// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Squashfs - a compressed read only filesystem for Linux
 *
 * Copyright (c) 2010
 * Phillip Lougher <phillip@squashfs.org.uk>
 *
 * xattr_id.c
 */

/*
 * This file implements code to map the 32-bit xattr id stored in the inode
 * into the on disk location of the xattr data.
 */

#include <linux/fs.h>
#include <linux/vfs.h>
#include <linux/slab.h>

#include "squashfs_fs.h"
#include "squashfs_fs_sb.h"
#include "squashfs.h"
#include "xattr.h"

/*
 * Map xattr id using the xattr id look up table
 */
int squashfs_xattr_lookup(struct super_block *sb, unsigned int index,
                int *count, unsigned int *size, unsigned long long *xattr)
{
        struct squashfs_sb_info *msblk = sb->s_fs_info;
        int block = SQUASHFS_XATTR_BLOCK(index);
        int offset = SQUASHFS_XATTR_BLOCK_OFFSET(index);
        u64 start_block;
        struct squashfs_xattr_id id;
        int err;

        if (index >= msblk->xattr_ids)
                return -EINVAL;

        start_block = le64_to_cpu(msblk->xattr_id_table[block]);

        err = squashfs_read_metadata(sb, &id, &start_block, &offset,
                                                        sizeof(id));
        if (err < 0)
                return err;

        *xattr = le64_to_cpu(id.xattr);
        *size = le32_to_cpu(id.size);
        *count = le32_to_cpu(id.count);
        return 0;
}


/*
 * Read uncompressed xattr id lookup table indexes from disk into memory
 */
__le64 *squashfs_read_xattr_id_table(struct super_block *sb, u64 table_start,
                u64 *xattr_table_start, unsigned int *xattr_ids)
{
        struct squashfs_sb_info *msblk = sb->s_fs_info;
        unsigned int len, indexes;
        struct squashfs_xattr_id_table *id_table;
        __le64 *table;
        u64 start, end;
        int n;

        id_table = squashfs_read_table(sb, table_start, sizeof(*id_table));
        if (IS_ERR(id_table))
                return (__le64 *) id_table;

        *xattr_table_start = le64_to_cpu(id_table->xattr_table_start);
        *xattr_ids = le32_to_cpu(id_table->xattr_ids);
        kfree(id_table);

        /* Sanity check values */

        /* there is always at least one xattr id */
        if (*xattr_ids == 0)
                return ERR_PTR(-EINVAL);

        len = SQUASHFS_XATTR_BLOCK_BYTES(*xattr_ids);
        indexes = SQUASHFS_XATTR_BLOCKS(*xattr_ids);

        /*
         * The computed size of the index table (len bytes) should exactly
         * match the table start and end points
         */
        start = table_start + sizeof(*id_table);
        end = msblk->bytes_used;

        if (len != (end - start))
                return ERR_PTR(-EINVAL);

        table = squashfs_read_table(sb, start, len);
        if (IS_ERR(table))
                return table;

        /* table[0], table[1], ... table[indexes - 1] store the locations
         * of the compressed xattr id blocks.  Each entry should be less than
         * the next (i.e. table[0] < table[1]), and the difference between them
         * should be SQUASHFS_METADATA_SIZE or less.  table[indexes - 1]
         * should be less than table_start, and again the difference
         * shouls be SQUASHFS_METADATA_SIZE or less.
         *
         * Finally xattr_table_start should be less than table[0].
         */
        for (n = 0; n < (indexes - 1); n++) {
                start = le64_to_cpu(table[n]);
                end = le64_to_cpu(table[n + 1]);

                if (start >= end || (end - start) >
                                (SQUASHFS_METADATA_SIZE + SQUASHFS_BLOCK_OFFSET)) {
                        kfree(table);
                        return ERR_PTR(-EINVAL);
                }
        }

        start = le64_to_cpu(table[indexes - 1]);
        if (start >= table_start || (table_start - start) >
                                (SQUASHFS_METADATA_SIZE + SQUASHFS_BLOCK_OFFSET)) {
                kfree(table);
                return ERR_PTR(-EINVAL);
        }

        if (*xattr_table_start >= le64_to_cpu(table[0])) {
                kfree(table);
                return ERR_PTR(-EINVAL);
        }

        return table;
}