file.c 11 KB

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  1. /**
  2. * eCryptfs: Linux filesystem encryption layer
  3. *
  4. * Copyright (C) 1997-2004 Erez Zadok
  5. * Copyright (C) 2001-2004 Stony Brook University
  6. * Copyright (C) 2004-2007 International Business Machines Corp.
  7. * Author(s): Michael A. Halcrow <mhalcrow@us.ibm.com>
  8. * Michael C. Thompson <mcthomps@us.ibm.com>
  9. *
  10. * This program is free software; you can redistribute it and/or
  11. * modify it under the terms of the GNU General Public License as
  12. * published by the Free Software Foundation; either version 2 of the
  13. * License, or (at your option) any later version.
  14. *
  15. * This program is distributed in the hope that it will be useful, but
  16. * WITHOUT ANY WARRANTY; without even the implied warranty of
  17. * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  18. * General Public License for more details.
  19. *
  20. * You should have received a copy of the GNU General Public License
  21. * along with this program; if not, write to the Free Software
  22. * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
  23. * 02111-1307, USA.
  24. */
  25. #include <linux/file.h>
  26. #include <linux/poll.h>
  27. #include <linux/slab.h>
  28. #include <linux/mount.h>
  29. #include <linux/pagemap.h>
  30. #include <linux/security.h>
  31. #include <linux/compat.h>
  32. #include <linux/fs_stack.h>
  33. #include <linux/aio.h>
  34. #include "ecryptfs_kernel.h"
  35. /**
  36. * ecryptfs_read_update_atime
  37. *
  38. * generic_file_read updates the atime of upper layer inode. But, it
  39. * doesn't give us a chance to update the atime of the lower layer
  40. * inode. This function is a wrapper to generic_file_read. It
  41. * updates the atime of the lower level inode if generic_file_read
  42. * returns without any errors. This is to be used only for file reads.
  43. * The function to be used for directory reads is ecryptfs_read.
  44. */
  45. static ssize_t ecryptfs_read_update_atime(struct kiocb *iocb,
  46. const struct iovec *iov,
  47. unsigned long nr_segs, loff_t pos)
  48. {
  49. ssize_t rc;
  50. struct path lower;
  51. struct file *file = iocb->ki_filp;
  52. rc = generic_file_aio_read(iocb, iov, nr_segs, pos);
  53. /*
  54. * Even though this is a async interface, we need to wait
  55. * for IO to finish to update atime
  56. */
  57. if (-EIOCBQUEUED == rc)
  58. rc = wait_on_sync_kiocb(iocb);
  59. if (rc >= 0) {
  60. lower.dentry = ecryptfs_dentry_to_lower(file->f_path.dentry);
  61. lower.mnt = ecryptfs_dentry_to_lower_mnt(file->f_path.dentry);
  62. touch_atime(&lower);
  63. }
  64. return rc;
  65. }
  66. struct ecryptfs_getdents_callback {
  67. struct dir_context ctx;
  68. struct dir_context *caller;
  69. struct dentry *dentry;
  70. int filldir_called;
  71. int entries_written;
  72. };
  73. /* Inspired by generic filldir in fs/readdir.c */
  74. static int
  75. ecryptfs_filldir(void *dirent, const char *lower_name, int lower_namelen,
  76. loff_t offset, u64 ino, unsigned int d_type)
  77. {
  78. struct ecryptfs_getdents_callback *buf =
  79. (struct ecryptfs_getdents_callback *)dirent;
  80. size_t name_size;
  81. char *name;
  82. int rc;
  83. buf->filldir_called++;
  84. rc = ecryptfs_decode_and_decrypt_filename(&name, &name_size,
  85. buf->dentry, lower_name,
  86. lower_namelen);
  87. if (rc) {
  88. printk(KERN_ERR "%s: Error attempting to decode and decrypt "
  89. "filename [%s]; rc = [%d]\n", __func__, lower_name,
  90. rc);
  91. goto out;
  92. }
  93. buf->caller->pos = buf->ctx.pos;
  94. rc = !dir_emit(buf->caller, name, name_size, ino, d_type);
  95. kfree(name);
  96. if (!rc)
  97. buf->entries_written++;
  98. out:
  99. return rc;
  100. }
  101. /**
  102. * ecryptfs_readdir
  103. * @file: The eCryptfs directory file
  104. * @ctx: The actor to feed the entries to
  105. */
  106. static int ecryptfs_readdir(struct file *file, struct dir_context *ctx)
  107. {
  108. int rc;
  109. struct file *lower_file;
  110. struct inode *inode;
  111. struct ecryptfs_getdents_callback buf = {
  112. .ctx.actor = ecryptfs_filldir,
  113. .caller = ctx,
  114. .dentry = file->f_path.dentry
  115. };
  116. lower_file = ecryptfs_file_to_lower(file);
  117. lower_file->f_pos = ctx->pos;
  118. inode = file_inode(file);
  119. rc = iterate_dir(lower_file, &buf.ctx);
  120. ctx->pos = buf.ctx.pos;
  121. if (rc < 0)
  122. goto out;
  123. if (buf.filldir_called && !buf.entries_written)
  124. goto out;
  125. if (rc >= 0)
  126. fsstack_copy_attr_atime(inode,
  127. file_inode(lower_file));
  128. out:
  129. return rc;
  130. }
  131. struct kmem_cache *ecryptfs_file_info_cache;
  132. static int read_or_initialize_metadata(struct dentry *dentry)
  133. {
  134. struct inode *inode = dentry->d_inode;
  135. struct ecryptfs_mount_crypt_stat *mount_crypt_stat;
  136. struct ecryptfs_crypt_stat *crypt_stat;
  137. int rc;
  138. crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat;
  139. mount_crypt_stat = &ecryptfs_superblock_to_private(
  140. inode->i_sb)->mount_crypt_stat;
  141. mutex_lock(&crypt_stat->cs_mutex);
  142. if (crypt_stat->flags & ECRYPTFS_POLICY_APPLIED &&
  143. crypt_stat->flags & ECRYPTFS_KEY_VALID) {
  144. rc = 0;
  145. goto out;
  146. }
  147. rc = ecryptfs_read_metadata(dentry);
  148. if (!rc)
  149. goto out;
  150. if (mount_crypt_stat->flags & ECRYPTFS_PLAINTEXT_PASSTHROUGH_ENABLED) {
  151. crypt_stat->flags &= ~(ECRYPTFS_I_SIZE_INITIALIZED
  152. | ECRYPTFS_ENCRYPTED);
  153. rc = 0;
  154. goto out;
  155. }
  156. if (!(mount_crypt_stat->flags & ECRYPTFS_XATTR_METADATA_ENABLED) &&
  157. !i_size_read(ecryptfs_inode_to_lower(inode))) {
  158. rc = ecryptfs_initialize_file(dentry, inode);
  159. if (!rc)
  160. goto out;
  161. }
  162. rc = -EIO;
  163. out:
  164. mutex_unlock(&crypt_stat->cs_mutex);
  165. return rc;
  166. }
  167. /**
  168. * ecryptfs_open
  169. * @inode: inode speciying file to open
  170. * @file: Structure to return filled in
  171. *
  172. * Opens the file specified by inode.
  173. *
  174. * Returns zero on success; non-zero otherwise
  175. */
  176. static int ecryptfs_open(struct inode *inode, struct file *file)
  177. {
  178. int rc = 0;
  179. struct ecryptfs_crypt_stat *crypt_stat = NULL;
  180. struct ecryptfs_mount_crypt_stat *mount_crypt_stat;
  181. struct dentry *ecryptfs_dentry = file->f_path.dentry;
  182. /* Private value of ecryptfs_dentry allocated in
  183. * ecryptfs_lookup() */
  184. struct ecryptfs_file_info *file_info;
  185. mount_crypt_stat = &ecryptfs_superblock_to_private(
  186. ecryptfs_dentry->d_sb)->mount_crypt_stat;
  187. if ((mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED)
  188. && ((file->f_flags & O_WRONLY) || (file->f_flags & O_RDWR)
  189. || (file->f_flags & O_CREAT) || (file->f_flags & O_TRUNC)
  190. || (file->f_flags & O_APPEND))) {
  191. printk(KERN_WARNING "Mount has encrypted view enabled; "
  192. "files may only be read\n");
  193. rc = -EPERM;
  194. goto out;
  195. }
  196. /* Released in ecryptfs_release or end of function if failure */
  197. file_info = kmem_cache_zalloc(ecryptfs_file_info_cache, GFP_KERNEL);
  198. ecryptfs_set_file_private(file, file_info);
  199. if (!file_info) {
  200. ecryptfs_printk(KERN_ERR,
  201. "Error attempting to allocate memory\n");
  202. rc = -ENOMEM;
  203. goto out;
  204. }
  205. crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat;
  206. mutex_lock(&crypt_stat->cs_mutex);
  207. if (!(crypt_stat->flags & ECRYPTFS_POLICY_APPLIED)) {
  208. ecryptfs_printk(KERN_DEBUG, "Setting flags for stat...\n");
  209. /* Policy code enabled in future release */
  210. crypt_stat->flags |= (ECRYPTFS_POLICY_APPLIED
  211. | ECRYPTFS_ENCRYPTED);
  212. }
  213. mutex_unlock(&crypt_stat->cs_mutex);
  214. rc = ecryptfs_get_lower_file(ecryptfs_dentry, inode);
  215. if (rc) {
  216. printk(KERN_ERR "%s: Error attempting to initialize "
  217. "the lower file for the dentry with name "
  218. "[%s]; rc = [%d]\n", __func__,
  219. ecryptfs_dentry->d_name.name, rc);
  220. goto out_free;
  221. }
  222. if ((ecryptfs_inode_to_private(inode)->lower_file->f_flags & O_ACCMODE)
  223. == O_RDONLY && (file->f_flags & O_ACCMODE) != O_RDONLY) {
  224. rc = -EPERM;
  225. printk(KERN_WARNING "%s: Lower file is RO; eCryptfs "
  226. "file must hence be opened RO\n", __func__);
  227. goto out_put;
  228. }
  229. ecryptfs_set_file_lower(
  230. file, ecryptfs_inode_to_private(inode)->lower_file);
  231. if (S_ISDIR(ecryptfs_dentry->d_inode->i_mode)) {
  232. ecryptfs_printk(KERN_DEBUG, "This is a directory\n");
  233. mutex_lock(&crypt_stat->cs_mutex);
  234. crypt_stat->flags &= ~(ECRYPTFS_ENCRYPTED);
  235. mutex_unlock(&crypt_stat->cs_mutex);
  236. rc = 0;
  237. goto out;
  238. }
  239. rc = read_or_initialize_metadata(ecryptfs_dentry);
  240. if (rc)
  241. goto out_put;
  242. ecryptfs_printk(KERN_DEBUG, "inode w/ addr = [0x%p], i_ino = "
  243. "[0x%.16lx] size: [0x%.16llx]\n", inode, inode->i_ino,
  244. (unsigned long long)i_size_read(inode));
  245. goto out;
  246. out_put:
  247. ecryptfs_put_lower_file(inode);
  248. out_free:
  249. kmem_cache_free(ecryptfs_file_info_cache,
  250. ecryptfs_file_to_private(file));
  251. out:
  252. return rc;
  253. }
  254. static int ecryptfs_flush(struct file *file, fl_owner_t td)
  255. {
  256. struct file *lower_file = ecryptfs_file_to_lower(file);
  257. if (lower_file->f_op && lower_file->f_op->flush) {
  258. filemap_write_and_wait(file->f_mapping);
  259. return lower_file->f_op->flush(lower_file, td);
  260. }
  261. return 0;
  262. }
  263. static int ecryptfs_release(struct inode *inode, struct file *file)
  264. {
  265. ecryptfs_put_lower_file(inode);
  266. kmem_cache_free(ecryptfs_file_info_cache,
  267. ecryptfs_file_to_private(file));
  268. return 0;
  269. }
  270. static int
  271. ecryptfs_fsync(struct file *file, loff_t start, loff_t end, int datasync)
  272. {
  273. int rc;
  274. rc = filemap_write_and_wait(file->f_mapping);
  275. if (rc)
  276. return rc;
  277. return vfs_fsync(ecryptfs_file_to_lower(file), datasync);
  278. }
  279. static int ecryptfs_fasync(int fd, struct file *file, int flag)
  280. {
  281. int rc = 0;
  282. struct file *lower_file = NULL;
  283. lower_file = ecryptfs_file_to_lower(file);
  284. if (lower_file->f_op && lower_file->f_op->fasync)
  285. rc = lower_file->f_op->fasync(fd, lower_file, flag);
  286. return rc;
  287. }
  288. static long
  289. ecryptfs_unlocked_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
  290. {
  291. struct file *lower_file = NULL;
  292. long rc = -ENOTTY;
  293. if (ecryptfs_file_to_private(file))
  294. lower_file = ecryptfs_file_to_lower(file);
  295. if (lower_file && lower_file->f_op && lower_file->f_op->unlocked_ioctl)
  296. rc = lower_file->f_op->unlocked_ioctl(lower_file, cmd, arg);
  297. return rc;
  298. }
  299. #ifdef CONFIG_COMPAT
  300. static long
  301. ecryptfs_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
  302. {
  303. struct file *lower_file = NULL;
  304. long rc = -ENOIOCTLCMD;
  305. if (ecryptfs_file_to_private(file))
  306. lower_file = ecryptfs_file_to_lower(file);
  307. if (lower_file && lower_file->f_op && lower_file->f_op->compat_ioctl)
  308. rc = lower_file->f_op->compat_ioctl(lower_file, cmd, arg);
  309. return rc;
  310. }
  311. #endif
  312. const struct file_operations ecryptfs_dir_fops = {
  313. .iterate = ecryptfs_readdir,
  314. .read = generic_read_dir,
  315. .unlocked_ioctl = ecryptfs_unlocked_ioctl,
  316. #ifdef CONFIG_COMPAT
  317. .compat_ioctl = ecryptfs_compat_ioctl,
  318. #endif
  319. .open = ecryptfs_open,
  320. .flush = ecryptfs_flush,
  321. .release = ecryptfs_release,
  322. .fsync = ecryptfs_fsync,
  323. .fasync = ecryptfs_fasync,
  324. .splice_read = generic_file_splice_read,
  325. .llseek = default_llseek,
  326. };
  327. const struct file_operations ecryptfs_main_fops = {
  328. .llseek = generic_file_llseek,
  329. .read = do_sync_read,
  330. .aio_read = ecryptfs_read_update_atime,
  331. .write = do_sync_write,
  332. .aio_write = generic_file_aio_write,
  333. .iterate = ecryptfs_readdir,
  334. .unlocked_ioctl = ecryptfs_unlocked_ioctl,
  335. #ifdef CONFIG_COMPAT
  336. .compat_ioctl = ecryptfs_compat_ioctl,
  337. #endif
  338. .mmap = generic_file_mmap,
  339. .open = ecryptfs_open,
  340. .flush = ecryptfs_flush,
  341. .release = ecryptfs_release,
  342. .fsync = ecryptfs_fsync,
  343. .fasync = ecryptfs_fasync,
  344. .splice_read = generic_file_splice_read,
  345. };