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 <linux/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");