[PATCH v6] backing_file: store user_path_file

[Paul Moore]

On Wed, Mar 18, 2026 at 9:13 AM Amir Goldstein <amir73il at gmail.com> wrote:
>
> Instead of storing the user_path, store an O_PATH file for the
> user_path with the original user file creds and a security context.
>
> The user_path_file is only exported as a const pointer and its refcnt
> is initialized to FILE_REF_DEAD, because it is not a refcounted object.
>
> The file_ref_init() helper was changed to accept the FILE_REF_ constant
> instead of the fake +1 integer count.
>
> Signed-off-by: Amir Goldstein <amir73il at gmail.com>
> ---
>
> Christian,
>
> My v5 patch was sent by Paul along with his LSM/selinux pataches [1].
> Here are the changes you requested.
>
> I removed the ACKs and Tested-by because of the changes.
>
> Thanks,
> Amir.
>
> Changes since v5:
> - Restore file_ref_init() helper without refcnt -1 offset
> - Future proofing errors from backing_file_open_user_path()
>
> [1] https://lore.kernel.org/r/20260316213606.374109-6-paul@paul-moore.com/
>
>  fs/backing-file.c            | 26 ++++++++++--------
>  fs/erofs/ishare.c            | 13 +++++++--
>  fs/file_table.c              | 53 ++++++++++++++++++++++++++++--------
>  fs/fuse/passthrough.c        |  3 +-
>  fs/internal.h                |  5 ++--
>  fs/overlayfs/dir.c           |  3 +-
>  fs/overlayfs/file.c          |  1 +
>  include/linux/backing-file.h | 29 ++++++++++++++++++--
>  include/linux/file_ref.h     |  4 +--
>  9 files changed, 103 insertions(+), 34 deletions(-)

Still works for me.  I'm going to update lsm/stable-7.0 with this
patch so we can get some more linux-next testing.

Tested-by: Paul Moore <paul at paul-moore.com>

-- 
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