1 /*
2 * linux/fs/xattr_acl.c
3 *
4 * Almost all from linux/fs/ext2/acl.c:
5 * Copyright (C) 2001 by Andreas Gruenbacher, <a.gruenbacher@computer.org>
6 */
7
8 #include <linux/export.h>
9 #include <linux/fs.h>
10 #include <linux/posix_acl_xattr.h>
11 #include <linux/gfp.h>
12 #include <linux/user_namespace.h>
13
14 /*
15 * Fix up the uids and gids in posix acl extended attributes in place.
16 */
posix_acl_fix_xattr_userns(struct user_namespace * to,struct user_namespace * from,void * value,size_t size)17 static void posix_acl_fix_xattr_userns(
18 struct user_namespace *to, struct user_namespace *from,
19 void *value, size_t size)
20 {
21 posix_acl_xattr_header *header = (posix_acl_xattr_header *)value;
22 posix_acl_xattr_entry *entry = (posix_acl_xattr_entry *)(header+1), *end;
23 int count;
24 kuid_t uid;
25 kgid_t gid;
26
27 if (!value)
28 return;
29 if (size < sizeof(posix_acl_xattr_header))
30 return;
31 if (header->a_version != cpu_to_le32(POSIX_ACL_XATTR_VERSION))
32 return;
33
34 count = posix_acl_xattr_count(size);
35 if (count < 0)
36 return;
37 if (count == 0)
38 return;
39
40 for (end = entry + count; entry != end; entry++) {
41 switch(le16_to_cpu(entry->e_tag)) {
42 case ACL_USER:
43 uid = make_kuid(from, le32_to_cpu(entry->e_id));
44 entry->e_id = cpu_to_le32(from_kuid(to, uid));
45 break;
46 case ACL_GROUP:
47 gid = make_kgid(from, le32_to_cpu(entry->e_id));
48 entry->e_id = cpu_to_le32(from_kgid(to, gid));
49 break;
50 default:
51 break;
52 }
53 }
54 }
55
posix_acl_fix_xattr_from_user(void * value,size_t size)56 void posix_acl_fix_xattr_from_user(void *value, size_t size)
57 {
58 struct user_namespace *user_ns = current_user_ns();
59 if (user_ns == &init_user_ns)
60 return;
61 posix_acl_fix_xattr_userns(&init_user_ns, user_ns, value, size);
62 }
63
posix_acl_fix_xattr_to_user(void * value,size_t size)64 void posix_acl_fix_xattr_to_user(void *value, size_t size)
65 {
66 struct user_namespace *user_ns = current_user_ns();
67 if (user_ns == &init_user_ns)
68 return;
69 posix_acl_fix_xattr_userns(user_ns, &init_user_ns, value, size);
70 }
71
72 /*
73 * Convert from extended attribute to in-memory representation.
74 */
75 struct posix_acl *
posix_acl_from_xattr(struct user_namespace * user_ns,const void * value,size_t size)76 posix_acl_from_xattr(struct user_namespace *user_ns,
77 const void *value, size_t size)
78 {
79 posix_acl_xattr_header *header = (posix_acl_xattr_header *)value;
80 posix_acl_xattr_entry *entry = (posix_acl_xattr_entry *)(header+1), *end;
81 int count;
82 struct posix_acl *acl;
83 struct posix_acl_entry *acl_e;
84
85 if (!value)
86 return NULL;
87 if (size < sizeof(posix_acl_xattr_header))
88 return ERR_PTR(-EINVAL);
89 if (header->a_version != cpu_to_le32(POSIX_ACL_XATTR_VERSION))
90 return ERR_PTR(-EOPNOTSUPP);
91
92 count = posix_acl_xattr_count(size);
93 if (count < 0)
94 return ERR_PTR(-EINVAL);
95 if (count == 0)
96 return NULL;
97
98 acl = posix_acl_alloc(count, GFP_NOFS);
99 if (!acl)
100 return ERR_PTR(-ENOMEM);
101 acl_e = acl->a_entries;
102
103 for (end = entry + count; entry != end; acl_e++, entry++) {
104 acl_e->e_tag = le16_to_cpu(entry->e_tag);
105 acl_e->e_perm = le16_to_cpu(entry->e_perm);
106
107 switch(acl_e->e_tag) {
108 case ACL_USER_OBJ:
109 case ACL_GROUP_OBJ:
110 case ACL_MASK:
111 case ACL_OTHER:
112 break;
113
114 case ACL_USER:
115 acl_e->e_uid =
116 make_kuid(user_ns,
117 le32_to_cpu(entry->e_id));
118 if (!uid_valid(acl_e->e_uid))
119 goto fail;
120 break;
121 case ACL_GROUP:
122 acl_e->e_gid =
123 make_kgid(user_ns,
124 le32_to_cpu(entry->e_id));
125 if (!gid_valid(acl_e->e_gid))
126 goto fail;
127 break;
128
129 default:
130 goto fail;
131 }
132 }
133 return acl;
134
135 fail:
136 posix_acl_release(acl);
137 return ERR_PTR(-EINVAL);
138 }
139 EXPORT_SYMBOL (posix_acl_from_xattr);
140
141 /*
142 * Convert from in-memory to extended attribute representation.
143 */
144 int
posix_acl_to_xattr(struct user_namespace * user_ns,const struct posix_acl * acl,void * buffer,size_t size)145 posix_acl_to_xattr(struct user_namespace *user_ns, const struct posix_acl *acl,
146 void *buffer, size_t size)
147 {
148 posix_acl_xattr_header *ext_acl = (posix_acl_xattr_header *)buffer;
149 posix_acl_xattr_entry *ext_entry = ext_acl->a_entries;
150 int real_size, n;
151
152 real_size = posix_acl_xattr_size(acl->a_count);
153 if (!buffer)
154 return real_size;
155 if (real_size > size)
156 return -ERANGE;
157
158 ext_acl->a_version = cpu_to_le32(POSIX_ACL_XATTR_VERSION);
159
160 for (n=0; n < acl->a_count; n++, ext_entry++) {
161 const struct posix_acl_entry *acl_e = &acl->a_entries[n];
162 ext_entry->e_tag = cpu_to_le16(acl_e->e_tag);
163 ext_entry->e_perm = cpu_to_le16(acl_e->e_perm);
164 switch(acl_e->e_tag) {
165 case ACL_USER:
166 ext_entry->e_id =
167 cpu_to_le32(from_kuid(user_ns, acl_e->e_uid));
168 break;
169 case ACL_GROUP:
170 ext_entry->e_id =
171 cpu_to_le32(from_kgid(user_ns, acl_e->e_gid));
172 break;
173 default:
174 ext_entry->e_id = cpu_to_le32(ACL_UNDEFINED_ID);
175 break;
176 }
177 }
178 return real_size;
179 }
180 EXPORT_SYMBOL (posix_acl_to_xattr);
181