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/byteorder.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 u8 pending[4];
23 size_t pending_len;
24
25 u32 l, r;
26 };
27
xswap(u32 val)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
michael_init(struct shash_desc * desc)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
michael_update(struct shash_desc * desc,const u8 * data,unsigned int len)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 const __le32 *src;
64
65 if (mctx->pending_len) {
66 int flen = 4 - mctx->pending_len;
67 if (flen > len)
68 flen = len;
69 memcpy(&mctx->pending[mctx->pending_len], data, flen);
70 mctx->pending_len += flen;
71 data += flen;
72 len -= flen;
73
74 if (mctx->pending_len < 4)
75 return 0;
76
77 src = (const __le32 *)mctx->pending;
78 mctx->l ^= le32_to_cpup(src);
79 michael_block(mctx->l, mctx->r);
80 mctx->pending_len = 0;
81 }
82
83 src = (const __le32 *)data;
84
85 while (len >= 4) {
86 mctx->l ^= le32_to_cpup(src++);
87 michael_block(mctx->l, mctx->r);
88 len -= 4;
89 }
90
91 if (len > 0) {
92 mctx->pending_len = len;
93 memcpy(mctx->pending, src, len);
94 }
95
96 return 0;
97 }
98
99
michael_final(struct shash_desc * desc,u8 * out)100 static int michael_final(struct shash_desc *desc, u8 *out)
101 {
102 struct michael_mic_desc_ctx *mctx = shash_desc_ctx(desc);
103 u8 *data = mctx->pending;
104 __le32 *dst = (__le32 *)out;
105
106 /* Last block and padding (0x5a, 4..7 x 0) */
107 switch (mctx->pending_len) {
108 case 0:
109 mctx->l ^= 0x5a;
110 break;
111 case 1:
112 mctx->l ^= data[0] | 0x5a00;
113 break;
114 case 2:
115 mctx->l ^= data[0] | (data[1] << 8) | 0x5a0000;
116 break;
117 case 3:
118 mctx->l ^= data[0] | (data[1] << 8) | (data[2] << 16) |
119 0x5a000000;
120 break;
121 }
122 michael_block(mctx->l, mctx->r);
123 /* l ^= 0; */
124 michael_block(mctx->l, mctx->r);
125
126 dst[0] = cpu_to_le32(mctx->l);
127 dst[1] = cpu_to_le32(mctx->r);
128
129 return 0;
130 }
131
132
michael_setkey(struct crypto_shash * tfm,const u8 * key,unsigned int keylen)133 static int michael_setkey(struct crypto_shash *tfm, const u8 *key,
134 unsigned int keylen)
135 {
136 struct michael_mic_ctx *mctx = crypto_shash_ctx(tfm);
137
138 const __le32 *data = (const __le32 *)key;
139
140 if (keylen != 8) {
141 crypto_shash_set_flags(tfm, CRYPTO_TFM_RES_BAD_KEY_LEN);
142 return -EINVAL;
143 }
144
145 mctx->l = le32_to_cpu(data[0]);
146 mctx->r = le32_to_cpu(data[1]);
147 return 0;
148 }
149
150 static struct shash_alg alg = {
151 .digestsize = 8,
152 .setkey = michael_setkey,
153 .init = michael_init,
154 .update = michael_update,
155 .final = michael_final,
156 .descsize = sizeof(struct michael_mic_desc_ctx),
157 .base = {
158 .cra_name = "michael_mic",
159 .cra_driver_name = "michael_mic-generic",
160 .cra_blocksize = 8,
161 .cra_alignmask = 3,
162 .cra_ctxsize = sizeof(struct michael_mic_ctx),
163 .cra_module = THIS_MODULE,
164 }
165 };
166
michael_mic_init(void)167 static int __init michael_mic_init(void)
168 {
169 return crypto_register_shash(&alg);
170 }
171
172
michael_mic_exit(void)173 static void __exit michael_mic_exit(void)
174 {
175 crypto_unregister_shash(&alg);
176 }
177
178
179 subsys_initcall(michael_mic_init);
180 module_exit(michael_mic_exit);
181
182 MODULE_LICENSE("GPL v2");
183 MODULE_DESCRIPTION("Michael MIC");
184 MODULE_AUTHOR("Jouni Malinen <j@w1.fi>");
185 MODULE_ALIAS_CRYPTO("michael_mic");
186