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[v1,0/2] systemd and RestrictNetworkInterfaces

Message ID 20240609080856.1020300-1-johannes.schneider@leica-geosystems.com
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Series systemd and RestrictNetworkInterfaces | expand

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SCHNEIDER Johannes June 9, 2024, 8:08 a.m. UTC 
Systemd has eBPF based resource-control features to limit file-system
and network-interface access [1][2]

For these to be usable the corresponding eBPFs that come with systemd
need to be compiled an deployed to the system - this could now be done
by setting the PACKAGECONFIG+="bpf-framework" in the target
build-setup.

Then clang-native (from meta-clang [3]) could be used to provide the
bpf-compiler, that then systemds build-setup uses to pre-compile these
eBPFs; the other build requirements are bpftool-native and libbpf
(both form meta-openembedded/meta-oe).

On the system the only run-time dependency is then libbpf to load these
pre-compiled filters. And "some kernel switches" [4]:
CONFIG_BPF
CONFIG_BPF_SYSCALL
CONFIG_CGROUP_BPF

To use/test these run for example:
$> systemd-run -t -p RestrictNetworkInterfaces=enp0s3 ping 8.8.8.8
which would result in 100% packet-loss, if the default route goes over
another interface.

Link: https://www.freedesktop.org/software/systemd/man/latest/systemd.resource-control.html#RestrictFileSystems=
Link: https://www.freedesktop.org/software/systemd/man/latest/systemd.resource-control.html#RestrictNetworkInterfaces=
Link: https://github.com/kraj/meta-clang
Link: https://kinvolk.io/blog/2021/04/extending-systemd-security-features-with-ebpf/

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