platform_system_vold/cryptfs.h
Ken Sumrall 29d8da8cef vold: allow to store key in a file on another partition
Add support for keeping the keys in a separate file on another partition,
for devices with no space reserved for a footer after the userdata filesystem.

Add support for encrypting the volumes managed by vold, if they meet certain
criteria, namely being marked as nonremovable and encryptable in vold.fstab.
A bit of trickiness is required to keep vold happy.

Change-Id: Idf0611f74b56c1026c45742ca82e0c26e58828fe
2011-06-02 16:30:14 -07:00

87 lines
2.9 KiB
C

/*
* Copyright (C) 2010 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/* This structure starts 16,384 bytes before the end of a hardware
* partition that is encrypted.
* Immediately following this structure is the encrypted key.
* The keysize field tells how long the key is, in bytes.
* Then there is 32 bytes of padding,
* Finally there is the salt used with the user password.
* The salt is fixed at 16 bytes long.
* Obviously, the filesystem does not include the last 16 kbytes
* of the partition.
*/
#define CRYPT_FOOTER_OFFSET 0x4000
#define MAX_CRYPTO_TYPE_NAME_LEN 64
#define SALT_LEN 16
#define KEY_TO_SALT_PADDING 32
/* definitions of flags in the structure below */
#define CRYPT_MNT_KEY_UNENCRYPTED 0x1 /* The key for the partition is not encrypted. */
#define CRYPT_ENCRYPTION_IN_PROGRESS 0x2 /* Set when starting encryption,
* clear when done before rebooting */
#define CRYPT_MNT_MAGIC 0xD0B5B1C4
#define __le32 unsigned int
#define __le16 unsigned short int
struct crypt_mnt_ftr {
__le32 magic; /* See above */
__le16 major_version;
__le16 minor_version;
__le32 ftr_size; /* in bytes, not including key following */
__le32 flags; /* See above */
__le32 keysize; /* in bytes */
__le32 spare1; /* ignored */
__le64 fs_size; /* Size of the encrypted fs, in 512 byte sectors */
__le32 failed_decrypt_count; /* count of # of failed attempts to decrypt and
mount, set to 0 on successful mount */
unsigned char crypto_type_name[MAX_CRYPTO_TYPE_NAME_LEN]; /* The type of encryption
needed to decrypt this
partition, null terminated */
};
struct volume_info {
unsigned int size;
unsigned int flags;
struct crypt_mnt_ftr crypt_ftr;
char mnt_point[256];
char blk_dev[256];
char crypto_blkdev[256];
char label[256];
};
#define VOL_NONREMOVABLE 0x1
#define VOL_ENCRYPTABLE 0x2
#ifdef __cplusplus
extern "C" {
#endif
int cryptfs_crypto_complete(void);
int cryptfs_check_passwd(char *pw);
int cryptfs_restart(void);
int cryptfs_enable(char *flag, char *passwd);
int cryptfs_changepw(char *newpw);
int cryptfs_setup_volume(const char *label, int major, int minor,
char *crypto_dev_path, unsigned int max_pathlen,
int *new_major, int *new_minor);
#ifdef __cplusplus
}
#endif