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f19f511 [CRYPTO] xts: XTS blockcipher mode implementation without partial blocks
Rik Snel authored
1 /* XTS: as defined in IEEE1619/D16
2 * http://grouper.ieee.org/groups/1619/email/pdf00086.pdf
3 * (sector sizes which are not a multiple of 16 bytes are,
4 * however currently unsupported)
5 *
6 * Copyright (c) 2007 Rik Snel <rsnel@cube.dyndns.org>
7 *
8 * Based om ecb.c
9 * Copyright (c) 2006 Herbert Xu <herbert@gondor.apana.org.au>
10 *
11 * This program is free software; you can redistribute it and/or modify it
12 * under the terms of the GNU General Public License as published by the Free
13 * Software Foundation; either version 2 of the License, or (at your option)
14 * any later version.
15 */
16 #include <crypto/algapi.h>
17 #include <linux/err.h>
18 #include <linux/init.h>
19 #include <linux/kernel.h>
20 #include <linux/module.h>
21 #include <linux/scatterlist.h>
22 #include <linux/slab.h>
23
ce00455 @jkivilin crypto: xts: add interface for parallelized cipher implementations
jkivilin authored
24 #include <crypto/xts.h>
f19f511 [CRYPTO] xts: XTS blockcipher mode implementation without partial blocks
Rik Snel authored
25 #include <crypto/b128ops.h>
26 #include <crypto/gf128mul.h>
27
28 struct priv {
29 struct crypto_cipher *child;
30 struct crypto_cipher *tweak;
31 };
32
33 static int setkey(struct crypto_tfm *parent, const u8 *key,
34 unsigned int keylen)
35 {
36 struct priv *ctx = crypto_tfm_ctx(parent);
37 struct crypto_cipher *child = ctx->tweak;
38 u32 *flags = &parent->crt_flags;
39 int err;
40
41 /* key consists of keys of equal size concatenated, therefore
42 * the length must be even */
43 if (keylen % 2) {
44 /* tell the user why there was an error */
45 *flags |= CRYPTO_TFM_RES_BAD_KEY_LEN;
46 return -EINVAL;
47 }
48
25985ed @lucasdemarchi Fix common misspellings
lucasdemarchi authored
49 /* we need two cipher instances: one to compute the initial 'tweak'
f19f511 [CRYPTO] xts: XTS blockcipher mode implementation without partial blocks
Rik Snel authored
50 * by encrypting the IV (usually the 'plain' iv) and the other
51 * one to encrypt and decrypt the data */
52
53 /* tweak cipher, uses Key2 i.e. the second half of *key */
54 crypto_cipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
55 crypto_cipher_set_flags(child, crypto_tfm_get_flags(parent) &
56 CRYPTO_TFM_REQ_MASK);
57 err = crypto_cipher_setkey(child, key + keylen/2, keylen/2);
58 if (err)
59 return err;
60
61 crypto_tfm_set_flags(parent, crypto_cipher_get_flags(child) &
62 CRYPTO_TFM_RES_MASK);
63
64 child = ctx->child;
65
66 /* data cipher, uses Key1 i.e. the first half of *key */
67 crypto_cipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
68 crypto_cipher_set_flags(child, crypto_tfm_get_flags(parent) &
69 CRYPTO_TFM_REQ_MASK);
70 err = crypto_cipher_setkey(child, key, keylen/2);
71 if (err)
72 return err;
73
74 crypto_tfm_set_flags(parent, crypto_cipher_get_flags(child) &
75 CRYPTO_TFM_RES_MASK);
76
77 return 0;
78 }
79
80 struct sinfo {
6212f2c [CRYPTO] xts: Use proper alignment
Sebastian Siewior authored
81 be128 *t;
f19f511 [CRYPTO] xts: XTS blockcipher mode implementation without partial blocks
Rik Snel authored
82 struct crypto_tfm *tfm;
83 void (*fn)(struct crypto_tfm *, u8 *, const u8 *);
84 };
85
86 static inline void xts_round(struct sinfo *s, void *dst, const void *src)
87 {
6212f2c [CRYPTO] xts: Use proper alignment
Sebastian Siewior authored
88 be128_xor(dst, s->t, src); /* PP <- T xor P */
f19f511 [CRYPTO] xts: XTS blockcipher mode implementation without partial blocks
Rik Snel authored
89 s->fn(s->tfm, dst, dst); /* CC <- E(Key1,PP) */
6212f2c [CRYPTO] xts: Use proper alignment
Sebastian Siewior authored
90 be128_xor(dst, dst, s->t); /* C <- T xor CC */
f19f511 [CRYPTO] xts: XTS blockcipher mode implementation without partial blocks
Rik Snel authored
91 }
92
93 static int crypt(struct blkcipher_desc *d,
94 struct blkcipher_walk *w, struct priv *ctx,
95 void (*tw)(struct crypto_tfm *, u8 *, const u8 *),
96 void (*fn)(struct crypto_tfm *, u8 *, const u8 *))
97 {
98 int err;
99 unsigned int avail;
f9d2691 @jkivilin crypto: xts - use blocksize constant
jkivilin authored
100 const int bs = XTS_BLOCK_SIZE;
f19f511 [CRYPTO] xts: XTS blockcipher mode implementation without partial blocks
Rik Snel authored
101 struct sinfo s = {
102 .tfm = crypto_cipher_tfm(ctx->child),
103 .fn = fn
104 };
105 u8 *wsrc;
106 u8 *wdst;
107
108 err = blkcipher_walk_virt(d, w);
109 if (!w->nbytes)
110 return err;
111
6212f2c [CRYPTO] xts: Use proper alignment
Sebastian Siewior authored
112 s.t = (be128 *)w->iv;
f19f511 [CRYPTO] xts: XTS blockcipher mode implementation without partial blocks
Rik Snel authored
113 avail = w->nbytes;
114
115 wsrc = w->src.virt.addr;
116 wdst = w->dst.virt.addr;
117
118 /* calculate first value of T */
6212f2c [CRYPTO] xts: Use proper alignment
Sebastian Siewior authored
119 tw(crypto_cipher_tfm(ctx->tweak), w->iv, w->iv);
f19f511 [CRYPTO] xts: XTS blockcipher mode implementation without partial blocks
Rik Snel authored
120
121 goto first;
122
123 for (;;) {
124 do {
6212f2c [CRYPTO] xts: Use proper alignment
Sebastian Siewior authored
125 gf128mul_x_ble(s.t, s.t);
f19f511 [CRYPTO] xts: XTS blockcipher mode implementation without partial blocks
Rik Snel authored
126
127 first:
128 xts_round(&s, wdst, wsrc);
129
130 wsrc += bs;
131 wdst += bs;
132 } while ((avail -= bs) >= bs);
133
134 err = blkcipher_walk_done(d, w, avail);
135 if (!w->nbytes)
136 break;
137
138 avail = w->nbytes;
139
140 wsrc = w->src.virt.addr;
141 wdst = w->dst.virt.addr;
142 }
143
144 return err;
145 }
146
147 static int encrypt(struct blkcipher_desc *desc, struct scatterlist *dst,
148 struct scatterlist *src, unsigned int nbytes)
149 {
150 struct priv *ctx = crypto_blkcipher_ctx(desc->tfm);
151 struct blkcipher_walk w;
152
153 blkcipher_walk_init(&w, dst, src, nbytes);
154 return crypt(desc, &w, ctx, crypto_cipher_alg(ctx->tweak)->cia_encrypt,
155 crypto_cipher_alg(ctx->child)->cia_encrypt);
156 }
157
158 static int decrypt(struct blkcipher_desc *desc, struct scatterlist *dst,
159 struct scatterlist *src, unsigned int nbytes)
160 {
161 struct priv *ctx = crypto_blkcipher_ctx(desc->tfm);
162 struct blkcipher_walk w;
163
164 blkcipher_walk_init(&w, dst, src, nbytes);
165 return crypt(desc, &w, ctx, crypto_cipher_alg(ctx->tweak)->cia_encrypt,
166 crypto_cipher_alg(ctx->child)->cia_decrypt);
167 }
168
ce00455 @jkivilin crypto: xts: add interface for parallelized cipher implementations
jkivilin authored
169 int xts_crypt(struct blkcipher_desc *desc, struct scatterlist *sdst,
170 struct scatterlist *ssrc, unsigned int nbytes,
171 struct xts_crypt_req *req)
172 {
173 const unsigned int bsize = XTS_BLOCK_SIZE;
174 const unsigned int max_blks = req->tbuflen / bsize;
175 struct blkcipher_walk walk;
176 unsigned int nblocks;
177 be128 *src, *dst, *t;
178 be128 *t_buf = req->tbuf;
179 int err, i;
180
181 BUG_ON(max_blks < 1);
182
183 blkcipher_walk_init(&walk, sdst, ssrc, nbytes);
184
185 err = blkcipher_walk_virt(desc, &walk);
186 nbytes = walk.nbytes;
187 if (!nbytes)
188 return err;
189
190 nblocks = min(nbytes / bsize, max_blks);
191 src = (be128 *)walk.src.virt.addr;
192 dst = (be128 *)walk.dst.virt.addr;
193
194 /* calculate first value of T */
195 req->tweak_fn(req->tweak_ctx, (u8 *)&t_buf[0], walk.iv);
196
197 i = 0;
198 goto first;
199
200 for (;;) {
201 do {
202 for (i = 0; i < nblocks; i++) {
203 gf128mul_x_ble(&t_buf[i], t);
204 first:
205 t = &t_buf[i];
206
207 /* PP <- T xor P */
208 be128_xor(dst + i, t, src + i);
209 }
210
211 /* CC <- E(Key2,PP) */
212 req->crypt_fn(req->crypt_ctx, (u8 *)dst,
213 nblocks * bsize);
214
215 /* C <- T xor CC */
216 for (i = 0; i < nblocks; i++)
217 be128_xor(dst + i, dst + i, &t_buf[i]);
218
219 src += nblocks;
220 dst += nblocks;
221 nbytes -= nblocks * bsize;
222 nblocks = min(nbytes / bsize, max_blks);
223 } while (nblocks > 0);
224
225 *(be128 *)walk.iv = *t;
226
227 err = blkcipher_walk_done(desc, &walk, nbytes);
228 nbytes = walk.nbytes;
229 if (!nbytes)
230 break;
231
232 nblocks = min(nbytes / bsize, max_blks);
233 src = (be128 *)walk.src.virt.addr;
234 dst = (be128 *)walk.dst.virt.addr;
235 }
236
237 return err;
238 }
239 EXPORT_SYMBOL_GPL(xts_crypt);
240
f19f511 [CRYPTO] xts: XTS blockcipher mode implementation without partial blocks
Rik Snel authored
241 static int init_tfm(struct crypto_tfm *tfm)
242 {
243 struct crypto_cipher *cipher;
244 struct crypto_instance *inst = (void *)tfm->__crt_alg;
245 struct crypto_spawn *spawn = crypto_instance_ctx(inst);
246 struct priv *ctx = crypto_tfm_ctx(tfm);
247 u32 *flags = &tfm->crt_flags;
248
249 cipher = crypto_spawn_cipher(spawn);
250 if (IS_ERR(cipher))
251 return PTR_ERR(cipher);
252
f9d2691 @jkivilin crypto: xts - use blocksize constant
jkivilin authored
253 if (crypto_cipher_blocksize(cipher) != XTS_BLOCK_SIZE) {
f19f511 [CRYPTO] xts: XTS blockcipher mode implementation without partial blocks
Rik Snel authored
254 *flags |= CRYPTO_TFM_RES_BAD_BLOCK_LEN;
255 crypto_free_cipher(cipher);
256 return -EINVAL;
257 }
258
259 ctx->child = cipher;
260
261 cipher = crypto_spawn_cipher(spawn);
262 if (IS_ERR(cipher)) {
263 crypto_free_cipher(ctx->child);
264 return PTR_ERR(cipher);
265 }
266
267 /* this check isn't really needed, leave it here just in case */
f9d2691 @jkivilin crypto: xts - use blocksize constant
jkivilin authored
268 if (crypto_cipher_blocksize(cipher) != XTS_BLOCK_SIZE) {
f19f511 [CRYPTO] xts: XTS blockcipher mode implementation without partial blocks
Rik Snel authored
269 crypto_free_cipher(cipher);
270 crypto_free_cipher(ctx->child);
271 *flags |= CRYPTO_TFM_RES_BAD_BLOCK_LEN;
272 return -EINVAL;
273 }
274
275 ctx->tweak = cipher;
276
277 return 0;
278 }
279
280 static void exit_tfm(struct crypto_tfm *tfm)
281 {
282 struct priv *ctx = crypto_tfm_ctx(tfm);
283 crypto_free_cipher(ctx->child);
284 crypto_free_cipher(ctx->tweak);
285 }
286
287 static struct crypto_instance *alloc(struct rtattr **tb)
288 {
289 struct crypto_instance *inst;
290 struct crypto_alg *alg;
291 int err;
292
293 err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_BLKCIPHER);
294 if (err)
295 return ERR_PTR(err);
296
297 alg = crypto_get_attr_alg(tb, CRYPTO_ALG_TYPE_CIPHER,
298 CRYPTO_ALG_TYPE_MASK);
299 if (IS_ERR(alg))
8db0507 @JuliaLawall crypto: Use ERR_CAST
JuliaLawall authored
300 return ERR_CAST(alg);
f19f511 [CRYPTO] xts: XTS blockcipher mode implementation without partial blocks
Rik Snel authored
301
302 inst = crypto_alloc_instance("xts", alg);
303 if (IS_ERR(inst))
304 goto out_put_alg;
305
306 inst->alg.cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER;
307 inst->alg.cra_priority = alg->cra_priority;
308 inst->alg.cra_blocksize = alg->cra_blocksize;
309
310 if (alg->cra_alignmask < 7)
311 inst->alg.cra_alignmask = 7;
312 else
313 inst->alg.cra_alignmask = alg->cra_alignmask;
314
315 inst->alg.cra_type = &crypto_blkcipher_type;
316
317 inst->alg.cra_blkcipher.ivsize = alg->cra_blocksize;
318 inst->alg.cra_blkcipher.min_keysize =
319 2 * alg->cra_cipher.cia_min_keysize;
320 inst->alg.cra_blkcipher.max_keysize =
321 2 * alg->cra_cipher.cia_max_keysize;
322
323 inst->alg.cra_ctxsize = sizeof(struct priv);
324
325 inst->alg.cra_init = init_tfm;
326 inst->alg.cra_exit = exit_tfm;
327
328 inst->alg.cra_blkcipher.setkey = setkey;
329 inst->alg.cra_blkcipher.encrypt = encrypt;
330 inst->alg.cra_blkcipher.decrypt = decrypt;
331
332 out_put_alg:
333 crypto_mod_put(alg);
334 return inst;
335 }
336
337 static void free(struct crypto_instance *inst)
338 {
339 crypto_drop_spawn(crypto_instance_ctx(inst));
340 kfree(inst);
341 }
342
343 static struct crypto_template crypto_tmpl = {
344 .name = "xts",
345 .alloc = alloc,
346 .free = free,
347 .module = THIS_MODULE,
348 };
349
350 static int __init crypto_module_init(void)
351 {
352 return crypto_register_template(&crypto_tmpl);
353 }
354
355 static void __exit crypto_module_exit(void)
356 {
357 crypto_unregister_template(&crypto_tmpl);
358 }
359
360 module_init(crypto_module_init);
361 module_exit(crypto_module_exit);
362
363 MODULE_LICENSE("GPL");
364 MODULE_DESCRIPTION("XTS block cipher mode");
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