diff options
Diffstat (limited to 'drivers/block/cryptoloop.c')
| -rw-r--r-- | drivers/block/cryptoloop.c | 216 |
1 files changed, 216 insertions, 0 deletions
diff --git a/drivers/block/cryptoloop.c b/drivers/block/cryptoloop.c new file mode 100644 index 000000000..99e773cb7 --- /dev/null +++ b/drivers/block/cryptoloop.c @@ -0,0 +1,216 @@ +/* + 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); |