blob: 376c84987e4fdf8f7ff0a312c843c6974d20e0b6 [file] [log] [blame]
Jiri Bencf0706e82007-05-05 11:45:53 -07001/*
2 * Software WEP encryption implementation
3 * Copyright 2002, Jouni Malinen <jkmaline@cc.hut.fi>
4 * Copyright 2003, Instant802 Networks, Inc.
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.
9 */
10
11#include <linux/netdevice.h>
12#include <linux/types.h>
13#include <linux/random.h>
14#include <linux/compiler.h>
15#include <linux/crc32.h>
16#include <linux/crypto.h>
17#include <linux/err.h>
18#include <linux/mm.h>
Ralf Baechle11763602007-10-23 20:42:11 +020019#include <linux/scatterlist.h>
Jiri Bencf0706e82007-05-05 11:45:53 -070020
21#include <net/mac80211.h>
22#include "ieee80211_i.h"
23#include "wep.h"
24
25
26int ieee80211_wep_init(struct ieee80211_local *local)
27{
28 /* start WEP IV from a random value */
29 get_random_bytes(&local->wep_iv, WEP_IV_LEN);
30
31 local->wep_tx_tfm = crypto_alloc_blkcipher("ecb(arc4)", 0,
32 CRYPTO_ALG_ASYNC);
33 if (IS_ERR(local->wep_tx_tfm))
Jeremy Fitzhardinge023a04b2008-07-14 12:52:08 -070034 return PTR_ERR(local->wep_tx_tfm);
Jiri Bencf0706e82007-05-05 11:45:53 -070035
36 local->wep_rx_tfm = crypto_alloc_blkcipher("ecb(arc4)", 0,
37 CRYPTO_ALG_ASYNC);
38 if (IS_ERR(local->wep_rx_tfm)) {
39 crypto_free_blkcipher(local->wep_tx_tfm);
Jeremy Fitzhardinge023a04b2008-07-14 12:52:08 -070040 return PTR_ERR(local->wep_rx_tfm);
Jiri Bencf0706e82007-05-05 11:45:53 -070041 }
42
43 return 0;
44}
45
46void ieee80211_wep_free(struct ieee80211_local *local)
47{
48 crypto_free_blkcipher(local->wep_tx_tfm);
49 crypto_free_blkcipher(local->wep_rx_tfm);
50}
51
52static inline int ieee80211_wep_weak_iv(u32 iv, int keylen)
53{
54 /* Fluhrer, Mantin, and Shamir have reported weaknesses in the
55 * key scheduling algorithm of RC4. At least IVs (KeyByte + 3,
56 * 0xff, N) can be used to speedup attacks, so avoid using them. */
57 if ((iv & 0xff00) == 0xff00) {
58 u8 B = (iv >> 16) & 0xff;
59 if (B >= 3 && B < 3 + keylen)
60 return 1;
61 }
62 return 0;
63}
64
65
Johannes Berg4f0d18e2007-09-26 15:19:40 +020066static void ieee80211_wep_get_iv(struct ieee80211_local *local,
67 struct ieee80211_key *key, u8 *iv)
Jiri Bencf0706e82007-05-05 11:45:53 -070068{
69 local->wep_iv++;
Johannes Berg8f20fc22007-08-28 17:01:54 -040070 if (ieee80211_wep_weak_iv(local->wep_iv, key->conf.keylen))
Jiri Bencf0706e82007-05-05 11:45:53 -070071 local->wep_iv += 0x0100;
72
73 if (!iv)
74 return;
75
76 *iv++ = (local->wep_iv >> 16) & 0xff;
77 *iv++ = (local->wep_iv >> 8) & 0xff;
78 *iv++ = local->wep_iv & 0xff;
Johannes Berg8f20fc22007-08-28 17:01:54 -040079 *iv++ = key->conf.keyidx << 6;
Jiri Bencf0706e82007-05-05 11:45:53 -070080}
81
82
Johannes Berg6a22a592007-09-26 15:19:41 +020083static u8 *ieee80211_wep_add_iv(struct ieee80211_local *local,
84 struct sk_buff *skb,
85 struct ieee80211_key *key)
Jiri Bencf0706e82007-05-05 11:45:53 -070086{
Harvey Harrison70217d72008-06-22 16:45:23 -070087 struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
88 unsigned int hdrlen;
Jiri Bencf0706e82007-05-05 11:45:53 -070089 u8 *newhdr;
90
Harvey Harrison70217d72008-06-22 16:45:23 -070091 hdr->frame_control |= cpu_to_le16(IEEE80211_FCTL_PROTECTED);
Jiri Bencf0706e82007-05-05 11:45:53 -070092
Johannes Berg23c07522008-05-29 10:38:53 +020093 if (WARN_ON(skb_tailroom(skb) < WEP_ICV_LEN ||
94 skb_headroom(skb) < WEP_IV_LEN))
95 return NULL;
Jiri Bencf0706e82007-05-05 11:45:53 -070096
Harvey Harrison70217d72008-06-22 16:45:23 -070097 hdrlen = ieee80211_hdrlen(hdr->frame_control);
Jiri Bencf0706e82007-05-05 11:45:53 -070098 newhdr = skb_push(skb, WEP_IV_LEN);
99 memmove(newhdr, newhdr + WEP_IV_LEN, hdrlen);
100 ieee80211_wep_get_iv(local, key, newhdr + hdrlen);
101 return newhdr + hdrlen;
102}
103
104
Johannes Berg4f0d18e2007-09-26 15:19:40 +0200105static void ieee80211_wep_remove_iv(struct ieee80211_local *local,
106 struct sk_buff *skb,
107 struct ieee80211_key *key)
Jiri Bencf0706e82007-05-05 11:45:53 -0700108{
Harvey Harrison70217d72008-06-22 16:45:23 -0700109 struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
110 unsigned int hdrlen;
Jiri Bencf0706e82007-05-05 11:45:53 -0700111
Harvey Harrison70217d72008-06-22 16:45:23 -0700112 hdrlen = ieee80211_hdrlen(hdr->frame_control);
Jiri Bencf0706e82007-05-05 11:45:53 -0700113 memmove(skb->data + WEP_IV_LEN, skb->data, hdrlen);
114 skb_pull(skb, WEP_IV_LEN);
115}
116
117
118/* Perform WEP encryption using given key. data buffer must have tailroom
119 * for 4-byte ICV. data_len must not include this ICV. Note: this function
120 * does _not_ add IV. data = RC4(data | CRC32(data)) */
121void ieee80211_wep_encrypt_data(struct crypto_blkcipher *tfm, u8 *rc4key,
122 size_t klen, u8 *data, size_t data_len)
123{
124 struct blkcipher_desc desc = { .tfm = tfm };
125 struct scatterlist sg;
126 __le32 *icv;
127
128 icv = (__le32 *)(data + data_len);
129 *icv = cpu_to_le32(~crc32_le(~0, data, data_len));
130
131 crypto_blkcipher_setkey(tfm, rc4key, klen);
Jens Axboefa05f122007-10-22 19:44:26 +0200132 sg_init_one(&sg, data, data_len + WEP_ICV_LEN);
Jiri Bencf0706e82007-05-05 11:45:53 -0700133 crypto_blkcipher_encrypt(&desc, &sg, &sg, sg.length);
134}
135
136
137/* Perform WEP encryption on given skb. 4 bytes of extra space (IV) in the
138 * beginning of the buffer 4 bytes of extra space (ICV) in the end of the
139 * buffer will be added. Both IV and ICV will be transmitted, so the
140 * payload length increases with 8 bytes.
141 *
142 * WEP frame payload: IV + TX key idx, RC4(data), ICV = RC4(CRC32(data))
143 */
144int ieee80211_wep_encrypt(struct ieee80211_local *local, struct sk_buff *skb,
145 struct ieee80211_key *key)
146{
147 u32 klen;
148 u8 *rc4key, *iv;
149 size_t len;
150
Johannes Berg8f20fc22007-08-28 17:01:54 -0400151 if (!key || key->conf.alg != ALG_WEP)
Jiri Bencf0706e82007-05-05 11:45:53 -0700152 return -1;
153
Johannes Berg8f20fc22007-08-28 17:01:54 -0400154 klen = 3 + key->conf.keylen;
Jiri Bencf0706e82007-05-05 11:45:53 -0700155 rc4key = kmalloc(klen, GFP_ATOMIC);
156 if (!rc4key)
157 return -1;
158
159 iv = ieee80211_wep_add_iv(local, skb, key);
160 if (!iv) {
161 kfree(rc4key);
162 return -1;
163 }
164
165 len = skb->len - (iv + WEP_IV_LEN - skb->data);
166
167 /* Prepend 24-bit IV to RC4 key */
168 memcpy(rc4key, iv, 3);
169
170 /* Copy rest of the WEP key (the secret part) */
Johannes Berg8f20fc22007-08-28 17:01:54 -0400171 memcpy(rc4key + 3, key->conf.key, key->conf.keylen);
Jiri Bencf0706e82007-05-05 11:45:53 -0700172
173 /* Add room for ICV */
174 skb_put(skb, WEP_ICV_LEN);
175
176 ieee80211_wep_encrypt_data(local->wep_tx_tfm, rc4key, klen,
177 iv + WEP_IV_LEN, len);
178
179 kfree(rc4key);
180
181 return 0;
182}
183
184
185/* Perform WEP decryption using given key. data buffer includes encrypted
186 * payload, including 4-byte ICV, but _not_ IV. data_len must not include ICV.
187 * Return 0 on success and -1 on ICV mismatch. */
188int ieee80211_wep_decrypt_data(struct crypto_blkcipher *tfm, u8 *rc4key,
189 size_t klen, u8 *data, size_t data_len)
190{
191 struct blkcipher_desc desc = { .tfm = tfm };
192 struct scatterlist sg;
193 __le32 crc;
194
195 crypto_blkcipher_setkey(tfm, rc4key, klen);
Jens Axboefa05f122007-10-22 19:44:26 +0200196 sg_init_one(&sg, data, data_len + WEP_ICV_LEN);
Jiri Bencf0706e82007-05-05 11:45:53 -0700197 crypto_blkcipher_decrypt(&desc, &sg, &sg, sg.length);
198
199 crc = cpu_to_le32(~crc32_le(~0, data, data_len));
200 if (memcmp(&crc, data + data_len, WEP_ICV_LEN) != 0)
201 /* ICV mismatch */
202 return -1;
203
204 return 0;
205}
206
207
208/* Perform WEP decryption on given skb. Buffer includes whole WEP part of
209 * the frame: IV (4 bytes), encrypted payload (including SNAP header),
210 * ICV (4 bytes). skb->len includes both IV and ICV.
211 *
212 * Returns 0 if frame was decrypted successfully and ICV was correct and -1 on
213 * failure. If frame is OK, IV and ICV will be removed, i.e., decrypted payload
214 * is moved to the beginning of the skb and skb length will be reduced.
215 */
216int ieee80211_wep_decrypt(struct ieee80211_local *local, struct sk_buff *skb,
217 struct ieee80211_key *key)
218{
219 u32 klen;
220 u8 *rc4key;
221 u8 keyidx;
Harvey Harrison70217d72008-06-22 16:45:23 -0700222 struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
223 unsigned int hdrlen;
Jiri Bencf0706e82007-05-05 11:45:53 -0700224 size_t len;
225 int ret = 0;
226
Harvey Harrison70217d72008-06-22 16:45:23 -0700227 if (!ieee80211_has_protected(hdr->frame_control))
Jiri Bencf0706e82007-05-05 11:45:53 -0700228 return -1;
229
Harvey Harrison70217d72008-06-22 16:45:23 -0700230 hdrlen = ieee80211_hdrlen(hdr->frame_control);
Harvey Harrisond2984872008-07-15 18:44:10 -0700231 if (skb->len < hdrlen + WEP_IV_LEN + WEP_ICV_LEN)
Jiri Bencf0706e82007-05-05 11:45:53 -0700232 return -1;
233
Harvey Harrisond2984872008-07-15 18:44:10 -0700234 len = skb->len - hdrlen - WEP_IV_LEN - WEP_ICV_LEN;
Jiri Bencf0706e82007-05-05 11:45:53 -0700235
236 keyidx = skb->data[hdrlen + 3] >> 6;
237
Johannes Berg8f20fc22007-08-28 17:01:54 -0400238 if (!key || keyidx != key->conf.keyidx || key->conf.alg != ALG_WEP)
Jiri Bencf0706e82007-05-05 11:45:53 -0700239 return -1;
240
Johannes Berg8f20fc22007-08-28 17:01:54 -0400241 klen = 3 + key->conf.keylen;
Jiri Bencf0706e82007-05-05 11:45:53 -0700242
243 rc4key = kmalloc(klen, GFP_ATOMIC);
244 if (!rc4key)
245 return -1;
246
247 /* Prepend 24-bit IV to RC4 key */
248 memcpy(rc4key, skb->data + hdrlen, 3);
249
250 /* Copy rest of the WEP key (the secret part) */
Johannes Berg8f20fc22007-08-28 17:01:54 -0400251 memcpy(rc4key + 3, key->conf.key, key->conf.keylen);
Jiri Bencf0706e82007-05-05 11:45:53 -0700252
253 if (ieee80211_wep_decrypt_data(local->wep_rx_tfm, rc4key, klen,
254 skb->data + hdrlen + WEP_IV_LEN,
Johannes Bergf4ea83d2008-06-30 15:10:46 +0200255 len))
Jiri Bencf0706e82007-05-05 11:45:53 -0700256 ret = -1;
Jiri Bencf0706e82007-05-05 11:45:53 -0700257
258 kfree(rc4key);
259
260 /* Trim ICV */
261 skb_trim(skb, skb->len - WEP_ICV_LEN);
262
263 /* Remove IV */
264 memmove(skb->data + WEP_IV_LEN, skb->data, hdrlen);
265 skb_pull(skb, WEP_IV_LEN);
266
267 return ret;
268}
269
270
Jiri Bencf0706e82007-05-05 11:45:53 -0700271u8 * ieee80211_wep_is_weak_iv(struct sk_buff *skb, struct ieee80211_key *key)
272{
Harvey Harrison70217d72008-06-22 16:45:23 -0700273 struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
274 unsigned int hdrlen;
Jiri Bencf0706e82007-05-05 11:45:53 -0700275 u8 *ivpos;
276 u32 iv;
277
Harvey Harrison70217d72008-06-22 16:45:23 -0700278 if (!ieee80211_has_protected(hdr->frame_control))
Jiri Bencf0706e82007-05-05 11:45:53 -0700279 return NULL;
280
Harvey Harrison70217d72008-06-22 16:45:23 -0700281 hdrlen = ieee80211_hdrlen(hdr->frame_control);
Jiri Bencf0706e82007-05-05 11:45:53 -0700282 ivpos = skb->data + hdrlen;
283 iv = (ivpos[0] << 16) | (ivpos[1] << 8) | ivpos[2];
284
Johannes Berg8f20fc22007-08-28 17:01:54 -0400285 if (ieee80211_wep_weak_iv(iv, key->conf.keylen))
Jiri Bencf0706e82007-05-05 11:45:53 -0700286 return ivpos;
287
288 return NULL;
289}
Johannes Berg4f0d18e2007-09-26 15:19:40 +0200290
Johannes Berg9ae54c82008-01-31 19:48:20 +0100291ieee80211_rx_result
Johannes Berg5cf121c2008-02-25 16:27:43 +0100292ieee80211_crypto_wep_decrypt(struct ieee80211_rx_data *rx)
Johannes Berg4f0d18e2007-09-26 15:19:40 +0200293{
Harvey Harrison358c8d92008-07-15 18:44:13 -0700294 struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)rx->skb->data;
295
296 if (!ieee80211_is_data(hdr->frame_control) &&
297 !ieee80211_is_auth(hdr->frame_control))
Johannes Berg9ae54c82008-01-31 19:48:20 +0100298 return RX_CONTINUE;
Johannes Berg4f0d18e2007-09-26 15:19:40 +0200299
Johannes Berg5cf121c2008-02-25 16:27:43 +0100300 if (!(rx->status->flag & RX_FLAG_DECRYPTED)) {
Johannes Bergf4ea83d2008-06-30 15:10:46 +0200301 if (ieee80211_wep_decrypt(rx->local, rx->skb, rx->key))
Johannes Berge4c26ad2008-01-31 19:48:21 +0100302 return RX_DROP_UNUSABLE;
Johannes Berg5cf121c2008-02-25 16:27:43 +0100303 } else if (!(rx->status->flag & RX_FLAG_IV_STRIPPED)) {
Johannes Berg4f0d18e2007-09-26 15:19:40 +0200304 ieee80211_wep_remove_iv(rx->local, rx->skb, rx->key);
305 /* remove ICV */
Harvey Harrisond2984872008-07-15 18:44:10 -0700306 skb_trim(rx->skb, rx->skb->len - WEP_ICV_LEN);
Johannes Berg4f0d18e2007-09-26 15:19:40 +0200307 }
308
Johannes Berg9ae54c82008-01-31 19:48:20 +0100309 return RX_CONTINUE;
Johannes Berg4f0d18e2007-09-26 15:19:40 +0200310}
Johannes Berg6a22a592007-09-26 15:19:41 +0200311
Johannes Berg5cf121c2008-02-25 16:27:43 +0100312static int wep_encrypt_skb(struct ieee80211_tx_data *tx, struct sk_buff *skb)
Johannes Berg6a22a592007-09-26 15:19:41 +0200313{
Johannes Berge039fa42008-05-15 12:55:29 +0200314 struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
315
316 info->control.iv_len = WEP_IV_LEN;
317 info->control.icv_len = WEP_ICV_LEN;
318
Johannes Berg6a22a592007-09-26 15:19:41 +0200319 if (!(tx->key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE)) {
320 if (ieee80211_wep_encrypt(tx->local, skb, tx->key))
321 return -1;
322 } else {
Pavel Roskin2b212142008-06-02 07:54:50 -0400323 info->control.hw_key = &tx->key->conf;
Johannes Berg6a22a592007-09-26 15:19:41 +0200324 if (tx->key->conf.flags & IEEE80211_KEY_FLAG_GENERATE_IV) {
325 if (!ieee80211_wep_add_iv(tx->local, skb, tx->key))
326 return -1;
327 }
328 }
329 return 0;
330}
331
Johannes Berg9ae54c82008-01-31 19:48:20 +0100332ieee80211_tx_result
Johannes Berg5cf121c2008-02-25 16:27:43 +0100333ieee80211_crypto_wep_encrypt(struct ieee80211_tx_data *tx)
Johannes Berg6a22a592007-09-26 15:19:41 +0200334{
Johannes Berg5cf121c2008-02-25 16:27:43 +0100335 ieee80211_tx_set_protected(tx);
Johannes Berg6a22a592007-09-26 15:19:41 +0200336
337 if (wep_encrypt_skb(tx, tx->skb) < 0) {
338 I802_DEBUG_INC(tx->local->tx_handlers_drop_wep);
Johannes Berg9ae54c82008-01-31 19:48:20 +0100339 return TX_DROP;
Johannes Berg6a22a592007-09-26 15:19:41 +0200340 }
341
Johannes Berg5cf121c2008-02-25 16:27:43 +0100342 if (tx->extra_frag) {
Johannes Berg6a22a592007-09-26 15:19:41 +0200343 int i;
Johannes Berg5cf121c2008-02-25 16:27:43 +0100344 for (i = 0; i < tx->num_extra_frag; i++) {
345 if (wep_encrypt_skb(tx, tx->extra_frag[i]) < 0) {
Johannes Berg6a22a592007-09-26 15:19:41 +0200346 I802_DEBUG_INC(tx->local->
347 tx_handlers_drop_wep);
Johannes Berg9ae54c82008-01-31 19:48:20 +0100348 return TX_DROP;
Johannes Berg6a22a592007-09-26 15:19:41 +0200349 }
350 }
351 }
352
Johannes Berg9ae54c82008-01-31 19:48:20 +0100353 return TX_CONTINUE;
Johannes Berg6a22a592007-09-26 15:19:41 +0200354}