Merge 4.14.14 into android-4.14
[GitHub/moto-9609/android_kernel_motorola_exynos9610.git] / security / apparmor / mount.c
1 /*
2 * AppArmor security module
3 *
4 * This file contains AppArmor mediation of files
5 *
6 * Copyright (C) 1998-2008 Novell/SUSE
7 * Copyright 2009-2017 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/fs.h>
16 #include <linux/mount.h>
17 #include <linux/namei.h>
18
19 #include "include/apparmor.h"
20 #include "include/audit.h"
21 #include "include/context.h"
22 #include "include/domain.h"
23 #include "include/file.h"
24 #include "include/match.h"
25 #include "include/mount.h"
26 #include "include/path.h"
27 #include "include/policy.h"
28
29
30 static void audit_mnt_flags(struct audit_buffer *ab, unsigned long flags)
31 {
32 if (flags & MS_RDONLY)
33 audit_log_format(ab, "ro");
34 else
35 audit_log_format(ab, "rw");
36 if (flags & MS_NOSUID)
37 audit_log_format(ab, ", nosuid");
38 if (flags & MS_NODEV)
39 audit_log_format(ab, ", nodev");
40 if (flags & MS_NOEXEC)
41 audit_log_format(ab, ", noexec");
42 if (flags & MS_SYNCHRONOUS)
43 audit_log_format(ab, ", sync");
44 if (flags & MS_REMOUNT)
45 audit_log_format(ab, ", remount");
46 if (flags & MS_MANDLOCK)
47 audit_log_format(ab, ", mand");
48 if (flags & MS_DIRSYNC)
49 audit_log_format(ab, ", dirsync");
50 if (flags & MS_NOATIME)
51 audit_log_format(ab, ", noatime");
52 if (flags & MS_NODIRATIME)
53 audit_log_format(ab, ", nodiratime");
54 if (flags & MS_BIND)
55 audit_log_format(ab, flags & MS_REC ? ", rbind" : ", bind");
56 if (flags & MS_MOVE)
57 audit_log_format(ab, ", move");
58 if (flags & MS_SILENT)
59 audit_log_format(ab, ", silent");
60 if (flags & MS_POSIXACL)
61 audit_log_format(ab, ", acl");
62 if (flags & MS_UNBINDABLE)
63 audit_log_format(ab, flags & MS_REC ? ", runbindable" :
64 ", unbindable");
65 if (flags & MS_PRIVATE)
66 audit_log_format(ab, flags & MS_REC ? ", rprivate" :
67 ", private");
68 if (flags & MS_SLAVE)
69 audit_log_format(ab, flags & MS_REC ? ", rslave" :
70 ", slave");
71 if (flags & MS_SHARED)
72 audit_log_format(ab, flags & MS_REC ? ", rshared" :
73 ", shared");
74 if (flags & MS_RELATIME)
75 audit_log_format(ab, ", relatime");
76 if (flags & MS_I_VERSION)
77 audit_log_format(ab, ", iversion");
78 if (flags & MS_STRICTATIME)
79 audit_log_format(ab, ", strictatime");
80 if (flags & MS_NOUSER)
81 audit_log_format(ab, ", nouser");
82 }
83
84 /**
85 * audit_cb - call back for mount specific audit fields
86 * @ab: audit_buffer (NOT NULL)
87 * @va: audit struct to audit values of (NOT NULL)
88 */
89 static void audit_cb(struct audit_buffer *ab, void *va)
90 {
91 struct common_audit_data *sa = va;
92
93 if (aad(sa)->mnt.type) {
94 audit_log_format(ab, " fstype=");
95 audit_log_untrustedstring(ab, aad(sa)->mnt.type);
96 }
97 if (aad(sa)->mnt.src_name) {
98 audit_log_format(ab, " srcname=");
99 audit_log_untrustedstring(ab, aad(sa)->mnt.src_name);
100 }
101 if (aad(sa)->mnt.trans) {
102 audit_log_format(ab, " trans=");
103 audit_log_untrustedstring(ab, aad(sa)->mnt.trans);
104 }
105 if (aad(sa)->mnt.flags) {
106 audit_log_format(ab, " flags=\"");
107 audit_mnt_flags(ab, aad(sa)->mnt.flags);
108 audit_log_format(ab, "\"");
109 }
110 if (aad(sa)->mnt.data) {
111 audit_log_format(ab, " options=");
112 audit_log_untrustedstring(ab, aad(sa)->mnt.data);
113 }
114 }
115
116 /**
117 * audit_mount - handle the auditing of mount operations
118 * @profile: the profile being enforced (NOT NULL)
119 * @op: operation being mediated (NOT NULL)
120 * @name: name of object being mediated (MAYBE NULL)
121 * @src_name: src_name of object being mediated (MAYBE_NULL)
122 * @type: type of filesystem (MAYBE_NULL)
123 * @trans: name of trans (MAYBE NULL)
124 * @flags: filesystem idependent mount flags
125 * @data: filesystem mount flags
126 * @request: permissions requested
127 * @perms: the permissions computed for the request (NOT NULL)
128 * @info: extra information message (MAYBE NULL)
129 * @error: 0 if operation allowed else failure error code
130 *
131 * Returns: %0 or error on failure
132 */
133 static int audit_mount(struct aa_profile *profile, const char *op,
134 const char *name, const char *src_name,
135 const char *type, const char *trans,
136 unsigned long flags, const void *data, u32 request,
137 struct aa_perms *perms, const char *info, int error)
138 {
139 int audit_type = AUDIT_APPARMOR_AUTO;
140 DEFINE_AUDIT_DATA(sa, LSM_AUDIT_DATA_NONE, op);
141
142 if (likely(!error)) {
143 u32 mask = perms->audit;
144
145 if (unlikely(AUDIT_MODE(profile) == AUDIT_ALL))
146 mask = 0xffff;
147
148 /* mask off perms that are not being force audited */
149 request &= mask;
150
151 if (likely(!request))
152 return 0;
153 audit_type = AUDIT_APPARMOR_AUDIT;
154 } else {
155 /* only report permissions that were denied */
156 request = request & ~perms->allow;
157
158 if (request & perms->kill)
159 audit_type = AUDIT_APPARMOR_KILL;
160
161 /* quiet known rejects, assumes quiet and kill do not overlap */
162 if ((request & perms->quiet) &&
163 AUDIT_MODE(profile) != AUDIT_NOQUIET &&
164 AUDIT_MODE(profile) != AUDIT_ALL)
165 request &= ~perms->quiet;
166
167 if (!request)
168 return error;
169 }
170
171 aad(&sa)->name = name;
172 aad(&sa)->mnt.src_name = src_name;
173 aad(&sa)->mnt.type = type;
174 aad(&sa)->mnt.trans = trans;
175 aad(&sa)->mnt.flags = flags;
176 if (data && (perms->audit & AA_AUDIT_DATA))
177 aad(&sa)->mnt.data = data;
178 aad(&sa)->info = info;
179 aad(&sa)->error = error;
180
181 return aa_audit(audit_type, profile, &sa, audit_cb);
182 }
183
184 /**
185 * match_mnt_flags - Do an ordered match on mount flags
186 * @dfa: dfa to match against
187 * @state: state to start in
188 * @flags: mount flags to match against
189 *
190 * Mount flags are encoded as an ordered match. This is done instead of
191 * checking against a simple bitmask, to allow for logical operations
192 * on the flags.
193 *
194 * Returns: next state after flags match
195 */
196 static unsigned int match_mnt_flags(struct aa_dfa *dfa, unsigned int state,
197 unsigned long flags)
198 {
199 unsigned int i;
200
201 for (i = 0; i <= 31 ; ++i) {
202 if ((1 << i) & flags)
203 state = aa_dfa_next(dfa, state, i + 1);
204 }
205
206 return state;
207 }
208
209 /**
210 * compute_mnt_perms - compute mount permission associated with @state
211 * @dfa: dfa to match against (NOT NULL)
212 * @state: state match finished in
213 *
214 * Returns: mount permissions
215 */
216 static struct aa_perms compute_mnt_perms(struct aa_dfa *dfa,
217 unsigned int state)
218 {
219 struct aa_perms perms;
220
221 perms.kill = 0;
222 perms.allow = dfa_user_allow(dfa, state);
223 perms.audit = dfa_user_audit(dfa, state);
224 perms.quiet = dfa_user_quiet(dfa, state);
225 perms.xindex = dfa_user_xindex(dfa, state);
226
227 return perms;
228 }
229
230 static const char * const mnt_info_table[] = {
231 "match succeeded",
232 "failed mntpnt match",
233 "failed srcname match",
234 "failed type match",
235 "failed flags match",
236 "failed data match"
237 };
238
239 /*
240 * Returns 0 on success else element that match failed in, this is the
241 * index into the mnt_info_table above
242 */
243 static int do_match_mnt(struct aa_dfa *dfa, unsigned int start,
244 const char *mntpnt, const char *devname,
245 const char *type, unsigned long flags,
246 void *data, bool binary, struct aa_perms *perms)
247 {
248 unsigned int state;
249
250 AA_BUG(!dfa);
251 AA_BUG(!perms);
252
253 state = aa_dfa_match(dfa, start, mntpnt);
254 state = aa_dfa_null_transition(dfa, state);
255 if (!state)
256 return 1;
257
258 if (devname)
259 state = aa_dfa_match(dfa, state, devname);
260 state = aa_dfa_null_transition(dfa, state);
261 if (!state)
262 return 2;
263
264 if (type)
265 state = aa_dfa_match(dfa, state, type);
266 state = aa_dfa_null_transition(dfa, state);
267 if (!state)
268 return 3;
269
270 state = match_mnt_flags(dfa, state, flags);
271 if (!state)
272 return 4;
273 *perms = compute_mnt_perms(dfa, state);
274 if (perms->allow & AA_MAY_MOUNT)
275 return 0;
276
277 /* only match data if not binary and the DFA flags data is expected */
278 if (data && !binary && (perms->allow & AA_MNT_CONT_MATCH)) {
279 state = aa_dfa_null_transition(dfa, state);
280 if (!state)
281 return 4;
282
283 state = aa_dfa_match(dfa, state, data);
284 if (!state)
285 return 5;
286 *perms = compute_mnt_perms(dfa, state);
287 if (perms->allow & AA_MAY_MOUNT)
288 return 0;
289 }
290
291 /* failed at end of flags match */
292 return 4;
293 }
294
295
296 static int path_flags(struct aa_profile *profile, const struct path *path)
297 {
298 AA_BUG(!profile);
299 AA_BUG(!path);
300
301 return profile->path_flags |
302 (S_ISDIR(path->dentry->d_inode->i_mode) ? PATH_IS_DIR : 0);
303 }
304
305 /**
306 * match_mnt_path_str - handle path matching for mount
307 * @profile: the confining profile
308 * @mntpath: for the mntpnt (NOT NULL)
309 * @buffer: buffer to be used to lookup mntpath
310 * @devnme: string for the devname/src_name (MAY BE NULL OR ERRPTR)
311 * @type: string for the dev type (MAYBE NULL)
312 * @flags: mount flags to match
313 * @data: fs mount data (MAYBE NULL)
314 * @binary: whether @data is binary
315 * @devinfo: error str if (IS_ERR(@devname))
316 *
317 * Returns: 0 on success else error
318 */
319 static int match_mnt_path_str(struct aa_profile *profile,
320 const struct path *mntpath, char *buffer,
321 const char *devname, const char *type,
322 unsigned long flags, void *data, bool binary,
323 const char *devinfo)
324 {
325 struct aa_perms perms = { };
326 const char *mntpnt = NULL, *info = NULL;
327 int pos, error;
328
329 AA_BUG(!profile);
330 AA_BUG(!mntpath);
331 AA_BUG(!buffer);
332
333 if (!PROFILE_MEDIATES(profile, AA_CLASS_MOUNT))
334 return 0;
335
336 error = aa_path_name(mntpath, path_flags(profile, mntpath), buffer,
337 &mntpnt, &info, profile->disconnected);
338 if (error)
339 goto audit;
340 if (IS_ERR(devname)) {
341 error = PTR_ERR(devname);
342 devname = NULL;
343 info = devinfo;
344 goto audit;
345 }
346
347 error = -EACCES;
348 pos = do_match_mnt(profile->policy.dfa,
349 profile->policy.start[AA_CLASS_MOUNT],
350 mntpnt, devname, type, flags, data, binary, &perms);
351 if (pos) {
352 info = mnt_info_table[pos];
353 goto audit;
354 }
355 error = 0;
356
357 audit:
358 return audit_mount(profile, OP_MOUNT, mntpnt, devname, type, NULL,
359 flags, data, AA_MAY_MOUNT, &perms, info, error);
360 }
361
362 /**
363 * match_mnt - handle path matching for mount
364 * @profile: the confining profile
365 * @mntpath: for the mntpnt (NOT NULL)
366 * @buffer: buffer to be used to lookup mntpath
367 * @devpath: path devname/src_name (MAYBE NULL)
368 * @devbuffer: buffer to be used to lookup devname/src_name
369 * @type: string for the dev type (MAYBE NULL)
370 * @flags: mount flags to match
371 * @data: fs mount data (MAYBE NULL)
372 * @binary: whether @data is binary
373 *
374 * Returns: 0 on success else error
375 */
376 static int match_mnt(struct aa_profile *profile, const struct path *path,
377 char *buffer, struct path *devpath, char *devbuffer,
378 const char *type, unsigned long flags, void *data,
379 bool binary)
380 {
381 const char *devname = NULL, *info = NULL;
382 int error = -EACCES;
383
384 AA_BUG(!profile);
385 AA_BUG(devpath && !devbuffer);
386
387 if (!PROFILE_MEDIATES(profile, AA_CLASS_MOUNT))
388 return 0;
389
390 if (devpath) {
391 error = aa_path_name(devpath, path_flags(profile, devpath),
392 devbuffer, &devname, &info,
393 profile->disconnected);
394 if (error)
395 devname = ERR_PTR(error);
396 }
397
398 return match_mnt_path_str(profile, path, buffer, devname, type, flags,
399 data, binary, info);
400 }
401
402 int aa_remount(struct aa_label *label, const struct path *path,
403 unsigned long flags, void *data)
404 {
405 struct aa_profile *profile;
406 char *buffer = NULL;
407 bool binary;
408 int error;
409
410 AA_BUG(!label);
411 AA_BUG(!path);
412
413 binary = path->dentry->d_sb->s_type->fs_flags & FS_BINARY_MOUNTDATA;
414
415 get_buffers(buffer);
416 error = fn_for_each_confined(label, profile,
417 match_mnt(profile, path, buffer, NULL, NULL, NULL,
418 flags, data, binary));
419 put_buffers(buffer);
420
421 return error;
422 }
423
424 int aa_bind_mount(struct aa_label *label, const struct path *path,
425 const char *dev_name, unsigned long flags)
426 {
427 struct aa_profile *profile;
428 char *buffer = NULL, *old_buffer = NULL;
429 struct path old_path;
430 int error;
431
432 AA_BUG(!label);
433 AA_BUG(!path);
434
435 if (!dev_name || !*dev_name)
436 return -EINVAL;
437
438 flags &= MS_REC | MS_BIND;
439
440 error = kern_path(dev_name, LOOKUP_FOLLOW|LOOKUP_AUTOMOUNT, &old_path);
441 if (error)
442 return error;
443
444 get_buffers(buffer, old_buffer);
445 error = fn_for_each_confined(label, profile,
446 match_mnt(profile, path, buffer, &old_path, old_buffer,
447 NULL, flags, NULL, false));
448 put_buffers(buffer, old_buffer);
449 path_put(&old_path);
450
451 return error;
452 }
453
454 int aa_mount_change_type(struct aa_label *label, const struct path *path,
455 unsigned long flags)
456 {
457 struct aa_profile *profile;
458 char *buffer = NULL;
459 int error;
460
461 AA_BUG(!label);
462 AA_BUG(!path);
463
464 /* These are the flags allowed by do_change_type() */
465 flags &= (MS_REC | MS_SILENT | MS_SHARED | MS_PRIVATE | MS_SLAVE |
466 MS_UNBINDABLE);
467
468 get_buffers(buffer);
469 error = fn_for_each_confined(label, profile,
470 match_mnt(profile, path, buffer, NULL, NULL, NULL,
471 flags, NULL, false));
472 put_buffers(buffer);
473
474 return error;
475 }
476
477 int aa_move_mount(struct aa_label *label, const struct path *path,
478 const char *orig_name)
479 {
480 struct aa_profile *profile;
481 char *buffer = NULL, *old_buffer = NULL;
482 struct path old_path;
483 int error;
484
485 AA_BUG(!label);
486 AA_BUG(!path);
487
488 if (!orig_name || !*orig_name)
489 return -EINVAL;
490
491 error = kern_path(orig_name, LOOKUP_FOLLOW, &old_path);
492 if (error)
493 return error;
494
495 get_buffers(buffer, old_buffer);
496 error = fn_for_each_confined(label, profile,
497 match_mnt(profile, path, buffer, &old_path, old_buffer,
498 NULL, MS_MOVE, NULL, false));
499 put_buffers(buffer, old_buffer);
500 path_put(&old_path);
501
502 return error;
503 }
504
505 int aa_new_mount(struct aa_label *label, const char *dev_name,
506 const struct path *path, const char *type, unsigned long flags,
507 void *data)
508 {
509 struct aa_profile *profile;
510 char *buffer = NULL, *dev_buffer = NULL;
511 bool binary = true;
512 int error;
513 int requires_dev = 0;
514 struct path tmp_path, *dev_path = NULL;
515
516 AA_BUG(!label);
517 AA_BUG(!path);
518
519 if (type) {
520 struct file_system_type *fstype;
521
522 fstype = get_fs_type(type);
523 if (!fstype)
524 return -ENODEV;
525 binary = fstype->fs_flags & FS_BINARY_MOUNTDATA;
526 requires_dev = fstype->fs_flags & FS_REQUIRES_DEV;
527 put_filesystem(fstype);
528
529 if (requires_dev) {
530 if (!dev_name || !*dev_name)
531 return -ENOENT;
532
533 error = kern_path(dev_name, LOOKUP_FOLLOW, &tmp_path);
534 if (error)
535 return error;
536 dev_path = &tmp_path;
537 }
538 }
539
540 get_buffers(buffer, dev_buffer);
541 if (dev_path) {
542 error = fn_for_each_confined(label, profile,
543 match_mnt(profile, path, buffer, dev_path, dev_buffer,
544 type, flags, data, binary));
545 } else {
546 error = fn_for_each_confined(label, profile,
547 match_mnt_path_str(profile, path, buffer, dev_name,
548 type, flags, data, binary, NULL));
549 }
550 put_buffers(buffer, dev_buffer);
551 if (dev_path)
552 path_put(dev_path);
553
554 return error;
555 }
556
557 static int profile_umount(struct aa_profile *profile, struct path *path,
558 char *buffer)
559 {
560 struct aa_perms perms = { };
561 const char *name = NULL, *info = NULL;
562 unsigned int state;
563 int error;
564
565 AA_BUG(!profile);
566 AA_BUG(!path);
567
568 if (!PROFILE_MEDIATES(profile, AA_CLASS_MOUNT))
569 return 0;
570
571 error = aa_path_name(path, path_flags(profile, path), buffer, &name,
572 &info, profile->disconnected);
573 if (error)
574 goto audit;
575
576 state = aa_dfa_match(profile->policy.dfa,
577 profile->policy.start[AA_CLASS_MOUNT],
578 name);
579 perms = compute_mnt_perms(profile->policy.dfa, state);
580 if (AA_MAY_UMOUNT & ~perms.allow)
581 error = -EACCES;
582
583 audit:
584 return audit_mount(profile, OP_UMOUNT, name, NULL, NULL, NULL, 0, NULL,
585 AA_MAY_UMOUNT, &perms, info, error);
586 }
587
588 int aa_umount(struct aa_label *label, struct vfsmount *mnt, int flags)
589 {
590 struct aa_profile *profile;
591 char *buffer = NULL;
592 int error;
593 struct path path = { .mnt = mnt, .dentry = mnt->mnt_root };
594
595 AA_BUG(!label);
596 AA_BUG(!mnt);
597
598 get_buffers(buffer);
599 error = fn_for_each_confined(label, profile,
600 profile_umount(profile, &path, buffer));
601 put_buffers(buffer);
602
603 return error;
604 }
605
606 /* helper fn for transition on pivotroot
607 *
608 * Returns: label for transition or ERR_PTR. Does not return NULL
609 */
610 static struct aa_label *build_pivotroot(struct aa_profile *profile,
611 const struct path *new_path,
612 char *new_buffer,
613 const struct path *old_path,
614 char *old_buffer)
615 {
616 const char *old_name, *new_name = NULL, *info = NULL;
617 const char *trans_name = NULL;
618 struct aa_perms perms = { };
619 unsigned int state;
620 int error;
621
622 AA_BUG(!profile);
623 AA_BUG(!new_path);
624 AA_BUG(!old_path);
625
626 if (profile_unconfined(profile) ||
627 !PROFILE_MEDIATES(profile, AA_CLASS_MOUNT))
628 return aa_get_newest_label(&profile->label);
629
630 error = aa_path_name(old_path, path_flags(profile, old_path),
631 old_buffer, &old_name, &info,
632 profile->disconnected);
633 if (error)
634 goto audit;
635 error = aa_path_name(new_path, path_flags(profile, new_path),
636 new_buffer, &new_name, &info,
637 profile->disconnected);
638 if (error)
639 goto audit;
640
641 error = -EACCES;
642 state = aa_dfa_match(profile->policy.dfa,
643 profile->policy.start[AA_CLASS_MOUNT],
644 new_name);
645 state = aa_dfa_null_transition(profile->policy.dfa, state);
646 state = aa_dfa_match(profile->policy.dfa, state, old_name);
647 perms = compute_mnt_perms(profile->policy.dfa, state);
648
649 if (AA_MAY_PIVOTROOT & perms.allow)
650 error = 0;
651
652 audit:
653 error = audit_mount(profile, OP_PIVOTROOT, new_name, old_name,
654 NULL, trans_name, 0, NULL, AA_MAY_PIVOTROOT,
655 &perms, info, error);
656 if (error)
657 return ERR_PTR(error);
658
659 return aa_get_newest_label(&profile->label);
660 }
661
662 int aa_pivotroot(struct aa_label *label, const struct path *old_path,
663 const struct path *new_path)
664 {
665 struct aa_profile *profile;
666 struct aa_label *target = NULL;
667 char *old_buffer = NULL, *new_buffer = NULL, *info = NULL;
668 int error;
669
670 AA_BUG(!label);
671 AA_BUG(!old_path);
672 AA_BUG(!new_path);
673
674 get_buffers(old_buffer, new_buffer);
675 target = fn_label_build(label, profile, GFP_ATOMIC,
676 build_pivotroot(profile, new_path, new_buffer,
677 old_path, old_buffer));
678 if (!target) {
679 info = "label build failed";
680 error = -ENOMEM;
681 goto fail;
682 } else if (!IS_ERR(target)) {
683 error = aa_replace_current_label(target);
684 if (error) {
685 /* TODO: audit target */
686 aa_put_label(target);
687 goto out;
688 }
689 } else
690 /* already audited error */
691 error = PTR_ERR(target);
692 out:
693 put_buffers(old_buffer, new_buffer);
694
695 return error;
696
697 fail:
698 /* TODO: add back in auditing of new_name and old_name */
699 error = fn_for_each(label, profile,
700 audit_mount(profile, OP_PIVOTROOT, NULL /*new_name */,
701 NULL /* old_name */,
702 NULL, NULL,
703 0, NULL, AA_MAY_PIVOTROOT, &nullperms, info,
704 error));
705 goto out;
706 }