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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 <[email protected]>
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 = inode->i_mode;
247  rc = posix_acl_equiv_mode(acl, &mode);
248  if (rc < 0)
249  return rc;
250  if (inode->i_mode != mode) {
251  struct iattr attr;
252 
253  attr.ia_valid = ATTR_MODE | ATTR_CTIME;
254  attr.ia_mode = mode;
255  attr.ia_ctime = CURRENT_TIME_SEC;
256  rc = jffs2_do_setattr(inode, &attr);
257  if (rc < 0)
258  return rc;
259  }
260  if (rc == 0)
261  acl = NULL;
262  }
263  break;
264  case ACL_TYPE_DEFAULT:
265  xprefix = JFFS2_XPREFIX_ACL_DEFAULT;
266  if (!S_ISDIR(inode->i_mode))
267  return acl ? -EACCES : 0;
268  break;
269  default:
270  return -EINVAL;
271  }
272  rc = __jffs2_set_acl(inode, xprefix, acl);
273  if (!rc)
274  set_cached_acl(inode, type, acl);
275  return rc;
276 }
277 
278 int jffs2_init_acl_pre(struct inode *dir_i, struct inode *inode, umode_t *i_mode)
279 {
280  struct posix_acl *acl;
281  int rc;
282 
283  cache_no_acl(inode);
284 
285  if (S_ISLNK(*i_mode))
286  return 0; /* Symlink always has no-ACL */
287 
288  acl = jffs2_get_acl(dir_i, ACL_TYPE_DEFAULT);
289  if (IS_ERR(acl))
290  return PTR_ERR(acl);
291 
292  if (!acl) {
293  *i_mode &= ~current_umask();
294  } else {
295  if (S_ISDIR(*i_mode))
296  set_cached_acl(inode, ACL_TYPE_DEFAULT, acl);
297 
298  rc = posix_acl_create(&acl, GFP_KERNEL, i_mode);
299  if (rc < 0)
300  return rc;
301  if (rc > 0)
302  set_cached_acl(inode, ACL_TYPE_ACCESS, acl);
303 
304  posix_acl_release(acl);
305  }
306  return 0;
307 }
308 
309 int jffs2_init_acl_post(struct inode *inode)
310 {
311  int rc;
312 
313  if (inode->i_default_acl) {
314  rc = __jffs2_set_acl(inode, JFFS2_XPREFIX_ACL_DEFAULT, inode->i_default_acl);
315  if (rc)
316  return rc;
317  }
318 
319  if (inode->i_acl) {
320  rc = __jffs2_set_acl(inode, JFFS2_XPREFIX_ACL_ACCESS, inode->i_acl);
321  if (rc)
322  return rc;
323  }
324 
325  return 0;
326 }
327 
328 int jffs2_acl_chmod(struct inode *inode)
329 {
330  struct posix_acl *acl;
331  int rc;
332 
333  if (S_ISLNK(inode->i_mode))
334  return -EOPNOTSUPP;
335  acl = jffs2_get_acl(inode, ACL_TYPE_ACCESS);
336  if (IS_ERR(acl) || !acl)
337  return PTR_ERR(acl);
338  rc = posix_acl_chmod(&acl, GFP_KERNEL, inode->i_mode);
339  if (rc)
340  return rc;
341  rc = jffs2_set_acl(inode, ACL_TYPE_ACCESS, acl);
342  posix_acl_release(acl);
343  return rc;
344 }
345 
346 static size_t jffs2_acl_access_listxattr(struct dentry *dentry, char *list,
347  size_t list_size, const char *name, size_t name_len, int type)
348 {
349  const int retlen = sizeof(POSIX_ACL_XATTR_ACCESS);
350 
351  if (list && retlen <= list_size)
352  strcpy(list, POSIX_ACL_XATTR_ACCESS);
353  return retlen;
354 }
355 
356 static size_t jffs2_acl_default_listxattr(struct dentry *dentry, char *list,
357  size_t list_size, const char *name, size_t name_len, int type)
358 {
359  const int retlen = sizeof(POSIX_ACL_XATTR_DEFAULT);
360 
361  if (list && retlen <= list_size)
362  strcpy(list, POSIX_ACL_XATTR_DEFAULT);
363  return retlen;
364 }
365 
366 static int jffs2_acl_getxattr(struct dentry *dentry, const char *name,
367  void *buffer, size_t size, int type)
368 {
369  struct posix_acl *acl;
370  int rc;
371 
372  if (name[0] != '\0')
373  return -EINVAL;
374 
375  acl = jffs2_get_acl(dentry->d_inode, type);
376  if (IS_ERR(acl))
377  return PTR_ERR(acl);
378  if (!acl)
379  return -ENODATA;
380  rc = posix_acl_to_xattr(&init_user_ns, acl, buffer, size);
381  posix_acl_release(acl);
382 
383  return rc;
384 }
385 
386 static int jffs2_acl_setxattr(struct dentry *dentry, const char *name,
387  const void *value, size_t size, int flags, int type)
388 {
389  struct posix_acl *acl;
390  int rc;
391 
392  if (name[0] != '\0')
393  return -EINVAL;
394  if (!inode_owner_or_capable(dentry->d_inode))
395  return -EPERM;
396 
397  if (value) {
398  acl = posix_acl_from_xattr(&init_user_ns, value, size);
399  if (IS_ERR(acl))
400  return PTR_ERR(acl);
401  if (acl) {
402  rc = posix_acl_valid(acl);
403  if (rc)
404  goto out;
405  }
406  } else {
407  acl = NULL;
408  }
409  rc = jffs2_set_acl(dentry->d_inode, type, acl);
410  out:
411  posix_acl_release(acl);
412  return rc;
413 }
414 
415 const struct xattr_handler jffs2_acl_access_xattr_handler = {
416  .prefix = POSIX_ACL_XATTR_ACCESS,
417  .flags = ACL_TYPE_DEFAULT,
418  .list = jffs2_acl_access_listxattr,
419  .get = jffs2_acl_getxattr,
420  .set = jffs2_acl_setxattr,
421 };
422 
423 const struct xattr_handler jffs2_acl_default_xattr_handler = {
424  .prefix = POSIX_ACL_XATTR_DEFAULT,
425  .flags = ACL_TYPE_DEFAULT,
426  .list = jffs2_acl_default_listxattr,
427  .get = jffs2_acl_getxattr,
428  .set = jffs2_acl_setxattr,
429 };
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