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259 lines
11 KiB
259 lines
11 KiB
/* |
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* Copyright (C) 2010 The Android Open Source Project |
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* |
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* Licensed under the Apache License, Version 2.0 (the "License"); |
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* you may not use this file except in compliance with the License. |
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* You may obtain a copy of the License at |
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* |
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* http://www.apache.org/licenses/LICENSE-2.0 |
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* |
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* Unless required by applicable law or agreed to in writing, software |
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* distributed under the License is distributed on an "AS IS" BASIS, |
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
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* See the License for the specific language governing permissions and |
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* limitations under the License. |
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*/ |
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/* This structure starts 16,384 bytes before the end of a hardware |
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* partition that is encrypted, or in a separate partition. It's location |
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* is specified by a property set in init.<device>.rc. |
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* The structure allocates 48 bytes for a key, but the real key size is |
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* specified in the struct. Currently, the code is hardcoded to use 128 |
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* bit keys. |
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* The fields after salt are only valid in rev 1.1 and later stuctures. |
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* Obviously, the filesystem does not include the last 16 kbytes |
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* of the partition if the crypt_mnt_ftr lives at the end of the |
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* partition. |
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*/ |
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#include <stdbool.h> |
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#include <cutils/properties.h> |
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/* The current cryptfs version */ |
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#define CURRENT_MAJOR_VERSION 1 |
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#define CURRENT_MINOR_VERSION 3 |
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#define CRYPT_FOOTER_OFFSET 0x4000 |
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#define CRYPT_FOOTER_TO_PERSIST_OFFSET 0x1000 |
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#define CRYPT_PERSIST_DATA_SIZE 0x1000 |
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#define MAX_CRYPTO_TYPE_NAME_LEN 64 |
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#define MAX_KEY_LEN 48 |
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#define SALT_LEN 16 |
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#define SCRYPT_LEN 32 |
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/* definitions of flags in the structure below */ |
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#define CRYPT_MNT_KEY_UNENCRYPTED 0x1 /* The key for the partition is not encrypted. */ |
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#define CRYPT_ENCRYPTION_IN_PROGRESS 0x2 /* Encryption partially completed, |
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encrypted_upto valid*/ |
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#define CRYPT_INCONSISTENT_STATE 0x4 /* Set when starting encryption, clear when |
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exit cleanly, either through success or |
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correctly marked partial encryption */ |
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#define CRYPT_DATA_CORRUPT 0x8 /* Set when encryption is fine, but the |
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underlying volume is corrupt */ |
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#define CRYPT_FORCE_ENCRYPTION 0x10 /* Set when it is time to encrypt this |
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volume on boot. Everything in this |
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structure is set up correctly as |
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though device is encrypted except |
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that the master key is encrypted with the |
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default password. */ |
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#define CRYPT_FORCE_COMPLETE 0x20 /* Set when the above encryption cycle is |
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complete. On next cryptkeeper entry, match |
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the password. If it matches fix the master |
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key and remove this flag. */ |
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/* Allowed values for type in the structure below */ |
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#define CRYPT_TYPE_PASSWORD 0 /* master_key is encrypted with a password |
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* Must be zero to be compatible with pre-L |
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* devices where type is always password.*/ |
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#define CRYPT_TYPE_DEFAULT 1 /* master_key is encrypted with default |
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* password */ |
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#define CRYPT_TYPE_PATTERN 2 /* master_key is encrypted with a pattern */ |
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#define CRYPT_TYPE_PIN 3 /* master_key is encrypted with a pin */ |
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#define CRYPT_TYPE_MAX_TYPE 3 /* type cannot be larger than this value */ |
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#define CRYPT_MNT_MAGIC 0xD0B5B1C4 |
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#define PERSIST_DATA_MAGIC 0xE950CD44 |
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/* Key Derivation Function algorithms */ |
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#define KDF_PBKDF2 1 |
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#define KDF_SCRYPT 2 |
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/* Algorithms 3 & 4 deprecated before shipping outside of google, so removed */ |
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#define KDF_SCRYPT_KEYMASTER 5 |
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/* Maximum allowed keymaster blob size. */ |
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#define KEYMASTER_BLOB_SIZE 2048 |
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/* __le32 and __le16 defined in system/extras/ext4_utils/ext4_utils.h */ |
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#define __le8 unsigned char |
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#if !defined(SHA256_DIGEST_LENGTH) |
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#define SHA256_DIGEST_LENGTH 32 |
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#endif |
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struct crypt_mnt_ftr { |
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__le32 magic; /* See above */ |
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__le16 major_version; |
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__le16 minor_version; |
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__le32 ftr_size; /* in bytes, not including key following */ |
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__le32 flags; /* See above */ |
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__le32 keysize; /* in bytes */ |
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__le32 crypt_type; /* how master_key is encrypted. Must be a |
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* CRYPT_TYPE_XXX value */ |
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__le64 fs_size; /* Size of the encrypted fs, in 512 byte sectors */ |
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__le32 failed_decrypt_count; /* count of # of failed attempts to decrypt and |
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mount, set to 0 on successful mount */ |
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unsigned char crypto_type_name[MAX_CRYPTO_TYPE_NAME_LEN]; /* The type of encryption |
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needed to decrypt this |
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partition, null terminated */ |
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__le32 spare2; /* ignored */ |
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unsigned char master_key[MAX_KEY_LEN]; /* The encrypted key for decrypting the filesystem */ |
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unsigned char salt[SALT_LEN]; /* The salt used for this encryption */ |
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__le64 persist_data_offset[2]; /* Absolute offset to both copies of crypt_persist_data |
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* on device with that info, either the footer of the |
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* real_blkdevice or the metadata partition. */ |
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__le32 persist_data_size; /* The number of bytes allocated to each copy of the |
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* persistent data table*/ |
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__le8 kdf_type; /* The key derivation function used. */ |
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/* scrypt parameters. See www.tarsnap.com/scrypt/scrypt.pdf */ |
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__le8 N_factor; /* (1 << N) */ |
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__le8 r_factor; /* (1 << r) */ |
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__le8 p_factor; /* (1 << p) */ |
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__le64 encrypted_upto; /* If we are in state CRYPT_ENCRYPTION_IN_PROGRESS and |
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we have to stop (e.g. power low) this is the last |
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encrypted 512 byte sector.*/ |
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__le8 hash_first_block[SHA256_DIGEST_LENGTH]; /* When CRYPT_ENCRYPTION_IN_PROGRESS |
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set, hash of first block, used |
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to validate before continuing*/ |
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/* key_master key, used to sign the derived key which is then used to generate |
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* the intermediate key |
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* This key should be used for no other purposes! We use this key to sign unpadded |
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* data, which is acceptable but only if the key is not reused elsewhere. */ |
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__le8 keymaster_blob[KEYMASTER_BLOB_SIZE]; |
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__le32 keymaster_blob_size; |
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/* Store scrypt of salted intermediate key. When decryption fails, we can |
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check if this matches, and if it does, we know that the problem is with the |
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drive, and there is no point in asking the user for more passwords. |
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Note that if any part of this structure is corrupt, this will not match and |
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we will continue to believe the user entered the wrong password. In that |
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case the only solution is for the user to enter a password enough times to |
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force a wipe. |
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Note also that there is no need to worry about migration. If this data is |
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wrong, we simply won't recognise a right password, and will continue to |
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prompt. On the first password change, this value will be populated and |
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then we will be OK. |
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*/ |
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unsigned char scrypted_intermediate_key[SCRYPT_LEN]; |
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/* sha of this structure with this element set to zero |
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Used when encrypting on reboot to validate structure before doing something |
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fatal |
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*/ |
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unsigned char sha256[SHA256_DIGEST_LENGTH]; |
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}; |
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/* Persistant data that should be available before decryption. |
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* Things like airplane mode, locale and timezone are kept |
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* here and can be retrieved by the CryptKeeper UI to properly |
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* configure the phone before asking for the password |
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* This is only valid if the major and minor version above |
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* is set to 1.1 or higher. |
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* |
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* This is a 4K structure. There are 2 copies, and the code alternates |
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* writing one and then clearing the previous one. The reading |
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* code reads the first valid copy it finds, based on the magic number. |
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* The absolute offset to the first of the two copies is kept in rev 1.1 |
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* and higher crypt_mnt_ftr structures. |
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*/ |
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struct crypt_persist_entry { |
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char key[PROPERTY_KEY_MAX]; |
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char val[PROPERTY_VALUE_MAX]; |
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}; |
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/* Should be exactly 4K in size */ |
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struct crypt_persist_data { |
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__le32 persist_magic; |
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__le32 persist_valid_entries; |
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__le32 persist_spare[30]; |
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struct crypt_persist_entry persist_entry[0]; |
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}; |
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#define DATA_MNT_POINT "/data" |
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/* Return values for cryptfs_crypto_complete */ |
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#define CRYPTO_COMPLETE_NOT_ENCRYPTED 1 |
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#define CRYPTO_COMPLETE_ENCRYPTED 0 |
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#define CRYPTO_COMPLETE_BAD_METADATA (-1) |
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#define CRYPTO_COMPLETE_PARTIAL (-2) |
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#define CRYPTO_COMPLETE_INCONSISTENT (-3) |
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#define CRYPTO_COMPLETE_CORRUPT (-4) |
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/* Return values for cryptfs_enable_inplace*() */ |
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#define ENABLE_INPLACE_OK 0 |
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#define ENABLE_INPLACE_ERR_OTHER (-1) |
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#define ENABLE_INPLACE_ERR_DEV (-2) /* crypto_blkdev issue */ |
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/* Return values for cryptfs_getfield */ |
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#define CRYPTO_GETFIELD_OK 0 |
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#define CRYPTO_GETFIELD_ERROR_NO_FIELD (-1) |
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#define CRYPTO_GETFIELD_ERROR_OTHER (-2) |
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#define CRYPTO_GETFIELD_ERROR_BUF_TOO_SMALL (-3) |
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/* Return values for cryptfs_setfield */ |
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#define CRYPTO_SETFIELD_OK 0 |
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#define CRYPTO_SETFIELD_ERROR_OTHER (-1) |
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#define CRYPTO_SETFIELD_ERROR_FIELD_TOO_LONG (-2) |
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#define CRYPTO_SETFIELD_ERROR_VALUE_TOO_LONG (-3) |
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/* Return values for persist_del_key */ |
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#define PERSIST_DEL_KEY_OK 0 |
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#define PERSIST_DEL_KEY_ERROR_OTHER (-1) |
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#define PERSIST_DEL_KEY_ERROR_NO_FIELD (-2) |
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#ifdef __cplusplus |
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extern "C" { |
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#endif |
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int wait_and_unmount(const char *mountpoint, bool kill); |
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typedef int (*kdf_func)(const char *passwd, const unsigned char *salt, |
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unsigned char *ikey, void *params); |
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int cryptfs_crypto_complete(void); |
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int cryptfs_check_passwd(const char *pw); |
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int cryptfs_verify_passwd(char *newpw); |
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int cryptfs_restart(void); |
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int cryptfs_enable(char *flag, int type, char *passwd, int no_ui); |
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int cryptfs_changepw(int type, const char *newpw); |
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int cryptfs_enable_default(char *flag, int no_ui); |
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int cryptfs_setup_ext_volume(const char* label, const char* real_blkdev, |
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const unsigned char* key, int keysize, char* out_crypto_blkdev); |
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int cryptfs_revert_ext_volume(const char* label); |
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int cryptfs_getfield(const char *fieldname, char *value, int len); |
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int cryptfs_setfield(const char *fieldname, const char *value); |
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int cryptfs_mount_default_encrypted(void); |
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int cryptfs_get_password_type(void); |
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const char* cryptfs_get_password(void); |
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void cryptfs_clear_password(void); |
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int cryptfs_isConvertibleToFBE(void); |
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// Functions for file encryption to use to inherit our encryption logic |
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int cryptfs_create_default_ftr(struct crypt_mnt_ftr* ftr, int key_length); |
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int cryptfs_get_master_key(struct crypt_mnt_ftr* ftr, const char* password, |
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unsigned char* master_key); |
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int cryptfs_set_password(struct crypt_mnt_ftr* ftr, const char* password, |
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const unsigned char* master_key); |
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void cryptfs_get_file_encryption_modes(const char **contents_mode_ret, |
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const char **filenames_mode_ret); |
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#ifdef __cplusplus |
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} |
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#endif
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