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22#include <linux/module.h>
23
24#include <crypto/skcipher.h>
25#include <linux/init.h>
26#include <linux/string.h>
27#include <linux/blkdev.h>
28#include <linux/scatterlist.h>
29#include <linux/uaccess.h>
30#include "loop.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_skcipher *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_skcipher(cms, 0, CRYPTO_ALG_ASYNC);
86 if (IS_ERR(tfm))
87 return PTR_ERR(tfm);
88
89 err = crypto_skcipher_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_skcipher(tfm);
100
101 out:
102 return err;
103}
104
105
106typedef int (*encdec_cbc_t)(struct skcipher_request *req);
107
108static int
109cryptoloop_transfer(struct loop_device *lo, int cmd,
110 struct page *raw_page, unsigned raw_off,
111 struct page *loop_page, unsigned loop_off,
112 int size, sector_t IV)
113{
114 struct crypto_skcipher *tfm = lo->key_data;
115 SKCIPHER_REQUEST_ON_STACK(req, tfm);
116 struct scatterlist sg_out;
117 struct scatterlist sg_in;
118
119 encdec_cbc_t encdecfunc;
120 struct page *in_page, *out_page;
121 unsigned in_offs, out_offs;
122 int err;
123
124 skcipher_request_set_tfm(req, tfm);
125 skcipher_request_set_callback(req, CRYPTO_TFM_REQ_MAY_SLEEP,
126 NULL, NULL);
127
128 sg_init_table(&sg_out, 1);
129 sg_init_table(&sg_in, 1);
130
131 if (cmd == READ) {
132 in_page = raw_page;
133 in_offs = raw_off;
134 out_page = loop_page;
135 out_offs = loop_off;
136 encdecfunc = crypto_skcipher_decrypt;
137 } else {
138 in_page = loop_page;
139 in_offs = loop_off;
140 out_page = raw_page;
141 out_offs = raw_off;
142 encdecfunc = crypto_skcipher_encrypt;
143 }
144
145 while (size > 0) {
146 const int sz = min(size, LOOP_IV_SECTOR_SIZE);
147 u32 iv[4] = { 0, };
148 iv[0] = cpu_to_le32(IV & 0xffffffff);
149
150 sg_set_page(&sg_in, in_page, sz, in_offs);
151 sg_set_page(&sg_out, out_page, sz, out_offs);
152
153 skcipher_request_set_crypt(req, &sg_in, &sg_out, sz, iv);
154 err = encdecfunc(req);
155 if (err)
156 goto out;
157
158 IV++;
159 size -= sz;
160 in_offs += sz;
161 out_offs += sz;
162 }
163
164 err = 0;
165
166out:
167 skcipher_request_zero(req);
168 return err;
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_skcipher *tfm = lo->key_data;
181 if (tfm != NULL) {
182 crypto_free_skcipher(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);
219
