Re: [PATCH v6 0/8] lsm: Replace security_sb_mount with granular mount hooks

Hi Christian and folks,

Could you please help review this set? Does this set address
concerns from earlier versions?

Thanks,
Song

On Mon, Jul 6, 2026 at 4:51 PM Song Liu <[email protected]> wrote:
>
> This series replaces the monolithic security_sb_mount() hook with
> per-operation mount hooks, addressing two main issues:
>
> 1. TOCTOU: security_sb_mount() receives dev_name as a string, which
>    LSMs like AppArmor and Tomoyo re-resolve via kern_path(). The new
>    hooks pass pre-resolved struct path pointers where possible (bind
>    mount, move mount), eliminating the double-resolution.
>
> 2. Conflation: security_sb_mount() handles bind, new mount, remount,
>    move, propagation changes, and mount reconfiguration through a
>    single hook, requiring LSMs to dispatch on flags internally. The
>    new hooks are called at the operation level with appropriate
>    context.
>
> The new hooks are:
>   mount_bind        - bind mount (pre-resolved source path)
>   mount_new         - new filesystem mount (with fs_context)
>   mount_remount     - filesystem remount (with fs_context)
>   mount_reconfigure - mount flag reconfiguration (MS_REMOUNT|MS_BIND)
>   mount_move        - move mount (pre-resolved paths)
>   mount_change_type - propagation type changes