The hardened project continues going forward…

This wednesday, the Gentoo Hardened team held its monthly online meeting, discussing the things that have been done the last few weeks and the ideas that are being worked out for the next. As I did with the last few meetings, allow me to summarize it for all interested parties…

Toolchain

The upstream GCC development on the 4.8 version progressed into its 3rd stage of its development cycle. Sadly, many of our hardened patches didn’t make the release. Zorry will continue working on these things, hopefully still being able to merge a few – and otherwise it’ll be for the next release.

For the MIPS platform, we might not be able to support the hardenedno* GCC profiles [1] in time. However, this is not seen as a blocker (we’re mostly interested in the hardened ones, not the ones without hardening ;-) so this could be done later on.

Blueness is migrating the stage building for the uclibc stages towards catalyst, providing more clean stages. For the amd64 and i686 platforms, the uclibc-hardened and uclibc-vanilla stages are already done, and mips32r2/uclibc is on the way. Later, ARM stages will be looked at. Other platforms, like little endian MIPS, are also on the roadmap.

Kernel

The latest hardened-sources (~arch) package contains a patch supporting the user.* namespace for extended attributes in tmpfs, as needed for the XATTR_PAX support [2]. However, this patch has not been properly investigated nor tested, so input is definitely welcome. During the meeting, it was suggested to cap the length of the attribute value and only allow the user.pax attribute, as we are otherwise allowing unprivileged applications to “grow data” in the kernel memory space (the tmpfs).

Prometheanfire confirmed that recent-enough kernels (3.5.4-r1 and later) with nested paging do not exhibit the performance issues reported earlier.

SELinux

The 20120725 upstream policies are stabilized on revision 5. Although a next revision is already available in the hardened-dev overlay, it will not be pushed to the main tree due to a broken admin interface. Revision 7 is slated to be made available later the same day to fix this, and is the next candidate for being pushed to the main tree.

The september-released newer userspace utilities for SELinux are also going to be stabilized in the next few days (at the time of writing this post, they are ;-). These also support epatch_user so that users and developers can easily add in patches to try out stuff without having to repackage the application themselves.

grSecurity and PaX

The toolchain support for PT_PAX (the ELF-header based PaX markings) is due to be removed soon, meaning that the XATTR_PAX support will need to be matured by then. This has a few consequences on available packages (which will need a bump and fix) such as elfix, but also on the pax-utils.eclass file (interested parties are kindly requested to test out the new eclass before it reaches “production”). Of course, it will also mean that the new PaX approach needs to be properly documented for end users and developers.

pipacs also mentioned that he is working on a paxctld daemon. Just like SELinux’ restorecond daemon, this deamon will look for files and check them against a known database of binaries with their appropriate PaX markings. If the markings are set differently (or not set), the paxctld daemon will rectify the situation. For Gentoo, this is less of a concern as we already set the proper information through the ebuilds.

Profiles

The old SELinux profiles, which were already deprecated for a while, have been removed from the portage tree. That means that all SELinux-using profiles use the features/selinux inclusion rather than a fully build (yet difficult to maintain) profile definition.

System Integrity

A few packages, needed to support or work with ima/evm, have been pushed to the hardened-dev overlay.

Documentation

The SELinux handbook has been updated with the latest policy changes (such as supporting the named init scripts). We also documented SELinux policy constraints which was long overdue.

So again a nice month of (volunteer) work on the security state of Gentoo Hardened. Thanks again to all (developers, contributors and users) for making Gentoo Hardened where it is today. Zorry will send out the meeting log later to the mailinglist, so you can look at the more gory details of the meeting if you want.

  • [1] GCC profiles are a set of parameters passed on to GCC as a “default” setting. Gentoo hardened uses GCC profiles to support using non-hardening features if the users wants to (through the gcc-config application).
  • [2] XATTR_PAX is a new way of handling PaX markings on binaries. Previously, we kept the PaX markings (i.e. flags telling the kernel PaX code to allow or deny specific behavior or enable certain memory-related hardening features for a specific application) as flags in the binary itself (inside the ELF header). With XATTR_PAX, this is moved to an extended attribute called “user.pax”.

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