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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * linux/fs/ext2/acl.c
4 *
5 * Copyright (C) 2001-2003 Andreas Gruenbacher, <[email protected]>
6 */
7
8#include <linux/init.h>
9#include <linux/sched.h>
10#include <linux/slab.h>
11#include <linux/fs.h>
12#include "ext2.h"
13#include "xattr.h"
14#include "acl.h"
15
16/*
17 * Convert from filesystem to in-memory representation.
18 */
19static struct posix_acl *
20ext2_acl_from_disk(const void *value, size_t size)
21{
22 const char *end = (char *)value + size;
23 int n, count;
24 struct posix_acl *acl;
25
26 if (!value)
27 return NULL;
28 if (size < sizeof(ext2_acl_header))
29 return ERR_PTR(-EINVAL);
30 if (((ext2_acl_header *)value)->a_version !=
31 cpu_to_le32(EXT2_ACL_VERSION))
32 return ERR_PTR(-EINVAL);
33 value = (char *)value + sizeof(ext2_acl_header);
34 count = ext2_acl_count(size);
35 if (count < 0)
36 return ERR_PTR(-EINVAL);
37 if (count == 0)
38 return NULL;
39 acl = posix_acl_alloc(count, GFP_KERNEL);
40 if (!acl)
41 return ERR_PTR(-ENOMEM);
42 for (n=0; n < count; n++) {
43 ext2_acl_entry *entry =
44 (ext2_acl_entry *)value;
45 if ((char *)value + sizeof(ext2_acl_entry_short) > end)
46 goto fail;
47 acl->a_entries[n].e_tag = le16_to_cpu(entry->e_tag);
48 acl->a_entries[n].e_perm = le16_to_cpu(entry->e_perm);
49 switch(acl->a_entries[n].e_tag) {
50 case ACL_USER_OBJ:
51 case ACL_GROUP_OBJ:
52 case ACL_MASK:
53 case ACL_OTHER:
54 value = (char *)value +
55 sizeof(ext2_acl_entry_short);
56 break;
57
58 case ACL_USER:
59 value = (char *)value + sizeof(ext2_acl_entry);
60 if ((char *)value > end)
61 goto fail;
62 acl->a_entries[n].e_uid =
63 make_kuid(&init_user_ns,
64 le32_to_cpu(entry->e_id));
65 break;
66 case ACL_GROUP:
67 value = (char *)value + sizeof(ext2_acl_entry);
68 if ((char *)value > end)
69 goto fail;
70 acl->a_entries[n].e_gid =
71 make_kgid(&init_user_ns,
72 le32_to_cpu(entry->e_id));
73 break;
74
75 default:
76 goto fail;
77 }
78 }
79 if (value != end)
80 goto fail;
81 return acl;
82
83fail:
84 posix_acl_release(acl);
85 return ERR_PTR(-EINVAL);
86}
87
88/*
89 * Convert from in-memory to filesystem representation.
90 */
91static void *
92ext2_acl_to_disk(const struct posix_acl *acl, size_t *size)
93{
94 ext2_acl_header *ext_acl;
95 char *e;
96 size_t n;
97
98 *size = ext2_acl_size(acl->a_count);
99 ext_acl = kmalloc(sizeof(ext2_acl_header) + acl->a_count *
100 sizeof(ext2_acl_entry), GFP_KERNEL);
101 if (!ext_acl)
102 return ERR_PTR(-ENOMEM);
103 ext_acl->a_version = cpu_to_le32(EXT2_ACL_VERSION);
104 e = (char *)ext_acl + sizeof(ext2_acl_header);
105 for (n=0; n < acl->a_count; n++) {
106 const struct posix_acl_entry *acl_e = &acl->a_entries[n];
107 ext2_acl_entry *entry = (ext2_acl_entry *)e;
108 entry->e_tag = cpu_to_le16(acl_e->e_tag);
109 entry->e_perm = cpu_to_le16(acl_e->e_perm);
110 switch(acl_e->e_tag) {
111 case ACL_USER:
112 entry->e_id = cpu_to_le32(
113 from_kuid(&init_user_ns, acl_e->e_uid));
114 e += sizeof(ext2_acl_entry);
115 break;
116 case ACL_GROUP:
117 entry->e_id = cpu_to_le32(
118 from_kgid(&init_user_ns, acl_e->e_gid));
119 e += sizeof(ext2_acl_entry);
120 break;
121
122 case ACL_USER_OBJ:
123 case ACL_GROUP_OBJ:
124 case ACL_MASK:
125 case ACL_OTHER:
126 e += sizeof(ext2_acl_entry_short);
127 break;
128
129 default:
130 goto fail;
131 }
132 }
133 return (char *)ext_acl;
134
135fail:
136 kfree(ext_acl);
137 return ERR_PTR(-EINVAL);
138}
139
140/*
141 * inode->i_mutex: don't care
142 */
143struct posix_acl *
144ext2_get_acl(struct inode *inode, int type, bool rcu)
145{
146 int name_index;
147 char *value = NULL;
148 struct posix_acl *acl;
149 int retval;
150
151 if (rcu)
152 return ERR_PTR(-ECHILD);
153
154 switch (type) {
155 case ACL_TYPE_ACCESS:
156 name_index = EXT2_XATTR_INDEX_POSIX_ACL_ACCESS;
157 break;
158 case ACL_TYPE_DEFAULT:
159 name_index = EXT2_XATTR_INDEX_POSIX_ACL_DEFAULT;
160 break;
161 default:
162 BUG();
163 }
164 retval = ext2_xattr_get(inode, name_index, "", NULL, 0);
165 if (retval > 0) {
166 value = kmalloc(retval, GFP_KERNEL);
167 if (!value)
168 return ERR_PTR(-ENOMEM);
169 retval = ext2_xattr_get(inode, name_index, "", value, retval);
170 }
171 if (retval > 0)
172 acl = ext2_acl_from_disk(value, retval);
173 else if (retval == -ENODATA || retval == -ENOSYS)
174 acl = NULL;
175 else
176 acl = ERR_PTR(retval);
177 kfree(value);
178
179 return acl;
180}
181
182static int
183__ext2_set_acl(struct inode *inode, struct posix_acl *acl, int type)
184{
185 int name_index;
186 void *value = NULL;
187 size_t size = 0;
188 int error;
189
190 switch(type) {
191 case ACL_TYPE_ACCESS:
192 name_index = EXT2_XATTR_INDEX_POSIX_ACL_ACCESS;
193 break;
194
195 case ACL_TYPE_DEFAULT:
196 name_index = EXT2_XATTR_INDEX_POSIX_ACL_DEFAULT;
197 if (!S_ISDIR(inode->i_mode))
198 return acl ? -EACCES : 0;
199 break;
200
201 default:
202 return -EINVAL;
203 }
204 if (acl) {
205 value = ext2_acl_to_disk(acl, &size);
206 if (IS_ERR(value))
207 return (int)PTR_ERR(value);
208 }
209
210 error = ext2_xattr_set(inode, name_index, "", value, size, 0);
211
212 kfree(value);
213 if (!error)
214 set_cached_acl(inode, type, acl);
215 return error;
216}
217
218/*
219 * inode->i_mutex: down
220 */
221int
222ext2_set_acl(const struct mnt_idmap *idmap, struct dentry *dentry,
223 struct posix_acl *acl, int type)
224{
225 int error;
226 int update_mode = 0;
227 struct inode *inode = d_inode(dentry);
228 umode_t mode = inode->i_mode;
229
230 if (type == ACL_TYPE_ACCESS && acl) {
231 error = posix_acl_update_mode(&nop_mnt_idmap, inode, &mode,
232 &acl);
233 if (error)
234 return error;
235 update_mode = 1;
236 }
237 error = __ext2_set_acl(inode, acl, type);
238 if (!error && update_mode) {
239 inode->i_mode = mode;
240 inode_set_ctime_current(inode);
241 mark_inode_dirty(inode);
242 }
243 return error;
244}
245
246/*
247 * Initialize the ACLs of a new inode. Called from ext2_new_inode.
248 *
249 * dir->i_mutex: down
250 * inode->i_mutex: up (access to inode is still exclusive)
251 */
252int
253ext2_init_acl(struct inode *inode, struct inode *dir)
254{
255 struct posix_acl *default_acl, *acl;
256 int error;
257
258 error = posix_acl_create(dir, &inode->i_mode, &default_acl, &acl);
259 if (error)
260 return error;
261
262 if (default_acl) {
263 error = __ext2_set_acl(inode, default_acl, ACL_TYPE_DEFAULT);
264 posix_acl_release(default_acl);
265 } else {
266 inode->i_default_acl = NULL;
267 }
268 if (acl) {
269 if (!error)
270 error = __ext2_set_acl(inode, acl, ACL_TYPE_ACCESS);
271 posix_acl_release(acl);
272 } else {
273 inode->i_acl = NULL;
274 }
275 return error;
276}