kntrl: A C repository from Kondukto

kntrl is an eBPF based runtime agent that monitors and prevents anomalous behaviour defined by you on your pipeline. kntrl achieves this by monitoring kernel calls, and denying access as soon as your defined behaviour is detected. Refer to this presentation to dive deeper into how we are achieving what kntrl does.

It can work as a single binary (kntrl) or with a docker runner (docker.io/kondukto/kntrl:0.1.2).

Installation

Linux

kntrl is available as downloadable binaries from the releases page. Download the pre-compiled binary from the releases page and copy to the desired location.

Container Images

We provide ready to use Docker container images. To pull the latest image:

docker pull kondukto/kntrl:latest

To pull a specific version:

docker pull kondukto/kntrl:0.1.2

Using kntrl

You can start using kntrl agent by simply running the following command:

- name: kntrl agent
  run: sudo ./kntrl run --mode=monitor --allowed-hosts=download.kondukto.io,${{ env.GITHUB_ACTIONS_URL }} --allowed-ips=10.0.2.3

OR with the docker:

- name: kntrl agent
  run: sudo docker run --privileged \
    --pid=host \
    --network=host \
    --cgroupns=host \
    --volume=/sys/kernel/debug:/sys/kernel/debug:ro \
    --volume /tmp:/tmp \
    --rm docker.io/kondukto/kntrl:0.1.2 run --mode=trace --allowed-hosts=kondukto.io,download.kondukto.io

This action will deploy kntrl into any GitHub Actions build.

Usage

The kntrl agent is self explanatory and it comes with a help command. Simply run --help flag after each command/subcommand.

 ./kntrl --help
Runtime security tool to control and monitor egress/ingress traffic in CI/CD runners

Usage:
  tracer [command]

Available Commands:
  completion  Generate the autocompletion script for the specified shell
  help        Help about any command
  run         Starts the TCP/UDP tracer

Flags:
  -h, --help      help for tracer
  -v, --verbose   more logs

Use "tracer [command] --help" for more information about a command.

The agent supports the following parameters:

Name	Default	Description
`mode`	monitor	kntrl for detected behaviours (monitor or prevent/trace)
`allowed-hosts`		allowed host list. (example.com, .github.com)
`allowed-ips`		allowed IP list. (192.168.0.100, 1.1.1.1)
`allow-local-ranges`	true	allow access to local IP ranges
`allow-github-meta`	false	allow access to GitHub meta IP ranges (https://api.github.com/meta)
`output-file`	`/tmp/kntrl.out`	report file

Running kntrl on monitoring mode

- name: kntrl agent
  run: sudo docker run --privileged \
  --pid=host \
  --network=host \
  --cgroupns=host \
  --volume=/sys/kernel/debug:/sys/kernel/debug:ro \
  --volume /tmp:/tmp \
  --rm docker.io/kondukto/kntrl:0.1.2 \
  --mode=monitor

Running kntrl on prevent mode

- name: kntrl agent
  run: sudo docker run --privileged \
  --pid=host \
  --network=host \
  --cgroupns=host \
  --volume=/sys/kernel/debug:/sys/kernel/debug:ro \
  --volume /tmp:/tmp \
  --rm docker.io/kondukto/kntrl:0.1.2 \
  --mode=trace --allowed-hosts=download.kondukto.io, .github.com

Open Policy Agent (OPA) Rules

kntrl supports an OPA-based policy engine to determine whether the event should be blocked or not. All the policy rules are stored under the bundle/kntrl/ directory.

An example rego rule:

package kntrl.network["is_local_ip_addr"]

import rego.v1

policy if {
        ipaddr := input.daddr
        local_ranges := ["192.168.0.0/16", "172.16.0.0/12", "10.0.0.0/8", "0.0.0.0/32"]
        net.cidr_contains(local_ranges[_], ipaddr)
        data.allow_local_ip_ranges == true
}

Reporting

Each event will be logged in the output file. The default report file location is /tmp/kntrl.out.

Here is an example report:

{
  "pid": 2806,
  "task_name": "curl",
  "proto": "tcp",
  "daddr": "140.82.114.22",
  "dport": 443,
  "domains": [
    "lb-140-82-114-22-iad.github.com."
  ],
  "policy": "pass"
}
{
  "pid": 2806,
  "task_name": "curl",
  "proto": "tcp",
  "daddr": "142.251.167.95",
  "dport": 443,
  "domains": [
    "ww-in-f95.1e100.net."
  ],
  "policy": "block"
}
{
  "pid": 2806,
  "task_name": "curl",
  "proto": "udp",
  "daddr": "127.0.0.1",
  "dport": 53,
  "domains": [
    "localhost"
  ],
  "policy": "pass"
}

Pid  | Comm    | Proto | Domain                          | Destination Addr   | Policy
------------------------------------------------------------------------------------
2806 | curl    | tcp   | lb-140-82-114-22-iad.github.com | 140.82.114.22:443  | pass
------------------------------------------------------------------------------------
2806 | curl    | tcp   | ww-in-f95.1e100.net             | 142.251.167.95:443 | block
------------------------------------------------------------------------------------
2806 | curl    | udp   | localhost                       | 127.0.0.1:53       | pass
------------------------------------------------------------------------------------

Contribution

Contributions to kntrl are welcome. Feel free to join our slack channel https://kntrl.slack.com

License

Except for the eBPF code, all components are distributed under the Apache License (version 2.0).

More about Kondukto

kntrl is an open source project maintained by Kondukto.

kondukto-io/kntrl