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
17 struct michael_mic_ctx {
18 u32 l, r;
19 };
20
21 struct michael_mic_desc_ctx {
22 __le32 pending;
23 size_t pending_len;
24
25 u32 l, r;
26 };
27
28 static inline u32 xswap(u32 val)
29 {
30 return ((val & 0x00ff00ff) << 8) | ((val & 0xff00ff00) >> 8);
31 }
32
33
34 #define michael_block(l, r) \
35 do { \
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
47 static 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
59 static 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
97 static 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
129 static 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
142 static 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
158 static int __init michael_mic_init(void)
159 {
160 return crypto_register_shash(&alg);
161 }
162
163
164 static void __exit michael_mic_exit(void)
165 {
166 crypto_unregister_shash(&alg);
167 }
168
169
170 subsys_initcall(michael_mic_init);
171 module_exit(michael_mic_exit);
172
173 MODULE_LICENSE("GPL v2");
174 MODULE_DESCRIPTION("Michael MIC");
175 MODULE_AUTHOR("Jouni Malinen <j@w1.fi>");
176 MODULE_ALIAS_CRYPTO("michael_mic");
177
Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.