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
32 #define LRW_BUFFER_SIZE 128u
33
34 #define LRW_BLOCK_SIZE 16
35
36 struct priv {
37 struct crypto_skcipher *child;
38
39 /*
40 * optimizes multiplying a random (non incrementing, as at the
41 * start of a new sector) value with key2, we could also have
42 * used 4k optimization tables or no optimization at all. In the
43 * latter case we would have to store key2 here
44 */
45 struct gf128mul_64k *table;
46
47 /*
48 * stores:
49 * key2*{ 0,0,...0,0,0,0,1 }, key2*{ 0,0,...0,0,0,1,1 },
50 * key2*{ 0,0,...0,0,1,1,1 }, key2*{ 0,0,...0,1,1,1,1 }
51 * key2*{ 0,0,...1,1,1,1,1 }, etc
52 * needed for optimized multiplication of incrementing values
53 * with key2
54 */
55 be128 mulinc[128];
56 };
57
58 struct rctx {
59 be128 buf[LRW_BUFFER_SIZE / sizeof(be128)];
60
61 be128 t;
62
63 be128 *ext;
64
65 struct scatterlist srcbuf[2];
66 struct scatterlist dstbuf[2];
67 struct scatterlist *src;
68 struct scatterlist *dst;
69
70 unsigned int left;
71
72 struct skcipher_request subreq;
73 };
74
setbit128_bbe(void * b,int bit)75 static inline void setbit128_bbe(void *b, int bit)
76 {
77 __set_bit(bit ^ (0x80 -
78 #ifdef __BIG_ENDIAN
79 BITS_PER_LONG
80 #else
81 BITS_PER_BYTE
82 #endif
83 ), b);
84 }
85
setkey(struct crypto_skcipher * parent,const u8 * key,unsigned int keylen)86 static int setkey(struct crypto_skcipher *parent, const u8 *key,
87 unsigned int keylen)
88 {
89 struct priv *ctx = crypto_skcipher_ctx(parent);
90 struct crypto_skcipher *child = ctx->child;
91 int err, bsize = LRW_BLOCK_SIZE;
92 const u8 *tweak = key + keylen - bsize;
93 be128 tmp = { 0 };
94 int i;
95
96 crypto_skcipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
97 crypto_skcipher_set_flags(child, crypto_skcipher_get_flags(parent) &
98 CRYPTO_TFM_REQ_MASK);
99 err = crypto_skcipher_setkey(child, key, keylen - bsize);
100 crypto_skcipher_set_flags(parent, crypto_skcipher_get_flags(child) &
101 CRYPTO_TFM_RES_MASK);
102 if (err)
103 return err;
104
105 if (ctx->table)
106 gf128mul_free_64k(ctx->table);
107
108 /* initialize multiplication table for Key2 */
109 ctx->table = gf128mul_init_64k_bbe((be128 *)tweak);
110 if (!ctx->table)
111 return -ENOMEM;
112
113 /* initialize optimization table */
114 for (i = 0; i < 128; i++) {
115 setbit128_bbe(&tmp, i);
116 ctx->mulinc[i] = tmp;
117 gf128mul_64k_bbe(&ctx->mulinc[i], ctx->table);
118 }
119
120 return 0;
121 }
122
inc(be128 * iv)123 static inline void inc(be128 *iv)
124 {
125 be64_add_cpu(&iv->b, 1);
126 if (!iv->b)
127 be64_add_cpu(&iv->a, 1);
128 }
129
130 /* this returns the number of consequative 1 bits starting
131 * from the right, get_index128(00 00 00 00 00 00 ... 00 00 10 FB) = 2 */
get_index128(be128 * block)132 static inline int get_index128(be128 *block)
133 {
134 int x;
135 __be32 *p = (__be32 *) block;
136
137 for (p += 3, x = 0; x < 128; p--, x += 32) {
138 u32 val = be32_to_cpup(p);
139
140 if (!~val)
141 continue;
142
143 return x + ffz(val);
144 }
145
146 return x;
147 }
148
post_crypt(struct skcipher_request * req)149 static int post_crypt(struct skcipher_request *req)
150 {
151 struct rctx *rctx = skcipher_request_ctx(req);
152 be128 *buf = rctx->ext ?: rctx->buf;
153 struct skcipher_request *subreq;
154 const int bs = LRW_BLOCK_SIZE;
155 struct skcipher_walk w;
156 struct scatterlist *sg;
157 unsigned offset;
158 int err;
159
160 subreq = &rctx->subreq;
161 err = skcipher_walk_virt(&w, subreq, false);
162
163 while (w.nbytes) {
164 unsigned int avail = w.nbytes;
165 be128 *wdst;
166
167 wdst = w.dst.virt.addr;
168
169 do {
170 be128_xor(wdst, buf++, wdst);
171 wdst++;
172 } while ((avail -= bs) >= bs);
173
174 err = skcipher_walk_done(&w, avail);
175 }
176
177 rctx->left -= subreq->cryptlen;
178
179 if (err || !rctx->left)
180 goto out;
181
182 rctx->dst = rctx->dstbuf;
183
184 scatterwalk_done(&w.out, 0, 1);
185 sg = w.out.sg;
186 offset = w.out.offset;
187
188 if (rctx->dst != sg) {
189 rctx->dst[0] = *sg;
190 sg_unmark_end(rctx->dst);
191 scatterwalk_crypto_chain(rctx->dst, sg_next(sg), 2);
192 }
193 rctx->dst[0].length -= offset - sg->offset;
194 rctx->dst[0].offset = offset;
195
196 out:
197 return err;
198 }
199
pre_crypt(struct skcipher_request * req)200 static int pre_crypt(struct skcipher_request *req)
201 {
202 struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
203 struct rctx *rctx = skcipher_request_ctx(req);
204 struct priv *ctx = crypto_skcipher_ctx(tfm);
205 be128 *buf = rctx->ext ?: rctx->buf;
206 struct skcipher_request *subreq;
207 const int bs = LRW_BLOCK_SIZE;
208 struct skcipher_walk w;
209 struct scatterlist *sg;
210 unsigned cryptlen;
211 unsigned offset;
212 be128 *iv;
213 bool more;
214 int err;
215
216 subreq = &rctx->subreq;
217 skcipher_request_set_tfm(subreq, tfm);
218
219 cryptlen = subreq->cryptlen;
220 more = rctx->left > cryptlen;
221 if (!more)
222 cryptlen = rctx->left;
223
224 skcipher_request_set_crypt(subreq, rctx->src, rctx->dst,
225 cryptlen, req->iv);
226
227 err = skcipher_walk_virt(&w, subreq, false);
228 iv = w.iv;
229
230 while (w.nbytes) {
231 unsigned int avail = w.nbytes;
232 be128 *wsrc;
233 be128 *wdst;
234
235 wsrc = w.src.virt.addr;
236 wdst = w.dst.virt.addr;
237
238 do {
239 *buf++ = rctx->t;
240 be128_xor(wdst++, &rctx->t, wsrc++);
241
242 /* T <- I*Key2, using the optimization
243 * discussed in the specification */
244 be128_xor(&rctx->t, &rctx->t,
245 &ctx->mulinc[get_index128(iv)]);
246 inc(iv);
247 } while ((avail -= bs) >= bs);
248
249 err = skcipher_walk_done(&w, avail);
250 }
251
252 skcipher_request_set_tfm(subreq, ctx->child);
253 skcipher_request_set_crypt(subreq, rctx->dst, rctx->dst,
254 cryptlen, NULL);
255
256 if (err || !more)
257 goto out;
258
259 rctx->src = rctx->srcbuf;
260
261 scatterwalk_done(&w.in, 0, 1);
262 sg = w.in.sg;
263 offset = w.in.offset;
264
265 if (rctx->src != sg) {
266 rctx->src[0] = *sg;
267 sg_unmark_end(rctx->src);
268 scatterwalk_crypto_chain(rctx->src, sg_next(sg), 2);
269 }
270 rctx->src[0].length -= offset - sg->offset;
271 rctx->src[0].offset = offset;
272
273 out:
274 return err;
275 }
276
init_crypt(struct skcipher_request * req,crypto_completion_t done)277 static int init_crypt(struct skcipher_request *req, crypto_completion_t done)
278 {
279 struct priv *ctx = crypto_skcipher_ctx(crypto_skcipher_reqtfm(req));
280 struct rctx *rctx = skcipher_request_ctx(req);
281 struct skcipher_request *subreq;
282 gfp_t gfp;
283
284 subreq = &rctx->subreq;
285 skcipher_request_set_callback(subreq, req->base.flags, done, req);
286
287 gfp = req->base.flags & CRYPTO_TFM_REQ_MAY_SLEEP ? GFP_KERNEL :
288 GFP_ATOMIC;
289 rctx->ext = NULL;
290
291 subreq->cryptlen = LRW_BUFFER_SIZE;
292 if (req->cryptlen > LRW_BUFFER_SIZE) {
293 unsigned int n = min(req->cryptlen, (unsigned int)PAGE_SIZE);
294
295 rctx->ext = kmalloc(n, gfp);
296 if (rctx->ext)
297 subreq->cryptlen = n;
298 }
299
300 rctx->src = req->src;
301 rctx->dst = req->dst;
302 rctx->left = req->cryptlen;
303
304 /* calculate first value of T */
305 memcpy(&rctx->t, req->iv, sizeof(rctx->t));
306
307 /* T <- I*Key2 */
308 gf128mul_64k_bbe(&rctx->t, ctx->table);
309
310 return 0;
311 }
312
exit_crypt(struct skcipher_request * req)313 static void exit_crypt(struct skcipher_request *req)
314 {
315 struct rctx *rctx = skcipher_request_ctx(req);
316
317 rctx->left = 0;
318
319 if (rctx->ext)
320 kzfree(rctx->ext);
321 }
322
do_encrypt(struct skcipher_request * req,int err)323 static int do_encrypt(struct skcipher_request *req, int err)
324 {
325 struct rctx *rctx = skcipher_request_ctx(req);
326 struct skcipher_request *subreq;
327
328 subreq = &rctx->subreq;
329
330 while (!err && rctx->left) {
331 err = pre_crypt(req) ?:
332 crypto_skcipher_encrypt(subreq) ?:
333 post_crypt(req);
334
335 if (err == -EINPROGRESS || err == -EBUSY)
336 return err;
337 }
338
339 exit_crypt(req);
340 return err;
341 }
342
encrypt_done(struct crypto_async_request * areq,int err)343 static void encrypt_done(struct crypto_async_request *areq, int err)
344 {
345 struct skcipher_request *req = areq->data;
346 struct skcipher_request *subreq;
347 struct rctx *rctx;
348
349 rctx = skcipher_request_ctx(req);
350
351 if (err == -EINPROGRESS) {
352 if (rctx->left != req->cryptlen)
353 return;
354 goto out;
355 }
356
357 subreq = &rctx->subreq;
358 subreq->base.flags &= CRYPTO_TFM_REQ_MAY_BACKLOG;
359
360 err = do_encrypt(req, err ?: post_crypt(req));
361 if (rctx->left)
362 return;
363
364 out:
365 skcipher_request_complete(req, err);
366 }
367
encrypt(struct skcipher_request * req)368 static int encrypt(struct skcipher_request *req)
369 {
370 return do_encrypt(req, init_crypt(req, encrypt_done));
371 }
372
do_decrypt(struct skcipher_request * req,int err)373 static int do_decrypt(struct skcipher_request *req, int err)
374 {
375 struct rctx *rctx = skcipher_request_ctx(req);
376 struct skcipher_request *subreq;
377
378 subreq = &rctx->subreq;
379
380 while (!err && rctx->left) {
381 err = pre_crypt(req) ?:
382 crypto_skcipher_decrypt(subreq) ?:
383 post_crypt(req);
384
385 if (err == -EINPROGRESS || err == -EBUSY)
386 return err;
387 }
388
389 exit_crypt(req);
390 return err;
391 }
392
decrypt_done(struct crypto_async_request * areq,int err)393 static void decrypt_done(struct crypto_async_request *areq, int err)
394 {
395 struct skcipher_request *req = areq->data;
396 struct skcipher_request *subreq;
397 struct rctx *rctx;
398
399 rctx = skcipher_request_ctx(req);
400
401 if (err == -EINPROGRESS) {
402 if (rctx->left != req->cryptlen)
403 return;
404 goto out;
405 }
406
407 subreq = &rctx->subreq;
408 subreq->base.flags &= CRYPTO_TFM_REQ_MAY_BACKLOG;
409
410 err = do_decrypt(req, err ?: post_crypt(req));
411 if (rctx->left)
412 return;
413
414 out:
415 skcipher_request_complete(req, err);
416 }
417
decrypt(struct skcipher_request * req)418 static int decrypt(struct skcipher_request *req)
419 {
420 return do_decrypt(req, init_crypt(req, decrypt_done));
421 }
422
init_tfm(struct crypto_skcipher * tfm)423 static int init_tfm(struct crypto_skcipher *tfm)
424 {
425 struct skcipher_instance *inst = skcipher_alg_instance(tfm);
426 struct crypto_skcipher_spawn *spawn = skcipher_instance_ctx(inst);
427 struct priv *ctx = crypto_skcipher_ctx(tfm);
428 struct crypto_skcipher *cipher;
429
430 cipher = crypto_spawn_skcipher(spawn);
431 if (IS_ERR(cipher))
432 return PTR_ERR(cipher);
433
434 ctx->child = cipher;
435
436 crypto_skcipher_set_reqsize(tfm, crypto_skcipher_reqsize(cipher) +
437 sizeof(struct rctx));
438
439 return 0;
440 }
441
exit_tfm(struct crypto_skcipher * tfm)442 static void exit_tfm(struct crypto_skcipher *tfm)
443 {
444 struct priv *ctx = crypto_skcipher_ctx(tfm);
445
446 if (ctx->table)
447 gf128mul_free_64k(ctx->table);
448 crypto_free_skcipher(ctx->child);
449 }
450
free(struct skcipher_instance * inst)451 static void free(struct skcipher_instance *inst)
452 {
453 crypto_drop_skcipher(skcipher_instance_ctx(inst));
454 kfree(inst);
455 }
456
create(struct crypto_template * tmpl,struct rtattr ** tb)457 static int create(struct crypto_template *tmpl, struct rtattr **tb)
458 {
459 struct crypto_skcipher_spawn *spawn;
460 struct skcipher_instance *inst;
461 struct crypto_attr_type *algt;
462 struct skcipher_alg *alg;
463 const char *cipher_name;
464 char ecb_name[CRYPTO_MAX_ALG_NAME];
465 int err;
466
467 algt = crypto_get_attr_type(tb);
468 if (IS_ERR(algt))
469 return PTR_ERR(algt);
470
471 if ((algt->type ^ CRYPTO_ALG_TYPE_SKCIPHER) & algt->mask)
472 return -EINVAL;
473
474 cipher_name = crypto_attr_alg_name(tb[1]);
475 if (IS_ERR(cipher_name))
476 return PTR_ERR(cipher_name);
477
478 inst = kzalloc(sizeof(*inst) + sizeof(*spawn), GFP_KERNEL);
479 if (!inst)
480 return -ENOMEM;
481
482 spawn = skcipher_instance_ctx(inst);
483
484 crypto_set_skcipher_spawn(spawn, skcipher_crypto_instance(inst));
485 err = crypto_grab_skcipher(spawn, cipher_name, 0,
486 crypto_requires_sync(algt->type,
487 algt->mask));
488 if (err == -ENOENT) {
489 err = -ENAMETOOLONG;
490 if (snprintf(ecb_name, CRYPTO_MAX_ALG_NAME, "ecb(%s)",
491 cipher_name) >= CRYPTO_MAX_ALG_NAME)
492 goto err_free_inst;
493
494 err = crypto_grab_skcipher(spawn, ecb_name, 0,
495 crypto_requires_sync(algt->type,
496 algt->mask));
497 }
498
499 if (err)
500 goto err_free_inst;
501
502 alg = crypto_skcipher_spawn_alg(spawn);
503
504 err = -EINVAL;
505 if (alg->base.cra_blocksize != LRW_BLOCK_SIZE)
506 goto err_drop_spawn;
507
508 if (crypto_skcipher_alg_ivsize(alg))
509 goto err_drop_spawn;
510
511 err = crypto_inst_setname(skcipher_crypto_instance(inst), "lrw",
512 &alg->base);
513 if (err)
514 goto err_drop_spawn;
515
516 err = -EINVAL;
517 cipher_name = alg->base.cra_name;
518
519 /* Alas we screwed up the naming so we have to mangle the
520 * cipher name.
521 */
522 if (!strncmp(cipher_name, "ecb(", 4)) {
523 unsigned len;
524
525 len = strlcpy(ecb_name, cipher_name + 4, sizeof(ecb_name));
526 if (len < 2 || len >= sizeof(ecb_name))
527 goto err_drop_spawn;
528
529 if (ecb_name[len - 1] != ')')
530 goto err_drop_spawn;
531
532 ecb_name[len - 1] = 0;
533
534 if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME,
535 "lrw(%s)", ecb_name) >= CRYPTO_MAX_ALG_NAME) {
536 err = -ENAMETOOLONG;
537 goto err_drop_spawn;
538 }
539 } else
540 goto err_drop_spawn;
541
542 inst->alg.base.cra_flags = alg->base.cra_flags & CRYPTO_ALG_ASYNC;
543 inst->alg.base.cra_priority = alg->base.cra_priority;
544 inst->alg.base.cra_blocksize = LRW_BLOCK_SIZE;
545 inst->alg.base.cra_alignmask = alg->base.cra_alignmask |
546 (__alignof__(u64) - 1);
547
548 inst->alg.ivsize = LRW_BLOCK_SIZE;
549 inst->alg.min_keysize = crypto_skcipher_alg_min_keysize(alg) +
550 LRW_BLOCK_SIZE;
551 inst->alg.max_keysize = crypto_skcipher_alg_max_keysize(alg) +
552 LRW_BLOCK_SIZE;
553
554 inst->alg.base.cra_ctxsize = sizeof(struct priv);
555
556 inst->alg.init = init_tfm;
557 inst->alg.exit = exit_tfm;
558
559 inst->alg.setkey = setkey;
560 inst->alg.encrypt = encrypt;
561 inst->alg.decrypt = decrypt;
562
563 inst->free = free;
564
565 err = skcipher_register_instance(tmpl, inst);
566 if (err)
567 goto err_drop_spawn;
568
569 out:
570 return err;
571
572 err_drop_spawn:
573 crypto_drop_skcipher(spawn);
574 err_free_inst:
575 kfree(inst);
576 goto out;
577 }
578
579 static struct crypto_template crypto_tmpl = {
580 .name = "lrw",
581 .create = create,
582 .module = THIS_MODULE,
583 };
584
crypto_module_init(void)585 static int __init crypto_module_init(void)
586 {
587 return crypto_register_template(&crypto_tmpl);
588 }
589
crypto_module_exit(void)590 static void __exit crypto_module_exit(void)
591 {
592 crypto_unregister_template(&crypto_tmpl);
593 }
594
595 module_init(crypto_module_init);
596 module_exit(crypto_module_exit);
597
598 MODULE_LICENSE("GPL");
599 MODULE_DESCRIPTION("LRW block cipher mode");
600 MODULE_ALIAS_CRYPTO("lrw");
601
