1 /* $NetBSD: ieee80211_crypto_ccmp.c,v 1.20 2023/06/24 05:12:03 msaitoh Exp $ */
2
3 /*
4 * Copyright (c) 2002-2005 Sam Leffler, Errno Consulting
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
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.
15 * 3. The name of the author may not be used to endorse or promote products
16 * derived from this software without specific prior written permission.
17 *
18 * Alternatively, this software may be distributed under the terms of the
19 * GNU General Public License ("GPL") version 2 as published by the Free
20 * Software Foundation.
21 *
22 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
23 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
24 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
25 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
26 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
27 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
28 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
29 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
30 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
31 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
32 */
33
34 #include <sys/cdefs.h>
35 #ifdef __FreeBSD__
36 __FBSDID("$FreeBSD: src/sys/net80211/ieee80211_crypto_ccmp.c,v 1.7 2005/07/11 03:06:23 sam Exp $");
37 #endif
38 #ifdef __NetBSD__
39 __KERNEL_RCSID(0, "$NetBSD: ieee80211_crypto_ccmp.c,v 1.20 2023/06/24 05:12:03 msaitoh Exp $");
40 #endif
41
42 /*
43 * IEEE 802.11i AES-CCMP crypto support.
44 *
45 * Part of this module is derived from similar code in the Host
46 * AP driver. The code is used with the consent of the author and
47 * its license is included below.
48 */
49 #include <sys/param.h>
50 #include <sys/kernel.h>
51 #include <sys/kmem.h>
52 #include <sys/mbuf.h>
53 #include <sys/systm.h>
54
55 #include <sys/socket.h>
56
57 #include <net/if.h>
58 #include <net/if_ether.h>
59 #include <net/if_media.h>
60
61 #include <net80211/ieee80211_var.h>
62
63 #include <crypto/aes/aes.h>
64 #include <crypto/aes/aes_ccm.h>
65 #include <crypto/aes/aes_ccm_mbuf.h>
66
67 #define AES_BLOCK_LEN 16
68
69 struct ccmp_ctx {
70 struct aesenc cc_aes;
71 struct ieee80211com *cc_ic; /* for diagnostics */
72 };
73
74 static void *ccmp_attach(struct ieee80211com *, struct ieee80211_key *);
75 static void ccmp_detach(struct ieee80211_key *);
76 static int ccmp_setkey(struct ieee80211_key *);
77 static int ccmp_encap(struct ieee80211_key *k, struct mbuf *, u_int8_t keyid);
78 static int ccmp_decap(struct ieee80211_key *, struct mbuf *, int);
79 static int ccmp_enmic(struct ieee80211_key *, struct mbuf *, int);
80 static int ccmp_demic(struct ieee80211_key *, struct mbuf *, int);
81
82 const struct ieee80211_cipher ieee80211_cipher_ccmp = {
83 .ic_name = "AES-CCM",
84 .ic_cipher = IEEE80211_CIPHER_AES_CCM,
85 .ic_header = IEEE80211_WEP_IVLEN + IEEE80211_WEP_KIDLEN +
86 IEEE80211_WEP_EXTIVLEN,
87 .ic_trailer = IEEE80211_WEP_MICLEN,
88 .ic_miclen = 0,
89 .ic_attach = ccmp_attach,
90 .ic_detach = ccmp_detach,
91 .ic_setkey = ccmp_setkey,
92 .ic_encap = ccmp_encap,
93 .ic_decap = ccmp_decap,
94 .ic_enmic = ccmp_enmic,
95 .ic_demic = ccmp_demic,
96 };
97
98 #define ccmp ieee80211_cipher_ccmp
99
100 static int ccmp_encrypt(struct ieee80211_key *, struct mbuf *, int hdrlen);
101 static int ccmp_decrypt(struct ieee80211_key *, u_int64_t pn,
102 struct mbuf *, int hdrlen);
103
104 static void *
ccmp_attach(struct ieee80211com * ic,struct ieee80211_key * k)105 ccmp_attach(struct ieee80211com *ic, struct ieee80211_key *k)
106 {
107 struct ccmp_ctx *ctx;
108
109 ctx = kmem_intr_zalloc(sizeof(*ctx), KM_NOSLEEP);
110 if (ctx == NULL) {
111 ic->ic_stats.is_crypto_nomem++;
112 return NULL;
113 }
114 ctx->cc_ic = ic;
115 return ctx;
116 }
117
118 static void
ccmp_detach(struct ieee80211_key * k)119 ccmp_detach(struct ieee80211_key *k)
120 {
121 struct ccmp_ctx *ctx = k->wk_private;
122
123 kmem_intr_free(ctx, sizeof(*ctx));
124 }
125
126 static int
ccmp_setkey(struct ieee80211_key * k)127 ccmp_setkey(struct ieee80211_key *k)
128 {
129 struct ccmp_ctx *ctx = k->wk_private;
130
131 if (k->wk_keylen != (128/NBBY)) {
132 IEEE80211_DPRINTF(ctx->cc_ic, IEEE80211_MSG_CRYPTO,
133 "%s: Invalid key length %u, expecting %u\n",
134 __func__, k->wk_keylen, 128/NBBY);
135 return 0;
136 }
137 if (k->wk_flags & IEEE80211_KEY_SWCRYPT)
138 aes_setenckey128(&ctx->cc_aes, k->wk_key);
139 return 1;
140 }
141
142 /*
143 * Add privacy headers appropriate for the specified key.
144 */
145 static int
ccmp_encap(struct ieee80211_key * k,struct mbuf * m,u_int8_t keyid)146 ccmp_encap(struct ieee80211_key *k, struct mbuf *m, u_int8_t keyid)
147 {
148 struct ccmp_ctx *ctx = k->wk_private;
149 struct ieee80211com *ic = ctx->cc_ic;
150 u_int8_t *ivp;
151 int hdrlen;
152
153 hdrlen = ieee80211_hdrspace(ic, mtod(m, void *));
154 ivp = mtod(m, u_int8_t *) + hdrlen;
155
156 k->wk_keytsc++; /* XXX wrap at 48 bits */
157 ivp[0] = k->wk_keytsc >> 0; /* PN0 */
158 ivp[1] = k->wk_keytsc >> 8; /* PN1 */
159 ivp[2] = 0; /* Reserved */
160 ivp[3] = keyid | IEEE80211_WEP_EXTIV; /* KeyID | ExtID */
161 ivp[4] = k->wk_keytsc >> 16; /* PN2 */
162 ivp[5] = k->wk_keytsc >> 24; /* PN3 */
163 ivp[6] = k->wk_keytsc >> 32; /* PN4 */
164 ivp[7] = k->wk_keytsc >> 40; /* PN5 */
165
166 /*
167 * Finally, do software encrypt if need.
168 */
169 if ((k->wk_flags & IEEE80211_KEY_SWCRYPT) &&
170 !ccmp_encrypt(k, m, hdrlen))
171 return 0;
172
173 return 1;
174 }
175
176 /*
177 * Add MIC to the frame as needed.
178 */
179 static int
ccmp_enmic(struct ieee80211_key * k,struct mbuf * m,int force)180 ccmp_enmic(struct ieee80211_key *k, struct mbuf *m,
181 int force)
182 {
183
184 return 1;
185 }
186
187 static __inline uint64_t
READ_6(uint8_t b0,uint8_t b1,uint8_t b2,uint8_t b3,uint8_t b4,uint8_t b5)188 READ_6(uint8_t b0, uint8_t b1, uint8_t b2, uint8_t b3, uint8_t b4, uint8_t b5)
189 {
190 uint32_t iv32 = (b0 << 0) | (b1 << 8) | (b2 << 16) | (b3 << 24);
191 uint16_t iv16 = (b4 << 0) | (b5 << 8);
192 return (((uint64_t)iv16) << 32) | iv32;
193 }
194
195 /*
196 * Validate and strip privacy headers (and trailer) for a
197 * received frame. The specified key should be correct but
198 * is also verified.
199 */
200 static int
ccmp_decap(struct ieee80211_key * k,struct mbuf * m,int hdrlen)201 ccmp_decap(struct ieee80211_key *k, struct mbuf *m, int hdrlen)
202 {
203 struct ccmp_ctx *ctx = k->wk_private;
204 struct ieee80211_frame *wh;
205 uint8_t *ivp;
206 uint64_t pn;
207
208 /*
209 * Header should have extended IV and sequence number;
210 * verify the former and validate the latter.
211 */
212 wh = mtod(m, struct ieee80211_frame *);
213 ivp = mtod(m, uint8_t *) + hdrlen;
214 if ((ivp[IEEE80211_WEP_IVLEN] & IEEE80211_WEP_EXTIV) == 0) {
215 /*
216 * No extended IV; discard frame.
217 */
218 IEEE80211_DPRINTF(ctx->cc_ic, IEEE80211_MSG_CRYPTO,
219 "[%s] Missing ExtIV for AES-CCM cipher\n",
220 ether_sprintf(wh->i_addr2));
221 ctx->cc_ic->ic_stats.is_rx_ccmpformat++;
222 return 0;
223 }
224 pn = READ_6(ivp[0], ivp[1], ivp[4], ivp[5], ivp[6], ivp[7]);
225 if (pn <= k->wk_keyrsc) {
226 /*
227 * Replay violation.
228 */
229 ieee80211_notify_replay_failure(ctx->cc_ic, wh, k, pn);
230 ctx->cc_ic->ic_stats.is_rx_ccmpreplay++;
231 return 0;
232 }
233
234 /*
235 * Check if the device handled the decrypt in hardware.
236 * If so we just strip the header; otherwise we need to
237 * handle the decrypt in software. Note that for the
238 * latter we leave the header in place for use in the
239 * decryption work.
240 */
241 if ((k->wk_flags & IEEE80211_KEY_SWCRYPT) &&
242 !ccmp_decrypt(k, pn, m, hdrlen))
243 return 0;
244
245 /*
246 * Copy up 802.11 header and strip crypto bits.
247 */
248 memmove(mtod(m, u_int8_t *) + ccmp.ic_header, mtod(m, void *), hdrlen);
249 m_adj(m, ccmp.ic_header);
250 m_adj(m, -ccmp.ic_trailer);
251
252 /*
253 * Ok to update rsc now.
254 */
255 k->wk_keyrsc = pn;
256
257 return 1;
258 }
259
260 /*
261 * Verify and strip MIC from the frame.
262 */
263 static int
ccmp_demic(struct ieee80211_key * k,struct mbuf * m,int force)264 ccmp_demic(struct ieee80211_key *k, struct mbuf *m, int force)
265 {
266 return 1;
267 }
268
269 /*
270 * Host AP crypt: host-based CCMP encryption implementation for Host AP driver
271 *
272 * Copyright (c) 2003-2004, Jouni Malinen <jkmaline@cc.hut.fi>
273 *
274 * This program is free software; you can redistribute it and/or modify
275 * it under the terms of the GNU General Public License version 2 as
276 * published by the Free Software Foundation. See README and COPYING for
277 * more details.
278 *
279 * Alternatively, this software may be distributed under the terms of BSD
280 * license.
281 */
282
283 static void
ccmp_init_blocks(struct aesenc * ctx,struct ieee80211_frame * wh,u_int64_t pn,size_t data_len,struct aes_ccm * aes_ccm)284 ccmp_init_blocks(struct aesenc *ctx, struct ieee80211_frame *wh,
285 u_int64_t pn, size_t data_len, struct aes_ccm *aes_ccm)
286 {
287 uint8_t nonce[13];
288 uint8_t ad[32];
289 uint8_t qos;
290 size_t adlen;
291
292 #define IS_4ADDRESS(wh) \
293 ((wh->i_fc[1] & IEEE80211_FC1_DIR_MASK) == IEEE80211_FC1_DIR_DSTODS)
294 #define IS_QOS_DATA(wh) ieee80211_has_qos(wh)
295
296 /* nonce[0] is qos, determined later */
297 IEEE80211_ADDR_COPY(nonce + 1, wh->i_addr2);
298 nonce[7] = pn >> 40;
299 nonce[8] = pn >> 32;
300 nonce[9] = pn >> 24;
301 nonce[10] = pn >> 16;
302 nonce[11] = pn >> 8;
303 nonce[12] = pn >> 0;
304
305 ad[0] = wh->i_fc[0] & 0x8f; /* XXX magic #s */
306 ad[1] = wh->i_fc[1] & 0xc7; /* XXX magic #s */
307 /* NB: we know 3 addresses are contiguous */
308 memcpy(ad + 2, wh->i_addr1, 3 * IEEE80211_ADDR_LEN);
309 ad[20] = wh->i_seq[0] & IEEE80211_SEQ_FRAG_MASK;
310 ad[21] = 0; /* all bits masked */
311
312 /*
313 * Construct variable-length portion of AAD based
314 * on whether this is a 4-address frame/QOS frame.
315 *
316 * We also fill in the priority bits of the CCM
317 * initial block as we know whether or not we have
318 * a QOS frame.
319 */
320 if (IS_4ADDRESS(wh)) {
321 IEEE80211_ADDR_COPY(ad + 22,
322 ((const struct ieee80211_frame_addr4 *)wh)->i_addr4);
323 if (IS_QOS_DATA(wh)) {
324 const struct ieee80211_qosframe_addr4 *qwh4 =
325 (const struct ieee80211_qosframe_addr4 *)wh;
326 qos = qwh4->i_qos[0] & 0x0f; /* just priority bits */
327 ad[28] = qos;
328 ad[29] = 0;
329 adlen = 22 + IEEE80211_ADDR_LEN + 2;
330 } else {
331 qos = 0;
332 adlen = 22 + IEEE80211_ADDR_LEN;
333 }
334 } else {
335 if (IS_QOS_DATA(wh)) {
336 const struct ieee80211_qosframe *qwh =
337 (const struct ieee80211_qosframe *)wh;
338 qos = qwh->i_qos[0] & 0x0f; /* just priority bits */
339 ad[22] = qos;
340 ad[23] = 0;
341 adlen = 22 + 2;
342 } else {
343 qos = 0;
344 adlen = 22;
345 }
346 }
347 nonce[0] = qos;
348
349 aes_ccm_init(aes_ccm, AES_128_NROUNDS, ctx, 2 /* L, counter octets */,
350 IEEE80211_WEP_MICLEN, nonce, sizeof nonce, ad, adlen, data_len);
351
352 #undef IS_QOS_DATA
353 #undef IS_4ADDRESS
354 }
355
356 static int
ccmp_encrypt(struct ieee80211_key * key,struct mbuf * m,int hdrlen)357 ccmp_encrypt(struct ieee80211_key *key, struct mbuf *m, int hdrlen)
358 {
359 struct ccmp_ctx *ctx = key->wk_private;
360 struct ieee80211_frame *wh;
361 struct aes_ccm aes_ccm;
362 size_t data_len;
363 uint8_t mic[IEEE80211_WEP_MICLEN];
364
365 KASSERT(hdrlen >= 0);
366 KASSERT(hdrlen < m->m_pkthdr.len);
367 KASSERT(ccmp.ic_header <= m->m_pkthdr.len - hdrlen);
368
369 ctx->cc_ic->ic_stats.is_crypto_ccmp++;
370
371 wh = mtod(m, struct ieee80211_frame *);
372 data_len = m->m_pkthdr.len - (hdrlen + ccmp.ic_header);
373 ccmp_init_blocks(&ctx->cc_aes, wh, key->wk_keytsc, data_len, &aes_ccm);
374 aes_ccm_enc_mbuf(&aes_ccm, m, hdrlen + ccmp.ic_header, data_len, mic);
375
376 return m_append(m, ccmp.ic_trailer, mic);
377 }
378
379 static int
ccmp_decrypt(struct ieee80211_key * key,u_int64_t pn,struct mbuf * m,int hdrlen)380 ccmp_decrypt(struct ieee80211_key *key, u_int64_t pn, struct mbuf *m,
381 int hdrlen)
382 {
383 struct ccmp_ctx *ctx = key->wk_private;
384 struct ieee80211_frame *wh;
385 struct aes_ccm aes_ccm;
386 size_t data_len;
387 uint8_t mic[IEEE80211_WEP_MICLEN];
388
389 KASSERT(hdrlen >= 0);
390 KASSERT(hdrlen < m->m_pkthdr.len);
391 KASSERT(ccmp.ic_header < m->m_pkthdr.len - hdrlen);
392 KASSERT(ccmp.ic_trailer < m->m_pkthdr.len - (hdrlen + ccmp.ic_header));
393
394 ctx->cc_ic->ic_stats.is_crypto_ccmp++;
395
396 wh = mtod(m, struct ieee80211_frame *);
397 data_len = m->m_pkthdr.len - (hdrlen + ccmp.ic_header + ccmp.ic_trailer);
398 ccmp_init_blocks(&ctx->cc_aes, wh, pn, data_len, &aes_ccm);
399 m_copydata(m, m->m_pkthdr.len - ccmp.ic_trailer, ccmp.ic_trailer, mic);
400
401 if (!aes_ccm_dec_mbuf(&aes_ccm, m, hdrlen + ccmp.ic_header, data_len,
402 mic)) {
403 IEEE80211_DPRINTF(ctx->cc_ic, IEEE80211_MSG_CRYPTO,
404 "[%s] AES-CCM decrypt failed; MIC mismatch\n",
405 ether_sprintf(wh->i_addr2));
406 ctx->cc_ic->ic_stats.is_rx_ccmpmic++;
407 return 0;
408 }
409
410 return 1;
411 }
412
IEEE80211_CRYPTO_SETUP(ccmp_register)413 IEEE80211_CRYPTO_SETUP(ccmp_register)
414 {
415 ieee80211_crypto_register(&ccmp);
416 }
417