aboutsummaryrefslogtreecommitdiff
path: root/net/mac80211/tkip.c
blob: 995f7af3d25e71cf2fc83473e1468dbd143a2fb1 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
/*
 * Copyright 2002-2004, Instant802 Networks, Inc.
 * Copyright 2005, Devicescape Software, Inc.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */
#include <linux/kernel.h>
#include <linux/bitops.h>
#include <linux/types.h>
#include <linux/netdevice.h>
#include <asm/unaligned.h>

#include <net/mac80211.h>
#include "key.h"
#include "tkip.h"
#include "wep.h"

#define PHASE1_LOOP_COUNT 8

/*
 * 2-byte by 2-byte subset of the full AES S-box table; second part of this
 * table is identical to first part but byte-swapped
 */
static const u16 tkip_sbox[256] =
{
	0xC6A5, 0xF884, 0xEE99, 0xF68D, 0xFF0D, 0xD6BD, 0xDEB1, 0x9154,
	0x6050, 0x0203, 0xCEA9, 0x567D, 0xE719, 0xB562, 0x4DE6, 0xEC9A,
	0x8F45, 0x1F9D, 0x8940, 0xFA87, 0xEF15, 0xB2EB, 0x8EC9, 0xFB0B,
	0x41EC, 0xB367, 0x5FFD, 0x45EA, 0x23BF, 0x53F7, 0xE496, 0x9B5B,
	0x75C2, 0xE11C, 0x3DAE, 0x4C6A, 0x6C5A, 0x7E41, 0xF502, 0x834F,
	0x685C, 0x51F4, 0xD134, 0xF908, 0xE293, 0xAB73, 0x6253, 0x2A3F,
	0x080C, 0x9552, 0x4665, 0x9D5E, 0x3028, 0x37A1, 0x0A0F, 0x2FB5,
	0x0E09, 0x2436, 0x1B9B, 0xDF3D, 0xCD26, 0x4E69, 0x7FCD, 0xEA9F,
	0x121B, 0x1D9E, 0x5874, 0x342E, 0x362D, 0xDCB2, 0xB4EE, 0x5BFB,
	0xA4F6, 0x764D, 0xB761, 0x7DCE, 0x527B, 0xDD3E, 0x5E71, 0x1397,
	0xA6F5, 0xB968, 0x0000, 0xC12C, 0x4060, 0xE31F, 0x79C8, 0xB6ED,
	0xD4BE, 0x8D46, 0x67D9, 0x724B, 0x94DE, 0x98D4, 0xB0E8, 0x854A,
	0xBB6B, 0xC52A, 0x4FE5, 0xED16, 0x86C5, 0x9AD7, 0x6655, 0x1194,
	0x8ACF, 0xE910, 0x0406, 0xFE81, 0xA0F0, 0x7844, 0x25BA, 0x4BE3,
	0xA2F3, 0x5DFE, 0x80C0, 0x058A, 0x3FAD, 0x21BC, 0x7048, 0xF104,
	0x63DF, 0x77C1, 0xAF75, 0x4263, 0x2030, 0xE51A, 0xFD0E, 0xBF6D,
	0x814C, 0x1814, 0x2635, 0xC32F, 0xBEE1, 0x35A2, 0x88CC, 0x2E39,
	0x9357, 0x55F2, 0xFC82, 0x7A47, 0xC8AC, 0xBAE7, 0x322B, 0xE695,
	0xC0A0, 0x1998, 0x9ED1, 0xA37F, 0x4466, 0x547E, 0x3BAB, 0x0B83,
	0x8CCA, 0xC729, 0x6BD3, 0x283C, 0xA779, 0xBCE2, 0x161D, 0xAD76,
	0xDB3B, 0x6456, 0x744E, 0x141E, 0x92DB, 0x0C0A, 0x486C, 0xB8E4,
	0x9F5D, 0xBD6E, 0x43EF, 0xC4A6, 0x39A8, 0x31A4, 0xD337, 0xF28B,
	0xD532, 0x8B43, 0x6E59, 0xDAB7, 0x018C, 0xB164, 0x9CD2, 0x49E0,
	0xD8B4, 0xACFA, 0xF307, 0xCF25, 0xCAAF, 0xF48E, 0x47E9, 0x1018,
	0x6FD5, 0xF088, 0x4A6F, 0x5C72, 0x3824, 0x57F1, 0x73C7, 0x9751,
	0xCB23, 0xA17C, 0xE89C, 0x3E21, 0x96DD, 0x61DC, 0x0D86, 0x0F85,
	0xE090, 0x7C42, 0x71C4, 0xCCAA, 0x90D8, 0x0605, 0xF701, 0x1C12,
	0xC2A3, 0x6A5F, 0xAEF9, 0x69D0, 0x1791, 0x9958, 0x3A27, 0x27B9,
	0xD938, 0xEB13, 0x2BB3, 0x2233, 0xD2BB, 0xA970, 0x0789, 0x33A7,
	0x2DB6, 0x3C22, 0x1592, 0xC920, 0x8749, 0xAAFF, 0x5078, 0xA57A,
	0x038F, 0x59F8, 0x0980, 0x1A17, 0x65DA, 0xD731, 0x84C6, 0xD0B8,
	0x82C3, 0x29B0, 0x5A77, 0x1E11, 0x7BCB, 0xA8FC, 0x6DD6, 0x2C3A,
};

static u16 tkipS(u16 val)
{
	return tkip_sbox[val & 0xff] ^ swab16(tkip_sbox[val >> 8]);
}

static u8 *write_tkip_iv(u8 *pos, u16 iv16)
{
	*pos++ = iv16 >> 8;
	*pos++ = ((iv16 >> 8) | 0x20) & 0x7f;
	*pos++ = iv16 & 0xFF;
	return pos;
}

/*
 * P1K := Phase1(TA, TK, TSC)
 * TA = transmitter address (48 bits)
 * TK = dot11DefaultKeyValue or dot11KeyMappingValue (128 bits)
 * TSC = TKIP sequence counter (48 bits, only 32 msb bits used)
 * P1K: 80 bits
 */
static void tkip_mixing_phase1(const u8 *tk, struct tkip_ctx *ctx,
			       const u8 *ta, u32 tsc_IV32)
{
	int i, j;
	u16 *p1k = ctx->p1k;

	p1k[0] = tsc_IV32 & 0xFFFF;
	p1k[1] = tsc_IV32 >> 16;
	p1k[2] = get_unaligned_le16(ta + 0);
	p1k[3] = get_unaligned_le16(ta + 2);
	p1k[4] = get_unaligned_le16(ta + 4);

	for (i = 0; i < PHASE1_LOOP_COUNT; i++) {
		j = 2 * (i & 1);
		p1k[0] += tkipS(p1k[4] ^ get_unaligned_le16(tk + 0 + j));
		p1k[1] += tkipS(p1k[0] ^ get_unaligned_le16(tk + 4 + j));
		p1k[2] += tkipS(p1k[1] ^ get_unaligned_le16(tk + 8 + j));
		p1k[3] += tkipS(p1k[2] ^ get_unaligned_le16(tk + 12 + j));
		p1k[4] += tkipS(p1k[3] ^ get_unaligned_le16(tk + 0 + j)) + i;
	}
	ctx->initialized = 1;
}

static void tkip_mixing_phase2(const u8 *tk, struct tkip_ctx *ctx,
			       u16 tsc_IV16, u8 *rc4key)
{
	u16 ppk[6];
	const u16 *p1k = ctx->p1k;
	int i;

	ppk[0] = p1k[0];
	ppk[1] = p1k[1];
	ppk[2] = p1k[2];
	ppk[3] = p1k[3];
	ppk[4] = p1k[4];
	ppk[5] = p1k[4] + tsc_IV16;

	ppk[0] += tkipS(ppk[5] ^ get_unaligned_le16(tk + 0));
	ppk[1] += tkipS(ppk[0] ^ get_unaligned_le16(tk + 2));
	ppk[2] += tkipS(ppk[1] ^ get_unaligned_le16(tk + 4));
	ppk[3] += tkipS(ppk[2] ^ get_unaligned_le16(tk + 6));
	ppk[4] += tkipS(ppk[3] ^ get_unaligned_le16(tk + 8));
	ppk[5] += tkipS(ppk[4] ^ get_unaligned_le16(tk + 10));
	ppk[0] += ror16(ppk[5] ^ get_unaligned_le16(tk + 12), 1);
	ppk[1] += ror16(ppk[0] ^ get_unaligned_le16(tk + 14), 1);
	ppk[2] += ror16(ppk[1], 1);
	ppk[3] += ror16(ppk[2], 1);
	ppk[4] += ror16(ppk[3], 1);
	ppk[5] += ror16(ppk[4], 1);

	rc4key = write_tkip_iv(rc4key, tsc_IV16);
	*rc4key++ = ((ppk[5] ^ get_unaligned_le16(tk)) >> 1) & 0xFF;

	for (i = 0; i < 6; i++)
		put_unaligned_le16(ppk[i], rc4key + 2 * i);
}

/* Add TKIP IV and Ext. IV at @pos. @iv0, @iv1, and @iv2 are the first octets
 * of the IV. Returns pointer to the octet following IVs (i.e., beginning of
 * the packet payload). */
u8 *ieee80211_tkip_add_iv(u8 *pos, struct ieee80211_key *key, u16 iv16)
{
	pos = write_tkip_iv(pos, iv16);
	*pos++ = (key->conf.keyidx << 6) | (1 << 5) /* Ext IV */;
	put_unaligned_le32(key->u.tkip.tx.iv32, pos);
	return pos + 4;
}

void ieee80211_get_tkip_key(struct ieee80211_key_conf *keyconf,
			struct sk_buff *skb, enum ieee80211_tkip_key_type type,
			u8 *outkey)
{
	struct ieee80211_key *key = (struct ieee80211_key *)
			container_of(keyconf, struct ieee80211_key, conf);
	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
	u8 *data;
	const u8 *tk;
	struct tkip_ctx *ctx;
	u16 iv16;
	u32 iv32;

	data = (u8 *)hdr + ieee80211_hdrlen(hdr->frame_control);
	iv16 = data[2] | (data[0] << 8);
	iv32 = get_unaligned_le32(&data[4]);

	tk = &key->conf.key[NL80211_TKIP_DATA_OFFSET_ENCR_KEY];
	ctx = &key->u.tkip.tx;

#ifdef CONFIG_MAC80211_TKIP_DEBUG
	printk(KERN_DEBUG "TKIP encrypt: iv16 = 0x%04x, iv32 = 0x%08x\n",
			iv16, iv32);

	if (iv32 != ctx->iv32) {
		printk(KERN_DEBUG "skb: iv32 = 0x%08x key: iv32 = 0x%08x\n",
			iv32, ctx->iv32);
		printk(KERN_DEBUG "Wrap around of iv16 in the middle of a "
			"fragmented packet\n");
	}
#endif

	/* Update the p1k only when the iv16 in the packet wraps around, this
	 * might occur after the wrap around of iv16 in the key in case of
	 * fragmented packets. */
	if (iv16 == 0 || !ctx->initialized)
		tkip_mixing_phase1(tk, ctx, hdr->addr2, iv32);

	if (type == IEEE80211_TKIP_P1_KEY) {
		memcpy(outkey, ctx->p1k, sizeof(u16) * 5);
		return;
	}

	tkip_mixing_phase2(tk, ctx, iv16, outkey);
}
EXPORT_SYMBOL(ieee80211_get_tkip_key);

/* Encrypt packet payload with TKIP using @key. @pos is a pointer to the
 * beginning of the buffer containing payload. This payload must include
 * headroom of eight octets for IV and Ext. IV and taildroom of four octets
 * for ICV. @payload_len is the length of payload (_not_ including extra
 * headroom and tailroom). @ta is the transmitter addresses. */
void ieee80211_tkip_encrypt_data(struct crypto_blkcipher *tfm,
				 struct ieee80211_key *key,
				 u8 *pos, size_t payload_len, u8 *ta)
{
	u8 rc4key[16];
	struct tkip_ctx *ctx = &key->u.tkip.tx;
	const u8 *tk = &key->conf.key[NL80211_TKIP_DATA_OFFSET_ENCR_KEY];

	/* Calculate per-packet key */
	if (ctx->iv16 == 0 || !ctx->initialized)
		tkip_mixing_phase1(tk, ctx, ta, ctx->iv32);

	tkip_mixing_phase2(tk, ctx, ctx->iv16, rc4key);

	pos = ieee80211_tkip_add_iv(pos, key, key->u.tkip.tx.iv16);
	ieee80211_wep_encrypt_data(tfm, rc4key, 16, pos, payload_len);
}

/* Decrypt packet payload with TKIP using @key. @pos is a pointer to the
 * beginning of the buffer containing IEEE 802.11 header payload, i.e.,
 * including IV, Ext. IV, real data, Michael MIC, ICV. @payload_len is the
 * length of payload, including IV, Ext. IV, MIC, ICV.  */
int ieee80211_tkip_decrypt_data(struct crypto_blkcipher *tfm,
				struct ieee80211_key *key,
				u8 *payload, size_t payload_len, u8 *ta,
				u8 *ra, int only_iv, int queue,
				u32 *out_iv32, u16 *out_iv16)
{
	u32 iv32;
	u32 iv16;
	u8 rc4key[16], keyid, *pos = payload;
	int res;
	const u8 *tk = &key->conf.key[NL80211_TKIP_DATA_OFFSET_ENCR_KEY];

	if (payload_len < 12)
		return -1;

	iv16 = (pos[0] << 8) | pos[2];
	keyid = pos[3];
	iv32 = get_unaligned_le32(pos + 4);
	pos += 8;
#ifdef CONFIG_MAC80211_TKIP_DEBUG
	{
		int i;
		printk(KERN_DEBUG "TKIP decrypt: data(len=%zd)", payload_len);
		for (i = 0; i < payload_len; i++)
			printk(" %02x", payload[i]);
		printk("\n");
		printk(KERN_DEBUG "TKIP decrypt: iv16=%04x iv32=%08x\n",
		       iv16, iv32);
	}
#endif

	if (!(keyid & (1 << 5)))
		return TKIP_DECRYPT_NO_EXT_IV;

	if ((keyid >> 6) != key->conf.keyidx)
		return TKIP_DECRYPT_INVALID_KEYIDX;

	if (key->u.tkip.rx[queue].initialized &&
	    (iv32 < key->u.tkip.rx[queue].iv32 ||
	     (iv32 == key->u.tkip.rx[queue].iv32 &&
	      iv16 <= key->u.tkip.rx[queue].iv16))) {
#ifdef CONFIG_MAC80211_TKIP_DEBUG
		DECLARE_MAC_BUF(mac);
		printk(KERN_DEBUG "TKIP replay detected for RX frame from "
		       "%s (RX IV (%04x,%02x) <= prev. IV (%04x,%02x)\n",
		       print_mac(mac, ta),
		       iv32, iv16, key->u.tkip.rx[queue].iv32,
		       key->u.tkip.rx[queue].iv16);
#endif
		return TKIP_DECRYPT_REPLAY;
	}

	if (only_iv) {
		res = TKIP_DECRYPT_OK;
		key->u.tkip.rx[queue].initialized = 1;
		goto done;
	}

	if (!key->u.tkip.rx[queue].initialized ||
	    key->u.tkip.rx[queue].iv32 != iv32) {
		/* IV16 wrapped around - perform TKIP phase 1 */
		tkip_mixing_phase1(tk, &key->u.tkip.rx[queue], ta, iv32);
#ifdef CONFIG_MAC80211_TKIP_DEBUG
		{
			int i;
			u8 key_offset = NL80211_TKIP_DATA_OFFSET_ENCR_KEY;
			DECLARE_MAC_BUF(mac);
			printk(KERN_DEBUG "TKIP decrypt: Phase1 TA=%s"
			       " TK=", print_mac(mac, ta));
			for (i = 0; i < 16; i++)
				printk("%02x ",
				       key->conf.key[key_offset + i]);
			printk("\n");
			printk(KERN_DEBUG "TKIP decrypt: P1K=");
			for (i = 0; i < 5; i++)
				printk("%04x ", key->u.tkip.rx[queue].p1k[i]);
			printk("\n");
		}
#endif
		if (key->local->ops->update_tkip_key &&
			key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE) {
			u8 bcast[ETH_ALEN] =
				{0xff, 0xff, 0xff, 0xff, 0xff, 0xff};
			u8 *sta_addr = key->sta->addr;

			if (is_multicast_ether_addr(ra))
				sta_addr = bcast;

			key->local->ops->update_tkip_key(
				local_to_hw(key->local), &key->conf,
				sta_addr, iv32, key->u.tkip.rx[queue].p1k);
		}
	}

	tkip_mixing_phase2(tk, &key->u.tkip.rx[queue], iv16, rc4key);
#ifdef CONFIG_MAC80211_TKIP_DEBUG
	{
		int i;
		printk(KERN_DEBUG "TKIP decrypt: Phase2 rc4key=");
		for (i = 0; i < 16; i++)
			printk("%02x ", rc4key[i]);
		printk("\n");
	}
#endif

	res = ieee80211_wep_decrypt_data(tfm, rc4key, 16, pos, payload_len - 12);
 done:
	if (res == TKIP_DECRYPT_OK) {
		/*
		 * Record previously received IV, will be copied into the
		 * key information after MIC verification. It is possible
		 * that we don't catch replays of fragments but that's ok
		 * because the Michael MIC verication will then fail.
		 */
		*out_iv32 = iv32;
		*out_iv16 = iv16;
	}

	return res;
}