1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Michael MIC implementation - optimized for TKIP MIC operations
4 * Copyright 2002-2003, Instant802 Networks, Inc.
5 */
6#include <linux/types.h>
7#include <linux/bitops.h>
8#include <linux/ieee80211.h>
9#include <linux/unaligned.h>
10
11#include "michael.h"
12
13static void michael_block(struct michael_mic_ctx *mctx, u32 val)
14{
15 mctx->l ^= val;
16 mctx->r ^= rol32(word: mctx->l, shift: 17);
17 mctx->l += mctx->r;
18 mctx->r ^= ((mctx->l & 0xff00ff00) >> 8) |
19 ((mctx->l & 0x00ff00ff) << 8);
20 mctx->l += mctx->r;
21 mctx->r ^= rol32(word: mctx->l, shift: 3);
22 mctx->l += mctx->r;
23 mctx->r ^= ror32(word: mctx->l, shift: 2);
24 mctx->l += mctx->r;
25}
26
27static void michael_mic_hdr(struct michael_mic_ctx *mctx, const u8 *key,
28 struct ieee80211_hdr *hdr)
29{
30 u8 *da, *sa, tid;
31
32 da = ieee80211_get_DA(hdr);
33 sa = ieee80211_get_SA(hdr);
34 if (ieee80211_is_data_qos(fc: hdr->frame_control))
35 tid = ieee80211_get_tid(hdr);
36 else
37 tid = 0;
38
39 mctx->l = get_unaligned_le32(p: key);
40 mctx->r = get_unaligned_le32(p: key + 4);
41
42 /*
43 * A pseudo header (DA, SA, Priority, 0, 0, 0) is used in Michael MIC
44 * calculation, but it is _not_ transmitted
45 */
46 michael_block(mctx, val: get_unaligned_le32(p: da));
47 michael_block(mctx, val: get_unaligned_le16(p: &da[4]) |
48 (get_unaligned_le16(p: sa) << 16));
49 michael_block(mctx, val: get_unaligned_le32(p: &sa[2]));
50 michael_block(mctx, val: tid);
51}
52
53void michael_mic(const u8 *key, struct ieee80211_hdr *hdr,
54 const u8 *data, size_t data_len, u8 *mic)
55{
56 u32 val;
57 size_t block, blocks, left;
58 struct michael_mic_ctx mctx;
59
60 michael_mic_hdr(mctx: &mctx, key, hdr);
61
62 /* Real data */
63 blocks = data_len / 4;
64 left = data_len % 4;
65
66 for (block = 0; block < blocks; block++)
67 michael_block(mctx: &mctx, val: get_unaligned_le32(p: &data[block * 4]));
68
69 /* Partial block of 0..3 bytes and padding: 0x5a + 4..7 zeros to make
70 * total length a multiple of 4. */
71 val = 0x5a;
72 while (left > 0) {
73 val <<= 8;
74 left--;
75 val |= data[blocks * 4 + left];
76 }
77
78 michael_block(mctx: &mctx, val);
79 michael_block(mctx: &mctx, val: 0);
80
81 put_unaligned_le32(val: mctx.l, p: mic);
82 put_unaligned_le32(val: mctx.r, p: mic + 4);
83}
84