1/*-
2 * Copyright (c) 2008 Isilon Inc http://www.isilon.com/
3 * Authors: Doug Rabson <dfr@rabson.org>
4 * Developed with Red Inc: Alfred Perlstein <alfred@freebsd.org>
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 *    notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 *    notice, this list of conditions and the following disclaimer in the
13 *    documentation and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
16 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
18 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
25 * SUCH DAMAGE.
26 */
27
28#include <sys/cdefs.h>
29__FBSDID("$FreeBSD$");
30
31#include <sys/param.h>
32#include <sys/lock.h>
33#include <sys/malloc.h>
34#include <sys/mutex.h>
35#include <sys/kobj.h>
36#include <sys/mbuf.h>
37#include <opencrypto/cryptodev.h>
38
39#include <kgssapi/gssapi.h>
40#include <kgssapi/gssapi_impl.h>
41
42#include "kcrypto.h"
43
44struct aes_state {
45	struct mtx	as_lock;
46	uint64_t	as_session_aes;
47	uint64_t	as_session_sha1;
48};
49
50static void
51aes_init(struct krb5_key_state *ks)
52{
53	struct aes_state *as;
54
55	as = malloc(sizeof(struct aes_state), M_GSSAPI, M_WAITOK|M_ZERO);
56	mtx_init(&as->as_lock, "gss aes lock", NULL, MTX_DEF);
57	ks->ks_priv = as;
58}
59
60static void
61aes_destroy(struct krb5_key_state *ks)
62{
63	struct aes_state *as = ks->ks_priv;
64
65	if (as->as_session_aes != 0)
66		crypto_freesession(as->as_session_aes);
67	if (as->as_session_sha1 != 0)
68		crypto_freesession(as->as_session_sha1);
69	mtx_destroy(&as->as_lock);
70	free(ks->ks_priv, M_GSSAPI);
71}
72
73static void
74aes_set_key(struct krb5_key_state *ks, const void *in)
75{
76	void *kp = ks->ks_key;
77	struct aes_state *as = ks->ks_priv;
78	struct cryptoini cri;
79
80	if (kp != in)
81		bcopy(in, kp, ks->ks_class->ec_keylen);
82
83	if (as->as_session_aes != 0)
84		crypto_freesession(as->as_session_aes);
85	if (as->as_session_sha1 != 0)
86		crypto_freesession(as->as_session_sha1);
87
88	/*
89	 * We only want the first 96 bits of the HMAC.
90	 */
91	bzero(&cri, sizeof(cri));
92	cri.cri_alg = CRYPTO_SHA1_HMAC;
93	cri.cri_klen = ks->ks_class->ec_keybits;
94	cri.cri_mlen = 12;
95	cri.cri_key = ks->ks_key;
96	cri.cri_next = NULL;
97	crypto_newsession(&as->as_session_sha1, &cri,
98	    CRYPTOCAP_F_HARDWARE | CRYPTOCAP_F_SOFTWARE);
99
100	bzero(&cri, sizeof(cri));
101	cri.cri_alg = CRYPTO_AES_CBC;
102	cri.cri_klen = ks->ks_class->ec_keybits;
103	cri.cri_mlen = 0;
104	cri.cri_key = ks->ks_key;
105	cri.cri_next = NULL;
106	crypto_newsession(&as->as_session_aes, &cri,
107	    CRYPTOCAP_F_HARDWARE | CRYPTOCAP_F_SOFTWARE);
108}
109
110static void
111aes_random_to_key(struct krb5_key_state *ks, const void *in)
112{
113
114	aes_set_key(ks, in);
115}
116
117static int
118aes_crypto_cb(struct cryptop *crp)
119{
120	int error;
121	struct aes_state *as = (struct aes_state *) crp->crp_opaque;
122
123	if (CRYPTO_SESID2CAPS(crp->crp_sid) & CRYPTOCAP_F_SYNC)
124		return (0);
125
126	error = crp->crp_etype;
127	if (error == EAGAIN)
128		error = crypto_dispatch(crp);
129	mtx_lock(&as->as_lock);
130	if (error || (crp->crp_flags & CRYPTO_F_DONE))
131		wakeup(crp);
132	mtx_unlock(&as->as_lock);
133
134	return (0);
135}
136
137static void
138aes_encrypt_1(const struct krb5_key_state *ks, int buftype, void *buf,
139    size_t skip, size_t len, void *ivec, int encdec)
140{
141	struct aes_state *as = ks->ks_priv;
142	struct cryptop *crp;
143	struct cryptodesc *crd;
144	int error;
145
146	crp = crypto_getreq(1);
147	crd = crp->crp_desc;
148
149	crd->crd_skip = skip;
150	crd->crd_len = len;
151	crd->crd_flags = CRD_F_IV_EXPLICIT | CRD_F_IV_PRESENT | encdec;
152	if (ivec) {
153		bcopy(ivec, crd->crd_iv, 16);
154	} else {
155		bzero(crd->crd_iv, 16);
156	}
157	crd->crd_next = NULL;
158	crd->crd_alg = CRYPTO_AES_CBC;
159
160	crp->crp_sid = as->as_session_aes;
161	crp->crp_flags = buftype | CRYPTO_F_CBIFSYNC;
162	crp->crp_buf = buf;
163	crp->crp_opaque = (void *) as;
164	crp->crp_callback = aes_crypto_cb;
165
166	error = crypto_dispatch(crp);
167
168	if ((CRYPTO_SESID2CAPS(as->as_session_aes) & CRYPTOCAP_F_SYNC) == 0) {
169		mtx_lock(&as->as_lock);
170		if (!error && !(crp->crp_flags & CRYPTO_F_DONE))
171			error = msleep(crp, &as->as_lock, 0, "gssaes", 0);
172		mtx_unlock(&as->as_lock);
173	}
174
175	crypto_freereq(crp);
176}
177
178static void
179aes_encrypt(const struct krb5_key_state *ks, struct mbuf *inout,
180    size_t skip, size_t len, void *ivec, size_t ivlen)
181{
182	size_t blocklen = 16, plen;
183	struct {
184		uint8_t cn_1[16], cn[16];
185	} last2;
186	int i, off;
187
188	/*
189	 * AES encryption with cyphertext stealing:
190	 *
191	 * CTSencrypt(P[0], ..., P[n], IV, K):
192	 *	len = length(P[n])
193	 *	(C[0], ..., C[n-2], E[n-1]) =
194	 *		CBCencrypt(P[0], ..., P[n-1], IV, K)
195	 *	P = pad(P[n], 0, blocksize)
196	 *	E[n] = CBCencrypt(P, E[n-1], K);
197	 *	C[n-1] = E[n]
198	 *	C[n] = E[n-1]{0..len-1}
199	 */
200	plen = len % blocklen;
201	if (len == blocklen) {
202		/*
203		 * Note: caller will ensure len >= blocklen.
204		 */
205		aes_encrypt_1(ks, CRYPTO_F_IMBUF, inout, skip, len, ivec,
206		    CRD_F_ENCRYPT);
207	} else if (plen == 0) {
208		/*
209		 * This is equivalent to CBC mode followed by swapping
210		 * the last two blocks. We assume that neither of the
211		 * last two blocks cross iov boundaries.
212		 */
213		aes_encrypt_1(ks, CRYPTO_F_IMBUF, inout, skip, len, ivec,
214		    CRD_F_ENCRYPT);
215		off = skip + len - 2 * blocklen;
216		m_copydata(inout, off, 2 * blocklen, (void*) &last2);
217		m_copyback(inout, off, blocklen, last2.cn);
218		m_copyback(inout, off + blocklen, blocklen, last2.cn_1);
219	} else {
220		/*
221		 * This is the difficult case. We encrypt all but the
222		 * last partial block first. We then create a padded
223		 * copy of the last block and encrypt that using the
224		 * second to last encrypted block as IV. Once we have
225		 * the encrypted versions of the last two blocks, we
226		 * reshuffle to create the final result.
227		 */
228		aes_encrypt_1(ks, CRYPTO_F_IMBUF, inout, skip, len - plen,
229		    ivec, CRD_F_ENCRYPT);
230
231		/*
232		 * Copy out the last two blocks, pad the last block
233		 * and encrypt it. Rearrange to get the final
234		 * result. The cyphertext for cn_1 is in cn. The
235		 * cyphertext for cn is the first plen bytes of what
236		 * is in cn_1 now.
237		 */
238		off = skip + len - blocklen - plen;
239		m_copydata(inout, off, blocklen + plen, (void*) &last2);
240		for (i = plen; i < blocklen; i++)
241			last2.cn[i] = 0;
242		aes_encrypt_1(ks, 0, last2.cn, 0, blocklen, last2.cn_1,
243		    CRD_F_ENCRYPT);
244		m_copyback(inout, off, blocklen, last2.cn);
245		m_copyback(inout, off + blocklen, plen, last2.cn_1);
246	}
247}
248
249static void
250aes_decrypt(const struct krb5_key_state *ks, struct mbuf *inout,
251    size_t skip, size_t len, void *ivec, size_t ivlen)
252{
253	size_t blocklen = 16, plen;
254	struct {
255		uint8_t cn_1[16], cn[16];
256	} last2;
257	int i, off, t;
258
259	/*
260	 * AES decryption with cyphertext stealing:
261	 *
262	 * CTSencrypt(C[0], ..., C[n], IV, K):
263	 *	len = length(C[n])
264	 *	E[n] = C[n-1]
265	 *	X = decrypt(E[n], K)
266	 *	P[n] = (X ^ C[n]){0..len-1}
267	 *	E[n-1] = {C[n,0],...,C[n,len-1],X[len],...,X[blocksize-1]}
268	 *	(P[0],...,P[n-1]) = CBCdecrypt(C[0],...,C[n-2],E[n-1], IV, K)
269	 */
270	plen = len % blocklen;
271	if (len == blocklen) {
272		/*
273		 * Note: caller will ensure len >= blocklen.
274		 */
275		aes_encrypt_1(ks, CRYPTO_F_IMBUF, inout, skip, len, ivec, 0);
276	} else if (plen == 0) {
277		/*
278		 * This is equivalent to CBC mode followed by swapping
279		 * the last two blocks.
280		 */
281		off = skip + len - 2 * blocklen;
282		m_copydata(inout, off, 2 * blocklen, (void*) &last2);
283		m_copyback(inout, off, blocklen, last2.cn);
284		m_copyback(inout, off + blocklen, blocklen, last2.cn_1);
285		aes_encrypt_1(ks, CRYPTO_F_IMBUF, inout, skip, len, ivec, 0);
286	} else {
287		/*
288		 * This is the difficult case. We first decrypt the
289		 * second to last block with a zero IV to make X. The
290		 * plaintext for the last block is the XOR of X and
291		 * the last cyphertext block.
292		 *
293		 * We derive a new cypher text for the second to last
294		 * block by mixing the unused bytes of X with the last
295		 * cyphertext block. The result of that can be
296		 * decrypted with the rest in CBC mode.
297		 */
298		off = skip + len - plen - blocklen;
299		aes_encrypt_1(ks, CRYPTO_F_IMBUF, inout, off, blocklen,
300		    NULL, 0);
301		m_copydata(inout, off, blocklen + plen, (void*) &last2);
302
303		for (i = 0; i < plen; i++) {
304			t = last2.cn[i];
305			last2.cn[i] ^= last2.cn_1[i];
306			last2.cn_1[i] = t;
307		}
308
309		m_copyback(inout, off, blocklen + plen, (void*) &last2);
310		aes_encrypt_1(ks, CRYPTO_F_IMBUF, inout, skip, len - plen,
311		    ivec, 0);
312	}
313
314}
315
316static void
317aes_checksum(const struct krb5_key_state *ks, int usage,
318    struct mbuf *inout, size_t skip, size_t inlen, size_t outlen)
319{
320	struct aes_state *as = ks->ks_priv;
321	struct cryptop *crp;
322	struct cryptodesc *crd;
323	int error;
324
325	crp = crypto_getreq(1);
326	crd = crp->crp_desc;
327
328	crd->crd_skip = skip;
329	crd->crd_len = inlen;
330	crd->crd_inject = skip + inlen;
331	crd->crd_flags = 0;
332	crd->crd_next = NULL;
333	crd->crd_alg = CRYPTO_SHA1_HMAC;
334
335	crp->crp_sid = as->as_session_sha1;
336	crp->crp_ilen = inlen;
337	crp->crp_olen = 12;
338	crp->crp_etype = 0;
339	crp->crp_flags = CRYPTO_F_IMBUF | CRYPTO_F_CBIFSYNC;
340	crp->crp_buf = (void *) inout;
341	crp->crp_opaque = (void *) as;
342	crp->crp_callback = aes_crypto_cb;
343
344	error = crypto_dispatch(crp);
345
346	if ((CRYPTO_SESID2CAPS(as->as_session_sha1) & CRYPTOCAP_F_SYNC) == 0) {
347		mtx_lock(&as->as_lock);
348		if (!error && !(crp->crp_flags & CRYPTO_F_DONE))
349			error = msleep(crp, &as->as_lock, 0, "gssaes", 0);
350		mtx_unlock(&as->as_lock);
351	}
352
353	crypto_freereq(crp);
354}
355
356struct krb5_encryption_class krb5_aes128_encryption_class = {
357	"aes128-cts-hmac-sha1-96", /* name */
358	ETYPE_AES128_CTS_HMAC_SHA1_96, /* etype */
359	EC_DERIVED_KEYS,	/* flags */
360	16,			/* blocklen */
361	1,			/* msgblocklen */
362	12,			/* checksumlen */
363	128,			/* keybits */
364	16,			/* keylen */
365	aes_init,
366	aes_destroy,
367	aes_set_key,
368	aes_random_to_key,
369	aes_encrypt,
370	aes_decrypt,
371	aes_checksum
372};
373
374struct krb5_encryption_class krb5_aes256_encryption_class = {
375	"aes256-cts-hmac-sha1-96", /* name */
376	ETYPE_AES256_CTS_HMAC_SHA1_96, /* etype */
377	EC_DERIVED_KEYS,	/* flags */
378	16,			/* blocklen */
379	1,			/* msgblocklen */
380	12,			/* checksumlen */
381	256,			/* keybits */
382	32,			/* keylen */
383	aes_init,
384	aes_destroy,
385	aes_set_key,
386	aes_random_to_key,
387	aes_encrypt,
388	aes_decrypt,
389	aes_checksum
390};
391