Commit | Line | Data |
---|---|---|
f0706e82 JB |
1 | /* |
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> | |
11763609 | 19 | #include <linux/scatterlist.h> |
5a0e3ad6 | 20 | #include <linux/slab.h> |
860c6e6a | 21 | #include <asm/unaligned.h> |
f0706e82 JB |
22 | |
23 | #include <net/mac80211.h> | |
24 | #include "ieee80211_i.h" | |
25 | #include "wep.h" | |
26 | ||
27 | ||
28 | int 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 | ||
5f9f1812 | 33 | local->wep_tx_tfm = crypto_alloc_cipher("arc4", 0, CRYPTO_ALG_ASYNC); |
088c8726 JL |
34 | if (IS_ERR(local->wep_tx_tfm)) { |
35 | local->wep_rx_tfm = ERR_PTR(-EINVAL); | |
023a04be | 36 | return PTR_ERR(local->wep_tx_tfm); |
088c8726 | 37 | } |
f0706e82 | 38 | |
5f9f1812 | 39 | local->wep_rx_tfm = crypto_alloc_cipher("arc4", 0, CRYPTO_ALG_ASYNC); |
f0706e82 | 40 | if (IS_ERR(local->wep_rx_tfm)) { |
5f9f1812 | 41 | crypto_free_cipher(local->wep_tx_tfm); |
088c8726 | 42 | local->wep_tx_tfm = ERR_PTR(-EINVAL); |
023a04be | 43 | return PTR_ERR(local->wep_rx_tfm); |
f0706e82 JB |
44 | } |
45 | ||
46 | return 0; | |
47 | } | |
48 | ||
49 | void ieee80211_wep_free(struct ieee80211_local *local) | |
50 | { | |
3473187d | 51 | if (!IS_ERR(local->wep_tx_tfm)) |
5f9f1812 | 52 | crypto_free_cipher(local->wep_tx_tfm); |
3473187d | 53 | if (!IS_ERR(local->wep_rx_tfm)) |
5f9f1812 | 54 | crypto_free_cipher(local->wep_rx_tfm); |
f0706e82 JB |
55 | } |
56 | ||
c6a1fa12 | 57 | static inline bool ieee80211_wep_weak_iv(u32 iv, int keylen) |
f0706e82 | 58 | { |
c6a1fa12 JB |
59 | /* |
60 | * Fluhrer, Mantin, and Shamir have reported weaknesses in the | |
f0706e82 | 61 | * key scheduling algorithm of RC4. At least IVs (KeyByte + 3, |
c6a1fa12 JB |
62 | * 0xff, N) can be used to speedup attacks, so avoid using them. |
63 | */ | |
f0706e82 JB |
64 | if ((iv & 0xff00) == 0xff00) { |
65 | u8 B = (iv >> 16) & 0xff; | |
66 | if (B >= 3 && B < 3 + keylen) | |
c6a1fa12 | 67 | return true; |
f0706e82 | 68 | } |
c6a1fa12 | 69 | return false; |
f0706e82 JB |
70 | } |
71 | ||
72 | ||
4f0d18e2 | 73 | static void ieee80211_wep_get_iv(struct ieee80211_local *local, |
c9cf0122 | 74 | int keylen, int keyidx, u8 *iv) |
f0706e82 JB |
75 | { |
76 | local->wep_iv++; | |
c9cf0122 | 77 | if (ieee80211_wep_weak_iv(local->wep_iv, keylen)) |
f0706e82 JB |
78 | 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; | |
c9cf0122 | 86 | *iv++ = keyidx << 6; |
f0706e82 JB |
87 | } |
88 | ||
89 | ||
6a22a59d JB |
90 | static u8 *ieee80211_wep_add_iv(struct ieee80211_local *local, |
91 | struct sk_buff *skb, | |
c9cf0122 | 92 | int keylen, int keyidx) |
f0706e82 | 93 | { |
70217d7f HH |
94 | struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data; |
95 | unsigned int hdrlen; | |
f0706e82 JB |
96 | u8 *newhdr; |
97 | ||
70217d7f | 98 | hdr->frame_control |= cpu_to_le16(IEEE80211_FCTL_PROTECTED); |
f0706e82 | 99 | |
23c0752a JB |
100 | if (WARN_ON(skb_tailroom(skb) < WEP_ICV_LEN || |
101 | skb_headroom(skb) < WEP_IV_LEN)) | |
102 | return NULL; | |
f0706e82 | 103 | |
70217d7f | 104 | hdrlen = ieee80211_hdrlen(hdr->frame_control); |
f0706e82 JB |
105 | newhdr = skb_push(skb, WEP_IV_LEN); |
106 | memmove(newhdr, newhdr + WEP_IV_LEN, hdrlen); | |
c9cf0122 | 107 | ieee80211_wep_get_iv(local, keylen, keyidx, newhdr + hdrlen); |
f0706e82 JB |
108 | return newhdr + hdrlen; |
109 | } | |
110 | ||
111 | ||
4f0d18e2 JB |
112 | static void ieee80211_wep_remove_iv(struct ieee80211_local *local, |
113 | struct sk_buff *skb, | |
114 | struct ieee80211_key *key) | |
f0706e82 | 115 | { |
70217d7f HH |
116 | struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data; |
117 | unsigned int hdrlen; | |
f0706e82 | 118 | |
70217d7f | 119 | hdrlen = ieee80211_hdrlen(hdr->frame_control); |
f0706e82 JB |
120 | 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)) */ | |
5f9f1812 | 128 | int ieee80211_wep_encrypt_data(struct crypto_cipher *tfm, u8 *rc4key, |
3473187d | 129 | size_t klen, u8 *data, size_t data_len) |
f0706e82 | 130 | { |
860c6e6a | 131 | __le32 icv; |
5f9f1812 | 132 | int i; |
f0706e82 | 133 | |
3473187d JL |
134 | if (IS_ERR(tfm)) |
135 | return -1; | |
136 | ||
860c6e6a IK |
137 | icv = cpu_to_le32(~crc32_le(~0, data, data_len)); |
138 | put_unaligned(icv, (__le32 *)(data + data_len)); | |
f0706e82 | 139 | |
5f9f1812 FF |
140 | 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); | |
3473187d JL |
143 | |
144 | return 0; | |
f0706e82 JB |
145 | } |
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 | */ | |
fffd0934 JB |
155 | int ieee80211_wep_encrypt(struct ieee80211_local *local, |
156 | struct sk_buff *skb, | |
157 | const u8 *key, int keylen, int keyidx) | |
f0706e82 | 158 | { |
c9cf0122 | 159 | u8 *iv; |
f0706e82 | 160 | size_t len; |
c9cf0122 | 161 | u8 rc4key[3 + WLAN_KEY_LEN_WEP104]; |
f0706e82 | 162 | |
c9cf0122 JB |
163 | iv = ieee80211_wep_add_iv(local, skb, keylen, keyidx); |
164 | if (!iv) | |
f0706e82 | 165 | return -1; |
f0706e82 JB |
166 | |
167 | 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) */ | |
c9cf0122 | 173 | memcpy(rc4key + 3, key, keylen); |
f0706e82 JB |
174 | |
175 | /* Add room for ICV */ | |
176 | skb_put(skb, WEP_ICV_LEN); | |
177 | ||
3473187d JL |
178 | return ieee80211_wep_encrypt_data(local->wep_tx_tfm, rc4key, keylen + 3, |
179 | iv + WEP_IV_LEN, len); | |
f0706e82 JB |
180 | } |
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. */ | |
5f9f1812 | 186 | int ieee80211_wep_decrypt_data(struct crypto_cipher *tfm, u8 *rc4key, |
f0706e82 JB |
187 | size_t klen, u8 *data, size_t data_len) |
188 | { | |
f0706e82 | 189 | __le32 crc; |
5f9f1812 | 190 | int i; |
f0706e82 | 191 | |
3473187d JL |
192 | if (IS_ERR(tfm)) |
193 | return -1; | |
194 | ||
5f9f1812 FF |
195 | 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); | |
f0706e82 JB |
198 | |
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 | */ | |
c9cf0122 JB |
216 | static int ieee80211_wep_decrypt(struct ieee80211_local *local, |
217 | struct sk_buff *skb, | |
218 | struct ieee80211_key *key) | |
f0706e82 JB |
219 | { |
220 | u32 klen; | |
730bd83b | 221 | u8 rc4key[3 + WLAN_KEY_LEN_WEP104]; |
f0706e82 | 222 | u8 keyidx; |
70217d7f HH |
223 | struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data; |
224 | unsigned int hdrlen; | |
f0706e82 JB |
225 | size_t len; |
226 | int ret = 0; | |
227 | ||
70217d7f | 228 | if (!ieee80211_has_protected(hdr->frame_control)) |
f0706e82 JB |
229 | return -1; |
230 | ||
70217d7f | 231 | hdrlen = ieee80211_hdrlen(hdr->frame_control); |
d2984872 | 232 | if (skb->len < hdrlen + WEP_IV_LEN + WEP_ICV_LEN) |
f0706e82 JB |
233 | return -1; |
234 | ||
d2984872 | 235 | len = skb->len - hdrlen - WEP_IV_LEN - WEP_ICV_LEN; |
f0706e82 JB |
236 | |
237 | keyidx = skb->data[hdrlen + 3] >> 6; | |
238 | ||
97359d12 | 239 | if (!key || keyidx != key->conf.keyidx) |
f0706e82 JB |
240 | return -1; |
241 | ||
8f20fc24 | 242 | klen = 3 + key->conf.keylen; |
f0706e82 | 243 | |
f0706e82 JB |
244 | /* 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) */ | |
8f20fc24 | 248 | memcpy(rc4key + 3, key->conf.key, key->conf.keylen); |
f0706e82 JB |
249 | |
250 | if (ieee80211_wep_decrypt_data(local->wep_rx_tfm, rc4key, klen, | |
251 | skb->data + hdrlen + WEP_IV_LEN, | |
f4ea83dd | 252 | len)) |
f0706e82 | 253 | ret = -1; |
f0706e82 | 254 | |
f0706e82 JB |
255 | /* 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 | ||
c6a1fa12 | 266 | bool ieee80211_wep_is_weak_iv(struct sk_buff *skb, struct ieee80211_key *key) |
f0706e82 | 267 | { |
70217d7f HH |
268 | struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data; |
269 | unsigned int hdrlen; | |
f0706e82 JB |
270 | u8 *ivpos; |
271 | u32 iv; | |
272 | ||
70217d7f | 273 | if (!ieee80211_has_protected(hdr->frame_control)) |
c6a1fa12 | 274 | return false; |
f0706e82 | 275 | |
70217d7f | 276 | hdrlen = ieee80211_hdrlen(hdr->frame_control); |
f0706e82 JB |
277 | ivpos = skb->data + hdrlen; |
278 | iv = (ivpos[0] << 16) | (ivpos[1] << 8) | ivpos[2]; | |
279 | ||
c6a1fa12 | 280 | return ieee80211_wep_weak_iv(iv, key->conf.keylen); |
f0706e82 | 281 | } |
4f0d18e2 | 282 | |
9ae54c84 | 283 | ieee80211_rx_result |
5cf121c3 | 284 | ieee80211_crypto_wep_decrypt(struct ieee80211_rx_data *rx) |
4f0d18e2 | 285 | { |
eb9fb5b8 JB |
286 | 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; | |
358c8d9d HH |
289 | |
290 | if (!ieee80211_is_data(hdr->frame_control) && | |
291 | !ieee80211_is_auth(hdr->frame_control)) | |
9ae54c84 | 292 | return RX_CONTINUE; |
4f0d18e2 | 293 | |
eb9fb5b8 | 294 | if (!(status->flag & RX_FLAG_DECRYPTED)) { |
f4ea83dd | 295 | if (ieee80211_wep_decrypt(rx->local, rx->skb, rx->key)) |
e4c26add | 296 | return RX_DROP_UNUSABLE; |
eb9fb5b8 | 297 | } else if (!(status->flag & RX_FLAG_IV_STRIPPED)) { |
4f0d18e2 JB |
298 | ieee80211_wep_remove_iv(rx->local, rx->skb, rx->key); |
299 | /* remove ICV */ | |
d2984872 | 300 | skb_trim(rx->skb, rx->skb->len - WEP_ICV_LEN); |
4f0d18e2 JB |
301 | } |
302 | ||
9ae54c84 | 303 | return RX_CONTINUE; |
4f0d18e2 | 304 | } |
6a22a59d | 305 | |
5cf121c3 | 306 | static int wep_encrypt_skb(struct ieee80211_tx_data *tx, struct sk_buff *skb) |
6a22a59d | 307 | { |
e039fa4a JB |
308 | struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb); |
309 | ||
813d7669 | 310 | if (!info->control.hw_key) { |
c9cf0122 JB |
311 | if (ieee80211_wep_encrypt(tx->local, skb, tx->key->conf.key, |
312 | tx->key->conf.keylen, | |
313 | tx->key->conf.keyidx)) | |
6a22a59d | 314 | return -1; |
e4fca007 JL |
315 | } else if (info->control.hw_key->flags & |
316 | IEEE80211_KEY_FLAG_GENERATE_IV) { | |
813d7669 JB |
317 | if (!ieee80211_wep_add_iv(tx->local, skb, |
318 | tx->key->conf.keylen, | |
319 | tx->key->conf.keyidx)) | |
320 | return -1; | |
321 | } | |
322 | ||
6a22a59d JB |
323 | return 0; |
324 | } | |
325 | ||
9ae54c84 | 326 | ieee80211_tx_result |
5cf121c3 | 327 | ieee80211_crypto_wep_encrypt(struct ieee80211_tx_data *tx) |
6a22a59d | 328 | { |
2de8e0d9 | 329 | struct sk_buff *skb; |
c6a1fa12 | 330 | |
5cf121c3 | 331 | ieee80211_tx_set_protected(tx); |
6a22a59d | 332 | |
2de8e0d9 JB |
333 | 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; | |
6a22a59d | 338 | } |
2de8e0d9 | 339 | } while ((skb = skb->next)); |
6a22a59d | 340 | |
9ae54c84 | 341 | return TX_CONTINUE; |
6a22a59d | 342 | } |