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83 lines
2.0 KiB
83 lines
2.0 KiB
// SPDX-License-Identifier: GPL-2.0-only |
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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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#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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