xref: /openbmc/linux/fs/ecryptfs/file.c (revision c5254e72) 
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 = filemap_write_and_wait(file->f_mapping);
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 };
427