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 | |
13 | static 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 | |
27 | static 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 | |
53 | void 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 | |