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ext2fs_hash.c
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ext2fs_hash.c
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#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 <ufs/ext2fs/ext2fs_htree.h>
#include <ufs/ufs/inode.h>
#include <ufs/ufs/ufsmount.h>
#include <ufs/ext2fs/ext2fs_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)); \
}
static void
ext2fs_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);
}
}
static uint32_t
ext2fs_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);
}
/*
* 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
ext2fs_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
ext2fs_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;
}
int
ext2fs_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) {
ext2fs_prep_hashbuf(name, len, data, 16, unsigned_char);
ext2fs_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 = ext2fs_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) {
ext2fs_prep_hashbuf(name, len, data, 32, unsigned_char);
ext2fs_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);
}