// SPDX-License-Identifier: GPL-2.0
/*
* linux/fs/ext4/hash.c
*
* Copyright (C) 2002 by Theodore Ts'o
*/
#include <linux/fs.h>
#include <linux/compiler.h>
#include <linux/bitops.h>
#include "ext4.h"
#define DELTA 0x9E3779B9
static void TEA_transform(__u32 buf[4], __u32 const in[])
{
__u32 sum = 0;
__u32 b0 = buf[0], b1 = buf[1];
__u32 a = in[0], b = in[1], c = in[2], d = in[3];
int n = 16;
do {
sum += DELTA;
b0 += ((b1 << 4)+a) ^ (b1+sum) ^ ((b1 >> 5)+b);
b1 += ((b0 << 4)+c) ^ (b0+sum) ^ ((b0 >> 5)+d);
} while (--n);
buf[0] += b0;
buf[1] += b1;
}
/* F, G and H are basic MD4 functions: selection, majority, parity */
#define F(x, y, z) ((z) ^ ((x) & ((y) ^ (z))))
#define G(x, y, z) (((x) & (y)) + (((x) ^ (y)) & (z)))
#define H(x, y, z) ((x) ^ (y) ^ (z))
/*
* The generic round function. The application is so specific that
* we don't bother protecting all the arguments with parens, as is generally
* good macro practice, in favor of extra legibility.
* Rotation is separate from addition to prevent recomputation
*/
#define ROUND(f, a, b, c, d, x, s) \
(a += f(b, c, d) + x, a = rol32(a, s))
#define K1 0
#define K2 013240474631UL
#define K3 015666365641UL
/*
* Basic cut-down MD4 transform. Returns only 32 bits of result.
*/
static __u32 half_md4_transform(__u32 buf[4], __u32 const in[8])
{
__u32 a = buf[0], b = buf[1], c = buf[2], d = buf[3];
/* Round 1 */
ROUND(F, a, b, c, d, in[0] + K1, 3);
ROUND(F, d, a, b, c, in[1] + K1, 7);
ROUND(F, c, d, a, b, in[2] + K1, 11);
ROUND(F, b, c, d, a, in[3] + K1, 19);
ROUND(F, a, b, c, d, in[4] + K1, 3);
ROUND(F, d, a, b, c, in[5] + K1, 7);
ROUND(F, c, d, a, b, in[6] + K1, 11);
ROUND(F, b, c, d, a, in[7] + K1, 19);
/* Round 2 */
ROUND(G, a, b, c, d, in[1] + K2, 3);
ROUND(G, d, a, b, c, in[3] + K2, 5);
ROUND(G, c, d, a, b, in[5] + K2, 9);
ROUND(G, b, c, d, a, in[7] + K2, 13);
ROUND(G, a, b, c, d, in[0] + K2, 3);
ROUND(G, d, a, b, c, in[2] + K2, 5);
ROUND(G, c, d, a, b, in[4] + K2, 9);
ROUND(G, b, c, d, a, in[6] + K2, 13);
/* Round 3 */
ROUND(H, a, b, c, d, in[3] + K3, 3);
ROUND(H, d, a, b, c, in[7] + K3, 9);
ROUND(H, c, d, a, b, in[2] + K3, 11);
ROUND(H, b, c, d, a, in[6] + K3, 15);
ROUND(H, a, b, c, d, in[1] + K3, 3);
ROUND(H, d, a, b, c, in[5] + K3, 9);
ROUND(H, c, d, a, b, in[0] + K3, 11);
ROUND(H, b, c, d, a, in[4] + K3, 15);
buf[0] += a;
buf[1] += b;
buf[2] += c;
buf[3] += d;
return buf[1]; /* "most hashed" word */
}
#undef ROUND
#undef K1
#undef K2
#undef K3
#undef F
#undef G
#undef H
/* The old legacy hash */
static __u32 dx_hack_hash_unsigned(const char *name, int len)
{
__u32 hash, hash0 = 0x12a3fe2d, hash1 = 0x37abe8f9;
const unsigned char *ucp = (const unsigned char *) name;
while (len--) {
hash = hash1 + (hash0 ^ (((int) *ucp++) * 7152373));
if (hash & 0x80000000)
hash -= 0x7fffffff;
hash1 = hash0;
hash0 = hash;
}
return hash0 << 1;
}
static __u32 dx_hack_hash_signed(const char *name, int len)
{
__u32 hash, hash0 = 0x12a3fe2d, hash1 = 0x37abe8f9;
const signed char *scp = (const signed char *) name;
while (len--) {
hash = hash1 + (hash0 ^ (((int) *scp++) * 7152373));
if (hash & 0x80000000)
hash -= 0x7fffffff;
hash1 = hash0;
hash0 = hash;
}
return hash0 << 1;
}
static void str2hashbuf_signed(const char *msg, int len, __u32 *buf, int num)
{
__u32 pad, val;
int i;
const signed char *scp = (const signed char *) msg;
pad = (__u32)len | ((__u32)len << 8);
pad |= pad << 16;
val = pad;
if (len > num*4)
len = num * 4;
for (i = 0; i < len; i++) {
val = ((int) scp[i]) + (val << 8);
if ((i % 4) == 3) {
*buf++ = val;
val = pad;
num--;
}
}
if (--num >= 0)
*buf++ = val;
while (--num >= 0)
*buf++ = pad;
}
static void str2hashbuf_unsigned(const char *msg, int len, __u32 *buf, int num)
{
__u32 pad, val;
int i;
const unsigned char *ucp = (const unsigned char *) msg;
pad = (__u32)len | ((__u32)len << 8);
pad |= pad << 16;
val = pad;
if (len > num*4)
len = num * 4;
for (i = 0; i < len; i++) {
val = ((int) ucp[i]) + (val << 8);
if ((i % 4) == 3) {
*buf++ = val;
val = pad;
num--;
}
}
if (--num >= 0)
*buf++ = val;
while (--num >= 0)
*buf++ = pad;
}
/*
* Returns the hash of a filename. If len is 0 and name is NULL, then
* this function can be used to test whether or not a hash version is
* supported.
*
* The seed is an 4 longword (32 bits) "secret" which can be used to
* uniquify a hash. If the seed is all zero's, then some default seed
* may be used.
*
* A particular hash version specifies whether or not the seed is
* represented, and whether or not the returned hash is 32 bits or 64
* bits. 32 bit hashes will return 0 for the minor hash.
*/
int ext4fs_dirhash(const char *name, int len, struct dx_hash_info *hinfo)
{
__u32 hash;
__u32 minor_hash = 0;
const char *p;
int i;
__u32 in[8], buf[4];
void (*str2hashbuf)(const char *, int, __u32 *, int) =
str2hashbuf_signed;
/* Initialize the default seed for the hash checksum functions */
buf[0] = 0x67452301;
buf[1] = 0xefcdab89;
buf[2] = 0x98badcfe;
buf[3] = 0x10325476;
/* Check to see if the seed is all zero's */
if (hinfo->seed) {
for (i = 0; i < 4; i++) {
if (hinfo->seed[i]) {
memcpy(buf, hinfo->seed, sizeof(buf));
break;
}
}
}
switch (hinfo->hash_version) {
case DX_HASH_LEGACY_UNSIGNED:
hash = dx_hack_hash_unsigned(name, len);
break;
case DX_HASH_LEGACY:
hash = dx_hack_hash_signed(name, len);
break;
case DX_HASH_HALF_MD4_UNSIGNED:
str2hashbuf = str2hashbuf_unsigned;
case DX_HASH_HALF_MD4:
p = name;
while (len > 0) {
(*str2hashbuf)(p, len, in, 8);
half_md4_transform(buf, in);
len -= 32;
p += 32;
}
minor_hash = buf[2];
hash = buf[1];
break;
case DX_HASH_TEA_UNSIGNED:
str2hashbuf = str2hashbuf_unsigned;
case DX_HASH_TEA:
p = name;
while (len > 0) {
(*str2hashbuf)(p, len, in, 4);
TEA_transform(buf, in);
len -= 16;
p += 16;
}
hash = buf[0];
minor_hash = buf[1];
break;
default:
hinfo->hash = 0;
return -1;
}
hash = hash & ~1;
if (hash == (EXT4_HTREE_EOF_32BIT << 1))
hash = (EXT4_HTREE_EOF_32BIT - 1) << 1;
hinfo->hash = hash;
hinfo->minor_hash = minor_hash;
return 0;
}
