Loading...
1/*
2 * AppArmor security module
3 *
4 * This file contains AppArmor mediation of files
5 *
6 * Copyright (C) 1998-2008 Novell/SUSE
7 * Copyright 2009-2010 Canonical Ltd.
8 *
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
12 * License.
13 */
14
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"
21
22struct file_perms nullperms;
23
24
25/**
26 * audit_file_mask - convert mask to permission string
27 * @buffer: buffer to write string to (NOT NULL)
28 * @mask: permission mask to convert
29 */
30static void audit_file_mask(struct audit_buffer *ab, u32 mask)
31{
32 char str[10];
33
34 char *m = str;
35
36 if (mask & AA_EXEC_MMAP)
37 *m++ = 'm';
38 if (mask & (MAY_READ | AA_MAY_META_READ))
39 *m++ = 'r';
40 if (mask & (MAY_WRITE | AA_MAY_META_WRITE | AA_MAY_CHMOD |
41 AA_MAY_CHOWN))
42 *m++ = 'w';
43 else if (mask & MAY_APPEND)
44 *m++ = 'a';
45 if (mask & AA_MAY_CREATE)
46 *m++ = 'c';
47 if (mask & AA_MAY_DELETE)
48 *m++ = 'd';
49 if (mask & AA_MAY_LINK)
50 *m++ = 'l';
51 if (mask & AA_MAY_LOCK)
52 *m++ = 'k';
53 if (mask & MAY_EXEC)
54 *m++ = 'x';
55 *m = '\0';
56
57 audit_log_string(ab, str);
58}
59
60/**
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)
64 */
65static void file_audit_cb(struct audit_buffer *ab, void *va)
66{
67 struct common_audit_data *sa = va;
68 uid_t fsuid = current_fsuid();
69
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);
73 }
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);
77 }
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);
81 }
82
83 if (sa->aad->fs.target) {
84 audit_log_format(ab, " target=");
85 audit_log_untrustedstring(ab, sa->aad->fs.target);
86 }
87}
88
89/**
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)
98 * @ouid: object uid
99 * @info: extra information message (MAYBE NULL)
100 * @error: 0 if operation allowed else failure error code
101 *
102 * Returns: %0 or error on failure
103 */
104int 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)
107{
108 int type = AUDIT_APPARMOR_AUTO;
109 struct common_audit_data sa;
110 struct apparmor_audit_data aad = {0,};
111 sa.type = LSM_AUDIT_DATA_NONE;
112 sa.aad = &aad;
113 aad.op = op,
114 aad.fs.request = request;
115 aad.name = name;
116 aad.fs.target = target;
117 aad.fs.ouid = ouid;
118 aad.info = info;
119 aad.error = error;
120
121 if (likely(!sa.aad->error)) {
122 u32 mask = perms->audit;
123
124 if (unlikely(AUDIT_MODE(profile) == AUDIT_ALL))
125 mask = 0xffff;
126
127 /* mask off perms that are not being force audited */
128 sa.aad->fs.request &= mask;
129
130 if (likely(!sa.aad->fs.request))
131 return 0;
132 type = AUDIT_APPARMOR_AUDIT;
133 } else {
134 /* only report permissions that were denied */
135 sa.aad->fs.request = sa.aad->fs.request & ~perms->allow;
136
137 if (sa.aad->fs.request & perms->kill)
138 type = AUDIT_APPARMOR_KILL;
139
140 /* quiet known rejects, assumes quiet and kill do not overlap */
141 if ((sa.aad->fs.request & perms->quiet) &&
142 AUDIT_MODE(profile) != AUDIT_NOQUIET &&
143 AUDIT_MODE(profile) != AUDIT_ALL)
144 sa.aad->fs.request &= ~perms->quiet;
145
146 if (!sa.aad->fs.request)
147 return COMPLAIN_MODE(profile) ? 0 : sa.aad->error;
148 }
149
150 sa.aad->fs.denied = sa.aad->fs.request & ~perms->allow;
151 return aa_audit(type, profile, gfp, &sa, file_audit_cb);
152}
153
154/**
155 * map_old_perms - map old file perms layout to the new layout
156 * @old: permission set in old mapping
157 *
158 * Returns: new permission mapping
159 */
160static u32 map_old_perms(u32 old)
161{
162 u32 new = old & 0xf;
163 if (old & MAY_READ)
164 new |= AA_MAY_META_READ;
165 if (old & MAY_WRITE)
166 new |= AA_MAY_META_WRITE | AA_MAY_CREATE | AA_MAY_DELETE |
167 AA_MAY_CHMOD | AA_MAY_CHOWN;
168 if (old & 0x10)
169 new |= AA_MAY_LINK;
170 /* the old mapping lock and link_subset flags where overlaid
171 * and use was determined by part of a pair that they were in
172 */
173 if (old & 0x20)
174 new |= AA_MAY_LOCK | AA_LINK_SUBSET;
175 if (old & 0x40) /* AA_EXEC_MMAP */
176 new |= AA_EXEC_MMAP;
177
178 return new;
179}
180
181/**
182 * compute_perms - convert dfa compressed perms to internal perms
183 * @dfa: dfa to compute perms for (NOT NULL)
184 * @state: state in dfa
185 * @cond: conditions to consider (NOT NULL)
186 *
187 * TODO: convert from dfa + state to permission entry, do computation conversion
188 * at load time.
189 *
190 * Returns: computed permission set
191 */
192static struct file_perms compute_perms(struct aa_dfa *dfa, unsigned int state,
193 struct path_cond *cond)
194{
195 struct file_perms perms;
196
197 /* FIXME: change over to new dfa format
198 * currently file perms are encoded in the dfa, new format
199 * splits the permissions from the dfa. This mapping can be
200 * done at profile load
201 */
202 perms.kill = 0;
203
204 if (current_fsuid() == cond->uid) {
205 perms.allow = map_old_perms(dfa_user_allow(dfa, state));
206 perms.audit = map_old_perms(dfa_user_audit(dfa, state));
207 perms.quiet = map_old_perms(dfa_user_quiet(dfa, state));
208 perms.xindex = dfa_user_xindex(dfa, state);
209 } else {
210 perms.allow = map_old_perms(dfa_other_allow(dfa, state));
211 perms.audit = map_old_perms(dfa_other_audit(dfa, state));
212 perms.quiet = map_old_perms(dfa_other_quiet(dfa, state));
213 perms.xindex = dfa_other_xindex(dfa, state);
214 }
215 perms.allow |= AA_MAY_META_READ;
216
217 /* change_profile wasn't determined by ownership in old mapping */
218 if (ACCEPT_TABLE(dfa)[state] & 0x80000000)
219 perms.allow |= AA_MAY_CHANGE_PROFILE;
220 if (ACCEPT_TABLE(dfa)[state] & 0x40000000)
221 perms.allow |= AA_MAY_ONEXEC;
222
223 return perms;
224}
225
226/**
227 * aa_str_perms - find permission that match @name
228 * @dfa: to match against (MAYBE NULL)
229 * @state: state to start matching in
230 * @name: string to match against dfa (NOT NULL)
231 * @cond: conditions to consider for permission set computation (NOT NULL)
232 * @perms: Returns - the permissions found when matching @name
233 *
234 * Returns: the final state in @dfa when beginning @start and walking @name
235 */
236unsigned int aa_str_perms(struct aa_dfa *dfa, unsigned int start,
237 const char *name, struct path_cond *cond,
238 struct file_perms *perms)
239{
240 unsigned int state;
241 if (!dfa) {
242 *perms = nullperms;
243 return DFA_NOMATCH;
244 }
245
246 state = aa_dfa_match(dfa, start, name);
247 *perms = compute_perms(dfa, state, cond);
248
249 return state;
250}
251
252/**
253 * is_deleted - test if a file has been completely unlinked
254 * @dentry: dentry of file to test for deletion (NOT NULL)
255 *
256 * Returns: %1 if deleted else %0
257 */
258static inline bool is_deleted(struct dentry *dentry)
259{
260 if (d_unlinked(dentry) && dentry->d_inode->i_nlink == 0)
261 return 1;
262 return 0;
263}
264
265/**
266 * aa_path_perm - do permissions check & audit for @path
267 * @op: operation being checked
268 * @profile: profile being enforced (NOT NULL)
269 * @path: path to check permissions of (NOT NULL)
270 * @flags: any additional path flags beyond what the profile specifies
271 * @request: requested permissions
272 * @cond: conditional info for this request (NOT NULL)
273 *
274 * Returns: %0 else error if access denied or other error
275 */
276int aa_path_perm(int op, struct aa_profile *profile, struct path *path,
277 int flags, u32 request, struct path_cond *cond)
278{
279 char *buffer = NULL;
280 struct file_perms perms = {};
281 const char *name, *info = NULL;
282 int error;
283
284 flags |= profile->path_flags | (S_ISDIR(cond->mode) ? PATH_IS_DIR : 0);
285 error = aa_path_name(path, flags, &buffer, &name, &info);
286 if (error) {
287 if (error == -ENOENT && is_deleted(path->dentry)) {
288 /* Access to open files that are deleted are
289 * give a pass (implicit delegation)
290 */
291 error = 0;
292 info = NULL;
293 perms.allow = request;
294 }
295 } else {
296 aa_str_perms(profile->file.dfa, profile->file.start, name, cond,
297 &perms);
298 if (request & ~perms.allow)
299 error = -EACCES;
300 }
301 error = aa_audit_file(profile, &perms, GFP_KERNEL, op, request, name,
302 NULL, cond->uid, info, error);
303 kfree(buffer);
304
305 return error;
306}
307
308/**
309 * xindex_is_subset - helper for aa_path_link
310 * @link: link permission set
311 * @target: target permission set
312 *
313 * test target x permissions are equal OR a subset of link x permissions
314 * this is done as part of the subset test, where a hardlink must have
315 * a subset of permissions that the target has.
316 *
317 * Returns: %1 if subset else %0
318 */
319static inline bool xindex_is_subset(u32 link, u32 target)
320{
321 if (((link & ~AA_X_UNSAFE) != (target & ~AA_X_UNSAFE)) ||
322 ((link & AA_X_UNSAFE) && !(target & AA_X_UNSAFE)))
323 return 0;
324
325 return 1;
326}
327
328/**
329 * aa_path_link - Handle hard link permission check
330 * @profile: the profile being enforced (NOT NULL)
331 * @old_dentry: the target dentry (NOT NULL)
332 * @new_dir: directory the new link will be created in (NOT NULL)
333 * @new_dentry: the link being created (NOT NULL)
334 *
335 * Handle the permission test for a link & target pair. Permission
336 * is encoded as a pair where the link permission is determined
337 * first, and if allowed, the target is tested. The target test
338 * is done from the point of the link match (not start of DFA)
339 * making the target permission dependent on the link permission match.
340 *
341 * The subset test if required forces that permissions granted
342 * on link are a subset of the permission granted to target.
343 *
344 * Returns: %0 if allowed else error
345 */
346int aa_path_link(struct aa_profile *profile, struct dentry *old_dentry,
347 struct path *new_dir, struct dentry *new_dentry)
348{
349 struct path link = { new_dir->mnt, new_dentry };
350 struct path target = { new_dir->mnt, old_dentry };
351 struct path_cond cond = {
352 old_dentry->d_inode->i_uid,
353 old_dentry->d_inode->i_mode
354 };
355 char *buffer = NULL, *buffer2 = NULL;
356 const char *lname, *tname = NULL, *info = NULL;
357 struct file_perms lperms, perms;
358 u32 request = AA_MAY_LINK;
359 unsigned int state;
360 int error;
361
362 lperms = nullperms;
363
364 /* buffer freed below, lname is pointer in buffer */
365 error = aa_path_name(&link, profile->path_flags, &buffer, &lname,
366 &info);
367 if (error)
368 goto audit;
369
370 /* buffer2 freed below, tname is pointer in buffer2 */
371 error = aa_path_name(&target, profile->path_flags, &buffer2, &tname,
372 &info);
373 if (error)
374 goto audit;
375
376 error = -EACCES;
377 /* aa_str_perms - handles the case of the dfa being NULL */
378 state = aa_str_perms(profile->file.dfa, profile->file.start, lname,
379 &cond, &lperms);
380
381 if (!(lperms.allow & AA_MAY_LINK))
382 goto audit;
383
384 /* test to see if target can be paired with link */
385 state = aa_dfa_null_transition(profile->file.dfa, state);
386 aa_str_perms(profile->file.dfa, state, tname, &cond, &perms);
387
388 /* force audit/quiet masks for link are stored in the second entry
389 * in the link pair.
390 */
391 lperms.audit = perms.audit;
392 lperms.quiet = perms.quiet;
393 lperms.kill = perms.kill;
394
395 if (!(perms.allow & AA_MAY_LINK)) {
396 info = "target restricted";
397 goto audit;
398 }
399
400 /* done if link subset test is not required */
401 if (!(perms.allow & AA_LINK_SUBSET))
402 goto done_tests;
403
404 /* Do link perm subset test requiring allowed permission on link are a
405 * subset of the allowed permissions on target.
406 */
407 aa_str_perms(profile->file.dfa, profile->file.start, tname, &cond,
408 &perms);
409
410 /* AA_MAY_LINK is not considered in the subset test */
411 request = lperms.allow & ~AA_MAY_LINK;
412 lperms.allow &= perms.allow | AA_MAY_LINK;
413
414 request |= AA_AUDIT_FILE_MASK & (lperms.allow & ~perms.allow);
415 if (request & ~lperms.allow) {
416 goto audit;
417 } else if ((lperms.allow & MAY_EXEC) &&
418 !xindex_is_subset(lperms.xindex, perms.xindex)) {
419 lperms.allow &= ~MAY_EXEC;
420 request |= MAY_EXEC;
421 info = "link not subset of target";
422 goto audit;
423 }
424
425done_tests:
426 error = 0;
427
428audit:
429 error = aa_audit_file(profile, &lperms, GFP_KERNEL, OP_LINK, request,
430 lname, tname, cond.uid, info, error);
431 kfree(buffer);
432 kfree(buffer2);
433
434 return error;
435}
436
437/**
438 * aa_file_perm - do permission revalidation check & audit for @file
439 * @op: operation being checked
440 * @profile: profile being enforced (NOT NULL)
441 * @file: file to revalidate access permissions on (NOT NULL)
442 * @request: requested permissions
443 *
444 * Returns: %0 if access allowed else error
445 */
446int aa_file_perm(int op, struct aa_profile *profile, struct file *file,
447 u32 request)
448{
449 struct path_cond cond = {
450 .uid = file->f_path.dentry->d_inode->i_uid,
451 .mode = file->f_path.dentry->d_inode->i_mode
452 };
453
454 return aa_path_perm(op, profile, &file->f_path, PATH_DELEGATE_DELETED,
455 request, &cond);
456}
1// SPDX-License-Identifier: GPL-2.0-only
2/*
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.
9 */
10
11#include <linux/tty.h>
12#include <linux/fdtable.h>
13#include <linux/file.h>
14#include <linux/fs.h>
15#include <linux/mount.h>
16
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"
26
27static 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}
38
39/**
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)
43 */
44static void file_audit_cb(struct audit_buffer *ab, void *va)
45{
46 struct common_audit_data *sa = va;
47 kuid_t fsuid = current_fsuid();
48 char str[10];
49
50 if (aad(sa)->request & AA_AUDIT_FILE_MASK) {
51 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);
54 }
55 if (aad(sa)->denied & AA_AUDIT_FILE_MASK) {
56 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);
59 }
60 if (aad(sa)->request & AA_AUDIT_FILE_MASK) {
61 audit_log_format(ab, " fsuid=%d",
62 from_kuid(&init_user_ns, fsuid));
63 audit_log_format(ab, " ouid=%d",
64 from_kuid(&init_user_ns, aad(sa)->fs.ouid));
65 }
66
67 if (aad(sa)->peer) {
68 audit_log_format(ab, " target=");
69 aa_label_xaudit(ab, labels_ns(aad(sa)->label), aad(sa)->peer,
70 FLAG_VIEW_SUBNS, GFP_KERNEL);
71 } else if (aad(sa)->fs.target) {
72 audit_log_format(ab, " target=");
73 audit_log_untrustedstring(ab, aad(sa)->fs.target);
74 }
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)
81 * @op: operation being mediated
82 * @request: permissions requested
83 * @name: name of object being mediated (MAYBE NULL)
84 * @target: name of target (MAYBE NULL)
85 * @tlabel: target label (MAY BE NULL)
86 * @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 */
92int aa_audit_file(struct aa_profile *profile, struct aa_perms *perms,
93 const char *op, u32 request, const char *name,
94 const char *target, struct aa_label *tlabel,
95 kuid_t ouid, const char *info, int error)
96{
97 int type = AUDIT_APPARMOR_AUTO;
98 DEFINE_AUDIT_DATA(sa, LSM_AUDIT_DATA_TASK, op);
99
100 sa.u.tsk = NULL;
101 aad(&sa)->request = request;
102 aad(&sa)->name = name;
103 aad(&sa)->fs.target = target;
104 aad(&sa)->peer = tlabel;
105 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)) {
111 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 */
117 aad(&sa)->request &= mask;
118
119 if (likely(!aad(&sa)->request))
120 return 0;
121 type = AUDIT_APPARMOR_AUDIT;
122 } else {
123 /* only report permissions that were denied */
124 aad(&sa)->request = aad(&sa)->request & ~perms->allow;
125 AA_BUG(!aad(&sa)->request);
126
127 if (aad(&sa)->request & perms->kill)
128 type = AUDIT_APPARMOR_KILL;
129
130 /* quiet known rejects, assumes quiet and kill do not overlap */
131 if ((aad(&sa)->request & perms->quiet) &&
132 AUDIT_MODE(profile) != AUDIT_NOQUIET &&
133 AUDIT_MODE(profile) != AUDIT_ALL)
134 aad(&sa)->request &= ~perms->quiet;
135
136 if (!aad(&sa)->request)
137 return aad(&sa)->error;
138 }
139
140 aad(&sa)->denied = aad(&sa)->request & ~perms->allow;
141 return aa_audit(type, profile, &sa, file_audit_cb);
142}
143
144/**
145 * is_deleted - test if a file has been completely unlinked
146 * @dentry: dentry of file to test for deletion (NOT NULL)
147 *
148 * Returns: true if deleted else false
149 */
150static inline bool is_deleted(struct dentry *dentry)
151{
152 if (d_unlinked(dentry) && d_backing_inode(dentry)->i_nlink == 0)
153 return true;
154 return false;
155}
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/**
178 * 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)
187 new |= AA_MAY_GETATTR | AA_MAY_OPEN;
188 if (old & MAY_WRITE)
189 new |= AA_MAY_SETATTR | AA_MAY_CREATE | AA_MAY_DELETE |
190 AA_MAY_CHMOD | AA_MAY_CHOWN | AA_MAY_OPEN;
191 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
201 return new;
202}
203
204/**
205 * aa_compute_fperms - convert dfa compressed perms to internal perms
206 * @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 */
215struct aa_perms aa_compute_fperms(struct aa_dfa *dfa, unsigned int state,
216 struct path_cond *cond)
217{
218 /* 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 */
223 struct aa_perms perms = { };
224
225 if (uid_eq(current_fsuid(), cond->uid)) {
226 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 }
236 perms.allow |= AA_MAY_GETATTR;
237
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;
241 if (ACCEPT_TABLE(dfa)[state] & 0x40000000)
242 perms.allow |= AA_MAY_ONEXEC;
243
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,
259 struct aa_perms *perms)
260{
261 unsigned int state;
262 state = aa_dfa_match(dfa, start, name);
263 *perms = aa_compute_fperms(dfa, state, cond);
264
265 return state;
266}
267
268int __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)
271{
272 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);
302}
303
304/**
305 * aa_path_perm - do permissions check & audit for @path
306 * @op: operation being checked
307 * @label: profile being enforced (NOT NULL)
308 * @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 */
315int aa_path_perm(const char *op, struct aa_label *label,
316 const struct path *path, int flags, u32 request,
317 struct path_cond *cond)
318{
319 struct aa_perms perms = {};
320 struct aa_profile *profile;
321 char *buffer = NULL;
322 int error;
323
324 flags |= PATH_DELEGATE_DELETED | (S_ISDIR(cond->mode) ? PATH_IS_DIR :
325 0);
326 buffer = aa_get_buffer(false);
327 if (!buffer)
328 return -ENOMEM;
329 error = fn_for_each_confined(label, profile,
330 profile_path_perm(op, profile, path, buffer, request,
331 cond, flags, &perms));
332
333 aa_put_buffer(buffer);
334
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 *
347 * Returns: true if subset else false
348 */
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)))
353 return false;
354
355 return true;
356}
357
358static 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)
362{
363 const char *lname, *tname = NULL;
364 struct aa_perms lperms = {}, perms;
365 const char *info = NULL;
366 u32 request = AA_MAY_LINK;
367 unsigned int state;
368 int error;
369
370 error = path_name(OP_LINK, &profile->label, link, profile->path_flags,
371 buffer, &lname, cond, AA_MAY_LINK);
372 if (error)
373 goto audit;
374
375 /* buffer2 freed below, tname is pointer in buffer2 */
376 error = path_name(OP_LINK, &profile->label, target, profile->path_flags,
377 buffer2, &tname, cond, AA_MAY_LINK);
378 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,
384 cond, &lperms);
385
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);
391 aa_str_perms(profile->file.dfa, state, tname, cond, &perms);
392
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";
402 lperms = perms;
403 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
410 /* Do link perm subset test requiring allowed permission on link are
411 * a subset of the allowed permissions on target.
412 */
413 aa_str_perms(profile->file.dfa, profile->file.start, tname, cond,
414 &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:
435 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{
460 struct path link = { .mnt = new_dir->mnt, .dentry = new_dentry };
461 struct path target = { .mnt = new_dir->mnt, .dentry = old_dentry };
462 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 */
471 buffer = aa_get_buffer(false);
472 buffer2 = aa_get_buffer(false);
473 error = -ENOMEM;
474 if (!buffer || !buffer2)
475 goto out;
476
477 error = fn_for_each_confined(label, profile,
478 profile_path_link(profile, &link, buffer, &target,
479 buffer2, &cond));
480out:
481 aa_put_buffer(buffer);
482 aa_put_buffer(buffer2);
483 return error;
484}
485
486static 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,
494 lockdep_is_held(&fctx->lock));
495 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,
509 u32 request, u32 denied, bool in_atomic)
510{
511 struct aa_profile *profile;
512 struct aa_perms perms = {};
513 struct path_cond cond = {
514 .uid = i_uid_into_mnt(file_mnt_user_ns(file), file_inode(file)),
515 .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);
526 buffer = aa_get_buffer(in_atomic);
527 if (!buffer)
528 return -ENOMEM;
529
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
557 aa_put_buffer(buffer);
558
559 return error;
560}
561
562static 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
588/**
589 * aa_file_perm - do permission revalidation check & audit for @file
590 * @op: operation being checked
591 * @label: label being enforced (NOT NULL)
592 * @file: file to revalidate access permissions on (NOT NULL)
593 * @request: requested permissions
594 * @in_atomic: whether allocations need to be done in atomic context
595 *
596 * Returns: %0 if access allowed else error
597 */
598int aa_file_perm(const char *op, struct aa_label *label, struct file *file,
599 u32 request, bool in_atomic)
600{
601 struct aa_file_ctx *fctx;
602 struct aa_label *flabel;
603 u32 denied;
604 int error = 0;
605
606 AA_BUG(!label);
607 AA_BUG(!file);
608
609 fctx = file_ctx(file);
610
611 rcu_read_lock();
612 flabel = rcu_dereference(fctx->label);
613 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) ||
624 (!denied && aa_label_is_subset(flabel, label))) {
625 rcu_read_unlock();
626 goto done;
627 }
628
629 flabel = aa_get_newest_label(flabel);
630 rcu_read_unlock();
631 /* TODO: label cross check */
632
633 if (file->f_path.mnt && path_mediated_fs(file->f_path.dentry))
634 error = __file_path_perm(op, label, flabel, file, request,
635 denied, in_atomic);
636
637 else if (S_ISSOCK(file_inode(file)->i_mode))
638 error = __file_sock_perm(op, label, flabel, file, request,
639 denied);
640 aa_put_label(flabel);
641
642done:
643 return error;
644}
645
646static void revalidate_tty(struct aa_label *label)
647{
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
664 if (aa_file_perm(OP_INHERIT, label, file, MAY_READ | MAY_WRITE,
665 IN_ATOMIC))
666 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{
677 struct aa_label *label = (struct aa_label *)p;
678
679 if (aa_file_perm(OP_INHERIT, label, file, aa_map_file_to_perms(file),
680 IN_ATOMIC))
681 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{
689 struct aa_label *label = aa_get_newest_cred_label(cred);
690 struct file *devnull = NULL;
691 unsigned int n;
692
693 revalidate_tty(label);
694
695 /* Revalidate access to inherited open files. */
696 n = iterate_fd(files, 0, match_file, label);
697 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);
706 } while ((n = iterate_fd(files, n, match_file, label)) != 0);
707 if (devnull)
708 fput(devnull);
709out:
710 aa_put_label(label);
711}