freebsd-nq/sys/boot/geli/geliboot_crypto.c
Allan Jude ec5c0e5be9 Implement boot-time encryption key passing (keybuf)
This patch adds a general mechanism for providing encryption keys to the
kernel from the boot loader. This is intended to enable GELI support at
boot time, providing a better mechanism for passing keys to the kernel
than environment variables. It is designed to be extensible to other
applications, and can easily handle multiple encrypted volumes with
different keys.

This mechanism is currently used by the pending GELI EFI work.
Additionally, this mechanism can potentially be used to interface with
GRUB, opening up options for coreboot+GRUB configurations with completely
encrypted disks.

Another benefit over the existing system is that it does not require
re-deriving the user key from the password at each boot stage.

Most of this patch was written by Eric McCorkle. It was extended by
Allan Jude with a number of minor enhancements and extending the keybuf
feature into boot2.

GELI user keys are now derived once, in boot2, then passed to the loader,
which reuses the key, then passes it to the kernel, where the GELI module
destroys the keybuf after decrypting the volumes.

Submitted by:	Eric McCorkle <eric@metricspace.net> (Original Version)
Reviewed by:	oshogbo (earlier version), cem (earlier version)
MFC after:	3 weeks
Relnotes:	yes
Sponsored by:	ScaleEngine Inc.
Differential Revision:	https://reviews.freebsd.org/D9575
2017-04-01 05:05:22 +00:00

141 lines
3.9 KiB
C

/*-
* Copyright (c) 2005-2010 Pawel Jakub Dawidek <pjd@FreeBSD.org>
* Copyright (c) 2015 Allan Jude <allanjude@FreeBSD.org>
* 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.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``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 AUTHORS OR CONTRIBUTORS 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.
*
* $FreeBSD$
*/
#include <stdio.h>
#include <string.h>
#include <strings.h>
#include "geliboot_internal.h"
#include "geliboot.h"
int
geliboot_crypt(u_int algo, int enc, u_char *data, size_t datasize,
const u_char *key, size_t keysize, u_char *iv)
{
keyInstance aeskey;
cipherInstance cipher;
struct aes_xts_ctx xtsctx, *ctxp;
size_t xts_len;
int err, blks, i;
switch (algo) {
case CRYPTO_AES_CBC:
err = rijndael_makeKey(&aeskey, !enc, keysize,
(const char *)key);
if (err < 0) {
printf("Failed to setup decryption keys: %d\n", err);
return (err);
}
err = rijndael_cipherInit(&cipher, MODE_CBC, iv);
if (err < 0) {
printf("Failed to setup IV: %d\n", err);
return (err);
}
switch (enc) {
case 0: /* decrypt */
blks = rijndael_blockDecrypt(&cipher, &aeskey, data,
datasize * 8, data);
break;
case 1: /* encrypt */
blks = rijndael_blockEncrypt(&cipher, &aeskey, data,
datasize * 8, data);
break;
}
if (datasize != (blks / 8)) {
printf("Failed to decrypt the entire input: "
"%u != %u\n", blks, datasize);
return (1);
}
break;
case CRYPTO_AES_XTS:
xts_len = keysize << 1;
ctxp = &xtsctx;
rijndael_set_key(&ctxp->key1, key, xts_len / 2);
rijndael_set_key(&ctxp->key2, key + (xts_len / 16), xts_len / 2);
enc_xform_aes_xts.reinit(ctxp, iv);
switch (enc) {
case 0: /* decrypt */
for (i = 0; i < datasize; i += AES_XTS_BLOCKSIZE) {
enc_xform_aes_xts.decrypt(ctxp, data + i);
}
break;
case 1: /* encrypt */
for (i = 0; i < datasize; i += AES_XTS_BLOCKSIZE) {
enc_xform_aes_xts.encrypt(ctxp, data + i);
}
break;
}
break;
default:
printf("Unsupported crypto algorithm #%d\n", algo);
return (1);
}
return (0);
}
static int
g_eli_crypto_cipher(u_int algo, int enc, u_char *data, size_t datasize,
const u_char *key, size_t keysize)
{
u_char iv[keysize];
explicit_bzero(iv, sizeof(iv));
return (geliboot_crypt(algo, enc, data, datasize, key, keysize, iv));
}
int
g_eli_crypto_encrypt(u_int algo, u_char *data, size_t datasize,
const u_char *key, size_t keysize)
{
/* We prefer AES-CBC for metadata protection. */
if (algo == CRYPTO_AES_XTS)
algo = CRYPTO_AES_CBC;
return (g_eli_crypto_cipher(algo, 1, data, datasize, key, keysize));
}
int
g_eli_crypto_decrypt(u_int algo, u_char *data, size_t datasize,
const u_char *key, size_t keysize)
{
/* We prefer AES-CBC for metadata protection. */
if (algo == CRYPTO_AES_XTS)
algo = CRYPTO_AES_CBC;
return (g_eli_crypto_cipher(algo, 0, data, datasize, key, keysize));
}