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TOMOYO Linux Cross Reference
Linux/net/mac80211/michael.c

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  1 /*
  2  * Michael MIC implementation - optimized for TKIP MIC operations
  3  * Copyright 2002-2003, Instant802 Networks, Inc.
  4  *
  5  * This program is free software; you can redistribute it and/or modify
  6  * it under the terms of the GNU General Public License version 2 as
  7  * published by the Free Software Foundation.
  8  */
  9 #include <linux/types.h>
 10 #include <linux/bitops.h>
 11 #include <linux/ieee80211.h>
 12 #include <asm/unaligned.h>
 13 
 14 #include "michael.h"
 15 
 16 static void michael_block(struct michael_mic_ctx *mctx, u32 val)
 17 {
 18         mctx->l ^= val;
 19         mctx->r ^= rol32(mctx->l, 17);
 20         mctx->l += mctx->r;
 21         mctx->r ^= ((mctx->l & 0xff00ff00) >> 8) |
 22                    ((mctx->l & 0x00ff00ff) << 8);
 23         mctx->l += mctx->r;
 24         mctx->r ^= rol32(mctx->l, 3);
 25         mctx->l += mctx->r;
 26         mctx->r ^= ror32(mctx->l, 2);
 27         mctx->l += mctx->r;
 28 }
 29 
 30 static void michael_mic_hdr(struct michael_mic_ctx *mctx, const u8 *key,
 31                             struct ieee80211_hdr *hdr)
 32 {
 33         u8 *da, *sa, tid;
 34 
 35         da = ieee80211_get_DA(hdr);
 36         sa = ieee80211_get_SA(hdr);
 37         if (ieee80211_is_data_qos(hdr->frame_control))
 38                 tid = *ieee80211_get_qos_ctl(hdr) & IEEE80211_QOS_CTL_TID_MASK;
 39         else
 40                 tid = 0;
 41 
 42         mctx->l = get_unaligned_le32(key);
 43         mctx->r = get_unaligned_le32(key + 4);
 44 
 45         /*
 46          * A pseudo header (DA, SA, Priority, 0, 0, 0) is used in Michael MIC
 47          * calculation, but it is _not_ transmitted
 48          */
 49         michael_block(mctx, get_unaligned_le32(da));
 50         michael_block(mctx, get_unaligned_le16(&da[4]) |
 51                             (get_unaligned_le16(sa) << 16));
 52         michael_block(mctx, get_unaligned_le32(&sa[2]));
 53         michael_block(mctx, tid);
 54 }
 55 
 56 void michael_mic(const u8 *key, struct ieee80211_hdr *hdr,
 57                  const u8 *data, size_t data_len, u8 *mic)
 58 {
 59         u32 val;
 60         size_t block, blocks, left;
 61         struct michael_mic_ctx mctx;
 62 
 63         michael_mic_hdr(&mctx, key, hdr);
 64 
 65         /* Real data */
 66         blocks = data_len / 4;
 67         left = data_len % 4;
 68 
 69         for (block = 0; block < blocks; block++)
 70                 michael_block(&mctx, get_unaligned_le32(&data[block * 4]));
 71 
 72         /* Partial block of 0..3 bytes and padding: 0x5a + 4..7 zeros to make
 73          * total length a multiple of 4. */
 74         val = 0x5a;
 75         while (left > 0) {
 76                 val <<= 8;
 77                 left--;
 78                 val |= data[blocks * 4 + left];
 79         }
 80 
 81         michael_block(&mctx, val);
 82         michael_block(&mctx, 0);
 83 
 84         put_unaligned_le32(mctx.l, mic);
 85         put_unaligned_le32(mctx.r, mic + 4);
 86 }
 87 

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