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Commit Graph

5 Commits

Author SHA1 Message Date
Zbigniew Jędrzejewski-Szmek
9a797ddc41 meson: allow "soft-static" allocations for uids and gids in the initrd
The general idea with users and groups created through sysusers is that an
appropriate number is picked when the allocation is made. The number that is
selected will be different on each system based on the order of creation of
users, installed packages, etc. Since system users and groups are not shared
between installations, this generally is not an issue. But it becomes a problem
for initrd: some file systems are shared between the initrd and the host (/run
and /dev are probably the only ones that matter). If the allocations are
different in the host and the initrd, and files survive switch-root, they will
have wrong ownership.

This makes the gids build-time-configurable for all groups and users where
state may survive the switch from initrd to the host.

In particular, all "hardware access" groups are like this: files in /dev will
be owned by them.  Eventually the new udev would change ownership, but there
would be a momemnt where the files were owned by the wrong group. The
allocations are "soft-static" in the language of Fedora packaging guidelines:
the uid/gid will be used if possible, but we'll fall back to a different
one. TTY_GID is the exception, because the number is used directly.

Similarly, the possibility to configure "soft-static" uids is added for daemons
which may usefully run in the initramfs: systemd-network (lease information and
interface state is serialized to /run), systemd-resolve (stub files and
interface state), systemd-timesync (/run/systemd/timesync).

Journal files are owned by the group systemd-journal, and acls are granted
for wheel and adm.

systemd-oom and systemd-coredump are excluded from this patch: I assume that
oomd is not useful in the initrd, and coredump leaves no state (it only creates
a pipe in /run?).

The defaults are not changed: if nothing is configured, dynamic allocation will
be used. I looked at a Debian system, and the numbers are all different than
on Fedora.

For Fedora, see the list of uids and gids at https://pagure.io/setup/blob/master/f/uidgid.
In particular, systemd-network and systemd-resolve got soft-static numbers to
make it easy to transition from a non-host-specific initrd to a host system
already a few years back (https://bugzilla.redhat.com/show_bug.cgi?id=1102002).

I also requested static allocations for sgx, input, render in
https://pagure.io/packaging-committee/issue/1078,
https://pagure.io/setup/pull-request/27.
2021-06-17 09:48:28 +02:00
Zbigniew Jędrzejewski-Szmek
6b1aac3ccf meson: replace some m4 templates with jinja2
m4 was nice in '85, but the syntax feels a bit dated. Since we use python for
meson, let's use a popular python templating engine to replace some m4 usage.

A little nicety is that typos are caught:

FAILED: sysusers.d/systemd-remote.conf
/usr/bin/meson --internal exe --capture sysusers.d/systemd-remote.conf -- /home/zbyszek/src/systemd/tools/meson-render-jinja2.py config.h ../sysusers.d/systemd-remote.conf.j2
Traceback (most recent call last):
  File "/home/zbyszek/src/systemd/tools/meson-render-jinja2.py", line 28, in <module>
    print(render(sys.argv[2], defines))
  File "/home/zbyszek/src/systemd/tools/meson-render-jinja2.py", line 24, in render
    return template.render(defines)
  File "/usr/lib/python3.9/site-packages/jinja2/environment.py", line 1090, in render
    self.environment.handle_exception()
  File "/usr/lib/python3.9/site-packages/jinja2/environment.py", line 832, in handle_exception
    reraise(*rewrite_traceback_stack(source=source))
  File "/usr/lib/python3.9/site-packages/jinja2/_compat.py", line 28, in reraise
    raise value.with_traceback(tb)
  File "<template>", line 8, in top-level template code
jinja2.exceptions.UndefinedError: 'HAVE_MICROHTTP' is undefined

This checking mirrors what 349cc4a507 did for C defines.
2021-05-19 10:24:43 +09:00
Lennart Poettering
94655a1670 sysusers: split up default sysusers snippet
This ways, distributions have an easier way to replace the OS specific
generic groups/users while keeping systemd's own.
2014-06-29 22:27:07 +02:00
Jonathan Boulle
59282254ef sysusers.d - fix typo in user definition file 2014-06-20 13:41:46 +02:00
Lennart Poettering
f8b5d99408 sysuser: generate default snippet incorporating TTY_GID properly
When the user specifies --with-tty-gid= then we should honour that and
write it to the snippet, too.
2014-06-12 23:22:27 +02:00