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
33 const struct qstr *usr_fname;
34 struct fscrypt_str disk_name;
37 struct fscrypt_str crypto_buf;
41 #define FSTR_INIT(n, l) { .name = n, .len = l }
42 #define FSTR_TO_QSTR(f) QSTR_INIT((f)->name, (f)->len)
43 #define fname_name(p) ((p)->disk_name.name)
44 #define fname_len(p) ((p)->disk_name.len)
46 /* Maximum value for the third parameter of fscrypt_operations.set_context(). */
47 #define FSCRYPT_SET_CONTEXT_MAX_SIZE 40
49 #ifdef CONFIG_FS_ENCRYPTION
51 * fscrypt superblock flags
53 #define FS_CFLG_OWN_PAGES (1U << 1)
56 * crypto operations for filesystems
58 struct fscrypt_operations {
60 const char *key_prefix;
61 int (*get_context)(struct inode *inode, void *ctx, size_t len);
62 int (*set_context)(struct inode *inode, const void *ctx, size_t len,
64 const union fscrypt_policy *(*get_dummy_policy)(struct super_block *sb);
65 bool (*empty_dir)(struct inode *inode);
66 unsigned int max_namelen;
67 bool (*has_stable_inodes)(struct super_block *sb);
68 void (*get_ino_and_lblk_bits)(struct super_block *sb,
69 int *ino_bits_ret, int *lblk_bits_ret);
70 int (*get_num_devices)(struct super_block *sb);
71 void (*get_devices)(struct super_block *sb,
72 struct request_queue **devs);
75 static inline struct fscrypt_info *fscrypt_get_info(const struct inode *inode)
78 * Pairs with the cmpxchg_release() in fscrypt_get_encryption_info().
79 * I.e., another task may publish ->i_crypt_info concurrently, executing
80 * a RELEASE barrier. We need to use smp_load_acquire() here to safely
81 * ACQUIRE the memory the other task published.
83 return smp_load_acquire(&inode->i_crypt_info);
87 * fscrypt_needs_contents_encryption() - check whether an inode needs
89 * @inode: the inode to check
91 * Return: %true iff the inode is an encrypted regular file and the kernel was
92 * built with fscrypt support.
94 * If you need to know whether the encrypt bit is set even when the kernel was
95 * built without fscrypt support, you must use IS_ENCRYPTED() directly instead.
97 static inline bool fscrypt_needs_contents_encryption(const struct inode *inode)
99 return IS_ENCRYPTED(inode) && S_ISREG(inode->i_mode);
103 * When d_splice_alias() moves a directory's no-key alias to its plaintext alias
104 * as a result of the encryption key being added, DCACHE_NOKEY_NAME must be
105 * cleared. Note that we don't have to support arbitrary moves of this flag
106 * because fscrypt doesn't allow no-key names to be the source or target of a
109 static inline void fscrypt_handle_d_move(struct dentry *dentry)
111 dentry->d_flags &= ~DCACHE_NOKEY_NAME;
115 void fscrypt_enqueue_decrypt_work(struct work_struct *);
117 struct page *fscrypt_encrypt_pagecache_blocks(struct page *page,
121 int fscrypt_encrypt_block_inplace(const struct inode *inode, struct page *page,
122 unsigned int len, unsigned int offs,
123 u64 lblk_num, gfp_t gfp_flags);
125 int fscrypt_decrypt_pagecache_blocks(struct page *page, unsigned int len,
127 int fscrypt_decrypt_block_inplace(const struct inode *inode, struct page *page,
128 unsigned int len, unsigned int offs,
131 static inline bool fscrypt_is_bounce_page(struct page *page)
133 return page->mapping == NULL;
136 static inline struct page *fscrypt_pagecache_page(struct page *bounce_page)
138 return (struct page *)page_private(bounce_page);
141 void fscrypt_free_bounce_page(struct page *bounce_page);
144 int fscrypt_ioctl_set_policy(struct file *filp, const void __user *arg);
145 int fscrypt_ioctl_get_policy(struct file *filp, void __user *arg);
146 int fscrypt_ioctl_get_policy_ex(struct file *filp, void __user *arg);
147 int fscrypt_ioctl_get_nonce(struct file *filp, void __user *arg);
148 int fscrypt_has_permitted_context(struct inode *parent, struct inode *child);
149 int fscrypt_set_context(struct inode *inode, void *fs_data);
151 struct fscrypt_dummy_policy {
152 const union fscrypt_policy *policy;
155 int fscrypt_set_test_dummy_encryption(struct super_block *sb, const char *arg,
156 struct fscrypt_dummy_policy *dummy_policy);
157 void fscrypt_show_test_dummy_encryption(struct seq_file *seq, char sep,
158 struct super_block *sb);
160 fscrypt_free_dummy_policy(struct fscrypt_dummy_policy *dummy_policy)
162 kfree(dummy_policy->policy);
163 dummy_policy->policy = NULL;
167 void fscrypt_sb_free(struct super_block *sb);
168 int fscrypt_ioctl_add_key(struct file *filp, void __user *arg);
169 int fscrypt_ioctl_remove_key(struct file *filp, void __user *arg);
170 int fscrypt_ioctl_remove_key_all_users(struct file *filp, void __user *arg);
171 int fscrypt_ioctl_get_key_status(struct file *filp, void __user *arg);
174 int fscrypt_get_encryption_info(struct inode *inode);
175 int fscrypt_prepare_new_inode(struct inode *dir, struct inode *inode,
177 void fscrypt_put_encryption_info(struct inode *inode);
178 void fscrypt_free_inode(struct inode *inode);
179 int fscrypt_drop_inode(struct inode *inode);
182 int fscrypt_setup_filename(struct inode *inode, const struct qstr *iname,
183 int lookup, struct fscrypt_name *fname);
185 static inline void fscrypt_free_filename(struct fscrypt_name *fname)
187 kfree(fname->crypto_buf.name);
190 int fscrypt_fname_alloc_buffer(u32 max_encrypted_len,
191 struct fscrypt_str *crypto_str);
192 void fscrypt_fname_free_buffer(struct fscrypt_str *crypto_str);
193 int fscrypt_fname_disk_to_usr(const struct inode *inode,
194 u32 hash, u32 minor_hash,
195 const struct fscrypt_str *iname,
196 struct fscrypt_str *oname);
197 bool fscrypt_match_name(const struct fscrypt_name *fname,
198 const u8 *de_name, u32 de_name_len);
199 u64 fscrypt_fname_siphash(const struct inode *dir, const struct qstr *name);
200 int fscrypt_d_revalidate(struct dentry *dentry, unsigned int flags);
203 void fscrypt_decrypt_bio(struct bio *bio);
204 int fscrypt_zeroout_range(const struct inode *inode, pgoff_t lblk,
205 sector_t pblk, unsigned int len);
208 int fscrypt_file_open(struct inode *inode, struct file *filp);
209 int __fscrypt_prepare_link(struct inode *inode, struct inode *dir,
210 struct dentry *dentry);
211 int __fscrypt_prepare_rename(struct inode *old_dir, struct dentry *old_dentry,
212 struct inode *new_dir, struct dentry *new_dentry,
214 int __fscrypt_prepare_lookup(struct inode *dir, struct dentry *dentry,
215 struct fscrypt_name *fname);
216 int fscrypt_prepare_setflags(struct inode *inode,
217 unsigned int oldflags, unsigned int flags);
218 int fscrypt_prepare_symlink(struct inode *dir, const char *target,
219 unsigned int len, unsigned int max_len,
220 struct fscrypt_str *disk_link);
221 int __fscrypt_encrypt_symlink(struct inode *inode, const char *target,
222 unsigned int len, struct fscrypt_str *disk_link);
223 const char *fscrypt_get_symlink(struct inode *inode, const void *caddr,
224 unsigned int max_size,
225 struct delayed_call *done);
226 static inline void fscrypt_set_ops(struct super_block *sb,
227 const struct fscrypt_operations *s_cop)
231 #else /* !CONFIG_FS_ENCRYPTION */
233 static inline struct fscrypt_info *fscrypt_get_info(const struct inode *inode)
238 static inline bool fscrypt_needs_contents_encryption(const struct inode *inode)
243 static inline void fscrypt_handle_d_move(struct dentry *dentry)
248 static inline void fscrypt_enqueue_decrypt_work(struct work_struct *work)
252 static inline struct page *fscrypt_encrypt_pagecache_blocks(struct page *page,
257 return ERR_PTR(-EOPNOTSUPP);
260 static inline int fscrypt_encrypt_block_inplace(const struct inode *inode,
263 unsigned int offs, u64 lblk_num,
269 static inline int fscrypt_decrypt_pagecache_blocks(struct page *page,
276 static inline int fscrypt_decrypt_block_inplace(const struct inode *inode,
279 unsigned int offs, u64 lblk_num)
284 static inline bool fscrypt_is_bounce_page(struct page *page)
289 static inline struct page *fscrypt_pagecache_page(struct page *bounce_page)
292 return ERR_PTR(-EINVAL);
295 static inline void fscrypt_free_bounce_page(struct page *bounce_page)
300 static inline int fscrypt_ioctl_set_policy(struct file *filp,
301 const void __user *arg)
306 static inline int fscrypt_ioctl_get_policy(struct file *filp, void __user *arg)
311 static inline int fscrypt_ioctl_get_policy_ex(struct file *filp,
317 static inline int fscrypt_ioctl_get_nonce(struct file *filp, void __user *arg)
322 static inline int fscrypt_has_permitted_context(struct inode *parent,
328 static inline int fscrypt_set_context(struct inode *inode, void *fs_data)
333 struct fscrypt_dummy_policy {
336 static inline void fscrypt_show_test_dummy_encryption(struct seq_file *seq,
338 struct super_block *sb)
343 fscrypt_free_dummy_policy(struct fscrypt_dummy_policy *dummy_policy)
348 static inline void fscrypt_sb_free(struct super_block *sb)
352 static inline int fscrypt_ioctl_add_key(struct file *filp, void __user *arg)
357 static inline int fscrypt_ioctl_remove_key(struct file *filp, void __user *arg)
362 static inline int fscrypt_ioctl_remove_key_all_users(struct file *filp,
368 static inline int fscrypt_ioctl_get_key_status(struct file *filp,
375 static inline int fscrypt_get_encryption_info(struct inode *inode)
380 static inline int fscrypt_prepare_new_inode(struct inode *dir,
384 if (IS_ENCRYPTED(dir))
389 static inline void fscrypt_put_encryption_info(struct inode *inode)
394 static inline void fscrypt_free_inode(struct inode *inode)
398 static inline int fscrypt_drop_inode(struct inode *inode)
404 static inline int fscrypt_setup_filename(struct inode *dir,
405 const struct qstr *iname,
406 int lookup, struct fscrypt_name *fname)
408 if (IS_ENCRYPTED(dir))
411 memset(fname, 0, sizeof(*fname));
412 fname->usr_fname = iname;
413 fname->disk_name.name = (unsigned char *)iname->name;
414 fname->disk_name.len = iname->len;
418 static inline void fscrypt_free_filename(struct fscrypt_name *fname)
423 static inline int fscrypt_fname_alloc_buffer(u32 max_encrypted_len,
424 struct fscrypt_str *crypto_str)
429 static inline void fscrypt_fname_free_buffer(struct fscrypt_str *crypto_str)
434 static inline int fscrypt_fname_disk_to_usr(const struct inode *inode,
435 u32 hash, u32 minor_hash,
436 const struct fscrypt_str *iname,
437 struct fscrypt_str *oname)
442 static inline bool fscrypt_match_name(const struct fscrypt_name *fname,
443 const u8 *de_name, u32 de_name_len)
445 /* Encryption support disabled; use standard comparison */
446 if (de_name_len != fname->disk_name.len)
448 return !memcmp(de_name, fname->disk_name.name, fname->disk_name.len);
451 static inline u64 fscrypt_fname_siphash(const struct inode *dir,
452 const struct qstr *name)
458 static inline int fscrypt_d_revalidate(struct dentry *dentry,
465 static inline void fscrypt_decrypt_bio(struct bio *bio)
469 static inline int fscrypt_zeroout_range(const struct inode *inode, pgoff_t lblk,
470 sector_t pblk, unsigned int len)
477 static inline int fscrypt_file_open(struct inode *inode, struct file *filp)
479 if (IS_ENCRYPTED(inode))
484 static inline int __fscrypt_prepare_link(struct inode *inode, struct inode *dir,
485 struct dentry *dentry)
490 static inline int __fscrypt_prepare_rename(struct inode *old_dir,
491 struct dentry *old_dentry,
492 struct inode *new_dir,
493 struct dentry *new_dentry,
499 static inline int __fscrypt_prepare_lookup(struct inode *dir,
500 struct dentry *dentry,
501 struct fscrypt_name *fname)
506 static inline int fscrypt_prepare_setflags(struct inode *inode,
507 unsigned int oldflags,
513 static inline int fscrypt_prepare_symlink(struct inode *dir,
516 unsigned int max_len,
517 struct fscrypt_str *disk_link)
519 if (IS_ENCRYPTED(dir))
521 disk_link->name = (unsigned char *)target;
522 disk_link->len = len + 1;
523 if (disk_link->len > max_len)
524 return -ENAMETOOLONG;
528 static inline int __fscrypt_encrypt_symlink(struct inode *inode,
531 struct fscrypt_str *disk_link)
536 static inline const char *fscrypt_get_symlink(struct inode *inode,
538 unsigned int max_size,
539 struct delayed_call *done)
541 return ERR_PTR(-EOPNOTSUPP);
544 static inline void fscrypt_set_ops(struct super_block *sb,
545 const struct fscrypt_operations *s_cop)
549 #endif /* !CONFIG_FS_ENCRYPTION */
552 #ifdef CONFIG_FS_ENCRYPTION_INLINE_CRYPT
554 bool __fscrypt_inode_uses_inline_crypto(const struct inode *inode);
556 void fscrypt_set_bio_crypt_ctx(struct bio *bio,
557 const struct inode *inode, u64 first_lblk,
560 void fscrypt_set_bio_crypt_ctx_bh(struct bio *bio,
561 const struct buffer_head *first_bh,
564 bool fscrypt_mergeable_bio(struct bio *bio, const struct inode *inode,
567 bool fscrypt_mergeable_bio_bh(struct bio *bio,
568 const struct buffer_head *next_bh);
570 #else /* CONFIG_FS_ENCRYPTION_INLINE_CRYPT */
572 static inline bool __fscrypt_inode_uses_inline_crypto(const struct inode *inode)
577 static inline void fscrypt_set_bio_crypt_ctx(struct bio *bio,
578 const struct inode *inode,
579 u64 first_lblk, gfp_t gfp_mask) { }
581 static inline void fscrypt_set_bio_crypt_ctx_bh(
583 const struct buffer_head *first_bh,
586 static inline bool fscrypt_mergeable_bio(struct bio *bio,
587 const struct inode *inode,
593 static inline bool fscrypt_mergeable_bio_bh(struct bio *bio,
594 const struct buffer_head *next_bh)
598 #endif /* !CONFIG_FS_ENCRYPTION_INLINE_CRYPT */
601 * fscrypt_inode_uses_inline_crypto() - test whether an inode uses inline
603 * @inode: an inode. If encrypted, its key must be set up.
605 * Return: true if the inode requires file contents encryption and if the
606 * encryption should be done in the block layer via blk-crypto rather
607 * than in the filesystem layer.
609 static inline bool fscrypt_inode_uses_inline_crypto(const struct inode *inode)
611 return fscrypt_needs_contents_encryption(inode) &&
612 __fscrypt_inode_uses_inline_crypto(inode);
616 * fscrypt_inode_uses_fs_layer_crypto() - test whether an inode uses fs-layer
618 * @inode: an inode. If encrypted, its key must be set up.
620 * Return: true if the inode requires file contents encryption and if the
621 * encryption should be done in the filesystem layer rather than in the
622 * block layer via blk-crypto.
624 static inline bool fscrypt_inode_uses_fs_layer_crypto(const struct inode *inode)
626 return fscrypt_needs_contents_encryption(inode) &&
627 !__fscrypt_inode_uses_inline_crypto(inode);
631 * fscrypt_has_encryption_key() - check whether an inode has had its key set up
632 * @inode: the inode to check
634 * Return: %true if the inode has had its encryption key set up, else %false.
636 * Usually this should be preceded by fscrypt_get_encryption_info() to try to
637 * set up the key first.
639 static inline bool fscrypt_has_encryption_key(const struct inode *inode)
641 return fscrypt_get_info(inode) != NULL;
645 * fscrypt_require_key() - require an inode's encryption key
646 * @inode: the inode we need the key for
648 * If the inode is encrypted, set up its encryption key if not already done.
649 * Then require that the key be present and return -ENOKEY otherwise.
651 * No locks are needed, and the key will live as long as the struct inode --- so
652 * it won't go away from under you.
654 * Return: 0 on success, -ENOKEY if the key is missing, or another -errno code
655 * if a problem occurred while setting up the encryption key.
657 static inline int fscrypt_require_key(struct inode *inode)
659 if (IS_ENCRYPTED(inode)) {
660 int err = fscrypt_get_encryption_info(inode);
664 if (!fscrypt_has_encryption_key(inode))
671 * fscrypt_prepare_link() - prepare to link an inode into a possibly-encrypted
673 * @old_dentry: an existing dentry for the inode being linked
674 * @dir: the target directory
675 * @dentry: negative dentry for the target filename
677 * A new link can only be added to an encrypted directory if the directory's
678 * encryption key is available --- since otherwise we'd have no way to encrypt
679 * the filename. Therefore, we first set up the directory's encryption key (if
680 * not already done) and return an error if it's unavailable.
682 * We also verify that the link will not violate the constraint that all files
683 * in an encrypted directory tree use the same encryption policy.
685 * Return: 0 on success, -ENOKEY if the directory's encryption key is missing,
686 * -EXDEV if the link would result in an inconsistent encryption policy, or
687 * another -errno code.
689 static inline int fscrypt_prepare_link(struct dentry *old_dentry,
691 struct dentry *dentry)
693 if (IS_ENCRYPTED(dir))
694 return __fscrypt_prepare_link(d_inode(old_dentry), dir, dentry);
699 * fscrypt_prepare_rename() - prepare for a rename between possibly-encrypted
701 * @old_dir: source directory
702 * @old_dentry: dentry for source file
703 * @new_dir: target directory
704 * @new_dentry: dentry for target location (may be negative unless exchanging)
705 * @flags: rename flags (we care at least about %RENAME_EXCHANGE)
707 * Prepare for ->rename() where the source and/or target directories may be
708 * encrypted. A new link can only be added to an encrypted directory if the
709 * directory's encryption key is available --- since otherwise we'd have no way
710 * to encrypt the filename. A rename to an existing name, on the other hand,
711 * *is* cryptographically possible without the key. However, we take the more
712 * conservative approach and just forbid all no-key renames.
714 * We also verify that the rename will not violate the constraint that all files
715 * in an encrypted directory tree use the same encryption policy.
717 * Return: 0 on success, -ENOKEY if an encryption key is missing, -EXDEV if the
718 * rename would cause inconsistent encryption policies, or another -errno code.
720 static inline int fscrypt_prepare_rename(struct inode *old_dir,
721 struct dentry *old_dentry,
722 struct inode *new_dir,
723 struct dentry *new_dentry,
726 if (IS_ENCRYPTED(old_dir) || IS_ENCRYPTED(new_dir))
727 return __fscrypt_prepare_rename(old_dir, old_dentry,
728 new_dir, new_dentry, flags);
733 * fscrypt_prepare_lookup() - prepare to lookup a name in a possibly-encrypted
735 * @dir: directory being searched
736 * @dentry: filename being looked up
737 * @fname: (output) the name to use to search the on-disk directory
739 * Prepare for ->lookup() in a directory which may be encrypted by determining
740 * the name that will actually be used to search the directory on-disk. If the
741 * directory's encryption key is available, then the lookup is assumed to be by
742 * plaintext name; otherwise, it is assumed to be by no-key name.
744 * This also installs a custom ->d_revalidate() method which will invalidate the
745 * dentry if it was created without the key and the key is later added.
747 * Return: 0 on success; -ENOENT if the directory's key is unavailable but the
748 * filename isn't a valid no-key name, so a negative dentry should be created;
749 * or another -errno code.
751 static inline int fscrypt_prepare_lookup(struct inode *dir,
752 struct dentry *dentry,
753 struct fscrypt_name *fname)
755 if (IS_ENCRYPTED(dir))
756 return __fscrypt_prepare_lookup(dir, dentry, fname);
758 memset(fname, 0, sizeof(*fname));
759 fname->usr_fname = &dentry->d_name;
760 fname->disk_name.name = (unsigned char *)dentry->d_name.name;
761 fname->disk_name.len = dentry->d_name.len;
766 * fscrypt_prepare_setattr() - prepare to change a possibly-encrypted inode's
768 * @dentry: dentry through which the inode is being changed
769 * @attr: attributes to change
771 * Prepare for ->setattr() on a possibly-encrypted inode. On an encrypted file,
772 * most attribute changes are allowed even without the encryption key. However,
773 * without the encryption key we do have to forbid truncates. This is needed
774 * because the size being truncated to may not be a multiple of the filesystem
775 * block size, and in that case we'd have to decrypt the final block, zero the
776 * portion past i_size, and re-encrypt it. (We *could* allow truncating to a
777 * filesystem block boundary, but it's simpler to just forbid all truncates ---
778 * and we already forbid all other contents modifications without the key.)
780 * Return: 0 on success, -ENOKEY if the key is missing, or another -errno code
781 * if a problem occurred while setting up the encryption key.
783 static inline int fscrypt_prepare_setattr(struct dentry *dentry,
786 if (attr->ia_valid & ATTR_SIZE)
787 return fscrypt_require_key(d_inode(dentry));
792 * fscrypt_encrypt_symlink() - encrypt the symlink target if needed
793 * @inode: symlink inode
794 * @target: plaintext symlink target
795 * @len: length of @target excluding null terminator
796 * @disk_link: (in/out) the on-disk symlink target being prepared
798 * If the symlink target needs to be encrypted, then this function encrypts it
799 * into @disk_link->name. fscrypt_prepare_symlink() must have been called
800 * previously to compute @disk_link->len. If the filesystem did not allocate a
801 * buffer for @disk_link->name after calling fscrypt_prepare_link(), then one
802 * will be kmalloc()'ed and the filesystem will be responsible for freeing it.
804 * Return: 0 on success, -errno on failure
806 static inline int fscrypt_encrypt_symlink(struct inode *inode,
809 struct fscrypt_str *disk_link)
811 if (IS_ENCRYPTED(inode))
812 return __fscrypt_encrypt_symlink(inode, target, len, disk_link);
816 /* If *pagep is a bounce page, free it and set *pagep to the pagecache page */
817 static inline void fscrypt_finalize_bounce_page(struct page **pagep)
819 struct page *page = *pagep;
821 if (fscrypt_is_bounce_page(page)) {
822 *pagep = fscrypt_pagecache_page(page);
823 fscrypt_free_bounce_page(page);
827 #endif /* _LINUX_FSCRYPT_H */