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There are essentially two ways for dealing with where to put the hash data for dm-verity block integrity checks. You can store both in a single partition, by using ~95% of the storage space for the filesystem and the remaining 5% tail for the hash, or you can use a completely separate partition (or even device) for storing the hash data elsewhere. Method A relies on using a hash offset argument during creation, which is generally OK from a scripted use case but is error prone when run from the command line and the offset calculated manually. Method B has the advantage of using the basic partition/device compartmentalization of the kernel to ensure the fs data doesn't overwrite the hash or vice versa. It takes any possible errors due to math miscalculations completely off the table. At the moment, our current support is hard coded to only support the offset method A. Here we add support for separate hash as per B. As multiple partitions are now in play, we use the UUID creation standard adopted by the systemd/verity community which implicitly links the root and hash partitions by splitting the top roothash in two for the UUIDs of the components. This change optionally creates the separate hash file but no examples use it yet. Further commits will implement an example. Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com> Signed-off-by: Armin Kuster <akuster808@gmail.com>
Meta-security
=============
The bbappend files for some recipes (e.g. linux-yocto) in this layer need
to have 'security' in DISTRO_FEATURES to have effect.
To enable them, add in configuration file the following line.
DISTRO_FEATURES:append = " security"
If meta-security is included, but security is not enabled as a
distro feature a warning is printed at parse time:
You have included the meta-security layer, but
'security' has not been enabled in your DISTRO_FEATURES. Some bbappend files
and preferred version setting may not take effect.
If you know what you are doing, this warning can be disabled by setting the following
variable in your configuration:
SKIP_META_SECURITY_SANITY_CHECK = 1
This layer provides security tools, hardening tools for Linux kernels
and libraries for implementing security mechanisms.
Dependencies
============
This layer depends on:
URI: git://git.openembedded.org/openembedded-core
branch: [same one as checked out for this layer]
URI: git://git.openembedded.org/meta-openembedded/meta-oe
branch: [same one as checked out for this layer]
Adding the security layer to your build
========================================
In order to use this layer, you need to make the build system aware of
it.
Assuming the security layer exists at the top-level of your
yocto build tree, you can add it to the build system by adding the
location of the security layer to bblayers.conf, along with any
other layers needed. e.g.:
BBLAYERS ?= " \
/path/to/oe-core/meta \
/path/to/meta-openembedded/meta-oe \
/path/to/layer/meta-security "
Optional Dynamic layer dependancy
======================================
URI: git://git.openembedded.org/meta-openembedded/meta-oe
URI: git://git.openembedded.org/meta-openembedded/meta-perl
URI: git://git.openembedded.org/meta-openembedded/meta-python
BBLAYERS += "/path/to/layer/meta-openembedded/meta-oe"
BBLAYERS += "/path/to/layer/meta-openembedded/meta-perl"
BBLAYERS += "/path/to/layer/meta-openembedded/meta-python"
This will activate the dynamic-layer mechanism.
Maintenance
======================================
Send pull requests, patches, comments or questions to yocto@lists.yoctoproject.org
When sending single patches, please using something like:
'git send-email -1 --to yocto@lists.yoctoproject.org --subject-prefix=meta-security][PATCH'
These values can be set as defaults for this repository:
$ git config sendemail.to yocto@lists.yoctoproject.org
$ git config format.subjectPrefix meta-security][PATCH
Now you can just do 'git send-email origin/master' to send all local patches.
For pull requests, please use create-pull-request and send-pull-request.
Maintainers: Armin Kuster <akuster808@gmail.com>
License
=======
All metadata is MIT licensed unless otherwise stated. Source code included
in tree for individual recipes is under the LICENSE stated in each recipe
(.bb file) unless otherwise stated.