Home Home > GIT Browse
summaryrefslogtreecommitdiff
blob: ba42acc4deba8059c65dff053faef591e3175517 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
/* LRW: as defined by Cyril Guyot in
 *	http://grouper.ieee.org/groups/1619/email/pdf00017.pdf
 *
 * Copyright (c) 2006 Rik Snel <rsnel@cube.dyndns.org>
 *
 * Based on ecb.c
 * Copyright (c) 2006 Herbert Xu <herbert@gondor.apana.org.au>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the Free
 * Software Foundation; either version 2 of the License, or (at your option)
 * any later version.
 */
/* This implementation is checked against the test vectors in the above
 * document and by a test vector provided by Ken Buchanan at
 * http://www.mail-archive.com/stds-p1619@listserv.ieee.org/msg00173.html
 *
 * The test vectors are included in the testing module tcrypt.[ch] */

#include <crypto/algapi.h>
#include <linux/err.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/scatterlist.h>
#include <linux/slab.h>

#include <crypto/b128ops.h>
#include <crypto/gf128mul.h>
#include <crypto/lrw.h>

struct priv {
	struct crypto_cipher *child;
	struct lrw_table_ctx table;
};

static inline void setbit128_bbe(void *b, int bit)
{
	__set_bit(bit ^ (0x80 -
#ifdef __BIG_ENDIAN
			 BITS_PER_LONG
#else
			 BITS_PER_BYTE
#endif
			), b);
}

int lrw_init_table(struct lrw_table_ctx *ctx, const u8 *tweak)
{
	be128 tmp = { 0 };
	int i;

	if (ctx->table)
		gf128mul_free_64k(ctx->table);

	/* initialize multiplication table for Key2 */
	ctx->table = gf128mul_init_64k_bbe((be128 *)tweak);
	if (!ctx->table)
		return -ENOMEM;

	/* initialize optimization table */
	for (i = 0; i < 128; i++) {
		setbit128_bbe(&tmp, i);
		ctx->mulinc[i] = tmp;
		gf128mul_64k_bbe(&ctx->mulinc[i], ctx->table);
	}

	return 0;
}
EXPORT_SYMBOL_GPL(lrw_init_table);

void lrw_free_table(struct lrw_table_ctx *ctx)
{
	if (ctx->table)
		gf128mul_free_64k(ctx->table);
}
EXPORT_SYMBOL_GPL(lrw_free_table);

static int setkey(struct crypto_tfm *parent, const u8 *key,
		  unsigned int keylen)
{
	struct priv *ctx = crypto_tfm_ctx(parent);
	struct crypto_cipher *child = ctx->child;
	int err, bsize = LRW_BLOCK_SIZE;
	const u8 *tweak = key + keylen - bsize;

	crypto_cipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
	crypto_cipher_set_flags(child, crypto_tfm_get_flags(parent) &
				       CRYPTO_TFM_REQ_MASK);
	err = crypto_cipher_setkey(child, key, keylen - bsize);
	if (err)
		return err;
	crypto_tfm_set_flags(parent, crypto_cipher_get_flags(child) &
				     CRYPTO_TFM_RES_MASK);

	return lrw_init_table(&ctx->table, tweak);
}

struct sinfo {
	be128 t;
	struct crypto_tfm *tfm;
	void (*fn)(struct crypto_tfm *, u8 *, const u8 *);
};

static inline void inc(be128 *iv)
{
	be64_add_cpu(&iv->b, 1);
	if (!iv->b)
		be64_add_cpu(&iv->a, 1);
}

static inline void lrw_round(struct sinfo *s, void *dst, const void *src)
{
	be128_xor(dst, &s->t, src);		/* PP <- T xor P */
	s->fn(s->tfm, dst, dst);		/* CC <- E(Key2,PP) */
	be128_xor(dst, dst, &s->t);		/* C <- T xor CC */
}

/* this returns the number of consequative 1 bits starting
 * from the right, get_index128(00 00 00 00 00 00 ... 00 00 10 FB) = 2 */
static inline int get_index128(be128 *block)
{
	int x;
	__be32 *p = (__be32 *) block;

	for (p += 3, x = 0; x < 128; p--, x += 32) {
		u32 val = be32_to_cpup(p);

		if (!~val)
			continue;

		return x + ffz(val);
	}

	return x;
}

static int crypt(struct blkcipher_desc *d,
		 struct blkcipher_walk *w, struct priv *ctx,
		 void (*fn)(struct crypto_tfm *, u8 *, const u8 *))
{
	int err;
	unsigned int avail;
	const int bs = LRW_BLOCK_SIZE;
	struct sinfo s = {
		.tfm = crypto_cipher_tfm(ctx->child),
		.fn = fn
	};
	be128 *iv;
	u8 *wsrc;
	u8 *wdst;

	err = blkcipher_walk_virt(d, w);
	if (!(avail = w->nbytes))
		return err;

	wsrc = w->src.virt.addr;
	wdst = w->dst.virt.addr;

	/* calculate first value of T */
	iv = (be128 *)w->iv;
	s.t = *iv;

	/* T <- I*Key2 */
	gf128mul_64k_bbe(&s.t, ctx->table.table);

	goto first;

	for (;;) {
		do {
			/* T <- I*Key2, using the optimization
			 * discussed in the specification */
			be128_xor(&s.t, &s.t,
				  &ctx->table.mulinc[get_index128(iv)]);
			inc(iv);

first:
			lrw_round(&s, wdst, wsrc);

			wsrc += bs;
			wdst += bs;
		} while ((avail -= bs) >= bs);

		err = blkcipher_walk_done(d, w, avail);
		if (!(avail = w->nbytes))
			break;

		wsrc = w->src.virt.addr;
		wdst = w->dst.virt.addr;
	}

	return err;
}

static int encrypt(struct blkcipher_desc *desc, struct scatterlist *dst,
		   struct scatterlist *src, unsigned int nbytes)
{
	struct priv *ctx = crypto_blkcipher_ctx(desc->tfm);
	struct blkcipher_walk w;

	blkcipher_walk_init(&w, dst, src, nbytes);
	return crypt(desc, &w, ctx,
		     crypto_cipher_alg(ctx->child)->cia_encrypt);
}

static int decrypt(struct blkcipher_desc *desc, struct scatterlist *dst,
		   struct scatterlist *src, unsigned int nbytes)
{
	struct priv *ctx = crypto_blkcipher_ctx(desc->tfm);
	struct blkcipher_walk w;

	blkcipher_walk_init(&w, dst, src, nbytes);
	return crypt(desc, &w, ctx,
		     crypto_cipher_alg(ctx->child)->cia_decrypt);
}

int lrw_crypt(struct blkcipher_desc *desc, struct scatterlist *sdst,
	      struct scatterlist *ssrc, unsigned int nbytes,
	      struct lrw_crypt_req *req)
{
	const unsigned int bsize = LRW_BLOCK_SIZE;
	const unsigned int max_blks = req->tbuflen / bsize;
	struct lrw_table_ctx *ctx = req->table_ctx;
	struct blkcipher_walk walk;
	unsigned int nblocks;
	be128 *iv, *src, *dst, *t;
	be128 *t_buf = req->tbuf;
	int err, i;

	BUG_ON(max_blks < 1);

	blkcipher_walk_init(&walk, sdst, ssrc, nbytes);

	err = blkcipher_walk_virt(desc, &walk);
	nbytes = walk.nbytes;
	if (!nbytes)
		return err;

	nblocks = min(walk.nbytes / bsize, max_blks);
	src = (be128 *)walk.src.virt.addr;
	dst = (be128 *)walk.dst.virt.addr;

	/* calculate first value of T */
	iv = (be128 *)walk.iv;
	t_buf[0] = *iv;

	/* T <- I*Key2 */
	gf128mul_64k_bbe(&t_buf[0], ctx->table);

	i = 0;
	goto first;

	for (;;) {
		do {
			for (i = 0; i < nblocks; i++) {
				/* T <- I*Key2, using the optimization
				 * discussed in the specification */
				be128_xor(&t_buf[i], t,
						&ctx->mulinc[get_index128(iv)]);
				inc(iv);
first:
				t = &t_buf[i];

				/* PP <- T xor P */
				be128_xor(dst + i, t, src + i);
			}

			/* CC <- E(Key2,PP) */
			req->crypt_fn(req->crypt_ctx, (u8 *)dst,
				      nblocks * bsize);

			/* C <- T xor CC */
			for (i = 0; i < nblocks; i++)
				be128_xor(dst + i, dst + i, &t_buf[i]);

			src += nblocks;
			dst += nblocks;
			nbytes -= nblocks * bsize;
			nblocks = min(nbytes / bsize, max_blks);
		} while (nblocks > 0);

		err = blkcipher_walk_done(desc, &walk, nbytes);
		nbytes = walk.nbytes;
		if (!nbytes)
			break;

		nblocks = min(nbytes / bsize, max_blks);
		src = (be128 *)walk.src.virt.addr;
		dst = (be128 *)walk.dst.virt.addr;
	}

	return err;
}
EXPORT_SYMBOL_GPL(lrw_crypt);

static int init_tfm(struct crypto_tfm *tfm)
{
	struct crypto_cipher *cipher;
	struct crypto_instance *inst = (void *)tfm->__crt_alg;
	struct crypto_spawn *spawn = crypto_instance_ctx(inst);
	struct priv *ctx = crypto_tfm_ctx(tfm);
	u32 *flags = &tfm->crt_flags;

	cipher = crypto_spawn_cipher(spawn);
	if (IS_ERR(cipher))
		return PTR_ERR(cipher);

	if (crypto_cipher_blocksize(cipher) != LRW_BLOCK_SIZE) {
		*flags |= CRYPTO_TFM_RES_BAD_BLOCK_LEN;
		crypto_free_cipher(cipher);
		return -EINVAL;
	}

	ctx->child = cipher;
	return 0;
}

static void exit_tfm(struct crypto_tfm *tfm)
{
	struct priv *ctx = crypto_tfm_ctx(tfm);

	lrw_free_table(&ctx->table);
	crypto_free_cipher(ctx->child);
}

static struct crypto_instance *alloc(struct rtattr **tb)
{
	struct crypto_instance *inst;
	struct crypto_alg *alg;
	int err;

	err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_BLKCIPHER);
	if (err)
		return ERR_PTR(err);

	alg = crypto_get_attr_alg(tb, CRYPTO_ALG_TYPE_CIPHER,
				  CRYPTO_ALG_TYPE_MASK);
	if (IS_ERR(alg))
		return ERR_CAST(alg);

	inst = crypto_alloc_instance("lrw", alg);
	if (IS_ERR(inst))
		goto out_put_alg;

	inst->alg.cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER;
	inst->alg.cra_priority = alg->cra_priority;
	inst->alg.cra_blocksize = alg->cra_blocksize;

	if (alg->cra_alignmask < 7) inst->alg.cra_alignmask = 7;
	else inst->alg.cra_alignmask = alg->cra_alignmask;
	inst->alg.cra_type = &crypto_blkcipher_type;

	if (!(alg->cra_blocksize % 4))
		inst->alg.cra_alignmask |= 3;
	inst->alg.cra_blkcipher.ivsize = alg->cra_blocksize;
	inst->alg.cra_blkcipher.min_keysize =
		alg->cra_cipher.cia_min_keysize + alg->cra_blocksize;
	inst->alg.cra_blkcipher.max_keysize =
		alg->cra_cipher.cia_max_keysize + alg->cra_blocksize;

	inst->alg.cra_ctxsize = sizeof(struct priv);

	inst->alg.cra_init = init_tfm;
	inst->alg.cra_exit = exit_tfm;

	inst->alg.cra_blkcipher.setkey = setkey;
	inst->alg.cra_blkcipher.encrypt = encrypt;
	inst->alg.cra_blkcipher.decrypt = decrypt;

out_put_alg:
	crypto_mod_put(alg);
	return inst;
}

static void free(struct crypto_instance *inst)
{
	crypto_drop_spawn(crypto_instance_ctx(inst));
	kfree(inst);
}

static struct crypto_template crypto_tmpl = {
	.name = "lrw",
	.alloc = alloc,
	.free = free,
	.module = THIS_MODULE,
};

static int __init crypto_module_init(void)
{
	return crypto_register_template(&crypto_tmpl);
}

static void __exit crypto_module_exit(void)
{
	crypto_unregister_template(&crypto_tmpl);
}

module_init(crypto_module_init);
module_exit(crypto_module_exit);

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("LRW block cipher mode");