blob: c1304018fc1c5e08247cc7882496a5688c3dcb85 [file] [log] [blame]
Jeff Garzikb4538722005-05-12 22:48:20 -04001/*
John W. Linville274bfb82008-10-29 11:35:05 -04002 * lib80211 crypt: host-based WEP encryption implementation for lib80211
Jeff Garzikb4538722005-05-12 22:48:20 -04003 *
Jouni Malinen85d32e72007-03-24 17:15:30 -07004 * Copyright (c) 2002-2004, Jouni Malinen <j@w1.fi>
John W. Linville274bfb82008-10-29 11:35:05 -04005 * Copyright (c) 2008, John W. Linville <linville@tuxdriver.com>
Jeff Garzikb4538722005-05-12 22:48:20 -04006 *
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
Herbert Xuf12cc202006-08-22 20:36:13 +100013#include <linux/err.h>
Jeff Garzikb4538722005-05-12 22:48:20 -040014#include <linux/module.h>
15#include <linux/init.h>
16#include <linux/slab.h>
17#include <linux/random.h>
Ralf Baechle11763602007-10-23 20:42:11 +020018#include <linux/scatterlist.h>
Jeff Garzikb4538722005-05-12 22:48:20 -040019#include <linux/skbuff.h>
Al Virod7fe0f22006-12-03 23:15:30 -050020#include <linux/mm.h>
Jeff Garzikb4538722005-05-12 22:48:20 -040021#include <asm/string.h>
22
John W. Linville274bfb82008-10-29 11:35:05 -040023#include <net/lib80211.h>
Jeff Garzikb4538722005-05-12 22:48:20 -040024
Jeff Garzikb4538722005-05-12 22:48:20 -040025#include <linux/crypto.h>
Jeff Garzikb4538722005-05-12 22:48:20 -040026#include <linux/crc32.h>
27
28MODULE_AUTHOR("Jouni Malinen");
John W. Linville274bfb82008-10-29 11:35:05 -040029MODULE_DESCRIPTION("lib80211 crypt: WEP");
Jeff Garzikb4538722005-05-12 22:48:20 -040030MODULE_LICENSE("GPL");
31
John W. Linville274bfb82008-10-29 11:35:05 -040032struct lib80211_wep_data {
Jeff Garzikb4538722005-05-12 22:48:20 -040033 u32 iv;
34#define WEP_KEY_LEN 13
35 u8 key[WEP_KEY_LEN + 1];
36 u8 key_len;
37 u8 key_idx;
Jeff Garzik28eb1772006-09-22 20:10:23 -040038 struct crypto_blkcipher *tx_tfm;
39 struct crypto_blkcipher *rx_tfm;
Jeff Garzikb4538722005-05-12 22:48:20 -040040};
41
John W. Linville274bfb82008-10-29 11:35:05 -040042static void *lib80211_wep_init(int keyidx)
Jeff Garzikb4538722005-05-12 22:48:20 -040043{
John W. Linville274bfb82008-10-29 11:35:05 -040044 struct lib80211_wep_data *priv;
Jeff Garzikb4538722005-05-12 22:48:20 -040045
Panagiotis Issaris0da974f2006-07-21 14:51:30 -070046 priv = kzalloc(sizeof(*priv), GFP_ATOMIC);
Jeff Garzikb4538722005-05-12 22:48:20 -040047 if (priv == NULL)
48 goto fail;
Jeff Garzikb4538722005-05-12 22:48:20 -040049 priv->key_idx = keyidx;
50
Jeff Garzik28eb1772006-09-22 20:10:23 -040051 priv->tx_tfm = crypto_alloc_blkcipher("ecb(arc4)", 0, CRYPTO_ALG_ASYNC);
52 if (IS_ERR(priv->tx_tfm)) {
Jeff Garzik18379872006-09-22 21:19:05 -040053 priv->tx_tfm = NULL;
Jeff Garzikb4538722005-05-12 22:48:20 -040054 goto fail;
55 }
56
Jeff Garzik28eb1772006-09-22 20:10:23 -040057 priv->rx_tfm = crypto_alloc_blkcipher("ecb(arc4)", 0, CRYPTO_ALG_ASYNC);
58 if (IS_ERR(priv->rx_tfm)) {
Jeff Garzik18379872006-09-22 21:19:05 -040059 priv->rx_tfm = NULL;
Zhu Yi5a656942006-08-21 11:33:56 +080060 goto fail;
61 }
Jeff Garzikb4538722005-05-12 22:48:20 -040062 /* start WEP IV from a random value */
63 get_random_bytes(&priv->iv, 4);
64
65 return priv;
66
Jeff Garzik0edd5b42005-09-07 00:48:31 -040067 fail:
Jeff Garzikb4538722005-05-12 22:48:20 -040068 if (priv) {
Zhu Yi5a656942006-08-21 11:33:56 +080069 if (priv->tx_tfm)
Jeff Garzik28eb1772006-09-22 20:10:23 -040070 crypto_free_blkcipher(priv->tx_tfm);
Zhu Yi5a656942006-08-21 11:33:56 +080071 if (priv->rx_tfm)
Jeff Garzik28eb1772006-09-22 20:10:23 -040072 crypto_free_blkcipher(priv->rx_tfm);
Jeff Garzikb4538722005-05-12 22:48:20 -040073 kfree(priv);
74 }
75 return NULL;
76}
77
John W. Linville274bfb82008-10-29 11:35:05 -040078static void lib80211_wep_deinit(void *priv)
Jeff Garzikb4538722005-05-12 22:48:20 -040079{
John W. Linville274bfb82008-10-29 11:35:05 -040080 struct lib80211_wep_data *_priv = priv;
Zhu Yi5a656942006-08-21 11:33:56 +080081 if (_priv) {
82 if (_priv->tx_tfm)
Jeff Garzik28eb1772006-09-22 20:10:23 -040083 crypto_free_blkcipher(_priv->tx_tfm);
Zhu Yi5a656942006-08-21 11:33:56 +080084 if (_priv->rx_tfm)
Jeff Garzik28eb1772006-09-22 20:10:23 -040085 crypto_free_blkcipher(_priv->rx_tfm);
Zhu Yi5a656942006-08-21 11:33:56 +080086 }
Jeff Garzikb4538722005-05-12 22:48:20 -040087 kfree(priv);
88}
89
Johannes Berga4bf26f2005-12-31 11:35:20 +010090/* Add WEP IV/key info to a frame that has at least 4 bytes of headroom */
John W. Linville274bfb82008-10-29 11:35:05 -040091static int lib80211_wep_build_iv(struct sk_buff *skb, int hdr_len,
Zhu Yi9184d932006-01-19 16:22:32 +080092 u8 *key, int keylen, void *priv)
Jeff Garzikb4538722005-05-12 22:48:20 -040093{
John W. Linville274bfb82008-10-29 11:35:05 -040094 struct lib80211_wep_data *wep = priv;
Rajkumar Manoharan6572e912011-04-25 15:56:16 +053095 u32 klen;
Johannes Berga4bf26f2005-12-31 11:35:20 +010096 u8 *pos;
YOSHIFUJI Hideaki64265652007-02-09 23:24:46 +090097
Johannes Berga4bf26f2005-12-31 11:35:20 +010098 if (skb_headroom(skb) < 4 || skb->len < hdr_len)
Jeff Garzikb4538722005-05-12 22:48:20 -040099 return -1;
100
Jeff Garzikb4538722005-05-12 22:48:20 -0400101 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 */
Johannes Berga4bf26f2005-12-31 11:35:20 +0100119 *pos++ = (wep->iv >> 16) & 0xff;
120 *pos++ = (wep->iv >> 8) & 0xff;
121 *pos++ = wep->iv & 0xff;
Jeff Garzikb4538722005-05-12 22:48:20 -0400122 *pos++ = wep->key_idx << 6;
123
Johannes Berga4bf26f2005-12-31 11:35:20 +0100124 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 */
John W. Linville274bfb82008-10-29 11:35:05 -0400133static int lib80211_wep_encrypt(struct sk_buff *skb, int hdr_len, void *priv)
Johannes Berga4bf26f2005-12-31 11:35:20 +0100134{
John W. Linville274bfb82008-10-29 11:35:05 -0400135 struct lib80211_wep_data *wep = priv;
Jeff Garzik28eb1772006-09-22 20:10:23 -0400136 struct blkcipher_desc desc = { .tfm = wep->tx_tfm };
Johannes Berga4bf26f2005-12-31 11:35:20 +0100137 u32 crc, klen, len;
138 u8 *pos, *icv;
139 struct scatterlist sg;
140 u8 key[WEP_KEY_LEN + 3];
141
John W. Linville274bfb82008-10-29 11:35:05 -0400142 /* other checks are in lib80211_wep_build_iv */
Johannes Berga4bf26f2005-12-31 11:35:20 +0100143 if (skb_tailroom(skb) < 4)
144 return -1;
YOSHIFUJI Hideaki64265652007-02-09 23:24:46 +0900145
Johannes Berga4bf26f2005-12-31 11:35:20 +0100146 /* add the IV to the frame */
John W. Linville274bfb82008-10-29 11:35:05 -0400147 if (lib80211_wep_build_iv(skb, hdr_len, NULL, 0, priv))
Johannes Berga4bf26f2005-12-31 11:35:20 +0100148 return -1;
YOSHIFUJI Hideaki64265652007-02-09 23:24:46 +0900149
Johannes Berga4bf26f2005-12-31 11:35:20 +0100150 /* Copy the IV into the first 3 bytes of the key */
Arnaldo Carvalho de Melod626f622007-03-27 18:55:52 -0300151 skb_copy_from_linear_data_offset(skb, hdr_len, key, 3);
Johannes Berga4bf26f2005-12-31 11:35:20 +0100152
Jeff Garzikb4538722005-05-12 22:48:20 -0400153 /* Copy rest of the WEP key (the secret part) */
154 memcpy(key + 3, wep->key, wep->key_len);
YOSHIFUJI Hideaki64265652007-02-09 23:24:46 +0900155
Johannes Berga4bf26f2005-12-31 11:35:20 +0100156 len = skb->len - hdr_len - 4;
157 pos = skb->data + hdr_len + 4;
158 klen = 3 + wep->key_len;
Jeff Garzikb4538722005-05-12 22:48:20 -0400159
Johannes Berga4bf26f2005-12-31 11:35:20 +0100160 /* Append little-endian CRC32 over only the data and encrypt it to produce ICV */
Jeff Garzikb4538722005-05-12 22:48:20 -0400161 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
Jeff Garzik28eb1772006-09-22 20:10:23 -0400168 crypto_blkcipher_setkey(wep->tx_tfm, key, klen);
Jens Axboefa05f122007-10-22 19:44:26 +0200169 sg_init_one(&sg, pos, len + 4);
Herbert Xuf12cc202006-08-22 20:36:13 +1000170 return crypto_blkcipher_encrypt(&desc, &sg, &sg, len + 4);
Jeff Garzikb4538722005-05-12 22:48:20 -0400171}
172
Jeff Garzikb4538722005-05-12 22:48:20 -0400173/* 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 */
John W. Linville274bfb82008-10-29 11:35:05 -0400180static int lib80211_wep_decrypt(struct sk_buff *skb, int hdr_len, void *priv)
Jeff Garzikb4538722005-05-12 22:48:20 -0400181{
John W. Linville274bfb82008-10-29 11:35:05 -0400182 struct lib80211_wep_data *wep = priv;
Jeff Garzik28eb1772006-09-22 20:10:23 -0400183 struct blkcipher_desc desc = { .tfm = wep->rx_tfm };
Jeff Garzikb4538722005-05-12 22:48:20 -0400184 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
Jeff Garzik28eb1772006-09-22 20:10:23 -0400208 crypto_blkcipher_setkey(wep->rx_tfm, key, klen);
Jens Axboefa05f122007-10-22 19:44:26 +0200209 sg_init_one(&sg, pos, plen + 4);
Herbert Xuf12cc202006-08-22 20:36:13 +1000210 if (crypto_blkcipher_decrypt(&desc, &sg, &sg, plen + 4))
211 return -7;
Jeff Garzikb4538722005-05-12 22:48:20 -0400212
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
John W. Linville274bfb82008-10-29 11:35:05 -0400231static int lib80211_wep_set_key(void *key, int len, u8 * seq, void *priv)
Jeff Garzikb4538722005-05-12 22:48:20 -0400232{
John W. Linville274bfb82008-10-29 11:35:05 -0400233 struct lib80211_wep_data *wep = priv;
Jeff Garzikb4538722005-05-12 22:48:20 -0400234
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
John W. Linville274bfb82008-10-29 11:35:05 -0400244static int lib80211_wep_get_key(void *key, int len, u8 * seq, void *priv)
Jeff Garzikb4538722005-05-12 22:48:20 -0400245{
John W. Linville274bfb82008-10-29 11:35:05 -0400246 struct lib80211_wep_data *wep = priv;
Jeff Garzikb4538722005-05-12 22:48:20 -0400247
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
John W. Linville274bfb82008-10-29 11:35:05 -0400256static char *lib80211_wep_print_stats(char *p, void *priv)
Jeff Garzikb4538722005-05-12 22:48:20 -0400257{
John W. Linville274bfb82008-10-29 11:35:05 -0400258 struct lib80211_wep_data *wep = priv;
Jeff Garzik0edd5b42005-09-07 00:48:31 -0400259 p += sprintf(p, "key[%d] alg=WEP len=%d\n", wep->key_idx, wep->key_len);
Jeff Garzikb4538722005-05-12 22:48:20 -0400260 return p;
261}
262
John W. Linville274bfb82008-10-29 11:35:05 -0400263static struct lib80211_crypto_ops lib80211_crypt_wep = {
James Ketrenos74079fd2005-09-13 17:35:21 -0500264 .name = "WEP",
John W. Linville274bfb82008-10-29 11:35:05 -0400265 .init = lib80211_wep_init,
266 .deinit = lib80211_wep_deinit,
John W. Linville274bfb82008-10-29 11:35:05 -0400267 .encrypt_mpdu = lib80211_wep_encrypt,
268 .decrypt_mpdu = lib80211_wep_decrypt,
James Ketrenos74079fd2005-09-13 17:35:21 -0500269 .encrypt_msdu = NULL,
270 .decrypt_msdu = NULL,
John W. Linville274bfb82008-10-29 11:35:05 -0400271 .set_key = lib80211_wep_set_key,
272 .get_key = lib80211_wep_get_key,
273 .print_stats = lib80211_wep_print_stats,
James Ketrenos1264fc02005-09-21 11:54:53 -0500274 .extra_mpdu_prefix_len = 4, /* IV */
275 .extra_mpdu_postfix_len = 4, /* ICV */
James Ketrenos74079fd2005-09-13 17:35:21 -0500276 .owner = THIS_MODULE,
Jeff Garzikb4538722005-05-12 22:48:20 -0400277};
278
John W. Linville274bfb82008-10-29 11:35:05 -0400279static int __init lib80211_crypto_wep_init(void)
Jeff Garzikb4538722005-05-12 22:48:20 -0400280{
John W. Linville274bfb82008-10-29 11:35:05 -0400281 return lib80211_register_crypto_ops(&lib80211_crypt_wep);
Jeff Garzikb4538722005-05-12 22:48:20 -0400282}
283
John W. Linville274bfb82008-10-29 11:35:05 -0400284static void __exit lib80211_crypto_wep_exit(void)
Jeff Garzikb4538722005-05-12 22:48:20 -0400285{
John W. Linville274bfb82008-10-29 11:35:05 -0400286 lib80211_unregister_crypto_ops(&lib80211_crypt_wep);
Jeff Garzikb4538722005-05-12 22:48:20 -0400287}
288
John W. Linville274bfb82008-10-29 11:35:05 -0400289module_init(lib80211_crypto_wep_init);
290module_exit(lib80211_crypto_wep_exit);