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 * |
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(error: -EINVAL); |
28 | if (((ext4_acl_header *)value)->a_version != |
29 | cpu_to_le32(EXT4_ACL_VERSION)) |
30 | return ERR_PTR(error: -EINVAL); |
31 | value = (char *)value + sizeof(ext4_acl_header); |
32 | count = ext4_acl_count(size); |
33 | if (count < 0) |
34 | return ERR_PTR(error: -EINVAL); |
35 | if (count == 0) |
36 | return NULL; |
37 | acl = posix_acl_alloc(count, GFP_NOFS); |
38 | if (!acl) |
39 | return ERR_PTR(error: -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(from: &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(from: &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(error: -EINVAL); |
85 | } |
86 | |
87 | /* |
88 | * Convert from in-memory to filesystem representation. |
89 | */ |
90 | static void * |
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(count: acl->a_count); |
98 | ext_acl = kmalloc(size: sizeof(ext4_acl_header) + acl->a_count * |
99 | sizeof(ext4_acl_entry), GFP_NOFS); |
100 | if (!ext_acl) |
101 | return ERR_PTR(error: -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(objp: ext_acl); |
136 | return ERR_PTR(error: -EINVAL); |
137 | } |
138 | |
139 | /* |
140 | * Inode operation get_posix_acl(). |
141 | * |
142 | * inode->i_rwsem: don't care |
143 | */ |
144 | struct posix_acl * |
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(error: -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(size: retval, GFP_NOFS); |
168 | if (!value) |
169 | return ERR_PTR(error: -ENOMEM); |
170 | retval = ext4_xattr_get(inode, name_index, "" , value, retval); |
171 | } |
172 | if (retval > 0) |
173 | acl = ext4_acl_from_disk(value, size: retval); |
174 | else if (retval == -ENODATA || retval == -ENOSYS) |
175 | acl = NULL; |
176 | else |
177 | acl = ERR_PTR(error: retval); |
178 | kfree(objp: 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 |
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: &size); |
213 | if (IS_ERR(ptr: value)) |
214 | return (int)PTR_ERR(ptr: value); |
215 | } |
216 | |
217 | error = ext4_xattr_set_handle(handle, inode, name_index, "" , |
218 | value, size, xattr_flags); |
219 | |
220 | kfree(objp: value); |
221 | if (!error) |
222 | set_cached_acl(inode, type, acl); |
223 | |
224 | return error; |
225 | } |
226 | |
227 | int |
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(count: 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, value_len: acl_size, is_create: false /* is_create */, |
243 | credits: &credits); |
244 | if (error) |
245 | return error; |
246 | |
247 | handle = ext4_journal_start(inode, EXT4_HT_XATTR, credits); |
248 | if (IS_ERR(ptr: handle)) |
249 | return PTR_ERR(ptr: 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, xattr_flags: 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(sb: inode->i_sb, retries: &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 |
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 | acl: default_acl, XATTR_CREATE); |
291 | posix_acl_release(acl: 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 | |