blob: 410a2e299085f162b6c1af1b048edd7d3ba53d6c [file] [log] [blame]
Rik Snelf19f5112007-09-19 20:23:13 +08001/* 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 *
Corentin LABBEddbc7362016-08-10 11:29:33 +02008 * Based on ecb.c
Rik Snelf19f5112007-09-19 20:23:13 +08009 * 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 */
Herbert Xuf1c131b2016-11-22 20:08:19 +080016#include <crypto/internal/skcipher.h>
17#include <crypto/scatterwalk.h>
Rik Snelf19f5112007-09-19 20:23:13 +080018#include <linux/err.h>
19#include <linux/init.h>
20#include <linux/kernel.h>
21#include <linux/module.h>
22#include <linux/scatterlist.h>
23#include <linux/slab.h>
24
Jussi Kivilinnace004552011-11-09 11:56:06 +080025#include <crypto/xts.h>
Rik Snelf19f5112007-09-19 20:23:13 +080026#include <crypto/b128ops.h>
27#include <crypto/gf128mul.h>
28
Herbert Xuf1c131b2016-11-22 20:08:19 +080029#define XTS_BUFFER_SIZE 128u
30
Rik Snelf19f5112007-09-19 20:23:13 +080031struct priv {
Herbert Xuf1c131b2016-11-22 20:08:19 +080032 struct crypto_skcipher *child;
Rik Snelf19f5112007-09-19 20:23:13 +080033 struct crypto_cipher *tweak;
34};
35
Herbert Xuf1c131b2016-11-22 20:08:19 +080036struct xts_instance_ctx {
37 struct crypto_skcipher_spawn spawn;
38 char name[CRYPTO_MAX_ALG_NAME];
39};
40
41struct rctx {
42 be128 buf[XTS_BUFFER_SIZE / sizeof(be128)];
43
44 be128 t;
45
46 be128 *ext;
47
48 struct scatterlist srcbuf[2];
49 struct scatterlist dstbuf[2];
50 struct scatterlist *src;
51 struct scatterlist *dst;
52
53 unsigned int left;
54
55 struct skcipher_request subreq;
56};
57
58static int setkey(struct crypto_skcipher *parent, const u8 *key,
Rik Snelf19f5112007-09-19 20:23:13 +080059 unsigned int keylen)
60{
Herbert Xuf1c131b2016-11-22 20:08:19 +080061 struct priv *ctx = crypto_skcipher_ctx(parent);
62 struct crypto_skcipher *child;
63 struct crypto_cipher *tweak;
Rik Snelf19f5112007-09-19 20:23:13 +080064 int err;
65
Herbert Xuf1c131b2016-11-22 20:08:19 +080066 err = xts_verify_key(parent, key, keylen);
Stephan Mueller28856a92016-02-09 15:37:47 +010067 if (err)
68 return err;
Rik Snelf19f5112007-09-19 20:23:13 +080069
Herbert Xuf1c131b2016-11-22 20:08:19 +080070 keylen /= 2;
71
Lucas De Marchi25985ed2011-03-30 22:57:33 -030072 /* we need two cipher instances: one to compute the initial 'tweak'
Rik Snelf19f5112007-09-19 20:23:13 +080073 * by encrypting the IV (usually the 'plain' iv) and the other
74 * one to encrypt and decrypt the data */
75
76 /* tweak cipher, uses Key2 i.e. the second half of *key */
Herbert Xuf1c131b2016-11-22 20:08:19 +080077 tweak = ctx->tweak;
78 crypto_cipher_clear_flags(tweak, CRYPTO_TFM_REQ_MASK);
79 crypto_cipher_set_flags(tweak, crypto_skcipher_get_flags(parent) &
Rik Snelf19f5112007-09-19 20:23:13 +080080 CRYPTO_TFM_REQ_MASK);
Herbert Xuf1c131b2016-11-22 20:08:19 +080081 err = crypto_cipher_setkey(tweak, key + keylen, keylen);
82 crypto_skcipher_set_flags(parent, crypto_cipher_get_flags(tweak) &
83 CRYPTO_TFM_RES_MASK);
Rik Snelf19f5112007-09-19 20:23:13 +080084 if (err)
85 return err;
86
Rik Snelf19f5112007-09-19 20:23:13 +080087 /* data cipher, uses Key1 i.e. the first half of *key */
Herbert Xuf1c131b2016-11-22 20:08:19 +080088 child = ctx->child;
89 crypto_skcipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
90 crypto_skcipher_set_flags(child, crypto_skcipher_get_flags(parent) &
91 CRYPTO_TFM_REQ_MASK);
92 err = crypto_skcipher_setkey(child, key, keylen);
93 crypto_skcipher_set_flags(parent, crypto_skcipher_get_flags(child) &
94 CRYPTO_TFM_RES_MASK);
Rik Snelf19f5112007-09-19 20:23:13 +080095
96 return err;
97}
98
Herbert Xuf1c131b2016-11-22 20:08:19 +080099static int post_crypt(struct skcipher_request *req)
Rik Snelf19f5112007-09-19 20:23:13 +0800100{
Herbert Xuf1c131b2016-11-22 20:08:19 +0800101 struct rctx *rctx = skcipher_request_ctx(req);
102 be128 *buf = rctx->ext ?: rctx->buf;
103 struct skcipher_request *subreq;
104 const int bs = XTS_BLOCK_SIZE;
105 struct skcipher_walk w;
106 struct scatterlist *sg;
107 unsigned offset;
108 int err;
Rik Snelf19f5112007-09-19 20:23:13 +0800109
Herbert Xuf1c131b2016-11-22 20:08:19 +0800110 subreq = &rctx->subreq;
111 err = skcipher_walk_virt(&w, subreq, false);
112
113 while (w.nbytes) {
114 unsigned int avail = w.nbytes;
115 be128 *wdst;
116
117 wdst = w.dst.virt.addr;
118
119 do {
120 be128_xor(wdst, buf++, wdst);
121 wdst++;
122 } while ((avail -= bs) >= bs);
123
124 err = skcipher_walk_done(&w, avail);
125 }
126
127 rctx->left -= subreq->cryptlen;
128
129 if (err || !rctx->left)
130 goto out;
131
132 rctx->dst = rctx->dstbuf;
133
134 scatterwalk_done(&w.out, 0, 1);
135 sg = w.out.sg;
136 offset = w.out.offset;
137
138 if (rctx->dst != sg) {
139 rctx->dst[0] = *sg;
140 sg_unmark_end(rctx->dst);
141 scatterwalk_crypto_chain(rctx->dst, sg_next(sg), 0, 2);
142 }
143 rctx->dst[0].length -= offset - sg->offset;
144 rctx->dst[0].offset = offset;
145
146out:
147 return err;
Rik Snelf19f5112007-09-19 20:23:13 +0800148}
149
Herbert Xuf1c131b2016-11-22 20:08:19 +0800150static int pre_crypt(struct skcipher_request *req)
Rik Snelf19f5112007-09-19 20:23:13 +0800151{
Herbert Xuf1c131b2016-11-22 20:08:19 +0800152 struct rctx *rctx = skcipher_request_ctx(req);
153 be128 *buf = rctx->ext ?: rctx->buf;
154 struct skcipher_request *subreq;
155 const int bs = XTS_BLOCK_SIZE;
156 struct skcipher_walk w;
157 struct scatterlist *sg;
158 unsigned cryptlen;
159 unsigned offset;
160 bool more;
161 int err;
Rik Snelf19f5112007-09-19 20:23:13 +0800162
Herbert Xuf1c131b2016-11-22 20:08:19 +0800163 subreq = &rctx->subreq;
164 cryptlen = subreq->cryptlen;
165
166 more = rctx->left > cryptlen;
167 if (!more)
168 cryptlen = rctx->left;
169
170 skcipher_request_set_crypt(subreq, rctx->src, rctx->dst,
171 cryptlen, NULL);
172
173 err = skcipher_walk_virt(&w, subreq, false);
174
175 while (w.nbytes) {
176 unsigned int avail = w.nbytes;
177 be128 *wsrc;
178 be128 *wdst;
179
180 wsrc = w.src.virt.addr;
181 wdst = w.dst.virt.addr;
182
183 do {
184 *buf++ = rctx->t;
185 be128_xor(wdst++, &rctx->t, wsrc++);
186 gf128mul_x_ble(&rctx->t, &rctx->t);
187 } while ((avail -= bs) >= bs);
188
189 err = skcipher_walk_done(&w, avail);
190 }
191
192 skcipher_request_set_crypt(subreq, rctx->dst, rctx->dst,
193 cryptlen, NULL);
194
195 if (err || !more)
196 goto out;
197
198 rctx->src = rctx->srcbuf;
199
200 scatterwalk_done(&w.in, 0, 1);
201 sg = w.in.sg;
202 offset = w.in.offset;
203
204 if (rctx->src != sg) {
205 rctx->src[0] = *sg;
206 sg_unmark_end(rctx->src);
207 scatterwalk_crypto_chain(rctx->src, sg_next(sg), 0, 2);
208 }
209 rctx->src[0].length -= offset - sg->offset;
210 rctx->src[0].offset = offset;
211
212out:
213 return err;
214}
215
216static int init_crypt(struct skcipher_request *req, crypto_completion_t done)
217{
218 struct priv *ctx = crypto_skcipher_ctx(crypto_skcipher_reqtfm(req));
219 struct rctx *rctx = skcipher_request_ctx(req);
220 struct skcipher_request *subreq;
221 gfp_t gfp;
222
223 subreq = &rctx->subreq;
224 skcipher_request_set_tfm(subreq, ctx->child);
225 skcipher_request_set_callback(subreq, req->base.flags, done, req);
226
227 gfp = req->base.flags & CRYPTO_TFM_REQ_MAY_SLEEP ? GFP_KERNEL :
228 GFP_ATOMIC;
229 rctx->ext = NULL;
230
231 subreq->cryptlen = XTS_BUFFER_SIZE;
232 if (req->cryptlen > XTS_BUFFER_SIZE) {
233 subreq->cryptlen = min(req->cryptlen, (unsigned)PAGE_SIZE);
234 rctx->ext = kmalloc(subreq->cryptlen, gfp);
235 }
236
237 rctx->src = req->src;
238 rctx->dst = req->dst;
239 rctx->left = req->cryptlen;
240
241 /* calculate first value of T */
242 crypto_cipher_encrypt_one(ctx->tweak, (u8 *)&rctx->t, req->iv);
243
244 return 0;
245}
246
247static void exit_crypt(struct skcipher_request *req)
248{
249 struct rctx *rctx = skcipher_request_ctx(req);
250
251 rctx->left = 0;
252
253 if (rctx->ext)
254 kzfree(rctx->ext);
255}
256
257static int do_encrypt(struct skcipher_request *req, int err)
258{
259 struct rctx *rctx = skcipher_request_ctx(req);
260 struct skcipher_request *subreq;
261
262 subreq = &rctx->subreq;
263
264 while (!err && rctx->left) {
265 err = pre_crypt(req) ?:
266 crypto_skcipher_encrypt(subreq) ?:
267 post_crypt(req);
268
269 if (err == -EINPROGRESS ||
270 (err == -EBUSY &&
271 req->base.flags & CRYPTO_TFM_REQ_MAY_BACKLOG))
272 return err;
273 }
274
275 exit_crypt(req);
276 return err;
277}
278
279static void encrypt_done(struct crypto_async_request *areq, int err)
280{
281 struct skcipher_request *req = areq->data;
282 struct skcipher_request *subreq;
283 struct rctx *rctx;
284
285 rctx = skcipher_request_ctx(req);
286 subreq = &rctx->subreq;
287 subreq->base.flags &= CRYPTO_TFM_REQ_MAY_BACKLOG;
288
289 err = do_encrypt(req, err ?: post_crypt(req));
290 if (rctx->left)
291 return;
292
293 skcipher_request_complete(req, err);
294}
295
296static int encrypt(struct skcipher_request *req)
297{
298 return do_encrypt(req, init_crypt(req, encrypt_done));
299}
300
301static int do_decrypt(struct skcipher_request *req, int err)
302{
303 struct rctx *rctx = skcipher_request_ctx(req);
304 struct skcipher_request *subreq;
305
306 subreq = &rctx->subreq;
307
308 while (!err && rctx->left) {
309 err = pre_crypt(req) ?:
310 crypto_skcipher_decrypt(subreq) ?:
311 post_crypt(req);
312
313 if (err == -EINPROGRESS ||
314 (err == -EBUSY &&
315 req->base.flags & CRYPTO_TFM_REQ_MAY_BACKLOG))
316 return err;
317 }
318
319 exit_crypt(req);
320 return err;
321}
322
323static void decrypt_done(struct crypto_async_request *areq, int err)
324{
325 struct skcipher_request *req = areq->data;
326 struct skcipher_request *subreq;
327 struct rctx *rctx;
328
329 rctx = skcipher_request_ctx(req);
330 subreq = &rctx->subreq;
331 subreq->base.flags &= CRYPTO_TFM_REQ_MAY_BACKLOG;
332
333 err = do_decrypt(req, err ?: post_crypt(req));
334 if (rctx->left)
335 return;
336
337 skcipher_request_complete(req, err);
338}
339
340static int decrypt(struct skcipher_request *req)
341{
342 return do_decrypt(req, init_crypt(req, decrypt_done));
Rik Snelf19f5112007-09-19 20:23:13 +0800343}
344
Jussi Kivilinnace004552011-11-09 11:56:06 +0800345int xts_crypt(struct blkcipher_desc *desc, struct scatterlist *sdst,
346 struct scatterlist *ssrc, unsigned int nbytes,
347 struct xts_crypt_req *req)
348{
349 const unsigned int bsize = XTS_BLOCK_SIZE;
350 const unsigned int max_blks = req->tbuflen / bsize;
351 struct blkcipher_walk walk;
352 unsigned int nblocks;
353 be128 *src, *dst, *t;
354 be128 *t_buf = req->tbuf;
355 int err, i;
356
357 BUG_ON(max_blks < 1);
358
359 blkcipher_walk_init(&walk, sdst, ssrc, nbytes);
360
361 err = blkcipher_walk_virt(desc, &walk);
362 nbytes = walk.nbytes;
363 if (!nbytes)
364 return err;
365
366 nblocks = min(nbytes / bsize, max_blks);
367 src = (be128 *)walk.src.virt.addr;
368 dst = (be128 *)walk.dst.virt.addr;
369
370 /* calculate first value of T */
371 req->tweak_fn(req->tweak_ctx, (u8 *)&t_buf[0], walk.iv);
372
373 i = 0;
374 goto first;
375
376 for (;;) {
377 do {
378 for (i = 0; i < nblocks; i++) {
379 gf128mul_x_ble(&t_buf[i], t);
380first:
381 t = &t_buf[i];
382
383 /* PP <- T xor P */
384 be128_xor(dst + i, t, src + i);
385 }
386
387 /* CC <- E(Key2,PP) */
388 req->crypt_fn(req->crypt_ctx, (u8 *)dst,
389 nblocks * bsize);
390
391 /* C <- T xor CC */
392 for (i = 0; i < nblocks; i++)
393 be128_xor(dst + i, dst + i, &t_buf[i]);
394
395 src += nblocks;
396 dst += nblocks;
397 nbytes -= nblocks * bsize;
398 nblocks = min(nbytes / bsize, max_blks);
399 } while (nblocks > 0);
400
401 *(be128 *)walk.iv = *t;
402
403 err = blkcipher_walk_done(desc, &walk, nbytes);
404 nbytes = walk.nbytes;
405 if (!nbytes)
406 break;
407
408 nblocks = min(nbytes / bsize, max_blks);
409 src = (be128 *)walk.src.virt.addr;
410 dst = (be128 *)walk.dst.virt.addr;
411 }
412
413 return err;
414}
415EXPORT_SYMBOL_GPL(xts_crypt);
416
Herbert Xuf1c131b2016-11-22 20:08:19 +0800417static int init_tfm(struct crypto_skcipher *tfm)
Rik Snelf19f5112007-09-19 20:23:13 +0800418{
Herbert Xuf1c131b2016-11-22 20:08:19 +0800419 struct skcipher_instance *inst = skcipher_alg_instance(tfm);
420 struct xts_instance_ctx *ictx = skcipher_instance_ctx(inst);
421 struct priv *ctx = crypto_skcipher_ctx(tfm);
422 struct crypto_skcipher *child;
423 struct crypto_cipher *tweak;
Rik Snelf19f5112007-09-19 20:23:13 +0800424
Herbert Xuf1c131b2016-11-22 20:08:19 +0800425 child = crypto_spawn_skcipher(&ictx->spawn);
426 if (IS_ERR(child))
427 return PTR_ERR(child);
Rik Snelf19f5112007-09-19 20:23:13 +0800428
Herbert Xuf1c131b2016-11-22 20:08:19 +0800429 ctx->child = child;
430
431 tweak = crypto_alloc_cipher(ictx->name, 0, 0);
432 if (IS_ERR(tweak)) {
433 crypto_free_skcipher(ctx->child);
434 return PTR_ERR(tweak);
Rik Snelf19f5112007-09-19 20:23:13 +0800435 }
436
Herbert Xuf1c131b2016-11-22 20:08:19 +0800437 ctx->tweak = tweak;
Rik Snelf19f5112007-09-19 20:23:13 +0800438
Herbert Xuf1c131b2016-11-22 20:08:19 +0800439 crypto_skcipher_set_reqsize(tfm, crypto_skcipher_reqsize(child) +
440 sizeof(struct rctx));
Rik Snelf19f5112007-09-19 20:23:13 +0800441
442 return 0;
443}
444
Herbert Xuf1c131b2016-11-22 20:08:19 +0800445static void exit_tfm(struct crypto_skcipher *tfm)
Rik Snelf19f5112007-09-19 20:23:13 +0800446{
Herbert Xuf1c131b2016-11-22 20:08:19 +0800447 struct priv *ctx = crypto_skcipher_ctx(tfm);
448
449 crypto_free_skcipher(ctx->child);
Rik Snelf19f5112007-09-19 20:23:13 +0800450 crypto_free_cipher(ctx->tweak);
451}
452
Herbert Xuf1c131b2016-11-22 20:08:19 +0800453static void free(struct skcipher_instance *inst)
Rik Snelf19f5112007-09-19 20:23:13 +0800454{
Herbert Xuf1c131b2016-11-22 20:08:19 +0800455 crypto_drop_skcipher(skcipher_instance_ctx(inst));
456 kfree(inst);
Rik Snelf19f5112007-09-19 20:23:13 +0800457}
458
Herbert Xuf1c131b2016-11-22 20:08:19 +0800459static int create(struct crypto_template *tmpl, struct rtattr **tb)
Rik Snelf19f5112007-09-19 20:23:13 +0800460{
Herbert Xuf1c131b2016-11-22 20:08:19 +0800461 struct skcipher_instance *inst;
462 struct crypto_attr_type *algt;
463 struct xts_instance_ctx *ctx;
464 struct skcipher_alg *alg;
465 const char *cipher_name;
466 int err;
467
468 algt = crypto_get_attr_type(tb);
469 if (IS_ERR(algt))
470 return PTR_ERR(algt);
471
472 if ((algt->type ^ CRYPTO_ALG_TYPE_SKCIPHER) & algt->mask)
473 return -EINVAL;
474
475 cipher_name = crypto_attr_alg_name(tb[1]);
476 if (IS_ERR(cipher_name))
477 return PTR_ERR(cipher_name);
478
479 inst = kzalloc(sizeof(*inst) + sizeof(*ctx), GFP_KERNEL);
480 if (!inst)
481 return -ENOMEM;
482
483 ctx = skcipher_instance_ctx(inst);
484
485 crypto_set_skcipher_spawn(&ctx->spawn, skcipher_crypto_instance(inst));
486 err = crypto_grab_skcipher(&ctx->spawn, cipher_name, 0,
487 crypto_requires_sync(algt->type,
488 algt->mask));
489 if (err == -ENOENT) {
490 err = -ENAMETOOLONG;
491 if (snprintf(ctx->name, CRYPTO_MAX_ALG_NAME, "ecb(%s)",
492 cipher_name) >= CRYPTO_MAX_ALG_NAME)
493 goto err_free_inst;
494
495 err = crypto_grab_skcipher(&ctx->spawn, ctx->name, 0,
496 crypto_requires_sync(algt->type,
497 algt->mask));
498 }
499
500 if (err)
501 goto err_free_inst;
502
503 alg = crypto_skcipher_spawn_alg(&ctx->spawn);
504
505 err = -EINVAL;
506 if (alg->base.cra_blocksize != XTS_BLOCK_SIZE)
507 goto err_drop_spawn;
508
509 if (crypto_skcipher_alg_ivsize(alg))
510 goto err_drop_spawn;
511
512 err = crypto_inst_setname(skcipher_crypto_instance(inst), "xts",
513 &alg->base);
514 if (err)
515 goto err_drop_spawn;
516
517 err = -EINVAL;
518 cipher_name = alg->base.cra_name;
519
520 /* Alas we screwed up the naming so we have to mangle the
521 * cipher name.
522 */
523 if (!strncmp(cipher_name, "ecb(", 4)) {
524 unsigned len;
525
526 len = strlcpy(ctx->name, cipher_name + 4, sizeof(ctx->name));
527 if (len < 2 || len >= sizeof(ctx->name))
528 goto err_drop_spawn;
529
530 if (ctx->name[len - 1] != ')')
531 goto err_drop_spawn;
532
533 ctx->name[len - 1] = 0;
534
535 if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME,
536 "xts(%s)", ctx->name) >= CRYPTO_MAX_ALG_NAME)
537 return -ENAMETOOLONG;
538 } else
539 goto err_drop_spawn;
540
541 inst->alg.base.cra_flags = alg->base.cra_flags & CRYPTO_ALG_ASYNC;
542 inst->alg.base.cra_priority = alg->base.cra_priority;
543 inst->alg.base.cra_blocksize = XTS_BLOCK_SIZE;
544 inst->alg.base.cra_alignmask = alg->base.cra_alignmask |
545 (__alignof__(u64) - 1);
546
547 inst->alg.ivsize = XTS_BLOCK_SIZE;
548 inst->alg.min_keysize = crypto_skcipher_alg_min_keysize(alg) * 2;
549 inst->alg.max_keysize = crypto_skcipher_alg_max_keysize(alg) * 2;
550
551 inst->alg.base.cra_ctxsize = sizeof(struct priv);
552
553 inst->alg.init = init_tfm;
554 inst->alg.exit = exit_tfm;
555
556 inst->alg.setkey = setkey;
557 inst->alg.encrypt = encrypt;
558 inst->alg.decrypt = decrypt;
559
560 inst->free = free;
561
562 err = skcipher_register_instance(tmpl, inst);
563 if (err)
564 goto err_drop_spawn;
565
566out:
567 return err;
568
569err_drop_spawn:
570 crypto_drop_skcipher(&ctx->spawn);
571err_free_inst:
Rik Snelf19f5112007-09-19 20:23:13 +0800572 kfree(inst);
Herbert Xuf1c131b2016-11-22 20:08:19 +0800573 goto out;
Rik Snelf19f5112007-09-19 20:23:13 +0800574}
575
576static struct crypto_template crypto_tmpl = {
577 .name = "xts",
Herbert Xuf1c131b2016-11-22 20:08:19 +0800578 .create = create,
Rik Snelf19f5112007-09-19 20:23:13 +0800579 .module = THIS_MODULE,
580};
581
582static int __init crypto_module_init(void)
583{
584 return crypto_register_template(&crypto_tmpl);
585}
586
587static void __exit crypto_module_exit(void)
588{
589 crypto_unregister_template(&crypto_tmpl);
590}
591
592module_init(crypto_module_init);
593module_exit(crypto_module_exit);
594
595MODULE_LICENSE("GPL");
596MODULE_DESCRIPTION("XTS block cipher mode");
Kees Cook4943ba12014-11-24 16:32:38 -0800597MODULE_ALIAS_CRYPTO("xts");