"Robert P. J. Day" | 63fc1a9 | 2006-07-02 19:47:05 +0000 | [diff] [blame^] | 1 | /* vi: set sw=4 ts=4: */ |
Mike Frysinger | 1fd98e0 | 2005-05-09 22:10:42 +0000 | [diff] [blame] | 2 | /* |
| 3 | * dirhash.c -- Calculate the hash of a directory entry |
| 4 | * |
| 5 | * Copyright (c) 2001 Daniel Phillips |
Tim Riker | c1ef7bd | 2006-01-25 00:08:53 +0000 | [diff] [blame] | 6 | * |
Mike Frysinger | 1fd98e0 | 2005-05-09 22:10:42 +0000 | [diff] [blame] | 7 | * Copyright (c) 2002 Theodore Ts'o. |
| 8 | * |
| 9 | * %Begin-Header% |
| 10 | * This file may be redistributed under the terms of the GNU Public |
| 11 | * License. |
| 12 | * %End-Header% |
| 13 | */ |
| 14 | |
| 15 | #include <stdio.h> |
| 16 | #include <string.h> |
| 17 | |
| 18 | #include "ext2_fs.h" |
| 19 | #include "ext2fs.h" |
| 20 | |
| 21 | /* |
| 22 | * Keyed 32-bit hash function using TEA in a Davis-Meyer function |
| 23 | * H0 = Key |
| 24 | * Hi = E Mi(Hi-1) + Hi-1 |
| 25 | * |
| 26 | * (see Applied Cryptography, 2nd edition, p448). |
| 27 | * |
| 28 | * Jeremy Fitzhardinge <jeremy@zip.com.au> 1998 |
Tim Riker | c1ef7bd | 2006-01-25 00:08:53 +0000 | [diff] [blame] | 29 | * |
Mike Frysinger | 1fd98e0 | 2005-05-09 22:10:42 +0000 | [diff] [blame] | 30 | * This code is made available under the terms of the GPL |
| 31 | */ |
| 32 | #define DELTA 0x9E3779B9 |
| 33 | |
| 34 | static void TEA_transform(__u32 buf[4], __u32 const in[]) |
| 35 | { |
| 36 | __u32 sum = 0; |
| 37 | __u32 b0 = buf[0], b1 = buf[1]; |
| 38 | __u32 a = in[0], b = in[1], c = in[2], d = in[3]; |
| 39 | int n = 16; |
| 40 | |
Tim Riker | c1ef7bd | 2006-01-25 00:08:53 +0000 | [diff] [blame] | 41 | do { |
| 42 | sum += DELTA; |
| 43 | b0 += ((b1 << 4)+a) ^ (b1+sum) ^ ((b1 >> 5)+b); |
| 44 | b1 += ((b0 << 4)+c) ^ (b0+sum) ^ ((b0 >> 5)+d); |
Mike Frysinger | 1fd98e0 | 2005-05-09 22:10:42 +0000 | [diff] [blame] | 45 | } while(--n); |
| 46 | |
| 47 | buf[0] += b0; |
| 48 | buf[1] += b1; |
| 49 | } |
| 50 | |
| 51 | /* F, G and H are basic MD4 functions: selection, majority, parity */ |
| 52 | #define F(x, y, z) ((z) ^ ((x) & ((y) ^ (z)))) |
| 53 | #define G(x, y, z) (((x) & (y)) + (((x) ^ (y)) & (z))) |
| 54 | #define H(x, y, z) ((x) ^ (y) ^ (z)) |
| 55 | |
| 56 | /* |
| 57 | * The generic round function. The application is so specific that |
| 58 | * we don't bother protecting all the arguments with parens, as is generally |
| 59 | * good macro practice, in favor of extra legibility. |
| 60 | * Rotation is separate from addition to prevent recomputation |
| 61 | */ |
| 62 | #define ROUND(f, a, b, c, d, x, s) \ |
| 63 | (a += f(b, c, d) + x, a = (a << s) | (a >> (32-s))) |
| 64 | #define K1 0 |
| 65 | #define K2 013240474631UL |
| 66 | #define K3 015666365641UL |
| 67 | |
| 68 | /* |
| 69 | * Basic cut-down MD4 transform. Returns only 32 bits of result. |
| 70 | */ |
| 71 | static void halfMD4Transform (__u32 buf[4], __u32 const in[]) |
| 72 | { |
| 73 | __u32 a = buf[0], b = buf[1], c = buf[2], d = buf[3]; |
| 74 | |
| 75 | /* Round 1 */ |
| 76 | ROUND(F, a, b, c, d, in[0] + K1, 3); |
| 77 | ROUND(F, d, a, b, c, in[1] + K1, 7); |
| 78 | ROUND(F, c, d, a, b, in[2] + K1, 11); |
| 79 | ROUND(F, b, c, d, a, in[3] + K1, 19); |
| 80 | ROUND(F, a, b, c, d, in[4] + K1, 3); |
| 81 | ROUND(F, d, a, b, c, in[5] + K1, 7); |
| 82 | ROUND(F, c, d, a, b, in[6] + K1, 11); |
| 83 | ROUND(F, b, c, d, a, in[7] + K1, 19); |
| 84 | |
| 85 | /* Round 2 */ |
| 86 | ROUND(G, a, b, c, d, in[1] + K2, 3); |
| 87 | ROUND(G, d, a, b, c, in[3] + K2, 5); |
| 88 | ROUND(G, c, d, a, b, in[5] + K2, 9); |
| 89 | ROUND(G, b, c, d, a, in[7] + K2, 13); |
| 90 | ROUND(G, a, b, c, d, in[0] + K2, 3); |
| 91 | ROUND(G, d, a, b, c, in[2] + K2, 5); |
| 92 | ROUND(G, c, d, a, b, in[4] + K2, 9); |
| 93 | ROUND(G, b, c, d, a, in[6] + K2, 13); |
| 94 | |
| 95 | /* Round 3 */ |
| 96 | ROUND(H, a, b, c, d, in[3] + K3, 3); |
| 97 | ROUND(H, d, a, b, c, in[7] + K3, 9); |
| 98 | ROUND(H, c, d, a, b, in[2] + K3, 11); |
| 99 | ROUND(H, b, c, d, a, in[6] + K3, 15); |
| 100 | ROUND(H, a, b, c, d, in[1] + K3, 3); |
| 101 | ROUND(H, d, a, b, c, in[5] + K3, 9); |
| 102 | ROUND(H, c, d, a, b, in[0] + K3, 11); |
| 103 | ROUND(H, b, c, d, a, in[4] + K3, 15); |
| 104 | |
| 105 | buf[0] += a; |
| 106 | buf[1] += b; |
| 107 | buf[2] += c; |
| 108 | buf[3] += d; |
| 109 | } |
| 110 | |
| 111 | #undef ROUND |
| 112 | #undef F |
| 113 | #undef G |
| 114 | #undef H |
| 115 | #undef K1 |
| 116 | #undef K2 |
| 117 | #undef K3 |
| 118 | |
| 119 | /* The old legacy hash */ |
| 120 | static ext2_dirhash_t dx_hack_hash (const char *name, int len) |
| 121 | { |
| 122 | __u32 hash0 = 0x12a3fe2d, hash1 = 0x37abe8f9; |
| 123 | while (len--) { |
| 124 | __u32 hash = hash1 + (hash0 ^ (*name++ * 7152373)); |
Tim Riker | c1ef7bd | 2006-01-25 00:08:53 +0000 | [diff] [blame] | 125 | |
Mike Frysinger | 1fd98e0 | 2005-05-09 22:10:42 +0000 | [diff] [blame] | 126 | if (hash & 0x80000000) hash -= 0x7fffffff; |
| 127 | hash1 = hash0; |
| 128 | hash0 = hash; |
| 129 | } |
| 130 | return (hash0 << 1); |
| 131 | } |
| 132 | |
| 133 | static void str2hashbuf(const char *msg, int len, __u32 *buf, int num) |
| 134 | { |
| 135 | __u32 pad, val; |
| 136 | int i; |
| 137 | |
| 138 | pad = (__u32)len | ((__u32)len << 8); |
| 139 | pad |= pad << 16; |
| 140 | |
| 141 | val = pad; |
| 142 | if (len > num*4) |
| 143 | len = num * 4; |
| 144 | for (i=0; i < len; i++) { |
| 145 | if ((i % 4) == 0) |
| 146 | val = pad; |
| 147 | val = msg[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; |
| 158 | } |
| 159 | |
| 160 | /* |
| 161 | * Returns the hash of a filename. If len is 0 and name is NULL, then |
| 162 | * this function can be used to test whether or not a hash version is |
| 163 | * supported. |
Tim Riker | c1ef7bd | 2006-01-25 00:08:53 +0000 | [diff] [blame] | 164 | * |
Mike Frysinger | 1fd98e0 | 2005-05-09 22:10:42 +0000 | [diff] [blame] | 165 | * The seed is an 4 longword (32 bits) "secret" which can be used to |
| 166 | * uniquify a hash. If the seed is all zero's, then some default seed |
| 167 | * may be used. |
Tim Riker | c1ef7bd | 2006-01-25 00:08:53 +0000 | [diff] [blame] | 168 | * |
Mike Frysinger | 1fd98e0 | 2005-05-09 22:10:42 +0000 | [diff] [blame] | 169 | * A particular hash version specifies whether or not the seed is |
| 170 | * represented, and whether or not the returned hash is 32 bits or 64 |
| 171 | * bits. 32 bit hashes will return 0 for the minor hash. |
| 172 | */ |
| 173 | errcode_t ext2fs_dirhash(int version, const char *name, int len, |
| 174 | const __u32 *seed, |
| 175 | ext2_dirhash_t *ret_hash, |
| 176 | ext2_dirhash_t *ret_minor_hash) |
| 177 | { |
| 178 | __u32 hash; |
| 179 | __u32 minor_hash = 0; |
| 180 | const char *p; |
| 181 | int i; |
Tim Riker | c1ef7bd | 2006-01-25 00:08:53 +0000 | [diff] [blame] | 182 | __u32 in[8], buf[4]; |
Mike Frysinger | 1fd98e0 | 2005-05-09 22:10:42 +0000 | [diff] [blame] | 183 | |
| 184 | /* Initialize the default seed for the hash checksum functions */ |
| 185 | buf[0] = 0x67452301; |
| 186 | buf[1] = 0xefcdab89; |
| 187 | buf[2] = 0x98badcfe; |
| 188 | buf[3] = 0x10325476; |
| 189 | |
| 190 | /* Check to see if the seed is all zero's */ |
| 191 | if (seed) { |
| 192 | for (i=0; i < 4; i++) { |
| 193 | if (seed[i]) |
| 194 | break; |
| 195 | } |
| 196 | if (i < 4) |
| 197 | memcpy(buf, seed, sizeof(buf)); |
| 198 | } |
Tim Riker | c1ef7bd | 2006-01-25 00:08:53 +0000 | [diff] [blame] | 199 | |
Mike Frysinger | 1fd98e0 | 2005-05-09 22:10:42 +0000 | [diff] [blame] | 200 | switch (version) { |
| 201 | case EXT2_HASH_LEGACY: |
| 202 | hash = dx_hack_hash(name, len); |
| 203 | break; |
| 204 | case EXT2_HASH_HALF_MD4: |
| 205 | p = name; |
| 206 | while (len > 0) { |
| 207 | str2hashbuf(p, len, in, 8); |
| 208 | halfMD4Transform(buf, in); |
| 209 | len -= 32; |
| 210 | p += 32; |
| 211 | } |
| 212 | minor_hash = buf[2]; |
| 213 | hash = buf[1]; |
| 214 | break; |
| 215 | case EXT2_HASH_TEA: |
| 216 | p = name; |
| 217 | while (len > 0) { |
| 218 | str2hashbuf(p, len, in, 4); |
| 219 | TEA_transform(buf, in); |
| 220 | len -= 16; |
| 221 | p += 16; |
| 222 | } |
| 223 | hash = buf[0]; |
| 224 | minor_hash = buf[1]; |
| 225 | break; |
| 226 | default: |
| 227 | *ret_hash = 0; |
| 228 | return EXT2_ET_DIRHASH_UNSUPP; |
| 229 | } |
| 230 | *ret_hash = hash & ~1; |
| 231 | if (ret_minor_hash) |
| 232 | *ret_minor_hash = minor_hash; |
| 233 | return 0; |
| 234 | } |