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/* $OpenBSD: uvm_swap_encrypt.c,v 1.24 2021/03/12 14:15:49 jsg Exp $ */
/*
* Copyright 1999 Niels Provos <provos@citi.umich.edu>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by Niels Provos.
* 4. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/malloc.h>
#include <sys/sysctl.h>
#include <sys/time.h>
#include <crypto/rijndael.h>
#include <uvm/uvm.h>
#include <uvm/uvm_swap_encrypt.h>
struct swap_key *kcur = NULL;
rijndael_ctx swap_ctxt;
int uvm_doswapencrypt = 1;
u_int uvm_swpkeyscreated = 0;
u_int uvm_swpkeysdeleted = 0;
int swap_encrypt_initialized = 0;
int
swap_encrypt_ctl(int *name, u_int namelen, void *oldp, size_t *oldlenp,
void *newp, size_t newlen, struct proc *p)
{
/* all sysctl names at this level are terminal */
if (namelen != 1)
return (ENOTDIR); /* overloaded */
switch (name[0]) {
case SWPENC_ENABLE: {
int doencrypt = uvm_doswapencrypt;
int result;
result = sysctl_int_bounded(oldp, oldlenp, newp, newlen,
&doencrypt, 0, 1);
if (result)
return result;
/*
* Swap Encryption has been turned on, we need to
* initialize state for swap devices that have been
* added.
*/
if (doencrypt)
uvm_swap_initcrypt_all();
uvm_doswapencrypt = doencrypt;
return (0);
}
case SWPENC_CREATED:
return (sysctl_rdint(oldp, oldlenp, newp, uvm_swpkeyscreated));
case SWPENC_DELETED:
return (sysctl_rdint(oldp, oldlenp, newp, uvm_swpkeysdeleted));
default:
return (EOPNOTSUPP);
}
/* NOTREACHED */
}
void
swap_key_create(struct swap_key *key)
{
arc4random_buf(key->key, sizeof(key->key));
uvm_swpkeyscreated++;
}
void
swap_key_delete(struct swap_key *key)
{
/* Make sure that this key gets removed if we just used it */
swap_key_cleanup(key);
explicit_bzero(key, sizeof(*key));
uvm_swpkeysdeleted++;
}
/*
* Encrypt the data before it goes to swap, the size should be 64-bit
* aligned.
*/
void
swap_encrypt(struct swap_key *key, caddr_t src, caddr_t dst, u_int64_t block,
size_t count)
{
u_int32_t *dsrc = (u_int32_t *)src;
u_int32_t *ddst = (u_int32_t *)dst;
u_int32_t iv[4];
u_int32_t iv1, iv2, iv3, iv4;
if (!swap_encrypt_initialized)
swap_encrypt_initialized = 1;
swap_key_prepare(key, 1);
count /= sizeof(u_int32_t);
iv[0] = block >> 32; iv[1] = block; iv[2] = ~iv[0]; iv[3] = ~iv[1];
rijndael_encrypt(&swap_ctxt, (u_char *)iv, (u_char *)iv);
iv1 = iv[0]; iv2 = iv[1]; iv3 = iv[2]; iv4 = iv[3];
for (; count > 0; count -= 4) {
ddst[0] = dsrc[0] ^ iv1;
ddst[1] = dsrc[1] ^ iv2;
ddst[2] = dsrc[2] ^ iv3;
ddst[3] = dsrc[3] ^ iv4;
/*
* Do not worry about endianness, it only needs to decrypt
* on this machine.
*/
rijndael_encrypt(&swap_ctxt, (u_char *)ddst, (u_char *)ddst);
iv1 = ddst[0];
iv2 = ddst[1];
iv3 = ddst[2];
iv4 = ddst[3];
dsrc += 4;
ddst += 4;
}
}
/*
* Decrypt the data after we retrieved it from swap, the size should be 64-bit
* aligned.
*/
void
swap_decrypt(struct swap_key *key, caddr_t src, caddr_t dst, u_int64_t block,
size_t count)
{
u_int32_t *dsrc = (u_int32_t *)src;
u_int32_t *ddst = (u_int32_t *)dst;
u_int32_t iv[4];
u_int32_t iv1, iv2, iv3, iv4, niv1, niv2, niv3, niv4;
if (!swap_encrypt_initialized)
panic("swap_decrypt: key not initialized");
swap_key_prepare(key, 0);
count /= sizeof(u_int32_t);
iv[0] = block >> 32; iv[1] = block; iv[2] = ~iv[0]; iv[3] = ~iv[1];
rijndael_encrypt(&swap_ctxt, (u_char *)iv, (u_char *)iv);
iv1 = iv[0]; iv2 = iv[1]; iv3 = iv[2]; iv4 = iv[3];
for (; count > 0; count -= 4) {
ddst[0] = niv1 = dsrc[0];
ddst[1] = niv2 = dsrc[1];
ddst[2] = niv3 = dsrc[2];
ddst[3] = niv4 = dsrc[3];
rijndael_decrypt(&swap_ctxt, (u_char *)ddst, (u_char *)ddst);
ddst[0] ^= iv1;
ddst[1] ^= iv2;
ddst[2] ^= iv3;
ddst[3] ^= iv4;
iv1 = niv1;
iv2 = niv2;
iv3 = niv3;
iv4 = niv4;
dsrc += 4;
ddst += 4;
}
}
void
swap_key_prepare(struct swap_key *key, int encrypt)
{
/*
* Check if we have prepared for this key already,
* if we only have the encryption schedule, we have
* to recompute and get the decryption schedule also.
*/
if (kcur == key && (encrypt || !swap_ctxt.enc_only))
return;
if (encrypt)
rijndael_set_key_enc_only(&swap_ctxt, (u_char *)key->key,
sizeof(key->key) * 8);
else
rijndael_set_key(&swap_ctxt, (u_char *)key->key,
sizeof(key->key) * 8);
kcur = key;
}
/*
* Make sure that a specific key is no longer available.
*/
void
swap_key_cleanup(struct swap_key *key)
{
/* Check if we have a key */
if (kcur == NULL || kcur != key)
return;
/* Zero out the subkeys */
explicit_bzero(&swap_ctxt, sizeof(swap_ctxt));
kcur = NULL;
}
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