The ifdef pattern is the same for all syscalls, so most of the time, if one is
not defined, all others will too. So let's reduce the noise a bit and emit one
warning in case the support for the architecture is fully missing. (Current
template was copied over from before when we added numbers for each syscall by
hand and stopped making sense when we started generating the header from a
table that is expected to have all syscall numbers.)
This allows to limit units to machines that run on a certain firmware
type. For device tree defined machines checking against the machine's
compatible is also possible.
We were duplicating setting flags for the message and a combination of
NLM_F_APPEND and NLM_F_CREATE which does not make sense. We should have
been using NLM_F_REPLACE and NLM_F_CREATE since the kernel can
dynamically create neighbors prior to us adding an entry. Otherwise, we
can end up with cases where the message will time out after ~25s even
though the neighbor still gets added. This delays the rest of the setup
of the interface even though the error is ultimately ignored.
Verify that service exited correctly if valid ports are passed to
SocketBind{Allow|Deny}=
Use `ncat` program starting a listening service binding to a specified
port, e.g.
"timeout --preserve-status -sSIGTERM 1s /bin/nc -l -p ${port} -vv"
Add supported and install unit interface for socket-bind feature.
supported verifies that
- unified cgroup hierarchy (cgroup v2) is used
- BPF_FRAMEWORK (libbpf + clang + llvm + bpftool) was available in
compile time
- kernel supports BPF_PROG_TYPE_CGROUP_SOCK_ADDR
- bpf programs can be loaded into kernel
- bpf link can be used
install:
- load bpf_object from bpf skeleton
- resize rules map to fit socket_bind_allow and socket_bind deny rules
from cgroup context
- populate cgroup-bpf maps with rules
- get bpf programs from bpf skeleton
- attach programs to unit cgroup using bpf link
- save bpf link in the unit
Introduce BPF program compiled from BPF source code in
restricted C - socket-bind.
It addresses feature request [0].
The goal is to allow systemd services to bind(2) only to a predefined set
of ports. This prevents assigning socket address with unallowed port
to a socket and creating servers listening on that port.
This compliments firewalling feature presenting in systemd:
whereas cgroup/{egress|ingress} hooks act on packets, this doesn't
protect from untrusted service or payload hijacking an important port.
While ports in 0-1023 range are restricted to root only, 1024-65535
range is not protected by any mean.
Performance is another aspect of socket_bind feature since per-packet
cost can be eliminated for some port-based filtering policies.
The feature is implemented with cgroup/bind{4|6} hooks [1].
In contrast to the present systemd approach using raw bpf instructions,
this program is compiled from sources. Stretch goal is to
make bpf ecosystem in systemd more friendly for developer and to clear
path for more BPF programs.
[0] https://github.com/systemd/systemd/pull/13496#issuecomment-570573085
[1] https://www.spinics.net/lists/netdev/msg489054.html
We should test both serialization and deserialization works properly.
But the serialization/deserialization code is deeply entwined with the
manager state, and I think quite a bit of refactoring will be required before
this is possible. But let's at least add this simple test for now.
After 4b30f2e135, reading stable_secret
sysctl property fails with -ENOMEM, instead of -EIO.
This is due to read_full_virtual_file() uses read() as the backend while
read_one_line_file() uses fgetc(). And each functions return different
error on fails.
Anyway, the failure is harmless here. So, the log message and comment is
updated.
Closes one of the issues in #19410.
Lennart Poettering
caoxia2008cxx
Yu Watanabe
Zbigniew Jędrzejewski-Szmek
Uwe Kleine-König
William A. Kennington III
Franck Bui
Frantisek Sumsal
Julia Kartseva
Luca Boccassi