Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
tjh.dev
kernel
os
linux
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
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 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
85typedef int (*encdec_ecb_t)(struct crypto_tfm *tfm,
86 struct scatterlist *sg_out,
87 struct scatterlist *sg_in,
88 unsigned int nsg);
89
90
91static int
92cryptoloop_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
140typedef 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
145static int
146cryptoloop_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
197static int
198cryptoloop_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
223static int
224cryptoloop_ioctl(struct loop_device *lo, int cmd, unsigned long arg)
225{
226 return -EINVAL;
227}
228
229static int
230cryptoloop_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
242static 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
251static int __init
252init_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
261static void __exit
262cleanup_cryptoloop(void)
263{
264 if (loop_unregister_transfer(LO_CRYPT_CRYPTOAPI))
265 printk(KERN_ERR
266 "cryptoloop: loop_unregister_transfer failed\n");
267}
268
269module_init(init_cryptoloop);
270module_exit(cleanup_cryptoloop);