1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * Copyright (C)2006 USAGI/WIDE Project
4 *
5 * Author:
6 * 	Kazunori Miyazawa <miyazawa@linux-ipv6.org>
7 */
8
9#include <crypto/internal/cipher.h>
10#include <crypto/internal/hash.h>
11#include <linux/err.h>
12#include <linux/kernel.h>
13#include <linux/module.h>
14
15static u_int32_t ks[12] = {0x01010101, 0x01010101, 0x01010101, 0x01010101,
16			   0x02020202, 0x02020202, 0x02020202, 0x02020202,
17			   0x03030303, 0x03030303, 0x03030303, 0x03030303};
18
19/*
20 * +------------------------
21 * | <parent tfm>
22 * +------------------------
23 * | xcbc_tfm_ctx
24 * +------------------------
25 * | consts (block size * 2)
26 * +------------------------
27 */
28struct xcbc_tfm_ctx {
29	struct crypto_cipher *child;
30	u8 consts[];
31};
32
33/*
34 * +------------------------
35 * | <shash desc>
36 * +------------------------
37 * | xcbc_desc_ctx
38 * +------------------------
39 * | odds (block size)
40 * +------------------------
41 * | prev (block size)
42 * +------------------------
43 */
44struct xcbc_desc_ctx {
45	unsigned int len;
46	u8 odds[];
47};
48
49#define XCBC_BLOCKSIZE	16
50
51static int crypto_xcbc_digest_setkey(struct crypto_shash *parent,
52				     const u8 *inkey, unsigned int keylen)
53{
54	struct xcbc_tfm_ctx *ctx = crypto_shash_ctx(parent);
55	u8 *consts = ctx->consts;
56	int err = 0;
57	u8 key1[XCBC_BLOCKSIZE];
58	int bs = sizeof(key1);
59
60	if ((err = crypto_cipher_setkey(ctx->child, inkey, keylen)))
61		return err;
62
63	crypto_cipher_encrypt_one(ctx->child, consts, (u8 *)ks + bs);
64	crypto_cipher_encrypt_one(ctx->child, consts + bs, (u8 *)ks + bs * 2);
65	crypto_cipher_encrypt_one(ctx->child, key1, (u8 *)ks);
66
67	return crypto_cipher_setkey(ctx->child, key1, bs);
68
69}
70
71static int crypto_xcbc_digest_init(struct shash_desc *pdesc)
72{
73	struct xcbc_desc_ctx *ctx = shash_desc_ctx(pdesc);
74	int bs = crypto_shash_blocksize(pdesc->tfm);
75	u8 *prev = &ctx->odds[bs];
76
77	ctx->len = 0;
78	memset(prev, 0, bs);
79
80	return 0;
81}
82
83static int crypto_xcbc_digest_update(struct shash_desc *pdesc, const u8 *p,
84				     unsigned int len)
85{
86	struct crypto_shash *parent = pdesc->tfm;
87	struct xcbc_tfm_ctx *tctx = crypto_shash_ctx(parent);
88	struct xcbc_desc_ctx *ctx = shash_desc_ctx(pdesc);
89	struct crypto_cipher *tfm = tctx->child;
90	int bs = crypto_shash_blocksize(parent);
91	u8 *odds = ctx->odds;
92	u8 *prev = odds + bs;
93
94	/* checking the data can fill the block */
95	if ((ctx->len + len) <= bs) {
96		memcpy(odds + ctx->len, p, len);
97		ctx->len += len;
98		return 0;
99	}
100
101	/* filling odds with new data and encrypting it */
102	memcpy(odds + ctx->len, p, bs - ctx->len);
103	len -= bs - ctx->len;
104	p += bs - ctx->len;
105
106	crypto_xor(prev, odds, bs);
107	crypto_cipher_encrypt_one(tfm, prev, prev);
108
109	/* clearing the length */
110	ctx->len = 0;
111
112	/* encrypting the rest of data */
113	while (len > bs) {
114		crypto_xor(prev, p, bs);
115		crypto_cipher_encrypt_one(tfm, prev, prev);
116		p += bs;
117		len -= bs;
118	}
119
120	/* keeping the surplus of blocksize */
121	if (len) {
122		memcpy(odds, p, len);
123		ctx->len = len;
124	}
125
126	return 0;
127}
128
129static int crypto_xcbc_digest_final(struct shash_desc *pdesc, u8 *out)
130{
131	struct crypto_shash *parent = pdesc->tfm;
132	struct xcbc_tfm_ctx *tctx = crypto_shash_ctx(parent);
133	struct xcbc_desc_ctx *ctx = shash_desc_ctx(pdesc);
134	struct crypto_cipher *tfm = tctx->child;
135	int bs = crypto_shash_blocksize(parent);
136	u8 *odds = ctx->odds;
137	u8 *prev = odds + bs;
138	unsigned int offset = 0;
139
140	if (ctx->len != bs) {
141		unsigned int rlen;
142		u8 *p = odds + ctx->len;
143
144		*p = 0x80;
145		p++;
146
147		rlen = bs - ctx->len -1;
148		if (rlen)
149			memset(p, 0, rlen);
150
151		offset += bs;
152	}
153
154	crypto_xor(prev, odds, bs);
155	crypto_xor(prev, &tctx->consts[offset], bs);
156
157	crypto_cipher_encrypt_one(tfm, out, prev);
158
159	return 0;
160}
161
162static int xcbc_init_tfm(struct crypto_tfm *tfm)
163{
164	struct crypto_cipher *cipher;
165	struct crypto_instance *inst = (void *)tfm->__crt_alg;
166	struct crypto_cipher_spawn *spawn = crypto_instance_ctx(inst);
167	struct xcbc_tfm_ctx *ctx = crypto_tfm_ctx(tfm);
168
169	cipher = crypto_spawn_cipher(spawn);
170	if (IS_ERR(cipher))
171		return PTR_ERR(cipher);
172
173	ctx->child = cipher;
174
175	return 0;
176};
177
178static void xcbc_exit_tfm(struct crypto_tfm *tfm)
179{
180	struct xcbc_tfm_ctx *ctx = crypto_tfm_ctx(tfm);
181	crypto_free_cipher(ctx->child);
182}
183
184static int xcbc_create(struct crypto_template *tmpl, struct rtattr **tb)
185{
186	struct shash_instance *inst;
187	struct crypto_cipher_spawn *spawn;
188	struct crypto_alg *alg;
189	u32 mask;
190	int err;
191
192	err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_SHASH, &mask);
193	if (err)
194		return err;
195
196	inst = kzalloc(sizeof(*inst) + sizeof(*spawn), GFP_KERNEL);
197	if (!inst)
198		return -ENOMEM;
199	spawn = shash_instance_ctx(inst);
200
201	err = crypto_grab_cipher(spawn, shash_crypto_instance(inst),
202				 crypto_attr_alg_name(tb[1]), 0, mask);
203	if (err)
204		goto err_free_inst;
205	alg = crypto_spawn_cipher_alg(spawn);
206
207	err = -EINVAL;
208	if (alg->cra_blocksize != XCBC_BLOCKSIZE)
209		goto err_free_inst;
210
211	err = crypto_inst_setname(shash_crypto_instance(inst), tmpl->name, alg);
212	if (err)
213		goto err_free_inst;
214
215	inst->alg.base.cra_priority = alg->cra_priority;
216	inst->alg.base.cra_blocksize = alg->cra_blocksize;
217	inst->alg.base.cra_ctxsize = sizeof(struct xcbc_tfm_ctx) +
218				     alg->cra_blocksize * 2;
219
220	inst->alg.digestsize = alg->cra_blocksize;
221	inst->alg.descsize = sizeof(struct xcbc_desc_ctx) +
222			     alg->cra_blocksize * 2;
223
224	inst->alg.base.cra_init = xcbc_init_tfm;
225	inst->alg.base.cra_exit = xcbc_exit_tfm;
226
227	inst->alg.init = crypto_xcbc_digest_init;
228	inst->alg.update = crypto_xcbc_digest_update;
229	inst->alg.final = crypto_xcbc_digest_final;
230	inst->alg.setkey = crypto_xcbc_digest_setkey;
231
232	inst->free = shash_free_singlespawn_instance;
233
234	err = shash_register_instance(tmpl, inst);
235	if (err) {
236err_free_inst:
237		shash_free_singlespawn_instance(inst);
238	}
239	return err;
240}
241
242static struct crypto_template crypto_xcbc_tmpl = {
243	.name = "xcbc",
244	.create = xcbc_create,
245	.module = THIS_MODULE,
246};
247
248static int __init crypto_xcbc_module_init(void)
249{
250	return crypto_register_template(&crypto_xcbc_tmpl);
251}
252
253static void __exit crypto_xcbc_module_exit(void)
254{
255	crypto_unregister_template(&crypto_xcbc_tmpl);
256}
257
258subsys_initcall(crypto_xcbc_module_init);
259module_exit(crypto_xcbc_module_exit);
260
261MODULE_LICENSE("GPL");
262MODULE_DESCRIPTION("XCBC keyed hash algorithm");
263MODULE_ALIAS_CRYPTO("xcbc");
264MODULE_IMPORT_NS(CRYPTO_INTERNAL);
265