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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
26 #include <linux/file.h>
27 #include <linux/poll.h>
28 #include <linux/slab.h>
29 #include <linux/mount.h>
30 #include <linux/pagemap.h>
31 #include <linux/security.h>
32 #include <linux/compat.h>
33 #include <linux/fs_stack.h>
34 #include "ecryptfs_kernel.h"
35
36 /**
37 * ecryptfs_read_update_atime
38 *
39 * generic_file_read updates the atime of upper layer inode. But, it
40 * doesn't give us a chance to update the atime of the lower layer
41 * inode. This function is a wrapper to generic_file_read. It
42 * updates the atime of the lower level inode if generic_file_read
43 * returns without any errors. This is to be used only for file reads.
44 * The function to be used for directory reads is ecryptfs_read.
45 */
46 static ssize_t ecryptfs_read_update_atime(struct kiocb *iocb,
47 struct iov_iter *to)
48 {
49 ssize_t rc;
50 struct path *path;
51 struct file *file = iocb->ki_filp;
52
53 rc = generic_file_read_iter(iocb, to);
54 if (rc >= 0) {
55 path = ecryptfs_dentry_to_lower_path(file->f_path.dentry);
56 touch_atime(path);
57 }
58 return rc;
59 }
60
61 struct ecryptfs_getdents_callback {
62 struct dir_context ctx;
63 struct dir_context *caller;
64 struct super_block *sb;
65 int filldir_called;
66 int entries_written;
67 };
68
69 /* Inspired by generic filldir in fs/readdir.c */
70 static int
71 ecryptfs_filldir(struct dir_context *ctx, const char *lower_name,
72 int lower_namelen, loff_t offset, u64 ino, unsigned int d_type)
73 {
74 struct ecryptfs_getdents_callback *buf =
75 container_of(ctx, struct ecryptfs_getdents_callback, ctx);
76 size_t name_size;
77 char *name;
78 int rc;
79
80 buf->filldir_called++;
81 rc = ecryptfs_decode_and_decrypt_filename(&name, &name_size,
82 buf->sb, lower_name,
83 lower_namelen);
84 if (rc) {
85 printk(KERN_ERR "%s: Error attempting to decode and decrypt "
86 "filename [%s]; rc = [%d]\n", __func__, lower_name,
87 rc);
88 goto out;
89 }
90 buf->caller->pos = buf->ctx.pos;
91 rc = !dir_emit(buf->caller, name, name_size, ino, d_type);
92 kfree(name);
93 if (!rc)
94 buf->entries_written++;
95 out:
96 return rc;
97 }
98
99 /**
100 * ecryptfs_readdir
101 * @file: The eCryptfs directory file
102 * @ctx: The actor to feed the entries to
103 */
104 static int ecryptfs_readdir(struct file *file, struct dir_context *ctx)
105 {
106 int rc;
107 struct file *lower_file;
108 struct inode *inode = file_inode(file);
109 struct ecryptfs_getdents_callback buf = {
110 .ctx.actor = ecryptfs_filldir,
111 .caller = ctx,
112 .sb = inode->i_sb,
113 };
114 lower_file = ecryptfs_file_to_lower(file);
115 rc = iterate_dir(lower_file, &buf.ctx);
116 ctx->pos = buf.ctx.pos;
117 if (rc < 0)
118 goto out;
119 if (buf.filldir_called && !buf.entries_written)
120 goto out;
121 if (rc >= 0)
122 fsstack_copy_attr_atime(inode,
123 file_inode(lower_file));
124 out:
125 return rc;
126 }
127
128 struct kmem_cache *ecryptfs_file_info_cache;
129
130 static int read_or_initialize_metadata(struct dentry *dentry)
131 {
132 struct inode *inode = d_inode(dentry);
133 struct ecryptfs_mount_crypt_stat *mount_crypt_stat;
134 struct ecryptfs_crypt_stat *crypt_stat;
135 int rc;
136
137 crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat;
138 mount_crypt_stat = &ecryptfs_superblock_to_private(
139 inode->i_sb)->mount_crypt_stat;
140 mutex_lock(&crypt_stat->cs_mutex);
141
142 if (crypt_stat->flags & ECRYPTFS_POLICY_APPLIED &&
143 crypt_stat->flags & ECRYPTFS_KEY_VALID) {
144 rc = 0;
145 goto out;
146 }
147
148 rc = ecryptfs_read_metadata(dentry);
149 if (!rc)
150 goto out;
151
152 if (mount_crypt_stat->flags & ECRYPTFS_PLAINTEXT_PASSTHROUGH_ENABLED) {
153 crypt_stat->flags &= ~(ECRYPTFS_I_SIZE_INITIALIZED
154 | ECRYPTFS_ENCRYPTED);
155 rc = 0;
156 goto out;
157 }
158
159 if (!(mount_crypt_stat->flags & ECRYPTFS_XATTR_METADATA_ENABLED) &&
160 !i_size_read(ecryptfs_inode_to_lower(inode))) {
161 rc = ecryptfs_initialize_file(dentry, inode);
162 if (!rc)
163 goto out;
164 }
165
166 rc = -EIO;
167 out:
168 mutex_unlock(&crypt_stat->cs_mutex);
169 return rc;
170 }
171
172 static int ecryptfs_mmap(struct file *file, struct vm_area_struct *vma)
173 {
174 struct file *lower_file = ecryptfs_file_to_lower(file);
175 /*
176 * Don't allow mmap on top of file systems that don't support it
177 * natively. If FILESYSTEM_MAX_STACK_DEPTH > 2 or ecryptfs
178 * allows recursive mounting, this will need to be extended.
179 */
180 if (!lower_file->f_op->mmap)
181 return -ENODEV;
182 return generic_file_mmap(file, vma);
183 }
184
185 /**
186 * ecryptfs_open
187 * @inode: inode specifying file to open
188 * @file: Structure to return filled in
189 *
190 * Opens the file specified by inode.
191 *
192 * Returns zero on success; non-zero otherwise
193 */
194 static int ecryptfs_open(struct inode *inode, struct file *file)
195 {
196 int rc = 0;
197 struct ecryptfs_crypt_stat *crypt_stat = NULL;
198 struct dentry *ecryptfs_dentry = file->f_path.dentry;
199 /* Private value of ecryptfs_dentry allocated in
200 * ecryptfs_lookup() */
201 struct ecryptfs_file_info *file_info;
202
203 /* Released in ecryptfs_release or end of function if failure */
204 file_info = kmem_cache_zalloc(ecryptfs_file_info_cache, GFP_KERNEL);
205 ecryptfs_set_file_private(file, file_info);
206 if (!file_info) {
207 ecryptfs_printk(KERN_ERR,
208 "Error attempting to allocate memory\n");
209 rc = -ENOMEM;
210 goto out;
211 }
212 crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat;
213 mutex_lock(&crypt_stat->cs_mutex);
214 if (!(crypt_stat->flags & ECRYPTFS_POLICY_APPLIED)) {
215 ecryptfs_printk(KERN_DEBUG, "Setting flags for stat...\n");
216 /* Policy code enabled in future release */
217 crypt_stat->flags |= (ECRYPTFS_POLICY_APPLIED
218 | ECRYPTFS_ENCRYPTED);
219 }
220 mutex_unlock(&crypt_stat->cs_mutex);
221 rc = ecryptfs_get_lower_file(ecryptfs_dentry, inode);
222 if (rc) {
223 printk(KERN_ERR "%s: Error attempting to initialize "
224 "the lower file for the dentry with name "
225 "[%pd]; rc = [%d]\n", __func__,
226 ecryptfs_dentry, rc);
227 goto out_free;
228 }
229 if ((ecryptfs_inode_to_private(inode)->lower_file->f_flags & O_ACCMODE)
230 == O_RDONLY && (file->f_flags & O_ACCMODE) != O_RDONLY) {
231 rc = -EPERM;
232 printk(KERN_WARNING "%s: Lower file is RO; eCryptfs "
233 "file must hence be opened RO\n", __func__);
234 goto out_put;
235 }
236 ecryptfs_set_file_lower(
237 file, ecryptfs_inode_to_private(inode)->lower_file);
238 rc = read_or_initialize_metadata(ecryptfs_dentry);
239 if (rc)
240 goto out_put;
241 ecryptfs_printk(KERN_DEBUG, "inode w/ addr = [0x%p], i_ino = "
242 "[0x%.16lx] size: [0x%.16llx]\n", inode, inode->i_ino,
243 (unsigned long long)i_size_read(inode));
244 goto out;
245 out_put:
246 ecryptfs_put_lower_file(inode);
247 out_free:
248 kmem_cache_free(ecryptfs_file_info_cache,
249 ecryptfs_file_to_private(file));
250 out:
251 return rc;
252 }
253
254 /**
255 * ecryptfs_dir_open
256 * @inode: inode specifying file to open
257 * @file: Structure to return filled in
258 *
259 * Opens the file specified by inode.
260 *
261 * Returns zero on success; non-zero otherwise
262 */
263 static int ecryptfs_dir_open(struct inode *inode, struct file *file)
264 {
265 struct dentry *ecryptfs_dentry = file->f_path.dentry;
266 /* Private value of ecryptfs_dentry allocated in
267 * ecryptfs_lookup() */
268 struct ecryptfs_file_info *file_info;
269 struct file *lower_file;
270
271 /* Released in ecryptfs_release or end of function if failure */
272 file_info = kmem_cache_zalloc(ecryptfs_file_info_cache, GFP_KERNEL);
273 ecryptfs_set_file_private(file, file_info);
274 if (unlikely(!file_info)) {
275 ecryptfs_printk(KERN_ERR,
276 "Error attempting to allocate memory\n");
277 return -ENOMEM;
278 }
279 lower_file = dentry_open(ecryptfs_dentry_to_lower_path(ecryptfs_dentry),
280 file->f_flags, current_cred());
281 if (IS_ERR(lower_file)) {
282 printk(KERN_ERR "%s: Error attempting to initialize "
283 "the lower file for the dentry with name "
284 "[%pd]; rc = [%ld]\n", __func__,
285 ecryptfs_dentry, PTR_ERR(lower_file));
286 kmem_cache_free(ecryptfs_file_info_cache, file_info);
287 return PTR_ERR(lower_file);
288 }
289 ecryptfs_set_file_lower(file, lower_file);
290 return 0;
291 }
292
293 static int ecryptfs_flush(struct file *file, fl_owner_t td)
294 {
295 struct file *lower_file = ecryptfs_file_to_lower(file);
296
297 if (lower_file->f_op->flush) {
298 filemap_write_and_wait(file->f_mapping);
299 return lower_file->f_op->flush(lower_file, td);
300 }
301
302 return 0;
303 }
304
305 static int ecryptfs_release(struct inode *inode, struct file *file)
306 {
307 ecryptfs_put_lower_file(inode);
308 kmem_cache_free(ecryptfs_file_info_cache,
309 ecryptfs_file_to_private(file));
310 return 0;
311 }
312
313 static int ecryptfs_dir_release(struct inode *inode, struct file *file)
314 {
315 fput(ecryptfs_file_to_lower(file));
316 kmem_cache_free(ecryptfs_file_info_cache,
317 ecryptfs_file_to_private(file));
318 return 0;
319 }
320
321 static loff_t ecryptfs_dir_llseek(struct file *file, loff_t offset, int whence)
322 {
323 return vfs_llseek(ecryptfs_file_to_lower(file), offset, whence);
324 }
325
326 static int
327 ecryptfs_fsync(struct file *file, loff_t start, loff_t end, int datasync)
328 {
329 int rc;
330
331 rc = file_write_and_wait(file);
332 if (rc)
333 return rc;
334
335 return vfs_fsync(ecryptfs_file_to_lower(file), datasync);
336 }
337
338 static int ecryptfs_fasync(int fd, struct file *file, int flag)
339 {
340 int rc = 0;
341 struct file *lower_file = NULL;
342
343 lower_file = ecryptfs_file_to_lower(file);
344 if (lower_file->f_op->fasync)
345 rc = lower_file->f_op->fasync(fd, lower_file, flag);
346 return rc;
347 }
348
349 static long
350 ecryptfs_unlocked_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
351 {
352 struct file *lower_file = ecryptfs_file_to_lower(file);
353 long rc = -ENOTTY;
354
355 if (!lower_file->f_op->unlocked_ioctl)
356 return rc;
357
358 switch (cmd) {
359 case FITRIM:
360 case FS_IOC_GETFLAGS:
361 case FS_IOC_SETFLAGS:
362 case FS_IOC_GETVERSION:
363 case FS_IOC_SETVERSION:
364 rc = lower_file->f_op->unlocked_ioctl(lower_file, cmd, arg);
365 fsstack_copy_attr_all(file_inode(file), file_inode(lower_file));
366
367 return rc;
368 default:
369 return rc;
370 }
371 }
372
373 #ifdef CONFIG_COMPAT
374 static long
375 ecryptfs_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
376 {
377 struct file *lower_file = ecryptfs_file_to_lower(file);
378 long rc = -ENOIOCTLCMD;
379
380 if (!lower_file->f_op->compat_ioctl)
381 return rc;
382
383 switch (cmd) {
384 case FS_IOC32_GETFLAGS:
385 case FS_IOC32_SETFLAGS:
386 case FS_IOC32_GETVERSION:
387 case FS_IOC32_SETVERSION:
388 rc = lower_file->f_op->compat_ioctl(lower_file, cmd, arg);
389 fsstack_copy_attr_all(file_inode(file), file_inode(lower_file));
390
391 return rc;
392 default:
393 return rc;
394 }
395 }
396 #endif
397
398 const struct file_operations ecryptfs_dir_fops = {
399 .iterate_shared = ecryptfs_readdir,
400 .read = generic_read_dir,
401 .unlocked_ioctl = ecryptfs_unlocked_ioctl,
402 #ifdef CONFIG_COMPAT
403 .compat_ioctl = ecryptfs_compat_ioctl,
404 #endif
405 .open = ecryptfs_dir_open,
406 .release = ecryptfs_dir_release,
407 .fsync = ecryptfs_fsync,
408 .llseek = ecryptfs_dir_llseek,
409 };
410
411 const struct file_operations ecryptfs_main_fops = {
412 .llseek = generic_file_llseek,
413 .read_iter = ecryptfs_read_update_atime,
414 .write_iter = generic_file_write_iter,
415 .unlocked_ioctl = ecryptfs_unlocked_ioctl,
416 #ifdef CONFIG_COMPAT
417 .compat_ioctl = ecryptfs_compat_ioctl,
418 #endif
419 .mmap = ecryptfs_mmap,
420 .open = ecryptfs_open,
421 .flush = ecryptfs_flush,
422 .release = ecryptfs_release,
423 .fsync = ecryptfs_fsync,
424 .fasync = ecryptfs_fasync,
425 .splice_read = generic_file_splice_read,
426 };