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/*
* 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_IV_SIZE 16
#define FS_AES_128_ECB_KEY_SIZE 16
#define FS_AES_128_CBC_KEY_SIZE 16
#define FS_AES_128_CTS_KEY_SIZE 16
#define FS_AES_256_GCM_KEY_SIZE 32
#define FS_AES_256_CBC_KEY_SIZE 32
#define FS_AES_256_CTS_KEY_SIZE 32
#define FS_AES_256_XTS_KEY_SIZE 64
#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;
/*
* A pointer to this structure is stored in the file system's in-core
* representation of an inode.
*/
struct fscrypt_info {
u8 ci_data_mode;
u8 ci_filename_mode;
u8 ci_flags;
struct crypto_skcipher *ci_ctfm;
struct crypto_cipher *ci_essiv_tfm;
u8 ci_master_key[FS_KEY_DESCRIPTOR_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
/* bio stuffs */
#define REQ_OP_READ READ
#define REQ_OP_WRITE WRITE
#define bio_op(bio) ((bio)->bi_rw & 1)
static inline void bio_set_op_attrs(struct bio *bio, unsigned op,
unsigned op_flags)
{
bio->bi_rw = op | op_flags;
}
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;
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);
/* 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 */
extern void __exit fscrypt_essiv_cleanup(void);
#endif /* _FSCRYPT_PRIVATE_H */
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