1 // SPDX-License-Identifier: GPL-2.0-or-later 1
2 /* XTS: as defined in IEEE1619/D16
3 * http://grouper.ieee.org/groups/1619/em
4 *
5 * Copyright (c) 2007 Rik Snel <rsnel@cube.dyn
6 *
7 * Based on ecb.c
8 * Copyright (c) 2006 Herbert Xu <herbert@gond
9 */
10 #include <crypto/internal/cipher.h>
11 #include <crypto/internal/skcipher.h>
12 #include <crypto/scatterwalk.h>
13 #include <linux/err.h>
14 #include <linux/init.h>
15 #include <linux/kernel.h>
16 #include <linux/module.h>
17 #include <linux/scatterlist.h>
18 #include <linux/slab.h>
19
20 #include <crypto/xts.h>
21 #include <crypto/b128ops.h>
22 #include <crypto/gf128mul.h>
23
24 struct xts_tfm_ctx {
25 struct crypto_skcipher *child;
26 struct crypto_cipher *tweak;
27 };
28
29 struct xts_instance_ctx {
30 struct crypto_skcipher_spawn spawn;
31 struct crypto_cipher_spawn tweak_spawn
32 };
33
34 struct xts_request_ctx {
35 le128 t;
36 struct scatterlist *tail;
37 struct scatterlist sg[2];
38 struct skcipher_request subreq;
39 };
40
41 static int xts_setkey(struct crypto_skcipher *
42 unsigned int keylen)
43 {
44 struct xts_tfm_ctx *ctx = crypto_skcip
45 struct crypto_skcipher *child;
46 struct crypto_cipher *tweak;
47 int err;
48
49 err = xts_verify_key(parent, key, keyl
50 if (err)
51 return err;
52
53 keylen /= 2;
54
55 /* we need two cipher instances: one t
56 * by encrypting the IV (usually the '
57 * one to encrypt and decrypt the data
58
59 /* tweak cipher, uses Key2 i.e. the se
60 tweak = ctx->tweak;
61 crypto_cipher_clear_flags(tweak, CRYPT
62 crypto_cipher_set_flags(tweak, crypto_
63 CRYPTO_
64 err = crypto_cipher_setkey(tweak, key
65 if (err)
66 return err;
67
68 /* data cipher, uses Key1 i.e. the fir
69 child = ctx->child;
70 crypto_skcipher_clear_flags(child, CRY
71 crypto_skcipher_set_flags(child, crypt
72 CRYPT
73 return crypto_skcipher_setkey(child, k
74 }
75
76 /*
77 * We compute the tweak masks twice (both befo
78 * decryption) to avoid having to allocate a t
79 * mutliple calls to the 'ecb(..)' instance, w
80 * just doing the gf128mul_x_ble() calls again
81 */
82 static int xts_xor_tweak(struct skcipher_reque
83 bool enc)
84 {
85 struct xts_request_ctx *rctx = skciphe
86 struct crypto_skcipher *tfm = crypto_s
87 const bool cts = (req->cryptlen % XTS_
88 const int bs = XTS_BLOCK_SIZE;
89 struct skcipher_walk w;
90 le128 t = rctx->t;
91 int err;
92
93 if (second_pass) {
94 req = &rctx->subreq;
95 /* set to our TFM to enforce c
96 skcipher_request_set_tfm(req,
97 }
98 err = skcipher_walk_virt(&w, req, fals
99
100 while (w.nbytes) {
101 unsigned int avail = w.nbytes;
102 le128 *wsrc;
103 le128 *wdst;
104
105 wsrc = w.src.virt.addr;
106 wdst = w.dst.virt.addr;
107
108 do {
109 if (unlikely(cts) &&
110 w.total - w.nbytes
111 if (!enc) {
112 if (se
113
114 gf128m
115 }
116 le128_xor(wdst
117 if (enc && sec
118 gf128m
119 skcipher_walk_
120 return 0;
121 }
122
123 le128_xor(wdst++, &t,
124 gf128mul_x_ble(&t, &t)
125 } while ((avail -= bs) >= bs);
126
127 err = skcipher_walk_done(&w, a
128 }
129
130 return err;
131 }
132
133 static int xts_xor_tweak_pre(struct skcipher_r
134 {
135 return xts_xor_tweak(req, false, enc);
136 }
137
138 static int xts_xor_tweak_post(struct skcipher_
139 {
140 return xts_xor_tweak(req, true, enc);
141 }
142
143 static void xts_cts_done(void *data, int err)
144 {
145 struct skcipher_request *req = data;
146 le128 b;
147
148 if (!err) {
149 struct xts_request_ctx *rctx =
150
151 scatterwalk_map_and_copy(&b, r
152 le128_xor(&b, &rctx->t, &b);
153 scatterwalk_map_and_copy(&b, r
154 }
155
156 skcipher_request_complete(req, err);
157 }
158
159 static int xts_cts_final(struct skcipher_reque
160 int (*crypt)(struct s
161 {
162 const struct xts_tfm_ctx *ctx =
163 crypto_skcipher_ctx(crypto_skc
164 int offset = req->cryptlen & ~(XTS_BLO
165 struct xts_request_ctx *rctx = skciphe
166 struct skcipher_request *subreq = &rct
167 int tail = req->cryptlen % XTS_BLOCK_S
168 le128 b[2];
169 int err;
170
171 rctx->tail = scatterwalk_ffwd(rctx->sg
172 offset -
173
174 scatterwalk_map_and_copy(b, rctx->tail
175 b[1] = b[0];
176 scatterwalk_map_and_copy(b, req->src,
177
178 le128_xor(b, &rctx->t, b);
179
180 scatterwalk_map_and_copy(b, rctx->tail
181
182 skcipher_request_set_tfm(subreq, ctx->
183 skcipher_request_set_callback(subreq,
184 req);
185 skcipher_request_set_crypt(subreq, rct
186 XTS_BLOCK_S
187
188 err = crypt(subreq);
189 if (err)
190 return err;
191
192 scatterwalk_map_and_copy(b, rctx->tail
193 le128_xor(b, &rctx->t, b);
194 scatterwalk_map_and_copy(b, rctx->tail
195
196 return 0;
197 }
198
199 static void xts_encrypt_done(void *data, int e
200 {
201 struct skcipher_request *req = data;
202
203 if (!err) {
204 struct xts_request_ctx *rctx =
205
206 rctx->subreq.base.flags &= CRY
207 err = xts_xor_tweak_post(req,
208
209 if (!err && unlikely(req->cryp
210 err = xts_cts_final(re
211 if (err == -EINPROGRES
212 return;
213 }
214 }
215
216 skcipher_request_complete(req, err);
217 }
218
219 static void xts_decrypt_done(void *data, int e
220 {
221 struct skcipher_request *req = data;
222
223 if (!err) {
224 struct xts_request_ctx *rctx =
225
226 rctx->subreq.base.flags &= CRY
227 err = xts_xor_tweak_post(req,
228
229 if (!err && unlikely(req->cryp
230 err = xts_cts_final(re
231 if (err == -EINPROGRES
232 return;
233 }
234 }
235
236 skcipher_request_complete(req, err);
237 }
238
239 static int xts_init_crypt(struct skcipher_requ
240 crypto_completion_t
241 {
242 const struct xts_tfm_ctx *ctx =
243 crypto_skcipher_ctx(crypto_skc
244 struct xts_request_ctx *rctx = skciphe
245 struct skcipher_request *subreq = &rct
246
247 if (req->cryptlen < XTS_BLOCK_SIZE)
248 return -EINVAL;
249
250 skcipher_request_set_tfm(subreq, ctx->
251 skcipher_request_set_callback(subreq,
252 skcipher_request_set_crypt(subreq, req
253 req->cryptl
254
255 /* calculate first value of T */
256 crypto_cipher_encrypt_one(ctx->tweak,
257
258 return 0;
259 }
260
261 static int xts_encrypt(struct skcipher_request
262 {
263 struct xts_request_ctx *rctx = skciphe
264 struct skcipher_request *subreq = &rct
265 int err;
266
267 err = xts_init_crypt(req, xts_encrypt_
268 xts_xor_tweak_pre(req, true) ?:
269 crypto_skcipher_encrypt(subreq)
270 xts_xor_tweak_post(req, true);
271
272 if (err || likely((req->cryptlen % XTS
273 return err;
274
275 return xts_cts_final(req, crypto_skcip
276 }
277
278 static int xts_decrypt(struct skcipher_request
279 {
280 struct xts_request_ctx *rctx = skciphe
281 struct skcipher_request *subreq = &rct
282 int err;
283
284 err = xts_init_crypt(req, xts_decrypt_
285 xts_xor_tweak_pre(req, false) ?:
286 crypto_skcipher_decrypt(subreq)
287 xts_xor_tweak_post(req, false);
288
289 if (err || likely((req->cryptlen % XTS
290 return err;
291
292 return xts_cts_final(req, crypto_skcip
293 }
294
295 static int xts_init_tfm(struct crypto_skcipher
296 {
297 struct skcipher_instance *inst = skcip
298 struct xts_instance_ctx *ictx = skciph
299 struct xts_tfm_ctx *ctx = crypto_skcip
300 struct crypto_skcipher *child;
301 struct crypto_cipher *tweak;
302
303 child = crypto_spawn_skcipher(&ictx->s
304 if (IS_ERR(child))
305 return PTR_ERR(child);
306
307 ctx->child = child;
308
309 tweak = crypto_spawn_cipher(&ictx->twe
310 if (IS_ERR(tweak)) {
311 crypto_free_skcipher(ctx->chil
312 return PTR_ERR(tweak);
313 }
314
315 ctx->tweak = tweak;
316
317 crypto_skcipher_set_reqsize(tfm, crypt
318 sizeo
319
320 return 0;
321 }
322
323 static void xts_exit_tfm(struct crypto_skciphe
324 {
325 struct xts_tfm_ctx *ctx = crypto_skcip
326
327 crypto_free_skcipher(ctx->child);
328 crypto_free_cipher(ctx->tweak);
329 }
330
331 static void xts_free_instance(struct skcipher_
332 {
333 struct xts_instance_ctx *ictx = skciph
334
335 crypto_drop_skcipher(&ictx->spawn);
336 crypto_drop_cipher(&ictx->tweak_spawn)
337 kfree(inst);
338 }
339
340 static int xts_create(struct crypto_template *
341 {
342 struct skcipher_alg_common *alg;
343 char name[CRYPTO_MAX_ALG_NAME];
344 struct skcipher_instance *inst;
345 struct xts_instance_ctx *ctx;
346 const char *cipher_name;
347 u32 mask;
348 int err;
349
350 err = crypto_check_attr_type(tb, CRYPT
351 if (err)
352 return err;
353
354 cipher_name = crypto_attr_alg_name(tb[
355 if (IS_ERR(cipher_name))
356 return PTR_ERR(cipher_name);
357
358 inst = kzalloc(sizeof(*inst) + sizeof(
359 if (!inst)
360 return -ENOMEM;
361
362 ctx = skcipher_instance_ctx(inst);
363
364 err = crypto_grab_skcipher(&ctx->spawn
365 cipher_name
366 if (err == -ENOENT) {
367 err = -ENAMETOOLONG;
368 if (snprintf(name, CRYPTO_MAX_
369 cipher_name) >= C
370 goto err_free_inst;
371
372 err = crypto_grab_skcipher(&ct
373 skc
374 nam
375 }
376
377 if (err)
378 goto err_free_inst;
379
380 alg = crypto_spawn_skcipher_alg_common
381
382 err = -EINVAL;
383 if (alg->base.cra_blocksize != XTS_BLO
384 goto err_free_inst;
385
386 if (alg->ivsize)
387 goto err_free_inst;
388
389 err = crypto_inst_setname(skcipher_cry
390 &alg->base);
391 if (err)
392 goto err_free_inst;
393
394 err = -EINVAL;
395 cipher_name = alg->base.cra_name;
396
397 /* Alas we screwed up the naming so we
398 * cipher name.
399 */
400 if (!strncmp(cipher_name, "ecb(", 4))
401 int len;
402
403 len = strscpy(name, cipher_nam
404 if (len < 2)
405 goto err_free_inst;
406
407 if (name[len - 1] != ')')
408 goto err_free_inst;
409
410 name[len - 1] = 0;
411
412 if (snprintf(inst->alg.base.cr
413 "xts(%s)", name)
414 err = -ENAMETOOLONG;
415 goto err_free_inst;
416 }
417 } else
418 goto err_free_inst;
419
420 err = crypto_grab_cipher(&ctx->tweak_s
421 skcipher_cryp
422 if (err)
423 goto err_free_inst;
424
425 inst->alg.base.cra_priority = alg->bas
426 inst->alg.base.cra_blocksize = XTS_BLO
427 inst->alg.base.cra_alignmask = alg->ba
428 (__alig
429
430 inst->alg.ivsize = XTS_BLOCK_SIZE;
431 inst->alg.min_keysize = alg->min_keysi
432 inst->alg.max_keysize = alg->max_keysi
433
434 inst->alg.base.cra_ctxsize = sizeof(st
435
436 inst->alg.init = xts_init_tfm;
437 inst->alg.exit = xts_exit_tfm;
438
439 inst->alg.setkey = xts_setkey;
440 inst->alg.encrypt = xts_encrypt;
441 inst->alg.decrypt = xts_decrypt;
442
443 inst->free = xts_free_instance;
444
445 err = skcipher_register_instance(tmpl,
446 if (err) {
447 err_free_inst:
448 xts_free_instance(inst);
449 }
450 return err;
451 }
452
453 static struct crypto_template xts_tmpl = {
454 .name = "xts",
455 .create = xts_create,
456 .module = THIS_MODULE,
457 };
458
459 static int __init xts_module_init(void)
460 {
461 return crypto_register_template(&xts_t
462 }
463
464 static void __exit xts_module_exit(void)
465 {
466 crypto_unregister_template(&xts_tmpl);
467 }
468
469 subsys_initcall(xts_module_init);
470 module_exit(xts_module_exit);
471
472 MODULE_LICENSE("GPL");
473 MODULE_DESCRIPTION("XTS block cipher mode");
474 MODULE_ALIAS_CRYPTO("xts");
475 MODULE_IMPORT_NS(CRYPTO_INTERNAL);
476 MODULE_SOFTDEP("pre: ecb");
477
Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.