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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
121
122
123
124
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
162
163
164
165
166
167
168
169
170
171
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
191
192
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;
203 } else if (rc == -EOPNOTSUPP) {
204 evm_status = INTEGRITY_UNKNOWN;
205 }
206 goto out;
207 }
208
209 xattr_len = rc;
210
211
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
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
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330
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332
333
334
335
336
337
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
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407
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
429
430
431
432
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
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452
453
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
467
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
476
477
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
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495
496
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500
501
502
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
531
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533
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536
537
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539
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
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
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
585 if (evm_hmac_disabled() && (evm_status == INTEGRITY_NOLABEL ||
586 evm_status == INTEGRITY_UNKNOWN))
587 return 0;
588
589
590
591
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
612
613
614
615
616
617
618
619
620
621
622
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
631
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
649
650
651
652
653
654
655
656int evm_inode_removexattr(struct user_namespace *mnt_userns,
657 struct dentry *dentry, const char *xattr_name)
658{
659
660
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
679
680
681
682
683
684
685
686bool evm_revalidate_status(const char *xattr_name)
687{
688 if (!evm_key_loaded())
689 return false;
690
691
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
704
705
706
707
708
709
710
711
712
713
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
734
735
736
737
738
739
740
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
773
774
775
776
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
784
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
794
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
815
816
817
818
819
820
821
822
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
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);
911