[linux-block.git] / drivers / block / cryptoloop.c

/*
   Linux loop encryption enabling module

   Copyright (C)  2002 Herbert Valerio Riedel <hvr@gnu.org>
   Copyright (C)  2003 Fruhwirth Clemens <clemens@endorphin.org>

   This module 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 module 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 module; if not, write to the Free Software
   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#include <linux/module.h>

#include <linux/init.h>
#include <linux/string.h>
#include <linux/crypto.h>
#include <linux/blkdev.h>
#include <linux/loop.h>
#include <linux/scatterlist.h>
#include <asm/semaphore.h>
#include <asm/uaccess.h>

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("loop blockdevice transferfunction adaptor / CryptoAPI");
MODULE_AUTHOR("Herbert Valerio Riedel <hvr@gnu.org>");

#define LOOP_IV_SECTOR_BITS 9
#define LOOP_IV_SECTOR_SIZE (1 << LOOP_IV_SECTOR_BITS)

static int
cryptoloop_init(struct loop_device *lo, const struct loop_info64 *info)
{
	int err = -EINVAL;
	int cipher_len;
	int mode_len;
	char cms[LO_NAME_SIZE];			/* cipher-mode string */
	char *cipher;
	char *mode;
	char *cmsp = cms;			/* c-m string pointer */
	struct crypto_blkcipher *tfm;

	/* encryption breaks for non sector aligned offsets */

	if (info->lo_offset % LOOP_IV_SECTOR_SIZE)
		goto out;

	strncpy(cms, info->lo_crypt_name, LO_NAME_SIZE);
	cms[LO_NAME_SIZE - 1] = 0;

	cipher = cmsp;
	cipher_len = strcspn(cmsp, "-");

	mode = cmsp + cipher_len;
	mode_len = 0;
	if (*mode) {
		mode++;
		mode_len = strcspn(mode, "-");
	}

	if (!mode_len) {
		mode = "cbc";
		mode_len = 3;
	}

	if (cipher_len + mode_len + 3 > LO_NAME_SIZE)
		return -EINVAL;

	memmove(cms, mode, mode_len);
	cmsp = cms + mode_len;
	*cmsp++ = '(';
	memcpy(cmsp, info->lo_crypt_name, cipher_len);
	cmsp += cipher_len;
	*cmsp++ = ')';
	*cmsp = 0;

	tfm = crypto_alloc_blkcipher(cms, 0, CRYPTO_ALG_ASYNC);
	if (IS_ERR(tfm))
		return PTR_ERR(tfm);

	err = crypto_blkcipher_setkey(tfm, info->lo_encrypt_key,
				      info->lo_encrypt_key_size);
	
	if (err != 0)
		goto out_free_tfm;

	lo->key_data = tfm;
	return 0;

 out_free_tfm:
	crypto_free_blkcipher(tfm);

 out:
	return err;
}


typedef int (*encdec_cbc_t)(struct blkcipher_desc *desc,
			struct scatterlist *sg_out,
			struct scatterlist *sg_in,
			unsigned int nsg);

static int
cryptoloop_transfer(struct loop_device *lo, int cmd,
		    struct page *raw_page, unsigned raw_off,
		    struct page *loop_page, unsigned loop_off,
		    int size, sector_t IV)
{
	struct crypto_blkcipher *tfm = lo->key_data;
	struct blkcipher_desc desc = {
		.tfm = tfm,
		.flags = CRYPTO_TFM_REQ_MAY_SLEEP,
	};
	struct scatterlist sg_out;
	struct scatterlist sg_in;

	encdec_cbc_t encdecfunc;
	struct page *in_page, *out_page;
	unsigned in_offs, out_offs;
	int err;

	sg_init_table(&sg_out, 1);
	sg_init_table(&sg_in, 1);

	if (cmd == READ) {
		in_page = raw_page;
		in_offs = raw_off;
		out_page = loop_page;
		out_offs = loop_off;
		encdecfunc = crypto_blkcipher_crt(tfm)->decrypt;
	} else {
		in_page = loop_page;
		in_offs = loop_off;
		out_page = raw_page;
		out_offs = raw_off;
		encdecfunc = crypto_blkcipher_crt(tfm)->encrypt;
	}

	while (size > 0) {
		const int sz = min(size, LOOP_IV_SECTOR_SIZE);
		u32 iv[4] = { 0, };
		iv[0] = cpu_to_le32(IV & 0xffffffff);

		sg_set_page(&sg_in, in_page, sz, in_offs);
		sg_set_page(&sg_out, out_page, sz, out_offs);

		desc.info = iv;
		err = encdecfunc(&desc, &sg_out, &sg_in, sz);
		if (err)
			return err;

		IV++;
		size -= sz;
		in_offs += sz;
		out_offs += sz;
	}

	return 0;
}

static int
cryptoloop_ioctl(struct loop_device *lo, int cmd, unsigned long arg)
{
	return -EINVAL;
}

static int
cryptoloop_release(struct loop_device *lo)
{
	struct crypto_blkcipher *tfm = lo->key_data;
	if (tfm != NULL) {
		crypto_free_blkcipher(tfm);
		lo->key_data = NULL;
		return 0;
	}
	printk(KERN_ERR "cryptoloop_release(): tfm == NULL?\n");
	return -EINVAL;
}

static struct loop_func_table cryptoloop_funcs = {
	.number = LO_CRYPT_CRYPTOAPI,
	.init = cryptoloop_init,
	.ioctl = cryptoloop_ioctl,
	.transfer = cryptoloop_transfer,
	.release = cryptoloop_release,
	.owner = THIS_MODULE
};

static int __init
init_cryptoloop(void)
{
	int rc = loop_register_transfer(&cryptoloop_funcs);

	if (rc)
		printk(KERN_ERR "cryptoloop: loop_register_transfer failed\n");
	return rc;
}

static void __exit
cleanup_cryptoloop(void)
{
	if (loop_unregister_transfer(LO_CRYPT_CRYPTOAPI))
		printk(KERN_ERR
			"cryptoloop: loop_unregister_transfer failed\n");
}

module_init(init_cryptoloop);
module_exit(cleanup_cryptoloop);
Commit	Line	Data
1da177e4 LT	1	/*
	2	Linux loop encryption enabling module
	3
	4	Copyright (C) 2002 Herbert Valerio Riedel <hvr@gnu.org>
	5	Copyright (C) 2003 Fruhwirth Clemens <clemens@endorphin.org>
	6
	7	This module is free software; you can redistribute it and/or modify
	8	it under the terms of the GNU General Public License as published by
	9	the Free Software Foundation; either version 2 of the License, or
	10	(at your option) any later version.
	11
	12	This module is distributed in the hope that it will be useful,
	13	but WITHOUT ANY WARRANTY; without even the implied warranty of
	14	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	15	GNU General Public License for more details.
	16
	17	You should have received a copy of the GNU General Public License
	18	along with this module; if not, write to the Free Software
	19	Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
	20	*/
	21
	22	#include <linux/module.h>
	23
	24	#include <linux/init.h>
	25	#include <linux/string.h>
	26	#include <linux/crypto.h>
	27	#include <linux/blkdev.h>
	28	#include <linux/loop.h>
45711f1a	29	#include <linux/scatterlist.h>
1da177e4 LT	30	#include <asm/semaphore.h>
	31	#include <asm/uaccess.h>
	32
	33	MODULE_LICENSE("GPL");
	34	MODULE_DESCRIPTION("loop blockdevice transferfunction adaptor / CryptoAPI");
	35	MODULE_AUTHOR("Herbert Valerio Riedel <hvr@gnu.org>");
	36
	37	#define LOOP_IV_SECTOR_BITS 9
	38	#define LOOP_IV_SECTOR_SIZE (1 << LOOP_IV_SECTOR_BITS)
	39
	40	static int
	41	cryptoloop_init(struct loop_device lo, const struct loop_info64 info)
	42	{
	43	int err = -EINVAL;
69affe7f HX	44	int cipher_len;
69affe7f HX	45	int mode_len;
1da177e4 LT	46	char cms[LO_NAME_SIZE]; /* cipher-mode string */
	47	char *cipher;
	48	char *mode;
	49	char cmsp = cms; / c-m string pointer */
69affe7f	50	struct crypto_blkcipher *tfm;
1da177e4 LT	51
	52	/* encryption breaks for non sector aligned offsets */
	53
	54	if (info->lo_offset % LOOP_IV_SECTOR_SIZE)
	55	goto out;
	56
	57	strncpy(cms, info->lo_crypt_name, LO_NAME_SIZE);
	58	cms[LO_NAME_SIZE - 1] = 0;
69affe7f HX	59
	60	cipher = cmsp;
	61	cipher_len = strcspn(cmsp, "-");
	62
	63	mode = cmsp + cipher_len;
	64	mode_len = 0;
	65	if (*mode) {
	66	mode++;
	67	mode_len = strcspn(mode, "-");
	68	}
	69
	70	if (!mode_len) {
	71	mode = "cbc";
	72	mode_len = 3;
	73	}
	74
	75	if (cipher_len + mode_len + 3 > LO_NAME_SIZE)
1da177e4 LT	76	return -EINVAL;
1da177e4 LT	77
69affe7f HX	78	memmove(cms, mode, mode_len);
	79	cmsp = cms + mode_len;
	80	*cmsp++ = '(';
	81	memcpy(cmsp, info->lo_crypt_name, cipher_len);
	82	cmsp += cipher_len;
	83	*cmsp++ = ')';
	84	*cmsp = 0;
	85
	86	tfm = crypto_alloc_blkcipher(cms, 0, CRYPTO_ALG_ASYNC);
	87	if (IS_ERR(tfm))
	88	return PTR_ERR(tfm);
	89
	90	err = crypto_blkcipher_setkey(tfm, info->lo_encrypt_key,
	91	info->lo_encrypt_key_size);
1da177e4 LT	92
	93	if (err != 0)
	94	goto out_free_tfm;
	95
	96	lo->key_data = tfm;
	97	return 0;
	98
	99	out_free_tfm:
69affe7f	100	crypto_free_blkcipher(tfm);
1da177e4 LT	101
	102	out:
	103	return err;
	104	}
	105
	106
69affe7f	107	typedef int (encdec_cbc_t)(struct blkcipher_desc desc,
1da177e4 LT	108	struct scatterlist *sg_out,
	109	struct scatterlist *sg_in,
	110	unsigned int nsg);
	111
1da177e4	112	static int
69affe7f HX	113	cryptoloop_transfer(struct loop_device *lo, int cmd,
	114	struct page *raw_page, unsigned raw_off,
	115	struct page *loop_page, unsigned loop_off,
	116	int size, sector_t IV)
1da177e4	117	{
69affe7f HX	118	struct crypto_blkcipher *tfm = lo->key_data;
	119	struct blkcipher_desc desc = {
	120	.tfm = tfm,
	121	.flags = CRYPTO_TFM_REQ_MAY_SLEEP,
	122	};
45711f1a JA	123	struct scatterlist sg_out;
45711f1a JA	124	struct scatterlist sg_in;
1da177e4 LT	125
	126	encdec_cbc_t encdecfunc;
	127	struct page in_page, out_page;
	128	unsigned in_offs, out_offs;
69affe7f	129	int err;
1da177e4	130
45711f1a JA	131	sg_init_table(&sg_out, 1);
	132	sg_init_table(&sg_in, 1);
	133
1da177e4 LT	134	if (cmd == READ) {
	135	in_page = raw_page;
	136	in_offs = raw_off;
	137	out_page = loop_page;
	138	out_offs = loop_off;
69affe7f	139	encdecfunc = crypto_blkcipher_crt(tfm)->decrypt;
1da177e4 LT	140	} else {
	141	in_page = loop_page;
	142	in_offs = loop_off;
	143	out_page = raw_page;
	144	out_offs = raw_off;
69affe7f	145	encdecfunc = crypto_blkcipher_crt(tfm)->encrypt;
1da177e4 LT	146	}
	147
	148	while (size > 0) {
	149	const int sz = min(size, LOOP_IV_SECTOR_SIZE);
	150	u32 iv[4] = { 0, };
	151	iv[0] = cpu_to_le32(IV & 0xffffffff);
	152
642f1490 JA	153	sg_set_page(&sg_in, in_page, sz, in_offs);
642f1490 JA	154	sg_set_page(&sg_out, out_page, sz, out_offs);
1da177e4	155
69affe7f HX	156	desc.info = iv;
	157	err = encdecfunc(&desc, &sg_out, &sg_in, sz);
	158	if (err)
	159	return err;
1da177e4 LT	160
	161	IV++;
	162	size -= sz;
	163	in_offs += sz;
	164	out_offs += sz;
	165	}
	166
	167	return 0;
	168	}
	169
1da177e4 LT	170	static int
	171	cryptoloop_ioctl(struct loop_device *lo, int cmd, unsigned long arg)
	172	{
	173	return -EINVAL;
	174	}
	175
	176	static int
	177	cryptoloop_release(struct loop_device *lo)
	178	{
69affe7f	179	struct crypto_blkcipher *tfm = lo->key_data;
1da177e4	180	if (tfm != NULL) {
69affe7f	181	crypto_free_blkcipher(tfm);
1da177e4 LT	182	lo->key_data = NULL;
	183	return 0;
	184	}
	185	printk(KERN_ERR "cryptoloop_release(): tfm == NULL?\n");
	186	return -EINVAL;
	187	}
	188
	189	static struct loop_func_table cryptoloop_funcs = {
	190	.number = LO_CRYPT_CRYPTOAPI,
	191	.init = cryptoloop_init,
	192	.ioctl = cryptoloop_ioctl,
	193	.transfer = cryptoloop_transfer,
	194	.release = cryptoloop_release,
	195	.owner = THIS_MODULE
	196	};
	197
	198	static int __init
	199	init_cryptoloop(void)
	200	{
	201	int rc = loop_register_transfer(&cryptoloop_funcs);
	202
	203	if (rc)
	204	printk(KERN_ERR "cryptoloop: loop_register_transfer failed\n");
	205	return rc;
	206	}
	207
	208	static void __exit
	209	cleanup_cryptoloop(void)
	210	{
	211	if (loop_unregister_transfer(LO_CRYPT_CRYPTOAPI))
	212	printk(KERN_ERR
	213	"cryptoloop: loop_unregister_transfer failed\n");
	214	}
	215
	216	module_init(init_cryptoloop);
	217	module_exit(cleanup_cryptoloop);