[net-next-2.6.git] / net / ieee80211 / ieee80211_crypt_wep.c

/*
 * Host AP crypt: host-based WEP encryption implementation for Host AP driver
 *
 * Copyright (c) 2002-2004, Jouni Malinen <jkmaline@cc.hut.fi>
 *
 * 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. See README and COPYING for
 * more details.
 */

#include <linux/err.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/random.h>
#include <linux/skbuff.h>
#include <asm/string.h>

#include <net/ieee80211.h>

#include <linux/crypto.h>
#include <asm/scatterlist.h>
#include <linux/crc32.h>

MODULE_AUTHOR("Jouni Malinen");
MODULE_DESCRIPTION("Host AP crypt: WEP");
MODULE_LICENSE("GPL");

struct prism2_wep_data {
	u32 iv;
#define WEP_KEY_LEN 13
	u8 key[WEP_KEY_LEN + 1];
	u8 key_len;
	u8 key_idx;
	struct crypto_blkcipher *tx_tfm;
	struct crypto_blkcipher *rx_tfm;
};

static void *prism2_wep_init(int keyidx)
{
	struct prism2_wep_data *priv;

	priv = kzalloc(sizeof(*priv), GFP_ATOMIC);
	if (priv == NULL)
		goto fail;
	priv->key_idx = keyidx;

	priv->tx_tfm = crypto_alloc_blkcipher("ecb(arc4)", 0, CRYPTO_ALG_ASYNC);
	if (IS_ERR(priv->tx_tfm)) {
		printk(KERN_DEBUG "ieee80211_crypt_wep: could not allocate "
		       "crypto API arc4\n");
		priv->tfm = NULL;
		goto fail;
	}

	priv->rx_tfm = crypto_alloc_blkcipher("ecb(arc4)", 0, CRYPTO_ALG_ASYNC);
	if (IS_ERR(priv->rx_tfm)) {
		printk(KERN_DEBUG "ieee80211_crypt_wep: could not allocate "
		       "crypto API arc4\n");
		goto fail;
	}
	/* start WEP IV from a random value */
	get_random_bytes(&priv->iv, 4);

	return priv;

      fail:
	if (priv) {
		if (priv->tx_tfm)
			crypto_free_blkcipher(priv->tx_tfm);
		if (priv->rx_tfm)
			crypto_free_blkcipher(priv->rx_tfm);
		kfree(priv);
	}
	return NULL;
}

static void prism2_wep_deinit(void *priv)
{
	struct prism2_wep_data *_priv = priv;
	if (_priv) {
		if (_priv->tx_tfm)
			crypto_free_blkcipher(_priv->tx_tfm);
		if (_priv->rx_tfm)
			crypto_free_blkcipher(_priv->rx_tfm);
	}
	kfree(priv);
}

/* Add WEP IV/key info to a frame that has at least 4 bytes of headroom */
static int prism2_wep_build_iv(struct sk_buff *skb, int hdr_len,
			       u8 *key, int keylen, void *priv)
{
	struct prism2_wep_data *wep = priv;
	u32 klen, len;
	u8 *pos;
	
	if (skb_headroom(skb) < 4 || skb->len < hdr_len)
		return -1;

	len = skb->len - hdr_len;
	pos = skb_push(skb, 4);
	memmove(pos, pos + 4, hdr_len);
	pos += hdr_len;

	klen = 3 + wep->key_len;

	wep->iv++;

	/* Fluhrer, Mantin, and Shamir have reported weaknesses in the key
	 * scheduling algorithm of RC4. At least IVs (KeyByte + 3, 0xff, N)
	 * can be used to speedup attacks, so avoid using them. */
	if ((wep->iv & 0xff00) == 0xff00) {
		u8 B = (wep->iv >> 16) & 0xff;
		if (B >= 3 && B < klen)
			wep->iv += 0x0100;
	}

	/* Prepend 24-bit IV to RC4 key and TX frame */
	*pos++ = (wep->iv >> 16) & 0xff;
	*pos++ = (wep->iv >> 8) & 0xff;
	*pos++ = wep->iv & 0xff;
	*pos++ = wep->key_idx << 6;

	return 0;
}

/* Perform WEP encryption on given skb that has at least 4 bytes of headroom
 * for IV and 4 bytes of tailroom for ICV. Both IV and ICV will be transmitted,
 * so the payload length increases with 8 bytes.
 *
 * WEP frame payload: IV + TX key idx, RC4(data), ICV = RC4(CRC32(data))
 */
static int prism2_wep_encrypt(struct sk_buff *skb, int hdr_len, void *priv)
{
	struct prism2_wep_data *wep = priv;
	struct blkcipher_desc desc = { .tfm = wep->tx_tfm };
	u32 crc, klen, len;
	u8 *pos, *icv;
	struct scatterlist sg;
	u8 key[WEP_KEY_LEN + 3];

	/* other checks are in prism2_wep_build_iv */
	if (skb_tailroom(skb) < 4)
		return -1;
	
	/* add the IV to the frame */
	if (prism2_wep_build_iv(skb, hdr_len, NULL, 0, priv))
		return -1;
	
	/* Copy the IV into the first 3 bytes of the key */
	memcpy(key, skb->data + hdr_len, 3);

	/* Copy rest of the WEP key (the secret part) */
	memcpy(key + 3, wep->key, wep->key_len);
	
	len = skb->len - hdr_len - 4;
	pos = skb->data + hdr_len + 4;
	klen = 3 + wep->key_len;

	/* Append little-endian CRC32 over only the data and encrypt it to produce ICV */
	crc = ~crc32_le(~0, pos, len);
	icv = skb_put(skb, 4);
	icv[0] = crc;
	icv[1] = crc >> 8;
	icv[2] = crc >> 16;
	icv[3] = crc >> 24;

	crypto_blkcipher_setkey(wep->tx_tfm, key, klen);
	sg.page = virt_to_page(pos);
	sg.offset = offset_in_page(pos);
	sg.length = len + 4;
	return crypto_blkcipher_encrypt(&desc, &sg, &sg, len + 4);
}

/* Perform WEP decryption on given buffer. Buffer includes whole WEP part of
 * the frame: IV (4 bytes), encrypted payload (including SNAP header),
 * ICV (4 bytes). len includes both IV and ICV.
 *
 * Returns 0 if frame was decrypted successfully and ICV was correct and -1 on
 * failure. If frame is OK, IV and ICV will be removed.
 */
static int prism2_wep_decrypt(struct sk_buff *skb, int hdr_len, void *priv)
{
	struct prism2_wep_data *wep = priv;
	struct blkcipher_desc desc = { .tfm = wep->rx_tfm };
	u32 crc, klen, plen;
	u8 key[WEP_KEY_LEN + 3];
	u8 keyidx, *pos, icv[4];
	struct scatterlist sg;

	if (skb->len < hdr_len + 8)
		return -1;

	pos = skb->data + hdr_len;
	key[0] = *pos++;
	key[1] = *pos++;
	key[2] = *pos++;
	keyidx = *pos++ >> 6;
	if (keyidx != wep->key_idx)
		return -1;

	klen = 3 + wep->key_len;

	/* Copy rest of the WEP key (the secret part) */
	memcpy(key + 3, wep->key, wep->key_len);

	/* Apply RC4 to data and compute CRC32 over decrypted data */
	plen = skb->len - hdr_len - 8;

	crypto_blkcipher_setkey(wep->rx_tfm, key, klen);
	sg.page = virt_to_page(pos);
	sg.offset = offset_in_page(pos);
	sg.length = plen + 4;
	if (crypto_blkcipher_decrypt(&desc, &sg, &sg, plen + 4))
		return -7;

	crc = ~crc32_le(~0, pos, plen);
	icv[0] = crc;
	icv[1] = crc >> 8;
	icv[2] = crc >> 16;
	icv[3] = crc >> 24;
	if (memcmp(icv, pos + plen, 4) != 0) {
		/* ICV mismatch - drop frame */
		return -2;
	}

	/* Remove IV and ICV */
	memmove(skb->data + 4, skb->data, hdr_len);
	skb_pull(skb, 4);
	skb_trim(skb, skb->len - 4);

	return 0;
}

static int prism2_wep_set_key(void *key, int len, u8 * seq, void *priv)
{
	struct prism2_wep_data *wep = priv;

	if (len < 0 || len > WEP_KEY_LEN)
		return -1;

	memcpy(wep->key, key, len);
	wep->key_len = len;

	return 0;
}

static int prism2_wep_get_key(void *key, int len, u8 * seq, void *priv)
{
	struct prism2_wep_data *wep = priv;

	if (len < wep->key_len)
		return -1;

	memcpy(key, wep->key, wep->key_len);

	return wep->key_len;
}

static char *prism2_wep_print_stats(char *p, void *priv)
{
	struct prism2_wep_data *wep = priv;
	p += sprintf(p, "key[%d] alg=WEP len=%d\n", wep->key_idx, wep->key_len);
	return p;
}

static struct ieee80211_crypto_ops ieee80211_crypt_wep = {
	.name = "WEP",
	.init = prism2_wep_init,
	.deinit = prism2_wep_deinit,
	.build_iv = prism2_wep_build_iv,
	.encrypt_mpdu = prism2_wep_encrypt,
	.decrypt_mpdu = prism2_wep_decrypt,
	.encrypt_msdu = NULL,
	.decrypt_msdu = NULL,
	.set_key = prism2_wep_set_key,
	.get_key = prism2_wep_get_key,
	.print_stats = prism2_wep_print_stats,
	.extra_mpdu_prefix_len = 4,	/* IV */
	.extra_mpdu_postfix_len = 4,	/* ICV */
	.owner = THIS_MODULE,
};

static int __init ieee80211_crypto_wep_init(void)
{
	return ieee80211_register_crypto_ops(&ieee80211_crypt_wep);
}

static void __exit ieee80211_crypto_wep_exit(void)
{
	ieee80211_unregister_crypto_ops(&ieee80211_crypt_wep);
}

module_init(ieee80211_crypto_wep_init);
module_exit(ieee80211_crypto_wep_exit);
Commit	Line	Data
b453872c JG	1	/*
	2	* Host AP crypt: host-based WEP encryption implementation for Host AP driver
	3	*
	4	* Copyright (c) 2002-2004, Jouni Malinen <jkmaline@cc.hut.fi>
	5	*
	6	* This program is free software; you can redistribute it and/or modify
	7	* it under the terms of the GNU General Public License version 2 as
	8	* published by the Free Software Foundation. See README and COPYING for
	9	* more details.
	10	*/
	11
f12cc209	12	#include <linux/err.h>
b453872c JG	13	#include <linux/module.h>
	14	#include <linux/init.h>
	15	#include <linux/slab.h>
	16	#include <linux/random.h>
	17	#include <linux/skbuff.h>
	18	#include <asm/string.h>
	19
	20	#include <net/ieee80211.h>
	21
b453872c JG	22	#include <linux/crypto.h>
	23	#include <asm/scatterlist.h>
	24	#include <linux/crc32.h>
	25
	26	MODULE_AUTHOR("Jouni Malinen");
	27	MODULE_DESCRIPTION("Host AP crypt: WEP");
	28	MODULE_LICENSE("GPL");
	29
b453872c JG	30	struct prism2_wep_data {
	31	u32 iv;
	32	#define WEP_KEY_LEN 13
	33	u8 key[WEP_KEY_LEN + 1];
	34	u8 key_len;
	35	u8 key_idx;
28eb177d JG	36	struct crypto_blkcipher *tx_tfm;
28eb177d JG	37	struct crypto_blkcipher *rx_tfm;
b453872c JG	38	};
b453872c JG	39
6eb6edf0	40	static void *prism2_wep_init(int keyidx)
b453872c JG	41	{
	42	struct prism2_wep_data *priv;
	43
0da974f4	44	priv = kzalloc(sizeof(*priv), GFP_ATOMIC);
b453872c JG	45	if (priv == NULL)
b453872c JG	46	goto fail;
b453872c JG	47	priv->key_idx = keyidx;
b453872c JG	48
28eb177d JG	49	priv->tx_tfm = crypto_alloc_blkcipher("ecb(arc4)", 0, CRYPTO_ALG_ASYNC);
28eb177d JG	50	if (IS_ERR(priv->tx_tfm)) {
b453872c JG	51	printk(KERN_DEBUG "ieee80211_crypt_wep: could not allocate "
b453872c JG	52	"crypto API arc4\n");
f12cc209	53	priv->tfm = NULL;
b453872c JG	54	goto fail;
	55	}
	56
28eb177d JG	57	priv->rx_tfm = crypto_alloc_blkcipher("ecb(arc4)", 0, CRYPTO_ALG_ASYNC);
28eb177d JG	58	if (IS_ERR(priv->rx_tfm)) {
5a656949 ZY	59	printk(KERN_DEBUG "ieee80211_crypt_wep: could not allocate "
	60	"crypto API arc4\n");
	61	goto fail;
	62	}
b453872c JG	63	/* start WEP IV from a random value */
	64	get_random_bytes(&priv->iv, 4);
	65
	66	return priv;
	67
0edd5b44	68	fail:
b453872c	69	if (priv) {
5a656949	70	if (priv->tx_tfm)
28eb177d	71	crypto_free_blkcipher(priv->tx_tfm);
5a656949	72	if (priv->rx_tfm)
28eb177d	73	crypto_free_blkcipher(priv->rx_tfm);
b453872c JG	74	kfree(priv);
	75	}
	76	return NULL;
	77	}
	78
b453872c JG	79	static void prism2_wep_deinit(void *priv)
	80	{
	81	struct prism2_wep_data *_priv = priv;
5a656949 ZY	82	if (_priv) {
5a656949 ZY	83	if (_priv->tx_tfm)
28eb177d	84	crypto_free_blkcipher(_priv->tx_tfm);
5a656949	85	if (_priv->rx_tfm)
28eb177d	86	crypto_free_blkcipher(_priv->rx_tfm);
5a656949	87	}
b453872c JG	88	kfree(priv);
	89	}
	90
a4bf26f3	91	/* Add WEP IV/key info to a frame that has at least 4 bytes of headroom */
9184d934 ZY	92	static int prism2_wep_build_iv(struct sk_buff *skb, int hdr_len,
9184d934 ZY	93	u8 key, int keylen, void priv)
b453872c JG	94	{
b453872c JG	95	struct prism2_wep_data *wep = priv;
a4bf26f3 JB	96	u32 klen, len;
	97	u8 *pos;
	98
	99	if (skb_headroom(skb) < 4 \|\| skb->len < hdr_len)
b453872c JG	100	return -1;
	101
	102	len = skb->len - hdr_len;
	103	pos = skb_push(skb, 4);
	104	memmove(pos, pos + 4, hdr_len);
	105	pos += hdr_len;
	106
	107	klen = 3 + wep->key_len;
	108
	109	wep->iv++;
	110
	111	/* Fluhrer, Mantin, and Shamir have reported weaknesses in the key
	112	* scheduling algorithm of RC4. At least IVs (KeyByte + 3, 0xff, N)
	113	* can be used to speedup attacks, so avoid using them. */
	114	if ((wep->iv & 0xff00) == 0xff00) {
	115	u8 B = (wep->iv >> 16) & 0xff;
	116	if (B >= 3 && B < klen)
	117	wep->iv += 0x0100;
	118	}
	119
	120	/* Prepend 24-bit IV to RC4 key and TX frame */
a4bf26f3 JB	121	*pos++ = (wep->iv >> 16) & 0xff;
	122	*pos++ = (wep->iv >> 8) & 0xff;
	123	*pos++ = wep->iv & 0xff;
b453872c JG	124	*pos++ = wep->key_idx << 6;
b453872c JG	125
a4bf26f3 JB	126	return 0;
	127	}
	128
	129	/* Perform WEP encryption on given skb that has at least 4 bytes of headroom
	130	* for IV and 4 bytes of tailroom for ICV. Both IV and ICV will be transmitted,
	131	* so the payload length increases with 8 bytes.
	132	*
	133	* WEP frame payload: IV + TX key idx, RC4(data), ICV = RC4(CRC32(data))
	134	*/
	135	static int prism2_wep_encrypt(struct sk_buff skb, int hdr_len, void priv)
	136	{
	137	struct prism2_wep_data *wep = priv;
28eb177d	138	struct blkcipher_desc desc = { .tfm = wep->tx_tfm };
a4bf26f3 JB	139	u32 crc, klen, len;
	140	u8 pos, icv;
	141	struct scatterlist sg;
	142	u8 key[WEP_KEY_LEN + 3];
	143
	144	/* other checks are in prism2_wep_build_iv */
	145	if (skb_tailroom(skb) < 4)
	146	return -1;
	147
	148	/* add the IV to the frame */
9184d934	149	if (prism2_wep_build_iv(skb, hdr_len, NULL, 0, priv))
a4bf26f3 JB	150	return -1;
	151
	152	/* Copy the IV into the first 3 bytes of the key */
	153	memcpy(key, skb->data + hdr_len, 3);
	154
b453872c JG	155	/* Copy rest of the WEP key (the secret part) */
b453872c JG	156	memcpy(key + 3, wep->key, wep->key_len);
a4bf26f3 JB	157
	158	len = skb->len - hdr_len - 4;
	159	pos = skb->data + hdr_len + 4;
	160	klen = 3 + wep->key_len;
b453872c	161
a4bf26f3	162	/* Append little-endian CRC32 over only the data and encrypt it to produce ICV */
b453872c JG	163	crc = ~crc32_le(~0, pos, len);
	164	icv = skb_put(skb, 4);
	165	icv[0] = crc;
	166	icv[1] = crc >> 8;
	167	icv[2] = crc >> 16;
	168	icv[3] = crc >> 24;
	169
28eb177d	170	crypto_blkcipher_setkey(wep->tx_tfm, key, klen);
b453872c JG	171	sg.page = virt_to_page(pos);
	172	sg.offset = offset_in_page(pos);
	173	sg.length = len + 4;
f12cc209	174	return crypto_blkcipher_encrypt(&desc, &sg, &sg, len + 4);
b453872c JG	175	}
b453872c JG	176
b453872c JG	177	/* Perform WEP decryption on given buffer. Buffer includes whole WEP part of
	178	* the frame: IV (4 bytes), encrypted payload (including SNAP header),
	179	* ICV (4 bytes). len includes both IV and ICV.
	180	*
	181	* Returns 0 if frame was decrypted successfully and ICV was correct and -1 on
	182	* failure. If frame is OK, IV and ICV will be removed.
	183	*/
	184	static int prism2_wep_decrypt(struct sk_buff skb, int hdr_len, void priv)
	185	{
	186	struct prism2_wep_data *wep = priv;
28eb177d	187	struct blkcipher_desc desc = { .tfm = wep->rx_tfm };
b453872c JG	188	u32 crc, klen, plen;
	189	u8 key[WEP_KEY_LEN + 3];
	190	u8 keyidx, *pos, icv[4];
	191	struct scatterlist sg;
	192
	193	if (skb->len < hdr_len + 8)
	194	return -1;
	195
	196	pos = skb->data + hdr_len;
	197	key[0] = *pos++;
	198	key[1] = *pos++;
	199	key[2] = *pos++;
	200	keyidx = *pos++ >> 6;
	201	if (keyidx != wep->key_idx)
	202	return -1;
	203
	204	klen = 3 + wep->key_len;
	205
	206	/* Copy rest of the WEP key (the secret part) */
	207	memcpy(key + 3, wep->key, wep->key_len);
	208
	209	/* Apply RC4 to data and compute CRC32 over decrypted data */
	210	plen = skb->len - hdr_len - 8;
	211
28eb177d	212	crypto_blkcipher_setkey(wep->rx_tfm, key, klen);
b453872c JG	213	sg.page = virt_to_page(pos);
	214	sg.offset = offset_in_page(pos);
	215	sg.length = plen + 4;
f12cc209 HX	216	if (crypto_blkcipher_decrypt(&desc, &sg, &sg, plen + 4))
f12cc209 HX	217	return -7;
b453872c JG	218
	219	crc = ~crc32_le(~0, pos, plen);
	220	icv[0] = crc;
	221	icv[1] = crc >> 8;
	222	icv[2] = crc >> 16;
	223	icv[3] = crc >> 24;
	224	if (memcmp(icv, pos + plen, 4) != 0) {
	225	/* ICV mismatch - drop frame */
	226	return -2;
	227	}
	228
	229	/* Remove IV and ICV */
	230	memmove(skb->data + 4, skb->data, hdr_len);
	231	skb_pull(skb, 4);
	232	skb_trim(skb, skb->len - 4);
	233
	234	return 0;
	235	}
	236
0edd5b44	237	static int prism2_wep_set_key(void key, int len, u8 seq, void *priv)
b453872c JG	238	{
	239	struct prism2_wep_data *wep = priv;
	240
	241	if (len < 0 \|\| len > WEP_KEY_LEN)
	242	return -1;
	243
	244	memcpy(wep->key, key, len);
	245	wep->key_len = len;
	246
	247	return 0;
	248	}
	249
0edd5b44	250	static int prism2_wep_get_key(void key, int len, u8 seq, void *priv)
b453872c JG	251	{
	252	struct prism2_wep_data *wep = priv;
	253
	254	if (len < wep->key_len)
	255	return -1;
	256
	257	memcpy(key, wep->key, wep->key_len);
	258
	259	return wep->key_len;
	260	}
	261
0edd5b44	262	static char prism2_wep_print_stats(char p, void *priv)
b453872c JG	263	{
b453872c JG	264	struct prism2_wep_data *wep = priv;
0edd5b44	265	p += sprintf(p, "key[%d] alg=WEP len=%d\n", wep->key_idx, wep->key_len);
b453872c JG	266	return p;
	267	}
	268
b453872c	269	static struct ieee80211_crypto_ops ieee80211_crypt_wep = {
74079fdc JK	270	.name = "WEP",
	271	.init = prism2_wep_init,
	272	.deinit = prism2_wep_deinit,
a4bf26f3	273	.build_iv = prism2_wep_build_iv,
74079fdc JK	274	.encrypt_mpdu = prism2_wep_encrypt,
	275	.decrypt_mpdu = prism2_wep_decrypt,
	276	.encrypt_msdu = NULL,
	277	.decrypt_msdu = NULL,
	278	.set_key = prism2_wep_set_key,
	279	.get_key = prism2_wep_get_key,
	280	.print_stats = prism2_wep_print_stats,
1264fc04 JK	281	.extra_mpdu_prefix_len = 4, /* IV */
1264fc04 JK	282	.extra_mpdu_postfix_len = 4, /* ICV */
74079fdc	283	.owner = THIS_MODULE,
b453872c JG	284	};
b453872c JG	285
b453872c JG	286	static int __init ieee80211_crypto_wep_init(void)
	287	{
	288	return ieee80211_register_crypto_ops(&ieee80211_crypt_wep);
	289	}
	290
b453872c JG	291	static void __exit ieee80211_crypto_wep_exit(void)
	292	{
	293	ieee80211_unregister_crypto_ops(&ieee80211_crypt_wep);
	294	}
	295
b453872c JG	296	module_init(ieee80211_crypto_wep_init);
b453872c JG	297	module_exit(ieee80211_crypto_wep_exit);