[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/config.h>
#include <linux/version.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_tfm *tfm;
};

static void *prism2_wep_init(struct ieee80211_device *ieee, int keyidx)
{
	struct prism2_wep_data *priv;

	priv = kmalloc(sizeof(*priv), GFP_ATOMIC);
	if (priv == NULL)
		goto fail;
	memset(priv, 0, sizeof(*priv));
	priv->key_idx = keyidx;

	priv->tfm = crypto_alloc_tfm("arc4", 0);
	if (priv->tfm == NULL) {
		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->tfm)
			crypto_free_tfm(priv->tfm);
		kfree(priv);
	}
	return NULL;
}

static void prism2_wep_deinit(void *priv)
{
	struct prism2_wep_data *_priv = priv;
	if (_priv && _priv->tfm)
		crypto_free_tfm(_priv->tfm);
	kfree(priv);
}

/* 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;
	u32 crc, klen, len;
	u8 key[WEP_KEY_LEN + 3];
	u8 *pos, *icv;
	struct scatterlist sg;

	if (skb_headroom(skb) < 4 || skb_tailroom(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++ = key[0] = (wep->iv >> 16) & 0xff;
	*pos++ = key[1] = (wep->iv >> 8) & 0xff;
	*pos++ = key[2] = wep->iv & 0xff;
	*pos++ = wep->key_idx << 6;

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

	/* Append little-endian CRC32 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_cipher_setkey(wep->tfm, key, klen);
	sg.page = virt_to_page(pos);
	sg.offset = offset_in_page(pos);
	sg.length = len + 4;
	crypto_cipher_encrypt(wep->tfm, &sg, &sg, len + 4);

	return 0;
}

/* 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;
	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_cipher_setkey(wep->tfm, key, klen);
	sg.page = virt_to_page(pos);
	sg.offset = offset_in_page(pos);
	sg.length = plen + 4;
	crypto_cipher_decrypt(wep->tfm, &sg, &sg, plen + 4);

	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,
	.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_prefix_len = 4,	/* IV */
	.extra_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
	12	#include <linux/config.h>
	13	#include <linux/version.h>
	14	#include <linux/module.h>
	15	#include <linux/init.h>
	16	#include <linux/slab.h>
	17	#include <linux/random.h>
	18	#include <linux/skbuff.h>
	19	#include <asm/string.h>
	20
	21	#include <net/ieee80211.h>
	22
b453872c JG	23	#include <linux/crypto.h>
	24	#include <asm/scatterlist.h>
	25	#include <linux/crc32.h>
	26
	27	MODULE_AUTHOR("Jouni Malinen");
	28	MODULE_DESCRIPTION("Host AP crypt: WEP");
	29	MODULE_LICENSE("GPL");
	30
b453872c JG	31	struct prism2_wep_data {
	32	u32 iv;
	33	#define WEP_KEY_LEN 13
	34	u8 key[WEP_KEY_LEN + 1];
	35	u8 key_len;
	36	u8 key_idx;
	37	struct crypto_tfm *tfm;
	38	};
	39
20d64713	40	static void prism2_wep_init(struct ieee80211_device ieee, int keyidx)
b453872c JG	41	{
	42	struct prism2_wep_data *priv;
	43
	44	priv = kmalloc(sizeof(*priv), GFP_ATOMIC);
	45	if (priv == NULL)
	46	goto fail;
	47	memset(priv, 0, sizeof(*priv));
	48	priv->key_idx = keyidx;
	49
	50	priv->tfm = crypto_alloc_tfm("arc4", 0);
	51	if (priv->tfm == NULL) {
	52	printk(KERN_DEBUG "ieee80211_crypt_wep: could not allocate "
	53	"crypto API arc4\n");
	54	goto fail;
	55	}
	56
	57	/* start WEP IV from a random value */
	58	get_random_bytes(&priv->iv, 4);
	59
	60	return priv;
	61
0edd5b44	62	fail:
b453872c JG	63	if (priv) {
	64	if (priv->tfm)
	65	crypto_free_tfm(priv->tfm);
	66	kfree(priv);
	67	}
	68	return NULL;
	69	}
	70
b453872c JG	71	static void prism2_wep_deinit(void *priv)
	72	{
	73	struct prism2_wep_data *_priv = priv;
	74	if (_priv && _priv->tfm)
	75	crypto_free_tfm(_priv->tfm);
	76	kfree(priv);
	77	}
	78
b453872c JG	79	/* Perform WEP encryption on given skb that has at least 4 bytes of headroom
	80	* for IV and 4 bytes of tailroom for ICV. Both IV and ICV will be transmitted,
	81	* so the payload length increases with 8 bytes.
	82	*
	83	* WEP frame payload: IV + TX key idx, RC4(data), ICV = RC4(CRC32(data))
	84	*/
	85	static int prism2_wep_encrypt(struct sk_buff skb, int hdr_len, void priv)
	86	{
	87	struct prism2_wep_data *wep = priv;
	88	u32 crc, klen, len;
	89	u8 key[WEP_KEY_LEN + 3];
	90	u8 pos, icv;
	91	struct scatterlist sg;
	92
	93	if (skb_headroom(skb) < 4 \|\| skb_tailroom(skb) < 4 \|\|
	94	skb->len < hdr_len)
	95	return -1;
	96
	97	len = skb->len - hdr_len;
	98	pos = skb_push(skb, 4);
	99	memmove(pos, pos + 4, hdr_len);
	100	pos += hdr_len;
	101
	102	klen = 3 + wep->key_len;
	103
	104	wep->iv++;
	105
	106	/* Fluhrer, Mantin, and Shamir have reported weaknesses in the key
	107	* scheduling algorithm of RC4. At least IVs (KeyByte + 3, 0xff, N)
	108	* can be used to speedup attacks, so avoid using them. */
	109	if ((wep->iv & 0xff00) == 0xff00) {
	110	u8 B = (wep->iv >> 16) & 0xff;
	111	if (B >= 3 && B < klen)
	112	wep->iv += 0x0100;
	113	}
	114
	115	/* Prepend 24-bit IV to RC4 key and TX frame */
	116	*pos++ = key[0] = (wep->iv >> 16) & 0xff;
	117	*pos++ = key[1] = (wep->iv >> 8) & 0xff;
	118	*pos++ = key[2] = wep->iv & 0xff;
	119	*pos++ = wep->key_idx << 6;
	120
	121	/* Copy rest of the WEP key (the secret part) */
	122	memcpy(key + 3, wep->key, wep->key_len);
	123
	124	/* Append little-endian CRC32 and encrypt it to produce ICV */
	125	crc = ~crc32_le(~0, pos, len);
	126	icv = skb_put(skb, 4);
	127	icv[0] = crc;
	128	icv[1] = crc >> 8;
	129	icv[2] = crc >> 16;
	130	icv[3] = crc >> 24;
	131
	132	crypto_cipher_setkey(wep->tfm, key, klen);
	133	sg.page = virt_to_page(pos);
	134	sg.offset = offset_in_page(pos);
	135	sg.length = len + 4;
	136	crypto_cipher_encrypt(wep->tfm, &sg, &sg, len + 4);
	137
	138	return 0;
	139	}
	140
b453872c JG	141	/* Perform WEP decryption on given buffer. Buffer includes whole WEP part of
	142	* the frame: IV (4 bytes), encrypted payload (including SNAP header),
	143	* ICV (4 bytes). len includes both IV and ICV.
	144	*
	145	* Returns 0 if frame was decrypted successfully and ICV was correct and -1 on
	146	* failure. If frame is OK, IV and ICV will be removed.
	147	*/
	148	static int prism2_wep_decrypt(struct sk_buff skb, int hdr_len, void priv)
	149	{
	150	struct prism2_wep_data *wep = priv;
	151	u32 crc, klen, plen;
	152	u8 key[WEP_KEY_LEN + 3];
	153	u8 keyidx, *pos, icv[4];
	154	struct scatterlist sg;
	155
	156	if (skb->len < hdr_len + 8)
	157	return -1;
	158
	159	pos = skb->data + hdr_len;
	160	key[0] = *pos++;
	161	key[1] = *pos++;
	162	key[2] = *pos++;
	163	keyidx = *pos++ >> 6;
	164	if (keyidx != wep->key_idx)
	165	return -1;
	166
	167	klen = 3 + wep->key_len;
	168
	169	/* Copy rest of the WEP key (the secret part) */
	170	memcpy(key + 3, wep->key, wep->key_len);
	171
	172	/* Apply RC4 to data and compute CRC32 over decrypted data */
	173	plen = skb->len - hdr_len - 8;
	174
	175	crypto_cipher_setkey(wep->tfm, key, klen);
	176	sg.page = virt_to_page(pos);
	177	sg.offset = offset_in_page(pos);
	178	sg.length = plen + 4;
	179	crypto_cipher_decrypt(wep->tfm, &sg, &sg, plen + 4);
	180
	181	crc = ~crc32_le(~0, pos, plen);
	182	icv[0] = crc;
	183	icv[1] = crc >> 8;
	184	icv[2] = crc >> 16;
	185	icv[3] = crc >> 24;
	186	if (memcmp(icv, pos + plen, 4) != 0) {
	187	/* ICV mismatch - drop frame */
	188	return -2;
	189	}
	190
	191	/* Remove IV and ICV */
	192	memmove(skb->data + 4, skb->data, hdr_len);
	193	skb_pull(skb, 4);
	194	skb_trim(skb, skb->len - 4);
	195
	196	return 0;
	197	}
	198
0edd5b44	199	static int prism2_wep_set_key(void key, int len, u8 seq, void *priv)
b453872c JG	200	{
	201	struct prism2_wep_data *wep = priv;
	202
	203	if (len < 0 \|\| len > WEP_KEY_LEN)
	204	return -1;
	205
	206	memcpy(wep->key, key, len);
	207	wep->key_len = len;
	208
	209	return 0;
	210	}
	211
0edd5b44	212	static int prism2_wep_get_key(void key, int len, u8 seq, void *priv)
b453872c JG	213	{
	214	struct prism2_wep_data *wep = priv;
	215
	216	if (len < wep->key_len)
	217	return -1;
	218
	219	memcpy(key, wep->key, wep->key_len);
	220
	221	return wep->key_len;
	222	}
	223
0edd5b44	224	static char prism2_wep_print_stats(char p, void *priv)
b453872c JG	225	{
b453872c JG	226	struct prism2_wep_data *wep = priv;
0edd5b44	227	p += sprintf(p, "key[%d] alg=WEP len=%d\n", wep->key_idx, wep->key_len);
b453872c JG	228	return p;
	229	}
	230
b453872c	231	static struct ieee80211_crypto_ops ieee80211_crypt_wep = {
74079fdc JK	232	.name = "WEP",
	233	.init = prism2_wep_init,
	234	.deinit = prism2_wep_deinit,
	235	.encrypt_mpdu = prism2_wep_encrypt,
	236	.decrypt_mpdu = prism2_wep_decrypt,
	237	.encrypt_msdu = NULL,
	238	.decrypt_msdu = NULL,
	239	.set_key = prism2_wep_set_key,
	240	.get_key = prism2_wep_get_key,
	241	.print_stats = prism2_wep_print_stats,
	242	.extra_prefix_len = 4, /* IV */
	243	.extra_postfix_len = 4, /* ICV */
	244	.owner = THIS_MODULE,
b453872c JG	245	};
b453872c JG	246
b453872c JG	247	static int __init ieee80211_crypto_wep_init(void)
	248	{
	249	return ieee80211_register_crypto_ops(&ieee80211_crypt_wep);
	250	}
	251
b453872c JG	252	static void __exit ieee80211_crypto_wep_exit(void)
	253	{
	254	ieee80211_unregister_crypto_ops(&ieee80211_crypt_wep);
	255	}
	256
b453872c JG	257	module_init(ieee80211_crypto_wep_init);
b453872c JG	258	module_exit(ieee80211_crypto_wep_exit);