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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 2009-2017 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/cred.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
30static 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 */
89static 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 */
133static 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 */
196static 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 */
216static struct aa_perms compute_mnt_perms(struct aa_dfa *dfa,
217 unsigned int state)
218{
219 struct aa_perms perms = {
220 .allow = dfa_user_allow(dfa, state),
221 .audit = dfa_user_audit(dfa, state),
222 .quiet = dfa_user_quiet(dfa, state),
223 .xindex = dfa_user_xindex(dfa, state),
224 };
225
226 return perms;
227}
228
229static const char * const mnt_info_table[] = {
230 "match succeeded",
231 "failed mntpnt match",
232 "failed srcname match",
233 "failed type match",
234 "failed flags match",
235 "failed data match"
236};
237
238/*
239 * Returns 0 on success else element that match failed in, this is the
240 * index into the mnt_info_table above
241 */
242static int do_match_mnt(struct aa_dfa *dfa, unsigned int start,
243 const char *mntpnt, const char *devname,
244 const char *type, unsigned long flags,
245 void *data, bool binary, struct aa_perms *perms)
246{
247 unsigned int state;
248
249 AA_BUG(!dfa);
250 AA_BUG(!perms);
251
252 state = aa_dfa_match(dfa, start, mntpnt);
253 state = aa_dfa_null_transition(dfa, state);
254 if (!state)
255 return 1;
256
257 if (devname)
258 state = aa_dfa_match(dfa, state, devname);
259 state = aa_dfa_null_transition(dfa, state);
260 if (!state)
261 return 2;
262
263 if (type)
264 state = aa_dfa_match(dfa, state, type);
265 state = aa_dfa_null_transition(dfa, state);
266 if (!state)
267 return 3;
268
269 state = match_mnt_flags(dfa, state, flags);
270 if (!state)
271 return 4;
272 *perms = compute_mnt_perms(dfa, state);
273 if (perms->allow & AA_MAY_MOUNT)
274 return 0;
275
276 /* only match data if not binary and the DFA flags data is expected */
277 if (data && !binary && (perms->allow & AA_MNT_CONT_MATCH)) {
278 state = aa_dfa_null_transition(dfa, state);
279 if (!state)
280 return 4;
281
282 state = aa_dfa_match(dfa, state, data);
283 if (!state)
284 return 5;
285 *perms = compute_mnt_perms(dfa, state);
286 if (perms->allow & AA_MAY_MOUNT)
287 return 0;
288 }
289
290 /* failed at end of flags match */
291 return 4;
292}
293
294
295static int path_flags(struct aa_profile *profile, const struct path *path)
296{
297 AA_BUG(!profile);
298 AA_BUG(!path);
299
300 return profile->path_flags |
301 (S_ISDIR(path->dentry->d_inode->i_mode) ? PATH_IS_DIR : 0);
302}
303
304/**
305 * match_mnt_path_str - handle path matching for mount
306 * @profile: the confining profile
307 * @mntpath: for the mntpnt (NOT NULL)
308 * @buffer: buffer to be used to lookup mntpath
309 * @devnme: string for the devname/src_name (MAY BE NULL OR ERRPTR)
310 * @type: string for the dev type (MAYBE NULL)
311 * @flags: mount flags to match
312 * @data: fs mount data (MAYBE NULL)
313 * @binary: whether @data is binary
314 * @devinfo: error str if (IS_ERR(@devname))
315 *
316 * Returns: 0 on success else error
317 */
318static int match_mnt_path_str(struct aa_profile *profile,
319 const struct path *mntpath, char *buffer,
320 const char *devname, const char *type,
321 unsigned long flags, void *data, bool binary,
322 const char *devinfo)
323{
324 struct aa_perms perms = { };
325 const char *mntpnt = NULL, *info = NULL;
326 int pos, error;
327
328 AA_BUG(!profile);
329 AA_BUG(!mntpath);
330 AA_BUG(!buffer);
331
332 if (!PROFILE_MEDIATES(profile, AA_CLASS_MOUNT))
333 return 0;
334
335 error = aa_path_name(mntpath, path_flags(profile, mntpath), buffer,
336 &mntpnt, &info, profile->disconnected);
337 if (error)
338 goto audit;
339 if (IS_ERR(devname)) {
340 error = PTR_ERR(devname);
341 devname = NULL;
342 info = devinfo;
343 goto audit;
344 }
345
346 error = -EACCES;
347 pos = do_match_mnt(profile->policy.dfa,
348 profile->policy.start[AA_CLASS_MOUNT],
349 mntpnt, devname, type, flags, data, binary, &perms);
350 if (pos) {
351 info = mnt_info_table[pos];
352 goto audit;
353 }
354 error = 0;
355
356audit:
357 return audit_mount(profile, OP_MOUNT, mntpnt, devname, type, NULL,
358 flags, data, AA_MAY_MOUNT, &perms, info, error);
359}
360
361/**
362 * match_mnt - handle path matching for mount
363 * @profile: the confining profile
364 * @mntpath: for the mntpnt (NOT NULL)
365 * @buffer: buffer to be used to lookup mntpath
366 * @devpath: path devname/src_name (MAYBE NULL)
367 * @devbuffer: buffer to be used to lookup devname/src_name
368 * @type: string for the dev type (MAYBE NULL)
369 * @flags: mount flags to match
370 * @data: fs mount data (MAYBE NULL)
371 * @binary: whether @data is binary
372 *
373 * Returns: 0 on success else error
374 */
375static int match_mnt(struct aa_profile *profile, const struct path *path,
376 char *buffer, struct path *devpath, char *devbuffer,
377 const char *type, unsigned long flags, void *data,
378 bool binary)
379{
380 const char *devname = NULL, *info = NULL;
381 int error = -EACCES;
382
383 AA_BUG(!profile);
384 AA_BUG(devpath && !devbuffer);
385
386 if (!PROFILE_MEDIATES(profile, AA_CLASS_MOUNT))
387 return 0;
388
389 if (devpath) {
390 error = aa_path_name(devpath, path_flags(profile, devpath),
391 devbuffer, &devname, &info,
392 profile->disconnected);
393 if (error)
394 devname = ERR_PTR(error);
395 }
396
397 return match_mnt_path_str(profile, path, buffer, devname, type, flags,
398 data, binary, info);
399}
400
401int aa_remount(struct aa_label *label, const struct path *path,
402 unsigned long flags, void *data)
403{
404 struct aa_profile *profile;
405 char *buffer = NULL;
406 bool binary;
407 int error;
408
409 AA_BUG(!label);
410 AA_BUG(!path);
411
412 binary = path->dentry->d_sb->s_type->fs_flags & FS_BINARY_MOUNTDATA;
413
414 get_buffers(buffer);
415 error = fn_for_each_confined(label, profile,
416 match_mnt(profile, path, buffer, NULL, NULL, NULL,
417 flags, data, binary));
418 put_buffers(buffer);
419
420 return error;
421}
422
423int aa_bind_mount(struct aa_label *label, const struct path *path,
424 const char *dev_name, unsigned long flags)
425{
426 struct aa_profile *profile;
427 char *buffer = NULL, *old_buffer = NULL;
428 struct path old_path;
429 int error;
430
431 AA_BUG(!label);
432 AA_BUG(!path);
433
434 if (!dev_name || !*dev_name)
435 return -EINVAL;
436
437 flags &= MS_REC | MS_BIND;
438
439 error = kern_path(dev_name, LOOKUP_FOLLOW|LOOKUP_AUTOMOUNT, &old_path);
440 if (error)
441 return error;
442
443 get_buffers(buffer, old_buffer);
444 error = fn_for_each_confined(label, profile,
445 match_mnt(profile, path, buffer, &old_path, old_buffer,
446 NULL, flags, NULL, false));
447 put_buffers(buffer, old_buffer);
448 path_put(&old_path);
449
450 return error;
451}
452
453int aa_mount_change_type(struct aa_label *label, const struct path *path,
454 unsigned long flags)
455{
456 struct aa_profile *profile;
457 char *buffer = NULL;
458 int error;
459
460 AA_BUG(!label);
461 AA_BUG(!path);
462
463 /* These are the flags allowed by do_change_type() */
464 flags &= (MS_REC | MS_SILENT | MS_SHARED | MS_PRIVATE | MS_SLAVE |
465 MS_UNBINDABLE);
466
467 get_buffers(buffer);
468 error = fn_for_each_confined(label, profile,
469 match_mnt(profile, path, buffer, NULL, NULL, NULL,
470 flags, NULL, false));
471 put_buffers(buffer);
472
473 return error;
474}
475
476int aa_move_mount(struct aa_label *label, const struct path *path,
477 const char *orig_name)
478{
479 struct aa_profile *profile;
480 char *buffer = NULL, *old_buffer = NULL;
481 struct path old_path;
482 int error;
483
484 AA_BUG(!label);
485 AA_BUG(!path);
486
487 if (!orig_name || !*orig_name)
488 return -EINVAL;
489
490 error = kern_path(orig_name, LOOKUP_FOLLOW, &old_path);
491 if (error)
492 return error;
493
494 get_buffers(buffer, old_buffer);
495 error = fn_for_each_confined(label, profile,
496 match_mnt(profile, path, buffer, &old_path, old_buffer,
497 NULL, MS_MOVE, NULL, false));
498 put_buffers(buffer, old_buffer);
499 path_put(&old_path);
500
501 return error;
502}
503
504int aa_new_mount(struct aa_label *label, const char *dev_name,
505 const struct path *path, const char *type, unsigned long flags,
506 void *data)
507{
508 struct aa_profile *profile;
509 char *buffer = NULL, *dev_buffer = NULL;
510 bool binary = true;
511 int error;
512 int requires_dev = 0;
513 struct path tmp_path, *dev_path = NULL;
514
515 AA_BUG(!label);
516 AA_BUG(!path);
517
518 if (type) {
519 struct file_system_type *fstype;
520
521 fstype = get_fs_type(type);
522 if (!fstype)
523 return -ENODEV;
524 binary = fstype->fs_flags & FS_BINARY_MOUNTDATA;
525 requires_dev = fstype->fs_flags & FS_REQUIRES_DEV;
526 put_filesystem(fstype);
527
528 if (requires_dev) {
529 if (!dev_name || !*dev_name)
530 return -ENOENT;
531
532 error = kern_path(dev_name, LOOKUP_FOLLOW, &tmp_path);
533 if (error)
534 return error;
535 dev_path = &tmp_path;
536 }
537 }
538
539 get_buffers(buffer, dev_buffer);
540 if (dev_path) {
541 error = fn_for_each_confined(label, profile,
542 match_mnt(profile, path, buffer, dev_path, dev_buffer,
543 type, flags, data, binary));
544 } else {
545 error = fn_for_each_confined(label, profile,
546 match_mnt_path_str(profile, path, buffer, dev_name,
547 type, flags, data, binary, NULL));
548 }
549 put_buffers(buffer, dev_buffer);
550 if (dev_path)
551 path_put(dev_path);
552
553 return error;
554}
555
556static int profile_umount(struct aa_profile *profile, struct path *path,
557 char *buffer)
558{
559 struct aa_perms perms = { };
560 const char *name = NULL, *info = NULL;
561 unsigned int state;
562 int error;
563
564 AA_BUG(!profile);
565 AA_BUG(!path);
566
567 if (!PROFILE_MEDIATES(profile, AA_CLASS_MOUNT))
568 return 0;
569
570 error = aa_path_name(path, path_flags(profile, path), buffer, &name,
571 &info, profile->disconnected);
572 if (error)
573 goto audit;
574
575 state = aa_dfa_match(profile->policy.dfa,
576 profile->policy.start[AA_CLASS_MOUNT],
577 name);
578 perms = compute_mnt_perms(profile->policy.dfa, state);
579 if (AA_MAY_UMOUNT & ~perms.allow)
580 error = -EACCES;
581
582audit:
583 return audit_mount(profile, OP_UMOUNT, name, NULL, NULL, NULL, 0, NULL,
584 AA_MAY_UMOUNT, &perms, info, error);
585}
586
587int aa_umount(struct aa_label *label, struct vfsmount *mnt, int flags)
588{
589 struct aa_profile *profile;
590 char *buffer = NULL;
591 int error;
592 struct path path = { .mnt = mnt, .dentry = mnt->mnt_root };
593
594 AA_BUG(!label);
595 AA_BUG(!mnt);
596
597 get_buffers(buffer);
598 error = fn_for_each_confined(label, profile,
599 profile_umount(profile, &path, buffer));
600 put_buffers(buffer);
601
602 return error;
603}
604
605/* helper fn for transition on pivotroot
606 *
607 * Returns: label for transition or ERR_PTR. Does not return NULL
608 */
609static struct aa_label *build_pivotroot(struct aa_profile *profile,
610 const struct path *new_path,
611 char *new_buffer,
612 const struct path *old_path,
613 char *old_buffer)
614{
615 const char *old_name, *new_name = NULL, *info = NULL;
616 const char *trans_name = NULL;
617 struct aa_perms perms = { };
618 unsigned int state;
619 int error;
620
621 AA_BUG(!profile);
622 AA_BUG(!new_path);
623 AA_BUG(!old_path);
624
625 if (profile_unconfined(profile) ||
626 !PROFILE_MEDIATES(profile, AA_CLASS_MOUNT))
627 return aa_get_newest_label(&profile->label);
628
629 error = aa_path_name(old_path, path_flags(profile, old_path),
630 old_buffer, &old_name, &info,
631 profile->disconnected);
632 if (error)
633 goto audit;
634 error = aa_path_name(new_path, path_flags(profile, new_path),
635 new_buffer, &new_name, &info,
636 profile->disconnected);
637 if (error)
638 goto audit;
639
640 error = -EACCES;
641 state = aa_dfa_match(profile->policy.dfa,
642 profile->policy.start[AA_CLASS_MOUNT],
643 new_name);
644 state = aa_dfa_null_transition(profile->policy.dfa, state);
645 state = aa_dfa_match(profile->policy.dfa, state, old_name);
646 perms = compute_mnt_perms(profile->policy.dfa, state);
647
648 if (AA_MAY_PIVOTROOT & perms.allow)
649 error = 0;
650
651audit:
652 error = audit_mount(profile, OP_PIVOTROOT, new_name, old_name,
653 NULL, trans_name, 0, NULL, AA_MAY_PIVOTROOT,
654 &perms, info, error);
655 if (error)
656 return ERR_PTR(error);
657
658 return aa_get_newest_label(&profile->label);
659}
660
661int aa_pivotroot(struct aa_label *label, const struct path *old_path,
662 const struct path *new_path)
663{
664 struct aa_profile *profile;
665 struct aa_label *target = NULL;
666 char *old_buffer = NULL, *new_buffer = NULL, *info = NULL;
667 int error;
668
669 AA_BUG(!label);
670 AA_BUG(!old_path);
671 AA_BUG(!new_path);
672
673 get_buffers(old_buffer, new_buffer);
674 target = fn_label_build(label, profile, GFP_ATOMIC,
675 build_pivotroot(profile, new_path, new_buffer,
676 old_path, old_buffer));
677 if (!target) {
678 info = "label build failed";
679 error = -ENOMEM;
680 goto fail;
681 } else if (!IS_ERR(target)) {
682 error = aa_replace_current_label(target);
683 if (error) {
684 /* TODO: audit target */
685 aa_put_label(target);
686 goto out;
687 }
688 } else
689 /* already audited error */
690 error = PTR_ERR(target);
691out:
692 put_buffers(old_buffer, new_buffer);
693
694 return error;
695
696fail:
697 /* TODO: add back in auditing of new_name and old_name */
698 error = fn_for_each(label, profile,
699 audit_mount(profile, OP_PIVOTROOT, NULL /*new_name */,
700 NULL /* old_name */,
701 NULL, NULL,
702 0, NULL, AA_MAY_PIVOTROOT, &nullperms, info,
703 error));
704 goto out;
705}