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 */
ecryptfs_read_update_atime(struct kiocb * iocb,const struct iovec * iov,unsigned long nr_segs,loff_t pos)46 static ssize_t ecryptfs_read_update_atime(struct kiocb *iocb,
47 const struct iovec *iov,
48 unsigned long nr_segs, loff_t pos)
49 {
50 ssize_t rc;
51 struct path lower;
52 struct file *file = iocb->ki_filp;
53
54 rc = generic_file_aio_read(iocb, iov, nr_segs, pos);
55 /*
56 * Even though this is a async interface, we need to wait
57 * for IO to finish to update atime
58 */
59 if (-EIOCBQUEUED == rc)
60 rc = wait_on_sync_kiocb(iocb);
61 if (rc >= 0) {
62 lower.dentry = ecryptfs_dentry_to_lower(file->f_path.dentry);
63 lower.mnt = ecryptfs_dentry_to_lower_mnt(file->f_path.dentry);
64 touch_atime(&lower);
65 }
66 return rc;
67 }
68
69 struct ecryptfs_getdents_callback {
70 void *dirent;
71 struct dentry *dentry;
72 filldir_t filldir;
73 int filldir_called;
74 int entries_written;
75 };
76
77 /* Inspired by generic filldir in fs/readdir.c */
78 static int
ecryptfs_filldir(void * dirent,const char * lower_name,int lower_namelen,loff_t offset,u64 ino,unsigned int d_type)79 ecryptfs_filldir(void *dirent, const char *lower_name, int lower_namelen,
80 loff_t offset, u64 ino, unsigned int d_type)
81 {
82 struct ecryptfs_getdents_callback *buf =
83 (struct ecryptfs_getdents_callback *)dirent;
84 size_t name_size;
85 char *name;
86 int rc;
87
88 buf->filldir_called++;
89 rc = ecryptfs_decode_and_decrypt_filename(&name, &name_size,
90 buf->dentry, lower_name,
91 lower_namelen);
92 if (rc) {
93 printk(KERN_ERR "%s: Error attempting to decode and decrypt "
94 "filename [%s]; rc = [%d]\n", __func__, lower_name,
95 rc);
96 goto out;
97 }
98 rc = buf->filldir(buf->dirent, name, name_size, offset, ino, d_type);
99 kfree(name);
100 if (rc >= 0)
101 buf->entries_written++;
102 out:
103 return rc;
104 }
105
106 /**
107 * ecryptfs_readdir
108 * @file: The eCryptfs directory file
109 * @dirent: Directory entry handle
110 * @filldir: The filldir callback function
111 */
ecryptfs_readdir(struct file * file,void * dirent,filldir_t filldir)112 static int ecryptfs_readdir(struct file *file, void *dirent, filldir_t filldir)
113 {
114 int rc;
115 struct file *lower_file;
116 struct inode *inode;
117 struct ecryptfs_getdents_callback buf;
118
119 lower_file = ecryptfs_file_to_lower(file);
120 lower_file->f_pos = file->f_pos;
121 inode = file->f_path.dentry->d_inode;
122 memset(&buf, 0, sizeof(buf));
123 buf.dirent = dirent;
124 buf.dentry = file->f_path.dentry;
125 buf.filldir = filldir;
126 buf.filldir_called = 0;
127 buf.entries_written = 0;
128 rc = vfs_readdir(lower_file, ecryptfs_filldir, (void *)&buf);
129 file->f_pos = lower_file->f_pos;
130 if (rc < 0)
131 goto out;
132 if (buf.filldir_called && !buf.entries_written)
133 goto out;
134 if (rc >= 0)
135 fsstack_copy_attr_atime(inode,
136 lower_file->f_path.dentry->d_inode);
137 out:
138 return rc;
139 }
140
141 struct kmem_cache *ecryptfs_file_info_cache;
142
read_or_initialize_metadata(struct dentry * dentry)143 static int read_or_initialize_metadata(struct dentry *dentry)
144 {
145 struct inode *inode = dentry->d_inode;
146 struct ecryptfs_mount_crypt_stat *mount_crypt_stat;
147 struct ecryptfs_crypt_stat *crypt_stat;
148 int rc;
149
150 crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat;
151 mount_crypt_stat = &ecryptfs_superblock_to_private(
152 inode->i_sb)->mount_crypt_stat;
153 mutex_lock(&crypt_stat->cs_mutex);
154
155 if (crypt_stat->flags & ECRYPTFS_POLICY_APPLIED &&
156 crypt_stat->flags & ECRYPTFS_KEY_VALID) {
157 rc = 0;
158 goto out;
159 }
160
161 rc = ecryptfs_read_metadata(dentry);
162 if (!rc)
163 goto out;
164
165 if (mount_crypt_stat->flags & ECRYPTFS_PLAINTEXT_PASSTHROUGH_ENABLED) {
166 crypt_stat->flags &= ~(ECRYPTFS_I_SIZE_INITIALIZED
167 | ECRYPTFS_ENCRYPTED);
168 rc = 0;
169 goto out;
170 }
171
172 if (!(mount_crypt_stat->flags & ECRYPTFS_XATTR_METADATA_ENABLED) &&
173 !i_size_read(ecryptfs_inode_to_lower(inode))) {
174 rc = ecryptfs_initialize_file(dentry, inode);
175 if (!rc)
176 goto out;
177 }
178
179 rc = -EIO;
180 out:
181 mutex_unlock(&crypt_stat->cs_mutex);
182 return rc;
183 }
184
185 /**
186 * ecryptfs_open
187 * @inode: inode speciying 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 */
ecryptfs_open(struct inode * inode,struct file * file)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 ecryptfs_mount_crypt_stat *mount_crypt_stat;
199 struct dentry *ecryptfs_dentry = file->f_path.dentry;
200 /* Private value of ecryptfs_dentry allocated in
201 * ecryptfs_lookup() */
202 struct dentry *lower_dentry;
203 struct ecryptfs_file_info *file_info;
204
205 mount_crypt_stat = &ecryptfs_superblock_to_private(
206 ecryptfs_dentry->d_sb)->mount_crypt_stat;
207 if ((mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED)
208 && ((file->f_flags & O_WRONLY) || (file->f_flags & O_RDWR)
209 || (file->f_flags & O_CREAT) || (file->f_flags & O_TRUNC)
210 || (file->f_flags & O_APPEND))) {
211 printk(KERN_WARNING "Mount has encrypted view enabled; "
212 "files may only be read\n");
213 rc = -EPERM;
214 goto out;
215 }
216 /* Released in ecryptfs_release or end of function if failure */
217 file_info = kmem_cache_zalloc(ecryptfs_file_info_cache, GFP_KERNEL);
218 ecryptfs_set_file_private(file, file_info);
219 if (!file_info) {
220 ecryptfs_printk(KERN_ERR,
221 "Error attempting to allocate memory\n");
222 rc = -ENOMEM;
223 goto out;
224 }
225 lower_dentry = ecryptfs_dentry_to_lower(ecryptfs_dentry);
226 crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat;
227 mutex_lock(&crypt_stat->cs_mutex);
228 if (!(crypt_stat->flags & ECRYPTFS_POLICY_APPLIED)) {
229 ecryptfs_printk(KERN_DEBUG, "Setting flags for stat...\n");
230 /* Policy code enabled in future release */
231 crypt_stat->flags |= (ECRYPTFS_POLICY_APPLIED
232 | ECRYPTFS_ENCRYPTED);
233 }
234 mutex_unlock(&crypt_stat->cs_mutex);
235 rc = ecryptfs_get_lower_file(ecryptfs_dentry, inode);
236 if (rc) {
237 printk(KERN_ERR "%s: Error attempting to initialize "
238 "the lower file for the dentry with name "
239 "[%s]; rc = [%d]\n", __func__,
240 ecryptfs_dentry->d_name.name, rc);
241 goto out_free;
242 }
243 if ((ecryptfs_inode_to_private(inode)->lower_file->f_flags & O_ACCMODE)
244 == O_RDONLY && (file->f_flags & O_ACCMODE) != O_RDONLY) {
245 rc = -EPERM;
246 printk(KERN_WARNING "%s: Lower file is RO; eCryptfs "
247 "file must hence be opened RO\n", __func__);
248 goto out_put;
249 }
250 ecryptfs_set_file_lower(
251 file, ecryptfs_inode_to_private(inode)->lower_file);
252 if (S_ISDIR(ecryptfs_dentry->d_inode->i_mode)) {
253 ecryptfs_printk(KERN_DEBUG, "This is a directory\n");
254 mutex_lock(&crypt_stat->cs_mutex);
255 crypt_stat->flags &= ~(ECRYPTFS_ENCRYPTED);
256 mutex_unlock(&crypt_stat->cs_mutex);
257 rc = 0;
258 goto out;
259 }
260 rc = read_or_initialize_metadata(ecryptfs_dentry);
261 if (rc)
262 goto out_put;
263 ecryptfs_printk(KERN_DEBUG, "inode w/ addr = [0x%p], i_ino = "
264 "[0x%.16lx] size: [0x%.16llx]\n", inode, inode->i_ino,
265 (unsigned long long)i_size_read(inode));
266 goto out;
267 out_put:
268 ecryptfs_put_lower_file(inode);
269 out_free:
270 kmem_cache_free(ecryptfs_file_info_cache,
271 ecryptfs_file_to_private(file));
272 out:
273 return rc;
274 }
275
ecryptfs_flush(struct file * file,fl_owner_t td)276 static int ecryptfs_flush(struct file *file, fl_owner_t td)
277 {
278 struct file *lower_file = ecryptfs_file_to_lower(file);
279
280 if (lower_file->f_op && lower_file->f_op->flush) {
281 filemap_write_and_wait(file->f_mapping);
282 return lower_file->f_op->flush(lower_file, td);
283 }
284
285 return 0;
286 }
287
ecryptfs_release(struct inode * inode,struct file * file)288 static int ecryptfs_release(struct inode *inode, struct file *file)
289 {
290 ecryptfs_put_lower_file(inode);
291 kmem_cache_free(ecryptfs_file_info_cache,
292 ecryptfs_file_to_private(file));
293 return 0;
294 }
295
296 static int
ecryptfs_fsync(struct file * file,loff_t start,loff_t end,int datasync)297 ecryptfs_fsync(struct file *file, loff_t start, loff_t end, int datasync)
298 {
299 return vfs_fsync(ecryptfs_file_to_lower(file), datasync);
300 }
301
ecryptfs_fasync(int fd,struct file * file,int flag)302 static int ecryptfs_fasync(int fd, struct file *file, int flag)
303 {
304 int rc = 0;
305 struct file *lower_file = NULL;
306
307 lower_file = ecryptfs_file_to_lower(file);
308 if (lower_file->f_op && lower_file->f_op->fasync)
309 rc = lower_file->f_op->fasync(fd, lower_file, flag);
310 return rc;
311 }
312
313 static long
ecryptfs_unlocked_ioctl(struct file * file,unsigned int cmd,unsigned long arg)314 ecryptfs_unlocked_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
315 {
316 struct file *lower_file = NULL;
317 long rc = -ENOTTY;
318
319 if (ecryptfs_file_to_private(file))
320 lower_file = ecryptfs_file_to_lower(file);
321 if (lower_file && lower_file->f_op && lower_file->f_op->unlocked_ioctl)
322 rc = lower_file->f_op->unlocked_ioctl(lower_file, cmd, arg);
323 return rc;
324 }
325
326 #ifdef CONFIG_COMPAT
327 static long
ecryptfs_compat_ioctl(struct file * file,unsigned int cmd,unsigned long arg)328 ecryptfs_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
329 {
330 struct file *lower_file = NULL;
331 long rc = -ENOIOCTLCMD;
332
333 if (ecryptfs_file_to_private(file))
334 lower_file = ecryptfs_file_to_lower(file);
335 if (lower_file && lower_file->f_op && lower_file->f_op->compat_ioctl)
336 rc = lower_file->f_op->compat_ioctl(lower_file, cmd, arg);
337 return rc;
338 }
339 #endif
340
341 const struct file_operations ecryptfs_dir_fops = {
342 .readdir = ecryptfs_readdir,
343 .read = generic_read_dir,
344 .unlocked_ioctl = ecryptfs_unlocked_ioctl,
345 #ifdef CONFIG_COMPAT
346 .compat_ioctl = ecryptfs_compat_ioctl,
347 #endif
348 .open = ecryptfs_open,
349 .flush = ecryptfs_flush,
350 .release = ecryptfs_release,
351 .fsync = ecryptfs_fsync,
352 .fasync = ecryptfs_fasync,
353 .splice_read = generic_file_splice_read,
354 .llseek = default_llseek,
355 };
356
357 const struct file_operations ecryptfs_main_fops = {
358 .llseek = generic_file_llseek,
359 .read = do_sync_read,
360 .aio_read = ecryptfs_read_update_atime,
361 .write = do_sync_write,
362 .aio_write = generic_file_aio_write,
363 .readdir = ecryptfs_readdir,
364 .unlocked_ioctl = ecryptfs_unlocked_ioctl,
365 #ifdef CONFIG_COMPAT
366 .compat_ioctl = ecryptfs_compat_ioctl,
367 #endif
368 .mmap = generic_file_mmap,
369 .open = ecryptfs_open,
370 .flush = ecryptfs_flush,
371 .release = ecryptfs_release,
372 .fsync = ecryptfs_fsync,
373 .fasync = ecryptfs_fasync,
374 .splice_read = generic_file_splice_read,
375 };
376