https://github.com/landlock-lsm/go-landlock

A Go library for the Linux Landlock sandboxing feature
https://github.com/landlock-lsm/go-landlock

landlock linux sandboxing security

Last synced: 3 months ago
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A Go library for the Linux Landlock sandboxing feature

• Host: GitHub
• URL: https://github.com/landlock-lsm/go-landlock
• Owner: landlock-lsm
• License: mit
• Created: 2021-06-28T07:39:39.000Z (over 3 years ago)
• Default Branch: main
• Last Pushed: 2024-07-15T19:35:15.000Z (4 months ago)
• Last Synced: 2024-07-15T23:49:55.961Z (4 months ago)
• Topics: landlock, linux, sandboxing, security
• Language: Go
• Homepage:
• Size: 140 KB
• Stars: 99
• Watchers: 8
• Forks: 7
• Open Issues: 4
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
# Go Landlock library

The Go-Landlock library restricts the current processes' ability to

use files, using Linux 5.13's Landlock feature. ([Package

documentation](https://pkg.go.dev/github.com/landlock-lsm/go-landlock/landlock))

For a more low-level interface, please see [the landlock/syscall

package](https://pkg.go.dev/github.com/landlock-lsm/go-landlock/landlock/syscall).

This package used to be located at `github.com/gnoack/golandlock`.

Please update your import paths to point to

`github.com/landlock-lsm/go-landlock/landlock`.

## Goals

Goals of Go-Landlock are:

* Make unprivileged sandboxing easy to use and effective.

* Keep Go-Landlock's implementation at an easily auditable size.

## Technical implementation

Some implementation notes that should simplify auditing.

### Applying Landlock to all Goroutines

The Landlock kernel API enabled Landlock for the current OS thread,

but the mapping between Goroutines and OS threads is not 1:1, and

there are few guarantees about it.

Because the mapping between OS threads and Goroutines is not

guaranteed anyway, the Go-Landlock API always enables the given

Landlock for the entire process.

This is done using the `psx` library, which is a helper library for

the `libcap` library for working with Linux capabilities. `psx`

exposes an API that does a system call with the given arguments on

*every OS thread* in a running Go program.

For pure Go programs, `psx` does the same as the

[`syscall.AllThreadsSyscall`

function](https://pkg.go.dev/syscall#AllThreadsSyscall) in the Go

runtime (and that case is straightforward to understand).

For programs linked with `cgo`, there can be more OS threads than just

the ones that were started by the Go runtime. To cover these, `psx`

intercepts calls to the pthread library to infer the list of all

threads, and then uses a trick with Unix signals to execute the given

system call on all of them. (This is unfortunately common practice for

system calls that only apply to the current thread -- glibc uses the

same approach for some system calls. To dig this up in the glibc

source, see `sysdeps/nptl/setxid.h` and its users.)

A deeper discussion of `psx` can be found at:

https://sites.google.com/site/fullycapable/who-ordered-libpsx