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 <asm/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(mctx->l, 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(mctx->l, 3);
22	mctx->l += mctx->r;
23	mctx->r ^= ror32(mctx->l, 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(hdr->frame_control))
35		tid = ieee80211_get_tid(hdr);
36	else
37		tid = 0;
38
39	mctx->l = get_unaligned_le32(key);
40	mctx->r = get_unaligned_le32(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, get_unaligned_le32(da));
47	michael_block(mctx, get_unaligned_le16(&da[4]) |
48			    (get_unaligned_le16(sa) << 16));
49	michael_block(mctx, get_unaligned_le32(&sa[2]));
50	michael_block(mctx, 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, 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, get_unaligned_le32(&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, val);
79	michael_block(&mctx, 0);
80
81	put_unaligned_le32(mctx.l, mic);
82	put_unaligned_le32(mctx.r, mic + 4);
83}
84