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grub/grub-core/fs/zfs/zfscrypt.c
Peter Jones 3f05d693d1 malloc: Use overflow checking primitives where we do complex allocations 
This attempts to fix the places where we do the following where
arithmetic_expr may include unvalidated data:

  X = grub_malloc(arithmetic_expr);

It accomplishes this by doing the arithmetic ahead of time using grub_add(),
grub_sub(), grub_mul() and testing for overflow before proceeding.

Among other issues, this fixes:
  - allocation of integer overflow in grub_video_bitmap_create()
    reported by Chris Coulson,
  - allocation of integer overflow in grub_png_decode_image_header()
    reported by Chris Coulson,
  - allocation of integer overflow in grub_squash_read_symlink()
    reported by Chris Coulson,
  - allocation of integer overflow in grub_ext2_read_symlink()
    reported by Chris Coulson,
  - allocation of integer overflow in read_section_as_string()
    reported by Chris Coulson.

Fixes: CVE-2020-14309, CVE-2020-14310, CVE-2020-14311

Signed-off-by: Peter Jones <pjones@redhat.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
2020-07-29 16:55:47 +02:00

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/*
* GRUB -- GRand Unified Bootloader
* Copyright (C) 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/err.h>
#include <grub/file.h>
#include <grub/mm.h>
#include <grub/misc.h>
#include <grub/disk.h>
#include <grub/partition.h>
#include <grub/safemath.h>
#include <grub/dl.h>
#include <grub/types.h>
#include <grub/zfs/zfs.h>
#include <grub/zfs/zio.h>
#include <grub/zfs/dnode.h>
#include <grub/zfs/uberblock_impl.h>
#include <grub/zfs/vdev_impl.h>
#include <grub/zfs/zio_checksum.h>
#include <grub/zfs/zap_impl.h>
#include <grub/zfs/zap_leaf.h>
#include <grub/zfs/zfs_znode.h>
#include <grub/zfs/dmu.h>
#include <grub/zfs/dmu_objset.h>
#include <grub/zfs/sa_impl.h>
#include <grub/zfs/dsl_dir.h>
#include <grub/zfs/dsl_dataset.h>
#include <grub/crypto.h>
#include <grub/extcmd.h>
#include <grub/i18n.h>
GRUB_MOD_LICENSE ("GPLv3+");
/*
Mostly based on following article:
https://blogs.oracle.com/darren/entry/zfs_encryption_what_is_on
*/
enum grub_zfs_algo
{
GRUB_ZFS_ALGO_CCM,
GRUB_ZFS_ALGO_GCM,
};
struct grub_zfs_key
{
grub_uint64_t algo;
grub_uint8_t enc_nonce[13];
grub_uint8_t unused[3];
grub_uint8_t enc_key[48];
grub_uint8_t unknown_purpose_nonce[13];
grub_uint8_t unused2[3];
grub_uint8_t unknown_purpose_key[48];
};
struct grub_zfs_wrap_key
{
struct grub_zfs_wrap_key *next;
grub_size_t keylen;
int is_passphrase;
grub_uint64_t key[0];
};
static struct grub_zfs_wrap_key *zfs_wrap_keys;
grub_err_t
grub_zfs_add_key (grub_uint8_t *key_in,
grub_size_t keylen,
int passphrase)
{
struct grub_zfs_wrap_key *key;
grub_size_t sz;
if (!passphrase && keylen > 32)
keylen = 32;
if (grub_add (sizeof (*key), keylen, &sz))
return GRUB_ERR_OUT_OF_RANGE;
key = grub_malloc (sz);
if (!key)
return grub_errno;
key->is_passphrase = passphrase;
key->keylen = keylen;
grub_memcpy (key->key, key_in, keylen);
key->next = zfs_wrap_keys;
zfs_wrap_keys = key;
return GRUB_ERR_NONE;
}
static gcry_err_code_t
grub_ccm_decrypt (grub_crypto_cipher_handle_t cipher,
grub_uint8_t *out, const grub_uint8_t *in,
grub_size_t psize,
void *mac_out, const void *nonce,
unsigned l, unsigned m)
{
grub_uint8_t iv[16];
grub_uint8_t mul[16];
grub_uint32_t mac[4];
unsigned i, j;
gcry_err_code_t err;
grub_memcpy (iv + 1, nonce, 15 - l);
iv[0] = (l - 1) | (((m-2) / 2) << 3);
for (j = 0; j < l; j++)
iv[15 - j] = psize >> (8 * j);
err = grub_crypto_ecb_encrypt (cipher, mac, iv, 16);
if (err)
return err;
iv[0] = l - 1;
for (i = 0; i < (psize + 15) / 16; i++)
{
grub_size_t csize;
csize = 16;
if (csize > psize - 16 * i)
csize = psize - 16 * i;
for (j = 0; j < l; j++)
iv[15 - j] = (i + 1) >> (8 * j);
err = grub_crypto_ecb_encrypt (cipher, mul, iv, 16);
if (err)
return err;
grub_crypto_xor (out + 16 * i, in + 16 * i, mul, csize);
grub_crypto_xor (mac, mac, out + 16 * i, csize);
err = grub_crypto_ecb_encrypt (cipher, mac, mac, 16);
if (err)
return err;
}
for (j = 0; j < l; j++)
iv[15 - j] = 0;
err = grub_crypto_ecb_encrypt (cipher, mul, iv, 16);
if (err)
return err;
if (mac_out)
grub_crypto_xor (mac_out, mac, mul, m);
return GPG_ERR_NO_ERROR;
}
static void
grub_gcm_mul_x (grub_uint8_t *a)
{
int i;
int c = 0, d = 0;
for (i = 0; i < 16; i++)
{
c = a[i] & 0x1;
a[i] = (a[i] >> 1) | (d << 7);
d = c;
}
if (d)
a[0] ^= 0xe1;
}
static void
grub_gcm_mul (grub_uint8_t *a, const grub_uint8_t *b)
{
grub_uint8_t res[16], bs[16];
int i;
grub_memcpy (bs, b, 16);
grub_memset (res, 0, 16);
for (i = 0; i < 128; i++)
{
if ((a[i / 8] << (i % 8)) & 0x80)
grub_crypto_xor (res, res, bs, 16);
grub_gcm_mul_x (bs);
}
grub_memcpy (a, res, 16);
}
static gcry_err_code_t
grub_gcm_decrypt (grub_crypto_cipher_handle_t cipher,
grub_uint8_t *out, const grub_uint8_t *in,
grub_size_t psize,
void *mac_out, const void *nonce,
unsigned nonce_len, unsigned m)
{
grub_uint8_t iv[16];
grub_uint8_t mul[16];
grub_uint8_t mac[16], h[16], mac_xor[16];
unsigned i, j;
gcry_err_code_t err;
grub_memset (mac, 0, sizeof (mac));
err = grub_crypto_ecb_encrypt (cipher, h, mac, 16);
if (err)
return err;
if (nonce_len == 12)
{
grub_memcpy (iv, nonce, 12);
iv[12] = 0;
iv[13] = 0;
iv[14] = 0;
iv[15] = 1;
}
else
{
grub_memset (iv, 0, sizeof (iv));
grub_memcpy (iv, nonce, nonce_len);
grub_gcm_mul (iv, h);
iv[15] ^= nonce_len * 8;
grub_gcm_mul (iv, h);
}
err = grub_crypto_ecb_encrypt (cipher, mac_xor, iv, 16);
if (err)
return err;
for (i = 0; i < (psize + 15) / 16; i++)
{
grub_size_t csize;
csize = 16;
if (csize > psize - 16 * i)
csize = psize - 16 * i;
for (j = 0; j < 4; j++)
{
iv[15 - j]++;
if (iv[15 - j] != 0)
break;
}
grub_crypto_xor (mac, mac, in + 16 * i, csize);
grub_gcm_mul (mac, h);
err = grub_crypto_ecb_encrypt (cipher, mul, iv, 16);
if (err)
return err;
grub_crypto_xor (out + 16 * i, in + 16 * i, mul, csize);
}
for (j = 0; j < 8; j++)
mac[15 - j] ^= ((((grub_uint64_t) psize) * 8) >> (8 * j));
grub_gcm_mul (mac, h);
if (mac_out)
grub_crypto_xor (mac_out, mac, mac_xor, m);
return GPG_ERR_NO_ERROR;
}
static gcry_err_code_t
algo_decrypt (grub_crypto_cipher_handle_t cipher, grub_uint64_t algo,
grub_uint8_t *out, const grub_uint8_t *in,
grub_size_t psize,
void *mac_out, const void *nonce,
unsigned l, unsigned m)
{
switch (algo)
{
case 0:
return grub_ccm_decrypt (cipher, out, in, psize,
mac_out, nonce, l, m);
case 1:
return grub_gcm_decrypt (cipher, out, in, psize,
mac_out, nonce,
15 - l, m);
default:
return GPG_ERR_CIPHER_ALGO;
}
}
static grub_err_t
grub_zfs_decrypt_real (grub_crypto_cipher_handle_t cipher,
grub_uint64_t algo,
void *nonce,
char *buf, grub_size_t size,
const grub_uint32_t *expected_mac,
grub_zfs_endian_t endian)
{
grub_uint32_t mac[4];
unsigned i;
grub_uint32_t sw[4];
gcry_err_code_t err;
grub_memcpy (sw, nonce, 16);
if (endian != GRUB_ZFS_BIG_ENDIAN)
for (i = 0; i < 4; i++)
sw[i] = grub_swap_bytes32 (sw[i]);
if (!cipher)
return grub_error (GRUB_ERR_ACCESS_DENIED,
N_("no decryption key available"));
err = algo_decrypt (cipher, algo,
(grub_uint8_t *) buf,
(grub_uint8_t *) buf,
size, mac,
sw + 1, 3, 12);
if (err)
return grub_crypto_gcry_error (err);
for (i = 0; i < 3; i++)
if (grub_zfs_to_cpu32 (expected_mac[i], endian)
!= grub_be_to_cpu32 (mac[i]))
return grub_error (GRUB_ERR_BAD_FS, N_("MAC verification failed"));
return GRUB_ERR_NONE;
}
static grub_crypto_cipher_handle_t
grub_zfs_load_key_real (const struct grub_zfs_key *key,
grub_size_t keysize,
grub_uint64_t salt,
grub_uint64_t algo)
{
unsigned keylen;
struct grub_zfs_wrap_key *wrap_key;
grub_crypto_cipher_handle_t ret = NULL;
if (keysize != sizeof (*key))
{
grub_dprintf ("zfs", "Unexpected key size %" PRIuGRUB_SIZE "\n", keysize);
return 0;
}
if (grub_memcmp (key->enc_key + 32, "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0", 16)
== 0)
keylen = 16;
else if (grub_memcmp (key->enc_key + 40, "\0\0\0\0\0\0\0\0", 8) == 0)
keylen = 24;
else
keylen = 32;
for (wrap_key = zfs_wrap_keys; wrap_key; wrap_key = wrap_key->next)
{
grub_crypto_cipher_handle_t cipher;
grub_uint8_t decrypted[32], mac[32], wrap_key_real[32];
gcry_err_code_t err;
cipher = grub_crypto_cipher_open (GRUB_CIPHER_AES);
if (!cipher)
{
grub_errno = GRUB_ERR_NONE;
return 0;
}
grub_memset (wrap_key_real, 0, sizeof (wrap_key_real));
err = 0;
if (!wrap_key->is_passphrase)
grub_memcpy(wrap_key_real, wrap_key->key,
wrap_key->keylen < keylen ? wrap_key->keylen : keylen);
else
err = grub_crypto_pbkdf2 (GRUB_MD_SHA1,
(const grub_uint8_t *) wrap_key->key,
wrap_key->keylen,
(const grub_uint8_t *) &salt, sizeof (salt),
1000, wrap_key_real, keylen);
if (err)
{
grub_errno = GRUB_ERR_NONE;
grub_crypto_cipher_close (cipher);
continue;
}
err = grub_crypto_cipher_set_key (cipher, wrap_key_real,
keylen);
if (err)
{
grub_errno = GRUB_ERR_NONE;
grub_crypto_cipher_close (cipher);
continue;
}
err = algo_decrypt (cipher, algo, decrypted, key->unknown_purpose_key, 32,
mac, key->unknown_purpose_nonce, 2, 16);
if (err || (grub_crypto_memcmp (mac, key->unknown_purpose_key + 32, 16)
!= 0))
{
grub_dprintf ("zfs", "key loading failed\n");
grub_errno = GRUB_ERR_NONE;
grub_crypto_cipher_close (cipher);
continue;
}
err = algo_decrypt (cipher, algo, decrypted, key->enc_key, keylen, mac,
key->enc_nonce, 2, 16);
if (err || grub_crypto_memcmp (mac, key->enc_key + keylen, 16) != 0)
{
grub_dprintf ("zfs", "key loading failed\n");
grub_errno = GRUB_ERR_NONE;
grub_crypto_cipher_close (cipher);
continue;
}
ret = grub_crypto_cipher_open (GRUB_CIPHER_AES);
if (!ret)
{
grub_errno = GRUB_ERR_NONE;
grub_crypto_cipher_close (cipher);
continue;
}
err = grub_crypto_cipher_set_key (ret, decrypted, keylen);
if (err)
{
grub_errno = GRUB_ERR_NONE;
grub_crypto_cipher_close (ret);
grub_crypto_cipher_close (cipher);
continue;
}
grub_crypto_cipher_close (cipher);
return ret;
}
return NULL;
}
static const struct grub_arg_option options[] =
{
{"raw", 'r', 0, N_("Assume input is raw."), 0, 0},
{"hex", 'h', 0, N_("Assume input is hex."), 0, 0},
{"passphrase", 'p', 0, N_("Assume input is passphrase."), 0, 0},
{0, 0, 0, 0, 0, 0}
};
static grub_err_t
grub_cmd_zfs_key (grub_extcmd_context_t ctxt, int argc, char **args)
{
grub_uint8_t buf[1024];
grub_ssize_t real_size;
if (argc > 0)
{
grub_file_t file;
file = grub_file_open (args[0], GRUB_FILE_TYPE_ZFS_ENCRYPTION_KEY);
if (!file)
return grub_errno;
real_size = grub_file_read (file, buf, 1024);
if (real_size < 0)
return grub_errno;
}
else
{
grub_xputs (_("Enter ZFS password: "));
if (!grub_password_get ((char *) buf, 1023))
return grub_errno;
real_size = grub_strlen ((char *) buf);
}
if (ctxt->state[1].set)
{
int i;
grub_err_t err;
for (i = 0; i < real_size / 2; i++)
{
char c1 = grub_tolower (buf[2 * i]) - '0';
char c2 = grub_tolower (buf[2 * i + 1]) - '0';
if (c1 > 9)
c1 += '0' - 'a' + 10;
if (c2 > 9)
c2 += '0' - 'a' + 10;
buf[i] = (c1 << 4) | c2;
}
err = grub_zfs_add_key (buf, real_size / 2, 0);
if (err)
return err;
return GRUB_ERR_NONE;
}
return grub_zfs_add_key (buf, real_size,
ctxt->state[2].set
|| (argc == 0 && !ctxt->state[0].set
&& !ctxt->state[1].set));
}
static grub_extcmd_t cmd_key;
GRUB_MOD_INIT(zfscrypt)
{
grub_zfs_decrypt = grub_zfs_decrypt_real;
grub_zfs_load_key = grub_zfs_load_key_real;
cmd_key = grub_register_extcmd ("zfskey", grub_cmd_zfs_key, 0,
N_("[-h|-p|-r] [FILE]"),
N_("Import ZFS wrapping key stored in FILE."),
options);
}
GRUB_MOD_FINI(zfscrypt)
{
grub_zfs_decrypt = 0;
grub_zfs_load_key = 0;
grub_unregister_extcmd (cmd_key);
}
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