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 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 = { NULL, };
123 struct scatterlist sg_in = { NULL, };
124
125 encdec_cbc_t encdecfunc;
126 struct page *in_page, *out_page;
127 unsigned in_offs, out_offs;
128 int err;
129
130 if (cmd == READ) {
131 in_page = raw_page;
132 in_offs = raw_off;
133 out_page = loop_page;
134 out_offs = loop_off;
135 encdecfunc = crypto_blkcipher_crt(tfm)->decrypt;
136 } else {
137 in_page = loop_page;
138 in_offs = loop_off;
139 out_page = raw_page;
140 out_offs = raw_off;
141 encdecfunc = crypto_blkcipher_crt(tfm)->encrypt;
142 }
143
144 while (size > 0) {
145 const int sz = min(size, LOOP_IV_SECTOR_SIZE);
146 u32 iv[4] = { 0, };
147 iv[0] = cpu_to_le32(IV & 0xffffffff);
148
149 sg_in.page = in_page;
150 sg_in.offset = in_offs;
151 sg_in.length = sz;
152
153 sg_out.page = out_page;
154 sg_out.offset = out_offs;
155 sg_out.length = sz;
156
157 desc.info = iv;
158 err = encdecfunc(&desc, &sg_out, &sg_in, sz);
159 if (err)
160 return err;
161
162 IV++;
163 size -= sz;
164 in_offs += sz;
165 out_offs += sz;
166 }
167
168 return 0;
169}
170
171static int
172cryptoloop_ioctl(struct loop_device *lo, int cmd, unsigned long arg)
173{
174 return -EINVAL;
175}
176
177static int
178cryptoloop_release(struct loop_device *lo)
179{
180 struct crypto_blkcipher *tfm = lo->key_data;
181 if (tfm != NULL) {
182 crypto_free_blkcipher(tfm);
183 lo->key_data = NULL;
184 return 0;
185 }
186 printk(KERN_ERR "cryptoloop_release(): tfm == NULL?\n");
187 return -EINVAL;
188}
189
190static struct loop_func_table cryptoloop_funcs = {
191 .number = LO_CRYPT_CRYPTOAPI,
192 .init = cryptoloop_init,
193 .ioctl = cryptoloop_ioctl,
194 .transfer = cryptoloop_transfer,
195 .release = cryptoloop_release,
196 .owner = THIS_MODULE
197};
198
199static int __init
200init_cryptoloop(void)
201{
202 int rc = loop_register_transfer(&cryptoloop_funcs);
203
204 if (rc)
205 printk(KERN_ERR "cryptoloop: loop_register_transfer failed\n");
206 return rc;
207}
208
209static void __exit
210cleanup_cryptoloop(void)
211{
212 if (loop_unregister_transfer(LO_CRYPT_CRYPTOAPI))
213 printk(KERN_ERR
214 "cryptoloop: loop_unregister_transfer failed\n");
215}
216
217module_init(init_cryptoloop);
218module_exit(cleanup_cryptoloop);