5324c335b1
While the AFSplitter code is currently used only by the luks module, upcoming support for luks2 will add a second module that depends on it. To avoid any linker errors when adding the code to both modules because of duplicated symbols, this commit moves it into its own standalone module afsplitter as a preparatory step. Signed-off-by: Patrick Steinhardt <ps@pks.im> Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
95 lines
3.1 KiB
C
95 lines
3.1 KiB
C
/*
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* AFsplitter - Anti forensic information splitter
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* Copyright 2004, Clemens Fruhwirth <clemens@endorphin.org>
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*
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* AFsplitter diffuses information over a large stripe of data,
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* therefor supporting secure data destruction.
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*
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* This program is grub_free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the grub_free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Library General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the grub_free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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*/
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#include <grub/crypto.h>
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#include <grub/dl.h>
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#include <grub/mm.h>
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#include <grub/misc.h>
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GRUB_MOD_LICENSE ("GPLv2+");
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gcry_err_code_t AF_merge (const gcry_md_spec_t * hash, grub_uint8_t * src,
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grub_uint8_t * dst, grub_size_t blocksize,
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grub_size_t blocknumbers);
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static void
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diffuse (const gcry_md_spec_t * hash, grub_uint8_t * src,
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grub_uint8_t * dst, grub_size_t size)
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{
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grub_size_t i;
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grub_uint32_t IV; /* host byte order independend hash IV */
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grub_size_t fullblocks = size / hash->mdlen;
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int padding = size % hash->mdlen;
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grub_uint8_t final[GRUB_CRYPTO_MAX_MDLEN];
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grub_uint8_t temp[sizeof (IV) + GRUB_CRYPTO_MAX_MDLEN];
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/* hash block the whole data set with different IVs to produce
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* more than just a single data block
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*/
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for (i = 0; i < fullblocks; i++)
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{
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IV = grub_cpu_to_be32 (i);
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grub_memcpy (temp, &IV, sizeof (IV));
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grub_memcpy (temp + sizeof (IV), src + hash->mdlen * i, hash->mdlen);
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grub_crypto_hash (hash, dst + hash->mdlen * i, temp,
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sizeof (IV) + hash->mdlen);
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}
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if (padding)
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{
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IV = grub_cpu_to_be32 (i);
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grub_memcpy (temp, &IV, sizeof (IV));
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grub_memcpy (temp + sizeof (IV), src + hash->mdlen * i, padding);
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grub_crypto_hash (hash, final, temp, sizeof (IV) + padding);
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grub_memcpy (dst + hash->mdlen * i, final, padding);
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}
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}
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/**
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* Merges the splitted master key stored on disk into the original key
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*/
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gcry_err_code_t
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AF_merge (const gcry_md_spec_t * hash, grub_uint8_t * src, grub_uint8_t * dst,
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grub_size_t blocksize, grub_size_t blocknumbers)
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{
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grub_size_t i;
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grub_uint8_t *bufblock;
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if (hash->mdlen > GRUB_CRYPTO_MAX_MDLEN || hash->mdlen == 0)
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return GPG_ERR_INV_ARG;
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bufblock = grub_zalloc (blocksize);
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if (bufblock == NULL)
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return GPG_ERR_OUT_OF_MEMORY;
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grub_memset (bufblock, 0, blocksize);
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for (i = 0; i < blocknumbers - 1; i++)
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{
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grub_crypto_xor (bufblock, src + (blocksize * i), bufblock, blocksize);
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diffuse (hash, bufblock, bufblock, blocksize);
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}
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grub_crypto_xor (dst, src + (i * blocksize), bufblock, blocksize);
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grub_free (bufblock);
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return GPG_ERR_NO_ERROR;
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}
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