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Diffstat (limited to 'crypto/fde/cryptfs.h')
| -rw-r--r-- | crypto/fde/cryptfs.h | 208 |
1 files changed, 208 insertions, 0 deletions
diff --git a/crypto/fde/cryptfs.h b/crypto/fde/cryptfs.h new file mode 100644 index 000000000..c67113a75 --- /dev/null +++ b/crypto/fde/cryptfs.h @@ -0,0 +1,208 @@ +/* + * 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. + */ + +#ifndef ANDROID_VOLD_CRYPTFS_H +#define ANDROID_VOLD_CRYPTFS_H + +/* This structure starts 16,384 bytes before the end of a hardware + * partition that is encrypted, or in a separate partition. It's location + * is specified by a property set in init.<device>.rc. + * The structure allocates 48 bytes for a key, but the real key size is + * specified in the struct. Currently, the code is hardcoded to use 128 + * bit keys. + * The fields after salt are only valid in rev 1.1 and later stuctures. + * Obviously, the filesystem does not include the last 16 kbytes + * of the partition if the crypt_mnt_ftr lives at the end of the + * partition. + */ + +#include <stdbool.h> +#include <stdint.h> +#include <cutils/properties.h> + +/* The current cryptfs version */ +#define CURRENT_MAJOR_VERSION 1 +#define CURRENT_MINOR_VERSION 3 + +#define CRYPT_FOOTER_OFFSET 0x4000 +#define CRYPT_FOOTER_TO_PERSIST_OFFSET 0x1000 +#define CRYPT_PERSIST_DATA_SIZE 0x1000 + +#define MAX_CRYPTO_TYPE_NAME_LEN 64 + +#define MAX_KEY_LEN 48 +#define SALT_LEN 16 +#define SCRYPT_LEN 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 /* Encryption partially completed, + encrypted_upto valid*/ +#define CRYPT_INCONSISTENT_STATE 0x4 /* Set when starting encryption, clear when + exit cleanly, either through success or + correctly marked partial encryption */ +#define CRYPT_DATA_CORRUPT 0x8 /* Set when encryption is fine, but the + underlying volume is corrupt */ +#define CRYPT_FORCE_ENCRYPTION 0x10 /* Set when it is time to encrypt this + volume on boot. Everything in this + structure is set up correctly as + though device is encrypted except + that the master key is encrypted with the + default password. */ +#define CRYPT_FORCE_COMPLETE 0x20 /* Set when the above encryption cycle is + complete. On next cryptkeeper entry, match + the password. If it matches fix the master + key and remove this flag. */ +#ifdef CONFIG_HW_DISK_ENCRYPTION +/* This flag is used to transition from L->M upgrade. L release passed + * a byte for every nible of user password while M release is passing + * ascii value of user password. + * Random flag value is chosen so that it does not conflict with other use cases + */ +#define CRYPT_ASCII_PASSWORD_UPDATED 0x1000 +#endif + +/* Allowed values for type in the structure below */ +#define CRYPT_TYPE_PASSWORD 0 /* master_key is encrypted with a password + * Must be zero to be compatible with pre-L + * devices where type is always password.*/ +#define CRYPT_TYPE_DEFAULT 1 /* master_key is encrypted with default + * password */ +#define CRYPT_TYPE_PATTERN 2 /* master_key is encrypted with a pattern */ +#define CRYPT_TYPE_PIN 3 /* master_key is encrypted with a pin */ +#define CRYPT_TYPE_MAX_TYPE 3 /* type cannot be larger than this value */ + +#define CRYPT_MNT_MAGIC 0xD0B5B1C4 +#define PERSIST_DATA_MAGIC 0xE950CD44 + +/* Key Derivation Function algorithms */ +#define KDF_PBKDF2 1 +#define KDF_SCRYPT 2 +/* Algorithms 3 & 4 deprecated before shipping outside of google, so removed */ +#define KDF_SCRYPT_KEYMASTER_UNPADDED 3 +#define KDF_SCRYPT_KEYMASTER_BADLY_PADDED 4 +#define KDF_SCRYPT_KEYMASTER 5 + +/* Maximum allowed keymaster blob size. */ +#define KEYMASTER_BLOB_SIZE 2048 + +/* __le32 and __le16 defined in system/extras/ext4_utils/ext4_utils.h */ +#define __le8 unsigned char + +#if !defined(SHA256_DIGEST_LENGTH) +#define SHA256_DIGEST_LENGTH 32 +#endif + +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 crypt_type; /* how master_key is encrypted. Must be a + * CRYPT_TYPE_XXX value */ + __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 */ + __le32 spare2; /* ignored */ + unsigned char master_key[MAX_KEY_LEN]; /* The encrypted key for decrypting the filesystem */ + unsigned char salt[SALT_LEN]; /* The salt used for this encryption */ + __le64 persist_data_offset[2]; /* Absolute offset to both copies of crypt_persist_data + * on device with that info, either the footer of the + * real_blkdevice or the metadata partition. */ + + __le32 persist_data_size; /* The number of bytes allocated to each copy of the + * persistent data table*/ + + __le8 kdf_type; /* The key derivation function used. */ + + /* scrypt parameters. See www.tarsnap.com/scrypt/scrypt.pdf */ + __le8 N_factor; /* (1 << N) */ + __le8 r_factor; /* (1 << r) */ + __le8 p_factor; /* (1 << p) */ + __le64 encrypted_upto; /* If we are in state CRYPT_ENCRYPTION_IN_PROGRESS and + we have to stop (e.g. power low) this is the last + encrypted 512 byte sector.*/ + __le8 hash_first_block[SHA256_DIGEST_LENGTH]; /* When CRYPT_ENCRYPTION_IN_PROGRESS + set, hash of first block, used + to validate before continuing*/ + + /* key_master key, used to sign the derived key which is then used to generate + * the intermediate key + * This key should be used for no other purposes! We use this key to sign unpadded + * data, which is acceptable but only if the key is not reused elsewhere. */ + __le8 keymaster_blob[KEYMASTER_BLOB_SIZE]; + __le32 keymaster_blob_size; + + /* Store scrypt of salted intermediate key. When decryption fails, we can + check if this matches, and if it does, we know that the problem is with the + drive, and there is no point in asking the user for more passwords. + + Note that if any part of this structure is corrupt, this will not match and + we will continue to believe the user entered the wrong password. In that + case the only solution is for the user to enter a password enough times to + force a wipe. + + Note also that there is no need to worry about migration. If this data is + wrong, we simply won't recognise a right password, and will continue to + prompt. On the first password change, this value will be populated and + then we will be OK. + */ + unsigned char scrypted_intermediate_key[SCRYPT_LEN]; + + /* sha of this structure with this element set to zero + Used when encrypting on reboot to validate structure before doing something + fatal + */ + unsigned char sha256[SHA256_DIGEST_LENGTH]; +}; + +#define DATA_MNT_POINT "/data" + +/* Return values for cryptfs_crypto_complete */ +#define CRYPTO_COMPLETE_NOT_ENCRYPTED 1 +#define CRYPTO_COMPLETE_ENCRYPTED 0 +#define CRYPTO_COMPLETE_BAD_METADATA (-1) +#define CRYPTO_COMPLETE_PARTIAL (-2) +#define CRYPTO_COMPLETE_INCONSISTENT (-3) +#define CRYPTO_COMPLETE_CORRUPT (-4) + +/* Return values for cryptfs_enable_inplace*() */ +#define ENABLE_INPLACE_OK 0 +#define ENABLE_INPLACE_ERR_OTHER (-1) +#define ENABLE_INPLACE_ERR_DEV (-2) /* crypto_blkdev issue */ + +typedef int (*kdf_func)(const char* passwd, const unsigned char* salt, unsigned char* ikey, + void* params); + +int cryptfs_check_passwd(const char* pw); +int cryptfs_verify_passwd(const char* pw); +int cryptfs_setup_ext_volume(const char* label, const char* real_blkdev, const unsigned char* key, int keysize, char* out_crypto_blkdev); +int cryptfs_revert_ext_volume(const char* label); +int cryptfs_get_password_type(void); + +uint32_t cryptfs_get_keysize(); +const char* cryptfs_get_crypto_name(); + +void set_partition_data(const char* block_device, const char* key_location, const char* fs); +int cryptfs_check_footer(); +int delete_crypto_blk_dev(const char *name); + +#endif /* ANDROID_VOLD_CRYPTFS_H */ |