Line data Source code
1 : // SPDX-License-Identifier: GPL-2.0
2 : /*
3 : * linux/fs/ext4/hash.c
4 : *
5 : * Copyright (C) 2002 by Theodore Ts'o
6 : */
7 :
8 : #include <linux/fs.h>
9 : #include <linux/unicode.h>
10 : #include <linux/compiler.h>
11 : #include <linux/bitops.h>
12 : #include "ext4.h"
13 :
14 : #define DELTA 0x9E3779B9
15 :
16 0 : static void TEA_transform(__u32 buf[4], __u32 const in[])
17 : {
18 0 : __u32 sum = 0;
19 0 : __u32 b0 = buf[0], b1 = buf[1];
20 0 : __u32 a = in[0], b = in[1], c = in[2], d = in[3];
21 0 : int n = 16;
22 :
23 0 : do {
24 0 : sum += DELTA;
25 0 : b0 += ((b1 << 4)+a) ^ (b1+sum) ^ ((b1 >> 5)+b);
26 0 : b1 += ((b0 << 4)+c) ^ (b0+sum) ^ ((b0 >> 5)+d);
27 0 : } while (--n);
28 :
29 0 : buf[0] += b0;
30 0 : buf[1] += b1;
31 0 : }
32 :
33 : /* F, G and H are basic MD4 functions: selection, majority, parity */
34 : #define F(x, y, z) ((z) ^ ((x) & ((y) ^ (z))))
35 : #define G(x, y, z) (((x) & (y)) + (((x) ^ (y)) & (z)))
36 : #define H(x, y, z) ((x) ^ (y) ^ (z))
37 :
38 : /*
39 : * The generic round function. The application is so specific that
40 : * we don't bother protecting all the arguments with parens, as is generally
41 : * good macro practice, in favor of extra legibility.
42 : * Rotation is separate from addition to prevent recomputation
43 : */
44 : #define ROUND(f, a, b, c, d, x, s) \
45 : (a += f(b, c, d) + x, a = rol32(a, s))
46 : #define K1 0
47 : #define K2 013240474631UL
48 : #define K3 015666365641UL
49 :
50 : /*
51 : * Basic cut-down MD4 transform. Returns only 32 bits of result.
52 : */
53 166474028 : static __u32 half_md4_transform(__u32 buf[4], __u32 const in[8])
54 : {
55 166474028 : __u32 a = buf[0], b = buf[1], c = buf[2], d = buf[3];
56 :
57 : /* Round 1 */
58 166474028 : ROUND(F, a, b, c, d, in[0] + K1, 3);
59 166474028 : ROUND(F, d, a, b, c, in[1] + K1, 7);
60 166474028 : ROUND(F, c, d, a, b, in[2] + K1, 11);
61 166474028 : ROUND(F, b, c, d, a, in[3] + K1, 19);
62 166474028 : ROUND(F, a, b, c, d, in[4] + K1, 3);
63 166474028 : ROUND(F, d, a, b, c, in[5] + K1, 7);
64 166474028 : ROUND(F, c, d, a, b, in[6] + K1, 11);
65 166474028 : ROUND(F, b, c, d, a, in[7] + K1, 19);
66 :
67 : /* Round 2 */
68 166474028 : ROUND(G, a, b, c, d, in[1] + K2, 3);
69 166474028 : ROUND(G, d, a, b, c, in[3] + K2, 5);
70 166474028 : ROUND(G, c, d, a, b, in[5] + K2, 9);
71 166474028 : ROUND(G, b, c, d, a, in[7] + K2, 13);
72 166474028 : ROUND(G, a, b, c, d, in[0] + K2, 3);
73 166474028 : ROUND(G, d, a, b, c, in[2] + K2, 5);
74 166474028 : ROUND(G, c, d, a, b, in[4] + K2, 9);
75 166474028 : ROUND(G, b, c, d, a, in[6] + K2, 13);
76 :
77 : /* Round 3 */
78 166474028 : ROUND(H, a, b, c, d, in[3] + K3, 3);
79 166474028 : ROUND(H, d, a, b, c, in[7] + K3, 9);
80 166474028 : ROUND(H, c, d, a, b, in[2] + K3, 11);
81 166474028 : ROUND(H, b, c, d, a, in[6] + K3, 15);
82 166474028 : ROUND(H, a, b, c, d, in[1] + K3, 3);
83 166474028 : ROUND(H, d, a, b, c, in[5] + K3, 9);
84 166474028 : ROUND(H, c, d, a, b, in[0] + K3, 11);
85 166474028 : ROUND(H, b, c, d, a, in[4] + K3, 15);
86 :
87 166474028 : buf[0] += a;
88 166474028 : buf[1] += b;
89 166474028 : buf[2] += c;
90 166474028 : buf[3] += d;
91 :
92 166474028 : return buf[1]; /* "most hashed" word */
93 : }
94 : #undef ROUND
95 : #undef K1
96 : #undef K2
97 : #undef K3
98 : #undef F
99 : #undef G
100 : #undef H
101 :
102 : /* The old legacy hash */
103 0 : static __u32 dx_hack_hash_unsigned(const char *name, int len)
104 : {
105 0 : __u32 hash, hash0 = 0x12a3fe2d, hash1 = 0x37abe8f9;
106 0 : const unsigned char *ucp = (const unsigned char *) name;
107 :
108 0 : while (len--) {
109 0 : hash = hash1 + (hash0 ^ (((int) *ucp++) * 7152373));
110 :
111 0 : if (hash & 0x80000000)
112 0 : hash -= 0x7fffffff;
113 : hash1 = hash0;
114 : hash0 = hash;
115 : }
116 0 : return hash0 << 1;
117 : }
118 :
119 0 : static __u32 dx_hack_hash_signed(const char *name, int len)
120 : {
121 0 : __u32 hash, hash0 = 0x12a3fe2d, hash1 = 0x37abe8f9;
122 0 : const signed char *scp = (const signed char *) name;
123 :
124 0 : while (len--) {
125 0 : hash = hash1 + (hash0 ^ (((int) *scp++) * 7152373));
126 :
127 0 : if (hash & 0x80000000)
128 0 : hash -= 0x7fffffff;
129 : hash1 = hash0;
130 : hash0 = hash;
131 : }
132 0 : return hash0 << 1;
133 : }
134 :
135 166468943 : static void str2hashbuf_signed(const char *msg, int len, __u32 *buf, int num)
136 : {
137 166468943 : __u32 pad, val;
138 166468943 : int i;
139 166468943 : const signed char *scp = (const signed char *) msg;
140 :
141 166468943 : pad = (__u32)len | ((__u32)len << 8);
142 166468943 : pad |= pad << 16;
143 :
144 166468943 : val = pad;
145 166468943 : if (len > num*4)
146 : len = num * 4;
147 1193751461 : for (i = 0; i < len; i++) {
148 1027282518 : val = ((int) scp[i]) + (val << 8);
149 1027282518 : if ((i % 4) == 3) {
150 222594934 : *buf++ = val;
151 222594934 : val = pad;
152 222594934 : num--;
153 : }
154 : }
155 166468943 : if (--num >= 0)
156 158178756 : *buf++ = val;
157 1117406670 : while (--num >= 0)
158 950937727 : *buf++ = pad;
159 166468943 : }
160 :
161 0 : static void str2hashbuf_unsigned(const char *msg, int len, __u32 *buf, int num)
162 : {
163 0 : __u32 pad, val;
164 0 : int i;
165 0 : const unsigned char *ucp = (const unsigned char *) msg;
166 :
167 0 : pad = (__u32)len | ((__u32)len << 8);
168 0 : pad |= pad << 16;
169 :
170 0 : val = pad;
171 0 : if (len > num*4)
172 : len = num * 4;
173 0 : for (i = 0; i < len; i++) {
174 0 : val = ((int) ucp[i]) + (val << 8);
175 0 : if ((i % 4) == 3) {
176 0 : *buf++ = val;
177 0 : val = pad;
178 0 : num--;
179 : }
180 : }
181 0 : if (--num >= 0)
182 0 : *buf++ = val;
183 0 : while (--num >= 0)
184 0 : *buf++ = pad;
185 0 : }
186 :
187 : /*
188 : * Returns the hash of a filename. If len is 0 and name is NULL, then
189 : * this function can be used to test whether or not a hash version is
190 : * supported.
191 : *
192 : * The seed is an 4 longword (32 bits) "secret" which can be used to
193 : * uniquify a hash. If the seed is all zero's, then some default seed
194 : * may be used.
195 : *
196 : * A particular hash version specifies whether or not the seed is
197 : * represented, and whether or not the returned hash is 32 bits or 64
198 : * bits. 32 bit hashes will return 0 for the minor hash.
199 : */
200 159231420 : static int __ext4fs_dirhash(const struct inode *dir, const char *name, int len,
201 : struct dx_hash_info *hinfo)
202 : {
203 159231420 : __u32 hash;
204 159231420 : __u32 minor_hash = 0;
205 159231420 : const char *p;
206 159231420 : int i;
207 159231420 : __u32 in[8], buf[4];
208 159231420 : void (*str2hashbuf)(const char *, int, __u32 *, int) =
209 : str2hashbuf_signed;
210 :
211 : /* Initialize the default seed for the hash checksum functions */
212 159231420 : buf[0] = 0x67452301;
213 159231420 : buf[1] = 0xefcdab89;
214 159231420 : buf[2] = 0x98badcfe;
215 159231420 : buf[3] = 0x10325476;
216 :
217 : /* Check to see if the seed is all zero's */
218 159231420 : if (hinfo->seed) {
219 159231420 : for (i = 0; i < 4; i++) {
220 159230481 : if (hinfo->seed[i]) {
221 159230481 : memcpy(buf, hinfo->seed, sizeof(buf));
222 159230481 : break;
223 : }
224 : }
225 : }
226 :
227 159231420 : switch (hinfo->hash_version) {
228 0 : case DX_HASH_LEGACY_UNSIGNED:
229 0 : hash = dx_hack_hash_unsigned(name, len);
230 0 : break;
231 0 : case DX_HASH_LEGACY:
232 0 : hash = dx_hack_hash_signed(name, len);
233 0 : break;
234 0 : case DX_HASH_HALF_MD4_UNSIGNED:
235 0 : str2hashbuf = str2hashbuf_unsigned;
236 159231420 : fallthrough;
237 159231420 : case DX_HASH_HALF_MD4:
238 159231420 : p = name;
239 325699505 : while (len > 0) {
240 166473886 : (*str2hashbuf)(p, len, in, 8);
241 166467867 : half_md4_transform(buf, in);
242 166468085 : len -= 32;
243 166468085 : p += 32;
244 : }
245 159225619 : minor_hash = buf[2];
246 159225619 : hash = buf[1];
247 159225619 : break;
248 0 : case DX_HASH_TEA_UNSIGNED:
249 0 : str2hashbuf = str2hashbuf_unsigned;
250 0 : fallthrough;
251 0 : case DX_HASH_TEA:
252 0 : p = name;
253 0 : while (len > 0) {
254 0 : (*str2hashbuf)(p, len, in, 4);
255 0 : TEA_transform(buf, in);
256 0 : len -= 16;
257 0 : p += 16;
258 : }
259 0 : hash = buf[0];
260 0 : minor_hash = buf[1];
261 0 : break;
262 0 : case DX_HASH_SIPHASH:
263 : {
264 0 : struct qstr qname = QSTR_INIT(name, len);
265 0 : __u64 combined_hash;
266 :
267 0 : if (fscrypt_has_encryption_key(dir)) {
268 : combined_hash = fscrypt_fname_siphash(dir, &qname);
269 : } else {
270 0 : ext4_warning_inode(dir, "Siphash requires key");
271 0 : return -1;
272 : }
273 :
274 : hash = (__u32)(combined_hash >> 32);
275 : minor_hash = (__u32)combined_hash;
276 : break;
277 : }
278 0 : default:
279 0 : hinfo->hash = 0;
280 0 : hinfo->minor_hash = 0;
281 0 : ext4_warning(dir->i_sb,
282 : "invalid/unsupported hash tree version %u",
283 : hinfo->hash_version);
284 0 : return -EINVAL;
285 : }
286 159225619 : hash = hash & ~1;
287 159225619 : if (hash == (EXT4_HTREE_EOF_32BIT << 1))
288 0 : hash = (EXT4_HTREE_EOF_32BIT - 1) << 1;
289 159225619 : hinfo->hash = hash;
290 159225619 : hinfo->minor_hash = minor_hash;
291 159225619 : return 0;
292 : }
293 :
294 159236203 : int ext4fs_dirhash(const struct inode *dir, const char *name, int len,
295 : struct dx_hash_info *hinfo)
296 : {
297 : #if IS_ENABLED(CONFIG_UNICODE)
298 : const struct unicode_map *um = dir->i_sb->s_encoding;
299 : int r, dlen;
300 : unsigned char *buff;
301 : struct qstr qstr = {.name = name, .len = len };
302 :
303 : if (len && IS_CASEFOLDED(dir) && um &&
304 : (!IS_ENCRYPTED(dir) || fscrypt_has_encryption_key(dir))) {
305 : buff = kzalloc(sizeof(char) * PATH_MAX, GFP_KERNEL);
306 : if (!buff)
307 : return -ENOMEM;
308 :
309 : dlen = utf8_casefold(um, &qstr, buff, PATH_MAX);
310 : if (dlen < 0) {
311 : kfree(buff);
312 : goto opaque_seq;
313 : }
314 :
315 : r = __ext4fs_dirhash(dir, buff, dlen, hinfo);
316 :
317 : kfree(buff);
318 : return r;
319 : }
320 : opaque_seq:
321 : #endif
322 159236203 : return __ext4fs_dirhash(dir, name, len, hinfo);
323 : }
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