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