Merge branch 'v6v7' into devel
[linux/fpc-iii.git] / net / mac80211 / wep.c
blob2ff6d1e3ed21565524fc55c724b24bbee67dd0c6
1 /*
2 * Software WEP encryption implementation
3 * Copyright 2002, Jouni Malinen <jkmaline@cc.hut.fi>
4 * Copyright 2003, Instant802 Networks, Inc.
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 */
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>
19 #include <linux/scatterlist.h>
20 #include <linux/slab.h>
21 #include <asm/unaligned.h>
23 #include <net/mac80211.h>
24 #include "ieee80211_i.h"
25 #include "wep.h"
28 int ieee80211_wep_init(struct ieee80211_local *local)
30 /* start WEP IV from a random value */
31 get_random_bytes(&local->wep_iv, WEP_IV_LEN);
33 local->wep_tx_tfm = crypto_alloc_blkcipher("ecb(arc4)", 0,
34 CRYPTO_ALG_ASYNC);
35 if (IS_ERR(local->wep_tx_tfm)) {
36 local->wep_rx_tfm = ERR_PTR(-EINVAL);
37 return PTR_ERR(local->wep_tx_tfm);
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);
44 local->wep_tx_tfm = ERR_PTR(-EINVAL);
45 return PTR_ERR(local->wep_rx_tfm);
48 return 0;
51 void ieee80211_wep_free(struct ieee80211_local *local)
53 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);
59 static inline bool ieee80211_wep_weak_iv(u32 iv, int keylen)
62 * Fluhrer, Mantin, and Shamir have reported weaknesses in the
63 * key scheduling algorithm of RC4. At least IVs (KeyByte + 3,
64 * 0xff, N) can be used to speedup attacks, so avoid using them.
66 if ((iv & 0xff00) == 0xff00) {
67 u8 B = (iv >> 16) & 0xff;
68 if (B >= 3 && B < 3 + keylen)
69 return true;
71 return false;
75 static void ieee80211_wep_get_iv(struct ieee80211_local *local,
76 int keylen, int keyidx, u8 *iv)
78 local->wep_iv++;
79 if (ieee80211_wep_weak_iv(local->wep_iv, keylen))
80 local->wep_iv += 0x0100;
82 if (!iv)
83 return;
85 *iv++ = (local->wep_iv >> 16) & 0xff;
86 *iv++ = (local->wep_iv >> 8) & 0xff;
87 *iv++ = local->wep_iv & 0xff;
88 *iv++ = keyidx << 6;
92 static u8 *ieee80211_wep_add_iv(struct ieee80211_local *local,
93 struct sk_buff *skb,
94 int keylen, int keyidx)
96 struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
97 unsigned int hdrlen;
98 u8 *newhdr;
100 hdr->frame_control |= cpu_to_le16(IEEE80211_FCTL_PROTECTED);
102 if (WARN_ON(skb_tailroom(skb) < WEP_ICV_LEN ||
103 skb_headroom(skb) < WEP_IV_LEN))
104 return NULL;
106 hdrlen = ieee80211_hdrlen(hdr->frame_control);
107 newhdr = skb_push(skb, WEP_IV_LEN);
108 memmove(newhdr, newhdr + WEP_IV_LEN, hdrlen);
109 ieee80211_wep_get_iv(local, keylen, keyidx, newhdr + hdrlen);
110 return newhdr + hdrlen;
114 static void ieee80211_wep_remove_iv(struct ieee80211_local *local,
115 struct sk_buff *skb,
116 struct ieee80211_key *key)
118 struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
119 unsigned int hdrlen;
121 hdrlen = ieee80211_hdrlen(hdr->frame_control);
122 memmove(skb->data + WEP_IV_LEN, skb->data, hdrlen);
123 skb_pull(skb, WEP_IV_LEN);
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)) */
130 int ieee80211_wep_encrypt_data(struct crypto_blkcipher *tfm, u8 *rc4key,
131 size_t klen, u8 *data, size_t data_len)
133 struct blkcipher_desc desc = { .tfm = tfm };
134 struct scatterlist sg;
135 __le32 icv;
137 if (IS_ERR(tfm))
138 return -1;
140 icv = cpu_to_le32(~crc32_le(~0, data, data_len));
141 put_unaligned(icv, (__le32 *)(data + data_len));
143 crypto_blkcipher_setkey(tfm, rc4key, klen);
144 sg_init_one(&sg, data, data_len + WEP_ICV_LEN);
145 crypto_blkcipher_encrypt(&desc, &sg, &sg, sg.length);
147 return 0;
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.
156 * WEP frame payload: IV + TX key idx, RC4(data), ICV = RC4(CRC32(data))
158 int ieee80211_wep_encrypt(struct ieee80211_local *local,
159 struct sk_buff *skb,
160 const u8 *key, int keylen, int keyidx)
162 u8 *iv;
163 size_t len;
164 u8 rc4key[3 + WLAN_KEY_LEN_WEP104];
166 iv = ieee80211_wep_add_iv(local, skb, keylen, keyidx);
167 if (!iv)
168 return -1;
170 len = skb->len - (iv + WEP_IV_LEN - skb->data);
172 /* Prepend 24-bit IV to RC4 key */
173 memcpy(rc4key, iv, 3);
175 /* Copy rest of the WEP key (the secret part) */
176 memcpy(rc4key + 3, key, keylen);
178 /* Add room for ICV */
179 skb_put(skb, WEP_ICV_LEN);
181 return ieee80211_wep_encrypt_data(local->wep_tx_tfm, rc4key, keylen + 3,
182 iv + WEP_IV_LEN, len);
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. */
189 int ieee80211_wep_decrypt_data(struct crypto_blkcipher *tfm, u8 *rc4key,
190 size_t klen, u8 *data, size_t data_len)
192 struct blkcipher_desc desc = { .tfm = tfm };
193 struct scatterlist sg;
194 __le32 crc;
196 if (IS_ERR(tfm))
197 return -1;
199 crypto_blkcipher_setkey(tfm, rc4key, klen);
200 sg_init_one(&sg, data, data_len + WEP_ICV_LEN);
201 crypto_blkcipher_decrypt(&desc, &sg, &sg, sg.length);
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;
208 return 0;
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.
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.
220 static int ieee80211_wep_decrypt(struct ieee80211_local *local,
221 struct sk_buff *skb,
222 struct ieee80211_key *key)
224 u32 klen;
225 u8 rc4key[3 + WLAN_KEY_LEN_WEP104];
226 u8 keyidx;
227 struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
228 unsigned int hdrlen;
229 size_t len;
230 int ret = 0;
232 if (!ieee80211_has_protected(hdr->frame_control))
233 return -1;
235 hdrlen = ieee80211_hdrlen(hdr->frame_control);
236 if (skb->len < hdrlen + WEP_IV_LEN + WEP_ICV_LEN)
237 return -1;
239 len = skb->len - hdrlen - WEP_IV_LEN - WEP_ICV_LEN;
241 keyidx = skb->data[hdrlen + 3] >> 6;
243 if (!key || keyidx != key->conf.keyidx)
244 return -1;
246 klen = 3 + key->conf.keylen;
248 /* Prepend 24-bit IV to RC4 key */
249 memcpy(rc4key, skb->data + hdrlen, 3);
251 /* Copy rest of the WEP key (the secret part) */
252 memcpy(rc4key + 3, key->conf.key, key->conf.keylen);
254 if (ieee80211_wep_decrypt_data(local->wep_rx_tfm, rc4key, klen,
255 skb->data + hdrlen + WEP_IV_LEN,
256 len))
257 ret = -1;
259 /* Trim ICV */
260 skb_trim(skb, skb->len - WEP_ICV_LEN);
262 /* Remove IV */
263 memmove(skb->data + WEP_IV_LEN, skb->data, hdrlen);
264 skb_pull(skb, WEP_IV_LEN);
266 return ret;
270 bool ieee80211_wep_is_weak_iv(struct sk_buff *skb, struct ieee80211_key *key)
272 struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
273 unsigned int hdrlen;
274 u8 *ivpos;
275 u32 iv;
277 if (!ieee80211_has_protected(hdr->frame_control))
278 return false;
280 hdrlen = ieee80211_hdrlen(hdr->frame_control);
281 ivpos = skb->data + hdrlen;
282 iv = (ivpos[0] << 16) | (ivpos[1] << 8) | ivpos[2];
284 return ieee80211_wep_weak_iv(iv, key->conf.keylen);
287 ieee80211_rx_result
288 ieee80211_crypto_wep_decrypt(struct ieee80211_rx_data *rx)
290 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;
294 if (!ieee80211_is_data(hdr->frame_control) &&
295 !ieee80211_is_auth(hdr->frame_control))
296 return RX_CONTINUE;
298 if (!(status->flag & RX_FLAG_DECRYPTED)) {
299 if (ieee80211_wep_decrypt(rx->local, rx->skb, rx->key))
300 return RX_DROP_UNUSABLE;
301 } else if (!(status->flag & RX_FLAG_IV_STRIPPED)) {
302 ieee80211_wep_remove_iv(rx->local, rx->skb, rx->key);
303 /* remove ICV */
304 skb_trim(rx->skb, rx->skb->len - WEP_ICV_LEN);
307 return RX_CONTINUE;
310 static int wep_encrypt_skb(struct ieee80211_tx_data *tx, struct sk_buff *skb)
312 struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
314 if (!info->control.hw_key) {
315 if (ieee80211_wep_encrypt(tx->local, skb, tx->key->conf.key,
316 tx->key->conf.keylen,
317 tx->key->conf.keyidx))
318 return -1;
319 } else if (info->control.hw_key->flags &
320 IEEE80211_KEY_FLAG_GENERATE_IV) {
321 if (!ieee80211_wep_add_iv(tx->local, skb,
322 tx->key->conf.keylen,
323 tx->key->conf.keyidx))
324 return -1;
327 return 0;
330 ieee80211_tx_result
331 ieee80211_crypto_wep_encrypt(struct ieee80211_tx_data *tx)
333 struct sk_buff *skb;
335 ieee80211_tx_set_protected(tx);
337 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;
343 } while ((skb = skb->next));
345 return TX_CONTINUE;