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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#include <linux/fs.h>
15#include <linux/mount.h>
16
17#include "include/apparmor.h"
18#include "include/audit.h"
19#include "include/cred.h"
20#include "include/file.h"
21#include "include/match.h"
22#include "include/net.h"
23#include "include/path.h"
24#include "include/policy.h"
25#include "include/label.h"
26
27static u32 map_mask_to_chr_mask(u32 mask)
28{
29 u32 m = mask & PERMS_CHRS_MASK;
30
31 if (mask & AA_MAY_GETATTR)
32 m |= MAY_READ;
33 if (mask & (AA_MAY_SETATTR | AA_MAY_CHMOD | AA_MAY_CHOWN))
34 m |= MAY_WRITE;
35
36 return m;
37}
38
39/**
40 * file_audit_cb - call back for file specific audit fields
41 * @ab: audit_buffer (NOT NULL)
42 * @va: audit struct to audit values of (NOT NULL)
43 */
44static void file_audit_cb(struct audit_buffer *ab, void *va)
45{
46 struct common_audit_data *sa = va;
47 kuid_t fsuid = current_fsuid();
48 char str[10];
49
50 if (aad(sa)->request & AA_AUDIT_FILE_MASK) {
51 aa_perm_mask_to_str(str, sizeof(str), aa_file_perm_chrs,
52 map_mask_to_chr_mask(aad(sa)->request));
53 audit_log_format(ab, " requested_mask=\"%s\"", str);
54 }
55 if (aad(sa)->denied & AA_AUDIT_FILE_MASK) {
56 aa_perm_mask_to_str(str, sizeof(str), aa_file_perm_chrs,
57 map_mask_to_chr_mask(aad(sa)->denied));
58 audit_log_format(ab, " denied_mask=\"%s\"", str);
59 }
60 if (aad(sa)->request & AA_AUDIT_FILE_MASK) {
61 audit_log_format(ab, " fsuid=%d",
62 from_kuid(&init_user_ns, fsuid));
63 audit_log_format(ab, " ouid=%d",
64 from_kuid(&init_user_ns, aad(sa)->fs.ouid));
65 }
66
67 if (aad(sa)->peer) {
68 audit_log_format(ab, " target=");
69 aa_label_xaudit(ab, labels_ns(aad(sa)->label), aad(sa)->peer,
70 FLAG_VIEW_SUBNS, GFP_KERNEL);
71 } else if (aad(sa)->fs.target) {
72 audit_log_format(ab, " target=");
73 audit_log_untrustedstring(ab, aad(sa)->fs.target);
74 }
75}
76
77/**
78 * aa_audit_file - handle the auditing of file operations
79 * @profile: the profile being enforced (NOT NULL)
80 * @perms: the permissions computed for the request (NOT NULL)
81 * @op: operation being mediated
82 * @request: permissions requested
83 * @name: name of object being mediated (MAYBE NULL)
84 * @target: name of target (MAYBE NULL)
85 * @tlabel: target label (MAY BE NULL)
86 * @ouid: object uid
87 * @info: extra information message (MAYBE NULL)
88 * @error: 0 if operation allowed else failure error code
89 *
90 * Returns: %0 or error on failure
91 */
92int aa_audit_file(struct aa_profile *profile, struct aa_perms *perms,
93 const char *op, u32 request, const char *name,
94 const char *target, struct aa_label *tlabel,
95 kuid_t ouid, const char *info, int error)
96{
97 int type = AUDIT_APPARMOR_AUTO;
98 DEFINE_AUDIT_DATA(sa, LSM_AUDIT_DATA_TASK, op);
99
100 sa.u.tsk = NULL;
101 aad(&sa)->request = request;
102 aad(&sa)->name = name;
103 aad(&sa)->fs.target = target;
104 aad(&sa)->peer = tlabel;
105 aad(&sa)->fs.ouid = ouid;
106 aad(&sa)->info = info;
107 aad(&sa)->error = error;
108 sa.u.tsk = NULL;
109
110 if (likely(!aad(&sa)->error)) {
111 u32 mask = perms->audit;
112
113 if (unlikely(AUDIT_MODE(profile) == AUDIT_ALL))
114 mask = 0xffff;
115
116 /* mask off perms that are not being force audited */
117 aad(&sa)->request &= mask;
118
119 if (likely(!aad(&sa)->request))
120 return 0;
121 type = AUDIT_APPARMOR_AUDIT;
122 } else {
123 /* only report permissions that were denied */
124 aad(&sa)->request = aad(&sa)->request & ~perms->allow;
125 AA_BUG(!aad(&sa)->request);
126
127 if (aad(&sa)->request & perms->kill)
128 type = AUDIT_APPARMOR_KILL;
129
130 /* quiet known rejects, assumes quiet and kill do not overlap */
131 if ((aad(&sa)->request & perms->quiet) &&
132 AUDIT_MODE(profile) != AUDIT_NOQUIET &&
133 AUDIT_MODE(profile) != AUDIT_ALL)
134 aad(&sa)->request &= ~perms->quiet;
135
136 if (!aad(&sa)->request)
137 return aad(&sa)->error;
138 }
139
140 aad(&sa)->denied = aad(&sa)->request & ~perms->allow;
141 return aa_audit(type, profile, &sa, file_audit_cb);
142}
143
144/**
145 * is_deleted - test if a file has been completely unlinked
146 * @dentry: dentry of file to test for deletion (NOT NULL)
147 *
148 * Returns: true if deleted else false
149 */
150static inline bool is_deleted(struct dentry *dentry)
151{
152 if (d_unlinked(dentry) && d_backing_inode(dentry)->i_nlink == 0)
153 return true;
154 return false;
155}
156
157static int path_name(const char *op, struct aa_label *label,
158 const struct path *path, int flags, char *buffer,
159 const char **name, struct path_cond *cond, u32 request)
160{
161 struct aa_profile *profile;
162 const char *info = NULL;
163 int error;
164
165 error = aa_path_name(path, flags, buffer, name, &info,
166 labels_profile(label)->disconnected);
167 if (error) {
168 fn_for_each_confined(label, profile,
169 aa_audit_file(profile, &nullperms, op, request, *name,
170 NULL, NULL, cond->uid, info, error));
171 return error;
172 }
173
174 return 0;
175}
176
177/**
178 * map_old_perms - map old file perms layout to the new layout
179 * @old: permission set in old mapping
180 *
181 * Returns: new permission mapping
182 */
183static u32 map_old_perms(u32 old)
184{
185 u32 new = old & 0xf;
186 if (old & MAY_READ)
187 new |= AA_MAY_GETATTR | AA_MAY_OPEN;
188 if (old & MAY_WRITE)
189 new |= AA_MAY_SETATTR | AA_MAY_CREATE | AA_MAY_DELETE |
190 AA_MAY_CHMOD | AA_MAY_CHOWN | AA_MAY_OPEN;
191 if (old & 0x10)
192 new |= AA_MAY_LINK;
193 /* the old mapping lock and link_subset flags where overlaid
194 * and use was determined by part of a pair that they were in
195 */
196 if (old & 0x20)
197 new |= AA_MAY_LOCK | AA_LINK_SUBSET;
198 if (old & 0x40) /* AA_EXEC_MMAP */
199 new |= AA_EXEC_MMAP;
200
201 return new;
202}
203
204/**
205 * aa_compute_fperms - convert dfa compressed perms to internal perms
206 * @dfa: dfa to compute perms for (NOT NULL)
207 * @state: state in dfa
208 * @cond: conditions to consider (NOT NULL)
209 *
210 * TODO: convert from dfa + state to permission entry, do computation conversion
211 * at load time.
212 *
213 * Returns: computed permission set
214 */
215struct aa_perms aa_compute_fperms(struct aa_dfa *dfa, unsigned int state,
216 struct path_cond *cond)
217{
218 /* FIXME: change over to new dfa format
219 * currently file perms are encoded in the dfa, new format
220 * splits the permissions from the dfa. This mapping can be
221 * done at profile load
222 */
223 struct aa_perms perms = { };
224
225 if (uid_eq(current_fsuid(), cond->uid)) {
226 perms.allow = map_old_perms(dfa_user_allow(dfa, state));
227 perms.audit = map_old_perms(dfa_user_audit(dfa, state));
228 perms.quiet = map_old_perms(dfa_user_quiet(dfa, state));
229 perms.xindex = dfa_user_xindex(dfa, state);
230 } else {
231 perms.allow = map_old_perms(dfa_other_allow(dfa, state));
232 perms.audit = map_old_perms(dfa_other_audit(dfa, state));
233 perms.quiet = map_old_perms(dfa_other_quiet(dfa, state));
234 perms.xindex = dfa_other_xindex(dfa, state);
235 }
236 perms.allow |= AA_MAY_GETATTR;
237
238 /* change_profile wasn't determined by ownership in old mapping */
239 if (ACCEPT_TABLE(dfa)[state] & 0x80000000)
240 perms.allow |= AA_MAY_CHANGE_PROFILE;
241 if (ACCEPT_TABLE(dfa)[state] & 0x40000000)
242 perms.allow |= AA_MAY_ONEXEC;
243
244 return perms;
245}
246
247/**
248 * aa_str_perms - find permission that match @name
249 * @dfa: to match against (MAYBE NULL)
250 * @state: state to start matching in
251 * @name: string to match against dfa (NOT NULL)
252 * @cond: conditions to consider for permission set computation (NOT NULL)
253 * @perms: Returns - the permissions found when matching @name
254 *
255 * Returns: the final state in @dfa when beginning @start and walking @name
256 */
257unsigned int aa_str_perms(struct aa_dfa *dfa, unsigned int start,
258 const char *name, struct path_cond *cond,
259 struct aa_perms *perms)
260{
261 unsigned int state;
262 state = aa_dfa_match(dfa, start, name);
263 *perms = aa_compute_fperms(dfa, state, cond);
264
265 return state;
266}
267
268int __aa_path_perm(const char *op, struct aa_profile *profile, const char *name,
269 u32 request, struct path_cond *cond, int flags,
270 struct aa_perms *perms)
271{
272 int e = 0;
273
274 if (profile_unconfined(profile))
275 return 0;
276 aa_str_perms(profile->file.dfa, profile->file.start, name, cond, perms);
277 if (request & ~perms->allow)
278 e = -EACCES;
279 return aa_audit_file(profile, perms, op, request, name, NULL, NULL,
280 cond->uid, NULL, e);
281}
282
283
284static int profile_path_perm(const char *op, struct aa_profile *profile,
285 const struct path *path, char *buffer, u32 request,
286 struct path_cond *cond, int flags,
287 struct aa_perms *perms)
288{
289 const char *name;
290 int error;
291
292 if (profile_unconfined(profile))
293 return 0;
294
295 error = path_name(op, &profile->label, path,
296 flags | profile->path_flags, buffer, &name, cond,
297 request);
298 if (error)
299 return error;
300 return __aa_path_perm(op, profile, name, request, cond, flags,
301 perms);
302}
303
304/**
305 * aa_path_perm - do permissions check & audit for @path
306 * @op: operation being checked
307 * @label: profile being enforced (NOT NULL)
308 * @path: path to check permissions of (NOT NULL)
309 * @flags: any additional path flags beyond what the profile specifies
310 * @request: requested permissions
311 * @cond: conditional info for this request (NOT NULL)
312 *
313 * Returns: %0 else error if access denied or other error
314 */
315int aa_path_perm(const char *op, struct aa_label *label,
316 const struct path *path, int flags, u32 request,
317 struct path_cond *cond)
318{
319 struct aa_perms perms = {};
320 struct aa_profile *profile;
321 char *buffer = NULL;
322 int error;
323
324 flags |= PATH_DELEGATE_DELETED | (S_ISDIR(cond->mode) ? PATH_IS_DIR :
325 0);
326 buffer = aa_get_buffer(false);
327 if (!buffer)
328 return -ENOMEM;
329 error = fn_for_each_confined(label, profile,
330 profile_path_perm(op, profile, path, buffer, request,
331 cond, flags, &perms));
332
333 aa_put_buffer(buffer);
334
335 return error;
336}
337
338/**
339 * xindex_is_subset - helper for aa_path_link
340 * @link: link permission set
341 * @target: target permission set
342 *
343 * test target x permissions are equal OR a subset of link x permissions
344 * this is done as part of the subset test, where a hardlink must have
345 * a subset of permissions that the target has.
346 *
347 * Returns: true if subset else false
348 */
349static inline bool xindex_is_subset(u32 link, u32 target)
350{
351 if (((link & ~AA_X_UNSAFE) != (target & ~AA_X_UNSAFE)) ||
352 ((link & AA_X_UNSAFE) && !(target & AA_X_UNSAFE)))
353 return false;
354
355 return true;
356}
357
358static int profile_path_link(struct aa_profile *profile,
359 const struct path *link, char *buffer,
360 const struct path *target, char *buffer2,
361 struct path_cond *cond)
362{
363 const char *lname, *tname = NULL;
364 struct aa_perms lperms = {}, perms;
365 const char *info = NULL;
366 u32 request = AA_MAY_LINK;
367 unsigned int state;
368 int error;
369
370 error = path_name(OP_LINK, &profile->label, link, profile->path_flags,
371 buffer, &lname, cond, AA_MAY_LINK);
372 if (error)
373 goto audit;
374
375 /* buffer2 freed below, tname is pointer in buffer2 */
376 error = path_name(OP_LINK, &profile->label, target, profile->path_flags,
377 buffer2, &tname, cond, AA_MAY_LINK);
378 if (error)
379 goto audit;
380
381 error = -EACCES;
382 /* aa_str_perms - handles the case of the dfa being NULL */
383 state = aa_str_perms(profile->file.dfa, profile->file.start, lname,
384 cond, &lperms);
385
386 if (!(lperms.allow & AA_MAY_LINK))
387 goto audit;
388
389 /* test to see if target can be paired with link */
390 state = aa_dfa_null_transition(profile->file.dfa, state);
391 aa_str_perms(profile->file.dfa, state, tname, cond, &perms);
392
393 /* force audit/quiet masks for link are stored in the second entry
394 * in the link pair.
395 */
396 lperms.audit = perms.audit;
397 lperms.quiet = perms.quiet;
398 lperms.kill = perms.kill;
399
400 if (!(perms.allow & AA_MAY_LINK)) {
401 info = "target restricted";
402 lperms = perms;
403 goto audit;
404 }
405
406 /* done if link subset test is not required */
407 if (!(perms.allow & AA_LINK_SUBSET))
408 goto done_tests;
409
410 /* Do link perm subset test requiring allowed permission on link are
411 * a subset of the allowed permissions on target.
412 */
413 aa_str_perms(profile->file.dfa, profile->file.start, tname, cond,
414 &perms);
415
416 /* AA_MAY_LINK is not considered in the subset test */
417 request = lperms.allow & ~AA_MAY_LINK;
418 lperms.allow &= perms.allow | AA_MAY_LINK;
419
420 request |= AA_AUDIT_FILE_MASK & (lperms.allow & ~perms.allow);
421 if (request & ~lperms.allow) {
422 goto audit;
423 } else if ((lperms.allow & MAY_EXEC) &&
424 !xindex_is_subset(lperms.xindex, perms.xindex)) {
425 lperms.allow &= ~MAY_EXEC;
426 request |= MAY_EXEC;
427 info = "link not subset of target";
428 goto audit;
429 }
430
431done_tests:
432 error = 0;
433
434audit:
435 return aa_audit_file(profile, &lperms, OP_LINK, request, lname, tname,
436 NULL, cond->uid, info, error);
437}
438
439/**
440 * aa_path_link - Handle hard link permission check
441 * @label: the label being enforced (NOT NULL)
442 * @old_dentry: the target dentry (NOT NULL)
443 * @new_dir: directory the new link will be created in (NOT NULL)
444 * @new_dentry: the link being created (NOT NULL)
445 *
446 * Handle the permission test for a link & target pair. Permission
447 * is encoded as a pair where the link permission is determined
448 * first, and if allowed, the target is tested. The target test
449 * is done from the point of the link match (not start of DFA)
450 * making the target permission dependent on the link permission match.
451 *
452 * The subset test if required forces that permissions granted
453 * on link are a subset of the permission granted to target.
454 *
455 * Returns: %0 if allowed else error
456 */
457int aa_path_link(struct aa_label *label, struct dentry *old_dentry,
458 const struct path *new_dir, struct dentry *new_dentry)
459{
460 struct path link = { .mnt = new_dir->mnt, .dentry = new_dentry };
461 struct path target = { .mnt = new_dir->mnt, .dentry = old_dentry };
462 struct path_cond cond = {
463 d_backing_inode(old_dentry)->i_uid,
464 d_backing_inode(old_dentry)->i_mode
465 };
466 char *buffer = NULL, *buffer2 = NULL;
467 struct aa_profile *profile;
468 int error;
469
470 /* buffer freed below, lname is pointer in buffer */
471 buffer = aa_get_buffer(false);
472 buffer2 = aa_get_buffer(false);
473 error = -ENOMEM;
474 if (!buffer || !buffer2)
475 goto out;
476
477 error = fn_for_each_confined(label, profile,
478 profile_path_link(profile, &link, buffer, &target,
479 buffer2, &cond));
480out:
481 aa_put_buffer(buffer);
482 aa_put_buffer(buffer2);
483 return error;
484}
485
486static void update_file_ctx(struct aa_file_ctx *fctx, struct aa_label *label,
487 u32 request)
488{
489 struct aa_label *l, *old;
490
491 /* update caching of label on file_ctx */
492 spin_lock(&fctx->lock);
493 old = rcu_dereference_protected(fctx->label,
494 lockdep_is_held(&fctx->lock));
495 l = aa_label_merge(old, label, GFP_ATOMIC);
496 if (l) {
497 if (l != old) {
498 rcu_assign_pointer(fctx->label, l);
499 aa_put_label(old);
500 } else
501 aa_put_label(l);
502 fctx->allow |= request;
503 }
504 spin_unlock(&fctx->lock);
505}
506
507static int __file_path_perm(const char *op, struct aa_label *label,
508 struct aa_label *flabel, struct file *file,
509 u32 request, u32 denied, bool in_atomic)
510{
511 struct aa_profile *profile;
512 struct aa_perms perms = {};
513 struct path_cond cond = {
514 .uid = i_uid_into_mnt(file_mnt_user_ns(file), file_inode(file)),
515 .mode = file_inode(file)->i_mode
516 };
517 char *buffer;
518 int flags, error;
519
520 /* revalidation due to label out of date. No revocation at this time */
521 if (!denied && aa_label_is_subset(flabel, label))
522 /* TODO: check for revocation on stale profiles */
523 return 0;
524
525 flags = PATH_DELEGATE_DELETED | (S_ISDIR(cond.mode) ? PATH_IS_DIR : 0);
526 buffer = aa_get_buffer(in_atomic);
527 if (!buffer)
528 return -ENOMEM;
529
530 /* check every profile in task label not in current cache */
531 error = fn_for_each_not_in_set(flabel, label, profile,
532 profile_path_perm(op, profile, &file->f_path, buffer,
533 request, &cond, flags, &perms));
534 if (denied && !error) {
535 /*
536 * check every profile in file label that was not tested
537 * in the initial check above.
538 *
539 * TODO: cache full perms so this only happens because of
540 * conditionals
541 * TODO: don't audit here
542 */
543 if (label == flabel)
544 error = fn_for_each(label, profile,
545 profile_path_perm(op, profile, &file->f_path,
546 buffer, request, &cond, flags,
547 &perms));
548 else
549 error = fn_for_each_not_in_set(label, flabel, profile,
550 profile_path_perm(op, profile, &file->f_path,
551 buffer, request, &cond, flags,
552 &perms));
553 }
554 if (!error)
555 update_file_ctx(file_ctx(file), label, request);
556
557 aa_put_buffer(buffer);
558
559 return error;
560}
561
562static int __file_sock_perm(const char *op, struct aa_label *label,
563 struct aa_label *flabel, struct file *file,
564 u32 request, u32 denied)
565{
566 struct socket *sock = (struct socket *) file->private_data;
567 int error;
568
569 AA_BUG(!sock);
570
571 /* revalidation due to label out of date. No revocation at this time */
572 if (!denied && aa_label_is_subset(flabel, label))
573 return 0;
574
575 /* TODO: improve to skip profiles cached in flabel */
576 error = aa_sock_file_perm(label, op, request, sock);
577 if (denied) {
578 /* TODO: improve to skip profiles checked above */
579 /* check every profile in file label to is cached */
580 last_error(error, aa_sock_file_perm(flabel, op, request, sock));
581 }
582 if (!error)
583 update_file_ctx(file_ctx(file), label, request);
584
585 return error;
586}
587
588/**
589 * aa_file_perm - do permission revalidation check & audit for @file
590 * @op: operation being checked
591 * @label: label being enforced (NOT NULL)
592 * @file: file to revalidate access permissions on (NOT NULL)
593 * @request: requested permissions
594 * @in_atomic: whether allocations need to be done in atomic context
595 *
596 * Returns: %0 if access allowed else error
597 */
598int aa_file_perm(const char *op, struct aa_label *label, struct file *file,
599 u32 request, bool in_atomic)
600{
601 struct aa_file_ctx *fctx;
602 struct aa_label *flabel;
603 u32 denied;
604 int error = 0;
605
606 AA_BUG(!label);
607 AA_BUG(!file);
608
609 fctx = file_ctx(file);
610
611 rcu_read_lock();
612 flabel = rcu_dereference(fctx->label);
613 AA_BUG(!flabel);
614
615 /* revalidate access, if task is unconfined, or the cached cred
616 * doesn't match or if the request is for more permissions than
617 * was granted.
618 *
619 * Note: the test for !unconfined(flabel) is to handle file
620 * delegation from unconfined tasks
621 */
622 denied = request & ~fctx->allow;
623 if (unconfined(label) || unconfined(flabel) ||
624 (!denied && aa_label_is_subset(flabel, label))) {
625 rcu_read_unlock();
626 goto done;
627 }
628
629 flabel = aa_get_newest_label(flabel);
630 rcu_read_unlock();
631 /* TODO: label cross check */
632
633 if (file->f_path.mnt && path_mediated_fs(file->f_path.dentry))
634 error = __file_path_perm(op, label, flabel, file, request,
635 denied, in_atomic);
636
637 else if (S_ISSOCK(file_inode(file)->i_mode))
638 error = __file_sock_perm(op, label, flabel, file, request,
639 denied);
640 aa_put_label(flabel);
641
642done:
643 return error;
644}
645
646static void revalidate_tty(struct aa_label *label)
647{
648 struct tty_struct *tty;
649 int drop_tty = 0;
650
651 tty = get_current_tty();
652 if (!tty)
653 return;
654
655 spin_lock(&tty->files_lock);
656 if (!list_empty(&tty->tty_files)) {
657 struct tty_file_private *file_priv;
658 struct file *file;
659 /* TODO: Revalidate access to controlling tty. */
660 file_priv = list_first_entry(&tty->tty_files,
661 struct tty_file_private, list);
662 file = file_priv->file;
663
664 if (aa_file_perm(OP_INHERIT, label, file, MAY_READ | MAY_WRITE,
665 IN_ATOMIC))
666 drop_tty = 1;
667 }
668 spin_unlock(&tty->files_lock);
669 tty_kref_put(tty);
670
671 if (drop_tty)
672 no_tty();
673}
674
675static int match_file(const void *p, struct file *file, unsigned int fd)
676{
677 struct aa_label *label = (struct aa_label *)p;
678
679 if (aa_file_perm(OP_INHERIT, label, file, aa_map_file_to_perms(file),
680 IN_ATOMIC))
681 return fd + 1;
682 return 0;
683}
684
685
686/* based on selinux's flush_unauthorized_files */
687void aa_inherit_files(const struct cred *cred, struct files_struct *files)
688{
689 struct aa_label *label = aa_get_newest_cred_label(cred);
690 struct file *devnull = NULL;
691 unsigned int n;
692
693 revalidate_tty(label);
694
695 /* Revalidate access to inherited open files. */
696 n = iterate_fd(files, 0, match_file, label);
697 if (!n) /* none found? */
698 goto out;
699
700 devnull = dentry_open(&aa_null, O_RDWR, cred);
701 if (IS_ERR(devnull))
702 devnull = NULL;
703 /* replace all the matching ones with this */
704 do {
705 replace_fd(n - 1, devnull, 0);
706 } while ((n = iterate_fd(files, n, match_file, label)) != 0);
707 if (devnull)
708 fput(devnull);
709out:
710 aa_put_label(label);
711}