[linux-2.6-block.git] / fs / ext4 / ext4_crypto.h

/*
 * linux/fs/ext4/ext4_crypto.h
 *
 * Copyright (C) 2015, Google, Inc.
 *
 * This contains encryption header content for ext4
 *
 * Written by Michael Halcrow, 2015.
 */

#ifndef _EXT4_CRYPTO_H
#define _EXT4_CRYPTO_H

#include <linux/fs.h>

#define EXT4_KEY_DESCRIPTOR_SIZE 8

/* Policy provided via an ioctl on the topmost directory */
struct ext4_encryption_policy {
	char version;
	char contents_encryption_mode;
	char filenames_encryption_mode;
	char flags;
	char master_key_descriptor[EXT4_KEY_DESCRIPTOR_SIZE];
} __attribute__((__packed__));

#define EXT4_ENCRYPTION_CONTEXT_FORMAT_V1 1
#define EXT4_KEY_DERIVATION_NONCE_SIZE 16

#define EXT4_POLICY_FLAGS_PAD_4		0x00
#define EXT4_POLICY_FLAGS_PAD_8		0x01
#define EXT4_POLICY_FLAGS_PAD_16	0x02
#define EXT4_POLICY_FLAGS_PAD_32	0x03
#define EXT4_POLICY_FLAGS_PAD_MASK	0x03
#define EXT4_POLICY_FLAGS_VALID		0x03

/**
 * Encryption context for inode
 *
 * Protector format:
 *  1 byte: Protector format (1 = this version)
 *  1 byte: File contents encryption mode
 *  1 byte: File names encryption mode
 *  1 byte: Reserved
 *  8 bytes: Master Key descriptor
 *  16 bytes: Encryption Key derivation nonce
 */
struct ext4_encryption_context {
	char format;
	char contents_encryption_mode;
	char filenames_encryption_mode;
	char flags;
	char master_key_descriptor[EXT4_KEY_DESCRIPTOR_SIZE];
	char nonce[EXT4_KEY_DERIVATION_NONCE_SIZE];
} __attribute__((__packed__));

/* Encryption parameters */
#define EXT4_XTS_TWEAK_SIZE 16
#define EXT4_AES_128_ECB_KEY_SIZE 16
#define EXT4_AES_256_GCM_KEY_SIZE 32
#define EXT4_AES_256_CBC_KEY_SIZE 32
#define EXT4_AES_256_CTS_KEY_SIZE 32
#define EXT4_AES_256_XTS_KEY_SIZE 64
#define EXT4_MAX_KEY_SIZE 64

#define EXT4_KEY_DESC_PREFIX "ext4:"
#define EXT4_KEY_DESC_PREFIX_SIZE 5

struct ext4_encryption_key {
	uint32_t mode;
	char raw[EXT4_MAX_KEY_SIZE];
	uint32_t size;
};

#define EXT4_CTX_REQUIRES_FREE_ENCRYPT_FL             0x00000001
#define EXT4_BOUNCE_PAGE_REQUIRES_FREE_ENCRYPT_FL     0x00000002

struct ext4_crypto_ctx {
	struct crypto_tfm *tfm;         /* Crypto API context */
	struct page *bounce_page;       /* Ciphertext page on write path */
	struct page *control_page;      /* Original page on write path */
	struct bio *bio;                /* The bio for this context */
	struct work_struct work;        /* Work queue for read complete path */
	struct list_head free_list;     /* Free list */
	int flags;                      /* Flags */
	int mode;                       /* Encryption mode for tfm */
};

struct ext4_completion_result {
	struct completion completion;
	int res;
};

#define DECLARE_EXT4_COMPLETION_RESULT(ecr) \
	struct ext4_completion_result ecr = { \
		COMPLETION_INITIALIZER((ecr).completion), 0 }

static inline int ext4_encryption_key_size(int mode)
{
	switch (mode) {
	case EXT4_ENCRYPTION_MODE_AES_256_XTS:
		return EXT4_AES_256_XTS_KEY_SIZE;
	case EXT4_ENCRYPTION_MODE_AES_256_GCM:
		return EXT4_AES_256_GCM_KEY_SIZE;
	case EXT4_ENCRYPTION_MODE_AES_256_CBC:
		return EXT4_AES_256_CBC_KEY_SIZE;
	case EXT4_ENCRYPTION_MODE_AES_256_CTS:
		return EXT4_AES_256_CTS_KEY_SIZE;
	default:
		BUG();
	}
	return 0;
}

#define EXT4_FNAME_NUM_SCATTER_ENTRIES	4
#define EXT4_CRYPTO_BLOCK_SIZE		16
#define EXT4_FNAME_CRYPTO_DIGEST_SIZE	32

struct ext4_str {
	unsigned char *name;
	u32 len;
};

struct ext4_fname_crypto_ctx {
	u32 lim;
	char tmp_buf[EXT4_CRYPTO_BLOCK_SIZE];
	struct crypto_ablkcipher *ctfm;
	struct crypto_hash *htfm;
	struct page *workpage;
	struct ext4_encryption_key key;
	unsigned flags : 8;
	unsigned has_valid_key : 1;
	unsigned ctfm_key_is_ready : 1;
};

/**
 * For encrypted symlinks, the ciphertext length is stored at the beginning
 * of the string in little-endian format.
 */
struct ext4_encrypted_symlink_data {
	__le16 len;
	char encrypted_path[1];
} __attribute__((__packed__));

/**
 * This function is used to calculate the disk space required to
 * store a filename of length l in encrypted symlink format.
 */
static inline u32 encrypted_symlink_data_len(u32 l)
{
	if (l < EXT4_CRYPTO_BLOCK_SIZE)
		l = EXT4_CRYPTO_BLOCK_SIZE;
	return (l + sizeof(struct ext4_encrypted_symlink_data) - 1);
}

#endif	/* _EXT4_CRYPTO_H */
Commit	Line	Data
9bd8212f MH	1	/*
	2	* linux/fs/ext4/ext4_crypto.h
	3	*
	4	* Copyright (C) 2015, Google, Inc.
	5	*
	6	* This contains encryption header content for ext4
	7	*
	8	* Written by Michael Halcrow, 2015.
	9	*/
	10
	11	#ifndef _EXT4_CRYPTO_H
	12	#define _EXT4_CRYPTO_H
	13
	14	#include <linux/fs.h>
	15
	16	#define EXT4_KEY_DESCRIPTOR_SIZE 8
	17
	18	/* Policy provided via an ioctl on the topmost directory */
	19	struct ext4_encryption_policy {
	20	char version;
	21	char contents_encryption_mode;
	22	char filenames_encryption_mode;
a44cd7a0	23	char flags;
9bd8212f MH	24	char master_key_descriptor[EXT4_KEY_DESCRIPTOR_SIZE];
	25	} __attribute__((__packed__));
	26
	27	#define EXT4_ENCRYPTION_CONTEXT_FORMAT_V1 1
	28	#define EXT4_KEY_DERIVATION_NONCE_SIZE 16
	29
a44cd7a0 TT	30	#define EXT4_POLICY_FLAGS_PAD_4 0x00
	31	#define EXT4_POLICY_FLAGS_PAD_8 0x01
	32	#define EXT4_POLICY_FLAGS_PAD_16 0x02
	33	#define EXT4_POLICY_FLAGS_PAD_32 0x03
	34	#define EXT4_POLICY_FLAGS_PAD_MASK 0x03
	35	#define EXT4_POLICY_FLAGS_VALID 0x03
	36
9bd8212f MH	37	/**
	38	* Encryption context for inode
	39	*
	40	* Protector format:
	41	* 1 byte: Protector format (1 = this version)
	42	* 1 byte: File contents encryption mode
	43	* 1 byte: File names encryption mode
	44	* 1 byte: Reserved
	45	* 8 bytes: Master Key descriptor
	46	* 16 bytes: Encryption Key derivation nonce
	47	*/
	48	struct ext4_encryption_context {
	49	char format;
	50	char contents_encryption_mode;
	51	char filenames_encryption_mode;
a44cd7a0	52	char flags;
9bd8212f MH	53	char master_key_descriptor[EXT4_KEY_DESCRIPTOR_SIZE];
	54	char nonce[EXT4_KEY_DERIVATION_NONCE_SIZE];
	55	} __attribute__((__packed__));
	56
b30ab0e0 MH	57	/* Encryption parameters */
	58	#define EXT4_XTS_TWEAK_SIZE 16
	59	#define EXT4_AES_128_ECB_KEY_SIZE 16
	60	#define EXT4_AES_256_GCM_KEY_SIZE 32
	61	#define EXT4_AES_256_CBC_KEY_SIZE 32
	62	#define EXT4_AES_256_CTS_KEY_SIZE 32
	63	#define EXT4_AES_256_XTS_KEY_SIZE 64
	64	#define EXT4_MAX_KEY_SIZE 64
	65
88bd6ccd MH	66	#define EXT4_KEY_DESC_PREFIX "ext4:"
	67	#define EXT4_KEY_DESC_PREFIX_SIZE 5
	68
b30ab0e0 MH	69	struct ext4_encryption_key {
	70	uint32_t mode;
	71	char raw[EXT4_MAX_KEY_SIZE];
	72	uint32_t size;
	73	};
	74
	75	#define EXT4_CTX_REQUIRES_FREE_ENCRYPT_FL 0x00000001
	76	#define EXT4_BOUNCE_PAGE_REQUIRES_FREE_ENCRYPT_FL 0x00000002
	77
	78	struct ext4_crypto_ctx {
	79	struct crypto_tfm tfm; / Crypto API context */
	80	struct page bounce_page; / Ciphertext page on write path */
	81	struct page control_page; / Original page on write path */
	82	struct bio bio; / The bio for this context */
	83	struct work_struct work; /* Work queue for read complete path */
	84	struct list_head free_list; /* Free list */
	85	int flags; /* Flags */
	86	int mode; /* Encryption mode for tfm */
	87	};
	88
	89	struct ext4_completion_result {
	90	struct completion completion;
	91	int res;
	92	};
	93
	94	#define DECLARE_EXT4_COMPLETION_RESULT(ecr) \
	95	struct ext4_completion_result ecr = { \
	96	COMPLETION_INITIALIZER((ecr).completion), 0 }
	97
	98	static inline int ext4_encryption_key_size(int mode)
	99	{
	100	switch (mode) {
	101	case EXT4_ENCRYPTION_MODE_AES_256_XTS:
	102	return EXT4_AES_256_XTS_KEY_SIZE;
	103	case EXT4_ENCRYPTION_MODE_AES_256_GCM:
	104	return EXT4_AES_256_GCM_KEY_SIZE;
	105	case EXT4_ENCRYPTION_MODE_AES_256_CBC:
	106	return EXT4_AES_256_CBC_KEY_SIZE;
	107	case EXT4_ENCRYPTION_MODE_AES_256_CTS:
	108	return EXT4_AES_256_CTS_KEY_SIZE;
	109	default:
	110	BUG();
	111	}
	112	return 0;
	113	}
	114
d5d0e8c7 MH	115	#define EXT4_FNAME_NUM_SCATTER_ENTRIES 4
	116	#define EXT4_CRYPTO_BLOCK_SIZE 16
	117	#define EXT4_FNAME_CRYPTO_DIGEST_SIZE 32
	118
	119	struct ext4_str {
	120	unsigned char *name;
	121	u32 len;
	122	};
	123
	124	struct ext4_fname_crypto_ctx {
	125	u32 lim;
	126	char tmp_buf[EXT4_CRYPTO_BLOCK_SIZE];
	127	struct crypto_ablkcipher *ctfm;
	128	struct crypto_hash *htfm;
	129	struct page *workpage;
	130	struct ext4_encryption_key key;
a44cd7a0	131	unsigned flags : 8;
d5d0e8c7 MH	132	unsigned has_valid_key : 1;
	133	unsigned ctfm_key_is_ready : 1;
	134	};
	135
f348c252 TT	136	/**
	137	* For encrypted symlinks, the ciphertext length is stored at the beginning
	138	* of the string in little-endian format.
	139	*/
	140	struct ext4_encrypted_symlink_data {
	141	__le16 len;
	142	char encrypted_path[1];
	143	} __attribute__((__packed__));
	144
	145	/**
	146	* This function is used to calculate the disk space required to
	147	* store a filename of length l in encrypted symlink format.
	148	*/
	149	static inline u32 encrypted_symlink_data_len(u32 l)
	150	{
	151	if (l < EXT4_CRYPTO_BLOCK_SIZE)
	152	l = EXT4_CRYPTO_BLOCK_SIZE;
	153	return (l + sizeof(struct ext4_encrypted_symlink_data) - 1);
	154	}
	155
9bd8212f	156	#endif /* _EXT4_CRYPTO_H */