xref: /netbsd-src/sys/net80211/ieee80211_crypto_ccmp.c (revision 676286b5eaac22a400505fcd7c7f2a7411e65ec6)
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