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 /*
147 * If we get here, then x == 128 and we are incrementing the counter
148 * from all ones to all zeros. This means we must return index 127, i.e.
149 * the one corresponding to key2*{ 1,...,1 }.
150 */
151 return 127;
152 }
153
post_crypt(struct skcipher_request * req)154 static int post_crypt(struct skcipher_request *req)
155 {
156 struct rctx *rctx = skcipher_request_ctx(req);
157 be128 *buf = rctx->ext ?: rctx->buf;
158 struct skcipher_request *subreq;
159 const int bs = LRW_BLOCK_SIZE;
160 struct skcipher_walk w;
161 struct scatterlist *sg;
162 unsigned offset;
163 int err;
164
165 subreq = &rctx->subreq;
166 err = skcipher_walk_virt(&w, subreq, false);
167
168 while (w.nbytes) {
169 unsigned int avail = w.nbytes;
170 be128 *wdst;
171
172 wdst = w.dst.virt.addr;
173
174 do {
175 be128_xor(wdst, buf++, wdst);
176 wdst++;
177 } while ((avail -= bs) >= bs);
178
179 err = skcipher_walk_done(&w, avail);
180 }
181
182 rctx->left -= subreq->cryptlen;
183
184 if (err || !rctx->left)
185 goto out;
186
187 rctx->dst = rctx->dstbuf;
188
189 scatterwalk_done(&w.out, 0, 1);
190 sg = w.out.sg;
191 offset = w.out.offset;
192
193 if (rctx->dst != sg) {
194 rctx->dst[0] = *sg;
195 sg_unmark_end(rctx->dst);
196 scatterwalk_crypto_chain(rctx->dst, sg_next(sg), 2);
197 }
198 rctx->dst[0].length -= offset - sg->offset;
199 rctx->dst[0].offset = offset;
200
201 out:
202 return err;
203 }
204
pre_crypt(struct skcipher_request * req)205 static int pre_crypt(struct skcipher_request *req)
206 {
207 struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
208 struct rctx *rctx = skcipher_request_ctx(req);
209 struct priv *ctx = crypto_skcipher_ctx(tfm);
210 be128 *buf = rctx->ext ?: rctx->buf;
211 struct skcipher_request *subreq;
212 const int bs = LRW_BLOCK_SIZE;
213 struct skcipher_walk w;
214 struct scatterlist *sg;
215 unsigned cryptlen;
216 unsigned offset;
217 be128 *iv;
218 bool more;
219 int err;
220
221 subreq = &rctx->subreq;
222 skcipher_request_set_tfm(subreq, tfm);
223
224 cryptlen = subreq->cryptlen;
225 more = rctx->left > cryptlen;
226 if (!more)
227 cryptlen = rctx->left;
228
229 skcipher_request_set_crypt(subreq, rctx->src, rctx->dst,
230 cryptlen, req->iv);
231
232 err = skcipher_walk_virt(&w, subreq, false);
233 iv = w.iv;
234
235 while (w.nbytes) {
236 unsigned int avail = w.nbytes;
237 be128 *wsrc;
238 be128 *wdst;
239
240 wsrc = w.src.virt.addr;
241 wdst = w.dst.virt.addr;
242
243 do {
244 *buf++ = rctx->t;
245 be128_xor(wdst++, &rctx->t, wsrc++);
246
247 /* T <- I*Key2, using the optimization
248 * discussed in the specification */
249 be128_xor(&rctx->t, &rctx->t,
250 &ctx->mulinc[get_index128(iv)]);
251 inc(iv);
252 } while ((avail -= bs) >= bs);
253
254 err = skcipher_walk_done(&w, avail);
255 }
256
257 skcipher_request_set_tfm(subreq, ctx->child);
258 skcipher_request_set_crypt(subreq, rctx->dst, rctx->dst,
259 cryptlen, NULL);
260
261 if (err || !more)
262 goto out;
263
264 rctx->src = rctx->srcbuf;
265
266 scatterwalk_done(&w.in, 0, 1);
267 sg = w.in.sg;
268 offset = w.in.offset;
269
270 if (rctx->src != sg) {
271 rctx->src[0] = *sg;
272 sg_unmark_end(rctx->src);
273 scatterwalk_crypto_chain(rctx->src, sg_next(sg), 2);
274 }
275 rctx->src[0].length -= offset - sg->offset;
276 rctx->src[0].offset = offset;
277
278 out:
279 return err;
280 }
281
init_crypt(struct skcipher_request * req,crypto_completion_t done)282 static int init_crypt(struct skcipher_request *req, crypto_completion_t done)
283 {
284 struct priv *ctx = crypto_skcipher_ctx(crypto_skcipher_reqtfm(req));
285 struct rctx *rctx = skcipher_request_ctx(req);
286 struct skcipher_request *subreq;
287 gfp_t gfp;
288
289 subreq = &rctx->subreq;
290 skcipher_request_set_callback(subreq, req->base.flags, done, req);
291
292 gfp = req->base.flags & CRYPTO_TFM_REQ_MAY_SLEEP ? GFP_KERNEL :
293 GFP_ATOMIC;
294 rctx->ext = NULL;
295
296 subreq->cryptlen = LRW_BUFFER_SIZE;
297 if (req->cryptlen > LRW_BUFFER_SIZE) {
298 unsigned int n = min(req->cryptlen, (unsigned int)PAGE_SIZE);
299
300 rctx->ext = kmalloc(n, gfp);
301 if (rctx->ext)
302 subreq->cryptlen = n;
303 }
304
305 rctx->src = req->src;
306 rctx->dst = req->dst;
307 rctx->left = req->cryptlen;
308
309 /* calculate first value of T */
310 memcpy(&rctx->t, req->iv, sizeof(rctx->t));
311
312 /* T <- I*Key2 */
313 gf128mul_64k_bbe(&rctx->t, ctx->table);
314
315 return 0;
316 }
317
exit_crypt(struct skcipher_request * req)318 static void exit_crypt(struct skcipher_request *req)
319 {
320 struct rctx *rctx = skcipher_request_ctx(req);
321
322 rctx->left = 0;
323
324 if (rctx->ext)
325 kzfree(rctx->ext);
326 }
327
do_encrypt(struct skcipher_request * req,int err)328 static int do_encrypt(struct skcipher_request *req, int err)
329 {
330 struct rctx *rctx = skcipher_request_ctx(req);
331 struct skcipher_request *subreq;
332
333 subreq = &rctx->subreq;
334
335 while (!err && rctx->left) {
336 err = pre_crypt(req) ?:
337 crypto_skcipher_encrypt(subreq) ?:
338 post_crypt(req);
339
340 if (err == -EINPROGRESS || err == -EBUSY)
341 return err;
342 }
343
344 exit_crypt(req);
345 return err;
346 }
347
encrypt_done(struct crypto_async_request * areq,int err)348 static void encrypt_done(struct crypto_async_request *areq, int err)
349 {
350 struct skcipher_request *req = areq->data;
351 struct skcipher_request *subreq;
352 struct rctx *rctx;
353
354 rctx = skcipher_request_ctx(req);
355
356 if (err == -EINPROGRESS) {
357 if (rctx->left != req->cryptlen)
358 return;
359 goto out;
360 }
361
362 subreq = &rctx->subreq;
363 subreq->base.flags &= CRYPTO_TFM_REQ_MAY_BACKLOG;
364
365 err = do_encrypt(req, err ?: post_crypt(req));
366 if (rctx->left)
367 return;
368
369 out:
370 skcipher_request_complete(req, err);
371 }
372
encrypt(struct skcipher_request * req)373 static int encrypt(struct skcipher_request *req)
374 {
375 return do_encrypt(req, init_crypt(req, encrypt_done));
376 }
377
do_decrypt(struct skcipher_request * req,int err)378 static int do_decrypt(struct skcipher_request *req, int err)
379 {
380 struct rctx *rctx = skcipher_request_ctx(req);
381 struct skcipher_request *subreq;
382
383 subreq = &rctx->subreq;
384
385 while (!err && rctx->left) {
386 err = pre_crypt(req) ?:
387 crypto_skcipher_decrypt(subreq) ?:
388 post_crypt(req);
389
390 if (err == -EINPROGRESS || err == -EBUSY)
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
init_tfm(struct crypto_skcipher * tfm)428 static int init_tfm(struct crypto_skcipher *tfm)
429 {
430 struct skcipher_instance *inst = skcipher_alg_instance(tfm);
431 struct crypto_skcipher_spawn *spawn = skcipher_instance_ctx(inst);
432 struct priv *ctx = crypto_skcipher_ctx(tfm);
433 struct crypto_skcipher *cipher;
434
435 cipher = crypto_spawn_skcipher(spawn);
436 if (IS_ERR(cipher))
437 return PTR_ERR(cipher);
438
439 ctx->child = cipher;
440
441 crypto_skcipher_set_reqsize(tfm, crypto_skcipher_reqsize(cipher) +
442 sizeof(struct rctx));
443
444 return 0;
445 }
446
exit_tfm(struct crypto_skcipher * tfm)447 static void exit_tfm(struct crypto_skcipher *tfm)
448 {
449 struct priv *ctx = crypto_skcipher_ctx(tfm);
450
451 if (ctx->table)
452 gf128mul_free_64k(ctx->table);
453 crypto_free_skcipher(ctx->child);
454 }
455
free_inst(struct skcipher_instance * inst)456 static void free_inst(struct skcipher_instance *inst)
457 {
458 crypto_drop_skcipher(skcipher_instance_ctx(inst));
459 kfree(inst);
460 }
461
create(struct crypto_template * tmpl,struct rtattr ** tb)462 static int create(struct crypto_template *tmpl, struct rtattr **tb)
463 {
464 struct crypto_skcipher_spawn *spawn;
465 struct skcipher_instance *inst;
466 struct crypto_attr_type *algt;
467 struct skcipher_alg *alg;
468 const char *cipher_name;
469 char ecb_name[CRYPTO_MAX_ALG_NAME];
470 int err;
471
472 algt = crypto_get_attr_type(tb);
473 if (IS_ERR(algt))
474 return PTR_ERR(algt);
475
476 if ((algt->type ^ CRYPTO_ALG_TYPE_SKCIPHER) & algt->mask)
477 return -EINVAL;
478
479 cipher_name = crypto_attr_alg_name(tb[1]);
480 if (IS_ERR(cipher_name))
481 return PTR_ERR(cipher_name);
482
483 inst = kzalloc(sizeof(*inst) + sizeof(*spawn), GFP_KERNEL);
484 if (!inst)
485 return -ENOMEM;
486
487 spawn = skcipher_instance_ctx(inst);
488
489 crypto_set_skcipher_spawn(spawn, skcipher_crypto_instance(inst));
490 err = crypto_grab_skcipher(spawn, cipher_name, 0,
491 crypto_requires_sync(algt->type,
492 algt->mask));
493 if (err == -ENOENT) {
494 err = -ENAMETOOLONG;
495 if (snprintf(ecb_name, CRYPTO_MAX_ALG_NAME, "ecb(%s)",
496 cipher_name) >= CRYPTO_MAX_ALG_NAME)
497 goto err_free_inst;
498
499 err = crypto_grab_skcipher(spawn, ecb_name, 0,
500 crypto_requires_sync(algt->type,
501 algt->mask));
502 }
503
504 if (err)
505 goto err_free_inst;
506
507 alg = crypto_skcipher_spawn_alg(spawn);
508
509 err = -EINVAL;
510 if (alg->base.cra_blocksize != LRW_BLOCK_SIZE)
511 goto err_drop_spawn;
512
513 if (crypto_skcipher_alg_ivsize(alg))
514 goto err_drop_spawn;
515
516 err = crypto_inst_setname(skcipher_crypto_instance(inst), "lrw",
517 &alg->base);
518 if (err)
519 goto err_drop_spawn;
520
521 err = -EINVAL;
522 cipher_name = alg->base.cra_name;
523
524 /* Alas we screwed up the naming so we have to mangle the
525 * cipher name.
526 */
527 if (!strncmp(cipher_name, "ecb(", 4)) {
528 unsigned len;
529
530 len = strlcpy(ecb_name, cipher_name + 4, sizeof(ecb_name));
531 if (len < 2 || len >= sizeof(ecb_name))
532 goto err_drop_spawn;
533
534 if (ecb_name[len - 1] != ')')
535 goto err_drop_spawn;
536
537 ecb_name[len - 1] = 0;
538
539 if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME,
540 "lrw(%s)", ecb_name) >= CRYPTO_MAX_ALG_NAME) {
541 err = -ENAMETOOLONG;
542 goto err_drop_spawn;
543 }
544 } else
545 goto err_drop_spawn;
546
547 inst->alg.base.cra_flags = alg->base.cra_flags & CRYPTO_ALG_ASYNC;
548 inst->alg.base.cra_priority = alg->base.cra_priority;
549 inst->alg.base.cra_blocksize = LRW_BLOCK_SIZE;
550 inst->alg.base.cra_alignmask = alg->base.cra_alignmask |
551 (__alignof__(u64) - 1);
552
553 inst->alg.ivsize = LRW_BLOCK_SIZE;
554 inst->alg.min_keysize = crypto_skcipher_alg_min_keysize(alg) +
555 LRW_BLOCK_SIZE;
556 inst->alg.max_keysize = crypto_skcipher_alg_max_keysize(alg) +
557 LRW_BLOCK_SIZE;
558
559 inst->alg.base.cra_ctxsize = sizeof(struct priv);
560
561 inst->alg.init = init_tfm;
562 inst->alg.exit = exit_tfm;
563
564 inst->alg.setkey = setkey;
565 inst->alg.encrypt = encrypt;
566 inst->alg.decrypt = decrypt;
567
568 inst->free = free_inst;
569
570 err = skcipher_register_instance(tmpl, inst);
571 if (err)
572 goto err_drop_spawn;
573
574 out:
575 return err;
576
577 err_drop_spawn:
578 crypto_drop_skcipher(spawn);
579 err_free_inst:
580 kfree(inst);
581 goto out;
582 }
583
584 static struct crypto_template crypto_tmpl = {
585 .name = "lrw",
586 .create = create,
587 .module = THIS_MODULE,
588 };
589
crypto_module_init(void)590 static int __init crypto_module_init(void)
591 {
592 return crypto_register_template(&crypto_tmpl);
593 }
594
crypto_module_exit(void)595 static void __exit crypto_module_exit(void)
596 {
597 crypto_unregister_template(&crypto_tmpl);
598 }
599
600 module_init(crypto_module_init);
601 module_exit(crypto_module_exit);
602
603 MODULE_LICENSE("GPL");
604 MODULE_DESCRIPTION("LRW block cipher mode");
605 MODULE_ALIAS_CRYPTO("lrw");
606