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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id.c (3094B)

      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
      6 * Phillip Lougher <phillip@squashfs.org.uk>
      7 *
      8 * id.c
      9 */
     10
     11/*
     12 * This file implements code to handle uids and gids.
     13 *
     14 * For space efficiency regular files store uid and gid indexes, which are
     15 * converted to 32-bit uids/gids using an id look up table.  This table is
     16 * stored compressed into metadata blocks.  A second index table is used to
     17 * locate these.  This second index table for speed of access (and because it
     18 * is small) is read at mount time and cached in memory.
     19 */
     20
     21#include <linux/fs.h>
     22#include <linux/vfs.h>
     23#include <linux/slab.h>
     24
     25#include "squashfs_fs.h"
     26#include "squashfs_fs_sb.h"
     27#include "squashfs.h"
     28
     29/*
     30 * Map uid/gid index into real 32-bit uid/gid using the id look up table
     31 */
     32int squashfs_get_id(struct super_block *sb, unsigned int index,
     33					unsigned int *id)
     34{
     35	struct squashfs_sb_info *msblk = sb->s_fs_info;
     36	int block = SQUASHFS_ID_BLOCK(index);
     37	int offset = SQUASHFS_ID_BLOCK_OFFSET(index);
     38	u64 start_block;
     39	__le32 disk_id;
     40	int err;
     41
     42	if (index >= msblk->ids)
     43		return -EINVAL;
     44
     45	start_block = le64_to_cpu(msblk->id_table[block]);
     46
     47	err = squashfs_read_metadata(sb, &disk_id, &start_block, &offset,
     48							sizeof(disk_id));
     49	if (err < 0)
     50		return err;
     51
     52	*id = le32_to_cpu(disk_id);
     53	return 0;
     54}
     55
     56
     57/*
     58 * Read uncompressed id lookup table indexes from disk into memory
     59 */
     60__le64 *squashfs_read_id_index_table(struct super_block *sb,
     61		u64 id_table_start, u64 next_table, unsigned short no_ids)
     62{
     63	unsigned int length = SQUASHFS_ID_BLOCK_BYTES(no_ids);
     64	unsigned int indexes = SQUASHFS_ID_BLOCKS(no_ids);
     65	int n;
     66	__le64 *table;
     67	u64 start, end;
     68
     69	TRACE("In read_id_index_table, length %d\n", length);
     70
     71	/* Sanity check values */
     72
     73	/* there should always be at least one id */
     74	if (no_ids == 0)
     75		return ERR_PTR(-EINVAL);
     76
     77	/*
     78	 * The computed size of the index table (length bytes) should exactly
     79	 * match the table start and end points
     80	 */
     81	if (length != (next_table - id_table_start))
     82		return ERR_PTR(-EINVAL);
     83
     84	table = squashfs_read_table(sb, id_table_start, length);
     85	if (IS_ERR(table))
     86		return table;
     87
     88	/*
     89	 * table[0], table[1], ... table[indexes - 1] store the locations
     90	 * of the compressed id blocks.   Each entry should be less than
     91	 * the next (i.e. table[0] < table[1]), and the difference between them
     92	 * should be SQUASHFS_METADATA_SIZE or less.  table[indexes - 1]
     93	 * should be less than id_table_start, and again the difference
     94	 * should be SQUASHFS_METADATA_SIZE or less
     95	 */
     96	for (n = 0; n < (indexes - 1); n++) {
     97		start = le64_to_cpu(table[n]);
     98		end = le64_to_cpu(table[n + 1]);
     99
    100		if (start >= end || (end - start) >
    101				(SQUASHFS_METADATA_SIZE + SQUASHFS_BLOCK_OFFSET)) {
    102			kfree(table);
    103			return ERR_PTR(-EINVAL);
    104		}
    105	}
    106
    107	start = le64_to_cpu(table[indexes - 1]);
    108	if (start >= id_table_start || (id_table_start - start) >
    109				(SQUASHFS_METADATA_SIZE + SQUASHFS_BLOCK_OFFSET)) {
    110		kfree(table);
    111		return ERR_PTR(-EINVAL);
    112	}
    113
    114	return table;
    115}