ext4: add ext4_iget_normal() which is to be used for dir tree lookups

commit f4bb2981024fc91b23b4d09a8817c415396dbabb upstream.

If there is a corrupted file system which has directory entries that
point at reserved, metadata inodes, prohibit them from being used by
treating them the same way we treat Boot Loader inodes --- that is,
mark them to be bad inodes.  This prohibits them from being opened,
deleted, or modified via chmod, chown, utimes, etc.

In particular, this prevents a corrupted file system which has a
directory entry which points at the journal inode from being deleted
and its blocks released, after which point Much Hilarity Ensues.

Reported-by: Sami Liedes <sami.liedes@iki.fi>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 40f4d06..6858d9d 100644 (file)
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -1874,6 +1874,7 @@ int ext4_get_block(struct inode *inode, sector_t iblock,
                                struct buffer_head *bh_result, int create);
 
 extern struct inode *ext4_iget(struct super_block *, unsigned long);
+extern struct inode *ext4_iget_normal(struct super_block *, unsigned long);
 extern int  ext4_write_inode(struct inode *, struct writeback_control *);
 extern int  ext4_setattr(struct dentry *, struct iattr *);
 extern int  ext4_getattr(struct vfsmount *mnt, struct dentry *dentry,

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index c343cdc..74c34c2 100644 (file)
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -3958,6 +3958,13 @@ bad_inode:
        return ERR_PTR(ret);
 }
 
+struct inode *ext4_iget_normal(struct super_block *sb, unsigned long ino)
+{
+       if (ino < EXT4_FIRST_INO(sb) && ino != EXT4_ROOT_INO)
+               return ERR_PTR(-EIO);
+       return ext4_iget(sb, ino);
+}
+
 static int ext4_inode_blocks_set(handle_t *handle,
                                struct ext4_inode *raw_inode,
                                struct ext4_inode_info *ei)

diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
index c4bf1ad..7ed4b03 100644 (file)
--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -1040,7 +1040,7 @@ static struct dentry *ext4_lookup(struct inode *dir, struct dentry *dentry, stru
                                         dentry->d_name.name);
                        return ERR_PTR(-EIO);
                }
-               inode = ext4_iget(dir->i_sb, ino);
+               inode = ext4_iget_normal(dir->i_sb, ino);
                if (inode == ERR_PTR(-ESTALE)) {
                        EXT4_ERROR_INODE(dir,
                                         "deleted inode referenced: %u",
@@ -1074,7 +1074,7 @@ struct dentry *ext4_get_parent(struct dentry *child)
                return ERR_PTR(-EIO);
        }
 
-       return d_obtain_alias(ext4_iget(child->d_inode->i_sb, ino));
+       return d_obtain_alias(ext4_iget_normal(child->d_inode->i_sb, ino));
 }
 
 #define S_SHIFT 12

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index f897cb8..422be11 100644 (file)
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -1185,7 +1185,7 @@ static struct inode *ext4_nfs_get_inode(struct super_block *sb,
         * Currently we don't know the generation for parent directory, so
         * a generation of 0 means "accept any"
         */
-       inode = ext4_iget(sb, ino);
+       inode = ext4_iget_normal(sb, ino);
        if (IS_ERR(inode))
                return ERR_CAST(inode);
        if (generation && inode->i_generation != generation) {