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 "include/apparmor.h"
16 #include "include/audit.h"
17 #include "include/file.h"
18 #include "include/match.h"
19 #include "include/path.h"
20 #include "include/policy.h"
22 struct file_perms nullperms;
26 * audit_file_mask - convert mask to permission string
27 * @buffer: buffer to write string to (NOT NULL)
28 * @mask: permission mask to convert
30 static void audit_file_mask(struct audit_buffer *ab, u32 mask)
36 if (mask & AA_EXEC_MMAP)
38 if (mask & (MAY_READ | AA_MAY_META_READ))
40 if (mask & (MAY_WRITE | AA_MAY_META_WRITE | AA_MAY_CHMOD |
43 else if (mask & MAY_APPEND)
45 if (mask & AA_MAY_CREATE)
47 if (mask & AA_MAY_DELETE)
49 if (mask & AA_MAY_LINK)
51 if (mask & AA_MAY_LOCK)
57 audit_log_string(ab, str);
61 * file_audit_cb - call back for file specific audit fields
62 * @ab: audit_buffer (NOT NULL)
63 * @va: audit struct to audit values of (NOT NULL)
65 static void file_audit_cb(struct audit_buffer *ab, void *va)
67 struct common_audit_data *sa = va;
68 uid_t fsuid = current_fsuid();
70 if (sa->aad.fs.request & AA_AUDIT_FILE_MASK) {
71 audit_log_format(ab, " requested_mask=");
72 audit_file_mask(ab, sa->aad.fs.request);
74 if (sa->aad.fs.denied & AA_AUDIT_FILE_MASK) {
75 audit_log_format(ab, " denied_mask=");
76 audit_file_mask(ab, sa->aad.fs.denied);
78 if (sa->aad.fs.request & AA_AUDIT_FILE_MASK) {
79 audit_log_format(ab, " fsuid=%d", fsuid);
80 audit_log_format(ab, " ouid=%d", sa->aad.fs.ouid);
83 if (sa->aad.fs.target) {
84 audit_log_format(ab, " target=");
85 audit_log_untrustedstring(ab, sa->aad.fs.target);
90 * aa_audit_file - handle the auditing of file operations
91 * @profile: the profile being enforced (NOT NULL)
92 * @perms: the permissions computed for the request (NOT NULL)
93 * @gfp: allocation flags
94 * @op: operation being mediated
95 * @request: permissions requested
96 * @name: name of object being mediated (MAYBE NULL)
97 * @target: name of target (MAYBE NULL)
99 * @info: extra information message (MAYBE NULL)
100 * @error: 0 if operation allowed else failure error code
102 * Returns: %0 or error on failure
104 int aa_audit_file(struct aa_profile *profile, struct file_perms *perms,
105 gfp_t gfp, int op, u32 request, const char *name,
106 const char *target, uid_t ouid, const char *info, int error)
108 int type = AUDIT_APPARMOR_AUTO;
109 struct common_audit_data sa;
110 COMMON_AUDIT_DATA_INIT(&sa, NONE);
112 sa.aad.fs.request = request;
114 sa.aad.fs.target = target;
115 sa.aad.fs.ouid = ouid;
117 sa.aad.error = error;
119 if (likely(!sa.aad.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 sa.aad.fs.request &= mask;
128 if (likely(!sa.aad.fs.request))
130 type = AUDIT_APPARMOR_AUDIT;
132 /* only report permissions that were denied */
133 sa.aad.fs.request = sa.aad.fs.request & ~perms->allow;
135 if (sa.aad.fs.request & perms->kill)
136 type = AUDIT_APPARMOR_KILL;
138 /* quiet known rejects, assumes quiet and kill do not overlap */
139 if ((sa.aad.fs.request & perms->quiet) &&
140 AUDIT_MODE(profile) != AUDIT_NOQUIET &&
141 AUDIT_MODE(profile) != AUDIT_ALL)
142 sa.aad.fs.request &= ~perms->quiet;
144 if (!sa.aad.fs.request)
145 return COMPLAIN_MODE(profile) ? 0 : sa.aad.error;
148 sa.aad.fs.denied = sa.aad.fs.request & ~perms->allow;
149 return aa_audit(type, profile, gfp, &sa, file_audit_cb);
153 * map_old_perms - map old file perms layout to the new layout
154 * @old: permission set in old mapping
156 * Returns: new permission mapping
158 static u32 map_old_perms(u32 old)
162 new |= AA_MAY_META_READ;
164 new |= AA_MAY_META_WRITE | AA_MAY_CREATE | AA_MAY_DELETE |
165 AA_MAY_CHMOD | AA_MAY_CHOWN;
168 /* the old mapping lock and link_subset flags where overlaid
169 * and use was determined by part of a pair that they were in
172 new |= AA_MAY_LOCK | AA_LINK_SUBSET;
173 if (old & 0x40) /* AA_EXEC_MMAP */
180 * compute_perms - convert dfa compressed perms to internal perms
181 * @dfa: dfa to compute perms for (NOT NULL)
182 * @state: state in dfa
183 * @cond: conditions to consider (NOT NULL)
185 * TODO: convert from dfa + state to permission entry, do computation conversion
188 * Returns: computed permission set
190 static struct file_perms compute_perms(struct aa_dfa *dfa, unsigned int state,
191 struct path_cond *cond)
193 struct file_perms perms;
195 /* FIXME: change over to new dfa format
196 * currently file perms are encoded in the dfa, new format
197 * splits the permissions from the dfa. This mapping can be
198 * done at profile load
202 if (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_META_READ;
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 file_perms *perms)
244 state = aa_dfa_match(dfa, start, name);
245 *perms = compute_perms(dfa, state, cond);
251 * is_deleted - test if a file has been completely unlinked
252 * @dentry: dentry of file to test for deletion (NOT NULL)
254 * Returns: %1 if deleted else %0
256 static inline bool is_deleted(struct dentry *dentry)
258 if (d_unlinked(dentry) && dentry->d_inode->i_nlink == 0)
264 * aa_path_perm - do permissions check & audit for @path
265 * @op: operation being checked
266 * @profile: profile being enforced (NOT NULL)
267 * @path: path to check permissions of (NOT NULL)
268 * @flags: any additional path flags beyond what the profile specifies
269 * @request: requested permissions
270 * @cond: conditional info for this request (NOT NULL)
272 * Returns: %0 else error if access denied or other error
274 int aa_path_perm(int op, struct aa_profile *profile, struct path *path,
275 int flags, u32 request, struct path_cond *cond)
278 struct file_perms perms = {};
279 const char *name, *info = NULL;
282 flags |= profile->path_flags | (S_ISDIR(cond->mode) ? PATH_IS_DIR : 0);
283 error = aa_path_name(path, flags, &buffer, &name, &info);
285 if (error == -ENOENT && is_deleted(path->dentry)) {
286 /* Access to open files that are deleted are
287 * give a pass (implicit delegation)
291 perms.allow = request;
294 aa_str_perms(profile->file.dfa, profile->file.start, name, cond,
296 if (request & ~perms.allow)
299 error = aa_audit_file(profile, &perms, GFP_KERNEL, op, request, name,
300 NULL, cond->uid, info, error);
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: %1 if subset else %0
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)))
327 * aa_path_link - Handle hard link permission check
328 * @profile: the profile being enforced (NOT NULL)
329 * @old_dentry: the target dentry (NOT NULL)
330 * @new_dir: directory the new link will be created in (NOT NULL)
331 * @new_dentry: the link being created (NOT NULL)
333 * Handle the permission test for a link & target pair. Permission
334 * is encoded as a pair where the link permission is determined
335 * first, and if allowed, the target is tested. The target test
336 * is done from the point of the link match (not start of DFA)
337 * making the target permission dependent on the link permission match.
339 * The subset test if required forces that permissions granted
340 * on link are a subset of the permission granted to target.
342 * Returns: %0 if allowed else error
344 int aa_path_link(struct aa_profile *profile, struct dentry *old_dentry,
345 struct path *new_dir, struct dentry *new_dentry)
347 struct path link = { new_dir->mnt, new_dentry };
348 struct path target = { new_dir->mnt, old_dentry };
349 struct path_cond cond = {
350 old_dentry->d_inode->i_uid,
351 old_dentry->d_inode->i_mode
353 char *buffer = NULL, *buffer2 = NULL;
354 const char *lname, *tname = NULL, *info = NULL;
355 struct file_perms lperms, perms;
356 u32 request = AA_MAY_LINK;
362 /* buffer freed below, lname is pointer in buffer */
363 error = aa_path_name(&link, profile->path_flags, &buffer, &lname,
368 /* buffer2 freed below, tname is pointer in buffer2 */
369 error = aa_path_name(&target, profile->path_flags, &buffer2, &tname,
375 /* aa_str_perms - handles the case of the dfa being NULL */
376 state = aa_str_perms(profile->file.dfa, profile->file.start, lname,
379 if (!(lperms.allow & AA_MAY_LINK))
382 /* test to see if target can be paired with link */
383 state = aa_dfa_null_transition(profile->file.dfa, state);
384 aa_str_perms(profile->file.dfa, state, tname, &cond, &perms);
386 /* force audit/quiet masks for link are stored in the second entry
389 lperms.audit = perms.audit;
390 lperms.quiet = perms.quiet;
391 lperms.kill = perms.kill;
393 if (!(perms.allow & AA_MAY_LINK)) {
394 info = "target restricted";
398 /* done if link subset test is not required */
399 if (!(perms.allow & AA_LINK_SUBSET))
402 /* Do link perm subset test requiring allowed permission on link are a
403 * subset of the allowed permissions on target.
405 aa_str_perms(profile->file.dfa, profile->file.start, tname, &cond,
408 /* AA_MAY_LINK is not considered in the subset test */
409 request = lperms.allow & ~AA_MAY_LINK;
410 lperms.allow &= perms.allow | AA_MAY_LINK;
412 request |= AA_AUDIT_FILE_MASK & (lperms.allow & ~perms.allow);
413 if (request & ~lperms.allow) {
415 } else if ((lperms.allow & MAY_EXEC) &&
416 !xindex_is_subset(lperms.xindex, perms.xindex)) {
417 lperms.allow &= ~MAY_EXEC;
419 info = "link not subset of target";
427 error = aa_audit_file(profile, &lperms, GFP_KERNEL, OP_LINK, request,
428 lname, tname, cond.uid, info, error);
436 * aa_file_perm - do permission revalidation check & audit for @file
437 * @op: operation being checked
438 * @profile: profile being enforced (NOT NULL)
439 * @file: file to revalidate access permissions on (NOT NULL)
440 * @request: requested permissions
442 * Returns: %0 if access allowed else error
444 int aa_file_perm(int op, struct aa_profile *profile, struct file *file,
447 struct path_cond cond = {
448 .uid = file->f_path.dentry->d_inode->i_uid,
449 .mode = file->f_path.dentry->d_inode->i_mode
452 return aa_path_perm(op, profile, &file->f_path, PATH_DELEGATE_DELETED,