1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * linux/fs/ext4/block_validity.c 4 * 5 * Copyright (C) 2009 6 * Theodore Ts'o (tytso@mit.edu) 7 * 8 * Track which blocks in the filesystem are metadata blocks that 9 * should never be used as data blocks by files or directories. 10 */ 11 12 #include <linux/time.h> 13 #include <linux/fs.h> 14 #include <linux/namei.h> 15 #include <linux/quotaops.h> 16 #include <linux/buffer_head.h> 17 #include <linux/swap.h> 18 #include <linux/pagemap.h> 19 #include <linux/blkdev.h> 20 #include <linux/slab.h> 21 #include "ext4.h" 22 23 struct ext4_system_zone { 24 struct rb_node node; 25 ext4_fsblk_t start_blk; 26 unsigned int count; 27 }; 28 29 static struct kmem_cache *ext4_system_zone_cachep; 30 31 int __init ext4_init_system_zone(void) 32 { 33 ext4_system_zone_cachep = KMEM_CACHE(ext4_system_zone, 0); 34 if (ext4_system_zone_cachep == NULL) 35 return -ENOMEM; 36 return 0; 37 } 38 39 void ext4_exit_system_zone(void) 40 { 41 kmem_cache_destroy(ext4_system_zone_cachep); 42 } 43 44 static inline int can_merge(struct ext4_system_zone *entry1, 45 struct ext4_system_zone *entry2) 46 { 47 if ((entry1->start_blk + entry1->count) == entry2->start_blk) 48 return 1; 49 return 0; 50 } 51 52 /* 53 * Mark a range of blocks as belonging to the "system zone" --- that 54 * is, filesystem metadata blocks which should never be used by 55 * inodes. 56 */ 57 static int add_system_zone(struct ext4_sb_info *sbi, 58 ext4_fsblk_t start_blk, 59 unsigned int count) 60 { 61 struct ext4_system_zone *new_entry = NULL, *entry; 62 struct rb_node **n = &sbi->system_blks.rb_node, *node; 63 struct rb_node *parent = NULL, *new_node = NULL; 64 65 while (*n) { 66 parent = *n; 67 entry = rb_entry(parent, struct ext4_system_zone, node); 68 if (start_blk < entry->start_blk) 69 n = &(*n)->rb_left; 70 else if (start_blk >= (entry->start_blk + entry->count)) 71 n = &(*n)->rb_right; 72 else { 73 if (start_blk + count > (entry->start_blk + 74 entry->count)) 75 entry->count = (start_blk + count - 76 entry->start_blk); 77 new_node = *n; 78 new_entry = rb_entry(new_node, struct ext4_system_zone, 79 node); 80 break; 81 } 82 } 83 84 if (!new_entry) { 85 new_entry = kmem_cache_alloc(ext4_system_zone_cachep, 86 GFP_KERNEL); 87 if (!new_entry) 88 return -ENOMEM; 89 new_entry->start_blk = start_blk; 90 new_entry->count = count; 91 new_node = &new_entry->node; 92 93 rb_link_node(new_node, parent, n); 94 rb_insert_color(new_node, &sbi->system_blks); 95 } 96 97 /* Can we merge to the left? */ 98 node = rb_prev(new_node); 99 if (node) { 100 entry = rb_entry(node, struct ext4_system_zone, node); 101 if (can_merge(entry, new_entry)) { 102 new_entry->start_blk = entry->start_blk; 103 new_entry->count += entry->count; 104 rb_erase(node, &sbi->system_blks); 105 kmem_cache_free(ext4_system_zone_cachep, entry); 106 } 107 } 108 109 /* Can we merge to the right? */ 110 node = rb_next(new_node); 111 if (node) { 112 entry = rb_entry(node, struct ext4_system_zone, node); 113 if (can_merge(new_entry, entry)) { 114 new_entry->count += entry->count; 115 rb_erase(node, &sbi->system_blks); 116 kmem_cache_free(ext4_system_zone_cachep, entry); 117 } 118 } 119 return 0; 120 } 121 122 static void debug_print_tree(struct ext4_sb_info *sbi) 123 { 124 struct rb_node *node; 125 struct ext4_system_zone *entry; 126 int first = 1; 127 128 printk(KERN_INFO "System zones: "); 129 node = rb_first(&sbi->system_blks); 130 while (node) { 131 entry = rb_entry(node, struct ext4_system_zone, node); 132 printk(KERN_CONT "%s%llu-%llu", first ? "" : ", ", 133 entry->start_blk, entry->start_blk + entry->count - 1); 134 first = 0; 135 node = rb_next(node); 136 } 137 printk(KERN_CONT "\n"); 138 } 139 140 static int ext4_protect_reserved_inode(struct super_block *sb, u32 ino) 141 { 142 struct inode *inode; 143 struct ext4_sb_info *sbi = EXT4_SB(sb); 144 struct ext4_map_blocks map; 145 u32 i = 0, err = 0, num, n; 146 147 if ((ino < EXT4_ROOT_INO) || 148 (ino > le32_to_cpu(sbi->s_es->s_inodes_count))) 149 return -EINVAL; 150 inode = ext4_iget(sb, ino, EXT4_IGET_SPECIAL); 151 if (IS_ERR(inode)) 152 return PTR_ERR(inode); 153 num = (inode->i_size + sb->s_blocksize - 1) >> sb->s_blocksize_bits; 154 while (i < num) { 155 map.m_lblk = i; 156 map.m_len = num - i; 157 n = ext4_map_blocks(NULL, inode, &map, 0); 158 if (n < 0) { 159 err = n; 160 break; 161 } 162 if (n == 0) { 163 i++; 164 } else { 165 if (!ext4_data_block_valid(sbi, map.m_pblk, n)) { 166 ext4_error(sb, "blocks %llu-%llu from inode %u " 167 "overlap system zone", map.m_pblk, 168 map.m_pblk + map.m_len - 1, ino); 169 err = -EFSCORRUPTED; 170 break; 171 } 172 err = add_system_zone(sbi, map.m_pblk, n); 173 if (err < 0) 174 break; 175 i += n; 176 } 177 } 178 iput(inode); 179 return err; 180 } 181 182 int ext4_setup_system_zone(struct super_block *sb) 183 { 184 ext4_group_t ngroups = ext4_get_groups_count(sb); 185 struct ext4_sb_info *sbi = EXT4_SB(sb); 186 struct ext4_group_desc *gdp; 187 ext4_group_t i; 188 int flex_size = ext4_flex_bg_size(sbi); 189 int ret; 190 191 if (!test_opt(sb, BLOCK_VALIDITY)) { 192 if (sbi->system_blks.rb_node) 193 ext4_release_system_zone(sb); 194 return 0; 195 } 196 if (sbi->system_blks.rb_node) 197 return 0; 198 199 for (i=0; i < ngroups; i++) { 200 cond_resched(); 201 if (ext4_bg_has_super(sb, i) && 202 ((i < 5) || ((i % flex_size) == 0))) 203 add_system_zone(sbi, ext4_group_first_block_no(sb, i), 204 ext4_bg_num_gdb(sb, i) + 1); 205 gdp = ext4_get_group_desc(sb, i, NULL); 206 ret = add_system_zone(sbi, ext4_block_bitmap(sb, gdp), 1); 207 if (ret) 208 return ret; 209 ret = add_system_zone(sbi, ext4_inode_bitmap(sb, gdp), 1); 210 if (ret) 211 return ret; 212 ret = add_system_zone(sbi, ext4_inode_table(sb, gdp), 213 sbi->s_itb_per_group); 214 if (ret) 215 return ret; 216 } 217 if (ext4_has_feature_journal(sb) && sbi->s_es->s_journal_inum) { 218 ret = ext4_protect_reserved_inode(sb, 219 le32_to_cpu(sbi->s_es->s_journal_inum)); 220 if (ret) 221 return ret; 222 } 223 224 if (test_opt(sb, DEBUG)) 225 debug_print_tree(sbi); 226 return 0; 227 } 228 229 /* Called when the filesystem is unmounted */ 230 void ext4_release_system_zone(struct super_block *sb) 231 { 232 struct ext4_system_zone *entry, *n; 233 234 rbtree_postorder_for_each_entry_safe(entry, n, 235 &EXT4_SB(sb)->system_blks, node) 236 kmem_cache_free(ext4_system_zone_cachep, entry); 237 238 EXT4_SB(sb)->system_blks = RB_ROOT; 239 } 240 241 /* 242 * Returns 1 if the passed-in block region (start_blk, 243 * start_blk+count) is valid; 0 if some part of the block region 244 * overlaps with filesystem metadata blocks. 245 */ 246 int ext4_data_block_valid(struct ext4_sb_info *sbi, ext4_fsblk_t start_blk, 247 unsigned int count) 248 { 249 struct ext4_system_zone *entry; 250 struct rb_node *n = sbi->system_blks.rb_node; 251 252 if ((start_blk <= le32_to_cpu(sbi->s_es->s_first_data_block)) || 253 (start_blk + count < start_blk) || 254 (start_blk + count > ext4_blocks_count(sbi->s_es))) { 255 sbi->s_es->s_last_error_block = cpu_to_le64(start_blk); 256 return 0; 257 } 258 while (n) { 259 entry = rb_entry(n, struct ext4_system_zone, node); 260 if (start_blk + count - 1 < entry->start_blk) 261 n = n->rb_left; 262 else if (start_blk >= (entry->start_blk + entry->count)) 263 n = n->rb_right; 264 else { 265 sbi->s_es->s_last_error_block = cpu_to_le64(start_blk); 266 return 0; 267 } 268 } 269 return 1; 270 } 271 272 int ext4_check_blockref(const char *function, unsigned int line, 273 struct inode *inode, __le32 *p, unsigned int max) 274 { 275 struct ext4_super_block *es = EXT4_SB(inode->i_sb)->s_es; 276 __le32 *bref = p; 277 unsigned int blk; 278 279 while (bref < p+max) { 280 blk = le32_to_cpu(*bref++); 281 if (blk && 282 unlikely(!ext4_data_block_valid(EXT4_SB(inode->i_sb), 283 blk, 1))) { 284 es->s_last_error_block = cpu_to_le64(blk); 285 ext4_error_inode(inode, function, line, blk, 286 "invalid block"); 287 return -EFSCORRUPTED; 288 } 289 } 290 return 0; 291 } 292 293