modprobe Whitelist
Sommario
Add a whitelist of allowed modules and commands to modprobe, to allow the system administrator to limit the amount of (potentially vulnerable) code that can run in the kernel.
Progettista
- Nome: Miloslav Trmac
- Email:mitr@redhat.com
Stato corrente
- Targeted release: Fedora 13
Per informazioni aggiornate sullo stato del progetto consultare la pagina originale di questo documento.
Descrizione dettagliata
The kernel, and various user-space applications, can automatically load kernel modules necessary to handle certain actions (e.g. flash dish with a specific filesystem is attached, other hardware is plugged in, application uses a network protocol). This may allow even unprivileged users to cause loading kernel modules, and the kernel code may be vulnerable. This feature allows system administrators in high-security situations to limit the modules loaded by modprobe to a specific list of modules configured by the administrator, making it impossible for unprivileged users to exploit vulnerabilities in modules that are not ordinarily used by e.g. attaching hardware.
modprobe can also run specified commands instead of loading a module (using the "install" configuration directive); this is restricted using the same whitelist as well.
To help system administrators compile the whitelist, additional functionality is added to modprobe: it will be possible to log all information (similar to using "modprobe -v") to a specified file, including modprobe actions run in the dracut initrd. A script will be provided that compiles a proposed whitelist from the logged data.
Vantaggi per Fedora
If desired and configured by the system administrator, a significant reduction of the kernel-space attack surface, avoiding risk of vulnerabilities in rarely-used kernel-mode code.
A sample desktop Fedora 12 system currently has 79 modules loaded, out of 1964 available modules (4%). When counting code size, and the main kernel file (/boot/vmlinuz*) is included, the sample desktop system runs 8.36 MB of kernel-space code, out of 34.66 MB available (24%).
Documentazione
Included in the patch set:
- Updates to modprobe.conf(5).
- New man page for build-modprobe-whitelist(8)
Note di rilascio
(in "Security" section)
Fedora now allows system administrators to restrict the modules that can be automatically loaded into the kernel to a specific subset of explicitly chosen modules. This prevents attacks on vulnerable kernel code that is not necessary for ordinary system operation (e.g. by plugging in a flash drive with an unusual filesystem, by plugging in unusual hardware, initializing network connections using an unusual protocol). See build-modprobe-whitelist(8) for details.
Altre informazioni
Per:
- Obbiettivi
- Test Plan
- Esperienza Utente
- Dipendenze
- Progetto corrente
- Commenti e Discussioni
visitare la pagina originale di questo documento.