2 * Copyright (c) 2002-2008 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.
34 #include <sys/param.h>
35 #include <sys/systm.h>
37 #include <sys/malloc.h>
38 #include <sys/kernel.h>
39 #include <sys/module.h>
40 #include <sys/endian.h>
42 #include <sys/socket.h>
45 #include <net/if_var.h>
46 #include <net/if_media.h>
47 #include <net/ethernet.h>
49 #include <netproto/802_11/ieee80211_var.h>
51 static void *wep_attach(struct ieee80211vap *, struct ieee80211_key *);
52 static void wep_detach(struct ieee80211_key *);
53 static int wep_setkey(struct ieee80211_key *);
54 static void wep_setiv(struct ieee80211_key *, uint8_t *);
55 static int wep_encap(struct ieee80211_key *, struct mbuf *);
56 static int wep_decap(struct ieee80211_key *, struct mbuf *, int);
57 static int wep_enmic(struct ieee80211_key *, struct mbuf *, int);
58 static int wep_demic(struct ieee80211_key *, struct mbuf *, int);
60 static const struct ieee80211_cipher wep = {
62 .ic_cipher = IEEE80211_CIPHER_WEP,
63 .ic_header = IEEE80211_WEP_IVLEN + IEEE80211_WEP_KIDLEN,
64 .ic_trailer = IEEE80211_WEP_CRCLEN,
66 .ic_attach = wep_attach,
67 .ic_detach = wep_detach,
68 .ic_setkey = wep_setkey,
69 .ic_setiv = wep_setiv,
70 .ic_encap = wep_encap,
71 .ic_decap = wep_decap,
72 .ic_enmic = wep_enmic,
73 .ic_demic = wep_demic,
76 static int wep_encrypt(struct ieee80211_key *, struct mbuf *, int hdrlen);
77 static int wep_decrypt(struct ieee80211_key *, struct mbuf *, int hdrlen);
80 struct ieee80211vap *wc_vap; /* for diagnostics+statistics */
81 struct ieee80211com *wc_ic;
82 uint32_t wc_iv; /* initial vector for crypto */
85 /* number of references from net80211 layer */
89 wep_attach(struct ieee80211vap *vap, struct ieee80211_key *k)
93 #if defined(__DragonFly__)
94 ctx = (struct wep_ctx *) kmalloc(sizeof(struct wep_ctx),
95 M_80211_CRYPTO, M_INTWAIT | M_ZERO);
97 ctx = (struct wep_ctx *) IEEE80211_MALLOC(sizeof(struct wep_ctx),
98 M_80211_CRYPTO, IEEE80211_M_NOWAIT | IEEE80211_M_ZERO);
101 vap->iv_stats.is_crypto_nomem++;
106 ctx->wc_ic = vap->iv_ic;
107 get_random_bytes(&ctx->wc_iv, sizeof(ctx->wc_iv));
108 nrefs++; /* NB: we assume caller locking */
113 wep_detach(struct ieee80211_key *k)
115 struct wep_ctx *ctx = k->wk_private;
117 IEEE80211_FREE(ctx, M_80211_CRYPTO);
118 KASSERT(nrefs > 0, ("imbalanced attach/detach"));
119 nrefs--; /* NB: we assume caller locking */
123 wep_setkey(struct ieee80211_key *k)
125 return k->wk_keylen >= 40/NBBY;
129 wep_setiv(struct ieee80211_key *k, uint8_t *ivp)
131 struct wep_ctx *ctx = k->wk_private;
132 struct ieee80211vap *vap = ctx->wc_vap;
136 keyid = ieee80211_crypto_get_keyid(vap, k) << 6;
140 * IV must not duplicate during the lifetime of the key.
141 * But no mechanism to renew keys is defined in IEEE 802.11
142 * for WEP. And the IV may be duplicated at other stations
143 * because the session key itself is shared. So we use a
144 * pseudo random IV for now, though it is not the right way.
146 * NB: Rather than use a strictly random IV we select a
147 * random one to start and then increment the value for
148 * each frame. This is an explicit tradeoff between
149 * overhead and security. Given the basic insecurity of
150 * WEP this seems worthwhile.
154 * Skip 'bad' IVs from Fluhrer/Mantin/Shamir:
155 * (B, 255, N) with 3 <= B < 16 and 0 <= N <= 255
158 if ((iv & 0xff00) == 0xff00) {
159 int B = (iv & 0xff0000) >> 16;
160 if (3 <= B && B < 16)
166 * NB: Preserve byte order of IV for packet
167 * sniffers; it doesn't matter otherwise.
169 #if _BYTE_ORDER == _BIG_ENDIAN
182 * Add privacy headers appropriate for the specified key.
185 wep_encap(struct ieee80211_key *k, struct mbuf *m)
187 struct wep_ctx *ctx = k->wk_private;
188 struct ieee80211com *ic = ctx->wc_ic;
192 hdrlen = ieee80211_hdrspace(ic, mtod(m, void *));
195 * Copy down 802.11 header and add the IV + KeyID.
197 M_PREPEND(m, wep.ic_header, M_NOWAIT);
200 ivp = mtod(m, uint8_t *);
201 bcopy(ivp + wep.ic_header, ivp, hdrlen);
207 * Finally, do software encrypt if needed.
209 if ((k->wk_flags & IEEE80211_KEY_SWENCRYPT) &&
210 !wep_encrypt(k, m, hdrlen))
217 * Add MIC to the frame as needed.
220 wep_enmic(struct ieee80211_key *k, struct mbuf *m, int force)
227 * Validate and strip privacy headers (and trailer) for a
228 * received frame. If necessary, decrypt the frame using
232 wep_decap(struct ieee80211_key *k, struct mbuf *m, int hdrlen)
234 struct wep_ctx *ctx = k->wk_private;
235 struct ieee80211vap *vap = ctx->wc_vap;
236 struct ieee80211_frame *wh;
238 wh = mtod(m, struct ieee80211_frame *);
241 * Check if the device handled the decrypt in hardware.
242 * If so we just strip the header; otherwise we need to
243 * handle the decrypt in software.
245 if ((k->wk_flags & IEEE80211_KEY_SWDECRYPT) &&
246 !wep_decrypt(k, m, hdrlen)) {
247 IEEE80211_NOTE_MAC(vap, IEEE80211_MSG_CRYPTO, wh->i_addr2,
248 "%s", "WEP ICV mismatch on decrypt");
249 vap->iv_stats.is_rx_wepfail++;
254 * Copy up 802.11 header and strip crypto bits.
256 bcopy(mtod(m, void *), mtod(m, uint8_t *) + wep.ic_header, hdrlen);
257 m_adj(m, wep.ic_header);
258 m_adj(m, -wep.ic_trailer);
264 * Verify and strip MIC from the frame.
267 wep_demic(struct ieee80211_key *k, struct mbuf *skb, int force)
272 static const uint32_t crc32_table[256] = {
273 0x00000000L, 0x77073096L, 0xee0e612cL, 0x990951baL, 0x076dc419L,
274 0x706af48fL, 0xe963a535L, 0x9e6495a3L, 0x0edb8832L, 0x79dcb8a4L,
275 0xe0d5e91eL, 0x97d2d988L, 0x09b64c2bL, 0x7eb17cbdL, 0xe7b82d07L,
276 0x90bf1d91L, 0x1db71064L, 0x6ab020f2L, 0xf3b97148L, 0x84be41deL,
277 0x1adad47dL, 0x6ddde4ebL, 0xf4d4b551L, 0x83d385c7L, 0x136c9856L,
278 0x646ba8c0L, 0xfd62f97aL, 0x8a65c9ecL, 0x14015c4fL, 0x63066cd9L,
279 0xfa0f3d63L, 0x8d080df5L, 0x3b6e20c8L, 0x4c69105eL, 0xd56041e4L,
280 0xa2677172L, 0x3c03e4d1L, 0x4b04d447L, 0xd20d85fdL, 0xa50ab56bL,
281 0x35b5a8faL, 0x42b2986cL, 0xdbbbc9d6L, 0xacbcf940L, 0x32d86ce3L,
282 0x45df5c75L, 0xdcd60dcfL, 0xabd13d59L, 0x26d930acL, 0x51de003aL,
283 0xc8d75180L, 0xbfd06116L, 0x21b4f4b5L, 0x56b3c423L, 0xcfba9599L,
284 0xb8bda50fL, 0x2802b89eL, 0x5f058808L, 0xc60cd9b2L, 0xb10be924L,
285 0x2f6f7c87L, 0x58684c11L, 0xc1611dabL, 0xb6662d3dL, 0x76dc4190L,
286 0x01db7106L, 0x98d220bcL, 0xefd5102aL, 0x71b18589L, 0x06b6b51fL,
287 0x9fbfe4a5L, 0xe8b8d433L, 0x7807c9a2L, 0x0f00f934L, 0x9609a88eL,
288 0xe10e9818L, 0x7f6a0dbbL, 0x086d3d2dL, 0x91646c97L, 0xe6635c01L,
289 0x6b6b51f4L, 0x1c6c6162L, 0x856530d8L, 0xf262004eL, 0x6c0695edL,
290 0x1b01a57bL, 0x8208f4c1L, 0xf50fc457L, 0x65b0d9c6L, 0x12b7e950L,
291 0x8bbeb8eaL, 0xfcb9887cL, 0x62dd1ddfL, 0x15da2d49L, 0x8cd37cf3L,
292 0xfbd44c65L, 0x4db26158L, 0x3ab551ceL, 0xa3bc0074L, 0xd4bb30e2L,
293 0x4adfa541L, 0x3dd895d7L, 0xa4d1c46dL, 0xd3d6f4fbL, 0x4369e96aL,
294 0x346ed9fcL, 0xad678846L, 0xda60b8d0L, 0x44042d73L, 0x33031de5L,
295 0xaa0a4c5fL, 0xdd0d7cc9L, 0x5005713cL, 0x270241aaL, 0xbe0b1010L,
296 0xc90c2086L, 0x5768b525L, 0x206f85b3L, 0xb966d409L, 0xce61e49fL,
297 0x5edef90eL, 0x29d9c998L, 0xb0d09822L, 0xc7d7a8b4L, 0x59b33d17L,
298 0x2eb40d81L, 0xb7bd5c3bL, 0xc0ba6cadL, 0xedb88320L, 0x9abfb3b6L,
299 0x03b6e20cL, 0x74b1d29aL, 0xead54739L, 0x9dd277afL, 0x04db2615L,
300 0x73dc1683L, 0xe3630b12L, 0x94643b84L, 0x0d6d6a3eL, 0x7a6a5aa8L,
301 0xe40ecf0bL, 0x9309ff9dL, 0x0a00ae27L, 0x7d079eb1L, 0xf00f9344L,
302 0x8708a3d2L, 0x1e01f268L, 0x6906c2feL, 0xf762575dL, 0x806567cbL,
303 0x196c3671L, 0x6e6b06e7L, 0xfed41b76L, 0x89d32be0L, 0x10da7a5aL,
304 0x67dd4accL, 0xf9b9df6fL, 0x8ebeeff9L, 0x17b7be43L, 0x60b08ed5L,
305 0xd6d6a3e8L, 0xa1d1937eL, 0x38d8c2c4L, 0x4fdff252L, 0xd1bb67f1L,
306 0xa6bc5767L, 0x3fb506ddL, 0x48b2364bL, 0xd80d2bdaL, 0xaf0a1b4cL,
307 0x36034af6L, 0x41047a60L, 0xdf60efc3L, 0xa867df55L, 0x316e8eefL,
308 0x4669be79L, 0xcb61b38cL, 0xbc66831aL, 0x256fd2a0L, 0x5268e236L,
309 0xcc0c7795L, 0xbb0b4703L, 0x220216b9L, 0x5505262fL, 0xc5ba3bbeL,
310 0xb2bd0b28L, 0x2bb45a92L, 0x5cb36a04L, 0xc2d7ffa7L, 0xb5d0cf31L,
311 0x2cd99e8bL, 0x5bdeae1dL, 0x9b64c2b0L, 0xec63f226L, 0x756aa39cL,
312 0x026d930aL, 0x9c0906a9L, 0xeb0e363fL, 0x72076785L, 0x05005713L,
313 0x95bf4a82L, 0xe2b87a14L, 0x7bb12baeL, 0x0cb61b38L, 0x92d28e9bL,
314 0xe5d5be0dL, 0x7cdcefb7L, 0x0bdbdf21L, 0x86d3d2d4L, 0xf1d4e242L,
315 0x68ddb3f8L, 0x1fda836eL, 0x81be16cdL, 0xf6b9265bL, 0x6fb077e1L,
316 0x18b74777L, 0x88085ae6L, 0xff0f6a70L, 0x66063bcaL, 0x11010b5cL,
317 0x8f659effL, 0xf862ae69L, 0x616bffd3L, 0x166ccf45L, 0xa00ae278L,
318 0xd70dd2eeL, 0x4e048354L, 0x3903b3c2L, 0xa7672661L, 0xd06016f7L,
319 0x4969474dL, 0x3e6e77dbL, 0xaed16a4aL, 0xd9d65adcL, 0x40df0b66L,
320 0x37d83bf0L, 0xa9bcae53L, 0xdebb9ec5L, 0x47b2cf7fL, 0x30b5ffe9L,
321 0xbdbdf21cL, 0xcabac28aL, 0x53b39330L, 0x24b4a3a6L, 0xbad03605L,
322 0xcdd70693L, 0x54de5729L, 0x23d967bfL, 0xb3667a2eL, 0xc4614ab8L,
323 0x5d681b02L, 0x2a6f2b94L, 0xb40bbe37L, 0xc30c8ea1L, 0x5a05df1bL,
328 wep_encrypt(struct ieee80211_key *key, struct mbuf *m0, int hdrlen)
330 #define S_SWAP(a,b) do { uint8_t t = S[a]; S[a] = S[b]; S[b] = t; } while(0)
331 struct wep_ctx *ctx = key->wk_private;
332 struct ieee80211vap *vap = ctx->wc_vap;
334 uint8_t rc4key[IEEE80211_WEP_IVLEN + IEEE80211_KEYBUF_SIZE];
335 uint8_t icv[IEEE80211_WEP_CRCLEN];
336 uint32_t i, j, k, crc;
337 size_t buflen, data_len;
342 vap->iv_stats.is_crypto_wep++;
344 /* NB: this assumes the header was pulled up */
345 memcpy(rc4key, mtod(m, uint8_t *) + hdrlen, IEEE80211_WEP_IVLEN);
346 memcpy(rc4key + IEEE80211_WEP_IVLEN, key->wk_key, key->wk_keylen);
348 /* Setup RC4 state */
349 for (i = 0; i < 256; i++)
352 keylen = key->wk_keylen + IEEE80211_WEP_IVLEN;
353 for (i = 0; i < 256; i++) {
354 j = (j + S[i] + rc4key[i % keylen]) & 0xff;
358 off = hdrlen + wep.ic_header;
359 data_len = m->m_pkthdr.len - off;
361 /* Compute CRC32 over unencrypted data and apply RC4 to data */
364 pos = mtod(m, uint8_t *) + off;
365 buflen = m->m_len - off;
367 if (buflen > data_len)
370 for (k = 0; k < buflen; k++) {
371 crc = crc32_table[(crc ^ *pos) & 0xff] ^ (crc >> 8);
373 j = (j + S[i]) & 0xff;
375 *pos++ ^= S[(S[i] + S[j]) & 0xff];
377 if (m->m_next == NULL) {
378 if (data_len != 0) { /* out of data */
379 IEEE80211_NOTE_MAC(vap, IEEE80211_MSG_CRYPTO,
380 ether_sprintf(mtod(m0,
381 struct ieee80211_frame *)->i_addr2),
382 "out of data for WEP (data_len %zu)",
390 pos = mtod(m, uint8_t *);
395 /* Append little-endian CRC32 and encrypt it to produce ICV */
400 for (k = 0; k < IEEE80211_WEP_CRCLEN; k++) {
402 j = (j + S[i]) & 0xff;
404 icv[k] ^= S[(S[i] + S[j]) & 0xff];
406 return m_append(m0, IEEE80211_WEP_CRCLEN, icv);
411 wep_decrypt(struct ieee80211_key *key, struct mbuf *m0, int hdrlen)
413 #define S_SWAP(a,b) do { uint8_t t = S[a]; S[a] = S[b]; S[b] = t; } while(0)
414 struct wep_ctx *ctx = key->wk_private;
415 struct ieee80211vap *vap = ctx->wc_vap;
417 uint8_t rc4key[IEEE80211_WEP_IVLEN + IEEE80211_KEYBUF_SIZE];
418 uint8_t icv[IEEE80211_WEP_CRCLEN];
419 uint32_t i, j, k, crc;
420 size_t buflen, data_len;
425 vap->iv_stats.is_crypto_wep++;
427 /* NB: this assumes the header was pulled up */
428 memcpy(rc4key, mtod(m, uint8_t *) + hdrlen, IEEE80211_WEP_IVLEN);
429 memcpy(rc4key + IEEE80211_WEP_IVLEN, key->wk_key, key->wk_keylen);
431 /* Setup RC4 state */
432 for (i = 0; i < 256; i++)
435 keylen = key->wk_keylen + IEEE80211_WEP_IVLEN;
436 for (i = 0; i < 256; i++) {
437 j = (j + S[i] + rc4key[i % keylen]) & 0xff;
441 off = hdrlen + wep.ic_header;
442 data_len = m->m_pkthdr.len - (off + wep.ic_trailer);
444 /* Compute CRC32 over unencrypted data and apply RC4 to data */
447 pos = mtod(m, uint8_t *) + off;
448 buflen = m->m_len - off;
450 if (buflen > data_len)
453 for (k = 0; k < buflen; k++) {
455 j = (j + S[i]) & 0xff;
457 *pos ^= S[(S[i] + S[j]) & 0xff];
458 crc = crc32_table[(crc ^ *pos) & 0xff] ^ (crc >> 8);
463 if (data_len != 0) { /* out of data */
464 IEEE80211_NOTE_MAC(vap, IEEE80211_MSG_CRYPTO,
465 mtod(m0, struct ieee80211_frame *)->i_addr2,
466 "out of data for WEP (data_len %zu)",
472 pos = mtod(m, uint8_t *);
477 /* Encrypt little-endian CRC32 and verify that it matches with
483 for (k = 0; k < IEEE80211_WEP_CRCLEN; k++) {
485 j = (j + S[i]) & 0xff;
487 /* XXX assumes ICV is contiguous in mbuf */
488 if ((icv[k] ^ S[(S[i] + S[j]) & 0xff]) != *pos++) {
489 /* ICV mismatch - drop frame */
500 IEEE80211_CRYPTO_MODULE(wep, 1);