Allow systemd_network_generator_t notify systemd manager

[zpytela]

Allow systemd-network-generator send system log messages

Logging support for the network generator was added by systemd commit
8b24bcdfa8 ("network-generator: Add missing log_setup()",
systemd/systemd@8b24bcdfa8).

Resolves: rhbz#2223571

[WOnder93]

The description doesn't seem to be correct... The denial in the BZ is for the journald socket and another one for /dev/kmsg (I assume this one only pops up as a fallback after the first one is denied). I believe the right interface for that is logging_send_syslog_msg().

[keszybz]

Yeah, the description doesn't seem to agree with the patch. systemd-network-generator does not use Type=notify-reload.

I think systemd/systemd@8b24bcd is the culprit. Simply speaking, logging was broken, and now we started logging. It probably tries to log to the journal, but gets a denial, and falls back to kmsg.

[zpytela]

Thank you both for the review, I apparently followed an incorrect lead written in oneof the reports and subsequently mismatched the problem with another one, still this was a draft PR where things can happen.