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Linux/fs/jffs2/acl.c

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  1 /*
  2  * JFFS2 -- Journalling Flash File System, Version 2.
  3  *
  4  * Copyright © 2006  NEC Corporation
  5  *
  6  * Created by KaiGai Kohei <kaigai@ak.jp.nec.com>
  7  *
  8  * For licensing information, see the file 'LICENCE' in this directory.
  9  *
 10  */
 11 
 12 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 13 
 14 #include <linux/kernel.h>
 15 #include <linux/slab.h>
 16 #include <linux/fs.h>
 17 #include <linux/sched.h>
 18 #include <linux/time.h>
 19 #include <linux/crc32.h>
 20 #include <linux/jffs2.h>
 21 #include <linux/xattr.h>
 22 #include <linux/posix_acl_xattr.h>
 23 #include <linux/mtd/mtd.h>
 24 #include "nodelist.h"
 25 
 26 static size_t jffs2_acl_size(int count)
 27 {
 28         if (count <= 4) {
 29                 return sizeof(struct jffs2_acl_header)
 30                        + count * sizeof(struct jffs2_acl_entry_short);
 31         } else {
 32                 return sizeof(struct jffs2_acl_header)
 33                        + 4 * sizeof(struct jffs2_acl_entry_short)
 34                        + (count - 4) * sizeof(struct jffs2_acl_entry);
 35         }
 36 }
 37 
 38 static int jffs2_acl_count(size_t size)
 39 {
 40         size_t s;
 41 
 42         size -= sizeof(struct jffs2_acl_header);
 43         if (size < 4 * sizeof(struct jffs2_acl_entry_short)) {
 44                 if (size % sizeof(struct jffs2_acl_entry_short))
 45                         return -1;
 46                 return size / sizeof(struct jffs2_acl_entry_short);
 47         } else {
 48                 s = size - 4 * sizeof(struct jffs2_acl_entry_short);
 49                 if (s % sizeof(struct jffs2_acl_entry))
 50                         return -1;
 51                 return s / sizeof(struct jffs2_acl_entry) + 4;
 52         }
 53 }
 54 
 55 static struct posix_acl *jffs2_acl_from_medium(void *value, size_t size)
 56 {
 57         void *end = value + size;
 58         struct jffs2_acl_header *header = value;
 59         struct jffs2_acl_entry *entry;
 60         struct posix_acl *acl;
 61         uint32_t ver;
 62         int i, count;
 63 
 64         if (!value)
 65                 return NULL;
 66         if (size < sizeof(struct jffs2_acl_header))
 67                 return ERR_PTR(-EINVAL);
 68         ver = je32_to_cpu(header->a_version);
 69         if (ver != JFFS2_ACL_VERSION) {
 70                 JFFS2_WARNING("Invalid ACL version. (=%u)\n", ver);
 71                 return ERR_PTR(-EINVAL);
 72         }
 73 
 74         value += sizeof(struct jffs2_acl_header);
 75         count = jffs2_acl_count(size);
 76         if (count < 0)
 77                 return ERR_PTR(-EINVAL);
 78         if (count == 0)
 79                 return NULL;
 80 
 81         acl = posix_acl_alloc(count, GFP_KERNEL);
 82         if (!acl)
 83                 return ERR_PTR(-ENOMEM);
 84 
 85         for (i=0; i < count; i++) {
 86                 entry = value;
 87                 if (value + sizeof(struct jffs2_acl_entry_short) > end)
 88                         goto fail;
 89                 acl->a_entries[i].e_tag = je16_to_cpu(entry->e_tag);
 90                 acl->a_entries[i].e_perm = je16_to_cpu(entry->e_perm);
 91                 switch (acl->a_entries[i].e_tag) {
 92                         case ACL_USER_OBJ:
 93                         case ACL_GROUP_OBJ:
 94                         case ACL_MASK:
 95                         case ACL_OTHER:
 96                                 value += sizeof(struct jffs2_acl_entry_short);
 97                                 break;
 98 
 99                         case ACL_USER:
100                                 value += sizeof(struct jffs2_acl_entry);
101                                 if (value > end)
102                                         goto fail;
103                                 acl->a_entries[i].e_uid =
104                                         make_kuid(&init_user_ns,
105                                                   je32_to_cpu(entry->e_id));
106                                 break;
107                         case ACL_GROUP:
108                                 value += sizeof(struct jffs2_acl_entry);
109                                 if (value > end)
110                                         goto fail;
111                                 acl->a_entries[i].e_gid =
112                                         make_kgid(&init_user_ns,
113                                                   je32_to_cpu(entry->e_id));
114                                 break;
115 
116                         default:
117                                 goto fail;
118                 }
119         }
120         if (value != end)
121                 goto fail;
122         return acl;
123  fail:
124         posix_acl_release(acl);
125         return ERR_PTR(-EINVAL);
126 }
127 
128 static void *jffs2_acl_to_medium(const struct posix_acl *acl, size_t *size)
129 {
130         struct jffs2_acl_header *header;
131         struct jffs2_acl_entry *entry;
132         void *e;
133         size_t i;
134 
135         *size = jffs2_acl_size(acl->a_count);
136         header = kmalloc(sizeof(*header) + acl->a_count * sizeof(*entry), GFP_KERNEL);
137         if (!header)
138                 return ERR_PTR(-ENOMEM);
139         header->a_version = cpu_to_je32(JFFS2_ACL_VERSION);
140         e = header + 1;
141         for (i=0; i < acl->a_count; i++) {
142                 const struct posix_acl_entry *acl_e = &acl->a_entries[i];
143                 entry = e;
144                 entry->e_tag = cpu_to_je16(acl_e->e_tag);
145                 entry->e_perm = cpu_to_je16(acl_e->e_perm);
146                 switch(acl_e->e_tag) {
147                         case ACL_USER:
148                                 entry->e_id = cpu_to_je32(
149                                         from_kuid(&init_user_ns, acl_e->e_uid));
150                                 e += sizeof(struct jffs2_acl_entry);
151                                 break;
152                         case ACL_GROUP:
153                                 entry->e_id = cpu_to_je32(
154                                         from_kgid(&init_user_ns, acl_e->e_gid));
155                                 e += sizeof(struct jffs2_acl_entry);
156                                 break;
157 
158                         case ACL_USER_OBJ:
159                         case ACL_GROUP_OBJ:
160                         case ACL_MASK:
161                         case ACL_OTHER:
162                                 e += sizeof(struct jffs2_acl_entry_short);
163                                 break;
164 
165                         default:
166                                 goto fail;
167                 }
168         }
169         return header;
170  fail:
171         kfree(header);
172         return ERR_PTR(-EINVAL);
173 }
174 
175 struct posix_acl *jffs2_get_acl(struct inode *inode, int type)
176 {
177         struct posix_acl *acl;
178         char *value = NULL;
179         int rc, xprefix;
180 
181         switch (type) {
182         case ACL_TYPE_ACCESS:
183                 xprefix = JFFS2_XPREFIX_ACL_ACCESS;
184                 break;
185         case ACL_TYPE_DEFAULT:
186                 xprefix = JFFS2_XPREFIX_ACL_DEFAULT;
187                 break;
188         default:
189                 BUG();
190         }
191         rc = do_jffs2_getxattr(inode, xprefix, "", NULL, 0);
192         if (rc > 0) {
193                 value = kmalloc(rc, GFP_KERNEL);
194                 if (!value)
195                         return ERR_PTR(-ENOMEM);
196                 rc = do_jffs2_getxattr(inode, xprefix, "", value, rc);
197         }
198         if (rc > 0) {
199                 acl = jffs2_acl_from_medium(value, rc);
200         } else if (rc == -ENODATA || rc == -ENOSYS) {
201                 acl = NULL;
202         } else {
203                 acl = ERR_PTR(rc);
204         }
205         kfree(value);
206         return acl;
207 }
208 
209 static int __jffs2_set_acl(struct inode *inode, int xprefix, struct posix_acl *acl)
210 {
211         char *value = NULL;
212         size_t size = 0;
213         int rc;
214 
215         if (acl) {
216                 value = jffs2_acl_to_medium(acl, &size);
217                 if (IS_ERR(value))
218                         return PTR_ERR(value);
219         }
220         rc = do_jffs2_setxattr(inode, xprefix, "", value, size, 0);
221         if (!value && rc == -ENODATA)
222                 rc = 0;
223         kfree(value);
224 
225         return rc;
226 }
227 
228 int jffs2_set_acl(struct inode *inode, struct posix_acl *acl, int type)
229 {
230         int rc, xprefix;
231 
232         switch (type) {
233         case ACL_TYPE_ACCESS:
234                 xprefix = JFFS2_XPREFIX_ACL_ACCESS;
235                 if (acl) {
236                         umode_t mode;
237 
238                         rc = posix_acl_update_mode(inode, &mode, &acl);
239                         if (rc)
240                                 return rc;
241                         if (inode->i_mode != mode) {
242                                 struct iattr attr;
243 
244                                 attr.ia_valid = ATTR_MODE | ATTR_CTIME;
245                                 attr.ia_mode = mode;
246                                 attr.ia_ctime = CURRENT_TIME_SEC;
247                                 rc = jffs2_do_setattr(inode, &attr);
248                                 if (rc < 0)
249                                         return rc;
250                         }
251                 }
252                 break;
253         case ACL_TYPE_DEFAULT:
254                 xprefix = JFFS2_XPREFIX_ACL_DEFAULT;
255                 if (!S_ISDIR(inode->i_mode))
256                         return acl ? -EACCES : 0;
257                 break;
258         default:
259                 return -EINVAL;
260         }
261         rc = __jffs2_set_acl(inode, xprefix, acl);
262         if (!rc)
263                 set_cached_acl(inode, type, acl);
264         return rc;
265 }
266 
267 int jffs2_init_acl_pre(struct inode *dir_i, struct inode *inode, umode_t *i_mode)
268 {
269         struct posix_acl *default_acl, *acl;
270         int rc;
271 
272         cache_no_acl(inode);
273 
274         rc = posix_acl_create(dir_i, i_mode, &default_acl, &acl);
275         if (rc)
276                 return rc;
277 
278         if (default_acl) {
279                 set_cached_acl(inode, ACL_TYPE_DEFAULT, default_acl);
280                 posix_acl_release(default_acl);
281         }
282         if (acl) {
283                 set_cached_acl(inode, ACL_TYPE_ACCESS, acl);
284                 posix_acl_release(acl);
285         }
286         return 0;
287 }
288 
289 int jffs2_init_acl_post(struct inode *inode)
290 {
291         int rc;
292 
293         if (inode->i_default_acl) {
294                 rc = __jffs2_set_acl(inode, JFFS2_XPREFIX_ACL_DEFAULT, inode->i_default_acl);
295                 if (rc)
296                         return rc;
297         }
298 
299         if (inode->i_acl) {
300                 rc = __jffs2_set_acl(inode, JFFS2_XPREFIX_ACL_ACCESS, inode->i_acl);
301                 if (rc)
302                         return rc;
303         }
304 
305         return 0;
306 }
307 

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