initial poc

This commit is contained in:
atagen 2025-10-31 14:37:46 +11:00
commit aae8e63107
7 changed files with 513 additions and 0 deletions

1
.envrc Normal file
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use flake

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.gitignore vendored Normal file
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/target
.direnv

217
Cargo.lock generated Normal file
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Cargo.toml Normal file
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[package]
name = "yoke"
version = "0.1.0"
edition = "2024"
[dependencies]
anyhow = "1.0.100"
exec = "0.3.1"
gumdrop = "0.8.1"
landlock = "0.4.3"

43
flake.lock generated Normal file
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{
"nodes": {
"nixpkgs": {
"locked": {
"lastModified": 1761656231,
"narHash": "sha256-EiED5k6gXTWoAIS8yQqi5mAX6ojnzpHwAQTS3ykeYMg=",
"owner": "nixos",
"repo": "nixpkgs",
"rev": "e99366c665bdd53b7b500ccdc5226675cfc51f45",
"type": "github"
},
"original": {
"owner": "nixos",
"ref": "nixpkgs-unstable",
"repo": "nixpkgs",
"type": "github"
}
},
"root": {
"inputs": {
"nixpkgs": "nixpkgs",
"systems": "systems"
}
},
"systems": {
"locked": {
"lastModified": 1689347949,
"narHash": "sha256-12tWmuL2zgBgZkdoB6qXZsgJEH9LR3oUgpaQq2RbI80=",
"owner": "nix-systems",
"repo": "default-linux",
"rev": "31732fcf5e8fea42e59c2488ad31a0e651500f68",
"type": "github"
},
"original": {
"owner": "nix-systems",
"repo": "default-linux",
"type": "github"
}
}
},
"root": "root",
"version": 7
}

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flake.nix Normal file
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{
inputs.nixpkgs.url = "github:nixos/nixpkgs/nixpkgs-unstable";
inputs.systems.url = "github:nix-systems/default-linux";
outputs =
{
self,
nixpkgs,
systems,
}:
let
forAllSystems =
func: nixpkgs.lib.genAttrs (import systems) (system: func (import nixpkgs { inherit system; }));
in
{
devShells = forAllSystems (pkgs: {
default = pkgs.mkShell {
packages = with pkgs; [
cargo
rustc
rust-analyzer
rustfmt
clippy
];
};
});
};
}

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src/main.rs Normal file
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use std::{collections::HashMap, path::PathBuf, str::FromStr};
use anyhow::{Context, Result, anyhow};
use gumdrop::Options;
use landlock::{
ABI, Access, AccessFs, AccessNet, Compatible, NetPort, Ruleset, RulesetAttr,
RulesetCreatedAttr, Scope, path_beneath_rules,
};
#[derive(Clone, Copy, Debug, Hash, Eq, PartialEq)]
enum Direction {
In,
Out,
}
#[derive(Debug, Options)]
struct Chas {
#[options(no_multi, parse(try_from_str = "fs_parse"))]
fs: HashMap<Permissions, Vec<PathBuf>>,
#[options(no_multi, parse(try_from_str = "tcp_parse"))]
tcp: HashMap<Direction, Vec<u16>>,
#[options(no_multi, parse(try_from_str = "env_parse"))]
env: HashMap<String, String>,
clear_env: bool,
#[options(free)]
exec: Vec<String>,
}
#[derive(Clone, Copy, Debug, Hash, PartialEq, Eq)]
enum Permissions {
Read,
Write,
}
fn env_parse(s: &str) -> Result<HashMap<String, String>> {
let pairs = s.split(',');
let mut envs = HashMap::new();
for pair in pairs {
let (k, v) = pair.split_once('=').ok_or(anyhow!("invalid env var"))?;
envs.entry(k.to_string())
.and_modify(|iv: &mut String| {
*iv = v.to_string();
})
.or_insert(v.to_string());
}
Ok(envs)
}
// TODO handle ioctl perms
fn fs_parse(s: &str) -> Result<HashMap<Permissions, Vec<PathBuf>>> {
let pairs = s.split(',');
let mut rules = HashMap::new();
for pair in pairs {
let (s_perm, s_path) = pair
.split_once('=')
.ok_or(anyhow!("invalid filesystem pair"))?;
if s_perm.len() > 1 {
return Err(anyhow!("permission specifier too long"));
}
let perm = unsafe {
match s_perm.get_unchecked(0..1) {
"r" | "R" => Permissions::Read,
"w" | "W" => Permissions::Write,
_ => {
return Err(anyhow!("invalid permission specifier"));
}
}
};
for sub in s_path.split(':') {
let path = PathBuf::from_str(sub).context("invalid path specifier")?;
rules
.entry(perm)
.and_modify(|v: &mut Vec<PathBuf>| {
v.push(path.clone());
})
.or_insert(vec![path]);
}
}
Ok(rules)
}
fn tcp_parse(s: &str) -> Result<HashMap<Direction, Vec<u16>>> {
let pairs = s.split(',');
let mut rules = HashMap::new();
for pair in pairs {
let (s_io, s_port) = pair.split_once('=').context("invalid tcp pair")?;
let dir = match s_io {
"i" => Direction::In,
"o" => Direction::Out,
_ => {
return Err(anyhow!("invalid tcp specifier"));
}
};
for sub in s_port.split(':') {
let port = sub.parse().context("invalid port")?;
rules
.entry(dir)
.and_modify(|v: &mut Vec<u16>| {
v.push(port);
})
.or_insert(vec![port]);
}
}
Ok(rules)
}
fn main() -> Result<()> {
let opts = Chas::parse_args_or_exit(gumdrop::ParsingStyle::StopAtFirstFree);
println!("{opts:?}");
let mut preempt = Ruleset::default();
preempt = preempt.set_compatibility(landlock::CompatLevel::HardRequirement);
preempt = preempt.scope(Scope::Signal).context("scoping signals")?;
preempt = preempt
.scope(Scope::AbstractUnixSocket)
.context("scoping sockets")?;
// let is_fs = !opts.fs.is_empty();
let is_fs = true;
let is_tcp = !opts.tcp.is_empty();
preempt = if is_fs {
preempt
.handle_access(AccessFs::from_all(ABI::V6))
.context("handling fs access")?
} else {
preempt
};
preempt = if is_tcp {
preempt
.handle_access(AccessNet::BindTcp)
.context("handling tcp bind access")?
.handle_access(AccessNet::ConnectTcp)
.context("handling tcp conn access")?
} else {
preempt
};
let mut ruleset = preempt.create().context("creating ruleset")?;
for (perms, paths) in opts.fs {
let access = match perms {
Permissions::Read => AccessFs::from_read(ABI::V6),
Permissions::Write => AccessFs::from_write(ABI::V6),
};
ruleset = ruleset
.add_rules(path_beneath_rules(paths, access))
.context("adding fs rule")?;
}
for (dir, ports) in opts.tcp {
let access = match dir {
Direction::In => AccessNet::BindTcp,
Direction::Out => AccessNet::ConnectTcp,
};
for port in ports {
ruleset = ruleset
.add_rule(NetPort::new(port, access))
.context("adding tcp rule")?;
}
}
ruleset.restrict_self().context("enforcing ruleset")?;
if !opts.exec.is_empty() {
let mut cmd = exec::Command::new(&opts.exec[0]);
if opts.exec.len() > 1 {
cmd.args(&opts.exec[1..]);
}
if opts.clear_env {
for (k, _) in std::env::vars() {
unsafe {
std::env::remove_var(k);
}
}
}
if !opts.env.is_empty() {
for (k, v) in opts.env {
unsafe {
std::env::set_var(k, v);
}
}
}
let err = cmd.exec();
eprintln!("failed to run process: {}", err);
} else {
eprintln!(
"
yoke -- simple command sandboxer
use: yoke [rules] [command]
rules:
--fs [access]=/path:/another/path,[access]=/more/path
filesystem rules
--tcp [access]=1234:5678,[access]=91011
tcp port rules
--env [key]=[value]
include env vars for process
--clear-env
clear all inherited env vars
access specifiers (only one may be used per entry):
fs:
r - read (implies execute)
w - write (implies read+execute)
tcp:
i - in/bind
o - out/connect
example:
yoke --fs r=$(which ls):/etc ls /etc
yoke --tcp i=80:443,o=80:443 --fs r=/srv/web --clear-env --env SERVE_FROM=/srv/web myhttpserver
"
);
}
Ok(())
}