1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * Squashfs - a compressed read only filesystem for Linux 4 * 5 * Copyright (c) 2010 6 * Phillip Lougher <phillip@squashfs.org.uk> 7 * 8 * xattr_id.c 9 */ 10 11 /* 12 * This file implements code to map the 32-bit xattr id stored in the inode 13 * into the on disk location of the xattr data. 14 */ 15 16 #include <linux/fs.h> 17 #include <linux/vfs.h> 18 #include <linux/slab.h> 19 20 #include "squashfs_fs.h" 21 #include "squashfs_fs_sb.h" 22 #include "squashfs.h" 23 #include "xattr.h" 24 25 /* 26 * Map xattr id using the xattr id look up table 27 */ 28 int squashfs_xattr_lookup(struct super_block *sb, unsigned int index, 29 int *count, unsigned int *size, unsigned long long *xattr) 30 { 31 struct squashfs_sb_info *msblk = sb->s_fs_info; 32 int block = SQUASHFS_XATTR_BLOCK(index); 33 int offset = SQUASHFS_XATTR_BLOCK_OFFSET(index); 34 u64 start_block; 35 struct squashfs_xattr_id id; 36 int err; 37 38 if (index >= msblk->xattr_ids) 39 return -EINVAL; 40 41 start_block = le64_to_cpu(msblk->xattr_id_table[block]); 42 43 err = squashfs_read_metadata(sb, &id, &start_block, &offset, 44 sizeof(id)); 45 if (err < 0) 46 return err; 47 48 *xattr = le64_to_cpu(id.xattr); 49 *size = le32_to_cpu(id.size); 50 *count = le32_to_cpu(id.count); 51 return 0; 52 } 53 54 55 /* 56 * Read uncompressed xattr id lookup table indexes from disk into memory 57 */ 58 __le64 *squashfs_read_xattr_id_table(struct super_block *sb, u64 table_start, 59 u64 *xattr_table_start, int *xattr_ids) 60 { 61 struct squashfs_sb_info *msblk = sb->s_fs_info; 62 unsigned int len, indexes; 63 struct squashfs_xattr_id_table *id_table; 64 __le64 *table; 65 u64 start, end; 66 int n; 67 68 id_table = squashfs_read_table(sb, table_start, sizeof(*id_table)); 69 if (IS_ERR(id_table)) 70 return (__le64 *) id_table; 71 72 *xattr_table_start = le64_to_cpu(id_table->xattr_table_start); 73 *xattr_ids = le32_to_cpu(id_table->xattr_ids); 74 kfree(id_table); 75 76 /* Sanity check values */ 77 78 /* there is always at least one xattr id */ 79 if (*xattr_ids == 0) 80 return ERR_PTR(-EINVAL); 81 82 len = SQUASHFS_XATTR_BLOCK_BYTES(*xattr_ids); 83 indexes = SQUASHFS_XATTR_BLOCKS(*xattr_ids); 84 85 /* 86 * The computed size of the index table (len bytes) should exactly 87 * match the table start and end points 88 */ 89 start = table_start + sizeof(*id_table); 90 end = msblk->bytes_used; 91 92 if (len != (end - start)) 93 return ERR_PTR(-EINVAL); 94 95 table = squashfs_read_table(sb, start, len); 96 if (IS_ERR(table)) 97 return table; 98 99 /* table[0], table[1], ... table[indexes - 1] store the locations 100 * of the compressed xattr id blocks. Each entry should be less than 101 * the next (i.e. table[0] < table[1]), and the difference between them 102 * should be SQUASHFS_METADATA_SIZE or less. table[indexes - 1] 103 * should be less than table_start, and again the difference 104 * shouls be SQUASHFS_METADATA_SIZE or less. 105 * 106 * Finally xattr_table_start should be less than table[0]. 107 */ 108 for (n = 0; n < (indexes - 1); n++) { 109 start = le64_to_cpu(table[n]); 110 end = le64_to_cpu(table[n + 1]); 111 112 if (start >= end || (end - start) > SQUASHFS_METADATA_SIZE) { 113 kfree(table); 114 return ERR_PTR(-EINVAL); 115 } 116 } 117 118 start = le64_to_cpu(table[indexes - 1]); 119 if (start >= table_start || (table_start - start) > SQUASHFS_METADATA_SIZE) { 120 kfree(table); 121 return ERR_PTR(-EINVAL); 122 } 123 124 if (*xattr_table_start >= le64_to_cpu(table[0])) { 125 kfree(table); 126 return ERR_PTR(-EINVAL); 127 } 128 129 return table; 130 } 131