168252eb5SThomas Gleixner // SPDX-License-Identifier: GPL-2.0-or-later
28256c8f6SPhillip Lougher /*
38256c8f6SPhillip Lougher * Squashfs - a compressed read only filesystem for Linux
48256c8f6SPhillip Lougher *
58256c8f6SPhillip Lougher * Copyright (c) 2002, 2003, 2004, 2005, 2006, 2007, 2008
6d7f2ff67SPhillip Lougher * Phillip Lougher <phillip@squashfs.org.uk>
78256c8f6SPhillip Lougher *
88256c8f6SPhillip Lougher * id.c
98256c8f6SPhillip Lougher */
108256c8f6SPhillip Lougher
118256c8f6SPhillip Lougher /*
128256c8f6SPhillip Lougher * This file implements code to handle uids and gids.
138256c8f6SPhillip Lougher *
148256c8f6SPhillip Lougher * For space efficiency regular files store uid and gid indexes, which are
158256c8f6SPhillip Lougher * converted to 32-bit uids/gids using an id look up table. This table is
168256c8f6SPhillip Lougher * stored compressed into metadata blocks. A second index table is used to
178256c8f6SPhillip Lougher * locate these. This second index table for speed of access (and because it
188256c8f6SPhillip Lougher * is small) is read at mount time and cached in memory.
198256c8f6SPhillip Lougher */
208256c8f6SPhillip Lougher
218256c8f6SPhillip Lougher #include <linux/fs.h>
228256c8f6SPhillip Lougher #include <linux/vfs.h>
238256c8f6SPhillip Lougher #include <linux/slab.h>
248256c8f6SPhillip Lougher
258256c8f6SPhillip Lougher #include "squashfs_fs.h"
268256c8f6SPhillip Lougher #include "squashfs_fs_sb.h"
278256c8f6SPhillip Lougher #include "squashfs.h"
288256c8f6SPhillip Lougher
298256c8f6SPhillip Lougher /*
308256c8f6SPhillip Lougher * Map uid/gid index into real 32-bit uid/gid using the id look up table
318256c8f6SPhillip Lougher */
squashfs_get_id(struct super_block * sb,unsigned int index,unsigned int * id)328256c8f6SPhillip Lougher int squashfs_get_id(struct super_block *sb, unsigned int index,
338256c8f6SPhillip Lougher unsigned int *id)
348256c8f6SPhillip Lougher {
358256c8f6SPhillip Lougher struct squashfs_sb_info *msblk = sb->s_fs_info;
368256c8f6SPhillip Lougher int block = SQUASHFS_ID_BLOCK(index);
378256c8f6SPhillip Lougher int offset = SQUASHFS_ID_BLOCK_OFFSET(index);
38f37aa4c7SPhillip Lougher u64 start_block;
398256c8f6SPhillip Lougher __le32 disk_id;
408256c8f6SPhillip Lougher int err;
418256c8f6SPhillip Lougher
42f37aa4c7SPhillip Lougher if (index >= msblk->ids)
43f37aa4c7SPhillip Lougher return -EINVAL;
44f37aa4c7SPhillip Lougher
45f37aa4c7SPhillip Lougher start_block = le64_to_cpu(msblk->id_table[block]);
46f37aa4c7SPhillip Lougher
478256c8f6SPhillip Lougher err = squashfs_read_metadata(sb, &disk_id, &start_block, &offset,
488256c8f6SPhillip Lougher sizeof(disk_id));
498256c8f6SPhillip Lougher if (err < 0)
508256c8f6SPhillip Lougher return err;
518256c8f6SPhillip Lougher
528256c8f6SPhillip Lougher *id = le32_to_cpu(disk_id);
538256c8f6SPhillip Lougher return 0;
548256c8f6SPhillip Lougher }
558256c8f6SPhillip Lougher
568256c8f6SPhillip Lougher
578256c8f6SPhillip Lougher /*
588256c8f6SPhillip Lougher * Read uncompressed id lookup table indexes from disk into memory
598256c8f6SPhillip Lougher */
squashfs_read_id_index_table(struct super_block * sb,u64 id_table_start,u64 next_table,unsigned short no_ids)608256c8f6SPhillip Lougher __le64 *squashfs_read_id_index_table(struct super_block *sb,
6137986f63SPhillip Lougher u64 id_table_start, u64 next_table, unsigned short no_ids)
628256c8f6SPhillip Lougher {
638256c8f6SPhillip Lougher unsigned int length = SQUASHFS_ID_BLOCK_BYTES(no_ids);
64f37aa4c7SPhillip Lougher unsigned int indexes = SQUASHFS_ID_BLOCKS(no_ids);
65f37aa4c7SPhillip Lougher int n;
6637986f63SPhillip Lougher __le64 *table;
67f37aa4c7SPhillip Lougher u64 start, end;
688256c8f6SPhillip Lougher
698256c8f6SPhillip Lougher TRACE("In read_id_index_table, length %d\n", length);
708256c8f6SPhillip Lougher
7137986f63SPhillip Lougher /* Sanity check values */
7237986f63SPhillip Lougher
7337986f63SPhillip Lougher /* there should always be at least one id */
7437986f63SPhillip Lougher if (no_ids == 0)
7537986f63SPhillip Lougher return ERR_PTR(-EINVAL);
7637986f63SPhillip Lougher
7737986f63SPhillip Lougher /*
78f37aa4c7SPhillip Lougher * The computed size of the index table (length bytes) should exactly
79f37aa4c7SPhillip Lougher * match the table start and end points
8037986f63SPhillip Lougher */
81f37aa4c7SPhillip Lougher if (length != (next_table - id_table_start))
8237986f63SPhillip Lougher return ERR_PTR(-EINVAL);
8337986f63SPhillip Lougher
8437986f63SPhillip Lougher table = squashfs_read_table(sb, id_table_start, length);
85f37aa4c7SPhillip Lougher if (IS_ERR(table))
86f37aa4c7SPhillip Lougher return table;
8737986f63SPhillip Lougher
8837986f63SPhillip Lougher /*
89f37aa4c7SPhillip Lougher * table[0], table[1], ... table[indexes - 1] store the locations
90f37aa4c7SPhillip Lougher * of the compressed id blocks. Each entry should be less than
91f37aa4c7SPhillip Lougher * the next (i.e. table[0] < table[1]), and the difference between them
92f37aa4c7SPhillip Lougher * should be SQUASHFS_METADATA_SIZE or less. table[indexes - 1]
93f37aa4c7SPhillip Lougher * should be less than id_table_start, and again the difference
94f37aa4c7SPhillip Lougher * should be SQUASHFS_METADATA_SIZE or less
9537986f63SPhillip Lougher */
96f37aa4c7SPhillip Lougher for (n = 0; n < (indexes - 1); n++) {
97f37aa4c7SPhillip Lougher start = le64_to_cpu(table[n]);
98f37aa4c7SPhillip Lougher end = le64_to_cpu(table[n + 1]);
99f37aa4c7SPhillip Lougher
100*8b44ca2bSPhillip Lougher if (start >= end || (end - start) >
101*8b44ca2bSPhillip Lougher (SQUASHFS_METADATA_SIZE + SQUASHFS_BLOCK_OFFSET)) {
102f37aa4c7SPhillip Lougher kfree(table);
103f37aa4c7SPhillip Lougher return ERR_PTR(-EINVAL);
104f37aa4c7SPhillip Lougher }
105f37aa4c7SPhillip Lougher }
106f37aa4c7SPhillip Lougher
107f37aa4c7SPhillip Lougher start = le64_to_cpu(table[indexes - 1]);
108*8b44ca2bSPhillip Lougher if (start >= id_table_start || (id_table_start - start) >
109*8b44ca2bSPhillip Lougher (SQUASHFS_METADATA_SIZE + SQUASHFS_BLOCK_OFFSET)) {
11037986f63SPhillip Lougher kfree(table);
11137986f63SPhillip Lougher return ERR_PTR(-EINVAL);
11237986f63SPhillip Lougher }
11337986f63SPhillip Lougher
11437986f63SPhillip Lougher return table;
1158256c8f6SPhillip Lougher }
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