inode.c 10 KB

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  1. // SPDX-License-Identifier: GPL-2.0-only
  2. /*
  3. * fs/kernfs/inode.c - kernfs inode implementation
  4. *
  5. * Copyright (c) 2001-3 Patrick Mochel
  6. * Copyright (c) 2007 SUSE Linux Products GmbH
  7. * Copyright (c) 2007, 2013 Tejun Heo <tj@kernel.org>
  8. */
  9. #include <linux/pagemap.h>
  10. #include <linux/backing-dev.h>
  11. #include <linux/capability.h>
  12. #include <linux/errno.h>
  13. #include <linux/slab.h>
  14. #include <linux/xattr.h>
  15. #include <linux/security.h>
  16. #include "kernfs-internal.h"
  17. static const struct address_space_operations kernfs_aops = {
  18. .readpage = simple_readpage,
  19. .write_begin = simple_write_begin,
  20. .write_end = simple_write_end,
  21. };
  22. static const struct inode_operations kernfs_iops = {
  23. .permission = kernfs_iop_permission,
  24. .setattr = kernfs_iop_setattr,
  25. .getattr = kernfs_iop_getattr,
  26. .listxattr = kernfs_iop_listxattr,
  27. };
  28. static struct kernfs_iattrs *__kernfs_iattrs(struct kernfs_node *kn, int alloc)
  29. {
  30. static DEFINE_MUTEX(iattr_mutex);
  31. struct kernfs_iattrs *ret;
  32. mutex_lock(&iattr_mutex);
  33. if (kn->iattr || !alloc)
  34. goto out_unlock;
  35. kn->iattr = kmem_cache_zalloc(kernfs_iattrs_cache, GFP_KERNEL);
  36. if (!kn->iattr)
  37. goto out_unlock;
  38. /* assign default attributes */
  39. kn->iattr->ia_uid = GLOBAL_ROOT_UID;
  40. kn->iattr->ia_gid = GLOBAL_ROOT_GID;
  41. ktime_get_real_ts64(&kn->iattr->ia_atime);
  42. kn->iattr->ia_mtime = kn->iattr->ia_atime;
  43. kn->iattr->ia_ctime = kn->iattr->ia_atime;
  44. simple_xattrs_init(&kn->iattr->xattrs);
  45. atomic_set(&kn->iattr->nr_user_xattrs, 0);
  46. atomic_set(&kn->iattr->user_xattr_size, 0);
  47. out_unlock:
  48. ret = kn->iattr;
  49. mutex_unlock(&iattr_mutex);
  50. return ret;
  51. }
  52. static struct kernfs_iattrs *kernfs_iattrs(struct kernfs_node *kn)
  53. {
  54. return __kernfs_iattrs(kn, 1);
  55. }
  56. static struct kernfs_iattrs *kernfs_iattrs_noalloc(struct kernfs_node *kn)
  57. {
  58. return __kernfs_iattrs(kn, 0);
  59. }
  60. int __kernfs_setattr(struct kernfs_node *kn, const struct iattr *iattr)
  61. {
  62. struct kernfs_iattrs *attrs;
  63. unsigned int ia_valid = iattr->ia_valid;
  64. attrs = kernfs_iattrs(kn);
  65. if (!attrs)
  66. return -ENOMEM;
  67. if (ia_valid & ATTR_UID)
  68. attrs->ia_uid = iattr->ia_uid;
  69. if (ia_valid & ATTR_GID)
  70. attrs->ia_gid = iattr->ia_gid;
  71. if (ia_valid & ATTR_ATIME)
  72. attrs->ia_atime = iattr->ia_atime;
  73. if (ia_valid & ATTR_MTIME)
  74. attrs->ia_mtime = iattr->ia_mtime;
  75. if (ia_valid & ATTR_CTIME)
  76. attrs->ia_ctime = iattr->ia_ctime;
  77. if (ia_valid & ATTR_MODE)
  78. kn->mode = iattr->ia_mode;
  79. return 0;
  80. }
  81. /**
  82. * kernfs_setattr - set iattr on a node
  83. * @kn: target node
  84. * @iattr: iattr to set
  85. *
  86. * Returns 0 on success, -errno on failure.
  87. */
  88. int kernfs_setattr(struct kernfs_node *kn, const struct iattr *iattr)
  89. {
  90. int ret;
  91. mutex_lock(&kernfs_mutex);
  92. ret = __kernfs_setattr(kn, iattr);
  93. mutex_unlock(&kernfs_mutex);
  94. return ret;
  95. }
  96. int kernfs_iop_setattr(struct dentry *dentry, struct iattr *iattr)
  97. {
  98. struct inode *inode = d_inode(dentry);
  99. struct kernfs_node *kn = inode->i_private;
  100. int error;
  101. if (!kn)
  102. return -EINVAL;
  103. mutex_lock(&kernfs_mutex);
  104. error = setattr_prepare(dentry, iattr);
  105. if (error)
  106. goto out;
  107. error = __kernfs_setattr(kn, iattr);
  108. if (error)
  109. goto out;
  110. /* this ignores size changes */
  111. setattr_copy(inode, iattr);
  112. out:
  113. mutex_unlock(&kernfs_mutex);
  114. return error;
  115. }
  116. ssize_t kernfs_iop_listxattr(struct dentry *dentry, char *buf, size_t size)
  117. {
  118. struct kernfs_node *kn = kernfs_dentry_node(dentry);
  119. struct kernfs_iattrs *attrs;
  120. attrs = kernfs_iattrs(kn);
  121. if (!attrs)
  122. return -ENOMEM;
  123. return simple_xattr_list(d_inode(dentry), &attrs->xattrs, buf, size);
  124. }
  125. static inline void set_default_inode_attr(struct inode *inode, umode_t mode)
  126. {
  127. inode->i_mode = mode;
  128. inode->i_atime = inode->i_mtime =
  129. inode->i_ctime = current_time(inode);
  130. }
  131. static inline void set_inode_attr(struct inode *inode,
  132. struct kernfs_iattrs *attrs)
  133. {
  134. inode->i_uid = attrs->ia_uid;
  135. inode->i_gid = attrs->ia_gid;
  136. inode->i_atime = attrs->ia_atime;
  137. inode->i_mtime = attrs->ia_mtime;
  138. inode->i_ctime = attrs->ia_ctime;
  139. }
  140. static void kernfs_refresh_inode(struct kernfs_node *kn, struct inode *inode)
  141. {
  142. struct kernfs_iattrs *attrs = kn->iattr;
  143. inode->i_mode = kn->mode;
  144. if (attrs)
  145. /*
  146. * kernfs_node has non-default attributes get them from
  147. * persistent copy in kernfs_node.
  148. */
  149. set_inode_attr(inode, attrs);
  150. if (kernfs_type(kn) == KERNFS_DIR)
  151. set_nlink(inode, kn->dir.subdirs + 2);
  152. }
  153. int kernfs_iop_getattr(const struct path *path, struct kstat *stat,
  154. u32 request_mask, unsigned int query_flags)
  155. {
  156. struct inode *inode = d_inode(path->dentry);
  157. struct kernfs_node *kn = inode->i_private;
  158. mutex_lock(&kernfs_mutex);
  159. kernfs_refresh_inode(kn, inode);
  160. mutex_unlock(&kernfs_mutex);
  161. generic_fillattr(inode, stat);
  162. return 0;
  163. }
  164. static void kernfs_init_inode(struct kernfs_node *kn, struct inode *inode)
  165. {
  166. kernfs_get(kn);
  167. inode->i_private = kn;
  168. inode->i_mapping->a_ops = &kernfs_aops;
  169. inode->i_op = &kernfs_iops;
  170. inode->i_generation = kernfs_gen(kn);
  171. set_default_inode_attr(inode, kn->mode);
  172. kernfs_refresh_inode(kn, inode);
  173. /* initialize inode according to type */
  174. switch (kernfs_type(kn)) {
  175. case KERNFS_DIR:
  176. inode->i_op = &kernfs_dir_iops;
  177. inode->i_fop = &kernfs_dir_fops;
  178. if (kn->flags & KERNFS_EMPTY_DIR)
  179. make_empty_dir_inode(inode);
  180. break;
  181. case KERNFS_FILE:
  182. inode->i_size = kn->attr.size;
  183. inode->i_fop = &kernfs_file_fops;
  184. break;
  185. case KERNFS_LINK:
  186. inode->i_op = &kernfs_symlink_iops;
  187. break;
  188. default:
  189. BUG();
  190. }
  191. unlock_new_inode(inode);
  192. }
  193. /**
  194. * kernfs_get_inode - get inode for kernfs_node
  195. * @sb: super block
  196. * @kn: kernfs_node to allocate inode for
  197. *
  198. * Get inode for @kn. If such inode doesn't exist, a new inode is
  199. * allocated and basics are initialized. New inode is returned
  200. * locked.
  201. *
  202. * LOCKING:
  203. * Kernel thread context (may sleep).
  204. *
  205. * RETURNS:
  206. * Pointer to allocated inode on success, NULL on failure.
  207. */
  208. struct inode *kernfs_get_inode(struct super_block *sb, struct kernfs_node *kn)
  209. {
  210. struct inode *inode;
  211. inode = iget_locked(sb, kernfs_ino(kn));
  212. if (inode && (inode->i_state & I_NEW))
  213. kernfs_init_inode(kn, inode);
  214. return inode;
  215. }
  216. /*
  217. * The kernfs_node serves as both an inode and a directory entry for
  218. * kernfs. To prevent the kernfs inode numbers from being freed
  219. * prematurely we take a reference to kernfs_node from the kernfs inode. A
  220. * super_operations.evict_inode() implementation is needed to drop that
  221. * reference upon inode destruction.
  222. */
  223. void kernfs_evict_inode(struct inode *inode)
  224. {
  225. struct kernfs_node *kn = inode->i_private;
  226. truncate_inode_pages_final(&inode->i_data);
  227. clear_inode(inode);
  228. kernfs_put(kn);
  229. }
  230. int kernfs_iop_permission(struct inode *inode, int mask)
  231. {
  232. struct kernfs_node *kn;
  233. if (mask & MAY_NOT_BLOCK)
  234. return -ECHILD;
  235. kn = inode->i_private;
  236. mutex_lock(&kernfs_mutex);
  237. kernfs_refresh_inode(kn, inode);
  238. mutex_unlock(&kernfs_mutex);
  239. return generic_permission(inode, mask);
  240. }
  241. int kernfs_xattr_get(struct kernfs_node *kn, const char *name,
  242. void *value, size_t size)
  243. {
  244. struct kernfs_iattrs *attrs = kernfs_iattrs_noalloc(kn);
  245. if (!attrs)
  246. return -ENODATA;
  247. return simple_xattr_get(&attrs->xattrs, name, value, size);
  248. }
  249. int kernfs_xattr_set(struct kernfs_node *kn, const char *name,
  250. const void *value, size_t size, int flags)
  251. {
  252. struct kernfs_iattrs *attrs = kernfs_iattrs(kn);
  253. if (!attrs)
  254. return -ENOMEM;
  255. return simple_xattr_set(&attrs->xattrs, name, value, size, flags, NULL);
  256. }
  257. static int kernfs_vfs_xattr_get(const struct xattr_handler *handler,
  258. struct dentry *unused, struct inode *inode,
  259. const char *suffix, void *value, size_t size,
  260. int flags)
  261. {
  262. const char *name = xattr_full_name(handler, suffix);
  263. struct kernfs_node *kn = inode->i_private;
  264. return kernfs_xattr_get(kn, name, value, size);
  265. }
  266. static int kernfs_vfs_xattr_set(const struct xattr_handler *handler,
  267. struct dentry *unused, struct inode *inode,
  268. const char *suffix, const void *value,
  269. size_t size, int flags)
  270. {
  271. const char *name = xattr_full_name(handler, suffix);
  272. struct kernfs_node *kn = inode->i_private;
  273. return kernfs_xattr_set(kn, name, value, size, flags);
  274. }
  275. static int kernfs_vfs_user_xattr_add(struct kernfs_node *kn,
  276. const char *full_name,
  277. struct simple_xattrs *xattrs,
  278. const void *value, size_t size, int flags)
  279. {
  280. atomic_t *sz = &kn->iattr->user_xattr_size;
  281. atomic_t *nr = &kn->iattr->nr_user_xattrs;
  282. ssize_t removed_size;
  283. int ret;
  284. if (atomic_inc_return(nr) > KERNFS_MAX_USER_XATTRS) {
  285. ret = -ENOSPC;
  286. goto dec_count_out;
  287. }
  288. if (atomic_add_return(size, sz) > KERNFS_USER_XATTR_SIZE_LIMIT) {
  289. ret = -ENOSPC;
  290. goto dec_size_out;
  291. }
  292. ret = simple_xattr_set(xattrs, full_name, value, size, flags,
  293. &removed_size);
  294. if (!ret && removed_size >= 0)
  295. size = removed_size;
  296. else if (!ret)
  297. return 0;
  298. dec_size_out:
  299. atomic_sub(size, sz);
  300. dec_count_out:
  301. atomic_dec(nr);
  302. return ret;
  303. }
  304. static int kernfs_vfs_user_xattr_rm(struct kernfs_node *kn,
  305. const char *full_name,
  306. struct simple_xattrs *xattrs,
  307. const void *value, size_t size, int flags)
  308. {
  309. atomic_t *sz = &kn->iattr->user_xattr_size;
  310. atomic_t *nr = &kn->iattr->nr_user_xattrs;
  311. ssize_t removed_size;
  312. int ret;
  313. ret = simple_xattr_set(xattrs, full_name, value, size, flags,
  314. &removed_size);
  315. if (removed_size >= 0) {
  316. atomic_sub(removed_size, sz);
  317. atomic_dec(nr);
  318. }
  319. return ret;
  320. }
  321. static int kernfs_vfs_user_xattr_set(const struct xattr_handler *handler,
  322. struct dentry *unused, struct inode *inode,
  323. const char *suffix, const void *value,
  324. size_t size, int flags)
  325. {
  326. const char *full_name = xattr_full_name(handler, suffix);
  327. struct kernfs_node *kn = inode->i_private;
  328. struct kernfs_iattrs *attrs;
  329. if (!(kernfs_root(kn)->flags & KERNFS_ROOT_SUPPORT_USER_XATTR))
  330. return -EOPNOTSUPP;
  331. attrs = kernfs_iattrs(kn);
  332. if (!attrs)
  333. return -ENOMEM;
  334. if (value)
  335. return kernfs_vfs_user_xattr_add(kn, full_name, &attrs->xattrs,
  336. value, size, flags);
  337. else
  338. return kernfs_vfs_user_xattr_rm(kn, full_name, &attrs->xattrs,
  339. value, size, flags);
  340. }
  341. static const struct xattr_handler kernfs_trusted_xattr_handler = {
  342. .prefix = XATTR_TRUSTED_PREFIX,
  343. .get = kernfs_vfs_xattr_get,
  344. .set = kernfs_vfs_xattr_set,
  345. };
  346. static const struct xattr_handler kernfs_security_xattr_handler = {
  347. .prefix = XATTR_SECURITY_PREFIX,
  348. .get = kernfs_vfs_xattr_get,
  349. .set = kernfs_vfs_xattr_set,
  350. };
  351. static const struct xattr_handler kernfs_user_xattr_handler = {
  352. .prefix = XATTR_USER_PREFIX,
  353. .get = kernfs_vfs_xattr_get,
  354. .set = kernfs_vfs_user_xattr_set,
  355. };
  356. const struct xattr_handler *kernfs_xattr_handlers[] = {
  357. &kernfs_trusted_xattr_handler,
  358. &kernfs_security_xattr_handler,
  359. &kernfs_user_xattr_handler,
  360. NULL
  361. };