[GitHub/mt8127/android_kernel_alcatel_ttab.git] / net / wireless / lib80211_crypt_wep.c

/*
 * lib80211 crypt: host-based WEP encryption implementation for lib80211
 *
 * Copyright (c) 2002-2004, Jouni Malinen <j@w1.fi>
 * Copyright (c) 2008, John W. Linville <linville@tuxdriver.com>
 *
 * 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/scatterlist.h>
#include <linux/skbuff.h>
#include <linux/mm.h>
#include <asm/string.h>

#include <net/lib80211.h>

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

MODULE_AUTHOR("Jouni Malinen");
MODULE_DESCRIPTION("lib80211 crypt: WEP");
MODULE_LICENSE("GPL");

struct lib80211_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 *lib80211_wep_init(int keyidx)
{
	struct lib80211_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)) {
		priv->tx_tfm = NULL;
		goto fail;
	}

	priv->rx_tfm = crypto_alloc_blkcipher("ecb(arc4)", 0, CRYPTO_ALG_ASYNC);
	if (IS_ERR(priv->rx_tfm)) {
		priv->rx_tfm = NULL;
		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 lib80211_wep_deinit(void *priv)
{
	struct lib80211_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 lib80211_wep_build_iv(struct sk_buff *skb, int hdr_len,
			       u8 *key, int keylen, void *priv)
{
	struct lib80211_wep_data *wep = priv;
	u32 klen;
	u8 *pos;

	if (skb_headroom(skb) < 4 || skb->len < hdr_len)
		return -1;

	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 lib80211_wep_encrypt(struct sk_buff *skb, int hdr_len, void *priv)
{
	struct lib80211_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 lib80211_wep_build_iv */
	if (skb_tailroom(skb) < 4)
		return -1;

	/* add the IV to the frame */
	if (lib80211_wep_build_iv(skb, hdr_len, NULL, 0, priv))
		return -1;

	/* Copy the IV into the first 3 bytes of the key */
	skb_copy_from_linear_data_offset(skb, hdr_len, key, 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_init_one(&sg, pos, 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 lib80211_wep_decrypt(struct sk_buff *skb, int hdr_len, void *priv)
{
	struct lib80211_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_init_one(&sg, pos, 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 lib80211_wep_set_key(void *key, int len, u8 * seq, void *priv)
{
	struct lib80211_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 lib80211_wep_get_key(void *key, int len, u8 * seq, void *priv)
{
	struct lib80211_wep_data *wep = priv;

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

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

	return wep->key_len;
}

static void lib80211_wep_print_stats(struct seq_file *m, void *priv)
{
	struct lib80211_wep_data *wep = priv;
	seq_printf(m, "key[%d] alg=WEP len=%d\n", wep->key_idx, wep->key_len);
}

static struct lib80211_crypto_ops lib80211_crypt_wep = {
	.name = "WEP",
	.init = lib80211_wep_init,
	.deinit = lib80211_wep_deinit,
	.encrypt_mpdu = lib80211_wep_encrypt,
	.decrypt_mpdu = lib80211_wep_decrypt,
	.encrypt_msdu = NULL,
	.decrypt_msdu = NULL,
	.set_key = lib80211_wep_set_key,
	.get_key = lib80211_wep_get_key,
	.print_stats = lib80211_wep_print_stats,
	.extra_mpdu_prefix_len = 4,	/* IV */
	.extra_mpdu_postfix_len = 4,	/* ICV */
	.owner = THIS_MODULE,
};

static int __init lib80211_crypto_wep_init(void)
{
	return lib80211_register_crypto_ops(&lib80211_crypt_wep);
}

static void __exit lib80211_crypto_wep_exit(void)
{
	lib80211_unregister_crypto_ops(&lib80211_crypt_wep);
}

module_init(lib80211_crypto_wep_init);
module_exit(lib80211_crypto_wep_exit);
Commit	Line	Data
b453872c	1	/*
274bfb8d	2	* lib80211 crypt: host-based WEP encryption implementation for lib80211
b453872c	3	*
85d32e7b	4	* Copyright (c) 2002-2004, Jouni Malinen <j@w1.fi>
274bfb8d	5	* Copyright (c) 2008, John W. Linville <linville@tuxdriver.com>
b453872c JG	6	*
	7	* This program is free software; you can redistribute it and/or modify
	8	* it under the terms of the GNU General Public License version 2 as
	9	* published by the Free Software Foundation. See README and COPYING for
	10	* more details.
	11	*/
	12
f12cc209	13	#include <linux/err.h>
b453872c JG	14	#include <linux/module.h>
	15	#include <linux/init.h>
	16	#include <linux/slab.h>
	17	#include <linux/random.h>
11763609	18	#include <linux/scatterlist.h>
b453872c	19	#include <linux/skbuff.h>
d7fe0f24	20	#include <linux/mm.h>
b453872c JG	21	#include <asm/string.h>
b453872c JG	22
274bfb8d	23	#include <net/lib80211.h>
b453872c	24
b453872c	25	#include <linux/crypto.h>
b453872c JG	26	#include <linux/crc32.h>
	27
	28	MODULE_AUTHOR("Jouni Malinen");
274bfb8d	29	MODULE_DESCRIPTION("lib80211 crypt: WEP");
b453872c JG	30	MODULE_LICENSE("GPL");
b453872c JG	31
274bfb8d	32	struct lib80211_wep_data {
b453872c JG	33	u32 iv;
	34	#define WEP_KEY_LEN 13
	35	u8 key[WEP_KEY_LEN + 1];
	36	u8 key_len;
	37	u8 key_idx;
28eb177d JG	38	struct crypto_blkcipher *tx_tfm;
28eb177d JG	39	struct crypto_blkcipher *rx_tfm;
b453872c JG	40	};
b453872c JG	41
274bfb8d	42	static void *lib80211_wep_init(int keyidx)
b453872c	43	{
274bfb8d	44	struct lib80211_wep_data *priv;
b453872c	45
0da974f4	46	priv = kzalloc(sizeof(*priv), GFP_ATOMIC);
b453872c JG	47	if (priv == NULL)
b453872c JG	48	goto fail;
b453872c JG	49	priv->key_idx = keyidx;
b453872c JG	50
28eb177d JG	51	priv->tx_tfm = crypto_alloc_blkcipher("ecb(arc4)", 0, CRYPTO_ALG_ASYNC);
28eb177d JG	52	if (IS_ERR(priv->tx_tfm)) {
18379879	53	priv->tx_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)) {
18379879	59	priv->rx_tfm = NULL;
5a656949 ZY	60	goto fail;
5a656949 ZY	61	}
b453872c JG	62	/* start WEP IV from a random value */
	63	get_random_bytes(&priv->iv, 4);
	64
	65	return priv;
	66
0edd5b44	67	fail:
b453872c	68	if (priv) {
5a656949	69	if (priv->tx_tfm)
28eb177d	70	crypto_free_blkcipher(priv->tx_tfm);
5a656949	71	if (priv->rx_tfm)
28eb177d	72	crypto_free_blkcipher(priv->rx_tfm);
b453872c JG	73	kfree(priv);
	74	}
	75	return NULL;
	76	}
	77
274bfb8d	78	static void lib80211_wep_deinit(void *priv)
b453872c	79	{
274bfb8d	80	struct lib80211_wep_data *_priv = priv;
5a656949 ZY	81	if (_priv) {
5a656949 ZY	82	if (_priv->tx_tfm)
28eb177d	83	crypto_free_blkcipher(_priv->tx_tfm);
5a656949	84	if (_priv->rx_tfm)
28eb177d	85	crypto_free_blkcipher(_priv->rx_tfm);
5a656949	86	}
b453872c JG	87	kfree(priv);
	88	}
	89
a4bf26f3	90	/* Add WEP IV/key info to a frame that has at least 4 bytes of headroom */
274bfb8d	91	static int lib80211_wep_build_iv(struct sk_buff *skb, int hdr_len,
9184d934	92	u8 key, int keylen, void priv)
b453872c	93	{
274bfb8d	94	struct lib80211_wep_data *wep = priv;
6572e91d	95	u32 klen;
a4bf26f3	96	u8 *pos;
64265651	97
a4bf26f3	98	if (skb_headroom(skb) < 4 \|\| skb->len < hdr_len)
b453872c JG	99	return -1;
b453872c JG	100
b453872c JG	101	pos = skb_push(skb, 4);
	102	memmove(pos, pos + 4, hdr_len);
	103	pos += hdr_len;
	104
	105	klen = 3 + wep->key_len;
	106
	107	wep->iv++;
	108
	109	/* Fluhrer, Mantin, and Shamir have reported weaknesses in the key
	110	* scheduling algorithm of RC4. At least IVs (KeyByte + 3, 0xff, N)
	111	* can be used to speedup attacks, so avoid using them. */
	112	if ((wep->iv & 0xff00) == 0xff00) {
	113	u8 B = (wep->iv >> 16) & 0xff;
	114	if (B >= 3 && B < klen)
	115	wep->iv += 0x0100;
	116	}
	117
	118	/* Prepend 24-bit IV to RC4 key and TX frame */
a4bf26f3 JB	119	*pos++ = (wep->iv >> 16) & 0xff;
	120	*pos++ = (wep->iv >> 8) & 0xff;
	121	*pos++ = wep->iv & 0xff;
b453872c JG	122	*pos++ = wep->key_idx << 6;
b453872c JG	123
a4bf26f3 JB	124	return 0;
	125	}
	126
	127	/* Perform WEP encryption on given skb that has at least 4 bytes of headroom
	128	* for IV and 4 bytes of tailroom for ICV. Both IV and ICV will be transmitted,
	129	* so the payload length increases with 8 bytes.
	130	*
	131	* WEP frame payload: IV + TX key idx, RC4(data), ICV = RC4(CRC32(data))
	132	*/
274bfb8d	133	static int lib80211_wep_encrypt(struct sk_buff skb, int hdr_len, void priv)
a4bf26f3	134	{
274bfb8d	135	struct lib80211_wep_data *wep = priv;
28eb177d	136	struct blkcipher_desc desc = { .tfm = wep->tx_tfm };
a4bf26f3 JB	137	u32 crc, klen, len;
	138	u8 pos, icv;
	139	struct scatterlist sg;
	140	u8 key[WEP_KEY_LEN + 3];
	141
274bfb8d	142	/* other checks are in lib80211_wep_build_iv */
a4bf26f3 JB	143	if (skb_tailroom(skb) < 4)
a4bf26f3 JB	144	return -1;
64265651	145
a4bf26f3	146	/* add the IV to the frame */
274bfb8d	147	if (lib80211_wep_build_iv(skb, hdr_len, NULL, 0, priv))
a4bf26f3	148	return -1;
64265651	149
a4bf26f3	150	/* Copy the IV into the first 3 bytes of the key */
d626f62b	151	skb_copy_from_linear_data_offset(skb, hdr_len, key, 3);
a4bf26f3	152
b453872c JG	153	/* Copy rest of the WEP key (the secret part) */
b453872c JG	154	memcpy(key + 3, wep->key, wep->key_len);
64265651	155
a4bf26f3 JB	156	len = skb->len - hdr_len - 4;
	157	pos = skb->data + hdr_len + 4;
	158	klen = 3 + wep->key_len;
b453872c	159
a4bf26f3	160	/* Append little-endian CRC32 over only the data and encrypt it to produce ICV */
b453872c JG	161	crc = ~crc32_le(~0, pos, len);
	162	icv = skb_put(skb, 4);
	163	icv[0] = crc;
	164	icv[1] = crc >> 8;
	165	icv[2] = crc >> 16;
	166	icv[3] = crc >> 24;
	167
28eb177d	168	crypto_blkcipher_setkey(wep->tx_tfm, key, klen);
fa05f128	169	sg_init_one(&sg, pos, len + 4);
f12cc209	170	return crypto_blkcipher_encrypt(&desc, &sg, &sg, len + 4);
b453872c JG	171	}
b453872c JG	172
b453872c JG	173	/* Perform WEP decryption on given buffer. Buffer includes whole WEP part of
	174	* the frame: IV (4 bytes), encrypted payload (including SNAP header),
	175	* ICV (4 bytes). len includes both IV and ICV.
	176	*
	177	* Returns 0 if frame was decrypted successfully and ICV was correct and -1 on
	178	* failure. If frame is OK, IV and ICV will be removed.
	179	*/
274bfb8d	180	static int lib80211_wep_decrypt(struct sk_buff skb, int hdr_len, void priv)
b453872c	181	{
274bfb8d	182	struct lib80211_wep_data *wep = priv;
28eb177d	183	struct blkcipher_desc desc = { .tfm = wep->rx_tfm };
b453872c JG	184	u32 crc, klen, plen;
	185	u8 key[WEP_KEY_LEN + 3];
	186	u8 keyidx, *pos, icv[4];
	187	struct scatterlist sg;
	188
	189	if (skb->len < hdr_len + 8)
	190	return -1;
	191
	192	pos = skb->data + hdr_len;
	193	key[0] = *pos++;
	194	key[1] = *pos++;
	195	key[2] = *pos++;
	196	keyidx = *pos++ >> 6;
	197	if (keyidx != wep->key_idx)
	198	return -1;
	199
	200	klen = 3 + wep->key_len;
	201
	202	/* Copy rest of the WEP key (the secret part) */
	203	memcpy(key + 3, wep->key, wep->key_len);
	204
	205	/* Apply RC4 to data and compute CRC32 over decrypted data */
	206	plen = skb->len - hdr_len - 8;
	207
28eb177d	208	crypto_blkcipher_setkey(wep->rx_tfm, key, klen);
fa05f128	209	sg_init_one(&sg, pos, plen + 4);
f12cc209 HX	210	if (crypto_blkcipher_decrypt(&desc, &sg, &sg, plen + 4))
f12cc209 HX	211	return -7;
b453872c JG	212
	213	crc = ~crc32_le(~0, pos, plen);
	214	icv[0] = crc;
	215	icv[1] = crc >> 8;
	216	icv[2] = crc >> 16;
	217	icv[3] = crc >> 24;
	218	if (memcmp(icv, pos + plen, 4) != 0) {
	219	/* ICV mismatch - drop frame */
	220	return -2;
	221	}
	222
	223	/* Remove IV and ICV */
	224	memmove(skb->data + 4, skb->data, hdr_len);
	225	skb_pull(skb, 4);
	226	skb_trim(skb, skb->len - 4);
	227
	228	return 0;
	229	}
	230
274bfb8d	231	static int lib80211_wep_set_key(void key, int len, u8 seq, void *priv)
b453872c	232	{
274bfb8d	233	struct lib80211_wep_data *wep = priv;
b453872c JG	234
	235	if (len < 0 \|\| len > WEP_KEY_LEN)
	236	return -1;
	237
	238	memcpy(wep->key, key, len);
	239	wep->key_len = len;
	240
	241	return 0;
	242	}
	243
274bfb8d	244	static int lib80211_wep_get_key(void key, int len, u8 seq, void *priv)
b453872c	245	{
274bfb8d	246	struct lib80211_wep_data *wep = priv;
b453872c JG	247
	248	if (len < wep->key_len)
	249	return -1;
	250
	251	memcpy(key, wep->key, wep->key_len);
	252
	253	return wep->key_len;
	254	}
	255
6bbefe86	256	static void lib80211_wep_print_stats(struct seq_file m, void priv)
b453872c	257	{
274bfb8d	258	struct lib80211_wep_data *wep = priv;
6bbefe86	259	seq_printf(m, "key[%d] alg=WEP len=%d\n", wep->key_idx, wep->key_len);
b453872c JG	260	}
b453872c JG	261
274bfb8d	262	static struct lib80211_crypto_ops lib80211_crypt_wep = {
74079fdc	263	.name = "WEP",
274bfb8d JL	264	.init = lib80211_wep_init,
274bfb8d JL	265	.deinit = lib80211_wep_deinit,
274bfb8d JL	266	.encrypt_mpdu = lib80211_wep_encrypt,
274bfb8d JL	267	.decrypt_mpdu = lib80211_wep_decrypt,
74079fdc JK	268	.encrypt_msdu = NULL,
74079fdc JK	269	.decrypt_msdu = NULL,
274bfb8d JL	270	.set_key = lib80211_wep_set_key,
	271	.get_key = lib80211_wep_get_key,
	272	.print_stats = lib80211_wep_print_stats,
1264fc04 JK	273	.extra_mpdu_prefix_len = 4, /* IV */
1264fc04 JK	274	.extra_mpdu_postfix_len = 4, /* ICV */
74079fdc	275	.owner = THIS_MODULE,
b453872c JG	276	};
b453872c JG	277
274bfb8d	278	static int __init lib80211_crypto_wep_init(void)
b453872c	279	{
274bfb8d	280	return lib80211_register_crypto_ops(&lib80211_crypt_wep);
b453872c JG	281	}
b453872c JG	282
274bfb8d	283	static void __exit lib80211_crypto_wep_exit(void)
b453872c	284	{
274bfb8d	285	lib80211_unregister_crypto_ops(&lib80211_crypt_wep);
b453872c JG	286	}
b453872c JG	287
274bfb8d JL	288	module_init(lib80211_crypto_wep_init);
274bfb8d JL	289	module_exit(lib80211_crypto_wep_exit);