1 /*
2 * linux/fs/ext4/acl.c
3 *
4 * Copyright (C) 2001-2003 Andreas Gruenbacher, <agruen@suse.de>
5 */
6
7 #include <linux/init.h>
8 #include <linux/sched.h>
9 #include <linux/slab.h>
10 #include <linux/capability.h>
11 #include <linux/fs.h>
12 #include "ext4_jbd2.h"
13 #include "ext4.h"
14 #include "xattr.h"
15 #include "acl.h"
16
17 /*
18 * Convert from filesystem to in-memory representation.
19 */
20 static struct posix_acl *
ext4_acl_from_disk(const void * value,size_t size)21 ext4_acl_from_disk(const void *value, size_t size)
22 {
23 const char *end = (char *)value + size;
24 int n, count;
25 struct posix_acl *acl;
26
27 if (!value)
28 return NULL;
29 if (size < sizeof(ext4_acl_header))
30 return ERR_PTR(-EINVAL);
31 if (((ext4_acl_header *)value)->a_version !=
32 cpu_to_le32(EXT4_ACL_VERSION))
33 return ERR_PTR(-EINVAL);
34 value = (char *)value + sizeof(ext4_acl_header);
35 count = ext4_acl_count(size);
36 if (count < 0)
37 return ERR_PTR(-EINVAL);
38 if (count == 0)
39 return NULL;
40 acl = posix_acl_alloc(count, GFP_NOFS);
41 if (!acl)
42 return ERR_PTR(-ENOMEM);
43 for (n = 0; n < count; n++) {
44 ext4_acl_entry *entry =
45 (ext4_acl_entry *)value;
46 if ((char *)value + sizeof(ext4_acl_entry_short) > end)
47 goto fail;
48 acl->a_entries[n].e_tag = le16_to_cpu(entry->e_tag);
49 acl->a_entries[n].e_perm = le16_to_cpu(entry->e_perm);
50
51 switch (acl->a_entries[n].e_tag) {
52 case ACL_USER_OBJ:
53 case ACL_GROUP_OBJ:
54 case ACL_MASK:
55 case ACL_OTHER:
56 value = (char *)value +
57 sizeof(ext4_acl_entry_short);
58 break;
59
60 case ACL_USER:
61 value = (char *)value + sizeof(ext4_acl_entry);
62 if ((char *)value > end)
63 goto fail;
64 acl->a_entries[n].e_uid =
65 make_kuid(&init_user_ns,
66 le32_to_cpu(entry->e_id));
67 break;
68 case ACL_GROUP:
69 value = (char *)value + sizeof(ext4_acl_entry);
70 if ((char *)value > end)
71 goto fail;
72 acl->a_entries[n].e_gid =
73 make_kgid(&init_user_ns,
74 le32_to_cpu(entry->e_id));
75 break;
76
77 default:
78 goto fail;
79 }
80 }
81 if (value != end)
82 goto fail;
83 return acl;
84
85 fail:
86 posix_acl_release(acl);
87 return ERR_PTR(-EINVAL);
88 }
89
90 /*
91 * Convert from in-memory to filesystem representation.
92 */
93 static void *
ext4_acl_to_disk(const struct posix_acl * acl,size_t * size)94 ext4_acl_to_disk(const struct posix_acl *acl, size_t *size)
95 {
96 ext4_acl_header *ext_acl;
97 char *e;
98 size_t n;
99
100 *size = ext4_acl_size(acl->a_count);
101 ext_acl = kmalloc(sizeof(ext4_acl_header) + acl->a_count *
102 sizeof(ext4_acl_entry), GFP_NOFS);
103 if (!ext_acl)
104 return ERR_PTR(-ENOMEM);
105 ext_acl->a_version = cpu_to_le32(EXT4_ACL_VERSION);
106 e = (char *)ext_acl + sizeof(ext4_acl_header);
107 for (n = 0; n < acl->a_count; n++) {
108 const struct posix_acl_entry *acl_e = &acl->a_entries[n];
109 ext4_acl_entry *entry = (ext4_acl_entry *)e;
110 entry->e_tag = cpu_to_le16(acl_e->e_tag);
111 entry->e_perm = cpu_to_le16(acl_e->e_perm);
112 switch (acl_e->e_tag) {
113 case ACL_USER:
114 entry->e_id = cpu_to_le32(
115 from_kuid(&init_user_ns, acl_e->e_uid));
116 e += sizeof(ext4_acl_entry);
117 break;
118 case ACL_GROUP:
119 entry->e_id = cpu_to_le32(
120 from_kgid(&init_user_ns, acl_e->e_gid));
121 e += sizeof(ext4_acl_entry);
122 break;
123
124 case ACL_USER_OBJ:
125 case ACL_GROUP_OBJ:
126 case ACL_MASK:
127 case ACL_OTHER:
128 e += sizeof(ext4_acl_entry_short);
129 break;
130
131 default:
132 goto fail;
133 }
134 }
135 return (char *)ext_acl;
136
137 fail:
138 kfree(ext_acl);
139 return ERR_PTR(-EINVAL);
140 }
141
142 /*
143 * Inode operation get_posix_acl().
144 *
145 * inode->i_mutex: don't care
146 */
147 struct posix_acl *
ext4_get_acl(struct inode * inode,int type)148 ext4_get_acl(struct inode *inode, int type)
149 {
150 int name_index;
151 char *value = NULL;
152 struct posix_acl *acl;
153 int retval;
154
155 switch (type) {
156 case ACL_TYPE_ACCESS:
157 name_index = EXT4_XATTR_INDEX_POSIX_ACL_ACCESS;
158 break;
159 case ACL_TYPE_DEFAULT:
160 name_index = EXT4_XATTR_INDEX_POSIX_ACL_DEFAULT;
161 break;
162 default:
163 BUG();
164 }
165 retval = ext4_xattr_get(inode, name_index, "", NULL, 0);
166 if (retval > 0) {
167 value = kmalloc(retval, GFP_NOFS);
168 if (!value)
169 return ERR_PTR(-ENOMEM);
170 retval = ext4_xattr_get(inode, name_index, "", value, retval);
171 }
172 if (retval > 0)
173 acl = ext4_acl_from_disk(value, retval);
174 else if (retval == -ENODATA || retval == -ENOSYS)
175 acl = NULL;
176 else
177 acl = ERR_PTR(retval);
178 kfree(value);
179
180 if (!IS_ERR(acl))
181 set_cached_acl(inode, type, acl);
182
183 return acl;
184 }
185
186 /*
187 * Set the access or default ACL of an inode.
188 *
189 * inode->i_mutex: down unless called from ext4_new_inode
190 */
191 static int
__ext4_set_acl(handle_t * handle,struct inode * inode,int type,struct posix_acl * acl)192 __ext4_set_acl(handle_t *handle, struct inode *inode, int type,
193 struct posix_acl *acl)
194 {
195 int name_index;
196 void *value = NULL;
197 size_t size = 0;
198 int error;
199
200 switch (type) {
201 case ACL_TYPE_ACCESS:
202 name_index = EXT4_XATTR_INDEX_POSIX_ACL_ACCESS;
203 break;
204
205 case ACL_TYPE_DEFAULT:
206 name_index = EXT4_XATTR_INDEX_POSIX_ACL_DEFAULT;
207 if (!S_ISDIR(inode->i_mode))
208 return acl ? -EACCES : 0;
209 break;
210
211 default:
212 return -EINVAL;
213 }
214 if (acl) {
215 value = ext4_acl_to_disk(acl, &size);
216 if (IS_ERR(value))
217 return (int)PTR_ERR(value);
218 }
219
220 error = ext4_xattr_set_handle(handle, inode, name_index, "",
221 value, size, 0);
222
223 kfree(value);
224 if (!error)
225 set_cached_acl(inode, type, acl);
226
227 return error;
228 }
229
230 int
ext4_set_acl(struct inode * inode,struct posix_acl * acl,int type)231 ext4_set_acl(struct inode *inode, struct posix_acl *acl, int type)
232 {
233 handle_t *handle;
234 int error, retries = 0;
235 umode_t mode = inode->i_mode;
236 int update_mode = 0;
237
238 retry:
239 handle = ext4_journal_start(inode, EXT4_HT_XATTR,
240 ext4_jbd2_credits_xattr(inode));
241 if (IS_ERR(handle))
242 return PTR_ERR(handle);
243
244 if ((type == ACL_TYPE_ACCESS) && acl) {
245 error = posix_acl_update_mode(inode, &mode, &acl);
246 if (error)
247 goto out_stop;
248 update_mode = 1;
249 }
250
251 error = __ext4_set_acl(handle, inode, type, acl);
252 if (!error && update_mode) {
253 inode->i_mode = mode;
254 inode->i_ctime = ext4_current_time(inode);
255 ext4_mark_inode_dirty(handle, inode);
256 }
257 out_stop:
258 ext4_journal_stop(handle);
259 if (error == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries))
260 goto retry;
261 return error;
262 }
263
264 /*
265 * Initialize the ACLs of a new inode. Called from ext4_new_inode.
266 *
267 * dir->i_mutex: down
268 * inode->i_mutex: up (access to inode is still exclusive)
269 */
270 int
ext4_init_acl(handle_t * handle,struct inode * inode,struct inode * dir)271 ext4_init_acl(handle_t *handle, struct inode *inode, struct inode *dir)
272 {
273 struct posix_acl *default_acl, *acl;
274 int error;
275
276 error = posix_acl_create(dir, &inode->i_mode, &default_acl, &acl);
277 if (error)
278 return error;
279
280 if (default_acl) {
281 error = __ext4_set_acl(handle, inode, ACL_TYPE_DEFAULT,
282 default_acl);
283 posix_acl_release(default_acl);
284 }
285 if (acl) {
286 if (!error)
287 error = __ext4_set_acl(handle, inode, ACL_TYPE_ACCESS,
288 acl);
289 posix_acl_release(acl);
290 }
291 return error;
292 }
293