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grub/grub-core/disk/geli.c
Vladimir 'phcoder' Serbinenko f718594e32 update fixme
2011-04-24 21:41:49 +02:00

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/*
* GRUB -- GRand Unified Bootloader
* Copyright (C) 2003,2007,2010,2011 Free Software Foundation, Inc.
*
* GRUB is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* GRUB is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with GRUB. If not, see <http://www.gnu.org/licenses/>.
*/
/* This file is loosely based on FreeBSD geli implementation
(but no code was directly copied). FreeBSD geli is distributed under
following terms: */
/*-
* Copyright (c) 2005-2006 Pawel Jakub Dawidek <pjd@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.
*/
#include <grub/cryptodisk.h>
#include <grub/types.h>
#include <grub/misc.h>
#include <grub/mm.h>
#include <grub/dl.h>
#include <grub/err.h>
#include <grub/disk.h>
#include <grub/crypto.h>
#include <grub/extcmd.h>
#include <grub/i18n.h>
GRUB_MOD_LICENSE ("GPLv3+");
struct grub_geli_key
{
grub_uint8_t iv_key[64];
grub_uint8_t cipher_key[64];
grub_uint8_t hmac[64];
} __attribute__ ((packed));
struct grub_geli_phdr
{
grub_uint8_t magic[16];
#define GELI_MAGIC "GEOM::ELI"
grub_uint32_t version;
grub_uint32_t flags;
grub_uint16_t alg;
grub_uint16_t keylen;
grub_uint16_t unused3[5];
grub_uint32_t sector_size;
grub_uint8_t keys_used;
grub_uint32_t niter;
grub_uint8_t salt[64];
struct grub_geli_key keys[2];
} __attribute__ ((packed));
enum
{
GRUB_GELI_FLAGS_ONETIME = 1,
GRUB_GELI_FLAGS_BOOT = 2,
};
/* FIXME: support version 0. */
/* FIXME: support big-endian pre-version-4 volumes. */
/* FIXME: support for keyfiles. */
/* FIXME: support for HMAC. */
const char *algorithms[] = {
[0x01] = "des",
[0x02] = "3des",
[0x03] = "blowfish",
[0x04] = "cast5",
/* FIXME: 0x05 is skipjack, but we don't have it. */
[0x0b] = "aes",
/* FIXME: 0x10 is null. */
[0x15] = "camellia128",
[0x16] = "aes"
};
#define MAX_PASSPHRASE 256
static const struct grub_arg_option options[] =
{
{"uuid", 'u', 0, N_("Mount by UUID."), 0, 0},
{"all", 'a', 0, N_("Mount all."), 0, 0},
{"boot", 'b', 0, N_("Mount all volumes marked as boot."), 0, 0},
{0, 0, 0, 0, 0, 0}
};
static int check_uuid, check_boot, have_it;
static char *search_uuid;
static gcry_err_code_t
geli_rekey (struct grub_cryptodisk *dev, grub_uint64_t zoneno)
{
gcry_err_code_t gcry_err;
const struct {
char magic[4];
grub_uint64_t zone;
} __attribute__ ((packed)) tohash
= { {'e', 'k', 'e', 'y'}, grub_cpu_to_le64 (zoneno) };
grub_uint64_t key[(dev->hash->mdlen + 7) / 8];
grub_dprintf ("geli", "rekeying %" PRIuGRUB_UINT64_T " keysize=%d\n",
zoneno, dev->rekey_derived_size);
gcry_err = grub_crypto_hmac_buffer (dev->hash, dev->rekey_key, 64,
&tohash, sizeof (tohash), key);
if (gcry_err)
return grub_crypto_gcry_error (gcry_err);
return grub_cryptodisk_setkey (dev, (grub_uint8_t *) key,
dev->rekey_derived_size);
}
static inline int
ascii2hex (char c)
{
if (c >= '0' && c <= '9')
return c - '0';
if (c >= 'a' && c <= 'f')
return c - 'a' + 10;
if (c >= 'A' && c <= 'F')
return c - 'A' + 10;
return 0;
}
static grub_cryptodisk_t
configure_ciphers (const struct grub_geli_phdr *header)
{
grub_cryptodisk_t newdev;
grub_crypto_cipher_handle_t cipher = NULL, secondary_cipher = NULL;
const struct gcry_cipher_spec *ciph;
const char *ciphername = NULL;
char uuid[GRUB_MD_SHA256->mdlen * 2 + 1];
grub_uint8_t uuidbin[GRUB_MD_SHA256->mdlen];
grub_uint8_t *iptr;
char *optr;
gcry_err_code_t gcry_err;
/* Look for GELI magic sequence. */
if (grub_memcmp (header->magic, GELI_MAGIC, sizeof (GELI_MAGIC))
|| grub_le_to_cpu32 (header->version) > 5
|| grub_le_to_cpu32 (header->version) < 1)
{
grub_dprintf ("geli", "wrong magic %02x\n", header->magic[0]);
return NULL;
}
if ((grub_le_to_cpu32 (header->sector_size)
& (grub_le_to_cpu32 (header->sector_size) - 1))
|| grub_le_to_cpu32 (header->sector_size) == 0)
{
grub_dprintf ("geli", "incorrect sector size %d\n",
grub_le_to_cpu32 (header->sector_size));
return NULL;
}
if (grub_le_to_cpu32 (header->flags) & GRUB_GELI_FLAGS_ONETIME)
{
grub_dprintf ("geli", "skipping one-time volume\n");
return NULL;
}
if (check_boot && !(grub_le_to_cpu32 (header->flags) & GRUB_GELI_FLAGS_BOOT))
{
grub_dprintf ("geli", "not a boot volume\n");
return NULL;
}
gcry_err = grub_crypto_hmac_buffer (GRUB_MD_SHA256,
header->salt, sizeof (header->salt),
"uuid", sizeof ("uuid") - 1, uuidbin);
if (gcry_err)
{
grub_crypto_gcry_error (gcry_err);
return NULL;
}
optr = uuid;
for (iptr = uuidbin; iptr < &uuidbin[ARRAY_SIZE (uuidbin)]; iptr++)
{
grub_snprintf (optr, 3, "%02x", *iptr);
optr += 2;
}
*optr = 0;
if (check_uuid && grub_strcasecmp (search_uuid, uuid) != 0)
{
grub_dprintf ("geli", "%s != %s\n", uuid, search_uuid);
return NULL;
}
if (grub_le_to_cpu16 (header->alg) >= ARRAY_SIZE (algorithms)
|| algorithms[grub_le_to_cpu16 (header->alg)] == NULL)
{
grub_error (GRUB_ERR_FILE_NOT_FOUND, "Cipher 0x%x unknown",
grub_le_to_cpu16 (header->alg));
return NULL;
}
ciphername = algorithms[grub_le_to_cpu16 (header->alg)];
ciph = grub_crypto_lookup_cipher_by_name (ciphername);
if (!ciph)
{
grub_error (GRUB_ERR_FILE_NOT_FOUND, "Cipher %s isn't available",
ciphername);
return NULL;
}
/* Configure the cipher used for the bulk data. */
cipher = grub_crypto_cipher_open (ciph);
if (!cipher)
return NULL;
if (grub_le_to_cpu16 (header->alg) == 0x16)
{
secondary_cipher = grub_crypto_cipher_open (ciph);
if (!secondary_cipher)
return NULL;
}
if (grub_le_to_cpu16 (header->keylen) > 1024)
{
grub_error (GRUB_ERR_BAD_ARGUMENT, "invalid keysize %d",
grub_le_to_cpu16 (header->keylen));
return NULL;
}
newdev = grub_zalloc (sizeof (struct grub_cryptodisk));
if (!newdev)
return NULL;
newdev->cipher = cipher;
newdev->secondary_cipher = secondary_cipher;
newdev->offset = 0;
newdev->source_disk = NULL;
newdev->benbi_log = 0;
if (grub_le_to_cpu16 (header->alg) == 0x16)
{
newdev->mode = GRUB_CRYPTODISK_MODE_XTS;
newdev->mode_iv = GRUB_CRYPTODISK_MODE_IV_BYTECOUNT64;
}
else
{
newdev->mode = GRUB_CRYPTODISK_MODE_CBC;
newdev->mode_iv = GRUB_CRYPTODISK_MODE_IV_BYTECOUNT64_HASH;
}
newdev->essiv_cipher = NULL;
newdev->essiv_hash = NULL;
newdev->hash = GRUB_MD_SHA512;
newdev->iv_hash = GRUB_MD_SHA256;
for (newdev->log_sector_size = 0;
(1U << newdev->log_sector_size) < grub_le_to_cpu32 (header->sector_size);
newdev->log_sector_size++);
if (grub_le_to_cpu32 (header->version) >= 5)
{
newdev->rekey = geli_rekey;
newdev->rekey_shift = 20;
}
grub_memcpy (newdev->uuid, uuid, sizeof (newdev->uuid));
COMPILE_TIME_ASSERT (sizeof (newdev->uuid) >= 32 * 2 + 1);
return newdev;
}
static grub_err_t
recover_key (grub_cryptodisk_t dev, const struct grub_geli_phdr *header,
const char *name, grub_disk_t source __attribute__ ((unused)))
{
grub_size_t keysize = grub_le_to_cpu16 (header->keylen) / 8;
grub_uint8_t digest[dev->hash->mdlen];
grub_uint8_t geomkey[dev->hash->mdlen];
grub_uint8_t verify_key[dev->hash->mdlen];
grub_uint8_t zero[dev->cipher->cipher->blocksize];
char passphrase[MAX_PASSPHRASE] = "";
unsigned i;
gcry_err_code_t gcry_err;
grub_memset (zero, 0, sizeof (zero));
grub_printf ("Attempting to decrypt master key...\n");
/* Get the passphrase from the user. */
grub_printf ("Enter passphrase for %s (%s): ", name, dev->uuid);
if (!grub_password_get (passphrase, MAX_PASSPHRASE))
return grub_error (GRUB_ERR_BAD_ARGUMENT, "Passphrase not supplied");
/* Calculate the PBKDF2 of the user supplied passphrase. */
if (grub_le_to_cpu32 (header->niter) != 0)
{
grub_uint8_t pbkdf_key[64];
gcry_err = grub_crypto_pbkdf2 (dev->hash, (grub_uint8_t *) passphrase,
grub_strlen (passphrase),
header->salt,
sizeof (header->salt),
grub_le_to_cpu32 (header->niter),
pbkdf_key, sizeof (pbkdf_key));
if (gcry_err)
return grub_crypto_gcry_error (gcry_err);
gcry_err = grub_crypto_hmac_buffer (dev->hash, NULL, 0, pbkdf_key,
sizeof (pbkdf_key), geomkey);
if (gcry_err)
return grub_crypto_gcry_error (gcry_err);
}
else
{
struct grub_crypto_hmac_handle *hnd;
hnd = grub_crypto_hmac_init (dev->hash, NULL, 0);
if (!hnd)
return grub_crypto_gcry_error (GPG_ERR_OUT_OF_MEMORY);
grub_crypto_hmac_write (hnd, header->salt, sizeof (header->salt));
grub_crypto_hmac_write (hnd, passphrase, grub_strlen (passphrase));
gcry_err = grub_crypto_hmac_fini (hnd, geomkey);
if (gcry_err)
return grub_crypto_gcry_error (gcry_err);
}
gcry_err = grub_crypto_hmac_buffer (dev->hash, geomkey,
sizeof (geomkey), "\1", 1, digest);
if (gcry_err)
return grub_crypto_gcry_error (gcry_err);
gcry_err = grub_crypto_hmac_buffer (dev->hash, geomkey,
sizeof (geomkey), "\0", 1, verify_key);
if (gcry_err)
return grub_crypto_gcry_error (gcry_err);
grub_dprintf ("geli", "keylen = %" PRIuGRUB_SIZE "\n", keysize);
/* Try to recover master key from each active keyslot. */
for (i = 0; i < ARRAY_SIZE (header->keys); i++)
{
struct grub_geli_key candidate_key;
grub_uint8_t key_hmac[dev->hash->mdlen];
/* Check if keyslot is enabled. */
if (! (header->keys_used & (1 << i)))
continue;
grub_dprintf ("geli", "Trying keyslot %d\n", i);
gcry_err = grub_crypto_cipher_set_key (dev->cipher,
digest, keysize);
if (gcry_err)
return grub_crypto_gcry_error (gcry_err);
gcry_err = grub_crypto_cbc_decrypt (dev->cipher, &candidate_key,
&header->keys[i],
sizeof (candidate_key),
zero);
if (gcry_err)
return grub_crypto_gcry_error (gcry_err);
gcry_err = grub_crypto_hmac_buffer (dev->hash, verify_key,
sizeof (verify_key),
&candidate_key,
(sizeof (candidate_key)
- sizeof (candidate_key.hmac)),
key_hmac);
if (gcry_err)
return grub_crypto_gcry_error (gcry_err);
if (grub_memcmp (candidate_key.hmac, key_hmac, dev->hash->mdlen) != 0)
continue;
grub_printf ("Slot %d opened\n", i);
/* Set the master key. */
if (!dev->rekey)
{
grub_size_t real_keysize = keysize;
if (grub_le_to_cpu16 (header->alg) == 0x16)
real_keysize *= 2;
gcry_err = grub_cryptodisk_setkey (dev, candidate_key.cipher_key,
real_keysize);
if (gcry_err)
return grub_crypto_gcry_error (gcry_err);
}
else
{
grub_size_t real_keysize = keysize;
if (grub_le_to_cpu16 (header->alg) == 0x16)
real_keysize *= 2;
/* For a reason I don't know, the IV key is used in rekeying. */
grub_memcpy (dev->rekey_key, candidate_key.iv_key,
sizeof (candidate_key.iv_key));
dev->rekey_derived_size = real_keysize;
dev->last_rekey = -1;
COMPILE_TIME_ASSERT (sizeof (dev->rekey_key)
>= sizeof (candidate_key.iv_key));
}
dev->iv_prefix_len = sizeof (candidate_key.iv_key);
grub_memcpy (dev->iv_prefix, candidate_key.iv_key,
sizeof (candidate_key.iv_key));
COMPILE_TIME_ASSERT (sizeof (dev->iv_prefix) >= sizeof (candidate_key.iv_key));
return GRUB_ERR_NONE;
}
return GRUB_ACCESS_DENIED;
}
static void
close (grub_cryptodisk_t luks)
{
grub_crypto_cipher_close (luks->cipher);
grub_crypto_cipher_close (luks->secondary_cipher);
grub_crypto_cipher_close (luks->essiv_cipher);
grub_free (luks);
}
static grub_err_t
grub_geli_scan_device_real (const char *name, grub_disk_t source)
{
grub_err_t err;
struct grub_geli_phdr header;
grub_cryptodisk_t newdev, dev;
grub_disk_addr_t sector;
grub_dprintf ("geli", "scanning %s\n", source->name);
dev = grub_cryptodisk_get_by_source_disk (source);
if (dev)
return GRUB_ERR_NONE;
sector = grub_disk_get_size (source);
if (sector == GRUB_DISK_SIZE_UNKNOWN)
return grub_error (GRUB_ERR_OUT_OF_RANGE, "not a geli");
/* Read the LUKS header. */
err = grub_disk_read (source, sector - 1, 0, sizeof (header), &header);
if (err)
return err;
newdev = configure_ciphers (&header);
if (!newdev)
return grub_errno;
newdev->total_length = grub_disk_get_size (source) - 1;
err = recover_key (newdev, &header, name, source);
if (err)
{
close (newdev);
return err;
}
grub_cryptodisk_insert (newdev, name, source);
have_it = 1;
return GRUB_ERR_NONE;
}
#ifdef GRUB_UTIL
grub_err_t
grub_geli_cheat_mount (const char *sourcedev, const char *cheat)
{
grub_err_t err;
struct grub_geli_phdr header;
grub_cryptodisk_t newdev, dev;
grub_disk_t source;
grub_disk_addr_t sector;
/* Try to open disk. */
source = grub_disk_open (sourcedev);
if (!source)
return grub_errno;
dev = grub_cryptodisk_get_by_source_disk (source);
if (dev)
{
grub_disk_close (source);
return GRUB_ERR_NONE;
}
sector = grub_disk_get_size (source);
if (sector == GRUB_DISK_SIZE_UNKNOWN)
return grub_error (GRUB_ERR_OUT_OF_RANGE, "not a geli");
/* Read the LUKS header. */
err = grub_disk_read (source, sector - 1, 0, sizeof (header), &header);
if (err)
return err;
newdev = configure_ciphers (&header);
if (!newdev)
{
grub_disk_close (source);
return grub_errno;
}
newdev->total_length = grub_disk_get_size (source) - 1;
err = grub_cryptodisk_cheat_insert (newdev, sourcedev, source, cheat);
grub_disk_close (source);
if (err)
grub_free (newdev);
return err;
}
#endif
static int
grub_geli_scan_device (const char *name)
{
grub_err_t err;
grub_disk_t source;
/* Try to open disk. */
source = grub_disk_open (name);
if (!source)
return grub_errno;
err = grub_geli_scan_device_real (name, source);
grub_disk_close (source);
if (err)
grub_print_error ();
return have_it && check_uuid ? 0 : 1;
}
#ifdef GRUB_UTIL
void
grub_util_geli_print_uuid (grub_disk_t disk)
{
grub_cryptodisk_t dev = (grub_cryptodisk_t) disk->data;
grub_printf ("%s ", dev->uuid);
}
#endif
static grub_err_t
grub_cmd_gelimount (grub_extcmd_context_t ctxt, int argc, char **args)
{
struct grub_arg_list *state = ctxt->state;
if (argc < 1 && !state[1].set && !state[2].set)
return grub_error (GRUB_ERR_BAD_ARGUMENT, "device name required");
have_it = 0;
if (state[0].set)
{
grub_cryptodisk_t dev;
dev = grub_cryptodisk_get_by_uuid (args[0]);
if (dev)
{
grub_dprintf ("luks", "already mounted as crypto%lu\n", dev->id);
return GRUB_ERR_NONE;
}
check_uuid = 1;
check_boot = state[2].set;
search_uuid = args[0];
grub_device_iterate (&grub_geli_scan_device);
search_uuid = NULL;
if (!have_it)
return grub_error (GRUB_ERR_BAD_ARGUMENT, "no such luks found");
return GRUB_ERR_NONE;
}
else if (state[1].set || (argc == 0 && state[2].set))
{
check_uuid = 0;
search_uuid = NULL;
check_boot = state[2].set;
grub_device_iterate (&grub_geli_scan_device);
search_uuid = NULL;
return GRUB_ERR_NONE;
}
else
{
grub_err_t err;
grub_disk_t disk;
grub_cryptodisk_t dev;
check_uuid = 0;
search_uuid = NULL;
check_boot = state[2].set;
disk = grub_disk_open (args[0]);
if (!disk)
return grub_errno;
dev = grub_cryptodisk_get_by_source_disk (disk);
if (dev)
{
grub_dprintf ("luks", "already mounted as luks%lu\n", dev->id);
grub_disk_close (disk);
return GRUB_ERR_NONE;
}
err = grub_geli_scan_device_real (args[0], disk);
grub_disk_close (disk);
return err;
}
}
static grub_extcmd_t cmd;
GRUB_MOD_INIT (geli)
{
cmd = grub_register_extcmd ("gelimount", grub_cmd_gelimount, 0,
N_("SOURCE|-u UUID|-a|-b"),
N_("Mount a GELI device."), options);
}
GRUB_MOD_FINI (geli)
{
grub_unregister_extcmd (cmd);
}
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