udica/README.md

<a href="https://copr.fedorainfracloud.org/coprs/lvrabec/udica/package/udica/"><img src="https://copr.fedorainfracloud.org/coprs/lvrabec/udica/package/udica/status_image/last_build.png" /></a>

# udica

This repository contains a tool for generating SELinux security profiles for containers. The whole concept is based on "block inheritence" feature inside CIL intermediate language supported by SELinux userspace. The tool creates a policy which combines rules inherited from specified CIL blocks(templates) and rules discovered by inspection of container JSON file, which contains mountpoints and ports definitions.

Final policy could be loaded imediately or moved to another system where could be loaded by semodule.

## State

This tool is still in early phase of development. Any feedback, ideas, pull requests are welcome. We're still adding new features, parameters and policy blocks which could be used.

## Proof of concept

Tool was created based on following PoC where process of creating policy is described:
https://github.com/fedora-selinux/container-selinux-customization

## Installing

Install udica tool with all dependencies

    $ sudo dnf install -y podman setools-console git container-selinux
    $ git clone https://github.com/containers/udica
    $ cd udica && sudo python3 ./setup.py install

Alternatively tou can run udica directly from git:

    $ python3 -m udica --help

Another way how to install udica is to use following repository:

    # cat << \EOF > /etc/yum.repos.d/lvrabec-udica-fedora-rawhide.repo
    [lvrabec-udica]
    name=Copr repo for udica owned by lvrabec
    baseurl=https://copr-be.cloud.fedoraproject.org/results/lvrabec/udica/fedora-rawhide-$basearch/
    type=rpm-md
    skip_if_unavailable=True
    gpgcheck=1
    gpgkey=https://copr-be.cloud.fedoraproject.org/results/lvrabec/udica/pubkey.gpg
    repo_gpgcheck=0
    enabled=1
    enabled_metadata=1
    EOF

    # dnf install udica -y

Make sure that SELinux is in Enforcing mode

    # setenforce 1
    # getenforce
    Enforcing

## Current situation

Let's start podman container with following parameters:

    # podman run -v /home:/home:ro -v /var/spool:/var/spool:rw -p 21:21 -it fedora bash

 - Container will bind mount /home with read only perms
 - Container will bind mount /var/spool with read/write perms
 - Container will publish container's port 21 to the host

Container runs with **container\_t** type and **c447,c628** categories.

Access mounted */home* is not working:

    [root@37a3635afb8f /]# cd /home/
    [root@37a3635afb8f home]# ls
    ls: cannot open directory '.': Permission denied

Because there is no allow rule for **container\_t** to access */home*

    # sesearch -A -s container_t -t home_root_t
    #

Access mounted */var/spool* is not working:

    [root@37a3635afb8f home]# cd /var/spool/
    [root@37a3635afb8f spool]# ls
    ls: cannot open directory '.': Permission denied
    [root@37a3635afb8f spool]# touch test
    touch: cannot touch 'test': Permission denied

Because there is no allow rule for **container\_t** to access */var/spool*

    # sesearch -A -s container_t -t var_spool_t -c dir -p read
    #

On the other hand, what is completely allowed is network access.

    # sesearch -A -s container_t -t port_type -c tcp_socket
    allow container_net_domain port_type:tcp_socket { name_bind name_connect recv_msg send_msg };
    allow sandbox_net_domain port_type:tcp_socket { name_bind name_connect recv_msg send_msg };

    # sesearch -A -s container_t -t port_type -c udp_socket
    allow container_net_domain port_type:udp_socket { name_bind recv_msg send_msg };
    allow sandbox_net_domain port_type:udp_socket { name_bind recv_msg send_msg };

It would be great to restrict this access and allow container bind just on tcp port *21* or with the same label.

## Creating SELinux policy for container

To create policy for container, it's necessary to have running container for which a policy will be generated. Container from previous chapter will be used.

Let's find container id using *podman ps* command:

    # podman ps
    CONTAINER ID   IMAGE                             COMMAND   CREATED          STATUS              PORTS   NAMES
    37a3635afb8f   docker.io/library/fedora:latest   bash      15 minutes ago   Up 15 minutes ago           heuristic_lewin

Container ID is **37a3635afb8f**.

To create policy for it **udica** tool could be used. Parameter '*-j*' is for *container json file* and '*-n*' for SELinux policy *name* for container.

    # podman inspect 37a3635afb8f > container.json
    # udica -j container.json -n my_container

    Policy my_container with container id 37a3635afb8f created!

    Please load these modules using:
    # semodule -i my_container.cil /usr/share/udica/templates/{base_container.cil,net_container.cil,home_container.cil}

    Restart the container with: "--security-opt label=type:my_container.process" parameter

Policy is generated. Let's follow instructions from output:

    # semodule -i my_container.cil /usr/share/udica/templates/{base_container.cil,net_container.cil,home_container.cil}

    # podman run --security-opt label=type:my_container.process -v /home:/home:ro -v /var/spool:/var/spool:rw -p 21:21 -it fedora bash

Container is now running with **my\_container.process** type:

    # ps -efZ | grep my_container.process
    unconfined_u:system_r:container_runtime_t:s0-s0:c0.c1023 root 2275 434  1 13:49 pts/1 00:00:00 podman run --security-opt label=type:my_container.process -v /home:/home:ro -v /var/spool:/var/spool:rw -p 21:21 -it fedora bash
    system_u:system_r:my_container.process:s0:c270,c963 root 2317 2305  0 13:49 pts/0 00:00:00 bash

Proof that SELinux now allowing access */home* and */var/spool* mount points:

    [root@814ec56079e5 /]# cd /home
    [root@814ec56079e5 home]# ls
    lvrabec

    [root@814ec56079e5 ~]# cd /var/spool/
    [root@814ec56079e5 spool]# touch test
    [root@814ec56079e5 spool]#

Proof that SELinux allows binding only to tcp/udp *21* port.

    [root@5bd8cb2ad911 /]# nc -lvp 21
    Ncat: Version 7.60 ( https://nmap.org/ncat )
    Ncat: Generating a temporary 1024-bit RSA key. Use --ssl-key and --ssl-cert to use a permanent one.
    Ncat: SHA-1 fingerprint: 6EEC 102E 6666 5F96 CC4F E5FA A1BE 4A5E 6C76 B6DC
    Ncat: Listening on :::21
    Ncat: Listening on 0.0.0.0:21

    [root@5bd8cb2ad911 /]# nc -lvp 80
    Ncat: Version 7.60 ( https://nmap.org/ncat )
    Ncat: Generating a temporary 1024-bit RSA key. Use --ssl-key and --ssl-cert to use a permanent one.
    Ncat: SHA-1 fingerprint: 6EEC 102E 6666 5F96 CC4F E5FA A1BE 4A5E 6C76 B6DC
    Ncat: bind to :::80: Permission denied. QUITTING.