[thirdparty/e2fsprogs.git] / lib / ext2fs / dirhash.c

/*
 * dirhash.c -- Calculate the hash of a directory entry
 *
 * Copyright (c) 2001  Daniel Phillips
 *
 * Copyright (c) 2002 Theodore Ts'o.
 *
 * %Begin-Header%
 * This file may be redistributed under the terms of the GNU Library
 * General Public License, version 2.
 * %End-Header%
 */

#include "config.h"
#include <stdio.h>
#include <string.h>
#include <limits.h>

#include "ext2_fs.h"
#include "ext2fs.h"

/*
 * Keyed 32-bit hash function using TEA in a Davis-Meyer function
 *   H0 = Key
 *   Hi = E Mi(Hi-1) + Hi-1
 *
 * (see Applied Cryptography, 2nd edition, p448).
 *
 * Jeremy Fitzhardinge <jeremy@zip.com.au> 1998
 *
 * This code is made available under the terms of the GPL
 */
#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 = (a << s) | (a >> (32-s)))
#define K1 0
#define K2 013240474631UL
#define K3 015666365641UL

/*
 * Basic cut-down MD4 transform.  Returns only 32 bits of result.
 */
static void halfMD4Transform (__u32 buf[4], __u32 const in[])
{
	__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;
}

#undef ROUND
#undef F
#undef G
#undef H
#undef K1
#undef K2
#undef K3

/* The old legacy hash */
static ext2_dirhash_t dx_hack_hash (const char *name, int len,
				    int unsigned_flag)
{
	__u32 hash, hash0 = 0x12a3fe2d, hash1 = 0x37abe8f9;
	const unsigned char *ucp = (const unsigned char *) name;
	const signed char *scp = (const signed char *) name;
	int c;

	while (len--) {
		if (unsigned_flag)
			c = (int) *ucp++;
		else
			c = (int) *scp++;
		hash = hash1 + (hash0 ^ (c * 7152373));

		if (hash & 0x80000000) hash -= 0x7fffffff;
		hash1 = hash0;
		hash0 = hash;
	}
	return (hash0 << 1);
}

static void str2hashbuf(const char *msg, int len, __u32 *buf, int num,
			int unsigned_flag)
{
	__u32	pad, val;
	int	i, c;
	const unsigned char *ucp = (const unsigned char *) msg;
	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++) {
		if (unsigned_flag)
			c = (int) ucp[i];
		else
			c = (int) scp[i];

		val = c + (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.
 *
 * This function doesn't do any normalization or casefolding of the
 * input string.  To take charset encoding into account, use
 * ext2fs_dirhash2.
 *
 */
errcode_t ext2fs_dirhash(int version, const char *name, int len,
			 const __u32 *seed,
			 ext2_dirhash_t *ret_hash,
			 ext2_dirhash_t *ret_minor_hash)
{
	__u32	hash;
	__u32	minor_hash = 0;
	const char	*p;
	int		i;
	__u32 		in[8], buf[4];
	int		unsigned_flag = 0;

	/* 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 (seed) {
		for (i=0; i < 4; i++) {
			if (seed[i])
				break;
		}
		if (i < 4)
			memcpy(buf, seed, sizeof(buf));
	}

	switch (version) {
	case EXT2_HASH_LEGACY_UNSIGNED:
		unsigned_flag++;
		/* fallthrough */
	case EXT2_HASH_LEGACY:
		hash = dx_hack_hash(name, len, unsigned_flag);
		break;
	case EXT2_HASH_HALF_MD4_UNSIGNED:
		unsigned_flag++;
		/* fallthrough */
	case EXT2_HASH_HALF_MD4:
		p = name;
		while (len > 0) {
			str2hashbuf(p, len, in, 8, unsigned_flag);
			halfMD4Transform(buf, in);
			len -= 32;
			p += 32;
		}
		minor_hash = buf[2];
		hash = buf[1];
		break;
	case EXT2_HASH_TEA_UNSIGNED:
		unsigned_flag++;
		/* fallthrough */
	case EXT2_HASH_TEA:
		p = name;
		while (len > 0) {
			str2hashbuf(p, len, in, 4, unsigned_flag);
			TEA_transform(buf, in);
			len -= 16;
			p += 16;
		}
		hash = buf[0];
		minor_hash = buf[1];
		break;
	default:
		*ret_hash = 0;
		return EXT2_ET_DIRHASH_UNSUPP;
	}
	*ret_hash = hash & ~1;
	if (ret_minor_hash)
		*ret_minor_hash = minor_hash;
	return 0;
}

/*
 * Returns the hash of a filename considering normalization and
 * casefolding.  This is a wrapper around ext2fs_dirhash with string
 * encoding support based on the nls_table and the flags. Check
 * ext2fs_dirhash for documentation on the input and output parameters.
 */
errcode_t ext2fs_dirhash2(int version, const char *name, int len,
			  const struct ext2fs_nls_table *charset,
			  int hash_flags, const __u32 *seed,
			  ext2_dirhash_t *ret_hash,
			  ext2_dirhash_t *ret_minor_hash)
{
	errcode_t r;
	int dlen;

	if (len && charset && (hash_flags & EXT4_CASEFOLD_FL)) {
		char buff[PATH_MAX];

		dlen = charset->ops->casefold(charset, name, len, buff,
						      sizeof(buff));
		if (dlen < 0) {
			if (dlen == -EINVAL)
				goto opaque_seq;

			return dlen;
		}
		r = ext2fs_dirhash(version, buff, dlen, seed, ret_hash,
				   ret_minor_hash);
		return r;
	}

opaque_seq:
	return ext2fs_dirhash(version, name, len, seed, ret_hash,
			      ret_minor_hash);
}
Commit	Line	Data
52783e0c TT	1	/*
	2	* dirhash.c -- Calculate the hash of a directory entry
	3	*
	4	* Copyright (c) 2001 Daniel Phillips
efc6f628	5	*
52783e0c TT	6	* Copyright (c) 2002 Theodore Ts'o.
	7	*
	8	* %Begin-Header%
543547a5 TT	9	* This file may be redistributed under the terms of the GNU Library
543547a5 TT	10	* General Public License, version 2.
52783e0c TT	11	* %End-Header%
	12	*/
	13
d1154eb4	14	#include "config.h"
52783e0c	15	#include <stdio.h>
d3f91798	16	#include <string.h>
28b44ef0	17	#include <limits.h>
52783e0c TT	18
	19	#include "ext2_fs.h"
	20	#include "ext2fs.h"
	21
b33278c4 TT	22	/*
	23	* Keyed 32-bit hash function using TEA in a Davis-Meyer function
	24	* H0 = Key
	25	* Hi = E Mi(Hi-1) + Hi-1
	26	*
	27	* (see Applied Cryptography, 2nd edition, p448).
	28	*
	29	* Jeremy Fitzhardinge <jeremy@zip.com.au> 1998
efc6f628	30	*
b33278c4 TT	31	* This code is made available under the terms of the GPL
	32	*/
	33	#define DELTA 0x9E3779B9
	34
	35	static void TEA_transform(__u32 buf[4], __u32 const in[])
	36	{
	37	__u32 sum = 0;
	38	__u32 b0 = buf[0], b1 = buf[1];
	39	__u32 a = in[0], b = in[1], c = in[2], d = in[3];
	40	int n = 16;
	41
efc6f628 TT	42	do {
	43	sum += DELTA;
	44	b0 += ((b1 << 4)+a) ^ (b1+sum) ^ ((b1 >> 5)+b);
	45	b1 += ((b0 << 4)+c) ^ (b0+sum) ^ ((b0 >> 5)+d);
b33278c4 TT	46	} while(--n);
	47
	48	buf[0] += b0;
	49	buf[1] += b1;
	50	}
	51
503f9e7f TT	52	/* F, G and H are basic MD4 functions: selection, majority, parity */
	53	#define F(x, y, z) ((z) ^ ((x) & ((y) ^ (z))))
	54	#define G(x, y, z) (((x) & (y)) + (((x) ^ (y)) & (z)))
	55	#define H(x, y, z) ((x) ^ (y) ^ (z))
	56
	57	/*
	58	* The generic round function. The application is so specific that
	59	* we don't bother protecting all the arguments with parens, as is generally
	60	* good macro practice, in favor of extra legibility.
	61	* Rotation is separate from addition to prevent recomputation
	62	*/
	63	#define ROUND(f, a, b, c, d, x, s) \
	64	(a += f(b, c, d) + x, a = (a << s) \| (a >> (32-s)))
	65	#define K1 0
	66	#define K2 013240474631UL
	67	#define K3 015666365641UL
	68
	69	/*
	70	* Basic cut-down MD4 transform. Returns only 32 bits of result.
	71	*/
b33278c4	72	static void halfMD4Transform (__u32 buf[4], __u32 const in[])
503f9e7f TT	73	{
	74	__u32 a = buf[0], b = buf[1], c = buf[2], d = buf[3];
	75
	76	/* Round 1 */
	77	ROUND(F, a, b, c, d, in[0] + K1, 3);
	78	ROUND(F, d, a, b, c, in[1] + K1, 7);
	79	ROUND(F, c, d, a, b, in[2] + K1, 11);
	80	ROUND(F, b, c, d, a, in[3] + K1, 19);
	81	ROUND(F, a, b, c, d, in[4] + K1, 3);
	82	ROUND(F, d, a, b, c, in[5] + K1, 7);
	83	ROUND(F, c, d, a, b, in[6] + K1, 11);
	84	ROUND(F, b, c, d, a, in[7] + K1, 19);
	85
	86	/* Round 2 */
	87	ROUND(G, a, b, c, d, in[1] + K2, 3);
	88	ROUND(G, d, a, b, c, in[3] + K2, 5);
	89	ROUND(G, c, d, a, b, in[5] + K2, 9);
	90	ROUND(G, b, c, d, a, in[7] + K2, 13);
	91	ROUND(G, a, b, c, d, in[0] + K2, 3);
	92	ROUND(G, d, a, b, c, in[2] + K2, 5);
	93	ROUND(G, c, d, a, b, in[4] + K2, 9);
	94	ROUND(G, b, c, d, a, in[6] + K2, 13);
	95
	96	/* Round 3 */
	97	ROUND(H, a, b, c, d, in[3] + K3, 3);
	98	ROUND(H, d, a, b, c, in[7] + K3, 9);
	99	ROUND(H, c, d, a, b, in[2] + K3, 11);
	100	ROUND(H, b, c, d, a, in[6] + K3, 15);
	101	ROUND(H, a, b, c, d, in[1] + K3, 3);
	102	ROUND(H, d, a, b, c, in[5] + K3, 9);
	103	ROUND(H, c, d, a, b, in[0] + K3, 11);
	104	ROUND(H, b, c, d, a, in[4] + K3, 15);
	105
	106	buf[0] += a;
	107	buf[1] += b;
	108	buf[2] += c;
	109	buf[3] += d;
503f9e7f TT	110	}
	111
	112	#undef ROUND
	113	#undef F
	114	#undef G
	115	#undef H
	116	#undef K1
	117	#undef K2
	118	#undef K3
	119
	120	/* The old legacy hash */
f77704e4 TT	121	static ext2_dirhash_t dx_hack_hash (const char *name, int len,
f77704e4 TT	122	int unsigned_flag)
52783e0c	123	{
f77704e4 TT	124	__u32 hash, hash0 = 0x12a3fe2d, hash1 = 0x37abe8f9;
	125	const unsigned char ucp = (const unsigned char ) name;
	126	const signed char scp = (const signed char ) name;
	127	int c;
	128
52783e0c	129	while (len--) {
f77704e4 TT	130	if (unsigned_flag)
	131	c = (int) *ucp++;
	132	else
	133	c = (int) *scp++;
	134	hash = hash1 + (hash0 ^ (c * 7152373));
efc6f628	135
52783e0c TT	136	if (hash & 0x80000000) hash -= 0x7fffffff;
	137	hash1 = hash0;
	138	hash0 = hash;
	139	}
1acb01b4	140	return (hash0 << 1);
52783e0c TT	141	}
52783e0c TT	142
f77704e4 TT	143	static void str2hashbuf(const char msg, int len, __u32 buf, int num,
f77704e4 TT	144	int unsigned_flag)
b33278c4 TT	145	{
b33278c4 TT	146	__u32 pad, val;
f77704e4 TT	147	int i, c;
	148	const unsigned char ucp = (const unsigned char ) msg;
	149	const signed char scp = (const signed char ) msg;
b33278c4 TT	150
	151	pad = (__u32)len \| ((__u32)len << 8);
	152	pad \|= pad << 16;
	153
	154	val = pad;
	155	if (len > num*4)
	156	len = num * 4;
	157	for (i=0; i < len; i++) {
f77704e4 TT	158	if (unsigned_flag)
	159	c = (int) ucp[i];
	160	else
	161	c = (int) scp[i];
	162
	163	val = c + (val << 8);
b33278c4 TT	164	if ((i % 4) == 3) {
	165	*buf++ = val;
	166	val = pad;
	167	num--;
	168	}
	169	}
	170	if (--num >= 0)
	171	*buf++ = val;
	172	while (--num >= 0)
	173	*buf++ = pad;
	174	}
	175
52783e0c TT	176	/*
	177	* Returns the hash of a filename. If len is 0 and name is NULL, then
	178	* this function can be used to test whether or not a hash version is
	179	* supported.
efc6f628	180	*
503f9e7f TT	181	* The seed is an 4 longword (32 bits) "secret" which can be used to
	182	* uniquify a hash. If the seed is all zero's, then some default seed
	183	* may be used.
efc6f628	184	*
503f9e7f TT	185	* A particular hash version specifies whether or not the seed is
	186	* represented, and whether or not the returned hash is 32 bits or 64
	187	* bits. 32 bit hashes will return 0 for the minor hash.
28b44ef0 GKB	188	*
	189	* This function doesn't do any normalization or casefolding of the
	190	* input string. To take charset encoding into account, use
	191	* ext2fs_dirhash2.
	192	*
52783e0c TT	193	*/
52783e0c TT	194	errcode_t ext2fs_dirhash(int version, const char *name, int len,
b33278c4	195	const __u32 *seed,
503f9e7f TT	196	ext2_dirhash_t *ret_hash,
503f9e7f TT	197	ext2_dirhash_t *ret_minor_hash)
52783e0c TT	198	{
52783e0c TT	199	__u32 hash;
503f9e7f	200	__u32 minor_hash = 0;
cc90bdfd	201	const char *p;
b33278c4 TT	202	int i;
b33278c4 TT	203	__u32 in[8], buf[4];
f77704e4	204	int unsigned_flag = 0;
b33278c4 TT	205
	206	/* Initialize the default seed for the hash checksum functions */
	207	buf[0] = 0x67452301;
	208	buf[1] = 0xefcdab89;
	209	buf[2] = 0x98badcfe;
	210	buf[3] = 0x10325476;
52783e0c	211
503f9e7f	212	/* Check to see if the seed is all zero's */
b33278c4 TT	213	if (seed) {
	214	for (i=0; i < 4; i++) {
	215	if (seed[i])
	216	break;
	217	}
	218	if (i < 4)
	219	memcpy(buf, seed, sizeof(buf));
503f9e7f	220	}
efc6f628	221
b33278c4	222	switch (version) {
f77704e4 TT	223	case EXT2_HASH_LEGACY_UNSIGNED:
f77704e4 TT	224	unsigned_flag++;
9e30fb23	225	/* fallthrough */
b33278c4	226	case EXT2_HASH_LEGACY:
f77704e4	227	hash = dx_hack_hash(name, len, unsigned_flag);
b33278c4	228	break;
f77704e4 TT	229	case EXT2_HASH_HALF_MD4_UNSIGNED:
f77704e4 TT	230	unsigned_flag++;
9e30fb23	231	/* fallthrough */
b33278c4	232	case EXT2_HASH_HALF_MD4:
cc90bdfd	233	p = name;
b33278c4	234	while (len > 0) {
f77704e4	235	str2hashbuf(p, len, in, 8, unsigned_flag);
b33278c4	236	halfMD4Transform(buf, in);
503f9e7f TT	237	len -= 32;
	238	p += 32;
	239	}
b33278c4 TT	240	minor_hash = buf[2];
	241	hash = buf[1];
	242	break;
f77704e4 TT	243	case EXT2_HASH_TEA_UNSIGNED:
f77704e4 TT	244	unsigned_flag++;
9e30fb23	245	/* fallthrough */
b33278c4 TT	246	case EXT2_HASH_TEA:
	247	p = name;
	248	while (len > 0) {
f77704e4	249	str2hashbuf(p, len, in, 4, unsigned_flag);
b33278c4 TT	250	TEA_transform(buf, in);
	251	len -= 16;
	252	p += 16;
	253	}
	254	hash = buf[0];
	255	minor_hash = buf[1];
	256	break;
	257	default:
52783e0c TT	258	*ret_hash = 0;
	259	return EXT2_ET_DIRHASH_UNSUPP;
	260	}
b33278c4	261	*ret_hash = hash & ~1;
503f9e7f TT	262	if (ret_minor_hash)
503f9e7f TT	263	*ret_minor_hash = minor_hash;
52783e0c	264	return 0;
52783e0c	265	}
28b44ef0 GKB	266
	267	/*
	268	* Returns the hash of a filename considering normalization and
	269	* casefolding. This is a wrapper around ext2fs_dirhash with string
	270	* encoding support based on the nls_table and the flags. Check
	271	* ext2fs_dirhash for documentation on the input and output parameters.
	272	*/
	273	errcode_t ext2fs_dirhash2(int version, const char *name, int len,
388e1d56 TT	274	const struct ext2fs_nls_table *charset,
388e1d56 TT	275	int hash_flags, const __u32 *seed,
28b44ef0 GKB	276	ext2_dirhash_t *ret_hash,
	277	ext2_dirhash_t *ret_minor_hash)
	278	{
	279	errcode_t r;
	280	int dlen;
28b44ef0	281
a8567fdb	282	if (len && charset && (hash_flags & EXT4_CASEFOLD_FL)) {
28b44ef0 GKB	283	char buff[PATH_MAX];
28b44ef0 GKB	284
a8567fdb	285	dlen = charset->ops->casefold(charset, name, len, buff,
28b44ef0	286	sizeof(buff));
28b44ef0 GKB	287	if (dlen < 0) {
	288	if (dlen == -EINVAL)
	289	goto opaque_seq;
	290
	291	return dlen;
	292	}
	293	r = ext2fs_dirhash(version, buff, dlen, seed, ret_hash,
	294	ret_minor_hash);
	295	return r;
	296	}
	297
	298	opaque_seq:
	299	return ext2fs_dirhash(version, name, len, seed, ret_hash,
	300	ret_minor_hash);
	301	}