Re: [PATCH 03/10] fs: consistently use file_has_valid_mmap_hooks() helper

Kees Cook
2025-06-16T20:01:07Z

On June 16, 2025 12:33:22 PM PDT, Lorenzo Stoakes <lorenzo.stoakes@oracle.com> wrote:
>Since commit c84bf6dd2b83 ("mm: introduce new .mmap_prepare() file
>callback"), the f_op->mmap() hook has been deprecated in favour of
>f_op->mmap_prepare().
>
>Additionally, commit bb666b7c2707 ("mm: add mmap_prepare() compatibility
>layer for nested file systems") permits the use of the .mmap_prepare() hook
>even in nested filesystems like overlayfs.
>
>There are a number of places where we check only for f_op->mmap - this is
>incorrect now mmap_prepare exists, so update all of these to use the
>general helper file_has_valid_mmap_hooks().
>
>Most notably, this updates the elf logic to allow for the ability to
>execute binaries on filesystems which have the .mmap_prepare hook, but
>additionally we update nested filesystems.
>
>Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
>---
> fs/backing-file.c | 2 +-
> fs/binfmt_elf.c | 4 ++--
> fs/binfmt_elf_fdpic.c | 2 +-

Thanks for the refactoring!

Acked-by: Kees Cook<kees@kernel.org>

--
Kees Cook