Re: [stable/linux-6.18.y 2/2] selinux: fix overlayfs mmap() and mprotect() access checks

[Greg KH]

On Mon, Jun 22, 2026 at 11:14:16AM +0800, Cai Xinchen wrote:
> From: Paul Moore <paul@xxxxxxxxxxxxxx>
> 
> The existing SELinux security model for overlayfs is to allow access if
> the current task is able to access the top level file (the "user" file)
> and the mounter's credentials are sufficient to access the lower
> level file (the "backing" file).  Unfortunately, the current code does
> not properly enforce these access controls for both mmap() and mprotect()
> operations on overlayfs filesystems.
> 
> This patch makes use of the newly created security_mmap_backing_file()
> LSM hook to provide the missing backing file enforcement for mmap()
> operations, and leverages the backing file API and new LSM blob to
> provide the necessary information to properly enforce the mprotect()
> access controls.
> 
> Cc: stable@xxxxxxxxxxxxxxx
> Acked-by: Amir Goldstein <amir73il@xxxxxxxxx>
> Signed-off-by: Paul Moore <paul@xxxxxxxxxxxxxx>
> Signed-off-by: Cai Xinchen <caixinchen1@xxxxxxxxxx>
> ---
>  security/selinux/hooks.c          | 242 ++++++++++++++++++++++--------
>  security/selinux/include/objsec.h |  11 ++
>  2 files changed, 189 insertions(+), 64 deletions(-)

Again, what is the git id?

thanks,

greg k-h