[ Upstream commit 6af36aeb147a06dea47c49859cd6ca5659aeb987 ]

Stacked filesystems such as overlayfs do not currently provide the
necessary mechanisms for LSMs to properly enforce access controls on the
mmap() and mprotect() operations.  In order to resolve this gap, a LSM
security blob is being added to the backing_file struct and the following
new LSM hooks are being created:

 security_backing_file_alloc()
 security_backing_file_free()
 security_mmap_backing_file()

The first two hooks are to manage the lifecycle of the LSM security blob
in the backing_file struct, while the third provides a new mmap() access
control point for the underlying backing file.  It is also expected that
LSMs will likely want to update their security_file_mprotect() callback
to address issues with their mprotect() controls, but that does not
require a change to the security_file_mprotect() LSM hook.

There are a three other small changes to support these new LSM hooks:
* Pass the user file associated with a backing file down to
alloc_empty_backing_file() so it can be included in the
security_backing_file_alloc() hook.
* Add getter and setter functions for the backing_file struct LSM blob
as the backing_file struct remains private to fs/file_table.c.
* Constify the file struct field in the LSM common_audit_data struct to
better support LSMs that need to pass a const file struct pointer into
the common LSM audit code.

Thanks to Arnd Bergmann for identifying the missing EXPORT_SYMBOL_GPL()
and supplying a fixup.

Cc: stable@vger.kernel.org
Cc: linux-fsdevel@vger.kernel.org
Cc: linux-unionfs@vger.kernel.org
Cc: linux-erofs@lists.ozlabs.org
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Serge Hallyn <serge@hallyn.com>
Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Paul Moore <paul@paul-moore.com>
[Mainline declares lsm_backing_file_cache in security/lsm.h.  Linux 6.18.y
does not have security/lsm_init.c or security/lsm.h; the cache variable
is defined locally as static struct kmem_cache *lsm_backing_file_cache in
security/security.c.]
Signed-off-by: Cai Xinchen <caixinchen1@huawei.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

commit 53a7c171e9dd833f0a96b545adcb89bd57387239 upstream.

The implicit FILEID_INO32_GEN encoder was changed to be explicit,
so we need to fix the detection.

When mounting overlayfs with upperdir and lowerdir on different ext4
filesystems, the expected kmsg log is:

  overlayfs: "xino" feature enabled using 32 upper inode bits.

But instead, since the regressing commit, the kmsg log was:

  overlayfs: "xino" feature enabled using 2 upper inode bits.

Fixes: e21fc2038c1b9 ("exportfs: make ->encode_fh() a mandatory method for NFS export")
Cc: stable@vger.kernel.org # v6.7+
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

commit 1f6ee9be92f8df85a8c9a5a78c20fd39c0c21a95 upstream.

Commit 7d6899fb69d25 ("ovl: fsync after metadata copy-up") was done to
fix durability of overlayfs copy up on an upper filesystem which does
not enforce ordering on storing of metadata changes (e.g. ubifs).

In an earlier revision of the regressing commit by Lei Lv, the metadata
fsync behavior was opt-in via a new "fsync=strict" mount option.
We were hoping that the opt-in mount option could be avoided, so the
change was only made to depend on metacopy=off, in the hope of not
hurting performance of metadata heavy workloads, which are more likely
to be using metacopy=on.

This hope was proven wrong by a performance regression report from Google
COS workload after upgrade to kernel 6.12.

This is an adaptation of Lei's original "fsync=strict" mount option
to the existing upstream code.

The new mount option is mutually exclusive with the "volatile" mount
option, so the latter is now an alias to the "fsync=volatile" mount
option.

Reported-by: Chenglong Tang <chenglongtang@google.com>
Closes: https://lore.kernel.org/linux-unionfs/CAOdxtTadAFH01Vui1FvWfcmQ8jH1O45owTzUcpYbNvBxnLeM7Q@mail.gmail.com/
Link: https://lore.kernel.org/linux-unionfs/CAOQ4uxgKC1SgjMWre=fUb00v8rxtd6sQi-S+dxR8oDzAuiGu8g@mail.gmail.com/
Fixes: 7d6899fb69d25 ("ovl: fsync after metadata copy-up")
Depends: 50e638beb67e0 ("ovl: Use str_on_off() helper in ovl_show_options()")
Cc: stable@vger.kernel.org # v6.12+
Signed-off-by: Fei Lv <feilv@asrmicro.com>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

[ Upstream commit 1992330d90dd766fcf1730fd7bf2d6af65370ac4 ]

Syzbot reported a KMSAN uninit-value issue in ovl_fill_real.

This iusse's call chain is:
__do_sys_getdents64()
    -> iterate_dir()
        ...
            -> ext4_readdir()
                -> fscrypt_fname_alloc_buffer() // alloc
                -> fscrypt_fname_disk_to_usr // write without tail '\0'
                -> dir_emit()
                    -> ovl_fill_real() // read by strcmp()

The string is used to store the decrypted directory entry name for an
encrypted inode. As shown in the call chain, fscrypt_fname_disk_to_usr()
write it without null-terminate. However, ovl_fill_real() uses strcmp() to
compare the name against "..", which assumes a null-terminated string and
may trigger a KMSAN uninit-value warning when the buffer tail contains
uninit data.

Reported-by: syzbot+d130f98b2c265fae5297@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=d130f98b2c265fae5297
Fixes: 4edb83bb1041 ("ovl: constant d_ino for non-merge dirs")
Signed-off-by: Qing Wang <wangqing7171@gmail.com>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Link: https://patch.msgid.link/20260128132406.23768-2-amir73il@gmail.com
Acked-by: Miklos Szeredi <mszeredi@redhat.com>
Reviewed-by: Eric Biggers <ebiggers@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

As well as checking that the parent hasn't changed after getting the
lock we need to check that the dentry hasn't been unhashed.
Otherwise we might try to rename something that has been removed.

Reported-by: syzbot+bfc9a0ccf0de47d04e8c@syzkaller.appspotmail.com
Fixes: d2c995581c7c ("ovl: Call ovl_create_temp() without lock held.")
Signed-off-by: NeilBrown <neil@brown.name>
Link: https://patch.msgid.link/176429295510.634289.1552337113663461690@noble.neil.brown.name
Tested-by: syzbot+bfc9a0ccf0de47d04e8c@syzkaller.appspotmail.com
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>

The backing_file_write_iter() function, which is called
immediately after this code, already contains identical
logic to clear the IOCB_DIO_CALLER_COMP flag along with
the same explanatory comment. There is no need to duplicate
this operation in the overlayfs code.

Signed-off-by: Seong-Gwang Heo <heo@mykernel.net>
Fixes: a6293b3e285c ("fs: factor out backing_file_{read,write}_iter() helpers")
Acked-by: Miklos Szeredi <mszeredi@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>

This reverts commit 474b155adf3927d2c944423045757b54aa1ca4de.

This patch caused regression in ioctl_setflags(). Underlying filesystems
use EOPNOTSUPP to indicate that flag is not supported. This error is
also gets converted in ioctl_setflags(). Therefore, for unsupported
flags error changed from EOPNOSUPP to ENOIOCTLCMD.

Link: https://lore.kernel.org/linux-xfs/a622643f-1585-40b0-9441-cf7ece176e83@kernel.org/
Signed-off-by: Andrey Albershteyn <aalbersh@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>

Pull file->f_path constification from Al Viro:
 "Only one thing was modifying ->f_path of an opened file - acct(2).

  Massaging that away and constifying a bunch of struct path * arguments
  in functions that might be given &file->f_path ends up with the
  situation where we can turn ->f_path into an anon union of const
  struct path f_path and struct path __f_path, the latter modified only
  in a few places in fs/{file_table,open,namei}.c, all for struct file
  instances that are yet to be opened"

* tag 'pull-f_path' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (23 commits)
  Have cc(1) catch attempts to modify ->f_path
  kernel/acct.c: saner struct file treatment
  configfs:get_target() - release path as soon as we grab configfs_item reference
  apparmor/af_unix: constify struct path * arguments
  ovl_is_real_file: constify realpath argument
  ovl_sync_file(): constify path argument
  ovl_lower_dir(): constify path argument
  ovl_get_verity_digest(): constify path argument
  ovl_validate_verity(): constify {meta,data}path arguments
  ovl_ensure_verity_loaded(): constify datapath argument
  ksmbd_vfs_set_init_posix_acl(): constify path argument
  ksmbd_vfs_inherit_posix_acl(): constify path argument
  ksmbd_vfs_kern_path_unlock(): constify path argument
  ksmbd_vfs_path_lookup_locked(): root_share_path can be const struct path *
  check_export(): constify path argument
  export_operations->open(): constify path argument
  rqst_exp_get_by_name(): constify path argument
  nfs: constify path argument of __vfs_getattr()
  bpf...d_path(): constify path argument
  done_path_create(): constify path argument
  ...

Pull overlayfs updates from Amir Goldstein:

 - Work by André Almeida to support case-insensitive overlayfs

   Underlying case-insensitive filesystems casefolding is per directory,
   but for overlayfs it is all-or-nothing. It supports layers where all
   directories are casefolded (with same encoding) or layers where no
   directories are casefolded.

 - A fix for a "bug" in Neil's ovl directory lock changes, which only
   manifested itself with casefold enabled layers which may return an
   unhashed negative dentry from lookup.

* tag 'ovl-update-6.18' of git://git.kernel.org/pub/scm/linux/kernel/git/overlayfs/vfs:
  ovl: make sure that ovl_create_real() returns a hashed dentry
  ovl: Support mounting case-insensitive enabled layers
  ovl: Check for casefold consistency when creating new dentries
  ovl: Add S_CASEFOLD as part of the inode flag to be copied
  ovl: Set case-insensitive dentry operations for ovl sb
  ovl: Ensure that all layers have the same encoding
  ovl: Create ovl_casefold() to support casefolded strncmp()
  ovl: Prepare for mounting case-insensitive enabled layers
  fs: Create sb_same_encoding() helper
  fs: Create sb_encoding() helper

Pull vfs async directory updates from Christian Brauner:
 "This contains further preparatory changes for the asynchronous directory
  locking scheme:

   - Add lookup_one_positive_killable() which allows overlayfs to
     perform lookup that won't block on a fatal signal

   - Unify the mount idmap handling in struct renamedata as a rename can
     only happen within a single mount

   - Introduce kern_path_parent() for audit which sets the path to the
     parent and returns a dentry for the target without holding any
     locks on return

   - Rename kern_path_locked() as it is only used to prepare for the
     removal of an object from the filesystem:

	kern_path_locked()    => start_removing_path()
	kern_path_create()    => start_creating_path()
	user_path_create()    => start_creating_user_path()
	user_path_locked_at() => start_removing_user_path_at()
	done_path_create()    => end_creating_path()
	NA                    => end_removing_path()"

* tag 'vfs-6.18-rc1.async' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
  debugfs: rename start_creating() to debugfs_start_creating()
  VFS: rename kern_path_locked() and related functions.
  VFS/audit: introduce kern_path_parent() for audit
  VFS: unify old_mnt_idmap and new_mnt_idmap in renamedata
  VFS: discard err2 in filename_create()
  VFS/ovl: add lookup_one_positive_killable()