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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 | // SPDX-License-Identifier: GPL-2.0-or-later /* * Squashfs - a compressed read only filesystem for Linux * * Copyright (c) 2002, 2003, 2004, 2005, 2006, 2007, 2008 * Phillip Lougher <phillip@squashfs.org.uk> * * id.c */ /* * This file implements code to handle uids and gids. * * For space efficiency regular files store uid and gid indexes, which are * converted to 32-bit uids/gids using an id look up table. This table is * stored compressed into metadata blocks. A second index table is used to * locate these. This second index table for speed of access (and because it * is small) is read at mount time and cached in memory. */ #include <linux/fs.h> #include <linux/vfs.h> #include <linux/slab.h> #include "squashfs_fs.h" #include "squashfs_fs_sb.h" #include "squashfs.h" /* * Map uid/gid index into real 32-bit uid/gid using the id look up table */ int squashfs_get_id(struct super_block *sb, unsigned int index, unsigned int *id) { struct squashfs_sb_info *msblk = sb->s_fs_info; int block = SQUASHFS_ID_BLOCK(index); int offset = SQUASHFS_ID_BLOCK_OFFSET(index); u64 start_block; __le32 disk_id; int err; if (index >= msblk->ids) return -EINVAL; start_block = le64_to_cpu(msblk->id_table[block]); err = squashfs_read_metadata(sb, &disk_id, &start_block, &offset, sizeof(disk_id)); if (err < 0) return err; *id = le32_to_cpu(disk_id); return 0; } /* * Read uncompressed id lookup table indexes from disk into memory */ __le64 *squashfs_read_id_index_table(struct super_block *sb, u64 id_table_start, u64 next_table, unsigned short no_ids) { unsigned int length = SQUASHFS_ID_BLOCK_BYTES(no_ids); unsigned int indexes = SQUASHFS_ID_BLOCKS(no_ids); int n; __le64 *table; u64 start, end; TRACE("In read_id_index_table, length %d\n", length); /* Sanity check values */ /* there should always be at least one id */ if (no_ids == 0) return ERR_PTR(-EINVAL); /* * The computed size of the index table (length bytes) should exactly * match the table start and end points */ if (length != (next_table - id_table_start)) return ERR_PTR(-EINVAL); table = squashfs_read_table(sb, id_table_start, length); if (IS_ERR(table)) return table; /* * table[0], table[1], ... table[indexes - 1] store the locations * of the compressed 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 id_table_start, and again the difference * should be SQUASHFS_METADATA_SIZE or less */ 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 >= id_table_start || (id_table_start - start) > (SQUASHFS_METADATA_SIZE + SQUASHFS_BLOCK_OFFSET)) { kfree(table); return ERR_PTR(-EINVAL); } return table; } |