ext4: Don't clear SGID when inheriting ACLs
[sfrench/cifs-2.6.git] / fs / ext4 / acl.c
1 /*
2  * linux/fs/ext4/acl.c
3  *
4  * Copyright (C) 2001-2003 Andreas Gruenbacher, <agruen@suse.de>
5  */
6
7 #include <linux/quotaops.h>
8 #include "ext4_jbd2.h"
9 #include "ext4.h"
10 #include "xattr.h"
11 #include "acl.h"
12
13 /*
14  * Convert from filesystem to in-memory representation.
15  */
16 static struct posix_acl *
17 ext4_acl_from_disk(const void *value, size_t size)
18 {
19         const char *end = (char *)value + size;
20         int n, count;
21         struct posix_acl *acl;
22
23         if (!value)
24                 return NULL;
25         if (size < sizeof(ext4_acl_header))
26                  return ERR_PTR(-EINVAL);
27         if (((ext4_acl_header *)value)->a_version !=
28             cpu_to_le32(EXT4_ACL_VERSION))
29                 return ERR_PTR(-EINVAL);
30         value = (char *)value + sizeof(ext4_acl_header);
31         count = ext4_acl_count(size);
32         if (count < 0)
33                 return ERR_PTR(-EINVAL);
34         if (count == 0)
35                 return NULL;
36         acl = posix_acl_alloc(count, GFP_NOFS);
37         if (!acl)
38                 return ERR_PTR(-ENOMEM);
39         for (n = 0; n < count; n++) {
40                 ext4_acl_entry *entry =
41                         (ext4_acl_entry *)value;
42                 if ((char *)value + sizeof(ext4_acl_entry_short) > end)
43                         goto fail;
44                 acl->a_entries[n].e_tag  = le16_to_cpu(entry->e_tag);
45                 acl->a_entries[n].e_perm = le16_to_cpu(entry->e_perm);
46
47                 switch (acl->a_entries[n].e_tag) {
48                 case ACL_USER_OBJ:
49                 case ACL_GROUP_OBJ:
50                 case ACL_MASK:
51                 case ACL_OTHER:
52                         value = (char *)value +
53                                 sizeof(ext4_acl_entry_short);
54                         break;
55
56                 case ACL_USER:
57                         value = (char *)value + sizeof(ext4_acl_entry);
58                         if ((char *)value > end)
59                                 goto fail;
60                         acl->a_entries[n].e_uid =
61                                 make_kuid(&init_user_ns,
62                                           le32_to_cpu(entry->e_id));
63                         break;
64                 case ACL_GROUP:
65                         value = (char *)value + sizeof(ext4_acl_entry);
66                         if ((char *)value > end)
67                                 goto fail;
68                         acl->a_entries[n].e_gid =
69                                 make_kgid(&init_user_ns,
70                                           le32_to_cpu(entry->e_id));
71                         break;
72
73                 default:
74                         goto fail;
75                 }
76         }
77         if (value != end)
78                 goto fail;
79         return acl;
80
81 fail:
82         posix_acl_release(acl);
83         return ERR_PTR(-EINVAL);
84 }
85
86 /*
87  * Convert from in-memory to filesystem representation.
88  */
89 static void *
90 ext4_acl_to_disk(const struct posix_acl *acl, size_t *size)
91 {
92         ext4_acl_header *ext_acl;
93         char *e;
94         size_t n;
95
96         *size = ext4_acl_size(acl->a_count);
97         ext_acl = kmalloc(sizeof(ext4_acl_header) + acl->a_count *
98                         sizeof(ext4_acl_entry), GFP_NOFS);
99         if (!ext_acl)
100                 return ERR_PTR(-ENOMEM);
101         ext_acl->a_version = cpu_to_le32(EXT4_ACL_VERSION);
102         e = (char *)ext_acl + sizeof(ext4_acl_header);
103         for (n = 0; n < acl->a_count; n++) {
104                 const struct posix_acl_entry *acl_e = &acl->a_entries[n];
105                 ext4_acl_entry *entry = (ext4_acl_entry *)e;
106                 entry->e_tag  = cpu_to_le16(acl_e->e_tag);
107                 entry->e_perm = cpu_to_le16(acl_e->e_perm);
108                 switch (acl_e->e_tag) {
109                 case ACL_USER:
110                         entry->e_id = cpu_to_le32(
111                                 from_kuid(&init_user_ns, acl_e->e_uid));
112                         e += sizeof(ext4_acl_entry);
113                         break;
114                 case ACL_GROUP:
115                         entry->e_id = cpu_to_le32(
116                                 from_kgid(&init_user_ns, acl_e->e_gid));
117                         e += sizeof(ext4_acl_entry);
118                         break;
119
120                 case ACL_USER_OBJ:
121                 case ACL_GROUP_OBJ:
122                 case ACL_MASK:
123                 case ACL_OTHER:
124                         e += sizeof(ext4_acl_entry_short);
125                         break;
126
127                 default:
128                         goto fail;
129                 }
130         }
131         return (char *)ext_acl;
132
133 fail:
134         kfree(ext_acl);
135         return ERR_PTR(-EINVAL);
136 }
137
138 /*
139  * Inode operation get_posix_acl().
140  *
141  * inode->i_mutex: don't care
142  */
143 struct posix_acl *
144 ext4_get_acl(struct inode *inode, int type)
145 {
146         int name_index;
147         char *value = NULL;
148         struct posix_acl *acl;
149         int retval;
150
151         switch (type) {
152         case ACL_TYPE_ACCESS:
153                 name_index = EXT4_XATTR_INDEX_POSIX_ACL_ACCESS;
154                 break;
155         case ACL_TYPE_DEFAULT:
156                 name_index = EXT4_XATTR_INDEX_POSIX_ACL_DEFAULT;
157                 break;
158         default:
159                 BUG();
160         }
161         retval = ext4_xattr_get(inode, name_index, "", NULL, 0);
162         if (retval > 0) {
163                 value = kmalloc(retval, GFP_NOFS);
164                 if (!value)
165                         return ERR_PTR(-ENOMEM);
166                 retval = ext4_xattr_get(inode, name_index, "", value, retval);
167         }
168         if (retval > 0)
169                 acl = ext4_acl_from_disk(value, retval);
170         else if (retval == -ENODATA || retval == -ENOSYS)
171                 acl = NULL;
172         else
173                 acl = ERR_PTR(retval);
174         kfree(value);
175
176         return acl;
177 }
178
179 /*
180  * Set the access or default ACL of an inode.
181  *
182  * inode->i_mutex: down unless called from ext4_new_inode
183  */
184 static int
185 __ext4_set_acl(handle_t *handle, struct inode *inode, int type,
186              struct posix_acl *acl, int xattr_flags)
187 {
188         int name_index;
189         void *value = NULL;
190         size_t size = 0;
191         int error;
192
193         switch (type) {
194         case ACL_TYPE_ACCESS:
195                 name_index = EXT4_XATTR_INDEX_POSIX_ACL_ACCESS;
196                 break;
197
198         case ACL_TYPE_DEFAULT:
199                 name_index = EXT4_XATTR_INDEX_POSIX_ACL_DEFAULT;
200                 if (!S_ISDIR(inode->i_mode))
201                         return acl ? -EACCES : 0;
202                 break;
203
204         default:
205                 return -EINVAL;
206         }
207         if (acl) {
208                 value = ext4_acl_to_disk(acl, &size);
209                 if (IS_ERR(value))
210                         return (int)PTR_ERR(value);
211         }
212
213         error = ext4_xattr_set_handle(handle, inode, name_index, "",
214                                       value, size, xattr_flags);
215
216         kfree(value);
217         if (!error) {
218                 set_cached_acl(inode, type, acl);
219         }
220
221         return error;
222 }
223
224 int
225 ext4_set_acl(struct inode *inode, struct posix_acl *acl, int type)
226 {
227         handle_t *handle;
228         int error, credits, retries = 0;
229         size_t acl_size = acl ? ext4_acl_size(acl->a_count) : 0;
230         umode_t mode = inode->i_mode;
231         int update_mode = 0;
232
233         error = dquot_initialize(inode);
234         if (error)
235                 return error;
236 retry:
237         error = ext4_xattr_set_credits(inode, acl_size, false /* is_create */,
238                                        &credits);
239         if (error)
240                 return error;
241
242         handle = ext4_journal_start(inode, EXT4_HT_XATTR, credits);
243         if (IS_ERR(handle))
244                 return PTR_ERR(handle);
245
246         if ((type == ACL_TYPE_ACCESS) && acl) {
247                 error = posix_acl_update_mode(inode, &mode, &acl);
248                 if (error)
249                         goto out_stop;
250                 update_mode = 1;
251         }
252
253         error = __ext4_set_acl(handle, inode, type, acl, 0 /* xattr_flags */);
254         if (!error && update_mode) {
255                 inode->i_mode = mode;
256                 inode->i_ctime = current_time(inode);
257                 ext4_mark_inode_dirty(handle, inode);
258         }
259 out_stop:
260         ext4_journal_stop(handle);
261         if (error == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries))
262                 goto retry;
263         return error;
264 }
265
266 /*
267  * Initialize the ACLs of a new inode. Called from ext4_new_inode.
268  *
269  * dir->i_mutex: down
270  * inode->i_mutex: up (access to inode is still exclusive)
271  */
272 int
273 ext4_init_acl(handle_t *handle, struct inode *inode, struct inode *dir)
274 {
275         struct posix_acl *default_acl, *acl;
276         int error;
277
278         error = posix_acl_create(dir, &inode->i_mode, &default_acl, &acl);
279         if (error)
280                 return error;
281
282         if (default_acl) {
283                 error = __ext4_set_acl(handle, inode, ACL_TYPE_DEFAULT,
284                                        default_acl, XATTR_CREATE);
285                 posix_acl_release(default_acl);
286         }
287         if (acl) {
288                 if (!error)
289                         error = __ext4_set_acl(handle, inode, ACL_TYPE_ACCESS,
290                                                acl, XATTR_CREATE);
291                 posix_acl_release(acl);
292         }
293         return error;
294 }