xref: /openbmc/linux/crypto/lrw.c (revision 4cff79e9) 
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 
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 
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 
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 */
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 
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), 0, 2);
192 	}
193 	rctx->dst[0].length -= offset - sg->offset;
194 	rctx->dst[0].offset = offset;
195 
196 out:
197 	return err;
198 }
199 
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), 0, 2);
269 	}
270 	rctx->src[0].length -= offset - sg->offset;
271 	rctx->src[0].offset = offset;
272 
273 out:
274 	return err;
275 }
276 
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 
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 
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 
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 
368 static int encrypt(struct skcipher_request *req)
369 {
370 	return do_encrypt(req, init_crypt(req, encrypt_done));
371 }
372 
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 
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 
418 static int decrypt(struct skcipher_request *req)
419 {
420 	return do_decrypt(req, init_crypt(req, decrypt_done));
421 }
422 
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 
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 
451 static void free(struct skcipher_instance *inst)
452 {
453 	crypto_drop_skcipher(skcipher_instance_ctx(inst));
454 	kfree(inst);
455 }
456 
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 
585 static int __init crypto_module_init(void)
586 {
587 	return crypto_register_template(&crypto_tmpl);
588 }
589 
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