ext4: protect journal inode's blocks using block_validity

Add the blocks which belong to the journal inode to block_validity's
system zone so attempts to deallocate or overwrite the journal due a
corrupted file system where the journal blocks are also claimed by
another inode.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=202879
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@kernel.org

2 files changed, 52 insertions, 0 deletions

diff --git a/fs/ext4/block_validity.c b/fs/ext4/block_validity.c
index 913061c0de1b..9409b1e11a22 100644
--- a/fs/ext4/block_validity.c
+++ b/fs/ext4/block_validity.c
@@ -137,6 +137,48 @@ static void debug_print_tree(struct ext4_sb_info *sbi)
         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, err = 0, num, 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);
@@ -171,6 +213,12 @@ int ext4_setup_system_zone(struct super_block *sb)
                 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);
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 190f0478582a..609c8366d029 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -399,6 +399,10 @@ static int __check_block_validity(struct inode *inode, const char *func,
                                 unsigned int line,
                                 struct ext4_map_blocks *map)
 {
+        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;
         if (!ext4_data_block_valid(EXT4_SB(inode->i_sb), map->m_pblk,
                                    map->m_len)) {
                 ext4_error_inode(inode, func, line, map->m_pblk,