[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

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