1/*-
2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
3 *
4 * Copyright (c) 2008 Isilon Inc http://www.isilon.com/
5 * Authors: Doug Rabson <dfr@rabson.org>
6 * Developed with Red Inc: Alfred Perlstein <alfred@freebsd.org>
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 *    notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 *    notice, this list of conditions and the following disclaimer in the
15 *    documentation and/or other materials provided with the distribution.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 */
29
30#include <sys/cdefs.h>
31__FBSDID("$FreeBSD$");
32
33#include <sys/param.h>
34#include <sys/lock.h>
35#include <sys/malloc.h>
36#include <sys/mutex.h>
37#include <sys/kobj.h>
38#include <sys/mbuf.h>
39#include <opencrypto/cryptodev.h>
40
41#include <kgssapi/gssapi.h>
42#include <kgssapi/gssapi_impl.h>
43
44#include "kcrypto.h"
45
46struct aes_state {
47	struct mtx	as_lock;
48	crypto_session_t as_session_aes;
49	crypto_session_t as_session_sha1;
50};
51
52static void
53aes_init(struct krb5_key_state *ks)
54{
55	struct aes_state *as;
56
57	as = malloc(sizeof(struct aes_state), M_GSSAPI, M_WAITOK|M_ZERO);
58	mtx_init(&as->as_lock, "gss aes lock", NULL, MTX_DEF);
59	ks->ks_priv = as;
60}
61
62static void
63aes_destroy(struct krb5_key_state *ks)
64{
65	struct aes_state *as = ks->ks_priv;
66
67	if (as->as_session_aes != 0)
68		crypto_freesession(as->as_session_aes);
69	if (as->as_session_sha1 != 0)
70		crypto_freesession(as->as_session_sha1);
71	mtx_destroy(&as->as_lock);
72	free(ks->ks_priv, M_GSSAPI);
73}
74
75static void
76aes_set_key(struct krb5_key_state *ks, const void *in)
77{
78	void *kp = ks->ks_key;
79	struct aes_state *as = ks->ks_priv;
80	struct crypto_session_params csp;
81
82	if (kp != in)
83		bcopy(in, kp, ks->ks_class->ec_keylen);
84
85	if (as->as_session_aes != 0)
86		crypto_freesession(as->as_session_aes);
87	if (as->as_session_sha1 != 0)
88		crypto_freesession(as->as_session_sha1);
89
90	/*
91	 * We only want the first 96 bits of the HMAC.
92	 */
93	memset(&csp, 0, sizeof(csp));
94	csp.csp_mode = CSP_MODE_DIGEST;
95	csp.csp_auth_alg = CRYPTO_SHA1_HMAC;
96	csp.csp_auth_klen = ks->ks_class->ec_keybits / 8;
97	csp.csp_auth_mlen = 12;
98	csp.csp_auth_key = ks->ks_key;
99	crypto_newsession(&as->as_session_sha1, &csp,
100	    CRYPTOCAP_F_HARDWARE | CRYPTOCAP_F_SOFTWARE);
101
102	memset(&csp, 0, sizeof(csp));
103	csp.csp_mode = CSP_MODE_CIPHER;
104	csp.csp_cipher_alg = CRYPTO_AES_CBC;
105	csp.csp_cipher_klen = ks->ks_class->ec_keybits / 8;
106	csp.csp_cipher_key = ks->ks_key;
107	csp.csp_ivlen = 16;
108	crypto_newsession(&as->as_session_aes, &csp,
109	    CRYPTOCAP_F_HARDWARE | CRYPTOCAP_F_SOFTWARE);
110}
111
112static void
113aes_random_to_key(struct krb5_key_state *ks, const void *in)
114{
115
116	aes_set_key(ks, in);
117}
118
119static int
120aes_crypto_cb(struct cryptop *crp)
121{
122	int error;
123	struct aes_state *as = (struct aes_state *) crp->crp_opaque;
124
125	if (crypto_ses2caps(crp->crp_session) & CRYPTOCAP_F_SYNC)
126		return (0);
127
128	error = crp->crp_etype;
129	if (error == EAGAIN)
130		error = crypto_dispatch(crp);
131	mtx_lock(&as->as_lock);
132	if (error || (crp->crp_flags & CRYPTO_F_DONE))
133		wakeup(crp);
134	mtx_unlock(&as->as_lock);
135
136	return (0);
137}
138
139static void
140aes_encrypt_1(const struct krb5_key_state *ks, int buftype, void *buf,
141    size_t skip, size_t len, void *ivec, bool encrypt)
142{
143	struct aes_state *as = ks->ks_priv;
144	struct cryptop *crp;
145	int error;
146
147	crp = crypto_getreq(as->as_session_aes, M_WAITOK);
148
149	crp->crp_payload_start = skip;
150	crp->crp_payload_length = len;
151	crp->crp_op = encrypt ? CRYPTO_OP_ENCRYPT : CRYPTO_OP_DECRYPT;
152	crp->crp_flags = CRYPTO_F_CBIFSYNC | CRYPTO_F_IV_SEPARATE;
153	if (ivec) {
154		memcpy(crp->crp_iv, ivec, 16);
155	} else {
156		memset(crp->crp_iv, 0, 16);
157	}
158
159	if (buftype == CRYPTO_BUF_MBUF)
160		crypto_use_mbuf(crp, buf);
161	else
162		crypto_use_buf(crp, buf, skip + len);
163	crp->crp_opaque = as;
164	crp->crp_callback = aes_crypto_cb;
165
166	error = crypto_dispatch(crp);
167
168	if ((crypto_ses2caps(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_BUF_MBUF, inout, skip, len, ivec,
206		    true);
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_BUF_MBUF, inout, skip, len, ivec,
214		    true);
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_BUF_MBUF, inout, skip, len - plen,
229		    ivec, true);
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, CRYPTO_BUF_CONTIG, last2.cn, 0, blocklen,
243		    last2.cn_1, true);
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_BUF_MBUF, inout, skip, len, ivec,
276		    false);
277	} else if (plen == 0) {
278		/*
279		 * This is equivalent to CBC mode followed by swapping
280		 * the last two blocks.
281		 */
282		off = skip + len - 2 * blocklen;
283		m_copydata(inout, off, 2 * blocklen, (void*) &last2);
284		m_copyback(inout, off, blocklen, last2.cn);
285		m_copyback(inout, off + blocklen, blocklen, last2.cn_1);
286		aes_encrypt_1(ks, CRYPTO_BUF_MBUF, inout, skip, len, ivec,
287		    false);
288	} else {
289		/*
290		 * This is the difficult case. We first decrypt the
291		 * second to last block with a zero IV to make X. The
292		 * plaintext for the last block is the XOR of X and
293		 * the last cyphertext block.
294		 *
295		 * We derive a new cypher text for the second to last
296		 * block by mixing the unused bytes of X with the last
297		 * cyphertext block. The result of that can be
298		 * decrypted with the rest in CBC mode.
299		 */
300		off = skip + len - plen - blocklen;
301		aes_encrypt_1(ks, CRYPTO_BUF_MBUF, inout, off, blocklen,
302		    NULL, false);
303		m_copydata(inout, off, blocklen + plen, (void*) &last2);
304
305		for (i = 0; i < plen; i++) {
306			t = last2.cn[i];
307			last2.cn[i] ^= last2.cn_1[i];
308			last2.cn_1[i] = t;
309		}
310
311		m_copyback(inout, off, blocklen + plen, (void*) &last2);
312		aes_encrypt_1(ks, CRYPTO_BUF_MBUF, inout, skip, len - plen,
313		    ivec, false);
314	}
315
316}
317
318static void
319aes_checksum(const struct krb5_key_state *ks, int usage,
320    struct mbuf *inout, size_t skip, size_t inlen, size_t outlen)
321{
322	struct aes_state *as = ks->ks_priv;
323	struct cryptop *crp;
324	int error;
325
326	crp = crypto_getreq(as->as_session_sha1, M_WAITOK);
327
328	crp->crp_payload_start = skip;
329	crp->crp_payload_length = inlen;
330	crp->crp_digest_start = skip + inlen;
331	crp->crp_flags = CRYPTO_F_CBIFSYNC;
332	crypto_use_mbuf(crp, inout);
333	crp->crp_opaque = as;
334	crp->crp_callback = aes_crypto_cb;
335
336	error = crypto_dispatch(crp);
337
338	if ((crypto_ses2caps(as->as_session_sha1) & CRYPTOCAP_F_SYNC) == 0) {
339		mtx_lock(&as->as_lock);
340		if (!error && !(crp->crp_flags & CRYPTO_F_DONE))
341			error = msleep(crp, &as->as_lock, 0, "gssaes", 0);
342		mtx_unlock(&as->as_lock);
343	}
344
345	crypto_freereq(crp);
346}
347
348struct krb5_encryption_class krb5_aes128_encryption_class = {
349	"aes128-cts-hmac-sha1-96", /* name */
350	ETYPE_AES128_CTS_HMAC_SHA1_96, /* etype */
351	EC_DERIVED_KEYS,	/* flags */
352	16,			/* blocklen */
353	1,			/* msgblocklen */
354	12,			/* checksumlen */
355	128,			/* keybits */
356	16,			/* keylen */
357	aes_init,
358	aes_destroy,
359	aes_set_key,
360	aes_random_to_key,
361	aes_encrypt,
362	aes_decrypt,
363	aes_checksum
364};
365
366struct krb5_encryption_class krb5_aes256_encryption_class = {
367	"aes256-cts-hmac-sha1-96", /* name */
368	ETYPE_AES256_CTS_HMAC_SHA1_96, /* etype */
369	EC_DERIVED_KEYS,	/* flags */
370	16,			/* blocklen */
371	1,			/* msgblocklen */
372	12,			/* checksumlen */
373	256,			/* keybits */
374	32,			/* keylen */
375	aes_init,
376	aes_destroy,
377	aes_set_key,
378	aes_random_to_key,
379	aes_encrypt,
380	aes_decrypt,
381	aes_checksum
382};
383