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
69struct ccmp_ctx {
70	struct aesenc cc_aes;
71	struct ieee80211com *cc_ic;	/* for diagnostics */
72};
73
74static	void *ccmp_attach(struct ieee80211com *, struct ieee80211_key *);
75static	void ccmp_detach(struct ieee80211_key *);
76static	int ccmp_setkey(struct ieee80211_key *);
77static	int ccmp_encap(struct ieee80211_key *k, struct mbuf *, u_int8_t keyid);
78static	int ccmp_decap(struct ieee80211_key *, struct mbuf *, int);
79static	int ccmp_enmic(struct ieee80211_key *, struct mbuf *, int);
80static	int ccmp_demic(struct ieee80211_key *, struct mbuf *, int);
81
82const 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
100static	int ccmp_encrypt(struct ieee80211_key *, struct mbuf *, int hdrlen);
101static	int ccmp_decrypt(struct ieee80211_key *, u_int64_t pn,
102		struct mbuf *, int hdrlen);
103
104static void *
105ccmp_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
118static void
119ccmp_detach(struct ieee80211_key *k)
120{
121	struct ccmp_ctx *ctx = k->wk_private;
122
123	kmem_intr_free(ctx, sizeof(*ctx));
124}
125
126static int
127ccmp_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 */
145static int
146ccmp_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 */
179static int
180ccmp_enmic(struct ieee80211_key *k, struct mbuf *m,
181    int force)
182{
183
184	return 1;
185}
186
187static __inline uint64_t
188READ_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 */
200static int
201ccmp_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 */
263static int
264ccmp_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
283static void
284ccmp_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
356static int
357ccmp_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
379static int
380ccmp_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
413IEEE80211_CRYPTO_SETUP(ccmp_register)
414{
415	ieee80211_crypto_register(&ccmp);
416}
417