1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * fs/f2fs/hash.c
4 *
5 * Copyright (c) 2012 Samsung Electronics Co., Ltd.
6 * http://www.samsung.com/
7 *
8 * Portions of this code from linux/fs/ext3/hash.c
9 *
10 * Copyright (C) 2002 by Theodore Ts'o
11 */
12 #include <linux/types.h>
13 #include <linux/fs.h>
14 #include <linux/f2fs_fs.h>
15 #include <linux/pagemap.h>
16 #include <linux/unicode.h>
17
18 #include "f2fs.h"
19
20 /*
21 * Hashing code copied from ext3
22 */
23 #define DELTA 0x9E3779B9
24
25 static void TEA_transform(unsigned int buf[4], unsigned int const in[])
26 {
27 __u32 sum = 0;
28 __u32 b0 = buf[0], b1 = buf[1];
29 __u32 a = in[0], b = in[1], c = in[2], d = in[3];
30 int n = 16;
31
32 do {
33 sum += DELTA;
34 b0 += ((b1 << 4)+a) ^ (b1+sum) ^ ((b1 >> 5)+b);
35 b1 += ((b0 << 4)+c) ^ (b0+sum) ^ ((b0 >> 5)+d);
36 } while (--n);
37
38 buf[0] += b0;
39 buf[1] += b1;
40 }
41
42 static void str2hashbuf(const unsigned char *msg, size_t len,
43 unsigned int *buf, int num)
44 {
45 unsigned pad, val;
46 int i;
47
48 pad = (__u32)len | ((__u32)len << 8);
49 pad |= pad << 16;
50
51 val = pad;
52 if (len > num * 4)
53 len = num * 4;
54 for (i = 0; i < len; i++) {
55 if ((i % 4) == 0)
56 val = pad;
57 val = msg[i] + (val << 8);
58 if ((i % 4) == 3) {
59 *buf++ = val;
60 val = pad;
61 num--;
62 }
63 }
64 if (--num >= 0)
65 *buf++ = val;
66 while (--num >= 0)
67 *buf++ = pad;
68 }
69
70 static u32 TEA_hash_name(const u8 *p, size_t len)
71 {
72 __u32 in[8], buf[4];
73
74 /* Initialize the default seed for the hash checksum functions */
75 buf[0] = 0x67452301;
76 buf[1] = 0xefcdab89;
77 buf[2] = 0x98badcfe;
78 buf[3] = 0x10325476;
79
80 while (1) {
81 str2hashbuf(p, len, in, 4);
82 TEA_transform(buf, in);
83 p += 16;
84 if (len <= 16)
85 break;
86 len -= 16;
87 }
88 return buf[0] & ~F2FS_HASH_COL_BIT;
89 }
90
91 /*
92 * Compute @fname->hash. For all directories, @fname->disk_name must be set.
93 * For casefolded directories, @fname->usr_fname must be set, and also
94 * @fname->cf_name if the filename is valid Unicode and is not "." or "..".
95 */
96 void f2fs_hash_filename(const struct inode *dir, struct f2fs_filename *fname)
97 {
98 const u8 *name = fname->disk_name.name;
99 size_t len = fname->disk_name.len;
100
101 WARN_ON_ONCE(!name);
102
103 if (is_dot_dotdot(name, len)) {
104 fname->hash = 0;
105 return;
106 }
107
108 #if IS_ENABLED(CONFIG_UNICODE)
109 if (IS_CASEFOLDED(dir)) {
110 /*
111 * If the casefolded name is provided, hash it instead of the
112 * on-disk name. If the casefolded name is *not* provided, that
113 * should only be because the name wasn't valid Unicode or was
114 * "." or "..", so fall back to treating the name as an opaque
115 * byte sequence. Note that to handle encrypted directories,
116 * the fallback must use usr_fname (plaintext) rather than
117 * disk_name (ciphertext).
118 */
119 WARN_ON_ONCE(!fname->usr_fname->name);
120 if (fname->cf_name.name) {
121 name = fname->cf_name.name;
122 len = fname->cf_name.len;
123 } else {
124 name = fname->usr_fname->name;
125 len = fname->usr_fname->len;
126 }
127 if (IS_ENCRYPTED(dir)) {
128 struct qstr tmp = QSTR_INIT(name, len);
129
130 fname->hash =
131 cpu_to_le32(fscrypt_fname_siphash(dir, &tmp));
132 return;
133 }
134 }
135 #endif
136 fname->hash = cpu_to_le32(TEA_hash_name(name, len));
137 }
138
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