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 kuid_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",
80 from_kuid(&init_user_ns, fsuid));
81 audit_log_format(ab, " ouid=%d",
82 from_kuid(&init_user_ns, sa->aad->fs.ouid));
83 }
84
85 if (sa->aad->fs.target) {
86 audit_log_format(ab, " target=");
87 audit_log_untrustedstring(ab, sa->aad->fs.target);
88 }
89}
90
91/**
92 * aa_audit_file - handle the auditing of file operations
93 * @profile: the profile being enforced (NOT NULL)
94 * @perms: the permissions computed for the request (NOT NULL)
95 * @gfp: allocation flags
96 * @op: operation being mediated
97 * @request: permissions requested
98 * @name: name of object being mediated (MAYBE NULL)
99 * @target: name of target (MAYBE NULL)
100 * @ouid: object uid
101 * @info: extra information message (MAYBE NULL)
102 * @error: 0 if operation allowed else failure error code
103 *
104 * Returns: %0 or error on failure
105 */
106int aa_audit_file(struct aa_profile *profile, struct file_perms *perms,
107 gfp_t gfp, int op, u32 request, const char *name,
108 const char *target, kuid_t ouid, const char *info, int error)
109{
110 int type = AUDIT_APPARMOR_AUTO;
111 struct common_audit_data sa;
112 struct apparmor_audit_data aad = {0,};
113 sa.type = LSM_AUDIT_DATA_NONE;
114 sa.aad = &aad;
115 aad.op = op,
116 aad.fs.request = request;
117 aad.name = name;
118 aad.fs.target = target;
119 aad.fs.ouid = ouid;
120 aad.info = info;
121 aad.error = error;
122
123 if (likely(!sa.aad->error)) {
124 u32 mask = perms->audit;
125
126 if (unlikely(AUDIT_MODE(profile) == AUDIT_ALL))
127 mask = 0xffff;
128
129 /* mask off perms that are not being force audited */
130 sa.aad->fs.request &= mask;
131
132 if (likely(!sa.aad->fs.request))
133 return 0;
134 type = AUDIT_APPARMOR_AUDIT;
135 } else {
136 /* only report permissions that were denied */
137 sa.aad->fs.request = sa.aad->fs.request & ~perms->allow;
138
139 if (sa.aad->fs.request & perms->kill)
140 type = AUDIT_APPARMOR_KILL;
141
142 /* quiet known rejects, assumes quiet and kill do not overlap */
143 if ((sa.aad->fs.request & perms->quiet) &&
144 AUDIT_MODE(profile) != AUDIT_NOQUIET &&
145 AUDIT_MODE(profile) != AUDIT_ALL)
146 sa.aad->fs.request &= ~perms->quiet;
147
148 if (!sa.aad->fs.request)
149 return COMPLAIN_MODE(profile) ? 0 : sa.aad->error;
150 }
151
152 sa.aad->fs.denied = sa.aad->fs.request & ~perms->allow;
153 return aa_audit(type, profile, gfp, &sa, file_audit_cb);
154}
155
156/**
157 * map_old_perms - map old file perms layout to the new layout
158 * @old: permission set in old mapping
159 *
160 * Returns: new permission mapping
161 */
162static u32 map_old_perms(u32 old)
163{
164 u32 new = old & 0xf;
165 if (old & MAY_READ)
166 new |= AA_MAY_META_READ;
167 if (old & MAY_WRITE)
168 new |= AA_MAY_META_WRITE | AA_MAY_CREATE | AA_MAY_DELETE |
169 AA_MAY_CHMOD | AA_MAY_CHOWN;
170 if (old & 0x10)
171 new |= AA_MAY_LINK;
172 /* the old mapping lock and link_subset flags where overlaid
173 * and use was determined by part of a pair that they were in
174 */
175 if (old & 0x20)
176 new |= AA_MAY_LOCK | AA_LINK_SUBSET;
177 if (old & 0x40) /* AA_EXEC_MMAP */
178 new |= AA_EXEC_MMAP;
179
180 return new;
181}
182
183/**
184 * compute_perms - convert dfa compressed perms to internal perms
185 * @dfa: dfa to compute perms for (NOT NULL)
186 * @state: state in dfa
187 * @cond: conditions to consider (NOT NULL)
188 *
189 * TODO: convert from dfa + state to permission entry, do computation conversion
190 * at load time.
191 *
192 * Returns: computed permission set
193 */
194static struct file_perms compute_perms(struct aa_dfa *dfa, unsigned int state,
195 struct path_cond *cond)
196{
197 struct file_perms perms;
198
199 /* FIXME: change over to new dfa format
200 * currently file perms are encoded in the dfa, new format
201 * splits the permissions from the dfa. This mapping can be
202 * done at profile load
203 */
204 perms.kill = 0;
205
206 if (uid_eq(current_fsuid(), cond->uid)) {
207 perms.allow = map_old_perms(dfa_user_allow(dfa, state));
208 perms.audit = map_old_perms(dfa_user_audit(dfa, state));
209 perms.quiet = map_old_perms(dfa_user_quiet(dfa, state));
210 perms.xindex = dfa_user_xindex(dfa, state);
211 } else {
212 perms.allow = map_old_perms(dfa_other_allow(dfa, state));
213 perms.audit = map_old_perms(dfa_other_audit(dfa, state));
214 perms.quiet = map_old_perms(dfa_other_quiet(dfa, state));
215 perms.xindex = dfa_other_xindex(dfa, state);
216 }
217 perms.allow |= AA_MAY_META_READ;
218
219 /* change_profile wasn't determined by ownership in old mapping */
220 if (ACCEPT_TABLE(dfa)[state] & 0x80000000)
221 perms.allow |= AA_MAY_CHANGE_PROFILE;
222 if (ACCEPT_TABLE(dfa)[state] & 0x40000000)
223 perms.allow |= AA_MAY_ONEXEC;
224
225 return perms;
226}
227
228/**
229 * aa_str_perms - find permission that match @name
230 * @dfa: to match against (MAYBE NULL)
231 * @state: state to start matching in
232 * @name: string to match against dfa (NOT NULL)
233 * @cond: conditions to consider for permission set computation (NOT NULL)
234 * @perms: Returns - the permissions found when matching @name
235 *
236 * Returns: the final state in @dfa when beginning @start and walking @name
237 */
238unsigned int aa_str_perms(struct aa_dfa *dfa, unsigned int start,
239 const char *name, struct path_cond *cond,
240 struct file_perms *perms)
241{
242 unsigned int state;
243 if (!dfa) {
244 *perms = nullperms;
245 return DFA_NOMATCH;
246 }
247
248 state = aa_dfa_match(dfa, start, name);
249 *perms = compute_perms(dfa, state, cond);
250
251 return state;
252}
253
254/**
255 * is_deleted - test if a file has been completely unlinked
256 * @dentry: dentry of file to test for deletion (NOT NULL)
257 *
258 * Returns: %1 if deleted else %0
259 */
260static inline bool is_deleted(struct dentry *dentry)
261{
262 if (d_unlinked(dentry) && d_backing_inode(dentry)->i_nlink == 0)
263 return 1;
264 return 0;
265}
266
267/**
268 * aa_path_perm - do permissions check & audit for @path
269 * @op: operation being checked
270 * @profile: profile being enforced (NOT NULL)
271 * @path: path to check permissions of (NOT NULL)
272 * @flags: any additional path flags beyond what the profile specifies
273 * @request: requested permissions
274 * @cond: conditional info for this request (NOT NULL)
275 *
276 * Returns: %0 else error if access denied or other error
277 */
278int aa_path_perm(int op, struct aa_profile *profile, struct path *path,
279 int flags, u32 request, struct path_cond *cond)
280{
281 char *buffer = NULL;
282 struct file_perms perms = {};
283 const char *name, *info = NULL;
284 int error;
285
286 flags |= profile->path_flags | (S_ISDIR(cond->mode) ? PATH_IS_DIR : 0);
287 error = aa_path_name(path, flags, &buffer, &name, &info);
288 if (error) {
289 if (error == -ENOENT && is_deleted(path->dentry)) {
290 /* Access to open files that are deleted are
291 * give a pass (implicit delegation)
292 */
293 error = 0;
294 info = NULL;
295 perms.allow = request;
296 }
297 } else {
298 aa_str_perms(profile->file.dfa, profile->file.start, name, cond,
299 &perms);
300 if (request & ~perms.allow)
301 error = -EACCES;
302 }
303 error = aa_audit_file(profile, &perms, GFP_KERNEL, op, request, name,
304 NULL, cond->uid, info, error);
305 kfree(buffer);
306
307 return error;
308}
309
310/**
311 * xindex_is_subset - helper for aa_path_link
312 * @link: link permission set
313 * @target: target permission set
314 *
315 * test target x permissions are equal OR a subset of link x permissions
316 * this is done as part of the subset test, where a hardlink must have
317 * a subset of permissions that the target has.
318 *
319 * Returns: %1 if subset else %0
320 */
321static inline bool xindex_is_subset(u32 link, u32 target)
322{
323 if (((link & ~AA_X_UNSAFE) != (target & ~AA_X_UNSAFE)) ||
324 ((link & AA_X_UNSAFE) && !(target & AA_X_UNSAFE)))
325 return 0;
326
327 return 1;
328}
329
330/**
331 * aa_path_link - Handle hard link permission check
332 * @profile: the profile being enforced (NOT NULL)
333 * @old_dentry: the target dentry (NOT NULL)
334 * @new_dir: directory the new link will be created in (NOT NULL)
335 * @new_dentry: the link being created (NOT NULL)
336 *
337 * Handle the permission test for a link & target pair. Permission
338 * is encoded as a pair where the link permission is determined
339 * first, and if allowed, the target is tested. The target test
340 * is done from the point of the link match (not start of DFA)
341 * making the target permission dependent on the link permission match.
342 *
343 * The subset test if required forces that permissions granted
344 * on link are a subset of the permission granted to target.
345 *
346 * Returns: %0 if allowed else error
347 */
348int aa_path_link(struct aa_profile *profile, struct dentry *old_dentry,
349 struct path *new_dir, struct dentry *new_dentry)
350{
351 struct path link = { new_dir->mnt, new_dentry };
352 struct path target = { new_dir->mnt, old_dentry };
353 struct path_cond cond = {
354 d_backing_inode(old_dentry)->i_uid,
355 d_backing_inode(old_dentry)->i_mode
356 };
357 char *buffer = NULL, *buffer2 = NULL;
358 const char *lname, *tname = NULL, *info = NULL;
359 struct file_perms lperms, perms;
360 u32 request = AA_MAY_LINK;
361 unsigned int state;
362 int error;
363
364 lperms = nullperms;
365
366 /* buffer freed below, lname is pointer in buffer */
367 error = aa_path_name(&link, profile->path_flags, &buffer, &lname,
368 &info);
369 if (error)
370 goto audit;
371
372 /* buffer2 freed below, tname is pointer in buffer2 */
373 error = aa_path_name(&target, profile->path_flags, &buffer2, &tname,
374 &info);
375 if (error)
376 goto audit;
377
378 error = -EACCES;
379 /* aa_str_perms - handles the case of the dfa being NULL */
380 state = aa_str_perms(profile->file.dfa, profile->file.start, lname,
381 &cond, &lperms);
382
383 if (!(lperms.allow & AA_MAY_LINK))
384 goto audit;
385
386 /* test to see if target can be paired with link */
387 state = aa_dfa_null_transition(profile->file.dfa, state);
388 aa_str_perms(profile->file.dfa, state, tname, &cond, &perms);
389
390 /* force audit/quiet masks for link are stored in the second entry
391 * in the link pair.
392 */
393 lperms.audit = perms.audit;
394 lperms.quiet = perms.quiet;
395 lperms.kill = perms.kill;
396
397 if (!(perms.allow & AA_MAY_LINK)) {
398 info = "target restricted";
399 goto audit;
400 }
401
402 /* done if link subset test is not required */
403 if (!(perms.allow & AA_LINK_SUBSET))
404 goto done_tests;
405
406 /* Do link perm subset test requiring allowed permission on link are a
407 * subset of the allowed permissions on target.
408 */
409 aa_str_perms(profile->file.dfa, profile->file.start, tname, &cond,
410 &perms);
411
412 /* AA_MAY_LINK is not considered in the subset test */
413 request = lperms.allow & ~AA_MAY_LINK;
414 lperms.allow &= perms.allow | AA_MAY_LINK;
415
416 request |= AA_AUDIT_FILE_MASK & (lperms.allow & ~perms.allow);
417 if (request & ~lperms.allow) {
418 goto audit;
419 } else if ((lperms.allow & MAY_EXEC) &&
420 !xindex_is_subset(lperms.xindex, perms.xindex)) {
421 lperms.allow &= ~MAY_EXEC;
422 request |= MAY_EXEC;
423 info = "link not subset of target";
424 goto audit;
425 }
426
427done_tests:
428 error = 0;
429
430audit:
431 error = aa_audit_file(profile, &lperms, GFP_KERNEL, OP_LINK, request,
432 lname, tname, cond.uid, info, error);
433 kfree(buffer);
434 kfree(buffer2);
435
436 return error;
437}
438
439/**
440 * aa_file_perm - do permission revalidation check & audit for @file
441 * @op: operation being checked
442 * @profile: profile being enforced (NOT NULL)
443 * @file: file to revalidate access permissions on (NOT NULL)
444 * @request: requested permissions
445 *
446 * Returns: %0 if access allowed else error
447 */
448int aa_file_perm(int op, struct aa_profile *profile, struct file *file,
449 u32 request)
450{
451 struct path_cond cond = {
452 .uid = file_inode(file)->i_uid,
453 .mode = file_inode(file)->i_mode
454 };
455
456 return aa_path_perm(op, profile, &file->f_path, PATH_DELEGATE_DELETED,
457 request, &cond);
458}
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
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"
24
25static u32 map_mask_to_chr_mask(u32 mask)
26{
27 u32 m = mask & PERMS_CHRS_MASK;
28
29 if (mask & AA_MAY_GETATTR)
30 m |= MAY_READ;
31 if (mask & (AA_MAY_SETATTR | AA_MAY_CHMOD | AA_MAY_CHOWN))
32 m |= MAY_WRITE;
33
34 return m;
35}
36
37/**
38 * audit_file_mask - convert mask to permission string
39 * @buffer: buffer to write string to (NOT NULL)
40 * @mask: permission mask to convert
41 */
42static void audit_file_mask(struct audit_buffer *ab, u32 mask)
43{
44 char str[10];
45
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);
49}
50
51/**
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)
55 */
56static void file_audit_cb(struct audit_buffer *ab, void *va)
57{
58 struct common_audit_data *sa = va;
59 kuid_t fsuid = current_fsuid();
60
61 if (aad(sa)->request & AA_AUDIT_FILE_MASK) {
62 audit_log_format(ab, " requested_mask=");
63 audit_file_mask(ab, aad(sa)->request);
64 }
65 if (aad(sa)->denied & AA_AUDIT_FILE_MASK) {
66 audit_log_format(ab, " denied_mask=");
67 audit_file_mask(ab, aad(sa)->denied);
68 }
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));
74 }
75
76 if (aad(sa)->peer) {
77 audit_log_format(ab, " target=");
78 aa_label_xaudit(ab, labels_ns(aad(sa)->label), aad(sa)->peer,
79 FLAG_VIEW_SUBNS, GFP_ATOMIC);
80 } else if (aad(sa)->fs.target) {
81 audit_log_format(ab, " target=");
82 audit_log_untrustedstring(ab, aad(sa)->fs.target);
83 }
84}
85
86/**
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)
95 * @ouid: object uid
96 * @info: extra information message (MAYBE NULL)
97 * @error: 0 if operation allowed else failure error code
98 *
99 * Returns: %0 or error on failure
100 */
101int 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)
105{
106 int type = AUDIT_APPARMOR_AUTO;
107 DEFINE_AUDIT_DATA(sa, LSM_AUDIT_DATA_TASK, op);
108
109 sa.u.tsk = NULL;
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;
117 sa.u.tsk = NULL;
118
119 if (likely(!aad(&sa)->error)) {
120 u32 mask = perms->audit;
121
122 if (unlikely(AUDIT_MODE(profile) == AUDIT_ALL))
123 mask = 0xffff;
124
125 /* mask off perms that are not being force audited */
126 aad(&sa)->request &= mask;
127
128 if (likely(!aad(&sa)->request))
129 return 0;
130 type = AUDIT_APPARMOR_AUDIT;
131 } else {
132 /* only report permissions that were denied */
133 aad(&sa)->request = aad(&sa)->request & ~perms->allow;
134 AA_BUG(!aad(&sa)->request);
135
136 if (aad(&sa)->request & perms->kill)
137 type = AUDIT_APPARMOR_KILL;
138
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;
144
145 if (!aad(&sa)->request)
146 return aad(&sa)->error;
147 }
148
149 aad(&sa)->denied = aad(&sa)->request & ~perms->allow;
150 return aa_audit(type, profile, &sa, file_audit_cb);
151}
152
153/**
154 * is_deleted - test if a file has been completely unlinked
155 * @dentry: dentry of file to test for deletion (NOT NULL)
156 *
157 * Returns: %1 if deleted else %0
158 */
159static inline bool is_deleted(struct dentry *dentry)
160{
161 if (d_unlinked(dentry) && d_backing_inode(dentry)->i_nlink == 0)
162 return 1;
163 return 0;
164}
165
166static 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)
169{
170 struct aa_profile *profile;
171 const char *info = NULL;
172 int error;
173
174 error = aa_path_name(path, flags, buffer, name, &info,
175 labels_profile(label)->disconnected);
176 if (error) {
177 fn_for_each_confined(label, profile,
178 aa_audit_file(profile, &nullperms, op, request, *name,
179 NULL, NULL, cond->uid, info, error));
180 return error;
181 }
182
183 return 0;
184}
185
186/**
187 * map_old_perms - map old file perms layout to the new layout
188 * @old: permission set in old mapping
189 *
190 * Returns: new permission mapping
191 */
192static u32 map_old_perms(u32 old)
193{
194 u32 new = old & 0xf;
195 if (old & MAY_READ)
196 new |= AA_MAY_GETATTR | AA_MAY_OPEN;
197 if (old & MAY_WRITE)
198 new |= AA_MAY_SETATTR | AA_MAY_CREATE | AA_MAY_DELETE |
199 AA_MAY_CHMOD | AA_MAY_CHOWN | AA_MAY_OPEN;
200 if (old & 0x10)
201 new |= AA_MAY_LINK;
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
204 */
205 if (old & 0x20)
206 new |= AA_MAY_LOCK | AA_LINK_SUBSET;
207 if (old & 0x40) /* AA_EXEC_MMAP */
208 new |= AA_EXEC_MMAP;
209
210 return new;
211}
212
213/**
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)
218 *
219 * TODO: convert from dfa + state to permission entry, do computation conversion
220 * at load time.
221 *
222 * Returns: computed permission set
223 */
224struct aa_perms aa_compute_fperms(struct aa_dfa *dfa, unsigned int state,
225 struct path_cond *cond)
226{
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
231 */
232 struct aa_perms perms = { };
233
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);
239 } else {
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);
244 }
245 perms.allow |= AA_MAY_GETATTR;
246
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;
252
253 return perms;
254}
255
256/**
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
263 *
264 * Returns: the final state in @dfa when beginning @start and walking @name
265 */
266unsigned int aa_str_perms(struct aa_dfa *dfa, unsigned int start,
267 const char *name, struct path_cond *cond,
268 struct aa_perms *perms)
269{
270 unsigned int state;
271 state = aa_dfa_match(dfa, start, name);
272 *perms = aa_compute_fperms(dfa, state, cond);
273
274 return state;
275}
276
277int __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)
280{
281 int e = 0;
282
283 if (profile_unconfined(profile))
284 return 0;
285 aa_str_perms(profile->file.dfa, profile->file.start, name, cond, perms);
286 if (request & ~perms->allow)
287 e = -EACCES;
288 return aa_audit_file(profile, perms, op, request, name, NULL, NULL,
289 cond->uid, NULL, e);
290}
291
292
293static 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)
297{
298 const char *name;
299 int error;
300
301 if (profile_unconfined(profile))
302 return 0;
303
304 error = path_name(op, &profile->label, path,
305 flags | profile->path_flags, buffer, &name, cond,
306 request);
307 if (error)
308 return error;
309 return __aa_path_perm(op, profile, name, request, cond, flags,
310 perms);
311}
312
313/**
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)
321 *
322 * Returns: %0 else error if access denied or other error
323 */
324int aa_path_perm(const char *op, struct aa_label *label,
325 const struct path *path, int flags, u32 request,
326 struct path_cond *cond)
327{
328 struct aa_perms perms = {};
329 struct aa_profile *profile;
330 char *buffer = NULL;
331 int error;
332
333 flags |= PATH_DELEGATE_DELETED | (S_ISDIR(cond->mode) ? PATH_IS_DIR :
334 0);
335 get_buffers(buffer);
336 error = fn_for_each_confined(label, profile,
337 profile_path_perm(op, profile, path, buffer, request,
338 cond, flags, &perms));
339
340 put_buffers(buffer);
341
342 return error;
343}
344
345/**
346 * xindex_is_subset - helper for aa_path_link
347 * @link: link permission set
348 * @target: target permission set
349 *
350 * test target x permissions are equal OR a subset of link x permissions
351 * this is done as part of the subset test, where a hardlink must have
352 * a subset of permissions that the target has.
353 *
354 * Returns: %1 if subset else %0
355 */
356static inline bool xindex_is_subset(u32 link, u32 target)
357{
358 if (((link & ~AA_X_UNSAFE) != (target & ~AA_X_UNSAFE)) ||
359 ((link & AA_X_UNSAFE) && !(target & AA_X_UNSAFE)))
360 return 0;
361
362 return 1;
363}
364
365static int profile_path_link(struct aa_profile *profile,
366 const struct path *link, char *buffer,
367 const struct path *target, char *buffer2,
368 struct path_cond *cond)
369{
370 const char *lname, *tname = NULL;
371 struct aa_perms lperms = {}, perms;
372 const char *info = NULL;
373 u32 request = AA_MAY_LINK;
374 unsigned int state;
375 int error;
376
377 error = path_name(OP_LINK, &profile->label, link, profile->path_flags,
378 buffer, &lname, cond, AA_MAY_LINK);
379 if (error)
380 goto audit;
381
382 /* buffer2 freed below, tname is pointer in buffer2 */
383 error = path_name(OP_LINK, &profile->label, target, profile->path_flags,
384 buffer2, &tname, cond, AA_MAY_LINK);
385 if (error)
386 goto audit;
387
388 error = -EACCES;
389 /* aa_str_perms - handles the case of the dfa being NULL */
390 state = aa_str_perms(profile->file.dfa, profile->file.start, lname,
391 cond, &lperms);
392
393 if (!(lperms.allow & AA_MAY_LINK))
394 goto audit;
395
396 /* test to see if target can be paired with link */
397 state = aa_dfa_null_transition(profile->file.dfa, state);
398 aa_str_perms(profile->file.dfa, state, tname, cond, &perms);
399
400 /* force audit/quiet masks for link are stored in the second entry
401 * in the link pair.
402 */
403 lperms.audit = perms.audit;
404 lperms.quiet = perms.quiet;
405 lperms.kill = perms.kill;
406
407 if (!(perms.allow & AA_MAY_LINK)) {
408 info = "target restricted";
409 lperms = perms;
410 goto audit;
411 }
412
413 /* done if link subset test is not required */
414 if (!(perms.allow & AA_LINK_SUBSET))
415 goto done_tests;
416
417 /* Do link perm subset test requiring allowed permission on link are
418 * a subset of the allowed permissions on target.
419 */
420 aa_str_perms(profile->file.dfa, profile->file.start, tname, cond,
421 &perms);
422
423 /* AA_MAY_LINK is not considered in the subset test */
424 request = lperms.allow & ~AA_MAY_LINK;
425 lperms.allow &= perms.allow | AA_MAY_LINK;
426
427 request |= AA_AUDIT_FILE_MASK & (lperms.allow & ~perms.allow);
428 if (request & ~lperms.allow) {
429 goto audit;
430 } else if ((lperms.allow & MAY_EXEC) &&
431 !xindex_is_subset(lperms.xindex, perms.xindex)) {
432 lperms.allow &= ~MAY_EXEC;
433 request |= MAY_EXEC;
434 info = "link not subset of target";
435 goto audit;
436 }
437
438done_tests:
439 error = 0;
440
441audit:
442 return aa_audit_file(profile, &lperms, OP_LINK, request, lname, tname,
443 NULL, cond->uid, info, error);
444}
445
446/**
447 * aa_path_link - Handle hard link permission check
448 * @label: the label being enforced (NOT NULL)
449 * @old_dentry: the target dentry (NOT NULL)
450 * @new_dir: directory the new link will be created in (NOT NULL)
451 * @new_dentry: the link being created (NOT NULL)
452 *
453 * Handle the permission test for a link & target pair. Permission
454 * is encoded as a pair where the link permission is determined
455 * first, and if allowed, the target is tested. The target test
456 * is done from the point of the link match (not start of DFA)
457 * making the target permission dependent on the link permission match.
458 *
459 * The subset test if required forces that permissions granted
460 * on link are a subset of the permission granted to target.
461 *
462 * Returns: %0 if allowed else error
463 */
464int aa_path_link(struct aa_label *label, struct dentry *old_dentry,
465 const struct path *new_dir, struct dentry *new_dentry)
466{
467 struct path link = { .mnt = new_dir->mnt, .dentry = new_dentry };
468 struct path target = { .mnt = new_dir->mnt, .dentry = old_dentry };
469 struct path_cond cond = {
470 d_backing_inode(old_dentry)->i_uid,
471 d_backing_inode(old_dentry)->i_mode
472 };
473 char *buffer = NULL, *buffer2 = NULL;
474 struct aa_profile *profile;
475 int error;
476
477 /* buffer freed below, lname is pointer in buffer */
478 get_buffers(buffer, buffer2);
479 error = fn_for_each_confined(label, profile,
480 profile_path_link(profile, &link, buffer, &target,
481 buffer2, &cond));
482 put_buffers(buffer, buffer2);
483
484 return error;
485}
486
487static void update_file_ctx(struct aa_file_ctx *fctx, struct aa_label *label,
488 u32 request)
489{
490 struct aa_label *l, *old;
491
492 /* update caching of label on file_ctx */
493 spin_lock(&fctx->lock);
494 old = rcu_dereference_protected(fctx->label,
495 lockdep_is_held(&fctx->lock));
496 l = aa_label_merge(old, label, GFP_ATOMIC);
497 if (l) {
498 if (l != old) {
499 rcu_assign_pointer(fctx->label, l);
500 aa_put_label(old);
501 } else
502 aa_put_label(l);
503 fctx->allow |= request;
504 }
505 spin_unlock(&fctx->lock);
506}
507
508static int __file_path_perm(const char *op, struct aa_label *label,
509 struct aa_label *flabel, struct file *file,
510 u32 request, u32 denied)
511{
512 struct aa_profile *profile;
513 struct aa_perms perms = {};
514 struct path_cond cond = {
515 .uid = file_inode(file)->i_uid,
516 .mode = file_inode(file)->i_mode
517 };
518 char *buffer;
519 int flags, error;
520
521 /* revalidation due to label out of date. No revocation at this time */
522 if (!denied && aa_label_is_subset(flabel, label))
523 /* TODO: check for revocation on stale profiles */
524 return 0;
525
526 flags = PATH_DELEGATE_DELETED | (S_ISDIR(cond.mode) ? PATH_IS_DIR : 0);
527 get_buffers(buffer);
528
529 /* check every profile in task label not in current cache */
530 error = fn_for_each_not_in_set(flabel, label, profile,
531 profile_path_perm(op, profile, &file->f_path, buffer,
532 request, &cond, flags, &perms));
533 if (denied && !error) {
534 /*
535 * check every profile in file label that was not tested
536 * in the initial check above.
537 *
538 * TODO: cache full perms so this only happens because of
539 * conditionals
540 * TODO: don't audit here
541 */
542 if (label == flabel)
543 error = fn_for_each(label, profile,
544 profile_path_perm(op, profile, &file->f_path,
545 buffer, request, &cond, flags,
546 &perms));
547 else
548 error = fn_for_each_not_in_set(label, flabel, profile,
549 profile_path_perm(op, profile, &file->f_path,
550 buffer, request, &cond, flags,
551 &perms));
552 }
553 if (!error)
554 update_file_ctx(file_ctx(file), label, request);
555
556 put_buffers(buffer);
557
558 return error;
559}
560
561static int __file_sock_perm(const char *op, struct aa_label *label,
562 struct aa_label *flabel, struct file *file,
563 u32 request, u32 denied)
564{
565 struct socket *sock = (struct socket *) file->private_data;
566 int error;
567
568 AA_BUG(!sock);
569
570 /* revalidation due to label out of date. No revocation at this time */
571 if (!denied && aa_label_is_subset(flabel, label))
572 return 0;
573
574 /* TODO: improve to skip profiles cached in flabel */
575 error = aa_sock_file_perm(label, op, request, sock);
576 if (denied) {
577 /* TODO: improve to skip profiles checked above */
578 /* check every profile in file label to is cached */
579 last_error(error, aa_sock_file_perm(flabel, op, request, sock));
580 }
581 if (!error)
582 update_file_ctx(file_ctx(file), label, request);
583
584 return error;
585}
586
587/**
588 * aa_file_perm - do permission revalidation check & audit for @file
589 * @op: operation being checked
590 * @label: label being enforced (NOT NULL)
591 * @file: file to revalidate access permissions on (NOT NULL)
592 * @request: requested permissions
593 *
594 * Returns: %0 if access allowed else error
595 */
596int aa_file_perm(const char *op, struct aa_label *label, struct file *file,
597 u32 request)
598{
599 struct aa_file_ctx *fctx;
600 struct aa_label *flabel;
601 u32 denied;
602 int error = 0;
603
604 AA_BUG(!label);
605 AA_BUG(!file);
606
607 fctx = file_ctx(file);
608
609 rcu_read_lock();
610 flabel = rcu_dereference(fctx->label);
611 AA_BUG(!flabel);
612
613 /* revalidate access, if task is unconfined, or the cached cred
614 * doesn't match or if the request is for more permissions than
615 * was granted.
616 *
617 * Note: the test for !unconfined(flabel) is to handle file
618 * delegation from unconfined tasks
619 */
620 denied = request & ~fctx->allow;
621 if (unconfined(label) || unconfined(flabel) ||
622 (!denied && aa_label_is_subset(flabel, label)))
623 goto done;
624
625 /* TODO: label cross check */
626
627 if (file->f_path.mnt && path_mediated_fs(file->f_path.dentry))
628 error = __file_path_perm(op, label, flabel, file, request,
629 denied);
630
631 else if (S_ISSOCK(file_inode(file)->i_mode))
632 error = __file_sock_perm(op, label, flabel, file, request,
633 denied);
634done:
635 rcu_read_unlock();
636
637 return error;
638}
639
640static void revalidate_tty(struct aa_label *label)
641{
642 struct tty_struct *tty;
643 int drop_tty = 0;
644
645 tty = get_current_tty();
646 if (!tty)
647 return;
648
649 spin_lock(&tty->files_lock);
650 if (!list_empty(&tty->tty_files)) {
651 struct tty_file_private *file_priv;
652 struct file *file;
653 /* TODO: Revalidate access to controlling tty. */
654 file_priv = list_first_entry(&tty->tty_files,
655 struct tty_file_private, list);
656 file = file_priv->file;
657
658 if (aa_file_perm(OP_INHERIT, label, file, MAY_READ | MAY_WRITE))
659 drop_tty = 1;
660 }
661 spin_unlock(&tty->files_lock);
662 tty_kref_put(tty);
663
664 if (drop_tty)
665 no_tty();
666}
667
668static int match_file(const void *p, struct file *file, unsigned int fd)
669{
670 struct aa_label *label = (struct aa_label *)p;
671
672 if (aa_file_perm(OP_INHERIT, label, file, aa_map_file_to_perms(file)))
673 return fd + 1;
674 return 0;
675}
676
677
678/* based on selinux's flush_unauthorized_files */
679void aa_inherit_files(const struct cred *cred, struct files_struct *files)
680{
681 struct aa_label *label = aa_get_newest_cred_label(cred);
682 struct file *devnull = NULL;
683 unsigned int n;
684
685 revalidate_tty(label);
686
687 /* Revalidate access to inherited open files. */
688 n = iterate_fd(files, 0, match_file, label);
689 if (!n) /* none found? */
690 goto out;
691
692 devnull = dentry_open(&aa_null, O_RDWR, cred);
693 if (IS_ERR(devnull))
694 devnull = NULL;
695 /* replace all the matching ones with this */
696 do {
697 replace_fd(n - 1, devnull, 0);
698 } while ((n = iterate_fd(files, n, match_file, label)) != 0);
699 if (devnull)
700 fput(devnull);
701out:
702 aa_put_label(label);
703}