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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * lib80211 crypt: host-based WEP encryption implementation for lib80211
4 *
5 * Copyright (c) 2002-2004, Jouni Malinen <j@w1.fi>
6 * Copyright (c) 2008, John W. Linville <linville@tuxdriver.com>
7 */
8
9#include <linux/err.h>
10#include <linux/fips.h>
11#include <linux/module.h>
12#include <linux/init.h>
13#include <linux/slab.h>
14#include <linux/random.h>
15#include <linux/scatterlist.h>
16#include <linux/skbuff.h>
17#include <linux/mm.h>
18#include <asm/string.h>
19
20#include <net/lib80211.h>
21
22#include <crypto/arc4.h>
23#include <linux/crc32.h>
24
25MODULE_AUTHOR("Jouni Malinen");
26MODULE_DESCRIPTION("lib80211 crypt: WEP");
27MODULE_LICENSE("GPL");
28
29struct lib80211_wep_data {
30 u32 iv;
31#define WEP_KEY_LEN 13
32 u8 key[WEP_KEY_LEN + 1];
33 u8 key_len;
34 u8 key_idx;
35 struct arc4_ctx tx_ctx;
36 struct arc4_ctx rx_ctx;
37};
38
39static void *lib80211_wep_init(int keyidx)
40{
41 struct lib80211_wep_data *priv;
42
43 if (fips_enabled)
44 return NULL;
45
46 priv = kzalloc(sizeof(*priv), GFP_ATOMIC);
47 if (priv == NULL)
48 return NULL;
49 priv->key_idx = keyidx;
50
51 /* start WEP IV from a random value */
52 get_random_bytes(&priv->iv, 4);
53
54 return priv;
55}
56
57static void lib80211_wep_deinit(void *priv)
58{
59 kfree_sensitive(priv);
60}
61
62/* Add WEP IV/key info to a frame that has at least 4 bytes of headroom */
63static int lib80211_wep_build_iv(struct sk_buff *skb, int hdr_len,
64 u8 *key, int keylen, void *priv)
65{
66 struct lib80211_wep_data *wep = priv;
67 u32 klen;
68 u8 *pos;
69
70 if (skb_headroom(skb) < 4 || skb->len < hdr_len)
71 return -1;
72
73 pos = skb_push(skb, 4);
74 memmove(pos, pos + 4, hdr_len);
75 pos += hdr_len;
76
77 klen = 3 + wep->key_len;
78
79 wep->iv++;
80
81 /* Fluhrer, Mantin, and Shamir have reported weaknesses in the key
82 * scheduling algorithm of RC4. At least IVs (KeyByte + 3, 0xff, N)
83 * can be used to speedup attacks, so avoid using them. */
84 if ((wep->iv & 0xff00) == 0xff00) {
85 u8 B = (wep->iv >> 16) & 0xff;
86 if (B >= 3 && B < klen)
87 wep->iv += 0x0100;
88 }
89
90 /* Prepend 24-bit IV to RC4 key and TX frame */
91 *pos++ = (wep->iv >> 16) & 0xff;
92 *pos++ = (wep->iv >> 8) & 0xff;
93 *pos++ = wep->iv & 0xff;
94 *pos++ = wep->key_idx << 6;
95
96 return 0;
97}
98
99/* Perform WEP encryption on given skb that has at least 4 bytes of headroom
100 * for IV and 4 bytes of tailroom for ICV. Both IV and ICV will be transmitted,
101 * so the payload length increases with 8 bytes.
102 *
103 * WEP frame payload: IV + TX key idx, RC4(data), ICV = RC4(CRC32(data))
104 */
105static int lib80211_wep_encrypt(struct sk_buff *skb, int hdr_len, void *priv)
106{
107 struct lib80211_wep_data *wep = priv;
108 u32 crc, klen, len;
109 u8 *pos, *icv;
110 u8 key[WEP_KEY_LEN + 3];
111
112 /* other checks are in lib80211_wep_build_iv */
113 if (skb_tailroom(skb) < 4)
114 return -1;
115
116 /* add the IV to the frame */
117 if (lib80211_wep_build_iv(skb, hdr_len, NULL, 0, priv))
118 return -1;
119
120 /* Copy the IV into the first 3 bytes of the key */
121 skb_copy_from_linear_data_offset(skb, hdr_len, key, 3);
122
123 /* Copy rest of the WEP key (the secret part) */
124 memcpy(key + 3, wep->key, wep->key_len);
125
126 len = skb->len - hdr_len - 4;
127 pos = skb->data + hdr_len + 4;
128 klen = 3 + wep->key_len;
129
130 /* Append little-endian CRC32 over only the data and encrypt it to produce ICV */
131 crc = ~crc32_le(~0, pos, len);
132 icv = skb_put(skb, 4);
133 icv[0] = crc;
134 icv[1] = crc >> 8;
135 icv[2] = crc >> 16;
136 icv[3] = crc >> 24;
137
138 arc4_setkey(&wep->tx_ctx, key, klen);
139 arc4_crypt(&wep->tx_ctx, pos, pos, len + 4);
140
141 return 0;
142}
143
144/* Perform WEP decryption on given buffer. Buffer includes whole WEP part of
145 * the frame: IV (4 bytes), encrypted payload (including SNAP header),
146 * ICV (4 bytes). len includes both IV and ICV.
147 *
148 * Returns 0 if frame was decrypted successfully and ICV was correct and -1 on
149 * failure. If frame is OK, IV and ICV will be removed.
150 */
151static int lib80211_wep_decrypt(struct sk_buff *skb, int hdr_len, void *priv)
152{
153 struct lib80211_wep_data *wep = priv;
154 u32 crc, klen, plen;
155 u8 key[WEP_KEY_LEN + 3];
156 u8 keyidx, *pos, icv[4];
157
158 if (skb->len < hdr_len + 8)
159 return -1;
160
161 pos = skb->data + hdr_len;
162 key[0] = *pos++;
163 key[1] = *pos++;
164 key[2] = *pos++;
165 keyidx = *pos++ >> 6;
166 if (keyidx != wep->key_idx)
167 return -1;
168
169 klen = 3 + wep->key_len;
170
171 /* Copy rest of the WEP key (the secret part) */
172 memcpy(key + 3, wep->key, wep->key_len);
173
174 /* Apply RC4 to data and compute CRC32 over decrypted data */
175 plen = skb->len - hdr_len - 8;
176
177 arc4_setkey(&wep->rx_ctx, key, klen);
178 arc4_crypt(&wep->rx_ctx, pos, pos, plen + 4);
179
180 crc = ~crc32_le(~0, pos, plen);
181 icv[0] = crc;
182 icv[1] = crc >> 8;
183 icv[2] = crc >> 16;
184 icv[3] = crc >> 24;
185 if (memcmp(icv, pos + plen, 4) != 0) {
186 /* ICV mismatch - drop frame */
187 return -2;
188 }
189
190 /* Remove IV and ICV */
191 memmove(skb->data + 4, skb->data, hdr_len);
192 skb_pull(skb, 4);
193 skb_trim(skb, skb->len - 4);
194
195 return 0;
196}
197
198static int lib80211_wep_set_key(void *key, int len, u8 * seq, void *priv)
199{
200 struct lib80211_wep_data *wep = priv;
201
202 if (len < 0 || len > WEP_KEY_LEN)
203 return -1;
204
205 memcpy(wep->key, key, len);
206 wep->key_len = len;
207
208 return 0;
209}
210
211static int lib80211_wep_get_key(void *key, int len, u8 * seq, void *priv)
212{
213 struct lib80211_wep_data *wep = priv;
214
215 if (len < wep->key_len)
216 return -1;
217
218 memcpy(key, wep->key, wep->key_len);
219
220 return wep->key_len;
221}
222
223static void lib80211_wep_print_stats(struct seq_file *m, void *priv)
224{
225 struct lib80211_wep_data *wep = priv;
226 seq_printf(m, "key[%d] alg=WEP len=%d\n", wep->key_idx, wep->key_len);
227}
228
229static struct lib80211_crypto_ops lib80211_crypt_wep = {
230 .name = "WEP",
231 .init = lib80211_wep_init,
232 .deinit = lib80211_wep_deinit,
233 .encrypt_mpdu = lib80211_wep_encrypt,
234 .decrypt_mpdu = lib80211_wep_decrypt,
235 .encrypt_msdu = NULL,
236 .decrypt_msdu = NULL,
237 .set_key = lib80211_wep_set_key,
238 .get_key = lib80211_wep_get_key,
239 .print_stats = lib80211_wep_print_stats,
240 .extra_mpdu_prefix_len = 4, /* IV */
241 .extra_mpdu_postfix_len = 4, /* ICV */
242 .owner = THIS_MODULE,
243};
244
245static int __init lib80211_crypto_wep_init(void)
246{
247 return lib80211_register_crypto_ops(&lib80211_crypt_wep);
248}
249
250static void __exit lib80211_crypto_wep_exit(void)
251{
252 lib80211_unregister_crypto_ops(&lib80211_crypt_wep);
253}
254
255module_init(lib80211_crypto_wep_init);
256module_exit(lib80211_crypto_wep_exit);
1/*
2 * lib80211 crypt: host-based WEP encryption implementation for lib80211
3 *
4 * Copyright (c) 2002-2004, Jouni Malinen <j@w1.fi>
5 * Copyright (c) 2008, John W. Linville <linville@tuxdriver.com>
6 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License version 2 as
9 * published by the Free Software Foundation. See README and COPYING for
10 * more details.
11 */
12
13#include <linux/err.h>
14#include <linux/module.h>
15#include <linux/init.h>
16#include <linux/slab.h>
17#include <linux/random.h>
18#include <linux/scatterlist.h>
19#include <linux/skbuff.h>
20#include <linux/mm.h>
21#include <asm/string.h>
22
23#include <net/lib80211.h>
24
25#include <crypto/skcipher.h>
26#include <linux/crc32.h>
27
28MODULE_AUTHOR("Jouni Malinen");
29MODULE_DESCRIPTION("lib80211 crypt: WEP");
30MODULE_LICENSE("GPL");
31
32struct lib80211_wep_data {
33 u32 iv;
34#define WEP_KEY_LEN 13
35 u8 key[WEP_KEY_LEN + 1];
36 u8 key_len;
37 u8 key_idx;
38 struct crypto_skcipher *tx_tfm;
39 struct crypto_skcipher *rx_tfm;
40};
41
42static void *lib80211_wep_init(int keyidx)
43{
44 struct lib80211_wep_data *priv;
45
46 priv = kzalloc(sizeof(*priv), GFP_ATOMIC);
47 if (priv == NULL)
48 goto fail;
49 priv->key_idx = keyidx;
50
51 priv->tx_tfm = crypto_alloc_skcipher("ecb(arc4)", 0, CRYPTO_ALG_ASYNC);
52 if (IS_ERR(priv->tx_tfm)) {
53 priv->tx_tfm = NULL;
54 goto fail;
55 }
56
57 priv->rx_tfm = crypto_alloc_skcipher("ecb(arc4)", 0, CRYPTO_ALG_ASYNC);
58 if (IS_ERR(priv->rx_tfm)) {
59 priv->rx_tfm = NULL;
60 goto fail;
61 }
62 /* start WEP IV from a random value */
63 get_random_bytes(&priv->iv, 4);
64
65 return priv;
66
67 fail:
68 if (priv) {
69 crypto_free_skcipher(priv->tx_tfm);
70 crypto_free_skcipher(priv->rx_tfm);
71 kfree(priv);
72 }
73 return NULL;
74}
75
76static void lib80211_wep_deinit(void *priv)
77{
78 struct lib80211_wep_data *_priv = priv;
79 if (_priv) {
80 crypto_free_skcipher(_priv->tx_tfm);
81 crypto_free_skcipher(_priv->rx_tfm);
82 }
83 kfree(priv);
84}
85
86/* Add WEP IV/key info to a frame that has at least 4 bytes of headroom */
87static int lib80211_wep_build_iv(struct sk_buff *skb, int hdr_len,
88 u8 *key, int keylen, void *priv)
89{
90 struct lib80211_wep_data *wep = priv;
91 u32 klen;
92 u8 *pos;
93
94 if (skb_headroom(skb) < 4 || skb->len < hdr_len)
95 return -1;
96
97 pos = skb_push(skb, 4);
98 memmove(pos, pos + 4, hdr_len);
99 pos += hdr_len;
100
101 klen = 3 + wep->key_len;
102
103 wep->iv++;
104
105 /* Fluhrer, Mantin, and Shamir have reported weaknesses in the key
106 * scheduling algorithm of RC4. At least IVs (KeyByte + 3, 0xff, N)
107 * can be used to speedup attacks, so avoid using them. */
108 if ((wep->iv & 0xff00) == 0xff00) {
109 u8 B = (wep->iv >> 16) & 0xff;
110 if (B >= 3 && B < klen)
111 wep->iv += 0x0100;
112 }
113
114 /* Prepend 24-bit IV to RC4 key and TX frame */
115 *pos++ = (wep->iv >> 16) & 0xff;
116 *pos++ = (wep->iv >> 8) & 0xff;
117 *pos++ = wep->iv & 0xff;
118 *pos++ = wep->key_idx << 6;
119
120 return 0;
121}
122
123/* Perform WEP encryption on given skb that has at least 4 bytes of headroom
124 * for IV and 4 bytes of tailroom for ICV. Both IV and ICV will be transmitted,
125 * so the payload length increases with 8 bytes.
126 *
127 * WEP frame payload: IV + TX key idx, RC4(data), ICV = RC4(CRC32(data))
128 */
129static int lib80211_wep_encrypt(struct sk_buff *skb, int hdr_len, void *priv)
130{
131 struct lib80211_wep_data *wep = priv;
132 SKCIPHER_REQUEST_ON_STACK(req, wep->tx_tfm);
133 u32 crc, klen, len;
134 u8 *pos, *icv;
135 struct scatterlist sg;
136 u8 key[WEP_KEY_LEN + 3];
137 int err;
138
139 /* other checks are in lib80211_wep_build_iv */
140 if (skb_tailroom(skb) < 4)
141 return -1;
142
143 /* add the IV to the frame */
144 if (lib80211_wep_build_iv(skb, hdr_len, NULL, 0, priv))
145 return -1;
146
147 /* Copy the IV into the first 3 bytes of the key */
148 skb_copy_from_linear_data_offset(skb, hdr_len, key, 3);
149
150 /* Copy rest of the WEP key (the secret part) */
151 memcpy(key + 3, wep->key, wep->key_len);
152
153 len = skb->len - hdr_len - 4;
154 pos = skb->data + hdr_len + 4;
155 klen = 3 + wep->key_len;
156
157 /* Append little-endian CRC32 over only the data and encrypt it to produce ICV */
158 crc = ~crc32_le(~0, pos, len);
159 icv = skb_put(skb, 4);
160 icv[0] = crc;
161 icv[1] = crc >> 8;
162 icv[2] = crc >> 16;
163 icv[3] = crc >> 24;
164
165 crypto_skcipher_setkey(wep->tx_tfm, key, klen);
166 sg_init_one(&sg, pos, len + 4);
167 skcipher_request_set_tfm(req, wep->tx_tfm);
168 skcipher_request_set_callback(req, 0, NULL, NULL);
169 skcipher_request_set_crypt(req, &sg, &sg, len + 4, NULL);
170 err = crypto_skcipher_encrypt(req);
171 skcipher_request_zero(req);
172 return err;
173}
174
175/* Perform WEP decryption on given buffer. Buffer includes whole WEP part of
176 * the frame: IV (4 bytes), encrypted payload (including SNAP header),
177 * ICV (4 bytes). len includes both IV and ICV.
178 *
179 * Returns 0 if frame was decrypted successfully and ICV was correct and -1 on
180 * failure. If frame is OK, IV and ICV will be removed.
181 */
182static int lib80211_wep_decrypt(struct sk_buff *skb, int hdr_len, void *priv)
183{
184 struct lib80211_wep_data *wep = priv;
185 SKCIPHER_REQUEST_ON_STACK(req, wep->rx_tfm);
186 u32 crc, klen, plen;
187 u8 key[WEP_KEY_LEN + 3];
188 u8 keyidx, *pos, icv[4];
189 struct scatterlist sg;
190 int err;
191
192 if (skb->len < hdr_len + 8)
193 return -1;
194
195 pos = skb->data + hdr_len;
196 key[0] = *pos++;
197 key[1] = *pos++;
198 key[2] = *pos++;
199 keyidx = *pos++ >> 6;
200 if (keyidx != wep->key_idx)
201 return -1;
202
203 klen = 3 + wep->key_len;
204
205 /* Copy rest of the WEP key (the secret part) */
206 memcpy(key + 3, wep->key, wep->key_len);
207
208 /* Apply RC4 to data and compute CRC32 over decrypted data */
209 plen = skb->len - hdr_len - 8;
210
211 crypto_skcipher_setkey(wep->rx_tfm, key, klen);
212 sg_init_one(&sg, pos, plen + 4);
213 skcipher_request_set_tfm(req, wep->rx_tfm);
214 skcipher_request_set_callback(req, 0, NULL, NULL);
215 skcipher_request_set_crypt(req, &sg, &sg, plen + 4, NULL);
216 err = crypto_skcipher_decrypt(req);
217 skcipher_request_zero(req);
218 if (err)
219 return -7;
220
221 crc = ~crc32_le(~0, pos, plen);
222 icv[0] = crc;
223 icv[1] = crc >> 8;
224 icv[2] = crc >> 16;
225 icv[3] = crc >> 24;
226 if (memcmp(icv, pos + plen, 4) != 0) {
227 /* ICV mismatch - drop frame */
228 return -2;
229 }
230
231 /* Remove IV and ICV */
232 memmove(skb->data + 4, skb->data, hdr_len);
233 skb_pull(skb, 4);
234 skb_trim(skb, skb->len - 4);
235
236 return 0;
237}
238
239static int lib80211_wep_set_key(void *key, int len, u8 * seq, void *priv)
240{
241 struct lib80211_wep_data *wep = priv;
242
243 if (len < 0 || len > WEP_KEY_LEN)
244 return -1;
245
246 memcpy(wep->key, key, len);
247 wep->key_len = len;
248
249 return 0;
250}
251
252static int lib80211_wep_get_key(void *key, int len, u8 * seq, void *priv)
253{
254 struct lib80211_wep_data *wep = priv;
255
256 if (len < wep->key_len)
257 return -1;
258
259 memcpy(key, wep->key, wep->key_len);
260
261 return wep->key_len;
262}
263
264static void lib80211_wep_print_stats(struct seq_file *m, void *priv)
265{
266 struct lib80211_wep_data *wep = priv;
267 seq_printf(m, "key[%d] alg=WEP len=%d\n", wep->key_idx, wep->key_len);
268}
269
270static struct lib80211_crypto_ops lib80211_crypt_wep = {
271 .name = "WEP",
272 .init = lib80211_wep_init,
273 .deinit = lib80211_wep_deinit,
274 .encrypt_mpdu = lib80211_wep_encrypt,
275 .decrypt_mpdu = lib80211_wep_decrypt,
276 .encrypt_msdu = NULL,
277 .decrypt_msdu = NULL,
278 .set_key = lib80211_wep_set_key,
279 .get_key = lib80211_wep_get_key,
280 .print_stats = lib80211_wep_print_stats,
281 .extra_mpdu_prefix_len = 4, /* IV */
282 .extra_mpdu_postfix_len = 4, /* ICV */
283 .owner = THIS_MODULE,
284};
285
286static int __init lib80211_crypto_wep_init(void)
287{
288 return lib80211_register_crypto_ops(&lib80211_crypt_wep);
289}
290
291static void __exit lib80211_crypto_wep_exit(void)
292{
293 lib80211_unregister_crypto_ops(&lib80211_crypt_wep);
294}
295
296module_init(lib80211_crypto_wep_init);
297module_exit(lib80211_crypto_wep_exit);