uvm_swap_encrypt.c revision 1.18 
1/*	$OpenBSD: uvm_swap_encrypt.c,v 1.18 2014/09/14 14:17:27 jsg 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 <dev/rndvar.h>
41#include <crypto/rijndael.h>
42
43#include <uvm/uvm.h>
44
45struct swap_key *kcur = NULL;
46rijndael_ctx swap_ctxt;
47
48int uvm_doswapencrypt = 1;
49u_int uvm_swpkeyscreated = 0;
50u_int uvm_swpkeysdeleted = 0;
51
52int swap_encrypt_initialized = 0;
53
54int
55swap_encrypt_ctl(int *name, u_int namelen, void *oldp, size_t *oldlenp,
56    void *newp, size_t newlen, struct proc *p)
57{
58	/* all sysctl names at this level are terminal */
59	if (namelen != 1)
60		return (ENOTDIR);		/* overloaded */
61
62	switch (name[0]) {
63	case SWPENC_ENABLE: {
64		int doencrypt = uvm_doswapencrypt;
65		int result;
66
67		result = sysctl_int(oldp, oldlenp, newp, newlen, &doencrypt);
68		if (result)
69			return result;
70
71		/*
72		 * Swap Encryption has been turned on, we need to
73		 * initialize state for swap devices that have been
74		 * added.
75		 */
76		if (doencrypt)
77			uvm_swap_initcrypt_all();
78		uvm_doswapencrypt = doencrypt;
79		return (0);
80	}
81	case SWPENC_CREATED:
82		return (sysctl_rdint(oldp, oldlenp, newp, uvm_swpkeyscreated));
83	case SWPENC_DELETED:
84		return (sysctl_rdint(oldp, oldlenp, newp, uvm_swpkeysdeleted));
85	default:
86		return (EOPNOTSUPP);
87	}
88	/* NOTREACHED */
89}
90
91void
92swap_key_delete(struct swap_key *key)
93{
94	/* Make sure that this key gets removed if we just used it */
95	swap_key_cleanup(key);
96
97	explicit_bzero(key, sizeof(*key));
98	uvm_swpkeysdeleted++;
99}
100
101/*
102 * Encrypt the data before it goes to swap, the size should be 64-bit
103 * aligned.
104 */
105
106void
107swap_encrypt(struct swap_key *key, caddr_t src, caddr_t dst, u_int64_t block,
108    size_t count)
109{
110	u_int32_t *dsrc = (u_int32_t *)src;
111	u_int32_t *ddst = (u_int32_t *)dst;
112	u_int32_t iv[4];
113	u_int32_t iv1, iv2, iv3, iv4;
114
115	if (!swap_encrypt_initialized)
116		swap_encrypt_initialized = 1;
117
118	swap_key_prepare(key, 1);
119
120	count /= sizeof(u_int32_t);
121
122	iv[0] = block >> 32; iv[1] = block; iv[2] = ~iv[0]; iv[3] = ~iv[1];
123	rijndael_encrypt(&swap_ctxt, (u_char *)iv, (u_char *)iv);
124	iv1 = iv[0]; iv2 = iv[1]; iv3 = iv[2]; iv4 = iv[3];
125
126	for (; count > 0; count -= 4) {
127		ddst[0] = dsrc[0] ^ iv1;
128		ddst[1] = dsrc[1] ^ iv2;
129		ddst[2] = dsrc[2] ^ iv3;
130		ddst[3] = dsrc[3] ^ iv4;
131		/*
132		 * Do not worry about endianess, it only needs to decrypt
133		 * on this machine.
134		 */
135		rijndael_encrypt(&swap_ctxt, (u_char *)ddst, (u_char *)ddst);
136		iv1 = ddst[0];
137		iv2 = ddst[1];
138		iv3 = ddst[2];
139		iv4 = ddst[3];
140
141		dsrc += 4;
142		ddst += 4;
143	}
144}
145
146/*
147 * Decrypt the data after we retrieved it from swap, the size should be 64-bit
148 * aligned.
149 */
150
151void
152swap_decrypt(struct swap_key *key, caddr_t src, caddr_t dst, u_int64_t block,
153    size_t count)
154{
155	u_int32_t *dsrc = (u_int32_t *)src;
156	u_int32_t *ddst = (u_int32_t *)dst;
157	u_int32_t iv[4];
158	u_int32_t iv1, iv2, iv3, iv4, niv1, niv2, niv3, niv4;
159
160	if (!swap_encrypt_initialized)
161		panic("swap_decrypt: key not initialized");
162
163	swap_key_prepare(key, 0);
164
165	count /= sizeof(u_int32_t);
166
167	iv[0] = block >> 32; iv[1] = block; iv[2] = ~iv[0]; iv[3] = ~iv[1];
168	rijndael_encrypt(&swap_ctxt, (u_char *)iv, (u_char *)iv);
169	iv1 = iv[0]; iv2 = iv[1]; iv3 = iv[2]; iv4 = iv[3];
170
171	for (; count > 0; count -= 4) {
172		ddst[0] = niv1 = dsrc[0];
173		ddst[1] = niv2 = dsrc[1];
174		ddst[2] = niv3 = dsrc[2];
175		ddst[3] = niv4 = dsrc[3];
176		rijndael_decrypt(&swap_ctxt, (u_char *)ddst, (u_char *)ddst);
177		ddst[0] ^= iv1;
178		ddst[1] ^= iv2;
179		ddst[2] ^= iv3;
180		ddst[3] ^= iv4;
181
182		iv1 = niv1;
183		iv2 = niv2;
184		iv3 = niv3;
185		iv4 = niv4;
186
187		dsrc += 4;
188		ddst += 4;
189	}
190}
191
192void
193swap_key_prepare(struct swap_key *key, int encrypt)
194{
195	/*
196	 * Check if we have prepared for this key already,
197	 * if we only have the encryption schedule, we have
198	 * to recompute and get the decryption schedule also.
199	 */
200	if (kcur == key && (encrypt || !swap_ctxt.enc_only))
201		return;
202
203	if (encrypt)
204		rijndael_set_key_enc_only(&swap_ctxt, (u_char *)key->key,
205		    sizeof(key->key) * 8);
206	else
207		rijndael_set_key(&swap_ctxt, (u_char *)key->key,
208		    sizeof(key->key) * 8);
209
210	kcur = key;
211}
212
213/*
214 * Make sure that a specific key is no longer available.
215 */
216
217void
218swap_key_cleanup(struct swap_key *key)
219{
220	/* Check if we have a key */
221	if (kcur == NULL || kcur != key)
222		return;
223
224	/* Zero out the subkeys */
225	explicit_bzero(&swap_ctxt, sizeof(swap_ctxt));
226
227	kcur = NULL;
228}
229