1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
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];
46 char *cipher;
47 char *mode;
48 char *cmsp = cms;
49 struct crypto_blkcipher *tfm;
50
51
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
