1 /*
2  * Squashfs - a compressed read only filesystem for Linux
3  *
4  * Copyright (c) 2010
5  * Phillip Lougher <phillip@squashfs.org.uk>
6  *
7  * This program is free software; you can redistribute it and/or
8  * modify it under the terms of the GNU General Public License
9  * as published by the Free Software Foundation; either version 2,
10  * or (at your option) any later version.
11  *
12  * This program is distributed in the hope that it will be useful,
13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
15  * GNU General Public License for more details.
16  *
17  * You should have received a copy of the GNU General Public License
18  * along with this program; if not, write to the Free Software
19  * Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
20  *
21  * xattr_id.c
22  */
23 
24 /*
25  * This file implements code to map the 32-bit xattr id stored in the inode
26  * into the on disk location of the xattr data.
27  */
28 
29 #include <linux/fs.h>
30 #include <linux/vfs.h>
31 #include <linux/slab.h>
32 
33 #include "squashfs_fs.h"
34 #include "squashfs_fs_sb.h"
35 #include "squashfs.h"
36 #include "xattr.h"
37 
38 /*
39  * Map xattr id using the xattr id look up table
40  */
squashfs_xattr_lookup(struct super_block * sb,unsigned int index,int * count,unsigned int * size,unsigned long long * xattr)41 int squashfs_xattr_lookup(struct super_block *sb, unsigned int index,
42 		int *count, unsigned int *size, unsigned long long *xattr)
43 {
44 	struct squashfs_sb_info *msblk = sb->s_fs_info;
45 	int block = SQUASHFS_XATTR_BLOCK(index);
46 	int offset = SQUASHFS_XATTR_BLOCK_OFFSET(index);
47 	u64 start_block = le64_to_cpu(msblk->xattr_id_table[block]);
48 	struct squashfs_xattr_id id;
49 	int err;
50 
51 	err = squashfs_read_metadata(sb, &id, &start_block, &offset,
52 							sizeof(id));
53 	if (err < 0)
54 		return err;
55 
56 	*xattr = le64_to_cpu(id.xattr);
57 	*size = le32_to_cpu(id.size);
58 	*count = le32_to_cpu(id.count);
59 	return 0;
60 }
61 
62 
63 /*
64  * Read uncompressed xattr id lookup table indexes from disk into memory
65  */
squashfs_read_xattr_id_table(struct super_block * sb,u64 start,u64 * xattr_table_start,int * xattr_ids)66 __le64 *squashfs_read_xattr_id_table(struct super_block *sb, u64 start,
67 		u64 *xattr_table_start, int *xattr_ids)
68 {
69 	unsigned int len;
70 	struct squashfs_xattr_id_table *id_table;
71 
72 	id_table = squashfs_read_table(sb, start, sizeof(*id_table));
73 	if (IS_ERR(id_table))
74 		return (__le64 *) id_table;
75 
76 	*xattr_table_start = le64_to_cpu(id_table->xattr_table_start);
77 	*xattr_ids = le32_to_cpu(id_table->xattr_ids);
78 	kfree(id_table);
79 
80 	/* Sanity check values */
81 
82 	/* there is always at least one xattr id */
83 	if (*xattr_ids == 0)
84 		return ERR_PTR(-EINVAL);
85 
86 	/* xattr_table should be less than start */
87 	if (*xattr_table_start >= start)
88 		return ERR_PTR(-EINVAL);
89 
90 	len = SQUASHFS_XATTR_BLOCK_BYTES(*xattr_ids);
91 
92 	TRACE("In read_xattr_index_table, length %d\n", len);
93 
94 	return squashfs_read_table(sb, start + sizeof(*id_table), len);
95 }
96