FreeBSD/Linux Kernel Cross Reference
sys/fs/ext2fs/ext2_hash.c

     /*-
      * SPDX-License-Identifier: (BSD-2-Clause-FreeBSD AND RSA-MD)
      *
      * 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.
     *
     * $FreeBSD: releng/12.0/sys/fs/ext2fs/ext2_hash.c 333584 2018-05-13 19:19:10Z fsu $
     */
    
    /*
     * 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.
     */
    
    #include <sys/param.h>
    #include <sys/systm.h>
    #include <sys/conf.h>
    #include <sys/vnode.h>
    #include <sys/stat.h>
    #include <sys/mount.h>
    
    #include <fs/ext2fs/ext2fs.h>
    #include <fs/ext2fs/fs.h>
    #include <fs/ext2fs/htree.h>
    #include <fs/ext2fs/inode.h>
    #include <fs/ext2fs/ext2_mount.h>
    #include <fs/ext2fs/ext2_extern.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 = (u_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, int slen, uint32_t *dst, int dlen,
       int unsigned_char)
   {
           uint32_t padding = slen | (slen << 8) | (slen << 16) | (slen << 24);
           uint32_t buf_val;
           const unsigned char *ubuf = (const unsigned char *)src;
           const signed char *sbuf = (const signed char *)src;
           int len, i;
           int buf_byte;
   
           if (slen > dlen)
                   len = dlen;
           else
                   len = slen;
   
           buf_val = padding;
   
           for (i = 0; i < len; i++) {
                   if (unsigned_char)
                           buf_byte = (u_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,
       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;
                   /* FALLTHROUGH */
           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;
                   /* FALLTHROUGH */
           case EXT2_HTREE_LEGACY:
                   major = ext2_legacy_hash(name, len, unsigned_char);
                   break;
           case EXT2_HTREE_HALF_MD4_UNSIGNED:
                   unsigned_char = 1;
                   /* FALLTHROUGH */
           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 (0);
   
   error:
           *hash_major = 0;
           if (hash_minor)
                   *hash_minor = 0;
           return (-1);
   }

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