2 * Copyright (C) 2002,2003 by Andreas Gruenbacher <a.gruenbacher@computer.org>
4 * Fixes from William Schumacher incorporated on 15 March 2001.
5 * (Reported by Charles Bertsch, <CBertsch@microtest.com>).
9 * This file contains generic functions for manipulating
10 * POSIX 1003.1e draft standard 17 ACLs.
13 #include <linux/kernel.h>
14 #include <linux/slab.h>
15 #include <linux/atomic.h>
17 #include <linux/sched.h>
18 #include <linux/posix_acl.h>
19 #include <linux/posix_acl_xattr.h>
20 #include <linux/xattr.h>
21 #include <linux/export.h>
22 #include <linux/user_namespace.h>
24 struct posix_acl **acl_by_type(struct inode *inode, int type)
29 case ACL_TYPE_DEFAULT:
30 return &inode->i_default_acl;
35 EXPORT_SYMBOL(acl_by_type);
37 struct posix_acl *get_cached_acl(struct inode *inode, int type)
39 struct posix_acl **p = acl_by_type(inode, type);
40 struct posix_acl *acl = ACCESS_ONCE(*p);
42 spin_lock(&inode->i_lock);
44 if (acl != ACL_NOT_CACHED)
45 acl = posix_acl_dup(acl);
46 spin_unlock(&inode->i_lock);
50 EXPORT_SYMBOL(get_cached_acl);
52 struct posix_acl *get_cached_acl_rcu(struct inode *inode, int type)
54 return rcu_dereference(*acl_by_type(inode, type));
56 EXPORT_SYMBOL(get_cached_acl_rcu);
58 void set_cached_acl(struct inode *inode, int type, struct posix_acl *acl)
60 struct posix_acl **p = acl_by_type(inode, type);
61 struct posix_acl *old;
62 spin_lock(&inode->i_lock);
64 rcu_assign_pointer(*p, posix_acl_dup(acl));
65 spin_unlock(&inode->i_lock);
66 if (old != ACL_NOT_CACHED)
67 posix_acl_release(old);
69 EXPORT_SYMBOL(set_cached_acl);
71 void forget_cached_acl(struct inode *inode, int type)
73 struct posix_acl **p = acl_by_type(inode, type);
74 struct posix_acl *old;
75 spin_lock(&inode->i_lock);
78 spin_unlock(&inode->i_lock);
79 if (old != ACL_NOT_CACHED)
80 posix_acl_release(old);
82 EXPORT_SYMBOL(forget_cached_acl);
84 void forget_all_cached_acls(struct inode *inode)
86 struct posix_acl *old_access, *old_default;
87 spin_lock(&inode->i_lock);
88 old_access = inode->i_acl;
89 old_default = inode->i_default_acl;
90 inode->i_acl = inode->i_default_acl = ACL_NOT_CACHED;
91 spin_unlock(&inode->i_lock);
92 if (old_access != ACL_NOT_CACHED)
93 posix_acl_release(old_access);
94 if (old_default != ACL_NOT_CACHED)
95 posix_acl_release(old_default);
97 EXPORT_SYMBOL(forget_all_cached_acls);
99 struct posix_acl *get_acl(struct inode *inode, int type)
101 struct posix_acl *acl;
103 acl = get_cached_acl(inode, type);
104 if (acl != ACL_NOT_CACHED)
107 if (!IS_POSIXACL(inode))
111 * A filesystem can force a ACL callback by just never filling the
112 * ACL cache. But normally you'd fill the cache either at inode
113 * instantiation time, or on the first ->get_acl call.
115 * If the filesystem doesn't have a get_acl() function at all, we'll
116 * just create the negative cache entry.
118 if (!inode->i_op->get_acl) {
119 set_cached_acl(inode, type, NULL);
122 return inode->i_op->get_acl(inode, type);
124 EXPORT_SYMBOL(get_acl);
127 * Init a fresh posix_acl
130 posix_acl_init(struct posix_acl *acl, int count)
132 atomic_set(&acl->a_refcount, 1);
133 acl->a_count = count;
135 EXPORT_SYMBOL(posix_acl_init);
138 * Allocate a new ACL with the specified number of entries.
141 posix_acl_alloc(int count, gfp_t flags)
143 const size_t size = sizeof(struct posix_acl) +
144 count * sizeof(struct posix_acl_entry);
145 struct posix_acl *acl = kmalloc(size, flags);
147 posix_acl_init(acl, count);
150 EXPORT_SYMBOL(posix_acl_alloc);
155 static struct posix_acl *
156 posix_acl_clone(const struct posix_acl *acl, gfp_t flags)
158 struct posix_acl *clone = NULL;
161 int size = sizeof(struct posix_acl) + acl->a_count *
162 sizeof(struct posix_acl_entry);
163 clone = kmemdup(acl, size, flags);
165 atomic_set(&clone->a_refcount, 1);
171 * Check if an acl is valid. Returns 0 if it is, or -E... otherwise.
174 posix_acl_valid(const struct posix_acl *acl)
176 const struct posix_acl_entry *pa, *pe;
177 int state = ACL_USER_OBJ;
180 FOREACH_ACL_ENTRY(pa, acl, pe) {
181 if (pa->e_perm & ~(ACL_READ|ACL_WRITE|ACL_EXECUTE))
185 if (state == ACL_USER_OBJ) {
192 if (state != ACL_USER)
194 if (!uid_valid(pa->e_uid))
200 if (state == ACL_USER) {
207 if (state != ACL_GROUP)
209 if (!gid_valid(pa->e_gid))
215 if (state != ACL_GROUP)
221 if (state == ACL_OTHER ||
222 (state == ACL_GROUP && !needs_mask)) {
236 EXPORT_SYMBOL(posix_acl_valid);
239 * Returns 0 if the acl can be exactly represented in the traditional
240 * file mode permission bits, or else 1. Returns -E... on error.
243 posix_acl_equiv_mode(const struct posix_acl *acl, umode_t *mode_p)
245 const struct posix_acl_entry *pa, *pe;
250 * A null ACL can always be presented as mode bits.
255 FOREACH_ACL_ENTRY(pa, acl, pe) {
258 mode |= (pa->e_perm & S_IRWXO) << 6;
261 mode |= (pa->e_perm & S_IRWXO) << 3;
264 mode |= pa->e_perm & S_IRWXO;
267 mode = (mode & ~S_IRWXG) |
268 ((pa->e_perm & S_IRWXO) << 3);
280 *mode_p = (*mode_p & ~S_IRWXUGO) | mode;
283 EXPORT_SYMBOL(posix_acl_equiv_mode);
286 * Create an ACL representing the file mode permission bits of an inode.
289 posix_acl_from_mode(umode_t mode, gfp_t flags)
291 struct posix_acl *acl = posix_acl_alloc(3, flags);
293 return ERR_PTR(-ENOMEM);
295 acl->a_entries[0].e_tag = ACL_USER_OBJ;
296 acl->a_entries[0].e_perm = (mode & S_IRWXU) >> 6;
298 acl->a_entries[1].e_tag = ACL_GROUP_OBJ;
299 acl->a_entries[1].e_perm = (mode & S_IRWXG) >> 3;
301 acl->a_entries[2].e_tag = ACL_OTHER;
302 acl->a_entries[2].e_perm = (mode & S_IRWXO);
305 EXPORT_SYMBOL(posix_acl_from_mode);
308 * Return 0 if current is granted want access to the inode
309 * by the acl. Returns -E... otherwise.
312 posix_acl_permission(struct inode *inode, const struct posix_acl *acl, int want)
314 const struct posix_acl_entry *pa, *pe, *mask_obj;
317 want &= MAY_READ | MAY_WRITE | MAY_EXEC | MAY_NOT_BLOCK;
319 FOREACH_ACL_ENTRY(pa, acl, pe) {
322 /* (May have been checked already) */
323 if (uid_eq(inode->i_uid, current_fsuid()))
327 if (uid_eq(pa->e_uid, current_fsuid()))
331 if (in_group_p(inode->i_gid)) {
333 if ((pa->e_perm & want) == want)
338 if (in_group_p(pa->e_gid)) {
340 if ((pa->e_perm & want) == want)
358 for (mask_obj = pa+1; mask_obj != pe; mask_obj++) {
359 if (mask_obj->e_tag == ACL_MASK) {
360 if ((pa->e_perm & mask_obj->e_perm & want) == want)
367 if ((pa->e_perm & want) == want)
373 * Modify acl when creating a new inode. The caller must ensure the acl is
374 * only referenced once.
376 * mode_p initially must contain the mode parameter to the open() / creat()
377 * system calls. All permissions that are not granted by the acl are removed.
378 * The permissions in the acl are changed to reflect the mode_p parameter.
380 static int posix_acl_create_masq(struct posix_acl *acl, umode_t *mode_p)
382 struct posix_acl_entry *pa, *pe;
383 struct posix_acl_entry *group_obj = NULL, *mask_obj = NULL;
384 umode_t mode = *mode_p;
387 /* assert(atomic_read(acl->a_refcount) == 1); */
389 FOREACH_ACL_ENTRY(pa, acl, pe) {
392 pa->e_perm &= (mode >> 6) | ~S_IRWXO;
393 mode &= (pa->e_perm << 6) | ~S_IRWXU;
406 pa->e_perm &= mode | ~S_IRWXO;
407 mode &= pa->e_perm | ~S_IRWXO;
421 mask_obj->e_perm &= (mode >> 3) | ~S_IRWXO;
422 mode &= (mask_obj->e_perm << 3) | ~S_IRWXG;
426 group_obj->e_perm &= (mode >> 3) | ~S_IRWXO;
427 mode &= (group_obj->e_perm << 3) | ~S_IRWXG;
430 *mode_p = (*mode_p & ~S_IRWXUGO) | mode;
435 * Modify the ACL for the chmod syscall.
437 static int __posix_acl_chmod_masq(struct posix_acl *acl, umode_t mode)
439 struct posix_acl_entry *group_obj = NULL, *mask_obj = NULL;
440 struct posix_acl_entry *pa, *pe;
442 /* assert(atomic_read(acl->a_refcount) == 1); */
444 FOREACH_ACL_ENTRY(pa, acl, pe) {
447 pa->e_perm = (mode & S_IRWXU) >> 6;
463 pa->e_perm = (mode & S_IRWXO);
472 mask_obj->e_perm = (mode & S_IRWXG) >> 3;
476 group_obj->e_perm = (mode & S_IRWXG) >> 3;
483 __posix_acl_create(struct posix_acl **acl, gfp_t gfp, umode_t *mode_p)
485 struct posix_acl *clone = posix_acl_clone(*acl, gfp);
488 err = posix_acl_create_masq(clone, mode_p);
490 posix_acl_release(clone);
494 posix_acl_release(*acl);
498 EXPORT_SYMBOL(__posix_acl_create);
501 __posix_acl_chmod(struct posix_acl **acl, gfp_t gfp, umode_t mode)
503 struct posix_acl *clone = posix_acl_clone(*acl, gfp);
506 err = __posix_acl_chmod_masq(clone, mode);
508 posix_acl_release(clone);
512 posix_acl_release(*acl);
516 EXPORT_SYMBOL(__posix_acl_chmod);
519 posix_acl_chmod(struct inode *inode, umode_t mode)
521 struct posix_acl *acl;
524 if (!IS_POSIXACL(inode))
526 if (!inode->i_op->set_acl)
529 acl = get_acl(inode, ACL_TYPE_ACCESS);
530 if (IS_ERR_OR_NULL(acl)) {
531 if (acl == ERR_PTR(-EOPNOTSUPP))
536 ret = __posix_acl_chmod(&acl, GFP_KERNEL, mode);
539 ret = inode->i_op->set_acl(inode, acl, ACL_TYPE_ACCESS);
540 posix_acl_release(acl);
543 EXPORT_SYMBOL(posix_acl_chmod);
546 posix_acl_create(struct inode *dir, umode_t *mode,
547 struct posix_acl **default_acl, struct posix_acl **acl)
550 struct posix_acl *clone;
556 if (S_ISLNK(*mode) || !IS_POSIXACL(dir))
559 p = get_acl(dir, ACL_TYPE_DEFAULT);
560 if (!p || p == ERR_PTR(-EOPNOTSUPP)) {
561 *mode &= ~current_umask();
567 clone = posix_acl_clone(p, GFP_NOFS);
571 ret = posix_acl_create_masq(clone, mode);
576 posix_acl_release(clone);
581 posix_acl_release(p);
588 posix_acl_release(clone);
590 posix_acl_release(p);
593 EXPORT_SYMBOL_GPL(posix_acl_create);
596 * posix_acl_update_mode - update mode in set_acl
598 * Update the file mode when setting an ACL: compute the new file permission
599 * bits based on the ACL. In addition, if the ACL is equivalent to the new
600 * file mode, set *acl to NULL to indicate that no ACL should be set.
602 * As with chmod, clear the setgit bit if the caller is not in the owning group
603 * or capable of CAP_FSETID (see inode_change_ok).
605 * Called from set_acl inode operations.
607 int posix_acl_update_mode(struct inode *inode, umode_t *mode_p,
608 struct posix_acl **acl)
610 umode_t mode = inode->i_mode;
613 error = posix_acl_equiv_mode(*acl, &mode);
618 if (!in_group_p(inode->i_gid) &&
619 !capable_wrt_inode_uidgid(inode, CAP_FSETID))
624 EXPORT_SYMBOL(posix_acl_update_mode);
627 * Fix up the uids and gids in posix acl extended attributes in place.
629 static void posix_acl_fix_xattr_userns(
630 struct user_namespace *to, struct user_namespace *from,
631 void *value, size_t size)
633 posix_acl_xattr_header *header = (posix_acl_xattr_header *)value;
634 posix_acl_xattr_entry *entry = (posix_acl_xattr_entry *)(header+1), *end;
641 if (size < sizeof(posix_acl_xattr_header))
643 if (header->a_version != cpu_to_le32(POSIX_ACL_XATTR_VERSION))
646 count = posix_acl_xattr_count(size);
652 for (end = entry + count; entry != end; entry++) {
653 switch(le16_to_cpu(entry->e_tag)) {
655 uid = make_kuid(from, le32_to_cpu(entry->e_id));
656 entry->e_id = cpu_to_le32(from_kuid(to, uid));
659 gid = make_kgid(from, le32_to_cpu(entry->e_id));
660 entry->e_id = cpu_to_le32(from_kgid(to, gid));
668 void posix_acl_fix_xattr_from_user(void *value, size_t size)
670 struct user_namespace *user_ns = current_user_ns();
671 if (user_ns == &init_user_ns)
673 posix_acl_fix_xattr_userns(&init_user_ns, user_ns, value, size);
676 void posix_acl_fix_xattr_to_user(void *value, size_t size)
678 struct user_namespace *user_ns = current_user_ns();
679 if (user_ns == &init_user_ns)
681 posix_acl_fix_xattr_userns(user_ns, &init_user_ns, value, size);
685 * Convert from extended attribute to in-memory representation.
688 posix_acl_from_xattr(struct user_namespace *user_ns,
689 const void *value, size_t size)
691 posix_acl_xattr_header *header = (posix_acl_xattr_header *)value;
692 posix_acl_xattr_entry *entry = (posix_acl_xattr_entry *)(header+1), *end;
694 struct posix_acl *acl;
695 struct posix_acl_entry *acl_e;
699 if (size < sizeof(posix_acl_xattr_header))
700 return ERR_PTR(-EINVAL);
701 if (header->a_version != cpu_to_le32(POSIX_ACL_XATTR_VERSION))
702 return ERR_PTR(-EOPNOTSUPP);
704 count = posix_acl_xattr_count(size);
706 return ERR_PTR(-EINVAL);
710 acl = posix_acl_alloc(count, GFP_NOFS);
712 return ERR_PTR(-ENOMEM);
713 acl_e = acl->a_entries;
715 for (end = entry + count; entry != end; acl_e++, entry++) {
716 acl_e->e_tag = le16_to_cpu(entry->e_tag);
717 acl_e->e_perm = le16_to_cpu(entry->e_perm);
719 switch(acl_e->e_tag) {
729 le32_to_cpu(entry->e_id));
730 if (!uid_valid(acl_e->e_uid))
736 le32_to_cpu(entry->e_id));
737 if (!gid_valid(acl_e->e_gid))
748 posix_acl_release(acl);
749 return ERR_PTR(-EINVAL);
751 EXPORT_SYMBOL (posix_acl_from_xattr);
754 * Convert from in-memory to extended attribute representation.
757 posix_acl_to_xattr(struct user_namespace *user_ns, const struct posix_acl *acl,
758 void *buffer, size_t size)
760 posix_acl_xattr_header *ext_acl = (posix_acl_xattr_header *)buffer;
761 posix_acl_xattr_entry *ext_entry;
764 real_size = posix_acl_xattr_size(acl->a_count);
767 if (real_size > size)
770 ext_entry = ext_acl->a_entries;
771 ext_acl->a_version = cpu_to_le32(POSIX_ACL_XATTR_VERSION);
773 for (n=0; n < acl->a_count; n++, ext_entry++) {
774 const struct posix_acl_entry *acl_e = &acl->a_entries[n];
775 ext_entry->e_tag = cpu_to_le16(acl_e->e_tag);
776 ext_entry->e_perm = cpu_to_le16(acl_e->e_perm);
777 switch(acl_e->e_tag) {
780 cpu_to_le32(from_kuid(user_ns, acl_e->e_uid));
784 cpu_to_le32(from_kgid(user_ns, acl_e->e_gid));
787 ext_entry->e_id = cpu_to_le32(ACL_UNDEFINED_ID);
793 EXPORT_SYMBOL (posix_acl_to_xattr);
796 posix_acl_xattr_get(const struct xattr_handler *handler,
797 struct dentry *dentry, const char *name,
798 void *value, size_t size)
800 struct posix_acl *acl;
803 if (strcmp(name, "") != 0)
805 if (!IS_POSIXACL(d_backing_inode(dentry)))
807 if (d_is_symlink(dentry))
810 acl = get_acl(d_backing_inode(dentry), handler->flags);
816 error = posix_acl_to_xattr(&init_user_ns, acl, value, size);
817 posix_acl_release(acl);
823 set_posix_acl(struct inode *inode, int type, struct posix_acl *acl)
825 if (!IS_POSIXACL(inode))
827 if (!inode->i_op->set_acl)
830 if (type == ACL_TYPE_DEFAULT && !S_ISDIR(inode->i_mode))
831 return acl ? -EACCES : 0;
832 if (!inode_owner_or_capable(inode))
836 int ret = posix_acl_valid(acl);
840 return inode->i_op->set_acl(inode, acl, type);
842 EXPORT_SYMBOL(set_posix_acl);
845 posix_acl_xattr_set(const struct xattr_handler *handler,
846 struct dentry *dentry, const char *name,
847 const void *value, size_t size, int flags)
849 struct inode *inode = d_backing_inode(dentry);
850 struct posix_acl *acl = NULL;
853 if (strcmp(name, "") != 0)
857 acl = posix_acl_from_xattr(&init_user_ns, value, size);
861 ret = set_posix_acl(inode, handler->flags, acl);
862 posix_acl_release(acl);
867 posix_acl_xattr_list(const struct xattr_handler *handler,
868 struct dentry *dentry, char *list, size_t list_size,
869 const char *name, size_t name_len)
871 const char *xname = handler->prefix;
874 if (!IS_POSIXACL(d_backing_inode(dentry)))
877 size = strlen(xname) + 1;
878 if (list && size <= list_size)
879 memcpy(list, xname, size);
883 const struct xattr_handler posix_acl_access_xattr_handler = {
884 .prefix = POSIX_ACL_XATTR_ACCESS,
885 .flags = ACL_TYPE_ACCESS,
886 .list = posix_acl_xattr_list,
887 .get = posix_acl_xattr_get,
888 .set = posix_acl_xattr_set,
890 EXPORT_SYMBOL_GPL(posix_acl_access_xattr_handler);
892 const struct xattr_handler posix_acl_default_xattr_handler = {
893 .prefix = POSIX_ACL_XATTR_DEFAULT,
894 .flags = ACL_TYPE_DEFAULT,
895 .list = posix_acl_xattr_list,
896 .get = posix_acl_xattr_get,
897 .set = posix_acl_xattr_set,
899 EXPORT_SYMBOL_GPL(posix_acl_default_xattr_handler);
901 int simple_set_acl(struct inode *inode, struct posix_acl *acl, int type)
905 if (type == ACL_TYPE_ACCESS) {
906 error = posix_acl_update_mode(inode,
907 &inode->i_mode, &acl);
912 inode->i_ctime = CURRENT_TIME;
913 set_cached_acl(inode, type, acl);
917 int simple_acl_create(struct inode *dir, struct inode *inode)
919 struct posix_acl *default_acl, *acl;
922 error = posix_acl_create(dir, &inode->i_mode, &default_acl, &acl);
926 set_cached_acl(inode, ACL_TYPE_DEFAULT, default_acl);
927 set_cached_acl(inode, ACL_TYPE_ACCESS, acl);
930 posix_acl_release(default_acl);
932 posix_acl_release(acl);