ecryptfs_kernel.h

linux 内核源代码

/**
 * eCryptfs: Linux filesystem encryption layer
 * Kernel declarations.
 *
 * Copyright (C) 1997-2003 Erez Zadok
 * Copyright (C) 2001-2003 Stony Brook University
 * Copyright (C) 2004-2007 International Business Machines Corp.
 *   Author(s): Michael A. Halcrow <[e-mail]>
 *              Trevor S. Highland <[e-mail]>
 *              Tyler Hicks <[e-mail]>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation; either version 2 of the
 * License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
 * 02111-1307, USA.
 */

#ifndef ECRYPTFS_KERNEL_H
#define ECRYPTFS_KERNEL_H

#include <keys/user-type.h>
#include <linux/fs.h>
#include <linux/fs_stack.h>
#include <linux/namei.h>
#include <linux/scatterlist.h>
#include <linux/hash.h>

/* Version verification for shared data structures w/ userspace */
#define ECRYPTFS_VERSION_MAJOR 0x00
#define ECRYPTFS_VERSION_MINOR 0x04
#define ECRYPTFS_SUPPORTED_FILE_VERSION 0x03
/* These flags indicate which features are supported by the kernel
 * module; userspace tools such as the mount helper read
 * ECRYPTFS_VERSIONING_MASK from a sysfs handle in order to determine
 * how to behave. */
#define ECRYPTFS_VERSIONING_PASSPHRASE            0x00000001
#define ECRYPTFS_VERSIONING_PUBKEY                0x00000002
#define ECRYPTFS_VERSIONING_PLAINTEXT_PASSTHROUGH 0x00000004
#define ECRYPTFS_VERSIONING_POLICY                0x00000008
#define ECRYPTFS_VERSIONING_XATTR                 0x00000010
#define ECRYPTFS_VERSIONING_MULTKEY               0x00000020
#define ECRYPTFS_VERSIONING_MASK (ECRYPTFS_VERSIONING_PASSPHRASE \
				  | ECRYPTFS_VERSIONING_PLAINTEXT_PASSTHROUGH \
				  | ECRYPTFS_VERSIONING_PUBKEY \
				  | ECRYPTFS_VERSIONING_XATTR \
				  | ECRYPTFS_VERSIONING_MULTKEY)
#define ECRYPTFS_MAX_PASSWORD_LENGTH 64
#define ECRYPTFS_MAX_PASSPHRASE_BYTES ECRYPTFS_MAX_PASSWORD_LENGTH
#define ECRYPTFS_SALT_SIZE 8
#define ECRYPTFS_SALT_SIZE_HEX (ECRYPTFS_SALT_SIZE*2)
/* The original signature size is only for what is stored on disk; all
 * in-memory representations are expanded hex, so it better adapted to
 * be passed around or referenced on the command line */
#define ECRYPTFS_SIG_SIZE 8
#define ECRYPTFS_SIG_SIZE_HEX (ECRYPTFS_SIG_SIZE*2)
#define ECRYPTFS_PASSWORD_SIG_SIZE ECRYPTFS_SIG_SIZE_HEX
#define ECRYPTFS_MAX_KEY_BYTES 64
#define ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES 512
#define ECRYPTFS_DEFAULT_IV_BYTES 16
#define ECRYPTFS_FILE_VERSION 0x03
#define ECRYPTFS_DEFAULT_EXTENT_SIZE 4096
#define ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE 8192
#define ECRYPTFS_DEFAULT_MSG_CTX_ELEMS 32
#define ECRYPTFS_DEFAULT_SEND_TIMEOUT HZ
#define ECRYPTFS_MAX_MSG_CTX_TTL (HZ*3)
#define ECRYPTFS_NLMSG_HELO 100
#define ECRYPTFS_NLMSG_QUIT 101
#define ECRYPTFS_NLMSG_REQUEST 102
#define ECRYPTFS_NLMSG_RESPONSE 103
#define ECRYPTFS_MAX_PKI_NAME_BYTES 16
#define ECRYPTFS_DEFAULT_NUM_USERS 4
#define ECRYPTFS_MAX_NUM_USERS 32768
#define ECRYPTFS_TRANSPORT_NETLINK 0
#define ECRYPTFS_TRANSPORT_CONNECTOR 1
#define ECRYPTFS_TRANSPORT_RELAYFS 2
#define ECRYPTFS_DEFAULT_TRANSPORT ECRYPTFS_TRANSPORT_NETLINK
#define ECRYPTFS_XATTR_NAME "user.ecryptfs"

#define RFC2440_CIPHER_DES3_EDE 0x02
#define RFC2440_CIPHER_CAST_5 0x03
#define RFC2440_CIPHER_BLOWFISH 0x04
#define RFC2440_CIPHER_AES_128 0x07
#define RFC2440_CIPHER_AES_192 0x08
#define RFC2440_CIPHER_AES_256 0x09
#define RFC2440_CIPHER_TWOFISH 0x0a
#define RFC2440_CIPHER_CAST_6 0x0b

#define RFC2440_CIPHER_RSA 0x01

/**
 * For convenience, we may need to pass around the encrypted session
 * key between kernel and userspace because the authentication token
 * may not be extractable.  For example, the TPM may not release the
 * private key, instead requiring the encrypted data and returning the
 * decrypted data.
 */
struct ecryptfs_session_key {
#define ECRYPTFS_USERSPACE_SHOULD_TRY_TO_DECRYPT 0x00000001
#define ECRYPTFS_USERSPACE_SHOULD_TRY_TO_ENCRYPT 0x00000002
#define ECRYPTFS_CONTAINS_DECRYPTED_KEY 0x00000004
#define ECRYPTFS_CONTAINS_ENCRYPTED_KEY 0x00000008
	u32 flags;
	u32 encrypted_key_size;
	u32 decrypted_key_size;
	u8 encrypted_key[ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES];
	u8 decrypted_key[ECRYPTFS_MAX_KEY_BYTES];
};

struct ecryptfs_password {
	u32 password_bytes;
	s32 hash_algo;
	u32 hash_iterations;
	u32 session_key_encryption_key_bytes;
#define ECRYPTFS_PERSISTENT_PASSWORD 0x01
#define ECRYPTFS_SESSION_KEY_ENCRYPTION_KEY_SET 0x02
	u32 flags;
	/* Iterated-hash concatenation of salt and passphrase */
	u8 session_key_encryption_key[ECRYPTFS_MAX_KEY_BYTES];
	u8 signature[ECRYPTFS_PASSWORD_SIG_SIZE + 1];
	/* Always in expanded hex */
	u8 salt[ECRYPTFS_SALT_SIZE];
};

enum ecryptfs_token_types {ECRYPTFS_PASSWORD, ECRYPTFS_PRIVATE_KEY};

struct ecryptfs_private_key {
	u32 key_size;
	u32 data_len;
	u8 signature[ECRYPTFS_PASSWORD_SIG_SIZE + 1];
	char pki_type[ECRYPTFS_MAX_PKI_NAME_BYTES + 1];
	u8 data[];
};

/* May be a password or a private key */
struct ecryptfs_auth_tok {
	u16 version; /* 8-bit major and 8-bit minor */
	u16 token_type;
#define ECRYPTFS_ENCRYPT_ONLY 0x00000001
	u32 flags;
	struct ecryptfs_session_key session_key;
	u8 reserved[32];
	union {
		struct ecryptfs_password password;
		struct ecryptfs_private_key private_key;
	} token;
} __attribute__ ((packed));

void ecryptfs_dump_auth_tok(struct ecryptfs_auth_tok *auth_tok);
extern void ecryptfs_to_hex(char *dst, char *src, size_t src_size);
extern void ecryptfs_from_hex(char *dst, char *src, int dst_size);

struct ecryptfs_key_record {
	unsigned char type;
	size_t enc_key_size;
	unsigned char sig[ECRYPTFS_SIG_SIZE];
	unsigned char enc_key[ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES];
};

struct ecryptfs_auth_tok_list {
	struct ecryptfs_auth_tok *auth_tok;
	struct list_head list;
};

struct ecryptfs_crypt_stat;
struct ecryptfs_mount_crypt_stat;

struct ecryptfs_page_crypt_context {
	struct page *page;
#define ECRYPTFS_PREPARE_COMMIT_MODE 0
#define ECRYPTFS_WRITEPAGE_MODE      1
	unsigned int mode;
	union {
		struct file *lower_file;
		struct writeback_control *wbc;
	} param;
};

static inline struct ecryptfs_auth_tok *
ecryptfs_get_key_payload_data(struct key *key)
{
	return (struct ecryptfs_auth_tok *)
		(((struct user_key_payload*)key->payload.data)->data);
}

#define ECRYPTFS_SUPER_MAGIC 0xf15f
#define ECRYPTFS_MAX_KEYSET_SIZE 1024
#define ECRYPTFS_MAX_CIPHER_NAME_SIZE 32
#define ECRYPTFS_MAX_NUM_ENC_KEYS 64
#define ECRYPTFS_MAX_IV_BYTES 16	/* 128 bits */
#define ECRYPTFS_SALT_BYTES 2
#define MAGIC_ECRYPTFS_MARKER 0x3c81b7f5
#define MAGIC_ECRYPTFS_MARKER_SIZE_BYTES 8	/* 4*2 */
#define ECRYPTFS_FILE_SIZE_BYTES (sizeof(u64))
#define ECRYPTFS_DEFAULT_CIPHER "aes"
#define ECRYPTFS_DEFAULT_KEY_BYTES 16
#define ECRYPTFS_DEFAULT_HASH "md5"
#define ECRYPTFS_TAG_1_PACKET_TYPE 0x01
#define ECRYPTFS_TAG_3_PACKET_TYPE 0x8C
#define ECRYPTFS_TAG_11_PACKET_TYPE 0xED
#define ECRYPTFS_TAG_64_PACKET_TYPE 0x40
#define ECRYPTFS_TAG_65_PACKET_TYPE 0x41
#define ECRYPTFS_TAG_66_PACKET_TYPE 0x42
#define ECRYPTFS_TAG_67_PACKET_TYPE 0x43
#define MD5_DIGEST_SIZE 16

struct ecryptfs_key_sig {
	struct list_head crypt_stat_list;
	char keysig[ECRYPTFS_SIG_SIZE_HEX];
};

/**
 * This is the primary struct associated with each encrypted file.
 *
 * TODO: cache align/pack?
 */
struct ecryptfs_crypt_stat {
#define ECRYPTFS_STRUCT_INITIALIZED 0x00000001
#define ECRYPTFS_POLICY_APPLIED     0x00000002
#define ECRYPTFS_NEW_FILE           0x00000004
#define ECRYPTFS_ENCRYPTED          0x00000008
#define ECRYPTFS_SECURITY_WARNING   0x00000010
#define ECRYPTFS_ENABLE_HMAC        0x00000020
#define ECRYPTFS_ENCRYPT_IV_PAGES   0x00000040
#define ECRYPTFS_KEY_VALID          0x00000080
#define ECRYPTFS_METADATA_IN_XATTR  0x00000100
#define ECRYPTFS_VIEW_AS_ENCRYPTED  0x00000200
	u32 flags;
	unsigned int file_version;
	size_t iv_bytes;
	size_t num_header_extents_at_front;
	size_t extent_size; /* Data extent size; default is 4096 */
	size_t key_size;
	size_t extent_shift;
	unsigned int extent_mask;
	struct ecryptfs_mount_crypt_stat *mount_crypt_stat;
	struct crypto_blkcipher *tfm;
	struct crypto_hash *hash_tfm; /* Crypto context for generating
				       * the initialization vectors */
	unsigned char cipher[ECRYPTFS_MAX_CIPHER_NAME_SIZE];
	unsigned char key[ECRYPTFS_MAX_KEY_BYTES];
	unsigned char root_iv[ECRYPTFS_MAX_IV_BYTES];
	struct list_head keysig_list;
	struct mutex keysig_list_mutex;
	struct mutex cs_tfm_mutex;
	struct mutex cs_hash_tfm_mutex;
	struct mutex cs_mutex;
};

/* inode private data. */
struct ecryptfs_inode_info {
	struct inode vfs_inode;
	struct inode *wii_inode;
	struct file *lower_file;
	struct mutex lower_file_mutex;
	struct ecryptfs_crypt_stat crypt_stat;
};

/* dentry private data. Each dentry must keep track of a lower
 * vfsmount too. */
struct ecryptfs_dentry_info {
	struct path lower_path;
	struct ecryptfs_crypt_stat *crypt_stat;
};

/**
 * ecryptfs_global_auth_tok - A key used to encrypt all new files under the mountpoint
 * @flags: Status flags
 * @mount_crypt_stat_list: These auth_toks hang off the mount-wide
 *                         cryptographic context. Every time a new
 *                         inode comes into existence, eCryptfs copies
 *                         the auth_toks on that list to the set of
 *                         auth_toks on the inode's crypt_stat
 * @global_auth_tok_key: The key from the user's keyring for the sig
 * @global_auth_tok: The key contents
 * @sig: The key identifier
 *
 * ecryptfs_global_auth_tok structs refer to authentication token keys
 * in the user keyring that apply to newly created files. A list of
 * these objects hangs off of the mount_crypt_stat struct for any
 * given eCryptfs mount. This struct maintains a reference to both the
 * key contents and the key itself so that the key can be put on
 * unmount.
 */
struct ecryptfs_global_auth_tok {
#define ECRYPTFS_AUTH_TOK_INVALID 0x00000001
	u32 flags;
	struct list_head mount_crypt_stat_list;
	struct key *global_auth_tok_key;
	struct ecryptfs_auth_tok *global_auth_tok;
	unsigned char sig[ECRYPTFS_SIG_SIZE_HEX + 1];
};

/**
 * ecryptfs_key_tfm - Persistent key tfm
 * @key_tfm: crypto API handle to the key
 * @key_size: Key size in bytes
 * @key_tfm_mutex: Mutex to ensure only one operation in eCryptfs is
 *                 using the persistent TFM at any point in time
 * @key_tfm_list: Handle to hang this off the module-wide TFM list
 * @cipher_name: String name for the cipher for this TFM
 *
 * Typically, eCryptfs will use the same ciphers repeatedly throughout
 * the course of its operations. In order to avoid unnecessarily
 * destroying and initializing the same cipher repeatedly, eCryptfs
 * keeps a list of crypto API contexts around to use when needed.
 */
struct ecryptfs_key_tfm {
	struct crypto_blkcipher *key_tfm;
	size_t key_size;
	struct mutex key_tfm_mutex;
	struct list_head key_tfm_list;
	unsigned char cipher_name[ECRYPTFS_MAX_CIPHER_NAME_SIZE + 1];
};

extern struct list_head key_tfm_list;
extern struct mutex key_tfm_list_mutex;