summaryrefslogtreecommitdiff
path: root/fs/ecryptfs/file.c
blob: c74ed3ca3372f8b8e91ed9da35de617c7b25ce08 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
/**
 * eCryptfs: Linux filesystem encryption layer
 *
 * Copyright (C) 1997-2004 Erez Zadok
 * Copyright (C) 2001-2004 Stony Brook University
 * Copyright (C) 2004-2007 International Business Machines Corp.
 *   Author(s): Michael A. Halcrow <mhalcrow@us.ibm.com>
 *   		Michael C. Thompson <mcthomps@us.ibm.com>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation; either version 2 of the
 * License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
 * 02111-1307, USA.
 */

#include <linux/file.h>
#include <linux/poll.h>
#include <linux/slab.h>
#include <linux/mount.h>
#include <linux/pagemap.h>
#include <linux/security.h>
#include <linux/compat.h>
#include <linux/fs_stack.h>
#include "ecryptfs_kernel.h"

/**
 * ecryptfs_read_update_atime
 *
 * generic_file_read updates the atime of upper layer inode.  But, it
 * doesn't give us a chance to update the atime of the lower layer
 * inode.  This function is a wrapper to generic_file_read.  It
 * updates the atime of the lower level inode if generic_file_read
 * returns without any errors. This is to be used only for file reads.
 * The function to be used for directory reads is ecryptfs_read.
 */
static ssize_t ecryptfs_read_update_atime(struct kiocb *iocb,
				struct iov_iter *to)
{
	ssize_t rc;
	struct path *path;
	struct file *file = iocb->ki_filp;

	rc = generic_file_read_iter(iocb, to);
	if (rc >= 0) {
		path = ecryptfs_dentry_to_lower_path(file->f_path.dentry);
		touch_atime(path);
	}
	return rc;
}

struct ecryptfs_getdents_callback {
	struct dir_context ctx;
	struct dir_context *caller;
	struct super_block *sb;
	int filldir_called;
	int entries_written;
};

/* Inspired by generic filldir in fs/readdir.c */
static int
ecryptfs_filldir(struct dir_context *ctx, const char *lower_name,
		 int lower_namelen, loff_t offset, u64 ino, unsigned int d_type)
{
	struct ecryptfs_getdents_callback *buf =
		container_of(ctx, struct ecryptfs_getdents_callback, ctx);
	size_t name_size;
	char *name;
	int rc;

	buf->filldir_called++;
	rc = ecryptfs_decode_and_decrypt_filename(&name, &name_size,
						  buf->sb, lower_name,
						  lower_namelen);
	if (rc) {
		printk(KERN_ERR "%s: Error attempting to decode and decrypt "
		       "filename [%s]; rc = [%d]\n", __func__, lower_name,
		       rc);
		goto out;
	}
	buf->caller->pos = buf->ctx.pos;
	rc = !dir_emit(buf->caller, name, name_size, ino, d_type);
	kfree(name);
	if (!rc)
		buf->entries_written++;
out:
	return rc;
}

/**
 * ecryptfs_readdir
 * @file: The eCryptfs directory file
 * @ctx: The actor to feed the entries to
 */
static int ecryptfs_readdir(struct file *file, struct dir_context *ctx)
{
	int rc;
	struct file *lower_file;
	struct inode *inode = file_inode(file);
	struct ecryptfs_getdents_callback buf = {
		.ctx.actor = ecryptfs_filldir,
		.caller = ctx,
		.sb = inode->i_sb,
	};
	lower_file = ecryptfs_file_to_lower(file);
	rc = iterate_dir(lower_file, &buf.ctx);
	ctx->pos = buf.ctx.pos;
	if (rc < 0)
		goto out;
	if (buf.filldir_called && !buf.entries_written)
		goto out;
	if (rc >= 0)
		fsstack_copy_attr_atime(inode,
					file_inode(lower_file));
out:
	return rc;
}

struct kmem_cache *ecryptfs_file_info_cache;

static int read_or_initialize_metadata(struct dentry *dentry)
{
	struct inode *inode = d_inode(dentry);
	struct ecryptfs_mount_crypt_stat *mount_crypt_stat;
	struct ecryptfs_crypt_stat *crypt_stat;
	int rc;

	crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat;
	mount_crypt_stat = &ecryptfs_superblock_to_private(
						inode->i_sb)->mount_crypt_stat;
	mutex_lock(&crypt_stat->cs_mutex);

	if (crypt_stat->flags & ECRYPTFS_POLICY_APPLIED &&
	    crypt_stat->flags & ECRYPTFS_KEY_VALID) {
		rc = 0;
		goto out;
	}

	rc = ecryptfs_read_metadata(dentry);
	if (!rc)
		goto out;

	if (mount_crypt_stat->flags & ECRYPTFS_PLAINTEXT_PASSTHROUGH_ENABLED) {
		crypt_stat->flags &= ~(ECRYPTFS_I_SIZE_INITIALIZED
				       | ECRYPTFS_ENCRYPTED);
		rc = 0;
		goto out;
	}

	if (!(mount_crypt_stat->flags & ECRYPTFS_XATTR_METADATA_ENABLED) &&
	    !i_size_read(ecryptfs_inode_to_lower(inode))) {
		rc = ecryptfs_initialize_file(dentry, inode);
		if (!rc)
			goto out;
	}

	rc = -EIO;
out:
	mutex_unlock(&crypt_stat->cs_mutex);
	return rc;
}

static int ecryptfs_mmap(struct file *file, struct vm_area_struct *vma)
{
	struct file *lower_file = ecryptfs_file_to_lower(file);
	/*
	 * Don't allow mmap on top of file systems that don't support it
	 * natively.  If FILESYSTEM_MAX_STACK_DEPTH > 2 or ecryptfs
	 * allows recursive mounting, this will need to be extended.
	 */
	if (!lower_file->f_op->mmap)
		return -ENODEV;
	return generic_file_mmap(file, vma);
}

/**
 * ecryptfs_open
 * @inode: inode specifying file to open
 * @file: Structure to return filled in
 *
 * Opens the file specified by inode.
 *
 * Returns zero on success; non-zero otherwise
 */
static int ecryptfs_open(struct inode *inode, struct file *file)
{
	int rc = 0;
	struct ecryptfs_crypt_stat *crypt_stat = NULL;
	struct dentry *ecryptfs_dentry = file->f_path.dentry;
	/* Private value of ecryptfs_dentry allocated in
	 * ecryptfs_lookup() */
	struct ecryptfs_file_info *file_info;

	/* Released in ecryptfs_release or end of function if failure */
	file_info = kmem_cache_zalloc(ecryptfs_file_info_cache, GFP_KERNEL);
	ecryptfs_set_file_private(file, file_info);
	if (!file_info) {
		ecryptfs_printk(KERN_ERR,
				"Error attempting to allocate memory\n");
		rc = -ENOMEM;
		goto out;
	}
	crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat;
	mutex_lock(&crypt_stat->cs_mutex);
	if (!(crypt_stat->flags & ECRYPTFS_POLICY_APPLIED)) {
		ecryptfs_printk(KERN_DEBUG, "Setting flags for stat...\n");
		/* Policy code enabled in future release */
		crypt_stat->flags |= (ECRYPTFS_POLICY_APPLIED
				      | ECRYPTFS_ENCRYPTED);
	}
	mutex_unlock(&crypt_stat->cs_mutex);
	rc = ecryptfs_get_lower_file(ecryptfs_dentry, inode);
	if (rc) {
		printk(KERN_ERR "%s: Error attempting to initialize "
			"the lower file for the dentry with name "
			"[%pd]; rc = [%d]\n", __func__,
			ecryptfs_dentry, rc);
		goto out_free;
	}
	if ((ecryptfs_inode_to_private(inode)->lower_file->f_flags & O_ACCMODE)
	    == O_RDONLY && (file->f_flags & O_ACCMODE) != O_RDONLY) {
		rc = -EPERM;
		printk(KERN_WARNING "%s: Lower file is RO; eCryptfs "
		       "file must hence be opened RO\n", __func__);
		goto out_put;
	}
	ecryptfs_set_file_lower(
		file, ecryptfs_inode_to_private(inode)->lower_file);
	rc = read_or_initialize_metadata(ecryptfs_dentry);
	if (rc)
		goto out_put;
	ecryptfs_printk(KERN_DEBUG, "inode w/ addr = [0x%p], i_ino = "
			"[0x%.16lx] size: [0x%.16llx]\n", inode, inode->i_ino,
			(unsigned long long)i_size_read(inode));
	goto out;
out_put:
	ecryptfs_put_lower_file(inode);
out_free:
	kmem_cache_free(ecryptfs_file_info_cache,
			ecryptfs_file_to_private(file));
out:
	return rc;
}

/**
 * ecryptfs_dir_open
 * @inode: inode specifying file to open
 * @file: Structure to return filled in
 *
 * Opens the file specified by inode.
 *
 * Returns zero on success; non-zero otherwise
 */
static int ecryptfs_dir_open(struct inode *inode, struct file *file)
{
	struct dentry *ecryptfs_dentry = file->f_path.dentry;
	/* Private value of ecryptfs_dentry allocated in
	 * ecryptfs_lookup() */
	struct ecryptfs_file_info *file_info;
	struct file *lower_file;

	/* Released in ecryptfs_release or end of function if failure */
	file_info = kmem_cache_zalloc(ecryptfs_file_info_cache, GFP_KERNEL);
	ecryptfs_set_file_private(file, file_info);
	if (unlikely(!file_info)) {
		ecryptfs_printk(KERN_ERR,
				"Error attempting to allocate memory\n");
		return -ENOMEM;
	}
	lower_file = dentry_open(ecryptfs_dentry_to_lower_path(ecryptfs_dentry),
				 file->f_flags, current_cred());
	if (IS_ERR(lower_file)) {
		printk(KERN_ERR "%s: Error attempting to initialize "
			"the lower file for the dentry with name "
			"[%pd]; rc = [%ld]\n", __func__,
			ecryptfs_dentry, PTR_ERR(lower_file));
		kmem_cache_free(ecryptfs_file_info_cache, file_info);
		return PTR_ERR(lower_file);
	}
	ecryptfs_set_file_lower(file, lower_file);
	return 0;
}

static int ecryptfs_flush(struct file *file, fl_owner_t td)
{
	struct file *lower_file = ecryptfs_file_to_lower(file);

	if (lower_file->f_op->flush) {
		filemap_write_and_wait(file->f_mapping);
		return lower_file->f_op->flush(lower_file, td);
	}

	return 0;
}

static int ecryptfs_release(struct inode *inode, struct file *file)
{
	ecryptfs_put_lower_file(inode);
	kmem_cache_free(ecryptfs_file_info_cache,
			ecryptfs_file_to_private(file));
	return 0;
}

static int ecryptfs_dir_release(struct inode *inode, struct file *file)
{
	fput(ecryptfs_file_to_lower(file));
	kmem_cache_free(ecryptfs_file_info_cache,
			ecryptfs_file_to_private(file));
	return 0;
}

static loff_t ecryptfs_dir_llseek(struct file *file, loff_t offset, int whence)
{
	return vfs_llseek(ecryptfs_file_to_lower(file), offset, whence);
}

static int
ecryptfs_fsync(struct file *file, loff_t start, loff_t end, int datasync)
{
	int rc;

	rc = file_write_and_wait(file);
	if (rc)
		return rc;

	return vfs_fsync(ecryptfs_file_to_lower(file), datasync);
}

static int ecryptfs_fasync(int fd, struct file *file, int flag)
{
	int rc = 0;
	struct file *lower_file = NULL;

	lower_file = ecryptfs_file_to_lower(file);
	if (lower_file->f_op->fasync)
		rc = lower_file->f_op->fasync(fd, lower_file, flag);
	return rc;
}

static long
ecryptfs_unlocked_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
	struct file *lower_file = ecryptfs_file_to_lower(file);
	long rc = -ENOTTY;

	if (!lower_file->f_op->unlocked_ioctl)
		return rc;

	switch (cmd) {
	case FITRIM:
	case FS_IOC_GETFLAGS:
	case FS_IOC_SETFLAGS:
	case FS_IOC_GETVERSION:
	case FS_IOC_SETVERSION:
		rc = lower_file->f_op->unlocked_ioctl(lower_file, cmd, arg);
		fsstack_copy_attr_all(file_inode(file), file_inode(lower_file));

		return rc;
	default:
		return rc;
	}
}

#ifdef CONFIG_COMPAT
static long
ecryptfs_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
	struct file *lower_file = ecryptfs_file_to_lower(file);
	long rc = -ENOIOCTLCMD;

	if (!lower_file->f_op->compat_ioctl)
		return rc;

	switch (cmd) {
	case FS_IOC32_GETFLAGS:
	case FS_IOC32_SETFLAGS:
	case FS_IOC32_GETVERSION:
	case FS_IOC32_SETVERSION:
		rc = lower_file->f_op->compat_ioctl(lower_file, cmd, arg);
		fsstack_copy_attr_all(file_inode(file), file_inode(lower_file));

		return rc;
	default:
		return rc;
	}
}
#endif

const struct file_operations ecryptfs_dir_fops = {
	.iterate_shared = ecryptfs_readdir,
	.read = generic_read_dir,
	.unlocked_ioctl = ecryptfs_unlocked_ioctl,
#ifdef CONFIG_COMPAT
	.compat_ioctl = ecryptfs_compat_ioctl,
#endif
	.open = ecryptfs_dir_open,
	.release = ecryptfs_dir_release,
	.fsync = ecryptfs_fsync,
	.llseek = ecryptfs_dir_llseek,
};

const struct file_operations ecryptfs_main_fops = {
	.llseek = generic_file_llseek,
	.read_iter = ecryptfs_read_update_atime,
	.write_iter = generic_file_write_iter,
	.unlocked_ioctl = ecryptfs_unlocked_ioctl,
#ifdef CONFIG_COMPAT
	.compat_ioctl = ecryptfs_compat_ioctl,
#endif
	.mmap = ecryptfs_mmap,
	.open = ecryptfs_open,
	.flush = ecryptfs_flush,
	.release = ecryptfs_release,
	.fsync = ecryptfs_fsync,
	.fasync = ecryptfs_fasync,
	.splice_read = generic_file_splice_read,
};