2 * Copyright (c) 2002-2005 Sam Leffler, Errno Consulting
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 * 3. The name of the author may not be used to endorse or promote products
14 * derived from this software without specific prior written permission.
16 * Alternatively, this software may be distributed under the terms of the
17 * GNU General Public License ("GPL") version 2 as published by the Free
18 * Software Foundation.
20 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
21 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
22 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
23 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
24 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
25 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
26 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
27 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
28 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
29 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
32 #include <sys/cdefs.h>
33 __FBSDID("$FreeBSD$");
36 * IEEE 802.11 WEP crypto support.
38 #include <sys/param.h>
39 #include <sys/systm.h>
41 #include <sys/malloc.h>
42 #include <sys/kernel.h>
43 #include <sys/module.h>
44 #include <sys/endian.h>
46 #include <sys/socket.h>
49 #include <net/if_media.h>
50 #include <net/ethernet.h>
52 #include <net80211/ieee80211_var.h>
54 static void *wep_attach(struct ieee80211com *, struct ieee80211_key *);
55 static void wep_detach(struct ieee80211_key *);
56 static int wep_setkey(struct ieee80211_key *);
57 static int wep_encap(struct ieee80211_key *, struct mbuf *, u_int8_t keyid);
58 static int wep_decap(struct ieee80211_key *, struct mbuf *, int hdrlen);
59 static int wep_enmic(struct ieee80211_key *, struct mbuf *, int);
60 static int wep_demic(struct ieee80211_key *, struct mbuf *, int);
62 static const struct ieee80211_cipher wep = {
64 .ic_cipher = IEEE80211_CIPHER_WEP,
65 .ic_header = IEEE80211_WEP_IVLEN + IEEE80211_WEP_KIDLEN,
66 .ic_trailer = IEEE80211_WEP_CRCLEN,
68 .ic_attach = wep_attach,
69 .ic_detach = wep_detach,
70 .ic_setkey = wep_setkey,
71 .ic_encap = wep_encap,
72 .ic_decap = wep_decap,
73 .ic_enmic = wep_enmic,
74 .ic_demic = wep_demic,
77 static int wep_encrypt(struct ieee80211_key *, struct mbuf *, int hdrlen);
78 static int wep_decrypt(struct ieee80211_key *, struct mbuf *, int hdrlen);
81 struct ieee80211com *wc_ic; /* for diagnostics */
82 u_int32_t wc_iv; /* initial vector for crypto */
85 /* number of references from net80211 layer */
89 wep_attach(struct ieee80211com *ic, struct ieee80211_key *k)
93 MALLOC(ctx, struct wep_ctx *, sizeof(struct wep_ctx),
94 M_DEVBUF, M_NOWAIT | M_ZERO);
96 ic->ic_stats.is_crypto_nomem++;
101 get_random_bytes(&ctx->wc_iv, sizeof(ctx->wc_iv));
102 nrefs++; /* NB: we assume caller locking */
107 wep_detach(struct ieee80211_key *k)
109 struct wep_ctx *ctx = k->wk_private;
112 KASSERT(nrefs > 0, ("imbalanced attach/detach"));
113 nrefs--; /* NB: we assume caller locking */
117 wep_setkey(struct ieee80211_key *k)
119 return k->wk_keylen >= 40/NBBY;
123 * Add privacy headers appropriate for the specified key.
126 wep_encap(struct ieee80211_key *k, struct mbuf *m, u_int8_t keyid)
128 struct wep_ctx *ctx = k->wk_private;
129 struct ieee80211com *ic = ctx->wc_ic;
134 hdrlen = ieee80211_hdrspace(ic, mtod(m, void *));
137 * Copy down 802.11 header and add the IV + KeyID.
139 M_PREPEND(m, wep.ic_header, M_NOWAIT);
142 ivp = mtod(m, u_int8_t *);
143 ovbcopy(ivp + wep.ic_header, ivp, hdrlen);
148 * IV must not duplicate during the lifetime of the key.
149 * But no mechanism to renew keys is defined in IEEE 802.11
150 * for WEP. And the IV may be duplicated at other stations
151 * because the session key itself is shared. So we use a
152 * pseudo random IV for now, though it is not the right way.
154 * NB: Rather than use a strictly random IV we select a
155 * random one to start and then increment the value for
156 * each frame. This is an explicit tradeoff between
157 * overhead and security. Given the basic insecurity of
158 * WEP this seems worthwhile.
162 * Skip 'bad' IVs from Fluhrer/Mantin/Shamir:
163 * (B, 255, N) with 3 <= B < 16 and 0 <= N <= 255
166 if ((iv & 0xff00) == 0xff00) {
167 int B = (iv & 0xff0000) >> 16;
168 if (3 <= B && B < 16)
174 * NB: Preserve byte order of IV for packet
175 * sniffers; it doesn't matter otherwise.
177 #if _BYTE_ORDER == _BIG_ENDIAN
189 * Finally, do software encrypt if neeed.
191 if ((k->wk_flags & IEEE80211_KEY_SWCRYPT) &&
192 !wep_encrypt(k, m, hdrlen))
199 * Add MIC to the frame as needed.
202 wep_enmic(struct ieee80211_key *k, struct mbuf *m, int force)
209 * Validate and strip privacy headers (and trailer) for a
210 * received frame. If necessary, decrypt the frame using
214 wep_decap(struct ieee80211_key *k, struct mbuf *m, int hdrlen)
216 struct wep_ctx *ctx = k->wk_private;
217 struct ieee80211_frame *wh;
219 wh = mtod(m, struct ieee80211_frame *);
222 * Check if the device handled the decrypt in hardware.
223 * If so we just strip the header; otherwise we need to
224 * handle the decrypt in software.
226 if ((k->wk_flags & IEEE80211_KEY_SWCRYPT) &&
227 !wep_decrypt(k, m, hdrlen)) {
228 IEEE80211_DPRINTF(ctx->wc_ic, IEEE80211_MSG_CRYPTO,
229 "[%s] WEP ICV mismatch on decrypt\n",
230 ether_sprintf(wh->i_addr2));
231 ctx->wc_ic->ic_stats.is_rx_wepfail++;
236 * Copy up 802.11 header and strip crypto bits.
238 ovbcopy(mtod(m, void *), mtod(m, u_int8_t *) + wep.ic_header, hdrlen);
239 m_adj(m, wep.ic_header);
240 m_adj(m, -wep.ic_trailer);
246 * Verify and strip MIC from the frame.
249 wep_demic(struct ieee80211_key *k, struct mbuf *skb, int force)
254 static const uint32_t crc32_table[256] = {
255 0x00000000L, 0x77073096L, 0xee0e612cL, 0x990951baL, 0x076dc419L,
256 0x706af48fL, 0xe963a535L, 0x9e6495a3L, 0x0edb8832L, 0x79dcb8a4L,
257 0xe0d5e91eL, 0x97d2d988L, 0x09b64c2bL, 0x7eb17cbdL, 0xe7b82d07L,
258 0x90bf1d91L, 0x1db71064L, 0x6ab020f2L, 0xf3b97148L, 0x84be41deL,
259 0x1adad47dL, 0x6ddde4ebL, 0xf4d4b551L, 0x83d385c7L, 0x136c9856L,
260 0x646ba8c0L, 0xfd62f97aL, 0x8a65c9ecL, 0x14015c4fL, 0x63066cd9L,
261 0xfa0f3d63L, 0x8d080df5L, 0x3b6e20c8L, 0x4c69105eL, 0xd56041e4L,
262 0xa2677172L, 0x3c03e4d1L, 0x4b04d447L, 0xd20d85fdL, 0xa50ab56bL,
263 0x35b5a8faL, 0x42b2986cL, 0xdbbbc9d6L, 0xacbcf940L, 0x32d86ce3L,
264 0x45df5c75L, 0xdcd60dcfL, 0xabd13d59L, 0x26d930acL, 0x51de003aL,
265 0xc8d75180L, 0xbfd06116L, 0x21b4f4b5L, 0x56b3c423L, 0xcfba9599L,
266 0xb8bda50fL, 0x2802b89eL, 0x5f058808L, 0xc60cd9b2L, 0xb10be924L,
267 0x2f6f7c87L, 0x58684c11L, 0xc1611dabL, 0xb6662d3dL, 0x76dc4190L,
268 0x01db7106L, 0x98d220bcL, 0xefd5102aL, 0x71b18589L, 0x06b6b51fL,
269 0x9fbfe4a5L, 0xe8b8d433L, 0x7807c9a2L, 0x0f00f934L, 0x9609a88eL,
270 0xe10e9818L, 0x7f6a0dbbL, 0x086d3d2dL, 0x91646c97L, 0xe6635c01L,
271 0x6b6b51f4L, 0x1c6c6162L, 0x856530d8L, 0xf262004eL, 0x6c0695edL,
272 0x1b01a57bL, 0x8208f4c1L, 0xf50fc457L, 0x65b0d9c6L, 0x12b7e950L,
273 0x8bbeb8eaL, 0xfcb9887cL, 0x62dd1ddfL, 0x15da2d49L, 0x8cd37cf3L,
274 0xfbd44c65L, 0x4db26158L, 0x3ab551ceL, 0xa3bc0074L, 0xd4bb30e2L,
275 0x4adfa541L, 0x3dd895d7L, 0xa4d1c46dL, 0xd3d6f4fbL, 0x4369e96aL,
276 0x346ed9fcL, 0xad678846L, 0xda60b8d0L, 0x44042d73L, 0x33031de5L,
277 0xaa0a4c5fL, 0xdd0d7cc9L, 0x5005713cL, 0x270241aaL, 0xbe0b1010L,
278 0xc90c2086L, 0x5768b525L, 0x206f85b3L, 0xb966d409L, 0xce61e49fL,
279 0x5edef90eL, 0x29d9c998L, 0xb0d09822L, 0xc7d7a8b4L, 0x59b33d17L,
280 0x2eb40d81L, 0xb7bd5c3bL, 0xc0ba6cadL, 0xedb88320L, 0x9abfb3b6L,
281 0x03b6e20cL, 0x74b1d29aL, 0xead54739L, 0x9dd277afL, 0x04db2615L,
282 0x73dc1683L, 0xe3630b12L, 0x94643b84L, 0x0d6d6a3eL, 0x7a6a5aa8L,
283 0xe40ecf0bL, 0x9309ff9dL, 0x0a00ae27L, 0x7d079eb1L, 0xf00f9344L,
284 0x8708a3d2L, 0x1e01f268L, 0x6906c2feL, 0xf762575dL, 0x806567cbL,
285 0x196c3671L, 0x6e6b06e7L, 0xfed41b76L, 0x89d32be0L, 0x10da7a5aL,
286 0x67dd4accL, 0xf9b9df6fL, 0x8ebeeff9L, 0x17b7be43L, 0x60b08ed5L,
287 0xd6d6a3e8L, 0xa1d1937eL, 0x38d8c2c4L, 0x4fdff252L, 0xd1bb67f1L,
288 0xa6bc5767L, 0x3fb506ddL, 0x48b2364bL, 0xd80d2bdaL, 0xaf0a1b4cL,
289 0x36034af6L, 0x41047a60L, 0xdf60efc3L, 0xa867df55L, 0x316e8eefL,
290 0x4669be79L, 0xcb61b38cL, 0xbc66831aL, 0x256fd2a0L, 0x5268e236L,
291 0xcc0c7795L, 0xbb0b4703L, 0x220216b9L, 0x5505262fL, 0xc5ba3bbeL,
292 0xb2bd0b28L, 0x2bb45a92L, 0x5cb36a04L, 0xc2d7ffa7L, 0xb5d0cf31L,
293 0x2cd99e8bL, 0x5bdeae1dL, 0x9b64c2b0L, 0xec63f226L, 0x756aa39cL,
294 0x026d930aL, 0x9c0906a9L, 0xeb0e363fL, 0x72076785L, 0x05005713L,
295 0x95bf4a82L, 0xe2b87a14L, 0x7bb12baeL, 0x0cb61b38L, 0x92d28e9bL,
296 0xe5d5be0dL, 0x7cdcefb7L, 0x0bdbdf21L, 0x86d3d2d4L, 0xf1d4e242L,
297 0x68ddb3f8L, 0x1fda836eL, 0x81be16cdL, 0xf6b9265bL, 0x6fb077e1L,
298 0x18b74777L, 0x88085ae6L, 0xff0f6a70L, 0x66063bcaL, 0x11010b5cL,
299 0x8f659effL, 0xf862ae69L, 0x616bffd3L, 0x166ccf45L, 0xa00ae278L,
300 0xd70dd2eeL, 0x4e048354L, 0x3903b3c2L, 0xa7672661L, 0xd06016f7L,
301 0x4969474dL, 0x3e6e77dbL, 0xaed16a4aL, 0xd9d65adcL, 0x40df0b66L,
302 0x37d83bf0L, 0xa9bcae53L, 0xdebb9ec5L, 0x47b2cf7fL, 0x30b5ffe9L,
303 0xbdbdf21cL, 0xcabac28aL, 0x53b39330L, 0x24b4a3a6L, 0xbad03605L,
304 0xcdd70693L, 0x54de5729L, 0x23d967bfL, 0xb3667a2eL, 0xc4614ab8L,
305 0x5d681b02L, 0x2a6f2b94L, 0xb40bbe37L, 0xc30c8ea1L, 0x5a05df1bL,
310 wep_encrypt(struct ieee80211_key *key, struct mbuf *m0, int hdrlen)
312 #define S_SWAP(a,b) do { uint8_t t = S[a]; S[a] = S[b]; S[b] = t; } while(0)
313 struct wep_ctx *ctx = key->wk_private;
315 u_int8_t rc4key[IEEE80211_WEP_IVLEN + IEEE80211_KEYBUF_SIZE];
316 uint8_t icv[IEEE80211_WEP_CRCLEN];
317 uint32_t i, j, k, crc;
318 size_t buflen, data_len;
323 ctx->wc_ic->ic_stats.is_crypto_wep++;
325 /* NB: this assumes the header was pulled up */
326 memcpy(rc4key, mtod(m, u_int8_t *) + hdrlen, IEEE80211_WEP_IVLEN);
327 memcpy(rc4key + IEEE80211_WEP_IVLEN, key->wk_key, key->wk_keylen);
329 /* Setup RC4 state */
330 for (i = 0; i < 256; i++)
333 keylen = key->wk_keylen + IEEE80211_WEP_IVLEN;
334 for (i = 0; i < 256; i++) {
335 j = (j + S[i] + rc4key[i % keylen]) & 0xff;
339 off = hdrlen + wep.ic_header;
340 data_len = m->m_pkthdr.len - off;
342 /* Compute CRC32 over unencrypted data and apply RC4 to data */
345 pos = mtod(m, uint8_t *) + off;
346 buflen = m->m_len - off;
348 if (buflen > data_len)
351 for (k = 0; k < buflen; k++) {
352 crc = crc32_table[(crc ^ *pos) & 0xff] ^ (crc >> 8);
354 j = (j + S[i]) & 0xff;
356 *pos++ ^= S[(S[i] + S[j]) & 0xff];
358 if (m->m_next == NULL) {
359 if (data_len != 0) { /* out of data */
360 IEEE80211_DPRINTF(ctx->wc_ic,
361 IEEE80211_MSG_CRYPTO,
362 "[%s] out of data for WEP (data_len %zu)\n",
363 ether_sprintf(mtod(m0,
364 struct ieee80211_frame *)->i_addr2),
371 pos = mtod(m, uint8_t *);
376 /* Append little-endian CRC32 and encrypt it to produce ICV */
381 for (k = 0; k < IEEE80211_WEP_CRCLEN; k++) {
383 j = (j + S[i]) & 0xff;
385 icv[k] ^= S[(S[i] + S[j]) & 0xff];
387 return m_append(m0, IEEE80211_WEP_CRCLEN, icv);
392 wep_decrypt(struct ieee80211_key *key, struct mbuf *m0, int hdrlen)
394 #define S_SWAP(a,b) do { uint8_t t = S[a]; S[a] = S[b]; S[b] = t; } while(0)
395 struct wep_ctx *ctx = key->wk_private;
397 u_int8_t rc4key[IEEE80211_WEP_IVLEN + IEEE80211_KEYBUF_SIZE];
398 uint8_t icv[IEEE80211_WEP_CRCLEN];
399 uint32_t i, j, k, crc;
400 size_t buflen, data_len;
405 ctx->wc_ic->ic_stats.is_crypto_wep++;
407 /* NB: this assumes the header was pulled up */
408 memcpy(rc4key, mtod(m, u_int8_t *) + hdrlen, IEEE80211_WEP_IVLEN);
409 memcpy(rc4key + IEEE80211_WEP_IVLEN, key->wk_key, key->wk_keylen);
411 /* Setup RC4 state */
412 for (i = 0; i < 256; i++)
415 keylen = key->wk_keylen + IEEE80211_WEP_IVLEN;
416 for (i = 0; i < 256; i++) {
417 j = (j + S[i] + rc4key[i % keylen]) & 0xff;
421 off = hdrlen + wep.ic_header;
422 data_len = m->m_pkthdr.len - (off + wep.ic_trailer),
424 /* Compute CRC32 over unencrypted data and apply RC4 to data */
427 pos = mtod(m, uint8_t *) + off;
428 buflen = m->m_len - off;
430 if (buflen > data_len)
433 for (k = 0; k < buflen; k++) {
435 j = (j + S[i]) & 0xff;
437 *pos ^= S[(S[i] + S[j]) & 0xff];
438 crc = crc32_table[(crc ^ *pos) & 0xff] ^ (crc >> 8);
443 if (data_len != 0) { /* out of data */
444 IEEE80211_DPRINTF(ctx->wc_ic,
445 IEEE80211_MSG_CRYPTO,
446 "[%s] out of data for WEP (data_len %zu)\n",
447 ether_sprintf(mtod(m0,
448 struct ieee80211_frame *)->i_addr2),
454 pos = mtod(m, uint8_t *);
459 /* Encrypt little-endian CRC32 and verify that it matches with
465 for (k = 0; k < IEEE80211_WEP_CRCLEN; k++) {
467 j = (j + S[i]) & 0xff;
469 /* XXX assumes ICV is contiguous in mbuf */
470 if ((icv[k] ^ S[(S[i] + S[j]) & 0xff]) != *pos++) {
471 /* ICV mismatch - drop frame */
483 wep_modevent(module_t mod, int type, void *unused)
487 ieee80211_crypto_register(&wep);
492 printf("wlan_wep: still in use (%u dynamic refs)\n",
496 if (type == MOD_UNLOAD)
497 ieee80211_crypto_unregister(&wep);
503 static moduledata_t wep_mod = {
508 DECLARE_MODULE(wlan_wep, wep_mod, SI_SUB_DRIVERS, SI_ORDER_FIRST);
509 MODULE_VERSION(wlan_wep, 1);
510 MODULE_DEPEND(wlan_wep, wlan, 1, 1, 1);