fs/squashfs/xattr_id.c

   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  */
  28 int 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 = le64_to_cpu(msblk->xattr_id_table[block]);
  35         struct squashfs_xattr_id id;
  36         int err;
  37
  38         err = squashfs_read_metadata(sb, &id, &start_block, &offset,
  39                                                         sizeof(id));
  40         if (err < 0)
  41                 return err;
  42
  43         *xattr = le64_to_cpu(id.xattr);
  44         *size = le32_to_cpu(id.size);
  45         *count = le32_to_cpu(id.count);
  46         return 0;
  47 }
  48
  49
  50 /*
  51  * Read uncompressed xattr id lookup table indexes from disk into memory
  52  */
  53 __le64 *squashfs_read_xattr_id_table(struct super_block *sb, u64 start,
  54                 u64 *xattr_table_start, int *xattr_ids)
  55 {
  56         unsigned int len;
  57         struct squashfs_xattr_id_table *id_table;
  58
  59         id_table = squashfs_read_table(sb, start, sizeof(*id_table));
  60         if (IS_ERR(id_table))
  61                 return (__le64 *) id_table;
  62
  63         *xattr_table_start = le64_to_cpu(id_table->xattr_table_start);
  64         *xattr_ids = le32_to_cpu(id_table->xattr_ids);
  65         kfree(id_table);
  66
  67         /* Sanity check values */
  68
  69         /* there is always at least one xattr id */
  70         if (*xattr_ids == 0)
  71                 return ERR_PTR(-EINVAL);
  72
  73         /* xattr_table should be less than start */
  74         if (*xattr_table_start >= start)
  75                 return ERR_PTR(-EINVAL);
  76
  77         len = SQUASHFS_XATTR_BLOCK_BYTES(*xattr_ids);
  78
  79         TRACE("In read_xattr_index_table, length %d\n", len);
  80
  81         return squashfs_read_table(sb, start + sizeof(*id_table), len);
  82 }