[mirror_ubuntu-bionic-kernel.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 <crypto/skcipher.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_skcipher *tx_tfm;
	struct crypto_skcipher *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_skcipher("ecb(arc4)", 0, CRYPTO_ALG_ASYNC);
	if (IS_ERR(priv->tx_tfm)) {
		priv->tx_tfm = NULL;
		goto fail;
	}

	priv->rx_tfm = crypto_alloc_skcipher("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) {
		crypto_free_skcipher(priv->tx_tfm);
		crypto_free_skcipher(priv->rx_tfm);
		kfree(priv);
	}
	return NULL;
}

static void lib80211_wep_deinit(void *priv)
{
	struct lib80211_wep_data *_priv = priv;
	if (_priv) {
		crypto_free_skcipher(_priv->tx_tfm);
		crypto_free_skcipher(_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;
	SKCIPHER_REQUEST_ON_STACK(req, wep->tx_tfm);
	u32 crc, klen, len;
	u8 *pos, *icv;
	struct scatterlist sg;
	u8 key[WEP_KEY_LEN + 3];
	int err;

	/* 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_skcipher_setkey(wep->tx_tfm, key, klen);
	sg_init_one(&sg, pos, len + 4);
	skcipher_request_set_tfm(req, wep->tx_tfm);
	skcipher_request_set_callback(req, 0, NULL, NULL);
	skcipher_request_set_crypt(req, &sg, &sg, len + 4, NULL);
	err = crypto_skcipher_encrypt(req);
	skcipher_request_zero(req);
	return err;
}

/* 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;
	SKCIPHER_REQUEST_ON_STACK(req, wep->rx_tfm);
	u32 crc, klen, plen;
	u8 key[WEP_KEY_LEN + 3];
	u8 keyidx, *pos, icv[4];
	struct scatterlist sg;
	int err;

	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_skcipher_setkey(wep->rx_tfm, key, klen);
	sg_init_one(&sg, pos, plen + 4);
	skcipher_request_set_tfm(req, wep->rx_tfm);
	skcipher_request_set_callback(req, 0, NULL, NULL);
	skcipher_request_set_crypt(req, &sg, &sg, plen + 4, NULL);
	err = crypto_skcipher_decrypt(req);
	skcipher_request_zero(req);
	if (err)
		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
608fb34c	25	#include <crypto/skcipher.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;
608fb34c HX	38	struct crypto_skcipher *tx_tfm;
608fb34c HX	39	struct crypto_skcipher *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
608fb34c	51	priv->tx_tfm = crypto_alloc_skcipher("ecb(arc4)", 0, CRYPTO_ALG_ASYNC);
28eb177d	52	if (IS_ERR(priv->tx_tfm)) {
18379879	53	priv->tx_tfm = NULL;
b453872c JG	54	goto fail;
	55	}
	56
608fb34c	57	priv->rx_tfm = crypto_alloc_skcipher("ecb(arc4)", 0, CRYPTO_ALG_ASYNC);
28eb177d	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) {
608fb34c HX	69	crypto_free_skcipher(priv->tx_tfm);
608fb34c HX	70	crypto_free_skcipher(priv->rx_tfm);
b453872c JG	71	kfree(priv);
	72	}
	73	return NULL;
	74	}
	75
274bfb8d	76	static void lib80211_wep_deinit(void *priv)
b453872c	77	{
274bfb8d	78	struct lib80211_wep_data *_priv = priv;
5a656949	79	if (_priv) {
608fb34c HX	80	crypto_free_skcipher(_priv->tx_tfm);
608fb34c HX	81	crypto_free_skcipher(_priv->rx_tfm);
5a656949	82	}
b453872c JG	83	kfree(priv);
	84	}
	85
a4bf26f3	86	/* Add WEP IV/key info to a frame that has at least 4 bytes of headroom */
274bfb8d	87	static int lib80211_wep_build_iv(struct sk_buff *skb, int hdr_len,
9184d934	88	u8 key, int keylen, void priv)
b453872c	89	{
274bfb8d	90	struct lib80211_wep_data *wep = priv;
6572e91d	91	u32 klen;
a4bf26f3	92	u8 *pos;
64265651	93
a4bf26f3	94	if (skb_headroom(skb) < 4 \|\| skb->len < hdr_len)
b453872c JG	95	return -1;
b453872c JG	96
b453872c JG	97	pos = skb_push(skb, 4);
	98	memmove(pos, pos + 4, hdr_len);
	99	pos += hdr_len;
	100
	101	klen = 3 + wep->key_len;
	102
	103	wep->iv++;
	104
	105	/* Fluhrer, Mantin, and Shamir have reported weaknesses in the key
	106	* scheduling algorithm of RC4. At least IVs (KeyByte + 3, 0xff, N)
	107	* can be used to speedup attacks, so avoid using them. */
	108	if ((wep->iv & 0xff00) == 0xff00) {
	109	u8 B = (wep->iv >> 16) & 0xff;
	110	if (B >= 3 && B < klen)
	111	wep->iv += 0x0100;
	112	}
	113
	114	/* Prepend 24-bit IV to RC4 key and TX frame */
a4bf26f3 JB	115	*pos++ = (wep->iv >> 16) & 0xff;
	116	*pos++ = (wep->iv >> 8) & 0xff;
	117	*pos++ = wep->iv & 0xff;
b453872c JG	118	*pos++ = wep->key_idx << 6;
b453872c JG	119
a4bf26f3 JB	120	return 0;
	121	}
	122
	123	/* Perform WEP encryption on given skb that has at least 4 bytes of headroom
	124	* for IV and 4 bytes of tailroom for ICV. Both IV and ICV will be transmitted,
	125	* so the payload length increases with 8 bytes.
	126	*
	127	* WEP frame payload: IV + TX key idx, RC4(data), ICV = RC4(CRC32(data))
	128	*/
274bfb8d	129	static int lib80211_wep_encrypt(struct sk_buff skb, int hdr_len, void priv)
a4bf26f3	130	{
274bfb8d	131	struct lib80211_wep_data *wep = priv;
608fb34c	132	SKCIPHER_REQUEST_ON_STACK(req, wep->tx_tfm);
a4bf26f3 JB	133	u32 crc, klen, len;
	134	u8 pos, icv;
	135	struct scatterlist sg;
	136	u8 key[WEP_KEY_LEN + 3];
608fb34c	137	int err;
a4bf26f3	138
274bfb8d	139	/* other checks are in lib80211_wep_build_iv */
a4bf26f3 JB	140	if (skb_tailroom(skb) < 4)
a4bf26f3 JB	141	return -1;
64265651	142
a4bf26f3	143	/* add the IV to the frame */
274bfb8d	144	if (lib80211_wep_build_iv(skb, hdr_len, NULL, 0, priv))
a4bf26f3	145	return -1;
64265651	146
a4bf26f3	147	/* Copy the IV into the first 3 bytes of the key */
d626f62b	148	skb_copy_from_linear_data_offset(skb, hdr_len, key, 3);
a4bf26f3	149
b453872c JG	150	/* Copy rest of the WEP key (the secret part) */
b453872c JG	151	memcpy(key + 3, wep->key, wep->key_len);
64265651	152
a4bf26f3 JB	153	len = skb->len - hdr_len - 4;
	154	pos = skb->data + hdr_len + 4;
	155	klen = 3 + wep->key_len;
b453872c	156
a4bf26f3	157	/* Append little-endian CRC32 over only the data and encrypt it to produce ICV */
b453872c JG	158	crc = ~crc32_le(~0, pos, len);
	159	icv = skb_put(skb, 4);
	160	icv[0] = crc;
	161	icv[1] = crc >> 8;
	162	icv[2] = crc >> 16;
	163	icv[3] = crc >> 24;
	164
608fb34c	165	crypto_skcipher_setkey(wep->tx_tfm, key, klen);
fa05f128	166	sg_init_one(&sg, pos, len + 4);
608fb34c HX	167	skcipher_request_set_tfm(req, wep->tx_tfm);
	168	skcipher_request_set_callback(req, 0, NULL, NULL);
	169	skcipher_request_set_crypt(req, &sg, &sg, len + 4, NULL);
	170	err = crypto_skcipher_encrypt(req);
	171	skcipher_request_zero(req);
	172	return err;
b453872c JG	173	}
b453872c JG	174
b453872c JG	175	/* Perform WEP decryption on given buffer. Buffer includes whole WEP part of
	176	* the frame: IV (4 bytes), encrypted payload (including SNAP header),
	177	* ICV (4 bytes). len includes both IV and ICV.
	178	*
	179	* Returns 0 if frame was decrypted successfully and ICV was correct and -1 on
	180	* failure. If frame is OK, IV and ICV will be removed.
	181	*/
274bfb8d	182	static int lib80211_wep_decrypt(struct sk_buff skb, int hdr_len, void priv)
b453872c	183	{
274bfb8d	184	struct lib80211_wep_data *wep = priv;
608fb34c	185	SKCIPHER_REQUEST_ON_STACK(req, wep->rx_tfm);
b453872c JG	186	u32 crc, klen, plen;
	187	u8 key[WEP_KEY_LEN + 3];
	188	u8 keyidx, *pos, icv[4];
	189	struct scatterlist sg;
608fb34c	190	int err;
b453872c JG	191
	192	if (skb->len < hdr_len + 8)
	193	return -1;
	194
	195	pos = skb->data + hdr_len;
	196	key[0] = *pos++;
	197	key[1] = *pos++;
	198	key[2] = *pos++;
	199	keyidx = *pos++ >> 6;
	200	if (keyidx != wep->key_idx)
	201	return -1;
	202
	203	klen = 3 + wep->key_len;
	204
	205	/* Copy rest of the WEP key (the secret part) */
	206	memcpy(key + 3, wep->key, wep->key_len);
	207
	208	/* Apply RC4 to data and compute CRC32 over decrypted data */
	209	plen = skb->len - hdr_len - 8;
	210
608fb34c	211	crypto_skcipher_setkey(wep->rx_tfm, key, klen);
fa05f128	212	sg_init_one(&sg, pos, plen + 4);
608fb34c HX	213	skcipher_request_set_tfm(req, wep->rx_tfm);
	214	skcipher_request_set_callback(req, 0, NULL, NULL);
	215	skcipher_request_set_crypt(req, &sg, &sg, plen + 4, NULL);
	216	err = crypto_skcipher_decrypt(req);
	217	skcipher_request_zero(req);
	218	if (err)
f12cc209	219	return -7;
b453872c JG	220
	221	crc = ~crc32_le(~0, pos, plen);
	222	icv[0] = crc;
	223	icv[1] = crc >> 8;
	224	icv[2] = crc >> 16;
	225	icv[3] = crc >> 24;
	226	if (memcmp(icv, pos + plen, 4) != 0) {
	227	/* ICV mismatch - drop frame */
	228	return -2;
	229	}
	230
	231	/* Remove IV and ICV */
	232	memmove(skb->data + 4, skb->data, hdr_len);
	233	skb_pull(skb, 4);
	234	skb_trim(skb, skb->len - 4);
	235
	236	return 0;
	237	}
	238
274bfb8d	239	static int lib80211_wep_set_key(void key, int len, u8 seq, void *priv)
b453872c	240	{
274bfb8d	241	struct lib80211_wep_data *wep = priv;
b453872c JG	242
	243	if (len < 0 \|\| len > WEP_KEY_LEN)
	244	return -1;
	245
	246	memcpy(wep->key, key, len);
	247	wep->key_len = len;
	248
	249	return 0;
	250	}
	251
274bfb8d	252	static int lib80211_wep_get_key(void key, int len, u8 seq, void *priv)
b453872c	253	{
274bfb8d	254	struct lib80211_wep_data *wep = priv;
b453872c JG	255
	256	if (len < wep->key_len)
	257	return -1;
	258
	259	memcpy(key, wep->key, wep->key_len);
	260
	261	return wep->key_len;
	262	}
	263
6bbefe86	264	static void lib80211_wep_print_stats(struct seq_file m, void priv)
b453872c	265	{
274bfb8d	266	struct lib80211_wep_data *wep = priv;
6bbefe86	267	seq_printf(m, "key[%d] alg=WEP len=%d\n", wep->key_idx, wep->key_len);
b453872c JG	268	}
b453872c JG	269
274bfb8d	270	static struct lib80211_crypto_ops lib80211_crypt_wep = {
74079fdc	271	.name = "WEP",
274bfb8d JL	272	.init = lib80211_wep_init,
274bfb8d JL	273	.deinit = lib80211_wep_deinit,
274bfb8d JL	274	.encrypt_mpdu = lib80211_wep_encrypt,
274bfb8d JL	275	.decrypt_mpdu = lib80211_wep_decrypt,
74079fdc JK	276	.encrypt_msdu = NULL,
74079fdc JK	277	.decrypt_msdu = NULL,
274bfb8d JL	278	.set_key = lib80211_wep_set_key,
	279	.get_key = lib80211_wep_get_key,
	280	.print_stats = lib80211_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
274bfb8d	286	static int __init lib80211_crypto_wep_init(void)
b453872c	287	{
274bfb8d	288	return lib80211_register_crypto_ops(&lib80211_crypt_wep);
b453872c JG	289	}
b453872c JG	290
274bfb8d	291	static void __exit lib80211_crypto_wep_exit(void)
b453872c	292	{
274bfb8d	293	lib80211_unregister_crypto_ops(&lib80211_crypt_wep);
b453872c JG	294	}
b453872c JG	295
274bfb8d JL	296	module_init(lib80211_crypto_wep_init);
274bfb8d JL	297	module_exit(lib80211_crypto_wep_exit);