87 lines
2.2 KiB
C
87 lines
2.2 KiB
C
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/*
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* Michael MIC implementation - optimized for TKIP MIC operations
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* Copyright 2002-2003, Instant802 Networks, Inc.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/types.h>
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#include <linux/bitops.h>
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#include <linux/ieee80211.h>
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#include <asm/unaligned.h>
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#include "michael.h"
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static void michael_block(struct michael_mic_ctx *mctx, u32 val)
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{
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mctx->l ^= val;
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mctx->r ^= rol32(mctx->l, 17);
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mctx->l += mctx->r;
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mctx->r ^= ((mctx->l & 0xff00ff00) >> 8) |
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((mctx->l & 0x00ff00ff) << 8);
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mctx->l += mctx->r;
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mctx->r ^= rol32(mctx->l, 3);
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mctx->l += mctx->r;
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mctx->r ^= ror32(mctx->l, 2);
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mctx->l += mctx->r;
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}
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static void michael_mic_hdr(struct michael_mic_ctx *mctx, const u8 *key,
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struct ieee80211_hdr *hdr)
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{
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u8 *da, *sa, tid;
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da = ieee80211_get_DA(hdr);
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sa = ieee80211_get_SA(hdr);
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if (ieee80211_is_data_qos(hdr->frame_control))
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tid = ieee80211_get_tid(hdr);
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else
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tid = 0;
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mctx->l = get_unaligned_le32(key);
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mctx->r = get_unaligned_le32(key + 4);
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/*
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* A pseudo header (DA, SA, Priority, 0, 0, 0) is used in Michael MIC
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* calculation, but it is _not_ transmitted
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*/
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michael_block(mctx, get_unaligned_le32(da));
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michael_block(mctx, get_unaligned_le16(&da[4]) |
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(get_unaligned_le16(sa) << 16));
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michael_block(mctx, get_unaligned_le32(&sa[2]));
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michael_block(mctx, tid);
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}
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void michael_mic(const u8 *key, struct ieee80211_hdr *hdr,
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const u8 *data, size_t data_len, u8 *mic)
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{
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u32 val;
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size_t block, blocks, left;
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struct michael_mic_ctx mctx;
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michael_mic_hdr(&mctx, key, hdr);
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/* Real data */
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blocks = data_len / 4;
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left = data_len % 4;
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for (block = 0; block < blocks; block++)
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michael_block(&mctx, get_unaligned_le32(&data[block * 4]));
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/* Partial block of 0..3 bytes and padding: 0x5a + 4..7 zeros to make
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* total length a multiple of 4. */
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val = 0x5a;
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while (left > 0) {
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val <<= 8;
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left--;
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val |= data[blocks * 4 + left];
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}
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michael_block(&mctx, val);
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michael_block(&mctx, 0);
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put_unaligned_le32(mctx.l, mic);
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put_unaligned_le32(mctx.r, mic + 4);
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}
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