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Linux/crypto/michael_mic.c

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  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 

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