1/*
2 * Copyright (C)2006 USAGI/WIDE Project
3 *
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License as published by
6 * the Free Software Foundation; either version 2 of the License, or
7 * (at your option) any later version.
8 *
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
12 * GNU General Public License for more details.
13 *
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, write to the Free Software
16 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
17 *
18 * Author:
19 * 	Kazunori Miyazawa <miyazawa@linux-ipv6.org>
20 */
21
22#include <crypto/internal/hash.h>
23#include <linux/err.h>
24#include <linux/kernel.h>
25
26static u_int32_t ks[12] = {0x01010101, 0x01010101, 0x01010101, 0x01010101,
27			   0x02020202, 0x02020202, 0x02020202, 0x02020202,
28			   0x03030303, 0x03030303, 0x03030303, 0x03030303};
29
30/*
31 * +------------------------
32 * | <parent tfm>
33 * +------------------------
34 * | xcbc_tfm_ctx
35 * +------------------------
36 * | consts (block size * 2)
37 * +------------------------
38 */
39struct xcbc_tfm_ctx {
40	struct crypto_cipher *child;
41	u8 ctx[];
42};
43
44/*
45 * +------------------------
46 * | <shash desc>
47 * +------------------------
48 * | xcbc_desc_ctx
49 * +------------------------
50 * | odds (block size)
51 * +------------------------
52 * | prev (block size)
53 * +------------------------
54 */
55struct xcbc_desc_ctx {
56	unsigned int len;
57	u8 ctx[];
58};
59
60static int crypto_xcbc_digest_setkey(struct crypto_shash *parent,
61				     const u8 *inkey, unsigned int keylen)
62{
63	unsigned long alignmask = crypto_shash_alignmask(parent);
64	struct xcbc_tfm_ctx *ctx = crypto_shash_ctx(parent);
65	int bs = crypto_shash_blocksize(parent);
66	u8 *consts = PTR_ALIGN(&ctx->ctx[0], alignmask + 1);
67	int err = 0;
68	u8 key1[bs];
69
70	if ((err = crypto_cipher_setkey(ctx->child, inkey, keylen)))
71		return err;
72
73	crypto_cipher_encrypt_one(ctx->child, consts, (u8 *)ks + bs);
74	crypto_cipher_encrypt_one(ctx->child, consts + bs, (u8 *)ks + bs * 2);
75	crypto_cipher_encrypt_one(ctx->child, key1, (u8 *)ks);
76
77	return crypto_cipher_setkey(ctx->child, key1, bs);
78
79}
80
81static int crypto_xcbc_digest_init(struct shash_desc *pdesc)
82{
83	unsigned long alignmask = crypto_shash_alignmask(pdesc->tfm);
84	struct xcbc_desc_ctx *ctx = shash_desc_ctx(pdesc);
85	int bs = crypto_shash_blocksize(pdesc->tfm);
86	u8 *prev = PTR_ALIGN(&ctx->ctx[0], alignmask + 1) + bs;
87
88	ctx->len = 0;
89	memset(prev, 0, bs);
90
91	return 0;
92}
93
94static int crypto_xcbc_digest_update(struct shash_desc *pdesc, const u8 *p,
95				     unsigned int len)
96{
97	struct crypto_shash *parent = pdesc->tfm;
98	unsigned long alignmask = crypto_shash_alignmask(parent);
99	struct xcbc_tfm_ctx *tctx = crypto_shash_ctx(parent);
100	struct xcbc_desc_ctx *ctx = shash_desc_ctx(pdesc);
101	struct crypto_cipher *tfm = tctx->child;
102	int bs = crypto_shash_blocksize(parent);
103	u8 *odds = PTR_ALIGN(&ctx->ctx[0], alignmask + 1);
104	u8 *prev = odds + bs;
105
106	/* checking the data can fill the block */
107	if ((ctx->len + len) <= bs) {
108		memcpy(odds + ctx->len, p, len);
109		ctx->len += len;
110		return 0;
111	}
112
113	/* filling odds with new data and encrypting it */
114	memcpy(odds + ctx->len, p, bs - ctx->len);
115	len -= bs - ctx->len;
116	p += bs - ctx->len;
117
118	crypto_xor(prev, odds, bs);
119	crypto_cipher_encrypt_one(tfm, prev, prev);
120
121	/* clearing the length */
122	ctx->len = 0;
123
124	/* encrypting the rest of data */
125	while (len > bs) {
126		crypto_xor(prev, p, bs);
127		crypto_cipher_encrypt_one(tfm, prev, prev);
128		p += bs;
129		len -= bs;
130	}
131
132	/* keeping the surplus of blocksize */
133	if (len) {
134		memcpy(odds, p, len);
135		ctx->len = len;
136	}
137
138	return 0;
139}
140
141static int crypto_xcbc_digest_final(struct shash_desc *pdesc, u8 *out)
142{
143	struct crypto_shash *parent = pdesc->tfm;
144	unsigned long alignmask = crypto_shash_alignmask(parent);
145	struct xcbc_tfm_ctx *tctx = crypto_shash_ctx(parent);
146	struct xcbc_desc_ctx *ctx = shash_desc_ctx(pdesc);
147	struct crypto_cipher *tfm = tctx->child;
148	int bs = crypto_shash_blocksize(parent);
149	u8 *consts = PTR_ALIGN(&tctx->ctx[0], alignmask + 1);
150	u8 *odds = PTR_ALIGN(&ctx->ctx[0], alignmask + 1);
151	u8 *prev = odds + bs;
152	unsigned int offset = 0;
153
154	if (ctx->len != bs) {
155		unsigned int rlen;
156		u8 *p = odds + ctx->len;
157
158		*p = 0x80;
159		p++;
160
161		rlen = bs - ctx->len -1;
162		if (rlen)
163			memset(p, 0, rlen);
164
165		offset += bs;
166	}
167
168	crypto_xor(prev, odds, bs);
169	crypto_xor(prev, consts + offset, bs);
170
171	crypto_cipher_encrypt_one(tfm, out, prev);
172
173	return 0;
174}
175
176static int xcbc_init_tfm(struct crypto_tfm *tfm)
177{
178	struct crypto_cipher *cipher;
179	struct crypto_instance *inst = (void *)tfm->__crt_alg;
180	struct crypto_spawn *spawn = crypto_instance_ctx(inst);
181	struct xcbc_tfm_ctx *ctx = crypto_tfm_ctx(tfm);
182
183	cipher = crypto_spawn_cipher(spawn);
184	if (IS_ERR(cipher))
185		return PTR_ERR(cipher);
186
187	ctx->child = cipher;
188
189	return 0;
190};
191
192static void xcbc_exit_tfm(struct crypto_tfm *tfm)
193{
194	struct xcbc_tfm_ctx *ctx = crypto_tfm_ctx(tfm);
195	crypto_free_cipher(ctx->child);
196}
197
198static int xcbc_create(struct crypto_template *tmpl, struct rtattr **tb)
199{
200	struct shash_instance *inst;
201	struct crypto_alg *alg;
202	unsigned long alignmask;
203	int err;
204
205	err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_SHASH);
206	if (err)
207		return err;
208
209	alg = crypto_get_attr_alg(tb, CRYPTO_ALG_TYPE_CIPHER,
210				  CRYPTO_ALG_TYPE_MASK);
211	if (IS_ERR(alg))
212		return PTR_ERR(alg);
213
214	switch(alg->cra_blocksize) {
215	case 16:
216		break;
217	default:
218		goto out_put_alg;
219	}
220
221	inst = shash_alloc_instance("xcbc", alg);
222	err = PTR_ERR(inst);
223	if (IS_ERR(inst))
224		goto out_put_alg;
225
226	err = crypto_init_spawn(shash_instance_ctx(inst), alg,
227				shash_crypto_instance(inst),
228				CRYPTO_ALG_TYPE_MASK);
229	if (err)
230		goto out_free_inst;
231
232	alignmask = alg->cra_alignmask | 3;
233	inst->alg.base.cra_alignmask = alignmask;
234	inst->alg.base.cra_priority = alg->cra_priority;
235	inst->alg.base.cra_blocksize = alg->cra_blocksize;
236
237	inst->alg.digestsize = alg->cra_blocksize;
238	inst->alg.descsize = ALIGN(sizeof(struct xcbc_desc_ctx),
239				   crypto_tfm_ctx_alignment()) +
240			     (alignmask &
241			      ~(crypto_tfm_ctx_alignment() - 1)) +
242			     alg->cra_blocksize * 2;
243
244	inst->alg.base.cra_ctxsize = ALIGN(sizeof(struct xcbc_tfm_ctx),
245					   alignmask + 1) +
246				     alg->cra_blocksize * 2;
247	inst->alg.base.cra_init = xcbc_init_tfm;
248	inst->alg.base.cra_exit = xcbc_exit_tfm;
249
250	inst->alg.init = crypto_xcbc_digest_init;
251	inst->alg.update = crypto_xcbc_digest_update;
252	inst->alg.final = crypto_xcbc_digest_final;
253	inst->alg.setkey = crypto_xcbc_digest_setkey;
254
255	err = shash_register_instance(tmpl, inst);
256	if (err) {
257out_free_inst:
258		shash_free_instance(shash_crypto_instance(inst));
259	}
260
261out_put_alg:
262	crypto_mod_put(alg);
263	return err;
264}
265
266static struct crypto_template crypto_xcbc_tmpl = {
267	.name = "xcbc",
268	.create = xcbc_create,
269	.free = shash_free_instance,
270	.module = THIS_MODULE,
271};
272
273static int __init crypto_xcbc_module_init(void)
274{
275	return crypto_register_template(&crypto_xcbc_tmpl);
276}
277
278static void __exit crypto_xcbc_module_exit(void)
279{
280	crypto_unregister_template(&crypto_xcbc_tmpl);
281}
282
283module_init(crypto_xcbc_module_init);
284module_exit(crypto_xcbc_module_exit);
285
286MODULE_LICENSE("GPL");
287MODULE_DESCRIPTION("XCBC keyed hash algorithm");
288