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
  17struct michael_mic_ctx {
  18        u32 l, r;
  19};
  20
  21struct michael_mic_desc_ctx {
  22        __le32 pending;
  23        size_t pending_len;
  24
  25        u32 l, r;
  26};
  27
  28static inline u32 xswap(u32 val)
  29{
  30        return ((val & 0x00ff00ff) << 8) | ((val & 0xff00ff00) >> 8);
  31}
  32
  33
  34#define michael_block(l, r)     \
  35do {                            \
  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
  47static 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
  59static 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
  97static 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
 129static 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
 142static 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
 158static int __init michael_mic_init(void)
 159{
 160        return crypto_register_shash(&alg);
 161}
 162
 163
 164static void __exit michael_mic_exit(void)
 165{
 166        crypto_unregister_shash(&alg);
 167}
 168
 169
 170subsys_initcall(michael_mic_init);
 171module_exit(michael_mic_exit);
 172
 173MODULE_LICENSE("GPL v2");
 174MODULE_DESCRIPTION("Michael MIC");
 175MODULE_AUTHOR("Jouni Malinen <j@w1.fi>");
 176MODULE_ALIAS_CRYPTO("michael_mic");
 177
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