ref: e6435a48f54c9f84eec99bb5f56c327ae59b9c1f
dir: /src/ext4_hash.c/
/* * Copyright (c) 2013 Grzegorz Kostka (kostka.grzegorz@gmail.com) * * FreeBSD: * Copyright (c) 2010, 2013 Zheng Liu <lz@freebsd.org> * Copyright (c) 2012, Vyacheslav Matyushin * 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 REGENTS 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 REGENTS 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. * */ /* * The following notice applies to the code in ext2_half_md4(): * * Copyright (C) 1990-2, RSA Data Security, Inc. All rights reserved. * * License to copy and use this software is granted provided that it * is identified as the "RSA Data Security, Inc. MD4 Message-Digest * Algorithm" in all material mentioning or referencing this software * or this function. * * License is also granted to make and use derivative works provided * that such works are identified as "derived from the RSA Data * Security, Inc. MD4 Message-Digest Algorithm" in all material * mentioning or referencing the derived work. * * RSA Data Security, Inc. makes no representations concerning either * the merchantability of this software or the suitability of this * software for any particular purpose. It is provided "as is" * without express or implied warranty of any kind. * * These notices must be retained in any copies of any part of this * documentation and/or software. */ /** @addtogroup lwext4 * @{ */ /** * @file ext4_hash.c * @brief Directory indexing hash functions. */ #include "ext4_config.h" #include "ext4_types.h" #include "ext4_misc.h" #include "ext4_errno.h" #include "ext4_debug.h" #include <string.h> /* F, G, and H are MD4 functions */ #define F(x, y, z) (((x) & (y)) | ((~x) & (z))) #define G(x, y, z) (((x) & (y)) | ((x) & (z)) | ((y) & (z))) #define H(x, y, z) ((x) ^ (y) ^ (z)) /* ROTATE_LEFT rotates x left n bits */ #define ROTATE_LEFT(x, n) (((x) << (n)) | ((x) >> (32 - (n)))) /* * FF, GG, and HH are transformations for rounds 1, 2, and 3. * Rotation is separated from addition to prevent recomputation. */ #define FF(a, b, c, d, x, s) \ { \ (a) += F((b), (c), (d)) + (x); \ (a) = ROTATE_LEFT((a), (s)); \ \ } #define GG(a, b, c, d, x, s) \ { \ (a) += G((b), (c), (d)) + (x) + (uint32_t)0x5A827999; \ (a) = ROTATE_LEFT((a), (s)); \ \ } #define HH(a, b, c, d, x, s) \ { \ (a) += H((b), (c), (d)) + (x) + (uint32_t)0x6ED9EBA1; \ (a) = ROTATE_LEFT((a), (s)); \ \ } /* * MD4 basic transformation. It transforms state based on block. * * This is a half md4 algorithm since Linux uses this algorithm for dir * index. This function is derived from the RSA Data Security, Inc. MD4 * Message-Digest Algorithm and was modified as necessary. * * The return value of this function is uint32_t in Linux, but actually we don't * need to check this value, so in our version this function doesn't return any * value. */ static void ext2_half_md4(uint32_t hash[4], uint32_t data[8]) { uint32_t a = hash[0], b = hash[1], c = hash[2], d = hash[3]; /* Round 1 */ FF(a, b, c, d, data[0], 3); FF(d, a, b, c, data[1], 7); FF(c, d, a, b, data[2], 11); FF(b, c, d, a, data[3], 19); FF(a, b, c, d, data[4], 3); FF(d, a, b, c, data[5], 7); FF(c, d, a, b, data[6], 11); FF(b, c, d, a, data[7], 19); /* Round 2 */ GG(a, b, c, d, data[1], 3); GG(d, a, b, c, data[3], 5); GG(c, d, a, b, data[5], 9); GG(b, c, d, a, data[7], 13); GG(a, b, c, d, data[0], 3); GG(d, a, b, c, data[2], 5); GG(c, d, a, b, data[4], 9); GG(b, c, d, a, data[6], 13); /* Round 3 */ HH(a, b, c, d, data[3], 3); HH(d, a, b, c, data[7], 9); HH(c, d, a, b, data[2], 11); HH(b, c, d, a, data[6], 15); HH(a, b, c, d, data[1], 3); HH(d, a, b, c, data[5], 9); HH(c, d, a, b, data[0], 11); HH(b, c, d, a, data[4], 15); hash[0] += a; hash[1] += b; hash[2] += c; hash[3] += d; } /* * Tiny Encryption Algorithm. */ static void ext2_tea(uint32_t hash[4], uint32_t data[8]) { uint32_t tea_delta = 0x9E3779B9; uint32_t sum; uint32_t x = hash[0], y = hash[1]; int n = 16; int i = 1; while (n-- > 0) { sum = i * tea_delta; x += ((y << 4) + data[0]) ^ (y + sum) ^ ((y >> 5) + data[1]); y += ((x << 4) + data[2]) ^ (x + sum) ^ ((x >> 5) + data[3]); i++; } hash[0] += x; hash[1] += y; } static uint32_t ext2_legacy_hash(const char *name, int len, int unsigned_char) { uint32_t h0, h1 = 0x12A3FE2D, h2 = 0x37ABE8F9; uint32_t multi = 0x6D22F5; const unsigned char *uname = (const unsigned char *)name; const signed char *sname = (const signed char *)name; int val, i; for (i = 0; i < len; i++) { if (unsigned_char) val = (unsigned int)*uname++; else val = (int)*sname++; h0 = h2 + (h1 ^ (val * multi)); if (h0 & 0x80000000) h0 -= 0x7FFFFFFF; h2 = h1; h1 = h0; } return (h1 << 1); } static void ext2_prep_hashbuf(const char *src, uint32_t slen, uint32_t *dst, int dlen, int unsigned_char) { uint32_t padding = slen | (slen << 8) | (slen << 16) | (slen << 24); uint32_t buf_val; int len, i; int buf_byte; const unsigned char *ubuf = (const unsigned char *)src; const signed char *sbuf = (const signed char *)src; if (slen > (uint32_t)dlen) len = dlen; else len = slen; buf_val = padding; for (i = 0; i < len; i++) { if (unsigned_char) buf_byte = (unsigned int)ubuf[i]; else buf_byte = (int)sbuf[i]; if ((i % 4) == 0) buf_val = padding; buf_val <<= 8; buf_val += buf_byte; if ((i % 4) == 3) { *dst++ = buf_val; dlen -= sizeof(uint32_t); buf_val = padding; } } dlen -= sizeof(uint32_t); if (dlen >= 0) *dst++ = buf_val; dlen -= sizeof(uint32_t); while (dlen >= 0) { *dst++ = padding; dlen -= sizeof(uint32_t); } } int ext2_htree_hash(const char *name, int len, const uint32_t *hash_seed, int hash_version, uint32_t *hash_major, uint32_t *hash_minor) { uint32_t hash[4]; uint32_t data[8]; uint32_t major = 0, minor = 0; int unsigned_char = 0; if (!name || !hash_major) return (-1); if (len < 1 || len > 255) goto error; hash[0] = 0x67452301; hash[1] = 0xEFCDAB89; hash[2] = 0x98BADCFE; hash[3] = 0x10325476; if (hash_seed) memcpy(hash, hash_seed, sizeof(hash)); switch (hash_version) { case EXT2_HTREE_TEA_UNSIGNED: unsigned_char = 1; case EXT2_HTREE_TEA: while (len > 0) { ext2_prep_hashbuf(name, len, data, 16, unsigned_char); ext2_tea(hash, data); len -= 16; name += 16; } major = hash[0]; minor = hash[1]; break; case EXT2_HTREE_LEGACY_UNSIGNED: unsigned_char = 1; case EXT2_HTREE_LEGACY: major = ext2_legacy_hash(name, len, unsigned_char); break; case EXT2_HTREE_HALF_MD4_UNSIGNED: unsigned_char = 1; case EXT2_HTREE_HALF_MD4: while (len > 0) { ext2_prep_hashbuf(name, len, data, 32, unsigned_char); ext2_half_md4(hash, data); len -= 32; name += 32; } major = hash[1]; minor = hash[2]; break; default: goto error; } major &= ~1; if (major == (EXT2_HTREE_EOF << 1)) major = (EXT2_HTREE_EOF - 1) << 1; *hash_major = major; if (hash_minor) *hash_minor = minor; return EOK; error: *hash_major = 0; if (hash_minor) *hash_minor = 0; return ENOTSUP; } /** * @} */