1 /* LRW: as defined by Cyril Guyot in
2 * http://grouper.ieee.org/groups/1619/email/pdf00017.pdf
3 *
4 * Copyright (c) 2006 Rik Snel <rsnel@cube.dyndns.org>
5 *
6 * Based on ecb.c
7 * Copyright (c) 2006 Herbert Xu <herbert@gondor.apana.org.au>
8 *
9 * This program is free software; you can redistribute it and/or modify it
10 * under the terms of the GNU General Public License as published by the Free
11 * Software Foundation; either version 2 of the License, or (at your option)
12 * any later version.
13 */
14 /* This implementation is checked against the test vectors in the above
15 * document and by a test vector provided by Ken Buchanan at
16 * http://www.mail-archive.com/stds-p1619@listserv.ieee.org/msg00173.html
17 *
18 * The test vectors are included in the testing module tcrypt.[ch] */
19
20 #include <crypto/internal/skcipher.h>
21 #include <crypto/scatterwalk.h>
22 #include <linux/err.h>
23 #include <linux/init.h>
24 #include <linux/kernel.h>
25 #include <linux/module.h>
26 #include <linux/scatterlist.h>
27 #include <linux/slab.h>
28
29 #include <crypto/b128ops.h>
30 #include <crypto/gf128mul.h>
31 #include <crypto/lrw.h>
32
33 #define LRW_BUFFER_SIZE 128u
34
35 struct priv {
36 struct crypto_skcipher *child;
37 struct lrw_table_ctx table;
38 };
39
40 struct rctx {
41 be128 buf[LRW_BUFFER_SIZE / sizeof(be128)];
42
43 be128 t;
44
45 be128 *ext;
46
47 struct scatterlist srcbuf[2];
48 struct scatterlist dstbuf[2];
49 struct scatterlist *src;
50 struct scatterlist *dst;
51
52 unsigned int left;
53
54 struct skcipher_request subreq;
55 };
56
setbit128_bbe(void * b,int bit)57 static inline void setbit128_bbe(void *b, int bit)
58 {
59 __set_bit(bit ^ (0x80 -
60 #ifdef __BIG_ENDIAN
61 BITS_PER_LONG
62 #else
63 BITS_PER_BYTE
64 #endif
65 ), b);
66 }
67
lrw_init_table(struct lrw_table_ctx * ctx,const u8 * tweak)68 int lrw_init_table(struct lrw_table_ctx *ctx, const u8 *tweak)
69 {
70 be128 tmp = { 0 };
71 int i;
72
73 if (ctx->table)
74 gf128mul_free_64k(ctx->table);
75
76 /* initialize multiplication table for Key2 */
77 ctx->table = gf128mul_init_64k_bbe((be128 *)tweak);
78 if (!ctx->table)
79 return -ENOMEM;
80
81 /* initialize optimization table */
82 for (i = 0; i < 128; i++) {
83 setbit128_bbe(&tmp, i);
84 ctx->mulinc[i] = tmp;
85 gf128mul_64k_bbe(&ctx->mulinc[i], ctx->table);
86 }
87
88 return 0;
89 }
90 EXPORT_SYMBOL_GPL(lrw_init_table);
91
lrw_free_table(struct lrw_table_ctx * ctx)92 void lrw_free_table(struct lrw_table_ctx *ctx)
93 {
94 if (ctx->table)
95 gf128mul_free_64k(ctx->table);
96 }
97 EXPORT_SYMBOL_GPL(lrw_free_table);
98
setkey(struct crypto_skcipher * parent,const u8 * key,unsigned int keylen)99 static int setkey(struct crypto_skcipher *parent, const u8 *key,
100 unsigned int keylen)
101 {
102 struct priv *ctx = crypto_skcipher_ctx(parent);
103 struct crypto_skcipher *child = ctx->child;
104 int err, bsize = LRW_BLOCK_SIZE;
105 const u8 *tweak = key + keylen - bsize;
106
107 crypto_skcipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
108 crypto_skcipher_set_flags(child, crypto_skcipher_get_flags(parent) &
109 CRYPTO_TFM_REQ_MASK);
110 err = crypto_skcipher_setkey(child, key, keylen - bsize);
111 crypto_skcipher_set_flags(parent, crypto_skcipher_get_flags(child) &
112 CRYPTO_TFM_RES_MASK);
113 if (err)
114 return err;
115
116 return lrw_init_table(&ctx->table, tweak);
117 }
118
inc(be128 * iv)119 static inline void inc(be128 *iv)
120 {
121 be64_add_cpu(&iv->b, 1);
122 if (!iv->b)
123 be64_add_cpu(&iv->a, 1);
124 }
125
126 /* this returns the number of consequative 1 bits starting
127 * from the right, get_index128(00 00 00 00 00 00 ... 00 00 10 FB) = 2 */
get_index128(be128 * block)128 static inline int get_index128(be128 *block)
129 {
130 int x;
131 __be32 *p = (__be32 *) block;
132
133 for (p += 3, x = 0; x < 128; p--, x += 32) {
134 u32 val = be32_to_cpup(p);
135
136 if (!~val)
137 continue;
138
139 return x + ffz(val);
140 }
141
142 /*
143 * If we get here, then x == 128 and we are incrementing the counter
144 * from all ones to all zeros. This means we must return index 127, i.e.
145 * the one corresponding to key2*{ 1,...,1 }.
146 */
147 return 127;
148 }
149
post_crypt(struct skcipher_request * req)150 static int post_crypt(struct skcipher_request *req)
151 {
152 struct rctx *rctx = skcipher_request_ctx(req);
153 be128 *buf = rctx->ext ?: rctx->buf;
154 struct skcipher_request *subreq;
155 const int bs = LRW_BLOCK_SIZE;
156 struct skcipher_walk w;
157 struct scatterlist *sg;
158 unsigned offset;
159 int err;
160
161 subreq = &rctx->subreq;
162 err = skcipher_walk_virt(&w, subreq, false);
163
164 while (w.nbytes) {
165 unsigned int avail = w.nbytes;
166 be128 *wdst;
167
168 wdst = w.dst.virt.addr;
169
170 do {
171 be128_xor(wdst, buf++, wdst);
172 wdst++;
173 } while ((avail -= bs) >= bs);
174
175 err = skcipher_walk_done(&w, avail);
176 }
177
178 rctx->left -= subreq->cryptlen;
179
180 if (err || !rctx->left)
181 goto out;
182
183 rctx->dst = rctx->dstbuf;
184
185 scatterwalk_done(&w.out, 0, 1);
186 sg = w.out.sg;
187 offset = w.out.offset;
188
189 if (rctx->dst != sg) {
190 rctx->dst[0] = *sg;
191 sg_unmark_end(rctx->dst);
192 scatterwalk_crypto_chain(rctx->dst, sg_next(sg), 0, 2);
193 }
194 rctx->dst[0].length -= offset - sg->offset;
195 rctx->dst[0].offset = offset;
196
197 out:
198 return err;
199 }
200
pre_crypt(struct skcipher_request * req)201 static int pre_crypt(struct skcipher_request *req)
202 {
203 struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
204 struct rctx *rctx = skcipher_request_ctx(req);
205 struct priv *ctx = crypto_skcipher_ctx(tfm);
206 be128 *buf = rctx->ext ?: rctx->buf;
207 struct skcipher_request *subreq;
208 const int bs = LRW_BLOCK_SIZE;
209 struct skcipher_walk w;
210 struct scatterlist *sg;
211 unsigned cryptlen;
212 unsigned offset;
213 be128 *iv;
214 bool more;
215 int err;
216
217 subreq = &rctx->subreq;
218 skcipher_request_set_tfm(subreq, tfm);
219
220 cryptlen = subreq->cryptlen;
221 more = rctx->left > cryptlen;
222 if (!more)
223 cryptlen = rctx->left;
224
225 skcipher_request_set_crypt(subreq, rctx->src, rctx->dst,
226 cryptlen, req->iv);
227
228 err = skcipher_walk_virt(&w, subreq, false);
229 iv = w.iv;
230
231 while (w.nbytes) {
232 unsigned int avail = w.nbytes;
233 be128 *wsrc;
234 be128 *wdst;
235
236 wsrc = w.src.virt.addr;
237 wdst = w.dst.virt.addr;
238
239 do {
240 *buf++ = rctx->t;
241 be128_xor(wdst++, &rctx->t, wsrc++);
242
243 /* T <- I*Key2, using the optimization
244 * discussed in the specification */
245 be128_xor(&rctx->t, &rctx->t,
246 &ctx->table.mulinc[get_index128(iv)]);
247 inc(iv);
248 } while ((avail -= bs) >= bs);
249
250 err = skcipher_walk_done(&w, avail);
251 }
252
253 skcipher_request_set_tfm(subreq, ctx->child);
254 skcipher_request_set_crypt(subreq, rctx->dst, rctx->dst,
255 cryptlen, NULL);
256
257 if (err || !more)
258 goto out;
259
260 rctx->src = rctx->srcbuf;
261
262 scatterwalk_done(&w.in, 0, 1);
263 sg = w.in.sg;
264 offset = w.in.offset;
265
266 if (rctx->src != sg) {
267 rctx->src[0] = *sg;
268 sg_unmark_end(rctx->src);
269 scatterwalk_crypto_chain(rctx->src, sg_next(sg), 0, 2);
270 }
271 rctx->src[0].length -= offset - sg->offset;
272 rctx->src[0].offset = offset;
273
274 out:
275 return err;
276 }
277
init_crypt(struct skcipher_request * req,crypto_completion_t done)278 static int init_crypt(struct skcipher_request *req, crypto_completion_t done)
279 {
280 struct priv *ctx = crypto_skcipher_ctx(crypto_skcipher_reqtfm(req));
281 struct rctx *rctx = skcipher_request_ctx(req);
282 struct skcipher_request *subreq;
283 gfp_t gfp;
284
285 subreq = &rctx->subreq;
286 skcipher_request_set_callback(subreq, req->base.flags, done, req);
287
288 gfp = req->base.flags & CRYPTO_TFM_REQ_MAY_SLEEP ? GFP_KERNEL :
289 GFP_ATOMIC;
290 rctx->ext = NULL;
291
292 subreq->cryptlen = LRW_BUFFER_SIZE;
293 if (req->cryptlen > LRW_BUFFER_SIZE) {
294 unsigned int n = min(req->cryptlen, (unsigned int)PAGE_SIZE);
295
296 rctx->ext = kmalloc(n, gfp);
297 if (rctx->ext)
298 subreq->cryptlen = n;
299 }
300
301 rctx->src = req->src;
302 rctx->dst = req->dst;
303 rctx->left = req->cryptlen;
304
305 /* calculate first value of T */
306 memcpy(&rctx->t, req->iv, sizeof(rctx->t));
307
308 /* T <- I*Key2 */
309 gf128mul_64k_bbe(&rctx->t, ctx->table.table);
310
311 return 0;
312 }
313
exit_crypt(struct skcipher_request * req)314 static void exit_crypt(struct skcipher_request *req)
315 {
316 struct rctx *rctx = skcipher_request_ctx(req);
317
318 rctx->left = 0;
319
320 if (rctx->ext)
321 kzfree(rctx->ext);
322 }
323
do_encrypt(struct skcipher_request * req,int err)324 static int do_encrypt(struct skcipher_request *req, int err)
325 {
326 struct rctx *rctx = skcipher_request_ctx(req);
327 struct skcipher_request *subreq;
328
329 subreq = &rctx->subreq;
330
331 while (!err && rctx->left) {
332 err = pre_crypt(req) ?:
333 crypto_skcipher_encrypt(subreq) ?:
334 post_crypt(req);
335
336 if (err == -EINPROGRESS ||
337 (err == -EBUSY &&
338 req->base.flags & CRYPTO_TFM_REQ_MAY_BACKLOG))
339 return err;
340 }
341
342 exit_crypt(req);
343 return err;
344 }
345
encrypt_done(struct crypto_async_request * areq,int err)346 static void encrypt_done(struct crypto_async_request *areq, int err)
347 {
348 struct skcipher_request *req = areq->data;
349 struct skcipher_request *subreq;
350 struct rctx *rctx;
351
352 rctx = skcipher_request_ctx(req);
353
354 if (err == -EINPROGRESS) {
355 if (rctx->left != req->cryptlen)
356 return;
357 goto out;
358 }
359
360 subreq = &rctx->subreq;
361 subreq->base.flags &= CRYPTO_TFM_REQ_MAY_BACKLOG;
362
363 err = do_encrypt(req, err ?: post_crypt(req));
364 if (rctx->left)
365 return;
366
367 out:
368 skcipher_request_complete(req, err);
369 }
370
encrypt(struct skcipher_request * req)371 static int encrypt(struct skcipher_request *req)
372 {
373 return do_encrypt(req, init_crypt(req, encrypt_done));
374 }
375
do_decrypt(struct skcipher_request * req,int err)376 static int do_decrypt(struct skcipher_request *req, int err)
377 {
378 struct rctx *rctx = skcipher_request_ctx(req);
379 struct skcipher_request *subreq;
380
381 subreq = &rctx->subreq;
382
383 while (!err && rctx->left) {
384 err = pre_crypt(req) ?:
385 crypto_skcipher_decrypt(subreq) ?:
386 post_crypt(req);
387
388 if (err == -EINPROGRESS ||
389 (err == -EBUSY &&
390 req->base.flags & CRYPTO_TFM_REQ_MAY_BACKLOG))
391 return err;
392 }
393
394 exit_crypt(req);
395 return err;
396 }
397
decrypt_done(struct crypto_async_request * areq,int err)398 static void decrypt_done(struct crypto_async_request *areq, int err)
399 {
400 struct skcipher_request *req = areq->data;
401 struct skcipher_request *subreq;
402 struct rctx *rctx;
403
404 rctx = skcipher_request_ctx(req);
405
406 if (err == -EINPROGRESS) {
407 if (rctx->left != req->cryptlen)
408 return;
409 goto out;
410 }
411
412 subreq = &rctx->subreq;
413 subreq->base.flags &= CRYPTO_TFM_REQ_MAY_BACKLOG;
414
415 err = do_decrypt(req, err ?: post_crypt(req));
416 if (rctx->left)
417 return;
418
419 out:
420 skcipher_request_complete(req, err);
421 }
422
decrypt(struct skcipher_request * req)423 static int decrypt(struct skcipher_request *req)
424 {
425 return do_decrypt(req, init_crypt(req, decrypt_done));
426 }
427
lrw_crypt(struct blkcipher_desc * desc,struct scatterlist * sdst,struct scatterlist * ssrc,unsigned int nbytes,struct lrw_crypt_req * req)428 int lrw_crypt(struct blkcipher_desc *desc, struct scatterlist *sdst,
429 struct scatterlist *ssrc, unsigned int nbytes,
430 struct lrw_crypt_req *req)
431 {
432 const unsigned int bsize = LRW_BLOCK_SIZE;
433 const unsigned int max_blks = req->tbuflen / bsize;
434 struct lrw_table_ctx *ctx = req->table_ctx;
435 struct blkcipher_walk walk;
436 unsigned int nblocks;
437 be128 *iv, *src, *dst, *t;
438 be128 *t_buf = req->tbuf;
439 int err, i;
440
441 BUG_ON(max_blks < 1);
442
443 blkcipher_walk_init(&walk, sdst, ssrc, nbytes);
444
445 err = blkcipher_walk_virt(desc, &walk);
446 nbytes = walk.nbytes;
447 if (!nbytes)
448 return err;
449
450 nblocks = min(walk.nbytes / bsize, max_blks);
451 src = (be128 *)walk.src.virt.addr;
452 dst = (be128 *)walk.dst.virt.addr;
453
454 /* calculate first value of T */
455 iv = (be128 *)walk.iv;
456 t_buf[0] = *iv;
457
458 /* T <- I*Key2 */
459 gf128mul_64k_bbe(&t_buf[0], ctx->table);
460
461 i = 0;
462 goto first;
463
464 for (;;) {
465 do {
466 for (i = 0; i < nblocks; i++) {
467 /* T <- I*Key2, using the optimization
468 * discussed in the specification */
469 be128_xor(&t_buf[i], t,
470 &ctx->mulinc[get_index128(iv)]);
471 inc(iv);
472 first:
473 t = &t_buf[i];
474
475 /* PP <- T xor P */
476 be128_xor(dst + i, t, src + i);
477 }
478
479 /* CC <- E(Key2,PP) */
480 req->crypt_fn(req->crypt_ctx, (u8 *)dst,
481 nblocks * bsize);
482
483 /* C <- T xor CC */
484 for (i = 0; i < nblocks; i++)
485 be128_xor(dst + i, dst + i, &t_buf[i]);
486
487 src += nblocks;
488 dst += nblocks;
489 nbytes -= nblocks * bsize;
490 nblocks = min(nbytes / bsize, max_blks);
491 } while (nblocks > 0);
492
493 err = blkcipher_walk_done(desc, &walk, nbytes);
494 nbytes = walk.nbytes;
495 if (!nbytes)
496 break;
497
498 nblocks = min(nbytes / bsize, max_blks);
499 src = (be128 *)walk.src.virt.addr;
500 dst = (be128 *)walk.dst.virt.addr;
501 }
502
503 return err;
504 }
505 EXPORT_SYMBOL_GPL(lrw_crypt);
506
init_tfm(struct crypto_skcipher * tfm)507 static int init_tfm(struct crypto_skcipher *tfm)
508 {
509 struct skcipher_instance *inst = skcipher_alg_instance(tfm);
510 struct crypto_skcipher_spawn *spawn = skcipher_instance_ctx(inst);
511 struct priv *ctx = crypto_skcipher_ctx(tfm);
512 struct crypto_skcipher *cipher;
513
514 cipher = crypto_spawn_skcipher(spawn);
515 if (IS_ERR(cipher))
516 return PTR_ERR(cipher);
517
518 ctx->child = cipher;
519
520 crypto_skcipher_set_reqsize(tfm, crypto_skcipher_reqsize(cipher) +
521 sizeof(struct rctx));
522
523 return 0;
524 }
525
exit_tfm(struct crypto_skcipher * tfm)526 static void exit_tfm(struct crypto_skcipher *tfm)
527 {
528 struct priv *ctx = crypto_skcipher_ctx(tfm);
529
530 lrw_free_table(&ctx->table);
531 crypto_free_skcipher(ctx->child);
532 }
533
free(struct skcipher_instance * inst)534 static void free(struct skcipher_instance *inst)
535 {
536 crypto_drop_skcipher(skcipher_instance_ctx(inst));
537 kfree(inst);
538 }
539
create(struct crypto_template * tmpl,struct rtattr ** tb)540 static int create(struct crypto_template *tmpl, struct rtattr **tb)
541 {
542 struct crypto_skcipher_spawn *spawn;
543 struct skcipher_instance *inst;
544 struct crypto_attr_type *algt;
545 struct skcipher_alg *alg;
546 const char *cipher_name;
547 char ecb_name[CRYPTO_MAX_ALG_NAME];
548 int err;
549
550 algt = crypto_get_attr_type(tb);
551 if (IS_ERR(algt))
552 return PTR_ERR(algt);
553
554 if ((algt->type ^ CRYPTO_ALG_TYPE_SKCIPHER) & algt->mask)
555 return -EINVAL;
556
557 cipher_name = crypto_attr_alg_name(tb[1]);
558 if (IS_ERR(cipher_name))
559 return PTR_ERR(cipher_name);
560
561 inst = kzalloc(sizeof(*inst) + sizeof(*spawn), GFP_KERNEL);
562 if (!inst)
563 return -ENOMEM;
564
565 spawn = skcipher_instance_ctx(inst);
566
567 crypto_set_skcipher_spawn(spawn, skcipher_crypto_instance(inst));
568 err = crypto_grab_skcipher(spawn, cipher_name, 0,
569 crypto_requires_sync(algt->type,
570 algt->mask));
571 if (err == -ENOENT) {
572 err = -ENAMETOOLONG;
573 if (snprintf(ecb_name, CRYPTO_MAX_ALG_NAME, "ecb(%s)",
574 cipher_name) >= CRYPTO_MAX_ALG_NAME)
575 goto err_free_inst;
576
577 err = crypto_grab_skcipher(spawn, ecb_name, 0,
578 crypto_requires_sync(algt->type,
579 algt->mask));
580 }
581
582 if (err)
583 goto err_free_inst;
584
585 alg = crypto_skcipher_spawn_alg(spawn);
586
587 err = -EINVAL;
588 if (alg->base.cra_blocksize != LRW_BLOCK_SIZE)
589 goto err_drop_spawn;
590
591 if (crypto_skcipher_alg_ivsize(alg))
592 goto err_drop_spawn;
593
594 err = crypto_inst_setname(skcipher_crypto_instance(inst), "lrw",
595 &alg->base);
596 if (err)
597 goto err_drop_spawn;
598
599 err = -EINVAL;
600 cipher_name = alg->base.cra_name;
601
602 /* Alas we screwed up the naming so we have to mangle the
603 * cipher name.
604 */
605 if (!strncmp(cipher_name, "ecb(", 4)) {
606 unsigned len;
607
608 len = strlcpy(ecb_name, cipher_name + 4, sizeof(ecb_name));
609 if (len < 2 || len >= sizeof(ecb_name))
610 goto err_drop_spawn;
611
612 if (ecb_name[len - 1] != ')')
613 goto err_drop_spawn;
614
615 ecb_name[len - 1] = 0;
616
617 if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME,
618 "lrw(%s)", ecb_name) >= CRYPTO_MAX_ALG_NAME) {
619 err = -ENAMETOOLONG;
620 goto err_drop_spawn;
621 }
622 }
623
624 inst->alg.base.cra_flags = alg->base.cra_flags & CRYPTO_ALG_ASYNC;
625 inst->alg.base.cra_priority = alg->base.cra_priority;
626 inst->alg.base.cra_blocksize = LRW_BLOCK_SIZE;
627 inst->alg.base.cra_alignmask = alg->base.cra_alignmask |
628 (__alignof__(u64) - 1);
629
630 inst->alg.ivsize = LRW_BLOCK_SIZE;
631 inst->alg.min_keysize = crypto_skcipher_alg_min_keysize(alg) +
632 LRW_BLOCK_SIZE;
633 inst->alg.max_keysize = crypto_skcipher_alg_max_keysize(alg) +
634 LRW_BLOCK_SIZE;
635
636 inst->alg.base.cra_ctxsize = sizeof(struct priv);
637
638 inst->alg.init = init_tfm;
639 inst->alg.exit = exit_tfm;
640
641 inst->alg.setkey = setkey;
642 inst->alg.encrypt = encrypt;
643 inst->alg.decrypt = decrypt;
644
645 inst->free = free;
646
647 err = skcipher_register_instance(tmpl, inst);
648 if (err)
649 goto err_drop_spawn;
650
651 out:
652 return err;
653
654 err_drop_spawn:
655 crypto_drop_skcipher(spawn);
656 err_free_inst:
657 kfree(inst);
658 goto out;
659 }
660
661 static struct crypto_template crypto_tmpl = {
662 .name = "lrw",
663 .create = create,
664 .module = THIS_MODULE,
665 };
666
crypto_module_init(void)667 static int __init crypto_module_init(void)
668 {
669 return crypto_register_template(&crypto_tmpl);
670 }
671
crypto_module_exit(void)672 static void __exit crypto_module_exit(void)
673 {
674 crypto_unregister_template(&crypto_tmpl);
675 }
676
677 module_init(crypto_module_init);
678 module_exit(crypto_module_exit);
679
680 MODULE_LICENSE("GPL");
681 MODULE_DESCRIPTION("LRW block cipher mode");
682 MODULE_ALIAS_CRYPTO("lrw");
683