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Jiri Bencf0706e822007-05-05 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 Bencf0706e822007-05-05 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
Felix Fietkau5f9f1812011-03-25 21:39:19 +010033 local->wep_tx_tfm = crypto_alloc_cipher("arc4", 0, CRYPTO_ALG_ASYNC);
John W. Linville088c8722010-07-15 16:16:17 -040034 if (IS_ERR(local->wep_tx_tfm)) {
35 local->wep_rx_tfm = ERR_PTR(-EINVAL);
Jeremy Fitzhardinge023a04b2008-07-14 12:52:08 -070036 return PTR_ERR(local->wep_tx_tfm);
John W. Linville088c8722010-07-15 16:16:17 -040037 }
Jiri Bencf0706e822007-05-05 11:45:53 -070038
Felix Fietkau5f9f1812011-03-25 21:39:19 +010039 local->wep_rx_tfm = crypto_alloc_cipher("arc4", 0, CRYPTO_ALG_ASYNC);
Jiri Bencf0706e822007-05-05 11:45:53 -070040 if (IS_ERR(local->wep_rx_tfm)) {
Felix Fietkau5f9f1812011-03-25 21:39:19 +010041 crypto_free_cipher(local->wep_tx_tfm);
John W. Linville088c8722010-07-15 16:16:17 -040042 local->wep_tx_tfm = ERR_PTR(-EINVAL);
Jeremy Fitzhardinge023a04b2008-07-14 12:52:08 -070043 return PTR_ERR(local->wep_rx_tfm);
Jiri Bencf0706e822007-05-05 11:45:53 -070044 }
45
46 return 0;
47}
48
49void ieee80211_wep_free(struct ieee80211_local *local)
50{
John W. Linville34731872010-07-07 15:07:49 -040051 if (!IS_ERR(local->wep_tx_tfm))
Felix Fietkau5f9f1812011-03-25 21:39:19 +010052 crypto_free_cipher(local->wep_tx_tfm);
John W. Linville34731872010-07-07 15:07:49 -040053 if (!IS_ERR(local->wep_rx_tfm))
Felix Fietkau5f9f1812011-03-25 21:39:19 +010054 crypto_free_cipher(local->wep_rx_tfm);
Jiri Bencf0706e822007-05-05 11:45:53 -070055}
56
Johannes Bergc6a1fa12008-10-07 12:04:32 +020057static inline bool ieee80211_wep_weak_iv(u32 iv, int keylen)
Jiri Bencf0706e822007-05-05 11:45:53 -070058{
Johannes Bergc6a1fa12008-10-07 12:04:32 +020059 /*
60 * Fluhrer, Mantin, and Shamir have reported weaknesses in the
Jiri Bencf0706e822007-05-05 11:45:53 -070061 * key scheduling algorithm of RC4. At least IVs (KeyByte + 3,
Johannes Bergc6a1fa12008-10-07 12:04:32 +020062 * 0xff, N) can be used to speedup attacks, so avoid using them.
63 */
Jiri Bencf0706e822007-05-05 11:45:53 -070064 if ((iv & 0xff00) == 0xff00) {
65 u8 B = (iv >> 16) & 0xff;
66 if (B >= 3 && B < 3 + keylen)
Johannes Bergc6a1fa12008-10-07 12:04:32 +020067 return true;
Jiri Bencf0706e822007-05-05 11:45:53 -070068 }
Johannes Bergc6a1fa12008-10-07 12:04:32 +020069 return false;
Jiri Bencf0706e822007-05-05 11:45:53 -070070}
71
72
Johannes Berg4f0d18e2007-09-26 15:19:40 +020073static void ieee80211_wep_get_iv(struct ieee80211_local *local,
Johannes Bergc9cf0122009-07-07 03:45:18 +020074 int keylen, int keyidx, u8 *iv)
Jiri Bencf0706e822007-05-05 11:45:53 -070075{
76 local->wep_iv++;
Johannes Bergc9cf0122009-07-07 03:45:18 +020077 if (ieee80211_wep_weak_iv(local->wep_iv, keylen))
Jiri Bencf0706e822007-05-05 11:45:53 -070078 local->wep_iv += 0x0100;
79
80 if (!iv)
81 return;
82
83 *iv++ = (local->wep_iv >> 16) & 0xff;
84 *iv++ = (local->wep_iv >> 8) & 0xff;
85 *iv++ = local->wep_iv & 0xff;
Johannes Bergc9cf0122009-07-07 03:45:18 +020086 *iv++ = keyidx << 6;
Jiri Bencf0706e822007-05-05 11:45:53 -070087}
88
89
Johannes Berg6a22a592007-09-26 15:19:41 +020090static u8 *ieee80211_wep_add_iv(struct ieee80211_local *local,
91 struct sk_buff *skb,
Johannes Bergc9cf0122009-07-07 03:45:18 +020092 int keylen, int keyidx)
Jiri Bencf0706e822007-05-05 11:45:53 -070093{
Harvey Harrison70217d72008-06-22 16:45:23 -070094 struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
95 unsigned int hdrlen;
Jiri Bencf0706e822007-05-05 11:45:53 -070096 u8 *newhdr;
97
Harvey Harrison70217d72008-06-22 16:45:23 -070098 hdr->frame_control |= cpu_to_le16(IEEE80211_FCTL_PROTECTED);
Jiri Bencf0706e822007-05-05 11:45:53 -070099
Johannes Berg23c07522008-05-29 10:38:53 +0200100 if (WARN_ON(skb_tailroom(skb) < WEP_ICV_LEN ||
101 skb_headroom(skb) < WEP_IV_LEN))
102 return NULL;
Jiri Bencf0706e822007-05-05 11:45:53 -0700103
Harvey Harrison70217d72008-06-22 16:45:23 -0700104 hdrlen = ieee80211_hdrlen(hdr->frame_control);
Jiri Bencf0706e822007-05-05 11:45:53 -0700105 newhdr = skb_push(skb, WEP_IV_LEN);
106 memmove(newhdr, newhdr + WEP_IV_LEN, hdrlen);
Johannes Bergc9cf0122009-07-07 03:45:18 +0200107 ieee80211_wep_get_iv(local, keylen, keyidx, newhdr + hdrlen);
Jiri Bencf0706e822007-05-05 11:45:53 -0700108 return newhdr + hdrlen;
109}
110
111
Johannes Berg4f0d18e2007-09-26 15:19:40 +0200112static void ieee80211_wep_remove_iv(struct ieee80211_local *local,
113 struct sk_buff *skb,
114 struct ieee80211_key *key)
Jiri Bencf0706e822007-05-05 11:45:53 -0700115{
Harvey Harrison70217d72008-06-22 16:45:23 -0700116 struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
117 unsigned int hdrlen;
Jiri Bencf0706e822007-05-05 11:45:53 -0700118
Harvey Harrison70217d72008-06-22 16:45:23 -0700119 hdrlen = ieee80211_hdrlen(hdr->frame_control);
Jiri Bencf0706e822007-05-05 11:45:53 -0700120 memmove(skb->data + WEP_IV_LEN, skb->data, hdrlen);
121 skb_pull(skb, WEP_IV_LEN);
122}
123
124
125/* Perform WEP encryption using given key. data buffer must have tailroom
126 * for 4-byte ICV. data_len must not include this ICV. Note: this function
127 * does _not_ add IV. data = RC4(data | CRC32(data)) */
Felix Fietkau5f9f1812011-03-25 21:39:19 +0100128int ieee80211_wep_encrypt_data(struct crypto_cipher *tfm, u8 *rc4key,
John W. Linville34731872010-07-07 15:07:49 -0400129 size_t klen, u8 *data, size_t data_len)
Jiri Bencf0706e822007-05-05 11:45:53 -0700130{
Ivan Kuten860c6e62008-11-24 15:17:54 -0500131 __le32 icv;
Felix Fietkau5f9f1812011-03-25 21:39:19 +0100132 int i;
Jiri Bencf0706e822007-05-05 11:45:53 -0700133
John W. Linville34731872010-07-07 15:07:49 -0400134 if (IS_ERR(tfm))
135 return -1;
136
Ivan Kuten860c6e62008-11-24 15:17:54 -0500137 icv = cpu_to_le32(~crc32_le(~0, data, data_len));
138 put_unaligned(icv, (__le32 *)(data + data_len));
Jiri Bencf0706e822007-05-05 11:45:53 -0700139
Felix Fietkau5f9f1812011-03-25 21:39:19 +0100140 crypto_cipher_setkey(tfm, rc4key, klen);
141 for (i = 0; i < data_len + WEP_ICV_LEN; i++)
142 crypto_cipher_encrypt_one(tfm, data + i, data + i);
John W. Linville34731872010-07-07 15:07:49 -0400143
144 return 0;
Jiri Bencf0706e822007-05-05 11:45:53 -0700145}
146
147
148/* Perform WEP encryption on given skb. 4 bytes of extra space (IV) in the
149 * beginning of the buffer 4 bytes of extra space (ICV) in the end of the
150 * buffer will be added. Both IV and ICV will be transmitted, so the
151 * payload length increases with 8 bytes.
152 *
153 * WEP frame payload: IV + TX key idx, RC4(data), ICV = RC4(CRC32(data))
154 */
Johannes Bergfffd0932009-07-08 14:22:54 +0200155int ieee80211_wep_encrypt(struct ieee80211_local *local,
156 struct sk_buff *skb,
157 const u8 *key, int keylen, int keyidx)
Jiri Bencf0706e822007-05-05 11:45:53 -0700158{
Johannes Bergc9cf0122009-07-07 03:45:18 +0200159 u8 *iv;
Jiri Bencf0706e822007-05-05 11:45:53 -0700160 size_t len;
Johannes Bergc9cf0122009-07-07 03:45:18 +0200161 u8 rc4key[3 + WLAN_KEY_LEN_WEP104];
Jiri Bencf0706e822007-05-05 11:45:53 -0700162
Johannes Bergc9cf0122009-07-07 03:45:18 +0200163 iv = ieee80211_wep_add_iv(local, skb, keylen, keyidx);
164 if (!iv)
Jiri Bencf0706e822007-05-05 11:45:53 -0700165 return -1;
166
Jiri Bencf0706e822007-05-05 11:45:53 -0700167 len = skb->len - (iv + WEP_IV_LEN - skb->data);
168
169 /* Prepend 24-bit IV to RC4 key */
170 memcpy(rc4key, iv, 3);
171
172 /* Copy rest of the WEP key (the secret part) */
Johannes Bergc9cf0122009-07-07 03:45:18 +0200173 memcpy(rc4key + 3, key, keylen);
Jiri Bencf0706e822007-05-05 11:45:53 -0700174
175 /* Add room for ICV */
176 skb_put(skb, WEP_ICV_LEN);
177
John W. Linville34731872010-07-07 15:07:49 -0400178 return ieee80211_wep_encrypt_data(local->wep_tx_tfm, rc4key, keylen + 3,
179 iv + WEP_IV_LEN, len);
Jiri Bencf0706e822007-05-05 11:45:53 -0700180}
181
182
183/* Perform WEP decryption using given key. data buffer includes encrypted
184 * payload, including 4-byte ICV, but _not_ IV. data_len must not include ICV.
185 * Return 0 on success and -1 on ICV mismatch. */
Felix Fietkau5f9f1812011-03-25 21:39:19 +0100186int ieee80211_wep_decrypt_data(struct crypto_cipher *tfm, u8 *rc4key,
Jiri Bencf0706e822007-05-05 11:45:53 -0700187 size_t klen, u8 *data, size_t data_len)
188{
Jiri Bencf0706e822007-05-05 11:45:53 -0700189 __le32 crc;
Felix Fietkau5f9f1812011-03-25 21:39:19 +0100190 int i;
Jiri Bencf0706e822007-05-05 11:45:53 -0700191
John W. Linville34731872010-07-07 15:07:49 -0400192 if (IS_ERR(tfm))
193 return -1;
194
Felix Fietkau5f9f1812011-03-25 21:39:19 +0100195 crypto_cipher_setkey(tfm, rc4key, klen);
196 for (i = 0; i < data_len + WEP_ICV_LEN; i++)
197 crypto_cipher_decrypt_one(tfm, data + i, data + i);
Jiri Bencf0706e822007-05-05 11:45:53 -0700198
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 */
Johannes Bergc9cf0122009-07-07 03:45:18 +0200216static int ieee80211_wep_decrypt(struct ieee80211_local *local,
217 struct sk_buff *skb,
218 struct ieee80211_key *key)
Jiri Bencf0706e822007-05-05 11:45:53 -0700219{
220 u32 klen;
Johannes Berg730bd832010-10-10 18:52:10 +0200221 u8 rc4key[3 + WLAN_KEY_LEN_WEP104];
Jiri Bencf0706e822007-05-05 11:45:53 -0700222 u8 keyidx;
Harvey Harrison70217d72008-06-22 16:45:23 -0700223 struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
224 unsigned int hdrlen;
Jiri Bencf0706e822007-05-05 11:45:53 -0700225 size_t len;
226 int ret = 0;
227
Harvey Harrison70217d72008-06-22 16:45:23 -0700228 if (!ieee80211_has_protected(hdr->frame_control))
Jiri Bencf0706e822007-05-05 11:45:53 -0700229 return -1;
230
Harvey Harrison70217d72008-06-22 16:45:23 -0700231 hdrlen = ieee80211_hdrlen(hdr->frame_control);
Harvey Harrisond2984872008-07-15 18:44:10 -0700232 if (skb->len < hdrlen + WEP_IV_LEN + WEP_ICV_LEN)
Jiri Bencf0706e822007-05-05 11:45:53 -0700233 return -1;
234
Harvey Harrisond2984872008-07-15 18:44:10 -0700235 len = skb->len - hdrlen - WEP_IV_LEN - WEP_ICV_LEN;
Jiri Bencf0706e822007-05-05 11:45:53 -0700236
237 keyidx = skb->data[hdrlen + 3] >> 6;
238
Johannes Berg97359d12010-08-10 09:46:38 +0200239 if (!key || keyidx != key->conf.keyidx)
Jiri Bencf0706e822007-05-05 11:45:53 -0700240 return -1;
241
Johannes Berg8f20fc22007-08-28 17:01:54 -0400242 klen = 3 + key->conf.keylen;
Jiri Bencf0706e822007-05-05 11:45:53 -0700243
Jiri Bencf0706e822007-05-05 11:45:53 -0700244 /* Prepend 24-bit IV to RC4 key */
245 memcpy(rc4key, skb->data + hdrlen, 3);
246
247 /* Copy rest of the WEP key (the secret part) */
Johannes Berg8f20fc22007-08-28 17:01:54 -0400248 memcpy(rc4key + 3, key->conf.key, key->conf.keylen);
Jiri Bencf0706e822007-05-05 11:45:53 -0700249
250 if (ieee80211_wep_decrypt_data(local->wep_rx_tfm, rc4key, klen,
251 skb->data + hdrlen + WEP_IV_LEN,
Johannes Bergf4ea83d2008-06-30 15:10:46 +0200252 len))
Jiri Bencf0706e822007-05-05 11:45:53 -0700253 ret = -1;
Jiri Bencf0706e822007-05-05 11:45:53 -0700254
Jiri Bencf0706e822007-05-05 11:45:53 -0700255 /* Trim ICV */
256 skb_trim(skb, skb->len - WEP_ICV_LEN);
257
258 /* Remove IV */
259 memmove(skb->data + WEP_IV_LEN, skb->data, hdrlen);
260 skb_pull(skb, WEP_IV_LEN);
261
262 return ret;
263}
264
265
Johannes Bergc6a1fa12008-10-07 12:04:32 +0200266bool ieee80211_wep_is_weak_iv(struct sk_buff *skb, struct ieee80211_key *key)
Jiri Bencf0706e822007-05-05 11:45:53 -0700267{
Harvey Harrison70217d72008-06-22 16:45:23 -0700268 struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
269 unsigned int hdrlen;
Jiri Bencf0706e822007-05-05 11:45:53 -0700270 u8 *ivpos;
271 u32 iv;
272
Harvey Harrison70217d72008-06-22 16:45:23 -0700273 if (!ieee80211_has_protected(hdr->frame_control))
Johannes Bergc6a1fa12008-10-07 12:04:32 +0200274 return false;
Jiri Bencf0706e822007-05-05 11:45:53 -0700275
Harvey Harrison70217d72008-06-22 16:45:23 -0700276 hdrlen = ieee80211_hdrlen(hdr->frame_control);
Jiri Bencf0706e822007-05-05 11:45:53 -0700277 ivpos = skb->data + hdrlen;
278 iv = (ivpos[0] << 16) | (ivpos[1] << 8) | ivpos[2];
279
Johannes Bergc6a1fa12008-10-07 12:04:32 +0200280 return ieee80211_wep_weak_iv(iv, key->conf.keylen);
Jiri Bencf0706e822007-05-05 11:45:53 -0700281}
Johannes Berg4f0d18e2007-09-26 15:19:40 +0200282
Johannes Berg9ae54c82008-01-31 19:48:20 +0100283ieee80211_rx_result
Johannes Berg5cf121c2008-02-25 16:27:43 +0100284ieee80211_crypto_wep_decrypt(struct ieee80211_rx_data *rx)
Johannes Berg4f0d18e2007-09-26 15:19:40 +0200285{
Johannes Bergeb9fb5b2009-11-16 13:58:20 +0100286 struct sk_buff *skb = rx->skb;
287 struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(skb);
288 struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
Harvey Harrison358c8d92008-07-15 18:44:13 -0700289
290 if (!ieee80211_is_data(hdr->frame_control) &&
291 !ieee80211_is_auth(hdr->frame_control))
Johannes Berg9ae54c82008-01-31 19:48:20 +0100292 return RX_CONTINUE;
Johannes Berg4f0d18e2007-09-26 15:19:40 +0200293
Johannes Bergeb9fb5b2009-11-16 13:58:20 +0100294 if (!(status->flag & RX_FLAG_DECRYPTED)) {
Johannes Bergf4ea83d2008-06-30 15:10:46 +0200295 if (ieee80211_wep_decrypt(rx->local, rx->skb, rx->key))
Johannes Berge4c26ad2008-01-31 19:48:21 +0100296 return RX_DROP_UNUSABLE;
Johannes Bergeb9fb5b2009-11-16 13:58:20 +0100297 } else if (!(status->flag & RX_FLAG_IV_STRIPPED)) {
Johannes Berg4f0d18e2007-09-26 15:19:40 +0200298 ieee80211_wep_remove_iv(rx->local, rx->skb, rx->key);
299 /* remove ICV */
Harvey Harrisond2984872008-07-15 18:44:10 -0700300 skb_trim(rx->skb, rx->skb->len - WEP_ICV_LEN);
Johannes Berg4f0d18e2007-09-26 15:19:40 +0200301 }
302
Johannes Berg9ae54c82008-01-31 19:48:20 +0100303 return RX_CONTINUE;
Johannes Berg4f0d18e2007-09-26 15:19:40 +0200304}
Johannes Berg6a22a592007-09-26 15:19:41 +0200305
Johannes Berg5cf121c2008-02-25 16:27:43 +0100306static int wep_encrypt_skb(struct ieee80211_tx_data *tx, struct sk_buff *skb)
Johannes Berg6a22a592007-09-26 15:19:41 +0200307{
Johannes Berge039fa42008-05-15 12:55:29 +0200308 struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
309
Johannes Berg813d7662010-01-17 01:47:58 +0100310 if (!info->control.hw_key) {
Johannes Bergc9cf0122009-07-07 03:45:18 +0200311 if (ieee80211_wep_encrypt(tx->local, skb, tx->key->conf.key,
312 tx->key->conf.keylen,
313 tx->key->conf.keyidx))
Johannes Berg6a22a592007-09-26 15:19:41 +0200314 return -1;
John W. Linvillee4fca002010-01-22 12:33:09 -0500315 } else if (info->control.hw_key->flags &
316 IEEE80211_KEY_FLAG_GENERATE_IV) {
Johannes Berg813d7662010-01-17 01:47:58 +0100317 if (!ieee80211_wep_add_iv(tx->local, skb,
318 tx->key->conf.keylen,
319 tx->key->conf.keyidx))
320 return -1;
321 }
322
Johannes Berg6a22a592007-09-26 15:19:41 +0200323 return 0;
324}
325
Johannes Berg9ae54c82008-01-31 19:48:20 +0100326ieee80211_tx_result
Johannes Berg5cf121c2008-02-25 16:27:43 +0100327ieee80211_crypto_wep_encrypt(struct ieee80211_tx_data *tx)
Johannes Berg6a22a592007-09-26 15:19:41 +0200328{
Johannes Berg2de8e0d2009-03-23 17:28:35 +0100329 struct sk_buff *skb;
Johannes Bergc6a1fa12008-10-07 12:04:32 +0200330
Johannes Berg5cf121c2008-02-25 16:27:43 +0100331 ieee80211_tx_set_protected(tx);
Johannes Berg6a22a592007-09-26 15:19:41 +0200332
Johannes Berg2de8e0d2009-03-23 17:28:35 +0100333 skb = tx->skb;
334 do {
335 if (wep_encrypt_skb(tx, skb) < 0) {
336 I802_DEBUG_INC(tx->local->tx_handlers_drop_wep);
337 return TX_DROP;
Johannes Berg6a22a592007-09-26 15:19:41 +0200338 }
Johannes Berg2de8e0d2009-03-23 17:28:35 +0100339 } while ((skb = skb->next));
Johannes Berg6a22a592007-09-26 15:19:41 +0200340
Johannes Berg9ae54c82008-01-31 19:48:20 +0100341 return TX_CONTINUE;
Johannes Berg6a22a592007-09-26 15:19:41 +0200342}