sys-apps/systemd: add hostnamed-fallback mode

this will allow networkd/hostnamed to properly set hostname
on systems without polkit.

while it's possible to set hostname/fqdn manually already, with fallback workaround
it will be possible to get hostnames from DHCP via networkd too without
using polkit->spidermonkey->rust->llvm chain of deps.

ideas and configs taken from yocto/oe
https://git.yoctoproject.org/cgit/cgit.cgi/poky/commit/?id=3dc37c12c17d5bb6d4701a425a4f79f6e31784ee

https://github.com/systemd/systemd/issues/13501
Closes: https://github.com/gentoo/gentoo/pull/22792
Signed-off-by: Georgy Yakovlev <gyakovlev@gentoo.org>

4 files changed, 34 insertions, 1 deletions

diff --git a/sys-apps/systemd/files/00-hostnamed-network-user.conf b/sys-apps/systemd/files/00-hostnamed-network-user.conf
new file mode 100644
index 000000000000..6b224ba9b937
--- /dev/null
+++ b/sys-apps/systemd/files/00-hostnamed-network-user.conf
@@ -0,0 +1,6 @@
+[Service]
+# By running with these options instead of root, networkd is allowed to request
+# a hostname change via DBUS when policykit is not present
+User=systemd-network
+Group=systemd-hostname
+AmbientCapabilities=CAP_SYS_ADMIN
diff --git a/sys-apps/systemd/files/org.freedesktop.hostname1_no_polkit.conf b/sys-apps/systemd/files/org.freedesktop.hostname1_no_polkit.conf
new file mode 100644
index 000000000000..f4d0271cdb6a
--- /dev/null
+++ b/sys-apps/systemd/files/org.freedesktop.hostname1_no_polkit.conf
@@ -0,0 +1,11 @@
+<?xml version="1.0"?> <!--*-nxml-*-->
+<!DOCTYPE busconfig PUBLIC "-//freedesktop//DTD D-BUS Bus Configuration 1.0//EN"
+        "http://www.freedesktop.org/standards/dbus/1.0/busconfig.dtd">
+
+<busconfig>
+        <policy group="systemd-hostname">
+                <allow own="org.freedesktop.hostname1"/>
+                <allow send_destination="org.freedesktop.hostname1"/>
+                <allow receive_sender="org.freedesktop.hostname1"/>
+        </policy>
+</busconfig>
diff --git a/sys-apps/systemd/metadata.xml b/sys-apps/systemd/metadata.xml
index b35d6bfbd411..cd0754d004d6 100644
--- a/sys-apps/systemd/metadata.xml
+++ b/sys-apps/systemd/metadata.xml
@@ -20,6 +20,7 @@
 		<flag name="fido2">Enable FIDO2 support</flag>
 		<flag name="gcrypt">Enable sealing of journal files using gcrypt</flag>
 		<flag name="homed">Enable portable home directories</flag>
+		<flag name="hostnamed-fallback">Enable setting hostname with networkd/hostnamed without polkit (requires running <pkg>sys-apps/dbus-broker</pkg>)</flag>
 		<flag name="http">Enable embedded HTTP server in journald</flag>
 		<flag name="hwdb">Enable support for the hardware database</flag>
 		<flag name="importd">Enable import daemon</flag>
diff --git a/sys-apps/systemd/systemd-9999.ebuild b/sys-apps/systemd/systemd-9999.ebuild
index 8348517478b6..485b6498181e 100644
--- a/sys-apps/systemd/systemd-9999.ebuild
+++ b/sys-apps/systemd/systemd-9999.ebuild
@@ -30,11 +30,12 @@ HOMEPAGE="https://www.freedesktop.org/wiki/Software/systemd"
 
 LICENSE="GPL-2 LGPL-2.1 MIT public-domain"
 SLOT="0/2"
-IUSE="acl apparmor audit build cgroup-hybrid cryptsetup curl dns-over-tls elfutils fido2 +gcrypt gnuefi homed http +hwdb idn importd +kmod +lz4 lzma nat pam pcre pkcs11 policykit pwquality qrcode repart +resolvconf +seccomp selinux split-usr +sysv-utils test tpm vanilla xkb +zstd"
+IUSE="acl apparmor audit build cgroup-hybrid cryptsetup curl dns-over-tls elfutils fido2 +gcrypt gnuefi homed hostnamed-fallback http +hwdb idn importd +kmod +lz4 lzma nat pam pcre pkcs11 policykit pwquality qrcode repart +resolvconf +seccomp selinux split-usr +sysv-utils test tpm vanilla xkb +zstd"
 
 REQUIRED_USE="
 	homed? ( cryptsetup pam )
 	importd? ( curl gcrypt lzma )
+	policykit? ( !hostnamed-fallback )
 	pwquality? ( homed )
 "
 RESTRICT="!test? ( test )"
@@ -117,6 +118,10 @@ RDEPEND="${COMMON_DEPEND}
 	>=acct-user/systemd-resolve-0-r1
 	>=acct-user/systemd-timesync-0-r1
 	>=sys-apps/baselayout-2.2
+	hostnamed-fallback? (
+		acct-group/systemd-hostname
+		sys-apps/dbus-broker
+	)
 	selinux? ( sec-policy/selinux-base-policy[systemd] )
 	sysv-utils? (
 		!sys-apps/openrc[sysv-utils(-)]
@@ -400,6 +405,16 @@ multilib_src_install_all() {
 		dosym ../../../lib/systemd/systemd-shutdown /usr/lib/systemd/systemd-shutdown
 	fi
 
+	# workaround for https://github.com/systemd/systemd/issues/13501
+	if use hostnamed-fallback; then
+		# this file requires dbus-broker
+		insinto /usr/share/dbus-1/system.d/
+		doins "${FILESDIR}/org.freedesktop.hostname1_no_polkit.conf"
+
+		insinto "${rootprefix}/lib/systemd/system/systemd-hostnamed.service.d/"
+		doins "${FILESDIR}/00-hostnamed-network-user.conf"
+	fi
+
 	gen_usr_ldscript -a systemd udev
 }