Implement BREAK for pseudo-terminals
This will greatly enhance the usefulness of QEMU virtual serial ports, because the Linux kernel interprets a break on the serial console as a SysRq, but there is currently no way to pass this signal over a pseudo-terminal.
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Hack Week 11
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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
Results
The project was a resounding success 
Lots of learning, and the initial target was met.
ESETv2 Emulator / interpreter by m.crivellari
Description
ESETv2 is an intriguing challenge developed by ESET, available on their website under the "Challenge" menu.
The challenge involves an "assembly-like" language and a Python compiler that generates .evm binary files.
This is an example using one of their samples (it prints N Fibonacci numbers):
.dataSize 0
.code
loadConst 0, r1 # first
loadConst 1, r2 # second
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hlt
This language also supports multi-threading. It includes instructions such as createThread to start a new thread, joinThread to wait until a thread completes, and lock/unlock to facilitate synchronization between threads.
Goals
- create a full interpreter able to run all the available samples provided by ESET.
- improve / optimize memory (eg. using bitfields where needed as well as avoid unnecessary memory allocations)
Resources
- Challenge URL: https://join.eset.com/en/challenges/core-software-engineer
- My github project: https://github.com/DispatchCode/eset_vm2 (not 100% complete)
Achivements
Project still not complete. Added lock / unlock instruction implementation but further debug is needed; there is a bug somewhere. Actually the code it works for almost all the examples in the samples folder. 1 of them is not yet runnable (due to a missing "write" opcode implementation), another will cause the bug to show up; still not investigated, anyhow.
FastFileCheck work by pstivanin
Description
FastFileCheck is a high-performance, multithreaded file integrity checker for Linux. Designed for speed and efficiency, it utilizes parallel processing and a lightweight database to quickly hash and verify large volumes of files, ensuring their integrity over time.
https://github.com/paolostivanin/FastFileCheck
Goals
- Release v1.0.0
Design overwiew:
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This separation of concerns is efficient because:
- Directory traversal is I/O bound and works well in a single thread
- Queue management is centralized, preventing race conditions
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Add a machine-readable output to dmidecode by jdelvare
Description
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Linux on Cavium CN23XX cards by tsbogend
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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
Results
The project was a resounding success Lots of learning, and the initial target was met.
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
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Hacking on sched_ext by flonnegren
Description
Sched_ext upstream has some interesting issues open for grabs:
Goals
Send patches to sched_ext upstream
Also set up perfetto to trace some of the example schedulers.
Resources
https://github.com/sched-ext/scx
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]