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