Contributing to Linux Kernel security by pperego

Description

A couple of weeks ago, I found this blog post by Gustavo Silva, a Linux Kernel contributor.

I always strived to start again into hacking the Linux Kernel, so I asked Coverity scan dashboard access and I want to contribute to Linux Kernel by fixing some minor issues.

I want also to create a Linux Kernel fuzzing lab using qemu and syzkaller

Goals

1. Fix at least 2 security bugs
2. Create the fuzzing lab and having it running

The story so far

• Day 1: setting up a virtual machine for kernel development using Tumbleweed. Reading a lot of documentation, taking confidence with Coverity dashboard and with procedures to submit a kernel patch
• Day 2: I read really a lot of documentation and I triaged some findings on Coverity SAST dashboard. I have to confirm that SAST tool are great false positives generator, even for low hanging fruits.
• Day 3: Working on trivial changes after I read this blog post: https://www.toblux.com/posts/2024/02/linux-kernel-patches.html. I have to take confidence with the patch preparation and submit process yet.
  • First trivial patch sent: using strtruefalse() macro instead of hard-coded strings in a staging driver for a lcd display
  • Fix for a dereference before null check issue discovered by Coverity (CID 1601566) https://scan7.scan.coverity.com/#/project-view/52110/11354?selectedIssue=1601566
• Day 4: Triaging more issues found by Coverity.
  • The patch for CID 1601566 was refused. The check against the NULL pointer was pointless so I prepared a version 2 of the patch removing the check.
  • Fixed another dereference before NULL check in iwlmvmparsewowlaninfo_notif() routine (CID 1601547). This one was already submitted by another kernel hacker :(
• Day 5: Wrapping up. I had to do some minor rework on patch for CID 1601566. I found a stalker bothering me in private emails and people I interacted with me, advised he is a well known bothering person. Markus Elfring for the record.

• Wrapping up: being back doing kernel hacking is amazing and I don't want to stop it. My battery pack is completely drained but changing the scope gave me a great twist and I really want to feel this energy not doing a single task for months.

  I failed in setting up a fuzzing lab but I was too optimistic for the patch submission process.

The patches

1

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Model checking the BPF verifier by shunghsiyu

Project Description

BPF verifier plays a crucial role in securing the system (though less so now that unprivileged BPF is disabled by default in both upstream and SLES), and bugs in the verifier has lead to privilege escalation vulnerabilities in the past (e.g. CVE-2021-3490).

One way to check whether the verifer has bugs to use model checking (a formal verification technique), in other words, build a abstract model of how the verifier operates, and then see if certain condition can occur (e.g. incorrect calculation during value tracking of registers) by giving both the model and condition to a solver.

For the solver I will be using the Z3 SMT solver to do the checking since it provide a Python binding that's relatively easy to use.

Goal for this Hackweek

Learn how to use the Z3 Python binding (i.e. Z3Py) to build a model of (part of) the BPF verifier, probably the part that's related to value tracking using tristate numbers (aka tnum), and then check that the algorithm work as intended.

Resources

• Formal Methods for the Informal Engineer: Tutorial #1 - The Z3 Theorem Prover and its accompanying notebook is a great introduction into Z3
  • Has a section specifically on model checking
• Software Verification and Analysis Using Z3 a great example of using Z3 for model checking
• Sound, Precise, and Fast Abstract Interpretation with Tristate Numbers - existing work that use formal verification to prove that the multiplication helper used for value tracking work as intended
• [PATCH v5 net-next 00/12] bpf: rewrite value tracking in verifier - initial patch set that adds tristate number to the verifier

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Migrate from Docker to Podman by tjyrinki_suse

Description

I'd like to continue my former work on containerization of several domains on a single server by changing from Docker containers to Podman containers. That will need an OS upgrade as well as Podman is not available in that old server version.

Goals

• Update OS.
• Migrate from Docker to Podman.
• Keep everything functional, including the existing "meanwhile done" additional Docker container that is actually being used already.
• Keep everything at least as secure as currently. One of the reasons of having the containers is to isolate risks related to services open to public Internet.
• Try to enable the Podman use in production.
• At minimum, learn about all of these topics.
• Optionally, improve Ansible side of things as well...

Resources

A search engine is one's friend. Migrating from Docker to Podman, and from docker-compose to podman-compose.

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Kanidm: A safe and modern IDM system by firstyear

Kanidm is an IDM system written in Rust for modern systems authentication. The github repo has a detailed "getting started" on the readme.

Kanidm Github

In addition Kanidm has spawn a number of adjacent projects in the Rust ecosystem such as LDAP, Kerberos, Webauthn, and cryptography libraries.

In this hack week, we'll be working on Quokca, a certificate authority that supports PKCS11/TPM storage of keys, issuance of PIV certificates, and ACME without the feature gatekeeping implemented by other CA's like smallstep.

For anyone who wants to participate in Kanidm, we have documentation and developer guides which can help.

I'm happy to help and share more, so please get in touch!

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Bot to identify reserved data leak in local files or when publishing on remote repository by mdati

Description

Scope here is to prevent reserved data or generally "unwanted", to be pushed and saved on a public repository, i.e. on Github, causing disclosure or leaking of reserved informations.

The above definition of reserved or "unwanted" may vary, depending on the context: sometime secret keys or password are stored in data or configuration files or hardcoded in source code and depending on the scope of the archive or the level of security, it can be either wanted, permitted or not at all.

As main target here, secrets will be registration keys or passwords, to be detected and managed locally or in a C.I. pipeline.

Goals

• Detection:

  • Local detection: detect secret words present in local files;
  • Remote detection: detect secrets in files, in pipelines, going to be transferred on a remote repository, i.e. via git push;

• Reporting:

  • report the result of detection on stderr and/or log files, noticed excluding the secret values.

• Acton:

  • Manage the detection, by either deleting or masking the impacted code or deleting/moving the file itself or simply notify it.

Resources

• Project repository, published on Github (link): m-dati/hkwk24;
• Reference folder: hkwk24/chksecret;
• First pull request (link): PR#1;
• Second PR, for improvements: PR#2;
• README.md and TESTS.md documentation files available in the repo root;
• Test subproject repository, for testing CI on push [TBD].

Notes

We use here some examples of secret words, that still can be improved.
The various patterns to match desired reserved words are written in a separated module, to be on demand updated or customized.

[Legend: TBD = to be done]

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Remote control for Adam Audio active monitor speakers by dmach

Description

I own a pair of Adam Audio A7V active studio monitor speakers. They have ethernet connectors that allow changing their settings remotely using the A Control software. From Windows :-( I couldn't find any open source alternative for Linux besides AES70.js library.

Goals

• Create a command-line tool for controlling the speakers.
• Python is the language of choice.
• Implement only a simple tool with the desired functionality rather than a full coverage of AES70 standard.

TODO

• ✅ discover the device
• ❌ get device manufacturer and model
• ✅ get serial number
• ✅ get description
• ✅ set description
• ✅ set mute
• ✅ set sleep
• ✅ set input (XRL (balanced), RCA (unbalanced))
• ✅ set room adaptation
  • bass (1, 0, -1, -2)
  • desk (0, -1, -2)
  • presence (1, 0, -1)
  • treble (1, 0, -1)
• ✅ set voicing (Pure, UNR, Ext)
• ❌ the Ext voicing enables the following extended functionality:
  • gain
  • equalizer bands
  • on/off
  • type
  • freq
  • q
  • gain
• ❌ udev rules to sleep/wakeup the speakers together with the sound card

Resources

• https://www.adam-audio.com/en/a-series/a7v/
• https://www.adam-audio.com/en/technology/a-control-remote-software/
• https://github.com/DeutscheSoft/AES70.js
• https://www.aes.org/publications/standards/search.cfm?docID=101 - paid
• https://www.aes.org/standards/webinars/AESStandardsWebinarSC0212L20220531.pdf
• https://ocaalliance.github.io/downloads/AES143%20Network%20track%20NA10%20-%20AES70%20Controller.pdf

Result

• The code is available on GitHub: https://github.com/dmach/pacontrol

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