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fs/squashfs/id.c
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// SPDX-License-Identifier: GPL-2.0-or-later |
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/* * Squashfs - a compressed read only filesystem for Linux * * Copyright (c) 2002, 2003, 2004, 2005, 2006, 2007, 2008 |
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* Phillip Lougher <phillip@squashfs.org.uk> |
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* |
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* 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> |
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#include "squashfs_fs.h" #include "squashfs_fs_sb.h" |
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#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 = le64_to_cpu(msblk->id_table[block]); __le32 disk_id; int err; 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, |
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u64 id_table_start, u64 next_table, unsigned short no_ids) |
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{ unsigned int length = SQUASHFS_ID_BLOCK_BYTES(no_ids); |
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__le64 *table; |
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TRACE("In read_id_index_table, length %d ", length); |
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/* Sanity check values */ /* there should always be at least one id */ if (no_ids == 0) return ERR_PTR(-EINVAL); /* * length bytes should not extend into the next table - this check * also traps instances where id_table_start is incorrectly larger * than the next table start */ if (id_table_start + length > next_table) return ERR_PTR(-EINVAL); table = squashfs_read_table(sb, id_table_start, length); /* * table[0] points to the first id lookup table metadata block, this * should be less than id_table_start */ |
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if (!IS_ERR(table) && le64_to_cpu(table[0]) >= id_table_start) { |
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kfree(table); return ERR_PTR(-EINVAL); } return table; |
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} |