156 lines
3.5 KiB
C
156 lines
3.5 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
|
|
/* Key to pathname encoder
|
|
*
|
|
* Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
|
|
* Written by David Howells (dhowells@redhat.com)
|
|
*/
|
|
|
|
#include <linux/slab.h>
|
|
#include "internal.h"
|
|
|
|
static const char cachefiles_charmap[64] =
|
|
"0123456789" /* 0 - 9 */
|
|
"abcdefghijklmnopqrstuvwxyz" /* 10 - 35 */
|
|
"ABCDEFGHIJKLMNOPQRSTUVWXYZ" /* 36 - 61 */
|
|
"_-" /* 62 - 63 */
|
|
;
|
|
|
|
static const char cachefiles_filecharmap[256] = {
|
|
/* we skip space and tab and control chars */
|
|
[33 ... 46] = 1, /* '!' -> '.' */
|
|
/* we skip '/' as it's significant to pathwalk */
|
|
[48 ... 127] = 1, /* '0' -> '~' */
|
|
};
|
|
|
|
/*
|
|
* turn the raw key into something cooked
|
|
* - the raw key should include the length in the two bytes at the front
|
|
* - the key may be up to 514 bytes in length (including the length word)
|
|
* - "base64" encode the strange keys, mapping 3 bytes of raw to four of
|
|
* cooked
|
|
* - need to cut the cooked key into 252 char lengths (189 raw bytes)
|
|
*/
|
|
char *cachefiles_cook_key(const u8 *raw, int keylen, uint8_t type)
|
|
{
|
|
unsigned char csum, ch;
|
|
unsigned int acc;
|
|
char *key;
|
|
int loop, len, max, seg, mark, print;
|
|
|
|
_enter(",%d", keylen);
|
|
|
|
BUG_ON(keylen < 2 || keylen > 514);
|
|
|
|
csum = raw[0] + raw[1];
|
|
print = 1;
|
|
for (loop = 2; loop < keylen; loop++) {
|
|
ch = raw[loop];
|
|
csum += ch;
|
|
print &= cachefiles_filecharmap[ch];
|
|
}
|
|
|
|
if (print) {
|
|
/* if the path is usable ASCII, then we render it directly */
|
|
max = keylen - 2;
|
|
max += 2; /* two base64'd length chars on the front */
|
|
max += 5; /* @checksum/M */
|
|
max += 3 * 2; /* maximum number of segment dividers (".../M")
|
|
* is ((514 + 251) / 252) = 3
|
|
*/
|
|
max += 1; /* NUL on end */
|
|
} else {
|
|
/* calculate the maximum length of the cooked key */
|
|
keylen = (keylen + 2) / 3;
|
|
|
|
max = keylen * 4;
|
|
max += 5; /* @checksum/M */
|
|
max += 3 * 2; /* maximum number of segment dividers (".../M")
|
|
* is ((514 + 188) / 189) = 3
|
|
*/
|
|
max += 1; /* NUL on end */
|
|
}
|
|
|
|
max += 1; /* 2nd NUL on end */
|
|
|
|
_debug("max: %d", max);
|
|
|
|
key = kmalloc(max, cachefiles_gfp);
|
|
if (!key)
|
|
return NULL;
|
|
|
|
len = 0;
|
|
|
|
/* build the cooked key */
|
|
sprintf(key, "@%02x%c+", (unsigned) csum, 0);
|
|
len = 5;
|
|
mark = len - 1;
|
|
|
|
if (print) {
|
|
acc = *(uint16_t *) raw;
|
|
raw += 2;
|
|
|
|
key[len + 1] = cachefiles_charmap[acc & 63];
|
|
acc >>= 6;
|
|
key[len] = cachefiles_charmap[acc & 63];
|
|
len += 2;
|
|
|
|
seg = 250;
|
|
for (loop = keylen; loop > 0; loop--) {
|
|
if (seg <= 0) {
|
|
key[len++] = '\0';
|
|
mark = len;
|
|
key[len++] = '+';
|
|
seg = 252;
|
|
}
|
|
|
|
key[len++] = *raw++;
|
|
ASSERT(len < max);
|
|
}
|
|
|
|
switch (type) {
|
|
case FSCACHE_COOKIE_TYPE_INDEX: type = 'I'; break;
|
|
case FSCACHE_COOKIE_TYPE_DATAFILE: type = 'D'; break;
|
|
default: type = 'S'; break;
|
|
}
|
|
} else {
|
|
seg = 252;
|
|
for (loop = keylen; loop > 0; loop--) {
|
|
if (seg <= 0) {
|
|
key[len++] = '\0';
|
|
mark = len;
|
|
key[len++] = '+';
|
|
seg = 252;
|
|
}
|
|
|
|
acc = *raw++;
|
|
acc |= *raw++ << 8;
|
|
acc |= *raw++ << 16;
|
|
|
|
_debug("acc: %06x", acc);
|
|
|
|
key[len++] = cachefiles_charmap[acc & 63];
|
|
acc >>= 6;
|
|
key[len++] = cachefiles_charmap[acc & 63];
|
|
acc >>= 6;
|
|
key[len++] = cachefiles_charmap[acc & 63];
|
|
acc >>= 6;
|
|
key[len++] = cachefiles_charmap[acc & 63];
|
|
|
|
ASSERT(len < max);
|
|
}
|
|
|
|
switch (type) {
|
|
case FSCACHE_COOKIE_TYPE_INDEX: type = 'J'; break;
|
|
case FSCACHE_COOKIE_TYPE_DATAFILE: type = 'E'; break;
|
|
default: type = 'T'; break;
|
|
}
|
|
}
|
|
|
|
key[mark] = type;
|
|
key[len++] = 0;
|
|
key[len] = 0;
|
|
|
|
_leave(" = %s %d", key, len);
|
|
return key;
|
|
}
|