xref: /openbmc/linux/fs/ecryptfs/file.c (revision 3932b9ca) 
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 <linux/aio.h>
35 #include "ecryptfs_kernel.h"
36 
37 /**
38  * ecryptfs_read_update_atime
39  *
40  * generic_file_read updates the atime of upper layer inode.  But, it
41  * doesn't give us a chance to update the atime of the lower layer
42  * inode.  This function is a wrapper to generic_file_read.  It
43  * updates the atime of the lower level inode if generic_file_read
44  * returns without any errors. This is to be used only for file reads.
45  * The function to be used for directory reads is ecryptfs_read.
46  */
47 static ssize_t ecryptfs_read_update_atime(struct kiocb *iocb,
48 				struct iov_iter *to)
49 {
50 	ssize_t rc;
51 	struct path *path;
52 	struct file *file = iocb->ki_filp;
53 
54 	rc = generic_file_read_iter(iocb, to);
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 		path = ecryptfs_dentry_to_lower_path(file->f_path.dentry);
63 		touch_atime(path);
64 	}
65 	return rc;
66 }
67 
68 struct ecryptfs_getdents_callback {
69 	struct dir_context ctx;
70 	struct dir_context *caller;
71 	struct super_block *sb;
72 	int filldir_called;
73 	int entries_written;
74 };
75 
76 /* Inspired by generic filldir in fs/readdir.c */
77 static int
78 ecryptfs_filldir(void *dirent, const char *lower_name, int lower_namelen,
79 		 loff_t offset, u64 ino, unsigned int d_type)
80 {
81 	struct ecryptfs_getdents_callback *buf =
82 	    (struct ecryptfs_getdents_callback *)dirent;
83 	size_t name_size;
84 	char *name;
85 	int rc;
86 
87 	buf->filldir_called++;
88 	rc = ecryptfs_decode_and_decrypt_filename(&name, &name_size,
89 						  buf->sb, lower_name,
90 						  lower_namelen);
91 	if (rc) {
92 		printk(KERN_ERR "%s: Error attempting to decode and decrypt "
93 		       "filename [%s]; rc = [%d]\n", __func__, lower_name,
94 		       rc);
95 		goto out;
96 	}
97 	buf->caller->pos = buf->ctx.pos;
98 	rc = !dir_emit(buf->caller, name, name_size, ino, d_type);
99 	kfree(name);
100 	if (!rc)
101 		buf->entries_written++;
102 out:
103 	return rc;
104 }
105 
106 /**
107  * ecryptfs_readdir
108  * @file: The eCryptfs directory file
109  * @ctx: The actor to feed the entries to
110  */
111 static int ecryptfs_readdir(struct file *file, struct dir_context *ctx)
112 {
113 	int rc;
114 	struct file *lower_file;
115 	struct inode *inode = file_inode(file);
116 	struct ecryptfs_getdents_callback buf = {
117 		.ctx.actor = ecryptfs_filldir,
118 		.caller = ctx,
119 		.sb = inode->i_sb,
120 	};
121 	lower_file = ecryptfs_file_to_lower(file);
122 	lower_file->f_pos = ctx->pos;
123 	rc = iterate_dir(lower_file, &buf.ctx);
124 	ctx->pos = buf.ctx.pos;
125 	if (rc < 0)
126 		goto out;
127 	if (buf.filldir_called && !buf.entries_written)
128 		goto out;
129 	if (rc >= 0)
130 		fsstack_copy_attr_atime(inode,
131 					file_inode(lower_file));
132 out:
133 	return rc;
134 }
135 
136 struct kmem_cache *ecryptfs_file_info_cache;
137 
138 static int read_or_initialize_metadata(struct dentry *dentry)
139 {
140 	struct inode *inode = dentry->d_inode;
141 	struct ecryptfs_mount_crypt_stat *mount_crypt_stat;
142 	struct ecryptfs_crypt_stat *crypt_stat;
143 	int rc;
144 
145 	crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat;
146 	mount_crypt_stat = &ecryptfs_superblock_to_private(
147 						inode->i_sb)->mount_crypt_stat;
148 	mutex_lock(&crypt_stat->cs_mutex);
149 
150 	if (crypt_stat->flags & ECRYPTFS_POLICY_APPLIED &&
151 	    crypt_stat->flags & ECRYPTFS_KEY_VALID) {
152 		rc = 0;
153 		goto out;
154 	}
155 
156 	rc = ecryptfs_read_metadata(dentry);
157 	if (!rc)
158 		goto out;
159 
160 	if (mount_crypt_stat->flags & ECRYPTFS_PLAINTEXT_PASSTHROUGH_ENABLED) {
161 		crypt_stat->flags &= ~(ECRYPTFS_I_SIZE_INITIALIZED
162 				       | ECRYPTFS_ENCRYPTED);
163 		rc = 0;
164 		goto out;
165 	}
166 
167 	if (!(mount_crypt_stat->flags & ECRYPTFS_XATTR_METADATA_ENABLED) &&
168 	    !i_size_read(ecryptfs_inode_to_lower(inode))) {
169 		rc = ecryptfs_initialize_file(dentry, inode);
170 		if (!rc)
171 			goto out;
172 	}
173 
174 	rc = -EIO;
175 out:
176 	mutex_unlock(&crypt_stat->cs_mutex);
177 	return rc;
178 }
179 
180 /**
181  * ecryptfs_open
182  * @inode: inode speciying file to open
183  * @file: Structure to return filled in
184  *
185  * Opens the file specified by inode.
186  *
187  * Returns zero on success; non-zero otherwise
188  */
189 static int ecryptfs_open(struct inode *inode, struct file *file)
190 {
191 	int rc = 0;
192 	struct ecryptfs_crypt_stat *crypt_stat = NULL;
193 	struct ecryptfs_mount_crypt_stat *mount_crypt_stat;
194 	struct dentry *ecryptfs_dentry = file->f_path.dentry;
195 	/* Private value of ecryptfs_dentry allocated in
196 	 * ecryptfs_lookup() */
197 	struct ecryptfs_file_info *file_info;
198 
199 	mount_crypt_stat = &ecryptfs_superblock_to_private(
200 		ecryptfs_dentry->d_sb)->mount_crypt_stat;
201 	if ((mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED)
202 	    && ((file->f_flags & O_WRONLY) || (file->f_flags & O_RDWR)
203 		|| (file->f_flags & O_CREAT) || (file->f_flags & O_TRUNC)
204 		|| (file->f_flags & O_APPEND))) {
205 		printk(KERN_WARNING "Mount has encrypted view enabled; "
206 		       "files may only be read\n");
207 		rc = -EPERM;
208 		goto out;
209 	}
210 	/* Released in ecryptfs_release or end of function if failure */
211 	file_info = kmem_cache_zalloc(ecryptfs_file_info_cache, GFP_KERNEL);
212 	ecryptfs_set_file_private(file, file_info);
213 	if (!file_info) {
214 		ecryptfs_printk(KERN_ERR,
215 				"Error attempting to allocate memory\n");
216 		rc = -ENOMEM;
217 		goto out;
218 	}
219 	crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat;
220 	mutex_lock(&crypt_stat->cs_mutex);
221 	if (!(crypt_stat->flags & ECRYPTFS_POLICY_APPLIED)) {
222 		ecryptfs_printk(KERN_DEBUG, "Setting flags for stat...\n");
223 		/* Policy code enabled in future release */
224 		crypt_stat->flags |= (ECRYPTFS_POLICY_APPLIED
225 				      | ECRYPTFS_ENCRYPTED);
226 	}
227 	mutex_unlock(&crypt_stat->cs_mutex);
228 	rc = ecryptfs_get_lower_file(ecryptfs_dentry, inode);
229 	if (rc) {
230 		printk(KERN_ERR "%s: Error attempting to initialize "
231 			"the lower file for the dentry with name "
232 			"[%s]; rc = [%d]\n", __func__,
233 			ecryptfs_dentry->d_name.name, rc);
234 		goto out_free;
235 	}
236 	if ((ecryptfs_inode_to_private(inode)->lower_file->f_flags & O_ACCMODE)
237 	    == O_RDONLY && (file->f_flags & O_ACCMODE) != O_RDONLY) {
238 		rc = -EPERM;
239 		printk(KERN_WARNING "%s: Lower file is RO; eCryptfs "
240 		       "file must hence be opened RO\n", __func__);
241 		goto out_put;
242 	}
243 	ecryptfs_set_file_lower(
244 		file, ecryptfs_inode_to_private(inode)->lower_file);
245 	if (S_ISDIR(ecryptfs_dentry->d_inode->i_mode)) {
246 		ecryptfs_printk(KERN_DEBUG, "This is a directory\n");
247 		mutex_lock(&crypt_stat->cs_mutex);
248 		crypt_stat->flags &= ~(ECRYPTFS_ENCRYPTED);
249 		mutex_unlock(&crypt_stat->cs_mutex);
250 		rc = 0;
251 		goto out;
252 	}
253 	rc = read_or_initialize_metadata(ecryptfs_dentry);
254 	if (rc)
255 		goto out_put;
256 	ecryptfs_printk(KERN_DEBUG, "inode w/ addr = [0x%p], i_ino = "
257 			"[0x%.16lx] size: [0x%.16llx]\n", inode, inode->i_ino,
258 			(unsigned long long)i_size_read(inode));
259 	goto out;
260 out_put:
261 	ecryptfs_put_lower_file(inode);
262 out_free:
263 	kmem_cache_free(ecryptfs_file_info_cache,
264 			ecryptfs_file_to_private(file));
265 out:
266 	return rc;
267 }
268 
269 static int ecryptfs_flush(struct file *file, fl_owner_t td)
270 {
271 	struct file *lower_file = ecryptfs_file_to_lower(file);
272 
273 	if (lower_file->f_op->flush) {
274 		filemap_write_and_wait(file->f_mapping);
275 		return lower_file->f_op->flush(lower_file, td);
276 	}
277 
278 	return 0;
279 }
280 
281 static int ecryptfs_release(struct inode *inode, struct file *file)
282 {
283 	ecryptfs_put_lower_file(inode);
284 	kmem_cache_free(ecryptfs_file_info_cache,
285 			ecryptfs_file_to_private(file));
286 	return 0;
287 }
288 
289 static int
290 ecryptfs_fsync(struct file *file, loff_t start, loff_t end, int datasync)
291 {
292 	int rc;
293 
294 	rc = filemap_write_and_wait(file->f_mapping);
295 	if (rc)
296 		return rc;
297 
298 	return vfs_fsync(ecryptfs_file_to_lower(file), datasync);
299 }
300 
301 static int ecryptfs_fasync(int fd, struct file *file, int flag)
302 {
303 	int rc = 0;
304 	struct file *lower_file = NULL;
305 
306 	lower_file = ecryptfs_file_to_lower(file);
307 	if (lower_file->f_op->fasync)
308 		rc = lower_file->f_op->fasync(fd, lower_file, flag);
309 	return rc;
310 }
311 
312 static long
313 ecryptfs_unlocked_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
314 {
315 	struct file *lower_file = ecryptfs_file_to_lower(file);
316 	long rc = -ENOTTY;
317 
318 	if (lower_file->f_op->unlocked_ioctl)
319 		rc = lower_file->f_op->unlocked_ioctl(lower_file, cmd, arg);
320 	return rc;
321 }
322 
323 #ifdef CONFIG_COMPAT
324 static long
325 ecryptfs_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
326 {
327 	struct file *lower_file = ecryptfs_file_to_lower(file);
328 	long rc = -ENOIOCTLCMD;
329 
330 	if (lower_file->f_op && lower_file->f_op->compat_ioctl)
331 		rc = lower_file->f_op->compat_ioctl(lower_file, cmd, arg);
332 	return rc;
333 }
334 #endif
335 
336 const struct file_operations ecryptfs_dir_fops = {
337 	.iterate = ecryptfs_readdir,
338 	.read = generic_read_dir,
339 	.unlocked_ioctl = ecryptfs_unlocked_ioctl,
340 #ifdef CONFIG_COMPAT
341 	.compat_ioctl = ecryptfs_compat_ioctl,
342 #endif
343 	.open = ecryptfs_open,
344 	.flush = ecryptfs_flush,
345 	.release = ecryptfs_release,
346 	.fsync = ecryptfs_fsync,
347 	.fasync = ecryptfs_fasync,
348 	.splice_read = generic_file_splice_read,
349 	.llseek = default_llseek,
350 };
351 
352 const struct file_operations ecryptfs_main_fops = {
353 	.llseek = generic_file_llseek,
354 	.read = new_sync_read,
355 	.read_iter = ecryptfs_read_update_atime,
356 	.write = new_sync_write,
357 	.write_iter = generic_file_write_iter,
358 	.iterate = ecryptfs_readdir,
359 	.unlocked_ioctl = ecryptfs_unlocked_ioctl,
360 #ifdef CONFIG_COMPAT
361 	.compat_ioctl = ecryptfs_compat_ioctl,
362 #endif
363 	.mmap = generic_file_mmap,
364 	.open = ecryptfs_open,
365 	.flush = ecryptfs_flush,
366 	.release = ecryptfs_release,
367 	.fsync = ecryptfs_fsync,
368 	.fasync = ecryptfs_fasync,
369 	.splice_read = generic_file_splice_read,
370 };
371