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/* $OpenBSD: softraid.c,v 1.2 2016/09/18 16:34:59 jsing Exp $ */
/*
* Copyright (c) 2012 Joel Sing <jsing@openbsd.org>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#include <sys/param.h>
#include <sys/queue.h>
#include <dev/biovar.h>
#include <dev/softraidvar.h>
#include <lib/libsa/bcrypt_pbkdf.h>
#include <lib/libsa/hmac_sha1.h>
#include <lib/libsa/pkcs5_pbkdf2.h>
#include <lib/libsa/rijndael.h>
#include "stand.h"
#include "softraid.h"
#define RIJNDAEL128_BLOCK_LEN 16
#define PASSPHRASE_LENGTH 1024
#define SR_CRYPTO_KEYBLOCK_BYTES SR_CRYPTO_MAXKEYS * SR_CRYPTO_KEYBYTES
/* List of softraid volumes. */
struct sr_boot_volume_head sr_volumes;
/* List of softraid keydisks. */
struct sr_boot_keydisk_head sr_keydisks;
#ifdef DEBUG
void
printhex(const char *s, const u_int8_t *buf, size_t len)
{
u_int8_t n1, n2;
size_t i;
printf("%s: ", s);
for (i = 0; i < len; i++) {
n1 = buf[i] & 0x0f;
n2 = buf[i] >> 4;
printf("%c", n2 > 9 ? n2 + 'a' - 10 : n2 + '0');
printf("%c", n1 > 9 ? n1 + 'a' - 10 : n1 + '0');
}
printf("\n");
}
#endif
void
sr_clear_keys(void)
{
struct sr_boot_volume *bv;
struct sr_boot_keydisk *kd;
SLIST_FOREACH(bv, &sr_volumes, sbv_link) {
if (bv->sbv_level != 'C')
continue;
if (bv->sbv_keys != NULL) {
explicit_bzero(bv->sbv_keys, SR_CRYPTO_KEYBLOCK_BYTES);
free(bv->sbv_keys, SR_CRYPTO_KEYBLOCK_BYTES);
bv->sbv_keys = NULL;
}
if (bv->sbv_maskkey != NULL) {
explicit_bzero(bv->sbv_maskkey, SR_CRYPTO_MAXKEYBYTES);
free(bv->sbv_maskkey, SR_CRYPTO_MAXKEYBYTES);
bv->sbv_maskkey = NULL;
}
}
SLIST_FOREACH(kd, &sr_keydisks, kd_link) {
explicit_bzero(kd, sizeof(*kd));
free(kd, sizeof(*kd));
}
}
void
sr_crypto_calculate_check_hmac_sha1(u_int8_t *maskkey, int maskkey_size,
u_int8_t *key, int key_size, u_char *check_digest)
{
u_int8_t check_key[SHA1_DIGEST_LENGTH];
SHA1_CTX shactx;
explicit_bzero(check_key, sizeof(check_key));
explicit_bzero(&shactx, sizeof(shactx));
/* k = SHA1(mask_key) */
SHA1Init(&shactx);
SHA1Update(&shactx, maskkey, maskkey_size);
SHA1Final(check_key, &shactx);
/* mac = HMAC_SHA1_k(unencrypted key) */
hmac_sha1(key, key_size, check_key, sizeof(check_key), check_digest);
explicit_bzero(check_key, sizeof(check_key));
explicit_bzero(&shactx, sizeof(shactx));
}
int
sr_crypto_decrypt_keys(struct sr_boot_volume *bv)
{
struct sr_meta_crypto *cm;
struct sr_boot_keydisk *kd;
struct sr_meta_opt_item *omi;
struct sr_crypto_pbkdf *kdfhint;
struct sr_crypto_kdfinfo kdfinfo;
char passphrase[PASSPHRASE_LENGTH];
u_int8_t digest[SHA1_DIGEST_LENGTH];
u_int8_t *keys = NULL;
u_int8_t *kp, *cp;
rijndael_ctx ctx;
u_int32_t type;
int rv = -1;
int c, i;
SLIST_FOREACH(omi, &bv->sbv_meta_opt, omi_link)
if (omi->omi_som->som_type == SR_OPT_CRYPTO)
break;
if (omi == NULL) {
printf("Crypto metadata not found!\n");
goto done;
}
cm = (struct sr_meta_crypto *)omi->omi_som;
kdfhint = (struct sr_crypto_pbkdf *)&cm->scm_kdfhint;
switch (cm->scm_mask_alg) {
case SR_CRYPTOM_AES_ECB_256:
break;
default:
printf("unsupported encryption algorithm %u\n",
cm->scm_mask_alg);
goto done;
}
SLIST_FOREACH(kd, &sr_keydisks, kd_link) {
if (bcmp(&kd->kd_uuid, &bv->sbv_uuid, sizeof(kd->kd_uuid)) == 0)
break;
}
if (kd) {
bcopy(&kd->kd_key, &kdfinfo.maskkey, sizeof(kdfinfo.maskkey));
} else {
if (kdfhint->generic.type != SR_CRYPTOKDFT_PKCS5_PBKDF2 &&
kdfhint->generic.type != SR_CRYPTOKDFT_BCRYPT_PBKDF) {
printf("unknown KDF type %u\n", kdfhint->generic.type);
goto done;
}
printf("Passphrase: ");
for (i = 0; i < PASSPHRASE_LENGTH - 1; i++) {
c = cngetc();
if (c == '\r' || c == '\n')
break;
else if (c == '\b') {
i = i > 0 ? i - 2 : -1;
continue;
}
passphrase[i] = (c & 0xff);
}
passphrase[i] = 0;
printf("\n");
#ifdef DEBUG
printf("Got passphrase: %s with len %d\n",
passphrase, strlen(passphrase));
#endif
type = kdfhint->generic.type;
if (type == SR_CRYPTOKDFT_PKCS5_PBKDF2) {
if (pkcs5_pbkdf2(passphrase, strlen(passphrase),
kdfhint->salt, sizeof(kdfhint->salt),
kdfinfo.maskkey, sizeof(kdfinfo.maskkey),
kdfhint->rounds) != 0) {
printf("pkcs5_pbkdf2 failed\n");
goto done;
}
} else if (type == SR_CRYPTOKDFT_BCRYPT_PBKDF) {
if (bcrypt_pbkdf(passphrase, strlen(passphrase),
kdfhint->salt, sizeof(kdfhint->salt),
kdfinfo.maskkey, sizeof(kdfinfo.maskkey),
kdfhint->rounds) != 0) {
printf("bcrypt_pbkdf failed\n");
goto done;
}
} else {
printf("unknown KDF type %u\n", kdfhint->generic.type);
goto done;
}
}
/* kdfinfo->maskkey now has key. */
/* Decrypt disk keys. */
keys = alloc(SR_CRYPTO_KEYBLOCK_BYTES);
bzero(keys, SR_CRYPTO_KEYBLOCK_BYTES);
if (rijndael_set_key(&ctx, kdfinfo.maskkey, 256) != 0)
goto done;
cp = (u_int8_t *)cm->scm_key;
kp = keys;
for (i = 0; i < SR_CRYPTO_KEYBLOCK_BYTES; i += RIJNDAEL128_BLOCK_LEN)
rijndael_decrypt(&ctx, (u_char *)(cp + i), (u_char *)(kp + i));
/* Check that the key decrypted properly. */
sr_crypto_calculate_check_hmac_sha1(kdfinfo.maskkey,
sizeof(kdfinfo.maskkey), keys, SR_CRYPTO_KEYBLOCK_BYTES, digest);
if (bcmp(digest, cm->chk_hmac_sha1.sch_mac, sizeof(digest))) {
printf("incorrect passphrase or keydisk\n");
goto done;
}
/* Keys and keydisks will be cleared before boot and from _rtt. */
bv->sbv_keys = keys;
bv->sbv_maskkey = alloc(sizeof(kdfinfo.maskkey));
bcopy(&kdfinfo.maskkey, bv->sbv_maskkey, sizeof(kdfinfo.maskkey));
rv = 0;
done:
explicit_bzero(passphrase, PASSPHRASE_LENGTH);
explicit_bzero(&kdfinfo, sizeof(kdfinfo));
explicit_bzero(digest, sizeof(digest));
if (keys != NULL && rv != 0) {
explicit_bzero(keys, SR_CRYPTO_KEYBLOCK_BYTES);
free(keys, SR_CRYPTO_KEYBLOCK_BYTES);
}
return (rv);
}
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