cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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decompressor.c (3332B)

      1// SPDX-License-Identifier: GPL-2.0-or-later
      2/*
      3 * Squashfs - a compressed read only filesystem for Linux
      4 *
      5 * Copyright (c) 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009
      6 * Phillip Lougher <phillip@squashfs.org.uk>
      7 *
      8 * decompressor.c
      9 */
     10
     11#include <linux/types.h>
     12#include <linux/mutex.h>
     13#include <linux/slab.h>
     14#include <linux/buffer_head.h>
     15
     16#include "squashfs_fs.h"
     17#include "squashfs_fs_sb.h"
     18#include "decompressor.h"
     19#include "squashfs.h"
     20#include "page_actor.h"
     21
     22/*
     23 * This file (and decompressor.h) implements a decompressor framework for
     24 * Squashfs, allowing multiple decompressors to be easily supported
     25 */
     26
     27static const struct squashfs_decompressor squashfs_lzma_unsupported_comp_ops = {
     28	NULL, NULL, NULL, NULL, LZMA_COMPRESSION, "lzma", 0
     29};
     30
     31#ifndef CONFIG_SQUASHFS_LZ4
     32static const struct squashfs_decompressor squashfs_lz4_comp_ops = {
     33	NULL, NULL, NULL, NULL, LZ4_COMPRESSION, "lz4", 0
     34};
     35#endif
     36
     37#ifndef CONFIG_SQUASHFS_LZO
     38static const struct squashfs_decompressor squashfs_lzo_comp_ops = {
     39	NULL, NULL, NULL, NULL, LZO_COMPRESSION, "lzo", 0
     40};
     41#endif
     42
     43#ifndef CONFIG_SQUASHFS_XZ
     44static const struct squashfs_decompressor squashfs_xz_comp_ops = {
     45	NULL, NULL, NULL, NULL, XZ_COMPRESSION, "xz", 0
     46};
     47#endif
     48
     49#ifndef CONFIG_SQUASHFS_ZLIB
     50static const struct squashfs_decompressor squashfs_zlib_comp_ops = {
     51	NULL, NULL, NULL, NULL, ZLIB_COMPRESSION, "zlib", 0
     52};
     53#endif
     54
     55#ifndef CONFIG_SQUASHFS_ZSTD
     56static const struct squashfs_decompressor squashfs_zstd_comp_ops = {
     57	NULL, NULL, NULL, NULL, ZSTD_COMPRESSION, "zstd", 0
     58};
     59#endif
     60
     61static const struct squashfs_decompressor squashfs_unknown_comp_ops = {
     62	NULL, NULL, NULL, NULL, 0, "unknown", 0
     63};
     64
     65static const struct squashfs_decompressor *decompressor[] = {
     66	&squashfs_zlib_comp_ops,
     67	&squashfs_lz4_comp_ops,
     68	&squashfs_lzo_comp_ops,
     69	&squashfs_xz_comp_ops,
     70	&squashfs_lzma_unsupported_comp_ops,
     71	&squashfs_zstd_comp_ops,
     72	&squashfs_unknown_comp_ops
     73};
     74
     75
     76const struct squashfs_decompressor *squashfs_lookup_decompressor(int id)
     77{
     78	int i;
     79
     80	for (i = 0; decompressor[i]->id; i++)
     81		if (id == decompressor[i]->id)
     82			break;
     83
     84	return decompressor[i];
     85}
     86
     87
     88static void *get_comp_opts(struct super_block *sb, unsigned short flags)
     89{
     90	struct squashfs_sb_info *msblk = sb->s_fs_info;
     91	void *buffer = NULL, *comp_opts;
     92	struct squashfs_page_actor *actor = NULL;
     93	int length = 0;
     94
     95	/*
     96	 * Read decompressor specific options from file system if present
     97	 */
     98	if (SQUASHFS_COMP_OPTS(flags)) {
     99		buffer = kmalloc(PAGE_SIZE, GFP_KERNEL);
    100		if (buffer == NULL) {
    101			comp_opts = ERR_PTR(-ENOMEM);
    102			goto out;
    103		}
    104
    105		actor = squashfs_page_actor_init(&buffer, 1, 0);
    106		if (actor == NULL) {
    107			comp_opts = ERR_PTR(-ENOMEM);
    108			goto out;
    109		}
    110
    111		length = squashfs_read_data(sb,
    112			sizeof(struct squashfs_super_block), 0, NULL, actor);
    113
    114		if (length < 0) {
    115			comp_opts = ERR_PTR(length);
    116			goto out;
    117		}
    118	}
    119
    120	comp_opts = squashfs_comp_opts(msblk, buffer, length);
    121
    122out:
    123	kfree(actor);
    124	kfree(buffer);
    125	return comp_opts;
    126}
    127
    128
    129void *squashfs_decompressor_setup(struct super_block *sb, unsigned short flags)
    130{
    131	struct squashfs_sb_info *msblk = sb->s_fs_info;
    132	void *stream, *comp_opts = get_comp_opts(sb, flags);
    133
    134	if (IS_ERR(comp_opts))
    135		return comp_opts;
    136
    137	stream = squashfs_decompressor_create(msblk, comp_opts);
    138	if (IS_ERR(stream))
    139		kfree(comp_opts);
    140
    141	return stream;
    142}