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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 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 struct apparmor_audit_data *ad = aad(sa);
48 kuid_t fsuid = ad->subj_cred ? ad->subj_cred->fsuid : current_fsuid();
49 char str[10];
50
51 if (ad->request & AA_AUDIT_FILE_MASK) {
52 aa_perm_mask_to_str(str, sizeof(str), aa_file_perm_chrs,
53 map_mask_to_chr_mask(ad->request));
54 audit_log_format(ab, " requested_mask=\"%s\"", str);
55 }
56 if (ad->denied & AA_AUDIT_FILE_MASK) {
57 aa_perm_mask_to_str(str, sizeof(str), aa_file_perm_chrs,
58 map_mask_to_chr_mask(ad->denied));
59 audit_log_format(ab, " denied_mask=\"%s\"", str);
60 }
61 if (ad->request & AA_AUDIT_FILE_MASK) {
62 audit_log_format(ab, " fsuid=%d",
63 from_kuid(&init_user_ns, fsuid));
64 audit_log_format(ab, " ouid=%d",
65 from_kuid(&init_user_ns, ad->fs.ouid));
66 }
67
68 if (ad->peer) {
69 audit_log_format(ab, " target=");
70 aa_label_xaudit(ab, labels_ns(ad->subj_label), ad->peer,
71 FLAG_VIEW_SUBNS, GFP_KERNEL);
72 } else if (ad->fs.target) {
73 audit_log_format(ab, " target=");
74 audit_log_untrustedstring(ab, ad->fs.target);
75 }
76}
77
78/**
79 * aa_audit_file - handle the auditing of file operations
80 * @subj_cred: cred of the subject
81 * @profile: the profile being enforced (NOT NULL)
82 * @perms: the permissions computed for the request (NOT NULL)
83 * @op: operation being mediated
84 * @request: permissions requested
85 * @name: name of object being mediated (MAYBE NULL)
86 * @target: name of target (MAYBE NULL)
87 * @tlabel: target label (MAY BE NULL)
88 * @ouid: object uid
89 * @info: extra information message (MAYBE NULL)
90 * @error: 0 if operation allowed else failure error code
91 *
92 * Returns: %0 or error on failure
93 */
94int aa_audit_file(const struct cred *subj_cred,
95 struct aa_profile *profile, struct aa_perms *perms,
96 const char *op, u32 request, const char *name,
97 const char *target, struct aa_label *tlabel,
98 kuid_t ouid, const char *info, int error)
99{
100 int type = AUDIT_APPARMOR_AUTO;
101 DEFINE_AUDIT_DATA(ad, LSM_AUDIT_DATA_TASK, AA_CLASS_FILE, op);
102
103 ad.subj_cred = subj_cred;
104 ad.request = request;
105 ad.name = name;
106 ad.fs.target = target;
107 ad.peer = tlabel;
108 ad.fs.ouid = ouid;
109 ad.info = info;
110 ad.error = error;
111 ad.common.u.tsk = NULL;
112
113 if (likely(!ad.error)) {
114 u32 mask = perms->audit;
115
116 if (unlikely(AUDIT_MODE(profile) == AUDIT_ALL))
117 mask = 0xffff;
118
119 /* mask off perms that are not being force audited */
120 ad.request &= mask;
121
122 if (likely(!ad.request))
123 return 0;
124 type = AUDIT_APPARMOR_AUDIT;
125 } else {
126 /* only report permissions that were denied */
127 ad.request = ad.request & ~perms->allow;
128 AA_BUG(!ad.request);
129
130 if (ad.request & perms->kill)
131 type = AUDIT_APPARMOR_KILL;
132
133 /* quiet known rejects, assumes quiet and kill do not overlap */
134 if ((ad.request & perms->quiet) &&
135 AUDIT_MODE(profile) != AUDIT_NOQUIET &&
136 AUDIT_MODE(profile) != AUDIT_ALL)
137 ad.request &= ~perms->quiet;
138
139 if (!ad.request)
140 return ad.error;
141 }
142
143 ad.denied = ad.request & ~perms->allow;
144 return aa_audit(type, profile, &ad, file_audit_cb);
145}
146
147/**
148 * is_deleted - test if a file has been completely unlinked
149 * @dentry: dentry of file to test for deletion (NOT NULL)
150 *
151 * Returns: true if deleted else false
152 */
153static inline bool is_deleted(struct dentry *dentry)
154{
155 if (d_unlinked(dentry) && d_backing_inode(dentry)->i_nlink == 0)
156 return true;
157 return false;
158}
159
160static int path_name(const char *op, const struct cred *subj_cred,
161 struct aa_label *label,
162 const struct path *path, int flags, char *buffer,
163 const char **name, struct path_cond *cond, u32 request)
164{
165 struct aa_profile *profile;
166 const char *info = NULL;
167 int error;
168
169 error = aa_path_name(path, flags, buffer, name, &info,
170 labels_profile(label)->disconnected);
171 if (error) {
172 fn_for_each_confined(label, profile,
173 aa_audit_file(subj_cred,
174 profile, &nullperms, op, request, *name,
175 NULL, NULL, cond->uid, info, error));
176 return error;
177 }
178
179 return 0;
180}
181
182struct aa_perms default_perms = {};
183/**
184 * aa_lookup_fperms - convert dfa compressed perms to internal perms
185 * @file_rules: the aa_policydb to lookup 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
190 *
191 * Returns: a pointer to a file permission set
192 */
193struct aa_perms *aa_lookup_fperms(struct aa_policydb *file_rules,
194 aa_state_t state, struct path_cond *cond)
195{
196 unsigned int index = ACCEPT_TABLE(file_rules->dfa)[state];
197
198 if (!(file_rules->perms))
199 return &default_perms;
200
201 if (uid_eq(current_fsuid(), cond->uid))
202 return &(file_rules->perms[index]);
203
204 return &(file_rules->perms[index + 1]);
205}
206
207/**
208 * aa_str_perms - find permission that match @name
209 * @file_rules: the aa_policydb to match against (NOT NULL)
210 * @start: state to start matching in
211 * @name: string to match against dfa (NOT NULL)
212 * @cond: conditions to consider for permission set computation (NOT NULL)
213 * @perms: Returns - the permissions found when matching @name
214 *
215 * Returns: the final state in @dfa when beginning @start and walking @name
216 */
217aa_state_t aa_str_perms(struct aa_policydb *file_rules, aa_state_t start,
218 const char *name, struct path_cond *cond,
219 struct aa_perms *perms)
220{
221 aa_state_t state;
222 state = aa_dfa_match(file_rules->dfa, start, name);
223 *perms = *(aa_lookup_fperms(file_rules, state, cond));
224
225 return state;
226}
227
228static int __aa_path_perm(const char *op, const struct cred *subj_cred,
229 struct aa_profile *profile, const char *name,
230 u32 request, struct path_cond *cond, int flags,
231 struct aa_perms *perms)
232{
233 struct aa_ruleset *rules = list_first_entry(&profile->rules,
234 typeof(*rules), list);
235 int e = 0;
236
237 if (profile_unconfined(profile))
238 return 0;
239 aa_str_perms(rules->file, rules->file->start[AA_CLASS_FILE],
240 name, cond, perms);
241 if (request & ~perms->allow)
242 e = -EACCES;
243 return aa_audit_file(subj_cred,
244 profile, perms, op, request, name, NULL, NULL,
245 cond->uid, NULL, e);
246}
247
248
249static int profile_path_perm(const char *op, const struct cred *subj_cred,
250 struct aa_profile *profile,
251 const struct path *path, char *buffer, u32 request,
252 struct path_cond *cond, int flags,
253 struct aa_perms *perms)
254{
255 const char *name;
256 int error;
257
258 if (profile_unconfined(profile))
259 return 0;
260
261 error = path_name(op, subj_cred, &profile->label, path,
262 flags | profile->path_flags, buffer, &name, cond,
263 request);
264 if (error)
265 return error;
266 return __aa_path_perm(op, subj_cred, profile, name, request, cond,
267 flags, perms);
268}
269
270/**
271 * aa_path_perm - do permissions check & audit for @path
272 * @op: operation being checked
273 * @subj_cred: subject cred
274 * @label: profile being enforced (NOT NULL)
275 * @path: path to check permissions of (NOT NULL)
276 * @flags: any additional path flags beyond what the profile specifies
277 * @request: requested permissions
278 * @cond: conditional info for this request (NOT NULL)
279 *
280 * Returns: %0 else error if access denied or other error
281 */
282int aa_path_perm(const char *op, const struct cred *subj_cred,
283 struct aa_label *label,
284 const struct path *path, int flags, u32 request,
285 struct path_cond *cond)
286{
287 struct aa_perms perms = {};
288 struct aa_profile *profile;
289 char *buffer = NULL;
290 int error;
291
292 flags |= PATH_DELEGATE_DELETED | (S_ISDIR(cond->mode) ? PATH_IS_DIR :
293 0);
294 buffer = aa_get_buffer(false);
295 if (!buffer)
296 return -ENOMEM;
297 error = fn_for_each_confined(label, profile,
298 profile_path_perm(op, subj_cred, profile, path, buffer,
299 request, cond, flags, &perms));
300
301 aa_put_buffer(buffer);
302
303 return error;
304}
305
306/**
307 * xindex_is_subset - helper for aa_path_link
308 * @link: link permission set
309 * @target: target permission set
310 *
311 * test target x permissions are equal OR a subset of link x permissions
312 * this is done as part of the subset test, where a hardlink must have
313 * a subset of permissions that the target has.
314 *
315 * Returns: true if subset else false
316 */
317static inline bool xindex_is_subset(u32 link, u32 target)
318{
319 if (((link & ~AA_X_UNSAFE) != (target & ~AA_X_UNSAFE)) ||
320 ((link & AA_X_UNSAFE) && !(target & AA_X_UNSAFE)))
321 return false;
322
323 return true;
324}
325
326static int profile_path_link(const struct cred *subj_cred,
327 struct aa_profile *profile,
328 const struct path *link, char *buffer,
329 const struct path *target, char *buffer2,
330 struct path_cond *cond)
331{
332 struct aa_ruleset *rules = list_first_entry(&profile->rules,
333 typeof(*rules), list);
334 const char *lname, *tname = NULL;
335 struct aa_perms lperms = {}, perms;
336 const char *info = NULL;
337 u32 request = AA_MAY_LINK;
338 aa_state_t state;
339 int error;
340
341 error = path_name(OP_LINK, subj_cred, &profile->label, link,
342 profile->path_flags,
343 buffer, &lname, cond, AA_MAY_LINK);
344 if (error)
345 goto audit;
346
347 /* buffer2 freed below, tname is pointer in buffer2 */
348 error = path_name(OP_LINK, subj_cred, &profile->label, target,
349 profile->path_flags,
350 buffer2, &tname, cond, AA_MAY_LINK);
351 if (error)
352 goto audit;
353
354 error = -EACCES;
355 /* aa_str_perms - handles the case of the dfa being NULL */
356 state = aa_str_perms(rules->file,
357 rules->file->start[AA_CLASS_FILE], lname,
358 cond, &lperms);
359
360 if (!(lperms.allow & AA_MAY_LINK))
361 goto audit;
362
363 /* test to see if target can be paired with link */
364 state = aa_dfa_null_transition(rules->file->dfa, state);
365 aa_str_perms(rules->file, state, tname, cond, &perms);
366
367 /* force audit/quiet masks for link are stored in the second entry
368 * in the link pair.
369 */
370 lperms.audit = perms.audit;
371 lperms.quiet = perms.quiet;
372 lperms.kill = perms.kill;
373
374 if (!(perms.allow & AA_MAY_LINK)) {
375 info = "target restricted";
376 lperms = perms;
377 goto audit;
378 }
379
380 /* done if link subset test is not required */
381 if (!(perms.allow & AA_LINK_SUBSET))
382 goto done_tests;
383
384 /* Do link perm subset test requiring allowed permission on link are
385 * a subset of the allowed permissions on target.
386 */
387 aa_str_perms(rules->file, rules->file->start[AA_CLASS_FILE],
388 tname, cond, &perms);
389
390 /* AA_MAY_LINK is not considered in the subset test */
391 request = lperms.allow & ~AA_MAY_LINK;
392 lperms.allow &= perms.allow | AA_MAY_LINK;
393
394 request |= AA_AUDIT_FILE_MASK & (lperms.allow & ~perms.allow);
395 if (request & ~lperms.allow) {
396 goto audit;
397 } else if ((lperms.allow & MAY_EXEC) &&
398 !xindex_is_subset(lperms.xindex, perms.xindex)) {
399 lperms.allow &= ~MAY_EXEC;
400 request |= MAY_EXEC;
401 info = "link not subset of target";
402 goto audit;
403 }
404
405done_tests:
406 error = 0;
407
408audit:
409 return aa_audit_file(subj_cred,
410 profile, &lperms, OP_LINK, request, lname, tname,
411 NULL, cond->uid, info, error);
412}
413
414/**
415 * aa_path_link - Handle hard link permission check
416 * @subj_cred: subject cred
417 * @label: the label being enforced (NOT NULL)
418 * @old_dentry: the target dentry (NOT NULL)
419 * @new_dir: directory the new link will be created in (NOT NULL)
420 * @new_dentry: the link being created (NOT NULL)
421 *
422 * Handle the permission test for a link & target pair. Permission
423 * is encoded as a pair where the link permission is determined
424 * first, and if allowed, the target is tested. The target test
425 * is done from the point of the link match (not start of DFA)
426 * making the target permission dependent on the link permission match.
427 *
428 * The subset test if required forces that permissions granted
429 * on link are a subset of the permission granted to target.
430 *
431 * Returns: %0 if allowed else error
432 */
433int aa_path_link(const struct cred *subj_cred,
434 struct aa_label *label, struct dentry *old_dentry,
435 const struct path *new_dir, struct dentry *new_dentry)
436{
437 struct path link = { .mnt = new_dir->mnt, .dentry = new_dentry };
438 struct path target = { .mnt = new_dir->mnt, .dentry = old_dentry };
439 struct path_cond cond = {
440 d_backing_inode(old_dentry)->i_uid,
441 d_backing_inode(old_dentry)->i_mode
442 };
443 char *buffer = NULL, *buffer2 = NULL;
444 struct aa_profile *profile;
445 int error;
446
447 /* buffer freed below, lname is pointer in buffer */
448 buffer = aa_get_buffer(false);
449 buffer2 = aa_get_buffer(false);
450 error = -ENOMEM;
451 if (!buffer || !buffer2)
452 goto out;
453
454 error = fn_for_each_confined(label, profile,
455 profile_path_link(subj_cred, profile, &link, buffer,
456 &target, buffer2, &cond));
457out:
458 aa_put_buffer(buffer);
459 aa_put_buffer(buffer2);
460 return error;
461}
462
463static void update_file_ctx(struct aa_file_ctx *fctx, struct aa_label *label,
464 u32 request)
465{
466 struct aa_label *l, *old;
467
468 /* update caching of label on file_ctx */
469 spin_lock(&fctx->lock);
470 old = rcu_dereference_protected(fctx->label,
471 lockdep_is_held(&fctx->lock));
472 l = aa_label_merge(old, label, GFP_ATOMIC);
473 if (l) {
474 if (l != old) {
475 rcu_assign_pointer(fctx->label, l);
476 aa_put_label(old);
477 } else
478 aa_put_label(l);
479 fctx->allow |= request;
480 }
481 spin_unlock(&fctx->lock);
482}
483
484static int __file_path_perm(const char *op, const struct cred *subj_cred,
485 struct aa_label *label,
486 struct aa_label *flabel, struct file *file,
487 u32 request, u32 denied, bool in_atomic)
488{
489 struct aa_profile *profile;
490 struct aa_perms perms = {};
491 vfsuid_t vfsuid = i_uid_into_vfsuid(file_mnt_idmap(file),
492 file_inode(file));
493 struct path_cond cond = {
494 .uid = vfsuid_into_kuid(vfsuid),
495 .mode = file_inode(file)->i_mode
496 };
497 char *buffer;
498 int flags, error;
499
500 /* revalidation due to label out of date. No revocation at this time */
501 if (!denied && aa_label_is_subset(flabel, label))
502 /* TODO: check for revocation on stale profiles */
503 return 0;
504
505 flags = PATH_DELEGATE_DELETED | (S_ISDIR(cond.mode) ? PATH_IS_DIR : 0);
506 buffer = aa_get_buffer(in_atomic);
507 if (!buffer)
508 return -ENOMEM;
509
510 /* check every profile in task label not in current cache */
511 error = fn_for_each_not_in_set(flabel, label, profile,
512 profile_path_perm(op, subj_cred, profile,
513 &file->f_path, buffer,
514 request, &cond, flags, &perms));
515 if (denied && !error) {
516 /*
517 * check every profile in file label that was not tested
518 * in the initial check above.
519 *
520 * TODO: cache full perms so this only happens because of
521 * conditionals
522 * TODO: don't audit here
523 */
524 if (label == flabel)
525 error = fn_for_each(label, profile,
526 profile_path_perm(op, subj_cred,
527 profile, &file->f_path,
528 buffer, request, &cond, flags,
529 &perms));
530 else
531 error = fn_for_each_not_in_set(label, flabel, profile,
532 profile_path_perm(op, subj_cred,
533 profile, &file->f_path,
534 buffer, request, &cond, flags,
535 &perms));
536 }
537 if (!error)
538 update_file_ctx(file_ctx(file), label, request);
539
540 aa_put_buffer(buffer);
541
542 return error;
543}
544
545static int __file_sock_perm(const char *op, const struct cred *subj_cred,
546 struct aa_label *label,
547 struct aa_label *flabel, struct file *file,
548 u32 request, u32 denied)
549{
550 struct socket *sock = (struct socket *) file->private_data;
551 int error;
552
553 AA_BUG(!sock);
554
555 /* revalidation due to label out of date. No revocation at this time */
556 if (!denied && aa_label_is_subset(flabel, label))
557 return 0;
558
559 /* TODO: improve to skip profiles cached in flabel */
560 error = aa_sock_file_perm(subj_cred, label, op, request, sock);
561 if (denied) {
562 /* TODO: improve to skip profiles checked above */
563 /* check every profile in file label to is cached */
564 last_error(error, aa_sock_file_perm(subj_cred, flabel, op,
565 request, sock));
566 }
567 if (!error)
568 update_file_ctx(file_ctx(file), label, request);
569
570 return error;
571}
572
573/**
574 * aa_file_perm - do permission revalidation check & audit for @file
575 * @op: operation being checked
576 * @subj_cred: subject cred
577 * @label: label being enforced (NOT NULL)
578 * @file: file to revalidate access permissions on (NOT NULL)
579 * @request: requested permissions
580 * @in_atomic: whether allocations need to be done in atomic context
581 *
582 * Returns: %0 if access allowed else error
583 */
584int aa_file_perm(const char *op, const struct cred *subj_cred,
585 struct aa_label *label, struct file *file,
586 u32 request, bool in_atomic)
587{
588 struct aa_file_ctx *fctx;
589 struct aa_label *flabel;
590 u32 denied;
591 int error = 0;
592
593 AA_BUG(!label);
594 AA_BUG(!file);
595
596 fctx = file_ctx(file);
597
598 rcu_read_lock();
599 flabel = rcu_dereference(fctx->label);
600 AA_BUG(!flabel);
601
602 /* revalidate access, if task is unconfined, or the cached cred
603 * doesn't match or if the request is for more permissions than
604 * was granted.
605 *
606 * Note: the test for !unconfined(flabel) is to handle file
607 * delegation from unconfined tasks
608 */
609 denied = request & ~fctx->allow;
610 if (unconfined(label) || unconfined(flabel) ||
611 (!denied && aa_label_is_subset(flabel, label))) {
612 rcu_read_unlock();
613 goto done;
614 }
615
616 flabel = aa_get_newest_label(flabel);
617 rcu_read_unlock();
618 /* TODO: label cross check */
619
620 if (file->f_path.mnt && path_mediated_fs(file->f_path.dentry))
621 error = __file_path_perm(op, subj_cred, label, flabel, file,
622 request, denied, in_atomic);
623
624 else if (S_ISSOCK(file_inode(file)->i_mode))
625 error = __file_sock_perm(op, subj_cred, label, flabel, file,
626 request, denied);
627 aa_put_label(flabel);
628
629done:
630 return error;
631}
632
633static void revalidate_tty(const struct cred *subj_cred, struct aa_label *label)
634{
635 struct tty_struct *tty;
636 int drop_tty = 0;
637
638 tty = get_current_tty();
639 if (!tty)
640 return;
641
642 spin_lock(&tty->files_lock);
643 if (!list_empty(&tty->tty_files)) {
644 struct tty_file_private *file_priv;
645 struct file *file;
646 /* TODO: Revalidate access to controlling tty. */
647 file_priv = list_first_entry(&tty->tty_files,
648 struct tty_file_private, list);
649 file = file_priv->file;
650
651 if (aa_file_perm(OP_INHERIT, subj_cred, label, file,
652 MAY_READ | MAY_WRITE, IN_ATOMIC))
653 drop_tty = 1;
654 }
655 spin_unlock(&tty->files_lock);
656 tty_kref_put(tty);
657
658 if (drop_tty)
659 no_tty();
660}
661
662struct cred_label {
663 const struct cred *cred;
664 struct aa_label *label;
665};
666
667static int match_file(const void *p, struct file *file, unsigned int fd)
668{
669 struct cred_label *cl = (struct cred_label *)p;
670
671 if (aa_file_perm(OP_INHERIT, cl->cred, cl->label, file,
672 aa_map_file_to_perms(file), IN_ATOMIC))
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 cred_label cl = {
683 .cred = cred,
684 .label = label,
685 };
686 struct file *devnull = NULL;
687 unsigned int n;
688
689 revalidate_tty(cred, label);
690
691 /* Revalidate access to inherited open files. */
692 n = iterate_fd(files, 0, match_file, &cl);
693 if (!n) /* none found? */
694 goto out;
695
696 devnull = dentry_open(&aa_null, O_RDWR, cred);
697 if (IS_ERR(devnull))
698 devnull = NULL;
699 /* replace all the matching ones with this */
700 do {
701 replace_fd(n - 1, devnull, 0);
702 } while ((n = iterate_fd(files, n, match_file, &cl)) != 0);
703 if (devnull)
704 fput(devnull);
705out:
706 aa_put_label(label);
707}