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_KERNEL);
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 :
335 buffer = aa_get_buffer(false);
338 error = fn_for_each_confined(label, profile,
339 profile_path_perm(op, profile, path, buffer, request,
340 cond, flags, &perms));
342 aa_put_buffer(buffer);
348 * xindex_is_subset - helper for aa_path_link
349 * @link: link permission set
350 * @target: target permission set
352 * test target x permissions are equal OR a subset of link x permissions
353 * this is done as part of the subset test, where a hardlink must have
354 * a subset of permissions that the target has.
356 * Returns: %1 if subset else %0
358 static inline bool xindex_is_subset(u32 link, u32 target)
360 if (((link & ~AA_X_UNSAFE) != (target & ~AA_X_UNSAFE)) ||
361 ((link & AA_X_UNSAFE) && !(target & AA_X_UNSAFE)))
367 static int profile_path_link(struct aa_profile *profile,
368 const struct path *link, char *buffer,
369 const struct path *target, char *buffer2,
370 struct path_cond *cond)
372 const char *lname, *tname = NULL;
373 struct aa_perms lperms = {}, perms;
374 const char *info = NULL;
375 u32 request = AA_MAY_LINK;
379 error = path_name(OP_LINK, &profile->label, link, profile->path_flags,
380 buffer, &lname, cond, AA_MAY_LINK);
384 /* buffer2 freed below, tname is pointer in buffer2 */
385 error = path_name(OP_LINK, &profile->label, target, profile->path_flags,
386 buffer2, &tname, cond, AA_MAY_LINK);
391 /* aa_str_perms - handles the case of the dfa being NULL */
392 state = aa_str_perms(profile->file.dfa, profile->file.start, lname,
395 if (!(lperms.allow & AA_MAY_LINK))
398 /* test to see if target can be paired with link */
399 state = aa_dfa_null_transition(profile->file.dfa, state);
400 aa_str_perms(profile->file.dfa, state, tname, cond, &perms);
402 /* force audit/quiet masks for link are stored in the second entry
405 lperms.audit = perms.audit;
406 lperms.quiet = perms.quiet;
407 lperms.kill = perms.kill;
409 if (!(perms.allow & AA_MAY_LINK)) {
410 info = "target restricted";
415 /* done if link subset test is not required */
416 if (!(perms.allow & AA_LINK_SUBSET))
419 /* Do link perm subset test requiring allowed permission on link are
420 * a subset of the allowed permissions on target.
422 aa_str_perms(profile->file.dfa, profile->file.start, tname, cond,
425 /* AA_MAY_LINK is not considered in the subset test */
426 request = lperms.allow & ~AA_MAY_LINK;
427 lperms.allow &= perms.allow | AA_MAY_LINK;
429 request |= AA_AUDIT_FILE_MASK & (lperms.allow & ~perms.allow);
430 if (request & ~lperms.allow) {
432 } else if ((lperms.allow & MAY_EXEC) &&
433 !xindex_is_subset(lperms.xindex, perms.xindex)) {
434 lperms.allow &= ~MAY_EXEC;
436 info = "link not subset of target";
444 return aa_audit_file(profile, &lperms, OP_LINK, request, lname, tname,
445 NULL, cond->uid, info, error);
449 * aa_path_link - Handle hard link permission check
450 * @label: the label being enforced (NOT NULL)
451 * @old_dentry: the target dentry (NOT NULL)
452 * @new_dir: directory the new link will be created in (NOT NULL)
453 * @new_dentry: the link being created (NOT NULL)
455 * Handle the permission test for a link & target pair. Permission
456 * is encoded as a pair where the link permission is determined
457 * first, and if allowed, the target is tested. The target test
458 * is done from the point of the link match (not start of DFA)
459 * making the target permission dependent on the link permission match.
461 * The subset test if required forces that permissions granted
462 * on link are a subset of the permission granted to target.
464 * Returns: %0 if allowed else error
466 int aa_path_link(struct aa_label *label, struct dentry *old_dentry,
467 const struct path *new_dir, struct dentry *new_dentry)
469 struct path link = { .mnt = new_dir->mnt, .dentry = new_dentry };
470 struct path target = { .mnt = new_dir->mnt, .dentry = old_dentry };
471 struct path_cond cond = {
472 d_backing_inode(old_dentry)->i_uid,
473 d_backing_inode(old_dentry)->i_mode
475 char *buffer = NULL, *buffer2 = NULL;
476 struct aa_profile *profile;
479 /* buffer freed below, lname is pointer in buffer */
480 buffer = aa_get_buffer(false);
481 buffer2 = aa_get_buffer(false);
483 if (!buffer || !buffer2)
486 error = fn_for_each_confined(label, profile,
487 profile_path_link(profile, &link, buffer, &target,
490 aa_put_buffer(buffer);
491 aa_put_buffer(buffer2);
495 static void update_file_ctx(struct aa_file_ctx *fctx, struct aa_label *label,
498 struct aa_label *l, *old;
500 /* update caching of label on file_ctx */
501 spin_lock(&fctx->lock);
502 old = rcu_dereference_protected(fctx->label,
503 lockdep_is_held(&fctx->lock));
504 l = aa_label_merge(old, label, GFP_ATOMIC);
507 rcu_assign_pointer(fctx->label, l);
511 fctx->allow |= request;
513 spin_unlock(&fctx->lock);
516 static int __file_path_perm(const char *op, struct aa_label *label,
517 struct aa_label *flabel, struct file *file,
518 u32 request, u32 denied, bool in_atomic)
520 struct aa_profile *profile;
521 struct aa_perms perms = {};
522 struct path_cond cond = {
523 .uid = file_inode(file)->i_uid,
524 .mode = file_inode(file)->i_mode
529 /* revalidation due to label out of date. No revocation at this time */
530 if (!denied && aa_label_is_subset(flabel, label))
531 /* TODO: check for revocation on stale profiles */
534 flags = PATH_DELEGATE_DELETED | (S_ISDIR(cond.mode) ? PATH_IS_DIR : 0);
535 buffer = aa_get_buffer(in_atomic);
539 /* check every profile in task label not in current cache */
540 error = fn_for_each_not_in_set(flabel, label, profile,
541 profile_path_perm(op, profile, &file->f_path, buffer,
542 request, &cond, flags, &perms));
543 if (denied && !error) {
545 * check every profile in file label that was not tested
546 * in the initial check above.
548 * TODO: cache full perms so this only happens because of
550 * TODO: don't audit here
553 error = fn_for_each(label, profile,
554 profile_path_perm(op, profile, &file->f_path,
555 buffer, request, &cond, flags,
558 error = fn_for_each_not_in_set(label, flabel, profile,
559 profile_path_perm(op, profile, &file->f_path,
560 buffer, request, &cond, flags,
564 update_file_ctx(file_ctx(file), label, request);
566 aa_put_buffer(buffer);
571 static int __file_sock_perm(const char *op, struct aa_label *label,
572 struct aa_label *flabel, struct file *file,
573 u32 request, u32 denied)
575 struct socket *sock = (struct socket *) file->private_data;
580 /* revalidation due to label out of date. No revocation at this time */
581 if (!denied && aa_label_is_subset(flabel, label))
584 /* TODO: improve to skip profiles cached in flabel */
585 error = aa_sock_file_perm(label, op, request, sock);
587 /* TODO: improve to skip profiles checked above */
588 /* check every profile in file label to is cached */
589 last_error(error, aa_sock_file_perm(flabel, op, request, sock));
592 update_file_ctx(file_ctx(file), label, request);
598 * aa_file_perm - do permission revalidation check & audit for @file
599 * @op: operation being checked
600 * @label: label being enforced (NOT NULL)
601 * @file: file to revalidate access permissions on (NOT NULL)
602 * @request: requested permissions
603 * @in_atomic: whether allocations need to be done in atomic context
605 * Returns: %0 if access allowed else error
607 int aa_file_perm(const char *op, struct aa_label *label, struct file *file,
608 u32 request, bool in_atomic)
610 struct aa_file_ctx *fctx;
611 struct aa_label *flabel;
618 fctx = file_ctx(file);
621 flabel = aa_get_newest_label(rcu_dereference(fctx->label));
625 /* revalidate access, if task is unconfined, or the cached cred
626 * doesn't match or if the request is for more permissions than
629 * Note: the test for !unconfined(flabel) is to handle file
630 * delegation from unconfined tasks
632 denied = request & ~fctx->allow;
633 if (unconfined(label) || unconfined(flabel) ||
634 (!denied && aa_label_is_subset(flabel, label)))
637 /* TODO: label cross check */
639 if (file->f_path.mnt && path_mediated_fs(file->f_path.dentry))
640 error = __file_path_perm(op, label, flabel, file, request,
643 else if (S_ISSOCK(file_inode(file)->i_mode))
644 error = __file_sock_perm(op, label, flabel, file, request,
647 aa_put_label(flabel);
651 static void revalidate_tty(struct aa_label *label)
653 struct tty_struct *tty;
656 tty = get_current_tty();
660 spin_lock(&tty->files_lock);
661 if (!list_empty(&tty->tty_files)) {
662 struct tty_file_private *file_priv;
664 /* TODO: Revalidate access to controlling tty. */
665 file_priv = list_first_entry(&tty->tty_files,
666 struct tty_file_private, list);
667 file = file_priv->file;
669 if (aa_file_perm(OP_INHERIT, label, file, MAY_READ | MAY_WRITE,
673 spin_unlock(&tty->files_lock);
680 static int match_file(const void *p, struct file *file, unsigned int fd)
682 struct aa_label *label = (struct aa_label *)p;
684 if (aa_file_perm(OP_INHERIT, label, file, aa_map_file_to_perms(file),
691 /* based on selinux's flush_unauthorized_files */
692 void aa_inherit_files(const struct cred *cred, struct files_struct *files)
694 struct aa_label *label = aa_get_newest_cred_label(cred);
695 struct file *devnull = NULL;
698 revalidate_tty(label);
700 /* Revalidate access to inherited open files. */
701 n = iterate_fd(files, 0, match_file, label);
702 if (!n) /* none found? */
705 devnull = dentry_open(&aa_null, O_RDWR, cred);
708 /* replace all the matching ones with this */
710 replace_fd(n - 1, devnull, 0);
711 } while ((n = iterate_fd(files, n, match_file, label)) != 0);