/*
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 <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;
char cms[LO_NAME_SIZE]; /* cipher-mode string */
char *cipher;
char *mode;
char *cmsp = cms; /* c-m string pointer */
struct crypto_tfm *tfm = NULL;
/* 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 = strsep(&cmsp, "-");
mode = strsep(&cmsp, "-");
if (mode == NULL || strcmp(mode, "cbc") == 0)
tfm = crypto_alloc_tfm(cipher, CRYPTO_TFM_MODE_CBC);
else if (strcmp(mode, "ecb") == 0)
tfm = crypto_alloc_tfm(cipher, CRYPTO_TFM_MODE_ECB);
if (tfm == NULL)
return -EINVAL;
err = tfm->crt_u.cipher.cit_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_tfm(tfm);
out:
return err;
}
typedef int (*encdec_ecb_t)(struct crypto_tfm *tfm,
struct scatterlist *sg_out,
struct scatterlist *sg_in,
unsigned int nsg);
static int
cryptoloop_transfer_ecb(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_tfm *tfm = (struct crypto_tfm *) lo->key_data;
struct scatterlist sg_out = { NULL, };
struct scatterlist sg_in = { NULL, };
encdec_ecb_t encdecfunc;
struct page *in_page, *out_page;
unsigned in_offs, out_offs;
if (cmd == READ) {
in_page = raw_page;
in_offs = raw_off;
out_page = loop_page;
out_offs = loop_off;
encdecfunc = tfm->crt_u.cipher.cit_decrypt;
} else {
in_page = loop_page;
in_offs = loop_off;
out_page = raw_page;
out_offs = raw_off;
encdecfunc = tfm->crt_u.cipher.cit_encrypt;
}
while (size > 0) {
const int sz = min(size, LOOP_IV_SECTOR_SIZE);
sg_in.page = in_page;
sg_in.offset = in_offs;
sg_in.length = sz;
sg_out.page = out_page;
sg_out.offset = out_offs;
sg_out.length = sz;
encdecfunc(tfm, &sg_out, &sg_in, sz);
size -= sz;
in_offs += sz;
out_offs += sz;
}
return 0;
}
typedef int (*encdec_cbc_t)(struct crypto_tfm *tfm,
struct scatterlist *sg_out,
struct scatterlist *sg_in,
unsigned int nsg, u8 *iv);
static int
cryptoloop_transfer_cbc(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_tfm *tfm = (struct crypto_tfm *) lo->key_data;
struct scatterlist sg_out = { NULL, };
struct scatterlist sg_in = { NULL, };
encdec_cbc_t encdecfunc;
struct page *in_page, *out_page;
unsigned in_offs, out_offs;
if (cmd == READ) {
in_page = raw_page;
in_offs = raw_off;
out_page = loop_page;
out_offs = loop_off;
encdecfunc = tfm->crt_u.cipher.cit_decrypt_iv;
} else {
in_page = loop_page;
in_offs = loop_off;
out_page = raw_page;
out_offs = raw_off;
encdecfunc = tfm->crt_u.cipher.cit_encrypt_iv;
}
while (size > 0) {
const int sz = min(size, LOOP_IV_SECTOR_SIZE);
u32 iv[4] = { 0, };
iv[0] = cpu_to_le32(IV & 0xffffffff);
sg_in.page = in_page;
sg_in.offset = in_offs;
sg_in.length = sz;
sg_out.page = out_page;
sg_out.offset = out_offs;
sg_out.length = sz;
encdecfunc(tfm, &sg_out, &sg_in, sz, (u8 *)iv);
IV++;
size -= sz;
in_offs += sz;
out_offs += sz;
}
return 0;
}
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_tfm *tfm = (struct crypto_tfm *) lo->key_data;
if(tfm->crt_cipher.cit_mode == CRYPTO_TFM_MODE_ECB)
{
lo->transfer = cryptoloop_transfer_ecb;
return cryptoloop_transfer_ecb(lo, cmd, raw_page, raw_off,
loop_page, loop_off, size, IV);
}
if(tfm->crt_cipher.cit_mode == CRYPTO_TFM_MODE_CBC)
{
lo->transfer = cryptoloop_transfer_cbc;
return cryptoloop_transfer_cbc(lo, cmd, raw_page, raw_off,
loop_page, loop_off, size, IV);
}
/* This is not supposed to happen */
printk( KERN_ERR "cryptoloop: unsupported cipher mode in cryptoloop_transfer!\n");
return -EINVAL;
}
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_tfm *tfm = (struct crypto_tfm *) lo->key_data;
if (tfm != NULL) {
crypto_free_tfm(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);
