1 /* 2 * dirhash.c -- Calculate the hash of a directory entry 3 * 4 * Copyright (c) 2001 Daniel Phillips 5 * 6 * Copyright (c) 2002 Theodore Ts'o. 7 * 8 * %Begin-Header% 9 * This file may be redistributed under the terms of the GNU Library 10 * General Public License, version 2. 11 * %End-Header% 12 */ 13 14 #include "config.h" 15 #include <stdio.h> 16 #include <string.h> 17 #include <limits.h> 18 19 #include "ext2_fs.h" 20 #include "ext2fs.h" 21 #include "ext2fsP.h" 22 23 #ifndef PATH_MAX 24 #define PATH_MAX 4096 25 #endif 26 27 /* 28 * Keyed 32-bit hash function using TEA in a Davis-Meyer function 29 * H0 = Key 30 * Hi = E Mi(Hi-1) + Hi-1 31 * 32 * (see Applied Cryptography, 2nd edition, p448). 33 * 34 * Jeremy Fitzhardinge <jeremy@zip.com.au> 1998 35 * 36 * This code is made available under the terms of the GPL 37 */ 38 #define DELTA 0x9E3779B9 39 40 static void TEA_transform(__u32 buf[4], __u32 const in[]) 41 { 42 __u32 sum = 0; 43 __u32 b0 = buf[0], b1 = buf[1]; 44 __u32 a = in[0], b = in[1], c = in[2], d = in[3]; 45 int n = 16; 46 47 do { 48 sum += DELTA; 49 b0 += ((b1 << 4)+a) ^ (b1+sum) ^ ((b1 >> 5)+b); 50 b1 += ((b0 << 4)+c) ^ (b0+sum) ^ ((b0 >> 5)+d); 51 } while(--n); 52 53 buf[0] += b0; 54 buf[1] += b1; 55 } 56 57 /* F, G and H are basic MD4 functions: selection, majority, parity */ 58 #define F(x, y, z) ((z) ^ ((x) & ((y) ^ (z)))) 59 #define G(x, y, z) (((x) & (y)) + (((x) ^ (y)) & (z))) 60 #define H(x, y, z) ((x) ^ (y) ^ (z)) 61 62 /* 63 * The generic round function. The application is so specific that 64 * we don't bother protecting all the arguments with parens, as is generally 65 * good macro practice, in favor of extra legibility. 66 * Rotation is separate from addition to prevent recomputation 67 */ 68 #define ROUND(f, a, b, c, d, x, s) \ 69 (a += f(b, c, d) + x, a = (a << s) | (a >> (32-s))) 70 #define K1 0 71 #define K2 013240474631UL 72 #define K3 015666365641UL 73 74 /* 75 * Basic cut-down MD4 transform. Returns only 32 bits of result. 76 */ 77 static void halfMD4Transform (__u32 buf[4], __u32 const in[]) 78 { 79 __u32 a = buf[0], b = buf[1], c = buf[2], d = buf[3]; 80 81 /* Round 1 */ 82 ROUND(F, a, b, c, d, in[0] + K1, 3); 83 ROUND(F, d, a, b, c, in[1] + K1, 7); 84 ROUND(F, c, d, a, b, in[2] + K1, 11); 85 ROUND(F, b, c, d, a, in[3] + K1, 19); 86 ROUND(F, a, b, c, d, in[4] + K1, 3); 87 ROUND(F, d, a, b, c, in[5] + K1, 7); 88 ROUND(F, c, d, a, b, in[6] + K1, 11); 89 ROUND(F, b, c, d, a, in[7] + K1, 19); 90 91 /* Round 2 */ 92 ROUND(G, a, b, c, d, in[1] + K2, 3); 93 ROUND(G, d, a, b, c, in[3] + K2, 5); 94 ROUND(G, c, d, a, b, in[5] + K2, 9); 95 ROUND(G, b, c, d, a, in[7] + K2, 13); 96 ROUND(G, a, b, c, d, in[0] + K2, 3); 97 ROUND(G, d, a, b, c, in[2] + K2, 5); 98 ROUND(G, c, d, a, b, in[4] + K2, 9); 99 ROUND(G, b, c, d, a, in[6] + K2, 13); 100 101 /* Round 3 */ 102 ROUND(H, a, b, c, d, in[3] + K3, 3); 103 ROUND(H, d, a, b, c, in[7] + K3, 9); 104 ROUND(H, c, d, a, b, in[2] + K3, 11); 105 ROUND(H, b, c, d, a, in[6] + K3, 15); 106 ROUND(H, a, b, c, d, in[1] + K3, 3); 107 ROUND(H, d, a, b, c, in[5] + K3, 9); 108 ROUND(H, c, d, a, b, in[0] + K3, 11); 109 ROUND(H, b, c, d, a, in[4] + K3, 15); 110 111 buf[0] += a; 112 buf[1] += b; 113 buf[2] += c; 114 buf[3] += d; 115 } 116 117 #undef ROUND 118 #undef F 119 #undef G 120 #undef H 121 #undef K1 122 #undef K2 123 #undef K3 124 125 /* The old legacy hash */ 126 static ext2_dirhash_t dx_hack_hash (const char *name, int len, 127 int unsigned_flag) 128 { 129 __u32 hash, hash0 = 0x12a3fe2d, hash1 = 0x37abe8f9; 130 const unsigned char *ucp = (const unsigned char *) name; 131 const signed char *scp = (const signed char *) name; 132 int c; 133 134 while (len--) { 135 if (unsigned_flag) 136 c = (int) *ucp++; 137 else 138 c = (int) *scp++; 139 hash = hash1 + (hash0 ^ (c * 7152373)); 140 141 if (hash & 0x80000000) hash -= 0x7fffffff; 142 hash1 = hash0; 143 hash0 = hash; 144 } 145 return (hash0 << 1); 146 } 147 148 static void str2hashbuf(const char *msg, int len, __u32 *buf, int num, 149 int unsigned_flag) 150 { 151 __u32 pad, val; 152 int i, c; 153 const unsigned char *ucp = (const unsigned char *) msg; 154 const signed char *scp = (const signed char *) msg; 155 156 pad = (__u32)len | ((__u32)len << 8); 157 pad |= pad << 16; 158 159 val = pad; 160 if (len > num*4) 161 len = num * 4; 162 for (i=0; i < len; i++) { 163 if (unsigned_flag) 164 c = (int) ucp[i]; 165 else 166 c = (int) scp[i]; 167 168 val = c + (val << 8); 169 if ((i % 4) == 3) { 170 *buf++ = val; 171 val = pad; 172 num--; 173 } 174 } 175 if (--num >= 0) 176 *buf++ = val; 177 while (--num >= 0) 178 *buf++ = pad; 179 } 180 181 /* 182 * Returns the hash of a filename. If len is 0 and name is NULL, then 183 * this function can be used to test whether or not a hash version is 184 * supported. 185 * 186 * The seed is an 4 longword (32 bits) "secret" which can be used to 187 * uniquify a hash. If the seed is all zero's, then some default seed 188 * may be used. 189 * 190 * A particular hash version specifies whether or not the seed is 191 * represented, and whether or not the returned hash is 32 bits or 64 192 * bits. 32 bit hashes will return 0 for the minor hash. 193 * 194 * This function doesn't do any normalization or casefolding of the 195 * input string. To take charset encoding into account, use 196 * ext2fs_dirhash2. 197 * 198 */ 199 errcode_t ext2fs_dirhash(int version, const char *name, int len, 200 const __u32 *seed, 201 ext2_dirhash_t *ret_hash, 202 ext2_dirhash_t *ret_minor_hash) 203 { 204 __u32 hash; 205 __u32 minor_hash = 0; 206 const char *p; 207 int i; 208 __u32 in[8], buf[4]; 209 int unsigned_flag = 0; 210 211 /* Initialize the default seed for the hash checksum functions */ 212 buf[0] = 0x67452301; 213 buf[1] = 0xefcdab89; 214 buf[2] = 0x98badcfe; 215 buf[3] = 0x10325476; 216 217 /* Check to see if the seed is all zero's */ 218 if (seed) { 219 for (i=0; i < 4; i++) { 220 if (seed[i]) 221 break; 222 } 223 if (i < 4) 224 memcpy(buf, seed, sizeof(buf)); 225 } 226 227 switch (version) { 228 case EXT2_HASH_LEGACY_UNSIGNED: 229 unsigned_flag++; 230 /* fallthrough */ 231 case EXT2_HASH_LEGACY: 232 hash = dx_hack_hash(name, len, unsigned_flag); 233 break; 234 case EXT2_HASH_HALF_MD4_UNSIGNED: 235 unsigned_flag++; 236 /* fallthrough */ 237 case EXT2_HASH_HALF_MD4: 238 p = name; 239 while (len > 0) { 240 str2hashbuf(p, len, in, 8, unsigned_flag); 241 halfMD4Transform(buf, in); 242 len -= 32; 243 p += 32; 244 } 245 minor_hash = buf[2]; 246 hash = buf[1]; 247 break; 248 case EXT2_HASH_TEA_UNSIGNED: 249 unsigned_flag++; 250 /* fallthrough */ 251 case EXT2_HASH_TEA: 252 p = name; 253 while (len > 0) { 254 str2hashbuf(p, len, in, 4, unsigned_flag); 255 TEA_transform(buf, in); 256 len -= 16; 257 p += 16; 258 } 259 hash = buf[0]; 260 minor_hash = buf[1]; 261 break; 262 default: 263 *ret_hash = 0; 264 return EXT2_ET_DIRHASH_UNSUPP; 265 } 266 *ret_hash = hash & ~1; 267 if (ret_minor_hash) 268 *ret_minor_hash = minor_hash; 269 return 0; 270 } 271 272 /* 273 * Returns the hash of a filename considering normalization and 274 * casefolding. This is a wrapper around ext2fs_dirhash with string 275 * encoding support based on the nls_table and the flags. Check 276 * ext2fs_dirhash for documentation on the input and output parameters. 277 */ 278 errcode_t ext2fs_dirhash2(int version, const char *name, int len, 279 const struct ext2fs_nls_table *charset, 280 int hash_flags, const __u32 *seed, 281 ext2_dirhash_t *ret_hash, 282 ext2_dirhash_t *ret_minor_hash) 283 { 284 errcode_t r; 285 int dlen; 286 287 if (len && charset && (hash_flags & EXT4_CASEFOLD_FL)) { 288 char buff[PATH_MAX]; 289 290 dlen = charset->ops->casefold(charset, 291 (const unsigned char *) name, len, 292 (unsigned char *) buff, sizeof(buff)); 293 if (dlen < 0) { 294 if (dlen == -EINVAL) 295 goto opaque_seq; 296 297 return dlen; 298 } 299 r = ext2fs_dirhash(version, buff, dlen, seed, ret_hash, 300 ret_minor_hash); 301 return r; 302 } 303 304 opaque_seq: 305 return ext2fs_dirhash(version, name, len, seed, ret_hash, 306 ret_minor_hash); 307 }