1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Cryptographic API
4 *
5 * Michael MIC (IEEE 802.11i/TKIP) keyed digest
6 *
7 * Copyright (c) 2004 Jouni Malinen <j@w1.fi>
8 */
9#include <crypto/internal/hash.h>
10#include <asm/unaligned.h>
11#include <linux/init.h>
12#include <linux/module.h>
13#include <linux/string.h>
14#include <linux/types.h>
15
16
17struct michael_mic_ctx {
18	u32 l, r;
19};
20
21struct michael_mic_desc_ctx {
22	__le32 pending;
23	size_t pending_len;
24
25	u32 l, r;
26};
27
28static inline u32 xswap(u32 val)
29{
30	return ((val & 0x00ff00ff) << 8) | ((val & 0xff00ff00) >> 8);
31}
32
33
34#define michael_block(l, r)	\
35do {				\
36	r ^= rol32(l, 17);	\
37	l += r;			\
38	r ^= xswap(l);		\
39	l += r;			\
40	r ^= rol32(l, 3);	\
41	l += r;			\
42	r ^= ror32(l, 2);	\
43	l += r;			\
44} while (0)
45
46
47static int michael_init(struct shash_desc *desc)
48{
49	struct michael_mic_desc_ctx *mctx = shash_desc_ctx(desc);
50	struct michael_mic_ctx *ctx = crypto_shash_ctx(desc->tfm);
51	mctx->pending_len = 0;
52	mctx->l = ctx->l;
53	mctx->r = ctx->r;
54
55	return 0;
56}
57
58
59static int michael_update(struct shash_desc *desc, const u8 *data,
60			   unsigned int len)
61{
62	struct michael_mic_desc_ctx *mctx = shash_desc_ctx(desc);
63
64	if (mctx->pending_len) {
65		int flen = 4 - mctx->pending_len;
66		if (flen > len)
67			flen = len;
68		memcpy((u8 *)&mctx->pending + mctx->pending_len, data, flen);
69		mctx->pending_len += flen;
70		data += flen;
71		len -= flen;
72
73		if (mctx->pending_len < 4)
74			return 0;
75
76		mctx->l ^= le32_to_cpu(mctx->pending);
77		michael_block(mctx->l, mctx->r);
78		mctx->pending_len = 0;
79	}
80
81	while (len >= 4) {
82		mctx->l ^= get_unaligned_le32(data);
83		michael_block(mctx->l, mctx->r);
84		data += 4;
85		len -= 4;
86	}
87
88	if (len > 0) {
89		mctx->pending_len = len;
90		memcpy(&mctx->pending, data, len);
91	}
92
93	return 0;
94}
95
96
97static int michael_final(struct shash_desc *desc, u8 *out)
98{
99	struct michael_mic_desc_ctx *mctx = shash_desc_ctx(desc);
100	u8 *data = (u8 *)&mctx->pending;
101
102	/* Last block and padding (0x5a, 4..7 x 0) */
103	switch (mctx->pending_len) {
104	case 0:
105		mctx->l ^= 0x5a;
106		break;
107	case 1:
108		mctx->l ^= data[0] | 0x5a00;
109		break;
110	case 2:
111		mctx->l ^= data[0] | (data[1] << 8) | 0x5a0000;
112		break;
113	case 3:
114		mctx->l ^= data[0] | (data[1] << 8) | (data[2] << 16) |
115			0x5a000000;
116		break;
117	}
118	michael_block(mctx->l, mctx->r);
119	/* l ^= 0; */
120	michael_block(mctx->l, mctx->r);
121
122	put_unaligned_le32(mctx->l, out);
123	put_unaligned_le32(mctx->r, out + 4);
124
125	return 0;
126}
127
128
129static int michael_setkey(struct crypto_shash *tfm, const u8 *key,
130			  unsigned int keylen)
131{
132	struct michael_mic_ctx *mctx = crypto_shash_ctx(tfm);
133
134	if (keylen != 8)
135		return -EINVAL;
136
137	mctx->l = get_unaligned_le32(key);
138	mctx->r = get_unaligned_le32(key + 4);
139	return 0;
140}
141
142static struct shash_alg alg = {
143	.digestsize		=	8,
144	.setkey			=	michael_setkey,
145	.init			=	michael_init,
146	.update			=	michael_update,
147	.final			=	michael_final,
148	.descsize		=	sizeof(struct michael_mic_desc_ctx),
149	.base			=	{
150		.cra_name		=	"michael_mic",
151		.cra_driver_name	=	"michael_mic-generic",
152		.cra_blocksize		=	8,
153		.cra_ctxsize		=	sizeof(struct michael_mic_ctx),
154		.cra_module		=	THIS_MODULE,
155	}
156};
157
158static int __init michael_mic_init(void)
159{
160	return crypto_register_shash(&alg);
161}
162
163
164static void __exit michael_mic_exit(void)
165{
166	crypto_unregister_shash(&alg);
167}
168
169
170subsys_initcall(michael_mic_init);
171module_exit(michael_mic_exit);
172
173MODULE_LICENSE("GPL v2");
174MODULE_DESCRIPTION("Michael MIC");
175MODULE_AUTHOR("Jouni Malinen <j@w1.fi>");
176MODULE_ALIAS_CRYPTO("michael_mic");
177