summaryrefslogtreecommitdiff
path: root/net/mac80211/tkip.c
blob: 96b87fc7122e93da23292f1fd91ea4a1608692cf (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
/*
 * Copyright 2002-2004, Instant802 Networks, Inc.
 * Copyright 2005, Devicescape Software, Inc.
 * Copyright (C) 2016 Intel Deutschland GmbH
 *
 * 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 <linux/export.h>
#include <asm/unaligned.h>

#include <net/mac80211.h>
#include "driver-ops.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->state = TKIP_STATE_PHASE1_DONE;
	ctx->p1k_iv32 = tsc_IV32;
}

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_conf *keyconf, u64 pn)
{
	pos = write_tkip_iv(pos, TKIP_PN_TO_IV16(pn));
	*pos++ = (keyconf->keyidx << 6) | (1 << 5) /* Ext IV */;
	put_unaligned_le32(TKIP_PN_TO_IV32(pn), pos);
	return pos + 4;
}
EXPORT_SYMBOL_GPL(ieee80211_tkip_add_iv);

static void ieee80211_compute_tkip_p1k(struct ieee80211_key *key, u32 iv32)
{
	struct ieee80211_sub_if_data *sdata = key->sdata;
	struct tkip_ctx *ctx = &key->u.tkip.tx;
	const u8 *tk = &key->conf.key[NL80211_TKIP_DATA_OFFSET_ENCR_KEY];

	lockdep_assert_held(&key->u.tkip.txlock);

	/*
	 * Update the P1K when the IV32 is different from the value it
	 * had when we last computed it (or when not initialised yet).
	 * This might flip-flop back and forth if packets are processed
	 * out-of-order due to the different ACs, but then we have to
	 * just compute the P1K more often.
	 */
	if (ctx->p1k_iv32 != iv32 || ctx->state == TKIP_STATE_NOT_INIT)
		tkip_mixing_phase1(tk, ctx, sdata->vif.addr, iv32);
}

void ieee80211_get_tkip_p1k_iv(struct ieee80211_key_conf *keyconf,
			       u32 iv32, u16 *p1k)
{
	struct ieee80211_key *key = (struct ieee80211_key *)
			container_of(keyconf, struct ieee80211_key, conf);
	struct tkip_ctx *ctx = &key->u.tkip.tx;

	spin_lock_bh(&key->u.tkip.txlock);
	ieee80211_compute_tkip_p1k(key, iv32);
	memcpy(p1k, ctx->p1k, sizeof(ctx->p1k));
	spin_unlock_bh(&key->u.tkip.txlock);
}
EXPORT_SYMBOL(ieee80211_get_tkip_p1k_iv);

void ieee80211_get_tkip_rx_p1k(struct ieee80211_key_conf *keyconf,
			       const u8 *ta, u32 iv32, u16 *p1k)
{
	const u8 *tk = &keyconf->key[NL80211_TKIP_DATA_OFFSET_ENCR_KEY];
	struct tkip_ctx ctx;

	tkip_mixing_phase1(tk, &ctx, ta, iv32);
	memcpy(p1k, ctx.p1k, sizeof(ctx.p1k));
}
EXPORT_SYMBOL(ieee80211_get_tkip_rx_p1k);

void ieee80211_get_tkip_p2k(struct ieee80211_key_conf *keyconf,
			    struct sk_buff *skb, u8 *p2k)
{
	struct ieee80211_key *key = (struct ieee80211_key *)
			container_of(keyconf, struct ieee80211_key, conf);
	const u8 *tk = &key->conf.key[NL80211_TKIP_DATA_OFFSET_ENCR_KEY];
	struct tkip_ctx *ctx = &key->u.tkip.tx;
	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
	const u8 *data = (u8 *)hdr + ieee80211_hdrlen(hdr->frame_control);
	u32 iv32 = get_unaligned_le32(&data[4]);
	u16 iv16 = data[2] | (data[0] << 8);

	spin_lock(&key->u.tkip.txlock);
	ieee80211_compute_tkip_p1k(key, iv32);
	tkip_mixing_phase2(tk, ctx, iv16, p2k);
	spin_unlock(&key->u.tkip.txlock);
}
EXPORT_SYMBOL(ieee80211_get_tkip_p2k);

/*
 * Encrypt packet payload with TKIP using @key. @pos is a pointer to the
 * beginning of the buffer containing payload. This payload must include
 * the IV/Ext.IV and space for (taildroom) four octets for ICV.
 * @payload_len is the length of payload (_not_ including IV/ICV length).
 * @ta is the transmitter addresses.
 */
int ieee80211_tkip_encrypt_data(struct arc4_ctx *ctx,
				struct ieee80211_key *key,
				struct sk_buff *skb,
				u8 *payload, size_t payload_len)
{
	u8 rc4key[16];

	ieee80211_get_tkip_p2k(&key->conf, skb, rc4key);

	return ieee80211_wep_encrypt_data(ctx, rc4key, 16,
					  payload, 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 arc4_ctx *ctx,
				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];
	struct tkip_ctx_rx *rx_ctx = &key->u.tkip.rx[queue];

	if (payload_len < 12)
		return -1;

	iv16 = (pos[0] << 8) | pos[2];
	keyid = pos[3];
	iv32 = get_unaligned_le32(pos + 4);
	pos += 8;

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

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

	if (rx_ctx->ctx.state != TKIP_STATE_NOT_INIT &&
	    (iv32 < rx_ctx->iv32 ||
	     (iv32 == rx_ctx->iv32 && iv16 <= rx_ctx->iv16)))
		return TKIP_DECRYPT_REPLAY;

	if (only_iv) {
		res = TKIP_DECRYPT_OK;
		rx_ctx->ctx.state = TKIP_STATE_PHASE1_HW_UPLOADED;
		goto done;
	}

	if (rx_ctx->ctx.state == TKIP_STATE_NOT_INIT ||
	    rx_ctx->iv32 != iv32) {
		/* IV16 wrapped around - perform TKIP phase 1 */
		tkip_mixing_phase1(tk, &rx_ctx->ctx, ta, iv32);
	}
	if (key->local->ops->update_tkip_key &&
	    key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE &&
	    rx_ctx->ctx.state != TKIP_STATE_PHASE1_HW_UPLOADED) {
		struct ieee80211_sub_if_data *sdata = key->sdata;

		if (sdata->vif.type == NL80211_IFTYPE_AP_VLAN)
			sdata = container_of(key->sdata->bss,
					struct ieee80211_sub_if_data, u.ap);
		drv_update_tkip_key(key->local, sdata, &key->conf, key->sta,
				iv32, rx_ctx->ctx.p1k);
		rx_ctx->ctx.state = TKIP_STATE_PHASE1_HW_UPLOADED;
	}

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

	res = ieee80211_wep_decrypt_data(ctx, 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;
}