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 <linux/mount.h>
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"
27 static u32 map_mask_to_chr_mask(u32 mask)
29 u32 m = mask & PERMS_CHRS_MASK;
31 if (mask & AA_MAY_GETATTR)
33 if (mask & (AA_MAY_SETATTR | AA_MAY_CHMOD | AA_MAY_CHOWN))
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)
44 static void file_audit_cb(struct audit_buffer *ab, void *va)
46 struct common_audit_data *sa = va;
47 struct apparmor_audit_data *ad = aad(sa);
48 kuid_t fsuid = ad->subj_cred ? ad->subj_cred->fsuid : current_fsuid();
51 if (ad->request & AA_AUDIT_FILE_MASK) {
52 aa_perm_mask_to_str(str, sizeof(str), aa_file_perm_chrs,
53 map_mask_to_chr_mask(ad->request));
54 audit_log_format(ab, " requested_mask=\"%s\"", str);
56 if (ad->denied & AA_AUDIT_FILE_MASK) {
57 aa_perm_mask_to_str(str, sizeof(str), aa_file_perm_chrs,
58 map_mask_to_chr_mask(ad->denied));
59 audit_log_format(ab, " denied_mask=\"%s\"", str);
61 if (ad->request & AA_AUDIT_FILE_MASK) {
62 audit_log_format(ab, " fsuid=%d",
63 from_kuid(&init_user_ns, fsuid));
64 audit_log_format(ab, " ouid=%d",
65 from_kuid(&init_user_ns, ad->fs.ouid));
69 audit_log_format(ab, " target=");
70 aa_label_xaudit(ab, labels_ns(ad->subj_label), ad->peer,
71 FLAG_VIEW_SUBNS, GFP_KERNEL);
72 } else if (ad->fs.target) {
73 audit_log_format(ab, " target=");
74 audit_log_untrustedstring(ab, ad->fs.target);
79 * aa_audit_file - handle the auditing of file operations
80 * @subj_cred: cred of the subject
81 * @profile: the profile being enforced (NOT NULL)
82 * @perms: the permissions computed for the request (NOT NULL)
83 * @op: operation being mediated
84 * @request: permissions requested
85 * @name: name of object being mediated (MAYBE NULL)
86 * @target: name of target (MAYBE NULL)
87 * @tlabel: target label (MAY BE NULL)
89 * @info: extra information message (MAYBE NULL)
90 * @error: 0 if operation allowed else failure error code
92 * Returns: %0 or error on failure
94 int aa_audit_file(const struct cred *subj_cred,
95 struct aa_profile *profile, struct aa_perms *perms,
96 const char *op, u32 request, const char *name,
97 const char *target, struct aa_label *tlabel,
98 kuid_t ouid, const char *info, int error)
100 int type = AUDIT_APPARMOR_AUTO;
101 DEFINE_AUDIT_DATA(ad, LSM_AUDIT_DATA_TASK, AA_CLASS_FILE, op);
103 ad.subj_cred = subj_cred;
104 ad.request = request;
106 ad.fs.target = target;
111 ad.common.u.tsk = NULL;
113 if (likely(!ad.error)) {
114 u32 mask = perms->audit;
116 if (unlikely(AUDIT_MODE(profile) == AUDIT_ALL))
119 /* mask off perms that are not being force audited */
122 if (likely(!ad.request))
124 type = AUDIT_APPARMOR_AUDIT;
126 /* only report permissions that were denied */
127 ad.request = ad.request & ~perms->allow;
130 if (ad.request & perms->kill)
131 type = AUDIT_APPARMOR_KILL;
133 /* quiet known rejects, assumes quiet and kill do not overlap */
134 if ((ad.request & perms->quiet) &&
135 AUDIT_MODE(profile) != AUDIT_NOQUIET &&
136 AUDIT_MODE(profile) != AUDIT_ALL)
137 ad.request &= ~perms->quiet;
143 ad.denied = ad.request & ~perms->allow;
144 return aa_audit(type, profile, &ad, file_audit_cb);
148 * is_deleted - test if a file has been completely unlinked
149 * @dentry: dentry of file to test for deletion (NOT NULL)
151 * Returns: true if deleted else false
153 static inline bool is_deleted(struct dentry *dentry)
155 if (d_unlinked(dentry) && d_backing_inode(dentry)->i_nlink == 0)
160 static int path_name(const char *op, const struct cred *subj_cred,
161 struct aa_label *label,
162 const struct path *path, int flags, char *buffer,
163 const char **name, struct path_cond *cond, u32 request)
165 struct aa_profile *profile;
166 const char *info = NULL;
169 error = aa_path_name(path, flags, buffer, name, &info,
170 labels_profile(label)->disconnected);
172 fn_for_each_confined(label, profile,
173 aa_audit_file(subj_cred,
174 profile, &nullperms, op, request, *name,
175 NULL, NULL, cond->uid, info, error));
182 struct aa_perms default_perms = {};
184 * aa_lookup_fperms - convert dfa compressed perms to internal perms
185 * @dfa: dfa to lookup perms for (NOT NULL)
186 * @state: state in dfa
187 * @cond: conditions to consider (NOT NULL)
189 * TODO: convert from dfa + state to permission entry
191 * Returns: a pointer to a file permission set
193 struct aa_perms *aa_lookup_fperms(struct aa_policydb *file_rules,
194 aa_state_t state, struct path_cond *cond)
196 unsigned int index = ACCEPT_TABLE(file_rules->dfa)[state];
198 if (!(file_rules->perms))
199 return &default_perms;
201 if (uid_eq(current_fsuid(), cond->uid))
202 return &(file_rules->perms[index]);
204 return &(file_rules->perms[index + 1]);
208 * aa_str_perms - find permission that match @name
209 * @dfa: to match against (MAYBE NULL)
210 * @state: state to start matching in
211 * @name: string to match against dfa (NOT NULL)
212 * @cond: conditions to consider for permission set computation (NOT NULL)
213 * @perms: Returns - the permissions found when matching @name
215 * Returns: the final state in @dfa when beginning @start and walking @name
217 aa_state_t aa_str_perms(struct aa_policydb *file_rules, aa_state_t start,
218 const char *name, struct path_cond *cond,
219 struct aa_perms *perms)
222 state = aa_dfa_match(file_rules->dfa, start, name);
223 *perms = *(aa_lookup_fperms(file_rules, state, cond));
228 static int __aa_path_perm(const char *op, const struct cred *subj_cred,
229 struct aa_profile *profile, const char *name,
230 u32 request, struct path_cond *cond, int flags,
231 struct aa_perms *perms)
233 struct aa_ruleset *rules = list_first_entry(&profile->rules,
234 typeof(*rules), list);
237 if (profile_unconfined(profile))
239 aa_str_perms(&(rules->file), rules->file.start[AA_CLASS_FILE],
241 if (request & ~perms->allow)
243 return aa_audit_file(subj_cred,
244 profile, perms, op, request, name, NULL, NULL,
249 static int profile_path_perm(const char *op, const struct cred *subj_cred,
250 struct aa_profile *profile,
251 const struct path *path, char *buffer, u32 request,
252 struct path_cond *cond, int flags,
253 struct aa_perms *perms)
258 if (profile_unconfined(profile))
261 error = path_name(op, subj_cred, &profile->label, path,
262 flags | profile->path_flags, buffer, &name, cond,
266 return __aa_path_perm(op, subj_cred, profile, name, request, cond,
271 * aa_path_perm - do permissions check & audit for @path
272 * @op: operation being checked
273 * @subj_cred: subject cred
274 * @label: profile being enforced (NOT NULL)
275 * @path: path to check permissions of (NOT NULL)
276 * @flags: any additional path flags beyond what the profile specifies
277 * @request: requested permissions
278 * @cond: conditional info for this request (NOT NULL)
280 * Returns: %0 else error if access denied or other error
282 int aa_path_perm(const char *op, const struct cred *subj_cred,
283 struct aa_label *label,
284 const struct path *path, int flags, u32 request,
285 struct path_cond *cond)
287 struct aa_perms perms = {};
288 struct aa_profile *profile;
292 flags |= PATH_DELEGATE_DELETED | (S_ISDIR(cond->mode) ? PATH_IS_DIR :
294 buffer = aa_get_buffer(false);
297 error = fn_for_each_confined(label, profile,
298 profile_path_perm(op, subj_cred, profile, path, buffer,
299 request, cond, flags, &perms));
301 aa_put_buffer(buffer);
307 * xindex_is_subset - helper for aa_path_link
308 * @link: link permission set
309 * @target: target permission set
311 * test target x permissions are equal OR a subset of link x permissions
312 * this is done as part of the subset test, where a hardlink must have
313 * a subset of permissions that the target has.
315 * Returns: true if subset else false
317 static inline bool xindex_is_subset(u32 link, u32 target)
319 if (((link & ~AA_X_UNSAFE) != (target & ~AA_X_UNSAFE)) ||
320 ((link & AA_X_UNSAFE) && !(target & AA_X_UNSAFE)))
326 static int profile_path_link(const struct cred *subj_cred,
327 struct aa_profile *profile,
328 const struct path *link, char *buffer,
329 const struct path *target, char *buffer2,
330 struct path_cond *cond)
332 struct aa_ruleset *rules = list_first_entry(&profile->rules,
333 typeof(*rules), list);
334 const char *lname, *tname = NULL;
335 struct aa_perms lperms = {}, perms;
336 const char *info = NULL;
337 u32 request = AA_MAY_LINK;
341 error = path_name(OP_LINK, subj_cred, &profile->label, link,
343 buffer, &lname, cond, AA_MAY_LINK);
347 /* buffer2 freed below, tname is pointer in buffer2 */
348 error = path_name(OP_LINK, subj_cred, &profile->label, target,
350 buffer2, &tname, cond, AA_MAY_LINK);
355 /* aa_str_perms - handles the case of the dfa being NULL */
356 state = aa_str_perms(&(rules->file),
357 rules->file.start[AA_CLASS_FILE], lname,
360 if (!(lperms.allow & AA_MAY_LINK))
363 /* test to see if target can be paired with link */
364 state = aa_dfa_null_transition(rules->file.dfa, state);
365 aa_str_perms(&(rules->file), state, tname, cond, &perms);
367 /* force audit/quiet masks for link are stored in the second entry
370 lperms.audit = perms.audit;
371 lperms.quiet = perms.quiet;
372 lperms.kill = perms.kill;
374 if (!(perms.allow & AA_MAY_LINK)) {
375 info = "target restricted";
380 /* done if link subset test is not required */
381 if (!(perms.allow & AA_LINK_SUBSET))
384 /* Do link perm subset test requiring allowed permission on link are
385 * a subset of the allowed permissions on target.
387 aa_str_perms(&(rules->file), rules->file.start[AA_CLASS_FILE],
388 tname, cond, &perms);
390 /* AA_MAY_LINK is not considered in the subset test */
391 request = lperms.allow & ~AA_MAY_LINK;
392 lperms.allow &= perms.allow | AA_MAY_LINK;
394 request |= AA_AUDIT_FILE_MASK & (lperms.allow & ~perms.allow);
395 if (request & ~lperms.allow) {
397 } else if ((lperms.allow & MAY_EXEC) &&
398 !xindex_is_subset(lperms.xindex, perms.xindex)) {
399 lperms.allow &= ~MAY_EXEC;
401 info = "link not subset of target";
409 return aa_audit_file(subj_cred,
410 profile, &lperms, OP_LINK, request, lname, tname,
411 NULL, cond->uid, info, error);
415 * aa_path_link - Handle hard link permission check
416 * @subj_cred: subject cred
417 * @label: the label being enforced (NOT NULL)
418 * @old_dentry: the target dentry (NOT NULL)
419 * @new_dir: directory the new link will be created in (NOT NULL)
420 * @new_dentry: the link being created (NOT NULL)
422 * Handle the permission test for a link & target pair. Permission
423 * is encoded as a pair where the link permission is determined
424 * first, and if allowed, the target is tested. The target test
425 * is done from the point of the link match (not start of DFA)
426 * making the target permission dependent on the link permission match.
428 * The subset test if required forces that permissions granted
429 * on link are a subset of the permission granted to target.
431 * Returns: %0 if allowed else error
433 int aa_path_link(const struct cred *subj_cred,
434 struct aa_label *label, struct dentry *old_dentry,
435 const struct path *new_dir, struct dentry *new_dentry)
437 struct path link = { .mnt = new_dir->mnt, .dentry = new_dentry };
438 struct path target = { .mnt = new_dir->mnt, .dentry = old_dentry };
439 struct path_cond cond = {
440 d_backing_inode(old_dentry)->i_uid,
441 d_backing_inode(old_dentry)->i_mode
443 char *buffer = NULL, *buffer2 = NULL;
444 struct aa_profile *profile;
447 /* buffer freed below, lname is pointer in buffer */
448 buffer = aa_get_buffer(false);
449 buffer2 = aa_get_buffer(false);
451 if (!buffer || !buffer2)
454 error = fn_for_each_confined(label, profile,
455 profile_path_link(subj_cred, profile, &link, buffer,
456 &target, buffer2, &cond));
458 aa_put_buffer(buffer);
459 aa_put_buffer(buffer2);
463 static void update_file_ctx(struct aa_file_ctx *fctx, struct aa_label *label,
466 struct aa_label *l, *old;
468 /* update caching of label on file_ctx */
469 spin_lock(&fctx->lock);
470 old = rcu_dereference_protected(fctx->label,
471 lockdep_is_held(&fctx->lock));
472 l = aa_label_merge(old, label, GFP_ATOMIC);
475 rcu_assign_pointer(fctx->label, l);
479 fctx->allow |= request;
481 spin_unlock(&fctx->lock);
484 static int __file_path_perm(const char *op, const struct cred *subj_cred,
485 struct aa_label *label,
486 struct aa_label *flabel, struct file *file,
487 u32 request, u32 denied, bool in_atomic)
489 struct aa_profile *profile;
490 struct aa_perms perms = {};
491 vfsuid_t vfsuid = i_uid_into_vfsuid(file_mnt_idmap(file),
493 struct path_cond cond = {
494 .uid = vfsuid_into_kuid(vfsuid),
495 .mode = file_inode(file)->i_mode
500 /* revalidation due to label out of date. No revocation at this time */
501 if (!denied && aa_label_is_subset(flabel, label))
502 /* TODO: check for revocation on stale profiles */
505 flags = PATH_DELEGATE_DELETED | (S_ISDIR(cond.mode) ? PATH_IS_DIR : 0);
506 buffer = aa_get_buffer(in_atomic);
510 /* check every profile in task label not in current cache */
511 error = fn_for_each_not_in_set(flabel, label, profile,
512 profile_path_perm(op, subj_cred, profile,
513 &file->f_path, buffer,
514 request, &cond, flags, &perms));
515 if (denied && !error) {
517 * check every profile in file label that was not tested
518 * in the initial check above.
520 * TODO: cache full perms so this only happens because of
522 * TODO: don't audit here
525 error = fn_for_each(label, profile,
526 profile_path_perm(op, subj_cred,
527 profile, &file->f_path,
528 buffer, request, &cond, flags,
531 error = fn_for_each_not_in_set(label, flabel, profile,
532 profile_path_perm(op, subj_cred,
533 profile, &file->f_path,
534 buffer, request, &cond, flags,
538 update_file_ctx(file_ctx(file), label, request);
540 aa_put_buffer(buffer);
545 static int __file_sock_perm(const char *op, const struct cred *subj_cred,
546 struct aa_label *label,
547 struct aa_label *flabel, struct file *file,
548 u32 request, u32 denied)
550 struct socket *sock = (struct socket *) file->private_data;
555 /* revalidation due to label out of date. No revocation at this time */
556 if (!denied && aa_label_is_subset(flabel, label))
559 /* TODO: improve to skip profiles cached in flabel */
560 error = aa_sock_file_perm(subj_cred, label, op, request, sock);
562 /* TODO: improve to skip profiles checked above */
563 /* check every profile in file label to is cached */
564 last_error(error, aa_sock_file_perm(subj_cred, flabel, op,
568 update_file_ctx(file_ctx(file), label, request);
574 * aa_file_perm - do permission revalidation check & audit for @file
575 * @op: operation being checked
576 * @subj_cred: subject cred
577 * @label: label being enforced (NOT NULL)
578 * @file: file to revalidate access permissions on (NOT NULL)
579 * @request: requested permissions
580 * @in_atomic: whether allocations need to be done in atomic context
582 * Returns: %0 if access allowed else error
584 int aa_file_perm(const char *op, const struct cred *subj_cred,
585 struct aa_label *label, struct file *file,
586 u32 request, bool in_atomic)
588 struct aa_file_ctx *fctx;
589 struct aa_label *flabel;
596 fctx = file_ctx(file);
599 flabel = rcu_dereference(fctx->label);
602 /* revalidate access, if task is unconfined, or the cached cred
603 * doesn't match or if the request is for more permissions than
606 * Note: the test for !unconfined(flabel) is to handle file
607 * delegation from unconfined tasks
609 denied = request & ~fctx->allow;
610 if (unconfined(label) || unconfined(flabel) ||
611 (!denied && aa_label_is_subset(flabel, label))) {
616 flabel = aa_get_newest_label(flabel);
618 /* TODO: label cross check */
620 if (file->f_path.mnt && path_mediated_fs(file->f_path.dentry))
621 error = __file_path_perm(op, subj_cred, label, flabel, file,
622 request, denied, in_atomic);
624 else if (S_ISSOCK(file_inode(file)->i_mode))
625 error = __file_sock_perm(op, subj_cred, label, flabel, file,
627 aa_put_label(flabel);
633 static void revalidate_tty(const struct cred *subj_cred, struct aa_label *label)
635 struct tty_struct *tty;
638 tty = get_current_tty();
642 spin_lock(&tty->files_lock);
643 if (!list_empty(&tty->tty_files)) {
644 struct tty_file_private *file_priv;
646 /* TODO: Revalidate access to controlling tty. */
647 file_priv = list_first_entry(&tty->tty_files,
648 struct tty_file_private, list);
649 file = file_priv->file;
651 if (aa_file_perm(OP_INHERIT, subj_cred, label, file,
652 MAY_READ | MAY_WRITE, IN_ATOMIC))
655 spin_unlock(&tty->files_lock);
663 const struct cred *cred;
664 struct aa_label *label;
667 static int match_file(const void *p, struct file *file, unsigned int fd)
669 struct cred_label *cl = (struct cred_label *)p;
671 if (aa_file_perm(OP_INHERIT, cl->cred, cl->label, file,
672 aa_map_file_to_perms(file), IN_ATOMIC))
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 cred_label cl = {
686 struct file *devnull = NULL;
689 revalidate_tty(cred, label);
691 /* Revalidate access to inherited open files. */
692 n = iterate_fd(files, 0, match_file, &cl);
693 if (!n) /* none found? */
696 devnull = dentry_open(&aa_null, O_RDWR, cred);
699 /* replace all the matching ones with this */
701 replace_fd(n - 1, devnull, 0);
702 } while ((n = iterate_fd(files, n, match_file, &cl)) != 0);