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 */
46static 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
61struct 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 */
70static int
71ecryptfs_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++;
95out:
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 */
104static 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	lower_file->f_pos = ctx->pos;
116	rc = iterate_dir(lower_file, &buf.ctx);
117	ctx->pos = buf.ctx.pos;
118	if (rc < 0)
119		goto out;
120	if (buf.filldir_called && !buf.entries_written)
121		goto out;
122	if (rc >= 0)
123		fsstack_copy_attr_atime(inode,
124					file_inode(lower_file));
125out:
126	return rc;
127}
128
129struct kmem_cache *ecryptfs_file_info_cache;
130
131static int read_or_initialize_metadata(struct dentry *dentry)
132{
133	struct inode *inode = d_inode(dentry);
134	struct ecryptfs_mount_crypt_stat *mount_crypt_stat;
135	struct ecryptfs_crypt_stat *crypt_stat;
136	int rc;
137
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
143	if (crypt_stat->flags & ECRYPTFS_POLICY_APPLIED &&
144	    crypt_stat->flags & ECRYPTFS_KEY_VALID) {
145		rc = 0;
146		goto out;
147	}
148
149	rc = ecryptfs_read_metadata(dentry);
150	if (!rc)
151		goto out;
152
153	if (mount_crypt_stat->flags & ECRYPTFS_PLAINTEXT_PASSTHROUGH_ENABLED) {
154		crypt_stat->flags &= ~(ECRYPTFS_I_SIZE_INITIALIZED
155				       | ECRYPTFS_ENCRYPTED);
156		rc = 0;
157		goto out;
158	}
159
160	if (!(mount_crypt_stat->flags & ECRYPTFS_XATTR_METADATA_ENABLED) &&
161	    !i_size_read(ecryptfs_inode_to_lower(inode))) {
162		rc = ecryptfs_initialize_file(dentry, inode);
163		if (!rc)
164			goto out;
165	}
166
167	rc = -EIO;
168out:
169	mutex_unlock(&crypt_stat->cs_mutex);
170	return rc;
171}
172
173/**
174 * ecryptfs_open
175 * @inode: inode speciying file to open
176 * @file: Structure to return filled in
177 *
178 * Opens the file specified by inode.
179 *
180 * Returns zero on success; non-zero otherwise
181 */
182static int ecryptfs_open(struct inode *inode, struct file *file)
183{
184	int rc = 0;
185	struct ecryptfs_crypt_stat *crypt_stat = NULL;
186	struct dentry *ecryptfs_dentry = file->f_path.dentry;
187	/* Private value of ecryptfs_dentry allocated in
188	 * ecryptfs_lookup() */
189	struct ecryptfs_file_info *file_info;
190
191	/* Released in ecryptfs_release or end of function if failure */
192	file_info = kmem_cache_zalloc(ecryptfs_file_info_cache, GFP_KERNEL);
193	ecryptfs_set_file_private(file, file_info);
194	if (!file_info) {
195		ecryptfs_printk(KERN_ERR,
196				"Error attempting to allocate memory\n");
197		rc = -ENOMEM;
198		goto out;
199	}
200	crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat;
201	mutex_lock(&crypt_stat->cs_mutex);
202	if (!(crypt_stat->flags & ECRYPTFS_POLICY_APPLIED)) {
203		ecryptfs_printk(KERN_DEBUG, "Setting flags for stat...\n");
204		/* Policy code enabled in future release */
205		crypt_stat->flags |= (ECRYPTFS_POLICY_APPLIED
206				      | ECRYPTFS_ENCRYPTED);
207	}
208	mutex_unlock(&crypt_stat->cs_mutex);
209	rc = ecryptfs_get_lower_file(ecryptfs_dentry, inode);
210	if (rc) {
211		printk(KERN_ERR "%s: Error attempting to initialize "
212			"the lower file for the dentry with name "
213			"[%pd]; rc = [%d]\n", __func__,
214			ecryptfs_dentry, rc);
215		goto out_free;
216	}
217	if ((ecryptfs_inode_to_private(inode)->lower_file->f_flags & O_ACCMODE)
218	    == O_RDONLY && (file->f_flags & O_ACCMODE) != O_RDONLY) {
219		rc = -EPERM;
220		printk(KERN_WARNING "%s: Lower file is RO; eCryptfs "
221		       "file must hence be opened RO\n", __func__);
222		goto out_put;
223	}
224	ecryptfs_set_file_lower(
225		file, ecryptfs_inode_to_private(inode)->lower_file);
226	if (d_is_dir(ecryptfs_dentry)) {
227		ecryptfs_printk(KERN_DEBUG, "This is a directory\n");
228		mutex_lock(&crypt_stat->cs_mutex);
229		crypt_stat->flags &= ~(ECRYPTFS_ENCRYPTED);
230		mutex_unlock(&crypt_stat->cs_mutex);
231		rc = 0;
232		goto out;
233	}
234	rc = read_or_initialize_metadata(ecryptfs_dentry);
235	if (rc)
236		goto out_put;
237	ecryptfs_printk(KERN_DEBUG, "inode w/ addr = [0x%p], i_ino = "
238			"[0x%.16lx] size: [0x%.16llx]\n", inode, inode->i_ino,
239			(unsigned long long)i_size_read(inode));
240	goto out;
241out_put:
242	ecryptfs_put_lower_file(inode);
243out_free:
244	kmem_cache_free(ecryptfs_file_info_cache,
245			ecryptfs_file_to_private(file));
246out:
247	return rc;
248}
249
250static int ecryptfs_flush(struct file *file, fl_owner_t td)
251{
252	struct file *lower_file = ecryptfs_file_to_lower(file);
253
254	if (lower_file->f_op->flush) {
255		filemap_write_and_wait(file->f_mapping);
256		return lower_file->f_op->flush(lower_file, td);
257	}
258
259	return 0;
260}
261
262static int ecryptfs_release(struct inode *inode, struct file *file)
263{
264	ecryptfs_put_lower_file(inode);
265	kmem_cache_free(ecryptfs_file_info_cache,
266			ecryptfs_file_to_private(file));
267	return 0;
268}
269
270static int
271ecryptfs_fsync(struct file *file, loff_t start, loff_t end, int datasync)
272{
273	int rc;
274
275	rc = filemap_write_and_wait(file->f_mapping);
276	if (rc)
277		return rc;
278
279	return vfs_fsync(ecryptfs_file_to_lower(file), datasync);
280}
281
282static int ecryptfs_fasync(int fd, struct file *file, int flag)
283{
284	int rc = 0;
285	struct file *lower_file = NULL;
286
287	lower_file = ecryptfs_file_to_lower(file);
288	if (lower_file->f_op->fasync)
289		rc = lower_file->f_op->fasync(fd, lower_file, flag);
290	return rc;
291}
292
293static long
294ecryptfs_unlocked_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
295{
296	struct file *lower_file = ecryptfs_file_to_lower(file);
297	long rc = -ENOTTY;
298
299	if (!lower_file->f_op->unlocked_ioctl)
300		return rc;
301
302	switch (cmd) {
303	case FITRIM:
304	case FS_IOC_GETFLAGS:
305	case FS_IOC_SETFLAGS:
306	case FS_IOC_GETVERSION:
307	case FS_IOC_SETVERSION:
308		rc = lower_file->f_op->unlocked_ioctl(lower_file, cmd, arg);
309		fsstack_copy_attr_all(file_inode(file), file_inode(lower_file));
310
311		return rc;
312	default:
313		return rc;
314	}
315}
316
317#ifdef CONFIG_COMPAT
318static long
319ecryptfs_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
320{
321	struct file *lower_file = ecryptfs_file_to_lower(file);
322	long rc = -ENOIOCTLCMD;
323
324	if (!lower_file->f_op->compat_ioctl)
325		return rc;
326
327	switch (cmd) {
328	case FITRIM:
329	case FS_IOC32_GETFLAGS:
330	case FS_IOC32_SETFLAGS:
331	case FS_IOC32_GETVERSION:
332	case FS_IOC32_SETVERSION:
333		rc = lower_file->f_op->compat_ioctl(lower_file, cmd, arg);
334		fsstack_copy_attr_all(file_inode(file), file_inode(lower_file));
335
336		return rc;
337	default:
338		return rc;
339	}
340}
341#endif
342
343const struct file_operations ecryptfs_dir_fops = {
344	.iterate = ecryptfs_readdir,
345	.read = generic_read_dir,
346	.unlocked_ioctl = ecryptfs_unlocked_ioctl,
347#ifdef CONFIG_COMPAT
348	.compat_ioctl = ecryptfs_compat_ioctl,
349#endif
350	.open = ecryptfs_open,
351	.flush = ecryptfs_flush,
352	.release = ecryptfs_release,
353	.fsync = ecryptfs_fsync,
354	.fasync = ecryptfs_fasync,
355	.splice_read = generic_file_splice_read,
356	.llseek = default_llseek,
357};
358
359const struct file_operations ecryptfs_main_fops = {
360	.llseek = generic_file_llseek,
361	.read_iter = ecryptfs_read_update_atime,
362	.write_iter = generic_file_write_iter,
363	.iterate = 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