1 // SPDX-License-Identifier: GPL-2.0-only
3 * AppArmor security module
5 * This file contains AppArmor mediation of files
7 * Copyright (C) 1998-2008 Novell/SUSE
8 * Copyright 2009-2010 Canonical Ltd.
11 #include <linux/tty.h>
12 #include <linux/fdtable.h>
13 #include <linux/file.h>
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"
25 static u32 map_mask_to_chr_mask(u32 mask)
27 u32 m = mask & PERMS_CHRS_MASK;
29 if (mask & AA_MAY_GETATTR)
31 if (mask & (AA_MAY_SETATTR | AA_MAY_CHMOD | AA_MAY_CHOWN))
38 * audit_file_mask - convert mask to permission string
39 * @buffer: buffer to write string to (NOT NULL)
40 * @mask: permission mask to convert
42 static void audit_file_mask(struct audit_buffer *ab, u32 mask)
46 aa_perm_mask_to_str(str, sizeof(str), aa_file_perm_chrs,
47 map_mask_to_chr_mask(mask));
48 audit_log_string(ab, str);
52 * file_audit_cb - call back for file specific audit fields
53 * @ab: audit_buffer (NOT NULL)
54 * @va: audit struct to audit values of (NOT NULL)
56 static void file_audit_cb(struct audit_buffer *ab, void *va)
58 struct common_audit_data *sa = va;
59 kuid_t fsuid = current_fsuid();
61 if (aad(sa)->request & AA_AUDIT_FILE_MASK) {
62 audit_log_format(ab, " requested_mask=");
63 audit_file_mask(ab, aad(sa)->request);
65 if (aad(sa)->denied & AA_AUDIT_FILE_MASK) {
66 audit_log_format(ab, " denied_mask=");
67 audit_file_mask(ab, aad(sa)->denied);
69 if (aad(sa)->request & AA_AUDIT_FILE_MASK) {
70 audit_log_format(ab, " fsuid=%d",
71 from_kuid(&init_user_ns, fsuid));
72 audit_log_format(ab, " ouid=%d",
73 from_kuid(&init_user_ns, aad(sa)->fs.ouid));
77 audit_log_format(ab, " target=");
78 aa_label_xaudit(ab, labels_ns(aad(sa)->label), aad(sa)->peer,
79 FLAG_VIEW_SUBNS, GFP_ATOMIC);
80 } else if (aad(sa)->fs.target) {
81 audit_log_format(ab, " target=");
82 audit_log_untrustedstring(ab, aad(sa)->fs.target);
87 * aa_audit_file - handle the auditing of file operations
88 * @profile: the profile being enforced (NOT NULL)
89 * @perms: the permissions computed for the request (NOT NULL)
90 * @op: operation being mediated
91 * @request: permissions requested
92 * @name: name of object being mediated (MAYBE NULL)
93 * @target: name of target (MAYBE NULL)
94 * @tlabel: target label (MAY BE NULL)
96 * @info: extra information message (MAYBE NULL)
97 * @error: 0 if operation allowed else failure error code
99 * Returns: %0 or error on failure
101 int aa_audit_file(struct aa_profile *profile, struct aa_perms *perms,
102 const char *op, u32 request, const char *name,
103 const char *target, struct aa_label *tlabel,
104 kuid_t ouid, const char *info, int error)
106 int type = AUDIT_APPARMOR_AUTO;
107 DEFINE_AUDIT_DATA(sa, LSM_AUDIT_DATA_TASK, op);
110 aad(&sa)->request = request;
111 aad(&sa)->name = name;
112 aad(&sa)->fs.target = target;
113 aad(&sa)->peer = tlabel;
114 aad(&sa)->fs.ouid = ouid;
115 aad(&sa)->info = info;
116 aad(&sa)->error = error;
119 if (likely(!aad(&sa)->error)) {
120 u32 mask = perms->audit;
122 if (unlikely(AUDIT_MODE(profile) == AUDIT_ALL))
125 /* mask off perms that are not being force audited */
126 aad(&sa)->request &= mask;
128 if (likely(!aad(&sa)->request))
130 type = AUDIT_APPARMOR_AUDIT;
132 /* only report permissions that were denied */
133 aad(&sa)->request = aad(&sa)->request & ~perms->allow;
134 AA_BUG(!aad(&sa)->request);
136 if (aad(&sa)->request & perms->kill)
137 type = AUDIT_APPARMOR_KILL;
139 /* quiet known rejects, assumes quiet and kill do not overlap */
140 if ((aad(&sa)->request & perms->quiet) &&
141 AUDIT_MODE(profile) != AUDIT_NOQUIET &&
142 AUDIT_MODE(profile) != AUDIT_ALL)
143 aad(&sa)->request &= ~perms->quiet;
145 if (!aad(&sa)->request)
146 return aad(&sa)->error;
149 aad(&sa)->denied = aad(&sa)->request & ~perms->allow;
150 return aa_audit(type, profile, &sa, file_audit_cb);
154 * is_deleted - test if a file has been completely unlinked
155 * @dentry: dentry of file to test for deletion (NOT NULL)
157 * Returns: %1 if deleted else %0
159 static inline bool is_deleted(struct dentry *dentry)
161 if (d_unlinked(dentry) && d_backing_inode(dentry)->i_nlink == 0)
166 static int path_name(const char *op, struct aa_label *label,
167 const struct path *path, int flags, char *buffer,
168 const char **name, struct path_cond *cond, u32 request)
170 struct aa_profile *profile;
171 const char *info = NULL;
174 error = aa_path_name(path, flags, buffer, name, &info,
175 labels_profile(label)->disconnected);
177 fn_for_each_confined(label, profile,
178 aa_audit_file(profile, &nullperms, op, request, *name,
179 NULL, NULL, cond->uid, info, error));
187 * map_old_perms - map old file perms layout to the new layout
188 * @old: permission set in old mapping
190 * Returns: new permission mapping
192 static u32 map_old_perms(u32 old)
196 new |= AA_MAY_GETATTR | AA_MAY_OPEN;
198 new |= AA_MAY_SETATTR | AA_MAY_CREATE | AA_MAY_DELETE |
199 AA_MAY_CHMOD | AA_MAY_CHOWN | AA_MAY_OPEN;
202 /* the old mapping lock and link_subset flags where overlaid
203 * and use was determined by part of a pair that they were in
206 new |= AA_MAY_LOCK | AA_LINK_SUBSET;
207 if (old & 0x40) /* AA_EXEC_MMAP */
214 * aa_compute_fperms - convert dfa compressed perms to internal perms
215 * @dfa: dfa to compute perms for (NOT NULL)
216 * @state: state in dfa
217 * @cond: conditions to consider (NOT NULL)
219 * TODO: convert from dfa + state to permission entry, do computation conversion
222 * Returns: computed permission set
224 struct aa_perms aa_compute_fperms(struct aa_dfa *dfa, unsigned int state,
225 struct path_cond *cond)
227 /* FIXME: change over to new dfa format
228 * currently file perms are encoded in the dfa, new format
229 * splits the permissions from the dfa. This mapping can be
230 * done at profile load
232 struct aa_perms perms = { };
234 if (uid_eq(current_fsuid(), cond->uid)) {
235 perms.allow = map_old_perms(dfa_user_allow(dfa, state));
236 perms.audit = map_old_perms(dfa_user_audit(dfa, state));
237 perms.quiet = map_old_perms(dfa_user_quiet(dfa, state));
238 perms.xindex = dfa_user_xindex(dfa, state);
240 perms.allow = map_old_perms(dfa_other_allow(dfa, state));
241 perms.audit = map_old_perms(dfa_other_audit(dfa, state));
242 perms.quiet = map_old_perms(dfa_other_quiet(dfa, state));
243 perms.xindex = dfa_other_xindex(dfa, state);
245 perms.allow |= AA_MAY_GETATTR;
247 /* change_profile wasn't determined by ownership in old mapping */
248 if (ACCEPT_TABLE(dfa)[state] & 0x80000000)
249 perms.allow |= AA_MAY_CHANGE_PROFILE;
250 if (ACCEPT_TABLE(dfa)[state] & 0x40000000)
251 perms.allow |= AA_MAY_ONEXEC;
257 * aa_str_perms - find permission that match @name
258 * @dfa: to match against (MAYBE NULL)
259 * @state: state to start matching in
260 * @name: string to match against dfa (NOT NULL)
261 * @cond: conditions to consider for permission set computation (NOT NULL)
262 * @perms: Returns - the permissions found when matching @name
264 * Returns: the final state in @dfa when beginning @start and walking @name
266 unsigned int aa_str_perms(struct aa_dfa *dfa, unsigned int start,
267 const char *name, struct path_cond *cond,
268 struct aa_perms *perms)
271 state = aa_dfa_match(dfa, start, name);
272 *perms = aa_compute_fperms(dfa, state, cond);
277 int __aa_path_perm(const char *op, struct aa_profile *profile, const char *name,
278 u32 request, struct path_cond *cond, int flags,
279 struct aa_perms *perms)
283 if (profile_unconfined(profile))
285 aa_str_perms(profile->file.dfa, profile->file.start, name, cond, perms);
286 if (request & ~perms->allow)
288 return aa_audit_file(profile, perms, op, request, name, NULL, NULL,
293 static int profile_path_perm(const char *op, struct aa_profile *profile,
294 const struct path *path, char *buffer, u32 request,
295 struct path_cond *cond, int flags,
296 struct aa_perms *perms)
301 if (profile_unconfined(profile))
304 error = path_name(op, &profile->label, path,
305 flags | profile->path_flags, buffer, &name, cond,
309 return __aa_path_perm(op, profile, name, request, cond, flags,
314 * aa_path_perm - do permissions check & audit for @path
315 * @op: operation being checked
316 * @label: profile being enforced (NOT NULL)
317 * @path: path to check permissions of (NOT NULL)
318 * @flags: any additional path flags beyond what the profile specifies
319 * @request: requested permissions
320 * @cond: conditional info for this request (NOT NULL)
322 * Returns: %0 else error if access denied or other error
324 int aa_path_perm(const char *op, struct aa_label *label,
325 const struct path *path, int flags, u32 request,
326 struct path_cond *cond)
328 struct aa_perms perms = {};
329 struct aa_profile *profile;
333 flags |= PATH_DELEGATE_DELETED | (S_ISDIR(cond->mode) ? PATH_IS_DIR :
336 error = fn_for_each_confined(label, profile,
337 profile_path_perm(op, profile, path, buffer, request,
338 cond, flags, &perms));
346 * xindex_is_subset - helper for aa_path_link
347 * @link: link permission set
348 * @target: target permission set
350 * test target x permissions are equal OR a subset of link x permissions
351 * this is done as part of the subset test, where a hardlink must have
352 * a subset of permissions that the target has.
354 * Returns: %1 if subset else %0
356 static inline bool xindex_is_subset(u32 link, u32 target)
358 if (((link & ~AA_X_UNSAFE) != (target & ~AA_X_UNSAFE)) ||
359 ((link & AA_X_UNSAFE) && !(target & AA_X_UNSAFE)))
365 static int profile_path_link(struct aa_profile *profile,
366 const struct path *link, char *buffer,
367 const struct path *target, char *buffer2,
368 struct path_cond *cond)
370 const char *lname, *tname = NULL;
371 struct aa_perms lperms = {}, perms;
372 const char *info = NULL;
373 u32 request = AA_MAY_LINK;
377 error = path_name(OP_LINK, &profile->label, link, profile->path_flags,
378 buffer, &lname, cond, AA_MAY_LINK);
382 /* buffer2 freed below, tname is pointer in buffer2 */
383 error = path_name(OP_LINK, &profile->label, target, profile->path_flags,
384 buffer2, &tname, cond, AA_MAY_LINK);
389 /* aa_str_perms - handles the case of the dfa being NULL */
390 state = aa_str_perms(profile->file.dfa, profile->file.start, lname,
393 if (!(lperms.allow & AA_MAY_LINK))
396 /* test to see if target can be paired with link */
397 state = aa_dfa_null_transition(profile->file.dfa, state);
398 aa_str_perms(profile->file.dfa, state, tname, cond, &perms);
400 /* force audit/quiet masks for link are stored in the second entry
403 lperms.audit = perms.audit;
404 lperms.quiet = perms.quiet;
405 lperms.kill = perms.kill;
407 if (!(perms.allow & AA_MAY_LINK)) {
408 info = "target restricted";
413 /* done if link subset test is not required */
414 if (!(perms.allow & AA_LINK_SUBSET))
417 /* Do link perm subset test requiring allowed permission on link are
418 * a subset of the allowed permissions on target.
420 aa_str_perms(profile->file.dfa, profile->file.start, tname, cond,
423 /* AA_MAY_LINK is not considered in the subset test */
424 request = lperms.allow & ~AA_MAY_LINK;
425 lperms.allow &= perms.allow | AA_MAY_LINK;
427 request |= AA_AUDIT_FILE_MASK & (lperms.allow & ~perms.allow);
428 if (request & ~lperms.allow) {
430 } else if ((lperms.allow & MAY_EXEC) &&
431 !xindex_is_subset(lperms.xindex, perms.xindex)) {
432 lperms.allow &= ~MAY_EXEC;
434 info = "link not subset of target";
442 return aa_audit_file(profile, &lperms, OP_LINK, request, lname, tname,
443 NULL, cond->uid, info, error);
447 * aa_path_link - Handle hard link permission check
448 * @label: the label being enforced (NOT NULL)
449 * @old_dentry: the target dentry (NOT NULL)
450 * @new_dir: directory the new link will be created in (NOT NULL)
451 * @new_dentry: the link being created (NOT NULL)
453 * Handle the permission test for a link & target pair. Permission
454 * is encoded as a pair where the link permission is determined
455 * first, and if allowed, the target is tested. The target test
456 * is done from the point of the link match (not start of DFA)
457 * making the target permission dependent on the link permission match.
459 * The subset test if required forces that permissions granted
460 * on link are a subset of the permission granted to target.
462 * Returns: %0 if allowed else error
464 int aa_path_link(struct aa_label *label, struct dentry *old_dentry,
465 const struct path *new_dir, struct dentry *new_dentry)
467 struct path link = { .mnt = new_dir->mnt, .dentry = new_dentry };
468 struct path target = { .mnt = new_dir->mnt, .dentry = old_dentry };
469 struct path_cond cond = {
470 d_backing_inode(old_dentry)->i_uid,
471 d_backing_inode(old_dentry)->i_mode
473 char *buffer = NULL, *buffer2 = NULL;
474 struct aa_profile *profile;
477 /* buffer freed below, lname is pointer in buffer */
478 get_buffers(buffer, buffer2);
479 error = fn_for_each_confined(label, profile,
480 profile_path_link(profile, &link, buffer, &target,
482 put_buffers(buffer, buffer2);
487 static void update_file_ctx(struct aa_file_ctx *fctx, struct aa_label *label,
490 struct aa_label *l, *old;
492 /* update caching of label on file_ctx */
493 spin_lock(&fctx->lock);
494 old = rcu_dereference_protected(fctx->label,
495 lockdep_is_held(&fctx->lock));
496 l = aa_label_merge(old, label, GFP_ATOMIC);
499 rcu_assign_pointer(fctx->label, l);
503 fctx->allow |= request;
505 spin_unlock(&fctx->lock);
508 static int __file_path_perm(const char *op, struct aa_label *label,
509 struct aa_label *flabel, struct file *file,
510 u32 request, u32 denied)
512 struct aa_profile *profile;
513 struct aa_perms perms = {};
514 struct path_cond cond = {
515 .uid = file_inode(file)->i_uid,
516 .mode = file_inode(file)->i_mode
521 /* revalidation due to label out of date. No revocation at this time */
522 if (!denied && aa_label_is_subset(flabel, label))
523 /* TODO: check for revocation on stale profiles */
526 flags = PATH_DELEGATE_DELETED | (S_ISDIR(cond.mode) ? PATH_IS_DIR : 0);
529 /* check every profile in task label not in current cache */
530 error = fn_for_each_not_in_set(flabel, label, profile,
531 profile_path_perm(op, profile, &file->f_path, buffer,
532 request, &cond, flags, &perms));
533 if (denied && !error) {
535 * check every profile in file label that was not tested
536 * in the initial check above.
538 * TODO: cache full perms so this only happens because of
540 * TODO: don't audit here
543 error = fn_for_each(label, profile,
544 profile_path_perm(op, profile, &file->f_path,
545 buffer, request, &cond, flags,
548 error = fn_for_each_not_in_set(label, flabel, profile,
549 profile_path_perm(op, profile, &file->f_path,
550 buffer, request, &cond, flags,
554 update_file_ctx(file_ctx(file), label, request);
561 static int __file_sock_perm(const char *op, struct aa_label *label,
562 struct aa_label *flabel, struct file *file,
563 u32 request, u32 denied)
565 struct socket *sock = (struct socket *) file->private_data;
570 /* revalidation due to label out of date. No revocation at this time */
571 if (!denied && aa_label_is_subset(flabel, label))
574 /* TODO: improve to skip profiles cached in flabel */
575 error = aa_sock_file_perm(label, op, request, sock);
577 /* TODO: improve to skip profiles checked above */
578 /* check every profile in file label to is cached */
579 last_error(error, aa_sock_file_perm(flabel, op, request, sock));
582 update_file_ctx(file_ctx(file), label, request);
588 * aa_file_perm - do permission revalidation check & audit for @file
589 * @op: operation being checked
590 * @label: label being enforced (NOT NULL)
591 * @file: file to revalidate access permissions on (NOT NULL)
592 * @request: requested permissions
594 * Returns: %0 if access allowed else error
596 int aa_file_perm(const char *op, struct aa_label *label, struct file *file,
599 struct aa_file_ctx *fctx;
600 struct aa_label *flabel;
607 fctx = file_ctx(file);
610 flabel = rcu_dereference(fctx->label);
613 /* revalidate access, if task is unconfined, or the cached cred
614 * doesn't match or if the request is for more permissions than
617 * Note: the test for !unconfined(flabel) is to handle file
618 * delegation from unconfined tasks
620 denied = request & ~fctx->allow;
621 if (unconfined(label) || unconfined(flabel) ||
622 (!denied && aa_label_is_subset(flabel, label)))
625 /* TODO: label cross check */
627 if (file->f_path.mnt && path_mediated_fs(file->f_path.dentry))
628 error = __file_path_perm(op, label, flabel, file, request,
631 else if (S_ISSOCK(file_inode(file)->i_mode))
632 error = __file_sock_perm(op, label, flabel, file, request,
640 static void revalidate_tty(struct aa_label *label)
642 struct tty_struct *tty;
645 tty = get_current_tty();
649 spin_lock(&tty->files_lock);
650 if (!list_empty(&tty->tty_files)) {
651 struct tty_file_private *file_priv;
653 /* TODO: Revalidate access to controlling tty. */
654 file_priv = list_first_entry(&tty->tty_files,
655 struct tty_file_private, list);
656 file = file_priv->file;
658 if (aa_file_perm(OP_INHERIT, label, file, MAY_READ | MAY_WRITE))
661 spin_unlock(&tty->files_lock);
668 static int match_file(const void *p, struct file *file, unsigned int fd)
670 struct aa_label *label = (struct aa_label *)p;
672 if (aa_file_perm(OP_INHERIT, label, file, aa_map_file_to_perms(file)))
678 /* based on selinux's flush_unauthorized_files */
679 void aa_inherit_files(const struct cred *cred, struct files_struct *files)
681 struct aa_label *label = aa_get_newest_cred_label(cred);
682 struct file *devnull = NULL;
685 revalidate_tty(label);
687 /* Revalidate access to inherited open files. */
688 n = iterate_fd(files, 0, match_file, label);
689 if (!n) /* none found? */
692 devnull = dentry_open(&aa_null, O_RDWR, cred);
695 /* replace all the matching ones with this */
697 replace_fd(n - 1, devnull, 0);
698 } while ((n = iterate_fd(files, n, match_file, label)) != 0);