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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/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 
 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         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 
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 
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                 return -EINVAL;
142 
143         mctx->l = le32_to_cpu(data[0]);
144         mctx->r = le32_to_cpu(data[1]);
145         return 0;
146 }
147 
148 static struct shash_alg alg = {
149         .digestsize             =       8,
150         .setkey                 =       michael_setkey,
151         .init                   =       michael_init,
152         .update                 =       michael_update,
153         .final                  =       michael_final,
154         .descsize               =       sizeof(struct michael_mic_desc_ctx),
155         .base                   =       {
156                 .cra_name               =       "michael_mic",
157                 .cra_driver_name        =       "michael_mic-generic",
158                 .cra_blocksize          =       8,
159                 .cra_alignmask          =       3,
160                 .cra_ctxsize            =       sizeof(struct michael_mic_ctx),
161                 .cra_module             =       THIS_MODULE,
162         }
163 };
164 
165 static int __init michael_mic_init(void)
166 {
167         return crypto_register_shash(&alg);
168 }
169 
170 
171 static void __exit michael_mic_exit(void)
172 {
173         crypto_unregister_shash(&alg);
174 }
175 
176 
177 subsys_initcall(michael_mic_init);
178 module_exit(michael_mic_exit);
179 
180 MODULE_LICENSE("GPL v2");
181 MODULE_DESCRIPTION("Michael MIC");
182 MODULE_AUTHOR("Jouni Malinen <j@w1.fi>");
183 MODULE_ALIAS_CRYPTO("michael_mic");
184 

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