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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) && dentry->d_inode->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 old_dentry->d_inode->i_uid,
355 old_dentry->d_inode->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#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, AA_CLASS_FILE, 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
144static int path_name(const char *op, struct aa_label *label,
145 const struct path *path, int flags, char *buffer,
146 const char **name, struct path_cond *cond, u32 request)
147{
148 struct aa_profile *profile;
149 const char *info = NULL;
150 int error;
151
152 error = aa_path_name(path, flags, buffer, name, &info,
153 labels_profile(label)->disconnected);
154 if (error) {
155 fn_for_each_confined(label, profile,
156 aa_audit_file(profile, &nullperms, op, request, *name,
157 NULL, NULL, cond->uid, info, error));
158 return error;
159 }
160
161 return 0;
162}
163
164/**
165 * aa_lookup_fperms - convert dfa compressed perms to internal perms
166 * @dfa: dfa to lookup perms for (NOT NULL)
167 * @state: state in dfa
168 * @cond: conditions to consider (NOT NULL)
169 *
170 * TODO: convert from dfa + state to permission entry
171 *
172 * Returns: a pointer to a file permission set
173 */
174struct aa_perms default_perms = {};
175struct aa_perms *aa_lookup_fperms(struct aa_policydb *file_rules,
176 aa_state_t state, struct path_cond *cond)
177{
178 unsigned int index = ACCEPT_TABLE(file_rules->dfa)[state];
179
180 if (!(file_rules->perms))
181 return &default_perms;
182
183 if (uid_eq(current_fsuid(), cond->uid))
184 return &(file_rules->perms[index]);
185
186 return &(file_rules->perms[index + 1]);
187}
188
189/**
190 * aa_str_perms - find permission that match @name
191 * @dfa: to match against (MAYBE NULL)
192 * @state: state to start matching in
193 * @name: string to match against dfa (NOT NULL)
194 * @cond: conditions to consider for permission set computation (NOT NULL)
195 * @perms: Returns - the permissions found when matching @name
196 *
197 * Returns: the final state in @dfa when beginning @start and walking @name
198 */
199aa_state_t aa_str_perms(struct aa_policydb *file_rules, aa_state_t start,
200 const char *name, struct path_cond *cond,
201 struct aa_perms *perms)
202{
203 aa_state_t state;
204 state = aa_dfa_match(file_rules->dfa, start, name);
205 *perms = *(aa_lookup_fperms(file_rules, state, cond));
206
207 return state;
208}
209
210static int __aa_path_perm(const char *op, struct aa_profile *profile,
211 const char *name, u32 request,
212 struct path_cond *cond, int flags,
213 struct aa_perms *perms)
214{
215 struct aa_ruleset *rules = list_first_entry(&profile->rules,
216 typeof(*rules), list);
217 int e = 0;
218
219 if (profile_unconfined(profile))
220 return 0;
221 aa_str_perms(&(rules->file), rules->file.start[AA_CLASS_FILE],
222 name, cond, perms);
223 if (request & ~perms->allow)
224 e = -EACCES;
225 return aa_audit_file(profile, perms, op, request, name, NULL, NULL,
226 cond->uid, NULL, e);
227}
228
229
230static int profile_path_perm(const char *op, struct aa_profile *profile,
231 const struct path *path, char *buffer, u32 request,
232 struct path_cond *cond, int flags,
233 struct aa_perms *perms)
234{
235 const char *name;
236 int error;
237
238 if (profile_unconfined(profile))
239 return 0;
240
241 error = path_name(op, &profile->label, path,
242 flags | profile->path_flags, buffer, &name, cond,
243 request);
244 if (error)
245 return error;
246 return __aa_path_perm(op, profile, name, request, cond, flags,
247 perms);
248}
249
250/**
251 * aa_path_perm - do permissions check & audit for @path
252 * @op: operation being checked
253 * @label: profile being enforced (NOT NULL)
254 * @path: path to check permissions of (NOT NULL)
255 * @flags: any additional path flags beyond what the profile specifies
256 * @request: requested permissions
257 * @cond: conditional info for this request (NOT NULL)
258 *
259 * Returns: %0 else error if access denied or other error
260 */
261int aa_path_perm(const char *op, struct aa_label *label,
262 const struct path *path, int flags, u32 request,
263 struct path_cond *cond)
264{
265 struct aa_perms perms = {};
266 struct aa_profile *profile;
267 char *buffer = NULL;
268 int error;
269
270 flags |= PATH_DELEGATE_DELETED | (S_ISDIR(cond->mode) ? PATH_IS_DIR :
271 0);
272 buffer = aa_get_buffer(false);
273 if (!buffer)
274 return -ENOMEM;
275 error = fn_for_each_confined(label, profile,
276 profile_path_perm(op, profile, path, buffer, request,
277 cond, flags, &perms));
278
279 aa_put_buffer(buffer);
280
281 return error;
282}
283
284/**
285 * xindex_is_subset - helper for aa_path_link
286 * @link: link permission set
287 * @target: target permission set
288 *
289 * test target x permissions are equal OR a subset of link x permissions
290 * this is done as part of the subset test, where a hardlink must have
291 * a subset of permissions that the target has.
292 *
293 * Returns: true if subset else false
294 */
295static inline bool xindex_is_subset(u32 link, u32 target)
296{
297 if (((link & ~AA_X_UNSAFE) != (target & ~AA_X_UNSAFE)) ||
298 ((link & AA_X_UNSAFE) && !(target & AA_X_UNSAFE)))
299 return false;
300
301 return true;
302}
303
304static int profile_path_link(struct aa_profile *profile,
305 const struct path *link, char *buffer,
306 const struct path *target, char *buffer2,
307 struct path_cond *cond)
308{
309 struct aa_ruleset *rules = list_first_entry(&profile->rules,
310 typeof(*rules), list);
311 const char *lname, *tname = NULL;
312 struct aa_perms lperms = {}, perms;
313 const char *info = NULL;
314 u32 request = AA_MAY_LINK;
315 aa_state_t state;
316 int error;
317
318 error = path_name(OP_LINK, &profile->label, link, profile->path_flags,
319 buffer, &lname, cond, AA_MAY_LINK);
320 if (error)
321 goto audit;
322
323 /* buffer2 freed below, tname is pointer in buffer2 */
324 error = path_name(OP_LINK, &profile->label, target, profile->path_flags,
325 buffer2, &tname, cond, AA_MAY_LINK);
326 if (error)
327 goto audit;
328
329 error = -EACCES;
330 /* aa_str_perms - handles the case of the dfa being NULL */
331 state = aa_str_perms(&(rules->file),
332 rules->file.start[AA_CLASS_FILE], lname,
333 cond, &lperms);
334
335 if (!(lperms.allow & AA_MAY_LINK))
336 goto audit;
337
338 /* test to see if target can be paired with link */
339 state = aa_dfa_null_transition(rules->file.dfa, state);
340 aa_str_perms(&(rules->file), state, tname, cond, &perms);
341
342 /* force audit/quiet masks for link are stored in the second entry
343 * in the link pair.
344 */
345 lperms.audit = perms.audit;
346 lperms.quiet = perms.quiet;
347 lperms.kill = perms.kill;
348
349 if (!(perms.allow & AA_MAY_LINK)) {
350 info = "target restricted";
351 lperms = perms;
352 goto audit;
353 }
354
355 /* done if link subset test is not required */
356 if (!(perms.allow & AA_LINK_SUBSET))
357 goto done_tests;
358
359 /* Do link perm subset test requiring allowed permission on link are
360 * a subset of the allowed permissions on target.
361 */
362 aa_str_perms(&(rules->file), rules->file.start[AA_CLASS_FILE],
363 tname, cond, &perms);
364
365 /* AA_MAY_LINK is not considered in the subset test */
366 request = lperms.allow & ~AA_MAY_LINK;
367 lperms.allow &= perms.allow | AA_MAY_LINK;
368
369 request |= AA_AUDIT_FILE_MASK & (lperms.allow & ~perms.allow);
370 if (request & ~lperms.allow) {
371 goto audit;
372 } else if ((lperms.allow & MAY_EXEC) &&
373 !xindex_is_subset(lperms.xindex, perms.xindex)) {
374 lperms.allow &= ~MAY_EXEC;
375 request |= MAY_EXEC;
376 info = "link not subset of target";
377 goto audit;
378 }
379
380done_tests:
381 error = 0;
382
383audit:
384 return aa_audit_file(profile, &lperms, OP_LINK, request, lname, tname,
385 NULL, cond->uid, info, error);
386}
387
388/**
389 * aa_path_link - Handle hard link permission check
390 * @label: the label being enforced (NOT NULL)
391 * @old_dentry: the target dentry (NOT NULL)
392 * @new_dir: directory the new link will be created in (NOT NULL)
393 * @new_dentry: the link being created (NOT NULL)
394 *
395 * Handle the permission test for a link & target pair. Permission
396 * is encoded as a pair where the link permission is determined
397 * first, and if allowed, the target is tested. The target test
398 * is done from the point of the link match (not start of DFA)
399 * making the target permission dependent on the link permission match.
400 *
401 * The subset test if required forces that permissions granted
402 * on link are a subset of the permission granted to target.
403 *
404 * Returns: %0 if allowed else error
405 */
406int aa_path_link(struct aa_label *label, struct dentry *old_dentry,
407 const struct path *new_dir, struct dentry *new_dentry)
408{
409 struct path link = { .mnt = new_dir->mnt, .dentry = new_dentry };
410 struct path target = { .mnt = new_dir->mnt, .dentry = old_dentry };
411 struct path_cond cond = {
412 d_backing_inode(old_dentry)->i_uid,
413 d_backing_inode(old_dentry)->i_mode
414 };
415 char *buffer = NULL, *buffer2 = NULL;
416 struct aa_profile *profile;
417 int error;
418
419 /* buffer freed below, lname is pointer in buffer */
420 buffer = aa_get_buffer(false);
421 buffer2 = aa_get_buffer(false);
422 error = -ENOMEM;
423 if (!buffer || !buffer2)
424 goto out;
425
426 error = fn_for_each_confined(label, profile,
427 profile_path_link(profile, &link, buffer, &target,
428 buffer2, &cond));
429out:
430 aa_put_buffer(buffer);
431 aa_put_buffer(buffer2);
432 return error;
433}
434
435static void update_file_ctx(struct aa_file_ctx *fctx, struct aa_label *label,
436 u32 request)
437{
438 struct aa_label *l, *old;
439
440 /* update caching of label on file_ctx */
441 spin_lock(&fctx->lock);
442 old = rcu_dereference_protected(fctx->label,
443 lockdep_is_held(&fctx->lock));
444 l = aa_label_merge(old, label, GFP_ATOMIC);
445 if (l) {
446 if (l != old) {
447 rcu_assign_pointer(fctx->label, l);
448 aa_put_label(old);
449 } else
450 aa_put_label(l);
451 fctx->allow |= request;
452 }
453 spin_unlock(&fctx->lock);
454}
455
456static int __file_path_perm(const char *op, struct aa_label *label,
457 struct aa_label *flabel, struct file *file,
458 u32 request, u32 denied, bool in_atomic)
459{
460 struct aa_profile *profile;
461 struct aa_perms perms = {};
462 vfsuid_t vfsuid = i_uid_into_vfsuid(file_mnt_user_ns(file),
463 file_inode(file));
464 struct path_cond cond = {
465 .uid = vfsuid_into_kuid(vfsuid),
466 .mode = file_inode(file)->i_mode
467 };
468 char *buffer;
469 int flags, error;
470
471 /* revalidation due to label out of date. No revocation at this time */
472 if (!denied && aa_label_is_subset(flabel, label))
473 /* TODO: check for revocation on stale profiles */
474 return 0;
475
476 flags = PATH_DELEGATE_DELETED | (S_ISDIR(cond.mode) ? PATH_IS_DIR : 0);
477 buffer = aa_get_buffer(in_atomic);
478 if (!buffer)
479 return -ENOMEM;
480
481 /* check every profile in task label not in current cache */
482 error = fn_for_each_not_in_set(flabel, label, profile,
483 profile_path_perm(op, profile, &file->f_path, buffer,
484 request, &cond, flags, &perms));
485 if (denied && !error) {
486 /*
487 * check every profile in file label that was not tested
488 * in the initial check above.
489 *
490 * TODO: cache full perms so this only happens because of
491 * conditionals
492 * TODO: don't audit here
493 */
494 if (label == flabel)
495 error = fn_for_each(label, profile,
496 profile_path_perm(op, profile, &file->f_path,
497 buffer, request, &cond, flags,
498 &perms));
499 else
500 error = fn_for_each_not_in_set(label, flabel, profile,
501 profile_path_perm(op, profile, &file->f_path,
502 buffer, request, &cond, flags,
503 &perms));
504 }
505 if (!error)
506 update_file_ctx(file_ctx(file), label, request);
507
508 aa_put_buffer(buffer);
509
510 return error;
511}
512
513static int __file_sock_perm(const char *op, struct aa_label *label,
514 struct aa_label *flabel, struct file *file,
515 u32 request, u32 denied)
516{
517 struct socket *sock = (struct socket *) file->private_data;
518 int error;
519
520 AA_BUG(!sock);
521
522 /* revalidation due to label out of date. No revocation at this time */
523 if (!denied && aa_label_is_subset(flabel, label))
524 return 0;
525
526 /* TODO: improve to skip profiles cached in flabel */
527 error = aa_sock_file_perm(label, op, request, sock);
528 if (denied) {
529 /* TODO: improve to skip profiles checked above */
530 /* check every profile in file label to is cached */
531 last_error(error, aa_sock_file_perm(flabel, op, request, sock));
532 }
533 if (!error)
534 update_file_ctx(file_ctx(file), label, request);
535
536 return error;
537}
538
539/**
540 * aa_file_perm - do permission revalidation check & audit for @file
541 * @op: operation being checked
542 * @label: label being enforced (NOT NULL)
543 * @file: file to revalidate access permissions on (NOT NULL)
544 * @request: requested permissions
545 * @in_atomic: whether allocations need to be done in atomic context
546 *
547 * Returns: %0 if access allowed else error
548 */
549int aa_file_perm(const char *op, struct aa_label *label, struct file *file,
550 u32 request, bool in_atomic)
551{
552 struct aa_file_ctx *fctx;
553 struct aa_label *flabel;
554 u32 denied;
555 int error = 0;
556
557 AA_BUG(!label);
558 AA_BUG(!file);
559
560 fctx = file_ctx(file);
561
562 rcu_read_lock();
563 flabel = rcu_dereference(fctx->label);
564 AA_BUG(!flabel);
565
566 /* revalidate access, if task is unconfined, or the cached cred
567 * doesn't match or if the request is for more permissions than
568 * was granted.
569 *
570 * Note: the test for !unconfined(flabel) is to handle file
571 * delegation from unconfined tasks
572 */
573 denied = request & ~fctx->allow;
574 if (unconfined(label) || unconfined(flabel) ||
575 (!denied && aa_label_is_subset(flabel, label))) {
576 rcu_read_unlock();
577 goto done;
578 }
579
580 flabel = aa_get_newest_label(flabel);
581 rcu_read_unlock();
582 /* TODO: label cross check */
583
584 if (file->f_path.mnt && path_mediated_fs(file->f_path.dentry))
585 error = __file_path_perm(op, label, flabel, file, request,
586 denied, in_atomic);
587
588 else if (S_ISSOCK(file_inode(file)->i_mode))
589 error = __file_sock_perm(op, label, flabel, file, request,
590 denied);
591 aa_put_label(flabel);
592
593done:
594 return error;
595}
596
597static void revalidate_tty(struct aa_label *label)
598{
599 struct tty_struct *tty;
600 int drop_tty = 0;
601
602 tty = get_current_tty();
603 if (!tty)
604 return;
605
606 spin_lock(&tty->files_lock);
607 if (!list_empty(&tty->tty_files)) {
608 struct tty_file_private *file_priv;
609 struct file *file;
610 /* TODO: Revalidate access to controlling tty. */
611 file_priv = list_first_entry(&tty->tty_files,
612 struct tty_file_private, list);
613 file = file_priv->file;
614
615 if (aa_file_perm(OP_INHERIT, label, file, MAY_READ | MAY_WRITE,
616 IN_ATOMIC))
617 drop_tty = 1;
618 }
619 spin_unlock(&tty->files_lock);
620 tty_kref_put(tty);
621
622 if (drop_tty)
623 no_tty();
624}
625
626static int match_file(const void *p, struct file *file, unsigned int fd)
627{
628 struct aa_label *label = (struct aa_label *)p;
629
630 if (aa_file_perm(OP_INHERIT, label, file, aa_map_file_to_perms(file),
631 IN_ATOMIC))
632 return fd + 1;
633 return 0;
634}
635
636
637/* based on selinux's flush_unauthorized_files */
638void aa_inherit_files(const struct cred *cred, struct files_struct *files)
639{
640 struct aa_label *label = aa_get_newest_cred_label(cred);
641 struct file *devnull = NULL;
642 unsigned int n;
643
644 revalidate_tty(label);
645
646 /* Revalidate access to inherited open files. */
647 n = iterate_fd(files, 0, match_file, label);
648 if (!n) /* none found? */
649 goto out;
650
651 devnull = dentry_open(&aa_null, O_RDWR, cred);
652 if (IS_ERR(devnull))
653 devnull = NULL;
654 /* replace all the matching ones with this */
655 do {
656 replace_fd(n - 1, devnull, 0);
657 } while ((n = iterate_fd(files, n, match_file, label)) != 0);
658 if (devnull)
659 fput(devnull);
660out:
661 aa_put_label(label);
662}