[linux-2.6-block.git] / fs / crypto / fscrypt_private.h

/* SPDX-License-Identifier: GPL-2.0 */
/*
 * fscrypt_private.h
 *
 * Copyright (C) 2015, Google, Inc.
 *
 * This contains encryption key functions.
 *
 * Written by Michael Halcrow, Ildar Muslukhov, and Uday Savagaonkar, 2015.
 */

#ifndef _FSCRYPT_PRIVATE_H
#define _FSCRYPT_PRIVATE_H

#define __FS_HAS_ENCRYPTION 1
#include <linux/fscrypt.h>
#include <crypto/hash.h>

/* Encryption parameters */
#define FS_KEY_DERIVATION_NONCE_SIZE	16

/**
 * Encryption context for inode
 *
 * Protector format:
 *  1 byte: Protector format (1 = this version)
 *  1 byte: File contents encryption mode
 *  1 byte: File names encryption mode
 *  1 byte: Flags
 *  8 bytes: Master Key descriptor
 *  16 bytes: Encryption Key derivation nonce
 */
struct fscrypt_context {
	u8 format;
	u8 contents_encryption_mode;
	u8 filenames_encryption_mode;
	u8 flags;
	u8 master_key_descriptor[FS_KEY_DESCRIPTOR_SIZE];
	u8 nonce[FS_KEY_DERIVATION_NONCE_SIZE];
} __packed;

#define FS_ENCRYPTION_CONTEXT_FORMAT_V1		1

/**
 * For encrypted symlinks, the ciphertext length is stored at the beginning
 * of the string in little-endian format.
 */
struct fscrypt_symlink_data {
	__le16 len;
	char encrypted_path[1];
} __packed;

/*
 * fscrypt_info - the "encryption key" for an inode
 *
 * When an encrypted file's key is made available, an instance of this struct is
 * allocated and stored in ->i_crypt_info.  Once created, it remains until the
 * inode is evicted.
 */
struct fscrypt_info {

	/* The actual crypto transform used for encryption and decryption */
	struct crypto_skcipher *ci_ctfm;

	/*
	 * Cipher for ESSIV IV generation.  Only set for CBC contents
	 * encryption, otherwise is NULL.
	 */
	struct crypto_cipher *ci_essiv_tfm;

	/*
	 * Encryption mode used for this inode.  It corresponds to either
	 * ci_data_mode or ci_filename_mode, depending on the inode type.
	 */
	struct fscrypt_mode *ci_mode;

	/*
	 * If non-NULL, then this inode uses a master key directly rather than a
	 * derived key, and ci_ctfm will equal ci_master_key->mk_ctfm.
	 * Otherwise, this inode uses a derived key.
	 */
	struct fscrypt_master_key *ci_master_key;

	/* fields from the fscrypt_context */
	u8 ci_data_mode;
	u8 ci_filename_mode;
	u8 ci_flags;
	u8 ci_master_key_descriptor[FS_KEY_DESCRIPTOR_SIZE];
	u8 ci_nonce[FS_KEY_DERIVATION_NONCE_SIZE];
};

typedef enum {
	FS_DECRYPT = 0,
	FS_ENCRYPT,
} fscrypt_direction_t;

#define FS_CTX_REQUIRES_FREE_ENCRYPT_FL		0x00000001
#define FS_CTX_HAS_BOUNCE_BUFFER_FL		0x00000002

static inline bool fscrypt_valid_enc_modes(u32 contents_mode,
					   u32 filenames_mode)
{
	if (contents_mode == FS_ENCRYPTION_MODE_AES_128_CBC &&
	    filenames_mode == FS_ENCRYPTION_MODE_AES_128_CTS)
		return true;

	if (contents_mode == FS_ENCRYPTION_MODE_AES_256_XTS &&
	    filenames_mode == FS_ENCRYPTION_MODE_AES_256_CTS)
		return true;

	if (contents_mode == FS_ENCRYPTION_MODE_ADIANTUM &&
	    filenames_mode == FS_ENCRYPTION_MODE_ADIANTUM)
		return true;

	return false;
}

/* crypto.c */
extern struct kmem_cache *fscrypt_info_cachep;
extern int fscrypt_initialize(unsigned int cop_flags);
extern int fscrypt_do_page_crypto(const struct inode *inode,
				  fscrypt_direction_t rw, u64 lblk_num,
				  struct page *src_page,
				  struct page *dest_page,
				  unsigned int len, unsigned int offs,
				  gfp_t gfp_flags);
extern struct page *fscrypt_alloc_bounce_page(struct fscrypt_ctx *ctx,
					      gfp_t gfp_flags);
extern const struct dentry_operations fscrypt_d_ops;

extern void __printf(3, 4) __cold
fscrypt_msg(struct super_block *sb, const char *level, const char *fmt, ...);

#define fscrypt_warn(sb, fmt, ...)		\
	fscrypt_msg(sb, KERN_WARNING, fmt, ##__VA_ARGS__)
#define fscrypt_err(sb, fmt, ...)		\
	fscrypt_msg(sb, KERN_ERR, fmt, ##__VA_ARGS__)

#define FSCRYPT_MAX_IV_SIZE	32

union fscrypt_iv {
	struct {
		/* logical block number within the file */
		__le64 lblk_num;

		/* per-file nonce; only set in DIRECT_KEY mode */
		u8 nonce[FS_KEY_DERIVATION_NONCE_SIZE];
	};
	u8 raw[FSCRYPT_MAX_IV_SIZE];
};

void fscrypt_generate_iv(union fscrypt_iv *iv, u64 lblk_num,
			 const struct fscrypt_info *ci);

/* fname.c */
extern int fname_encrypt(struct inode *inode, const struct qstr *iname,
			 u8 *out, unsigned int olen);
extern bool fscrypt_fname_encrypted_size(const struct inode *inode,
					 u32 orig_len, u32 max_len,
					 u32 *encrypted_len_ret);

/* keyinfo.c */

struct fscrypt_mode {
	const char *friendly_name;
	const char *cipher_str;
	int keysize;
	int ivsize;
	bool logged_impl_name;
	bool needs_essiv;
};

extern void __exit fscrypt_essiv_cleanup(void);

#endif /* _FSCRYPT_PRIVATE_H */
Commit	Line	Data
b2441318	1	/* SPDX-License-Identifier: GPL-2.0 */
3325bea5 TT	2	/*
	3	* fscrypt_private.h
	4	*
	5	* Copyright (C) 2015, Google, Inc.
	6	*
	7	* This contains encryption key functions.
	8	*
	9	* Written by Michael Halcrow, Ildar Muslukhov, and Uday Savagaonkar, 2015.
	10	*/
	11
	12	#ifndef _FSCRYPT_PRIVATE_H
	13	#define _FSCRYPT_PRIVATE_H
	14
734f0d24 DC	15	#define __FS_HAS_ENCRYPTION 1
734f0d24 DC	16	#include <linux/fscrypt.h>
b7e7cf7a	17	#include <crypto/hash.h>
3325bea5	18
cc4e0df0	19	/* Encryption parameters */
11b8818e	20	#define FS_KEY_DERIVATION_NONCE_SIZE 16
cc4e0df0 TT	21
	22	/**
	23	* Encryption context for inode
	24	*
	25	* Protector format:
	26	* 1 byte: Protector format (1 = this version)
	27	* 1 byte: File contents encryption mode
	28	* 1 byte: File names encryption mode
	29	* 1 byte: Flags
	30	* 8 bytes: Master Key descriptor
	31	* 16 bytes: Encryption Key derivation nonce
	32	*/
	33	struct fscrypt_context {
	34	u8 format;
	35	u8 contents_encryption_mode;
	36	u8 filenames_encryption_mode;
	37	u8 flags;
	38	u8 master_key_descriptor[FS_KEY_DESCRIPTOR_SIZE];
	39	u8 nonce[FS_KEY_DERIVATION_NONCE_SIZE];
	40	} __packed;
	41
	42	#define FS_ENCRYPTION_CONTEXT_FORMAT_V1 1
	43
0eaab5b1 EB	44	/**
	45	* For encrypted symlinks, the ciphertext length is stored at the beginning
	46	* of the string in little-endian format.
	47	*/
	48	struct fscrypt_symlink_data {
	49	__le16 len;
	50	char encrypted_path[1];
	51	} __packed;
	52
cc4e0df0	53	/*
8094c3ce EB	54	* fscrypt_info - the "encryption key" for an inode
	55	*
	56	* When an encrypted file's key is made available, an instance of this struct is
	57	* allocated and stored in ->i_crypt_info. Once created, it remains until the
	58	* inode is evicted.
cc4e0df0 TT	59	*/
cc4e0df0 TT	60	struct fscrypt_info {
8094c3ce EB	61
	62	/* The actual crypto transform used for encryption and decryption */
	63	struct crypto_skcipher *ci_ctfm;
	64
	65	/*
	66	* Cipher for ESSIV IV generation. Only set for CBC contents
	67	* encryption, otherwise is NULL.
	68	*/
	69	struct crypto_cipher *ci_essiv_tfm;
	70
	71	/*
	72	* Encryption mode used for this inode. It corresponds to either
	73	* ci_data_mode or ci_filename_mode, depending on the inode type.
	74	*/
	75	struct fscrypt_mode *ci_mode;
	76
	77	/*
	78	* If non-NULL, then this inode uses a master key directly rather than a
	79	* derived key, and ci_ctfm will equal ci_master_key->mk_ctfm.
	80	* Otherwise, this inode uses a derived key.
	81	*/
	82	struct fscrypt_master_key *ci_master_key;
	83
	84	/* fields from the fscrypt_context */
cc4e0df0 TT	85	u8 ci_data_mode;
	86	u8 ci_filename_mode;
	87	u8 ci_flags;
8094c3ce EB	88	u8 ci_master_key_descriptor[FS_KEY_DESCRIPTOR_SIZE];
8094c3ce EB	89	u8 ci_nonce[FS_KEY_DERIVATION_NONCE_SIZE];
cc4e0df0 TT	90	};
cc4e0df0 TT	91
58ae7468 RW	92	typedef enum {
	93	FS_DECRYPT = 0,
	94	FS_ENCRYPT,
	95	} fscrypt_direction_t;
	96
cc4e0df0	97	#define FS_CTX_REQUIRES_FREE_ENCRYPT_FL 0x00000001
6a34e4d2	98	#define FS_CTX_HAS_BOUNCE_BUFFER_FL 0x00000002
cc4e0df0	99
bb8179e5 EB	100	static inline bool fscrypt_valid_enc_modes(u32 contents_mode,
	101	u32 filenames_mode)
	102	{
	103	if (contents_mode == FS_ENCRYPTION_MODE_AES_128_CBC &&
	104	filenames_mode == FS_ENCRYPTION_MODE_AES_128_CTS)
	105	return true;
	106
	107	if (contents_mode == FS_ENCRYPTION_MODE_AES_256_XTS &&
	108	filenames_mode == FS_ENCRYPTION_MODE_AES_256_CTS)
	109	return true;
	110
8094c3ce EB	111	if (contents_mode == FS_ENCRYPTION_MODE_ADIANTUM &&
	112	filenames_mode == FS_ENCRYPTION_MODE_ADIANTUM)
	113	return true;
	114
bb8179e5 EB	115	return false;
	116	}
	117
b98701df	118	/* crypto.c */
e4de782a	119	extern struct kmem_cache *fscrypt_info_cachep;
58ae7468	120	extern int fscrypt_initialize(unsigned int cop_flags);
58ae7468 RW	121	extern int fscrypt_do_page_crypto(const struct inode *inode,
	122	fscrypt_direction_t rw, u64 lblk_num,
	123	struct page *src_page,
	124	struct page *dest_page,
	125	unsigned int len, unsigned int offs,
	126	gfp_t gfp_flags);
	127	extern struct page fscrypt_alloc_bounce_page(struct fscrypt_ctx ctx,
	128	gfp_t gfp_flags);
54222025	129	extern const struct dentry_operations fscrypt_d_ops;
b98701df	130
544d08fd EB	131	extern void __printf(3, 4) __cold
	132	fscrypt_msg(struct super_block sb, const char level, const char *fmt, ...);
	133
	134	#define fscrypt_warn(sb, fmt, ...) \
	135	fscrypt_msg(sb, KERN_WARNING, fmt, ##__VA_ARGS__)
	136	#define fscrypt_err(sb, fmt, ...) \
	137	fscrypt_msg(sb, KERN_ERR, fmt, ##__VA_ARGS__)
	138
8094c3ce EB	139	#define FSCRYPT_MAX_IV_SIZE 32
	140
	141	union fscrypt_iv {
	142	struct {
	143	/* logical block number within the file */
	144	__le64 lblk_num;
	145
	146	/* per-file nonce; only set in DIRECT_KEY mode */
	147	u8 nonce[FS_KEY_DERIVATION_NONCE_SIZE];
	148	};
	149	u8 raw[FSCRYPT_MAX_IV_SIZE];
	150	};
	151
	152	void fscrypt_generate_iv(union fscrypt_iv *iv, u64 lblk_num,
	153	const struct fscrypt_info *ci);
	154
76e81d6d	155	/* fname.c */
50c961de EB	156	extern int fname_encrypt(struct inode inode, const struct qstr iname,
50c961de EB	157	u8 *out, unsigned int olen);
b9db0b4a EB	158	extern bool fscrypt_fname_encrypted_size(const struct inode *inode,
	159	u32 orig_len, u32 max_len,
	160	u32 *encrypted_len_ret);
76e81d6d	161
b7e7cf7a	162	/* keyinfo.c */
8094c3ce EB	163
	164	struct fscrypt_mode {
	165	const char *friendly_name;
	166	const char *cipher_str;
	167	int keysize;
	168	int ivsize;
	169	bool logged_impl_name;
	170	bool needs_essiv;
	171	};
	172
b7e7cf7a DW	173	extern void __exit fscrypt_essiv_cleanup(void);
b7e7cf7a DW	174
3325bea5	175	#endif /* _FSCRYPT_PRIVATE_H */