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1// SPDX-License-Identifier: GPL-2.0-or-later
2/* Key to pathname encoder
3 *
4 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
5 * Written by David Howells (dhowells@redhat.com)
6 */
7
8#include <linux/slab.h>
9#include "internal.h"
10
11static const char cachefiles_charmap[64] =
12 "0123456789" /* 0 - 9 */
13 "abcdefghijklmnopqrstuvwxyz" /* 10 - 35 */
14 "ABCDEFGHIJKLMNOPQRSTUVWXYZ" /* 36 - 61 */
15 "_-" /* 62 - 63 */
16 ;
17
18static const char cachefiles_filecharmap[256] = {
19 /* we skip space and tab and control chars */
20 [33 ... 46] = 1, /* '!' -> '.' */
21 /* we skip '/' as it's significant to pathwalk */
22 [48 ... 127] = 1, /* '0' -> '~' */
23};
24
25/*
26 * turn the raw key into something cooked
27 * - the raw key should include the length in the two bytes at the front
28 * - the key may be up to 514 bytes in length (including the length word)
29 * - "base64" encode the strange keys, mapping 3 bytes of raw to four of
30 * cooked
31 * - need to cut the cooked key into 252 char lengths (189 raw bytes)
32 */
33char *cachefiles_cook_key(const u8 *raw, int keylen, uint8_t type)
34{
35 unsigned char csum, ch;
36 unsigned int acc;
37 char *key;
38 int loop, len, max, seg, mark, print;
39
40 _enter(",%d", keylen);
41
42 BUG_ON(keylen < 2 || keylen > 514);
43
44 csum = raw[0] + raw[1];
45 print = 1;
46 for (loop = 2; loop < keylen; loop++) {
47 ch = raw[loop];
48 csum += ch;
49 print &= cachefiles_filecharmap[ch];
50 }
51
52 if (print) {
53 /* if the path is usable ASCII, then we render it directly */
54 max = keylen - 2;
55 max += 2; /* two base64'd length chars on the front */
56 max += 5; /* @checksum/M */
57 max += 3 * 2; /* maximum number of segment dividers (".../M")
58 * is ((514 + 251) / 252) = 3
59 */
60 max += 1; /* NUL on end */
61 } else {
62 /* calculate the maximum length of the cooked key */
63 keylen = (keylen + 2) / 3;
64
65 max = keylen * 4;
66 max += 5; /* @checksum/M */
67 max += 3 * 2; /* maximum number of segment dividers (".../M")
68 * is ((514 + 188) / 189) = 3
69 */
70 max += 1; /* NUL on end */
71 }
72
73 max += 1; /* 2nd NUL on end */
74
75 _debug("max: %d", max);
76
77 key = kmalloc(max, cachefiles_gfp);
78 if (!key)
79 return NULL;
80
81 len = 0;
82
83 /* build the cooked key */
84 sprintf(key, "@%02x%c+", (unsigned) csum, 0);
85 len = 5;
86 mark = len - 1;
87
88 if (print) {
89 acc = *(uint16_t *) raw;
90 raw += 2;
91
92 key[len + 1] = cachefiles_charmap[acc & 63];
93 acc >>= 6;
94 key[len] = cachefiles_charmap[acc & 63];
95 len += 2;
96
97 seg = 250;
98 for (loop = keylen; loop > 0; loop--) {
99 if (seg <= 0) {
100 key[len++] = '\0';
101 mark = len;
102 key[len++] = '+';
103 seg = 252;
104 }
105
106 key[len++] = *raw++;
107 ASSERT(len < max);
108 }
109
110 switch (type) {
111 case FSCACHE_COOKIE_TYPE_INDEX: type = 'I'; break;
112 case FSCACHE_COOKIE_TYPE_DATAFILE: type = 'D'; break;
113 default: type = 'S'; break;
114 }
115 } else {
116 seg = 252;
117 for (loop = keylen; loop > 0; loop--) {
118 if (seg <= 0) {
119 key[len++] = '\0';
120 mark = len;
121 key[len++] = '+';
122 seg = 252;
123 }
124
125 acc = *raw++;
126 acc |= *raw++ << 8;
127 acc |= *raw++ << 16;
128
129 _debug("acc: %06x", acc);
130
131 key[len++] = cachefiles_charmap[acc & 63];
132 acc >>= 6;
133 key[len++] = cachefiles_charmap[acc & 63];
134 acc >>= 6;
135 key[len++] = cachefiles_charmap[acc & 63];
136 acc >>= 6;
137 key[len++] = cachefiles_charmap[acc & 63];
138
139 ASSERT(len < max);
140 }
141
142 switch (type) {
143 case FSCACHE_COOKIE_TYPE_INDEX: type = 'J'; break;
144 case FSCACHE_COOKIE_TYPE_DATAFILE: type = 'E'; break;
145 default: type = 'T'; break;
146 }
147 }
148
149 key[mark] = type;
150 key[len++] = 0;
151 key[len] = 0;
152
153 _leave(" = %p %d", key, len);
154 return key;
155}
1/* Key to pathname encoder
2 *
3 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
4 * Written by David Howells (dhowells@redhat.com)
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public Licence
8 * as published by the Free Software Foundation; either version
9 * 2 of the Licence, or (at your option) any later version.
10 */
11
12#include <linux/slab.h>
13#include "internal.h"
14
15static const char cachefiles_charmap[64] =
16 "0123456789" /* 0 - 9 */
17 "abcdefghijklmnopqrstuvwxyz" /* 10 - 35 */
18 "ABCDEFGHIJKLMNOPQRSTUVWXYZ" /* 36 - 61 */
19 "_-" /* 62 - 63 */
20 ;
21
22static const char cachefiles_filecharmap[256] = {
23 /* we skip space and tab and control chars */
24 [33 ... 46] = 1, /* '!' -> '.' */
25 /* we skip '/' as it's significant to pathwalk */
26 [48 ... 127] = 1, /* '0' -> '~' */
27};
28
29/*
30 * turn the raw key into something cooked
31 * - the raw key should include the length in the two bytes at the front
32 * - the key may be up to 514 bytes in length (including the length word)
33 * - "base64" encode the strange keys, mapping 3 bytes of raw to four of
34 * cooked
35 * - need to cut the cooked key into 252 char lengths (189 raw bytes)
36 */
37char *cachefiles_cook_key(const u8 *raw, int keylen, uint8_t type)
38{
39 unsigned char csum, ch;
40 unsigned int acc;
41 char *key;
42 int loop, len, max, seg, mark, print;
43
44 _enter(",%d", keylen);
45
46 BUG_ON(keylen < 2 || keylen > 514);
47
48 csum = raw[0] + raw[1];
49 print = 1;
50 for (loop = 2; loop < keylen; loop++) {
51 ch = raw[loop];
52 csum += ch;
53 print &= cachefiles_filecharmap[ch];
54 }
55
56 if (print) {
57 /* if the path is usable ASCII, then we render it directly */
58 max = keylen - 2;
59 max += 2; /* two base64'd length chars on the front */
60 max += 5; /* @checksum/M */
61 max += 3 * 2; /* maximum number of segment dividers (".../M")
62 * is ((514 + 251) / 252) = 3
63 */
64 max += 1; /* NUL on end */
65 } else {
66 /* calculate the maximum length of the cooked key */
67 keylen = (keylen + 2) / 3;
68
69 max = keylen * 4;
70 max += 5; /* @checksum/M */
71 max += 3 * 2; /* maximum number of segment dividers (".../M")
72 * is ((514 + 188) / 189) = 3
73 */
74 max += 1; /* NUL on end */
75 }
76
77 max += 1; /* 2nd NUL on end */
78
79 _debug("max: %d", max);
80
81 key = kmalloc(max, GFP_KERNEL);
82 if (!key)
83 return NULL;
84
85 len = 0;
86
87 /* build the cooked key */
88 sprintf(key, "@%02x%c+", (unsigned) csum, 0);
89 len = 5;
90 mark = len - 1;
91
92 if (print) {
93 acc = *(uint16_t *) raw;
94 raw += 2;
95
96 key[len + 1] = cachefiles_charmap[acc & 63];
97 acc >>= 6;
98 key[len] = cachefiles_charmap[acc & 63];
99 len += 2;
100
101 seg = 250;
102 for (loop = keylen; loop > 0; loop--) {
103 if (seg <= 0) {
104 key[len++] = '\0';
105 mark = len;
106 key[len++] = '+';
107 seg = 252;
108 }
109
110 key[len++] = *raw++;
111 ASSERT(len < max);
112 }
113
114 switch (type) {
115 case FSCACHE_COOKIE_TYPE_INDEX: type = 'I'; break;
116 case FSCACHE_COOKIE_TYPE_DATAFILE: type = 'D'; break;
117 default: type = 'S'; break;
118 }
119 } else {
120 seg = 252;
121 for (loop = keylen; loop > 0; loop--) {
122 if (seg <= 0) {
123 key[len++] = '\0';
124 mark = len;
125 key[len++] = '+';
126 seg = 252;
127 }
128
129 acc = *raw++;
130 acc |= *raw++ << 8;
131 acc |= *raw++ << 16;
132
133 _debug("acc: %06x", acc);
134
135 key[len++] = cachefiles_charmap[acc & 63];
136 acc >>= 6;
137 key[len++] = cachefiles_charmap[acc & 63];
138 acc >>= 6;
139 key[len++] = cachefiles_charmap[acc & 63];
140 acc >>= 6;
141 key[len++] = cachefiles_charmap[acc & 63];
142
143 ASSERT(len < max);
144 }
145
146 switch (type) {
147 case FSCACHE_COOKIE_TYPE_INDEX: type = 'J'; break;
148 case FSCACHE_COOKIE_TYPE_DATAFILE: type = 'E'; break;
149 default: type = 'T'; break;
150 }
151 }
152
153 key[mark] = type;
154 key[len++] = 0;
155 key[len] = 0;
156
157 _leave(" = %p %d", key, len);
158 return key;
159}