1 /* SPDX-License-Identifier: GPL-2.0 */
3 * llcrypt.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.
14 * Linux commit 219d54332a09
17 #ifndef _LINUX_LLCRYPT_H
18 #define _LINUX_LLCRYPT_H
20 #ifndef DCACHE_ENCRYPTED_NAME
21 #define DCACHE_ENCRYPTED_NAME 0x02000000
26 #include <linux/slab.h>
27 #include <lustre_disk.h>
28 #include <uapi/linux/llcrypt.h>
30 #define LL_CRYPTO_BLOCK_SIZE 16
41 const struct qstr *usr_fname;
42 struct llcrypt_str disk_name;
45 struct llcrypt_str crypto_buf;
46 bool is_ciphertext_name;
49 #define LLTR_INIT(n, l) { .name = n, .len = l }
50 #define LLTR_TO_QSTR(f) QSTR_INIT((f)->name, (f)->len)
51 #define lname_name(p) ((p)->disk_name.name)
52 #define lname_len(p) ((p)->disk_name.len)
54 /* Maximum value for the third parameter of llcrypt_operations.set_context(). */
55 #define LLCRYPT_SET_CONTEXT_MAX_SIZE 40
57 #ifdef CONFIG_LL_ENCRYPTION
59 * llcrypt superblock flags
61 #define LL_CFLG_OWN_PAGES (1U << 1)
64 * crypto operations for filesystems
66 struct llcrypt_operations {
68 const char *key_prefix;
69 int (*get_context)(struct inode *, void *, size_t);
70 int (*set_context)(struct inode *, const void *, size_t, void *);
71 bool (*dummy_context)(struct inode *);
72 bool (*empty_dir)(struct inode *);
73 unsigned int max_namelen;
81 struct work_struct work;
83 struct list_head free_list; /* Free list */
88 extern bool llcrypt_has_encryption_key(const struct inode *inode);
90 static inline bool llcrypt_dummy_context_enabled(struct inode *inode)
92 struct lustre_sb_info *lsi = s2lsi(inode->i_sb);
97 return lsi->lsi_cop->dummy_context &&
98 lsi->lsi_cop->dummy_context(inode);
102 * When d_splice_alias() moves a directory's encrypted alias to its decrypted
103 * alias as a result of the encryption key being added, DCACHE_ENCRYPTED_NAME
104 * must be cleared. Note that we don't have to support arbitrary moves of this
105 * flag because llcrypt doesn't allow encrypted aliases to be the source or
106 * target of a rename().
108 static inline void llcrypt_handle_d_move(struct dentry *dentry)
110 dentry->d_flags &= ~DCACHE_ENCRYPTED_NAME;
114 extern int __init llcrypt_init(void);
115 extern void __exit llcrypt_exit(void);
116 extern void llcrypt_enqueue_decrypt_work(struct work_struct *);
117 extern struct llcrypt_ctx *llcrypt_get_ctx(gfp_t);
118 extern void llcrypt_release_ctx(struct llcrypt_ctx *);
120 extern struct page *llcrypt_encrypt_pagecache_blocks(struct page *page,
124 extern int llcrypt_encrypt_block(const struct inode *inode, struct page *src,
125 struct page *dst, unsigned int len,
126 unsigned int offs, u64 lblk_num, gfp_t gfp_flags);
128 extern int llcrypt_decrypt_pagecache_blocks(struct page *page, unsigned int len,
131 extern int llcrypt_decrypt_block(const struct inode *inode, struct page *src,
132 struct page *dst, unsigned int len,
133 unsigned int offs, u64 lblk_num, gfp_t gfp_flags);
135 static inline int llcrypt_decrypt_block_inplace(const struct inode *inode,
141 return llcrypt_decrypt_block(inode, page, page, len, offs, lblk_num,
145 static inline bool llcrypt_is_bounce_page(struct page *page)
147 return page->mapping == NULL;
150 static inline struct page *llcrypt_pagecache_page(struct page *bounce_page)
152 return (struct page *)page_private(bounce_page);
155 extern void llcrypt_free_bounce_page(struct page *bounce_page);
158 extern int llcrypt_ioctl_set_policy(struct file *, const void __user *);
159 extern int llcrypt_ioctl_get_policy(struct file *, void __user *);
160 extern int llcrypt_ioctl_get_policy_ex(struct file *, void __user *);
161 extern int llcrypt_has_permitted_context(struct inode *, struct inode *);
162 extern int llcrypt_inherit_context(struct inode *, struct inode *,
164 extern bool llcrypt_policy_has_filename_enc(struct inode *inode);
166 extern void llcrypt_sb_free(struct super_block *sb);
167 extern int llcrypt_ioctl_add_key(struct file *filp, void __user *arg);
168 extern int llcrypt_ioctl_remove_key(struct file *filp, void __user *arg);
169 extern int llcrypt_ioctl_remove_key_all_users(struct file *filp,
171 extern int llcrypt_ioctl_get_key_status(struct file *filp, void __user *arg);
174 extern int llcrypt_get_encryption_info(struct inode *);
175 extern void llcrypt_put_encryption_info(struct inode *);
176 extern void llcrypt_free_inode(struct inode *);
177 extern int llcrypt_drop_inode(struct inode *inode);
180 extern int llcrypt_setup_filename(struct inode *, const struct qstr *,
181 int lookup, struct llcrypt_name *);
183 static inline void llcrypt_free_filename(struct llcrypt_name *fname)
185 kfree(fname->crypto_buf.name);
188 extern int llcrypt_fname_alloc_buffer(const struct inode *, u32,
189 struct llcrypt_str *);
190 extern void llcrypt_fname_free_buffer(struct llcrypt_str *);
191 extern int llcrypt_fname_disk_to_usr(struct inode *, u32, u32,
192 const struct llcrypt_str *, struct llcrypt_str *);
194 #define LLCRYPT_FNAME_MAX_UNDIGESTED_SIZE 32
196 /* Extracts the second-to-last ciphertext block; see explanation below */
197 #define LLCRYPT_FNAME_DIGEST(name, len) \
198 ((name) + round_down((len) - LL_CRYPTO_BLOCK_SIZE - 1, \
199 LL_CRYPTO_BLOCK_SIZE))
201 #define LLCRYPT_FNAME_DIGEST_SIZE LL_CRYPTO_BLOCK_SIZE
204 * llcrypt_digested_name - alternate identifier for an on-disk filename
206 * When userspace lists an encrypted directory without access to the key,
207 * filenames whose ciphertext is longer than LLCRYPT_FNAME_MAX_UNDIGESTED_SIZE
208 * bytes are shown in this abbreviated form (base64-encoded) rather than as the
209 * full ciphertext (base64-encoded). This is necessary to allow supporting
210 * filenames up to NAME_MAX bytes, since base64 encoding expands the length.
212 * To make it possible for filesystems to still find the correct directory entry
213 * despite not knowing the full on-disk name, we encode any filesystem-specific
214 * 'hash' and/or 'minor_hash' which the filesystem may need for its lookups,
215 * followed by the second-to-last ciphertext block of the filename. Due to the
216 * use of the CBC-CTS encryption mode, the second-to-last ciphertext block
217 * depends on the full plaintext. (Note that ciphertext stealing causes the
218 * last two blocks to appear "flipped".) This makes accidental collisions very
219 * unlikely: just a 1 in 2^128 chance for two filenames to collide even if they
220 * share the same filesystem-specific hashes.
222 * However, this scheme isn't immune to intentional collisions, which can be
223 * created by anyone able to create arbitrary plaintext filenames and view them
224 * without the key. Making the "digest" be a real cryptographic hash like
225 * SHA-256 over the full ciphertext would prevent this, although it would be
226 * less efficient and harder to implement, especially since the filesystem would
227 * need to calculate it for each directory entry examined during a search.
229 struct llcrypt_digested_name {
232 u8 digest[LLCRYPT_FNAME_DIGEST_SIZE];
236 * llcrypt_match_name() - test whether the given name matches a directory entry
237 * @fname: the name being searched for
238 * @de_name: the name from the directory entry
239 * @de_name_len: the length of @de_name in bytes
241 * Normally @fname->disk_name will be set, and in that case we simply compare
242 * that to the name stored in the directory entry. The only exception is that
243 * if we don't have the key for an encrypted directory and a filename in it is
244 * very long, then we won't have the full disk_name and we'll instead need to
245 * match against the llcrypt_digested_name.
247 * Return: %true if the name matches, otherwise %false.
249 static inline bool llcrypt_match_name(const struct llcrypt_name *fname,
250 const u8 *de_name, u32 de_name_len)
252 if (unlikely(!fname->disk_name.name)) {
253 const struct llcrypt_digested_name *n =
254 (const void *)fname->crypto_buf.name;
255 if (WARN_ON_ONCE(fname->usr_fname->name[0] != '_'))
257 if (de_name_len <= LLCRYPT_FNAME_MAX_UNDIGESTED_SIZE)
259 return !memcmp(LLCRYPT_FNAME_DIGEST(de_name, de_name_len),
260 n->digest, LLCRYPT_FNAME_DIGEST_SIZE);
263 if (de_name_len != fname->disk_name.len)
265 return !memcmp(de_name, fname->disk_name.name, fname->disk_name.len);
269 extern void llcrypt_decrypt_bio(struct bio *);
270 extern void llcrypt_enqueue_decrypt_bio(struct llcrypt_ctx *ctx,
272 extern int llcrypt_zeroout_range(const struct inode *, pgoff_t, sector_t,
276 extern int llcrypt_file_open(struct inode *inode, struct file *filp);
277 extern int __llcrypt_prepare_link(struct inode *inode, struct inode *dir,
278 struct dentry *dentry);
279 extern int __llcrypt_prepare_rename(struct inode *old_dir,
280 struct dentry *old_dentry,
281 struct inode *new_dir,
282 struct dentry *new_dentry,
284 extern int __llcrypt_prepare_lookup(struct inode *dir, struct dentry *dentry,
285 struct llcrypt_name *fname);
286 extern int __llcrypt_prepare_symlink(struct inode *dir, unsigned int len,
287 unsigned int max_len,
288 struct llcrypt_str *disk_link);
289 extern int __llcrypt_encrypt_symlink(struct inode *inode, const char *target,
291 struct llcrypt_str *disk_link);
292 extern const char *llcrypt_get_symlink(struct inode *inode, const void *caddr,
293 unsigned int max_size,
294 struct delayed_call *done);
295 static inline void llcrypt_set_ops(struct super_block *sb,
296 const struct llcrypt_operations *lsi_cop)
298 struct lustre_sb_info *lsi = s2lsi(sb);
301 lsi->lsi_cop = lsi_cop;
303 #else /* !CONFIG_LL_ENCRYPTION */
305 struct llcrypt_operations;
306 #define llcrypt_init() 0
307 #define llcrypt_exit() {}
310 #define IS_ENCRYPTED(x) 0
312 static inline bool llcrypt_has_encryption_key(const struct inode *inode)
317 static inline bool llcrypt_dummy_context_enabled(struct inode *inode)
322 static inline void llcrypt_handle_d_move(struct dentry *dentry)
327 static inline void llcrypt_enqueue_decrypt_work(struct work_struct *work)
331 static inline struct llcrypt_ctx *llcrypt_get_ctx(gfp_t gfp_flags)
333 return ERR_PTR(-EOPNOTSUPP);
336 static inline void llcrypt_release_ctx(struct llcrypt_ctx *ctx)
341 static inline struct page *llcrypt_encrypt_pagecache_blocks(struct page *page,
346 return ERR_PTR(-EOPNOTSUPP);
349 static inline int llcrypt_encrypt_block(const struct inode *inode,
350 struct page *src, struct page *dst,
351 unsigned int len, unsigned int offs,
352 u64 lblk_num, gfp_t gfp_flags)
357 static inline int llcrypt_decrypt_pagecache_blocks(struct page *page,
364 static inline int llcrypt_decrypt_block(const struct inode *inode,
365 struct page *src, struct page *dst,
366 unsigned int len, unsigned int offs,
367 u64 lblk_num, gfp_t gfp_flags)
372 static inline int llcrypt_decrypt_block_inplace(const struct inode *inode,
375 unsigned int offs, u64 lblk_num)
380 static inline bool llcrypt_is_bounce_page(struct page *page)
385 static inline struct page *llcrypt_pagecache_page(struct page *bounce_page)
388 return ERR_PTR(-EINVAL);
391 static inline void llcrypt_free_bounce_page(struct page *bounce_page)
396 static inline int llcrypt_ioctl_set_policy(struct file *filp,
397 const void __user *arg)
402 static inline int llcrypt_ioctl_get_policy(struct file *filp, void __user *arg)
407 static inline int llcrypt_ioctl_get_policy_ex(struct file *filp,
413 static inline int llcrypt_has_permitted_context(struct inode *parent,
419 static inline int llcrypt_inherit_context(struct inode *parent,
421 void *fs_data, bool preload)
425 static inline bool llcrypt_policy_has_filename_enc(struct inode *inode)
431 static inline void llcrypt_sb_free(struct super_block *sb)
435 static inline int llcrypt_ioctl_add_key(struct file *filp, void __user *arg)
440 static inline int llcrypt_ioctl_remove_key(struct file *filp, void __user *arg)
445 static inline int llcrypt_ioctl_remove_key_all_users(struct file *filp,
451 static inline int llcrypt_ioctl_get_key_status(struct file *filp,
458 static inline int llcrypt_get_encryption_info(struct inode *inode)
463 static inline void llcrypt_put_encryption_info(struct inode *inode)
468 static inline void llcrypt_free_inode(struct inode *inode)
472 static inline int llcrypt_drop_inode(struct inode *inode)
478 static inline int llcrypt_setup_filename(struct inode *dir,
479 const struct qstr *iname,
480 int lookup, struct llcrypt_name *fname)
482 if (IS_ENCRYPTED(dir))
485 memset(fname, 0, sizeof(*fname));
486 fname->usr_fname = iname;
487 fname->disk_name.name = (unsigned char *)iname->name;
488 fname->disk_name.len = iname->len;
492 static inline void llcrypt_free_filename(struct llcrypt_name *fname)
497 static inline int llcrypt_fname_alloc_buffer(const struct inode *inode,
498 u32 max_encrypted_len,
499 struct llcrypt_str *crypto_str)
504 static inline void llcrypt_fname_free_buffer(struct llcrypt_str *crypto_str)
509 static inline int llcrypt_fname_disk_to_usr(struct inode *inode,
510 u32 hash, u32 minor_hash,
511 const struct llcrypt_str *iname,
512 struct llcrypt_str *oname)
517 static inline bool llcrypt_match_name(const struct llcrypt_name *fname,
518 const u8 *de_name, u32 de_name_len)
520 /* Encryption support disabled; use standard comparison */
521 if (de_name_len != fname->disk_name.len)
523 return !memcmp(de_name, fname->disk_name.name, fname->disk_name.len);
527 static inline void llcrypt_decrypt_bio(struct bio *bio)
531 static inline void llcrypt_enqueue_decrypt_bio(struct llcrypt_ctx *ctx,
536 static inline int llcrypt_zeroout_range(const struct inode *inode, pgoff_t lblk,
537 sector_t pblk, unsigned int len)
544 static inline int llcrypt_file_open(struct inode *inode, struct file *filp)
546 if (IS_ENCRYPTED(inode))
551 static inline int __llcrypt_prepare_link(struct inode *inode, struct inode *dir,
552 struct dentry *dentry)
557 static inline int __llcrypt_prepare_rename(struct inode *old_dir,
558 struct dentry *old_dentry,
559 struct inode *new_dir,
560 struct dentry *new_dentry,
566 static inline int __llcrypt_prepare_lookup(struct inode *dir,
567 struct dentry *dentry,
568 struct llcrypt_name *fname)
573 static inline int __llcrypt_prepare_symlink(struct inode *dir,
575 unsigned int max_len,
576 struct llcrypt_str *disk_link)
582 static inline int __llcrypt_encrypt_symlink(struct inode *inode,
585 struct llcrypt_str *disk_link)
590 #define llcrypt_get_symlink(inode, caddr, max_size, done) ERR_PTR(-EOPNOTSUPP)
592 static inline void llcrypt_set_ops(struct super_block *sb,
593 const struct llcrypt_operations *lsi_cop)
597 #endif /* !CONFIG_LL_ENCRYPTION */
600 * llcrypt_require_key - require an inode's encryption key
601 * @inode: the inode we need the key for
603 * If the inode is encrypted, set up its encryption key if not already done.
604 * Then require that the key be present and return -ENOKEY otherwise.
606 * No locks are needed, and the key will live as long as the struct inode --- so
607 * it won't go away from under you.
609 * Return: 0 on success, -ENOKEY if the key is missing, or another -errno code
610 * if a problem occurred while setting up the encryption key.
612 static inline int llcrypt_require_key(struct inode *inode)
614 if (IS_ENCRYPTED(inode)) {
615 int err = llcrypt_get_encryption_info(inode);
619 if (!llcrypt_has_encryption_key(inode))
626 * llcrypt_prepare_link - prepare to link an inode into a possibly-encrypted directory
627 * @old_dentry: an existing dentry for the inode being linked
628 * @dir: the target directory
629 * @dentry: negative dentry for the target filename
631 * A new link can only be added to an encrypted directory if the directory's
632 * encryption key is available --- since otherwise we'd have no way to encrypt
633 * the filename. Therefore, we first set up the directory's encryption key (if
634 * not already done) and return an error if it's unavailable.
636 * We also verify that the link will not violate the constraint that all files
637 * in an encrypted directory tree use the same encryption policy.
639 * Return: 0 on success, -ENOKEY if the directory's encryption key is missing,
640 * -EXDEV if the link would result in an inconsistent encryption policy, or
641 * another -errno code.
643 static inline int llcrypt_prepare_link(struct dentry *old_dentry,
645 struct dentry *dentry)
647 if (IS_ENCRYPTED(dir))
648 return __llcrypt_prepare_link(d_inode(old_dentry), dir, dentry);
653 * llcrypt_prepare_rename - prepare for a rename between possibly-encrypted directories
654 * @old_dir: source directory
655 * @old_dentry: dentry for source file
656 * @new_dir: target directory
657 * @new_dentry: dentry for target location (may be negative unless exchanging)
658 * @flags: rename flags (we care at least about %RENAME_EXCHANGE)
660 * Prepare for ->rename() where the source and/or target directories may be
661 * encrypted. A new link can only be added to an encrypted directory if the
662 * directory's encryption key is available --- since otherwise we'd have no way
663 * to encrypt the filename. A rename to an existing name, on the other hand,
664 * *is* cryptographically possible without the key. However, we take the more
665 * conservative approach and just forbid all no-key renames.
667 * We also verify that the rename will not violate the constraint that all files
668 * in an encrypted directory tree use the same encryption policy.
670 * Return: 0 on success, -ENOKEY if an encryption key is missing, -EXDEV if the
671 * rename would cause inconsistent encryption policies, or another -errno code.
673 static inline int llcrypt_prepare_rename(struct inode *old_dir,
674 struct dentry *old_dentry,
675 struct inode *new_dir,
676 struct dentry *new_dentry,
679 if (IS_ENCRYPTED(old_dir) || IS_ENCRYPTED(new_dir))
680 return __llcrypt_prepare_rename(old_dir, old_dentry,
681 new_dir, new_dentry, flags);
686 * llcrypt_prepare_lookup - prepare to lookup a name in a possibly-encrypted directory
687 * @dir: directory being searched
688 * @dentry: filename being looked up
689 * @fname: (output) the name to use to search the on-disk directory
691 * Prepare for ->lookup() in a directory which may be encrypted by determining
692 * the name that will actually be used to search the directory on-disk. Lookups
693 * can be done with or without the directory's encryption key; without the key,
694 * filenames are presented in encrypted form. Therefore, we'll try to set up
695 * the directory's encryption key, but even without it the lookup can continue.
697 * This also installs a custom ->d_revalidate() method which will invalidate the
698 * dentry if it was created without the key and the key is later added.
700 * Return: 0 on success; -ENOENT if key is unavailable but the filename isn't a
701 * correctly formed encoded ciphertext name, so a negative dentry should be
702 * created; or another -errno code.
704 static inline int llcrypt_prepare_lookup(struct inode *dir,
705 struct dentry *dentry,
706 struct llcrypt_name *fname)
708 if (IS_ENCRYPTED(dir))
709 return __llcrypt_prepare_lookup(dir, dentry, fname);
711 memset(fname, 0, sizeof(*fname));
712 fname->usr_fname = &dentry->d_name;
713 fname->disk_name.name = (unsigned char *)dentry->d_name.name;
714 fname->disk_name.len = dentry->d_name.len;
719 * llcrypt_prepare_setattr - prepare to change a possibly-encrypted inode's attributes
720 * @dentry: dentry through which the inode is being changed
721 * @attr: attributes to change
723 * Prepare for ->setattr() on a possibly-encrypted inode. On an encrypted file,
724 * most attribute changes are allowed even without the encryption key. However,
725 * without the encryption key we do have to forbid truncates. This is needed
726 * because the size being truncated to may not be a multiple of the filesystem
727 * block size, and in that case we'd have to decrypt the final block, zero the
728 * portion past i_size, and re-encrypt it. (We *could* allow truncating to a
729 * filesystem block boundary, but it's simpler to just forbid all truncates ---
730 * and we already forbid all other contents modifications without the key.)
732 * Return: 0 on success, -ENOKEY if the key is missing, or another -errno code
733 * if a problem occurred while setting up the encryption key.
735 static inline int llcrypt_prepare_setattr(struct dentry *dentry,
738 if (attr->ia_valid & ATTR_SIZE)
739 return llcrypt_require_key(d_inode(dentry));
744 * llcrypt_prepare_symlink - prepare to create a possibly-encrypted symlink
745 * @dir: directory in which the symlink is being created
746 * @target: plaintext symlink target
747 * @len: length of @target excluding null terminator
748 * @max_len: space the filesystem has available to store the symlink target
749 * @disk_link: (out) the on-disk symlink target being prepared
751 * This function computes the size the symlink target will require on-disk,
752 * stores it in @disk_link->len, and validates it against @max_len. An
753 * encrypted symlink may be longer than the original.
755 * Additionally, @disk_link->name is set to @target if the symlink will be
756 * unencrypted, but left NULL if the symlink will be encrypted. For encrypted
757 * symlinks, the filesystem must call llcrypt_encrypt_symlink() to create the
758 * on-disk target later. (The reason for the two-step process is that some
759 * filesystems need to know the size of the symlink target before creating the
760 * inode, e.g. to determine whether it will be a "fast" or "slow" symlink.)
762 * Return: 0 on success, -ENAMETOOLONG if the symlink target is too long,
763 * -ENOKEY if the encryption key is missing, or another -errno code if a problem
764 * occurred while setting up the encryption key.
766 static inline int llcrypt_prepare_symlink(struct inode *dir,
769 unsigned int max_len,
770 struct llcrypt_str *disk_link)
772 if ((IS_ENCRYPTED(dir) || llcrypt_dummy_context_enabled(dir)) &&
773 llcrypt_policy_has_filename_enc(dir))
774 return __llcrypt_prepare_symlink(dir, len, max_len, disk_link);
776 disk_link->name = (unsigned char *)target;
777 disk_link->len = len + 1;
778 if (disk_link->len > max_len)
779 return -ENAMETOOLONG;
784 * llcrypt_encrypt_symlink - encrypt the symlink target if needed
785 * @inode: symlink inode
786 * @target: plaintext symlink target
787 * @len: length of @target excluding null terminator
788 * @disk_link: (in/out) the on-disk symlink target being prepared
790 * If the symlink target needs to be encrypted, then this function encrypts it
791 * into @disk_link->name. llcrypt_prepare_symlink() must have been called
792 * previously to compute @disk_link->len. If the filesystem did not allocate a
793 * buffer for @disk_link->name after calling llcrypt_prepare_link(), then one
794 * will be kmalloc()'ed and the filesystem will be responsible for freeing it.
796 * Return: 0 on success, -errno on failure
798 static inline int llcrypt_encrypt_symlink(struct inode *inode,
801 struct llcrypt_str *disk_link)
803 if (IS_ENCRYPTED(inode))
804 return __llcrypt_encrypt_symlink(inode, target, len, disk_link);
808 /* If *pagep is a bounce page, free it and set *pagep to the pagecache page */
809 static inline void llcrypt_finalize_bounce_page(struct page **pagep)
811 struct page *page = *pagep;
813 if (llcrypt_is_bounce_page(page)) {
814 *pagep = llcrypt_pagecache_page(page);
815 llcrypt_free_bounce_page(page);
819 #endif /* _LINUX_LLCRYPT_H */