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
Looking for hackers with the skills:
This project is part of:
Hack Week 21 Hack Week 23 Hack Week 24
Activity
Comments
-
almost 3 years ago by shunghsiyu | Reply
I've uploaded the jupyter notebook on GitHub that contains a minimal model of tnum along with tnum_add(), as well as the prove that it works.
-
almost 3 years ago by shunghsiyu | Reply
The slides used for lightning talk can be found here
While I'd like to achieve much more, I think what I've done during hack week is suffice to be called a complete project, so I'm marking this as complete
-
over 1 year ago by shunghsiyu | Reply
I'm restarting this project to model check the range tracking (minimal and maximal value possible in s32/u32/u64/s64 range) done in BPF verifier.
In addition to that I hope to unify signed and unsigned range tracking based on previously posted idea and the "Interval Analysis and Machine Arithmetic: Why Signedness Ignorance Is Bliss" paper for simpler range tracking code.
Similar Projects
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
Resources
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
Resources
Modularization and Modernization of cifs.ko for Enhanced SMB Protocol Support by hcarvalho
Creator:
Enzo Matsumiya ematsumiya@suse.de @ SUSE Samba team
Members:
Henrique Carvalho henrique.carvalho@suse.com @ SUSE Samba team
Description
Split cifs.ko in 2 separate modules; one for SMB 1.0 and 2.0.x, and another for SMB 2.1, 3.0, and 3.1.1.
Goals
Primary
Start phasing out/deprecation of older SMB versions
Secondary
- Clean up of the code (with focus on the newer versions)
- Update cifs-utils
- Update documentation
- Improve backport workflow (see below)
Technical details
Ideas for the implementation.
- fs/smb/client/{old,new}.c to generate the respective modules
- Maybe don't create separate folders? (re-evaluate as things progresses!)
- Remove server->{ops,vals} if possible
- Clean up fs_context.* -- merge duplicate options into one, handle them in userspace utils
- Reduce code in smb2pdu.c -- tons of functions with very similar init/setup -> send/recv -> handle/free flow
- Restructure multichannel
- Treat initial connection as "channel 0" regardless of multichannel enabled/negotiated status, proceed with extra channels accordingly
- Extra channel just point to "channel 0" as the primary server, no need to allocate an extra TCPServerInfo for each one
- Authentication mechanisms
- Modernize algorithms (references: himmelblau, IAKERB/Local KDC, SCRAM, oauth2 (Azure), etc.
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
- Investigate if this is possible and the implications it would have (done in HW21)
- Hack up a PoC (done in HW22 and HW23)
- 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 afterkcsan_init()
- I workaround for a smoke test was to hack
kexec_file_load()
systemcall which has two problems:- My initramfs in the porduction kernel does not have a new enough kexec version, that's not a blocker but where the week ended
- 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
afterkcsan_init()
- getting to call the invocation of loading the early kernel from
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()
- crash systems crashes (no pun intended) in
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/
- hacking
TODOs
- fix elfcorehdr so that we actually can make use of all this...
- test where in the boot
__init()
chain we can/should callkexec_early_dump()
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
Create DRM drivers for VESA and EFI framebuffers by tdz
Description
We already have simpledrm for firmware framebuffers. But the driver is originally for ARM boards, not PCs. It is already overloaded with code to support both use cases. At the same time it is missing possible features for VESA and EFI, such as palette modes or EDID support. We should have DRM drivers for VESA and EFI interfaces. The infrastructure exists already and initial drivers can be forked from simpledrm.
Goals
- Initially, a bare driver for VESA or EFI should be created. It can take functionality from simpledrm.
- Then we can begin to add additional features. The boot loader can provide EDID data. With VGA hardware, VESA can support paletted modes or color management. Example code exists in vesafb.
Officially Become a Kernel Hacker! by m.crivellari
Description
My studies as well my spare time are dedicated to the Linux Kernel. Currently I'm focusing on interrupts on x86_64, but my interests are not restricted to one specific topic, for now.
I also "played" a little bit with kernel modules (ie lantern, a toy packet analyzer) and I've added a new syscall in order read from a task A, the memory of a task B.
Maybe this will be a good chance to...
Goals
- create my first kernel patch
Resources
- https://www.kernel.org/doc/html/latest/process/submitting-patches.html
- https://git-send-email.io/ (mentioned also in the kernel doc)
- https://javiercarrascocruz.github.io/kernel-contributor-1
Achivements
- found while working on a bug, this is the 1st patch: cifs: avoid deadlocks while updating iface [✅ has been merged]
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.
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.
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]
OIDC Loginproxy by toe
Description
Reverse proxies can be a useful option to separate authentication logic from application logic. SUSE and openSUSE use "loginproxies" as an authentication layer in front of several services.
Currently, loginproxies exist which support LDAP authentication or SAML authentication.
Goals
The goal of this Hack Week project is, to create another loginproxy which supports OpenID Connect authentication which can then act as a drop-in replacement for the existing LDAP or SAML loginproxies.
Testing is intended to focus on the integration with OIDC IDPs from Okta, KanIDM and Authentik.
Resources
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.
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!