hostapd/wlantest/tkip.c

/*
 * Temporal Key Integrity Protocol (TKIP)
 * Copyright (c) 2010, Jouni Malinen <j@w1.fi>
 *
 * This software may be distributed under the terms of the BSD license.
 * See README for more details.
 */

#include "utils/includes.h"

#include "utils/common.h"
#include "utils/crc32.h"
#include "common/ieee802_11_defs.h"
#include "wlantest.h"


void wep_crypt(u8 *key, u8 *buf, size_t plen);


static inline u16 RotR1(u16 val)
{
	return (val >> 1) | (val << 15);
}


static inline u8 Lo8(u16 val)
{
	return val & 0xff;
}


static inline u8 Hi8(u16 val)
{
	return val >> 8;
}


static inline u16 Lo16(u32 val)
{
	return val & 0xffff;
}


static inline u16 Hi16(u32 val)
{
	return val >> 16;
}


static inline u16 Mk16(u8 hi, u8 lo)
{
	return lo | (((u16) hi) << 8);
}


static inline u16 Mk16_le(u16 *v)
{
	return le_to_host16(*v);
}


static const u16 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 inline u16 _S_(u16 v)
{
	u16 t = Sbox[Hi8(v)];
	return Sbox[Lo8(v)] ^ ((t << 8) | (t >> 8));
}


#define PHASE1_LOOP_COUNT 8

static void tkip_mixing_phase1(u16 *TTAK, const u8 *TK, const u8 *TA, u32 IV32)
{
	int i, j;

	/* Initialize the 80-bit TTAK from TSC (IV32) and TA[0..5] */
	TTAK[0] = Lo16(IV32);
	TTAK[1] = Hi16(IV32);
	TTAK[2] = Mk16(TA[1], TA[0]);
	TTAK[3] = Mk16(TA[3], TA[2]);
	TTAK[4] = Mk16(TA[5], TA[4]);

	for (i = 0; i < PHASE1_LOOP_COUNT; i++) {
		j = 2 * (i & 1);
		TTAK[0] += _S_(TTAK[4] ^ Mk16(TK[1 + j], TK[0 + j]));
		TTAK[1] += _S_(TTAK[0] ^ Mk16(TK[5 + j], TK[4 + j]));
		TTAK[2] += _S_(TTAK[1] ^ Mk16(TK[9 + j], TK[8 + j]));
		TTAK[3] += _S_(TTAK[2] ^ Mk16(TK[13 + j], TK[12 + j]));
		TTAK[4] += _S_(TTAK[3] ^ Mk16(TK[1 + j], TK[0 + j])) + i;
	}
}


static void tkip_mixing_phase2(u8 *WEPSeed, const u8 *TK, const u16 *TTAK,
			       u16 IV16)
{
	u16 PPK[6];

	/* Step 1 - make copy of TTAK and bring in TSC */
	PPK[0] = TTAK[0];
	PPK[1] = TTAK[1];
	PPK[2] = TTAK[2];
	PPK[3] = TTAK[3];
	PPK[4] = TTAK[4];
	PPK[5] = TTAK[4] + IV16;

	/* Step 2 - 96-bit bijective mixing using S-box */
	PPK[0] += _S_(PPK[5] ^ Mk16_le((u16 *) &TK[0]));
	PPK[1] += _S_(PPK[0] ^ Mk16_le((u16 *) &TK[2]));
	PPK[2] += _S_(PPK[1] ^ Mk16_le((u16 *) &TK[4]));
	PPK[3] += _S_(PPK[2] ^ Mk16_le((u16 *) &TK[6]));
	PPK[4] += _S_(PPK[3] ^ Mk16_le((u16 *) &TK[8]));
	PPK[5] += _S_(PPK[4] ^ Mk16_le((u16 *) &TK[10]));

	PPK[0] += RotR1(PPK[5] ^ Mk16_le((u16 *) &TK[12]));
	PPK[1] += RotR1(PPK[0] ^ Mk16_le((u16 *) &TK[14]));
	PPK[2] += RotR1(PPK[1]);
	PPK[3] += RotR1(PPK[2]);
	PPK[4] += RotR1(PPK[3]);
	PPK[5] += RotR1(PPK[4]);

	/* Step 3 - bring in last of TK bits, assign 24-bit WEP IV value
	 * WEPSeed[0..2] is transmitted as WEP IV */
	WEPSeed[0] = Hi8(IV16);
	WEPSeed[1] = (Hi8(IV16) | 0x20) & 0x7F;
	WEPSeed[2] = Lo8(IV16);
	WEPSeed[3] = Lo8((PPK[5] ^ Mk16_le((u16 *) &TK[0])) >> 1);
	WPA_PUT_LE16(&WEPSeed[4], PPK[0]);
	WPA_PUT_LE16(&WEPSeed[6], PPK[1]);
	WPA_PUT_LE16(&WEPSeed[8], PPK[2]);
	WPA_PUT_LE16(&WEPSeed[10], PPK[3]);
	WPA_PUT_LE16(&WEPSeed[12], PPK[4]);
	WPA_PUT_LE16(&WEPSeed[14], PPK[5]);
}


static inline u32 rotl(u32 val, int bits)
{
	return (val << bits) | (val >> (32 - bits));
}


static inline u32 rotr(u32 val, int bits)
{
	return (val >> bits) | (val << (32 - bits));
}


static inline u32 xswap(u32 val)
{
	return ((val & 0x00ff00ff) << 8) | ((val & 0xff00ff00) >> 8);
}


#define michael_block(l, r)	\
do {				\
	r ^= rotl(l, 17);	\
	l += r;			\
	r ^= xswap(l);		\
	l += r;			\
	r ^= rotl(l, 3);	\
	l += r;			\
	r ^= rotr(l, 2);	\
	l += r;			\
} while (0)


static void michael_mic(const u8 *key, const u8 *hdr, const u8 *data,
			size_t data_len, u8 *mic)
{
	u32 l, r;
	int i, blocks, last;

	l = WPA_GET_LE32(key);
	r = WPA_GET_LE32(key + 4);

	/* Michael MIC pseudo header: DA, SA, 3 x 0, Priority */
	l ^= WPA_GET_LE32(hdr);
	michael_block(l, r);
	l ^= WPA_GET_LE32(&hdr[4]);
	michael_block(l, r);
	l ^= WPA_GET_LE32(&hdr[8]);
	michael_block(l, r);
	l ^= WPA_GET_LE32(&hdr[12]);
	michael_block(l, r);

	/* 32-bit blocks of data */
	blocks = data_len / 4;
	last = data_len % 4;
	for (i = 0; i < blocks; i++) {
		l ^= WPA_GET_LE32(&data[4 * i]);
		michael_block(l, r);
	}

	/* Last block and padding (0x5a, 4..7 x 0) */
	switch (last) {
	case 0:
		l ^= 0x5a;
		break;
	case 1:
		l ^= data[4 * i] | 0x5a00;
		break;
	case 2:
		l ^= data[4 * i] | (data[4 * i + 1] << 8) | 0x5a0000;
		break;
	case 3:
		l ^= data[4 * i] | (data[4 * i + 1] << 8) |
			(data[4 * i + 2] << 16) | 0x5a000000;
		break;
	}
	michael_block(l, r);
	/* l ^= 0; */
	michael_block(l, r);

	WPA_PUT_LE32(mic, l);
	WPA_PUT_LE32(mic + 4, r);
}


static void michael_mic_hdr(const struct ieee80211_hdr *hdr11, u8 *hdr)
{
	int hdrlen = 24;
	u16 fc = le_to_host16(hdr11->frame_control);

	switch (fc & (WLAN_FC_FROMDS | WLAN_FC_TODS)) {
	case WLAN_FC_TODS:
		os_memcpy(hdr, hdr11->addr3, ETH_ALEN); /* DA */
		os_memcpy(hdr + ETH_ALEN, hdr11->addr2, ETH_ALEN); /* SA */
		break;
	case WLAN_FC_FROMDS:
		os_memcpy(hdr, hdr11->addr1, ETH_ALEN); /* DA */
		os_memcpy(hdr + ETH_ALEN, hdr11->addr3, ETH_ALEN); /* SA */
		break;
	case WLAN_FC_FROMDS | WLAN_FC_TODS:
		os_memcpy(hdr, hdr11->addr3, ETH_ALEN); /* DA */
		os_memcpy(hdr + ETH_ALEN, hdr11 + 1, ETH_ALEN); /* SA */
		hdrlen += ETH_ALEN;
		break;
	case 0:
		os_memcpy(hdr, hdr11->addr1, ETH_ALEN); /* DA */
		os_memcpy(hdr + ETH_ALEN, hdr11->addr2, ETH_ALEN); /* SA */
		break;
	}

	if (WLAN_FC_GET_TYPE(fc) == WLAN_FC_TYPE_DATA &&
	    (WLAN_FC_GET_STYPE(fc) & 0x08)) {
		const u8 *qos = ((const u8 *) hdr11) + hdrlen;
		hdr[12] = qos[0] & 0x0f; /* priority */
	} else
		hdr[12] = 0; /* priority */

	hdr[13] = hdr[14] = hdr[15] = 0; /* reserved */
}


u8 * tkip_decrypt(const u8 *tk, const struct ieee80211_hdr *hdr,
		  const u8 *data, size_t data_len, size_t *decrypted_len,
		  enum michael_mic_result *mic_res, struct tkip_frag *frag)
{
	u16 iv16;
	u32 iv32;
	u16 ttak[5];
	u8 rc4key[16];
	u8 *plain;
	size_t plain_len;
	u32 icv, rx_icv;
	const u8 *mic_key;
	u8 michael_hdr[16];
	u8 mic[8];
	u16 fc = le_to_host16(hdr->frame_control);
	const u8 *full_payload;
	size_t full_payload_len;
	u16 sc = le_to_host16(hdr->seq_ctrl);
	u16 sn;
	u8 fn;

	if (data_len < 8 + 4)
		return NULL;

	iv16 = (data[0] << 8) | data[2];
	iv32 = WPA_GET_LE32(&data[4]);
	wpa_printf(MSG_EXCESSIVE, "TKIP decrypt: iv32=%08x iv16=%04x",
		   iv32, iv16);

	tkip_mixing_phase1(ttak, tk, hdr->addr2, iv32);
	wpa_hexdump(MSG_EXCESSIVE, "TKIP TTAK", (u8 *) ttak, sizeof(ttak));
	tkip_mixing_phase2(rc4key, tk, ttak, iv16);
	wpa_hexdump(MSG_EXCESSIVE, "TKIP RC4KEY", rc4key, sizeof(rc4key));

	plain_len = data_len - 8;
	plain = os_memdup(data + 8, plain_len);
	if (plain == NULL)
		return NULL;
	wep_crypt(rc4key, plain, plain_len);

	icv = ieee80211_crc32(plain, plain_len - 4);
	rx_icv = WPA_GET_LE32(plain + plain_len - 4);
	if (icv != rx_icv) {
		wpa_printf(MSG_INFO, "TKIP ICV mismatch in frame from " MACSTR,
			   MAC2STR(hdr->addr2));
		wpa_printf(MSG_DEBUG, "TKIP calculated ICV %08x  received ICV "
			   "%08x", icv, rx_icv);
		os_free(plain);
		return NULL;
	}
	plain_len -= 4;

	full_payload = plain;
	full_payload_len = plain_len;

	sn = WLAN_GET_SEQ_SEQ(sc);
	fn = WLAN_GET_SEQ_FRAG(sc);

	if (frag) {
		/* MSDU reassembly for Michael MIC validation */
		if (fn == 0 && (fc & WLAN_FC_MOREFRAG)) {
			/* Start of a new fragmented MSDU */
			wpabuf_free(frag->buf);
			frag->buf = NULL;
			frag->buf = wpabuf_alloc_copy(plain, plain_len);
			os_memcpy(frag->ra, hdr->addr1, ETH_ALEN);
			os_memcpy(frag->ta, hdr->addr2, ETH_ALEN);
			frag->sn = sn;
			frag->fn = 0;
		}

		if (frag->buf && (fn || (fc & WLAN_FC_MOREFRAG)) &&
		    sn == frag->sn && fn == frag->fn + 1 &&
		    ether_addr_equal(frag->ra, hdr->addr1) &&
		    ether_addr_equal(frag->ta, hdr->addr2)) {
			/* Add the next fragment */
			if (wpabuf_resize(&frag->buf, plain_len) == 0) {
				wpabuf_put_data(frag->buf, plain, plain_len);
				frag->fn = fn;
				if (!(fc & WLAN_FC_MOREFRAG)) {
					full_payload = wpabuf_head(frag->buf);
					full_payload_len =
						wpabuf_len(frag->buf);
					wpa_hexdump(MSG_MSGDUMP,
						    "TKIP reassembled full payload",
						    full_payload,
						    full_payload_len);
				}
			}
		}
	}

	if ((fc & WLAN_FC_MOREFRAG) || (fn > 0 && full_payload == plain)) {
		/* Return the decrypted fragment and do not check the
		 * Michael MIC value since no reassembled frame is available. */
		*decrypted_len = plain_len;
		if (mic_res) {
			*mic_res = MICHAEL_MIC_NOT_VERIFIED;
			return plain;
		}
	}

	if (full_payload_len < 8) {
		wpa_printf(MSG_INFO, "TKIP: Not enough room for Michael MIC "
			   "in a frame from " MACSTR, MAC2STR(hdr->addr2));
		os_free(plain);
		return NULL;
	}

	michael_mic_hdr(hdr, michael_hdr);
	mic_key = tk + ((fc & WLAN_FC_FROMDS) ? 16 : 24);
	michael_mic(mic_key, michael_hdr, full_payload, full_payload_len - 8,
		    mic);
	if (os_memcmp(mic, full_payload + full_payload_len - 8, 8) != 0) {
		wpa_printf(MSG_INFO, "TKIP: Michael MIC mismatch in a frame "
			   "from " MACSTR, MAC2STR(hdr->addr2));
		wpa_hexdump(MSG_DEBUG, "TKIP: Calculated MIC", mic, 8);
		wpa_hexdump(MSG_DEBUG, "TKIP: Received MIC",
			    full_payload + full_payload_len - 8, 8);
		if (mic_res) {
			*decrypted_len = plain_len - 8;
			*mic_res = MICHAEL_MIC_INCORRECT;
			return plain;
		}
		os_free(plain);
		return NULL;
	} else if (mic_res) {
		*mic_res = MICHAEL_MIC_OK;
	}

	*decrypted_len = plain_len - 8;
	return plain;
}


void tkip_get_pn(u8 *pn, const u8 *data)
{
	pn[0] = data[7]; /* PN5 */
	pn[1] = data[6]; /* PN4 */
	pn[2] = data[5]; /* PN3 */
	pn[3] = data[4]; /* PN2 */
	pn[4] = data[0]; /* PN1 */
	pn[5] = data[2]; /* PN0 */
}


u8 * tkip_encrypt(const u8 *tk, u8 *frame, size_t len, size_t hdrlen, u8 *qos,
		  u8 *pn, int keyid, size_t *encrypted_len)
{
	u8 michael_hdr[16];
	u8 mic[8];
	struct ieee80211_hdr *hdr;
	u16 fc;
	const u8 *mic_key;
	u8 *crypt, *pos;
	u16 iv16;
	u32 iv32;
	u16 ttak[5];
	u8 rc4key[16];

	if (len < sizeof(*hdr) || len < hdrlen)
		return NULL;
	hdr = (struct ieee80211_hdr *) frame;
	fc = le_to_host16(hdr->frame_control);

	michael_mic_hdr(hdr, michael_hdr);
	mic_key = tk + ((fc & WLAN_FC_FROMDS) ? 16 : 24);
	michael_mic(mic_key, michael_hdr, frame + hdrlen, len - hdrlen, mic);
	wpa_hexdump(MSG_EXCESSIVE, "TKIP: MIC", mic, sizeof(mic));

	iv32 = WPA_GET_BE32(pn);
	iv16 = WPA_GET_BE16(pn + 4);
	tkip_mixing_phase1(ttak, tk, hdr->addr2, iv32);
	wpa_hexdump(MSG_EXCESSIVE, "TKIP TTAK", (u8 *) ttak, sizeof(ttak));
	tkip_mixing_phase2(rc4key, tk, ttak, iv16);
	wpa_hexdump(MSG_EXCESSIVE, "TKIP RC4KEY", rc4key, sizeof(rc4key));

	crypt = os_malloc(len + 8 + sizeof(mic) + 4);
	if (crypt == NULL)
		return NULL;
	os_memcpy(crypt, frame, hdrlen);
	pos = crypt + hdrlen;
	os_memcpy(pos, rc4key, 3);
	pos += 3;
	*pos++ = keyid << 6 | BIT(5);
	*pos++ = pn[3];
	*pos++ = pn[2];
	*pos++ = pn[1];
	*pos++ = pn[0];

	os_memcpy(pos, frame + hdrlen, len - hdrlen);
	os_memcpy(pos + len - hdrlen, mic, sizeof(mic));
	WPA_PUT_LE32(pos + len - hdrlen + sizeof(mic),
		     ieee80211_crc32(pos, len - hdrlen + sizeof(mic)));
	wep_crypt(rc4key, pos, len - hdrlen + sizeof(mic) + 4);

	*encrypted_len = len + 8 + sizeof(mic) + 4;
	return crypt;
}