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