[GitHub/LineageOS/android_kernel_motorola_exynos9610.git] / include / linux / fscrypt_supp.h

/* SPDX-License-Identifier: GPL-2.0 */
/*
 * fscrypt_supp.h
 *
 * Do not include this file directly. Use fscrypt.h instead!
 */
#ifndef _LINUX_FSCRYPT_H
#error "Incorrect include of linux/fscrypt_supp.h!"
#endif

#ifndef _LINUX_FSCRYPT_SUPP_H
#define _LINUX_FSCRYPT_SUPP_H

#include <linux/mm.h>
#include <linux/slab.h>

/*
 * fscrypt superblock flags
 */
#define FS_CFLG_OWN_PAGES (1U << 1)

/*
 * crypto operations for filesystems
 */
struct fscrypt_operations {
	unsigned int flags;
	const char *key_prefix;
	int (*get_context)(struct inode *, void *, size_t);
	int (*set_context)(struct inode *, const void *, size_t, void *);
	bool (*dummy_context)(struct inode *);
	bool (*empty_dir)(struct inode *);
	unsigned (*max_namelen)(struct inode *);
};

struct fscrypt_ctx {
	union {
		struct {
			struct page *bounce_page;	/* Ciphertext page */
			struct page *control_page;	/* Original page  */
		} w;
		struct {
			struct bio *bio;
			struct work_struct work;
		} r;
		struct list_head free_list;	/* Free list */
	};
	u8 flags;				/* Flags */
};

static inline bool fscrypt_has_encryption_key(const struct inode *inode)
{
	return (inode->i_crypt_info != NULL);
}

static inline bool fscrypt_dummy_context_enabled(struct inode *inode)
{
	return inode->i_sb->s_cop->dummy_context &&
		inode->i_sb->s_cop->dummy_context(inode);
}

/* crypto.c */
extern void fscrypt_enqueue_decrypt_work(struct work_struct *);
extern struct fscrypt_ctx *fscrypt_get_ctx(const struct inode *, gfp_t);
extern void fscrypt_release_ctx(struct fscrypt_ctx *);
extern struct page *fscrypt_encrypt_page(const struct inode *, struct page *,
						unsigned int, unsigned int,
						u64, gfp_t);
extern int fscrypt_decrypt_page(const struct inode *, struct page *, unsigned int,
				unsigned int, u64);

static inline struct page *fscrypt_control_page(struct page *page)
{
	return ((struct fscrypt_ctx *)page_private(page))->w.control_page;
}

extern void fscrypt_restore_control_page(struct page *);

extern const struct dentry_operations fscrypt_d_ops;

static inline void fscrypt_set_d_op(struct dentry *dentry)
{
	d_set_d_op(dentry, &fscrypt_d_ops);
}

static inline void fscrypt_set_encrypted_dentry(struct dentry *dentry)
{
	spin_lock(&dentry->d_lock);
	dentry->d_flags |= DCACHE_ENCRYPTED_WITH_KEY;
	spin_unlock(&dentry->d_lock);
}

/* policy.c */
extern int fscrypt_ioctl_set_policy(struct file *, const void __user *);
extern int fscrypt_ioctl_get_policy(struct file *, void __user *);
extern int fscrypt_has_permitted_context(struct inode *, struct inode *);
extern int fscrypt_inherit_context(struct inode *, struct inode *,
					void *, bool);
/* keyinfo.c */
extern int fscrypt_get_encryption_info(struct inode *);
extern void fscrypt_put_encryption_info(struct inode *);

/* fname.c */
extern int fscrypt_setup_filename(struct inode *, const struct qstr *,
				int lookup, struct fscrypt_name *);

static inline void fscrypt_free_filename(struct fscrypt_name *fname)
{
	kfree(fname->crypto_buf.name);
}

extern int fscrypt_fname_alloc_buffer(const struct inode *, u32,
				struct fscrypt_str *);
extern void fscrypt_fname_free_buffer(struct fscrypt_str *);
extern int fscrypt_fname_disk_to_usr(struct inode *, u32, u32,
			const struct fscrypt_str *, struct fscrypt_str *);

#define FSCRYPT_FNAME_MAX_UNDIGESTED_SIZE	32

/* Extracts the second-to-last ciphertext block; see explanation below */
#define FSCRYPT_FNAME_DIGEST(name, len)	\
	((name) + round_down((len) - FS_CRYPTO_BLOCK_SIZE - 1, \
			     FS_CRYPTO_BLOCK_SIZE))

#define FSCRYPT_FNAME_DIGEST_SIZE	FS_CRYPTO_BLOCK_SIZE

/**
 * fscrypt_digested_name - alternate identifier for an on-disk filename
 *
 * When userspace lists an encrypted directory without access to the key,
 * filenames whose ciphertext is longer than FSCRYPT_FNAME_MAX_UNDIGESTED_SIZE
 * bytes are shown in this abbreviated form (base64-encoded) rather than as the
 * full ciphertext (base64-encoded).  This is necessary to allow supporting
 * filenames up to NAME_MAX bytes, since base64 encoding expands the length.
 *
 * To make it possible for filesystems to still find the correct directory entry
 * despite not knowing the full on-disk name, we encode any filesystem-specific
 * 'hash' and/or 'minor_hash' which the filesystem may need for its lookups,
 * followed by the second-to-last ciphertext block of the filename.  Due to the
 * use of the CBC-CTS encryption mode, the second-to-last ciphertext block
 * depends on the full plaintext.  (Note that ciphertext stealing causes the
 * last two blocks to appear "flipped".)  This makes accidental collisions very
 * unlikely: just a 1 in 2^128 chance for two filenames to collide even if they
 * share the same filesystem-specific hashes.
 *
 * However, this scheme isn't immune to intentional collisions, which can be
 * created by anyone able to create arbitrary plaintext filenames and view them
 * without the key.  Making the "digest" be a real cryptographic hash like
 * SHA-256 over the full ciphertext would prevent this, although it would be
 * less efficient and harder to implement, especially since the filesystem would
 * need to calculate it for each directory entry examined during a search.
 */
struct fscrypt_digested_name {
	u32 hash;
	u32 minor_hash;
	u8 digest[FSCRYPT_FNAME_DIGEST_SIZE];
};

/**
 * fscrypt_match_name() - test whether the given name matches a directory entry
 * @fname: the name being searched for
 * @de_name: the name from the directory entry
 * @de_name_len: the length of @de_name in bytes
 *
 * Normally @fname->disk_name will be set, and in that case we simply compare
 * that to the name stored in the directory entry.  The only exception is that
 * if we don't have the key for an encrypted directory and a filename in it is
 * very long, then we won't have the full disk_name and we'll instead need to
 * match against the fscrypt_digested_name.
 *
 * Return: %true if the name matches, otherwise %false.
 */
static inline bool fscrypt_match_name(const struct fscrypt_name *fname,
				      const u8 *de_name, u32 de_name_len)
{
	if (unlikely(!fname->disk_name.name)) {
		const struct fscrypt_digested_name *n =
			(const void *)fname->crypto_buf.name;
		if (WARN_ON_ONCE(fname->usr_fname->name[0] != '_'))
			return false;
		if (de_name_len <= FSCRYPT_FNAME_MAX_UNDIGESTED_SIZE)
			return false;
		return !memcmp(FSCRYPT_FNAME_DIGEST(de_name, de_name_len),
			       n->digest, FSCRYPT_FNAME_DIGEST_SIZE);
	}

	if (de_name_len != fname->disk_name.len)
		return false;
	return !memcmp(de_name, fname->disk_name.name, fname->disk_name.len);
}

/* bio.c */
extern void fscrypt_decrypt_bio(struct bio *);
extern void fscrypt_enqueue_decrypt_bio(struct fscrypt_ctx *ctx,
					struct bio *bio);
extern void fscrypt_pullback_bio_page(struct page **, bool);
extern int fscrypt_zeroout_range(const struct inode *, pgoff_t, sector_t,
				 unsigned int);
void fscrypt_set_bio(const struct inode *inode, struct bio *bio, u64 dun);
void *fscrypt_get_diskcipher(const struct inode *inode);
int fscrypt_disk_encrypted(const struct inode *inode);

/* hooks.c */
extern int fscrypt_file_open(struct inode *inode, struct file *filp);
extern int __fscrypt_prepare_link(struct inode *inode, struct inode *dir);
extern int __fscrypt_prepare_rename(struct inode *old_dir,
				    struct dentry *old_dentry,
				    struct inode *new_dir,
				    struct dentry *new_dentry,
				    unsigned int flags);
extern int __fscrypt_prepare_lookup(struct inode *dir, struct dentry *dentry);
extern int __fscrypt_prepare_symlink(struct inode *dir, unsigned int len,
				     unsigned int max_len,
				     struct fscrypt_str *disk_link);
extern int __fscrypt_encrypt_symlink(struct inode *inode, const char *target,
				     unsigned int len,
				     struct fscrypt_str *disk_link);
extern const char *fscrypt_get_symlink(struct inode *inode, const void *caddr,
				       unsigned int max_size,
				       struct delayed_call *done);

#endif	/* _LINUX_FSCRYPT_SUPP_H */
Commit	Line	Data
b2441318	1	/* SPDX-License-Identifier: GPL-2.0 */
46f47e48 EB	2	/*
	3	* fscrypt_supp.h
	4	*
a53dc75a	5	* Do not include this file directly. Use fscrypt.h instead!
46f47e48	6	*/
a53dc75a JK	7	#ifndef _LINUX_FSCRYPT_H
	8	#error "Incorrect include of linux/fscrypt_supp.h!"
	9	#endif
46f47e48 EB	10
	11	#ifndef _LINUX_FSCRYPT_SUPP_H
	12	#define _LINUX_FSCRYPT_SUPP_H
	13
a2a9032a JK	14	#include <linux/mm.h>
	15	#include <linux/slab.h>
	16
	17	/*
	18	* fscrypt superblock flags
	19	*/
	20	#define FS_CFLG_OWN_PAGES (1U << 1)
	21
	22	/*
	23	* crypto operations for filesystems
	24	*/
	25	struct fscrypt_operations {
	26	unsigned int flags;
	27	const char *key_prefix;
	28	int (get_context)(struct inode , void *, size_t);
	29	int (set_context)(struct inode , const void , size_t, void );
	30	bool (dummy_context)(struct inode );
	31	bool (empty_dir)(struct inode );
	32	unsigned (max_namelen)(struct inode );
	33	};
	34
	35	struct fscrypt_ctx {
	36	union {
	37	struct {
	38	struct page bounce_page; / Ciphertext page */
	39	struct page control_page; / Original page */
	40	} w;
	41	struct {
	42	struct bio *bio;
	43	struct work_struct work;
	44	} r;
	45	struct list_head free_list; /* Free list */
	46	};
	47	u8 flags; /* Flags */
	48	};
	49
	50	static inline bool fscrypt_has_encryption_key(const struct inode *inode)
	51	{
	52	return (inode->i_crypt_info != NULL);
	53	}
	54
	55	static inline bool fscrypt_dummy_context_enabled(struct inode *inode)
	56	{
	57	return inode->i_sb->s_cop->dummy_context &&
	58	inode->i_sb->s_cop->dummy_context(inode);
	59	}
	60
46f47e48	61	/* crypto.c */
61760b0b	62	extern void fscrypt_enqueue_decrypt_work(struct work_struct *);
46f47e48 EB	63	extern struct fscrypt_ctx fscrypt_get_ctx(const struct inode , gfp_t);
	64	extern void fscrypt_release_ctx(struct fscrypt_ctx *);
	65	extern struct page fscrypt_encrypt_page(const struct inode , struct page *,
	66	unsigned int, unsigned int,
	67	u64, gfp_t);
	68	extern int fscrypt_decrypt_page(const struct inode , struct page , unsigned int,
	69	unsigned int, u64);
a2a9032a JK	70
	71	static inline struct page fscrypt_control_page(struct page page)
	72	{
	73	return ((struct fscrypt_ctx *)page_private(page))->w.control_page;
	74	}
	75
46f47e48 EB	76	extern void fscrypt_restore_control_page(struct page *);
	77
	78	extern const struct dentry_operations fscrypt_d_ops;
	79
	80	static inline void fscrypt_set_d_op(struct dentry *dentry)
	81	{
	82	d_set_d_op(dentry, &fscrypt_d_ops);
	83	}
	84
	85	static inline void fscrypt_set_encrypted_dentry(struct dentry *dentry)
	86	{
	87	spin_lock(&dentry->d_lock);
	88	dentry->d_flags \|= DCACHE_ENCRYPTED_WITH_KEY;
	89	spin_unlock(&dentry->d_lock);
	90	}
	91
	92	/* policy.c */
	93	extern int fscrypt_ioctl_set_policy(struct file , const void __user );
	94	extern int fscrypt_ioctl_get_policy(struct file , void __user );
	95	extern int fscrypt_has_permitted_context(struct inode , struct inode );
	96	extern int fscrypt_inherit_context(struct inode , struct inode ,
	97	void *, bool);
	98	/* keyinfo.c */
	99	extern int fscrypt_get_encryption_info(struct inode *);
a2a9032a	100	extern void fscrypt_put_encryption_info(struct inode *);
46f47e48 EB	101
	102	/* fname.c */
	103	extern int fscrypt_setup_filename(struct inode , const struct qstr ,
	104	int lookup, struct fscrypt_name *);
27e47a63 EB	105
	106	static inline void fscrypt_free_filename(struct fscrypt_name *fname)
	107	{
	108	kfree(fname->crypto_buf.name);
	109	}
	110
46f47e48 EB	111	extern int fscrypt_fname_alloc_buffer(const struct inode *, u32,
	112	struct fscrypt_str *);
	113	extern void fscrypt_fname_free_buffer(struct fscrypt_str *);
	114	extern int fscrypt_fname_disk_to_usr(struct inode *, u32, u32,
	115	const struct fscrypt_str , struct fscrypt_str );
46f47e48	116
17159420 EB	117	#define FSCRYPT_FNAME_MAX_UNDIGESTED_SIZE 32
	118
	119	/* Extracts the second-to-last ciphertext block; see explanation below */
	120	#define FSCRYPT_FNAME_DIGEST(name, len) \
	121	((name) + round_down((len) - FS_CRYPTO_BLOCK_SIZE - 1, \
	122	FS_CRYPTO_BLOCK_SIZE))
	123
	124	#define FSCRYPT_FNAME_DIGEST_SIZE FS_CRYPTO_BLOCK_SIZE
	125
	126	/**
	127	* fscrypt_digested_name - alternate identifier for an on-disk filename
	128	*
	129	* When userspace lists an encrypted directory without access to the key,
	130	* filenames whose ciphertext is longer than FSCRYPT_FNAME_MAX_UNDIGESTED_SIZE
	131	* bytes are shown in this abbreviated form (base64-encoded) rather than as the
	132	* full ciphertext (base64-encoded). This is necessary to allow supporting
	133	* filenames up to NAME_MAX bytes, since base64 encoding expands the length.
	134	*
	135	* To make it possible for filesystems to still find the correct directory entry
	136	* despite not knowing the full on-disk name, we encode any filesystem-specific
	137	* 'hash' and/or 'minor_hash' which the filesystem may need for its lookups,
	138	* followed by the second-to-last ciphertext block of the filename. Due to the
	139	* use of the CBC-CTS encryption mode, the second-to-last ciphertext block
	140	* depends on the full plaintext. (Note that ciphertext stealing causes the
6f9d696f EB	141	* last two blocks to appear "flipped".) This makes accidental collisions very
	142	* unlikely: just a 1 in 2^128 chance for two filenames to collide even if they
	143	* share the same filesystem-specific hashes.
17159420	144	*
6f9d696f EB	145	* However, this scheme isn't immune to intentional collisions, which can be
	146	* created by anyone able to create arbitrary plaintext filenames and view them
	147	* without the key. Making the "digest" be a real cryptographic hash like
	148	* SHA-256 over the full ciphertext would prevent this, although it would be
	149	* less efficient and harder to implement, especially since the filesystem would
	150	* need to calculate it for each directory entry examined during a search.
17159420 EB	151	*/
	152	struct fscrypt_digested_name {
	153	u32 hash;
	154	u32 minor_hash;
	155	u8 digest[FSCRYPT_FNAME_DIGEST_SIZE];
	156	};
	157
	158	/**
	159	* fscrypt_match_name() - test whether the given name matches a directory entry
	160	* @fname: the name being searched for
	161	* @de_name: the name from the directory entry
	162	* @de_name_len: the length of @de_name in bytes
	163	*
	164	* Normally @fname->disk_name will be set, and in that case we simply compare
	165	* that to the name stored in the directory entry. The only exception is that
	166	* if we don't have the key for an encrypted directory and a filename in it is
	167	* very long, then we won't have the full disk_name and we'll instead need to
	168	* match against the fscrypt_digested_name.
	169	*
	170	* Return: %true if the name matches, otherwise %false.
	171	*/
	172	static inline bool fscrypt_match_name(const struct fscrypt_name *fname,
	173	const u8 *de_name, u32 de_name_len)
	174	{
	175	if (unlikely(!fname->disk_name.name)) {
	176	const struct fscrypt_digested_name *n =
	177	(const void *)fname->crypto_buf.name;
	178	if (WARN_ON_ONCE(fname->usr_fname->name[0] != '_'))
	179	return false;
	180	if (de_name_len <= FSCRYPT_FNAME_MAX_UNDIGESTED_SIZE)
	181	return false;
	182	return !memcmp(FSCRYPT_FNAME_DIGEST(de_name, de_name_len),
	183	n->digest, FSCRYPT_FNAME_DIGEST_SIZE);
	184	}
	185
	186	if (de_name_len != fname->disk_name.len)
	187	return false;
	188	return !memcmp(de_name, fname->disk_name.name, fname->disk_name.len);
	189	}
	190
46f47e48	191	/* bio.c */
61760b0b EB	192	extern void fscrypt_decrypt_bio(struct bio *);
	193	extern void fscrypt_enqueue_decrypt_bio(struct fscrypt_ctx *ctx,
	194	struct bio *bio);
46f47e48 EB	195	extern void fscrypt_pullback_bio_page(struct page **, bool);
	196	extern int fscrypt_zeroout_range(const struct inode *, pgoff_t, sector_t,
	197	unsigned int);
49e3bbe3	198	void fscrypt_set_bio(const struct inode inode, struct bio bio, u64 dun);
bb32a122 BK	199	void fscrypt_get_diskcipher(const struct inode inode);
	200	int fscrypt_disk_encrypted(const struct inode *inode);
	201
a53dc75a JK	202	/* hooks.c */
	203	extern int fscrypt_file_open(struct inode inode, struct file filp);
	204	extern int __fscrypt_prepare_link(struct inode inode, struct inode dir);
	205	extern int __fscrypt_prepare_rename(struct inode *old_dir,
	206	struct dentry *old_dentry,
	207	struct inode *new_dir,
	208	struct dentry *new_dentry,
	209	unsigned int flags);
	210	extern int __fscrypt_prepare_lookup(struct inode dir, struct dentry dentry);
a2a9032a JK	211	extern int __fscrypt_prepare_symlink(struct inode *dir, unsigned int len,
	212	unsigned int max_len,
	213	struct fscrypt_str *disk_link);
	214	extern int __fscrypt_encrypt_symlink(struct inode inode, const char target,
	215	unsigned int len,
	216	struct fscrypt_str *disk_link);
	217	extern const char fscrypt_get_symlink(struct inode inode, const void *caddr,
	218	unsigned int max_size,
	219	struct delayed_call *done);
a53dc75a	220
46f47e48	221	#endif /* _LINUX_FSCRYPT_SUPP_H */