1 /* 2 * Copyright (C) 2010 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 /* This structure starts 16,384 bytes before the end of a hardware 18 * partition that is encrypted, or in a separate partition. It's location 19 * is specified by a property set in init.<device>.rc. 20 * The structure allocates 48 bytes for a key, but the real key size is 21 * specified in the struct. Currently, the code is hardcoded to use 128 22 * bit keys. 23 * The fields after salt are only valid in rev 1.1 and later stuctures. 24 * Obviously, the filesystem does not include the last 16 kbytes 25 * of the partition if the crypt_mnt_ftr lives at the end of the 26 * partition. 27 */ 28 29 #include <cutils/properties.h> 30 31 /* The current cryptfs version */ 32 #define CURRENT_MAJOR_VERSION 1 33 #define CURRENT_MINOR_VERSION 2 34 35 #define CRYPT_FOOTER_OFFSET 0x4000 36 #define CRYPT_FOOTER_TO_PERSIST_OFFSET 0x1000 37 #define CRYPT_PERSIST_DATA_SIZE 0x1000 38 39 #define MAX_CRYPTO_TYPE_NAME_LEN 64 40 41 #define MAX_KEY_LEN 48 42 #define SALT_LEN 16 43 44 /* definitions of flags in the structure below */ 45 #define CRYPT_MNT_KEY_UNENCRYPTED 0x1 /* The key for the partition is not encrypted. */ 46 #define CRYPT_ENCRYPTION_IN_PROGRESS 0x2 /* Set when starting encryption, 47 * clear when done before rebooting */ 48 49 #define CRYPT_MNT_MAGIC 0xD0B5B1C4 50 #define PERSIST_DATA_MAGIC 0xE950CD44 51 52 #define SCRYPT_PROP "ro.crypto.scrypt_params" 53 #define SCRYPT_DEFAULTS { 15, 3, 1 } 54 55 /* Key Derivation Function algorithms */ 56 #define KDF_PBKDF2 1 57 #define KDF_SCRYPT 2 58 59 #define __le32 unsigned int 60 #define __le16 unsigned short int 61 #define __le8 unsigned char 62 63 struct crypt_mnt_ftr { 64 __le32 magic; /* See above */ 65 __le16 major_version; 66 __le16 minor_version; 67 __le32 ftr_size; /* in bytes, not including key following */ 68 __le32 flags; /* See above */ 69 __le32 keysize; /* in bytes */ 70 __le32 spare1; /* ignored */ 71 __le64 fs_size; /* Size of the encrypted fs, in 512 byte sectors */ 72 __le32 failed_decrypt_count; /* count of # of failed attempts to decrypt and 73 mount, set to 0 on successful mount */ 74 unsigned char crypto_type_name[MAX_CRYPTO_TYPE_NAME_LEN]; /* The type of encryption 75 needed to decrypt this 76 partition, null terminated */ 77 __le32 spare2; /* ignored */ 78 unsigned char master_key[MAX_KEY_LEN]; /* The encrypted key for decrypting the filesystem */ 79 unsigned char salt[SALT_LEN]; /* The salt used for this encryption */ 80 __le64 persist_data_offset[2]; /* Absolute offset to both copies of crypt_persist_data 81 * on device with that info, either the footer of the 82 * real_blkdevice or the metadata partition. */ 83 84 __le32 persist_data_size; /* The number of bytes allocated to each copy of the 85 * persistent data table*/ 86 87 __le8 kdf_type; /* The key derivation function used. */ 88 89 /* scrypt parameters. See www.tarsnap.com/scrypt/scrypt.pdf */ 90 __le8 N_factor; /* (1 << N) */ 91 __le8 r_factor; /* (1 << r) */ 92 __le8 p_factor; /* (1 << p) */ 93 }; 94 95 /* Persistant data that should be available before decryption. 96 * Things like airplane mode, locale and timezone are kept 97 * here and can be retrieved by the CryptKeeper UI to properly 98 * configure the phone before asking for the password 99 * This is only valid if the major and minor version above 100 * is set to 1.1 or higher. 101 * 102 * This is a 4K structure. There are 2 copies, and the code alternates 103 * writing one and then clearing the previous one. The reading 104 * code reads the first valid copy it finds, based on the magic number. 105 * The absolute offset to the first of the two copies is kept in rev 1.1 106 * and higher crypt_mnt_ftr structures. 107 */ 108 struct crypt_persist_entry { 109 char key[PROPERTY_KEY_MAX]; 110 char val[PROPERTY_VALUE_MAX]; 111 }; 112 113 /* Should be exactly 4K in size */ 114 struct crypt_persist_data { 115 __le32 persist_magic; 116 __le32 persist_valid_entries; 117 __le32 persist_spare[30]; 118 struct crypt_persist_entry persist_entry[0]; 119 }; 120 121 struct volume_info { 122 unsigned int size; 123 unsigned int flags; 124 struct crypt_mnt_ftr crypt_ftr; 125 char mnt_point[256]; 126 char blk_dev[256]; 127 char crypto_blkdev[256]; 128 char label[256]; 129 }; 130 #define VOL_NONREMOVABLE 0x1 131 #define VOL_ENCRYPTABLE 0x2 132 #define VOL_PRIMARY 0x4 133 #define VOL_PROVIDES_ASEC 0x8 134 135 #ifdef __cplusplus 136 extern "C" { 137 #endif 138 139 typedef void (*kdf_func)(char *passwd, unsigned char *salt, unsigned char *ikey, void *params); 140 141 int cryptfs_crypto_complete(void); 142 int cryptfs_check_passwd(char *pw); 143 int cryptfs_verify_passwd(char *newpw); 144 int cryptfs_restart(void); 145 int cryptfs_enable(char *flag, char *passwd); 146 int cryptfs_changepw(char *newpw); 147 int cryptfs_setup_volume(const char *label, int major, int minor, 148 char *crypto_dev_path, unsigned int max_pathlen, 149 int *new_major, int *new_minor); 150 int cryptfs_revert_volume(const char *label); 151 int cryptfs_getfield(char *fieldname, char *value, int len); 152 int cryptfs_setfield(char *fieldname, char *value); 153 #ifdef __cplusplus 154 } 155 #endif 156 157