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 #ifndef ANDROID_VOLD_CRYPTFS_H 18 #define ANDROID_VOLD_CRYPTFS_H 19 20 /* This structure starts 16,384 bytes before the end of a hardware 21 * partition that is encrypted, or in a separate partition. It's location 22 * is specified by a property set in init.<device>.rc. 23 * The structure allocates 48 bytes for a key, but the real key size is 24 * specified in the struct. Currently, the code is hardcoded to use 128 25 * bit keys. 26 * The fields after salt are only valid in rev 1.1 and later stuctures. 27 * Obviously, the filesystem does not include the last 16 kbytes 28 * of the partition if the crypt_mnt_ftr lives at the end of the 29 * partition. 30 */ 31 32 #include <stdbool.h> 33 #include <stdint.h> 34 #include <cutils/properties.h> 35 36 /* The current cryptfs version */ 37 #define CURRENT_MAJOR_VERSION 1 38 #define CURRENT_MINOR_VERSION 3 39 40 #define CRYPT_FOOTER_OFFSET 0x4000 41 #define CRYPT_FOOTER_TO_PERSIST_OFFSET 0x1000 42 #define CRYPT_PERSIST_DATA_SIZE 0x1000 43 44 #define MAX_CRYPTO_TYPE_NAME_LEN 64 45 46 #define MAX_KEY_LEN 48 47 #define SALT_LEN 16 48 #define SCRYPT_LEN 32 49 50 /* definitions of flags in the structure below */ 51 #define CRYPT_MNT_KEY_UNENCRYPTED 0x1 /* The key for the partition is not encrypted. */ 52 #define CRYPT_ENCRYPTION_IN_PROGRESS 0x2 /* Encryption partially completed, 53 encrypted_upto valid*/ 54 #define CRYPT_INCONSISTENT_STATE 0x4 /* Set when starting encryption, clear when 55 exit cleanly, either through success or 56 correctly marked partial encryption */ 57 #define CRYPT_DATA_CORRUPT 0x8 /* Set when encryption is fine, but the 58 underlying volume is corrupt */ 59 #define CRYPT_FORCE_ENCRYPTION 0x10 /* Set when it is time to encrypt this 60 volume on boot. Everything in this 61 structure is set up correctly as 62 though device is encrypted except 63 that the master key is encrypted with the 64 default password. */ 65 #define CRYPT_FORCE_COMPLETE 0x20 /* Set when the above encryption cycle is 66 complete. On next cryptkeeper entry, match 67 the password. If it matches fix the master 68 key and remove this flag. */ 69 70 /* Allowed values for type in the structure below */ 71 #define CRYPT_TYPE_PASSWORD 0 /* master_key is encrypted with a password 72 * Must be zero to be compatible with pre-L 73 * devices where type is always password.*/ 74 #define CRYPT_TYPE_DEFAULT 1 /* master_key is encrypted with default 75 * password */ 76 #define CRYPT_TYPE_PATTERN 2 /* master_key is encrypted with a pattern */ 77 #define CRYPT_TYPE_PIN 3 /* master_key is encrypted with a pin */ 78 #define CRYPT_TYPE_MAX_TYPE 3 /* type cannot be larger than this value */ 79 80 #define CRYPT_MNT_MAGIC 0xD0B5B1C4 81 #define PERSIST_DATA_MAGIC 0xE950CD44 82 83 /* Key Derivation Function algorithms */ 84 #define KDF_PBKDF2 1 85 #define KDF_SCRYPT 2 86 /* Algorithms 3 & 4 deprecated before shipping outside of google, so removed */ 87 #define KDF_SCRYPT_KEYMASTER 5 88 89 /* Maximum allowed keymaster blob size. */ 90 #define KEYMASTER_BLOB_SIZE 2048 91 92 /* __le32 and __le16 defined in system/extras/ext4_utils/ext4_utils.h */ 93 #define __le8 unsigned char 94 95 #if !defined(SHA256_DIGEST_LENGTH) 96 #define SHA256_DIGEST_LENGTH 32 97 #endif 98 99 struct crypt_mnt_ftr { 100 __le32 magic; /* See above */ 101 __le16 major_version; 102 __le16 minor_version; 103 __le32 ftr_size; /* in bytes, not including key following */ 104 __le32 flags; /* See above */ 105 __le32 keysize; /* in bytes */ 106 __le32 crypt_type; /* how master_key is encrypted. Must be a 107 * CRYPT_TYPE_XXX value */ 108 __le64 fs_size; /* Size of the encrypted fs, in 512 byte sectors */ 109 __le32 failed_decrypt_count; /* count of # of failed attempts to decrypt and 110 mount, set to 0 on successful mount */ 111 unsigned char crypto_type_name[MAX_CRYPTO_TYPE_NAME_LEN]; /* The type of encryption 112 needed to decrypt this 113 partition, null terminated */ 114 __le32 spare2; /* ignored */ 115 unsigned char master_key[MAX_KEY_LEN]; /* The encrypted key for decrypting the filesystem */ 116 unsigned char salt[SALT_LEN]; /* The salt used for this encryption */ 117 __le64 persist_data_offset[2]; /* Absolute offset to both copies of crypt_persist_data 118 * on device with that info, either the footer of the 119 * real_blkdevice or the metadata partition. */ 120 121 __le32 persist_data_size; /* The number of bytes allocated to each copy of the 122 * persistent data table*/ 123 124 __le8 kdf_type; /* The key derivation function used. */ 125 126 /* scrypt parameters. See www.tarsnap.com/scrypt/scrypt.pdf */ 127 __le8 N_factor; /* (1 << N) */ 128 __le8 r_factor; /* (1 << r) */ 129 __le8 p_factor; /* (1 << p) */ 130 __le64 encrypted_upto; /* If we are in state CRYPT_ENCRYPTION_IN_PROGRESS and 131 we have to stop (e.g. power low) this is the last 132 encrypted 512 byte sector.*/ 133 __le8 hash_first_block[SHA256_DIGEST_LENGTH]; /* When CRYPT_ENCRYPTION_IN_PROGRESS 134 set, hash of first block, used 135 to validate before continuing*/ 136 137 /* key_master key, used to sign the derived key which is then used to generate 138 * the intermediate key 139 * This key should be used for no other purposes! We use this key to sign unpadded 140 * data, which is acceptable but only if the key is not reused elsewhere. */ 141 __le8 keymaster_blob[KEYMASTER_BLOB_SIZE]; 142 __le32 keymaster_blob_size; 143 144 /* Store scrypt of salted intermediate key. When decryption fails, we can 145 check if this matches, and if it does, we know that the problem is with the 146 drive, and there is no point in asking the user for more passwords. 147 148 Note that if any part of this structure is corrupt, this will not match and 149 we will continue to believe the user entered the wrong password. In that 150 case the only solution is for the user to enter a password enough times to 151 force a wipe. 152 153 Note also that there is no need to worry about migration. If this data is 154 wrong, we simply won't recognise a right password, and will continue to 155 prompt. On the first password change, this value will be populated and 156 then we will be OK. 157 */ 158 unsigned char scrypted_intermediate_key[SCRYPT_LEN]; 159 160 /* sha of this structure with this element set to zero 161 Used when encrypting on reboot to validate structure before doing something 162 fatal 163 */ 164 unsigned char sha256[SHA256_DIGEST_LENGTH]; 165 }; 166 167 /* Persistant data that should be available before decryption. 168 * Things like airplane mode, locale and timezone are kept 169 * here and can be retrieved by the CryptKeeper UI to properly 170 * configure the phone before asking for the password 171 * This is only valid if the major and minor version above 172 * is set to 1.1 or higher. 173 * 174 * This is a 4K structure. There are 2 copies, and the code alternates 175 * writing one and then clearing the previous one. The reading 176 * code reads the first valid copy it finds, based on the magic number. 177 * The absolute offset to the first of the two copies is kept in rev 1.1 178 * and higher crypt_mnt_ftr structures. 179 */ 180 struct crypt_persist_entry { 181 char key[PROPERTY_KEY_MAX]; 182 char val[PROPERTY_VALUE_MAX]; 183 }; 184 185 /* Should be exactly 4K in size */ 186 struct crypt_persist_data { 187 __le32 persist_magic; 188 __le32 persist_valid_entries; 189 __le32 persist_spare[30]; 190 struct crypt_persist_entry persist_entry[0]; 191 }; 192 193 #define DATA_MNT_POINT "/data" 194 195 /* Return values for cryptfs_crypto_complete */ 196 #define CRYPTO_COMPLETE_NOT_ENCRYPTED 1 197 #define CRYPTO_COMPLETE_ENCRYPTED 0 198 #define CRYPTO_COMPLETE_BAD_METADATA (-1) 199 #define CRYPTO_COMPLETE_PARTIAL (-2) 200 #define CRYPTO_COMPLETE_INCONSISTENT (-3) 201 #define CRYPTO_COMPLETE_CORRUPT (-4) 202 203 /* Return values for cryptfs_enable_inplace*() */ 204 #define ENABLE_INPLACE_OK 0 205 #define ENABLE_INPLACE_ERR_OTHER (-1) 206 #define ENABLE_INPLACE_ERR_DEV (-2) /* crypto_blkdev issue */ 207 208 /* Return values for cryptfs_getfield */ 209 #define CRYPTO_GETFIELD_OK 0 210 #define CRYPTO_GETFIELD_ERROR_NO_FIELD (-1) 211 #define CRYPTO_GETFIELD_ERROR_OTHER (-2) 212 #define CRYPTO_GETFIELD_ERROR_BUF_TOO_SMALL (-3) 213 214 /* Return values for cryptfs_setfield */ 215 #define CRYPTO_SETFIELD_OK 0 216 #define CRYPTO_SETFIELD_ERROR_OTHER (-1) 217 #define CRYPTO_SETFIELD_ERROR_FIELD_TOO_LONG (-2) 218 #define CRYPTO_SETFIELD_ERROR_VALUE_TOO_LONG (-3) 219 220 /* Return values for persist_del_key */ 221 #define PERSIST_DEL_KEY_OK 0 222 #define PERSIST_DEL_KEY_ERROR_OTHER (-1) 223 #define PERSIST_DEL_KEY_ERROR_NO_FIELD (-2) 224 225 int match_multi_entry(const char* key, const char* field, unsigned index); 226 int wait_and_unmount(const char* mountpoint, bool kill); 227 228 typedef int (*kdf_func)(const char* passwd, const unsigned char* salt, unsigned char* ikey, 229 void* params); 230 231 int cryptfs_crypto_complete(void); 232 int cryptfs_check_passwd(const char* pw); 233 int cryptfs_verify_passwd(const char* pw); 234 int cryptfs_restart(void); 235 int cryptfs_enable(int type, const char* passwd, int no_ui); 236 int cryptfs_changepw(int type, const char* newpw); 237 int cryptfs_enable_default(int no_ui); 238 int cryptfs_setup_ext_volume(const char* label, const char* real_blkdev, const unsigned char* key, 239 char* out_crypto_blkdev); 240 int cryptfs_revert_ext_volume(const char* label); 241 int cryptfs_getfield(const char* fieldname, char* value, int len); 242 int cryptfs_setfield(const char* fieldname, const char* value); 243 int cryptfs_mount_default_encrypted(void); 244 int cryptfs_get_password_type(void); 245 const char* cryptfs_get_password(void); 246 void cryptfs_clear_password(void); 247 int cryptfs_isConvertibleToFBE(void); 248 249 uint32_t cryptfs_get_keysize(); 250 const char* cryptfs_get_crypto_name(); 251 252 #endif /* ANDROID_VOLD_CRYPTFS_H */ 253
