Introduction¶
In this document, we will describe the SSG Test Suite.
Goal of this Test Suite is primarily to ensure Remediation scripts are usable, and to define scenarios in which these should work.
Priority is to provide very simple system of test scenarios, easily extendable so everyone contributing remediation can also provide cases where this remediation works.
The Test Suite executes the scans, remediations, and test scenarios on VMs or containers. To test content using VMs, Libvirt backend is used; to test content using containers, either Podman or Docker backend can be used.
Once a domain or container is prepared it can be used indefinitely.
The Test Suite can perform tests focused on a profile or a specific rule.
Typically, for a test run, a sequence of scan, remediation and scan is peformed.
Preparing a backend for testing¶
For the test suite to work, you need to have a backend image prepared for testing. You can use a powerful full-blown VM backend, or a lightweight container backend.
Libvirt backend¶
To use Libvirt backend, you need to have:
These packages installed in your host
openssh-clients
libvirt
libvirt-daemon
python2-libvirt/python3-libvirt
virt-install
(recommended, used byinstall_vm.py
script)libvirt-client
(optional, to manage VMs via console)virt-manager
(optional, to manage VMs via GUI)virt-viewer
(optional, to access graphical console of VMs)ansible
(required if remediating via Ansible)edk2-ovmf
(required if you want to install UEFI based machine)
A VM that fulfils the following requirements:
Package
qemu-guest-agent
installedPackage
openscap
version 1.2.15 or higher installedroot
can login via ssh (it is recommended to setup key-based authentication)root
can install packages (for RHEL7, it means subscription enabled).CPE_NAME
is present in/etc/os-release
. Currently, Ubuntu doesn’t ship it in the stock image. See this Ubuntu bug.
An easy way to install your VM is via install_vm.py
script. It will setup a VM according to the requirements, including configuration of a key for SSH login.
Common usage looks like:
$ python install_vm.py --domain test-suite-fedora --distro fedora
By default, the key at ~/.ssh/id_rsa.pub
is used. You can change default key used via --ssh-pubkey
option.
By default, the VM will be created on the user hypervisor, i.e. qemu:///session
.
For Test Suite this should be enough, in case you need the VM to reside under qemu:///system
, use the install script with --libvirt qemu:///system
.
When installing a RHEL VM, you will still need to subscribe it. You can also run installation and provide custom URLs pointing to your repositories:
$ python install_vm.py --domain test-suite-rhel8 --distro rhel8 --url http://baseos_repo_addr --extra-repo http://appstream_repo_addr
By default, the script creates a BIOS based machine. If you need to create UEFI
based machine, supply the --uefi normal
or --uefi secureboot
command line
argument. The script will create UEFI based machine and make necessary changes
to partitioning scheme. Note that the Libvirt backend cannot make snapshots of
UEFI based machines. Therefore, you can’t use them with SSG test suite.
TIP: Create a snapshot as soon as your VM is setup. This way, you can manually revert
in case the test suite breaks something and fails to revert. Do not use snapshot names starting with ssg_
.
You can create a snapshot using virsh
or virt-manager
.
Container backends¶
There are 2 container backends supported, Podman and Docker.
The container image needs to be prepared so it can accept ssh connections from root
, and run OpenSCAP scan.
The image needs to fulfil the following requirements:
Package
openssh-server
installedroot
’s.ssh/authorized_keys
is setup with correct permissionsthe container’s server host keys have to be in place
Packages
scp
andopenssh-clients
are installedscp
requires more than a ssh server on the server-side
Package
openscap-scanner
version 1.2.15 or higher installedYou may want to include other packages, as base images tend to be bare-bone and tests may require more packages to be present.
You can use test_suite-*
Dockerfiles in the content/Dockerfiles
directory to build the images.
We recommend to use RHEL-based containers, as the test suite is optimized for testing the RHEL content.
Podman¶
To use Podman backend, you need to have:
podman
package installed
Building podman base image¶
The Test Suite will log in to the container via SSH, so, if you don’t have an SSH key pair, lets setup a key without passphrase, so the procedure could happen without any additional interaction. You can skip this step if you already have an SSH key pair.
ssh-keygen -N ""
NOTE: With Podman you don’t have to be root in order to run tests and manage containers. But if you prefer to set up your test containers as superuser do keep in mind that root user typically doesn’t have an SSH key and you have to create it with sudo ssh-keygen -N “” command before moving forward. You can check if your root user has the key with a command like this: sudo test -f /root/.ssh/id_rsa && echo “Root user already has an id_rsa key” || echo “Root user has no id_rsa key”
Now when we all set with SSH keys let’s build the container. Go into the Dockerfiles
directory of the project, and execute the following:
public_key="$(cat ~/.ssh/id_rsa.pub)"
podman build --build-arg CLIENT_PUBLIC_KEY="$public_key" -t ssg_test_suite -f test_suite-rhel .
or just call the build_test_container.sh
script.
NOTE: If you are setting up the suite as superuser (i.e. sudo podman build …) use public_key=”$(sudo cat /root/.ssh/id_rsa.pub)” instead of the first command.
Docker¶
To use Docker backend, you need to have:
The docker Python module installed. You may have to use
pip
to install it on older distributions s.a. RHEL 7, runningpip install --user docker
asroot
will do the trick of installing it only for theroot
user.the Docker service running, and
Rights that allow you to start/stop containers and to create images. This is achieved by:
using
sudo
with everydocker
command, or;create a
docker
group, then add yourself to it and restartdocker
. Depending on your OS, you may need to logout for the group change to apply.
Building docker base image¶
The procedure is same as using Podman, you just swap the podman
call with docker
. But since Docker does not support rootless containers you will have to take superuser route of the guide.
Test scenarios¶
The test scenarios are used to test rules. They modify the system configuration so that OpenSCAP can return expected results.
The test scenarios for a rule are located in tests
subdirectory in rule
directory. The test scenarios are written in Bash. The format of the file name
is scenario_name.expected_scan_result.sh
, where scenario_name
is an
arbitrary name, and expected_scan_result
is the result of the evaluation of
the rule that oscap
should return when the rule is evaluated.
expected_scan_result
can be one of pass
, fail
or notapplicable
. It’s
very important to keep this naming form.
For example:
something.pass.sh
: Success scenario - script is expected to prepare machine in such way that the rule is expected to pass.something.fail.sh
: Fail scenario - script is expected to break machine so the rule fails. Test Suite than, if initial scan fails as expected, tries to remediate machine and expects evaluation to pass after the remediation.
Scenarios format¶
Scenarios are simple Bash scripts. A scenario starts with a header which provides metadata. The metadata are parsed by the test framework and affect the test runs. After the header, arbitrary Bash commands can follow.
The header consists of comments (starting by #
). Possible keys are:
packages
is a comma-separated list of packages to install.platform
is a comma-separated list of platforms where the test scenario can be run. This is similar toplatform
used in our remediations. Examples of values:multi_platform_rhel
,Red Hat Enterprise Linux 7
,multi_platform_all
. Ifplatform
is not specified in the header,multi_platform_all
is assumed.profiles
is a comma-separated list of profiles to which this scenario is restricted. Use this only if the scenario makes sense only in a specific profile. Typically, a rule doesn’t depend on a profile and behaves the same way regardless the profile it’s a part of. If the rule is parametrized by variables (XCCDF Values), use thevariables
key instead. This key is intended to be used in regression testing of bugs in profiles, it isn’t intended for casual use.remediation
is a string specifying one of the allowed remediation types (eg.bash
,ansible
,none
). Thenone
value means that the tested rule has no implemented remediation. Thenone
value can also be used in case that remediation breaks test environment (for example unmounting /tmp in a test scenario would break test suite because OpenSCAP generates reports into the /tmp directory).templates
has no effect at the moment.variables
is a comma-separated list of XCCDF values that sets a different default value for XCCDF variables in a form<variable name>=<value>
. Typically, you use only one ofprofile
orvariables
in scenario metadata - default values are effective only if the variable is not defined using a selector, which is exactly what profiles do.
Examples of test scenario:
Using platform
and variables
metadata:
#!/bin/bash
#
# platform = Red Hat Enterprise Linux 7,multi_platform_fedora
# variables = auth_enabled=yes,var_example_1=value_example
echo "KerberosAuthentication $auth_enabled" >> /etc/ssh/sshd_config
Example of adding new test scenarios¶
Let’s add test scenarios for rule accounts_password_minlen_login_defs
.
Create
tests
directory within rule directory (in this case/linux_os/guide/system/accounts/accounts-restrictions/password_expiration/accounts_password_minlen_login_defs/tests
further referenced as DIR).write a few fail scripts - for example removing the line, commenting it, wrong value, etc. into DIR
write a pass script into DIR - (some rules can have more than one pass scenario)
build the data stream by running
./build_product --datastream-only fedora
run
test_suite.py
with command:
./test_suite.py rule --libvirt qemu:///session ssg-test-suite-fedora accounts_password_minlen_login_defs
Example of test scenarios for this rule can be found at: #3697
Sharing code among test scenarios¶
Test scenarios can use files from /tests/shared
directory. This directory
and its contents is copied to the target VM or container together with the
test scenarios. The path to the directory is accessible in Bash using $SHARED
variable.
For example, script /tests/shared/setup_config_files.sh
can be sourced in
the following way:
. $SHARED/setup_config_files.sh
If you happen to have many similar test scenarios, consider extracting the common code to the shared directory.
Running tests¶
To test you profile or rule use test_suite.py
script. It can take your SCAP source data stream, and test it on the specified backend.
The Test Suite can test a whole profile or just a specific rule within a profile.
Argument summary¶
Mode of operation, specify one of the following commands;
rule
: Evaluate a rule, remediate, and evaluate again in context of test scenarios.profile
: Evaluate, remediate and evaluate again using selected profilecombined
: Evaluate, remediate, and evaluate again the rules from a profile in context of test scenarios.
Specify backend and image to use:
To use VM backend, use the following option on the command line:
Libvirt -
--libvirt <hypervisor> <domain>
hypervisor
: Typically, you will use theqemu:///session
, orqemu:///system
. It depends on where your VM resides.domain
:libvirt
domain, which is basically name of the virtual machine.
NOTE: It might happen, especially while using other distros than Fedora or RHEL (for example Arch), that you encounter the following error:
libvirt: QEMU Driver error : operation failed Failed to take snapshot: Error: Nested VMX virtualization does not support live migration yet
This error might be followed by Python tracebacks where the above message is repeated. First make sure that you are running the test suite on the physical machine and that you really DO NOT use nested virtualization by running VM in VM.
If you pass this requirement, it might happen that nested virtualization is enabled for your KVM kernel module. Libvirt will refuse to do live migration in this case. You can check this by running:
$ cat /sys/module/kvm_intel/parameters/nested
If you see “Y” then the nested virtualization is enabled for the KVM kernel module and it needs to be disabled. This can be done temporarily by running:
# modprobe -r kvm_intel
# modprobe kvm_intel nested=0
or permanently by putting
options kvm_intel nested=0
into a file ending with .conf and placed into the /etc/modprobe.d/ directory.
To use container backends, use the following options on the command line:
Podman -
--container <base image name>
Docker -
--docker <base image name>
Specify SCAP source data stream to use:
--datastream
: Path to the data stream that you want to use for scanning. It will be transferred to the scanned system via SSH. The option can be omitted if there is only one data stream in the build directory.
Specify as last argument the id of a profile or rule to be tested.
Note:Also, as containers may get any IP address, a conflict may happen in your local client’s known_hosts
file.
You might have a version of oscap-ssh
that doesn’t support ssh connection customization at the client-side, so it may be a good idea to disable known hosts checks for all hosts if you are testing on a VM or under a separate user.
You can do that by putting following lines in your $HOME/.ssh/config
file:
StrictHostKeyChecking no
UserKnownHostsFile /dev/null
All logs of Test Suite are stored in logs
directory. The specific diretory is shown at the beginning of each test run.
Rule-based testing¶
./test_suite.py rule RULE ...
In this mode, you supply one or more rule IDs or wildcards as positional arguments. Unlike the profile mode, each rule is evaluated and tested independently, one-by-one.
Rule-based testing enables to perform two kinds of tests:
Check tests: The system is set up into a compliant, or a non-compliant state.
Typically, the compliant state is different from the default or post-remediation state. The scanner is supposed to correctly identify the state of the system, so it is checked against false positives and false negatives.
Remediation tests: The system is set up into a non-compliant state, and remediation is performed.
If you would like to test the rule sshd_disable_kerb_auth
:
Using Libvirt:
./test_suite.py rule --libvirt qemu:///system ssg-test-suite-rhel7 --datastream ../build/ssg-rhel7-ds.xml sshd_disable_kerb_auth
Using Podman:
./test_suite.py rule --container ssg_test_suite --datastream ../build/ssg-rhel7-ds.xml sshd_disable_kerb_auth
or just call the test_rule_in_container.sh
script that passes the backend options for you
in addition to --remove-machine-only
and --add-platform
that remove some testing limitations of the container backend.
Using Docker:
./test_suite.py rule --docker ssg_test_suite --datastream ../build/ssg-rhel7-ds.xml sshd_disable_kerb_auth
Notice we didn’t use full rule name on the command line. The prefix xccdf_org.ssgproject.content_rule_
is added if not provided.
It is possible to use wildcards, eg accounts_passwords*
will run test scenarios for all
rules which ID starts with accounts_passwords
.
If the data stream file path is not supplied, auto detection is attempted by
looking into the /build
directory.
In the rule mode, the test suite follows the profiles
metadata key from the
scenario headers. It will run test scenario for each profile listed in this
profile
key. If there is no profiles
key in the test scenario header the
test suite will use the virtual (all)
profile. It is a profile that contains
all the rules.
Moreover, there is the --profile
option which can be used to override the
profile selection from profiles metadata so every test scenario will be executed
only against the profile selected by this command-line argument and variable
selections will be done according to this profile.
Debug mode¶
Use --debug
option, to investigate a test scenario which is not evaluating to expected result.
The Test Suite will pause its execution, and you will be able to SSH into the environment to inspect its state manually.
Profile-based testing¶
In this operation mode, you specify the profile
command and you supply the
profile ID as a positional argument. The test suite then runs scans over the
target domain and remediates it based on particular profile.
To test RHEL7 STIG Profile on a VM:
./test_suite.py profile --libvirt qemu:///session ssg-test-suite-rhel7 --datastream ../build/ssg-rhel7-ds.xml stig
To test Fedora Standard Profile on a Podman container:
./test_suite.py profile --container ssg_test_suite --datastream ../build/ssg-fedora-ds.xml standard
To test Fedora Standard Profile on a Docker container:
./test_suite.py profile --docker ssg_test_suite --datastream ../build/ssg-fedora-ds.xml standard
Note that profile-id
is matched by the suffix, so it works the same as in oscap
tool
(you can use oscap info --profiles
to see available profiles).
Unselecting problematic rules¶
Sometimes you would like to skip a rule in the profile because they are too slow to test, or you know a rule doesn’t have a remediation and you get less value by testing it.
Also, some rules need to be skipped in the profile mode because they might break
the test backend. For example, the rule sshd_disable_root_login
which disables
root login to the tested VM will prevent the test suite from execution because
the test suite uses root user in all underlying SSH commands.
For these situations, use ds_unselect_rules.sh
to unselect these rules in all profiles of the data stream.
It will copy your data stream to /tmp
and unselect rules listed in rules_list
./ds_unselect_rules.sh <datastream> <rules_list>
Where:
datastream
: is the data stream to unselect rules fromrules_list
: is a file with list of complete rule IDs, one per line
Example usage:
./ds_unselect_rules.sh ../build/ssg-fedora-ds.xml unselect_rules_list
Tip: file unselect_rules_list
contains a few typical rules you may want to skip
Combined testing mode¶
In this mode, you are testing the rules selected by a profile, using the contexts provided by each rule’s test scenarios. This mode provides an easy way of performing rule-based testing on all rules that are part of a profile.
In the combined mode, all rules selected by the given profile are tested. However, each rule is evaluated and tested separately.
The test scenarios are chosen to execute based on the presence and contents of
the profiles
metadata key in the test scenario header. If there is no
profiles
metadata key in a test scenario the test scenario will be executed
using the virtual (all)
profile. If there is a profiles
key in a test
scenario and the tested profile is listed under the profiles
key, the test
scenario will be executed using the tested profile. If there is the profiles
key but it doesn’t contain the tested profile the test scenario will be skipped
and won’t be executed. Most of the test scenarios do not have profiles
key,
therefore using the virtual (all)
profile is the most frequent behavior.
This way we can re-use test scenarios when testing any profile.
If you want to have a specific regression test only for a certain profile(s)
which relies on a specific value being selected by some variable in this profile
you need to use the profiles
key in the test scenarios metadata to limit test
scenario so it is executed only when testing profiles listed there.
# profiles = xccdf_org.ssgproject.content_profile_ID1,xccdf_org.ssgproject.content_profile_ID2,...
If a rule doesn’t have any test scenario, it will be skipped and a INFO
message printed at the end.
If you would like to test all profile’s rules against their test scenarios:
./test_suite.py combined --libvirt qemu:///system ssg-test-suite-rhel8 --datastream ../build/ssg-rhel8-ds.xml ospp
Analysis of results¶
The rule tests results are saved as results.json
into the corresponding log directory.
You can then analyze those results by running e.g.
python analyze_results.py $(find . -name results.json)
The tool will print some general statistics and it will give you more detailed information about scenarios that yielded different results. Sometimes, different results may have been caused by different test environments, whereas sometimes the security content is different, and those scans can be identified by respective scanning dates only.
Known issues¶
1 - Test suite fails to test rule with the message:
Rule <rule_id> has not been evaluated! Wrong profile selected in test scenario?
If you are using SCAP 1.3 content (which is built by default) and you are sure that you have selected the rule in the particular profile, it might be that the target scan environment has an OpenSCAP version contains a bug with SCAP 1.3 content. To solve this issue you can either update the OpenSCAP package in the target scan environment to the latest version or build SCAP 1.2 content. To build SCAP 1.2 content check the SSG Developer Guide