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grub/grub-core/disk/luks.c
Andrei Borzenkov ea44693fc8 grub-core/disk/luks.c: fix use after free and memory leaks 
configure_ciphers:

- several memory leaks where allocated ciphers were not freed. CID: 73813,
73710

- use after free. It is probably quite innocent as grub is single threaded,
but could potentially be a problem with memory allocator debugger turned on.
CID: 73730

luks_recover_key:

- memory leak. CID: 73854
2014-11-28 21:12:00 +03:00

485 lines
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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/>.
*/
#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/partition.h>
#include <grub/i18n.h>
GRUB_MOD_LICENSE ("GPLv3+");
#define MAX_PASSPHRASE 256
#define LUKS_KEY_ENABLED 0x00AC71F3
/* On disk LUKS header */
struct grub_luks_phdr
{
grub_uint8_t magic[6];
#define LUKS_MAGIC "LUKS\xBA\xBE"
grub_uint16_t version;
char cipherName[32];
char cipherMode[32];
char hashSpec[32];
grub_uint32_t payloadOffset;
grub_uint32_t keyBytes;
grub_uint8_t mkDigest[20];
grub_uint8_t mkDigestSalt[32];
grub_uint32_t mkDigestIterations;
char uuid[40];
struct
{
grub_uint32_t active;
grub_uint32_t passwordIterations;
grub_uint8_t passwordSalt[32];
grub_uint32_t keyMaterialOffset;
grub_uint32_t stripes;
} keyblock[8];
} GRUB_PACKED;
typedef struct grub_luks_phdr *grub_luks_phdr_t;
gcry_err_code_t AF_merge (const gcry_md_spec_t * hash, grub_uint8_t * src,
grub_uint8_t * dst, grub_size_t blocksize,
grub_size_t blocknumbers);
static grub_cryptodisk_t
configure_ciphers (grub_disk_t disk, const char *check_uuid,
int check_boot)
{
grub_cryptodisk_t newdev;
const char *iptr;
struct grub_luks_phdr header;
char *optr;
char uuid[sizeof (header.uuid) + 1];
char ciphername[sizeof (header.cipherName) + 1];
char ciphermode[sizeof (header.cipherMode) + 1];
char *cipheriv = NULL;
char hashspec[sizeof (header.hashSpec) + 1];
grub_crypto_cipher_handle_t cipher = NULL, secondary_cipher = NULL;
grub_crypto_cipher_handle_t essiv_cipher = NULL;
const gcry_md_spec_t *hash = NULL, *essiv_hash = NULL;
const struct gcry_cipher_spec *ciph;
grub_cryptodisk_mode_t mode;
grub_cryptodisk_mode_iv_t mode_iv = GRUB_CRYPTODISK_MODE_IV_PLAIN64;
int benbi_log = 0;
grub_err_t err;
if (check_boot)
return NULL;
/* Read the LUKS header. */
err = grub_disk_read (disk, 0, 0, sizeof (header), &header);
if (err)
{
if (err == GRUB_ERR_OUT_OF_RANGE)
grub_errno = GRUB_ERR_NONE;
return NULL;
}
/* Look for LUKS magic sequence. */
if (grub_memcmp (header.magic, LUKS_MAGIC, sizeof (header.magic))
|| grub_be_to_cpu16 (header.version) != 1)
return NULL;
optr = uuid;
for (iptr = header.uuid; iptr < &header.uuid[ARRAY_SIZE (header.uuid)];
iptr++)
{
if (*iptr != '-')
*optr++ = *iptr;
}
*optr = 0;
if (check_uuid && grub_strcasecmp (check_uuid, uuid) != 0)
{
grub_dprintf ("luks", "%s != %s\n", uuid, check_uuid);
return NULL;
}
/* Make sure that strings are null terminated. */
grub_memcpy (ciphername, header.cipherName, sizeof (header.cipherName));
ciphername[sizeof (header.cipherName)] = 0;
grub_memcpy (ciphermode, header.cipherMode, sizeof (header.cipherMode));
ciphermode[sizeof (header.cipherMode)] = 0;
grub_memcpy (hashspec, header.hashSpec, sizeof (header.hashSpec));
hashspec[sizeof (header.hashSpec)] = 0;
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_be_to_cpu32 (header.keyBytes) > 1024)
{
grub_error (GRUB_ERR_BAD_ARGUMENT, "invalid keysize %d",
grub_be_to_cpu32 (header.keyBytes));
grub_crypto_cipher_close (cipher);
return NULL;
}
/* Configure the cipher mode. */
if (grub_strcmp (ciphermode, "ecb") == 0)
{
mode = GRUB_CRYPTODISK_MODE_ECB;
mode_iv = GRUB_CRYPTODISK_MODE_IV_PLAIN;
cipheriv = NULL;
}
else if (grub_strcmp (ciphermode, "plain") == 0)
{
mode = GRUB_CRYPTODISK_MODE_CBC;
mode_iv = GRUB_CRYPTODISK_MODE_IV_PLAIN;
cipheriv = NULL;
}
else if (grub_memcmp (ciphermode, "cbc-", sizeof ("cbc-") - 1) == 0)
{
mode = GRUB_CRYPTODISK_MODE_CBC;
cipheriv = ciphermode + sizeof ("cbc-") - 1;
}
else if (grub_memcmp (ciphermode, "pcbc-", sizeof ("pcbc-") - 1) == 0)
{
mode = GRUB_CRYPTODISK_MODE_PCBC;
cipheriv = ciphermode + sizeof ("pcbc-") - 1;
}
else if (grub_memcmp (ciphermode, "xts-", sizeof ("xts-") - 1) == 0)
{
mode = GRUB_CRYPTODISK_MODE_XTS;
cipheriv = ciphermode + sizeof ("xts-") - 1;
secondary_cipher = grub_crypto_cipher_open (ciph);
if (!secondary_cipher)
{
grub_crypto_cipher_close (cipher);
return NULL;
}
if (cipher->cipher->blocksize != GRUB_CRYPTODISK_GF_BYTES)
{
grub_error (GRUB_ERR_BAD_ARGUMENT, "Unsupported XTS block size: %d",
cipher->cipher->blocksize);
grub_crypto_cipher_close (cipher);
grub_crypto_cipher_close (secondary_cipher);
return NULL;
}
if (secondary_cipher->cipher->blocksize != GRUB_CRYPTODISK_GF_BYTES)
{
grub_crypto_cipher_close (cipher);
grub_error (GRUB_ERR_BAD_ARGUMENT, "Unsupported XTS block size: %d",
secondary_cipher->cipher->blocksize);
grub_crypto_cipher_close (secondary_cipher);
return NULL;
}
}
else if (grub_memcmp (ciphermode, "lrw-", sizeof ("lrw-") - 1) == 0)
{
mode = GRUB_CRYPTODISK_MODE_LRW;
cipheriv = ciphermode + sizeof ("lrw-") - 1;
if (cipher->cipher->blocksize != GRUB_CRYPTODISK_GF_BYTES)
{
grub_error (GRUB_ERR_BAD_ARGUMENT, "Unsupported LRW block size: %d",
cipher->cipher->blocksize);
grub_crypto_cipher_close (cipher);
return NULL;
}
}
else
{
grub_crypto_cipher_close (cipher);
grub_error (GRUB_ERR_BAD_ARGUMENT, "Unknown cipher mode: %s",
ciphermode);
return NULL;
}
if (cipheriv == NULL);
else if (grub_memcmp (cipheriv, "plain", sizeof ("plain") - 1) == 0)
mode_iv = GRUB_CRYPTODISK_MODE_IV_PLAIN;
else if (grub_memcmp (cipheriv, "plain64", sizeof ("plain64") - 1) == 0)
mode_iv = GRUB_CRYPTODISK_MODE_IV_PLAIN64;
else if (grub_memcmp (cipheriv, "benbi", sizeof ("benbi") - 1) == 0)
{
if (cipher->cipher->blocksize & (cipher->cipher->blocksize - 1)
|| cipher->cipher->blocksize == 0)
grub_error (GRUB_ERR_BAD_ARGUMENT, "Unsupported benbi blocksize: %d",
cipher->cipher->blocksize);
/* FIXME should we return an error here? */
for (benbi_log = 0;
(cipher->cipher->blocksize << benbi_log) < GRUB_DISK_SECTOR_SIZE;
benbi_log++);
mode_iv = GRUB_CRYPTODISK_MODE_IV_BENBI;
}
else if (grub_memcmp (cipheriv, "null", sizeof ("null") - 1) == 0)
mode_iv = GRUB_CRYPTODISK_MODE_IV_NULL;
else if (grub_memcmp (cipheriv, "essiv:", sizeof ("essiv:") - 1) == 0)
{
char *hash_str = cipheriv + 6;
mode_iv = GRUB_CRYPTODISK_MODE_IV_ESSIV;
/* Configure the hash and cipher used for ESSIV. */
essiv_hash = grub_crypto_lookup_md_by_name (hash_str);
if (!essiv_hash)
{
grub_crypto_cipher_close (cipher);
grub_crypto_cipher_close (secondary_cipher);
grub_error (GRUB_ERR_FILE_NOT_FOUND,
"Couldn't load %s hash", hash_str);
return NULL;
}
essiv_cipher = grub_crypto_cipher_open (ciph);
if (!essiv_cipher)
{
grub_crypto_cipher_close (cipher);
grub_crypto_cipher_close (secondary_cipher);
return NULL;
}
}
else
{
grub_crypto_cipher_close (cipher);
grub_crypto_cipher_close (secondary_cipher);
grub_error (GRUB_ERR_BAD_ARGUMENT, "Unknown IV mode: %s",
cipheriv);
return NULL;
}
/* Configure the hash used for the AF splitter and HMAC. */
hash = grub_crypto_lookup_md_by_name (hashspec);
if (!hash)
{
grub_crypto_cipher_close (cipher);
grub_crypto_cipher_close (essiv_cipher);
grub_crypto_cipher_close (secondary_cipher);
grub_error (GRUB_ERR_FILE_NOT_FOUND, "Couldn't load %s hash",
hashspec);
return NULL;
}
newdev = grub_zalloc (sizeof (struct grub_cryptodisk));
if (!newdev)
{
grub_crypto_cipher_close (cipher);
grub_crypto_cipher_close (essiv_cipher);
grub_crypto_cipher_close (secondary_cipher);
return NULL;
}
newdev->cipher = cipher;
newdev->offset = grub_be_to_cpu32 (header.payloadOffset);
newdev->source_disk = NULL;
newdev->benbi_log = benbi_log;
newdev->mode = mode;
newdev->mode_iv = mode_iv;
newdev->secondary_cipher = secondary_cipher;
newdev->essiv_cipher = essiv_cipher;
newdev->essiv_hash = essiv_hash;
newdev->hash = hash;
newdev->log_sector_size = 9;
newdev->total_length = grub_disk_get_size (disk) - newdev->offset;
grub_memcpy (newdev->uuid, uuid, sizeof (newdev->uuid));
newdev->modname = "luks";
COMPILE_TIME_ASSERT (sizeof (newdev->uuid) >= sizeof (uuid));
return newdev;
}
static grub_err_t
luks_recover_key (grub_disk_t source,
grub_cryptodisk_t dev)
{
struct grub_luks_phdr header;
grub_size_t keysize;
grub_uint8_t *split_key = NULL;
char passphrase[MAX_PASSPHRASE] = "";
grub_uint8_t candidate_digest[sizeof (header.mkDigest)];
unsigned i;
grub_size_t length;
grub_err_t err;
grub_size_t max_stripes = 1;
char *tmp;
err = grub_disk_read (source, 0, 0, sizeof (header), &header);
if (err)
return err;
grub_puts_ (N_("Attempting to decrypt master key..."));
keysize = grub_be_to_cpu32 (header.keyBytes);
if (keysize > GRUB_CRYPTODISK_MAX_KEYLEN)
return grub_error (GRUB_ERR_BAD_FS, "key is too long");
for (i = 0; i < ARRAY_SIZE (header.keyblock); i++)
if (grub_be_to_cpu32 (header.keyblock[i].active) == LUKS_KEY_ENABLED
&& grub_be_to_cpu32 (header.keyblock[i].stripes) > max_stripes)
max_stripes = grub_be_to_cpu32 (header.keyblock[i].stripes);
split_key = grub_malloc (keysize * max_stripes);
if (!split_key)
return grub_errno;
/* Get the passphrase from the user. */
tmp = NULL;
if (source->partition)
tmp = grub_partition_get_name (source->partition);
grub_printf_ (N_("Enter passphrase for %s%s%s (%s): "), source->name,
source->partition ? "," : "", tmp ? : "",
dev->uuid);
grub_free (tmp);
if (!grub_password_get (passphrase, MAX_PASSPHRASE))
{
grub_free (split_key);
return grub_error (GRUB_ERR_BAD_ARGUMENT, "Passphrase not supplied");
}
/* Try to recover master key from each active keyslot. */
for (i = 0; i < ARRAY_SIZE (header.keyblock); i++)
{
gcry_err_code_t gcry_err;
grub_uint8_t candidate_key[GRUB_CRYPTODISK_MAX_KEYLEN];
grub_uint8_t digest[GRUB_CRYPTODISK_MAX_KEYLEN];
/* Check if keyslot is enabled. */
if (grub_be_to_cpu32 (header.keyblock[i].active) != LUKS_KEY_ENABLED)
continue;
grub_dprintf ("luks", "Trying keyslot %d\n", i);
/* Calculate the PBKDF2 of the user supplied passphrase. */
gcry_err = grub_crypto_pbkdf2 (dev->hash, (grub_uint8_t *) passphrase,
grub_strlen (passphrase),
header.keyblock[i].passwordSalt,
sizeof (header.keyblock[i].passwordSalt),
grub_be_to_cpu32 (header.keyblock[i].
passwordIterations),
digest, keysize);
if (gcry_err)
{
grub_free (split_key);
return grub_crypto_gcry_error (gcry_err);
}
grub_dprintf ("luks", "PBKDF2 done\n");
gcry_err = grub_cryptodisk_setkey (dev, digest, keysize);
if (gcry_err)
{
grub_free (split_key);
return grub_crypto_gcry_error (gcry_err);
}
length = (keysize * grub_be_to_cpu32 (header.keyblock[i].stripes));
/* Read and decrypt the key material from the disk. */
err = grub_disk_read (source,
grub_be_to_cpu32 (header.keyblock
[i].keyMaterialOffset), 0,
length, split_key);
if (err)
{
grub_free (split_key);
return err;
}
gcry_err = grub_cryptodisk_decrypt (dev, split_key, length, 0);
if (gcry_err)
{
grub_free (split_key);
return grub_crypto_gcry_error (gcry_err);
}
/* Merge the decrypted key material to get the candidate master key. */
gcry_err = AF_merge (dev->hash, split_key, candidate_key, keysize,
grub_be_to_cpu32 (header.keyblock[i].stripes));
if (gcry_err)
{
grub_free (split_key);
return grub_crypto_gcry_error (gcry_err);
}
grub_dprintf ("luks", "candidate key recovered\n");
/* Calculate the PBKDF2 of the candidate master key. */
gcry_err = grub_crypto_pbkdf2 (dev->hash, candidate_key,
grub_be_to_cpu32 (header.keyBytes),
header.mkDigestSalt,
sizeof (header.mkDigestSalt),
grub_be_to_cpu32
(header.mkDigestIterations),
candidate_digest,
sizeof (candidate_digest));
if (gcry_err)
{
grub_free (split_key);
return grub_crypto_gcry_error (gcry_err);
}
/* Compare the calculated PBKDF2 to the digest stored
in the header to see if it's correct. */
if (grub_memcmp (candidate_digest, header.mkDigest,
sizeof (header.mkDigest)) != 0)
{
grub_dprintf ("luks", "bad digest\n");
continue;
}
/* TRANSLATORS: It's a cryptographic key slot: one element of an array
where each element is either empty or holds a key. */
grub_printf_ (N_("Slot %d opened\n"), i);
/* Set the master key. */
gcry_err = grub_cryptodisk_setkey (dev, candidate_key, keysize);
if (gcry_err)
{
grub_free (split_key);
return grub_crypto_gcry_error (gcry_err);
}
grub_free (split_key);
return GRUB_ERR_NONE;
}
grub_free (split_key);
return GRUB_ACCESS_DENIED;
}
struct grub_cryptodisk_dev luks_crypto = {
.scan = configure_ciphers,
.recover_key = luks_recover_key
};
GRUB_MOD_INIT (luks)
{
COMPILE_TIME_ASSERT (sizeof (((struct grub_luks_phdr *) 0)->uuid)
< GRUB_CRYPTODISK_MAX_UUID_LENGTH);
grub_cryptodisk_dev_register (&luks_crypto);
}
GRUB_MOD_FINI (luks)
{
grub_cryptodisk_dev_unregister (&luks_crypto);
}
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