Tracing system calls with eBPF by doreilly

Description

Many security tools need to record system calls like execve. Using the Linux audit system for this can have a detrimental performance impact in some cases.

Goals

The goal is to investigate eBPF as an alternative and do some benchmarking to see the impact and how it compares to using the audit subsystem.

Progress

BPF done - traceexec

Benchmark report

Resources

eBPF doc

libbpf

libMicro benchmark tool

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Tracing system calls with eBPF by doreilly

Description

Many security tools need to record system calls like execve. Using the Linux audit system for this can have a detrimental performance impact in some cases.

Goals

The goal is to investigate eBPF as an alternative and do some benchmarking to see the impact and how it compares to using the audit subsystem.

Progress

BPF done - traceexec

Benchmark report

Resources

eBPF doc

libbpf

libMicro benchmark tool

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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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Kill DMA and DMA32 memory zones by ptesarik

Description

Provide a better allocator for DMA-capable buffers, making the DMA and DMA32 zones obsolete.

Goals

Make a PoC kernel which can boot a x86 VM and a Raspberry Pi (because early RPi4 boards have some of the weirdest DMA constraints).

Resources

• LPC2024 talk:
• video:

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early stage kdump support by mbrugger

Project Description

When we experience a early boot crash, we are not able to analyze the kernel dump, as user-space wasn't able to load the crash system. The idea is to make the crash system compiled into the host kernel (think of initramfs) so that we can create a kernel dump really early in the boot process.

Goal for the Hackweeks

1. Investigate if this is possible and the implications it would have (done in HW21)
2. Hack up a PoC (done in HW22 and HW23)
3. Prepare RFC series (giving it's only one week, we are entering wishful thinking territory here).

update HW23

• I was able to include the crash kernel into the kernel Image.
• I'll need to find a way to load that from init/main.c:start_kernel() probably after kcsan_init()
• I workaround for a smoke test was to hack kexec_file_load() systemcall which has two problems:
  1. My initramfs in the porduction kernel does not have a new enough kexec version, that's not a blocker but where the week ended
  2. As the crash kernel is part of init.data it will be already stale once I can call kexec_file_load() from user-space.

The solution is probably to rewrite the POC so that the invocation can be done from init.text (that's my theory) but I'm not sure if I can reuse the kexec infrastructure in the kernel from there, which I rely on heavily.

update HW24

• Day1
  • rebased on v6.12 with no problems others then me breaking the config
  • setting up a new compilation and qemu/virtme env
  • getting desperate as nothing works that used to work
• Day 2
  • getting to call the invocation of loading the early kernel from __init after kcsan_init()

• Day 3

  • fix problem of memdup not being able to alloc so much memory... use 64K page sizes for now
  • code refactoring
  • I'm now able to load the crash kernel
  • When using virtme I can boot into the crash kernel, also it doesn't boot completely (major milestone!), crash in elfcorehdr_read_notes()

• Day 4

  • crash systems crashes (no pun intended) in copy_old_mempage() link; will need to understand elfcorehdr...
  • call path vmcore_init() -> parse_crash_elf_headers() -> elfcorehdr_read() -> read_from_oldmem() -> copy_oldmem_page() -> copy_to_iter()

• Day 5

  • hacking arch/arm64/kernel/crash_dump.c:copy_old_mempage() to see if crash system really starts. It does.
  • fun fact: retested with more reserved memory and with UEFI FW, host kernel crashes in init but directly starts the crash kernel, so it works (somehow) \o/

• TODOs

  • fix elfcorehdr so that we actually can make use of all this...
  • test where in the boot __init() chain we can/should call kexec_early_dump()

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FizzBuzz OS by mssola

Project Description

FizzBuzz OS (or just fbos) is an idea I've had in order to better grasp the fundamentals of the low level of a RISC-V machine. In practice, I'd like to build a small Operating System kernel that is able to launch three processes: one that simply prints "Fizz", another that prints "Buzz", and the third which prints "FizzBuzz". These processes are unaware of each other and it's up to the kernel to schedule them by using the timer interrupts as given on openSBI (fizz on % 3 seconds, buzz on % 5 seconds, and fizzbuzz on % 15 seconds).

This kernel provides just one system call, write, which allows any program to pass the string to be written into stdout.

This project is free software and you can find it here.

Goal for this Hackweek

• Better understand the RISC-V SBI interface.
• Better understand RISC-V in privileged mode.
• Have fun.

Resources

• SBI v2.0 ratified specification
• Blog post on SBI
• mssola/fbos

Results

The project was a resounding success Lots of learning, and the initial target was met.

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Create a DRM driver for VGA video cards by tdz

Yes, those VGA video cards. The goal of this project is to implement a DRM graphics driver for such devices. While actual hardware is hard to obtain or even run today, qemu emulates VGA output.

VGA has a number of limitations, which make this project interesting.

• There are only 640x480 pixels (or less) on the screen. That resolution is also a soft lower limit imposed by DRM. It's mostly a problem for desktop environments though.
• Desktop environments assume 16 million colors, but there are only 16 colors with VGA. VGA's 256 color palette is not available at 640x480. We can choose those 16 colors freely. The interesting part is how to choose them. We have to build a palette for the displayed frame and map each color to one of the palette's 16 entries. This is called dithering, and VGA's limitations are a good opportunity to learn about dithering algorithms.
• VGA has an interesting memory layout. Most graphics devices use linear framebuffers, which store the pixels byte by byte. VGA uses 4 bitplanes instead. Plane 0 holds all bits 0 of all pixels. Plane 1 holds all bits 1 of all pixels, and so on.

The driver will probably not be useful to many people. But, if finished, it can serve as test environment for low-level hardware. There's some interest in supporting old Amiga and Atari framebuffers in DRM. Those systems have similar limitations as VGA, but are harder to obtain and test with. With qemu, the VGA driver could fill this gap.

Apart from the Wikipedia entry, good resources on VGA are at osdev.net and FreeVGA

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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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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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VulnHeap by r1chard-lyu

Description

The VulnHeap project is dedicated to the in-depth analysis and exploitation of vulnerabilities within heap memory management. It focuses on understanding the intricate workflow of heap allocation, chunk structures, and bin management, which are essential to identifying and mitigating security risks.

Goals

• Familiarize with heap
  • Heap workflow
  • Chunk and bin structure
  • Vulnerabilities
• Vulnerability
  • Use after free (UAF)
  • Heap overflow
  • Double free
• Use Docker to create a vulnerable environment and apply techniques to exploit it

Resources

• https://heap-exploitation.dhavalkapil.com/divingintoglibc_heap
• https://raw.githubusercontent.com/cloudburst/libheap/master/heap.png
• https://github.com/shellphish/how2heap?tab=readme-ov-file

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CVE portal for SUSE Rancher products by gmacedo

Description

Currently it's a bit difficult for users to quickly see the list of CVEs affecting images in Rancher, RKE2, Harvester and Longhorn releases. Users need to individually look for each CVE in the SUSE CVE database page - https://www.suse.com/security/cve/ . This is not optimal, because those CVE pages are a bit hard to read and contain data for all SLE and BCI products too, making it difficult to easily see only the CVEs affecting the latest release of Rancher, for example. We understand that certain costumers are only looking for CVE data for Rancher and not SLE or BCI.

Goals

The objective is to create a simple to read and navigate page that contains only CVE data related to Rancher, RKE2, Harvester and Longhorn, where it's easy to search by a CVE ID, an image name or a release version. The page should also provide the raw data as an exportable CSV file.

It must be an MVP with the minimal amount of effort/time invested, but still providing great value to our users and saving the wasted time that the Rancher Security team needs to spend by manually sharing such data. It might not be long lived, as it can be replaced in 2-3 years with a better SUSE wide solution.

Resources

• The page must be simple and easy to read.
• The UI/UX must be as straightforward as possible with minimal visual noise.
• The content must be created automatically from the raw data that we already have internally.
• It must be updated automatically on a daily basis and on ad-hoc runs (when needed).
• The CVE status must be aligned with VEX.
• The raw data must be exportable as CSV file.
• Ideally it will be written in Go or pure Shell script with basic HTML and no external dependencies in CSS or JS.

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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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