1*4882a593Smuzhiyun // SPDX-License-Identifier: GPL-2.0
2*4882a593Smuzhiyun /*
3*4882a593Smuzhiyun * fs/f2fs/hash.c
4*4882a593Smuzhiyun *
5*4882a593Smuzhiyun * Copyright (c) 2012 Samsung Electronics Co., Ltd.
6*4882a593Smuzhiyun * http://www.samsung.com/
7*4882a593Smuzhiyun *
8*4882a593Smuzhiyun * Portions of this code from linux/fs/ext3/hash.c
9*4882a593Smuzhiyun *
10*4882a593Smuzhiyun * Copyright (C) 2002 by Theodore Ts'o
11*4882a593Smuzhiyun */
12*4882a593Smuzhiyun #include <linux/types.h>
13*4882a593Smuzhiyun #include <linux/fs.h>
14*4882a593Smuzhiyun #include <linux/f2fs_fs.h>
15*4882a593Smuzhiyun #include <linux/pagemap.h>
16*4882a593Smuzhiyun #include <linux/unicode.h>
17*4882a593Smuzhiyun
18*4882a593Smuzhiyun #include "f2fs.h"
19*4882a593Smuzhiyun
20*4882a593Smuzhiyun /*
21*4882a593Smuzhiyun * Hashing code copied from ext3
22*4882a593Smuzhiyun */
23*4882a593Smuzhiyun #define DELTA 0x9E3779B9
24*4882a593Smuzhiyun
TEA_transform(unsigned int buf[4],unsigned int const in[])25*4882a593Smuzhiyun static void TEA_transform(unsigned int buf[4], unsigned int const in[])
26*4882a593Smuzhiyun {
27*4882a593Smuzhiyun __u32 sum = 0;
28*4882a593Smuzhiyun __u32 b0 = buf[0], b1 = buf[1];
29*4882a593Smuzhiyun __u32 a = in[0], b = in[1], c = in[2], d = in[3];
30*4882a593Smuzhiyun int n = 16;
31*4882a593Smuzhiyun
32*4882a593Smuzhiyun do {
33*4882a593Smuzhiyun sum += DELTA;
34*4882a593Smuzhiyun b0 += ((b1 << 4)+a) ^ (b1+sum) ^ ((b1 >> 5)+b);
35*4882a593Smuzhiyun b1 += ((b0 << 4)+c) ^ (b0+sum) ^ ((b0 >> 5)+d);
36*4882a593Smuzhiyun } while (--n);
37*4882a593Smuzhiyun
38*4882a593Smuzhiyun buf[0] += b0;
39*4882a593Smuzhiyun buf[1] += b1;
40*4882a593Smuzhiyun }
41*4882a593Smuzhiyun
str2hashbuf(const unsigned char * msg,size_t len,unsigned int * buf,int num)42*4882a593Smuzhiyun static void str2hashbuf(const unsigned char *msg, size_t len,
43*4882a593Smuzhiyun unsigned int *buf, int num)
44*4882a593Smuzhiyun {
45*4882a593Smuzhiyun unsigned pad, val;
46*4882a593Smuzhiyun int i;
47*4882a593Smuzhiyun
48*4882a593Smuzhiyun pad = (__u32)len | ((__u32)len << 8);
49*4882a593Smuzhiyun pad |= pad << 16;
50*4882a593Smuzhiyun
51*4882a593Smuzhiyun val = pad;
52*4882a593Smuzhiyun if (len > num * 4)
53*4882a593Smuzhiyun len = num * 4;
54*4882a593Smuzhiyun for (i = 0; i < len; i++) {
55*4882a593Smuzhiyun if ((i % 4) == 0)
56*4882a593Smuzhiyun val = pad;
57*4882a593Smuzhiyun val = msg[i] + (val << 8);
58*4882a593Smuzhiyun if ((i % 4) == 3) {
59*4882a593Smuzhiyun *buf++ = val;
60*4882a593Smuzhiyun val = pad;
61*4882a593Smuzhiyun num--;
62*4882a593Smuzhiyun }
63*4882a593Smuzhiyun }
64*4882a593Smuzhiyun if (--num >= 0)
65*4882a593Smuzhiyun *buf++ = val;
66*4882a593Smuzhiyun while (--num >= 0)
67*4882a593Smuzhiyun *buf++ = pad;
68*4882a593Smuzhiyun }
69*4882a593Smuzhiyun
TEA_hash_name(const u8 * p,size_t len)70*4882a593Smuzhiyun static u32 TEA_hash_name(const u8 *p, size_t len)
71*4882a593Smuzhiyun {
72*4882a593Smuzhiyun __u32 in[8], buf[4];
73*4882a593Smuzhiyun
74*4882a593Smuzhiyun /* Initialize the default seed for the hash checksum functions */
75*4882a593Smuzhiyun buf[0] = 0x67452301;
76*4882a593Smuzhiyun buf[1] = 0xefcdab89;
77*4882a593Smuzhiyun buf[2] = 0x98badcfe;
78*4882a593Smuzhiyun buf[3] = 0x10325476;
79*4882a593Smuzhiyun
80*4882a593Smuzhiyun while (1) {
81*4882a593Smuzhiyun str2hashbuf(p, len, in, 4);
82*4882a593Smuzhiyun TEA_transform(buf, in);
83*4882a593Smuzhiyun p += 16;
84*4882a593Smuzhiyun if (len <= 16)
85*4882a593Smuzhiyun break;
86*4882a593Smuzhiyun len -= 16;
87*4882a593Smuzhiyun }
88*4882a593Smuzhiyun return buf[0] & ~F2FS_HASH_COL_BIT;
89*4882a593Smuzhiyun }
90*4882a593Smuzhiyun
91*4882a593Smuzhiyun /*
92*4882a593Smuzhiyun * Compute @fname->hash. For all directories, @fname->disk_name must be set.
93*4882a593Smuzhiyun * For casefolded directories, @fname->usr_fname must be set, and also
94*4882a593Smuzhiyun * @fname->cf_name if the filename is valid Unicode and is not "." or "..".
95*4882a593Smuzhiyun */
f2fs_hash_filename(const struct inode * dir,struct f2fs_filename * fname)96*4882a593Smuzhiyun void f2fs_hash_filename(const struct inode *dir, struct f2fs_filename *fname)
97*4882a593Smuzhiyun {
98*4882a593Smuzhiyun const u8 *name = fname->disk_name.name;
99*4882a593Smuzhiyun size_t len = fname->disk_name.len;
100*4882a593Smuzhiyun
101*4882a593Smuzhiyun WARN_ON_ONCE(!name);
102*4882a593Smuzhiyun
103*4882a593Smuzhiyun if (is_dot_dotdot(name, len)) {
104*4882a593Smuzhiyun fname->hash = 0;
105*4882a593Smuzhiyun return;
106*4882a593Smuzhiyun }
107*4882a593Smuzhiyun
108*4882a593Smuzhiyun #ifdef CONFIG_UNICODE
109*4882a593Smuzhiyun if (IS_CASEFOLDED(dir)) {
110*4882a593Smuzhiyun /*
111*4882a593Smuzhiyun * If the casefolded name is provided, hash it instead of the
112*4882a593Smuzhiyun * on-disk name. If the casefolded name is *not* provided, that
113*4882a593Smuzhiyun * should only be because the name wasn't valid Unicode or was
114*4882a593Smuzhiyun * "." or "..", so fall back to treating the name as an opaque
115*4882a593Smuzhiyun * byte sequence. Note that to handle encrypted directories,
116*4882a593Smuzhiyun * the fallback must use usr_fname (plaintext) rather than
117*4882a593Smuzhiyun * disk_name (ciphertext).
118*4882a593Smuzhiyun */
119*4882a593Smuzhiyun WARN_ON_ONCE(!fname->usr_fname->name);
120*4882a593Smuzhiyun if (fname->cf_name.name) {
121*4882a593Smuzhiyun name = fname->cf_name.name;
122*4882a593Smuzhiyun len = fname->cf_name.len;
123*4882a593Smuzhiyun } else {
124*4882a593Smuzhiyun name = fname->usr_fname->name;
125*4882a593Smuzhiyun len = fname->usr_fname->len;
126*4882a593Smuzhiyun }
127*4882a593Smuzhiyun if (IS_ENCRYPTED(dir)) {
128*4882a593Smuzhiyun struct qstr tmp = QSTR_INIT(name, len);
129*4882a593Smuzhiyun
130*4882a593Smuzhiyun fname->hash =
131*4882a593Smuzhiyun cpu_to_le32(fscrypt_fname_siphash(dir, &tmp));
132*4882a593Smuzhiyun return;
133*4882a593Smuzhiyun }
134*4882a593Smuzhiyun }
135*4882a593Smuzhiyun #endif
136*4882a593Smuzhiyun fname->hash = cpu_to_le32(TEA_hash_name(name, len));
137*4882a593Smuzhiyun }
138