crypto/michael_mic.c

   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");