can be paired with link */
400 state = aa_dfa_null_transition(profile->file.dfa, state);
401 aa_str_perms(profile->file.dfa, state, tname, cond, &perms);
402
403 /* force audit/quiet masks for link are stored in the second entry
404 * in the link pair.
405 */
406 lperms.audit = perms.audit;
407 lperms.quiet = perms.quiet;
408 lperms.kill = perms.kill;
409
410 if (!(perms.allow & AA_MAY_LINK)) {
411 info = "target restricted";
412 lperms = perms;
413 goto audit;
414 }
415
416 /* done if link subset test is not required */
417 if (!(perms.allow & AA_LINK_SUBSET))
418 goto done_tests;
419
420 /* Do link perm subset test requiring allowed permission on link are
421 * a subset of the allowed permissions on target.
422 */
423 aa_str_perms(profile->file.dfa, profile->file.start, tname, cond,
424 &perms);
425
426 /* AA_MAY_LINK is not considered in the subset test */
427 request = lperms.allow & ~AA_MAY_LINK;
428 lperms.allow &= perms.allow | AA_MAY_LINK;
429
430 request |= AA_AUDIT_FILE_MASK & (lperms.allow & ~perms.allow);
431 if (request & ~lperms.allow) {
432 goto audit;
433 } else if ((lperms.allow & MAY_EXEC) &&
434 !xindex_is_subset(lperms.xindex, perms.xindex)) {
435 lperms.allow &= ~MAY_EXEC;
436 request |= MAY_EXEC;
437 info = "link not subset of target";
438 goto audit;
439 }
440
441done_tests:
442 error = 0;
443
444audit:
445 return aa_audit_file(profile, &lperms, OP_LINK, request, lname, tname,
446 NULL, cond->uid, info, error);
447}
448
449/**
450 * aa_path_link - Handle hard link permission check
451 * @label: the label being enforced (NOT NULL)
452 * @old_dentry: the target dentry (NOT NULL)
453 * @new_dir: directory the new link will be created in (NOT NULL)
454 * @new_dentry: the link being created (NOT NULL)
455 *
456 * Handle the permission test for a link & target pair. Permission
457 * is encoded as a pair where the link permission is determined
458 * first, and if allowed, the target is tested. The target test
459 * is done from the point of the link match (not start of DFA)
460 * making the target permission dependent on the link permission match.
461 *
462 * The subset test if required forces that permissions granted
463 * on link are a subset of the permission granted to target.
464 *
465 * Returns: %0 if allowed else error
466 */
467int aa_path_link(struct aa_label *label, struct dentry *old_dentry,
468 const struct path *new_dir, struct dentry *new_dentry)
469{
470 struct path link = { .mnt = new_dir->mnt, .dentry = new_dentry };
471 struct path target = { .mnt = new_dir->mnt, .dentry = old_dentry };
472 struct path_cond cond = {
473 d_backing_inode(old_dentry)->i_uid,
474 d_backing_inode(old_dentry)->i_mode
475 };
476 char *buffer = NULL, *buffer2 = NULL;
477 struct aa_profile *profile;
478 int error;
479
480 /* buffer freed below, lname is pointer in buffer */
481 get_buffers(buffer, buffer2);
482 error = fn_for_each_confined(label, profile,
483 profile_path_link(profile, &link, buffer, &target,
484 buffer2, &cond));
485 put_buffers(buffer, buffer2);
486
487 return error;
488}
489
490static void update_file_ctx(struct aa_file_ctx *fctx, struct aa_label *label,
491 u32 request)
492{
493 struct aa_label *l, *old;
494
495 /* update caching of label on file_ctx */
496 spin_lock(&fctx->lock);
497 old = rcu_dereference_protected(fctx->label,
498 spin_is_locked(&fctx->lock));
499 l = aa_label_merge(old, label, GFP_ATOMIC);
500 if (l) {
501 if (l != old) {
502 rcu_assign_pointer(fctx->label, l);
503 aa_put_label(old);
504 } else
505 aa_put_label(l);
506 fctx->allow |= request;
507 }
508 spin_unlock(&fctx->lock);
509}
510
511static int __file_path_perm(const char *op, struct aa_label *label,
512 struct aa_label *flabel, struct file *file,
513 u32 request, u32 denied)
514{
515 struct aa_profile *profile;
516 struct aa_perms perms = {};
517 struct path_cond cond = {
518 .uid = file_inode(file)->i_uid,
519 .mode = file_inode(file)->i_mode
520 };
521 char *buffer;
522 int flags, error;
523
524 /* revalidation due to label out of date. No revocation at this time */
525 if (!denied && aa_label_is_subset(flabel, label))
526 /* TODO: check for revocation on stale profiles */
527 return 0;
528
529 flags = PATH_DELEGATE_DELETED | (S_ISDIR(cond.mode) ? PATH_IS_DIR : 0);
530 get_buffers(buffer);
531
532 /* check every profile in task label not in current cache */
533 error = fn_for_each_not_in_set(flabel, label, profile,
534 profile_path_perm(op, profile, &file->f_path, buffer,
535 request, &cond, flags, &perms));
536 if (denied && !error) {
537 /*
538 * check every profile in file label that was not tested
539 * in the initial check above.
540 *
541 * TODO: cache full perms so this only happens because of
542 * conditionals
543 * TODO: don't audit here
544 */
545 if (label == flabel)
546 error = fn_for_each(label, profile,
547 profile_path_perm(op, profile, &file->f_path,
548 buffer, request, &cond, flags,
549 &perms));
550 else
551 error = fn_for_each_not_in_set(label, flabel, profile,
552 profile_path_perm(op, profile, &file->f_path,
553 buffer, request, &cond, flags,
554 &perms));
555 }
556 if (!error)
557 update_file_ctx(file_ctx(file), label, request);
558
559 put_buffers(buffer);
560
561 return error;
562}
563
564static int __file_sock_perm(const char *op, struct aa_label *label,
565 struct aa_label *flabel, struct file *file,
566 u32 request, u32 denied)
567{
568 struct socket *sock = (struct socket *) file->private_data;
569 int error;
570
571 AA_BUG(!sock);
572
573 /* revalidation due to label out of date. No revocation at this time */
574 if (!denied && aa_label_is_subset(flabel, label))
575 return 0;
576
577 /* TODO: improve to skip profiles cached in flabel */
578 error = aa_sock_file_perm(label, op, request, sock);
579 if (denied) {
580 /* TODO: improve to skip profiles checked above */
581 /* check every profile in file label to is cached */
582 last_error(error, aa_sock_file_perm(flabel, op, request, sock));
583 }
584 if (!error)
585 update_file_ctx(file_ctx(file), label, request);
586
587 return error;
588}
589
590/**
591 * aa_file_perm - do permission revalidation check & audit for @file
592 * @op: operation being checked
593 * @label: label being enforced (NOT NULL)
594 * @file: file to revalidate access permissions on (NOT NULL)
595 * @request: requested permissions
596 *
597 * Returns: %0 if access allowed else error
598 */
599int aa_file_perm(const char *op, struct aa_label *label, struct file *file,
600 u32 request)
601{
602 struct aa_file_ctx *fctx;
603 struct aa_label *flabel;
604 u32 denied;
605 int error = 0;
606
607 AA_BUG(!label);
608 AA_BUG(!file);
609
610 fctx = file_ctx(file);
611
612 rcu_read_lock();
613 flabel = rcu_dereference(fctx->label);
614 AA_BUG(!flabel);
615
616 /* revalidate access, if task is unconfined, or the cached cred
617 * doesn't match or if the request is for more permissions than
618 * was granted.
619 *
620 * Note: the test for !unconfined(flabel) is to handle file
621 * delegation from unconfined tasks
622 */
623 denied = request & ~fctx->allow;
624 if (unconfined(label) || unconfined(flabel) ||
625 (!denied && aa_label_is_subset(flabel, label)))
626 goto done;
627
628 /* TODO: label cross check */
629
630 if (file->f_path.mnt && path_mediated_fs(file->f_path.dentry))
631 error = __file_path_perm(op, label, flabel, file, request,
632 denied);
633
634 else if (S_ISSOCK(file_inode(file)->i_mode))
635 error = __file_sock_perm(op, label, flabel, file, request,
636 denied);
637done:
638 rcu_read_unlock();
639
640 return error;
641}
642
643static void revalidate_tty(struct aa_label *label)
644{
645 struct tty_struct *tty;
646 int drop_tty = 0;
647
648 tty = get_current_tty();
649 if (!tty)
650 return;
651
652 spin_lock(&tty->files_lock);
653 if (!list_empty(&tty->tty_files)) {
654 struct tty_file_private *file_priv;
655 struct file *file;
656 /* TODO: Revalidate access to controlling tty. */
657 file_priv = list_first_entry(&tty->tty_files,
658 struct tty_file_private, list);
659 file = file_priv->file;
660
661 if (aa_file_perm(OP_INHERIT, label, file, MAY_READ | MAY_WRITE))
662 drop_tty = 1;
663 }
664 spin_unlock(&tty->files_lock);
665 tty_kref_put(tty);
666
667 if (drop_tty)
668 no_tty();
669}
670
671static int match_file(const void *p, struct file *file, unsigned int fd)
672{
673 struct aa_label *label = (struct aa_label *)p;
674
675 if (aa_file_perm(OP_INHERIT, label, file, aa_map_file_to_perms(file)))
676 return fd + 1;
677 return 0;
678}
679
680
681/* based on selinux's flush_unauthorized_files */
682void aa_inherit_files(const struct cred *cred, struct files_struct *files)
683{
684 struct aa_label *label = aa_get_newest_cred_label(cred);
685 struct file *devnull = NULL;
686 unsigned int n;
687
688 revalidate_tty(label);
689
690 /* Revalidate access to inherited open files. */
691 n = iterate_fd(files, 0, match_file, label);
692 if (!n) /* none found? */
693 goto out;
694
695 devnull = dentry_open(&aa_null, O_RDWR, cred);
696 if (IS_ERR(devnull))
697 devnull = NULL;
698 /* replace all the matching ones with this */
699 do {
700 replace_fd(n - 1, devnull, 0);
701 } while ((n = iterate_fd(files, n, match_file, label)) != 0);
702 if (devnull)
703 fput(devnull);
704out:
705 aa_put_label(label);
706}
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * AppArmor security module
4 *
5 * This file contains AppArmor mediation of files
6 *
7 * Copyright (C) 1998-2008 Novell/SUSE
8 * Copyright 2009-2010 Canonical Ltd.
9 */
10
11#include <linux/tty.h>
12#include <linux/fdtable.h>
13#include <linux/file.h>
14
15#include "include/apparmor.h"
16#include "include/audit.h"
17#include "include/cred.h"
18#include "include/file.h"
19#include "include/match.h"
20#include "include/net.h"
21#include "include/path.h"
22#include "include/policy.h"
23#include "include/label.h"
24
25static u32 map_mask_to_chr_mask(u32 mask)
26{
27 u32 m = mask & PERMS_CHRS_MASK;
28
29 if (mask & AA_MAY_GETATTR)
30 m |= MAY_READ;
31 if (mask & (AA_MAY_SETATTR | AA_MAY_CHMOD | AA_MAY_CHOWN))
32 m |= MAY_WRITE;
33
34 return m;
35}
36
37/**
38 * file_audit_cb - call back for file specific audit fields
39 * @ab: audit_buffer (NOT NULL)
40 * @va: audit struct to audit values of (NOT NULL)
41 */
42static void file_audit_cb(struct audit_buffer *ab, void *va)
43{
44 struct common_audit_data *sa = va;
45 kuid_t fsuid = current_fsuid();
46 char str[10];
47
48 if (aad(sa)->request & AA_AUDIT_FILE_MASK) {
49 aa_perm_mask_to_str(str, sizeof(str), aa_file_perm_chrs,
50 map_mask_to_chr_mask(aad(sa)->request));
51 audit_log_format(ab, " requested_mask=\"%s\"", str);
52 }
53 if (aad(sa)->denied & AA_AUDIT_FILE_MASK) {
54 aa_perm_mask_to_str(str, sizeof(str), aa_file_perm_chrs,
55 map_mask_to_chr_mask(aad(sa)->denied));
56 audit_log_format(ab, " denied_mask=\"%s\"", str);
57 }
58 if (aad(sa)->request & AA_AUDIT_FILE_MASK) {
59 audit_log_format(ab, " fsuid=%d",
60 from_kuid(&init_user_ns, fsuid));
61 audit_log_format(ab, " ouid=%d",
62 from_kuid(&init_user_ns, aad(sa)->fs.ouid));
63 }
64
65 if (aad(sa)->peer) {
66 audit_log_format(ab, " target=");
67 aa_label_xaudit(ab, labels_ns(aad(sa)->label), aad(sa)->peer,
68 FLAG_VIEW_SUBNS, GFP_KERNEL);
69 } else if (aad(sa)->fs.target) {
70 audit_log_format(ab, " target=");
71 audit_log_untrustedstring(ab, aad(sa)->fs.target);
72 }
73}
74
75/**
76 * aa_audit_file - handle the auditing of file operations
77 * @profile: the profile being enforced (NOT NULL)
78 * @perms: the permissions computed for the request (NOT NULL)
79 * @op: operation being mediated
80 * @request: permissions requested
81 * @name: name of object being mediated (MAYBE NULL)
82 * @target: name of target (MAYBE NULL)
83 * @tlabel: target label (MAY BE NULL)
84 * @ouid: object uid
85 * @info: extra information message (MAYBE NULL)
86 * @error: 0 if operation allowed else failure error code
87 *
88 * Returns: %0 or error on failure
89 */
90int aa_audit_file(struct aa_profile *profile, struct aa_perms *perms,
91 const char *op, u32 request, const char *name,
92 const char *target, struct aa_label *tlabel,
93 kuid_t ouid, const char *info, int error)
94{
95 int type = AUDIT_APPARMOR_AUTO;
96 DEFINE_AUDIT_DATA(sa, LSM_AUDIT_DATA_TASK, op);
97
98 sa.u.tsk = NULL;
99 aad(&sa)->request = request;
100 aad(&sa)->name = name;
101 aad(&sa)->fs.target = target;
102 aad(&sa)->peer = tlabel;
103 aad(&sa)->fs.ouid = ouid;
104 aad(&sa)->info = info;
105 aad(&sa)->error = error;
106 sa.u.tsk = NULL;
107
108 if (likely(!aad(&sa)->error)) {
109 u32 mask = perms->audit;
110
111 if (unlikely(AUDIT_MODE(profile) == AUDIT_ALL))
112 mask = 0xffff;
113
114 /* mask off perms that are not being force audited */
115 aad(&sa)->request &= mask;
116
117 if (likely(!aad(&sa)->request))
118 return 0;
119 type = AUDIT_APPARMOR_AUDIT;
120 } else {
121 /* only report permissions that were denied */
122 aad(&sa)->request = aad(&sa)->request & ~perms->allow;
123 AA_BUG(!aad(&sa)->request);
124
125 if (aad(&sa)->request & perms->kill)
126 type = AUDIT_APPARMOR_KILL;
127
128 /* quiet known rejects, assumes quiet and kill do not overlap */
129 if ((aad(&sa)->request & perms->quiet) &&
130 AUDIT_MODE(profile) != AUDIT_NOQUIET &&
131 AUDIT_MODE(profile) != AUDIT_ALL)
132 aad(&sa)->request &= ~perms->quiet;
133
134 if (!aad(&sa)->request)
135 return aad(&sa)->error;
136 }
137
138 aad(&sa)->denied = aad(&sa)->request & ~perms->allow;
139 return aa_audit(type, profile, &sa, file_audit_cb);
140}
141
142/**
143 * is_deleted - test if a file has been completely unlinked
144 * @dentry: dentry of file to test for deletion (NOT NULL)
145 *
146 * Returns: true if deleted else false
147 */
148static inline bool is_deleted(struct dentry *dentry)
149{
150 if (d_unlinked(dentry) && d_backing_inode(dentry)->i_nlink == 0)
151 return true;
152 return false;
153}
154
155static int path_name(const char *op, struct aa_label *label,
156 const struct path *path, int flags, char *buffer,
157 const char **name, struct path_cond *cond, u32 request)
158{
159 struct aa_profile *profile;
160 const char *info = NULL;
161 int error;
162
163 error = aa_path_name(path, flags, buffer, name, &info,
164 labels_profile(label)->disconnected);
165 if (error) {
166 fn_for_each_confined(label, profile,
167 aa_audit_file(profile, &nullperms, op, request, *name,
168 NULL, NULL, cond->uid, info, error));
169 return error;
170 }
171
172 return 0;
173}
174
175/**
176 * map_old_perms - map old file perms layout to the new layout
177 * @old: permission set in old mapping
178 *
179 * Returns: new permission mapping
180 */
181static u32 map_old_perms(u32 old)
182{
183 u32 new = old & 0xf;
184 if (old & MAY_READ)
185 new |= AA_MAY_GETATTR | AA_MAY_OPEN;
186 if (old & MAY_WRITE)
187 new |= AA_MAY_SETATTR | AA_MAY_CREATE | AA_MAY_DELETE |
188 AA_MAY_CHMOD | AA_MAY_CHOWN | AA_MAY_OPEN;
189 if (old & 0x10)
190 new |= AA_MAY_LINK;
191 /* the old mapping lock and link_subset flags where overlaid
192 * and use was determined by part of a pair that they were in
193 */
194 if (old & 0x20)
195 new |= AA_MAY_LOCK | AA_LINK_SUBSET;
196 if (old & 0x40) /* AA_EXEC_MMAP */
197 new |= AA_EXEC_MMAP;
198
199 return new;
200}
201
202/**
203 * aa_compute_fperms - convert dfa compressed perms to internal perms
204 * @dfa: dfa to compute perms for (NOT NULL)
205 * @state: state in dfa
206 * @cond: conditions to consider (NOT NULL)
207 *
208 * TODO: convert from dfa + state to permission entry, do computation conversion
209 * at load time.
210 *
211 * Returns: computed permission set
212 */
213struct aa_perms aa_compute_fperms(struct aa_dfa *dfa, unsigned int state,
214 struct path_cond *cond)
215{
216 /* FIXME: change over to new dfa format
217 * currently file perms are encoded in the dfa, new format
218 * splits the permissions from the dfa. This mapping can be
219 * done at profile load
220 */
221 struct aa_perms perms = { };
222
223 if (uid_eq(current_fsuid(), cond->uid)) {
224 perms.allow = map_old_perms(dfa_user_allow(dfa, state));
225 perms.audit = map_old_perms(dfa_user_audit(dfa, state));
226 perms.quiet = map_old_perms(dfa_user_quiet(dfa, state));
227 perms.xindex = dfa_user_xindex(dfa, state);
228 } else {
229 perms.allow = map_old_perms(dfa_other_allow(dfa, state));
230 perms.audit = map_old_perms(dfa_other_audit(dfa, state));
231 perms.quiet = map_old_perms(dfa_other_quiet(dfa, state));
232 perms.xindex = dfa_other_xindex(dfa, state);
233 }
234 perms.allow |= AA_MAY_GETATTR;
235
236 /* change_profile wasn't determined by ownership in old mapping */
237 if (ACCEPT_TABLE(dfa)[state] & 0x80000000)
238 perms.allow |= AA_MAY_CHANGE_PROFILE;
239 if (ACCEPT_TABLE(dfa)[state] & 0x40000000)
240 perms.allow |= AA_MAY_ONEXEC;
241
242 return perms;
243}
244
245/**
246 * aa_str_perms - find permission that match @name
247 * @dfa: to match against (MAYBE NULL)
248 * @state: state to start matching in
249 * @name: string to match against dfa (NOT NULL)
250 * @cond: conditions to consider for permission set computation (NOT NULL)
251 * @perms: Returns - the permissions found when matching @name
252 *
253 * Returns: the final state in @dfa when beginning @start and walking @name
254 */
255unsigned int aa_str_perms(struct aa_dfa *dfa, unsigned int start,
256 const char *name, struct path_cond *cond,
257 struct aa_perms *perms)
258{
259 unsigned int state;
260 state = aa_dfa_match(dfa, start, name);
261 *perms = aa_compute_fperms(dfa, state, cond);
262
263 return state;
264}
265
266int __aa_path_perm(const char *op, struct aa_profile *profile, const char *name,
267 u32 request, struct path_cond *cond, int flags,
268 struct aa_perms *perms)
269{
270 int e = 0;
271
272 if (profile_unconfined(profile))
273 return 0;
274 aa_str_perms(profile->file.dfa, profile->file.start, name, cond, perms);
275 if (request & ~perms->allow)
276 e = -EACCES;
277 return aa_audit_file(profile, perms, op, request, name, NULL, NULL,
278 cond->uid, NULL, e);
279}
280
281
282static int profile_path_perm(const char *op, struct aa_profile *profile,
283 const struct path *path, char *buffer, u32 request,
284 struct path_cond *cond, int flags,
285 struct aa_perms *perms)
286{
287 const char *name;
288 int error;
289
290 if (profile_unconfined(profile))
291 return 0;
292
293 error = path_name(op, &profile->label, path,
294 flags | profile->path_flags, buffer, &name, cond,
295 request);
296 if (error)
297 return error;
298 return __aa_path_perm(op, profile, name, request, cond, flags,
299 perms);
300}
301
302/**
303 * aa_path_perm - do permissions check & audit for @path
304 * @op: operation being checked
305 * @label: profile being enforced (NOT NULL)
306 * @path: path to check permissions of (NOT NULL)
307 * @flags: any additional path flags beyond what the profile specifies
308 * @request: requested permissions
309 * @cond: conditional info for this request (NOT NULL)
310 *
311 * Returns: %0 else error if access denied or other error
312 */
313int aa_path_perm(const char *op, struct aa_label *label,
314 const struct path *path, int flags, u32 request,
315 struct path_cond *cond)
316{
317 struct aa_perms perms = {};
318 struct aa_profile *profile;
319 char *buffer = NULL;
320 int error;
321
322 flags |= PATH_DELEGATE_DELETED | (S_ISDIR(cond->mode) ? PATH_IS_DIR :
323 0);
324 buffer = aa_get_buffer(false);
325 if (!buffer)
326 return -ENOMEM;
327 error = fn_for_each_confined(label, profile,
328 profile_path_perm(op, profile, path, buffer, request,
329 cond, flags, &perms));
330
331 aa_put_buffer(buffer);
332
333 return error;
334}
335
336/**
337 * xindex_is_subset - helper for aa_path_link
338 * @link: link permission set
339 * @target: target permission set
340 *
341 * test target x permissions are equal OR a subset of link x permissions
342 * this is done as part of the subset test, where a hardlink must have
343 * a subset of permissions that the target has.
344 *
345 * Returns: true if subset else false
346 */
347static inline bool xindex_is_subset(u32 link, u32 target)
348{
349 if (((link & ~AA_X_UNSAFE) != (target & ~AA_X_UNSAFE)) ||
350 ((link & AA_X_UNSAFE) && !(target & AA_X_UNSAFE)))
351 return false;
352
353 return true;
354}
355
356static int profile_path_link(struct aa_profile *profile,
357 const struct path *link, char *buffer,
358 const struct path *target, char *buffer2,
359 struct path_cond *cond)
360{
361 const char *lname, *tname = NULL;
362 struct aa_perms lperms = {}, perms;
363 const char *info = NULL;
364 u32 request = AA_MAY_LINK;
365 unsigned int state;
366 int error;
367
368 error = path_name(OP_LINK, &profile->label, link, profile->path_flags,
369 buffer, &lname, cond, AA_MAY_LINK);
370 if (error)
371 goto audit;
372
373 /* buffer2 freed below, tname is pointer in buffer2 */
374 error = path_name(OP_LINK, &profile->label, target, profile->path_flags,
375 buffer2, &tname, cond, AA_MAY_LINK);
376 if (error)
377 goto audit;
378
379 error = -EACCES;
380 /* aa_str_perms - handles the case of the dfa being NULL */
381 state = aa_str_perms(profile->file.dfa, profile->file.start, lname,
382 cond, &lperms);
383
384 if (!(lperms.allow & AA_MAY_LINK))
385 goto audit;
386
387 /* test to see if target can be paired with link */
388 state = aa_dfa_null_transition(profile->file.dfa, state);
389 aa_str_perms(profile->file.dfa, state, tname, cond, &perms);
390
391 /* force audit/quiet masks for link are stored in the second entry
392 * in the link pair.
393 */
394 lperms.audit = perms.audit;
395 lperms.quiet = perms.quiet;
396 lperms.kill = perms.kill;
397
398 if (!(perms.allow & AA_MAY_LINK)) {
399 info = "target restricted";
400 lperms = perms;
401 goto audit;
402 }
403
404 /* done if link subset test is not required */
405 if (!(perms.allow & AA_LINK_SUBSET))
406 goto done_tests;
407
408 /* Do link perm subset test requiring allowed permission on link are
409 * a subset of the allowed permissions on target.
410 */
411 aa_str_perms(profile->file.dfa, profile->file.start, tname, cond,
412 &perms);
413
414 /* AA_MAY_LINK is not considered in the subset test */
415 request = lperms.allow & ~AA_MAY_LINK;
416 lperms.allow &= perms.allow | AA_MAY_LINK;
417
418 request |= AA_AUDIT_FILE_MASK & (lperms.allow & ~perms.allow);
419 if (request & ~lperms.allow) {
420 goto audit;
421 } else if ((lperms.allow & MAY_EXEC) &&
422 !xindex_is_subset(lperms.xindex, perms.xindex)) {
423 lperms.allow &= ~MAY_EXEC;
424 request |= MAY_EXEC;
425 info = "link not subset of target";
426 goto audit;
427 }
428
429done_tests:
430 error = 0;
431
432audit:
433 return aa_audit_file(profile, &lperms, OP_LINK, request, lname, tname,
434 NULL, cond->uid, info, error);
435}
436
437/**
438 * aa_path_link - Handle hard link permission check
439 * @label: the label being enforced (NOT NULL)
440 * @old_dentry: the target dentry (NOT NULL)
441 * @new_dir: directory the new link will be created in (NOT NULL)
442 * @new_dentry: the link being created (NOT NULL)
443 *
444 * Handle the permission test for a link & target pair. Permission
445 * is encoded as a pair where the link permission is determined
446 * first, and if allowed, the target is tested. The target test
447 * is done from the point of the link match (not start of DFA)
448 * making the target permission dependent on the link permission match.
449 *
450 * The subset test if required forces that permissions granted
451 * on link are a subset of the permission granted to target.
452 *
453 * Returns: %0 if allowed else error
454 */
455int aa_path_link(struct aa_label *label, struct dentry *old_dentry,
456 const struct path *new_dir, struct dentry *new_dentry)
457{
458 struct path link = { .mnt = new_dir->mnt, .dentry = new_dentry };
459 struct path target = { .mnt = new_dir->mnt, .dentry = old_dentry };
460 struct path_cond cond = {
461 d_backing_inode(old_dentry)->i_uid,
462 d_backing_inode(old_dentry)->i_mode
463 };
464 char *buffer = NULL, *buffer2 = NULL;
465 struct aa_profile *profile;
466 int error;
467
468 /* buffer freed below, lname is pointer in buffer */
469 buffer = aa_get_buffer(false);
470 buffer2 = aa_get_buffer(false);
471 error = -ENOMEM;
472 if (!buffer || !buffer2)
473 goto out;
474
475 error = fn_for_each_confined(label, profile,
476 profile_path_link(profile, &link, buffer, &target,
477 buffer2, &cond));
478out:
479 aa_put_buffer(buffer);
480 aa_put_buffer(buffer2);
481 return error;
482}
483
484static void update_file_ctx(struct aa_file_ctx *fctx, struct aa_label *label,
485 u32 request)
486{
487 struct aa_label *l, *old;
488
489 /* update caching of label on file_ctx */
490 spin_lock(&fctx->lock);
491 old = rcu_dereference_protected(fctx->label,
492 lockdep_is_held(&fctx->lock));
493 l = aa_label_merge(old, label, GFP_ATOMIC);
494 if (l) {
495 if (l != old) {
496 rcu_assign_pointer(fctx->label, l);
497 aa_put_label(old);
498 } else
499 aa_put_label(l);
500 fctx->allow |= request;
501 }
502 spin_unlock(&fctx->lock);
503}
504
505static int __file_path_perm(const char *op, struct aa_label *label,
506 struct aa_label *flabel, struct file *file,
507 u32 request, u32 denied, bool in_atomic)
508{
509 struct aa_profile *profile;
510 struct aa_perms perms = {};
511 struct path_cond cond = {
512 .uid = file_inode(file)->i_uid,
513 .mode = file_inode(file)->i_mode
514 };
515 char *buffer;
516 int flags, error;
517
518 /* revalidation due to label out of date. No revocation at this time */
519 if (!denied && aa_label_is_subset(flabel, label))
520 /* TODO: check for revocation on stale profiles */
521 return 0;
522
523 flags = PATH_DELEGATE_DELETED | (S_ISDIR(cond.mode) ? PATH_IS_DIR : 0);
524 buffer = aa_get_buffer(in_atomic);
525 if (!buffer)
526 return -ENOMEM;
527
528 /* check every profile in task label not in current cache */
529 error = fn_for_each_not_in_set(flabel, label, profile,
530 profile_path_perm(op, profile, &file->f_path, buffer,
531 request, &cond, flags, &perms));
532 if (denied && !error) {
533 /*
534 * check every profile in file label that was not tested
535 * in the initial check above.
536 *
537 * TODO: cache full perms so this only happens because of
538 * conditionals
539 * TODO: don't audit here
540 */
541 if (label == flabel)
542 error = fn_for_each(label, profile,
543 profile_path_perm(op, profile, &file->f_path,
544 buffer, request, &cond, flags,
545 &perms));
546 else
547 error = fn_for_each_not_in_set(label, flabel, profile,
548 profile_path_perm(op, profile, &file->f_path,
549 buffer, request, &cond, flags,
550 &perms));
551 }
552 if (!error)
553 update_file_ctx(file_ctx(file), label, request);
554
555 aa_put_buffer(buffer);
556
557 return error;
558}
559
560static int __file_sock_perm(const char *op, struct aa_label *label,
561 struct aa_label *flabel, struct file *file,
562 u32 request, u32 denied)
563{
564 struct socket *sock = (struct socket *) file->private_data;
565 int error;
566
567 AA_BUG(!sock);
568
569 /* revalidation due to label out of date. No revocation at this time */
570 if (!denied && aa_label_is_subset(flabel, label))
571 return 0;
572
573 /* TODO: improve to skip profiles cached in flabel */
574 error = aa_sock_file_perm(label, op, request, sock);
575 if (denied) {
576 /* TODO: improve to skip profiles checked above */
577 /* check every profile in file label to is cached */
578 last_error(error, aa_sock_file_perm(flabel, op, request, sock));
579 }
580 if (!error)
581 update_file_ctx(file_ctx(file), label, request);
582
583 return error;
584}
585
586/**
587 * aa_file_perm - do permission revalidation check & audit for @file
588 * @op: operation being checked
589 * @label: label being enforced (NOT NULL)
590 * @file: file to revalidate access permissions on (NOT NULL)
591 * @request: requested permissions
592 * @in_atomic: whether allocations need to be done in atomic context
593 *
594 * Returns: %0 if access allowed else error
595 */
596int aa_file_perm(const char *op, struct aa_label *label, struct file *file,
597 u32 request, bool in_atomic)
598{
599 struct aa_file_ctx *fctx;
600 struct aa_label *flabel;
601 u32 denied;
602 int error = 0;
603
604 AA_BUG(!label);
605 AA_BUG(!file);
606
607 fctx = file_ctx(file);
608
609 rcu_read_lock();
610 flabel = rcu_dereference(fctx->label);
611 AA_BUG(!flabel);
612
613 /* revalidate access, if task is unconfined, or the cached cred
614 * doesn't match or if the request is for more permissions than
615 * was granted.
616 *
617 * Note: the test for !unconfined(flabel) is to handle file
618 * delegation from unconfined tasks
619 */
620 denied = request & ~fctx->allow;
621 if (unconfined(label) || unconfined(flabel) ||
622 (!denied && aa_label_is_subset(flabel, label))) {
623 rcu_read_unlock();
624 goto done;
625 }
626
627 flabel = aa_get_newest_label(flabel);
628 rcu_read_unlock();
629 /* TODO: label cross check */
630
631 if (file->f_path.mnt && path_mediated_fs(file->f_path.dentry))
632 error = __file_path_perm(op, label, flabel, file, request,
633 denied, in_atomic);
634
635 else if (S_ISSOCK(file_inode(file)->i_mode))
636 error = __file_sock_perm(op, label, flabel, file, request,
637 denied);
638 aa_put_label(flabel);
639
640done:
641 return error;
642}
643
644static void revalidate_tty(struct aa_label *label)
645{
646 struct tty_struct *tty;
647 int drop_tty = 0;
648
649 tty = get_current_tty();
650 if (!tty)
651 return;
652
653 spin_lock(&tty->files_lock);
654 if (!list_empty(&tty->tty_files)) {
655 struct tty_file_private *file_priv;
656 struct file *file;
657 /* TODO: Revalidate access to controlling tty. */
658 file_priv = list_first_entry(&tty->tty_files,
659 struct tty_file_private, list);
660 file = file_priv->file;
661
662 if (aa_file_perm(OP_INHERIT, label, file, MAY_READ | MAY_WRITE,
663 IN_ATOMIC))
664 drop_tty = 1;
665 }
666 spin_unlock(&tty->files_lock);
667 tty_kref_put(tty);
668
669 if (drop_tty)
670 no_tty();
671}
672
673static int match_file(const void *p, struct file *file, unsigned int fd)
674{
675 struct aa_label *label = (struct aa_label *)p;
676
677 if (aa_file_perm(OP_INHERIT, label, file, aa_map_file_to_perms(file),
678 IN_ATOMIC))
679 return fd + 1;
680 return 0;
681}
682
683
684/* based on selinux's flush_unauthorized_files */
685void aa_inherit_files(const struct cred *cred, struct files_struct *files)
686{
687 struct aa_label *label = aa_get_newest_cred_label(cred);
688 struct file *devnull = NULL;
689 unsigned int n;
690
691 revalidate_tty(label);
692
693 /* Revalidate access to inherited open files. */
694 n = iterate_fd(files, 0, match_file, label);
695 if (!n) /* none found? */
696 goto out;
697
698 devnull = dentry_open(&aa_null, O_RDWR, cred);
699 if (IS_ERR(devnull))
700 devnull = NULL;
701 /* replace all the matching ones with this */
702 do {
703 replace_fd(n - 1, devnull, 0);
704 } while ((n = iterate_fd(files, n, match_file, label)) != 0);
705 if (devnull)
706 fput(devnull);
707out:
708 aa_put_label(label);
709}