linux.git/fs/overlayfs, branch v4.13

ovl: check for bad and whiteout index on lookup

2017-07-20T09:08:21+00:00

Index should always be of the same file type as origin, except for
the case of a whiteout index.  A whiteout index should only exist
if all lower aliases have been unlinked, which means that finding
a lower origin on lookup whose index is a whiteout should be treated
as a lookup error.

Signed-off-by: Amir Goldstein 
Signed-off-by: Miklos Szeredi

ovl: do not cleanup directory and whiteout index entries

2017-07-20T09:08:21+00:00

Directory index entries are going to be used for looking up
redirected upper dirs by lower dir fh when decoding an overlay
file handle of a merge dir.

Whiteout index entries are going to be used as an indication that
an exported overlay file handle should be treated as stale (i.e.
after unlink of the overlay inode).

We don't know the verification rules for directory and whiteout
index entries, because they have not been implemented yet, so fail
to mount overlay rw if those entries are found to avoid corrupting
an index that was created by a newer kernel.

Signed-off-by: Amir Goldstein 
Signed-off-by: Miklos Szeredi

ovl: fix xattr get and set with selinux

2017-07-20T09:08:21+00:00

inode_doinit_with_dentry() in SELinux wants to read the upper inode's xattr
to get security label, and ovl_xattr_get() calls ovl_dentry_real(), which
depends on dentry->d_inode, but d_inode is null and not initialized yet at
this point resulting in an Oops.

Fix by getting the upperdentry info from the inode directly in this case.

Reported-by: Eryu Guan 
Fixes: 09d8b586731b ("ovl: move __upperdentry to ovl_inode")
Signed-off-by: Miklos Szeredi

ovl: remove unneeded check for IS_ERR()

2017-07-13T20:06:46+00:00

ovl_workdir_create() returns a valid index dentry or NULL.

Reported-by: Dan Carpenter 
Signed-off-by: Amir Goldstein 
Signed-off-by: Miklos Szeredi

ovl: fix origin verification of index dir

2017-07-13T20:06:46+00:00

Commit 54fb347e836f ("ovl: verify index dir matches upper dir")
introduced a new ovl_fh flag OVL_FH_FLAG_PATH_UPPER to indicate
an upper file handle, but forgot to add the flag to the mask of
valid flags, so index dir origin verification always discards
existing origin and stores a new one.

Signed-off-by: Amir Goldstein 
Signed-off-by: Miklos Szeredi

ovl: mark parent impure on ovl_link()

2017-07-13T20:06:45+00:00

When linking a file with copy up origin into a new parent, mark the
new parent dir "impure".

Fixes: ee1d6d37b6b8 ("ovl: mark upper dir with type origin entries "impure"")
Cc:  # v4.12
Signed-off-by: Amir Goldstein 
Signed-off-by: Miklos Szeredi

ovl: fix random return value on mount

2017-07-13T20:06:45+00:00

On failure to prepare_creds(), mount fails with a random
return value, as err was last set to an integer cast of
a valid lower mnt pointer or set to 0 if inodes index feature
is enabled.

Reported-by: Dan Carpenter 
Fixes: 3fe6e52f0626 ("ovl: override creds with the ones from ...")
Cc:  # v4.7
Signed-off-by: Amir Goldstein 
Signed-off-by: Miklos Szeredi

ovl: mark parent impure and restore timestamp on ovl_link_up()

2017-07-04T20:08:15+00:00

Signed-off-by: Amir Goldstein

ovl: cleanup orphan index entries

2017-07-04T20:03:19+00:00

index entry should live only as long as there are upper or lower
hardlinks.

Cleanup orphan index entries on mount and when dropping the last
overlay inode nlink.

When about to cleanup or link up to orphan index and the index inode
nlink > 1, admit that something went wrong and adjust overlay nlink
to index inode nlink - 1 to prevent it from dropping below zero.
This could happen when adding lower hardlinks underneath a mounted
overlay and then trying to unlink them.

Signed-off-by: Amir Goldstein 
Signed-off-by: Miklos Szeredi

ovl: persistent overlay inode nlink for indexed inodes

2017-07-04T20:03:19+00:00

With inodes index enabled, an overlay inode nlink counts the union of upper
and non-covered lower hardlinks. During the lifetime of a non-pure upper
inode, the following nlink modifying operations can happen:

1. Lower hardlink copy up
2. Upper hardlink created, unlinked or renamed over
3. Lower hardlink whiteout or renamed over

For the first, copy up case, the union nlink does not change, whether the
operation succeeds or fails, but the upper inode nlink may change.
Therefore, before copy up, we store the union nlink value relative to the
lower inode nlink in the index inode xattr trusted.overlay.nlink.

For the second, upper hardlink case, the union nlink should be incremented
or decremented IFF the operation succeeds, aligned with nlink change of the
upper inode. Therefore, before link/unlink/rename, we store the union nlink
value relative to the upper inode nlink in the index inode.

For the last, lower cover up case, we simplify things by preceding the
whiteout or cover up with copy up. This makes sure that there is an index
upper inode where the nlink xattr can be stored before the copied up upper
entry is unlink.

Return the overlay inode nlinks for indexed upper inodes on stat(2).

Signed-off-by: Amir Goldstein 
Signed-off-by: Miklos Szeredi