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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>
Ivan Kuten860c6e62008-11-24 15:17:54 -050020#include <asm/unaligned.h>
Jiri Bencf0706e822007-05-05 11:45:53 -070021
22#include <net/mac80211.h>
23#include "ieee80211_i.h"
24#include "wep.h"
25
26
27int ieee80211_wep_init(struct ieee80211_local *local)
28{
29 /* start WEP IV from a random value */
30 get_random_bytes(&local->wep_iv, WEP_IV_LEN);
31
32 local->wep_tx_tfm = crypto_alloc_blkcipher("ecb(arc4)", 0,
33 CRYPTO_ALG_ASYNC);
34 if (IS_ERR(local->wep_tx_tfm))
Jeremy Fitzhardinge023a04b2008-07-14 12:52:08 -070035 return PTR_ERR(local->wep_tx_tfm);
Jiri Bencf0706e822007-05-05 11:45:53 -070036
37 local->wep_rx_tfm = crypto_alloc_blkcipher("ecb(arc4)", 0,
38 CRYPTO_ALG_ASYNC);
39 if (IS_ERR(local->wep_rx_tfm)) {
40 crypto_free_blkcipher(local->wep_tx_tfm);
Jeremy Fitzhardinge023a04b2008-07-14 12:52:08 -070041 return PTR_ERR(local->wep_rx_tfm);
Jiri Bencf0706e822007-05-05 11:45:53 -070042 }
43
44 return 0;
45}
46
47void ieee80211_wep_free(struct ieee80211_local *local)
48{
49 crypto_free_blkcipher(local->wep_tx_tfm);
50 crypto_free_blkcipher(local->wep_rx_tfm);
51}
52
Johannes Bergc6a1fa12008-10-07 12:04:32 +020053static inline bool ieee80211_wep_weak_iv(u32 iv, int keylen)
Jiri Bencf0706e822007-05-05 11:45:53 -070054{
Johannes Bergc6a1fa12008-10-07 12:04:32 +020055 /*
56 * Fluhrer, Mantin, and Shamir have reported weaknesses in the
Jiri Bencf0706e822007-05-05 11:45:53 -070057 * key scheduling algorithm of RC4. At least IVs (KeyByte + 3,
Johannes Bergc6a1fa12008-10-07 12:04:32 +020058 * 0xff, N) can be used to speedup attacks, so avoid using them.
59 */
Jiri Bencf0706e822007-05-05 11:45:53 -070060 if ((iv & 0xff00) == 0xff00) {
61 u8 B = (iv >> 16) & 0xff;
62 if (B >= 3 && B < 3 + keylen)
Johannes Bergc6a1fa12008-10-07 12:04:32 +020063 return true;
Jiri Bencf0706e822007-05-05 11:45:53 -070064 }
Johannes Bergc6a1fa12008-10-07 12:04:32 +020065 return false;
Jiri Bencf0706e822007-05-05 11:45:53 -070066}
67
68
Johannes Berg4f0d18e2007-09-26 15:19:40 +020069static void ieee80211_wep_get_iv(struct ieee80211_local *local,
70 struct ieee80211_key *key, u8 *iv)
Jiri Bencf0706e822007-05-05 11:45:53 -070071{
72 local->wep_iv++;
Johannes Berg8f20fc22007-08-28 17:01:54 -040073 if (ieee80211_wep_weak_iv(local->wep_iv, key->conf.keylen))
Jiri Bencf0706e822007-05-05 11:45:53 -070074 local->wep_iv += 0x0100;
75
76 if (!iv)
77 return;
78
79 *iv++ = (local->wep_iv >> 16) & 0xff;
80 *iv++ = (local->wep_iv >> 8) & 0xff;
81 *iv++ = local->wep_iv & 0xff;
Johannes Berg8f20fc22007-08-28 17:01:54 -040082 *iv++ = key->conf.keyidx << 6;
Jiri Bencf0706e822007-05-05 11:45:53 -070083}
84
85
Johannes Berg6a22a592007-09-26 15:19:41 +020086static u8 *ieee80211_wep_add_iv(struct ieee80211_local *local,
87 struct sk_buff *skb,
88 struct ieee80211_key *key)
Jiri Bencf0706e822007-05-05 11:45:53 -070089{
Harvey Harrison70217d72008-06-22 16:45:23 -070090 struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
91 unsigned int hdrlen;
Jiri Bencf0706e822007-05-05 11:45:53 -070092 u8 *newhdr;
93
Harvey Harrison70217d72008-06-22 16:45:23 -070094 hdr->frame_control |= cpu_to_le16(IEEE80211_FCTL_PROTECTED);
Jiri Bencf0706e822007-05-05 11:45:53 -070095
Johannes Berg23c07522008-05-29 10:38:53 +020096 if (WARN_ON(skb_tailroom(skb) < WEP_ICV_LEN ||
97 skb_headroom(skb) < WEP_IV_LEN))
98 return NULL;
Jiri Bencf0706e822007-05-05 11:45:53 -070099
Harvey Harrison70217d72008-06-22 16:45:23 -0700100 hdrlen = ieee80211_hdrlen(hdr->frame_control);
Jiri Bencf0706e822007-05-05 11:45:53 -0700101 newhdr = skb_push(skb, WEP_IV_LEN);
102 memmove(newhdr, newhdr + WEP_IV_LEN, hdrlen);
103 ieee80211_wep_get_iv(local, key, newhdr + hdrlen);
104 return newhdr + hdrlen;
105}
106
107
Johannes Berg4f0d18e2007-09-26 15:19:40 +0200108static void ieee80211_wep_remove_iv(struct ieee80211_local *local,
109 struct sk_buff *skb,
110 struct ieee80211_key *key)
Jiri Bencf0706e822007-05-05 11:45:53 -0700111{
Harvey Harrison70217d72008-06-22 16:45:23 -0700112 struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
113 unsigned int hdrlen;
Jiri Bencf0706e822007-05-05 11:45:53 -0700114
Harvey Harrison70217d72008-06-22 16:45:23 -0700115 hdrlen = ieee80211_hdrlen(hdr->frame_control);
Jiri Bencf0706e822007-05-05 11:45:53 -0700116 memmove(skb->data + WEP_IV_LEN, skb->data, hdrlen);
117 skb_pull(skb, WEP_IV_LEN);
118}
119
120
121/* Perform WEP encryption using given key. data buffer must have tailroom
122 * for 4-byte ICV. data_len must not include this ICV. Note: this function
123 * does _not_ add IV. data = RC4(data | CRC32(data)) */
124void ieee80211_wep_encrypt_data(struct crypto_blkcipher *tfm, u8 *rc4key,
125 size_t klen, u8 *data, size_t data_len)
126{
127 struct blkcipher_desc desc = { .tfm = tfm };
128 struct scatterlist sg;
Ivan Kuten860c6e62008-11-24 15:17:54 -0500129 __le32 icv;
Jiri Bencf0706e822007-05-05 11:45:53 -0700130
Ivan Kuten860c6e62008-11-24 15:17:54 -0500131 icv = cpu_to_le32(~crc32_le(~0, data, data_len));
132 put_unaligned(icv, (__le32 *)(data + data_len));
Jiri Bencf0706e822007-05-05 11:45:53 -0700133
134 crypto_blkcipher_setkey(tfm, rc4key, klen);
Jens Axboefa05f122007-10-22 19:44:26 +0200135 sg_init_one(&sg, data, data_len + WEP_ICV_LEN);
Jiri Bencf0706e822007-05-05 11:45:53 -0700136 crypto_blkcipher_encrypt(&desc, &sg, &sg, sg.length);
137}
138
139
140/* Perform WEP encryption on given skb. 4 bytes of extra space (IV) in the
141 * beginning of the buffer 4 bytes of extra space (ICV) in the end of the
142 * buffer will be added. Both IV and ICV will be transmitted, so the
143 * payload length increases with 8 bytes.
144 *
145 * WEP frame payload: IV + TX key idx, RC4(data), ICV = RC4(CRC32(data))
146 */
147int ieee80211_wep_encrypt(struct ieee80211_local *local, struct sk_buff *skb,
148 struct ieee80211_key *key)
149{
150 u32 klen;
151 u8 *rc4key, *iv;
152 size_t len;
153
Johannes Berg8f20fc22007-08-28 17:01:54 -0400154 if (!key || key->conf.alg != ALG_WEP)
Jiri Bencf0706e822007-05-05 11:45:53 -0700155 return -1;
156
Johannes Berg8f20fc22007-08-28 17:01:54 -0400157 klen = 3 + key->conf.keylen;
Jiri Bencf0706e822007-05-05 11:45:53 -0700158 rc4key = kmalloc(klen, GFP_ATOMIC);
159 if (!rc4key)
160 return -1;
161
162 iv = ieee80211_wep_add_iv(local, skb, key);
163 if (!iv) {
164 kfree(rc4key);
165 return -1;
166 }
167
168 len = skb->len - (iv + WEP_IV_LEN - skb->data);
169
170 /* Prepend 24-bit IV to RC4 key */
171 memcpy(rc4key, iv, 3);
172
173 /* Copy rest of the WEP key (the secret part) */
Johannes Berg8f20fc22007-08-28 17:01:54 -0400174 memcpy(rc4key + 3, key->conf.key, key->conf.keylen);
Jiri Bencf0706e822007-05-05 11:45:53 -0700175
176 /* Add room for ICV */
177 skb_put(skb, WEP_ICV_LEN);
178
179 ieee80211_wep_encrypt_data(local->wep_tx_tfm, rc4key, klen,
180 iv + WEP_IV_LEN, len);
181
182 kfree(rc4key);
183
184 return 0;
185}
186
187
188/* Perform WEP decryption using given key. data buffer includes encrypted
189 * payload, including 4-byte ICV, but _not_ IV. data_len must not include ICV.
190 * Return 0 on success and -1 on ICV mismatch. */
191int ieee80211_wep_decrypt_data(struct crypto_blkcipher *tfm, u8 *rc4key,
192 size_t klen, u8 *data, size_t data_len)
193{
194 struct blkcipher_desc desc = { .tfm = tfm };
195 struct scatterlist sg;
196 __le32 crc;
197
198 crypto_blkcipher_setkey(tfm, rc4key, klen);
Jens Axboefa05f122007-10-22 19:44:26 +0200199 sg_init_one(&sg, data, data_len + WEP_ICV_LEN);
Jiri Bencf0706e822007-05-05 11:45:53 -0700200 crypto_blkcipher_decrypt(&desc, &sg, &sg, sg.length);
201
202 crc = cpu_to_le32(~crc32_le(~0, data, data_len));
203 if (memcmp(&crc, data + data_len, WEP_ICV_LEN) != 0)
204 /* ICV mismatch */
205 return -1;
206
207 return 0;
208}
209
210
211/* Perform WEP decryption on given skb. Buffer includes whole WEP part of
212 * the frame: IV (4 bytes), encrypted payload (including SNAP header),
213 * ICV (4 bytes). skb->len includes both IV and ICV.
214 *
215 * Returns 0 if frame was decrypted successfully and ICV was correct and -1 on
216 * failure. If frame is OK, IV and ICV will be removed, i.e., decrypted payload
217 * is moved to the beginning of the skb and skb length will be reduced.
218 */
219int ieee80211_wep_decrypt(struct ieee80211_local *local, struct sk_buff *skb,
220 struct ieee80211_key *key)
221{
222 u32 klen;
223 u8 *rc4key;
224 u8 keyidx;
Harvey Harrison70217d72008-06-22 16:45:23 -0700225 struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
226 unsigned int hdrlen;
Jiri Bencf0706e822007-05-05 11:45:53 -0700227 size_t len;
228 int ret = 0;
229
Harvey Harrison70217d72008-06-22 16:45:23 -0700230 if (!ieee80211_has_protected(hdr->frame_control))
Jiri Bencf0706e822007-05-05 11:45:53 -0700231 return -1;
232
Harvey Harrison70217d72008-06-22 16:45:23 -0700233 hdrlen = ieee80211_hdrlen(hdr->frame_control);
Harvey Harrisond2984872008-07-15 18:44:10 -0700234 if (skb->len < hdrlen + WEP_IV_LEN + WEP_ICV_LEN)
Jiri Bencf0706e822007-05-05 11:45:53 -0700235 return -1;
236
Harvey Harrisond2984872008-07-15 18:44:10 -0700237 len = skb->len - hdrlen - WEP_IV_LEN - WEP_ICV_LEN;
Jiri Bencf0706e822007-05-05 11:45:53 -0700238
239 keyidx = skb->data[hdrlen + 3] >> 6;
240
Johannes Berg8f20fc22007-08-28 17:01:54 -0400241 if (!key || keyidx != key->conf.keyidx || key->conf.alg != ALG_WEP)
Jiri Bencf0706e822007-05-05 11:45:53 -0700242 return -1;
243
Johannes Berg8f20fc22007-08-28 17:01:54 -0400244 klen = 3 + key->conf.keylen;
Jiri Bencf0706e822007-05-05 11:45:53 -0700245
246 rc4key = kmalloc(klen, GFP_ATOMIC);
247 if (!rc4key)
248 return -1;
249
250 /* Prepend 24-bit IV to RC4 key */
251 memcpy(rc4key, skb->data + hdrlen, 3);
252
253 /* Copy rest of the WEP key (the secret part) */
Johannes Berg8f20fc22007-08-28 17:01:54 -0400254 memcpy(rc4key + 3, key->conf.key, key->conf.keylen);
Jiri Bencf0706e822007-05-05 11:45:53 -0700255
256 if (ieee80211_wep_decrypt_data(local->wep_rx_tfm, rc4key, klen,
257 skb->data + hdrlen + WEP_IV_LEN,
Johannes Bergf4ea83d2008-06-30 15:10:46 +0200258 len))
Jiri Bencf0706e822007-05-05 11:45:53 -0700259 ret = -1;
Jiri Bencf0706e822007-05-05 11:45:53 -0700260
261 kfree(rc4key);
262
263 /* Trim ICV */
264 skb_trim(skb, skb->len - WEP_ICV_LEN);
265
266 /* Remove IV */
267 memmove(skb->data + WEP_IV_LEN, skb->data, hdrlen);
268 skb_pull(skb, WEP_IV_LEN);
269
270 return ret;
271}
272
273
Johannes Bergc6a1fa12008-10-07 12:04:32 +0200274bool ieee80211_wep_is_weak_iv(struct sk_buff *skb, struct ieee80211_key *key)
Jiri Bencf0706e822007-05-05 11:45:53 -0700275{
Harvey Harrison70217d72008-06-22 16:45:23 -0700276 struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
277 unsigned int hdrlen;
Jiri Bencf0706e822007-05-05 11:45:53 -0700278 u8 *ivpos;
279 u32 iv;
280
Harvey Harrison70217d72008-06-22 16:45:23 -0700281 if (!ieee80211_has_protected(hdr->frame_control))
Johannes Bergc6a1fa12008-10-07 12:04:32 +0200282 return false;
Jiri Bencf0706e822007-05-05 11:45:53 -0700283
Harvey Harrison70217d72008-06-22 16:45:23 -0700284 hdrlen = ieee80211_hdrlen(hdr->frame_control);
Jiri Bencf0706e822007-05-05 11:45:53 -0700285 ivpos = skb->data + hdrlen;
286 iv = (ivpos[0] << 16) | (ivpos[1] << 8) | ivpos[2];
287
Johannes Bergc6a1fa12008-10-07 12:04:32 +0200288 return ieee80211_wep_weak_iv(iv, key->conf.keylen);
Jiri Bencf0706e822007-05-05 11:45:53 -0700289}
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
Johannes Berg6a22a592007-09-26 15:19:41 +0200316 if (!(tx->key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE)) {
317 if (ieee80211_wep_encrypt(tx->local, skb, tx->key))
318 return -1;
319 } else {
Pavel Roskin2b212142008-06-02 07:54:50 -0400320 info->control.hw_key = &tx->key->conf;
Johannes Berg6a22a592007-09-26 15:19:41 +0200321 if (tx->key->conf.flags & IEEE80211_KEY_FLAG_GENERATE_IV) {
322 if (!ieee80211_wep_add_iv(tx->local, skb, tx->key))
323 return -1;
324 }
325 }
326 return 0;
327}
328
Johannes Berg9ae54c82008-01-31 19:48:20 +0100329ieee80211_tx_result
Johannes Berg5cf121c2008-02-25 16:27:43 +0100330ieee80211_crypto_wep_encrypt(struct ieee80211_tx_data *tx)
Johannes Berg6a22a592007-09-26 15:19:41 +0200331{
Johannes Bergc6a1fa12008-10-07 12:04:32 +0200332 int i;
333
Johannes Berg5cf121c2008-02-25 16:27:43 +0100334 ieee80211_tx_set_protected(tx);
Johannes Berg6a22a592007-09-26 15:19:41 +0200335
336 if (wep_encrypt_skb(tx, tx->skb) < 0) {
337 I802_DEBUG_INC(tx->local->tx_handlers_drop_wep);
Johannes Berg9ae54c82008-01-31 19:48:20 +0100338 return TX_DROP;
Johannes Berg6a22a592007-09-26 15:19:41 +0200339 }
340
Johannes Berg5cf121c2008-02-25 16:27:43 +0100341 if (tx->extra_frag) {
Johannes Berg5cf121c2008-02-25 16:27:43 +0100342 for (i = 0; i < tx->num_extra_frag; i++) {
Johannes Bergc6a1fa12008-10-07 12:04:32 +0200343 if (wep_encrypt_skb(tx, tx->extra_frag[i])) {
Johannes Berg6a22a592007-09-26 15:19:41 +0200344 I802_DEBUG_INC(tx->local->
345 tx_handlers_drop_wep);
Johannes Berg9ae54c82008-01-31 19:48:20 +0100346 return TX_DROP;
Johannes Berg6a22a592007-09-26 15:19:41 +0200347 }
348 }
349 }
350
Johannes Berg9ae54c82008-01-31 19:48:20 +0100351 return TX_CONTINUE;
Johannes Berg6a22a592007-09-26 15:19:41 +0200352}