This geneally makes sense as setting up a PAM session pretty much
defines what a login session is.
In context of #30547 this has the benefit that we can take benefit of
the SetLoginEnvironment= effect without having to set it explicitly,
thus retaining some compat of the uid0 client towards older systemd
service managers.
Until now, using any form of seccomp while being unprivileged (User=)
resulted in systemd enabling no_new_privs.
There's no need for doing this because:
* We trust the filters we apply
* If User= is set and a process wants to apply a new seccomp filter, it
will need to set no_new_privs itself
An example of application that might want seccomp + !no_new_privs is a
program that wants to run as an unprivileged user but uses file
capabilities to start a web server on a privileged port while
benefitting from a restrictive seccomp profile.
We now keep the privileges needed to do seccomp before calling
enforce_user() and drop them after the seccomp filters are applied.
If the syscall filter doesn't allow the needed syscalls to drop the
privileges, we keep the previous behavior by enabling no_new_privs.
As pointed out in https://github.com/systemd/systemd/issues/29814, we need to
use phrases are are meaningful on their own, because the man page formatter
creates a list at the bottom. With <ulink>see docs</ulink>, we end up with:
NOTES:
1. see docs
https://some.url/page
2. see docs
https://some.url/page2
which is not very useful :(
Also, the text inside the tag should not include punctuation.
Python helper:
from xml_helper import xml_parse
for p in glob.glob('../man/*.xml'):
t = xml_parse(p)
ulinks = t.iterfind('.//ulink')
for ulink in ulinks:
if ulink.text is None: continue
text = ' '.join(ulink.text.split())
print(f'{p}: {text}')
Before this commit, $USER, $HOME, $LOGNAME and $SHELL are only
set when User= is set for the unit. For system service, this
results in different behaviors depending on whether User=root is set.
$USER always makes sense on its own, so let's set it unconditionally.
Ideally $HOME should be set too, but it causes trouble when e.g. getty
passes '-p' to login(1), which then doesn't override $HOME. $LOGNAME and
$SHELL are more like "login environments", and are generally not
suitable for system services. Therefore, a new option SetLoginEnvironment=
is also added to control the latter three variables.
Fixes#23438
Replaces #8227
