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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xattr_id.c (3400B)

      1// SPDX-License-Identifier: GPL-2.0-or-later
      2/*
      3 * Squashfs - a compressed read only filesystem for Linux
      4 *
      5 * Copyright (c) 2010
      6 * Phillip Lougher <phillip@squashfs.org.uk>
      7 *
      8 * xattr_id.c
      9 */
     10
     11/*
     12 * This file implements code to map the 32-bit xattr id stored in the inode
     13 * into the on disk location of the xattr data.
     14 */
     15
     16#include <linux/fs.h>
     17#include <linux/vfs.h>
     18#include <linux/slab.h>
     19
     20#include "squashfs_fs.h"
     21#include "squashfs_fs_sb.h"
     22#include "squashfs.h"
     23#include "xattr.h"
     24
     25/*
     26 * Map xattr id using the xattr id look up table
     27 */
     28int squashfs_xattr_lookup(struct super_block *sb, unsigned int index,
     29		int *count, unsigned int *size, unsigned long long *xattr)
     30{
     31	struct squashfs_sb_info *msblk = sb->s_fs_info;
     32	int block = SQUASHFS_XATTR_BLOCK(index);
     33	int offset = SQUASHFS_XATTR_BLOCK_OFFSET(index);
     34	u64 start_block;
     35	struct squashfs_xattr_id id;
     36	int err;
     37
     38	if (index >= msblk->xattr_ids)
     39		return -EINVAL;
     40
     41	start_block = le64_to_cpu(msblk->xattr_id_table[block]);
     42
     43	err = squashfs_read_metadata(sb, &id, &start_block, &offset,
     44							sizeof(id));
     45	if (err < 0)
     46		return err;
     47
     48	*xattr = le64_to_cpu(id.xattr);
     49	*size = le32_to_cpu(id.size);
     50	*count = le32_to_cpu(id.count);
     51	return 0;
     52}
     53
     54
     55/*
     56 * Read uncompressed xattr id lookup table indexes from disk into memory
     57 */
     58__le64 *squashfs_read_xattr_id_table(struct super_block *sb, u64 table_start,
     59		u64 *xattr_table_start, int *xattr_ids)
     60{
     61	struct squashfs_sb_info *msblk = sb->s_fs_info;
     62	unsigned int len, indexes;
     63	struct squashfs_xattr_id_table *id_table;
     64	__le64 *table;
     65	u64 start, end;
     66	int n;
     67
     68	id_table = squashfs_read_table(sb, table_start, sizeof(*id_table));
     69	if (IS_ERR(id_table))
     70		return (__le64 *) id_table;
     71
     72	*xattr_table_start = le64_to_cpu(id_table->xattr_table_start);
     73	*xattr_ids = le32_to_cpu(id_table->xattr_ids);
     74	kfree(id_table);
     75
     76	/* Sanity check values */
     77
     78	/* there is always at least one xattr id */
     79	if (*xattr_ids == 0)
     80		return ERR_PTR(-EINVAL);
     81
     82	len = SQUASHFS_XATTR_BLOCK_BYTES(*xattr_ids);
     83	indexes = SQUASHFS_XATTR_BLOCKS(*xattr_ids);
     84
     85	/*
     86	 * The computed size of the index table (len bytes) should exactly
     87	 * match the table start and end points
     88	 */
     89	start = table_start + sizeof(*id_table);
     90	end = msblk->bytes_used;
     91
     92	if (len != (end - start))
     93		return ERR_PTR(-EINVAL);
     94
     95	table = squashfs_read_table(sb, start, len);
     96	if (IS_ERR(table))
     97		return table;
     98
     99	/* table[0], table[1], ... table[indexes - 1] store the locations
    100	 * of the compressed xattr id blocks.  Each entry should be less than
    101	 * the next (i.e. table[0] < table[1]), and the difference between them
    102	 * should be SQUASHFS_METADATA_SIZE or less.  table[indexes - 1]
    103	 * should be less than table_start, and again the difference
    104	 * shouls be SQUASHFS_METADATA_SIZE or less.
    105	 *
    106	 * Finally xattr_table_start should be less than table[0].
    107	 */
    108	for (n = 0; n < (indexes - 1); n++) {
    109		start = le64_to_cpu(table[n]);
    110		end = le64_to_cpu(table[n + 1]);
    111
    112		if (start >= end || (end - start) >
    113				(SQUASHFS_METADATA_SIZE + SQUASHFS_BLOCK_OFFSET)) {
    114			kfree(table);
    115			return ERR_PTR(-EINVAL);
    116		}
    117	}
    118
    119	start = le64_to_cpu(table[indexes - 1]);
    120	if (start >= table_start || (table_start - start) >
    121				(SQUASHFS_METADATA_SIZE + SQUASHFS_BLOCK_OFFSET)) {
    122		kfree(table);
    123		return ERR_PTR(-EINVAL);
    124	}
    125
    126	if (*xattr_table_start >= le64_to_cpu(table[0])) {
    127		kfree(table);
    128		return ERR_PTR(-EINVAL);
    129	}
    130
    131	return table;
    132}