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/*
* Copyright (C) 2017 sigma star gmbh
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 as published by
* the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
* more details.
*
* You should have received a copy of the GNU General Public License along with
* this program; if not, write to the Free Software Foundation, Inc., 51
* Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*
* Authors: Richard Weinberger <richard@sigma-star.at>
* David Oberhollenzer <david.oberhollenzer@sigma-star.at>
*/
#ifndef FSCRYPT_H
#define FSCRYPT_H
#include "mkfs.ubifs.h"
#include <sys/types.h>
#include "crypto.h"
#ifndef FS_KEY_DESCRIPTOR_SIZE
#define FS_KEY_DESCRIPTOR_SIZE 8
#endif
#define FS_ENCRYPTION_CONTEXT_FORMAT_V1 1
#define FS_KEY_DERIVATION_NONCE_SIZE 16
#ifndef FS_ENCRYPTION_MODE_AES_256_XTS
#define FS_ENCRYPTION_MODE_AES_256_XTS 1
#endif
#ifndef FS_ENCRYPTION_MODE_AES_256_CTS
#define FS_ENCRYPTION_MODE_AES_256_CTS 4
#endif
#ifndef FS_ENCRYPTION_MODE_AES_128_CBC
#define FS_ENCRYPTION_MODE_AES_128_CBC 5
#endif
#ifndef FS_ENCRYPTION_MODE_AES_128_CTS
#define FS_ENCRYPTION_MODE_AES_128_CTS 6
#endif
#ifndef FS_POLICY_FLAGS_VALID
#define FS_POLICY_FLAGS_PAD_4 0x00
#define FS_POLICY_FLAGS_PAD_8 0x01
#define FS_POLICY_FLAGS_PAD_16 0x02
#define FS_POLICY_FLAGS_PAD_32 0x03
#define FS_POLICY_FLAGS_PAD_MASK 0x03
#define FS_POLICY_FLAGS_VALID 0x03
#endif
#define FS_CRYPTO_BLOCK_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];
} __attribute__((packed));
/**
* 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];
} __attribute__((packed));
#ifndef FS_MAX_KEY_SIZE
#define FS_MAX_KEY_SIZE 64
#endif
unsigned char *calc_fscrypt_subkey(struct fscrypt_context *fctx);
struct fscrypt_context *inherit_fscrypt_context(struct fscrypt_context *fctx);
void free_fscrypt_context(struct fscrypt_context *fctx);
void print_fscrypt_master_key_descriptor(struct fscrypt_context *fctx);
unsigned int fscrypt_fname_encrypted_size(struct fscrypt_context *fctx,
unsigned int ilen);
int encrypt_path(void **outbuf, void *data, unsigned int data_len,
unsigned int max_namelen, struct fscrypt_context *fctx);
int encrypt_data_node(struct fscrypt_context *fctx, unsigned int block_no,
struct ubifs_data_node *dn, size_t length);
struct fscrypt_context *init_fscrypt_context(const char *cipher_name,
unsigned int flags,
const char *key_file,
const char *key_descriptor);
#endif /* FSCRYPT_H */
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