2 * Copyright (c) 2002-2007 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.
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
15 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
16 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
17 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
18 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
19 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
20 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
21 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
23 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26 #include <sys/cdefs.h>
27 __FBSDID("$FreeBSD$");
30 * IEEE 802.11 WEP crypto support.
32 #include <sys/param.h>
33 #include <sys/systm.h>
35 #include <sys/malloc.h>
36 #include <sys/kernel.h>
37 #include <sys/module.h>
38 #include <sys/endian.h>
40 #include <sys/socket.h>
43 #include <net/if_media.h>
44 #include <net/ethernet.h>
46 #include <net80211/ieee80211_var.h>
48 static void *wep_attach(struct ieee80211com *, struct ieee80211_key *);
49 static void wep_detach(struct ieee80211_key *);
50 static int wep_setkey(struct ieee80211_key *);
51 static int wep_encap(struct ieee80211_key *, struct mbuf *, u_int8_t keyid);
52 static int wep_decap(struct ieee80211_key *, struct mbuf *, int hdrlen);
53 static int wep_enmic(struct ieee80211_key *, struct mbuf *, int);
54 static int wep_demic(struct ieee80211_key *, struct mbuf *, int);
56 static const struct ieee80211_cipher wep = {
58 .ic_cipher = IEEE80211_CIPHER_WEP,
59 .ic_header = IEEE80211_WEP_IVLEN + IEEE80211_WEP_KIDLEN,
60 .ic_trailer = IEEE80211_WEP_CRCLEN,
62 .ic_attach = wep_attach,
63 .ic_detach = wep_detach,
64 .ic_setkey = wep_setkey,
65 .ic_encap = wep_encap,
66 .ic_decap = wep_decap,
67 .ic_enmic = wep_enmic,
68 .ic_demic = wep_demic,
71 static int wep_encrypt(struct ieee80211_key *, struct mbuf *, int hdrlen);
72 static int wep_decrypt(struct ieee80211_key *, struct mbuf *, int hdrlen);
75 struct ieee80211com *wc_ic; /* for diagnostics */
76 u_int32_t wc_iv; /* initial vector for crypto */
79 /* number of references from net80211 layer */
83 wep_attach(struct ieee80211com *ic, struct ieee80211_key *k)
87 MALLOC(ctx, struct wep_ctx *, sizeof(struct wep_ctx),
88 M_DEVBUF, M_NOWAIT | M_ZERO);
90 ic->ic_stats.is_crypto_nomem++;
95 get_random_bytes(&ctx->wc_iv, sizeof(ctx->wc_iv));
96 nrefs++; /* NB: we assume caller locking */
101 wep_detach(struct ieee80211_key *k)
103 struct wep_ctx *ctx = k->wk_private;
106 KASSERT(nrefs > 0, ("imbalanced attach/detach"));
107 nrefs--; /* NB: we assume caller locking */
111 wep_setkey(struct ieee80211_key *k)
113 return k->wk_keylen >= 40/NBBY;
117 * Add privacy headers appropriate for the specified key.
120 wep_encap(struct ieee80211_key *k, struct mbuf *m, u_int8_t keyid)
122 struct wep_ctx *ctx = k->wk_private;
123 struct ieee80211com *ic = ctx->wc_ic;
128 hdrlen = ieee80211_hdrspace(ic, mtod(m, void *));
131 * Copy down 802.11 header and add the IV + KeyID.
133 M_PREPEND(m, wep.ic_header, M_NOWAIT);
136 ivp = mtod(m, u_int8_t *);
137 ovbcopy(ivp + wep.ic_header, ivp, hdrlen);
142 * IV must not duplicate during the lifetime of the key.
143 * But no mechanism to renew keys is defined in IEEE 802.11
144 * for WEP. And the IV may be duplicated at other stations
145 * because the session key itself is shared. So we use a
146 * pseudo random IV for now, though it is not the right way.
148 * NB: Rather than use a strictly random IV we select a
149 * random one to start and then increment the value for
150 * each frame. This is an explicit tradeoff between
151 * overhead and security. Given the basic insecurity of
152 * WEP this seems worthwhile.
156 * Skip 'bad' IVs from Fluhrer/Mantin/Shamir:
157 * (B, 255, N) with 3 <= B < 16 and 0 <= N <= 255
160 if ((iv & 0xff00) == 0xff00) {
161 int B = (iv & 0xff0000) >> 16;
162 if (3 <= B && B < 16)
168 * NB: Preserve byte order of IV for packet
169 * sniffers; it doesn't matter otherwise.
171 #if _BYTE_ORDER == _BIG_ENDIAN
183 * Finally, do software encrypt if neeed.
185 if ((k->wk_flags & IEEE80211_KEY_SWCRYPT) &&
186 !wep_encrypt(k, m, hdrlen))
193 * Add MIC to the frame as needed.
196 wep_enmic(struct ieee80211_key *k, struct mbuf *m, int force)
203 * Validate and strip privacy headers (and trailer) for a
204 * received frame. If necessary, decrypt the frame using
208 wep_decap(struct ieee80211_key *k, struct mbuf *m, int hdrlen)
210 struct wep_ctx *ctx = k->wk_private;
211 struct ieee80211_frame *wh;
213 wh = mtod(m, struct ieee80211_frame *);
216 * Check if the device handled the decrypt in hardware.
217 * If so we just strip the header; otherwise we need to
218 * handle the decrypt in software.
220 if ((k->wk_flags & IEEE80211_KEY_SWCRYPT) &&
221 !wep_decrypt(k, m, hdrlen)) {
222 IEEE80211_DPRINTF(ctx->wc_ic, IEEE80211_MSG_CRYPTO,
223 "[%s] WEP ICV mismatch on decrypt\n",
224 ether_sprintf(wh->i_addr2));
225 ctx->wc_ic->ic_stats.is_rx_wepfail++;
230 * Copy up 802.11 header and strip crypto bits.
232 ovbcopy(mtod(m, void *), mtod(m, u_int8_t *) + wep.ic_header, hdrlen);
233 m_adj(m, wep.ic_header);
234 m_adj(m, -wep.ic_trailer);
240 * Verify and strip MIC from the frame.
243 wep_demic(struct ieee80211_key *k, struct mbuf *skb, int force)
248 static const uint32_t crc32_table[256] = {
249 0x00000000L, 0x77073096L, 0xee0e612cL, 0x990951baL, 0x076dc419L,
250 0x706af48fL, 0xe963a535L, 0x9e6495a3L, 0x0edb8832L, 0x79dcb8a4L,
251 0xe0d5e91eL, 0x97d2d988L, 0x09b64c2bL, 0x7eb17cbdL, 0xe7b82d07L,
252 0x90bf1d91L, 0x1db71064L, 0x6ab020f2L, 0xf3b97148L, 0x84be41deL,
253 0x1adad47dL, 0x6ddde4ebL, 0xf4d4b551L, 0x83d385c7L, 0x136c9856L,
254 0x646ba8c0L, 0xfd62f97aL, 0x8a65c9ecL, 0x14015c4fL, 0x63066cd9L,
255 0xfa0f3d63L, 0x8d080df5L, 0x3b6e20c8L, 0x4c69105eL, 0xd56041e4L,
256 0xa2677172L, 0x3c03e4d1L, 0x4b04d447L, 0xd20d85fdL, 0xa50ab56bL,
257 0x35b5a8faL, 0x42b2986cL, 0xdbbbc9d6L, 0xacbcf940L, 0x32d86ce3L,
258 0x45df5c75L, 0xdcd60dcfL, 0xabd13d59L, 0x26d930acL, 0x51de003aL,
259 0xc8d75180L, 0xbfd06116L, 0x21b4f4b5L, 0x56b3c423L, 0xcfba9599L,
260 0xb8bda50fL, 0x2802b89eL, 0x5f058808L, 0xc60cd9b2L, 0xb10be924L,
261 0x2f6f7c87L, 0x58684c11L, 0xc1611dabL, 0xb6662d3dL, 0x76dc4190L,
262 0x01db7106L, 0x98d220bcL, 0xefd5102aL, 0x71b18589L, 0x06b6b51fL,
263 0x9fbfe4a5L, 0xe8b8d433L, 0x7807c9a2L, 0x0f00f934L, 0x9609a88eL,
264 0xe10e9818L, 0x7f6a0dbbL, 0x086d3d2dL, 0x91646c97L, 0xe6635c01L,
265 0x6b6b51f4L, 0x1c6c6162L, 0x856530d8L, 0xf262004eL, 0x6c0695edL,
266 0x1b01a57bL, 0x8208f4c1L, 0xf50fc457L, 0x65b0d9c6L, 0x12b7e950L,
267 0x8bbeb8eaL, 0xfcb9887cL, 0x62dd1ddfL, 0x15da2d49L, 0x8cd37cf3L,
268 0xfbd44c65L, 0x4db26158L, 0x3ab551ceL, 0xa3bc0074L, 0xd4bb30e2L,
269 0x4adfa541L, 0x3dd895d7L, 0xa4d1c46dL, 0xd3d6f4fbL, 0x4369e96aL,
270 0x346ed9fcL, 0xad678846L, 0xda60b8d0L, 0x44042d73L, 0x33031de5L,
271 0xaa0a4c5fL, 0xdd0d7cc9L, 0x5005713cL, 0x270241aaL, 0xbe0b1010L,
272 0xc90c2086L, 0x5768b525L, 0x206f85b3L, 0xb966d409L, 0xce61e49fL,
273 0x5edef90eL, 0x29d9c998L, 0xb0d09822L, 0xc7d7a8b4L, 0x59b33d17L,
274 0x2eb40d81L, 0xb7bd5c3bL, 0xc0ba6cadL, 0xedb88320L, 0x9abfb3b6L,
275 0x03b6e20cL, 0x74b1d29aL, 0xead54739L, 0x9dd277afL, 0x04db2615L,
276 0x73dc1683L, 0xe3630b12L, 0x94643b84L, 0x0d6d6a3eL, 0x7a6a5aa8L,
277 0xe40ecf0bL, 0x9309ff9dL, 0x0a00ae27L, 0x7d079eb1L, 0xf00f9344L,
278 0x8708a3d2L, 0x1e01f268L, 0x6906c2feL, 0xf762575dL, 0x806567cbL,
279 0x196c3671L, 0x6e6b06e7L, 0xfed41b76L, 0x89d32be0L, 0x10da7a5aL,
280 0x67dd4accL, 0xf9b9df6fL, 0x8ebeeff9L, 0x17b7be43L, 0x60b08ed5L,
281 0xd6d6a3e8L, 0xa1d1937eL, 0x38d8c2c4L, 0x4fdff252L, 0xd1bb67f1L,
282 0xa6bc5767L, 0x3fb506ddL, 0x48b2364bL, 0xd80d2bdaL, 0xaf0a1b4cL,
283 0x36034af6L, 0x41047a60L, 0xdf60efc3L, 0xa867df55L, 0x316e8eefL,
284 0x4669be79L, 0xcb61b38cL, 0xbc66831aL, 0x256fd2a0L, 0x5268e236L,
285 0xcc0c7795L, 0xbb0b4703L, 0x220216b9L, 0x5505262fL, 0xc5ba3bbeL,
286 0xb2bd0b28L, 0x2bb45a92L, 0x5cb36a04L, 0xc2d7ffa7L, 0xb5d0cf31L,
287 0x2cd99e8bL, 0x5bdeae1dL, 0x9b64c2b0L, 0xec63f226L, 0x756aa39cL,
288 0x026d930aL, 0x9c0906a9L, 0xeb0e363fL, 0x72076785L, 0x05005713L,
289 0x95bf4a82L, 0xe2b87a14L, 0x7bb12baeL, 0x0cb61b38L, 0x92d28e9bL,
290 0xe5d5be0dL, 0x7cdcefb7L, 0x0bdbdf21L, 0x86d3d2d4L, 0xf1d4e242L,
291 0x68ddb3f8L, 0x1fda836eL, 0x81be16cdL, 0xf6b9265bL, 0x6fb077e1L,
292 0x18b74777L, 0x88085ae6L, 0xff0f6a70L, 0x66063bcaL, 0x11010b5cL,
293 0x8f659effL, 0xf862ae69L, 0x616bffd3L, 0x166ccf45L, 0xa00ae278L,
294 0xd70dd2eeL, 0x4e048354L, 0x3903b3c2L, 0xa7672661L, 0xd06016f7L,
295 0x4969474dL, 0x3e6e77dbL, 0xaed16a4aL, 0xd9d65adcL, 0x40df0b66L,
296 0x37d83bf0L, 0xa9bcae53L, 0xdebb9ec5L, 0x47b2cf7fL, 0x30b5ffe9L,
297 0xbdbdf21cL, 0xcabac28aL, 0x53b39330L, 0x24b4a3a6L, 0xbad03605L,
298 0xcdd70693L, 0x54de5729L, 0x23d967bfL, 0xb3667a2eL, 0xc4614ab8L,
299 0x5d681b02L, 0x2a6f2b94L, 0xb40bbe37L, 0xc30c8ea1L, 0x5a05df1bL,
304 wep_encrypt(struct ieee80211_key *key, struct mbuf *m0, int hdrlen)
306 #define S_SWAP(a,b) do { uint8_t t = S[a]; S[a] = S[b]; S[b] = t; } while(0)
307 struct wep_ctx *ctx = key->wk_private;
309 u_int8_t rc4key[IEEE80211_WEP_IVLEN + IEEE80211_KEYBUF_SIZE];
310 uint8_t icv[IEEE80211_WEP_CRCLEN];
311 uint32_t i, j, k, crc;
312 size_t buflen, data_len;
317 ctx->wc_ic->ic_stats.is_crypto_wep++;
319 /* NB: this assumes the header was pulled up */
320 memcpy(rc4key, mtod(m, u_int8_t *) + hdrlen, IEEE80211_WEP_IVLEN);
321 memcpy(rc4key + IEEE80211_WEP_IVLEN, key->wk_key, key->wk_keylen);
323 /* Setup RC4 state */
324 for (i = 0; i < 256; i++)
327 keylen = key->wk_keylen + IEEE80211_WEP_IVLEN;
328 for (i = 0; i < 256; i++) {
329 j = (j + S[i] + rc4key[i % keylen]) & 0xff;
333 off = hdrlen + wep.ic_header;
334 data_len = m->m_pkthdr.len - off;
336 /* Compute CRC32 over unencrypted data and apply RC4 to data */
339 pos = mtod(m, uint8_t *) + off;
340 buflen = m->m_len - off;
342 if (buflen > data_len)
345 for (k = 0; k < buflen; k++) {
346 crc = crc32_table[(crc ^ *pos) & 0xff] ^ (crc >> 8);
348 j = (j + S[i]) & 0xff;
350 *pos++ ^= S[(S[i] + S[j]) & 0xff];
352 if (m->m_next == NULL) {
353 if (data_len != 0) { /* out of data */
354 IEEE80211_DPRINTF(ctx->wc_ic,
355 IEEE80211_MSG_CRYPTO,
356 "[%s] out of data for WEP (data_len %zu)\n",
357 ether_sprintf(mtod(m0,
358 struct ieee80211_frame *)->i_addr2),
365 pos = mtod(m, uint8_t *);
370 /* Append little-endian CRC32 and encrypt it to produce ICV */
375 for (k = 0; k < IEEE80211_WEP_CRCLEN; k++) {
377 j = (j + S[i]) & 0xff;
379 icv[k] ^= S[(S[i] + S[j]) & 0xff];
381 return m_append(m0, IEEE80211_WEP_CRCLEN, icv);
386 wep_decrypt(struct ieee80211_key *key, struct mbuf *m0, int hdrlen)
388 #define S_SWAP(a,b) do { uint8_t t = S[a]; S[a] = S[b]; S[b] = t; } while(0)
389 struct wep_ctx *ctx = key->wk_private;
391 u_int8_t rc4key[IEEE80211_WEP_IVLEN + IEEE80211_KEYBUF_SIZE];
392 uint8_t icv[IEEE80211_WEP_CRCLEN];
393 uint32_t i, j, k, crc;
394 size_t buflen, data_len;
399 ctx->wc_ic->ic_stats.is_crypto_wep++;
401 /* NB: this assumes the header was pulled up */
402 memcpy(rc4key, mtod(m, u_int8_t *) + hdrlen, IEEE80211_WEP_IVLEN);
403 memcpy(rc4key + IEEE80211_WEP_IVLEN, key->wk_key, key->wk_keylen);
405 /* Setup RC4 state */
406 for (i = 0; i < 256; i++)
409 keylen = key->wk_keylen + IEEE80211_WEP_IVLEN;
410 for (i = 0; i < 256; i++) {
411 j = (j + S[i] + rc4key[i % keylen]) & 0xff;
415 off = hdrlen + wep.ic_header;
416 data_len = m->m_pkthdr.len - (off + wep.ic_trailer),
418 /* Compute CRC32 over unencrypted data and apply RC4 to data */
421 pos = mtod(m, uint8_t *) + off;
422 buflen = m->m_len - off;
424 if (buflen > data_len)
427 for (k = 0; k < buflen; k++) {
429 j = (j + S[i]) & 0xff;
431 *pos ^= S[(S[i] + S[j]) & 0xff];
432 crc = crc32_table[(crc ^ *pos) & 0xff] ^ (crc >> 8);
437 if (data_len != 0) { /* out of data */
438 IEEE80211_DPRINTF(ctx->wc_ic,
439 IEEE80211_MSG_CRYPTO,
440 "[%s] out of data for WEP (data_len %zu)\n",
441 ether_sprintf(mtod(m0,
442 struct ieee80211_frame *)->i_addr2),
448 pos = mtod(m, uint8_t *);
453 /* Encrypt little-endian CRC32 and verify that it matches with
459 for (k = 0; k < IEEE80211_WEP_CRCLEN; k++) {
461 j = (j + S[i]) & 0xff;
463 /* XXX assumes ICV is contiguous in mbuf */
464 if ((icv[k] ^ S[(S[i] + S[j]) & 0xff]) != *pos++) {
465 /* ICV mismatch - drop frame */
477 wep_modevent(module_t mod, int type, void *unused)
481 ieee80211_crypto_register(&wep);
486 printf("wlan_wep: still in use (%u dynamic refs)\n",
490 if (type == MOD_UNLOAD)
491 ieee80211_crypto_unregister(&wep);
497 static moduledata_t wep_mod = {
502 DECLARE_MODULE(wlan_wep, wep_mod, SI_SUB_DRIVERS, SI_ORDER_FIRST);
503 MODULE_VERSION(wlan_wep, 1);
504 MODULE_DEPEND(wlan_wep, wlan, 1, 1, 1);