1 /* SPDX-License-Identifier: GPL-2.0 */
3 * fscrypt.h: declarations for per-file encryption
5 * Filesystems that implement per-file encryption must include this header
8 * Copyright (C) 2015, Google, Inc.
10 * Written by Michael Halcrow, 2015.
11 * Modified by Jaegeuk Kim, 2015.
13 #ifndef _LINUX_FSCRYPT_H
14 #define _LINUX_FSCRYPT_H
18 #include <linux/slab.h>
19 #include <uapi/linux/fscrypt.h>
21 #define FS_CRYPTO_BLOCK_SIZE 16
32 const struct qstr *usr_fname;
33 struct fscrypt_str disk_name;
36 struct fscrypt_str crypto_buf;
37 bool is_ciphertext_name;
40 #define FSTR_INIT(n, l) { .name = n, .len = l }
41 #define FSTR_TO_QSTR(f) QSTR_INIT((f)->name, (f)->len)
42 #define fname_name(p) ((p)->disk_name.name)
43 #define fname_len(p) ((p)->disk_name.len)
45 /* Maximum value for the third parameter of fscrypt_operations.set_context(). */
46 #define FSCRYPT_SET_CONTEXT_MAX_SIZE 40
48 #ifdef CONFIG_FS_ENCRYPTION
50 * fscrypt superblock flags
52 #define FS_CFLG_OWN_PAGES (1U << 1)
55 * crypto operations for filesystems
57 struct fscrypt_operations {
59 const char *key_prefix;
60 int (*get_context)(struct inode *, void *, size_t);
61 int (*set_context)(struct inode *, const void *, size_t, void *);
62 bool (*dummy_context)(struct inode *);
63 bool (*empty_dir)(struct inode *);
64 unsigned int max_namelen;
72 struct work_struct work;
74 struct list_head free_list; /* Free list */
79 static inline bool fscrypt_has_encryption_key(const struct inode *inode)
81 /* pairs with cmpxchg_release() in fscrypt_get_encryption_info() */
82 return READ_ONCE(inode->i_crypt_info) != NULL;
85 static inline bool fscrypt_dummy_context_enabled(struct inode *inode)
87 return inode->i_sb->s_cop->dummy_context &&
88 inode->i_sb->s_cop->dummy_context(inode);
92 * When d_splice_alias() moves a directory's encrypted alias to its decrypted
93 * alias as a result of the encryption key being added, DCACHE_ENCRYPTED_NAME
94 * must be cleared. Note that we don't have to support arbitrary moves of this
95 * flag because fscrypt doesn't allow encrypted aliases to be the source or
96 * target of a rename().
98 static inline void fscrypt_handle_d_move(struct dentry *dentry)
100 dentry->d_flags &= ~DCACHE_ENCRYPTED_NAME;
104 * fscrypt_is_nokey_name() - test whether a dentry is a no-key name
105 * @dentry: the dentry to check
107 * This returns true if the dentry is a no-key dentry. A no-key dentry is a
108 * dentry that was created in an encrypted directory that hasn't had its
109 * encryption key added yet. Such dentries may be either positive or negative.
111 * When a filesystem is asked to create a new filename in an encrypted directory
112 * and the new filename's dentry is a no-key dentry, it must fail the operation
113 * with ENOKEY. This includes ->create(), ->mkdir(), ->mknod(), ->symlink(),
114 * ->rename(), and ->link(). (However, ->rename() and ->link() are already
115 * handled by fscrypt_prepare_rename() and fscrypt_prepare_link().)
117 * This is necessary because creating a filename requires the directory's
118 * encryption key, but just checking for the key on the directory inode during
119 * the final filesystem operation doesn't guarantee that the key was available
120 * during the preceding dentry lookup. And the key must have already been
121 * available during the dentry lookup in order for it to have been checked
122 * whether the filename already exists in the directory and for the new file's
123 * dentry not to be invalidated due to it incorrectly having the no-key flag.
125 * Return: %true if the dentry is a no-key name
127 static inline bool fscrypt_is_nokey_name(const struct dentry *dentry)
129 return dentry->d_flags & DCACHE_ENCRYPTED_NAME;
133 extern void fscrypt_enqueue_decrypt_work(struct work_struct *);
134 extern struct fscrypt_ctx *fscrypt_get_ctx(gfp_t);
135 extern void fscrypt_release_ctx(struct fscrypt_ctx *);
137 extern struct page *fscrypt_encrypt_pagecache_blocks(struct page *page,
141 extern int fscrypt_encrypt_block_inplace(const struct inode *inode,
142 struct page *page, unsigned int len,
143 unsigned int offs, u64 lblk_num,
146 extern int fscrypt_decrypt_pagecache_blocks(struct page *page, unsigned int len,
148 extern int fscrypt_decrypt_block_inplace(const struct inode *inode,
149 struct page *page, unsigned int len,
150 unsigned int offs, u64 lblk_num);
152 static inline bool fscrypt_is_bounce_page(struct page *page)
154 return page->mapping == NULL;
157 static inline struct page *fscrypt_pagecache_page(struct page *bounce_page)
159 return (struct page *)page_private(bounce_page);
162 extern void fscrypt_free_bounce_page(struct page *bounce_page);
165 extern int fscrypt_ioctl_set_policy(struct file *, const void __user *);
166 extern int fscrypt_ioctl_get_policy(struct file *, void __user *);
167 extern int fscrypt_ioctl_get_policy_ex(struct file *, void __user *);
168 extern int fscrypt_has_permitted_context(struct inode *, struct inode *);
169 extern int fscrypt_inherit_context(struct inode *, struct inode *,
172 extern void fscrypt_sb_free(struct super_block *sb);
173 extern int fscrypt_ioctl_add_key(struct file *filp, void __user *arg);
174 extern int fscrypt_ioctl_remove_key(struct file *filp, void __user *arg);
175 extern int fscrypt_ioctl_remove_key_all_users(struct file *filp,
177 extern int fscrypt_ioctl_get_key_status(struct file *filp, void __user *arg);
180 extern int fscrypt_get_encryption_info(struct inode *);
181 extern void fscrypt_put_encryption_info(struct inode *);
182 extern void fscrypt_free_inode(struct inode *);
183 extern int fscrypt_drop_inode(struct inode *inode);
186 extern int fscrypt_setup_filename(struct inode *, const struct qstr *,
187 int lookup, struct fscrypt_name *);
189 static inline void fscrypt_free_filename(struct fscrypt_name *fname)
191 kfree(fname->crypto_buf.name);
194 extern int fscrypt_fname_alloc_buffer(const struct inode *, u32,
195 struct fscrypt_str *);
196 extern void fscrypt_fname_free_buffer(struct fscrypt_str *);
197 extern int fscrypt_fname_disk_to_usr(struct inode *, u32, u32,
198 const struct fscrypt_str *, struct fscrypt_str *);
200 #define FSCRYPT_FNAME_MAX_UNDIGESTED_SIZE 32
202 /* Extracts the second-to-last ciphertext block; see explanation below */
203 #define FSCRYPT_FNAME_DIGEST(name, len) \
204 ((name) + round_down((len) - FS_CRYPTO_BLOCK_SIZE - 1, \
205 FS_CRYPTO_BLOCK_SIZE))
207 #define FSCRYPT_FNAME_DIGEST_SIZE FS_CRYPTO_BLOCK_SIZE
210 * fscrypt_digested_name - alternate identifier for an on-disk filename
212 * When userspace lists an encrypted directory without access to the key,
213 * filenames whose ciphertext is longer than FSCRYPT_FNAME_MAX_UNDIGESTED_SIZE
214 * bytes are shown in this abbreviated form (base64-encoded) rather than as the
215 * full ciphertext (base64-encoded). This is necessary to allow supporting
216 * filenames up to NAME_MAX bytes, since base64 encoding expands the length.
218 * To make it possible for filesystems to still find the correct directory entry
219 * despite not knowing the full on-disk name, we encode any filesystem-specific
220 * 'hash' and/or 'minor_hash' which the filesystem may need for its lookups,
221 * followed by the second-to-last ciphertext block of the filename. Due to the
222 * use of the CBC-CTS encryption mode, the second-to-last ciphertext block
223 * depends on the full plaintext. (Note that ciphertext stealing causes the
224 * last two blocks to appear "flipped".) This makes accidental collisions very
225 * unlikely: just a 1 in 2^128 chance for two filenames to collide even if they
226 * share the same filesystem-specific hashes.
228 * However, this scheme isn't immune to intentional collisions, which can be
229 * created by anyone able to create arbitrary plaintext filenames and view them
230 * without the key. Making the "digest" be a real cryptographic hash like
231 * SHA-256 over the full ciphertext would prevent this, although it would be
232 * less efficient and harder to implement, especially since the filesystem would
233 * need to calculate it for each directory entry examined during a search.
235 struct fscrypt_digested_name {
238 u8 digest[FSCRYPT_FNAME_DIGEST_SIZE];
242 * fscrypt_match_name() - test whether the given name matches a directory entry
243 * @fname: the name being searched for
244 * @de_name: the name from the directory entry
245 * @de_name_len: the length of @de_name in bytes
247 * Normally @fname->disk_name will be set, and in that case we simply compare
248 * that to the name stored in the directory entry. The only exception is that
249 * if we don't have the key for an encrypted directory and a filename in it is
250 * very long, then we won't have the full disk_name and we'll instead need to
251 * match against the fscrypt_digested_name.
253 * Return: %true if the name matches, otherwise %false.
255 static inline bool fscrypt_match_name(const struct fscrypt_name *fname,
256 const u8 *de_name, u32 de_name_len)
258 if (unlikely(!fname->disk_name.name)) {
259 const struct fscrypt_digested_name *n =
260 (const void *)fname->crypto_buf.name;
261 if (WARN_ON_ONCE(fname->usr_fname->name[0] != '_'))
263 if (de_name_len <= FSCRYPT_FNAME_MAX_UNDIGESTED_SIZE)
265 return !memcmp(FSCRYPT_FNAME_DIGEST(de_name, de_name_len),
266 n->digest, FSCRYPT_FNAME_DIGEST_SIZE);
269 if (de_name_len != fname->disk_name.len)
271 return !memcmp(de_name, fname->disk_name.name, fname->disk_name.len);
275 extern void fscrypt_decrypt_bio(struct bio *);
276 extern void fscrypt_enqueue_decrypt_bio(struct fscrypt_ctx *ctx,
278 extern int fscrypt_zeroout_range(const struct inode *, pgoff_t, sector_t,
282 extern int fscrypt_file_open(struct inode *inode, struct file *filp);
283 extern int __fscrypt_prepare_link(struct inode *inode, struct inode *dir,
284 struct dentry *dentry);
285 extern int __fscrypt_prepare_rename(struct inode *old_dir,
286 struct dentry *old_dentry,
287 struct inode *new_dir,
288 struct dentry *new_dentry,
290 extern int __fscrypt_prepare_lookup(struct inode *dir, struct dentry *dentry,
291 struct fscrypt_name *fname);
292 extern int __fscrypt_prepare_symlink(struct inode *dir, unsigned int len,
293 unsigned int max_len,
294 struct fscrypt_str *disk_link);
295 extern int __fscrypt_encrypt_symlink(struct inode *inode, const char *target,
297 struct fscrypt_str *disk_link);
298 extern const char *fscrypt_get_symlink(struct inode *inode, const void *caddr,
299 unsigned int max_size,
300 struct delayed_call *done);
301 int fscrypt_symlink_getattr(const struct path *path, struct kstat *stat);
302 static inline void fscrypt_set_ops(struct super_block *sb,
303 const struct fscrypt_operations *s_cop)
307 #else /* !CONFIG_FS_ENCRYPTION */
309 static inline bool fscrypt_has_encryption_key(const struct inode *inode)
314 static inline bool fscrypt_dummy_context_enabled(struct inode *inode)
319 static inline void fscrypt_handle_d_move(struct dentry *dentry)
323 static inline bool fscrypt_is_nokey_name(const struct dentry *dentry)
329 static inline void fscrypt_enqueue_decrypt_work(struct work_struct *work)
333 static inline struct fscrypt_ctx *fscrypt_get_ctx(gfp_t gfp_flags)
335 return ERR_PTR(-EOPNOTSUPP);
338 static inline void fscrypt_release_ctx(struct fscrypt_ctx *ctx)
343 static inline struct page *fscrypt_encrypt_pagecache_blocks(struct page *page,
348 return ERR_PTR(-EOPNOTSUPP);
351 static inline int fscrypt_encrypt_block_inplace(const struct inode *inode,
354 unsigned int offs, u64 lblk_num,
360 static inline int fscrypt_decrypt_pagecache_blocks(struct page *page,
367 static inline int fscrypt_decrypt_block_inplace(const struct inode *inode,
370 unsigned int offs, u64 lblk_num)
375 static inline bool fscrypt_is_bounce_page(struct page *page)
380 static inline struct page *fscrypt_pagecache_page(struct page *bounce_page)
383 return ERR_PTR(-EINVAL);
386 static inline void fscrypt_free_bounce_page(struct page *bounce_page)
391 static inline int fscrypt_ioctl_set_policy(struct file *filp,
392 const void __user *arg)
397 static inline int fscrypt_ioctl_get_policy(struct file *filp, void __user *arg)
402 static inline int fscrypt_ioctl_get_policy_ex(struct file *filp,
408 static inline int fscrypt_has_permitted_context(struct inode *parent,
414 static inline int fscrypt_inherit_context(struct inode *parent,
416 void *fs_data, bool preload)
422 static inline void fscrypt_sb_free(struct super_block *sb)
426 static inline int fscrypt_ioctl_add_key(struct file *filp, void __user *arg)
431 static inline int fscrypt_ioctl_remove_key(struct file *filp, void __user *arg)
436 static inline int fscrypt_ioctl_remove_key_all_users(struct file *filp,
442 static inline int fscrypt_ioctl_get_key_status(struct file *filp,
449 static inline int fscrypt_get_encryption_info(struct inode *inode)
454 static inline void fscrypt_put_encryption_info(struct inode *inode)
459 static inline void fscrypt_free_inode(struct inode *inode)
463 static inline int fscrypt_drop_inode(struct inode *inode)
469 static inline int fscrypt_setup_filename(struct inode *dir,
470 const struct qstr *iname,
471 int lookup, struct fscrypt_name *fname)
473 if (IS_ENCRYPTED(dir))
476 memset(fname, 0, sizeof(*fname));
477 fname->usr_fname = iname;
478 fname->disk_name.name = (unsigned char *)iname->name;
479 fname->disk_name.len = iname->len;
483 static inline void fscrypt_free_filename(struct fscrypt_name *fname)
488 static inline int fscrypt_fname_alloc_buffer(const struct inode *inode,
489 u32 max_encrypted_len,
490 struct fscrypt_str *crypto_str)
495 static inline void fscrypt_fname_free_buffer(struct fscrypt_str *crypto_str)
500 static inline int fscrypt_fname_disk_to_usr(struct inode *inode,
501 u32 hash, u32 minor_hash,
502 const struct fscrypt_str *iname,
503 struct fscrypt_str *oname)
508 static inline bool fscrypt_match_name(const struct fscrypt_name *fname,
509 const u8 *de_name, u32 de_name_len)
511 /* Encryption support disabled; use standard comparison */
512 if (de_name_len != fname->disk_name.len)
514 return !memcmp(de_name, fname->disk_name.name, fname->disk_name.len);
518 static inline void fscrypt_decrypt_bio(struct bio *bio)
522 static inline void fscrypt_enqueue_decrypt_bio(struct fscrypt_ctx *ctx,
527 static inline int fscrypt_zeroout_range(const struct inode *inode, pgoff_t lblk,
528 sector_t pblk, unsigned int len)
535 static inline int fscrypt_file_open(struct inode *inode, struct file *filp)
537 if (IS_ENCRYPTED(inode))
542 static inline int __fscrypt_prepare_link(struct inode *inode, struct inode *dir,
543 struct dentry *dentry)
548 static inline int __fscrypt_prepare_rename(struct inode *old_dir,
549 struct dentry *old_dentry,
550 struct inode *new_dir,
551 struct dentry *new_dentry,
557 static inline int __fscrypt_prepare_lookup(struct inode *dir,
558 struct dentry *dentry,
559 struct fscrypt_name *fname)
564 static inline int __fscrypt_prepare_symlink(struct inode *dir,
566 unsigned int max_len,
567 struct fscrypt_str *disk_link)
573 static inline int __fscrypt_encrypt_symlink(struct inode *inode,
576 struct fscrypt_str *disk_link)
581 static inline const char *fscrypt_get_symlink(struct inode *inode,
583 unsigned int max_size,
584 struct delayed_call *done)
586 return ERR_PTR(-EOPNOTSUPP);
589 static inline int fscrypt_symlink_getattr(const struct path *path,
595 static inline void fscrypt_set_ops(struct super_block *sb,
596 const struct fscrypt_operations *s_cop)
600 #endif /* !CONFIG_FS_ENCRYPTION */
603 * fscrypt_require_key - require an inode's encryption key
604 * @inode: the inode we need the key for
606 * If the inode is encrypted, set up its encryption key if not already done.
607 * Then require that the key be present and return -ENOKEY otherwise.
609 * No locks are needed, and the key will live as long as the struct inode --- so
610 * it won't go away from under you.
612 * Return: 0 on success, -ENOKEY if the key is missing, or another -errno code
613 * if a problem occurred while setting up the encryption key.
615 static inline int fscrypt_require_key(struct inode *inode)
617 if (IS_ENCRYPTED(inode)) {
618 int err = fscrypt_get_encryption_info(inode);
622 if (!fscrypt_has_encryption_key(inode))
629 * fscrypt_prepare_link - prepare to link an inode into a possibly-encrypted directory
630 * @old_dentry: an existing dentry for the inode being linked
631 * @dir: the target directory
632 * @dentry: negative dentry for the target filename
634 * A new link can only be added to an encrypted directory if the directory's
635 * encryption key is available --- since otherwise we'd have no way to encrypt
636 * the filename. Therefore, we first set up the directory's encryption key (if
637 * not already done) and return an error if it's unavailable.
639 * We also verify that the link will not violate the constraint that all files
640 * in an encrypted directory tree use the same encryption policy.
642 * Return: 0 on success, -ENOKEY if the directory's encryption key is missing,
643 * -EXDEV if the link would result in an inconsistent encryption policy, or
644 * another -errno code.
646 static inline int fscrypt_prepare_link(struct dentry *old_dentry,
648 struct dentry *dentry)
650 if (IS_ENCRYPTED(dir))
651 return __fscrypt_prepare_link(d_inode(old_dentry), dir, dentry);
656 * fscrypt_prepare_rename - prepare for a rename between possibly-encrypted directories
657 * @old_dir: source directory
658 * @old_dentry: dentry for source file
659 * @new_dir: target directory
660 * @new_dentry: dentry for target location (may be negative unless exchanging)
661 * @flags: rename flags (we care at least about %RENAME_EXCHANGE)
663 * Prepare for ->rename() where the source and/or target directories may be
664 * encrypted. A new link can only be added to an encrypted directory if the
665 * directory's encryption key is available --- since otherwise we'd have no way
666 * to encrypt the filename. A rename to an existing name, on the other hand,
667 * *is* cryptographically possible without the key. However, we take the more
668 * conservative approach and just forbid all no-key renames.
670 * We also verify that the rename will not violate the constraint that all files
671 * in an encrypted directory tree use the same encryption policy.
673 * Return: 0 on success, -ENOKEY if an encryption key is missing, -EXDEV if the
674 * rename would cause inconsistent encryption policies, or another -errno code.
676 static inline int fscrypt_prepare_rename(struct inode *old_dir,
677 struct dentry *old_dentry,
678 struct inode *new_dir,
679 struct dentry *new_dentry,
682 if (IS_ENCRYPTED(old_dir) || IS_ENCRYPTED(new_dir))
683 return __fscrypt_prepare_rename(old_dir, old_dentry,
684 new_dir, new_dentry, flags);
689 * fscrypt_prepare_lookup - prepare to lookup a name in a possibly-encrypted directory
690 * @dir: directory being searched
691 * @dentry: filename being looked up
692 * @fname: (output) the name to use to search the on-disk directory
694 * Prepare for ->lookup() in a directory which may be encrypted by determining
695 * the name that will actually be used to search the directory on-disk. Lookups
696 * can be done with or without the directory's encryption key; without the key,
697 * filenames are presented in encrypted form. Therefore, we'll try to set up
698 * the directory's encryption key, but even without it the lookup can continue.
700 * This also installs a custom ->d_revalidate() method which will invalidate the
701 * dentry if it was created without the key and the key is later added.
703 * Return: 0 on success; -ENOENT if key is unavailable but the filename isn't a
704 * correctly formed encoded ciphertext name, so a negative dentry should be
705 * created; or another -errno code.
707 static inline int fscrypt_prepare_lookup(struct inode *dir,
708 struct dentry *dentry,
709 struct fscrypt_name *fname)
711 if (IS_ENCRYPTED(dir))
712 return __fscrypt_prepare_lookup(dir, dentry, fname);
714 memset(fname, 0, sizeof(*fname));
715 fname->usr_fname = &dentry->d_name;
716 fname->disk_name.name = (unsigned char *)dentry->d_name.name;
717 fname->disk_name.len = dentry->d_name.len;
722 * fscrypt_prepare_setattr - prepare to change a possibly-encrypted inode's attributes
723 * @dentry: dentry through which the inode is being changed
724 * @attr: attributes to change
726 * Prepare for ->setattr() on a possibly-encrypted inode. On an encrypted file,
727 * most attribute changes are allowed even without the encryption key. However,
728 * without the encryption key we do have to forbid truncates. This is needed
729 * because the size being truncated to may not be a multiple of the filesystem
730 * block size, and in that case we'd have to decrypt the final block, zero the
731 * portion past i_size, and re-encrypt it. (We *could* allow truncating to a
732 * filesystem block boundary, but it's simpler to just forbid all truncates ---
733 * and we already forbid all other contents modifications without the key.)
735 * Return: 0 on success, -ENOKEY if the key is missing, or another -errno code
736 * if a problem occurred while setting up the encryption key.
738 static inline int fscrypt_prepare_setattr(struct dentry *dentry,
741 if (attr->ia_valid & ATTR_SIZE)
742 return fscrypt_require_key(d_inode(dentry));
747 * fscrypt_prepare_symlink - prepare to create a possibly-encrypted symlink
748 * @dir: directory in which the symlink is being created
749 * @target: plaintext symlink target
750 * @len: length of @target excluding null terminator
751 * @max_len: space the filesystem has available to store the symlink target
752 * @disk_link: (out) the on-disk symlink target being prepared
754 * This function computes the size the symlink target will require on-disk,
755 * stores it in @disk_link->len, and validates it against @max_len. An
756 * encrypted symlink may be longer than the original.
758 * Additionally, @disk_link->name is set to @target if the symlink will be
759 * unencrypted, but left NULL if the symlink will be encrypted. For encrypted
760 * symlinks, the filesystem must call fscrypt_encrypt_symlink() to create the
761 * on-disk target later. (The reason for the two-step process is that some
762 * filesystems need to know the size of the symlink target before creating the
763 * inode, e.g. to determine whether it will be a "fast" or "slow" symlink.)
765 * Return: 0 on success, -ENAMETOOLONG if the symlink target is too long,
766 * -ENOKEY if the encryption key is missing, or another -errno code if a problem
767 * occurred while setting up the encryption key.
769 static inline int fscrypt_prepare_symlink(struct inode *dir,
772 unsigned int max_len,
773 struct fscrypt_str *disk_link)
775 if (IS_ENCRYPTED(dir) || fscrypt_dummy_context_enabled(dir))
776 return __fscrypt_prepare_symlink(dir, len, max_len, disk_link);
778 disk_link->name = (unsigned char *)target;
779 disk_link->len = len + 1;
780 if (disk_link->len > max_len)
781 return -ENAMETOOLONG;
786 * fscrypt_encrypt_symlink - encrypt the symlink target if needed
787 * @inode: symlink inode
788 * @target: plaintext symlink target
789 * @len: length of @target excluding null terminator
790 * @disk_link: (in/out) the on-disk symlink target being prepared
792 * If the symlink target needs to be encrypted, then this function encrypts it
793 * into @disk_link->name. fscrypt_prepare_symlink() must have been called
794 * previously to compute @disk_link->len. If the filesystem did not allocate a
795 * buffer for @disk_link->name after calling fscrypt_prepare_link(), then one
796 * will be kmalloc()'ed and the filesystem will be responsible for freeing it.
798 * Return: 0 on success, -errno on failure
800 static inline int fscrypt_encrypt_symlink(struct inode *inode,
803 struct fscrypt_str *disk_link)
805 if (IS_ENCRYPTED(inode))
806 return __fscrypt_encrypt_symlink(inode, target, len, disk_link);
810 /* If *pagep is a bounce page, free it and set *pagep to the pagecache page */
811 static inline void fscrypt_finalize_bounce_page(struct page **pagep)
813 struct page *page = *pagep;
815 if (fscrypt_is_bounce_page(page)) {
816 *pagep = fscrypt_pagecache_page(page);
817 fscrypt_free_bounce_page(page);
821 #endif /* _LINUX_FSCRYPT_H */