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Linux/fs/ext4/acl.c

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

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