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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         acl = get_cached_acl(inode, type);
182         if (acl != ACL_NOT_CACHED)
183                 return acl;
184 
185         switch (type) {
186         case ACL_TYPE_ACCESS:
187                 xprefix = JFFS2_XPREFIX_ACL_ACCESS;
188                 break;
189         case ACL_TYPE_DEFAULT:
190                 xprefix = JFFS2_XPREFIX_ACL_DEFAULT;
191                 break;
192         default:
193                 BUG();
194         }
195         rc = do_jffs2_getxattr(inode, xprefix, "", NULL, 0);
196         if (rc > 0) {
197                 value = kmalloc(rc, GFP_KERNEL);
198                 if (!value)
199                         return ERR_PTR(-ENOMEM);
200                 rc = do_jffs2_getxattr(inode, xprefix, "", value, rc);
201         }
202         if (rc > 0) {
203                 acl = jffs2_acl_from_medium(value, rc);
204         } else if (rc == -ENODATA || rc == -ENOSYS) {
205                 acl = NULL;
206         } else {
207                 acl = ERR_PTR(rc);
208         }
209         if (value)
210                 kfree(value);
211         if (!IS_ERR(acl))
212                 set_cached_acl(inode, type, acl);
213         return acl;
214 }
215 
216 static int __jffs2_set_acl(struct inode *inode, int xprefix, struct posix_acl *acl)
217 {
218         char *value = NULL;
219         size_t size = 0;
220         int rc;
221 
222         if (acl) {
223                 value = jffs2_acl_to_medium(acl, &size);
224                 if (IS_ERR(value))
225                         return PTR_ERR(value);
226         }
227         rc = do_jffs2_setxattr(inode, xprefix, "", value, size, 0);
228         if (!value && rc == -ENODATA)
229                 rc = 0;
230         kfree(value);
231 
232         return rc;
233 }
234 
235 static int jffs2_set_acl(struct inode *inode, int type, struct posix_acl *acl)
236 {
237         int rc, xprefix;
238 
239         if (S_ISLNK(inode->i_mode))
240                 return -EOPNOTSUPP;
241 
242         switch (type) {
243         case ACL_TYPE_ACCESS:
244                 xprefix = JFFS2_XPREFIX_ACL_ACCESS;
245                 if (acl) {
246                         umode_t mode;
247 
248                         rc = posix_acl_update_mode(inode, &mode, &acl);
249                         if (rc)
250                                 return rc;
251                         if (inode->i_mode != mode) {
252                                 struct iattr attr;
253 
254                                 attr.ia_valid = ATTR_MODE | ATTR_CTIME;
255                                 attr.ia_mode = mode;
256                                 attr.ia_ctime = CURRENT_TIME_SEC;
257                                 rc = jffs2_do_setattr(inode, &attr);
258                                 if (rc < 0)
259                                         return rc;
260                         }
261                 }
262                 break;
263         case ACL_TYPE_DEFAULT:
264                 xprefix = JFFS2_XPREFIX_ACL_DEFAULT;
265                 if (!S_ISDIR(inode->i_mode))
266                         return acl ? -EACCES : 0;
267                 break;
268         default:
269                 return -EINVAL;
270         }
271         rc = __jffs2_set_acl(inode, xprefix, acl);
272         if (!rc)
273                 set_cached_acl(inode, type, acl);
274         return rc;
275 }
276 
277 int jffs2_init_acl_pre(struct inode *dir_i, struct inode *inode, umode_t *i_mode)
278 {
279         struct posix_acl *acl;
280         int rc;
281 
282         cache_no_acl(inode);
283 
284         if (S_ISLNK(*i_mode))
285                 return 0;       /* Symlink always has no-ACL */
286 
287         acl = jffs2_get_acl(dir_i, ACL_TYPE_DEFAULT);
288         if (IS_ERR(acl))
289                 return PTR_ERR(acl);
290 
291         if (!acl) {
292                 *i_mode &= ~current_umask();
293         } else {
294                 if (S_ISDIR(*i_mode))
295                         set_cached_acl(inode, ACL_TYPE_DEFAULT, acl);
296 
297                 rc = posix_acl_create(&acl, GFP_KERNEL, i_mode);
298                 if (rc < 0)
299                         return rc;
300                 if (rc > 0)
301                         set_cached_acl(inode, ACL_TYPE_ACCESS, acl);
302 
303                 posix_acl_release(acl);
304         }
305         return 0;
306 }
307 
308 int jffs2_init_acl_post(struct inode *inode)
309 {
310         int rc;
311 
312         if (inode->i_default_acl) {
313                 rc = __jffs2_set_acl(inode, JFFS2_XPREFIX_ACL_DEFAULT, inode->i_default_acl);
314                 if (rc)
315                         return rc;
316         }
317 
318         if (inode->i_acl) {
319                 rc = __jffs2_set_acl(inode, JFFS2_XPREFIX_ACL_ACCESS, inode->i_acl);
320                 if (rc)
321                         return rc;
322         }
323 
324         return 0;
325 }
326 
327 int jffs2_acl_chmod(struct inode *inode)
328 {
329         struct posix_acl *acl;
330         int rc;
331 
332         if (S_ISLNK(inode->i_mode))
333                 return -EOPNOTSUPP;
334         acl = jffs2_get_acl(inode, ACL_TYPE_ACCESS);
335         if (IS_ERR(acl) || !acl)
336                 return PTR_ERR(acl);
337         rc = posix_acl_chmod(&acl, GFP_KERNEL, inode->i_mode);
338         if (rc)
339                 return rc;
340         rc = jffs2_set_acl(inode, ACL_TYPE_ACCESS, acl);
341         posix_acl_release(acl);
342         return rc;
343 }
344 
345 static size_t jffs2_acl_access_listxattr(struct dentry *dentry, char *list,
346                 size_t list_size, const char *name, size_t name_len, int type)
347 {
348         const int retlen = sizeof(POSIX_ACL_XATTR_ACCESS);
349 
350         if (list && retlen <= list_size)
351                 strcpy(list, POSIX_ACL_XATTR_ACCESS);
352         return retlen;
353 }
354 
355 static size_t jffs2_acl_default_listxattr(struct dentry *dentry, char *list,
356                 size_t list_size, const char *name, size_t name_len, int type)
357 {
358         const int retlen = sizeof(POSIX_ACL_XATTR_DEFAULT);
359 
360         if (list && retlen <= list_size)
361                 strcpy(list, POSIX_ACL_XATTR_DEFAULT);
362         return retlen;
363 }
364 
365 static int jffs2_acl_getxattr(struct dentry *dentry, const char *name,
366                 void *buffer, size_t size, int type)
367 {
368         struct posix_acl *acl;
369         int rc;
370 
371         if (name[0] != '\0')
372                 return -EINVAL;
373 
374         acl = jffs2_get_acl(dentry->d_inode, type);
375         if (IS_ERR(acl))
376                 return PTR_ERR(acl);
377         if (!acl)
378                 return -ENODATA;
379         rc = posix_acl_to_xattr(&init_user_ns, acl, buffer, size);
380         posix_acl_release(acl);
381 
382         return rc;
383 }
384 
385 static int jffs2_acl_setxattr(struct dentry *dentry, const char *name,
386                 const void *value, size_t size, int flags, int type)
387 {
388         struct posix_acl *acl;
389         int rc;
390 
391         if (name[0] != '\0')
392                 return -EINVAL;
393         if (!inode_owner_or_capable(dentry->d_inode))
394                 return -EPERM;
395 
396         if (value) {
397                 acl = posix_acl_from_xattr(&init_user_ns, value, size);
398                 if (IS_ERR(acl))
399                         return PTR_ERR(acl);
400                 if (acl) {
401                         rc = posix_acl_valid(acl);
402                         if (rc)
403                                 goto out;
404                 }
405         } else {
406                 acl = NULL;
407         }
408         rc = jffs2_set_acl(dentry->d_inode, type, acl);
409  out:
410         posix_acl_release(acl);
411         return rc;
412 }
413 
414 const struct xattr_handler jffs2_acl_access_xattr_handler = {
415         .prefix = POSIX_ACL_XATTR_ACCESS,
416         .flags  = ACL_TYPE_DEFAULT,
417         .list   = jffs2_acl_access_listxattr,
418         .get    = jffs2_acl_getxattr,
419         .set    = jffs2_acl_setxattr,
420 };
421 
422 const struct xattr_handler jffs2_acl_default_xattr_handler = {
423         .prefix = POSIX_ACL_XATTR_DEFAULT,
424         .flags  = ACL_TYPE_DEFAULT,
425         .list   = jffs2_acl_default_listxattr,
426         .get    = jffs2_acl_getxattr,
427         .set    = jffs2_acl_setxattr,
428 };
429 

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