Auditd in Yocto - yocto

I'm trying to add auditd to Yocto linux.
I added the selinux layer and it's dependent layers: openembedded-core and meta-virtualization.
I added the layers to bblayers.conf.
I added DISTRO_FEATURES_append = " acl xattr pam selinux"
and PREFERRED_PROVIDER_virtual/refpolicy ?= "refpolicy-mls" to the local.conf file.
After building (by using bitbake core-image-base) and running the qemu, the kauditd process is running, but all user-space tools are not.
The /etc/audit folder is not exist ,non of the audit's config files exists (audit.rules) and no user-space audit process is running.
In the layer's info it is declared - "User space tools for kernel auditing".
What I am missing?
Thanks.

I think I found something that will answer your question: If you know what an example binary or library you expect to be in the target image, you can find what recipe the executable is in, and then add that package to the image.
Start with the name of a binary or library you expect to be in the image and run the following. For me, I am using a CAN bus executable called candump. I wonder what recipe it's in? To find out, I issue:
devtool search candump
Which returns:
can-utils
If nothing is returned, I'd double check your conf/bblayers.conf so that the layer you think it may be in is actually being seen by your build system. If you are unsure, take a look at the link below which points to OpenEmbedded which has a handy search utility for packages.
After you find the recipe, you can then include that recipe into your build.
Here is a good reference in doing what I think you're asking on the OpenEmbedded website:
https://wiki.yoctoproject.org/wiki/Cookbook:Example:Adding_packages_to_your_OS_image

I just added auditd to my system. This is what I did.
First I got the repository checked out.
cd /path/to/yocto
git clone git://git.yoctoproject.org/meta-selinux
cd meta-selinux
# checkout the branch matching the Yocto release you are on
git checkout thud
Then I added auditd to my build.
cd /path/to/build
bitbake-layers add-layer /path/to/yocto/meta-selinux
cat >> conf/local.conf <<'END'
IMAGE_INSTALL_append = " auditd"
END
bitbake my_normal_image_target
Even though the Yocto recipe is called audit, the package name is auditd.
Of course, auditd without selinux is useless but it did attempt to run (journalctl -u auditd) and /etc/audit exists.
FWIW: To get auditd to a point where it reports say, login success/failure, I had to do a few more things. I'm not just adding it to a standard Yocto image, but to a custom image and custom machine. I'm already using systemd so I didn't have to change that (the layer seems to indicate it's required?). My local.conf looked like this.
# enable selinux
DISTRO_FEATURES_append = " acl xattr pam selinux"
# set the policy
PREFERRED_PROVIDER_virtual/refpolicy ?= "refpolicy-mls"
# install selinux packages and auditd
IMAGE_INSTALL_append = " packagegroup-core-selinux auditd"
# tell the kernel to enable selinux (non-enforcing) and audting
APPEND_append = " selinux=1 enforcing=0 audit=1"
I also had to change linux-yocto_selinux.inc to load selinux.cfg later. Probably layer/recipe ordering could have solved this too?
-SRC_URI += "${#bb.utils.contains('DISTRO_FEATURES', 'selinux', 'file://selinux.cfg', '', d)}"
+SRC_URI_append = "${#bb.utils.contains('DISTRO_FEATURES', 'selinux', 'file://selinux.cfg', '', d)}"
With all that in place, I see audit logs in my journal.

Related

Yocto: Data file clashes build error while enabling libvirt

While enabling libvirt in yocto, I am seeing below data file clash issue while building yocto image,
Below are the packages I am trying to append install to my yocto image
IMAGE_INSTALL_append = " \
packagegroup-core-boot \
qemu \
libvirt \
libvirt-libvirtd \
libvirt-virsh \
kernel-module-kvm \
kernel-module-kvm-intel \
"
But I see below issue, when I build image enabling above packages,
`Collected errors:
check_data_file_clashes: Package iptables wants to install file /-/-/-/rootfs/etc/ethertypes
But that file is already provided by package * ebtables`
FYI: I see that libvirt has both iptables and ebtables dependency.
can someone help on understanding this and how to resolve?
I tried to remove ebtables with PACKAGECONFIG_remove = "ebtables" and image is built but I when starting libvirtd service it is always in dead mode and I see some issue related to socket.
Actually, this is a problem that has no solution except:
Remove one of the packages (ebtables or iptables)
Remove the file ethertypes from one of the recipes
libvirt depends on iptables on compile time only, so I did not know why iptables is present in the image ?
Anyways, it has a config on ebtables and from your comment when you removed it from PACKAGECONFIG it failed to work. So:
I suggest check if iptables is required by other package at run time, if not remove it.
If both are required in your case, then go for the second solution which is removing the file from one of the recipes, using a bbappend file for one of them:
The block that you may need to add is:
do_install_append() {
rm ${D}/etc/ethertypes
}
either to:
meta-custom/recipes-filter/ebtables/ebtables_%.bbappend
or to:
meta-custom/recipes-extended/iptables/iptables_%.bbappend
NOTE
If you go for the second solution, you need to make sure that the file is not present in the FILES variable of the recipe that you will remove the file from, FILES_ebtables or FILES_iptables.

Include systemd-journal-remote with Bitbake

I am using an embedded Linux system based on Yocto/Open Embedded Linux and the systemd-journald-remote program is missing.
When I look at the systemd recipe the program is mentioned. It seems like it is not compiled or added by default to the image. I understand how to add normal recipes but unfortunately I don't understand how to add such a "subpackage".
The Bitbake documentation is unfortunately overwhelming for a beginner like me. Can someone help me?
Create bbappend for systemd in your meta-layer with following path recipes-core/systemd/systemd_%.bbappend and:
PACKAGECONFIG_append = " \
microhttpd \
"
You can add it into your image .bb or .bbappend file with following parameter:
IMAGE_INSTALL += "systemd-journal-remote"
This will add systemd-journal-remote into your image. Install the image on your target board, log in to your target and configure the file /etc/systemd/journal-remote.conf.
Then, enable the service with systemctl enable systemd-journal-remote, and then restart it with systemctl restart systemd-journal-remote.

How to remove getty#tty1 link in yocto dunfell branch at time of compiliation

I am building linux system for raspberrypi4 but for some reason I need to remove getty#tty1 service in yocto.
I have created systemd_%.bbappend file for that.
Host PC is Ubuntu 18.04
this is working with warrior branch
Now, I am trying to compile with dunfell branch in yocto
but at the time of systemd compiling it gives an error like
"cannot remove /etc/systemd/system/getty.target.wants/getty#tty1, no such file or deirectory
But at the end, In final image there I can see getty#tty1.service
Also I can't find any other receipe that creates this link.
systemd_%.bbappend looks like this
DESCRIPTION = "Customization of systemD services."
do_install_append() {
rm ${D}${sysconfdir}/systemd/system/getty.target.wants/getty#tty1.service
}
FILES_${PN} += "${sysconfdir}/systemd/system"
REQUIRED_DISTRO_FEATURES= "systemd"
Thanks
Margish
On more recent versions of systemd (like the one in Yocto dunfell), the links to services are not created by the build system (ninja), but instead by running systemctl preset-all on the running system after installation (see here). This command reads the systemd preset files to determine which units to enable or disable by default.
In Yocto, what this means is that instead of the links being created as part of the systemd recipe, systemctl preset-all is run as part of the IMAGE_PREPROCESS_COMMAND during image creation in image.bbclass (see here). This is why the old method of deleting the symbolic links in /etc/systemd/system from the systemd recipe no longer works.
Instead, what you need to do is modify the 90-systemd.preset file to disable the getty#tty1 preset (or any other default system service) by changing the below line:
enable getty#.service
to this:
disable getty#.service
You can accomplish this using a bbappend file as follows*:
# systemd_%.bbappend
do_install_append() {
# Disable getty#tty1 from starting at boot time.
sed -i -e "s/enable getty#.service/disable getty#.service/g" ${D}${systemd_unitdir}/system-preset/90-systemd.preset
}
*https://stackoverflow.com/a/67505478/286701

Yocto remove unused init system (on per-image basis)

I would like to change the init system on a per-image basis.
I have created a sample image as pointed out here.
This works well, but I also want to remove the unused init system (in this case SysVinit) from rootfs.
Therefore I tried something like this inside my distro config: (REQUIRED_DISTRO_FEATURES = "systemd" is set inside my image.bb)
DISTRO_FEATURES_BACKFILL_CONSIDERED = "${#bb.utils.contains('REQUIRED_DISTRO_FEATURES', 'systemd', 'sysvinit', '', d)}"
Finally it results into this, exactly what I expect:
$ bitbake sample-image-systemd -e | grep DISTRO_FEATURES_BACKFILL_CONSIDERED=
DISTRO_FEATURES_BACKFILL_CONSIDERED="sysvinit"
So far so good. But the final rootfs still contains sysvinit scripts (/etc/init.d/*)
If I do the following inside my distro config everything works well and /etc/init.d is not created:
DISTRO_FEATURES_BACKFILL_CONSIDERED = "sysvinit"
So I don't really understand the difference and why my solution doesn't work.
The difference is that that systemd recipe does not have a dependency to your recipe which is good because if it had it would be a circular dependency. So, variables defined in your recipe are not expanded or accessible by the systemd recipe
Now to better explain this you can run the following command.
$ bitbake systemd -e | grep DISTRO_FEATURES_BACKFILL_CONSIDERED=
The result should be
DISTRO_FEATURES_BACKFILL_CONSIDERED=""
This happens because the sample-image-systemd recipe variables are not expanded and used while you are building/packaging/etc the systemd recipe. To make a variable global or accessible by all recipes you should add it to your distro config or your local config.

How can I get "HelloWorld - BitBake Style" working on a newer version of Yocto?

In the book "Embedded Linux Systems with the Yocto Project", Chapter 4 contains a sample called "HelloWorld - BitBake style". I encountered a bunch of problems trying to get the old example working against the "Sumo" release 2.5.
If you're like me, the first error you encountered following the book's instructions was that you copied across bitbake.conf and got:
ERROR: ParseError at /tmp/bbhello/conf/bitbake.conf:749: Could not include required file conf/abi_version.conf
And after copying over abi_version.conf as well, you kept finding more and more cross-connected files that needed to be moved, and then some relative-path errors after that... Is there a better way?
Here's a series of steps which can allow you to bitbake nano based on the book's instructions.
Unless otherwise specified, these samples and instructions are all based on the online copy of the book's code-samples. While convenient for copy-pasting, the online resource is not totally consistent with the printed copy, and contains at least one extra bug.
Initial workspace setup
This guide assumes that you're working with Yocto release 2.5 ("sumo"), installed into /tmp/poky, and that the build environment will go into /tmp/bbhello. If you don't the Poky tools+libraries already, the easiest way is to clone it with:
$ git clone -b sumo git://git.yoctoproject.org/poky.git /tmp/poky
Then you can initialize the workspace with:
$ source /tmp/poky/oe-init-build-env /tmp/bbhello/
If you start a new terminal window, you'll need to repeat the previous command which will get get your shell environment set up again, but it should not replace any of the files created inside the workspace from the first time.
Wiring up the defaults
The oe-init-build-env script should have just created these files for you:
bbhello/conf/local.conf
bbhello/conf/templateconf.cfg
bbhello/conf/bblayers.conf
Keep these, they supersede some of the book-instructions, meaning that you should not create or have the files:
bbhello/classes/base.bbclass
bbhello/conf/bitbake.conf
Similarly, do not overwrite bbhello/conf/bblayers.conf with the book's sample. Instead, edit it to add a single line pointing to your own meta-hello folder, ex:
BBLAYERS ?= " \
${TOPDIR}/meta-hello \
/tmp/poky/meta \
/tmp/poky/meta-poky \
/tmp/poky/meta-yocto-bsp \
"
Creating the layer and recipe
Go ahead and create the following files from the book-samples:
meta-hello/conf/layer.conf
meta-hello/recipes-editor/nano/nano.bb
We'll edit these files gradually as we hit errors.
Can't find recipe error
The error:
ERROR: BBFILE_PATTERN_hello not defined
It is caused by the book-website's bbhello/meta-hello/conf/layer.conf being internally inconsistent. It uses the collection-name "hello" but on the next two lines uses _test suffixes. Just change them to _hello to match:
# Set layer search pattern and priority
BBFILE_COLLECTIONS += "hello"
BBFILE_PATTERN_hello := "^${LAYERDIR}/"
BBFILE_PRIORITY_hello = "5"
Interestingly, this error is not present in the printed copy of the book.
No license error
The error:
ERROR: /tmp/bbhello/meta-hello/recipes-editor/nano/nano.bb: This recipe does not have the LICENSE field set (nano)
ERROR: Failed to parse recipe: /tmp/bbhello/meta-hello/recipes-editor/nano/nano.bb
Can be fixed by adding a license setting with one of the values that bitbake recognizes. In this case, add a line onto nano.bb of:
LICENSE="GPLv3"
Recipe parse error
ERROR: ExpansionError during parsing /tmp/bbhello/meta-hello/recipes-editor/nano/nano.bb
[...]
bb.data_smart.ExpansionError: Failure expanding variable PV_MAJOR, expression was ${#bb.data.getVar('PV',d,1).split('.')[0]} which triggered exception AttributeError: module 'bb.data' has no attribute 'getVar'
This is fixed by updating the special python commands being used in the recipe, because #bb.data was deprecated and is now removed. Instead, replace it with #d, ex:
PV_MAJOR = "${#d.getVar('PV',d,1).split('.')[0]}"
PV_MINOR = "${#d.getVar('PV',d,1).split('.')[1]}"
License checksum failure
ERROR: nano-2.2.6-r0 do_populate_lic: QA Issue: nano: Recipe file fetches files and does not have license file information (LIC_FILES_CHKSUM) [license-checksum]
This can be fixed by adding a directive to the recipe telling it what license-info-containing file to grab, and what checksum we expect it to have.
We can follow the way the recipe generates the SRC_URI, and modify it slightly to point at the COPYING file in the same web-directory. Add this line to nano.bb:
LIC_FILES_CHKSUM = "${SITE}/v${PV_MAJOR}.${PV_MINOR}/COPYING;md5=f27defe1e96c2e1ecd4e0c9be8967949"
The MD5 checksum in this case came from manually downloading and inspecting the matching file.
Done!
Now bitbake nano ought to work, and when it is complete you should see it built nano:
/tmp/bbhello $ find ./tmp/deploy/ -name "*nano*.rpm*"
./tmp/deploy/rpm/i586/nano-dbg-2.2.6-r0.i586.rpm
./tmp/deploy/rpm/i586/nano-dev-2.2.6-r0.i586.rpm
I have recently worked on that hands-on hello world project. As far as I am concerned, I think that the source code in the book contains some bugs. Below there is a list of suggested fixes:
Inheriting native class
In fact, when you build with bitbake that you got from poky, it builds only for the target, unless you mention in your recipe that you are building for the host machine (native). You can do the latter by adding this line at the end of your recipe:
inherit native
Adding license information
It is worth mentioning that the variable LICENSE is important to be set in any recipe, otherwise bitbake rises an error. In our case, we try to build the version 2.2.6 of the nano editor, its current license is GPLv3, hence it should be mentioned as follow:
LICENSE = "GPLv3"
Using os.system calls
As the book states, you cannot dereference metadata directly from a python function. Which means it is mandatory to access metadata through the d dictionary. Bellow, there is a suggestion for the do_unpack python function, you can use its concept to code the next tasks (do_configure, do_compile):
python do_unpack() {
workdir = d.getVar("WORKDIR", True)
dl_dir = d.getVar("DL_DIR", True)
p = d.getVar("P", True)
tarball_name = os.path.join(dl_dir, p+".tar.gz")
bb.plain("Unpacking tarball")
os.system("tar -x -C " + workdir + " -f " + tarball_name)
bb.plain("tarball unpacked successfully")
}
Launching the nano editor
After successfully building your nano editor package, you can find your nano executable in the following directory in case you are using Ubuntu (arch x86_64):
./tmp/work/x86_64-linux/nano/2.2.6-r0/src/nano
Should you have any comments or questions, Don't hesitate !