[deliverable/linux.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/scatterlist.h>
#include <asm/uaccess.h>
#include "loop.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>
45711f1a	28	#include <linux/scatterlist.h>
1da177e4	29	#include <asm/uaccess.h>
83a87611	30	#include "loop.h"
1da177e4 LT	31
	32	MODULE_LICENSE("GPL");
	33	MODULE_DESCRIPTION("loop blockdevice transferfunction adaptor / CryptoAPI");
	34	MODULE_AUTHOR("Herbert Valerio Riedel <hvr@gnu.org>");
	35
	36	#define LOOP_IV_SECTOR_BITS 9
	37	#define LOOP_IV_SECTOR_SIZE (1 << LOOP_IV_SECTOR_BITS)
	38
	39	static int
	40	cryptoloop_init(struct loop_device lo, const struct loop_info64 info)
	41	{
	42	int err = -EINVAL;
69affe7f HX	43	int cipher_len;
69affe7f HX	44	int mode_len;
1da177e4 LT	45	char cms[LO_NAME_SIZE]; /* cipher-mode string */
	46	char *cipher;
	47	char *mode;
	48	char cmsp = cms; / c-m string pointer */
69affe7f	49	struct crypto_blkcipher *tfm;
1da177e4 LT	50
	51	/* encryption breaks for non sector aligned offsets */
	52
	53	if (info->lo_offset % LOOP_IV_SECTOR_SIZE)
	54	goto out;
	55
	56	strncpy(cms, info->lo_crypt_name, LO_NAME_SIZE);
	57	cms[LO_NAME_SIZE - 1] = 0;
69affe7f HX	58
	59	cipher = cmsp;
	60	cipher_len = strcspn(cmsp, "-");
	61
	62	mode = cmsp + cipher_len;
	63	mode_len = 0;
	64	if (*mode) {
	65	mode++;
	66	mode_len = strcspn(mode, "-");
	67	}
	68
	69	if (!mode_len) {
	70	mode = "cbc";
	71	mode_len = 3;
	72	}
	73
	74	if (cipher_len + mode_len + 3 > LO_NAME_SIZE)
1da177e4 LT	75	return -EINVAL;
1da177e4 LT	76
69affe7f HX	77	memmove(cms, mode, mode_len);
	78	cmsp = cms + mode_len;
	79	*cmsp++ = '(';
	80	memcpy(cmsp, info->lo_crypt_name, cipher_len);
	81	cmsp += cipher_len;
	82	*cmsp++ = ')';
	83	*cmsp = 0;
	84
	85	tfm = crypto_alloc_blkcipher(cms, 0, CRYPTO_ALG_ASYNC);
	86	if (IS_ERR(tfm))
	87	return PTR_ERR(tfm);
	88
	89	err = crypto_blkcipher_setkey(tfm, info->lo_encrypt_key,
	90	info->lo_encrypt_key_size);
1da177e4 LT	91
	92	if (err != 0)
	93	goto out_free_tfm;
	94
	95	lo->key_data = tfm;
	96	return 0;
	97
	98	out_free_tfm:
69affe7f	99	crypto_free_blkcipher(tfm);
1da177e4 LT	100
	101	out:
	102	return err;
	103	}
	104
	105
69affe7f	106	typedef int (encdec_cbc_t)(struct blkcipher_desc desc,
1da177e4 LT	107	struct scatterlist *sg_out,
	108	struct scatterlist *sg_in,
	109	unsigned int nsg);
	110
1da177e4	111	static int
69affe7f HX	112	cryptoloop_transfer(struct loop_device *lo, int cmd,
	113	struct page *raw_page, unsigned raw_off,
	114	struct page *loop_page, unsigned loop_off,
	115	int size, sector_t IV)
1da177e4	116	{
69affe7f HX	117	struct crypto_blkcipher *tfm = lo->key_data;
	118	struct blkcipher_desc desc = {
	119	.tfm = tfm,
	120	.flags = CRYPTO_TFM_REQ_MAY_SLEEP,
	121	};
45711f1a JA	122	struct scatterlist sg_out;
45711f1a JA	123	struct scatterlist sg_in;
1da177e4 LT	124
	125	encdec_cbc_t encdecfunc;
	126	struct page in_page, out_page;
	127	unsigned in_offs, out_offs;
69affe7f	128	int err;
1da177e4	129
45711f1a JA	130	sg_init_table(&sg_out, 1);
	131	sg_init_table(&sg_in, 1);
	132
1da177e4 LT	133	if (cmd == READ) {
	134	in_page = raw_page;
	135	in_offs = raw_off;
	136	out_page = loop_page;
	137	out_offs = loop_off;
69affe7f	138	encdecfunc = crypto_blkcipher_crt(tfm)->decrypt;
1da177e4 LT	139	} else {
	140	in_page = loop_page;
	141	in_offs = loop_off;
	142	out_page = raw_page;
	143	out_offs = raw_off;
69affe7f	144	encdecfunc = crypto_blkcipher_crt(tfm)->encrypt;
1da177e4 LT	145	}
	146
	147	while (size > 0) {
	148	const int sz = min(size, LOOP_IV_SECTOR_SIZE);
	149	u32 iv[4] = { 0, };
	150	iv[0] = cpu_to_le32(IV & 0xffffffff);
	151
642f1490 JA	152	sg_set_page(&sg_in, in_page, sz, in_offs);
642f1490 JA	153	sg_set_page(&sg_out, out_page, sz, out_offs);
1da177e4	154
69affe7f HX	155	desc.info = iv;
	156	err = encdecfunc(&desc, &sg_out, &sg_in, sz);
	157	if (err)
	158	return err;
1da177e4 LT	159
	160	IV++;
	161	size -= sz;
	162	in_offs += sz;
	163	out_offs += sz;
	164	}
	165
	166	return 0;
	167	}
	168
1da177e4 LT	169	static int
	170	cryptoloop_ioctl(struct loop_device *lo, int cmd, unsigned long arg)
	171	{
	172	return -EINVAL;
	173	}
	174
	175	static int
	176	cryptoloop_release(struct loop_device *lo)
	177	{
69affe7f	178	struct crypto_blkcipher *tfm = lo->key_data;
1da177e4	179	if (tfm != NULL) {
69affe7f	180	crypto_free_blkcipher(tfm);
1da177e4 LT	181	lo->key_data = NULL;
	182	return 0;
	183	}
	184	printk(KERN_ERR "cryptoloop_release(): tfm == NULL?\n");
	185	return -EINVAL;
	186	}
	187
	188	static struct loop_func_table cryptoloop_funcs = {
	189	.number = LO_CRYPT_CRYPTOAPI,
	190	.init = cryptoloop_init,
	191	.ioctl = cryptoloop_ioctl,
	192	.transfer = cryptoloop_transfer,
	193	.release = cryptoloop_release,
	194	.owner = THIS_MODULE
	195	};
	196
	197	static int __init
	198	init_cryptoloop(void)
	199	{
	200	int rc = loop_register_transfer(&cryptoloop_funcs);
	201
	202	if (rc)
	203	printk(KERN_ERR "cryptoloop: loop_register_transfer failed\n");
	204	return rc;
	205	}
	206
	207	static void __exit
	208	cleanup_cryptoloop(void)
	209	{
	210	if (loop_unregister_transfer(LO_CRYPT_CRYPTOAPI))
	211	printk(KERN_ERR
	212	"cryptoloop: loop_unregister_transfer failed\n");
	213	}
	214
	215	module_init(init_cryptoloop);
	216	module_exit(cleanup_cryptoloop);