linux/fs/cachefiles/key.c
Thomas Gleixner b4d0d230cc treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 36
Based on 1 normalized pattern(s):

  this program is free software you can redistribute it and or modify
  it under the terms of the gnu general public licence as published by
  the free software foundation either version 2 of the licence or at
  your option any later version

extracted by the scancode license scanner the SPDX license identifier

  GPL-2.0-or-later

has been chosen to replace the boilerplate/reference in 114 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Allison Randal <allison@lohutok.net>
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190520170857.552531963@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-05-24 17:27:11 +02:00

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(" = %p %d", key, len);
return key;
}