/*

Linux loop encryption enabling module

Copyright (C) 2002 Herbert Valerio Riedel <[email protected]>

Copyright (C) 2003 Fruhwirth Clemens <[email protected]>

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 <[email protected]>");

#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);