| // 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 <linux/time.h> |
| #include <linux/fs.h> |
| #include <linux/namei.h> |
| #include <linux/quotaops.h> |
| #include <linux/buffer_head.h> |
| #include <linux/swap.h> |
| #include <linux/pagemap.h> |
| #include <linux/blkdev.h> |
| #include <linux/slab.h> |
| #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) |
| { |
| rcu_barrier(); |
| 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; |
| } |
| |
| static void release_system_zone(struct ext4_system_blocks *system_blks) |
| { |
| struct ext4_system_zone *entry, *n; |
| |
| rbtree_postorder_for_each_entry_safe(entry, n, |
| &system_blks->root, node) |
| kmem_cache_free(ext4_system_zone_cachep, entry); |
| } |
| |
| /* |
| * 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_system_blocks *system_blks, |
| ext4_fsblk_t start_blk, |
| unsigned int count) |
| { |
| struct ext4_system_zone *new_entry, *entry; |
| struct rb_node **n = &system_blks->root.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 /* Unexpected overlap of system zones. */ |
| return -EFSCORRUPTED; |
| } |
| |
| 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, &system_blks->root); |
| |
| /* 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, &system_blks->root); |
| 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, &system_blks->root); |
| 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->root); |
| 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"); |
| } |
| |
| /* |
| * 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. |
| */ |
| static int ext4_data_block_valid_rcu(struct ext4_sb_info *sbi, |
| struct ext4_system_blocks *system_blks, |
| ext4_fsblk_t start_blk, |
| unsigned int count) |
| { |
| struct ext4_system_zone *entry; |
| struct rb_node *n; |
| |
| 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; |
| } |
| |
| if (system_blks == NULL) |
| return 1; |
| |
| n = system_blks->root.rb_node; |
| 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; |
| } |
| |
| static int ext4_protect_reserved_inode(struct super_block *sb, |
| struct ext4_system_blocks *system_blks, |
| 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) { |
| cond_resched(); |
| 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_rcu(sbi, system_blks, |
| 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(system_blks, map.m_pblk, n); |
| if (err < 0) |
| break; |
| i += n; |
| } |
| } |
| iput(inode); |
| return err; |
| } |
| |
| static void ext4_destroy_system_zone(struct rcu_head *rcu) |
| { |
| struct ext4_system_blocks *system_blks; |
| |
| system_blks = container_of(rcu, struct ext4_system_blocks, rcu); |
| release_system_zone(system_blks); |
| kfree(system_blks); |
| } |
| |
| /* |
| * Build system zone rbtree which is used for block validity checking. |
| * |
| * The update of system_blks pointer in this function is protected by |
| * sb->s_umount semaphore. However we have to be careful as we can be |
| * racing with ext4_data_block_valid() calls reading system_blks rbtree |
| * protected only by RCU. That's why we first build the rbtree and then |
| * swap it in place. |
| */ |
| 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_system_blocks *system_blks; |
| struct ext4_group_desc *gdp; |
| ext4_group_t i; |
| int flex_size = ext4_flex_bg_size(sbi); |
| int ret; |
| |
| system_blks = kzalloc(sizeof(*system_blks), GFP_KERNEL); |
| if (!system_blks) |
| return -ENOMEM; |
| |
| for (i=0; i < ngroups; i++) { |
| cond_resched(); |
| if (ext4_bg_has_super(sb, i) && |
| ((i < 5) || ((i % flex_size) == 0))) |
| add_system_zone(system_blks, |
| 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(system_blks, |
| ext4_block_bitmap(sb, gdp), 1); |
| if (ret) |
| goto err; |
| ret = add_system_zone(system_blks, |
| ext4_inode_bitmap(sb, gdp), 1); |
| if (ret) |
| goto err; |
| ret = add_system_zone(system_blks, |
| ext4_inode_table(sb, gdp), |
| sbi->s_itb_per_group); |
| if (ret) |
| goto err; |
| } |
| if (ext4_has_feature_journal(sb) && sbi->s_es->s_journal_inum) { |
| ret = ext4_protect_reserved_inode(sb, system_blks, |
| le32_to_cpu(sbi->s_es->s_journal_inum)); |
| if (ret) |
| goto err; |
| } |
| |
| /* |
| * System blks rbtree complete, announce it once to prevent racing |
| * with ext4_data_block_valid() accessing the rbtree at the same |
| * time. |
| */ |
| rcu_assign_pointer(sbi->system_blks, system_blks); |
| |
| if (test_opt(sb, DEBUG)) |
| debug_print_tree(sbi); |
| return 0; |
| err: |
| release_system_zone(system_blks); |
| kfree(system_blks); |
| return ret; |
| } |
| |
| /* |
| * Called when the filesystem is unmounted or when remounting it with |
| * noblock_validity specified. |
| * |
| * The update of system_blks pointer in this function is protected by |
| * sb->s_umount semaphore. However we have to be careful as we can be |
| * racing with ext4_data_block_valid() calls reading system_blks rbtree |
| * protected only by RCU. So we first clear the system_blks pointer and |
| * then free the rbtree only after RCU grace period expires. |
| */ |
| void ext4_release_system_zone(struct super_block *sb) |
| { |
| struct ext4_system_blocks *system_blks; |
| |
| system_blks = rcu_dereference_protected(EXT4_SB(sb)->system_blks, |
| lockdep_is_held(&sb->s_umount)); |
| rcu_assign_pointer(EXT4_SB(sb)->system_blks, NULL); |
| |
| if (system_blks) |
| call_rcu(&system_blks->rcu, ext4_destroy_system_zone); |
| } |
| |
| int ext4_data_block_valid(struct ext4_sb_info *sbi, ext4_fsblk_t start_blk, |
| unsigned int count) |
| { |
| struct ext4_system_blocks *system_blks; |
| int ret; |
| |
| /* |
| * Lock the system zone to prevent it being released concurrently |
| * when doing a remount which inverse current "[no]block_validity" |
| * mount option. |
| */ |
| rcu_read_lock(); |
| system_blks = rcu_dereference(sbi->system_blks); |
| ret = ext4_data_block_valid_rcu(sbi, system_blks, start_blk, |
| count); |
| rcu_read_unlock(); |
| return ret; |
| } |
| |
| 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; |
| } |
| |