Podman

w0d0

Logistics

Announcements

• Welcome to Systems in C

  • You first semester in a compiled language - more on that soon.

• Action Items:

  • Access the course webpage
  • Join the Discord!
    • Working on this.
  • Spin up a GitHub acct if you don’t have one.

Homework

• The first homework, “Enigma”, is ready after this class.
  • Due Thursday, 03 Sep at midnight AOE
  • The infamous CS1 hw, now in a good language!
  • Mostly just get the toolchain working.

Enigma

ABCDEFGHIJKLMNOPQRSTUVWXYZ # in
    |
BDFHJLCPRTXVZNYEIWGAKMUSQO # fast
    >>>>>>
ABCDEFGHIJKLMNOPQRSTUVWXYZ 
         |
AJDKSIRUXBLHWTMCQGZNPYFVOE # mid
 <<<<<<<<<
ABCDEFGHIJKLMNOPQRSTUVWXYZ
 |
BDFHJLCPRTXVZNYEIWGAKMUSQO # slow

→

BDFHJLCPRTXVZNYEIWGAKMUSQO
 >>>
ABCDEFGHIJKLMNOPQRSTUVWXYZ 
   |
IXUHFEZDAOMTKQJWNSRLCYPBVG # reflect
   |
BDFHJLCPRTXVZNYEIWGAKMUSQO # slow
   >>>>>
ABCDEFGHIJKLMNOPQRSTUVWXYZ # out

## etc etc   

Today

• Introduce the course
  • The C Programming Language
  • Cryptography + Cryptocurrency
• Introduce the technologies
  • podman
  • vim
  • gcc
  • git

Pre-reqs

• These things:
  • podman
  • vim
  • gcc
  • git
• Are commands at the command line
• If you are afraid of the command line, drop this class.

It me

• Name
  • Calvin (Deutschbein)
• Call me
  • (Professor) Calvin
• Pronouns
  • pronouns or big frowns - me
  • they/them

The Great Work

• Thesis Title
  • Mining Secure Behavior of Hardware Designs
• Plain English
  • Just as there are bugs in code that makes software, modern hardware is also written in code and therefore may contain bugs. I find these bugs.

Learning Objectives

How To Do It

• After ~10 years of systems research I’ve convinced myself only two things that really matter:

  • Pointers, and
  • Recursion

• Recursion isn’t too bad…

>>> exp = lambda b, n : b if n == 1 else b*exp(b,n-1)
>>> exp(2,8)
256

Pointers

• Pointers are a beast, but without them nothing makes sense!

>>> x = 1
>>> def addx():
...     x += 1
...
>>> addx()
UnboundLocalError:
<blah blah blah error messages>

>>> x = [1]
>>> def addx():
...     x[0] += 1
...
>>> addx()
>>> x
[2]

Insight

• Definition:
  • Pointers: Variables that store memory addresses.
  • Recursion: Functions calling themselves to solve sub-problems.
• Importance:
  • Core to efficient algorithms and memory management in low-level programming.

Python and Pointers

• Why not .py (.js, .java, .cs, .cpp, etc)?
  • These languages abstract memory.
  • This abstraction makes computation unclear
  • This lack of clarity:
    • Adversely impacts education
    • Complicates low-level design
    • Leads to low performance
  • Good languages (except Java) but not for us

C and Pointers

• Why C?
  • Everyone hates C because it makes us think…
  • And thinking is hard.
  • But there exist problems (security) for which careful thought is necessary.
  • Learning C makes us better Blub programmers.
• I claim: You needn’t use C in real life.

Kennedy is my middle name

Not an endorsement; I voted for ******* **** ****** ********!

C is for Clear

• C does not obscure what a computer is doing.
• This lack of obscurity allows for greater precision.
• This greater precision can be used to achieve security goals.
• Advantages of C:
  • Fine-grained control over memory.
  • Essential for systems programming.

This class

• I am a systems security researcher and I discerned two core gaps in Willamette CS education:
  • Systems, and
  • Security
• Teaching systems alone can be boring or tedious.
• Teaching security alone can be defuse and ethereal.

Learning Objectives

• Differentiate confidentiality, integrity, and availability.
• Apply modular arithmetic to computational systems.
• Apply recursion and a pointers to programming problems.
• Articulate the impossibility of distributed consensus.
• Understand a low-level systems language.

Sketch

flowchart LR
  A( ) --> B(SHA)
  A --> C(RSA)
  B --> E(Block Chain)
  C --> F(Merkle Tree)
  B --> F
  E --> G(Nakamoto'08)
  F --> G
  G --> I((Capstone))

flowchart LR
  A( ) --> B(SHA)
  A --> C(RSA)
  B --> E(Block Chain)
  C --> F(Merkle Tree)
  B --> F
  E --> G(Nakamoto'08)
  F --> G
  G --> I((Capstone))

SHA

• SHA Basics:
  • Cryptographic hash function family.
  • Input data into fixed-size hash values.
• Use Cases:
  • Data integrity.
• Learning Objectives:
  • Reason about bits and bytes.

RSA

• RSA Basics:
  • Public-key cryptography algorithm.
  • Based on prime factorization being hard.
• Use Cases:
  • Data confidentiality.
• Learning Objectives:
  • Reason about numerical computing.

RSA + SHA = BTC

• Facilitating Blockchain:
  • SHA & RSA in play
    • RSA: Keep wallet keys confidential
    • SHA: Maintain wallet content integrity
• But we need some techniques to implement…
  • Pointers & Recursion

Blockchain

• Blockchain:
  • Blockchain structure resembles linked lists.
    • Linked lists use pointers
    • Pointers are used recursively
  • Pointers are validated with SHA
    • That is, they have integrity

Merkle Trees

• Merkle Trees:
  • Tree structure using SHA for data integrity.
  • Hashes stored as nodes; pointers link them.
  • Leaf nodes are RSA signatures!
• Merkle Trees are balanced
  • We get to see a way to implement complex data structures in a low level language in a way that solves a real problem.

Final

• Implement Full-Custom BTC
  • Under absolutely no circumstances use it
    • It’ll be insecure for reasons out-of-scope

Today

• ✓ Introduce the course
  • ✓ The C Programming Language
  • ✓ Cryptography + Cryptocurrency
• Introduce the technologies
  • podman
  • vim
  • gcc
  • git

podman

What is Podman?

• Definition:
  • Platform to develop, ship, and run applications in isolated containers.
• Benefits:
  • Portability, consistency across environments.
• Editorializing:
  • Probably all code should be written in a container now that they exist.

In practice:

• Windows only
  • Run wsl --install -d ubuntu command once
• Windows+Mac:
  • Use Podman Installer once
  • Launch Podman Desktop each time you code
  • Use podman commands
• Linux:
  • Have fun with your package manager.

Circa ~2013

• The problem:
  • We want to run code.
  • We want the code to create programs
  • We want the programs to work on more than one computer.
• The solution:
  • Realistically, the Java Virtual Machine
  • But then you have to write Java (this is pre-Scala, pre-Kotlin)

Circa ~2008

• The setting:
  • Cloud is taking off, mainly Amazon + Google
  • They already have to run everything in virtual machine.
  • They needed a lightweight solution.
• The solution:
  • Docker is written in the Google C-like, Go
  • It is a lightweight pretend computer.

Docker→Podman

• Docker is closed-source (bad)
• Docker is critical infastructre in most code bases
• The Redhat team (from CAROLINA) stepped into solve the problem
• They make Podman - completely compatible, completely open-source
• We use Podman in this class

Podman

• Podman solves the problem of writing code on one computer and running it another.
• Simply specify a Podman image
  • a description of a imaginary computer
• Podman will pretend to be that computer
• We can run code “inside” Podman
  • Code in the container can’t tell it’s running inside Podman

Podman & Python

• Windows, Mac, Linux:
  • Win tends to refer to Python3 as “python”
  • Mac tends to refer to Python2 as “python”
  • Linux, because its good, makes you specify:

user@DESKTOP-THMS2PJ:~$ python
Command 'python' not found, did you mean:
  command 'python3' from deb python3
  command 'python' from deb python-is-python3

Bugs

• This can lead to bugs pretty quickly
  • Say I write and test a .py file on Mac
  • I email it to my prof for help
  • SyntaxError on my prof’s Linux device:

user@DESKTOP-THMS2PJ:~$ python2 -c "print 'hello world'"
hello world
user@DESKTOP-THMS2PJ:~$ python3 -c "print 'hello world'"
  File "<string>", line 1
    print 'hello world'
    ^^^^^^^^^^^^^^^^^^^
SyntaxError: Missing parentheses in call to 'print'. Did you mean print(...)?

Versioning

• Python2/3 is just an extreme example
  • Most of code reuse has versioning problems
  • Many CS1 headaches are Win/Mac python’ing
  • But really: everything breaks all the time
• Solution: Just run in podman:

C:\Users\cd-desk>podman run -it python:alpine python
Python 3.13.1 (main, Dec  4 2024, 20:31:31) [GCC 13.2.1 20240309] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> print("hello world")
hello world
>>> exit()

Images

• Something we podman run -it is an image
  • It is a template that correspond to many possible pretend computers
  • I think of them like object oriented class
  • They define something that could be

Containers

• Each time we run said command, we have a different container
  • They have different file systems
  • Things we install don’t persist to future run instances.
  • I think of them like objects of a class
  • Like ‘1’ instead of ‘integer’
  • They actually existing, running code.

Today

• ✓ Introduce the course
  • ✓ The C Programming Language
  • ✓ Cryptography + Cryptocurrency
• Introduce the technologies
  • ✓ podman
  • vim
  • gcc
  • git

vim

IDEs

• At some point in time, code started being written in IDEs.
  • Integrated design environments.
  • To me, the first one was Eclipse (for Java)
• VS Code is the ascendent IDE, and is everywhere.
  • Google Cloud has browser based VS Code clone
• VS Code has some nice things - including good git and docker (less so podman) integration.

Integration

• VS Code has some nice things
  • Works with git/docker (less so podman).
  • You know what else can do that?
  • The command line
  • Which you don’t have to install
• IDEs are ~new, the was command line utilities
  • Vi(m)
  • Emacs
  • Nano

Why Vim?

• While IDEs are ascendent…
  • The are not installed on every system
  • They can be hard to use in cloud
  • They can start costing money at any time
  • They seem slower and to produce worse code
• Like Python, IDEs are easy!
  • This is good for new coders
  • It is a design decision thereafter

Vim

• Vim isn’t too bad
  • It can basically be used as a keyboard navigated text editor.
  • It has really good keyboard shortcuts and modes that we learn over time.
  • It seems to be the pound-for-pound productivity champion of all time.
• It is hard to find people who have learned vim who don’t prefer it.

Podvim

• We can install and run vim inside a container (which happens to run Debian & ∴ apt)
• Even directly from Python…

>>> import os
>>> os.system("apt update") # update the registry of packages
<blah blah blah>
>>> os.system("apt install vim -y") # -y saves us from having to say "yes" to any prompts
<blah blah blah>
>>> os.system("vim") # a vim window will open

• This is vim inside python inside podman
  • Don’t do this, it’s a proof-of-concept

Vim

• It looks like this:

~               VIM - Vi IMproved
~                  version 9.1
~            by Bram Moolenaar et al.
~   Vim is open source and freely distributable
~
~          Become a registered Vim user!
~  type  :help register<Enter>   for information
~
~  type  :q<Enter>              to exit
~  type  :help<Enter>  or  <F1> for on-line help
~  type  :help version9<Enter>  for version info

Usage

• I usually use vim as vim filename.py
  • When vim opens I type i (for “insert”)
  • Then I write code.
  • ESC → :x → ENTER to save+quit
• Learn vim incrementally by using it for this class - for code, for notes, for whatever.

Today

• ✓ Introduce the course
  • ✓ The C Programming Language
  • ✓ Cryptography + Cryptocurrency
• Introduce the technologies
  • ✓ podman
  • ✓ vim
  • gcc
  • git

gcc

GCC

• Developed for the C language to make an open source operating system in 1987.
• Mainly around today for the C language to make an open source operating system (Linux)
• (The C language was invented to write an operating system).
• python is written in GCC C

C:\Users\cd-desk>podman run -it python
Python 3.13.1 (main, Dec  4 2024, 20:40:27) [GCC 12.2.0] on linux

Great freeware

• Many legendary programs created using GCC:
  • HTTPD & NGINX, which serve a majority of webtraffic
  • Every major Linux and FreeBSD distribution
  • Major browsers like Firefox and Chromium
    • Firefox is on clang now but that’s new
  • GNU Bash and Coreutils, like cat, ls, rm
  • Bitcoin Core

Compilation

• Like python or podman or vim, GCC is a command - gcc
• gcc takes at least one argument: a filename, usually of a C file
• GCC takes this C file and makes an executable
  • a program, sort of
• Executables run as command with ./ prefix
  • This differs from python which runs a script without creating a corresponding program.

.py vs .c

flowchart LR
  A(Python) --> B[fname.py file]
  B --> C[python fname.py]
  C --> D{hello world}
  E(C) --> F[fname.c  file]
  F --> G[gcc fname.c -o ename]
  G --> H[./ename]
  H --> I{hello world}

flowchart LR
  A(Python) --> B[fname.py file]
  B --> C[python fname.py]
  C --> D{hello world}
  E(C) --> F[fname.c  file]
  F --> G[gcc fname.c -o ename]
  G --> H[./ename]
  H --> I{hello world}

• You only have to compile once to have the executable forever.
• Most programs are executables, not scripts.

Today

• ✓ Introduce the course
  • ✓ The C Programming Language
  • ✓ Cryptography + Cryptocurrency
• Introduce the technologies
  • ✓ podman
  • ✓ vim
  • ✓ gcc
  • git

git

Git

• Git was invented… to store the C language source code for an open source operating system (Linux)
• It is de facto the only way in the universe to store code other than “on my HDD/SSD”
• It is also a very good way to
  1. Keep track of podman images
  2. Keep track of podman containers
  3. Keep track of code used inside containers

As a command

• Git corresponds, like the others, to a command: git
  • It is common now to use other techniques, but the command remains extremely stable
• Quoth GitHub, the first and greatest of the collaboration tools:

If you want a lot of control and flexibility, you can use the command line.

As a technology

• So basically, you have things called repositories or “repos”

flowchart LR
  A(My ️‍🔥 code repo)

flowchart LR
  A(My ️‍🔥 code repo)

As a technology

• Then you realize you wrote an infinite loop so you update it

flowchart LR
  A(My ️‍🔥 code repo v0 ) --> B(My ️‍🔥 code repo v1)

flowchart LR
  A(My ️‍🔥 code repo v0 ) --> B(My ️‍🔥 code repo v1)

As a technology

• Then you come to class and realize your code is on your gaming rig in your apartment.

flowchart LR
  A(<s>My ️‍🔥 code repo v0</s>) --> B(<s>My ️‍🔥 code repo v1</s>)

flowchart LR
  A(<s>My ️‍🔥 code repo v0</s>) --> B(<s>My ️‍🔥 code repo v1</s>)

As a technology

• So you save your code on GitHub
  • GH = GitHub, GR = Gaming Rig

flowchart LR
  A(GR.️‍🔥 v0) --> B(GR.️‍🔥 v1)
  B --> C(GH.‍🔥 v0)

flowchart LR
  A(GR.️‍🔥 v0) --> B(GR.️‍🔥 v1)
  B --> C(GH.‍🔥 v0)

As a technology

• But you realize you didn’t sanitize your inputs so you update again.

flowchart LR
  A(GR.️‍🔥 v0) --> B(GR.️‍🔥 v1)
  B --> C(GR.️‍🔥 v2)
  B --> D(GH.‍🔥 v0)

flowchart LR
  A(GR.️‍🔥 v0) --> B(GR.️‍🔥 v1)
  B --> C(GR.️‍🔥 v2)
  B --> D(GH.‍🔥 v0)

As a technology

• Then you have class again and grab the GitHub version onto your LT = Laptop

flowchart LR
  A(GR.️‍🔥 v0) --> B(GR.️‍🔥 v1)
  B --> C(GR.️‍🔥 v2)
  B --> D(GH.‍🔥 v0)
  D --> E(LT.‍🔥 v0)

flowchart LR
  A(GR.️‍🔥 v0) --> B(GR.️‍🔥 v1)
  B --> C(GR.️‍🔥 v2)
  B --> D(GH.‍🔥 v0)
  D --> E(LT.‍🔥 v0)

As a technology

• You notice it has the bug so you fix it again on your laptop in almost the same way

flowchart LR
  A(GR.️‍🔥 v0) --> B(GR.️‍🔥 v1)
  B --> C(GR.️‍🔥 v2)
  B --> D(GH.‍🔥 v0)
  D --> E(LT.‍🔥 v0)
  E --> F(LT.‍🔥 v1)

flowchart LR
  A(GR.️‍🔥 v0) --> B(GR.️‍🔥 v1)
  B --> C(GR.️‍🔥 v2)
  B --> D(GH.‍🔥 v0)
  D --> E(LT.‍🔥 v0)
  E --> F(LT.‍🔥 v1)

As a technology

• And save that back to GitHub then head back home to play Nethack on your 12000USD Gaming PC

flowchart LR
  A(GR.️‍🔥 v0) --> B(GR.️‍🔥 v1)
  B --> C(GR.️‍🔥 v2)
  B --> D(GH.‍🔥 v0)
  D --> E(LT.‍🔥 v0)
  E --> F(LT.‍🔥 v1)
  F --> G(GH.‍🔥 v1)

flowchart LR
  A(GR.️‍🔥 v0) --> B(GR.️‍🔥 v1)
  B --> C(GR.️‍🔥 v2)
  B --> D(GH.‍🔥 v0)
  D --> E(LT.‍🔥 v0)
  E --> F(LT.‍🔥 v1)
  F --> G(GH.‍🔥 v1)

As a technology

• You realize you also added some ASCII art and try to send that to GitHub

flowchart LR
  A(GR.️‍🔥 v0) --> B(GR.️‍🔥 v1)
  B --> C(GR.️‍🔥 v2)
  B --> D(GH.‍🔥 v0)
  D --> E(LT.‍🔥 v0)
  E --> F(LT.‍🔥 v1)
  F --> G(GH.‍🔥 v1)
  G --> H(GH.‍🔥 v2)
  C --> H

flowchart LR
  A(GR.️‍🔥 v0) --> B(GR.️‍🔥 v1)
  B --> C(GR.️‍🔥 v2)
  B --> D(GH.‍🔥 v0)
  D --> E(LT.‍🔥 v0)
  E --> F(LT.‍🔥 v1)
  F --> G(GH.‍🔥 v1)
  G --> H(GH.‍🔥 v2)
  C --> H

As a technology

• Two arrows into one thing is a merge conflict and out-of-scope for now.

flowchart LR
  A(GR.️‍🔥 v0) --> B(GR.️‍🔥 v1)
  B --> C(GR.️‍🔥 v2)
  B --> D(GH.‍🔥 v0)
  D --> E(LT.‍🔥 v0)
  E --> F(LT.‍🔥 v1)
  F --> G(GH.‍🔥 v1)
  G --> H{💥}
  C --> H

flowchart LR
  A(GR.️‍🔥 v0) --> B(GR.️‍🔥 v1)
  B --> C(GR.️‍🔥 v2)
  B --> D(GH.‍🔥 v0)
  D --> E(LT.‍🔥 v0)
  E --> F(LT.‍🔥 v1)
  F --> G(GH.‍🔥 v1)
  G --> H{💥}
  C --> H

As a technology

• Basically versions of code can live in more than one place.
  • Ah, versions, our old friend…

flowchart LR
  A(GR.️‍🔥 v0) --> B(GR.️‍🔥 v1)
  B --> C(GR.️‍🔥 v2)
  B --> D(GH.‍🔥 v0)
  D --> E(LT.‍🔥 v0)
  E --> F(LT.‍🔥 v1)
  F --> G(GH.‍🔥 v1)
  G --> H{💥}
  C --> H

flowchart LR
  A(GR.️‍🔥 v0) --> B(GR.️‍🔥 v1)
  B --> C(GR.️‍🔥 v2)
  B --> D(GH.‍🔥 v0)
  D --> E(LT.‍🔥 v0)
  E --> F(LT.‍🔥 v1)
  F --> G(GH.‍🔥 v1)
  G --> H{💥}
  C --> H

In Brief

• Generally create repositories + tokens in browser
• Use command line and use ‘git clone ’ once.
• Authenticate via access token from browser
• Then use ‘git add’, ‘git commit’, ‘git push’ to save work
• Use ‘git pull’ to grab saved work
• Use a “.gitignore” file so only code (NOT executables) live on GitHub

Today

• ✓ Introduce the course
  • ✓ The C Programming Language
  • ✓ Cryptography + Cryptocurrency
• ✓ Introduce the technologies
  • ✓ podman
  • ✓ vim
  • ✓ gcc
  • ✓ git