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
TEA_transform(__u32 buf[4],__u32 const in[])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 */
halfMD4Transform(__u32 buf[4],__u32 const in[])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 */
dx_hack_hash(const char * name,int len,int unsigned_flag)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
str2hashbuf(const char * msg,int len,__u32 * buf,int num,int unsigned_flag)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 */
ext2fs_dirhash(int version,const char * name,int len,const __u32 * seed,ext2_dirhash_t * ret_hash,ext2_dirhash_t * ret_minor_hash)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 */
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)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 }
308