[linux-2.6-block.git] / fs / ext4 / hash.c

// 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;
}
Commit	Line	Data
f5166768	1	// SPDX-License-Identifier: GPL-2.0
ac27a0ec	2	/*
617ba13b	3	* linux/fs/ext4/hash.c
ac27a0ec DK	4	*
ac27a0ec DK	5	* Copyright (C) 2002 by Theodore Ts'o
ac27a0ec DK	6	*/
	7
	8	#include <linux/fs.h>
1c83a9aa JD	9	#include <linux/compiler.h>
1c83a9aa JD	10	#include <linux/bitops.h>
3dcf5451	11	#include "ext4.h"
ac27a0ec DK	12
	13	#define DELTA 0x9E3779B9
	14
	15	static void TEA_transform(__u32 buf[4], __u32 const in[])
	16	{
	17	__u32 sum = 0;
	18	__u32 b0 = buf[0], b1 = buf[1];
	19	__u32 a = in[0], b = in[1], c = in[2], d = in[3];
	20	int n = 16;
	21
	22	do {
	23	sum += DELTA;
	24	b0 += ((b1 << 4)+a) ^ (b1+sum) ^ ((b1 >> 5)+b);
	25	b1 += ((b0 << 4)+c) ^ (b0+sum) ^ ((b0 >> 5)+d);
af5bc92d	26	} while (--n);
ac27a0ec DK	27
	28	buf[0] += b0;
	29	buf[1] += b1;
	30	}
	31
1c83a9aa JD	32	/* F, G and H are basic MD4 functions: selection, majority, parity */
	33	#define F(x, y, z) ((z) ^ ((x) & ((y) ^ (z))))
	34	#define G(x, y, z) (((x) & (y)) + (((x) ^ (y)) & (z)))
	35	#define H(x, y, z) ((x) ^ (y) ^ (z))
	36
	37	/*
	38	* The generic round function. The application is so specific that
	39	* we don't bother protecting all the arguments with parens, as is generally
	40	* good macro practice, in favor of extra legibility.
	41	* Rotation is separate from addition to prevent recomputation
	42	*/
	43	#define ROUND(f, a, b, c, d, x, s) \
	44	(a += f(b, c, d) + x, a = rol32(a, s))
	45	#define K1 0
	46	#define K2 013240474631UL
	47	#define K3 015666365641UL
	48
	49	/*
	50	* Basic cut-down MD4 transform. Returns only 32 bits of result.
	51	*/
	52	static __u32 half_md4_transform(__u32 buf[4], __u32 const in[8])
	53	{
	54	__u32 a = buf[0], b = buf[1], c = buf[2], d = buf[3];
	55
	56	/* Round 1 */
	57	ROUND(F, a, b, c, d, in[0] + K1, 3);
	58	ROUND(F, d, a, b, c, in[1] + K1, 7);
	59	ROUND(F, c, d, a, b, in[2] + K1, 11);
	60	ROUND(F, b, c, d, a, in[3] + K1, 19);
	61	ROUND(F, a, b, c, d, in[4] + K1, 3);
	62	ROUND(F, d, a, b, c, in[5] + K1, 7);
	63	ROUND(F, c, d, a, b, in[6] + K1, 11);
	64	ROUND(F, b, c, d, a, in[7] + K1, 19);
	65
	66	/* Round 2 */
	67	ROUND(G, a, b, c, d, in[1] + K2, 3);
	68	ROUND(G, d, a, b, c, in[3] + K2, 5);
	69	ROUND(G, c, d, a, b, in[5] + K2, 9);
	70	ROUND(G, b, c, d, a, in[7] + K2, 13);
	71	ROUND(G, a, b, c, d, in[0] + K2, 3);
	72	ROUND(G, d, a, b, c, in[2] + K2, 5);
	73	ROUND(G, c, d, a, b, in[4] + K2, 9);
	74	ROUND(G, b, c, d, a, in[6] + K2, 13);
	75
	76	/* Round 3 */
	77	ROUND(H, a, b, c, d, in[3] + K3, 3);
	78	ROUND(H, d, a, b, c, in[7] + K3, 9);
	79	ROUND(H, c, d, a, b, in[2] + K3, 11);
	80	ROUND(H, b, c, d, a, in[6] + K3, 15);
	81	ROUND(H, a, b, c, d, in[1] + K3, 3);
	82	ROUND(H, d, a, b, c, in[5] + K3, 9);
	83	ROUND(H, c, d, a, b, in[0] + K3, 11);
	84	ROUND(H, b, c, d, a, in[4] + K3, 15);
	85
	86	buf[0] += a;
	87	buf[1] += b;
	88	buf[2] += c;
	89	buf[3] += d;
	90
	91	return buf[1]; /* "most hashed" word */
	92	}
	93	#undef ROUND
	94	#undef K1
	95	#undef K2
96	#undef K3
97	#undef F
98	#undef G
99	#undef H
ac27a0ec DK	100
ac27a0ec DK	101	/* The old legacy hash */
f99b2589	102	static __u32 dx_hack_hash_unsigned(const char *name, int len)
ac27a0ec	103	{
f99b2589 TT	104	__u32 hash, hash0 = 0x12a3fe2d, hash1 = 0x37abe8f9;
	105	const unsigned char ucp = (const unsigned char ) name;
	106
	107	while (len--) {
	108	hash = hash1 + (hash0 ^ (((int) ucp++) 7152373));
	109
	110	if (hash & 0x80000000)
	111	hash -= 0x7fffffff;
	112	hash1 = hash0;
	113	hash0 = hash;
	114	}
	115	return hash0 << 1;
	116	}
	117
	118	static __u32 dx_hack_hash_signed(const char *name, int len)
	119	{
	120	__u32 hash, hash0 = 0x12a3fe2d, hash1 = 0x37abe8f9;
	121	const signed char scp = (const signed char ) name;
	122
ac27a0ec	123	while (len--) {
f99b2589	124	hash = hash1 + (hash0 ^ (((int) scp++) 7152373));
ac27a0ec	125
f99b2589 TT	126	if (hash & 0x80000000)
f99b2589 TT	127	hash -= 0x7fffffff;
ac27a0ec DK	128	hash1 = hash0;
	129	hash0 = hash;
	130	}
f99b2589 TT	131	return hash0 << 1;
	132	}
	133
	134	static void str2hashbuf_signed(const char msg, int len, __u32 buf, int num)
	135	{
	136	__u32 pad, val;
	137	int i;
	138	const signed char scp = (const signed char ) msg;
	139
	140	pad = (__u32)len \| ((__u32)len << 8);
	141	pad \|= pad << 16;
	142
	143	val = pad;
	144	if (len > num*4)
	145	len = num * 4;
	146	for (i = 0; i < len; i++) {
f99b2589 TT	147	val = ((int) scp[i]) + (val << 8);
	148	if ((i % 4) == 3) {
	149	*buf++ = val;
	150	val = pad;
	151	num--;
	152	}
	153	}
	154	if (--num >= 0)
	155	*buf++ = val;
	156	while (--num >= 0)
	157	*buf++ = pad;
ac27a0ec DK	158	}
ac27a0ec DK	159
f99b2589	160	static void str2hashbuf_unsigned(const char msg, int len, __u32 buf, int num)
ac27a0ec DK	161	{
	162	__u32 pad, val;
	163	int i;
f99b2589	164	const unsigned char ucp = (const unsigned char ) msg;
ac27a0ec DK	165
	166	pad = (__u32)len \| ((__u32)len << 8);
	167	pad \|= pad << 16;
	168
	169	val = pad;
	170	if (len > num*4)
	171	len = num * 4;
af5bc92d	172	for (i = 0; i < len; i++) {
f99b2589	173	val = ((int) ucp[i]) + (val << 8);
ac27a0ec DK	174	if ((i % 4) == 3) {
	175	*buf++ = val;
	176	val = pad;
	177	num--;
	178	}
	179	}
	180	if (--num >= 0)
	181	*buf++ = val;
	182	while (--num >= 0)
	183	*buf++ = pad;
	184	}
	185
	186	/*
	187	* Returns the hash of a filename. If len is 0 and name is NULL, then
	188	* this function can be used to test whether or not a hash version is
	189	* supported.
	190	*
	191	* The seed is an 4 longword (32 bits) "secret" which can be used to
	192	* uniquify a hash. If the seed is all zero's, then some default seed
	193	* may be used.
	194	*
	195	* A particular hash version specifies whether or not the seed is
	196	* represented, and whether or not the returned hash is 32 bits or 64
	197	* bits. 32 bit hashes will return 0 for the minor hash.
	198	*/
617ba13b	199	int ext4fs_dirhash(const char name, int len, struct dx_hash_info hinfo)
ac27a0ec DK	200	{
	201	__u32 hash;
	202	__u32 minor_hash = 0;
	203	const char *p;
	204	int i;
	205	__u32 in[8], buf[4];
f99b2589 TT	206	void (str2hashbuf)(const char , int, __u32 *, int) =
f99b2589 TT	207	str2hashbuf_signed;
ac27a0ec DK	208
	209	/* Initialize the default seed for the hash checksum functions */
	210	buf[0] = 0x67452301;
	211	buf[1] = 0xefcdab89;
	212	buf[2] = 0x98badcfe;
	213	buf[3] = 0x10325476;
	214
	215	/* Check to see if the seed is all zero's */
	216	if (hinfo->seed) {
af5bc92d	217	for (i = 0; i < 4; i++) {
0e79537d CD	218	if (hinfo->seed[i]) {
0e79537d CD	219	memcpy(buf, hinfo->seed, sizeof(buf));
ac27a0ec	220	break;
0e79537d	221	}
ac27a0ec	222	}
ac27a0ec DK	223	}
	224
	225	switch (hinfo->hash_version) {
f99b2589 TT	226	case DX_HASH_LEGACY_UNSIGNED:
	227	hash = dx_hack_hash_unsigned(name, len);
	228	break;
ac27a0ec	229	case DX_HASH_LEGACY:
f99b2589	230	hash = dx_hack_hash_signed(name, len);
ac27a0ec	231	break;
f99b2589 TT	232	case DX_HASH_HALF_MD4_UNSIGNED:
f99b2589 TT	233	str2hashbuf = str2hashbuf_unsigned;
ac27a0ec DK	234	case DX_HASH_HALF_MD4:
	235	p = name;
	236	while (len > 0) {
f99b2589	237	(*str2hashbuf)(p, len, in, 8);
ac27a0ec DK	238	half_md4_transform(buf, in);
	239	len -= 32;
	240	p += 32;
	241	}
	242	minor_hash = buf[2];
	243	hash = buf[1];
	244	break;
f99b2589 TT	245	case DX_HASH_TEA_UNSIGNED:
f99b2589 TT	246	str2hashbuf = str2hashbuf_unsigned;
ac27a0ec DK	247	case DX_HASH_TEA:
	248	p = name;
	249	while (len > 0) {
f99b2589	250	(*str2hashbuf)(p, len, in, 4);
ac27a0ec DK	251	TEA_transform(buf, in);
	252	len -= 16;
	253	p += 16;
	254	}
	255	hash = buf[0];
	256	minor_hash = buf[1];
	257	break;
	258	default:
	259	hinfo->hash = 0;
	260	return -1;
	261	}
	262	hash = hash & ~1;
d1f5273e FY	263	if (hash == (EXT4_HTREE_EOF_32BIT << 1))
d1f5273e FY	264	hash = (EXT4_HTREE_EOF_32BIT - 1) << 1;
ac27a0ec DK	265	hinfo->hash = hash;
	266	hinfo->minor_hash = minor_hash;
	267	return 0;
	268	}