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.
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>
19 #include <linux/scatterlist.h>
21 #include <net/mac80211.h>
22 #include "ieee80211_i.h"
26 int ieee80211_wep_init(struct ieee80211_local *local)
28 /* start WEP IV from a random value */
29 get_random_bytes(&local->wep_iv, WEP_IV_LEN);
31 local->wep_tx_tfm = crypto_alloc_blkcipher("ecb(arc4)", 0,
33 if (IS_ERR(local->wep_tx_tfm))
36 local->wep_rx_tfm = crypto_alloc_blkcipher("ecb(arc4)", 0,
38 if (IS_ERR(local->wep_rx_tfm)) {
39 crypto_free_blkcipher(local->wep_tx_tfm);
46 void ieee80211_wep_free(struct ieee80211_local *local)
48 crypto_free_blkcipher(local->wep_tx_tfm);
49 crypto_free_blkcipher(local->wep_rx_tfm);
52 static inline int ieee80211_wep_weak_iv(u32 iv, int keylen)
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)
66 static void ieee80211_wep_get_iv(struct ieee80211_local *local,
67 struct ieee80211_key *key, u8 *iv)
70 if (ieee80211_wep_weak_iv(local->wep_iv, key->conf.keylen))
71 local->wep_iv += 0x0100;
76 *iv++ = (local->wep_iv >> 16) & 0xff;
77 *iv++ = (local->wep_iv >> 8) & 0xff;
78 *iv++ = local->wep_iv & 0xff;
79 *iv++ = key->conf.keyidx << 6;
83 static u8 *ieee80211_wep_add_iv(struct ieee80211_local *local,
85 struct ieee80211_key *key)
87 struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
92 fc = le16_to_cpu(hdr->frame_control);
93 fc |= IEEE80211_FCTL_PROTECTED;
94 hdr->frame_control = cpu_to_le16(fc);
96 if (WARN_ON(skb_tailroom(skb) < WEP_ICV_LEN ||
97 skb_headroom(skb) < WEP_IV_LEN))
100 hdrlen = ieee80211_get_hdrlen(fc);
101 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;
108 static void ieee80211_wep_remove_iv(struct ieee80211_local *local,
110 struct ieee80211_key *key)
112 struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
116 fc = le16_to_cpu(hdr->frame_control);
117 hdrlen = ieee80211_get_hdrlen(fc);
118 memmove(skb->data + WEP_IV_LEN, skb->data, hdrlen);
119 skb_pull(skb, WEP_IV_LEN);
123 /* Perform WEP encryption using given key. data buffer must have tailroom
124 * for 4-byte ICV. data_len must not include this ICV. Note: this function
125 * does _not_ add IV. data = RC4(data | CRC32(data)) */
126 void ieee80211_wep_encrypt_data(struct crypto_blkcipher *tfm, u8 *rc4key,
127 size_t klen, u8 *data, size_t data_len)
129 struct blkcipher_desc desc = { .tfm = tfm };
130 struct scatterlist sg;
133 icv = (__le32 *)(data + data_len);
134 *icv = cpu_to_le32(~crc32_le(~0, data, data_len));
136 crypto_blkcipher_setkey(tfm, rc4key, klen);
137 sg_init_one(&sg, data, data_len + WEP_ICV_LEN);
138 crypto_blkcipher_encrypt(&desc, &sg, &sg, sg.length);
142 /* Perform WEP encryption on given skb. 4 bytes of extra space (IV) in the
143 * beginning of the buffer 4 bytes of extra space (ICV) in the end of the
144 * buffer will be added. Both IV and ICV will be transmitted, so the
145 * payload length increases with 8 bytes.
147 * WEP frame payload: IV + TX key idx, RC4(data), ICV = RC4(CRC32(data))
149 int ieee80211_wep_encrypt(struct ieee80211_local *local, struct sk_buff *skb,
150 struct ieee80211_key *key)
156 if (!key || key->conf.alg != ALG_WEP)
159 klen = 3 + key->conf.keylen;
160 rc4key = kmalloc(klen, GFP_ATOMIC);
164 iv = ieee80211_wep_add_iv(local, skb, key);
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->conf.key, key->conf.keylen);
178 /* Add room for ICV */
179 skb_put(skb, WEP_ICV_LEN);
181 ieee80211_wep_encrypt_data(local->wep_tx_tfm, rc4key, klen,
182 iv + WEP_IV_LEN, len);
190 /* Perform WEP decryption using given key. data buffer includes encrypted
191 * payload, including 4-byte ICV, but _not_ IV. data_len must not include ICV.
192 * Return 0 on success and -1 on ICV mismatch. */
193 int ieee80211_wep_decrypt_data(struct crypto_blkcipher *tfm, u8 *rc4key,
194 size_t klen, u8 *data, size_t data_len)
196 struct blkcipher_desc desc = { .tfm = tfm };
197 struct scatterlist sg;
200 crypto_blkcipher_setkey(tfm, rc4key, klen);
201 sg_init_one(&sg, data, data_len + WEP_ICV_LEN);
202 crypto_blkcipher_decrypt(&desc, &sg, &sg, sg.length);
204 crc = cpu_to_le32(~crc32_le(~0, data, data_len));
205 if (memcmp(&crc, data + data_len, WEP_ICV_LEN) != 0)
213 /* Perform WEP decryption on given skb. Buffer includes whole WEP part of
214 * the frame: IV (4 bytes), encrypted payload (including SNAP header),
215 * ICV (4 bytes). skb->len includes both IV and ICV.
217 * Returns 0 if frame was decrypted successfully and ICV was correct and -1 on
218 * failure. If frame is OK, IV and ICV will be removed, i.e., decrypted payload
219 * is moved to the beginning of the skb and skb length will be reduced.
221 int ieee80211_wep_decrypt(struct ieee80211_local *local, struct sk_buff *skb,
222 struct ieee80211_key *key)
227 struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
233 fc = le16_to_cpu(hdr->frame_control);
234 if (!(fc & IEEE80211_FCTL_PROTECTED))
237 hdrlen = ieee80211_get_hdrlen(fc);
239 if (skb->len < 8 + hdrlen)
242 len = skb->len - hdrlen - 8;
244 keyidx = skb->data[hdrlen + 3] >> 6;
246 if (!key || keyidx != key->conf.keyidx || key->conf.alg != ALG_WEP)
249 klen = 3 + key->conf.keylen;
251 rc4key = kmalloc(klen, GFP_ATOMIC);
255 /* Prepend 24-bit IV to RC4 key */
256 memcpy(rc4key, skb->data + hdrlen, 3);
258 /* Copy rest of the WEP key (the secret part) */
259 memcpy(rc4key + 3, key->conf.key, key->conf.keylen);
261 if (ieee80211_wep_decrypt_data(local->wep_rx_tfm, rc4key, klen,
262 skb->data + hdrlen + WEP_IV_LEN,
265 printk(KERN_DEBUG "WEP decrypt failed (ICV)\n");
272 skb_trim(skb, skb->len - WEP_ICV_LEN);
275 memmove(skb->data + WEP_IV_LEN, skb->data, hdrlen);
276 skb_pull(skb, WEP_IV_LEN);
282 u8 * ieee80211_wep_is_weak_iv(struct sk_buff *skb, struct ieee80211_key *key)
284 struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
290 fc = le16_to_cpu(hdr->frame_control);
291 if (!(fc & IEEE80211_FCTL_PROTECTED))
294 hdrlen = ieee80211_get_hdrlen(fc);
295 ivpos = skb->data + hdrlen;
296 iv = (ivpos[0] << 16) | (ivpos[1] << 8) | ivpos[2];
298 if (ieee80211_wep_weak_iv(iv, key->conf.keylen))
305 ieee80211_crypto_wep_decrypt(struct ieee80211_rx_data *rx)
307 if ((rx->fc & IEEE80211_FCTL_FTYPE) != IEEE80211_FTYPE_DATA &&
308 ((rx->fc & IEEE80211_FCTL_FTYPE) != IEEE80211_FTYPE_MGMT ||
309 (rx->fc & IEEE80211_FCTL_STYPE) != IEEE80211_STYPE_AUTH))
312 if (!(rx->status->flag & RX_FLAG_DECRYPTED)) {
313 if (ieee80211_wep_decrypt(rx->local, rx->skb, rx->key)) {
314 #ifdef CONFIG_MAC80211_DEBUG
316 printk(KERN_DEBUG "%s: RX WEP frame, decrypt "
317 "failed\n", rx->dev->name);
318 #endif /* CONFIG_MAC80211_DEBUG */
319 return RX_DROP_UNUSABLE;
321 } else if (!(rx->status->flag & RX_FLAG_IV_STRIPPED)) {
322 ieee80211_wep_remove_iv(rx->local, rx->skb, rx->key);
324 skb_trim(rx->skb, rx->skb->len - 4);
330 static int wep_encrypt_skb(struct ieee80211_tx_data *tx, struct sk_buff *skb)
332 struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
334 info->control.iv_len = WEP_IV_LEN;
335 info->control.icv_len = WEP_ICV_LEN;
337 if (!(tx->key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE)) {
338 if (ieee80211_wep_encrypt(tx->local, skb, tx->key))
341 info->control.hw_key = &tx->key->conf;
342 if (tx->key->conf.flags & IEEE80211_KEY_FLAG_GENERATE_IV) {
343 if (!ieee80211_wep_add_iv(tx->local, skb, tx->key))
351 ieee80211_crypto_wep_encrypt(struct ieee80211_tx_data *tx)
353 ieee80211_tx_set_protected(tx);
355 if (wep_encrypt_skb(tx, tx->skb) < 0) {
356 I802_DEBUG_INC(tx->local->tx_handlers_drop_wep);
360 if (tx->extra_frag) {
362 for (i = 0; i < tx->num_extra_frag; i++) {
363 if (wep_encrypt_skb(tx, tx->extra_frag[i]) < 0) {
364 I802_DEBUG_INC(tx->local->
365 tx_handlers_drop_wep);