/*
 * 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/time.h>
#include <dev/rndvar.h>
#include <crypto/rijndael.h>

#include <vm/vm.h>
#include <vm/vm_conf.h>

#include <uvm/uvm.h>

struct swap_key *kcur = NULL;
rijndael_ctx swap_key;

int uvm_doswapencrypt = 0;
u_int uvm_swpkeyscreated = 0;
u_int uvm_swpkeysdeleted = 0;

int swap_encrypt_initalized = 0;

void
swap_key_create(struct swap_key *key)
{
	int i;
	u_int32_t *p = key->key;

	key->refcount = 0;
	for (i = 0; i < sizeof(key->key) / sizeof(u_int32_t); i++)
		*p++ = arc4random();

	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);

	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_initalized)
		swap_encrypt_initalized = 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_key, iv, 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 endianess, it only needs to decrypt
		 * on this machine
		 */
		rijndael_encrypt(&swap_key, ddst, 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_initalized)
		panic("swap_decrypt: key not initalized");

	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_key, iv, 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_key, ddst, 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 ang get the decryption schedule also
	 */
	if (kcur == key && (encrypt || swap_key.decrypt))
		return;

	rijndael_set_key(&swap_key, key->key,
			 sizeof(key->key) * 8,
			 encrypt);

	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 */
	bzero(&swap_key, sizeof(swap_key));

	kcur = NULL;
}