[PATCH 2/2] ipe: Update documentation for script enforcement

[Fan Wu]

On Thu, Oct 23, 2025 at 4:37 PM Yanzhu Huang
<yanzhuhuang at linux.microsoft.com> wrote:
>
> This patch adds explanation of script enforcement mechanism in admin
> guide documentation. Describes how IPE supports integrity enforcement
> for indirectly executed scripts through the AT_EXECVE_CHECK flag, and
> how this differs from kernel enforcement for compiled executables.
>
> Signed-off-by: Yanzhu Huang <yanzhuhuang at linux.microsoft.com>
> ---
>  Documentation/admin-guide/LSM/ipe.rst | 15 ++++++++++++++-
>  1 file changed, 14 insertions(+), 1 deletion(-)
>
> diff --git a/Documentation/admin-guide/LSM/ipe.rst b/Documentation/admin-guide/LSM/ipe.rst
> index dc7088451f9d..1063256559a8 100644
> --- a/Documentation/admin-guide/LSM/ipe.rst
> +++ b/Documentation/admin-guide/LSM/ipe.rst
> @@ -95,7 +95,20 @@ languages when these scripts are invoked by passing these program files
>  to the interpreter. This is because the way interpreters execute these
>  files; the scripts themselves are not evaluated as executable code
>  through one of IPE's hooks, but they are merely text files that are read
> -(as opposed to compiled executables) [#interpreters]_.
> +(as opposed to compiled executables) [#interpreters]_. However, with the

All looks good to me, however, we could also update the
[#interpreters] reference to userspace-api/check_exec.

-Fan

> +introduction of the ``AT_EXECVE_CHECK`` flag, interpreters can use it to
> +signal the kernel that a script file will be executed, and request the
> +kernel to perform LSM security checks on it.
> +
> +IPE's EXECUTE operation enforcement differs between compiled executables and
> +interpreted scripts: For compiled executables, enforcement is triggered
> +automatically by the kernel during ``execve()``, ``execveat()``, ``mmap()``
> +and ``mprotect()`` syscalls when loading executable content. For interpreted
> +scripts, enforcement requires explicit interpreter integration using
> +``execveat()`` with ``AT_EXECVE_CHECK`` flag. Unlike exec syscalls that IPE
> +intercepts during the execution process, this mechanism needs the interpreter
> +to take the initiative, and existing interpreters won't be automatically
> +supported unless the signal call is added.
>
>  Threat Model
>  ------------
> --
> 2.43.0
>