// SPDX-License-Identifier: GPL-2.0 /* * linux/fs/ext4/block_validity.c * * Copyright (C) 2009 * Theodore Ts'o (tytso@mit.edu) * * Track which blocks in the filesystem are metadata blocks that * should never be used as data blocks by files or directories. */ #include #include #include #include #include #include #include #include #include #include "ext4.h" struct ext4_system_zone { struct rb_node node; ext4_fsblk_t start_blk; unsigned int count; }; static struct kmem_cache *ext4_system_zone_cachep; int __init ext4_init_system_zone(void) { ext4_system_zone_cachep = KMEM_CACHE(ext4_system_zone, 0); if (ext4_system_zone_cachep == NULL) return -ENOMEM; return 0; } void ext4_exit_system_zone(void) { kmem_cache_destroy(ext4_system_zone_cachep); } static inline int can_merge(struct ext4_system_zone *entry1, struct ext4_system_zone *entry2) { if ((entry1->start_blk + entry1->count) == entry2->start_blk) return 1; return 0; } /* * Mark a range of blocks as belonging to the "system zone" --- that * is, filesystem metadata blocks which should never be used by * inodes. */ static int add_system_zone(struct ext4_sb_info *sbi, ext4_fsblk_t start_blk, unsigned int count) { struct ext4_system_zone *new_entry = NULL, *entry; struct rb_node **n = &sbi->system_blks.rb_node, *node; struct rb_node *parent = NULL, *new_node = NULL; while (*n) { parent = *n; entry = rb_entry(parent, struct ext4_system_zone, node); if (start_blk < entry->start_blk) n = &(*n)->rb_left; else if (start_blk >= (entry->start_blk + entry->count)) n = &(*n)->rb_right; else { if (start_blk + count > (entry->start_blk + entry->count)) entry->count = (start_blk + count - entry->start_blk); new_node = *n; new_entry = rb_entry(new_node, struct ext4_system_zone, node); break; } } if (!new_entry) { new_entry = kmem_cache_alloc(ext4_system_zone_cachep, GFP_KERNEL); if (!new_entry) return -ENOMEM; new_entry->start_blk = start_blk; new_entry->count = count; new_node = &new_entry->node; rb_link_node(new_node, parent, n); rb_insert_color(new_node, &sbi->system_blks); } /* Can we merge to the left? */ node = rb_prev(new_node); if (node) { entry = rb_entry(node, struct ext4_system_zone, node); if (can_merge(entry, new_entry)) { new_entry->start_blk = entry->start_blk; new_entry->count += entry->count; rb_erase(node, &sbi->system_blks); kmem_cache_free(ext4_system_zone_cachep, entry); } } /* Can we merge to the right? */ node = rb_next(new_node); if (node) { entry = rb_entry(node, struct ext4_system_zone, node); if (can_merge(new_entry, entry)) { new_entry->count += entry->count; rb_erase(node, &sbi->system_blks); kmem_cache_free(ext4_system_zone_cachep, entry); } } return 0; } static void debug_print_tree(struct ext4_sb_info *sbi) { struct rb_node *node; struct ext4_system_zone *entry; int first = 1; printk(KERN_INFO "System zones: "); node = rb_first(&sbi->system_blks); while (node) { entry = rb_entry(node, struct ext4_system_zone, node); printk(KERN_CONT "%s%llu-%llu", first ? "" : ", ", entry->start_blk, entry->start_blk + entry->count - 1); first = 0; node = rb_next(node); } printk(KERN_CONT "\n"); } static int ext4_protect_reserved_inode(struct super_block *sb, u32 ino) { struct inode *inode; struct ext4_sb_info *sbi = EXT4_SB(sb); struct ext4_map_blocks map; u32 i = 0, num; int err = 0, n; if ((ino < EXT4_ROOT_INO) || (ino > le32_to_cpu(sbi->s_es->s_inodes_count))) return -EINVAL; inode = ext4_iget(sb, ino, EXT4_IGET_SPECIAL); if (IS_ERR(inode)) return PTR_ERR(inode); num = (inode->i_size + sb->s_blocksize - 1) >> sb->s_blocksize_bits; while (i < num) { map.m_lblk = i; map.m_len = num - i; n = ext4_map_blocks(NULL, inode, &map, 0); if (n < 0) { err = n; break; } if (n == 0) { i++; } else { if (!ext4_data_block_valid(sbi, map.m_pblk, n)) { ext4_error(sb, "blocks %llu-%llu from inode %u " "overlap system zone", map.m_pblk, map.m_pblk + map.m_len - 1, ino); err = -EFSCORRUPTED; break; } err = add_system_zone(sbi, map.m_pblk, n); if (err < 0) break; i += n; } } iput(inode); return err; } int ext4_setup_system_zone(struct super_block *sb) { ext4_group_t ngroups = ext4_get_groups_count(sb); struct ext4_sb_info *sbi = EXT4_SB(sb); struct ext4_group_desc *gdp; ext4_group_t i; int flex_size = ext4_flex_bg_size(sbi); int ret; if (!test_opt(sb, BLOCK_VALIDITY)) { if (sbi->system_blks.rb_node) ext4_release_system_zone(sb); return 0; } if (sbi->system_blks.rb_node) return 0; for (i=0; i < ngroups; i++) { if (ext4_bg_has_super(sb, i) && ((i < 5) || ((i % flex_size) == 0))) add_system_zone(sbi, ext4_group_first_block_no(sb, i), ext4_bg_num_gdb(sb, i) + 1); gdp = ext4_get_group_desc(sb, i, NULL); ret = add_system_zone(sbi, ext4_block_bitmap(sb, gdp), 1); if (ret) return ret; ret = add_system_zone(sbi, ext4_inode_bitmap(sb, gdp), 1); if (ret) return ret; ret = add_system_zone(sbi, ext4_inode_table(sb, gdp), sbi->s_itb_per_group); if (ret) return ret; } if (ext4_has_feature_journal(sb) && sbi->s_es->s_journal_inum) { ret = ext4_protect_reserved_inode(sb, le32_to_cpu(sbi->s_es->s_journal_inum)); if (ret) return ret; } if (test_opt(sb, DEBUG)) debug_print_tree(sbi); return 0; } /* Called when the filesystem is unmounted */ void ext4_release_system_zone(struct super_block *sb) { struct ext4_system_zone *entry, *n; rbtree_postorder_for_each_entry_safe(entry, n, &EXT4_SB(sb)->system_blks, node) kmem_cache_free(ext4_system_zone_cachep, entry); EXT4_SB(sb)->system_blks = RB_ROOT; } /* * Returns 1 if the passed-in block region (start_blk, * start_blk+count) is valid; 0 if some part of the block region * overlaps with filesystem metadata blocks. */ int ext4_data_block_valid(struct ext4_sb_info *sbi, ext4_fsblk_t start_blk, unsigned int count) { struct ext4_system_zone *entry; struct rb_node *n = sbi->system_blks.rb_node; if ((start_blk <= le32_to_cpu(sbi->s_es->s_first_data_block)) || (start_blk + count < start_blk) || (start_blk + count > ext4_blocks_count(sbi->s_es))) { sbi->s_es->s_last_error_block = cpu_to_le64(start_blk); return 0; } while (n) { entry = rb_entry(n, struct ext4_system_zone, node); if (start_blk + count - 1 < entry->start_blk) n = n->rb_left; else if (start_blk >= (entry->start_blk + entry->count)) n = n->rb_right; else { sbi->s_es->s_last_error_block = cpu_to_le64(start_blk); return 0; } } return 1; } int ext4_check_blockref(const char *function, unsigned int line, struct inode *inode, __le32 *p, unsigned int max) { struct ext4_super_block *es = EXT4_SB(inode->i_sb)->s_es; __le32 *bref = p; unsigned int blk; if (ext4_has_feature_journal(inode->i_sb) && (inode->i_ino == le32_to_cpu(EXT4_SB(inode->i_sb)->s_es->s_journal_inum))) return 0; while (bref < p+max) { blk = le32_to_cpu(*bref++); if (blk && unlikely(!ext4_data_block_valid(EXT4_SB(inode->i_sb), blk, 1))) { es->s_last_error_block = cpu_to_le64(blk); ext4_error_inode(inode, function, line, blk, "invalid block"); return -EFSCORRUPTED; } } return 0; }