drivers/block/cryptoloop.c

   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>
  29 #include <asm/semaphore.h>
  30 #include <asm/uaccess.h>
  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;
  43         char cms[LO_NAME_SIZE];                 /* cipher-mode string */
  44         char *cipher;
  45         char *mode;
  46         char *cmsp = cms;                       /* c-m string pointer */
  47         struct crypto_tfm *tfm = NULL;
  48
  49         /* encryption breaks for non sector aligned offsets */
  50
  51         if (info->lo_offset % LOOP_IV_SECTOR_SIZE)
  52                 goto out;
  53
  54         strncpy(cms, info->lo_crypt_name, LO_NAME_SIZE);
  55         cms[LO_NAME_SIZE - 1] = 0;
  56         cipher = strsep(&cmsp, "-");
  57         mode = strsep(&cmsp, "-");
  58
  59         if (mode == NULL || strcmp(mode, "cbc") == 0)
  60                 tfm = crypto_alloc_tfm(cipher, CRYPTO_TFM_MODE_CBC);
  61         else if (strcmp(mode, "ecb") == 0)
  62                 tfm = crypto_alloc_tfm(cipher, CRYPTO_TFM_MODE_ECB);
  63         if (tfm == NULL)
  64                 return -EINVAL;
  65
  66         err = tfm->crt_u.cipher.cit_setkey(tfm, info->lo_encrypt_key,
  67                                            info->lo_encrypt_key_size);
  68
  69         if (err != 0)
  70                 goto out_free_tfm;
  71
  72         lo->key_data = tfm;
  73         return 0;
  74
  75  out_free_tfm:
  76         crypto_free_tfm(tfm);
  77
  78  out:
  79         return err;
  80 }
  81
  82
  83 typedef int (*encdec_ecb_t)(struct crypto_tfm *tfm,
  84                         struct scatterlist *sg_out,
  85                         struct scatterlist *sg_in,
  86                         unsigned int nsg);
  87
  88
  89 static int
  90 cryptoloop_transfer_ecb(struct loop_device *lo, int cmd,
  91                         struct page *raw_page, unsigned raw_off,
  92                         struct page *loop_page, unsigned loop_off,
  93                         int size, sector_t IV)
  94 {
  95         struct crypto_tfm *tfm = (struct crypto_tfm *) lo->key_data;
  96         struct scatterlist sg_out = { NULL, };
  97         struct scatterlist sg_in = { NULL, };
  98
  99         encdec_ecb_t encdecfunc;
 100         struct page *in_page, *out_page;
 101         unsigned in_offs, out_offs;
 102
 103         if (cmd == READ) {
 104                 in_page = raw_page;
 105                 in_offs = raw_off;
 106                 out_page = loop_page;
 107                 out_offs = loop_off;
 108                 encdecfunc = tfm->crt_u.cipher.cit_decrypt;
 109         } else {
 110                 in_page = loop_page;
 111                 in_offs = loop_off;
 112                 out_page = raw_page;
 113                 out_offs = raw_off;
 114                 encdecfunc = tfm->crt_u.cipher.cit_encrypt;
 115         }
 116
 117         while (size > 0) {
 118                 const int sz = min(size, LOOP_IV_SECTOR_SIZE);
 119
 120                 sg_in.page = in_page;
 121                 sg_in.offset = in_offs;
 122                 sg_in.length = sz;
 123
 124                 sg_out.page = out_page;
 125                 sg_out.offset = out_offs;
 126                 sg_out.length = sz;
 127
 128                 encdecfunc(tfm, &sg_out, &sg_in, sz);
 129
 130                 size -= sz;
 131                 in_offs += sz;
 132                 out_offs += sz;
 133         }
 134
 135         return 0;
 136 }
 137
 138 typedef int (*encdec_cbc_t)(struct crypto_tfm *tfm,
 139                         struct scatterlist *sg_out,
 140                         struct scatterlist *sg_in,
 141                         unsigned int nsg, u8 *iv);
 142
 143 static int
 144 cryptoloop_transfer_cbc(struct loop_device *lo, int cmd,
 145                         struct page *raw_page, unsigned raw_off,
 146                         struct page *loop_page, unsigned loop_off,
 147                         int size, sector_t IV)
 148 {
 149         struct crypto_tfm *tfm = (struct crypto_tfm *) lo->key_data;
 150         struct scatterlist sg_out = { NULL, };
 151         struct scatterlist sg_in = { NULL, };
 152
 153         encdec_cbc_t encdecfunc;
 154         struct page *in_page, *out_page;
 155         unsigned in_offs, out_offs;
 156
 157         if (cmd == READ) {
 158                 in_page = raw_page;
 159                 in_offs = raw_off;
 160                 out_page = loop_page;
 161                 out_offs = loop_off;
 162                 encdecfunc = tfm->crt_u.cipher.cit_decrypt_iv;
 163         } else {
 164                 in_page = loop_page;
 165                 in_offs = loop_off;
 166                 out_page = raw_page;
 167                 out_offs = raw_off;
 168                 encdecfunc = tfm->crt_u.cipher.cit_encrypt_iv;
 169         }
 170
 171         while (size > 0) {
 172                 const int sz = min(size, LOOP_IV_SECTOR_SIZE);
 173                 u32 iv[4] = { 0, };
 174                 iv[0] = cpu_to_le32(IV & 0xffffffff);
 175
 176                 sg_in.page = in_page;
 177                 sg_in.offset = in_offs;
 178                 sg_in.length = sz;
 179
 180                 sg_out.page = out_page;
 181                 sg_out.offset = out_offs;
 182                 sg_out.length = sz;
 183
 184                 encdecfunc(tfm, &sg_out, &sg_in, sz, (u8 *)iv);
 185
 186                 IV++;
 187                 size -= sz;
 188                 in_offs += sz;
 189                 out_offs += sz;
 190         }
 191
 192         return 0;
 193 }
 194
 195 static int
 196 cryptoloop_transfer(struct loop_device *lo, int cmd,
 197                     struct page *raw_page, unsigned raw_off,
 198                     struct page *loop_page, unsigned loop_off,
 199                     int size, sector_t IV)
 200 {
 201         struct crypto_tfm *tfm = (struct crypto_tfm *) lo->key_data;
 202         if(tfm->crt_cipher.cit_mode == CRYPTO_TFM_MODE_ECB)
 203         {
 204                 lo->transfer = cryptoloop_transfer_ecb;
 205                 return cryptoloop_transfer_ecb(lo, cmd, raw_page, raw_off,
 206                                                loop_page, loop_off, size, IV);
 207         }
 208         if(tfm->crt_cipher.cit_mode == CRYPTO_TFM_MODE_CBC)
 209         {
 210                 lo->transfer = cryptoloop_transfer_cbc;
 211                 return cryptoloop_transfer_cbc(lo, cmd, raw_page, raw_off,
 212                                                loop_page, loop_off, size, IV);
 213         }
 214
 215         /*  This is not supposed to happen */
 216
 217         printk( KERN_ERR "cryptoloop: unsupported cipher mode in cryptoloop_transfer!\n");
 218         return -EINVAL;
 219 }
 220
 221 static int
 222 cryptoloop_ioctl(struct loop_device *lo, int cmd, unsigned long arg)
 223 {
 224         return -EINVAL;
 225 }
 226
 227 static int
 228 cryptoloop_release(struct loop_device *lo)
 229 {
 230         struct crypto_tfm *tfm = (struct crypto_tfm *) lo->key_data;
 231         if (tfm != NULL) {
 232                 crypto_free_tfm(tfm);
 233                 lo->key_data = NULL;
 234                 return 0;
 235         }
 236         printk(KERN_ERR "cryptoloop_release(): tfm == NULL?\n");
 237         return -EINVAL;
 238 }
 239
 240 static struct loop_func_table cryptoloop_funcs = {
 241         .number = LO_CRYPT_CRYPTOAPI,
 242         .init = cryptoloop_init,
 243         .ioctl = cryptoloop_ioctl,
 244         .transfer = cryptoloop_transfer,
 245         .release = cryptoloop_release,
 246         .owner = THIS_MODULE
 247 };
 248
 249 static int __init
 250 init_cryptoloop(void)
 251 {
 252         int rc = loop_register_transfer(&cryptoloop_funcs);
 253
 254         if (rc)
 255                 printk(KERN_ERR "cryptoloop: loop_register_transfer failed\n");
 256         return rc;
 257 }
 258
 259 static void __exit
 260 cleanup_cryptoloop(void)
 261 {
 262         if (loop_unregister_transfer(LO_CRYPT_CRYPTOAPI))
 263                 printk(KERN_ERR
 264                         "cryptoloop: loop_unregister_transfer failed\n");
 265 }
 266
 267 module_init(init_cryptoloop);
 268 module_exit(cleanup_cryptoloop);