1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * eCryptfs: Linux filesystem encryption layer
4 *
5 * Copyright (C) 1997-2004 Erez Zadok
6 * Copyright (C) 2001-2004 Stony Brook University
7 * Copyright (C) 2004-2007 International Business Machines Corp.
8 * Author(s): Michael A. Halcrow <mhalcrow@us.ibm.com>
9 * Michael C. Thompson <mcthomps@us.ibm.com>
10 */
11
12 #include <linux/file.h>
13 #include <linux/poll.h>
14 #include <linux/slab.h>
15 #include <linux/mount.h>
16 #include <linux/pagemap.h>
17 #include <linux/security.h>
18 #include <linux/compat.h>
19 #include <linux/fs_stack.h>
20 #include "ecryptfs_kernel.h"
21
22 /*
23 * ecryptfs_read_update_atime
24 *
25 * generic_file_read updates the atime of upper layer inode. But, it
26 * doesn't give us a chance to update the atime of the lower layer
27 * inode. This function is a wrapper to generic_file_read. It
28 * updates the atime of the lower level inode if generic_file_read
29 * returns without any errors. This is to be used only for file reads.
30 * The function to be used for directory reads is ecryptfs_read.
31 */
32 static ssize_t ecryptfs_read_update_atime(struct kiocb *iocb,
33 struct iov_iter *to)
34 {
35 ssize_t rc;
36 const struct path *path;
37 struct file *file = iocb->ki_filp;
38
39 rc = generic_file_read_iter(iocb, to);
40 if (rc >= 0) {
41 path = ecryptfs_dentry_to_lower_path(file->f_path.dentry);
42 touch_atime(path);
43 }
44 return rc;
45 }
46
47 /*
48 * ecryptfs_splice_read_update_atime
49 *
50 * filemap_splice_read updates the atime of upper layer inode. But, it
51 * doesn't give us a chance to update the atime of the lower layer inode. This
52 * function is a wrapper to generic_file_read. It updates the atime of the
53 * lower level inode if generic_file_read returns without any errors. This is
54 * to be used only for file reads. The function to be used for directory reads
55 * is ecryptfs_read.
56 */
57 static ssize_t ecryptfs_splice_read_update_atime(struct file *in, loff_t *ppos,
58 struct pipe_inode_info *pipe,
59 size_t len, unsigned int flags)
60 {
61 ssize_t rc;
62 const struct path *path;
63
64 rc = filemap_splice_read(in, ppos, pipe, len, flags);
65 if (rc >= 0) {
66 path = ecryptfs_dentry_to_lower_path(in->f_path.dentry);
67 touch_atime(path);
68 }
69 return rc;
70 }
71
72 struct ecryptfs_getdents_callback {
73 struct dir_context ctx;
74 struct dir_context *caller;
75 struct super_block *sb;
76 int filldir_called;
77 int entries_written;
78 };
79
80 /* Inspired by generic filldir in fs/readdir.c */
81 static bool
82 ecryptfs_filldir(struct dir_context *ctx, const char *lower_name,
83 int lower_namelen, loff_t offset, u64 ino, unsigned int d_type)
84 {
85 struct ecryptfs_getdents_callback *buf =
86 container_of(ctx, struct ecryptfs_getdents_callback, ctx);
87 size_t name_size;
88 char *name;
89 int err;
90 bool res;
91
92 buf->filldir_called++;
93 err = ecryptfs_decode_and_decrypt_filename(&name, &name_size,
94 buf->sb, lower_name,
95 lower_namelen);
96 if (err) {
97 if (err != -EINVAL) {
98 ecryptfs_printk(KERN_DEBUG,
99 "%s: Error attempting to decode and decrypt filename [%s]; rc = [%d]\n",
100 __func__, lower_name, err);
101 return false;
102 }
103
104 /* Mask -EINVAL errors as these are most likely due a plaintext
105 * filename present in the lower filesystem despite filename
106 * encryption being enabled. One unavoidable example would be
107 * the "lost+found" dentry in the root directory of an Ext4
108 * filesystem.
109 */
110 return true;
111 }
112
113 buf->caller->pos = buf->ctx.pos;
114 res = dir_emit(buf->caller, name, name_size, ino, d_type);
115 kfree(name);
116 if (res)
117 buf->entries_written++;
118 return res;
119 }
120
121 /**
122 * ecryptfs_readdir
123 * @file: The eCryptfs directory file
124 * @ctx: The actor to feed the entries to
125 */
126 static int ecryptfs_readdir(struct file *file, struct dir_context *ctx)
127 {
128 int rc;
129 struct file *lower_file;
130 struct inode *inode = file_inode(file);
131 struct ecryptfs_getdents_callback buf = {
132 .ctx.actor = ecryptfs_filldir,
133 .caller = ctx,
134 .sb = inode->i_sb,
135 };
136 lower_file = ecryptfs_file_to_lower(file);
137 rc = iterate_dir(lower_file, &buf.ctx);
138 ctx->pos = buf.ctx.pos;
139 if (rc >= 0 && (buf.entries_written || !buf.filldir_called))
140 fsstack_copy_attr_atime(inode, file_inode(lower_file));
141 return rc;
142 }
143
144 struct kmem_cache *ecryptfs_file_info_cache;
145
146 static int read_or_initialize_metadata(struct dentry *dentry)
147 {
148 struct inode *inode = d_inode(dentry);
149 struct ecryptfs_mount_crypt_stat *mount_crypt_stat;
150 struct ecryptfs_crypt_stat *crypt_stat;
151 int rc;
152
153 crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat;
154 mount_crypt_stat = &ecryptfs_superblock_to_private(
155 inode->i_sb)->mount_crypt_stat;
156 mutex_lock(&crypt_stat->cs_mutex);
157
158 if (crypt_stat->flags & ECRYPTFS_POLICY_APPLIED &&
159 crypt_stat->flags & ECRYPTFS_KEY_VALID) {
160 rc = 0;
161 goto out;
162 }
163
164 rc = ecryptfs_read_metadata(dentry);
165 if (!rc)
166 goto out;
167
168 if (mount_crypt_stat->flags & ECRYPTFS_PLAINTEXT_PASSTHROUGH_ENABLED) {
169 crypt_stat->flags &= ~(ECRYPTFS_I_SIZE_INITIALIZED
170 | ECRYPTFS_ENCRYPTED);
171 rc = 0;
172 goto out;
173 }
174
175 if (!(mount_crypt_stat->flags & ECRYPTFS_XATTR_METADATA_ENABLED) &&
176 !i_size_read(ecryptfs_inode_to_lower(inode))) {
177 rc = ecryptfs_initialize_file(dentry, inode);
178 if (!rc)
179 goto out;
180 }
181
182 rc = -EIO;
183 out:
184 mutex_unlock(&crypt_stat->cs_mutex);
185 return rc;
186 }
187
188 static int ecryptfs_mmap(struct file *file, struct vm_area_struct *vma)
189 {
190 struct file *lower_file = ecryptfs_file_to_lower(file);
191 /*
192 * Don't allow mmap on top of file systems that don't support it
193 * natively. If FILESYSTEM_MAX_STACK_DEPTH > 2 or ecryptfs
194 * allows recursive mounting, this will need to be extended.
195 */
196 if (!lower_file->f_op->mmap)
197 return -ENODEV;
198 return generic_file_mmap(file, vma);
199 }
200
201 /**
202 * ecryptfs_open
203 * @inode: inode specifying file to open
204 * @file: Structure to return filled in
205 *
206 * Opens the file specified by inode.
207 *
208 * Returns zero on success; non-zero otherwise
209 */
210 static int ecryptfs_open(struct inode *inode, struct file *file)
211 {
212 int rc = 0;
213 struct ecryptfs_crypt_stat *crypt_stat = NULL;
214 struct dentry *ecryptfs_dentry = file->f_path.dentry;
215 /* Private value of ecryptfs_dentry allocated in
216 * ecryptfs_lookup() */
217 struct ecryptfs_file_info *file_info;
218
219 /* Released in ecryptfs_release or end of function if failure */
220 file_info = kmem_cache_zalloc(ecryptfs_file_info_cache, GFP_KERNEL);
221 ecryptfs_set_file_private(file, file_info);
222 if (!file_info) {
223 ecryptfs_printk(KERN_ERR,
224 "Error attempting to allocate memory\n");
225 rc = -ENOMEM;
226 goto out;
227 }
228 crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat;
229 mutex_lock(&crypt_stat->cs_mutex);
230 if (!(crypt_stat->flags & ECRYPTFS_POLICY_APPLIED)) {
231 ecryptfs_printk(KERN_DEBUG, "Setting flags for stat...\n");
232 /* Policy code enabled in future release */
233 crypt_stat->flags |= (ECRYPTFS_POLICY_APPLIED
234 | ECRYPTFS_ENCRYPTED);
235 }
236 mutex_unlock(&crypt_stat->cs_mutex);
237 rc = ecryptfs_get_lower_file(ecryptfs_dentry, inode);
238 if (rc) {
239 printk(KERN_ERR "%s: Error attempting to initialize "
240 "the lower file for the dentry with name "
241 "[%pd]; rc = [%d]\n", __func__,
242 ecryptfs_dentry, rc);
243 goto out_free;
244 }
245 if ((ecryptfs_inode_to_private(inode)->lower_file->f_flags & O_ACCMODE)
246 == O_RDONLY && (file->f_flags & O_ACCMODE) != O_RDONLY) {
247 rc = -EPERM;
248 printk(KERN_WARNING "%s: Lower file is RO; eCryptfs "
249 "file must hence be opened RO\n", __func__);
250 goto out_put;
251 }
252 ecryptfs_set_file_lower(
253 file, ecryptfs_inode_to_private(inode)->lower_file);
254 rc = read_or_initialize_metadata(ecryptfs_dentry);
255 if (rc)
256 goto out_put;
257 ecryptfs_printk(KERN_DEBUG, "inode w/ addr = [0x%p], i_ino = "
258 "[0x%.16lx] size: [0x%.16llx]\n", inode, inode->i_ino,
259 (unsigned long long)i_size_read(inode));
260 goto out;
261 out_put:
262 ecryptfs_put_lower_file(inode);
263 out_free:
264 kmem_cache_free(ecryptfs_file_info_cache,
265 ecryptfs_file_to_private(file));
266 out:
267 return rc;
268 }
269
270 /**
271 * ecryptfs_dir_open
272 * @inode: inode specifying file to open
273 * @file: Structure to return filled in
274 *
275 * Opens the file specified by inode.
276 *
277 * Returns zero on success; non-zero otherwise
278 */
279 static int ecryptfs_dir_open(struct inode *inode, struct file *file)
280 {
281 struct dentry *ecryptfs_dentry = file->f_path.dentry;
282 /* Private value of ecryptfs_dentry allocated in
283 * ecryptfs_lookup() */
284 struct ecryptfs_file_info *file_info;
285 struct file *lower_file;
286
287 /* Released in ecryptfs_release or end of function if failure */
288 file_info = kmem_cache_zalloc(ecryptfs_file_info_cache, GFP_KERNEL);
289 ecryptfs_set_file_private(file, file_info);
290 if (unlikely(!file_info)) {
291 ecryptfs_printk(KERN_ERR,
292 "Error attempting to allocate memory\n");
293 return -ENOMEM;
294 }
295 lower_file = dentry_open(ecryptfs_dentry_to_lower_path(ecryptfs_dentry),
296 file->f_flags, current_cred());
297 if (IS_ERR(lower_file)) {
298 printk(KERN_ERR "%s: Error attempting to initialize "
299 "the lower file for the dentry with name "
300 "[%pd]; rc = [%ld]\n", __func__,
301 ecryptfs_dentry, PTR_ERR(lower_file));
302 kmem_cache_free(ecryptfs_file_info_cache, file_info);
303 return PTR_ERR(lower_file);
304 }
305 ecryptfs_set_file_lower(file, lower_file);
306 return 0;
307 }
308
309 static int ecryptfs_flush(struct file *file, fl_owner_t td)
310 {
311 struct file *lower_file = ecryptfs_file_to_lower(file);
312
313 if (lower_file->f_op->flush) {
314 filemap_write_and_wait(file->f_mapping);
315 return lower_file->f_op->flush(lower_file, td);
316 }
317
318 return 0;
319 }
320
321 static int ecryptfs_release(struct inode *inode, struct file *file)
322 {
323 ecryptfs_put_lower_file(inode);
324 kmem_cache_free(ecryptfs_file_info_cache,
325 ecryptfs_file_to_private(file));
326 return 0;
327 }
328
329 static int ecryptfs_dir_release(struct inode *inode, struct file *file)
330 {
331 fput(ecryptfs_file_to_lower(file));
332 kmem_cache_free(ecryptfs_file_info_cache,
333 ecryptfs_file_to_private(file));
334 return 0;
335 }
336
337 static loff_t ecryptfs_dir_llseek(struct file *file, loff_t offset, int whence)
338 {
339 return vfs_llseek(ecryptfs_file_to_lower(file), offset, whence);
340 }
341
342 static int
343 ecryptfs_fsync(struct file *file, loff_t start, loff_t end, int datasync)
344 {
345 int rc;
346
347 rc = file_write_and_wait(file);
348 if (rc)
349 return rc;
350
351 return vfs_fsync(ecryptfs_file_to_lower(file), datasync);
352 }
353
354 static int ecryptfs_fasync(int fd, struct file *file, int flag)
355 {
356 int rc = 0;
357 struct file *lower_file = NULL;
358
359 lower_file = ecryptfs_file_to_lower(file);
360 if (lower_file->f_op->fasync)
361 rc = lower_file->f_op->fasync(fd, lower_file, flag);
362 return rc;
363 }
364
365 static long
366 ecryptfs_unlocked_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
367 {
368 struct file *lower_file = ecryptfs_file_to_lower(file);
369 long rc = -ENOTTY;
370
371 if (!lower_file->f_op->unlocked_ioctl)
372 return rc;
373
374 switch (cmd) {
375 case FITRIM:
376 case FS_IOC_GETFLAGS:
377 case FS_IOC_SETFLAGS:
378 case FS_IOC_GETVERSION:
379 case FS_IOC_SETVERSION:
380 rc = lower_file->f_op->unlocked_ioctl(lower_file, cmd, arg);
381 fsstack_copy_attr_all(file_inode(file), file_inode(lower_file));
382
383 return rc;
384 default:
385 return rc;
386 }
387 }
388
389 #ifdef CONFIG_COMPAT
390 static long
391 ecryptfs_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
392 {
393 struct file *lower_file = ecryptfs_file_to_lower(file);
394 long rc = -ENOIOCTLCMD;
395
396 if (!lower_file->f_op->compat_ioctl)
397 return rc;
398
399 switch (cmd) {
400 case FITRIM:
401 case FS_IOC32_GETFLAGS:
402 case FS_IOC32_SETFLAGS:
403 case FS_IOC32_GETVERSION:
404 case FS_IOC32_SETVERSION:
405 rc = lower_file->f_op->compat_ioctl(lower_file, cmd, arg);
406 fsstack_copy_attr_all(file_inode(file), file_inode(lower_file));
407
408 return rc;
409 default:
410 return rc;
411 }
412 }
413 #endif
414
415 const struct file_operations ecryptfs_dir_fops = {
416 .iterate_shared = ecryptfs_readdir,
417 .read = generic_read_dir,
418 .unlocked_ioctl = ecryptfs_unlocked_ioctl,
419 #ifdef CONFIG_COMPAT
420 .compat_ioctl = ecryptfs_compat_ioctl,
421 #endif
422 .open = ecryptfs_dir_open,
423 .release = ecryptfs_dir_release,
424 .fsync = ecryptfs_fsync,
425 .llseek = ecryptfs_dir_llseek,
426 };
427
428 const struct file_operations ecryptfs_main_fops = {
429 .llseek = generic_file_llseek,
430 .read_iter = ecryptfs_read_update_atime,
431 .write_iter = generic_file_write_iter,
432 .unlocked_ioctl = ecryptfs_unlocked_ioctl,
433 #ifdef CONFIG_COMPAT
434 .compat_ioctl = ecryptfs_compat_ioctl,
435 #endif
436 .mmap = ecryptfs_mmap,
437 .open = ecryptfs_open,
438 .flush = ecryptfs_flush,
439 .release = ecryptfs_release,
440 .fsync = ecryptfs_fsync,
441 .fasync = ecryptfs_fasync,
442 .splice_read = ecryptfs_splice_read_update_atime,
443 };
444
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