2 * AppArmor security module
4 * This file contains AppArmor mediation of files
6 * Copyright (C) 1998-2008 Novell/SUSE
7 * Copyright 2009-2010 Canonical Ltd.
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
15 #include <linux/tty.h>
16 #include <linux/fdtable.h>
17 #include <linux/file.h>
19 #include "include/apparmor.h"
20 #include "include/audit.h"
21 #include "include/context.h"
22 #include "include/file.h"
23 #include "include/match.h"
24 #include "include/path.h"
25 #include "include/policy.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 * audit_file_mask - convert mask to permission string
41 * @buffer: buffer to write string to (NOT NULL)
42 * @mask: permission mask to convert
44 static void audit_file_mask(struct audit_buffer *ab, u32 mask)
48 aa_perm_mask_to_str(str, aa_file_perm_chrs, map_mask_to_chr_mask(mask));
49 audit_log_string(ab, str);
53 * file_audit_cb - call back for file specific audit fields
54 * @ab: audit_buffer (NOT NULL)
55 * @va: audit struct to audit values of (NOT NULL)
57 static void file_audit_cb(struct audit_buffer *ab, void *va)
59 struct common_audit_data *sa = va;
60 kuid_t fsuid = current_fsuid();
62 if (aad(sa)->request & AA_AUDIT_FILE_MASK) {
63 audit_log_format(ab, " requested_mask=");
64 audit_file_mask(ab, aad(sa)->request);
66 if (aad(sa)->denied & AA_AUDIT_FILE_MASK) {
67 audit_log_format(ab, " denied_mask=");
68 audit_file_mask(ab, aad(sa)->denied);
70 if (aad(sa)->request & AA_AUDIT_FILE_MASK) {
71 audit_log_format(ab, " fsuid=%d",
72 from_kuid(&init_user_ns, fsuid));
73 audit_log_format(ab, " ouid=%d",
74 from_kuid(&init_user_ns, aad(sa)->fs.ouid));
77 if (aad(sa)->fs.target) {
78 audit_log_format(ab, " target=");
79 audit_log_untrustedstring(ab, aad(sa)->fs.target);
84 * aa_audit_file - handle the auditing of file operations
85 * @profile: the profile being enforced (NOT NULL)
86 * @perms: the permissions computed for the request (NOT NULL)
87 * @gfp: allocation flags
88 * @op: operation being mediated
89 * @request: permissions requested
90 * @name: name of object being mediated (MAYBE NULL)
91 * @target: name of target (MAYBE NULL)
93 * @info: extra information message (MAYBE NULL)
94 * @error: 0 if operation allowed else failure error code
96 * Returns: %0 or error on failure
98 int aa_audit_file(struct aa_profile *profile, struct aa_perms *perms,
99 const char *op, u32 request, const char *name,
100 const char *target, kuid_t ouid, const char *info, int error)
102 int type = AUDIT_APPARMOR_AUTO;
103 DEFINE_AUDIT_DATA(sa, LSM_AUDIT_DATA_TASK, op);
106 aad(&sa)->request = request;
107 aad(&sa)->name = name;
108 aad(&sa)->fs.target = target;
109 aad(&sa)->fs.ouid = ouid;
110 aad(&sa)->info = info;
111 aad(&sa)->error = error;
114 if (likely(!aad(&sa)->error)) {
115 u32 mask = perms->audit;
117 if (unlikely(AUDIT_MODE(profile) == AUDIT_ALL))
120 /* mask off perms that are not being force audited */
121 aad(&sa)->request &= mask;
123 if (likely(!aad(&sa)->request))
125 type = AUDIT_APPARMOR_AUDIT;
127 /* only report permissions that were denied */
128 aad(&sa)->request = aad(&sa)->request & ~perms->allow;
129 AA_BUG(!aad(&sa)->request);
131 if (aad(&sa)->request & perms->kill)
132 type = AUDIT_APPARMOR_KILL;
134 /* quiet known rejects, assumes quiet and kill do not overlap */
135 if ((aad(&sa)->request & perms->quiet) &&
136 AUDIT_MODE(profile) != AUDIT_NOQUIET &&
137 AUDIT_MODE(profile) != AUDIT_ALL)
138 aad(&sa)->request &= ~perms->quiet;
140 if (!aad(&sa)->request)
141 return COMPLAIN_MODE(profile) ? 0 : aad(&sa)->error;
144 aad(&sa)->denied = aad(&sa)->request & ~perms->allow;
145 return aa_audit(type, profile, &sa, file_audit_cb);
149 * map_old_perms - map old file perms layout to the new layout
150 * @old: permission set in old mapping
152 * Returns: new permission mapping
154 static u32 map_old_perms(u32 old)
158 new |= AA_MAY_GETATTR | AA_MAY_OPEN;
160 new |= AA_MAY_SETATTR | AA_MAY_CREATE | AA_MAY_DELETE |
161 AA_MAY_CHMOD | AA_MAY_CHOWN | AA_MAY_OPEN;
164 /* the old mapping lock and link_subset flags where overlaid
165 * and use was determined by part of a pair that they were in
168 new |= AA_MAY_LOCK | AA_LINK_SUBSET;
169 if (old & 0x40) /* AA_EXEC_MMAP */
176 * aa_compute_fperms - convert dfa compressed perms to internal perms
177 * @dfa: dfa to compute perms for (NOT NULL)
178 * @state: state in dfa
179 * @cond: conditions to consider (NOT NULL)
181 * TODO: convert from dfa + state to permission entry, do computation conversion
184 * Returns: computed permission set
186 struct aa_perms aa_compute_fperms(struct aa_dfa *dfa, unsigned int state,
187 struct path_cond *cond)
189 struct aa_perms perms;
191 /* FIXME: change over to new dfa format
192 * currently file perms are encoded in the dfa, new format
193 * splits the permissions from the dfa. This mapping can be
194 * done at profile load
197 perms.kill = perms.stop = 0;
198 perms.complain = perms.cond = 0;
202 if (uid_eq(current_fsuid(), cond->uid)) {
203 perms.allow = map_old_perms(dfa_user_allow(dfa, state));
204 perms.audit = map_old_perms(dfa_user_audit(dfa, state));
205 perms.quiet = map_old_perms(dfa_user_quiet(dfa, state));
206 perms.xindex = dfa_user_xindex(dfa, state);
208 perms.allow = map_old_perms(dfa_other_allow(dfa, state));
209 perms.audit = map_old_perms(dfa_other_audit(dfa, state));
210 perms.quiet = map_old_perms(dfa_other_quiet(dfa, state));
211 perms.xindex = dfa_other_xindex(dfa, state);
213 perms.allow |= AA_MAY_GETATTR;
215 /* change_profile wasn't determined by ownership in old mapping */
216 if (ACCEPT_TABLE(dfa)[state] & 0x80000000)
217 perms.allow |= AA_MAY_CHANGE_PROFILE;
218 if (ACCEPT_TABLE(dfa)[state] & 0x40000000)
219 perms.allow |= AA_MAY_ONEXEC;
225 * aa_str_perms - find permission that match @name
226 * @dfa: to match against (MAYBE NULL)
227 * @state: state to start matching in
228 * @name: string to match against dfa (NOT NULL)
229 * @cond: conditions to consider for permission set computation (NOT NULL)
230 * @perms: Returns - the permissions found when matching @name
232 * Returns: the final state in @dfa when beginning @start and walking @name
234 unsigned int aa_str_perms(struct aa_dfa *dfa, unsigned int start,
235 const char *name, struct path_cond *cond,
236 struct aa_perms *perms)
239 state = aa_dfa_match(dfa, start, name);
240 *perms = aa_compute_fperms(dfa, state, cond);
246 * is_deleted - test if a file has been completely unlinked
247 * @dentry: dentry of file to test for deletion (NOT NULL)
249 * Returns: %1 if deleted else %0
251 static inline bool is_deleted(struct dentry *dentry)
253 if (d_unlinked(dentry) && d_backing_inode(dentry)->i_nlink == 0)
259 * aa_path_perm - do permissions check & audit for @path
260 * @op: operation being checked
261 * @profile: profile being enforced (NOT NULL)
262 * @path: path to check permissions of (NOT NULL)
263 * @flags: any additional path flags beyond what the profile specifies
264 * @request: requested permissions
265 * @cond: conditional info for this request (NOT NULL)
267 * Returns: %0 else error if access denied or other error
269 int aa_path_perm(const char *op, struct aa_profile *profile,
270 const struct path *path, int flags, u32 request,
271 struct path_cond *cond)
274 struct aa_perms perms = {};
275 const char *name, *info = NULL;
278 flags |= profile->path_flags | (S_ISDIR(cond->mode) ? PATH_IS_DIR : 0);
280 error = aa_path_name(path, flags, buffer, &name, &info,
281 profile->disconnected);
283 if (error == -ENOENT && is_deleted(path->dentry)) {
284 /* Access to open files that are deleted are
285 * give a pass (implicit delegation)
289 perms.allow = request;
292 aa_str_perms(profile->file.dfa, profile->file.start, name, cond,
294 if (request & ~perms.allow)
297 error = aa_audit_file(profile, &perms, op, request, name, NULL,
298 cond->uid, info, error);
305 * xindex_is_subset - helper for aa_path_link
306 * @link: link permission set
307 * @target: target permission set
309 * test target x permissions are equal OR a subset of link x permissions
310 * this is done as part of the subset test, where a hardlink must have
311 * a subset of permissions that the target has.
313 * Returns: %1 if subset else %0
315 static inline bool xindex_is_subset(u32 link, u32 target)
317 if (((link & ~AA_X_UNSAFE) != (target & ~AA_X_UNSAFE)) ||
318 ((link & AA_X_UNSAFE) && !(target & AA_X_UNSAFE)))
325 * aa_path_link - Handle hard link permission check
326 * @profile: the profile being enforced (NOT NULL)
327 * @old_dentry: the target dentry (NOT NULL)
328 * @new_dir: directory the new link will be created in (NOT NULL)
329 * @new_dentry: the link being created (NOT NULL)
331 * Handle the permission test for a link & target pair. Permission
332 * is encoded as a pair where the link permission is determined
333 * first, and if allowed, the target is tested. The target test
334 * is done from the point of the link match (not start of DFA)
335 * making the target permission dependent on the link permission match.
337 * The subset test if required forces that permissions granted
338 * on link are a subset of the permission granted to target.
340 * Returns: %0 if allowed else error
342 int aa_path_link(struct aa_profile *profile, struct dentry *old_dentry,
343 const struct path *new_dir, struct dentry *new_dentry)
345 struct path link = { .mnt = new_dir->mnt, .dentry = new_dentry };
346 struct path target = { .mnt = new_dir->mnt, .dentry = old_dentry };
347 struct path_cond cond = {
348 d_backing_inode(old_dentry)->i_uid,
349 d_backing_inode(old_dentry)->i_mode
351 char *buffer = NULL, *buffer2 = NULL;
352 const char *lname, *tname = NULL, *info = NULL;
353 struct aa_perms lperms, perms;
354 u32 request = AA_MAY_LINK;
358 get_buffers(buffer, buffer2);
361 /* buffer freed below, lname is pointer in buffer */
362 error = aa_path_name(&link, profile->path_flags, buffer, &lname,
363 &info, profile->disconnected);
367 /* buffer2 freed below, tname is pointer in buffer2 */
368 error = aa_path_name(&target, profile->path_flags, buffer2, &tname,
369 &info, profile->disconnected);
374 /* aa_str_perms - handles the case of the dfa being NULL */
375 state = aa_str_perms(profile->file.dfa, profile->file.start, lname,
378 if (!(lperms.allow & AA_MAY_LINK))
381 /* test to see if target can be paired with link */
382 state = aa_dfa_null_transition(profile->file.dfa, state);
383 aa_str_perms(profile->file.dfa, state, tname, &cond, &perms);
385 /* force audit/quiet masks for link are stored in the second entry
388 lperms.audit = perms.audit;
389 lperms.quiet = perms.quiet;
390 lperms.kill = perms.kill;
392 if (!(perms.allow & AA_MAY_LINK)) {
393 info = "target restricted";
397 /* done if link subset test is not required */
398 if (!(perms.allow & AA_LINK_SUBSET))
401 /* Do link perm subset test requiring allowed permission on link are a
402 * subset of the allowed permissions on target.
404 aa_str_perms(profile->file.dfa, profile->file.start, tname, &cond,
407 /* AA_MAY_LINK is not considered in the subset test */
408 request = lperms.allow & ~AA_MAY_LINK;
409 lperms.allow &= perms.allow | AA_MAY_LINK;
411 request |= AA_AUDIT_FILE_MASK & (lperms.allow & ~perms.allow);
412 if (request & ~lperms.allow) {
414 } else if ((lperms.allow & MAY_EXEC) &&
415 !xindex_is_subset(lperms.xindex, perms.xindex)) {
416 lperms.allow &= ~MAY_EXEC;
418 info = "link not subset of target";
426 error = aa_audit_file(profile, &lperms, OP_LINK, request,
427 lname, tname, cond.uid, info, error);
428 put_buffers(buffer, buffer2);
434 * aa_file_perm - do permission revalidation check & audit for @file
435 * @op: operation being checked
436 * @profile: profile being enforced (NOT NULL)
437 * @file: file to revalidate access permissions on (NOT NULL)
438 * @request: requested permissions
440 * Returns: %0 if access allowed else error
442 int aa_file_perm(const char *op, struct aa_profile *profile, struct file *file,
445 struct path_cond cond = {
446 .uid = file_inode(file)->i_uid,
447 .mode = file_inode(file)->i_mode
450 return aa_path_perm(op, profile, &file->f_path, PATH_DELEGATE_DELETED,
454 static void revalidate_tty(struct aa_label *label)
456 struct tty_struct *tty;
459 tty = get_current_tty();
463 spin_lock(&tty->files_lock);
464 if (!list_empty(&tty->tty_files)) {
465 struct tty_file_private *file_priv;
467 /* TODO: Revalidate access to controlling tty. */
468 file_priv = list_first_entry(&tty->tty_files,
469 struct tty_file_private, list);
470 file = file_priv->file;
472 if (aa_file_perm(OP_INHERIT, labels_profile(label), file,
473 MAY_READ | MAY_WRITE))
476 spin_unlock(&tty->files_lock);
483 static int match_file(const void *p, struct file *file, unsigned int fd)
485 struct aa_label *label = (struct aa_label *)p;
487 if (aa_file_perm(OP_INHERIT, labels_profile(label), file,
488 aa_map_file_to_perms(file)))
494 /* based on selinux's flush_unauthorized_files */
495 void aa_inherit_files(const struct cred *cred, struct files_struct *files)
497 struct aa_label *label = aa_get_newest_cred_label(cred);
498 struct file *devnull = NULL;
501 revalidate_tty(label);
503 /* Revalidate access to inherited open files. */
504 n = iterate_fd(files, 0, match_file, label);
505 if (!n) /* none found? */
508 devnull = dentry_open(&aa_null, O_RDWR, cred);
511 /* replace all the matching ones with this */
513 replace_fd(n - 1, devnull, 0);
514 } while ((n = iterate_fd(files, n, match_file, label)) != 0);