| 1 | |
| 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/export.h>
|
| 9 | #include <linux/ieee80211.h>
|
| 10 | #include <linux/unaligned.h>
|
| 11 |
|
| 12 | struct michael_mic_ctx {
|
| 13 | u32 l, r;
|
| 14 | };
|
| 15 |
|
| 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 |
|
| 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_tid(hdr);
|
| 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 |
|
| 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 |
|
| 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 | |
| 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 | EXPORT_SYMBOL_GPL(michael_mic);
|