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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
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
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
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
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
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 */
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 return x;
143 }
144
145 static int post_crypt(struct skcipher_request *req)
146 {
147 struct rctx *rctx = skcipher_request_ctx(req);
148 be128 *buf = rctx->ext ?: rctx->buf;
149 struct skcipher_request *subreq;
150 const int bs = LRW_BLOCK_SIZE;
151 struct skcipher_walk w;
152 struct scatterlist *sg;
153 unsigned offset;
154 int err;
155
156 subreq = &rctx->subreq;
157 err = skcipher_walk_virt(&w, subreq, false);
158
159 while (w.nbytes) {
160 unsigned int avail = w.nbytes;
161 be128 *wdst;
162
163 wdst = w.dst.virt.addr;
164
165 do {
166 be128_xor(wdst, buf++, wdst);
167 wdst++;
168 } while ((avail -= bs) >= bs);
169
170 err = skcipher_walk_done(&w, avail);
171 }
172
173 rctx->left -= subreq->cryptlen;
174
175 if (err || !rctx->left)
176 goto out;
177
178 rctx->dst = rctx->dstbuf;
179
180 scatterwalk_done(&w.out, 0, 1);
181 sg = w.out.sg;
182 offset = w.out.offset;
183
184 if (rctx->dst != sg) {
185 rctx->dst[0] = *sg;
186 sg_unmark_end(rctx->dst);
187 scatterwalk_crypto_chain(rctx->dst, sg_next(sg), 0, 2);
188 }
189 rctx->dst[0].length -= offset - sg->offset;
190 rctx->dst[0].offset = offset;
191
192 out:
193 return err;
194 }
195
196 static int pre_crypt(struct skcipher_request *req)
197 {
198 struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
199 struct rctx *rctx = skcipher_request_ctx(req);
200 struct priv *ctx = crypto_skcipher_ctx(tfm);
201 be128 *buf = rctx->ext ?: rctx->buf;
202 struct skcipher_request *subreq;
203 const int bs = LRW_BLOCK_SIZE;
204 struct skcipher_walk w;
205 struct scatterlist *sg;
206 unsigned cryptlen;
207 unsigned offset;
208 be128 *iv;
209 bool more;
210 int err;
211
212 subreq = &rctx->subreq;
213 skcipher_request_set_tfm(subreq, tfm);
214
215 cryptlen = subreq->cryptlen;
216 more = rctx->left > cryptlen;
217 if (!more)
218 cryptlen = rctx->left;
219
220 skcipher_request_set_crypt(subreq, rctx->src, rctx->dst,
221 cryptlen, req->iv);
222
223 err = skcipher_walk_virt(&w, subreq, false);
224 iv = w.iv;
225
226 while (w.nbytes) {
227 unsigned int avail = w.nbytes;
228 be128 *wsrc;
229 be128 *wdst;
230
231 wsrc = w.src.virt.addr;
232 wdst = w.dst.virt.addr;
233
234 do {
235 *buf++ = rctx->t;
236 be128_xor(wdst++, &rctx->t, wsrc++);
237
238 /* T <- I*Key2, using the optimization
239 * discussed in the specification */
240 be128_xor(&rctx->t, &rctx->t,
241 &ctx->table.mulinc[get_index128(iv)]);
242 inc(iv);
243 } while ((avail -= bs) >= bs);
244
245 err = skcipher_walk_done(&w, avail);
246 }
247
248 skcipher_request_set_tfm(subreq, ctx->child);
249 skcipher_request_set_crypt(subreq, rctx->dst, rctx->dst,
250 cryptlen, NULL);
251
252 if (err || !more)
253 goto out;
254
255 rctx->src = rctx->srcbuf;
256
257 scatterwalk_done(&w.in, 0, 1);
258 sg = w.in.sg;
259 offset = w.in.offset;
260
261 if (rctx->src != sg) {
262 rctx->src[0] = *sg;
263 sg_unmark_end(rctx->src);
264 scatterwalk_crypto_chain(rctx->src, sg_next(sg), 0, 2);
265 }
266 rctx->src[0].length -= offset - sg->offset;
267 rctx->src[0].offset = offset;
268
269 out:
270 return err;
271 }
272
273 static int init_crypt(struct skcipher_request *req, crypto_completion_t done)
274 {
275 struct priv *ctx = crypto_skcipher_ctx(crypto_skcipher_reqtfm(req));
276 struct rctx *rctx = skcipher_request_ctx(req);
277 struct skcipher_request *subreq;
278 gfp_t gfp;
279
280 subreq = &rctx->subreq;
281 skcipher_request_set_callback(subreq, req->base.flags, done, req);
282
283 gfp = req->base.flags & CRYPTO_TFM_REQ_MAY_SLEEP ? GFP_KERNEL :
284 GFP_ATOMIC;
285 rctx->ext = NULL;
286
287 subreq->cryptlen = LRW_BUFFER_SIZE;
288 if (req->cryptlen > LRW_BUFFER_SIZE) {
289 unsigned int n = min(req->cryptlen, (unsigned int)PAGE_SIZE);
290
291 rctx->ext = kmalloc(n, gfp);
292 if (rctx->ext)
293 subreq->cryptlen = n;
294 }
295
296 rctx->src = req->src;
297 rctx->dst = req->dst;
298 rctx->left = req->cryptlen;
299
300 /* calculate first value of T */
301 memcpy(&rctx->t, req->iv, sizeof(rctx->t));
302
303 /* T <- I*Key2 */
304 gf128mul_64k_bbe(&rctx->t, ctx->table.table);
305
306 return 0;
307 }
308
309 static void exit_crypt(struct skcipher_request *req)
310 {
311 struct rctx *rctx = skcipher_request_ctx(req);
312
313 rctx->left = 0;
314
315 if (rctx->ext)
316 kfree(rctx->ext);
317 }
318
319 static int do_encrypt(struct skcipher_request *req, int err)
320 {
321 struct rctx *rctx = skcipher_request_ctx(req);
322 struct skcipher_request *subreq;
323
324 subreq = &rctx->subreq;
325
326 while (!err && rctx->left) {
327 err = pre_crypt(req) ?:
328 crypto_skcipher_encrypt(subreq) ?:
329 post_crypt(req);
330
331 if (err == -EINPROGRESS ||
332 (err == -EBUSY &&
333 req->base.flags & CRYPTO_TFM_REQ_MAY_BACKLOG))
334 return err;
335 }
336
337 exit_crypt(req);
338 return err;
339 }
340
341 static void encrypt_done(struct crypto_async_request *areq, int err)
342 {
343 struct skcipher_request *req = areq->data;
344 struct skcipher_request *subreq;
345 struct rctx *rctx;
346
347 rctx = skcipher_request_ctx(req);
348 subreq = &rctx->subreq;
349 subreq->base.flags &= CRYPTO_TFM_REQ_MAY_BACKLOG;
350
351 err = do_encrypt(req, err ?: post_crypt(req));
352 if (rctx->left)
353 return;
354
355 skcipher_request_complete(req, err);
356 }
357
358 static int encrypt(struct skcipher_request *req)
359 {
360 return do_encrypt(req, init_crypt(req, encrypt_done));
361 }
362
363 static int do_decrypt(struct skcipher_request *req, int err)
364 {
365 struct rctx *rctx = skcipher_request_ctx(req);
366 struct skcipher_request *subreq;
367
368 subreq = &rctx->subreq;
369
370 while (!err && rctx->left) {
371 err = pre_crypt(req) ?:
372 crypto_skcipher_decrypt(subreq) ?:
373 post_crypt(req);
374
375 if (err == -EINPROGRESS ||
376 (err == -EBUSY &&
377 req->base.flags & CRYPTO_TFM_REQ_MAY_BACKLOG))
378 return err;
379 }
380
381 exit_crypt(req);
382 return err;
383 }
384
385 static void decrypt_done(struct crypto_async_request *areq, int err)
386 {
387 struct skcipher_request *req = areq->data;
388 struct skcipher_request *subreq;
389 struct rctx *rctx;
390
391 rctx = skcipher_request_ctx(req);
392 subreq = &rctx->subreq;
393 subreq->base.flags &= CRYPTO_TFM_REQ_MAY_BACKLOG;
394
395 err = do_decrypt(req, err ?: post_crypt(req));
396 if (rctx->left)
397 return;
398
399 skcipher_request_complete(req, err);
400 }
401
402 static int decrypt(struct skcipher_request *req)
403 {
404 return do_decrypt(req, init_crypt(req, decrypt_done));
405 }
406
407 int lrw_crypt(struct blkcipher_desc *desc, struct scatterlist *sdst,
408 struct scatterlist *ssrc, unsigned int nbytes,
409 struct lrw_crypt_req *req)
410 {
411 const unsigned int bsize = LRW_BLOCK_SIZE;
412 const unsigned int max_blks = req->tbuflen / bsize;
413 struct lrw_table_ctx *ctx = req->table_ctx;
414 struct blkcipher_walk walk;
415 unsigned int nblocks;
416 be128 *iv, *src, *dst, *t;
417 be128 *t_buf = req->tbuf;
418 int err, i;
419
420 BUG_ON(max_blks < 1);
421
422 blkcipher_walk_init(&walk, sdst, ssrc, nbytes);
423
424 err = blkcipher_walk_virt(desc, &walk);
425 nbytes = walk.nbytes;
426 if (!nbytes)
427 return err;
428
429 nblocks = min(walk.nbytes / bsize, max_blks);
430 src = (be128 *)walk.src.virt.addr;
431 dst = (be128 *)walk.dst.virt.addr;
432
433 /* calculate first value of T */
434 iv = (be128 *)walk.iv;
435 t_buf[0] = *iv;
436
437 /* T <- I*Key2 */
438 gf128mul_64k_bbe(&t_buf[0], ctx->table);
439
440 i = 0;
441 goto first;
442
443 for (;;) {
444 do {
445 for (i = 0; i < nblocks; i++) {
446 /* T <- I*Key2, using the optimization
447 * discussed in the specification */
448 be128_xor(&t_buf[i], t,
449 &ctx->mulinc[get_index128(iv)]);
450 inc(iv);
451 first:
452 t = &t_buf[i];
453
454 /* PP <- T xor P */
455 be128_xor(dst + i, t, src + i);
456 }
457
458 /* CC <- E(Key2,PP) */
459 req->crypt_fn(req->crypt_ctx, (u8 *)dst,
460 nblocks * bsize);
461
462 /* C <- T xor CC */
463 for (i = 0; i < nblocks; i++)
464 be128_xor(dst + i, dst + i, &t_buf[i]);
465
466 src += nblocks;
467 dst += nblocks;
468 nbytes -= nblocks * bsize;
469 nblocks = min(nbytes / bsize, max_blks);
470 } while (nblocks > 0);
471
472 err = blkcipher_walk_done(desc, &walk, nbytes);
473 nbytes = walk.nbytes;
474 if (!nbytes)
475 break;
476
477 nblocks = min(nbytes / bsize, max_blks);
478 src = (be128 *)walk.src.virt.addr;
479 dst = (be128 *)walk.dst.virt.addr;
480 }
481
482 return err;
483 }
484 EXPORT_SYMBOL_GPL(lrw_crypt);
485
486 static int init_tfm(struct crypto_skcipher *tfm)
487 {
488 struct skcipher_instance *inst = skcipher_alg_instance(tfm);
489 struct crypto_skcipher_spawn *spawn = skcipher_instance_ctx(inst);
490 struct priv *ctx = crypto_skcipher_ctx(tfm);
491 struct crypto_skcipher *cipher;
492
493 cipher = crypto_spawn_skcipher(spawn);
494 if (IS_ERR(cipher))
495 return PTR_ERR(cipher);
496
497 ctx->child = cipher;
498
499 crypto_skcipher_set_reqsize(tfm, crypto_skcipher_reqsize(cipher) +
500 sizeof(struct rctx));
501
502 return 0;
503 }
504
505 static void exit_tfm(struct crypto_skcipher *tfm)
506 {
507 struct priv *ctx = crypto_skcipher_ctx(tfm);
508
509 lrw_free_table(&ctx->table);
510 crypto_free_skcipher(ctx->child);
511 }
512
513 static void free(struct skcipher_instance *inst)
514 {
515 crypto_drop_skcipher(skcipher_instance_ctx(inst));
516 kfree(inst);
517 }
518
519 static int create(struct crypto_template *tmpl, struct rtattr **tb)
520 {
521 struct crypto_skcipher_spawn *spawn;
522 struct skcipher_instance *inst;
523 struct crypto_attr_type *algt;
524 struct skcipher_alg *alg;
525 const char *cipher_name;
526 char ecb_name[CRYPTO_MAX_ALG_NAME];
527 int err;
528
529 algt = crypto_get_attr_type(tb);
530 if (IS_ERR(algt))
531 return PTR_ERR(algt);
532
533 if ((algt->type ^ CRYPTO_ALG_TYPE_SKCIPHER) & algt->mask)
534 return -EINVAL;
535
536 cipher_name = crypto_attr_alg_name(tb[1]);
537 if (IS_ERR(cipher_name))
538 return PTR_ERR(cipher_name);
539
540 inst = kzalloc(sizeof(*inst) + sizeof(*spawn), GFP_KERNEL);
541 if (!inst)
542 return -ENOMEM;
543
544 spawn = skcipher_instance_ctx(inst);
545
546 crypto_set_skcipher_spawn(spawn, skcipher_crypto_instance(inst));
547 err = crypto_grab_skcipher(spawn, cipher_name, 0,
548 crypto_requires_sync(algt->type,
549 algt->mask));
550 if (err == -ENOENT) {
551 err = -ENAMETOOLONG;
552 if (snprintf(ecb_name, CRYPTO_MAX_ALG_NAME, "ecb(%s)",
553 cipher_name) >= CRYPTO_MAX_ALG_NAME)
554 goto err_free_inst;
555
556 err = crypto_grab_skcipher(spawn, ecb_name, 0,
557 crypto_requires_sync(algt->type,
558 algt->mask));
559 }
560
561 if (err)
562 goto err_free_inst;
563
564 alg = crypto_skcipher_spawn_alg(spawn);
565
566 err = -EINVAL;
567 if (alg->base.cra_blocksize != LRW_BLOCK_SIZE)
568 goto err_drop_spawn;
569
570 if (crypto_skcipher_alg_ivsize(alg))
571 goto err_drop_spawn;
572
573 err = crypto_inst_setname(skcipher_crypto_instance(inst), "lrw",
574 &alg->base);
575 if (err)
576 goto err_drop_spawn;
577
578 err = -EINVAL;
579 cipher_name = alg->base.cra_name;
580
581 /* Alas we screwed up the naming so we have to mangle the
582 * cipher name.
583 */
584 if (!strncmp(cipher_name, "ecb(", 4)) {
585 unsigned len;
586
587 len = strlcpy(ecb_name, cipher_name + 4, sizeof(ecb_name));
588 if (len < 2 || len >= sizeof(ecb_name))
589 goto err_drop_spawn;
590
591 if (ecb_name[len - 1] != ')')
592 goto err_drop_spawn;
593
594 ecb_name[len - 1] = 0;
595
596 if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME,
597 "lrw(%s)", ecb_name) >= CRYPTO_MAX_ALG_NAME)
598 return -ENAMETOOLONG;
599 }
600
601 inst->alg.base.cra_flags = alg->base.cra_flags & CRYPTO_ALG_ASYNC;
602 inst->alg.base.cra_priority = alg->base.cra_priority;
603 inst->alg.base.cra_blocksize = LRW_BLOCK_SIZE;
604 inst->alg.base.cra_alignmask = alg->base.cra_alignmask |
605 (__alignof__(u64) - 1);
606
607 inst->alg.ivsize = LRW_BLOCK_SIZE;
608 inst->alg.min_keysize = crypto_skcipher_alg_min_keysize(alg) +
609 LRW_BLOCK_SIZE;
610 inst->alg.max_keysize = crypto_skcipher_alg_max_keysize(alg) +
611 LRW_BLOCK_SIZE;
612
613 inst->alg.base.cra_ctxsize = sizeof(struct priv);
614
615 inst->alg.init = init_tfm;
616 inst->alg.exit = exit_tfm;
617
618 inst->alg.setkey = setkey;
619 inst->alg.encrypt = encrypt;
620 inst->alg.decrypt = decrypt;
621
622 inst->free = free;
623
624 err = skcipher_register_instance(tmpl, inst);
625 if (err)
626 goto err_drop_spawn;
627
628 out:
629 return err;
630
631 err_drop_spawn:
632 crypto_drop_skcipher(spawn);
633 err_free_inst:
634 kfree(inst);
635 goto out;
636 }
637
638 static struct crypto_template crypto_tmpl = {
639 .name = "lrw",
640 .create = create,
641 .module = THIS_MODULE,
642 };
643
644 static int __init crypto_module_init(void)
645 {
646 return crypto_register_template(&crypto_tmpl);
647 }
648
649 static void __exit crypto_module_exit(void)
650 {
651 crypto_unregister_template(&crypto_tmpl);
652 }
653
654 module_init(crypto_module_init);
655 module_exit(crypto_module_exit);
656
657 MODULE_LICENSE("GPL");
658 MODULE_DESCRIPTION("LRW block cipher mode");
659 MODULE_ALIAS_CRYPTO("lrw");