acl.c 9.8 KB

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  1. /*
  2. * linux/fs/ext4/acl.c
  3. *
  4. * Copyright (C) 2001-2003 Andreas Gruenbacher, <agruen@suse.de>
  5. */
  6. #include <linux/init.h>
  7. #include <linux/sched.h>
  8. #include <linux/slab.h>
  9. #include <linux/capability.h>
  10. #include <linux/fs.h>
  11. #include "ext4_jbd2.h"
  12. #include "ext4.h"
  13. #include "xattr.h"
  14. #include "acl.h"
  15. /*
  16. * Convert from filesystem to in-memory representation.
  17. */
  18. static struct posix_acl *
  19. ext4_acl_from_disk(const void *value, size_t size)
  20. {
  21. const char *end = (char *)value + size;
  22. int n, count;
  23. struct posix_acl *acl;
  24. if (!value)
  25. return NULL;
  26. if (size < sizeof(ext4_acl_header))
  27. return ERR_PTR(-EINVAL);
  28. if (((ext4_acl_header *)value)->a_version !=
  29. cpu_to_le32(EXT4_ACL_VERSION))
  30. return ERR_PTR(-EINVAL);
  31. value = (char *)value + sizeof(ext4_acl_header);
  32. count = ext4_acl_count(size);
  33. if (count < 0)
  34. return ERR_PTR(-EINVAL);
  35. if (count == 0)
  36. return NULL;
  37. acl = posix_acl_alloc(count, GFP_NOFS);
  38. if (!acl)
  39. return ERR_PTR(-ENOMEM);
  40. for (n = 0; n < count; n++) {
  41. ext4_acl_entry *entry =
  42. (ext4_acl_entry *)value;
  43. if ((char *)value + sizeof(ext4_acl_entry_short) > end)
  44. goto fail;
  45. acl->a_entries[n].e_tag = le16_to_cpu(entry->e_tag);
  46. acl->a_entries[n].e_perm = le16_to_cpu(entry->e_perm);
  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. acl->a_entries[n].e_id = ACL_UNDEFINED_ID;
  55. break;
  56. case ACL_USER:
  57. case ACL_GROUP:
  58. value = (char *)value + sizeof(ext4_acl_entry);
  59. if ((char *)value > end)
  60. goto fail;
  61. acl->a_entries[n].e_id =
  62. le32_to_cpu(entry->e_id);
  63. break;
  64. default:
  65. goto fail;
  66. }
  67. }
  68. if (value != end)
  69. goto fail;
  70. return acl;
  71. fail:
  72. posix_acl_release(acl);
  73. return ERR_PTR(-EINVAL);
  74. }
  75. /*
  76. * Convert from in-memory to filesystem representation.
  77. */
  78. static void *
  79. ext4_acl_to_disk(const struct posix_acl *acl, size_t *size)
  80. {
  81. ext4_acl_header *ext_acl;
  82. char *e;
  83. size_t n;
  84. *size = ext4_acl_size(acl->a_count);
  85. ext_acl = kmalloc(sizeof(ext4_acl_header) + acl->a_count *
  86. sizeof(ext4_acl_entry), GFP_NOFS);
  87. if (!ext_acl)
  88. return ERR_PTR(-ENOMEM);
  89. ext_acl->a_version = cpu_to_le32(EXT4_ACL_VERSION);
  90. e = (char *)ext_acl + sizeof(ext4_acl_header);
  91. for (n = 0; n < acl->a_count; n++) {
  92. ext4_acl_entry *entry = (ext4_acl_entry *)e;
  93. entry->e_tag = cpu_to_le16(acl->a_entries[n].e_tag);
  94. entry->e_perm = cpu_to_le16(acl->a_entries[n].e_perm);
  95. switch (acl->a_entries[n].e_tag) {
  96. case ACL_USER:
  97. case ACL_GROUP:
  98. entry->e_id = cpu_to_le32(acl->a_entries[n].e_id);
  99. e += sizeof(ext4_acl_entry);
  100. break;
  101. case ACL_USER_OBJ:
  102. case ACL_GROUP_OBJ:
  103. case ACL_MASK:
  104. case ACL_OTHER:
  105. e += sizeof(ext4_acl_entry_short);
  106. break;
  107. default:
  108. goto fail;
  109. }
  110. }
  111. return (char *)ext_acl;
  112. fail:
  113. kfree(ext_acl);
  114. return ERR_PTR(-EINVAL);
  115. }
  116. /*
  117. * Inode operation get_posix_acl().
  118. *
  119. * inode->i_mutex: don't care
  120. */
  121. struct posix_acl *
  122. ext4_get_acl(struct inode *inode, int type)
  123. {
  124. int name_index;
  125. char *value = NULL;
  126. struct posix_acl *acl;
  127. int retval;
  128. if (!test_opt(inode->i_sb, POSIX_ACL))
  129. return NULL;
  130. acl = get_cached_acl(inode, type);
  131. if (acl != ACL_NOT_CACHED)
  132. return acl;
  133. switch (type) {
  134. case ACL_TYPE_ACCESS:
  135. name_index = EXT4_XATTR_INDEX_POSIX_ACL_ACCESS;
  136. break;
  137. case ACL_TYPE_DEFAULT:
  138. name_index = EXT4_XATTR_INDEX_POSIX_ACL_DEFAULT;
  139. break;
  140. default:
  141. BUG();
  142. }
  143. retval = ext4_xattr_get(inode, name_index, "", NULL, 0);
  144. if (retval > 0) {
  145. value = kmalloc(retval, GFP_NOFS);
  146. if (!value)
  147. return ERR_PTR(-ENOMEM);
  148. retval = ext4_xattr_get(inode, name_index, "", value, retval);
  149. }
  150. if (retval > 0)
  151. acl = ext4_acl_from_disk(value, retval);
  152. else if (retval == -ENODATA || retval == -ENOSYS)
  153. acl = NULL;
  154. else
  155. acl = ERR_PTR(retval);
  156. kfree(value);
  157. if (!IS_ERR(acl))
  158. set_cached_acl(inode, type, acl);
  159. return acl;
  160. }
  161. /*
  162. * Set the access or default ACL of an inode.
  163. *
  164. * inode->i_mutex: down unless called from ext4_new_inode
  165. */
  166. static int
  167. ext4_set_acl(handle_t *handle, struct inode *inode, int type,
  168. struct posix_acl *acl)
  169. {
  170. int name_index;
  171. void *value = NULL;
  172. size_t size = 0;
  173. int error;
  174. if (S_ISLNK(inode->i_mode))
  175. return -EOPNOTSUPP;
  176. switch (type) {
  177. case ACL_TYPE_ACCESS:
  178. name_index = EXT4_XATTR_INDEX_POSIX_ACL_ACCESS;
  179. if (acl) {
  180. error = posix_acl_update_mode(inode, &inode->i_mode, &acl);
  181. if (error)
  182. return error;
  183. inode->i_ctime = ext4_current_time(inode);
  184. ext4_mark_inode_dirty(handle, inode);
  185. }
  186. break;
  187. case ACL_TYPE_DEFAULT:
  188. name_index = EXT4_XATTR_INDEX_POSIX_ACL_DEFAULT;
  189. if (!S_ISDIR(inode->i_mode))
  190. return acl ? -EACCES : 0;
  191. break;
  192. default:
  193. return -EINVAL;
  194. }
  195. if (acl) {
  196. value = ext4_acl_to_disk(acl, &size);
  197. if (IS_ERR(value))
  198. return (int)PTR_ERR(value);
  199. }
  200. error = ext4_xattr_set_handle(handle, inode, name_index, "",
  201. value, size, 0);
  202. kfree(value);
  203. if (!error)
  204. set_cached_acl(inode, type, acl);
  205. return error;
  206. }
  207. /*
  208. * Initialize the ACLs of a new inode. Called from ext4_new_inode.
  209. *
  210. * dir->i_mutex: down
  211. * inode->i_mutex: up (access to inode is still exclusive)
  212. */
  213. int
  214. ext4_init_acl(handle_t *handle, struct inode *inode, struct inode *dir)
  215. {
  216. struct posix_acl *acl = NULL;
  217. int error = 0;
  218. if (!S_ISLNK(inode->i_mode)) {
  219. if (test_opt(dir->i_sb, POSIX_ACL)) {
  220. acl = ext4_get_acl(dir, ACL_TYPE_DEFAULT);
  221. if (IS_ERR(acl))
  222. return PTR_ERR(acl);
  223. }
  224. if (!acl)
  225. inode->i_mode &= ~current_umask();
  226. }
  227. if (test_opt(inode->i_sb, POSIX_ACL) && acl) {
  228. if (S_ISDIR(inode->i_mode)) {
  229. error = ext4_set_acl(handle, inode,
  230. ACL_TYPE_DEFAULT, acl);
  231. if (error)
  232. goto cleanup;
  233. }
  234. error = __posix_acl_create(&acl, GFP_NOFS, &inode->i_mode);
  235. if (error < 0)
  236. return error;
  237. if (error > 0) {
  238. /* This is an extended ACL */
  239. error = ext4_set_acl(handle, inode, ACL_TYPE_ACCESS, acl);
  240. }
  241. }
  242. cleanup:
  243. posix_acl_release(acl);
  244. return error;
  245. }
  246. /*
  247. * Does chmod for an inode that may have an Access Control List. The
  248. * inode->i_mode field must be updated to the desired value by the caller
  249. * before calling this function.
  250. * Returns 0 on success, or a negative error number.
  251. *
  252. * We change the ACL rather than storing some ACL entries in the file
  253. * mode permission bits (which would be more efficient), because that
  254. * would break once additional permissions (like ACL_APPEND, ACL_DELETE
  255. * for directories) are added. There are no more bits available in the
  256. * file mode.
  257. *
  258. * inode->i_mutex: down
  259. */
  260. int
  261. ext4_acl_chmod(struct inode *inode)
  262. {
  263. struct posix_acl *acl;
  264. handle_t *handle;
  265. int retries = 0;
  266. int error;
  267. if (S_ISLNK(inode->i_mode))
  268. return -EOPNOTSUPP;
  269. if (!test_opt(inode->i_sb, POSIX_ACL))
  270. return 0;
  271. acl = ext4_get_acl(inode, ACL_TYPE_ACCESS);
  272. if (IS_ERR(acl) || !acl)
  273. return PTR_ERR(acl);
  274. error = __posix_acl_chmod(&acl, GFP_KERNEL, inode->i_mode);
  275. if (error)
  276. return error;
  277. retry:
  278. handle = ext4_journal_start(inode,
  279. EXT4_DATA_TRANS_BLOCKS(inode->i_sb));
  280. if (IS_ERR(handle)) {
  281. error = PTR_ERR(handle);
  282. ext4_std_error(inode->i_sb, error);
  283. goto out;
  284. }
  285. error = ext4_set_acl(handle, inode, ACL_TYPE_ACCESS, acl);
  286. ext4_journal_stop(handle);
  287. if (error == -ENOSPC &&
  288. ext4_should_retry_alloc(inode->i_sb, &retries))
  289. goto retry;
  290. out:
  291. posix_acl_release(acl);
  292. return error;
  293. }
  294. /*
  295. * Extended attribute handlers
  296. */
  297. static size_t
  298. ext4_xattr_list_acl_access(struct dentry *dentry, char *list, size_t list_len,
  299. const char *name, size_t name_len, int type)
  300. {
  301. const size_t size = sizeof(POSIX_ACL_XATTR_ACCESS);
  302. if (!test_opt(dentry->d_sb, POSIX_ACL))
  303. return 0;
  304. if (list && size <= list_len)
  305. memcpy(list, POSIX_ACL_XATTR_ACCESS, size);
  306. return size;
  307. }
  308. static size_t
  309. ext4_xattr_list_acl_default(struct dentry *dentry, char *list, size_t list_len,
  310. const char *name, size_t name_len, int type)
  311. {
  312. const size_t size = sizeof(POSIX_ACL_XATTR_DEFAULT);
  313. if (!test_opt(dentry->d_sb, POSIX_ACL))
  314. return 0;
  315. if (list && size <= list_len)
  316. memcpy(list, POSIX_ACL_XATTR_DEFAULT, size);
  317. return size;
  318. }
  319. static int
  320. ext4_xattr_get_acl(struct dentry *dentry, const char *name, void *buffer,
  321. size_t size, int type)
  322. {
  323. struct posix_acl *acl;
  324. int error;
  325. if (strcmp(name, "") != 0)
  326. return -EINVAL;
  327. if (!test_opt(dentry->d_sb, POSIX_ACL))
  328. return -EOPNOTSUPP;
  329. acl = ext4_get_acl(dentry->d_inode, type);
  330. if (IS_ERR(acl))
  331. return PTR_ERR(acl);
  332. if (acl == NULL)
  333. return -ENODATA;
  334. error = posix_acl_to_xattr(&init_user_ns, acl, buffer, size);
  335. posix_acl_release(acl);
  336. return error;
  337. }
  338. static int
  339. ext4_xattr_set_acl(struct dentry *dentry, const char *name, const void *value,
  340. size_t size, int flags, int type)
  341. {
  342. struct inode *inode = dentry->d_inode;
  343. handle_t *handle;
  344. struct posix_acl *acl;
  345. int error, retries = 0;
  346. if (strcmp(name, "") != 0)
  347. return -EINVAL;
  348. if (!test_opt(inode->i_sb, POSIX_ACL))
  349. return -EOPNOTSUPP;
  350. if (!inode_owner_or_capable(inode))
  351. return -EPERM;
  352. if (value) {
  353. acl = posix_acl_from_xattr(&init_user_ns, value, size);
  354. if (IS_ERR(acl))
  355. return PTR_ERR(acl);
  356. else if (acl) {
  357. error = posix_acl_valid(acl);
  358. if (error)
  359. goto release_and_out;
  360. }
  361. } else
  362. acl = NULL;
  363. retry:
  364. handle = ext4_journal_start(inode, EXT4_DATA_TRANS_BLOCKS(inode->i_sb));
  365. if (IS_ERR(handle)) {
  366. error = PTR_ERR(handle);
  367. goto release_and_out;
  368. }
  369. error = ext4_set_acl(handle, inode, type, acl);
  370. ext4_journal_stop(handle);
  371. if (error == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries))
  372. goto retry;
  373. release_and_out:
  374. posix_acl_release(acl);
  375. return error;
  376. }
  377. const struct xattr_handler ext4_xattr_acl_access_handler = {
  378. .prefix = POSIX_ACL_XATTR_ACCESS,
  379. .flags = ACL_TYPE_ACCESS,
  380. .list = ext4_xattr_list_acl_access,
  381. .get = ext4_xattr_get_acl,
  382. .set = ext4_xattr_set_acl,
  383. };
  384. const struct xattr_handler ext4_xattr_acl_default_handler = {
  385. .prefix = POSIX_ACL_XATTR_DEFAULT,
  386. .flags = ACL_TYPE_DEFAULT,
  387. .list = ext4_xattr_list_acl_default,
  388. .get = ext4_xattr_get_acl,
  389. .set = ext4_xattr_set_acl,
  390. };