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 <linux/scatterlist.h> 30#include <asm/uaccess.h> 31 32MODULE_LICENSE("GPL"); 33MODULE_DESCRIPTION("loop blockdevice transferfunction adaptor / CryptoAPI"); 34MODULE_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 39static int 40cryptoloop_init(struct loop_device *lo, const struct loop_info64 *info) 41{ 42 int err = -EINVAL; 43 int cipher_len; 44 int mode_len; 45 char cms[LO_NAME_SIZE]; /* cipher-mode string */ 46 char *cipher; 47 char *mode; 48 char *cmsp = cms; /* c-m string pointer */ 49 struct crypto_blkcipher *tfm; 50 51 /* encryption breaks for non sector aligned offsets */ 52 53 if (info->lo_offset % LOOP_IV_SECTOR_SIZE) 54 goto out; 55 56 strncpy(cms, info->lo_crypt_name, LO_NAME_SIZE); 57 cms[LO_NAME_SIZE - 1] = 0; 58 59 cipher = cmsp; 60 cipher_len = strcspn(cmsp, "-"); 61 62 mode = cmsp + cipher_len; 63 mode_len = 0; 64 if (*mode) { 65 mode++; 66 mode_len = strcspn(mode, "-"); 67 } 68 69 if (!mode_len) { 70 mode = "cbc"; 71 mode_len = 3; 72 } 73 74 if (cipher_len + mode_len + 3 > LO_NAME_SIZE) 75 return -EINVAL; 76 77 memmove(cms, mode, mode_len); 78 cmsp = cms + mode_len; 79 *cmsp++ = '('; 80 memcpy(cmsp, info->lo_crypt_name, cipher_len); 81 cmsp += cipher_len; 82 *cmsp++ = ')'; 83 *cmsp = 0; 84 85 tfm = crypto_alloc_blkcipher(cms, 0, CRYPTO_ALG_ASYNC); 86 if (IS_ERR(tfm)) 87 return PTR_ERR(tfm); 88 89 err = crypto_blkcipher_setkey(tfm, info->lo_encrypt_key, 90 info->lo_encrypt_key_size); 91 92 if (err != 0) 93 goto out_free_tfm; 94 95 lo->key_data = tfm; 96 return 0; 97 98 out_free_tfm: 99 crypto_free_blkcipher(tfm); 100 101 out: 102 return err; 103} 104 105 106typedef int (*encdec_cbc_t)(struct blkcipher_desc *desc, 107 struct scatterlist *sg_out, 108 struct scatterlist *sg_in, 109 unsigned int nsg); 110 111static int 112cryptoloop_transfer(struct loop_device *lo, int cmd, 113 struct page *raw_page, unsigned raw_off, 114 struct page *loop_page, unsigned loop_off, 115 int size, sector_t IV) 116{ 117 struct crypto_blkcipher *tfm = lo->key_data; 118 struct blkcipher_desc desc = { 119 .tfm = tfm, 120 .flags = CRYPTO_TFM_REQ_MAY_SLEEP, 121 }; 122 struct scatterlist sg_out; 123 struct scatterlist sg_in; 124 125 encdec_cbc_t encdecfunc; 126 struct page *in_page, *out_page; 127 unsigned in_offs, out_offs; 128 int err; 129 130 sg_init_table(&sg_out, 1); 131 sg_init_table(&sg_in, 1); 132 133 if (cmd == READ) { 134 in_page = raw_page; 135 in_offs = raw_off; 136 out_page = loop_page; 137 out_offs = loop_off; 138 encdecfunc = crypto_blkcipher_crt(tfm)->decrypt; 139 } else { 140 in_page = loop_page; 141 in_offs = loop_off; 142 out_page = raw_page; 143 out_offs = raw_off; 144 encdecfunc = crypto_blkcipher_crt(tfm)->encrypt; 145 } 146 147 while (size > 0) { 148 const int sz = min(size, LOOP_IV_SECTOR_SIZE); 149 u32 iv[4] = { 0, }; 150 iv[0] = cpu_to_le32(IV & 0xffffffff); 151 152 sg_set_page(&sg_in, in_page, sz, in_offs); 153 sg_set_page(&sg_out, out_page, sz, out_offs); 154 155 desc.info = iv; 156 err = encdecfunc(&desc, &sg_out, &sg_in, sz); 157 if (err) 158 return err; 159 160 IV++; 161 size -= sz; 162 in_offs += sz; 163 out_offs += sz; 164 } 165 166 return 0; 167} 168 169static int 170cryptoloop_ioctl(struct loop_device *lo, int cmd, unsigned long arg) 171{ 172 return -EINVAL; 173} 174 175static int 176cryptoloop_release(struct loop_device *lo) 177{ 178 struct crypto_blkcipher *tfm = lo->key_data; 179 if (tfm != NULL) { 180 crypto_free_blkcipher(tfm); 181 lo->key_data = NULL; 182 return 0; 183 } 184 printk(KERN_ERR "cryptoloop_release(): tfm == NULL?\n"); 185 return -EINVAL; 186} 187 188static struct loop_func_table cryptoloop_funcs = { 189 .number = LO_CRYPT_CRYPTOAPI, 190 .init = cryptoloop_init, 191 .ioctl = cryptoloop_ioctl, 192 .transfer = cryptoloop_transfer, 193 .release = cryptoloop_release, 194 .owner = THIS_MODULE 195}; 196 197static int __init 198init_cryptoloop(void) 199{ 200 int rc = loop_register_transfer(&cryptoloop_funcs); 201 202 if (rc) 203 printk(KERN_ERR "cryptoloop: loop_register_transfer failed\n"); 204 return rc; 205} 206 207static void __exit 208cleanup_cryptoloop(void) 209{ 210 if (loop_unregister_transfer(LO_CRYPT_CRYPTOAPI)) 211 printk(KERN_ERR 212 "cryptoloop: loop_unregister_transfer failed\n"); 213} 214 215module_init(init_cryptoloop); 216module_exit(cleanup_cryptoloop); 217