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115 lines
3.0 KiB
115 lines
3.0 KiB
// SPDX-License-Identifier: GPL-2.0-or-later |
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/* |
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* Squashfs - a compressed read only filesystem for Linux |
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* |
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* Copyright (c) 2002, 2003, 2004, 2005, 2006, 2007, 2008 |
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* Phillip Lougher <[email protected]> |
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* |
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* id.c |
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*/ |
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/* |
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* This file implements code to handle uids and gids. |
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* |
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* For space efficiency regular files store uid and gid indexes, which are |
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* converted to 32-bit uids/gids using an id look up table. This table is |
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* stored compressed into metadata blocks. A second index table is used to |
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* locate these. This second index table for speed of access (and because it |
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* is small) is read at mount time and cached in memory. |
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*/ |
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#include <linux/fs.h> |
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#include <linux/vfs.h> |
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#include <linux/slab.h> |
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#include "squashfs_fs.h" |
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#include "squashfs_fs_sb.h" |
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#include "squashfs.h" |
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/* |
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* Map uid/gid index into real 32-bit uid/gid using the id look up table |
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*/ |
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int squashfs_get_id(struct super_block *sb, unsigned int index, |
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unsigned int *id) |
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{ |
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struct squashfs_sb_info *msblk = sb->s_fs_info; |
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int block = SQUASHFS_ID_BLOCK(index); |
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int offset = SQUASHFS_ID_BLOCK_OFFSET(index); |
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u64 start_block; |
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__le32 disk_id; |
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int err; |
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if (index >= msblk->ids) |
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return -EINVAL; |
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start_block = le64_to_cpu(msblk->id_table[block]); |
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err = squashfs_read_metadata(sb, &disk_id, &start_block, &offset, |
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sizeof(disk_id)); |
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if (err < 0) |
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return err; |
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*id = le32_to_cpu(disk_id); |
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return 0; |
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} |
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/* |
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* Read uncompressed id lookup table indexes from disk into memory |
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*/ |
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__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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{ |
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unsigned int length = SQUASHFS_ID_BLOCK_BYTES(no_ids); |
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unsigned int indexes = SQUASHFS_ID_BLOCKS(no_ids); |
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int n; |
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__le64 *table; |
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u64 start, end; |
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TRACE("In read_id_index_table, length %d\n", length); |
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/* Sanity check values */ |
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/* there should always be at least one id */ |
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if (no_ids == 0) |
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return ERR_PTR(-EINVAL); |
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/* |
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* The computed size of the index table (length bytes) should exactly |
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* match the table start and end points |
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*/ |
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if (length != (next_table - id_table_start)) |
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return ERR_PTR(-EINVAL); |
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table = squashfs_read_table(sb, id_table_start, length); |
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if (IS_ERR(table)) |
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return table; |
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/* |
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* table[0], table[1], ... table[indexes - 1] store the locations |
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* of the compressed id blocks. Each entry should be less than |
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* the next (i.e. table[0] < table[1]), and the difference between them |
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* should be SQUASHFS_METADATA_SIZE or less. table[indexes - 1] |
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* should be less than id_table_start, and again the difference |
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* should be SQUASHFS_METADATA_SIZE or less |
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*/ |
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for (n = 0; n < (indexes - 1); n++) { |
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start = le64_to_cpu(table[n]); |
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end = le64_to_cpu(table[n + 1]); |
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if (start >= end || (end - start) > |
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(SQUASHFS_METADATA_SIZE + SQUASHFS_BLOCK_OFFSET)) { |
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kfree(table); |
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return ERR_PTR(-EINVAL); |
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} |
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} |
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start = le64_to_cpu(table[indexes - 1]); |
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if (start >= id_table_start || (id_table_start - start) > |
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(SQUASHFS_METADATA_SIZE + SQUASHFS_BLOCK_OFFSET)) { |
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kfree(table); |
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return ERR_PTR(-EINVAL); |
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} |
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return table; |
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}
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