blob: 2ff6d1e3ed21565524fc55c724b24bbee67dd0c6 [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>
Tejun Heo5a0e3ad2010-03-24 17:04:11 +090020#include <linux/slab.h>
Ivan Kuten860c6e62008-11-24 15:17:54 -050021#include <asm/unaligned.h>
Jiri Bencf0706e82007-05-05 11:45:53 -070022
23#include <net/mac80211.h>
24#include "ieee80211_i.h"
25#include "wep.h"
26
27
28int ieee80211_wep_init(struct ieee80211_local *local)
29{
30 /* start WEP IV from a random value */
31 get_random_bytes(&local->wep_iv, WEP_IV_LEN);
32
33 local->wep_tx_tfm = crypto_alloc_blkcipher("ecb(arc4)", 0,
34 CRYPTO_ALG_ASYNC);
John W. Linville088c8722010-07-15 16:16:17 -040035 if (IS_ERR(local->wep_tx_tfm)) {
36 local->wep_rx_tfm = ERR_PTR(-EINVAL);
Jeremy Fitzhardinge023a04b2008-07-14 12:52:08 -070037 return PTR_ERR(local->wep_tx_tfm);
John W. Linville088c8722010-07-15 16:16:17 -040038 }
Jiri Bencf0706e82007-05-05 11:45:53 -070039
40 local->wep_rx_tfm = crypto_alloc_blkcipher("ecb(arc4)", 0,
41 CRYPTO_ALG_ASYNC);
42 if (IS_ERR(local->wep_rx_tfm)) {
43 crypto_free_blkcipher(local->wep_tx_tfm);
John W. Linville088c8722010-07-15 16:16:17 -040044 local->wep_tx_tfm = ERR_PTR(-EINVAL);
Jeremy Fitzhardinge023a04b2008-07-14 12:52:08 -070045 return PTR_ERR(local->wep_rx_tfm);
Jiri Bencf0706e82007-05-05 11:45:53 -070046 }
47
48 return 0;
49}
50
51void ieee80211_wep_free(struct ieee80211_local *local)
52{
John W. Linville34731872010-07-07 15:07:49 -040053 if (!IS_ERR(local->wep_tx_tfm))
54 crypto_free_blkcipher(local->wep_tx_tfm);
55 if (!IS_ERR(local->wep_rx_tfm))
56 crypto_free_blkcipher(local->wep_rx_tfm);
Jiri Bencf0706e82007-05-05 11:45:53 -070057}
58
Johannes Bergc6a1fa12008-10-07 12:04:32 +020059static inline bool ieee80211_wep_weak_iv(u32 iv, int keylen)
Jiri Bencf0706e82007-05-05 11:45:53 -070060{
Johannes Bergc6a1fa12008-10-07 12:04:32 +020061 /*
62 * Fluhrer, Mantin, and Shamir have reported weaknesses in the
Jiri Bencf0706e82007-05-05 11:45:53 -070063 * key scheduling algorithm of RC4. At least IVs (KeyByte + 3,
Johannes Bergc6a1fa12008-10-07 12:04:32 +020064 * 0xff, N) can be used to speedup attacks, so avoid using them.
65 */
Jiri Bencf0706e82007-05-05 11:45:53 -070066 if ((iv & 0xff00) == 0xff00) {
67 u8 B = (iv >> 16) & 0xff;
68 if (B >= 3 && B < 3 + keylen)
Johannes Bergc6a1fa12008-10-07 12:04:32 +020069 return true;
Jiri Bencf0706e82007-05-05 11:45:53 -070070 }
Johannes Bergc6a1fa12008-10-07 12:04:32 +020071 return false;
Jiri Bencf0706e82007-05-05 11:45:53 -070072}
73
74
Johannes Berg4f0d18e2007-09-26 15:19:40 +020075static void ieee80211_wep_get_iv(struct ieee80211_local *local,
Johannes Bergc9cf0122009-07-07 03:45:18 +020076 int keylen, int keyidx, u8 *iv)
Jiri Bencf0706e82007-05-05 11:45:53 -070077{
78 local->wep_iv++;
Johannes Bergc9cf0122009-07-07 03:45:18 +020079 if (ieee80211_wep_weak_iv(local->wep_iv, keylen))
Jiri Bencf0706e82007-05-05 11:45:53 -070080 local->wep_iv += 0x0100;
81
82 if (!iv)
83 return;
84
85 *iv++ = (local->wep_iv >> 16) & 0xff;
86 *iv++ = (local->wep_iv >> 8) & 0xff;
87 *iv++ = local->wep_iv & 0xff;
Johannes Bergc9cf0122009-07-07 03:45:18 +020088 *iv++ = keyidx << 6;
Jiri Bencf0706e82007-05-05 11:45:53 -070089}
90
91
Johannes Berg6a22a592007-09-26 15:19:41 +020092static u8 *ieee80211_wep_add_iv(struct ieee80211_local *local,
93 struct sk_buff *skb,
Johannes Bergc9cf0122009-07-07 03:45:18 +020094 int keylen, int keyidx)
Jiri Bencf0706e82007-05-05 11:45:53 -070095{
Harvey Harrison70217d72008-06-22 16:45:23 -070096 struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
97 unsigned int hdrlen;
Jiri Bencf0706e82007-05-05 11:45:53 -070098 u8 *newhdr;
99
Harvey Harrison70217d72008-06-22 16:45:23 -0700100 hdr->frame_control |= cpu_to_le16(IEEE80211_FCTL_PROTECTED);
Jiri Bencf0706e82007-05-05 11:45:53 -0700101
Johannes Berg23c07522008-05-29 10:38:53 +0200102 if (WARN_ON(skb_tailroom(skb) < WEP_ICV_LEN ||
103 skb_headroom(skb) < WEP_IV_LEN))
104 return NULL;
Jiri Bencf0706e82007-05-05 11:45:53 -0700105
Harvey Harrison70217d72008-06-22 16:45:23 -0700106 hdrlen = ieee80211_hdrlen(hdr->frame_control);
Jiri Bencf0706e82007-05-05 11:45:53 -0700107 newhdr = skb_push(skb, WEP_IV_LEN);
108 memmove(newhdr, newhdr + WEP_IV_LEN, hdrlen);
Johannes Bergc9cf0122009-07-07 03:45:18 +0200109 ieee80211_wep_get_iv(local, keylen, keyidx, newhdr + hdrlen);
Jiri Bencf0706e82007-05-05 11:45:53 -0700110 return newhdr + hdrlen;
111}
112
113
Johannes Berg4f0d18e2007-09-26 15:19:40 +0200114static void ieee80211_wep_remove_iv(struct ieee80211_local *local,
115 struct sk_buff *skb,
116 struct ieee80211_key *key)
Jiri Bencf0706e82007-05-05 11:45:53 -0700117{
Harvey Harrison70217d72008-06-22 16:45:23 -0700118 struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
119 unsigned int hdrlen;
Jiri Bencf0706e82007-05-05 11:45:53 -0700120
Harvey Harrison70217d72008-06-22 16:45:23 -0700121 hdrlen = ieee80211_hdrlen(hdr->frame_control);
Jiri Bencf0706e82007-05-05 11:45:53 -0700122 memmove(skb->data + WEP_IV_LEN, skb->data, hdrlen);
123 skb_pull(skb, WEP_IV_LEN);
124}
125
126
127/* Perform WEP encryption using given key. data buffer must have tailroom
128 * for 4-byte ICV. data_len must not include this ICV. Note: this function
129 * does _not_ add IV. data = RC4(data | CRC32(data)) */
John W. Linville34731872010-07-07 15:07:49 -0400130int ieee80211_wep_encrypt_data(struct crypto_blkcipher *tfm, u8 *rc4key,
131 size_t klen, u8 *data, size_t data_len)
Jiri Bencf0706e82007-05-05 11:45:53 -0700132{
133 struct blkcipher_desc desc = { .tfm = tfm };
134 struct scatterlist sg;
Ivan Kuten860c6e62008-11-24 15:17:54 -0500135 __le32 icv;
Jiri Bencf0706e82007-05-05 11:45:53 -0700136
John W. Linville34731872010-07-07 15:07:49 -0400137 if (IS_ERR(tfm))
138 return -1;
139
Ivan Kuten860c6e62008-11-24 15:17:54 -0500140 icv = cpu_to_le32(~crc32_le(~0, data, data_len));
141 put_unaligned(icv, (__le32 *)(data + data_len));
Jiri Bencf0706e82007-05-05 11:45:53 -0700142
143 crypto_blkcipher_setkey(tfm, rc4key, klen);
Jens Axboefa05f122007-10-22 19:44:26 +0200144 sg_init_one(&sg, data, data_len + WEP_ICV_LEN);
Jiri Bencf0706e82007-05-05 11:45:53 -0700145 crypto_blkcipher_encrypt(&desc, &sg, &sg, sg.length);
John W. Linville34731872010-07-07 15:07:49 -0400146
147 return 0;
Jiri Bencf0706e82007-05-05 11:45:53 -0700148}
149
150
151/* Perform WEP encryption on given skb. 4 bytes of extra space (IV) in the
152 * beginning of the buffer 4 bytes of extra space (ICV) in the end of the
153 * buffer will be added. Both IV and ICV will be transmitted, so the
154 * payload length increases with 8 bytes.
155 *
156 * WEP frame payload: IV + TX key idx, RC4(data), ICV = RC4(CRC32(data))
157 */
Johannes Bergfffd0932009-07-08 14:22:54 +0200158int ieee80211_wep_encrypt(struct ieee80211_local *local,
159 struct sk_buff *skb,
160 const u8 *key, int keylen, int keyidx)
Jiri Bencf0706e82007-05-05 11:45:53 -0700161{
Johannes Bergc9cf0122009-07-07 03:45:18 +0200162 u8 *iv;
Jiri Bencf0706e82007-05-05 11:45:53 -0700163 size_t len;
Johannes Bergc9cf0122009-07-07 03:45:18 +0200164 u8 rc4key[3 + WLAN_KEY_LEN_WEP104];
Jiri Bencf0706e82007-05-05 11:45:53 -0700165
Johannes Bergc9cf0122009-07-07 03:45:18 +0200166 iv = ieee80211_wep_add_iv(local, skb, keylen, keyidx);
167 if (!iv)
Jiri Bencf0706e82007-05-05 11:45:53 -0700168 return -1;
169
Jiri Bencf0706e82007-05-05 11:45:53 -0700170 len = skb->len - (iv + WEP_IV_LEN - skb->data);
171
172 /* Prepend 24-bit IV to RC4 key */
173 memcpy(rc4key, iv, 3);
174
175 /* Copy rest of the WEP key (the secret part) */
Johannes Bergc9cf0122009-07-07 03:45:18 +0200176 memcpy(rc4key + 3, key, keylen);
Jiri Bencf0706e82007-05-05 11:45:53 -0700177
178 /* Add room for ICV */
179 skb_put(skb, WEP_ICV_LEN);
180
John W. Linville34731872010-07-07 15:07:49 -0400181 return ieee80211_wep_encrypt_data(local->wep_tx_tfm, rc4key, keylen + 3,
182 iv + WEP_IV_LEN, len);
Jiri Bencf0706e82007-05-05 11:45:53 -0700183}
184
185
186/* Perform WEP decryption using given key. data buffer includes encrypted
187 * payload, including 4-byte ICV, but _not_ IV. data_len must not include ICV.
188 * Return 0 on success and -1 on ICV mismatch. */
189int ieee80211_wep_decrypt_data(struct crypto_blkcipher *tfm, u8 *rc4key,
190 size_t klen, u8 *data, size_t data_len)
191{
192 struct blkcipher_desc desc = { .tfm = tfm };
193 struct scatterlist sg;
194 __le32 crc;
195
John W. Linville34731872010-07-07 15:07:49 -0400196 if (IS_ERR(tfm))
197 return -1;
198
Jiri Bencf0706e82007-05-05 11:45:53 -0700199 crypto_blkcipher_setkey(tfm, rc4key, klen);
Jens Axboefa05f122007-10-22 19:44:26 +0200200 sg_init_one(&sg, data, data_len + WEP_ICV_LEN);
Jiri Bencf0706e82007-05-05 11:45:53 -0700201 crypto_blkcipher_decrypt(&desc, &sg, &sg, sg.length);
202
203 crc = cpu_to_le32(~crc32_le(~0, data, data_len));
204 if (memcmp(&crc, data + data_len, WEP_ICV_LEN) != 0)
205 /* ICV mismatch */
206 return -1;
207
208 return 0;
209}
210
211
212/* Perform WEP decryption on given skb. Buffer includes whole WEP part of
213 * the frame: IV (4 bytes), encrypted payload (including SNAP header),
214 * ICV (4 bytes). skb->len includes both IV and ICV.
215 *
216 * Returns 0 if frame was decrypted successfully and ICV was correct and -1 on
217 * failure. If frame is OK, IV and ICV will be removed, i.e., decrypted payload
218 * is moved to the beginning of the skb and skb length will be reduced.
219 */
Johannes Bergc9cf0122009-07-07 03:45:18 +0200220static int ieee80211_wep_decrypt(struct ieee80211_local *local,
221 struct sk_buff *skb,
222 struct ieee80211_key *key)
Jiri Bencf0706e82007-05-05 11:45:53 -0700223{
224 u32 klen;
Johannes Berg730bd832010-10-10 18:52:10 +0200225 u8 rc4key[3 + WLAN_KEY_LEN_WEP104];
Jiri Bencf0706e82007-05-05 11:45:53 -0700226 u8 keyidx;
Harvey Harrison70217d72008-06-22 16:45:23 -0700227 struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
228 unsigned int hdrlen;
Jiri Bencf0706e82007-05-05 11:45:53 -0700229 size_t len;
230 int ret = 0;
231
Harvey Harrison70217d72008-06-22 16:45:23 -0700232 if (!ieee80211_has_protected(hdr->frame_control))
Jiri Bencf0706e82007-05-05 11:45:53 -0700233 return -1;
234
Harvey Harrison70217d72008-06-22 16:45:23 -0700235 hdrlen = ieee80211_hdrlen(hdr->frame_control);
Harvey Harrisond2984872008-07-15 18:44:10 -0700236 if (skb->len < hdrlen + WEP_IV_LEN + WEP_ICV_LEN)
Jiri Bencf0706e82007-05-05 11:45:53 -0700237 return -1;
238
Harvey Harrisond2984872008-07-15 18:44:10 -0700239 len = skb->len - hdrlen - WEP_IV_LEN - WEP_ICV_LEN;
Jiri Bencf0706e82007-05-05 11:45:53 -0700240
241 keyidx = skb->data[hdrlen + 3] >> 6;
242
Johannes Berg97359d12010-08-10 09:46:38 +0200243 if (!key || keyidx != key->conf.keyidx)
Jiri Bencf0706e82007-05-05 11:45:53 -0700244 return -1;
245
Johannes Berg8f20fc22007-08-28 17:01:54 -0400246 klen = 3 + key->conf.keylen;
Jiri Bencf0706e82007-05-05 11:45:53 -0700247
Jiri Bencf0706e82007-05-05 11:45:53 -0700248 /* Prepend 24-bit IV to RC4 key */
249 memcpy(rc4key, skb->data + hdrlen, 3);
250
251 /* Copy rest of the WEP key (the secret part) */
Johannes Berg8f20fc22007-08-28 17:01:54 -0400252 memcpy(rc4key + 3, key->conf.key, key->conf.keylen);
Jiri Bencf0706e82007-05-05 11:45:53 -0700253
254 if (ieee80211_wep_decrypt_data(local->wep_rx_tfm, rc4key, klen,
255 skb->data + hdrlen + WEP_IV_LEN,
Johannes Bergf4ea83d2008-06-30 15:10:46 +0200256 len))
Jiri Bencf0706e82007-05-05 11:45:53 -0700257 ret = -1;
Jiri Bencf0706e82007-05-05 11:45:53 -0700258
Jiri Bencf0706e82007-05-05 11:45:53 -0700259 /* Trim ICV */
260 skb_trim(skb, skb->len - WEP_ICV_LEN);
261
262 /* Remove IV */
263 memmove(skb->data + WEP_IV_LEN, skb->data, hdrlen);
264 skb_pull(skb, WEP_IV_LEN);
265
266 return ret;
267}
268
269
Johannes Bergc6a1fa12008-10-07 12:04:32 +0200270bool ieee80211_wep_is_weak_iv(struct sk_buff *skb, struct ieee80211_key *key)
Jiri Bencf0706e82007-05-05 11:45:53 -0700271{
Harvey Harrison70217d72008-06-22 16:45:23 -0700272 struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
273 unsigned int hdrlen;
Jiri Bencf0706e82007-05-05 11:45:53 -0700274 u8 *ivpos;
275 u32 iv;
276
Harvey Harrison70217d72008-06-22 16:45:23 -0700277 if (!ieee80211_has_protected(hdr->frame_control))
Johannes Bergc6a1fa12008-10-07 12:04:32 +0200278 return false;
Jiri Bencf0706e82007-05-05 11:45:53 -0700279
Harvey Harrison70217d72008-06-22 16:45:23 -0700280 hdrlen = ieee80211_hdrlen(hdr->frame_control);
Jiri Bencf0706e82007-05-05 11:45:53 -0700281 ivpos = skb->data + hdrlen;
282 iv = (ivpos[0] << 16) | (ivpos[1] << 8) | ivpos[2];
283
Johannes Bergc6a1fa12008-10-07 12:04:32 +0200284 return ieee80211_wep_weak_iv(iv, key->conf.keylen);
Jiri Bencf0706e82007-05-05 11:45:53 -0700285}
Johannes Berg4f0d18e2007-09-26 15:19:40 +0200286
Johannes Berg9ae54c82008-01-31 19:48:20 +0100287ieee80211_rx_result
Johannes Berg5cf121c2008-02-25 16:27:43 +0100288ieee80211_crypto_wep_decrypt(struct ieee80211_rx_data *rx)
Johannes Berg4f0d18e2007-09-26 15:19:40 +0200289{
Johannes Bergeb9fb5b2009-11-16 13:58:20 +0100290 struct sk_buff *skb = rx->skb;
291 struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(skb);
292 struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
Harvey Harrison358c8d92008-07-15 18:44:13 -0700293
294 if (!ieee80211_is_data(hdr->frame_control) &&
295 !ieee80211_is_auth(hdr->frame_control))
Johannes Berg9ae54c82008-01-31 19:48:20 +0100296 return RX_CONTINUE;
Johannes Berg4f0d18e2007-09-26 15:19:40 +0200297
Johannes Bergeb9fb5b2009-11-16 13:58:20 +0100298 if (!(status->flag & RX_FLAG_DECRYPTED)) {
Johannes Bergf4ea83d2008-06-30 15:10:46 +0200299 if (ieee80211_wep_decrypt(rx->local, rx->skb, rx->key))
Johannes Berge4c26ad2008-01-31 19:48:21 +0100300 return RX_DROP_UNUSABLE;
Johannes Bergeb9fb5b2009-11-16 13:58:20 +0100301 } else if (!(status->flag & RX_FLAG_IV_STRIPPED)) {
Johannes Berg4f0d18e2007-09-26 15:19:40 +0200302 ieee80211_wep_remove_iv(rx->local, rx->skb, rx->key);
303 /* remove ICV */
Harvey Harrisond2984872008-07-15 18:44:10 -0700304 skb_trim(rx->skb, rx->skb->len - WEP_ICV_LEN);
Johannes Berg4f0d18e2007-09-26 15:19:40 +0200305 }
306
Johannes Berg9ae54c82008-01-31 19:48:20 +0100307 return RX_CONTINUE;
Johannes Berg4f0d18e2007-09-26 15:19:40 +0200308}
Johannes Berg6a22a592007-09-26 15:19:41 +0200309
Johannes Berg5cf121c2008-02-25 16:27:43 +0100310static int wep_encrypt_skb(struct ieee80211_tx_data *tx, struct sk_buff *skb)
Johannes Berg6a22a592007-09-26 15:19:41 +0200311{
Johannes Berge039fa42008-05-15 12:55:29 +0200312 struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
313
Johannes Berg813d7662010-01-17 01:47:58 +0100314 if (!info->control.hw_key) {
Johannes Bergc9cf0122009-07-07 03:45:18 +0200315 if (ieee80211_wep_encrypt(tx->local, skb, tx->key->conf.key,
316 tx->key->conf.keylen,
317 tx->key->conf.keyidx))
Johannes Berg6a22a592007-09-26 15:19:41 +0200318 return -1;
John W. Linvillee4fca002010-01-22 12:33:09 -0500319 } else if (info->control.hw_key->flags &
320 IEEE80211_KEY_FLAG_GENERATE_IV) {
Johannes Berg813d7662010-01-17 01:47:58 +0100321 if (!ieee80211_wep_add_iv(tx->local, skb,
322 tx->key->conf.keylen,
323 tx->key->conf.keyidx))
324 return -1;
325 }
326
Johannes Berg6a22a592007-09-26 15:19:41 +0200327 return 0;
328}
329
Johannes Berg9ae54c82008-01-31 19:48:20 +0100330ieee80211_tx_result
Johannes Berg5cf121c2008-02-25 16:27:43 +0100331ieee80211_crypto_wep_encrypt(struct ieee80211_tx_data *tx)
Johannes Berg6a22a592007-09-26 15:19:41 +0200332{
Johannes Berg2de8e0d2009-03-23 17:28:35 +0100333 struct sk_buff *skb;
Johannes Bergc6a1fa12008-10-07 12:04:32 +0200334
Johannes Berg5cf121c2008-02-25 16:27:43 +0100335 ieee80211_tx_set_protected(tx);
Johannes Berg6a22a592007-09-26 15:19:41 +0200336
Johannes Berg2de8e0d2009-03-23 17:28:35 +0100337 skb = tx->skb;
338 do {
339 if (wep_encrypt_skb(tx, skb) < 0) {
340 I802_DEBUG_INC(tx->local->tx_handlers_drop_wep);
341 return TX_DROP;
Johannes Berg6a22a592007-09-26 15:19:41 +0200342 }
Johannes Berg2de8e0d2009-03-23 17:28:35 +0100343 } while ((skb = skb->next));
Johannes Berg6a22a592007-09-26 15:19:41 +0200344
Johannes Berg9ae54c82008-01-31 19:48:20 +0100345 return TX_CONTINUE;
Johannes Berg6a22a592007-09-26 15:19:41 +0200346}