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
16static 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
30static 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
56void 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