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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright (C) 2005-2010 IBM Corporation
4 *
5 * Author:
6 * Mimi Zohar <zohar@us.ibm.com>
7 * Kylene Hall <kjhall@us.ibm.com>
8 *
9 * File: evm_main.c
10 * implements evm_inode_setxattr, evm_inode_post_setxattr,
11 * evm_inode_removexattr, and evm_verifyxattr
12 */
13
14#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
15
16#include <linux/init.h>
17#include <linux/crypto.h>
18#include <linux/audit.h>
19#include <linux/xattr.h>
20#include <linux/integrity.h>
21#include <linux/evm.h>
22#include <linux/magic.h>
23
24#include <crypto/hash.h>
25#include <crypto/hash_info.h>
26#include <crypto/algapi.h>
27#include "evm.h"
28
29int evm_initialized;
30
31static const char * const integrity_status_msg[] = {
32 "pass", "pass_immutable", "fail", "no_label", "no_xattrs", "unknown"
33};
34int evm_hmac_attrs;
35
36static struct xattr_list evm_config_default_xattrnames[] = {
37#ifdef CONFIG_SECURITY_SELINUX
38 {.name = XATTR_NAME_SELINUX},
39#endif
40#ifdef CONFIG_SECURITY_SMACK
41 {.name = XATTR_NAME_SMACK},
42#ifdef CONFIG_EVM_EXTRA_SMACK_XATTRS
43 {.name = XATTR_NAME_SMACKEXEC},
44 {.name = XATTR_NAME_SMACKTRANSMUTE},
45 {.name = XATTR_NAME_SMACKMMAP},
46#endif
47#endif
48#ifdef CONFIG_SECURITY_APPARMOR
49 {.name = XATTR_NAME_APPARMOR},
50#endif
51#ifdef CONFIG_IMA_APPRAISE
52 {.name = XATTR_NAME_IMA},
53#endif
54 {.name = XATTR_NAME_CAPS},
55};
56
57LIST_HEAD(evm_config_xattrnames);
58
59static int evm_fixmode;
60static int __init evm_set_fixmode(char *str)
61{
62 if (strncmp(str, "fix", 3) == 0)
63 evm_fixmode = 1;
64 return 0;
65}
66__setup("evm=", evm_set_fixmode);
67
68static void __init evm_init_config(void)
69{
70 int i, xattrs;
71
72 xattrs = ARRAY_SIZE(evm_config_default_xattrnames);
73
74 pr_info("Initialising EVM extended attributes:\n");
75 for (i = 0; i < xattrs; i++) {
76 pr_info("%s\n", evm_config_default_xattrnames[i].name);
77 list_add_tail(&evm_config_default_xattrnames[i].list,
78 &evm_config_xattrnames);
79 }
80
81#ifdef CONFIG_EVM_ATTR_FSUUID
82 evm_hmac_attrs |= EVM_ATTR_FSUUID;
83#endif
84 pr_info("HMAC attrs: 0x%x\n", evm_hmac_attrs);
85}
86
87static bool evm_key_loaded(void)
88{
89 return (bool)(evm_initialized & EVM_KEY_MASK);
90}
91
92static int evm_find_protected_xattrs(struct dentry *dentry)
93{
94 struct inode *inode = d_backing_inode(dentry);
95 struct xattr_list *xattr;
96 int error;
97 int count = 0;
98
99 if (!(inode->i_opflags & IOP_XATTR))
100 return -EOPNOTSUPP;
101
102 list_for_each_entry_rcu(xattr, &evm_config_xattrnames, list) {
103 error = __vfs_getxattr(dentry, inode, xattr->name, NULL, 0);
104 if (error < 0) {
105 if (error == -ENODATA)
106 continue;
107 return error;
108 }
109 count++;
110 }
111
112 return count;
113}
114
115/*
116 * evm_verify_hmac - calculate and compare the HMAC with the EVM xattr
117 *
118 * Compute the HMAC on the dentry's protected set of extended attributes
119 * and compare it against the stored security.evm xattr.
120 *
121 * For performance:
122 * - use the previoulsy retrieved xattr value and length to calculate the
123 * HMAC.)
124 * - cache the verification result in the iint, when available.
125 *
126 * Returns integrity status
127 */
128static enum integrity_status evm_verify_hmac(struct dentry *dentry,
129 const char *xattr_name,
130 char *xattr_value,
131 size_t xattr_value_len,
132 struct integrity_iint_cache *iint)
133{
134 struct evm_ima_xattr_data *xattr_data = NULL;
135 struct signature_v2_hdr *hdr;
136 enum integrity_status evm_status = INTEGRITY_PASS;
137 struct evm_digest digest;
138 struct inode *inode;
139 int rc, xattr_len;
140
141 if (iint && (iint->evm_status == INTEGRITY_PASS ||
142 iint->evm_status == INTEGRITY_PASS_IMMUTABLE))
143 return iint->evm_status;
144
145 /* if status is not PASS, try to check again - against -ENOMEM */
146
147 /* first need to know the sig type */
148 rc = vfs_getxattr_alloc(dentry, XATTR_NAME_EVM, (char **)&xattr_data, 0,
149 GFP_NOFS);
150 if (rc <= 0) {
151 evm_status = INTEGRITY_FAIL;
152 if (rc == -ENODATA) {
153 rc = evm_find_protected_xattrs(dentry);
154 if (rc > 0)
155 evm_status = INTEGRITY_NOLABEL;
156 else if (rc == 0)
157 evm_status = INTEGRITY_NOXATTRS; /* new file */
158 } else if (rc == -EOPNOTSUPP) {
159 evm_status = INTEGRITY_UNKNOWN;
160 }
161 goto out;
162 }
163
164 xattr_len = rc;
165
166 /* check value type */
167 switch (xattr_data->type) {
168 case EVM_XATTR_HMAC:
169 if (xattr_len != sizeof(struct evm_xattr)) {
170 evm_status = INTEGRITY_FAIL;
171 goto out;
172 }
173
174 digest.hdr.algo = HASH_ALGO_SHA1;
175 rc = evm_calc_hmac(dentry, xattr_name, xattr_value,
176 xattr_value_len, &digest);
177 if (rc)
178 break;
179 rc = crypto_memneq(xattr_data->data, digest.digest,
180 SHA1_DIGEST_SIZE);
181 if (rc)
182 rc = -EINVAL;
183 break;
184 case EVM_IMA_XATTR_DIGSIG:
185 case EVM_XATTR_PORTABLE_DIGSIG:
186 hdr = (struct signature_v2_hdr *)xattr_data;
187 digest.hdr.algo = hdr->hash_algo;
188 rc = evm_calc_hash(dentry, xattr_name, xattr_value,
189 xattr_value_len, xattr_data->type, &digest);
190 if (rc)
191 break;
192 rc = integrity_digsig_verify(INTEGRITY_KEYRING_EVM,
193 (const char *)xattr_data, xattr_len,
194 digest.digest, digest.hdr.length);
195 if (!rc) {
196 inode = d_backing_inode(dentry);
197
198 if (xattr_data->type == EVM_XATTR_PORTABLE_DIGSIG) {
199 if (iint)
200 iint->flags |= EVM_IMMUTABLE_DIGSIG;
201 evm_status = INTEGRITY_PASS_IMMUTABLE;
202 } else if (!IS_RDONLY(inode) &&
203 !(inode->i_sb->s_readonly_remount) &&
204 !IS_IMMUTABLE(inode)) {
205 evm_update_evmxattr(dentry, xattr_name,
206 xattr_value,
207 xattr_value_len);
208 }
209 }
210 break;
211 default:
212 rc = -EINVAL;
213 break;
214 }
215
216 if (rc)
217 evm_status = (rc == -ENODATA) ?
218 INTEGRITY_NOXATTRS : INTEGRITY_FAIL;
219out:
220 if (iint)
221 iint->evm_status = evm_status;
222 kfree(xattr_data);
223 return evm_status;
224}
225
226static int evm_protected_xattr(const char *req_xattr_name)
227{
228 int namelen;
229 int found = 0;
230 struct xattr_list *xattr;
231
232 namelen = strlen(req_xattr_name);
233 list_for_each_entry_rcu(xattr, &evm_config_xattrnames, list) {
234 if ((strlen(xattr->name) == namelen)
235 && (strncmp(req_xattr_name, xattr->name, namelen) == 0)) {
236 found = 1;
237 break;
238 }
239 if (strncmp(req_xattr_name,
240 xattr->name + XATTR_SECURITY_PREFIX_LEN,
241 strlen(req_xattr_name)) == 0) {
242 found = 1;
243 break;
244 }
245 }
246
247 return found;
248}
249
250/**
251 * evm_verifyxattr - verify the integrity of the requested xattr
252 * @dentry: object of the verify xattr
253 * @xattr_name: requested xattr
254 * @xattr_value: requested xattr value
255 * @xattr_value_len: requested xattr value length
256 *
257 * Calculate the HMAC for the given dentry and verify it against the stored
258 * security.evm xattr. For performance, use the xattr value and length
259 * previously retrieved to calculate the HMAC.
260 *
261 * Returns the xattr integrity status.
262 *
263 * This function requires the caller to lock the inode's i_mutex before it
264 * is executed.
265 */
266enum integrity_status evm_verifyxattr(struct dentry *dentry,
267 const char *xattr_name,
268 void *xattr_value, size_t xattr_value_len,
269 struct integrity_iint_cache *iint)
270{
271 if (!evm_key_loaded() || !evm_protected_xattr(xattr_name))
272 return INTEGRITY_UNKNOWN;
273
274 if (!iint) {
275 iint = integrity_iint_find(d_backing_inode(dentry));
276 if (!iint)
277 return INTEGRITY_UNKNOWN;
278 }
279 return evm_verify_hmac(dentry, xattr_name, xattr_value,
280 xattr_value_len, iint);
281}
282EXPORT_SYMBOL_GPL(evm_verifyxattr);
283
284/*
285 * evm_verify_current_integrity - verify the dentry's metadata integrity
286 * @dentry: pointer to the affected dentry
287 *
288 * Verify and return the dentry's metadata integrity. The exceptions are
289 * before EVM is initialized or in 'fix' mode.
290 */
291static enum integrity_status evm_verify_current_integrity(struct dentry *dentry)
292{
293 struct inode *inode = d_backing_inode(dentry);
294
295 if (!evm_key_loaded() || !S_ISREG(inode->i_mode) || evm_fixmode)
296 return 0;
297 return evm_verify_hmac(dentry, NULL, NULL, 0, NULL);
298}
299
300/*
301 * evm_protect_xattr - protect the EVM extended attribute
302 *
303 * Prevent security.evm from being modified or removed without the
304 * necessary permissions or when the existing value is invalid.
305 *
306 * The posix xattr acls are 'system' prefixed, which normally would not
307 * affect security.evm. An interesting side affect of writing posix xattr
308 * acls is their modifying of the i_mode, which is included in security.evm.
309 * For posix xattr acls only, permit security.evm, even if it currently
310 * doesn't exist, to be updated unless the EVM signature is immutable.
311 */
312static int evm_protect_xattr(struct dentry *dentry, const char *xattr_name,
313 const void *xattr_value, size_t xattr_value_len)
314{
315 enum integrity_status evm_status;
316
317 if (strcmp(xattr_name, XATTR_NAME_EVM) == 0) {
318 if (!capable(CAP_SYS_ADMIN))
319 return -EPERM;
320 } else if (!evm_protected_xattr(xattr_name)) {
321 if (!posix_xattr_acl(xattr_name))
322 return 0;
323 evm_status = evm_verify_current_integrity(dentry);
324 if ((evm_status == INTEGRITY_PASS) ||
325 (evm_status == INTEGRITY_NOXATTRS))
326 return 0;
327 goto out;
328 }
329
330 evm_status = evm_verify_current_integrity(dentry);
331 if (evm_status == INTEGRITY_NOXATTRS) {
332 struct integrity_iint_cache *iint;
333
334 iint = integrity_iint_find(d_backing_inode(dentry));
335 if (iint && (iint->flags & IMA_NEW_FILE))
336 return 0;
337
338 /* exception for pseudo filesystems */
339 if (dentry->d_sb->s_magic == TMPFS_MAGIC
340 || dentry->d_sb->s_magic == SYSFS_MAGIC)
341 return 0;
342
343 integrity_audit_msg(AUDIT_INTEGRITY_METADATA,
344 dentry->d_inode, dentry->d_name.name,
345 "update_metadata",
346 integrity_status_msg[evm_status],
347 -EPERM, 0);
348 }
349out:
350 if (evm_status != INTEGRITY_PASS)
351 integrity_audit_msg(AUDIT_INTEGRITY_METADATA, d_backing_inode(dentry),
352 dentry->d_name.name, "appraise_metadata",
353 integrity_status_msg[evm_status],
354 -EPERM, 0);
355 return evm_status == INTEGRITY_PASS ? 0 : -EPERM;
356}
357
358/**
359 * evm_inode_setxattr - protect the EVM extended attribute
360 * @dentry: pointer to the affected dentry
361 * @xattr_name: pointer to the affected extended attribute name
362 * @xattr_value: pointer to the new extended attribute value
363 * @xattr_value_len: pointer to the new extended attribute value length
364 *
365 * Before allowing the 'security.evm' protected xattr to be updated,
366 * verify the existing value is valid. As only the kernel should have
367 * access to the EVM encrypted key needed to calculate the HMAC, prevent
368 * userspace from writing HMAC value. Writing 'security.evm' requires
369 * requires CAP_SYS_ADMIN privileges.
370 */
371int evm_inode_setxattr(struct dentry *dentry, const char *xattr_name,
372 const void *xattr_value, size_t xattr_value_len)
373{
374 const struct evm_ima_xattr_data *xattr_data = xattr_value;
375
376 /* Policy permits modification of the protected xattrs even though
377 * there's no HMAC key loaded
378 */
379 if (evm_initialized & EVM_ALLOW_METADATA_WRITES)
380 return 0;
381
382 if (strcmp(xattr_name, XATTR_NAME_EVM) == 0) {
383 if (!xattr_value_len)
384 return -EINVAL;
385 if (xattr_data->type != EVM_IMA_XATTR_DIGSIG &&
386 xattr_data->type != EVM_XATTR_PORTABLE_DIGSIG)
387 return -EPERM;
388 }
389 return evm_protect_xattr(dentry, xattr_name, xattr_value,
390 xattr_value_len);
391}
392
393/**
394 * evm_inode_removexattr - protect the EVM extended attribute
395 * @dentry: pointer to the affected dentry
396 * @xattr_name: pointer to the affected extended attribute name
397 *
398 * Removing 'security.evm' requires CAP_SYS_ADMIN privileges and that
399 * the current value is valid.
400 */
401int evm_inode_removexattr(struct dentry *dentry, const char *xattr_name)
402{
403 /* Policy permits modification of the protected xattrs even though
404 * there's no HMAC key loaded
405 */
406 if (evm_initialized & EVM_ALLOW_METADATA_WRITES)
407 return 0;
408
409 return evm_protect_xattr(dentry, xattr_name, NULL, 0);
410}
411
412static void evm_reset_status(struct inode *inode)
413{
414 struct integrity_iint_cache *iint;
415
416 iint = integrity_iint_find(inode);
417 if (iint)
418 iint->evm_status = INTEGRITY_UNKNOWN;
419}
420
421/**
422 * evm_inode_post_setxattr - update 'security.evm' to reflect the changes
423 * @dentry: pointer to the affected dentry
424 * @xattr_name: pointer to the affected extended attribute name
425 * @xattr_value: pointer to the new extended attribute value
426 * @xattr_value_len: pointer to the new extended attribute value length
427 *
428 * Update the HMAC stored in 'security.evm' to reflect the change.
429 *
430 * No need to take the i_mutex lock here, as this function is called from
431 * __vfs_setxattr_noperm(). The caller of which has taken the inode's
432 * i_mutex lock.
433 */
434void evm_inode_post_setxattr(struct dentry *dentry, const char *xattr_name,
435 const void *xattr_value, size_t xattr_value_len)
436{
437 if (!evm_key_loaded() || (!evm_protected_xattr(xattr_name)
438 && !posix_xattr_acl(xattr_name)))
439 return;
440
441 evm_reset_status(dentry->d_inode);
442
443 evm_update_evmxattr(dentry, xattr_name, xattr_value, xattr_value_len);
444}
445
446/**
447 * evm_inode_post_removexattr - update 'security.evm' after removing the xattr
448 * @dentry: pointer to the affected dentry
449 * @xattr_name: pointer to the affected extended attribute name
450 *
451 * Update the HMAC stored in 'security.evm' to reflect removal of the xattr.
452 *
453 * No need to take the i_mutex lock here, as this function is called from
454 * vfs_removexattr() which takes the i_mutex.
455 */
456void evm_inode_post_removexattr(struct dentry *dentry, const char *xattr_name)
457{
458 if (!evm_key_loaded() || !evm_protected_xattr(xattr_name))
459 return;
460
461 evm_reset_status(dentry->d_inode);
462
463 evm_update_evmxattr(dentry, xattr_name, NULL, 0);
464}
465
466/**
467 * evm_inode_setattr - prevent updating an invalid EVM extended attribute
468 * @dentry: pointer to the affected dentry
469 *
470 * Permit update of file attributes when files have a valid EVM signature,
471 * except in the case of them having an immutable portable signature.
472 */
473int evm_inode_setattr(struct dentry *dentry, struct iattr *attr)
474{
475 unsigned int ia_valid = attr->ia_valid;
476 enum integrity_status evm_status;
477
478 /* Policy permits modification of the protected attrs even though
479 * there's no HMAC key loaded
480 */
481 if (evm_initialized & EVM_ALLOW_METADATA_WRITES)
482 return 0;
483
484 if (!(ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID)))
485 return 0;
486 evm_status = evm_verify_current_integrity(dentry);
487 if ((evm_status == INTEGRITY_PASS) ||
488 (evm_status == INTEGRITY_NOXATTRS))
489 return 0;
490 integrity_audit_msg(AUDIT_INTEGRITY_METADATA, d_backing_inode(dentry),
491 dentry->d_name.name, "appraise_metadata",
492 integrity_status_msg[evm_status], -EPERM, 0);
493 return -EPERM;
494}
495
496/**
497 * evm_inode_post_setattr - update 'security.evm' after modifying metadata
498 * @dentry: pointer to the affected dentry
499 * @ia_valid: for the UID and GID status
500 *
501 * For now, update the HMAC stored in 'security.evm' to reflect UID/GID
502 * changes.
503 *
504 * This function is called from notify_change(), which expects the caller
505 * to lock the inode's i_mutex.
506 */
507void evm_inode_post_setattr(struct dentry *dentry, int ia_valid)
508{
509 if (!evm_key_loaded())
510 return;
511
512 if (ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID))
513 evm_update_evmxattr(dentry, NULL, NULL, 0);
514}
515
516/*
517 * evm_inode_init_security - initializes security.evm
518 */
519int evm_inode_init_security(struct inode *inode,
520 const struct xattr *lsm_xattr,
521 struct xattr *evm_xattr)
522{
523 struct evm_xattr *xattr_data;
524 int rc;
525
526 if (!evm_key_loaded() || !evm_protected_xattr(lsm_xattr->name))
527 return 0;
528
529 xattr_data = kzalloc(sizeof(*xattr_data), GFP_NOFS);
530 if (!xattr_data)
531 return -ENOMEM;
532
533 xattr_data->data.type = EVM_XATTR_HMAC;
534 rc = evm_init_hmac(inode, lsm_xattr, xattr_data->digest);
535 if (rc < 0)
536 goto out;
537
538 evm_xattr->value = xattr_data;
539 evm_xattr->value_len = sizeof(*xattr_data);
540 evm_xattr->name = XATTR_EVM_SUFFIX;
541 return 0;
542out:
543 kfree(xattr_data);
544 return rc;
545}
546EXPORT_SYMBOL_GPL(evm_inode_init_security);
547
548#ifdef CONFIG_EVM_LOAD_X509
549void __init evm_load_x509(void)
550{
551 int rc;
552
553 rc = integrity_load_x509(INTEGRITY_KEYRING_EVM, CONFIG_EVM_X509_PATH);
554 if (!rc)
555 evm_initialized |= EVM_INIT_X509;
556}
557#endif
558
559static int __init init_evm(void)
560{
561 int error;
562 struct list_head *pos, *q;
563
564 evm_init_config();
565
566 error = integrity_init_keyring(INTEGRITY_KEYRING_EVM);
567 if (error)
568 goto error;
569
570 error = evm_init_secfs();
571 if (error < 0) {
572 pr_info("Error registering secfs\n");
573 goto error;
574 }
575
576error:
577 if (error != 0) {
578 if (!list_empty(&evm_config_xattrnames)) {
579 list_for_each_safe(pos, q, &evm_config_xattrnames)
580 list_del(pos);
581 }
582 }
583
584 return error;
585}
586
587late_initcall(init_evm);
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright (C) 2005-2010 IBM Corporation
4 *
5 * Author:
6 * Mimi Zohar <zohar@us.ibm.com>
7 * Kylene Hall <kjhall@us.ibm.com>
8 *
9 * File: evm_main.c
10 * implements evm_inode_setxattr, evm_inode_post_setxattr,
11 * evm_inode_removexattr, and evm_verifyxattr
12 */
13
14#define pr_fmt(fmt) "EVM: "fmt
15
16#include <linux/init.h>
17#include <linux/crypto.h>
18#include <linux/audit.h>
19#include <linux/xattr.h>
20#include <linux/integrity.h>
21#include <linux/evm.h>
22#include <linux/magic.h>
23#include <linux/posix_acl_xattr.h>
24
25#include <crypto/hash.h>
26#include <crypto/hash_info.h>
27#include <crypto/algapi.h>
28#include "evm.h"
29
30int evm_initialized;
31
32static const char * const integrity_status_msg[] = {
33 "pass", "pass_immutable", "fail", "fail_immutable", "no_label",
34 "no_xattrs", "unknown"
35};
36int evm_hmac_attrs;
37
38static struct xattr_list evm_config_default_xattrnames[] = {
39 {.name = XATTR_NAME_SELINUX,
40#ifdef CONFIG_SECURITY_SELINUX
41 .enabled = true
42#endif
43 },
44 {.name = XATTR_NAME_SMACK,
45#ifdef CONFIG_SECURITY_SMACK
46 .enabled = true
47#endif
48 },
49 {.name = XATTR_NAME_SMACKEXEC,
50#ifdef CONFIG_EVM_EXTRA_SMACK_XATTRS
51 .enabled = true
52#endif
53 },
54 {.name = XATTR_NAME_SMACKTRANSMUTE,
55#ifdef CONFIG_EVM_EXTRA_SMACK_XATTRS
56 .enabled = true
57#endif
58 },
59 {.name = XATTR_NAME_SMACKMMAP,
60#ifdef CONFIG_EVM_EXTRA_SMACK_XATTRS
61 .enabled = true
62#endif
63 },
64 {.name = XATTR_NAME_APPARMOR,
65#ifdef CONFIG_SECURITY_APPARMOR
66 .enabled = true
67#endif
68 },
69 {.name = XATTR_NAME_IMA,
70#ifdef CONFIG_IMA_APPRAISE
71 .enabled = true
72#endif
73 },
74 {.name = XATTR_NAME_CAPS,
75 .enabled = true
76 },
77};
78
79LIST_HEAD(evm_config_xattrnames);
80
81static int evm_fixmode;
82static int __init evm_set_fixmode(char *str)
83{
84 if (strncmp(str, "fix", 3) == 0)
85 evm_fixmode = 1;
86 else
87 pr_err("invalid \"%s\" mode", str);
88
89 return 0;
90}
91__setup("evm=", evm_set_fixmode);
92
93static void __init evm_init_config(void)
94{
95 int i, xattrs;
96
97 xattrs = ARRAY_SIZE(evm_config_default_xattrnames);
98
99 pr_info("Initialising EVM extended attributes:\n");
100 for (i = 0; i < xattrs; i++) {
101 pr_info("%s%s\n", evm_config_default_xattrnames[i].name,
102 !evm_config_default_xattrnames[i].enabled ?
103 " (disabled)" : "");
104 list_add_tail(&evm_config_default_xattrnames[i].list,
105 &evm_config_xattrnames);
106 }
107
108#ifdef CONFIG_EVM_ATTR_FSUUID
109 evm_hmac_attrs |= EVM_ATTR_FSUUID;
110#endif
111 pr_info("HMAC attrs: 0x%x\n", evm_hmac_attrs);
112}
113
114static bool evm_key_loaded(void)
115{
116 return (bool)(evm_initialized & EVM_KEY_MASK);
117}
118
119/*
120 * This function determines whether or not it is safe to ignore verification
121 * errors, based on the ability of EVM to calculate HMACs. If the HMAC key
122 * is not loaded, and it cannot be loaded in the future due to the
123 * EVM_SETUP_COMPLETE initialization flag, allowing an operation despite the
124 * attrs/xattrs being found invalid will not make them valid.
125 */
126static bool evm_hmac_disabled(void)
127{
128 if (evm_initialized & EVM_INIT_HMAC)
129 return false;
130
131 if (!(evm_initialized & EVM_SETUP_COMPLETE))
132 return false;
133
134 return true;
135}
136
137static int evm_find_protected_xattrs(struct dentry *dentry)
138{
139 struct inode *inode = d_backing_inode(dentry);
140 struct xattr_list *xattr;
141 int error;
142 int count = 0;
143
144 if (!(inode->i_opflags & IOP_XATTR))
145 return -EOPNOTSUPP;
146
147 list_for_each_entry_lockless(xattr, &evm_config_xattrnames, list) {
148 error = __vfs_getxattr(dentry, inode, xattr->name, NULL, 0);
149 if (error < 0) {
150 if (error == -ENODATA)
151 continue;
152 return error;
153 }
154 count++;
155 }
156
157 return count;
158}
159
160/*
161 * evm_verify_hmac - calculate and compare the HMAC with the EVM xattr
162 *
163 * Compute the HMAC on the dentry's protected set of extended attributes
164 * and compare it against the stored security.evm xattr.
165 *
166 * For performance:
167 * - use the previoulsy retrieved xattr value and length to calculate the
168 * HMAC.)
169 * - cache the verification result in the iint, when available.
170 *
171 * Returns integrity status
172 */
173static enum integrity_status evm_verify_hmac(struct dentry *dentry,
174 const char *xattr_name,
175 char *xattr_value,
176 size_t xattr_value_len,
177 struct integrity_iint_cache *iint)
178{
179 struct evm_ima_xattr_data *xattr_data = NULL;
180 struct signature_v2_hdr *hdr;
181 enum integrity_status evm_status = INTEGRITY_PASS;
182 struct evm_digest digest;
183 struct inode *inode;
184 int rc, xattr_len, evm_immutable = 0;
185
186 if (iint && (iint->evm_status == INTEGRITY_PASS ||
187 iint->evm_status == INTEGRITY_PASS_IMMUTABLE))
188 return iint->evm_status;
189
190 /* if status is not PASS, try to check again - against -ENOMEM */
191
192 /* first need to know the sig type */
193 rc = vfs_getxattr_alloc(&init_user_ns, dentry, XATTR_NAME_EVM,
194 (char **)&xattr_data, 0, GFP_NOFS);
195 if (rc <= 0) {
196 evm_status = INTEGRITY_FAIL;
197 if (rc == -ENODATA) {
198 rc = evm_find_protected_xattrs(dentry);
199 if (rc > 0)
200 evm_status = INTEGRITY_NOLABEL;
201 else if (rc == 0)
202 evm_status = INTEGRITY_NOXATTRS; /* new file */
203 } else if (rc == -EOPNOTSUPP) {
204 evm_status = INTEGRITY_UNKNOWN;
205 }
206 goto out;
207 }
208
209 xattr_len = rc;
210
211 /* check value type */
212 switch (xattr_data->type) {
213 case EVM_XATTR_HMAC:
214 if (xattr_len != sizeof(struct evm_xattr)) {
215 evm_status = INTEGRITY_FAIL;
216 goto out;
217 }
218
219 digest.hdr.algo = HASH_ALGO_SHA1;
220 rc = evm_calc_hmac(dentry, xattr_name, xattr_value,
221 xattr_value_len, &digest);
222 if (rc)
223 break;
224 rc = crypto_memneq(xattr_data->data, digest.digest,
225 SHA1_DIGEST_SIZE);
226 if (rc)
227 rc = -EINVAL;
228 break;
229 case EVM_XATTR_PORTABLE_DIGSIG:
230 evm_immutable = 1;
231 fallthrough;
232 case EVM_IMA_XATTR_DIGSIG:
233 /* accept xattr with non-empty signature field */
234 if (xattr_len <= sizeof(struct signature_v2_hdr)) {
235 evm_status = INTEGRITY_FAIL;
236 goto out;
237 }
238
239 hdr = (struct signature_v2_hdr *)xattr_data;
240 digest.hdr.algo = hdr->hash_algo;
241 rc = evm_calc_hash(dentry, xattr_name, xattr_value,
242 xattr_value_len, xattr_data->type, &digest);
243 if (rc)
244 break;
245 rc = integrity_digsig_verify(INTEGRITY_KEYRING_EVM,
246 (const char *)xattr_data, xattr_len,
247 digest.digest, digest.hdr.length);
248 if (!rc) {
249 inode = d_backing_inode(dentry);
250
251 if (xattr_data->type == EVM_XATTR_PORTABLE_DIGSIG) {
252 if (iint)
253 iint->flags |= EVM_IMMUTABLE_DIGSIG;
254 evm_status = INTEGRITY_PASS_IMMUTABLE;
255 } else if (!IS_RDONLY(inode) &&
256 !(inode->i_sb->s_readonly_remount) &&
257 !IS_IMMUTABLE(inode)) {
258 evm_update_evmxattr(dentry, xattr_name,
259 xattr_value,
260 xattr_value_len);
261 }
262 }
263 break;
264 default:
265 rc = -EINVAL;
266 break;
267 }
268
269 if (rc) {
270 if (rc == -ENODATA)
271 evm_status = INTEGRITY_NOXATTRS;
272 else if (evm_immutable)
273 evm_status = INTEGRITY_FAIL_IMMUTABLE;
274 else
275 evm_status = INTEGRITY_FAIL;
276 }
277 pr_debug("digest: (%d) [%*phN]\n", digest.hdr.length, digest.hdr.length,
278 digest.digest);
279out:
280 if (iint)
281 iint->evm_status = evm_status;
282 kfree(xattr_data);
283 return evm_status;
284}
285
286static int evm_protected_xattr_common(const char *req_xattr_name,
287 bool all_xattrs)
288{
289 int namelen;
290 int found = 0;
291 struct xattr_list *xattr;
292
293 namelen = strlen(req_xattr_name);
294 list_for_each_entry_lockless(xattr, &evm_config_xattrnames, list) {
295 if (!all_xattrs && !xattr->enabled)
296 continue;
297
298 if ((strlen(xattr->name) == namelen)
299 && (strncmp(req_xattr_name, xattr->name, namelen) == 0)) {
300 found = 1;
301 break;
302 }
303 if (strncmp(req_xattr_name,
304 xattr->name + XATTR_SECURITY_PREFIX_LEN,
305 strlen(req_xattr_name)) == 0) {
306 found = 1;
307 break;
308 }
309 }
310
311 return found;
312}
313
314static int evm_protected_xattr(const char *req_xattr_name)
315{
316 return evm_protected_xattr_common(req_xattr_name, false);
317}
318
319int evm_protected_xattr_if_enabled(const char *req_xattr_name)
320{
321 return evm_protected_xattr_common(req_xattr_name, true);
322}
323
324/**
325 * evm_read_protected_xattrs - read EVM protected xattr names, lengths, values
326 * @dentry: dentry of the read xattrs
327 * @inode: inode of the read xattrs
328 * @buffer: buffer xattr names, lengths or values are copied to
329 * @buffer_size: size of buffer
330 * @type: n: names, l: lengths, v: values
331 * @canonical_fmt: data format (true: little endian, false: native format)
332 *
333 * Read protected xattr names (separated by |), lengths (u32) or values for a
334 * given dentry and return the total size of copied data. If buffer is NULL,
335 * just return the total size.
336 *
337 * Returns the total size on success, a negative value on error.
338 */
339int evm_read_protected_xattrs(struct dentry *dentry, u8 *buffer,
340 int buffer_size, char type, bool canonical_fmt)
341{
342 struct xattr_list *xattr;
343 int rc, size, total_size = 0;
344
345 list_for_each_entry_lockless(xattr, &evm_config_xattrnames, list) {
346 rc = __vfs_getxattr(dentry, d_backing_inode(dentry),
347 xattr->name, NULL, 0);
348 if (rc < 0 && rc == -ENODATA)
349 continue;
350 else if (rc < 0)
351 return rc;
352
353 switch (type) {
354 case 'n':
355 size = strlen(xattr->name) + 1;
356 if (buffer) {
357 if (total_size)
358 *(buffer + total_size - 1) = '|';
359
360 memcpy(buffer + total_size, xattr->name, size);
361 }
362 break;
363 case 'l':
364 size = sizeof(u32);
365 if (buffer) {
366 if (canonical_fmt)
367 rc = (__force int)cpu_to_le32(rc);
368
369 *(u32 *)(buffer + total_size) = rc;
370 }
371 break;
372 case 'v':
373 size = rc;
374 if (buffer) {
375 rc = __vfs_getxattr(dentry,
376 d_backing_inode(dentry), xattr->name,
377 buffer + total_size,
378 buffer_size - total_size);
379 if (rc < 0)
380 return rc;
381 }
382 break;
383 default:
384 return -EINVAL;
385 }
386
387 total_size += size;
388 }
389
390 return total_size;
391}
392
393/**
394 * evm_verifyxattr - verify the integrity of the requested xattr
395 * @dentry: object of the verify xattr
396 * @xattr_name: requested xattr
397 * @xattr_value: requested xattr value
398 * @xattr_value_len: requested xattr value length
399 *
400 * Calculate the HMAC for the given dentry and verify it against the stored
401 * security.evm xattr. For performance, use the xattr value and length
402 * previously retrieved to calculate the HMAC.
403 *
404 * Returns the xattr integrity status.
405 *
406 * This function requires the caller to lock the inode's i_mutex before it
407 * is executed.
408 */
409enum integrity_status evm_verifyxattr(struct dentry *dentry,
410 const char *xattr_name,
411 void *xattr_value, size_t xattr_value_len,
412 struct integrity_iint_cache *iint)
413{
414 if (!evm_key_loaded() || !evm_protected_xattr(xattr_name))
415 return INTEGRITY_UNKNOWN;
416
417 if (!iint) {
418 iint = integrity_iint_find(d_backing_inode(dentry));
419 if (!iint)
420 return INTEGRITY_UNKNOWN;
421 }
422 return evm_verify_hmac(dentry, xattr_name, xattr_value,
423 xattr_value_len, iint);
424}
425EXPORT_SYMBOL_GPL(evm_verifyxattr);
426
427/*
428 * evm_verify_current_integrity - verify the dentry's metadata integrity
429 * @dentry: pointer to the affected dentry
430 *
431 * Verify and return the dentry's metadata integrity. The exceptions are
432 * before EVM is initialized or in 'fix' mode.
433 */
434static enum integrity_status evm_verify_current_integrity(struct dentry *dentry)
435{
436 struct inode *inode = d_backing_inode(dentry);
437
438 if (!evm_key_loaded() || !S_ISREG(inode->i_mode) || evm_fixmode)
439 return 0;
440 return evm_verify_hmac(dentry, NULL, NULL, 0, NULL);
441}
442
443/*
444 * evm_xattr_acl_change - check if passed ACL changes the inode mode
445 * @mnt_userns: user namespace of the idmapped mount
446 * @dentry: pointer to the affected dentry
447 * @xattr_name: requested xattr
448 * @xattr_value: requested xattr value
449 * @xattr_value_len: requested xattr value length
450 *
451 * Check if passed ACL changes the inode mode, which is protected by EVM.
452 *
453 * Returns 1 if passed ACL causes inode mode change, 0 otherwise.
454 */
455static int evm_xattr_acl_change(struct user_namespace *mnt_userns,
456 struct dentry *dentry, const char *xattr_name,
457 const void *xattr_value, size_t xattr_value_len)
458{
459#ifdef CONFIG_FS_POSIX_ACL
460 umode_t mode;
461 struct posix_acl *acl = NULL, *acl_res;
462 struct inode *inode = d_backing_inode(dentry);
463 int rc;
464
465 /*
466 * user_ns is not relevant here, ACL_USER/ACL_GROUP don't have impact
467 * on the inode mode (see posix_acl_equiv_mode()).
468 */
469 acl = posix_acl_from_xattr(&init_user_ns, xattr_value, xattr_value_len);
470 if (IS_ERR_OR_NULL(acl))
471 return 1;
472
473 acl_res = acl;
474 /*
475 * Passing mnt_userns is necessary to correctly determine the GID in
476 * an idmapped mount, as the GID is used to clear the setgid bit in
477 * the inode mode.
478 */
479 rc = posix_acl_update_mode(mnt_userns, inode, &mode, &acl_res);
480
481 posix_acl_release(acl);
482
483 if (rc)
484 return 1;
485
486 if (inode->i_mode != mode)
487 return 1;
488#endif
489 return 0;
490}
491
492/*
493 * evm_xattr_change - check if passed xattr value differs from current value
494 * @mnt_userns: user namespace of the idmapped mount
495 * @dentry: pointer to the affected dentry
496 * @xattr_name: requested xattr
497 * @xattr_value: requested xattr value
498 * @xattr_value_len: requested xattr value length
499 *
500 * Check if passed xattr value differs from current value.
501 *
502 * Returns 1 if passed xattr value differs from current value, 0 otherwise.
503 */
504static int evm_xattr_change(struct user_namespace *mnt_userns,
505 struct dentry *dentry, const char *xattr_name,
506 const void *xattr_value, size_t xattr_value_len)
507{
508 char *xattr_data = NULL;
509 int rc = 0;
510
511 if (posix_xattr_acl(xattr_name))
512 return evm_xattr_acl_change(mnt_userns, dentry, xattr_name,
513 xattr_value, xattr_value_len);
514
515 rc = vfs_getxattr_alloc(&init_user_ns, dentry, xattr_name, &xattr_data,
516 0, GFP_NOFS);
517 if (rc < 0)
518 return 1;
519
520 if (rc == xattr_value_len)
521 rc = !!memcmp(xattr_value, xattr_data, rc);
522 else
523 rc = 1;
524
525 kfree(xattr_data);
526 return rc;
527}
528
529/*
530 * evm_protect_xattr - protect the EVM extended attribute
531 *
532 * Prevent security.evm from being modified or removed without the
533 * necessary permissions or when the existing value is invalid.
534 *
535 * The posix xattr acls are 'system' prefixed, which normally would not
536 * affect security.evm. An interesting side affect of writing posix xattr
537 * acls is their modifying of the i_mode, which is included in security.evm.
538 * For posix xattr acls only, permit security.evm, even if it currently
539 * doesn't exist, to be updated unless the EVM signature is immutable.
540 */
541static int evm_protect_xattr(struct user_namespace *mnt_userns,
542 struct dentry *dentry, const char *xattr_name,
543 const void *xattr_value, size_t xattr_value_len)
544{
545 enum integrity_status evm_status;
546
547 if (strcmp(xattr_name, XATTR_NAME_EVM) == 0) {
548 if (!capable(CAP_SYS_ADMIN))
549 return -EPERM;
550 } else if (!evm_protected_xattr(xattr_name)) {
551 if (!posix_xattr_acl(xattr_name))
552 return 0;
553 evm_status = evm_verify_current_integrity(dentry);
554 if ((evm_status == INTEGRITY_PASS) ||
555 (evm_status == INTEGRITY_NOXATTRS))
556 return 0;
557 goto out;
558 }
559
560 evm_status = evm_verify_current_integrity(dentry);
561 if (evm_status == INTEGRITY_NOXATTRS) {
562 struct integrity_iint_cache *iint;
563
564 /* Exception if the HMAC is not going to be calculated. */
565 if (evm_hmac_disabled())
566 return 0;
567
568 iint = integrity_iint_find(d_backing_inode(dentry));
569 if (iint && (iint->flags & IMA_NEW_FILE))
570 return 0;
571
572 /* exception for pseudo filesystems */
573 if (dentry->d_sb->s_magic == TMPFS_MAGIC
574 || dentry->d_sb->s_magic == SYSFS_MAGIC)
575 return 0;
576
577 integrity_audit_msg(AUDIT_INTEGRITY_METADATA,
578 dentry->d_inode, dentry->d_name.name,
579 "update_metadata",
580 integrity_status_msg[evm_status],
581 -EPERM, 0);
582 }
583out:
584 /* Exception if the HMAC is not going to be calculated. */
585 if (evm_hmac_disabled() && (evm_status == INTEGRITY_NOLABEL ||
586 evm_status == INTEGRITY_UNKNOWN))
587 return 0;
588
589 /*
590 * Writing other xattrs is safe for portable signatures, as portable
591 * signatures are immutable and can never be updated.
592 */
593 if (evm_status == INTEGRITY_FAIL_IMMUTABLE)
594 return 0;
595
596 if (evm_status == INTEGRITY_PASS_IMMUTABLE &&
597 !evm_xattr_change(mnt_userns, dentry, xattr_name, xattr_value,
598 xattr_value_len))
599 return 0;
600
601 if (evm_status != INTEGRITY_PASS &&
602 evm_status != INTEGRITY_PASS_IMMUTABLE)
603 integrity_audit_msg(AUDIT_INTEGRITY_METADATA, d_backing_inode(dentry),
604 dentry->d_name.name, "appraise_metadata",
605 integrity_status_msg[evm_status],
606 -EPERM, 0);
607 return evm_status == INTEGRITY_PASS ? 0 : -EPERM;
608}
609
610/**
611 * evm_inode_setxattr - protect the EVM extended attribute
612 * @mnt_userns: user namespace of the idmapped mount
613 * @dentry: pointer to the affected dentry
614 * @xattr_name: pointer to the affected extended attribute name
615 * @xattr_value: pointer to the new extended attribute value
616 * @xattr_value_len: pointer to the new extended attribute value length
617 *
618 * Before allowing the 'security.evm' protected xattr to be updated,
619 * verify the existing value is valid. As only the kernel should have
620 * access to the EVM encrypted key needed to calculate the HMAC, prevent
621 * userspace from writing HMAC value. Writing 'security.evm' requires
622 * requires CAP_SYS_ADMIN privileges.
623 */
624int evm_inode_setxattr(struct user_namespace *mnt_userns, struct dentry *dentry,
625 const char *xattr_name, const void *xattr_value,
626 size_t xattr_value_len)
627{
628 const struct evm_ima_xattr_data *xattr_data = xattr_value;
629
630 /* Policy permits modification of the protected xattrs even though
631 * there's no HMAC key loaded
632 */
633 if (evm_initialized & EVM_ALLOW_METADATA_WRITES)
634 return 0;
635
636 if (strcmp(xattr_name, XATTR_NAME_EVM) == 0) {
637 if (!xattr_value_len)
638 return -EINVAL;
639 if (xattr_data->type != EVM_IMA_XATTR_DIGSIG &&
640 xattr_data->type != EVM_XATTR_PORTABLE_DIGSIG)
641 return -EPERM;
642 }
643 return evm_protect_xattr(mnt_userns, dentry, xattr_name, xattr_value,
644 xattr_value_len);
645}
646
647/**
648 * evm_inode_removexattr - protect the EVM extended attribute
649 * @mnt_userns: user namespace of the idmapped mount
650 * @dentry: pointer to the affected dentry
651 * @xattr_name: pointer to the affected extended attribute name
652 *
653 * Removing 'security.evm' requires CAP_SYS_ADMIN privileges and that
654 * the current value is valid.
655 */
656int evm_inode_removexattr(struct user_namespace *mnt_userns,
657 struct dentry *dentry, const char *xattr_name)
658{
659 /* Policy permits modification of the protected xattrs even though
660 * there's no HMAC key loaded
661 */
662 if (evm_initialized & EVM_ALLOW_METADATA_WRITES)
663 return 0;
664
665 return evm_protect_xattr(mnt_userns, dentry, xattr_name, NULL, 0);
666}
667
668static void evm_reset_status(struct inode *inode)
669{
670 struct integrity_iint_cache *iint;
671
672 iint = integrity_iint_find(inode);
673 if (iint)
674 iint->evm_status = INTEGRITY_UNKNOWN;
675}
676
677/**
678 * evm_revalidate_status - report whether EVM status re-validation is necessary
679 * @xattr_name: pointer to the affected extended attribute name
680 *
681 * Report whether callers of evm_verifyxattr() should re-validate the
682 * EVM status.
683 *
684 * Return true if re-validation is necessary, false otherwise.
685 */
686bool evm_revalidate_status(const char *xattr_name)
687{
688 if (!evm_key_loaded())
689 return false;
690
691 /* evm_inode_post_setattr() passes NULL */
692 if (!xattr_name)
693 return true;
694
695 if (!evm_protected_xattr(xattr_name) && !posix_xattr_acl(xattr_name) &&
696 strcmp(xattr_name, XATTR_NAME_EVM))
697 return false;
698
699 return true;
700}
701
702/**
703 * evm_inode_post_setxattr - update 'security.evm' to reflect the changes
704 * @dentry: pointer to the affected dentry
705 * @xattr_name: pointer to the affected extended attribute name
706 * @xattr_value: pointer to the new extended attribute value
707 * @xattr_value_len: pointer to the new extended attribute value length
708 *
709 * Update the HMAC stored in 'security.evm' to reflect the change.
710 *
711 * No need to take the i_mutex lock here, as this function is called from
712 * __vfs_setxattr_noperm(). The caller of which has taken the inode's
713 * i_mutex lock.
714 */
715void evm_inode_post_setxattr(struct dentry *dentry, const char *xattr_name,
716 const void *xattr_value, size_t xattr_value_len)
717{
718 if (!evm_revalidate_status(xattr_name))
719 return;
720
721 evm_reset_status(dentry->d_inode);
722
723 if (!strcmp(xattr_name, XATTR_NAME_EVM))
724 return;
725
726 if (!(evm_initialized & EVM_INIT_HMAC))
727 return;
728
729 evm_update_evmxattr(dentry, xattr_name, xattr_value, xattr_value_len);
730}
731
732/**
733 * evm_inode_post_removexattr - update 'security.evm' after removing the xattr
734 * @dentry: pointer to the affected dentry
735 * @xattr_name: pointer to the affected extended attribute name
736 *
737 * Update the HMAC stored in 'security.evm' to reflect removal of the xattr.
738 *
739 * No need to take the i_mutex lock here, as this function is called from
740 * vfs_removexattr() which takes the i_mutex.
741 */
742void evm_inode_post_removexattr(struct dentry *dentry, const char *xattr_name)
743{
744 if (!evm_revalidate_status(xattr_name))
745 return;
746
747 evm_reset_status(dentry->d_inode);
748
749 if (!strcmp(xattr_name, XATTR_NAME_EVM))
750 return;
751
752 if (!(evm_initialized & EVM_INIT_HMAC))
753 return;
754
755 evm_update_evmxattr(dentry, xattr_name, NULL, 0);
756}
757
758static int evm_attr_change(struct dentry *dentry, struct iattr *attr)
759{
760 struct inode *inode = d_backing_inode(dentry);
761 unsigned int ia_valid = attr->ia_valid;
762
763 if ((!(ia_valid & ATTR_UID) || uid_eq(attr->ia_uid, inode->i_uid)) &&
764 (!(ia_valid & ATTR_GID) || gid_eq(attr->ia_gid, inode->i_gid)) &&
765 (!(ia_valid & ATTR_MODE) || attr->ia_mode == inode->i_mode))
766 return 0;
767
768 return 1;
769}
770
771/**
772 * evm_inode_setattr - prevent updating an invalid EVM extended attribute
773 * @dentry: pointer to the affected dentry
774 *
775 * Permit update of file attributes when files have a valid EVM signature,
776 * except in the case of them having an immutable portable signature.
777 */
778int evm_inode_setattr(struct dentry *dentry, struct iattr *attr)
779{
780 unsigned int ia_valid = attr->ia_valid;
781 enum integrity_status evm_status;
782
783 /* Policy permits modification of the protected attrs even though
784 * there's no HMAC key loaded
785 */
786 if (evm_initialized & EVM_ALLOW_METADATA_WRITES)
787 return 0;
788
789 if (!(ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID)))
790 return 0;
791 evm_status = evm_verify_current_integrity(dentry);
792 /*
793 * Writing attrs is safe for portable signatures, as portable signatures
794 * are immutable and can never be updated.
795 */
796 if ((evm_status == INTEGRITY_PASS) ||
797 (evm_status == INTEGRITY_NOXATTRS) ||
798 (evm_status == INTEGRITY_FAIL_IMMUTABLE) ||
799 (evm_hmac_disabled() && (evm_status == INTEGRITY_NOLABEL ||
800 evm_status == INTEGRITY_UNKNOWN)))
801 return 0;
802
803 if (evm_status == INTEGRITY_PASS_IMMUTABLE &&
804 !evm_attr_change(dentry, attr))
805 return 0;
806
807 integrity_audit_msg(AUDIT_INTEGRITY_METADATA, d_backing_inode(dentry),
808 dentry->d_name.name, "appraise_metadata",
809 integrity_status_msg[evm_status], -EPERM, 0);
810 return -EPERM;
811}
812
813/**
814 * evm_inode_post_setattr - update 'security.evm' after modifying metadata
815 * @dentry: pointer to the affected dentry
816 * @ia_valid: for the UID and GID status
817 *
818 * For now, update the HMAC stored in 'security.evm' to reflect UID/GID
819 * changes.
820 *
821 * This function is called from notify_change(), which expects the caller
822 * to lock the inode's i_mutex.
823 */
824void evm_inode_post_setattr(struct dentry *dentry, int ia_valid)
825{
826 if (!evm_revalidate_status(NULL))
827 return;
828
829 evm_reset_status(dentry->d_inode);
830
831 if (!(evm_initialized & EVM_INIT_HMAC))
832 return;
833
834 if (ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID))
835 evm_update_evmxattr(dentry, NULL, NULL, 0);
836}
837
838/*
839 * evm_inode_init_security - initializes security.evm HMAC value
840 */
841int evm_inode_init_security(struct inode *inode,
842 const struct xattr *lsm_xattr,
843 struct xattr *evm_xattr)
844{
845 struct evm_xattr *xattr_data;
846 int rc;
847
848 if (!(evm_initialized & EVM_INIT_HMAC) ||
849 !evm_protected_xattr(lsm_xattr->name))
850 return 0;
851
852 xattr_data = kzalloc(sizeof(*xattr_data), GFP_NOFS);
853 if (!xattr_data)
854 return -ENOMEM;
855
856 xattr_data->data.type = EVM_XATTR_HMAC;
857 rc = evm_init_hmac(inode, lsm_xattr, xattr_data->digest);
858 if (rc < 0)
859 goto out;
860
861 evm_xattr->value = xattr_data;
862 evm_xattr->value_len = sizeof(*xattr_data);
863 evm_xattr->name = XATTR_EVM_SUFFIX;
864 return 0;
865out:
866 kfree(xattr_data);
867 return rc;
868}
869EXPORT_SYMBOL_GPL(evm_inode_init_security);
870
871#ifdef CONFIG_EVM_LOAD_X509
872void __init evm_load_x509(void)
873{
874 int rc;
875
876 rc = integrity_load_x509(INTEGRITY_KEYRING_EVM, CONFIG_EVM_X509_PATH);
877 if (!rc)
878 evm_initialized |= EVM_INIT_X509;
879}
880#endif
881
882static int __init init_evm(void)
883{
884 int error;
885 struct list_head *pos, *q;
886
887 evm_init_config();
888
889 error = integrity_init_keyring(INTEGRITY_KEYRING_EVM);
890 if (error)
891 goto error;
892
893 error = evm_init_secfs();
894 if (error < 0) {
895 pr_info("Error registering secfs\n");
896 goto error;
897 }
898
899error:
900 if (error != 0) {
901 if (!list_empty(&evm_config_xattrnames)) {
902 list_for_each_safe(pos, q, &evm_config_xattrnames)
903 list_del(pos);
904 }
905 }
906
907 return error;
908}
909
910late_initcall(init_evm);