Sandbox Tool

A simple sandbox tool that works with bubblewrap, seccomp, and xdg-dbus-proxy to securely start your applications from a desktop entry.

Use case

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If you do not want to use flatpak for your applications but you are looking for a secure program to sandbox your applications without sacrificing convenience. This is it.

Examples

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Set up Element with Wayland for graphics, DRI for video acceleration and NET for sharing a network namespace

sandbox-create --app Element --entry element-desktop --path /opt/Element --dri

Set up Element with Wayland for graphics, Audio, DRI for video acceleration and a shared Downloads folder with the user in $HOME/Downloads. DBus permissions for notifications, screencasting and screenshotting.

sandbox-create --app Element \
    --path /opt/Element \
    --entry element-desktop \
    --dri \
    --downloads \
    --pulseaudio \
    --pipewire \
    --dbus \
    --dbus-app im.riot.Riot \
    --notifications \
    --screencast \

Seccomp

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To utilize seccomp-bpf for increased security, go to tools/minijail, and follow these instructions. Whitelisting is always better than blacklisting. So we shall first try to create a whitelist seccomp-bpf.

First we want to generate the LLVM IR for our platform specific instruction set.

make minijail0 constants.json

Then we want to strace the application we want to confine so we can pull all of the syscalls it uses, and turn it into a policy file.

strace -f -e raw=all -o strace.txt -- <program>
./tools/generate_seccomp_policy.py strace.txt > <program>.policy

Now we want to compile it into an actual BPF filter.

./tools/compile_seccomp_policy.py <program>.policy <program>.bpf

Now we want to output this in /home/$USER/.sandbox_manager/seccomp

mv <program>.policy /home/$USER/.sandbox_manager/seccomp
mv <program>.bpf /home/$USER/.sandbox_manager/seccomp

Now if we want to add the seccomp filter to our program:

sandbox-create \
    --app Element \
    --entry element-desktop \
    --path /opt/Element \
    --dri \
    --seccomp /home/$USER/.sandbox_manager/seccomp/element.bpf

if the program is not launching correctly, check /var/log/audit/audit.log for seccomp denials to fix them. By reading the syscall you can create a very strict policy.

type=SECCOMP msg=audit(1728657531.241:911): auid=1000 uid=1000 gid=1000 ses=4 subj=unconfined_u:unconfined_r:unconfined_t:s0 pid=40463 comm="element-desktop" exe="/opt/Element/element-desktop" sig=31 arch=c000003e **syscall=296** compat=0 ip=0x7f2461d1f050 code=0x0AUID="user" UID="user" GID="user" ARCH=x86_64 **SYSCALL=pwritev**