131 lines
3.3 KiB
C
131 lines
3.3 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* Squashfs - a compressed read only filesystem for Linux
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*
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* Copyright (c) 2010
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* Phillip Lougher <phillip@squashfs.org.uk>
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*
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* xattr_id.c
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*/
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/*
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* This file implements code to map the 32-bit xattr id stored in the inode
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* into the on disk location of the xattr data.
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*/
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#include <linux/fs.h>
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#include <linux/vfs.h>
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#include <linux/slab.h>
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#include "squashfs_fs.h"
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#include "squashfs_fs_sb.h"
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#include "squashfs.h"
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#include "xattr.h"
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/*
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* Map xattr id using the xattr id look up table
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*/
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int squashfs_xattr_lookup(struct super_block *sb, unsigned int index,
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int *count, unsigned int *size, unsigned long long *xattr)
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{
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struct squashfs_sb_info *msblk = sb->s_fs_info;
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int block = SQUASHFS_XATTR_BLOCK(index);
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int offset = SQUASHFS_XATTR_BLOCK_OFFSET(index);
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u64 start_block;
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struct squashfs_xattr_id id;
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int err;
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if (index >= msblk->xattr_ids)
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return -EINVAL;
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start_block = le64_to_cpu(msblk->xattr_id_table[block]);
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err = squashfs_read_metadata(sb, &id, &start_block, &offset,
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sizeof(id));
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if (err < 0)
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return err;
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*xattr = le64_to_cpu(id.xattr);
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*size = le32_to_cpu(id.size);
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*count = le32_to_cpu(id.count);
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return 0;
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}
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/*
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* Read uncompressed xattr id lookup table indexes from disk into memory
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*/
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__le64 *squashfs_read_xattr_id_table(struct super_block *sb, u64 table_start,
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u64 *xattr_table_start, int *xattr_ids)
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{
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struct squashfs_sb_info *msblk = sb->s_fs_info;
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unsigned int len, indexes;
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struct squashfs_xattr_id_table *id_table;
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__le64 *table;
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u64 start, end;
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int n;
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id_table = squashfs_read_table(sb, table_start, sizeof(*id_table));
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if (IS_ERR(id_table))
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return (__le64 *) id_table;
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*xattr_table_start = le64_to_cpu(id_table->xattr_table_start);
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*xattr_ids = le32_to_cpu(id_table->xattr_ids);
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kfree(id_table);
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/* Sanity check values */
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/* there is always at least one xattr id */
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if (*xattr_ids == 0)
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return ERR_PTR(-EINVAL);
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len = SQUASHFS_XATTR_BLOCK_BYTES(*xattr_ids);
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indexes = SQUASHFS_XATTR_BLOCKS(*xattr_ids);
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/*
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* The computed size of the index table (len bytes) should exactly
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* match the table start and end points
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*/
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start = table_start + sizeof(*id_table);
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end = msblk->bytes_used;
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if (len != (end - start))
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return ERR_PTR(-EINVAL);
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table = squashfs_read_table(sb, start, len);
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if (IS_ERR(table))
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return table;
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/* table[0], table[1], ... table[indexes - 1] store the locations
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* of the compressed xattr id blocks. Each entry should be less than
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* the next (i.e. table[0] < table[1]), and the difference between them
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* should be SQUASHFS_METADATA_SIZE or less. table[indexes - 1]
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* should be less than table_start, and again the difference
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* shouls be SQUASHFS_METADATA_SIZE or less.
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*
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* Finally xattr_table_start should be less than table[0].
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*/
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for (n = 0; n < (indexes - 1); n++) {
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start = le64_to_cpu(table[n]);
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end = le64_to_cpu(table[n + 1]);
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if (start >= end || (end - start) > SQUASHFS_METADATA_SIZE) {
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kfree(table);
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return ERR_PTR(-EINVAL);
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}
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}
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start = le64_to_cpu(table[indexes - 1]);
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if (start >= table_start || (table_start - start) > SQUASHFS_METADATA_SIZE) {
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kfree(table);
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return ERR_PTR(-EINVAL);
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}
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if (*xattr_table_start >= le64_to_cpu(table[0])) {
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kfree(table);
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return ERR_PTR(-EINVAL);
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}
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return table;
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}
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