2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
4 * Copyright (c) 2002-2008 Sam Leffler, Errno Consulting
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
17 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
18 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
19 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
21 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
22 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
23 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
25 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
28 #include <sys/cdefs.h>
29 __FBSDID("$FreeBSD$");
32 * IEEE 802.11 WEP crypto support.
36 #include <sys/param.h>
37 #include <sys/systm.h>
39 #include <sys/malloc.h>
40 #include <sys/kernel.h>
41 #include <sys/module.h>
42 #include <sys/endian.h>
44 #include <sys/socket.h>
47 #include <net/if_media.h>
48 #include <net/ethernet.h>
50 #include <net80211/ieee80211_var.h>
52 static void *wep_attach(struct ieee80211vap *, struct ieee80211_key *);
53 static void wep_detach(struct ieee80211_key *);
54 static int wep_setkey(struct ieee80211_key *);
55 static void wep_setiv(struct ieee80211_key *, uint8_t *);
56 static int wep_encap(struct ieee80211_key *, struct mbuf *);
57 static int wep_decap(struct ieee80211_key *, struct mbuf *, int);
58 static int wep_enmic(struct ieee80211_key *, struct mbuf *, int);
59 static int wep_demic(struct ieee80211_key *, struct mbuf *, int);
61 static const struct ieee80211_cipher wep = {
63 .ic_cipher = IEEE80211_CIPHER_WEP,
64 .ic_header = IEEE80211_WEP_IVLEN + IEEE80211_WEP_KIDLEN,
65 .ic_trailer = IEEE80211_WEP_CRCLEN,
67 .ic_attach = wep_attach,
68 .ic_detach = wep_detach,
69 .ic_setkey = wep_setkey,
70 .ic_setiv = wep_setiv,
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 ieee80211vap *wc_vap; /* for diagnostics+statistics */
82 struct ieee80211com *wc_ic;
83 uint32_t wc_iv; /* initial vector for crypto */
86 /* number of references from net80211 layer */
90 wep_attach(struct ieee80211vap *vap, struct ieee80211_key *k)
94 ctx = (struct wep_ctx *) IEEE80211_MALLOC(sizeof(struct wep_ctx),
95 M_80211_CRYPTO, IEEE80211_M_NOWAIT | IEEE80211_M_ZERO);
97 vap->iv_stats.is_crypto_nomem++;
102 ctx->wc_ic = vap->iv_ic;
103 get_random_bytes(&ctx->wc_iv, sizeof(ctx->wc_iv));
104 nrefs++; /* NB: we assume caller locking */
109 wep_detach(struct ieee80211_key *k)
111 struct wep_ctx *ctx = k->wk_private;
113 IEEE80211_FREE(ctx, M_80211_CRYPTO);
114 KASSERT(nrefs > 0, ("imbalanced attach/detach"));
115 nrefs--; /* NB: we assume caller locking */
119 wep_setkey(struct ieee80211_key *k)
121 return k->wk_keylen >= 40/NBBY;
125 wep_setiv(struct ieee80211_key *k, uint8_t *ivp)
127 struct wep_ctx *ctx = k->wk_private;
128 struct ieee80211vap *vap = ctx->wc_vap;
132 keyid = ieee80211_crypto_get_keyid(vap, k) << 6;
136 * IV must not duplicate during the lifetime of the key.
137 * But no mechanism to renew keys is defined in IEEE 802.11
138 * for WEP. And the IV may be duplicated at other stations
139 * because the session key itself is shared. So we use a
140 * pseudo random IV for now, though it is not the right way.
142 * NB: Rather than use a strictly random IV we select a
143 * random one to start and then increment the value for
144 * each frame. This is an explicit tradeoff between
145 * overhead and security. Given the basic insecurity of
146 * WEP this seems worthwhile.
150 * Skip 'bad' IVs from Fluhrer/Mantin/Shamir:
151 * (B, 255, N) with 3 <= B < 16 and 0 <= N <= 255
154 if ((iv & 0xff00) == 0xff00) {
155 int B = (iv & 0xff0000) >> 16;
156 if (3 <= B && B < 16)
162 * NB: Preserve byte order of IV for packet
163 * sniffers; it doesn't matter otherwise.
165 #if _BYTE_ORDER == _BIG_ENDIAN
178 * Add privacy headers appropriate for the specified key.
181 wep_encap(struct ieee80211_key *k, struct mbuf *m)
183 struct wep_ctx *ctx = k->wk_private;
184 struct ieee80211com *ic = ctx->wc_ic;
185 struct ieee80211_frame *wh;
190 hdrlen = ieee80211_hdrspace(ic, mtod(m, void *));
191 wh = mtod(m, struct ieee80211_frame *);
192 is_mgmt = IEEE80211_IS_MGMT(wh);
195 * Check to see if IV is required.
197 if (is_mgmt && (k->wk_flags & IEEE80211_KEY_NOIVMGT))
199 if ((! is_mgmt) && (k->wk_flags & IEEE80211_KEY_NOIV))
203 * Copy down 802.11 header and add the IV + KeyID.
205 M_PREPEND(m, wep.ic_header, M_NOWAIT);
208 ivp = mtod(m, uint8_t *);
209 ovbcopy(ivp + wep.ic_header, ivp, hdrlen);
215 * Finally, do software encrypt if needed.
217 if ((k->wk_flags & IEEE80211_KEY_SWENCRYPT) &&
218 !wep_encrypt(k, m, hdrlen))
225 * Add MIC to the frame as needed.
228 wep_enmic(struct ieee80211_key *k, struct mbuf *m, int force)
235 * Validate and strip privacy headers (and trailer) for a
236 * received frame. If necessary, decrypt the frame using
240 wep_decap(struct ieee80211_key *k, struct mbuf *m, int hdrlen)
242 struct wep_ctx *ctx = k->wk_private;
243 struct ieee80211vap *vap = ctx->wc_vap;
244 struct ieee80211_frame *wh;
245 const struct ieee80211_rx_stats *rxs;
247 wh = mtod(m, struct ieee80211_frame *);
249 rxs = ieee80211_get_rx_params_ptr(m);
251 if ((rxs != NULL) && (rxs->c_pktflags & IEEE80211_RX_F_IV_STRIP))
255 * Check if the device handled the decrypt in hardware.
256 * If so we just strip the header; otherwise we need to
257 * handle the decrypt in software.
259 if ((k->wk_flags & IEEE80211_KEY_SWDECRYPT) &&
260 !wep_decrypt(k, m, hdrlen)) {
261 IEEE80211_NOTE_MAC(vap, IEEE80211_MSG_CRYPTO, wh->i_addr2,
262 "%s", "WEP ICV mismatch on decrypt");
263 vap->iv_stats.is_rx_wepfail++;
268 * Copy up 802.11 header and strip crypto bits.
270 ovbcopy(mtod(m, void *), mtod(m, uint8_t *) + wep.ic_header, hdrlen);
271 m_adj(m, wep.ic_header);
274 /* XXX TODO: do we have to strip this for offload devices? */
275 m_adj(m, -wep.ic_trailer);
281 * Verify and strip MIC from the frame.
284 wep_demic(struct ieee80211_key *k, struct mbuf *skb, int force)
289 static const uint32_t crc32_table[256] = {
290 0x00000000L, 0x77073096L, 0xee0e612cL, 0x990951baL, 0x076dc419L,
291 0x706af48fL, 0xe963a535L, 0x9e6495a3L, 0x0edb8832L, 0x79dcb8a4L,
292 0xe0d5e91eL, 0x97d2d988L, 0x09b64c2bL, 0x7eb17cbdL, 0xe7b82d07L,
293 0x90bf1d91L, 0x1db71064L, 0x6ab020f2L, 0xf3b97148L, 0x84be41deL,
294 0x1adad47dL, 0x6ddde4ebL, 0xf4d4b551L, 0x83d385c7L, 0x136c9856L,
295 0x646ba8c0L, 0xfd62f97aL, 0x8a65c9ecL, 0x14015c4fL, 0x63066cd9L,
296 0xfa0f3d63L, 0x8d080df5L, 0x3b6e20c8L, 0x4c69105eL, 0xd56041e4L,
297 0xa2677172L, 0x3c03e4d1L, 0x4b04d447L, 0xd20d85fdL, 0xa50ab56bL,
298 0x35b5a8faL, 0x42b2986cL, 0xdbbbc9d6L, 0xacbcf940L, 0x32d86ce3L,
299 0x45df5c75L, 0xdcd60dcfL, 0xabd13d59L, 0x26d930acL, 0x51de003aL,
300 0xc8d75180L, 0xbfd06116L, 0x21b4f4b5L, 0x56b3c423L, 0xcfba9599L,
301 0xb8bda50fL, 0x2802b89eL, 0x5f058808L, 0xc60cd9b2L, 0xb10be924L,
302 0x2f6f7c87L, 0x58684c11L, 0xc1611dabL, 0xb6662d3dL, 0x76dc4190L,
303 0x01db7106L, 0x98d220bcL, 0xefd5102aL, 0x71b18589L, 0x06b6b51fL,
304 0x9fbfe4a5L, 0xe8b8d433L, 0x7807c9a2L, 0x0f00f934L, 0x9609a88eL,
305 0xe10e9818L, 0x7f6a0dbbL, 0x086d3d2dL, 0x91646c97L, 0xe6635c01L,
306 0x6b6b51f4L, 0x1c6c6162L, 0x856530d8L, 0xf262004eL, 0x6c0695edL,
307 0x1b01a57bL, 0x8208f4c1L, 0xf50fc457L, 0x65b0d9c6L, 0x12b7e950L,
308 0x8bbeb8eaL, 0xfcb9887cL, 0x62dd1ddfL, 0x15da2d49L, 0x8cd37cf3L,
309 0xfbd44c65L, 0x4db26158L, 0x3ab551ceL, 0xa3bc0074L, 0xd4bb30e2L,
310 0x4adfa541L, 0x3dd895d7L, 0xa4d1c46dL, 0xd3d6f4fbL, 0x4369e96aL,
311 0x346ed9fcL, 0xad678846L, 0xda60b8d0L, 0x44042d73L, 0x33031de5L,
312 0xaa0a4c5fL, 0xdd0d7cc9L, 0x5005713cL, 0x270241aaL, 0xbe0b1010L,
313 0xc90c2086L, 0x5768b525L, 0x206f85b3L, 0xb966d409L, 0xce61e49fL,
314 0x5edef90eL, 0x29d9c998L, 0xb0d09822L, 0xc7d7a8b4L, 0x59b33d17L,
315 0x2eb40d81L, 0xb7bd5c3bL, 0xc0ba6cadL, 0xedb88320L, 0x9abfb3b6L,
316 0x03b6e20cL, 0x74b1d29aL, 0xead54739L, 0x9dd277afL, 0x04db2615L,
317 0x73dc1683L, 0xe3630b12L, 0x94643b84L, 0x0d6d6a3eL, 0x7a6a5aa8L,
318 0xe40ecf0bL, 0x9309ff9dL, 0x0a00ae27L, 0x7d079eb1L, 0xf00f9344L,
319 0x8708a3d2L, 0x1e01f268L, 0x6906c2feL, 0xf762575dL, 0x806567cbL,
320 0x196c3671L, 0x6e6b06e7L, 0xfed41b76L, 0x89d32be0L, 0x10da7a5aL,
321 0x67dd4accL, 0xf9b9df6fL, 0x8ebeeff9L, 0x17b7be43L, 0x60b08ed5L,
322 0xd6d6a3e8L, 0xa1d1937eL, 0x38d8c2c4L, 0x4fdff252L, 0xd1bb67f1L,
323 0xa6bc5767L, 0x3fb506ddL, 0x48b2364bL, 0xd80d2bdaL, 0xaf0a1b4cL,
324 0x36034af6L, 0x41047a60L, 0xdf60efc3L, 0xa867df55L, 0x316e8eefL,
325 0x4669be79L, 0xcb61b38cL, 0xbc66831aL, 0x256fd2a0L, 0x5268e236L,
326 0xcc0c7795L, 0xbb0b4703L, 0x220216b9L, 0x5505262fL, 0xc5ba3bbeL,
327 0xb2bd0b28L, 0x2bb45a92L, 0x5cb36a04L, 0xc2d7ffa7L, 0xb5d0cf31L,
328 0x2cd99e8bL, 0x5bdeae1dL, 0x9b64c2b0L, 0xec63f226L, 0x756aa39cL,
329 0x026d930aL, 0x9c0906a9L, 0xeb0e363fL, 0x72076785L, 0x05005713L,
330 0x95bf4a82L, 0xe2b87a14L, 0x7bb12baeL, 0x0cb61b38L, 0x92d28e9bL,
331 0xe5d5be0dL, 0x7cdcefb7L, 0x0bdbdf21L, 0x86d3d2d4L, 0xf1d4e242L,
332 0x68ddb3f8L, 0x1fda836eL, 0x81be16cdL, 0xf6b9265bL, 0x6fb077e1L,
333 0x18b74777L, 0x88085ae6L, 0xff0f6a70L, 0x66063bcaL, 0x11010b5cL,
334 0x8f659effL, 0xf862ae69L, 0x616bffd3L, 0x166ccf45L, 0xa00ae278L,
335 0xd70dd2eeL, 0x4e048354L, 0x3903b3c2L, 0xa7672661L, 0xd06016f7L,
336 0x4969474dL, 0x3e6e77dbL, 0xaed16a4aL, 0xd9d65adcL, 0x40df0b66L,
337 0x37d83bf0L, 0xa9bcae53L, 0xdebb9ec5L, 0x47b2cf7fL, 0x30b5ffe9L,
338 0xbdbdf21cL, 0xcabac28aL, 0x53b39330L, 0x24b4a3a6L, 0xbad03605L,
339 0xcdd70693L, 0x54de5729L, 0x23d967bfL, 0xb3667a2eL, 0xc4614ab8L,
340 0x5d681b02L, 0x2a6f2b94L, 0xb40bbe37L, 0xc30c8ea1L, 0x5a05df1bL,
345 wep_encrypt(struct ieee80211_key *key, struct mbuf *m0, int hdrlen)
347 #define S_SWAP(a,b) do { uint8_t t = S[a]; S[a] = S[b]; S[b] = t; } while(0)
348 struct wep_ctx *ctx = key->wk_private;
349 struct ieee80211vap *vap = ctx->wc_vap;
351 uint8_t rc4key[IEEE80211_WEP_IVLEN + IEEE80211_KEYBUF_SIZE];
352 uint8_t icv[IEEE80211_WEP_CRCLEN];
353 uint32_t i, j, k, crc;
354 size_t buflen, data_len;
359 vap->iv_stats.is_crypto_wep++;
361 /* NB: this assumes the header was pulled up */
362 memcpy(rc4key, mtod(m, uint8_t *) + hdrlen, IEEE80211_WEP_IVLEN);
363 memcpy(rc4key + IEEE80211_WEP_IVLEN, key->wk_key, key->wk_keylen);
365 /* Setup RC4 state */
366 for (i = 0; i < 256; i++)
369 keylen = key->wk_keylen + IEEE80211_WEP_IVLEN;
370 for (i = 0; i < 256; i++) {
371 j = (j + S[i] + rc4key[i % keylen]) & 0xff;
375 off = hdrlen + wep.ic_header;
376 data_len = m->m_pkthdr.len - off;
378 /* Compute CRC32 over unencrypted data and apply RC4 to data */
381 pos = mtod(m, uint8_t *) + off;
382 buflen = m->m_len - off;
384 if (buflen > data_len)
387 for (k = 0; k < buflen; k++) {
388 crc = crc32_table[(crc ^ *pos) & 0xff] ^ (crc >> 8);
390 j = (j + S[i]) & 0xff;
392 *pos++ ^= S[(S[i] + S[j]) & 0xff];
394 if (m->m_next == NULL) {
395 if (data_len != 0) { /* out of data */
396 IEEE80211_NOTE_MAC(vap, IEEE80211_MSG_CRYPTO,
397 ether_sprintf(mtod(m0,
398 struct ieee80211_frame *)->i_addr2),
399 "out of data for WEP (data_len %zu)",
407 pos = mtod(m, uint8_t *);
412 /* Append little-endian CRC32 and encrypt it to produce ICV */
417 for (k = 0; k < IEEE80211_WEP_CRCLEN; k++) {
419 j = (j + S[i]) & 0xff;
421 icv[k] ^= S[(S[i] + S[j]) & 0xff];
423 return m_append(m0, IEEE80211_WEP_CRCLEN, icv);
428 wep_decrypt(struct ieee80211_key *key, struct mbuf *m0, int hdrlen)
430 #define S_SWAP(a,b) do { uint8_t t = S[a]; S[a] = S[b]; S[b] = t; } while(0)
431 struct wep_ctx *ctx = key->wk_private;
432 struct ieee80211vap *vap = ctx->wc_vap;
434 uint8_t rc4key[IEEE80211_WEP_IVLEN + IEEE80211_KEYBUF_SIZE];
435 uint8_t icv[IEEE80211_WEP_CRCLEN];
436 uint32_t i, j, k, crc;
437 size_t buflen, data_len;
442 vap->iv_stats.is_crypto_wep++;
444 /* NB: this assumes the header was pulled up */
445 memcpy(rc4key, mtod(m, uint8_t *) + hdrlen, IEEE80211_WEP_IVLEN);
446 memcpy(rc4key + IEEE80211_WEP_IVLEN, key->wk_key, key->wk_keylen);
448 /* Setup RC4 state */
449 for (i = 0; i < 256; i++)
452 keylen = key->wk_keylen + IEEE80211_WEP_IVLEN;
453 for (i = 0; i < 256; i++) {
454 j = (j + S[i] + rc4key[i % keylen]) & 0xff;
458 off = hdrlen + wep.ic_header;
459 data_len = m->m_pkthdr.len - (off + wep.ic_trailer);
461 /* Compute CRC32 over unencrypted data and apply RC4 to data */
464 pos = mtod(m, uint8_t *) + off;
465 buflen = m->m_len - off;
467 if (buflen > data_len)
470 for (k = 0; k < buflen; k++) {
472 j = (j + S[i]) & 0xff;
474 *pos ^= S[(S[i] + S[j]) & 0xff];
475 crc = crc32_table[(crc ^ *pos) & 0xff] ^ (crc >> 8);
480 if (data_len != 0) { /* out of data */
481 IEEE80211_NOTE_MAC(vap, IEEE80211_MSG_CRYPTO,
482 mtod(m0, struct ieee80211_frame *)->i_addr2,
483 "out of data for WEP (data_len %zu)",
489 pos = mtod(m, uint8_t *);
494 /* Encrypt little-endian CRC32 and verify that it matches with
500 for (k = 0; k < IEEE80211_WEP_CRCLEN; k++) {
502 j = (j + S[i]) & 0xff;
504 /* XXX assumes ICV is contiguous in mbuf */
505 if ((icv[k] ^ S[(S[i] + S[j]) & 0xff]) != *pos++) {
506 /* ICV mismatch - drop frame */
517 IEEE80211_CRYPTO_MODULE(wep, 1);