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