uvm_swap_encrypt.c revision 1.19 
1/*	$OpenBSD: uvm_swap_encrypt.c,v 1.19 2014/11/18 02:37:31 tedu Exp $	*/
2
3/*
4 * Copyright 1999 Niels Provos <provos@citi.umich.edu>
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. All advertising materials mentioning features or use of this software
16 *    must display the following acknowledgement:
17 *      This product includes software developed by Niels Provos.
18 * 4. The name of the author may not be used to endorse or promote products
19 *    derived from this software without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
22 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
23 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
24 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
25 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
26 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
27 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
28 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
29 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
30 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
31 */
32
33#include <sys/param.h>
34#include <sys/systm.h>
35#include <sys/kernel.h>
36#include <sys/malloc.h>
37#include <sys/sysctl.h>
38#include <sys/time.h>
39#include <sys/conf.h>
40#include <crypto/rijndael.h>
41
42#include <uvm/uvm.h>
43
44struct swap_key *kcur = NULL;
45rijndael_ctx swap_ctxt;
46
47int uvm_doswapencrypt = 1;
48u_int uvm_swpkeyscreated = 0;
49u_int uvm_swpkeysdeleted = 0;
50
51int swap_encrypt_initialized = 0;
52
53int
54swap_encrypt_ctl(int *name, u_int namelen, void *oldp, size_t *oldlenp,
55    void *newp, size_t newlen, struct proc *p)
56{
57	/* all sysctl names at this level are terminal */
58	if (namelen != 1)
59		return (ENOTDIR);		/* overloaded */
60
61	switch (name[0]) {
62	case SWPENC_ENABLE: {
63		int doencrypt = uvm_doswapencrypt;
64		int result;
65
66		result = sysctl_int(oldp, oldlenp, newp, newlen, &doencrypt);
67		if (result)
68			return result;
69
70		/*
71		 * Swap Encryption has been turned on, we need to
72		 * initialize state for swap devices that have been
73		 * added.
74		 */
75		if (doencrypt)
76			uvm_swap_initcrypt_all();
77		uvm_doswapencrypt = doencrypt;
78		return (0);
79	}
80	case SWPENC_CREATED:
81		return (sysctl_rdint(oldp, oldlenp, newp, uvm_swpkeyscreated));
82	case SWPENC_DELETED:
83		return (sysctl_rdint(oldp, oldlenp, newp, uvm_swpkeysdeleted));
84	default:
85		return (EOPNOTSUPP);
86	}
87	/* NOTREACHED */
88}
89
90void
91swap_key_delete(struct swap_key *key)
92{
93	/* Make sure that this key gets removed if we just used it */
94	swap_key_cleanup(key);
95
96	explicit_bzero(key, sizeof(*key));
97	uvm_swpkeysdeleted++;
98}
99
100/*
101 * Encrypt the data before it goes to swap, the size should be 64-bit
102 * aligned.
103 */
104
105void
106swap_encrypt(struct swap_key *key, caddr_t src, caddr_t dst, u_int64_t block,
107    size_t count)
108{
109	u_int32_t *dsrc = (u_int32_t *)src;
110	u_int32_t *ddst = (u_int32_t *)dst;
111	u_int32_t iv[4];
112	u_int32_t iv1, iv2, iv3, iv4;
113
114	if (!swap_encrypt_initialized)
115		swap_encrypt_initialized = 1;
116
117	swap_key_prepare(key, 1);
118
119	count /= sizeof(u_int32_t);
120
121	iv[0] = block >> 32; iv[1] = block; iv[2] = ~iv[0]; iv[3] = ~iv[1];
122	rijndael_encrypt(&swap_ctxt, (u_char *)iv, (u_char *)iv);
123	iv1 = iv[0]; iv2 = iv[1]; iv3 = iv[2]; iv4 = iv[3];
124
125	for (; count > 0; count -= 4) {
126		ddst[0] = dsrc[0] ^ iv1;
127		ddst[1] = dsrc[1] ^ iv2;
128		ddst[2] = dsrc[2] ^ iv3;
129		ddst[3] = dsrc[3] ^ iv4;
130		/*
131		 * Do not worry about endianess, it only needs to decrypt
132		 * on this machine.
133		 */
134		rijndael_encrypt(&swap_ctxt, (u_char *)ddst, (u_char *)ddst);
135		iv1 = ddst[0];
136		iv2 = ddst[1];
137		iv3 = ddst[2];
138		iv4 = ddst[3];
139
140		dsrc += 4;
141		ddst += 4;
142	}
143}
144
145/*
146 * Decrypt the data after we retrieved it from swap, the size should be 64-bit
147 * aligned.
148 */
149
150void
151swap_decrypt(struct swap_key *key, caddr_t src, caddr_t dst, u_int64_t block,
152    size_t count)
153{
154	u_int32_t *dsrc = (u_int32_t *)src;
155	u_int32_t *ddst = (u_int32_t *)dst;
156	u_int32_t iv[4];
157	u_int32_t iv1, iv2, iv3, iv4, niv1, niv2, niv3, niv4;
158
159	if (!swap_encrypt_initialized)
160		panic("swap_decrypt: key not initialized");
161
162	swap_key_prepare(key, 0);
163
164	count /= sizeof(u_int32_t);
165
166	iv[0] = block >> 32; iv[1] = block; iv[2] = ~iv[0]; iv[3] = ~iv[1];
167	rijndael_encrypt(&swap_ctxt, (u_char *)iv, (u_char *)iv);
168	iv1 = iv[0]; iv2 = iv[1]; iv3 = iv[2]; iv4 = iv[3];
169
170	for (; count > 0; count -= 4) {
171		ddst[0] = niv1 = dsrc[0];
172		ddst[1] = niv2 = dsrc[1];
173		ddst[2] = niv3 = dsrc[2];
174		ddst[3] = niv4 = dsrc[3];
175		rijndael_decrypt(&swap_ctxt, (u_char *)ddst, (u_char *)ddst);
176		ddst[0] ^= iv1;
177		ddst[1] ^= iv2;
178		ddst[2] ^= iv3;
179		ddst[3] ^= iv4;
180
181		iv1 = niv1;
182		iv2 = niv2;
183		iv3 = niv3;
184		iv4 = niv4;
185
186		dsrc += 4;
187		ddst += 4;
188	}
189}
190
191void
192swap_key_prepare(struct swap_key *key, int encrypt)
193{
194	/*
195	 * Check if we have prepared for this key already,
196	 * if we only have the encryption schedule, we have
197	 * to recompute and get the decryption schedule also.
198	 */
199	if (kcur == key && (encrypt || !swap_ctxt.enc_only))
200		return;
201
202	if (encrypt)
203		rijndael_set_key_enc_only(&swap_ctxt, (u_char *)key->key,
204		    sizeof(key->key) * 8);
205	else
206		rijndael_set_key(&swap_ctxt, (u_char *)key->key,
207		    sizeof(key->key) * 8);
208
209	kcur = key;
210}
211
212/*
213 * Make sure that a specific key is no longer available.
214 */
215
216void
217swap_key_cleanup(struct swap_key *key)
218{
219	/* Check if we have a key */
220	if (kcur == NULL || kcur != key)
221		return;
222
223	/* Zero out the subkeys */
224	explicit_bzero(&swap_ctxt, sizeof(swap_ctxt));
225
226	kcur = NULL;
227}
228