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
michael_block(struct michael_mic_ctx * mctx,u32 val)16 static 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
michael_mic_hdr(struct michael_mic_ctx * mctx,const u8 * key,struct ieee80211_hdr * hdr)30 static 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
michael_mic(const u8 * key,struct ieee80211_hdr * hdr,const u8 * data,size_t data_len,u8 * mic)56 void 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