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Thomas Gleixnerb886d83c2019-06-01 10:08:55 +02001// SPDX-License-Identifier: GPL-2.0-only
John Johansen6380bd82010-07-29 14:48:04 -07002/*
3 * AppArmor security module
4 *
5 * This file contains AppArmor mediation of files
6 *
7 * Copyright (C) 1998-2008 Novell/SUSE
8 * Copyright 2009-2010 Canonical Ltd.
John Johansen6380bd82010-07-29 14:48:04 -07009 */
10
John Johansen192ca6b2017-06-09 11:58:42 -070011#include <linux/tty.h>
12#include <linux/fdtable.h>
13#include <linux/file.h>
Christian Brauner3cee6072021-01-21 14:19:44 +010014#include <linux/fs.h>
15#include <linux/mount.h>
John Johansen192ca6b2017-06-09 11:58:42 -070016
John Johansen6380bd82010-07-29 14:48:04 -070017#include "include/apparmor.h"
18#include "include/audit.h"
John Johansend8889d42017-10-11 01:04:48 -070019#include "include/cred.h"
John Johansen6380bd82010-07-29 14:48:04 -070020#include "include/file.h"
21#include "include/match.h"
John Johansen56974a62017-07-18 23:18:33 -070022#include "include/net.h"
John Johansen6380bd82010-07-29 14:48:04 -070023#include "include/path.h"
24#include "include/policy.h"
John Johansen190a9512017-06-09 14:59:51 -070025#include "include/label.h"
John Johansen6380bd82010-07-29 14:48:04 -070026
John Johansene53cfe62017-05-26 15:07:22 -070027static u32 map_mask_to_chr_mask(u32 mask)
28{
29 u32 m = mask & PERMS_CHRS_MASK;
30
31 if (mask & AA_MAY_GETATTR)
32 m |= MAY_READ;
33 if (mask & (AA_MAY_SETATTR | AA_MAY_CHMOD | AA_MAY_CHOWN))
34 m |= MAY_WRITE;
35
36 return m;
37}
John Johansen6380bd82010-07-29 14:48:04 -070038
39/**
John Johansen6380bd82010-07-29 14:48:04 -070040 * 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)
43 */
44static void file_audit_cb(struct audit_buffer *ab, void *va)
45{
46 struct common_audit_data *sa = va;
Eric W. Biederman2db81452012-02-07 16:33:13 -080047 kuid_t fsuid = current_fsuid();
Richard Guy Briggsf1d9b232020-07-13 15:51:59 -040048 char str[10];
John Johansen6380bd82010-07-29 14:48:04 -070049
John Johansenaa9aeea2017-05-29 12:16:04 -070050 if (aad(sa)->request & AA_AUDIT_FILE_MASK) {
Richard Guy Briggsf1d9b232020-07-13 15:51:59 -040051 aa_perm_mask_to_str(str, sizeof(str), aa_file_perm_chrs,
52 map_mask_to_chr_mask(aad(sa)->request));
53 audit_log_format(ab, " requested_mask=\"%s\"", str);
John Johansen6380bd82010-07-29 14:48:04 -070054 }
John Johansenaa9aeea2017-05-29 12:16:04 -070055 if (aad(sa)->denied & AA_AUDIT_FILE_MASK) {
Richard Guy Briggsf1d9b232020-07-13 15:51:59 -040056 aa_perm_mask_to_str(str, sizeof(str), aa_file_perm_chrs,
57 map_mask_to_chr_mask(aad(sa)->denied));
58 audit_log_format(ab, " denied_mask=\"%s\"", str);
John Johansen6380bd82010-07-29 14:48:04 -070059 }
John Johansenaa9aeea2017-05-29 12:16:04 -070060 if (aad(sa)->request & AA_AUDIT_FILE_MASK) {
Eric W. Biederman2db81452012-02-07 16:33:13 -080061 audit_log_format(ab, " fsuid=%d",
62 from_kuid(&init_user_ns, fsuid));
63 audit_log_format(ab, " ouid=%d",
John Johansenef88a7a2017-01-16 00:43:02 -080064 from_kuid(&init_user_ns, aad(sa)->fs.ouid));
John Johansen6380bd82010-07-29 14:48:04 -070065 }
66
John Johansen98c3d182017-06-09 15:48:20 -070067 if (aad(sa)->peer) {
68 audit_log_format(ab, " target=");
69 aa_label_xaudit(ab, labels_ns(aad(sa)->label), aad(sa)->peer,
Sebastian Andrzej Siewior8ac2ca32019-04-05 15:34:58 +020070 FLAG_VIEW_SUBNS, GFP_KERNEL);
John Johansen98c3d182017-06-09 15:48:20 -070071 } else if (aad(sa)->fs.target) {
John Johansen6380bd82010-07-29 14:48:04 -070072 audit_log_format(ab, " target=");
John Johansenef88a7a2017-01-16 00:43:02 -080073 audit_log_untrustedstring(ab, aad(sa)->fs.target);
John Johansen6380bd82010-07-29 14:48:04 -070074 }
75}
76
77/**
78 * aa_audit_file - handle the auditing of file operations
79 * @profile: the profile being enforced (NOT NULL)
80 * @perms: the permissions computed for the request (NOT NULL)
John Johansen6380bd82010-07-29 14:48:04 -070081 * @op: operation being mediated
82 * @request: permissions requested
83 * @name: name of object being mediated (MAYBE NULL)
84 * @target: name of target (MAYBE NULL)
John Johansen98c3d182017-06-09 15:48:20 -070085 * @tlabel: target label (MAY BE NULL)
John Johansen6380bd82010-07-29 14:48:04 -070086 * @ouid: object uid
87 * @info: extra information message (MAYBE NULL)
88 * @error: 0 if operation allowed else failure error code
89 *
90 * Returns: %0 or error on failure
91 */
John Johansen2d679f32017-05-29 12:19:39 -070092int aa_audit_file(struct aa_profile *profile, struct aa_perms *perms,
John Johansenef88a7a2017-01-16 00:43:02 -080093 const char *op, u32 request, const char *name,
John Johansen98c3d182017-06-09 15:48:20 -070094 const char *target, struct aa_label *tlabel,
95 kuid_t ouid, const char *info, int error)
John Johansen6380bd82010-07-29 14:48:04 -070096{
97 int type = AUDIT_APPARMOR_AUTO;
John Johansenef88a7a2017-01-16 00:43:02 -080098 DEFINE_AUDIT_DATA(sa, LSM_AUDIT_DATA_TASK, op);
John Johansen6380bd82010-07-29 14:48:04 -070099
John Johansenef88a7a2017-01-16 00:43:02 -0800100 sa.u.tsk = NULL;
John Johansenaa9aeea2017-05-29 12:16:04 -0700101 aad(&sa)->request = request;
John Johansenef88a7a2017-01-16 00:43:02 -0800102 aad(&sa)->name = name;
103 aad(&sa)->fs.target = target;
John Johansen98c3d182017-06-09 15:48:20 -0700104 aad(&sa)->peer = tlabel;
John Johansenef88a7a2017-01-16 00:43:02 -0800105 aad(&sa)->fs.ouid = ouid;
106 aad(&sa)->info = info;
107 aad(&sa)->error = error;
108 sa.u.tsk = NULL;
109
110 if (likely(!aad(&sa)->error)) {
John Johansen6380bd82010-07-29 14:48:04 -0700111 u32 mask = perms->audit;
112
113 if (unlikely(AUDIT_MODE(profile) == AUDIT_ALL))
114 mask = 0xffff;
115
116 /* mask off perms that are not being force audited */
John Johansenaa9aeea2017-05-29 12:16:04 -0700117 aad(&sa)->request &= mask;
John Johansen6380bd82010-07-29 14:48:04 -0700118
John Johansenaa9aeea2017-05-29 12:16:04 -0700119 if (likely(!aad(&sa)->request))
John Johansen6380bd82010-07-29 14:48:04 -0700120 return 0;
121 type = AUDIT_APPARMOR_AUDIT;
122 } else {
123 /* only report permissions that were denied */
John Johansenaa9aeea2017-05-29 12:16:04 -0700124 aad(&sa)->request = aad(&sa)->request & ~perms->allow;
125 AA_BUG(!aad(&sa)->request);
John Johansen6380bd82010-07-29 14:48:04 -0700126
John Johansenaa9aeea2017-05-29 12:16:04 -0700127 if (aad(&sa)->request & perms->kill)
John Johansen6380bd82010-07-29 14:48:04 -0700128 type = AUDIT_APPARMOR_KILL;
129
130 /* quiet known rejects, assumes quiet and kill do not overlap */
John Johansenaa9aeea2017-05-29 12:16:04 -0700131 if ((aad(&sa)->request & perms->quiet) &&
John Johansen6380bd82010-07-29 14:48:04 -0700132 AUDIT_MODE(profile) != AUDIT_NOQUIET &&
133 AUDIT_MODE(profile) != AUDIT_ALL)
John Johansenaa9aeea2017-05-29 12:16:04 -0700134 aad(&sa)->request &= ~perms->quiet;
John Johansen6380bd82010-07-29 14:48:04 -0700135
John Johansenaa9aeea2017-05-29 12:16:04 -0700136 if (!aad(&sa)->request)
John Johansen98c3d182017-06-09 15:48:20 -0700137 return aad(&sa)->error;
John Johansen6380bd82010-07-29 14:48:04 -0700138 }
139
John Johansenaa9aeea2017-05-29 12:16:04 -0700140 aad(&sa)->denied = aad(&sa)->request & ~perms->allow;
John Johansenef88a7a2017-01-16 00:43:02 -0800141 return aa_audit(type, profile, &sa, file_audit_cb);
John Johansen6380bd82010-07-29 14:48:04 -0700142}
143
144/**
John Johansenaebd8732017-06-09 16:02:25 -0700145 * is_deleted - test if a file has been completely unlinked
146 * @dentry: dentry of file to test for deletion (NOT NULL)
147 *
Zou Weie3798602020-04-28 19:52:21 +0800148 * Returns: true if deleted else false
John Johansenaebd8732017-06-09 16:02:25 -0700149 */
150static inline bool is_deleted(struct dentry *dentry)
151{
152 if (d_unlinked(dentry) && d_backing_inode(dentry)->i_nlink == 0)
Zou Weie3798602020-04-28 19:52:21 +0800153 return true;
154 return false;
John Johansenaebd8732017-06-09 16:02:25 -0700155}
156
157static int path_name(const char *op, struct aa_label *label,
158 const struct path *path, int flags, char *buffer,
159 const char **name, struct path_cond *cond, u32 request)
160{
161 struct aa_profile *profile;
162 const char *info = NULL;
163 int error;
164
165 error = aa_path_name(path, flags, buffer, name, &info,
166 labels_profile(label)->disconnected);
167 if (error) {
168 fn_for_each_confined(label, profile,
169 aa_audit_file(profile, &nullperms, op, request, *name,
170 NULL, NULL, cond->uid, info, error));
171 return error;
172 }
173
174 return 0;
175}
176
177/**
John Johansen6380bd82010-07-29 14:48:04 -0700178 * map_old_perms - map old file perms layout to the new layout
179 * @old: permission set in old mapping
180 *
181 * Returns: new permission mapping
182 */
183static u32 map_old_perms(u32 old)
184{
185 u32 new = old & 0xf;
186 if (old & MAY_READ)
John Johansene53cfe62017-05-26 15:07:22 -0700187 new |= AA_MAY_GETATTR | AA_MAY_OPEN;
John Johansen6380bd82010-07-29 14:48:04 -0700188 if (old & MAY_WRITE)
John Johansene53cfe62017-05-26 15:07:22 -0700189 new |= AA_MAY_SETATTR | AA_MAY_CREATE | AA_MAY_DELETE |
190 AA_MAY_CHMOD | AA_MAY_CHOWN | AA_MAY_OPEN;
John Johansen6380bd82010-07-29 14:48:04 -0700191 if (old & 0x10)
192 new |= AA_MAY_LINK;
193 /* the old mapping lock and link_subset flags where overlaid
194 * and use was determined by part of a pair that they were in
195 */
196 if (old & 0x20)
197 new |= AA_MAY_LOCK | AA_LINK_SUBSET;
198 if (old & 0x40) /* AA_EXEC_MMAP */
199 new |= AA_EXEC_MMAP;
200
John Johansen6380bd82010-07-29 14:48:04 -0700201 return new;
202}
203
204/**
John Johansen2d679f32017-05-29 12:19:39 -0700205 * aa_compute_fperms - convert dfa compressed perms to internal perms
John Johansen6380bd82010-07-29 14:48:04 -0700206 * @dfa: dfa to compute perms for (NOT NULL)
207 * @state: state in dfa
208 * @cond: conditions to consider (NOT NULL)
209 *
210 * TODO: convert from dfa + state to permission entry, do computation conversion
211 * at load time.
212 *
213 * Returns: computed permission set
214 */
John Johansen2d679f32017-05-29 12:19:39 -0700215struct aa_perms aa_compute_fperms(struct aa_dfa *dfa, unsigned int state,
216 struct path_cond *cond)
John Johansen6380bd82010-07-29 14:48:04 -0700217{
John Johansen6380bd82010-07-29 14:48:04 -0700218 /* FIXME: change over to new dfa format
219 * currently file perms are encoded in the dfa, new format
220 * splits the permissions from the dfa. This mapping can be
221 * done at profile load
222 */
Arnd Bergmann7bba39a2017-09-15 21:55:46 +0200223 struct aa_perms perms = { };
John Johansen6380bd82010-07-29 14:48:04 -0700224
Eric W. Biederman2db81452012-02-07 16:33:13 -0800225 if (uid_eq(current_fsuid(), cond->uid)) {
John Johansen6380bd82010-07-29 14:48:04 -0700226 perms.allow = map_old_perms(dfa_user_allow(dfa, state));
227 perms.audit = map_old_perms(dfa_user_audit(dfa, state));
228 perms.quiet = map_old_perms(dfa_user_quiet(dfa, state));
229 perms.xindex = dfa_user_xindex(dfa, state);
230 } else {
231 perms.allow = map_old_perms(dfa_other_allow(dfa, state));
232 perms.audit = map_old_perms(dfa_other_audit(dfa, state));
233 perms.quiet = map_old_perms(dfa_other_quiet(dfa, state));
234 perms.xindex = dfa_other_xindex(dfa, state);
235 }
John Johansene53cfe62017-05-26 15:07:22 -0700236 perms.allow |= AA_MAY_GETATTR;
John Johansen6380bd82010-07-29 14:48:04 -0700237
238 /* change_profile wasn't determined by ownership in old mapping */
239 if (ACCEPT_TABLE(dfa)[state] & 0x80000000)
240 perms.allow |= AA_MAY_CHANGE_PROFILE;
John Johansen0421ea92012-03-27 04:14:33 -0700241 if (ACCEPT_TABLE(dfa)[state] & 0x40000000)
242 perms.allow |= AA_MAY_ONEXEC;
John Johansen6380bd82010-07-29 14:48:04 -0700243
244 return perms;
245}
246
247/**
248 * aa_str_perms - find permission that match @name
249 * @dfa: to match against (MAYBE NULL)
250 * @state: state to start matching in
251 * @name: string to match against dfa (NOT NULL)
252 * @cond: conditions to consider for permission set computation (NOT NULL)
253 * @perms: Returns - the permissions found when matching @name
254 *
255 * Returns: the final state in @dfa when beginning @start and walking @name
256 */
257unsigned int aa_str_perms(struct aa_dfa *dfa, unsigned int start,
258 const char *name, struct path_cond *cond,
John Johansen2d679f32017-05-29 12:19:39 -0700259 struct aa_perms *perms)
John Johansen6380bd82010-07-29 14:48:04 -0700260{
261 unsigned int state;
John Johansen6380bd82010-07-29 14:48:04 -0700262 state = aa_dfa_match(dfa, start, name);
John Johansen2d679f32017-05-29 12:19:39 -0700263 *perms = aa_compute_fperms(dfa, state, cond);
John Johansen6380bd82010-07-29 14:48:04 -0700264
265 return state;
266}
267
John Johansenaebd8732017-06-09 16:02:25 -0700268int __aa_path_perm(const char *op, struct aa_profile *profile, const char *name,
269 u32 request, struct path_cond *cond, int flags,
270 struct aa_perms *perms)
John Johansen6380bd82010-07-29 14:48:04 -0700271{
John Johansenaebd8732017-06-09 16:02:25 -0700272 int e = 0;
273
274 if (profile_unconfined(profile))
275 return 0;
276 aa_str_perms(profile->file.dfa, profile->file.start, name, cond, perms);
277 if (request & ~perms->allow)
278 e = -EACCES;
279 return aa_audit_file(profile, perms, op, request, name, NULL, NULL,
280 cond->uid, NULL, e);
281}
282
283
284static int profile_path_perm(const char *op, struct aa_profile *profile,
285 const struct path *path, char *buffer, u32 request,
286 struct path_cond *cond, int flags,
287 struct aa_perms *perms)
288{
289 const char *name;
290 int error;
291
292 if (profile_unconfined(profile))
293 return 0;
294
295 error = path_name(op, &profile->label, path,
296 flags | profile->path_flags, buffer, &name, cond,
297 request);
298 if (error)
299 return error;
300 return __aa_path_perm(op, profile, name, request, cond, flags,
301 perms);
John Johansen6380bd82010-07-29 14:48:04 -0700302}
303
304/**
305 * aa_path_perm - do permissions check & audit for @path
306 * @op: operation being checked
John Johansenaebd8732017-06-09 16:02:25 -0700307 * @label: profile being enforced (NOT NULL)
John Johansen6380bd82010-07-29 14:48:04 -0700308 * @path: path to check permissions of (NOT NULL)
309 * @flags: any additional path flags beyond what the profile specifies
310 * @request: requested permissions
311 * @cond: conditional info for this request (NOT NULL)
312 *
313 * Returns: %0 else error if access denied or other error
314 */
John Johansenaebd8732017-06-09 16:02:25 -0700315int aa_path_perm(const char *op, struct aa_label *label,
John Johansen47f6e5c2017-01-16 00:43:01 -0800316 const struct path *path, int flags, u32 request,
317 struct path_cond *cond)
John Johansen6380bd82010-07-29 14:48:04 -0700318{
John Johansen2d679f32017-05-29 12:19:39 -0700319 struct aa_perms perms = {};
John Johansenaebd8732017-06-09 16:02:25 -0700320 struct aa_profile *profile;
321 char *buffer = NULL;
John Johansen6380bd82010-07-29 14:48:04 -0700322 int error;
323
John Johansenaebd8732017-06-09 16:02:25 -0700324 flags |= PATH_DELEGATE_DELETED | (S_ISDIR(cond->mode) ? PATH_IS_DIR :
325 0);
John Johansen341c1fd2019-09-14 03:34:06 -0700326 buffer = aa_get_buffer(false);
Sebastian Andrzej Siewiordf323332019-05-03 16:12:21 +0200327 if (!buffer)
328 return -ENOMEM;
John Johansenaebd8732017-06-09 16:02:25 -0700329 error = fn_for_each_confined(label, profile,
330 profile_path_perm(op, profile, path, buffer, request,
331 cond, flags, &perms));
332
Sebastian Andrzej Siewiordf323332019-05-03 16:12:21 +0200333 aa_put_buffer(buffer);
John Johansen6380bd82010-07-29 14:48:04 -0700334
335 return error;
336}
337
338/**
339 * xindex_is_subset - helper for aa_path_link
340 * @link: link permission set
341 * @target: target permission set
342 *
343 * test target x permissions are equal OR a subset of link x permissions
344 * this is done as part of the subset test, where a hardlink must have
345 * a subset of permissions that the target has.
346 *
Zou Weie3798602020-04-28 19:52:21 +0800347 * Returns: true if subset else false
John Johansen6380bd82010-07-29 14:48:04 -0700348 */
349static inline bool xindex_is_subset(u32 link, u32 target)
350{
351 if (((link & ~AA_X_UNSAFE) != (target & ~AA_X_UNSAFE)) ||
352 ((link & AA_X_UNSAFE) && !(target & AA_X_UNSAFE)))
Zou Weie3798602020-04-28 19:52:21 +0800353 return false;
John Johansen6380bd82010-07-29 14:48:04 -0700354
Zou Weie3798602020-04-28 19:52:21 +0800355 return true;
John Johansen6380bd82010-07-29 14:48:04 -0700356}
357
John Johansen80143702017-06-09 16:06:21 -0700358static int profile_path_link(struct aa_profile *profile,
359 const struct path *link, char *buffer,
360 const struct path *target, char *buffer2,
361 struct path_cond *cond)
John Johansen6380bd82010-07-29 14:48:04 -0700362{
John Johansen80143702017-06-09 16:06:21 -0700363 const char *lname, *tname = NULL;
364 struct aa_perms lperms = {}, perms;
365 const char *info = NULL;
John Johansen6380bd82010-07-29 14:48:04 -0700366 u32 request = AA_MAY_LINK;
367 unsigned int state;
368 int error;
369
John Johansen80143702017-06-09 16:06:21 -0700370 error = path_name(OP_LINK, &profile->label, link, profile->path_flags,
371 buffer, &lname, cond, AA_MAY_LINK);
John Johansen6380bd82010-07-29 14:48:04 -0700372 if (error)
373 goto audit;
374
375 /* buffer2 freed below, tname is pointer in buffer2 */
John Johansen80143702017-06-09 16:06:21 -0700376 error = path_name(OP_LINK, &profile->label, target, profile->path_flags,
377 buffer2, &tname, cond, AA_MAY_LINK);
John Johansen6380bd82010-07-29 14:48:04 -0700378 if (error)
379 goto audit;
380
381 error = -EACCES;
382 /* aa_str_perms - handles the case of the dfa being NULL */
383 state = aa_str_perms(profile->file.dfa, profile->file.start, lname,
John Johansen80143702017-06-09 16:06:21 -0700384 cond, &lperms);
John Johansen6380bd82010-07-29 14:48:04 -0700385
386 if (!(lperms.allow & AA_MAY_LINK))
387 goto audit;
388
389 /* test to see if target can be paired with link */
390 state = aa_dfa_null_transition(profile->file.dfa, state);
John Johansen80143702017-06-09 16:06:21 -0700391 aa_str_perms(profile->file.dfa, state, tname, cond, &perms);
John Johansen6380bd82010-07-29 14:48:04 -0700392
393 /* force audit/quiet masks for link are stored in the second entry
394 * in the link pair.
395 */
396 lperms.audit = perms.audit;
397 lperms.quiet = perms.quiet;
398 lperms.kill = perms.kill;
399
400 if (!(perms.allow & AA_MAY_LINK)) {
401 info = "target restricted";
John Johansen80143702017-06-09 16:06:21 -0700402 lperms = perms;
John Johansen6380bd82010-07-29 14:48:04 -0700403 goto audit;
404 }
405
406 /* done if link subset test is not required */
407 if (!(perms.allow & AA_LINK_SUBSET))
408 goto done_tests;
409
John Johansen80143702017-06-09 16:06:21 -0700410 /* Do link perm subset test requiring allowed permission on link are
411 * a subset of the allowed permissions on target.
John Johansen6380bd82010-07-29 14:48:04 -0700412 */
John Johansen80143702017-06-09 16:06:21 -0700413 aa_str_perms(profile->file.dfa, profile->file.start, tname, cond,
John Johansen6380bd82010-07-29 14:48:04 -0700414 &perms);
415
416 /* AA_MAY_LINK is not considered in the subset test */
417 request = lperms.allow & ~AA_MAY_LINK;
418 lperms.allow &= perms.allow | AA_MAY_LINK;
419
420 request |= AA_AUDIT_FILE_MASK & (lperms.allow & ~perms.allow);
421 if (request & ~lperms.allow) {
422 goto audit;
423 } else if ((lperms.allow & MAY_EXEC) &&
424 !xindex_is_subset(lperms.xindex, perms.xindex)) {
425 lperms.allow &= ~MAY_EXEC;
426 request |= MAY_EXEC;
427 info = "link not subset of target";
428 goto audit;
429 }
430
431done_tests:
432 error = 0;
433
434audit:
John Johansen80143702017-06-09 16:06:21 -0700435 return aa_audit_file(profile, &lperms, OP_LINK, request, lname, tname,
436 NULL, cond->uid, info, error);
437}
438
439/**
440 * aa_path_link - Handle hard link permission check
441 * @label: the label being enforced (NOT NULL)
442 * @old_dentry: the target dentry (NOT NULL)
443 * @new_dir: directory the new link will be created in (NOT NULL)
444 * @new_dentry: the link being created (NOT NULL)
445 *
446 * Handle the permission test for a link & target pair. Permission
447 * is encoded as a pair where the link permission is determined
448 * first, and if allowed, the target is tested. The target test
449 * is done from the point of the link match (not start of DFA)
450 * making the target permission dependent on the link permission match.
451 *
452 * The subset test if required forces that permissions granted
453 * on link are a subset of the permission granted to target.
454 *
455 * Returns: %0 if allowed else error
456 */
457int aa_path_link(struct aa_label *label, struct dentry *old_dentry,
458 const struct path *new_dir, struct dentry *new_dentry)
459{
Stephen Rothwellc4758fa2017-06-20 14:50:36 +1000460 struct path link = { .mnt = new_dir->mnt, .dentry = new_dentry };
461 struct path target = { .mnt = new_dir->mnt, .dentry = old_dentry };
John Johansen80143702017-06-09 16:06:21 -0700462 struct path_cond cond = {
463 d_backing_inode(old_dentry)->i_uid,
464 d_backing_inode(old_dentry)->i_mode
465 };
466 char *buffer = NULL, *buffer2 = NULL;
467 struct aa_profile *profile;
468 int error;
469
470 /* buffer freed below, lname is pointer in buffer */
John Johansen341c1fd2019-09-14 03:34:06 -0700471 buffer = aa_get_buffer(false);
472 buffer2 = aa_get_buffer(false);
Sebastian Andrzej Siewiordf323332019-05-03 16:12:21 +0200473 error = -ENOMEM;
474 if (!buffer || !buffer2)
475 goto out;
476
John Johansen80143702017-06-09 16:06:21 -0700477 error = fn_for_each_confined(label, profile,
478 profile_path_link(profile, &link, buffer, &target,
479 buffer2, &cond));
Sebastian Andrzej Siewiordf323332019-05-03 16:12:21 +0200480out:
481 aa_put_buffer(buffer);
482 aa_put_buffer(buffer2);
John Johansen6380bd82010-07-29 14:48:04 -0700483 return error;
484}
485
John Johansen496c9312017-06-09 16:19:02 -0700486static void update_file_ctx(struct aa_file_ctx *fctx, struct aa_label *label,
487 u32 request)
488{
489 struct aa_label *l, *old;
490
491 /* update caching of label on file_ctx */
492 spin_lock(&fctx->lock);
493 old = rcu_dereference_protected(fctx->label,
Lance Roy0fb871c2018-10-02 22:39:01 -0700494 lockdep_is_held(&fctx->lock));
John Johansen496c9312017-06-09 16:19:02 -0700495 l = aa_label_merge(old, label, GFP_ATOMIC);
496 if (l) {
497 if (l != old) {
498 rcu_assign_pointer(fctx->label, l);
499 aa_put_label(old);
500 } else
501 aa_put_label(l);
502 fctx->allow |= request;
503 }
504 spin_unlock(&fctx->lock);
505}
506
507static int __file_path_perm(const char *op, struct aa_label *label,
508 struct aa_label *flabel, struct file *file,
John Johansen341c1fd2019-09-14 03:34:06 -0700509 u32 request, u32 denied, bool in_atomic)
John Johansen496c9312017-06-09 16:19:02 -0700510{
511 struct aa_profile *profile;
512 struct aa_perms perms = {};
513 struct path_cond cond = {
Christian Brauner3cee6072021-01-21 14:19:44 +0100514 .uid = i_uid_into_mnt(file_mnt_user_ns(file), file_inode(file)),
John Johansen496c9312017-06-09 16:19:02 -0700515 .mode = file_inode(file)->i_mode
516 };
517 char *buffer;
518 int flags, error;
519
520 /* revalidation due to label out of date. No revocation at this time */
521 if (!denied && aa_label_is_subset(flabel, label))
522 /* TODO: check for revocation on stale profiles */
523 return 0;
524
525 flags = PATH_DELEGATE_DELETED | (S_ISDIR(cond.mode) ? PATH_IS_DIR : 0);
John Johansen341c1fd2019-09-14 03:34:06 -0700526 buffer = aa_get_buffer(in_atomic);
Sebastian Andrzej Siewiordf323332019-05-03 16:12:21 +0200527 if (!buffer)
528 return -ENOMEM;
John Johansen496c9312017-06-09 16:19:02 -0700529
530 /* check every profile in task label not in current cache */
531 error = fn_for_each_not_in_set(flabel, label, profile,
532 profile_path_perm(op, profile, &file->f_path, buffer,
533 request, &cond, flags, &perms));
534 if (denied && !error) {
535 /*
536 * check every profile in file label that was not tested
537 * in the initial check above.
538 *
539 * TODO: cache full perms so this only happens because of
540 * conditionals
541 * TODO: don't audit here
542 */
543 if (label == flabel)
544 error = fn_for_each(label, profile,
545 profile_path_perm(op, profile, &file->f_path,
546 buffer, request, &cond, flags,
547 &perms));
548 else
549 error = fn_for_each_not_in_set(label, flabel, profile,
550 profile_path_perm(op, profile, &file->f_path,
551 buffer, request, &cond, flags,
552 &perms));
553 }
554 if (!error)
555 update_file_ctx(file_ctx(file), label, request);
556
Sebastian Andrzej Siewiordf323332019-05-03 16:12:21 +0200557 aa_put_buffer(buffer);
John Johansen496c9312017-06-09 16:19:02 -0700558
559 return error;
560}
561
John Johansen56974a62017-07-18 23:18:33 -0700562static int __file_sock_perm(const char *op, struct aa_label *label,
563 struct aa_label *flabel, struct file *file,
564 u32 request, u32 denied)
565{
566 struct socket *sock = (struct socket *) file->private_data;
567 int error;
568
569 AA_BUG(!sock);
570
571 /* revalidation due to label out of date. No revocation at this time */
572 if (!denied && aa_label_is_subset(flabel, label))
573 return 0;
574
575 /* TODO: improve to skip profiles cached in flabel */
576 error = aa_sock_file_perm(label, op, request, sock);
577 if (denied) {
578 /* TODO: improve to skip profiles checked above */
579 /* check every profile in file label to is cached */
580 last_error(error, aa_sock_file_perm(flabel, op, request, sock));
581 }
582 if (!error)
583 update_file_ctx(file_ctx(file), label, request);
584
585 return error;
586}
587
John Johansen6380bd82010-07-29 14:48:04 -0700588/**
589 * aa_file_perm - do permission revalidation check & audit for @file
590 * @op: operation being checked
John Johansen190a9512017-06-09 14:59:51 -0700591 * @label: label being enforced (NOT NULL)
John Johansen6380bd82010-07-29 14:48:04 -0700592 * @file: file to revalidate access permissions on (NOT NULL)
593 * @request: requested permissions
John Johansen341c1fd2019-09-14 03:34:06 -0700594 * @in_atomic: whether allocations need to be done in atomic context
John Johansen6380bd82010-07-29 14:48:04 -0700595 *
596 * Returns: %0 if access allowed else error
597 */
John Johansen190a9512017-06-09 14:59:51 -0700598int aa_file_perm(const char *op, struct aa_label *label, struct file *file,
John Johansen341c1fd2019-09-14 03:34:06 -0700599 u32 request, bool in_atomic)
John Johansen6380bd82010-07-29 14:48:04 -0700600{
John Johansen190a9512017-06-09 14:59:51 -0700601 struct aa_file_ctx *fctx;
602 struct aa_label *flabel;
603 u32 denied;
604 int error = 0;
John Johansen6380bd82010-07-29 14:48:04 -0700605
John Johansen190a9512017-06-09 14:59:51 -0700606 AA_BUG(!label);
607 AA_BUG(!file);
608
609 fctx = file_ctx(file);
610
611 rcu_read_lock();
John Johansen20d4e802019-12-18 11:04:07 -0800612 flabel = rcu_dereference(fctx->label);
John Johansen190a9512017-06-09 14:59:51 -0700613 AA_BUG(!flabel);
614
615 /* revalidate access, if task is unconfined, or the cached cred
616 * doesn't match or if the request is for more permissions than
617 * was granted.
618 *
619 * Note: the test for !unconfined(flabel) is to handle file
620 * delegation from unconfined tasks
621 */
622 denied = request & ~fctx->allow;
623 if (unconfined(label) || unconfined(flabel) ||
John Johansen20d4e802019-12-18 11:04:07 -0800624 (!denied && aa_label_is_subset(flabel, label))) {
625 rcu_read_unlock();
John Johansen190a9512017-06-09 14:59:51 -0700626 goto done;
John Johansen20d4e802019-12-18 11:04:07 -0800627 }
John Johansen190a9512017-06-09 14:59:51 -0700628
John Johansen20d4e802019-12-18 11:04:07 -0800629 flabel = aa_get_newest_label(flabel);
630 rcu_read_unlock();
John Johansen190a9512017-06-09 14:59:51 -0700631 /* TODO: label cross check */
632
633 if (file->f_path.mnt && path_mediated_fs(file->f_path.dentry))
John Johansen496c9312017-06-09 16:19:02 -0700634 error = __file_path_perm(op, label, flabel, file, request,
John Johansen341c1fd2019-09-14 03:34:06 -0700635 denied, in_atomic);
John Johansen190a9512017-06-09 14:59:51 -0700636
John Johansen56974a62017-07-18 23:18:33 -0700637 else if (S_ISSOCK(file_inode(file)->i_mode))
638 error = __file_sock_perm(op, label, flabel, file, request,
639 denied);
John Johansenbce4e7e2019-09-13 22:24:23 -0700640 aa_put_label(flabel);
John Johansen20d4e802019-12-18 11:04:07 -0800641
642done:
John Johansen190a9512017-06-09 14:59:51 -0700643 return error;
John Johansen6380bd82010-07-29 14:48:04 -0700644}
John Johansen192ca6b2017-06-09 11:58:42 -0700645
John Johansen637f6882017-06-09 08:14:28 -0700646static void revalidate_tty(struct aa_label *label)
John Johansen192ca6b2017-06-09 11:58:42 -0700647{
648 struct tty_struct *tty;
649 int drop_tty = 0;
650
651 tty = get_current_tty();
652 if (!tty)
653 return;
654
655 spin_lock(&tty->files_lock);
656 if (!list_empty(&tty->tty_files)) {
657 struct tty_file_private *file_priv;
658 struct file *file;
659 /* TODO: Revalidate access to controlling tty. */
660 file_priv = list_first_entry(&tty->tty_files,
661 struct tty_file_private, list);
662 file = file_priv->file;
663
John Johansen341c1fd2019-09-14 03:34:06 -0700664 if (aa_file_perm(OP_INHERIT, label, file, MAY_READ | MAY_WRITE,
665 IN_ATOMIC))
John Johansen192ca6b2017-06-09 11:58:42 -0700666 drop_tty = 1;
667 }
668 spin_unlock(&tty->files_lock);
669 tty_kref_put(tty);
670
671 if (drop_tty)
672 no_tty();
673}
674
675static int match_file(const void *p, struct file *file, unsigned int fd)
676{
John Johansen637f6882017-06-09 08:14:28 -0700677 struct aa_label *label = (struct aa_label *)p;
John Johansen192ca6b2017-06-09 11:58:42 -0700678
John Johansen341c1fd2019-09-14 03:34:06 -0700679 if (aa_file_perm(OP_INHERIT, label, file, aa_map_file_to_perms(file),
680 IN_ATOMIC))
John Johansen192ca6b2017-06-09 11:58:42 -0700681 return fd + 1;
682 return 0;
683}
684
685
686/* based on selinux's flush_unauthorized_files */
687void aa_inherit_files(const struct cred *cred, struct files_struct *files)
688{
John Johansen637f6882017-06-09 08:14:28 -0700689 struct aa_label *label = aa_get_newest_cred_label(cred);
John Johansen192ca6b2017-06-09 11:58:42 -0700690 struct file *devnull = NULL;
691 unsigned int n;
692
John Johansen637f6882017-06-09 08:14:28 -0700693 revalidate_tty(label);
John Johansen192ca6b2017-06-09 11:58:42 -0700694
695 /* Revalidate access to inherited open files. */
John Johansen637f6882017-06-09 08:14:28 -0700696 n = iterate_fd(files, 0, match_file, label);
John Johansen192ca6b2017-06-09 11:58:42 -0700697 if (!n) /* none found? */
698 goto out;
699
700 devnull = dentry_open(&aa_null, O_RDWR, cred);
701 if (IS_ERR(devnull))
702 devnull = NULL;
703 /* replace all the matching ones with this */
704 do {
705 replace_fd(n - 1, devnull, 0);
John Johansen637f6882017-06-09 08:14:28 -0700706 } while ((n = iterate_fd(files, n, match_file, label)) != 0);
John Johansen192ca6b2017-06-09 11:58:42 -0700707 if (devnull)
708 fput(devnull);
709out:
John Johansen637f6882017-06-09 08:14:28 -0700710 aa_put_label(label);
John Johansen192ca6b2017-06-09 11:58:42 -0700711}