tkip.c revision c801242c38de247d82f12f6bf28bd19a280a12ae
1/*
2 * Copyright 2002-2004, Instant802 Networks, Inc.
3 * Copyright 2005, Devicescape Software, 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/kernel.h>
10#include <linux/bitops.h>
11#include <linux/types.h>
12#include <linux/netdevice.h>
13#include <asm/unaligned.h>
14
15#include <net/mac80211.h>
16#include "key.h"
17#include "tkip.h"
18#include "wep.h"
19
20#define PHASE1_LOOP_COUNT 8
21
22/*
23 * 2-byte by 2-byte subset of the full AES S-box table; second part of this
24 * table is identical to first part but byte-swapped
25 */
26static const u16 tkip_sbox[256] =
27{
28	0xC6A5, 0xF884, 0xEE99, 0xF68D, 0xFF0D, 0xD6BD, 0xDEB1, 0x9154,
29	0x6050, 0x0203, 0xCEA9, 0x567D, 0xE719, 0xB562, 0x4DE6, 0xEC9A,
30	0x8F45, 0x1F9D, 0x8940, 0xFA87, 0xEF15, 0xB2EB, 0x8EC9, 0xFB0B,
31	0x41EC, 0xB367, 0x5FFD, 0x45EA, 0x23BF, 0x53F7, 0xE496, 0x9B5B,
32	0x75C2, 0xE11C, 0x3DAE, 0x4C6A, 0x6C5A, 0x7E41, 0xF502, 0x834F,
33	0x685C, 0x51F4, 0xD134, 0xF908, 0xE293, 0xAB73, 0x6253, 0x2A3F,
34	0x080C, 0x9552, 0x4665, 0x9D5E, 0x3028, 0x37A1, 0x0A0F, 0x2FB5,
35	0x0E09, 0x2436, 0x1B9B, 0xDF3D, 0xCD26, 0x4E69, 0x7FCD, 0xEA9F,
36	0x121B, 0x1D9E, 0x5874, 0x342E, 0x362D, 0xDCB2, 0xB4EE, 0x5BFB,
37	0xA4F6, 0x764D, 0xB761, 0x7DCE, 0x527B, 0xDD3E, 0x5E71, 0x1397,
38	0xA6F5, 0xB968, 0x0000, 0xC12C, 0x4060, 0xE31F, 0x79C8, 0xB6ED,
39	0xD4BE, 0x8D46, 0x67D9, 0x724B, 0x94DE, 0x98D4, 0xB0E8, 0x854A,
40	0xBB6B, 0xC52A, 0x4FE5, 0xED16, 0x86C5, 0x9AD7, 0x6655, 0x1194,
41	0x8ACF, 0xE910, 0x0406, 0xFE81, 0xA0F0, 0x7844, 0x25BA, 0x4BE3,
42	0xA2F3, 0x5DFE, 0x80C0, 0x058A, 0x3FAD, 0x21BC, 0x7048, 0xF104,
43	0x63DF, 0x77C1, 0xAF75, 0x4263, 0x2030, 0xE51A, 0xFD0E, 0xBF6D,
44	0x814C, 0x1814, 0x2635, 0xC32F, 0xBEE1, 0x35A2, 0x88CC, 0x2E39,
45	0x9357, 0x55F2, 0xFC82, 0x7A47, 0xC8AC, 0xBAE7, 0x322B, 0xE695,
46	0xC0A0, 0x1998, 0x9ED1, 0xA37F, 0x4466, 0x547E, 0x3BAB, 0x0B83,
47	0x8CCA, 0xC729, 0x6BD3, 0x283C, 0xA779, 0xBCE2, 0x161D, 0xAD76,
48	0xDB3B, 0x6456, 0x744E, 0x141E, 0x92DB, 0x0C0A, 0x486C, 0xB8E4,
49	0x9F5D, 0xBD6E, 0x43EF, 0xC4A6, 0x39A8, 0x31A4, 0xD337, 0xF28B,
50	0xD532, 0x8B43, 0x6E59, 0xDAB7, 0x018C, 0xB164, 0x9CD2, 0x49E0,
51	0xD8B4, 0xACFA, 0xF307, 0xCF25, 0xCAAF, 0xF48E, 0x47E9, 0x1018,
52	0x6FD5, 0xF088, 0x4A6F, 0x5C72, 0x3824, 0x57F1, 0x73C7, 0x9751,
53	0xCB23, 0xA17C, 0xE89C, 0x3E21, 0x96DD, 0x61DC, 0x0D86, 0x0F85,
54	0xE090, 0x7C42, 0x71C4, 0xCCAA, 0x90D8, 0x0605, 0xF701, 0x1C12,
55	0xC2A3, 0x6A5F, 0xAEF9, 0x69D0, 0x1791, 0x9958, 0x3A27, 0x27B9,
56	0xD938, 0xEB13, 0x2BB3, 0x2233, 0xD2BB, 0xA970, 0x0789, 0x33A7,
57	0x2DB6, 0x3C22, 0x1592, 0xC920, 0x8749, 0xAAFF, 0x5078, 0xA57A,
58	0x038F, 0x59F8, 0x0980, 0x1A17, 0x65DA, 0xD731, 0x84C6, 0xD0B8,
59	0x82C3, 0x29B0, 0x5A77, 0x1E11, 0x7BCB, 0xA8FC, 0x6DD6, 0x2C3A,
60};
61
62static u16 tkipS(u16 val)
63{
64	return tkip_sbox[val & 0xff] ^ swab16(tkip_sbox[val >> 8]);
65}
66
67static u8 *write_tkip_iv(u8 *pos, u16 iv16)
68{
69	*pos++ = iv16 >> 8;
70	*pos++ = ((iv16 >> 8) | 0x20) & 0x7f;
71	*pos++ = iv16 & 0xFF;
72	return pos;
73}
74
75
76/*
77 * P1K := Phase1(TA, TK, TSC)
78 * TA = transmitter address (48 bits)
79 * TK = dot11DefaultKeyValue or dot11KeyMappingValue (128 bits)
80 * TSC = TKIP sequence counter (48 bits, only 32 msb bits used)
81 * P1K: 80 bits
82 */
83static void tkip_mixing_phase1(struct ieee80211_key *key, const u8 *ta,
84			       struct tkip_ctx *ctx, u32 tsc_IV32)
85{
86	int i, j;
87	const u8 *tk = &key->conf.key[ALG_TKIP_TEMP_ENCR_KEY];
88	u16 *p1k = ctx->p1k;
89
90	p1k[0] = tsc_IV32 & 0xFFFF;
91	p1k[1] = tsc_IV32 >> 16;
92	p1k[2] = get_unaligned_le16(ta + 0);
93	p1k[3] = get_unaligned_le16(ta + 2);
94	p1k[4] = get_unaligned_le16(ta + 4);
95
96	for (i = 0; i < PHASE1_LOOP_COUNT; i++) {
97		j = 2 * (i & 1);
98		p1k[0] += tkipS(p1k[4] ^ get_unaligned_le16(tk + 0 + j));
99		p1k[1] += tkipS(p1k[0] ^ get_unaligned_le16(tk + 4 + j));
100		p1k[2] += tkipS(p1k[1] ^ get_unaligned_le16(tk + 8 + j));
101		p1k[3] += tkipS(p1k[2] ^ get_unaligned_le16(tk + 12 + j));
102		p1k[4] += tkipS(p1k[3] ^ get_unaligned_le16(tk + 0 + j)) + i;
103	}
104	ctx->initialized = 1;
105}
106
107static void tkip_mixing_phase2(struct ieee80211_key *key, struct tkip_ctx *ctx,
108			       u16 tsc_IV16, u8 *rc4key)
109{
110	u16 ppk[6];
111	const u16 *p1k = ctx->p1k;
112	const u8 *tk = &key->conf.key[ALG_TKIP_TEMP_ENCR_KEY];
113	int i;
114
115	ppk[0] = p1k[0];
116	ppk[1] = p1k[1];
117	ppk[2] = p1k[2];
118	ppk[3] = p1k[3];
119	ppk[4] = p1k[4];
120	ppk[5] = p1k[4] + tsc_IV16;
121
122	ppk[0] += tkipS(ppk[5] ^ get_unaligned_le16(tk + 0));
123	ppk[1] += tkipS(ppk[0] ^ get_unaligned_le16(tk + 2));
124	ppk[2] += tkipS(ppk[1] ^ get_unaligned_le16(tk + 4));
125	ppk[3] += tkipS(ppk[2] ^ get_unaligned_le16(tk + 6));
126	ppk[4] += tkipS(ppk[3] ^ get_unaligned_le16(tk + 8));
127	ppk[5] += tkipS(ppk[4] ^ get_unaligned_le16(tk + 10));
128	ppk[0] += ror16(ppk[5] ^ get_unaligned_le16(tk + 12), 1);
129	ppk[1] += ror16(ppk[0] ^ get_unaligned_le16(tk + 14), 1);
130	ppk[2] += ror16(ppk[1], 1);
131	ppk[3] += ror16(ppk[2], 1);
132	ppk[4] += ror16(ppk[3], 1);
133	ppk[5] += ror16(ppk[4], 1);
134
135	rc4key = write_tkip_iv(rc4key, tsc_IV16);
136	*rc4key++ = ((ppk[5] ^ get_unaligned_le16(tk)) >> 1) & 0xFF;
137
138	for (i = 0; i < 6; i++)
139		put_unaligned_le16(ppk[i], rc4key + 2 * i);
140}
141
142/* Add TKIP IV and Ext. IV at @pos. @iv0, @iv1, and @iv2 are the first octets
143 * of the IV. Returns pointer to the octet following IVs (i.e., beginning of
144 * the packet payload). */
145u8 *ieee80211_tkip_add_iv(u8 *pos, struct ieee80211_key *key, u16 iv16)
146{
147	pos = write_tkip_iv(pos, iv16);
148	*pos++ = (key->conf.keyidx << 6) | (1 << 5) /* Ext IV */;
149	put_unaligned_le32(key->u.tkip.tx.iv32, pos);
150	return pos + 4;
151}
152
153static void ieee80211_tkip_gen_rc4key(struct ieee80211_key *key, u8 *ta,
154			       u8 *rc4key)
155{
156	/* Calculate per-packet key */
157	if (key->u.tkip.tx.iv16 == 0 || !key->u.tkip.tx.initialized)
158		tkip_mixing_phase1(key, ta, &key->u.tkip.tx, key->u.tkip.tx.iv32);
159
160	tkip_mixing_phase2(key, &key->u.tkip.tx, key->u.tkip.tx.iv16, rc4key);
161}
162
163void ieee80211_get_tkip_key(struct ieee80211_key_conf *keyconf,
164			struct sk_buff *skb, enum ieee80211_tkip_key_type type,
165			u8 *outkey)
166{
167	struct ieee80211_key *key = (struct ieee80211_key *)
168			container_of(keyconf, struct ieee80211_key, conf);
169	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
170	u8 *data = (u8 *) hdr;
171	u16 fc = le16_to_cpu(hdr->frame_control);
172	int hdr_len = ieee80211_get_hdrlen(fc);
173	u8 *ta = hdr->addr2;
174	u16 iv16;
175	u32 iv32;
176
177	iv16 = data[hdr_len + 2] | (data[hdr_len] << 8);
178	iv32 = get_unaligned_le32(data + hdr_len + 4);
179
180#ifdef CONFIG_TKIP_DEBUG
181	printk(KERN_DEBUG "TKIP encrypt: iv16 = 0x%04x, iv32 = 0x%08x\n",
182			iv16, iv32);
183
184	if (iv32 != key->u.tkip.tx.iv32) {
185		printk(KERN_DEBUG "skb: iv32 = 0x%08x key: iv32 = 0x%08x\n",
186			iv32, key->u.tkip.tx.iv32);
187		printk(KERN_DEBUG "Wrap around of iv16 in the middle of a "
188			"fragmented packet\n");
189	}
190#endif /* CONFIG_TKIP_DEBUG */
191
192	/* Update the p1k only when the iv16 in the packet wraps around, this
193	 * might occur after the wrap around of iv16 in the key in case of
194	 * fragmented packets. */
195	if (iv16 == 0 || !key->u.tkip.tx.initialized)
196		tkip_mixing_phase1(key, ta, &key->u.tkip.tx, iv32);
197
198	if (type == IEEE80211_TKIP_P1_KEY) {
199		memcpy(outkey, key->u.tkip.tx.p1k, sizeof(u16) * 5);
200		return;
201	}
202
203	tkip_mixing_phase2(key, &key->u.tkip.tx, iv16, outkey);
204}
205EXPORT_SYMBOL(ieee80211_get_tkip_key);
206
207/* Encrypt packet payload with TKIP using @key. @pos is a pointer to the
208 * beginning of the buffer containing payload. This payload must include
209 * headroom of eight octets for IV and Ext. IV and taildroom of four octets
210 * for ICV. @payload_len is the length of payload (_not_ including extra
211 * headroom and tailroom). @ta is the transmitter addresses. */
212void ieee80211_tkip_encrypt_data(struct crypto_blkcipher *tfm,
213				 struct ieee80211_key *key,
214				 u8 *pos, size_t payload_len, u8 *ta)
215{
216	u8 rc4key[16];
217
218	ieee80211_tkip_gen_rc4key(key, ta, rc4key);
219	pos = ieee80211_tkip_add_iv(pos, key, key->u.tkip.tx.iv16);
220	ieee80211_wep_encrypt_data(tfm, rc4key, 16, pos, payload_len);
221}
222
223/* Decrypt packet payload with TKIP using @key. @pos is a pointer to the
224 * beginning of the buffer containing IEEE 802.11 header payload, i.e.,
225 * including IV, Ext. IV, real data, Michael MIC, ICV. @payload_len is the
226 * length of payload, including IV, Ext. IV, MIC, ICV.  */
227int ieee80211_tkip_decrypt_data(struct crypto_blkcipher *tfm,
228				struct ieee80211_key *key,
229				u8 *payload, size_t payload_len, u8 *ta,
230				u8 *ra, int only_iv, int queue,
231				u32 *out_iv32, u16 *out_iv16)
232{
233	u32 iv32;
234	u32 iv16;
235	u8 rc4key[16], keyid, *pos = payload;
236	int res;
237
238	if (payload_len < 12)
239		return -1;
240
241	iv16 = (pos[0] << 8) | pos[2];
242	keyid = pos[3];
243	iv32 = get_unaligned_le32(pos + 4);
244	pos += 8;
245#ifdef CONFIG_TKIP_DEBUG
246	{
247		int i;
248		printk(KERN_DEBUG "TKIP decrypt: data(len=%zd)", payload_len);
249		for (i = 0; i < payload_len; i++)
250			printk(" %02x", payload[i]);
251		printk("\n");
252		printk(KERN_DEBUG "TKIP decrypt: iv16=%04x iv32=%08x\n",
253		       iv16, iv32);
254	}
255#endif /* CONFIG_TKIP_DEBUG */
256
257	if (!(keyid & (1 << 5)))
258		return TKIP_DECRYPT_NO_EXT_IV;
259
260	if ((keyid >> 6) != key->conf.keyidx)
261		return TKIP_DECRYPT_INVALID_KEYIDX;
262
263	if (key->u.tkip.rx[queue].initialized &&
264	    (iv32 < key->u.tkip.rx[queue].iv32 ||
265	     (iv32 == key->u.tkip.rx[queue].iv32 &&
266	      iv16 <= key->u.tkip.rx[queue].iv16))) {
267#ifdef CONFIG_TKIP_DEBUG
268		DECLARE_MAC_BUF(mac);
269		printk(KERN_DEBUG "TKIP replay detected for RX frame from "
270		       "%s (RX IV (%04x,%02x) <= prev. IV (%04x,%02x)\n",
271		       print_mac(mac, ta),
272		       iv32, iv16, key->u.tkip.rx[queue].iv32,
273		       key->u.tkip.rx[queue].iv16);
274#endif /* CONFIG_TKIP_DEBUG */
275		return TKIP_DECRYPT_REPLAY;
276	}
277
278	if (only_iv) {
279		res = TKIP_DECRYPT_OK;
280		key->u.tkip.rx[queue].initialized = 1;
281		goto done;
282	}
283
284	if (!key->u.tkip.rx[queue].initialized ||
285	    key->u.tkip.rx[queue].iv32 != iv32) {
286		/* IV16 wrapped around - perform TKIP phase 1 */
287		tkip_mixing_phase1(key, ta, &key->u.tkip.rx[queue], iv32);
288#ifdef CONFIG_TKIP_DEBUG
289		{
290			int i;
291			DECLARE_MAC_BUF(mac);
292			printk(KERN_DEBUG "TKIP decrypt: Phase1 TA=%s"
293			       " TK=", print_mac(mac, ta));
294			for (i = 0; i < 16; i++)
295				printk("%02x ",
296				       key->conf.key[
297						ALG_TKIP_TEMP_ENCR_KEY + i]);
298			printk("\n");
299			printk(KERN_DEBUG "TKIP decrypt: P1K=");
300			for (i = 0; i < 5; i++)
301				printk("%04x ", key->u.tkip.rx[queue].p1k[i]);
302			printk("\n");
303		}
304#endif /* CONFIG_TKIP_DEBUG */
305		if (key->local->ops->update_tkip_key &&
306			key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE) {
307			u8 bcast[ETH_ALEN] =
308				{0xff, 0xff, 0xff, 0xff, 0xff, 0xff};
309			u8 *sta_addr = key->sta->addr;
310
311			if (is_multicast_ether_addr(ra))
312				sta_addr = bcast;
313
314			key->local->ops->update_tkip_key(
315				local_to_hw(key->local), &key->conf,
316				sta_addr, iv32, key->u.tkip.rx[queue].p1k);
317		}
318	}
319
320	tkip_mixing_phase2(key, &key->u.tkip.rx[queue], iv16, rc4key);
321#ifdef CONFIG_TKIP_DEBUG
322	{
323		int i;
324		printk(KERN_DEBUG "TKIP decrypt: Phase2 rc4key=");
325		for (i = 0; i < 16; i++)
326			printk("%02x ", rc4key[i]);
327		printk("\n");
328	}
329#endif /* CONFIG_TKIP_DEBUG */
330
331	res = ieee80211_wep_decrypt_data(tfm, rc4key, 16, pos, payload_len - 12);
332 done:
333	if (res == TKIP_DECRYPT_OK) {
334		/*
335		 * Record previously received IV, will be copied into the
336		 * key information after MIC verification. It is possible
337		 * that we don't catch replays of fragments but that's ok
338		 * because the Michael MIC verication will then fail.
339		 */
340		*out_iv32 = iv32;
341		*out_iv16 = iv16;
342	}
343
344	return res;
345}
346