1 /* SPDX-License-Identifier: GPL-2.0 */
2 /*
3 * fscrypt.h: declarations for per-file encryption
4 *
5 * Filesystems that implement per-file encryption must include this header
6 * file.
7 *
8 * Copyright (C) 2015, Google, Inc.
9 *
10 * Written by Michael Halcrow, 2015.
11 * Modified by Jaegeuk Kim, 2015.
12 */
13 #ifndef _LINUX_FSCRYPT_H
14 #define _LINUX_FSCRYPT_H
15
16 #include <linux/fs.h>
17 #include <linux/mm.h>
18 #include <linux/slab.h>
19 #include <uapi/linux/fscrypt.h>
20
21 /*
22 * The lengths of all file contents blocks must be divisible by this value.
23 * This is needed to ensure that all contents encryption modes will work, as
24 * some of the supported modes don't support arbitrarily byte-aligned messages.
25 *
26 * Since the needed alignment is 16 bytes, most filesystems will meet this
27 * requirement naturally, as typical block sizes are powers of 2. However, if a
28 * filesystem can generate arbitrarily byte-aligned block lengths (e.g., via
29 * compression), then it will need to pad to this alignment before encryption.
30 */
31 #define FSCRYPT_CONTENTS_ALIGNMENT 16
32
33 union fscrypt_policy;
34 struct fscrypt_inode_info;
35 struct fs_parameter;
36 struct seq_file;
37
38 struct fscrypt_str {
39 unsigned char *name;
40 u32 len;
41 };
42
43 struct fscrypt_name {
44 const struct qstr *usr_fname;
45 struct fscrypt_str disk_name;
46 u32 hash;
47 u32 minor_hash;
48 struct fscrypt_str crypto_buf;
49 bool is_nokey_name;
50 };
51
52 #define FSTR_INIT(n, l) { .name = n, .len = l }
53 #define FSTR_TO_QSTR(f) QSTR_INIT((f)->name, (f)->len)
54 #define fname_name(p) ((p)->disk_name.name)
55 #define fname_len(p) ((p)->disk_name.len)
56
57 /* Maximum value for the third parameter of fscrypt_operations.set_context(). */
58 #define FSCRYPT_SET_CONTEXT_MAX_SIZE 40
59
60 #ifdef CONFIG_FS_ENCRYPTION
61
62 /* Crypto operations for filesystems */
63 struct fscrypt_operations {
64
65 /*
66 * If set, then fs/crypto/ will allocate a global bounce page pool the
67 * first time an encryption key is set up for a file. The bounce page
68 * pool is required by the following functions:
69 *
70 * - fscrypt_encrypt_pagecache_blocks()
71 * - fscrypt_zeroout_range() for files not using inline crypto
72 *
73 * If the filesystem doesn't use those, it doesn't need to set this.
74 */
75 unsigned int needs_bounce_pages : 1;
76
77 /*
78 * If set, then fs/crypto/ will allow the use of encryption settings
79 * that assume inode numbers fit in 32 bits (i.e.
80 * FSCRYPT_POLICY_FLAG_IV_INO_LBLK_{32,64}), provided that the other
81 * prerequisites for these settings are also met. This is only useful
82 * if the filesystem wants to support inline encryption hardware that is
83 * limited to 32-bit or 64-bit data unit numbers and where programming
84 * keyslots is very slow.
85 */
86 unsigned int has_32bit_inodes : 1;
87
88 /*
89 * If set, then fs/crypto/ will allow users to select a crypto data unit
90 * size that is less than the filesystem block size. This is done via
91 * the log2_data_unit_size field of the fscrypt policy. This flag is
92 * not compatible with filesystems that encrypt variable-length blocks
93 * (i.e. blocks that aren't all equal to filesystem's block size), for
94 * example as a result of compression. It's also not compatible with
95 * the fscrypt_encrypt_block_inplace() and
96 * fscrypt_decrypt_block_inplace() functions.
97 */
98 unsigned int supports_subblock_data_units : 1;
99
100 /*
101 * This field exists only for backwards compatibility reasons and should
102 * only be set by the filesystems that are setting it already. It
103 * contains the filesystem-specific key description prefix that is
104 * accepted for "logon" keys for v1 fscrypt policies. This
105 * functionality is deprecated in favor of the generic prefix
106 * "fscrypt:", which itself is deprecated in favor of the filesystem
107 * keyring ioctls such as FS_IOC_ADD_ENCRYPTION_KEY. Filesystems that
108 * are newly adding fscrypt support should not set this field.
109 */
110 const char *legacy_key_prefix;
111
112 /*
113 * Get the fscrypt context of the given inode.
114 *
115 * @inode: the inode whose context to get
116 * @ctx: the buffer into which to get the context
117 * @len: length of the @ctx buffer in bytes
118 *
119 * Return: On success, returns the length of the context in bytes; this
120 * may be less than @len. On failure, returns -ENODATA if the
121 * inode doesn't have a context, -ERANGE if the context is
122 * longer than @len, or another -errno code.
123 */
124 int (*get_context)(struct inode *inode, void *ctx, size_t len);
125
126 /*
127 * Set an fscrypt context on the given inode.
128 *
129 * @inode: the inode whose context to set. The inode won't already have
130 * an fscrypt context.
131 * @ctx: the context to set
132 * @len: length of @ctx in bytes (at most FSCRYPT_SET_CONTEXT_MAX_SIZE)
133 * @fs_data: If called from fscrypt_set_context(), this will be the
134 * value the filesystem passed to fscrypt_set_context().
135 * Otherwise (i.e. when called from
136 * FS_IOC_SET_ENCRYPTION_POLICY) this will be NULL.
137 *
138 * i_rwsem will be held for write.
139 *
140 * Return: 0 on success, -errno on failure.
141 */
142 int (*set_context)(struct inode *inode, const void *ctx, size_t len,
143 void *fs_data);
144
145 /*
146 * Get the dummy fscrypt policy in use on the filesystem (if any).
147 *
148 * Filesystems only need to implement this function if they support the
149 * test_dummy_encryption mount option.
150 *
151 * Return: A pointer to the dummy fscrypt policy, if the filesystem is
152 * mounted with test_dummy_encryption; otherwise NULL.
153 */
154 const union fscrypt_policy *(*get_dummy_policy)(struct super_block *sb);
155
156 /*
157 * Check whether a directory is empty. i_rwsem will be held for write.
158 */
159 bool (*empty_dir)(struct inode *inode);
160
161 /*
162 * Check whether the filesystem's inode numbers and UUID are stable,
163 * meaning that they will never be changed even by offline operations
164 * such as filesystem shrinking and therefore can be used in the
165 * encryption without the possibility of files becoming unreadable.
166 *
167 * Filesystems only need to implement this function if they want to
168 * support the FSCRYPT_POLICY_FLAG_IV_INO_LBLK_{32,64} flags. These
169 * flags are designed to work around the limitations of UFS and eMMC
170 * inline crypto hardware, and they shouldn't be used in scenarios where
171 * such hardware isn't being used.
172 *
173 * Leaving this NULL is equivalent to always returning false.
174 */
175 bool (*has_stable_inodes)(struct super_block *sb);
176
177 /*
178 * Return an array of pointers to the block devices to which the
179 * filesystem may write encrypted file contents, NULL if the filesystem
180 * only has a single such block device, or an ERR_PTR() on error.
181 *
182 * On successful non-NULL return, *num_devs is set to the number of
183 * devices in the returned array. The caller must free the returned
184 * array using kfree().
185 *
186 * If the filesystem can use multiple block devices (other than block
187 * devices that aren't used for encrypted file contents, such as
188 * external journal devices), and wants to support inline encryption,
189 * then it must implement this function. Otherwise it's not needed.
190 */
191 struct block_device **(*get_devices)(struct super_block *sb,
192 unsigned int *num_devs);
193 };
194
195 int fscrypt_d_revalidate(struct dentry *dentry, unsigned int flags);
196
197 static inline struct fscrypt_inode_info *
198 fscrypt_get_inode_info(const struct inode *inode)
199 {
200 /*
201 * Pairs with the cmpxchg_release() in fscrypt_setup_encryption_info().
202 * I.e., another task may publish ->i_crypt_info concurrently, executing
203 * a RELEASE barrier. We need to use smp_load_acquire() here to safely
204 * ACQUIRE the memory the other task published.
205 */
206 return smp_load_acquire(&inode->i_crypt_info);
207 }
208
209 /**
210 * fscrypt_needs_contents_encryption() - check whether an inode needs
211 * contents encryption
212 * @inode: the inode to check
213 *
214 * Return: %true iff the inode is an encrypted regular file and the kernel was
215 * built with fscrypt support.
216 *
217 * If you need to know whether the encrypt bit is set even when the kernel was
218 * built without fscrypt support, you must use IS_ENCRYPTED() directly instead.
219 */
220 static inline bool fscrypt_needs_contents_encryption(const struct inode *inode)
221 {
222 return IS_ENCRYPTED(inode) && S_ISREG(inode->i_mode);
223 }
224
225 /*
226 * When d_splice_alias() moves a directory's no-key alias to its
227 * plaintext alias as a result of the encryption key being added,
228 * DCACHE_NOKEY_NAME must be cleared and there might be an opportunity
229 * to disable d_revalidate. Note that we don't have to support the
230 * inverse operation because fscrypt doesn't allow no-key names to be
231 * the source or target of a rename().
232 */
233 static inline void fscrypt_handle_d_move(struct dentry *dentry)
234 {
235 /*
236 * VFS calls fscrypt_handle_d_move even for non-fscrypt
237 * filesystems.
238 */
239 if (dentry->d_flags & DCACHE_NOKEY_NAME) {
240 dentry->d_flags &= ~DCACHE_NOKEY_NAME;
241
242 /*
243 * Other filesystem features might be handling dentry
244 * revalidation, in which case it cannot be disabled.
245 */
246 if (dentry->d_op->d_revalidate == fscrypt_d_revalidate)
247 dentry->d_flags &= ~DCACHE_OP_REVALIDATE;
248 }
249 }
250
251 /**
252 * fscrypt_is_nokey_name() - test whether a dentry is a no-key name
253 * @dentry: the dentry to check
254 *
255 * This returns true if the dentry is a no-key dentry. A no-key dentry is a
256 * dentry that was created in an encrypted directory that hasn't had its
257 * encryption key added yet. Such dentries may be either positive or negative.
258 *
259 * When a filesystem is asked to create a new filename in an encrypted directory
260 * and the new filename's dentry is a no-key dentry, it must fail the operation
261 * with ENOKEY. This includes ->create(), ->mkdir(), ->mknod(), ->symlink(),
262 * ->rename(), and ->link(). (However, ->rename() and ->link() are already
263 * handled by fscrypt_prepare_rename() and fscrypt_prepare_link().)
264 *
265 * This is necessary because creating a filename requires the directory's
266 * encryption key, but just checking for the key on the directory inode during
267 * the final filesystem operation doesn't guarantee that the key was available
268 * during the preceding dentry lookup. And the key must have already been
269 * available during the dentry lookup in order for it to have been checked
270 * whether the filename already exists in the directory and for the new file's
271 * dentry not to be invalidated due to it incorrectly having the no-key flag.
272 *
273 * Return: %true if the dentry is a no-key name
274 */
275 static inline bool fscrypt_is_nokey_name(const struct dentry *dentry)
276 {
277 return dentry->d_flags & DCACHE_NOKEY_NAME;
278 }
279
280 static inline void fscrypt_prepare_dentry(struct dentry *dentry,
281 bool is_nokey_name)
282 {
283 /*
284 * This code tries to only take ->d_lock when necessary to write
285 * to ->d_flags. We shouldn't be peeking on d_flags for
286 * DCACHE_OP_REVALIDATE unlocked, but in the unlikely case
287 * there is a race, the worst it can happen is that we fail to
288 * unset DCACHE_OP_REVALIDATE and pay the cost of an extra
289 * d_revalidate.
290 */
291 if (is_nokey_name) {
292 spin_lock(&dentry->d_lock);
293 dentry->d_flags |= DCACHE_NOKEY_NAME;
294 spin_unlock(&dentry->d_lock);
295 } else if (dentry->d_flags & DCACHE_OP_REVALIDATE &&
296 dentry->d_op->d_revalidate == fscrypt_d_revalidate) {
297 /*
298 * Unencrypted dentries and encrypted dentries where the
299 * key is available are always valid from fscrypt
300 * perspective. Avoid the cost of calling
301 * fscrypt_d_revalidate unnecessarily.
302 */
303 spin_lock(&dentry->d_lock);
304 dentry->d_flags &= ~DCACHE_OP_REVALIDATE;
305 spin_unlock(&dentry->d_lock);
306 }
307 }
308
309 /* crypto.c */
310 void fscrypt_enqueue_decrypt_work(struct work_struct *);
311
312 struct page *fscrypt_encrypt_pagecache_blocks(struct page *page,
313 unsigned int len,
314 unsigned int offs,
315 gfp_t gfp_flags);
316 int fscrypt_encrypt_block_inplace(const struct inode *inode, struct page *page,
317 unsigned int len, unsigned int offs,
318 u64 lblk_num, gfp_t gfp_flags);
319
320 int fscrypt_decrypt_pagecache_blocks(struct folio *folio, size_t len,
321 size_t offs);
322 int fscrypt_decrypt_block_inplace(const struct inode *inode, struct page *page,
323 unsigned int len, unsigned int offs,
324 u64 lblk_num);
325
326 static inline bool fscrypt_is_bounce_page(struct page *page)
327 {
328 return page->mapping == NULL;
329 }
330
331 static inline struct page *fscrypt_pagecache_page(struct page *bounce_page)
332 {
333 return (struct page *)page_private(bounce_page);
334 }
335
336 static inline bool fscrypt_is_bounce_folio(struct folio *folio)
337 {
338 return folio->mapping == NULL;
339 }
340
341 static inline struct folio *fscrypt_pagecache_folio(struct folio *bounce_folio)
342 {
343 return bounce_folio->private;
344 }
345
346 void fscrypt_free_bounce_page(struct page *bounce_page);
347
348 /* policy.c */
349 int fscrypt_ioctl_set_policy(struct file *filp, const void __user *arg);
350 int fscrypt_ioctl_get_policy(struct file *filp, void __user *arg);
351 int fscrypt_ioctl_get_policy_ex(struct file *filp, void __user *arg);
352 int fscrypt_ioctl_get_nonce(struct file *filp, void __user *arg);
353 int fscrypt_has_permitted_context(struct inode *parent, struct inode *child);
354 int fscrypt_context_for_new_inode(void *ctx, struct inode *inode);
355 int fscrypt_set_context(struct inode *inode, void *fs_data);
356
357 struct fscrypt_dummy_policy {
358 const union fscrypt_policy *policy;
359 };
360
361 int fscrypt_parse_test_dummy_encryption(const struct fs_parameter *param,
362 struct fscrypt_dummy_policy *dummy_policy);
363 bool fscrypt_dummy_policies_equal(const struct fscrypt_dummy_policy *p1,
364 const struct fscrypt_dummy_policy *p2);
365 void fscrypt_show_test_dummy_encryption(struct seq_file *seq, char sep,
366 struct super_block *sb);
367 static inline bool
368 fscrypt_is_dummy_policy_set(const struct fscrypt_dummy_policy *dummy_policy)
369 {
370 return dummy_policy->policy != NULL;
371 }
372 static inline void
373 fscrypt_free_dummy_policy(struct fscrypt_dummy_policy *dummy_policy)
374 {
375 kfree(dummy_policy->policy);
376 dummy_policy->policy = NULL;
377 }
378
379 /* keyring.c */
380 void fscrypt_destroy_keyring(struct super_block *sb);
381 int fscrypt_ioctl_add_key(struct file *filp, void __user *arg);
382 int fscrypt_ioctl_remove_key(struct file *filp, void __user *arg);
383 int fscrypt_ioctl_remove_key_all_users(struct file *filp, void __user *arg);
384 int fscrypt_ioctl_get_key_status(struct file *filp, void __user *arg);
385
386 /* keysetup.c */
387 int fscrypt_prepare_new_inode(struct inode *dir, struct inode *inode,
388 bool *encrypt_ret);
389 void fscrypt_put_encryption_info(struct inode *inode);
390 void fscrypt_free_inode(struct inode *inode);
391 int fscrypt_drop_inode(struct inode *inode);
392
393 /* fname.c */
394 int fscrypt_fname_encrypt(const struct inode *inode, const struct qstr *iname,
395 u8 *out, unsigned int olen);
396 bool fscrypt_fname_encrypted_size(const struct inode *inode, u32 orig_len,
397 u32 max_len, u32 *encrypted_len_ret);
398 int fscrypt_setup_filename(struct inode *inode, const struct qstr *iname,
399 int lookup, struct fscrypt_name *fname);
400
401 static inline void fscrypt_free_filename(struct fscrypt_name *fname)
402 {
403 kfree(fname->crypto_buf.name);
404 }
405
406 int fscrypt_fname_alloc_buffer(u32 max_encrypted_len,
407 struct fscrypt_str *crypto_str);
408 void fscrypt_fname_free_buffer(struct fscrypt_str *crypto_str);
409 int fscrypt_fname_disk_to_usr(const struct inode *inode,
410 u32 hash, u32 minor_hash,
411 const struct fscrypt_str *iname,
412 struct fscrypt_str *oname);
413 bool fscrypt_match_name(const struct fscrypt_name *fname,
414 const u8 *de_name, u32 de_name_len);
415 u64 fscrypt_fname_siphash(const struct inode *dir, const struct qstr *name);
416
417 /* bio.c */
418 bool fscrypt_decrypt_bio(struct bio *bio);
419 int fscrypt_zeroout_range(const struct inode *inode, pgoff_t lblk,
420 sector_t pblk, unsigned int len);
421
422 /* hooks.c */
423 int fscrypt_file_open(struct inode *inode, struct file *filp);
424 int __fscrypt_prepare_link(struct inode *inode, struct inode *dir,
425 struct dentry *dentry);
426 int __fscrypt_prepare_rename(struct inode *old_dir, struct dentry *old_dentry,
427 struct inode *new_dir, struct dentry *new_dentry,
428 unsigned int flags);
429 int __fscrypt_prepare_lookup(struct inode *dir, struct dentry *dentry,
430 struct fscrypt_name *fname);
431 int fscrypt_prepare_lookup_partial(struct inode *dir, struct dentry *dentry);
432 int __fscrypt_prepare_readdir(struct inode *dir);
433 int __fscrypt_prepare_setattr(struct dentry *dentry, struct iattr *attr);
434 int fscrypt_prepare_setflags(struct inode *inode,
435 unsigned int oldflags, unsigned int flags);
436 int fscrypt_prepare_symlink(struct inode *dir, const char *target,
437 unsigned int len, unsigned int max_len,
438 struct fscrypt_str *disk_link);
439 int __fscrypt_encrypt_symlink(struct inode *inode, const char *target,
440 unsigned int len, struct fscrypt_str *disk_link);
441 const char *fscrypt_get_symlink(struct inode *inode, const void *caddr,
442 unsigned int max_size,
443 struct delayed_call *done);
444 int fscrypt_symlink_getattr(const struct path *path, struct kstat *stat);
445 static inline void fscrypt_set_ops(struct super_block *sb,
446 const struct fscrypt_operations *s_cop)
447 {
448 sb->s_cop = s_cop;
449 }
450 #else /* !CONFIG_FS_ENCRYPTION */
451
452 static inline struct fscrypt_inode_info *
453 fscrypt_get_inode_info(const struct inode *inode)
454 {
455 return NULL;
456 }
457
458 static inline bool fscrypt_needs_contents_encryption(const struct inode *inode)
459 {
460 return false;
461 }
462
463 static inline void fscrypt_handle_d_move(struct dentry *dentry)
464 {
465 }
466
467 static inline bool fscrypt_is_nokey_name(const struct dentry *dentry)
468 {
469 return false;
470 }
471
472 static inline void fscrypt_prepare_dentry(struct dentry *dentry,
473 bool is_nokey_name)
474 {
475 }
476
477 /* crypto.c */
478 static inline void fscrypt_enqueue_decrypt_work(struct work_struct *work)
479 {
480 }
481
482 static inline struct page *fscrypt_encrypt_pagecache_blocks(struct page *page,
483 unsigned int len,
484 unsigned int offs,
485 gfp_t gfp_flags)
486 {
487 return ERR_PTR(-EOPNOTSUPP);
488 }
489
490 static inline int fscrypt_encrypt_block_inplace(const struct inode *inode,
491 struct page *page,
492 unsigned int len,
493 unsigned int offs, u64 lblk_num,
494 gfp_t gfp_flags)
495 {
496 return -EOPNOTSUPP;
497 }
498
499 static inline int fscrypt_decrypt_pagecache_blocks(struct folio *folio,
500 size_t len, size_t offs)
501 {
502 return -EOPNOTSUPP;
503 }
504
505 static inline int fscrypt_decrypt_block_inplace(const struct inode *inode,
506 struct page *page,
507 unsigned int len,
508 unsigned int offs, u64 lblk_num)
509 {
510 return -EOPNOTSUPP;
511 }
512
513 static inline bool fscrypt_is_bounce_page(struct page *page)
514 {
515 return false;
516 }
517
518 static inline struct page *fscrypt_pagecache_page(struct page *bounce_page)
519 {
520 WARN_ON_ONCE(1);
521 return ERR_PTR(-EINVAL);
522 }
523
524 static inline bool fscrypt_is_bounce_folio(struct folio *folio)
525 {
526 return false;
527 }
528
529 static inline struct folio *fscrypt_pagecache_folio(struct folio *bounce_folio)
530 {
531 WARN_ON_ONCE(1);
532 return ERR_PTR(-EINVAL);
533 }
534
535 static inline void fscrypt_free_bounce_page(struct page *bounce_page)
536 {
537 }
538
539 /* policy.c */
540 static inline int fscrypt_ioctl_set_policy(struct file *filp,
541 const void __user *arg)
542 {
543 return -EOPNOTSUPP;
544 }
545
546 static inline int fscrypt_ioctl_get_policy(struct file *filp, void __user *arg)
547 {
548 return -EOPNOTSUPP;
549 }
550
551 static inline int fscrypt_ioctl_get_policy_ex(struct file *filp,
552 void __user *arg)
553 {
554 return -EOPNOTSUPP;
555 }
556
557 static inline int fscrypt_ioctl_get_nonce(struct file *filp, void __user *arg)
558 {
559 return -EOPNOTSUPP;
560 }
561
562 static inline int fscrypt_has_permitted_context(struct inode *parent,
563 struct inode *child)
564 {
565 return 0;
566 }
567
568 static inline int fscrypt_set_context(struct inode *inode, void *fs_data)
569 {
570 return -EOPNOTSUPP;
571 }
572
573 struct fscrypt_dummy_policy {
574 };
575
576 static inline int
577 fscrypt_parse_test_dummy_encryption(const struct fs_parameter *param,
578 struct fscrypt_dummy_policy *dummy_policy)
579 {
580 return -EINVAL;
581 }
582
583 static inline bool
584 fscrypt_dummy_policies_equal(const struct fscrypt_dummy_policy *p1,
585 const struct fscrypt_dummy_policy *p2)
586 {
587 return true;
588 }
589
590 static inline void fscrypt_show_test_dummy_encryption(struct seq_file *seq,
591 char sep,
592 struct super_block *sb)
593 {
594 }
595
596 static inline bool
597 fscrypt_is_dummy_policy_set(const struct fscrypt_dummy_policy *dummy_policy)
598 {
599 return false;
600 }
601
602 static inline void
603 fscrypt_free_dummy_policy(struct fscrypt_dummy_policy *dummy_policy)
604 {
605 }
606
607 /* keyring.c */
608 static inline void fscrypt_destroy_keyring(struct super_block *sb)
609 {
610 }
611
612 static inline int fscrypt_ioctl_add_key(struct file *filp, void __user *arg)
613 {
614 return -EOPNOTSUPP;
615 }
616
617 static inline int fscrypt_ioctl_remove_key(struct file *filp, void __user *arg)
618 {
619 return -EOPNOTSUPP;
620 }
621
622 static inline int fscrypt_ioctl_remove_key_all_users(struct file *filp,
623 void __user *arg)
624 {
625 return -EOPNOTSUPP;
626 }
627
628 static inline int fscrypt_ioctl_get_key_status(struct file *filp,
629 void __user *arg)
630 {
631 return -EOPNOTSUPP;
632 }
633
634 /* keysetup.c */
635
636 static inline int fscrypt_prepare_new_inode(struct inode *dir,
637 struct inode *inode,
638 bool *encrypt_ret)
639 {
640 if (IS_ENCRYPTED(dir))
641 return -EOPNOTSUPP;
642 return 0;
643 }
644
645 static inline void fscrypt_put_encryption_info(struct inode *inode)
646 {
647 return;
648 }
649
650 static inline void fscrypt_free_inode(struct inode *inode)
651 {
652 }
653
654 static inline int fscrypt_drop_inode(struct inode *inode)
655 {
656 return 0;
657 }
658
659 /* fname.c */
660 static inline int fscrypt_setup_filename(struct inode *dir,
661 const struct qstr *iname,
662 int lookup, struct fscrypt_name *fname)
663 {
664 if (IS_ENCRYPTED(dir))
665 return -EOPNOTSUPP;
666
667 memset(fname, 0, sizeof(*fname));
668 fname->usr_fname = iname;
669 fname->disk_name.name = (unsigned char *)iname->name;
670 fname->disk_name.len = iname->len;
671 return 0;
672 }
673
674 static inline void fscrypt_free_filename(struct fscrypt_name *fname)
675 {
676 return;
677 }
678
679 static inline int fscrypt_fname_alloc_buffer(u32 max_encrypted_len,
680 struct fscrypt_str *crypto_str)
681 {
682 return -EOPNOTSUPP;
683 }
684
685 static inline void fscrypt_fname_free_buffer(struct fscrypt_str *crypto_str)
686 {
687 return;
688 }
689
690 static inline int fscrypt_fname_disk_to_usr(const struct inode *inode,
691 u32 hash, u32 minor_hash,
692 const struct fscrypt_str *iname,
693 struct fscrypt_str *oname)
694 {
695 return -EOPNOTSUPP;
696 }
697
698 static inline bool fscrypt_match_name(const struct fscrypt_name *fname,
699 const u8 *de_name, u32 de_name_len)
700 {
701 /* Encryption support disabled; use standard comparison */
702 if (de_name_len != fname->disk_name.len)
703 return false;
704 return !memcmp(de_name, fname->disk_name.name, fname->disk_name.len);
705 }
706
707 static inline u64 fscrypt_fname_siphash(const struct inode *dir,
708 const struct qstr *name)
709 {
710 WARN_ON_ONCE(1);
711 return 0;
712 }
713
714 static inline int fscrypt_d_revalidate(struct dentry *dentry,
715 unsigned int flags)
716 {
717 return 1;
718 }
719
720 /* bio.c */
721 static inline bool fscrypt_decrypt_bio(struct bio *bio)
722 {
723 return true;
724 }
725
726 static inline int fscrypt_zeroout_range(const struct inode *inode, pgoff_t lblk,
727 sector_t pblk, unsigned int len)
728 {
729 return -EOPNOTSUPP;
730 }
731
732 /* hooks.c */
733
734 static inline int fscrypt_file_open(struct inode *inode, struct file *filp)
735 {
736 if (IS_ENCRYPTED(inode))
737 return -EOPNOTSUPP;
738 return 0;
739 }
740
741 static inline int __fscrypt_prepare_link(struct inode *inode, struct inode *dir,
742 struct dentry *dentry)
743 {
744 return -EOPNOTSUPP;
745 }
746
747 static inline int __fscrypt_prepare_rename(struct inode *old_dir,
748 struct dentry *old_dentry,
749 struct inode *new_dir,
750 struct dentry *new_dentry,
751 unsigned int flags)
752 {
753 return -EOPNOTSUPP;
754 }
755
756 static inline int __fscrypt_prepare_lookup(struct inode *dir,
757 struct dentry *dentry,
758 struct fscrypt_name *fname)
759 {
760 return -EOPNOTSUPP;
761 }
762
763 static inline int fscrypt_prepare_lookup_partial(struct inode *dir,
764 struct dentry *dentry)
765 {
766 return -EOPNOTSUPP;
767 }
768
769 static inline int __fscrypt_prepare_readdir(struct inode *dir)
770 {
771 return -EOPNOTSUPP;
772 }
773
774 static inline int __fscrypt_prepare_setattr(struct dentry *dentry,
775 struct iattr *attr)
776 {
777 return -EOPNOTSUPP;
778 }
779
780 static inline int fscrypt_prepare_setflags(struct inode *inode,
781 unsigned int oldflags,
782 unsigned int flags)
783 {
784 return 0;
785 }
786
787 static inline int fscrypt_prepare_symlink(struct inode *dir,
788 const char *target,
789 unsigned int len,
790 unsigned int max_len,
791 struct fscrypt_str *disk_link)
792 {
793 if (IS_ENCRYPTED(dir))
794 return -EOPNOTSUPP;
795 disk_link->name = (unsigned char *)target;
796 disk_link->len = len + 1;
797 if (disk_link->len > max_len)
798 return -ENAMETOOLONG;
799 return 0;
800 }
801
802 static inline int __fscrypt_encrypt_symlink(struct inode *inode,
803 const char *target,
804 unsigned int len,
805 struct fscrypt_str *disk_link)
806 {
807 return -EOPNOTSUPP;
808 }
809
810 static inline const char *fscrypt_get_symlink(struct inode *inode,
811 const void *caddr,
812 unsigned int max_size,
813 struct delayed_call *done)
814 {
815 return ERR_PTR(-EOPNOTSUPP);
816 }
817
818 static inline int fscrypt_symlink_getattr(const struct path *path,
819 struct kstat *stat)
820 {
821 return -EOPNOTSUPP;
822 }
823
824 static inline void fscrypt_set_ops(struct super_block *sb,
825 const struct fscrypt_operations *s_cop)
826 {
827 }
828
829 #endif /* !CONFIG_FS_ENCRYPTION */
830
831 /* inline_crypt.c */
832 #ifdef CONFIG_FS_ENCRYPTION_INLINE_CRYPT
833
834 bool __fscrypt_inode_uses_inline_crypto(const struct inode *inode);
835
836 void fscrypt_set_bio_crypt_ctx(struct bio *bio,
837 const struct inode *inode, u64 first_lblk,
838 gfp_t gfp_mask);
839
840 void fscrypt_set_bio_crypt_ctx_bh(struct bio *bio,
841 const struct buffer_head *first_bh,
842 gfp_t gfp_mask);
843
844 bool fscrypt_mergeable_bio(struct bio *bio, const struct inode *inode,
845 u64 next_lblk);
846
847 bool fscrypt_mergeable_bio_bh(struct bio *bio,
848 const struct buffer_head *next_bh);
849
850 bool fscrypt_dio_supported(struct inode *inode);
851
852 u64 fscrypt_limit_io_blocks(const struct inode *inode, u64 lblk, u64 nr_blocks);
853
854 #else /* CONFIG_FS_ENCRYPTION_INLINE_CRYPT */
855
856 static inline bool __fscrypt_inode_uses_inline_crypto(const struct inode *inode)
857 {
858 return false;
859 }
860
861 static inline void fscrypt_set_bio_crypt_ctx(struct bio *bio,
862 const struct inode *inode,
863 u64 first_lblk, gfp_t gfp_mask) { }
864
865 static inline void fscrypt_set_bio_crypt_ctx_bh(
866 struct bio *bio,
867 const struct buffer_head *first_bh,
868 gfp_t gfp_mask) { }
869
870 static inline bool fscrypt_mergeable_bio(struct bio *bio,
871 const struct inode *inode,
872 u64 next_lblk)
873 {
874 return true;
875 }
876
877 static inline bool fscrypt_mergeable_bio_bh(struct bio *bio,
878 const struct buffer_head *next_bh)
879 {
880 return true;
881 }
882
883 static inline bool fscrypt_dio_supported(struct inode *inode)
884 {
885 return !fscrypt_needs_contents_encryption(inode);
886 }
887
888 static inline u64 fscrypt_limit_io_blocks(const struct inode *inode, u64 lblk,
889 u64 nr_blocks)
890 {
891 return nr_blocks;
892 }
893 #endif /* !CONFIG_FS_ENCRYPTION_INLINE_CRYPT */
894
895 /**
896 * fscrypt_inode_uses_inline_crypto() - test whether an inode uses inline
897 * encryption
898 * @inode: an inode. If encrypted, its key must be set up.
899 *
900 * Return: true if the inode requires file contents encryption and if the
901 * encryption should be done in the block layer via blk-crypto rather
902 * than in the filesystem layer.
903 */
904 static inline bool fscrypt_inode_uses_inline_crypto(const struct inode *inode)
905 {
906 return fscrypt_needs_contents_encryption(inode) &&
907 __fscrypt_inode_uses_inline_crypto(inode);
908 }
909
910 /**
911 * fscrypt_inode_uses_fs_layer_crypto() - test whether an inode uses fs-layer
912 * encryption
913 * @inode: an inode. If encrypted, its key must be set up.
914 *
915 * Return: true if the inode requires file contents encryption and if the
916 * encryption should be done in the filesystem layer rather than in the
917 * block layer via blk-crypto.
918 */
919 static inline bool fscrypt_inode_uses_fs_layer_crypto(const struct inode *inode)
920 {
921 return fscrypt_needs_contents_encryption(inode) &&
922 !__fscrypt_inode_uses_inline_crypto(inode);
923 }
924
925 /**
926 * fscrypt_has_encryption_key() - check whether an inode has had its key set up
927 * @inode: the inode to check
928 *
929 * Return: %true if the inode has had its encryption key set up, else %false.
930 *
931 * Usually this should be preceded by fscrypt_get_encryption_info() to try to
932 * set up the key first.
933 */
934 static inline bool fscrypt_has_encryption_key(const struct inode *inode)
935 {
936 return fscrypt_get_inode_info(inode) != NULL;
937 }
938
939 /**
940 * fscrypt_prepare_link() - prepare to link an inode into a possibly-encrypted
941 * directory
942 * @old_dentry: an existing dentry for the inode being linked
943 * @dir: the target directory
944 * @dentry: negative dentry for the target filename
945 *
946 * A new link can only be added to an encrypted directory if the directory's
947 * encryption key is available --- since otherwise we'd have no way to encrypt
948 * the filename.
949 *
950 * We also verify that the link will not violate the constraint that all files
951 * in an encrypted directory tree use the same encryption policy.
952 *
953 * Return: 0 on success, -ENOKEY if the directory's encryption key is missing,
954 * -EXDEV if the link would result in an inconsistent encryption policy, or
955 * another -errno code.
956 */
957 static inline int fscrypt_prepare_link(struct dentry *old_dentry,
958 struct inode *dir,
959 struct dentry *dentry)
960 {
961 if (IS_ENCRYPTED(dir))
962 return __fscrypt_prepare_link(d_inode(old_dentry), dir, dentry);
963 return 0;
964 }
965
966 /**
967 * fscrypt_prepare_rename() - prepare for a rename between possibly-encrypted
968 * directories
969 * @old_dir: source directory
970 * @old_dentry: dentry for source file
971 * @new_dir: target directory
972 * @new_dentry: dentry for target location (may be negative unless exchanging)
973 * @flags: rename flags (we care at least about %RENAME_EXCHANGE)
974 *
975 * Prepare for ->rename() where the source and/or target directories may be
976 * encrypted. A new link can only be added to an encrypted directory if the
977 * directory's encryption key is available --- since otherwise we'd have no way
978 * to encrypt the filename. A rename to an existing name, on the other hand,
979 * *is* cryptographically possible without the key. However, we take the more
980 * conservative approach and just forbid all no-key renames.
981 *
982 * We also verify that the rename will not violate the constraint that all files
983 * in an encrypted directory tree use the same encryption policy.
984 *
985 * Return: 0 on success, -ENOKEY if an encryption key is missing, -EXDEV if the
986 * rename would cause inconsistent encryption policies, or another -errno code.
987 */
988 static inline int fscrypt_prepare_rename(struct inode *old_dir,
989 struct dentry *old_dentry,
990 struct inode *new_dir,
991 struct dentry *new_dentry,
992 unsigned int flags)
993 {
994 if (IS_ENCRYPTED(old_dir) || IS_ENCRYPTED(new_dir))
995 return __fscrypt_prepare_rename(old_dir, old_dentry,
996 new_dir, new_dentry, flags);
997 return 0;
998 }
999
1000 /**
1001 * fscrypt_prepare_lookup() - prepare to lookup a name in a possibly-encrypted
1002 * directory
1003 * @dir: directory being searched
1004 * @dentry: filename being looked up
1005 * @fname: (output) the name to use to search the on-disk directory
1006 *
1007 * Prepare for ->lookup() in a directory which may be encrypted by determining
1008 * the name that will actually be used to search the directory on-disk. If the
1009 * directory's encryption policy is supported by this kernel and its encryption
1010 * key is available, then the lookup is assumed to be by plaintext name;
1011 * otherwise, it is assumed to be by no-key name.
1012 *
1013 * This will set DCACHE_NOKEY_NAME on the dentry if the lookup is by no-key
1014 * name. In this case the filesystem must assign the dentry a dentry_operations
1015 * which contains fscrypt_d_revalidate (or contains a d_revalidate method that
1016 * calls fscrypt_d_revalidate), so that the dentry will be invalidated if the
1017 * directory's encryption key is later added.
1018 *
1019 * Return: 0 on success; -ENOENT if the directory's key is unavailable but the
1020 * filename isn't a valid no-key name, so a negative dentry should be created;
1021 * or another -errno code.
1022 */
1023 static inline int fscrypt_prepare_lookup(struct inode *dir,
1024 struct dentry *dentry,
1025 struct fscrypt_name *fname)
1026 {
1027 if (IS_ENCRYPTED(dir))
1028 return __fscrypt_prepare_lookup(dir, dentry, fname);
1029
1030 memset(fname, 0, sizeof(*fname));
1031 fname->usr_fname = &dentry->d_name;
1032 fname->disk_name.name = (unsigned char *)dentry->d_name.name;
1033 fname->disk_name.len = dentry->d_name.len;
1034
1035 fscrypt_prepare_dentry(dentry, false);
1036
1037 return 0;
1038 }
1039
1040 /**
1041 * fscrypt_prepare_readdir() - prepare to read a possibly-encrypted directory
1042 * @dir: the directory inode
1043 *
1044 * If the directory is encrypted and it doesn't already have its encryption key
1045 * set up, try to set it up so that the filenames will be listed in plaintext
1046 * form rather than in no-key form.
1047 *
1048 * Return: 0 on success; -errno on error. Note that the encryption key being
1049 * unavailable is not considered an error. It is also not an error if
1050 * the encryption policy is unsupported by this kernel; that is treated
1051 * like the key being unavailable, so that files can still be deleted.
1052 */
1053 static inline int fscrypt_prepare_readdir(struct inode *dir)
1054 {
1055 if (IS_ENCRYPTED(dir))
1056 return __fscrypt_prepare_readdir(dir);
1057 return 0;
1058 }
1059
1060 /**
1061 * fscrypt_prepare_setattr() - prepare to change a possibly-encrypted inode's
1062 * attributes
1063 * @dentry: dentry through which the inode is being changed
1064 * @attr: attributes to change
1065 *
1066 * Prepare for ->setattr() on a possibly-encrypted inode. On an encrypted file,
1067 * most attribute changes are allowed even without the encryption key. However,
1068 * without the encryption key we do have to forbid truncates. This is needed
1069 * because the size being truncated to may not be a multiple of the filesystem
1070 * block size, and in that case we'd have to decrypt the final block, zero the
1071 * portion past i_size, and re-encrypt it. (We *could* allow truncating to a
1072 * filesystem block boundary, but it's simpler to just forbid all truncates ---
1073 * and we already forbid all other contents modifications without the key.)
1074 *
1075 * Return: 0 on success, -ENOKEY if the key is missing, or another -errno code
1076 * if a problem occurred while setting up the encryption key.
1077 */
1078 static inline int fscrypt_prepare_setattr(struct dentry *dentry,
1079 struct iattr *attr)
1080 {
1081 if (IS_ENCRYPTED(d_inode(dentry)))
1082 return __fscrypt_prepare_setattr(dentry, attr);
1083 return 0;
1084 }
1085
1086 /**
1087 * fscrypt_encrypt_symlink() - encrypt the symlink target if needed
1088 * @inode: symlink inode
1089 * @target: plaintext symlink target
1090 * @len: length of @target excluding null terminator
1091 * @disk_link: (in/out) the on-disk symlink target being prepared
1092 *
1093 * If the symlink target needs to be encrypted, then this function encrypts it
1094 * into @disk_link->name. fscrypt_prepare_symlink() must have been called
1095 * previously to compute @disk_link->len. If the filesystem did not allocate a
1096 * buffer for @disk_link->name after calling fscrypt_prepare_link(), then one
1097 * will be kmalloc()'ed and the filesystem will be responsible for freeing it.
1098 *
1099 * Return: 0 on success, -errno on failure
1100 */
1101 static inline int fscrypt_encrypt_symlink(struct inode *inode,
1102 const char *target,
1103 unsigned int len,
1104 struct fscrypt_str *disk_link)
1105 {
1106 if (IS_ENCRYPTED(inode))
1107 return __fscrypt_encrypt_symlink(inode, target, len, disk_link);
1108 return 0;
1109 }
1110
1111 /* If *pagep is a bounce page, free it and set *pagep to the pagecache page */
1112 static inline void fscrypt_finalize_bounce_page(struct page **pagep)
1113 {
1114 struct page *page = *pagep;
1115
1116 if (fscrypt_is_bounce_page(page)) {
1117 *pagep = fscrypt_pagecache_page(page);
1118 fscrypt_free_bounce_page(page);
1119 }
1120 }
1121
1122 #endif /* _LINUX_FSCRYPT_H */
1123
Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.