From 73be12dcd50069dccc76b7bd2d72d70258f420df Mon Sep 17 00:00:00 2001 From: Paul Crowley Date: Mon, 3 Feb 2020 12:22:03 -0800 Subject: [PATCH] Refactor: make cryptfs.h smaller Move most of it into cryptfs.cpp, and include cryptfs.h in fewer files. Bug: 147814592 Test: Treehugger Change-Id: Ia3592d73e7abc1f07a60538e0978a3033bdea7de --- EncryptInplace.h | 5 ++ FsCrypt.cpp | 2 - VoldNativeService.cpp | 12 +-- VoldUtil.h | 2 + VolumeManager.cpp | 1 - cryptfs.cpp | 188 ++++++++++++++++++++++++++++++++++++++++-- cryptfs.h | 186 +---------------------------------------- main.cpp | 1 - 8 files changed, 196 insertions(+), 201 deletions(-) diff --git a/EncryptInplace.h b/EncryptInplace.h index bf0c314..a2b46cf 100644 --- a/EncryptInplace.h +++ b/EncryptInplace.h @@ -24,6 +24,11 @@ #define RETRY_MOUNT_ATTEMPTS 10 #define RETRY_MOUNT_DELAY_SECONDS 1 +/* 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 */ + int cryptfs_enable_inplace(const char* crypto_blkdev, const char* real_blkdev, off64_t size, off64_t* size_already_done, off64_t tot_size, off64_t previously_encrypted_upto, bool set_progress_properties); diff --git a/FsCrypt.cpp b/FsCrypt.cpp index 712f544..1f7faac 100644 --- a/FsCrypt.cpp +++ b/FsCrypt.cpp @@ -43,8 +43,6 @@ #include "android/os/IVold.h" -#include "cryptfs.h" - #define EMULATED_USES_SELINUX 0 #define MANAGE_MISC_DIRS 0 diff --git a/VoldNativeService.cpp b/VoldNativeService.cpp index 6af34d9..905407b 100644 --- a/VoldNativeService.cpp +++ b/VoldNativeService.cpp @@ -17,17 +17,19 @@ #define ATRACE_TAG ATRACE_TAG_PACKAGE_MANAGER #include "VoldNativeService.h" + #include "Benchmark.h" #include "CheckEncryption.h" -#include "IdleMaint.h" -#include "MoveStorage.h" -#include "Process.h" -#include "VolumeManager.h" - #include "Checkpoint.h" #include "FsCrypt.h" +#include "IdleMaint.h" #include "MetadataCrypt.h" +#include "MoveStorage.h" +#include "Process.h" +#include "VoldUtil.h" +#include "VolumeManager.h" #include "cryptfs.h" + #include "incfs_ndk.h" #include diff --git a/VoldUtil.h b/VoldUtil.h index 173c598..6ef8cb1 100644 --- a/VoldUtil.h +++ b/VoldUtil.h @@ -22,3 +22,5 @@ extern android::fs_mgr::Fstab fstab_default; #define ARRAY_SIZE(a) (sizeof(a) / sizeof(*(a))) + +#define DATA_MNT_POINT "/data" diff --git a/VolumeManager.cpp b/VolumeManager.cpp index 44bff5a..f860eef 100644 --- a/VolumeManager.cpp +++ b/VolumeManager.cpp @@ -62,7 +62,6 @@ #include "VoldNativeService.h" #include "VoldUtil.h" #include "VolumeManager.h" -#include "cryptfs.h" #include "fs/Ext4.h" #include "fs/Vfat.h" #include "model/EmulatedVolume.h" diff --git a/cryptfs.cpp b/cryptfs.cpp index 403282e..64b72f0 100644 --- a/cryptfs.cpp +++ b/cryptfs.cpp @@ -14,12 +14,6 @@ * limitations under the License. */ -/* TO DO: - * 1. Perhaps keep several copies of the encrypted key, in case something - * goes horribly wrong? - * - */ - #define LOG_TAG "Cryptfs" #include "cryptfs.h" @@ -80,6 +74,186 @@ using android::fs_mgr::GetEntryForMountPoint; using namespace android::dm; using namespace std::chrono_literals; +/* The current cryptfs version */ +#define CURRENT_MAJOR_VERSION 1 +#define CURRENT_MINOR_VERSION 3 + +#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. */ + +/* 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 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 + +/* 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..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. + */ + +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]; +}; + +/* Persistant data that should be available before decryption. + * Things like airplane mode, locale and timezone are kept + * here and can be retrieved by the CryptKeeper UI to properly + * configure the phone before asking for the password + * This is only valid if the major and minor version above + * is set to 1.1 or higher. + * + * This is a 4K structure. There are 2 copies, and the code alternates + * writing one and then clearing the previous one. The reading + * code reads the first valid copy it finds, based on the magic number. + * The absolute offset to the first of the two copies is kept in rev 1.1 + * and higher crypt_mnt_ftr structures. + */ +struct crypt_persist_entry { + char key[PROPERTY_KEY_MAX]; + char val[PROPERTY_VALUE_MAX]; +}; + +/* Should be exactly 4K in size */ +struct crypt_persist_data { + __le32 persist_magic; + __le32 persist_valid_entries; + __le32 persist_spare[30]; + struct crypt_persist_entry persist_entry[0]; +}; + +static int wait_and_unmount(const char* mountpoint, bool kill); + +typedef int (*kdf_func)(const char* passwd, const unsigned char* salt, unsigned char* ikey, + void* params); + #define UNUSED __attribute__((unused)) #define HASH_COUNT 2000 @@ -1298,7 +1472,7 @@ static int create_encrypted_random_key(const char* passwd, unsigned char* master return encrypt_master_key(passwd, salt, key_buf, master_key, crypt_ftr); } -int wait_and_unmount(const char* mountpoint, bool kill) { +static int wait_and_unmount(const char* mountpoint, bool kill) { int i, err, rc; #define WAIT_UNMOUNT_COUNT 20 diff --git a/cryptfs.h b/cryptfs.h index 692d7ee..28d1887 100644 --- a/cryptfs.h +++ b/cryptfs.h @@ -17,189 +17,13 @@ #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..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 #include #include #include -/* 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. */ - -/* 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 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]; -}; - -/* Persistant data that should be available before decryption. - * Things like airplane mode, locale and timezone are kept - * here and can be retrieved by the CryptKeeper UI to properly - * configure the phone before asking for the password - * This is only valid if the major and minor version above - * is set to 1.1 or higher. - * - * This is a 4K structure. There are 2 copies, and the code alternates - * writing one and then clearing the previous one. The reading - * code reads the first valid copy it finds, based on the magic number. - * The absolute offset to the first of the two copies is kept in rev 1.1 - * and higher crypt_mnt_ftr structures. - */ -struct crypt_persist_entry { - char key[PROPERTY_KEY_MAX]; - char val[PROPERTY_VALUE_MAX]; -}; - -/* Should be exactly 4K in size */ -struct crypt_persist_data { - __le32 persist_magic; - __le32 persist_valid_entries; - __le32 persist_spare[30]; - struct crypt_persist_entry persist_entry[0]; -}; - -#define DATA_MNT_POINT "/data" /* Return values for cryptfs_crypto_complete */ #define CRYPTO_COMPLETE_NOT_ENCRYPTED 1 @@ -209,11 +33,6 @@ struct crypt_persist_data { #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 */ - /* Return values for cryptfs_getfield */ #define CRYPTO_GETFIELD_OK 0 #define CRYPTO_GETFIELD_ERROR_NO_FIELD (-1) @@ -231,11 +50,8 @@ struct crypt_persist_data { #define PERSIST_DEL_KEY_ERROR_OTHER (-1) #define PERSIST_DEL_KEY_ERROR_NO_FIELD (-2) +// Exposed for testing only int match_multi_entry(const char* key, const char* field, unsigned index); -int wait_and_unmount(const char* mountpoint, bool kill); - -typedef int (*kdf_func)(const char* passwd, const unsigned char* salt, unsigned char* ikey, - void* params); int cryptfs_crypto_complete(void); int cryptfs_check_passwd(const char* pw); diff --git a/main.cpp b/main.cpp index 7555276..ebe5510 100644 --- a/main.cpp +++ b/main.cpp @@ -20,7 +20,6 @@ #include "VoldNativeService.h" #include "VoldUtil.h" #include "VolumeManager.h" -#include "cryptfs.h" #include "model/Disk.h" #include "sehandle.h"