1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * linux/fs/ext4/acl.c
4 *
5 * Copyright (C) 2001-2003 Andreas Gruenbacher, <agruen@suse.de>
6 */
7
8 #include <linux/quotaops.h>
9 #include "ext4_jbd2.h"
10 #include "ext4.h"
11 #include "xattr.h"
12 #include "acl.h"
13
14 /*
15 * Convert from filesystem to in-memory representation.
16 */
17 static struct posix_acl *
ext4_acl_from_disk(const void * value,size_t size)18 ext4_acl_from_disk(const void *value, size_t size)
19 {
20 const char *end = (char *)value + size;
21 int n, count;
22 struct posix_acl *acl;
23
24 if (!value)
25 return NULL;
26 if (size < sizeof(ext4_acl_header))
27 return ERR_PTR(-EINVAL);
28 if (((ext4_acl_header *)value)->a_version !=
29 cpu_to_le32(EXT4_ACL_VERSION))
30 return ERR_PTR(-EINVAL);
31 value = (char *)value + sizeof(ext4_acl_header);
32 count = ext4_acl_count(size);
33 if (count < 0)
34 return ERR_PTR(-EINVAL);
35 if (count == 0)
36 return NULL;
37 acl = posix_acl_alloc(count, GFP_NOFS);
38 if (!acl)
39 return ERR_PTR(-ENOMEM);
40 for (n = 0; n < count; n++) {
41 ext4_acl_entry *entry =
42 (ext4_acl_entry *)value;
43 if ((char *)value + sizeof(ext4_acl_entry_short) > end)
44 goto fail;
45 acl->a_entries[n].e_tag = le16_to_cpu(entry->e_tag);
46 acl->a_entries[n].e_perm = le16_to_cpu(entry->e_perm);
47
48 switch (acl->a_entries[n].e_tag) {
49 case ACL_USER_OBJ:
50 case ACL_GROUP_OBJ:
51 case ACL_MASK:
52 case ACL_OTHER:
53 value = (char *)value +
54 sizeof(ext4_acl_entry_short);
55 break;
56
57 case ACL_USER:
58 value = (char *)value + sizeof(ext4_acl_entry);
59 if ((char *)value > end)
60 goto fail;
61 acl->a_entries[n].e_uid =
62 make_kuid(&init_user_ns,
63 le32_to_cpu(entry->e_id));
64 break;
65 case ACL_GROUP:
66 value = (char *)value + sizeof(ext4_acl_entry);
67 if ((char *)value > end)
68 goto fail;
69 acl->a_entries[n].e_gid =
70 make_kgid(&init_user_ns,
71 le32_to_cpu(entry->e_id));
72 break;
73
74 default:
75 goto fail;
76 }
77 }
78 if (value != end)
79 goto fail;
80 return acl;
81
82 fail:
83 posix_acl_release(acl);
84 return ERR_PTR(-EINVAL);
85 }
86
87 /*
88 * Convert from in-memory to filesystem representation.
89 */
90 static void *
ext4_acl_to_disk(const struct posix_acl * acl,size_t * size)91 ext4_acl_to_disk(const struct posix_acl *acl, size_t *size)
92 {
93 ext4_acl_header *ext_acl;
94 char *e;
95 size_t n;
96
97 *size = ext4_acl_size(acl->a_count);
98 ext_acl = kmalloc(sizeof(ext4_acl_header) + acl->a_count *
99 sizeof(ext4_acl_entry), GFP_NOFS);
100 if (!ext_acl)
101 return ERR_PTR(-ENOMEM);
102 ext_acl->a_version = cpu_to_le32(EXT4_ACL_VERSION);
103 e = (char *)ext_acl + sizeof(ext4_acl_header);
104 for (n = 0; n < acl->a_count; n++) {
105 const struct posix_acl_entry *acl_e = &acl->a_entries[n];
106 ext4_acl_entry *entry = (ext4_acl_entry *)e;
107 entry->e_tag = cpu_to_le16(acl_e->e_tag);
108 entry->e_perm = cpu_to_le16(acl_e->e_perm);
109 switch (acl_e->e_tag) {
110 case ACL_USER:
111 entry->e_id = cpu_to_le32(
112 from_kuid(&init_user_ns, acl_e->e_uid));
113 e += sizeof(ext4_acl_entry);
114 break;
115 case ACL_GROUP:
116 entry->e_id = cpu_to_le32(
117 from_kgid(&init_user_ns, acl_e->e_gid));
118 e += sizeof(ext4_acl_entry);
119 break;
120
121 case ACL_USER_OBJ:
122 case ACL_GROUP_OBJ:
123 case ACL_MASK:
124 case ACL_OTHER:
125 e += sizeof(ext4_acl_entry_short);
126 break;
127
128 default:
129 goto fail;
130 }
131 }
132 return (char *)ext_acl;
133
134 fail:
135 kfree(ext_acl);
136 return ERR_PTR(-EINVAL);
137 }
138
139 /*
140 * Inode operation get_posix_acl().
141 *
142 * inode->i_rwsem: don't care
143 */
144 struct posix_acl *
ext4_get_acl(struct inode * inode,int type,bool rcu)145 ext4_get_acl(struct inode *inode, int type, bool rcu)
146 {
147 int name_index;
148 char *value = NULL;
149 struct posix_acl *acl;
150 int retval;
151
152 if (rcu)
153 return ERR_PTR(-ECHILD);
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 return acl;
181 }
182
183 /*
184 * Set the access or default ACL of an inode.
185 *
186 * inode->i_rwsem: down unless called from ext4_new_inode
187 */
188 static int
__ext4_set_acl(handle_t * handle,struct inode * inode,int type,struct posix_acl * acl,int xattr_flags)189 __ext4_set_acl(handle_t *handle, struct inode *inode, int type,
190 struct posix_acl *acl, int xattr_flags)
191 {
192 int name_index;
193 void *value = NULL;
194 size_t size = 0;
195 int error;
196
197 switch (type) {
198 case ACL_TYPE_ACCESS:
199 name_index = EXT4_XATTR_INDEX_POSIX_ACL_ACCESS;
200 break;
201
202 case ACL_TYPE_DEFAULT:
203 name_index = EXT4_XATTR_INDEX_POSIX_ACL_DEFAULT;
204 if (!S_ISDIR(inode->i_mode))
205 return acl ? -EACCES : 0;
206 break;
207
208 default:
209 return -EINVAL;
210 }
211 if (acl) {
212 value = ext4_acl_to_disk(acl, &size);
213 if (IS_ERR(value))
214 return (int)PTR_ERR(value);
215 }
216
217 error = ext4_xattr_set_handle(handle, inode, name_index, "",
218 value, size, xattr_flags);
219
220 kfree(value);
221 if (!error)
222 set_cached_acl(inode, type, acl);
223
224 return error;
225 }
226
227 int
ext4_set_acl(struct mnt_idmap * idmap,struct dentry * dentry,struct posix_acl * acl,int type)228 ext4_set_acl(struct mnt_idmap *idmap, struct dentry *dentry,
229 struct posix_acl *acl, int type)
230 {
231 handle_t *handle;
232 int error, credits, retries = 0;
233 size_t acl_size = acl ? ext4_acl_size(acl->a_count) : 0;
234 struct inode *inode = d_inode(dentry);
235 umode_t mode = inode->i_mode;
236 int update_mode = 0;
237
238 error = dquot_initialize(inode);
239 if (error)
240 return error;
241 retry:
242 error = ext4_xattr_set_credits(inode, acl_size, false /* is_create */,
243 &credits);
244 if (error)
245 return error;
246
247 handle = ext4_journal_start(inode, EXT4_HT_XATTR, credits);
248 if (IS_ERR(handle))
249 return PTR_ERR(handle);
250
251 if ((type == ACL_TYPE_ACCESS) && acl) {
252 error = posix_acl_update_mode(idmap, inode, &mode, &acl);
253 if (error)
254 goto out_stop;
255 if (mode != inode->i_mode)
256 update_mode = 1;
257 }
258
259 error = __ext4_set_acl(handle, inode, type, acl, 0 /* xattr_flags */);
260 if (!error && update_mode) {
261 inode->i_mode = mode;
262 inode_set_ctime_current(inode);
263 error = ext4_mark_inode_dirty(handle, inode);
264 }
265 out_stop:
266 ext4_journal_stop(handle);
267 if (error == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries))
268 goto retry;
269 return error;
270 }
271
272 /*
273 * Initialize the ACLs of a new inode. Called from ext4_new_inode.
274 *
275 * dir->i_rwsem: down
276 * inode->i_rwsem: up (access to inode is still exclusive)
277 */
278 int
ext4_init_acl(handle_t * handle,struct inode * inode,struct inode * dir)279 ext4_init_acl(handle_t *handle, struct inode *inode, struct inode *dir)
280 {
281 struct posix_acl *default_acl, *acl;
282 int error;
283
284 error = posix_acl_create(dir, &inode->i_mode, &default_acl, &acl);
285 if (error)
286 return error;
287
288 if (default_acl) {
289 error = __ext4_set_acl(handle, inode, ACL_TYPE_DEFAULT,
290 default_acl, XATTR_CREATE);
291 posix_acl_release(default_acl);
292 } else {
293 inode->i_default_acl = NULL;
294 }
295 if (acl) {
296 if (!error)
297 error = __ext4_set_acl(handle, inode, ACL_TYPE_ACCESS,
298 acl, XATTR_CREATE);
299 posix_acl_release(acl);
300 } else {
301 inode->i_acl = NULL;
302 }
303 return error;
304 }
305