24e54a65f6
Change all of the builds to use $(MAKE) instead of the /usr/bin/make. Download and build GNU make-4.2 if the wrong version is installed on the system. Re-invoke build/make-4.2/make with the target that was passed in once the correct make has been built. |
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build | ||
config | ||
initrd | ||
modules | ||
packages | ||
patches | ||
.gitignore | ||
cpio-clean | ||
FAQ.md | ||
fit-parse | ||
Makefile | ||
populate-lib | ||
README.md | ||
verity-sign |
Heads: the other side of TAILS
Heads is a configuration for laptops that tries to bring more security to commodity hardware. Among its goals are:
- Use free software on the boot path
- Move the root of trust into hardware (or at least the ROM bootblock)
- Measure and attest to the state of the firmware
- Measure and verify all filesystems
NOTE: It is a work in progress and not yet ready for users. If you're interested in contributing, please get in touch. Installation requires disassembly of your laptop or server, external SPI flash programmers, possible risk of destruction and significant frustration.
More information is available in the 33C3 presentation of building "Slightly more secure systems".
Building heads
Components:
- coreboot
- Linux
- busybox
- kexec
- tpmtotp (with qrencode)
- QubesOS (Xen)
The top level Makefile
will handle most of the details -- it downloads
the various packages, patches them, configures and builds, and then
copies the necessary parts into the initrd
directory.
Notes:
- Building coreboot's cross compilers can take a while. Luckily this is only done once.
- Builds are not reproducible; there are several issue with the reproduciblebuilds tag to track it.
- Currently only tested in Qemu and on a Thinkpad x230. Xen and the TPM do no t work in Qemu, so it is only for testing the
initrd
image. - Booting Qubes requires patching Xen's real mode startup code
see
patches/xen-4.6.3.patch
and addno-real-mode
to start of the Xen command line. Booting or installing Qubes is a bit hacky and needs to be documented. - Coreboot 4.4 does not handle initrd separately from the kernel correctly, so it must be bundled into the coreboot image. Building from git does the right thing.
Signing with GPG
gpgv
is a stripped down version of GPG that can be used to verify
signatures without extraneous libraries. This works well with the
Free Software workflow that we want to use.
gpg --clearsign roothash
The roothash
and roothash.sig
files can be embedded into the
HDD image and then extracted at firmware boot time:
gpgv --keyring /trustedkeys.gpg roothash.sig roothash \
|| echo "FAILED"
The mount-boot
script is a start at doing this automatically.
There needs to be an empty block at the end of the partition
that includes a signed script to be executed; typically it will
contain the dm-verity parameters to build the dmsetup
command
line to mount /boot
.
The boot script can't be stored in the boot filesystem since the dm-verity hashes that protect the filesystem would need to have their own hash pre-computed, which is not feasible with a good hashing algorithm. You could store the hashes in the ROM, but that would not allow upgrades without rewriting the ROM.
coreboot console messages
The coreboot console messages are stored in the CBMEM region
and can be read by the Linux payload with the cbmem --console | less
command. There is lots of interesting data about the state of the
system.