dtprobed: start as early as possible

We'd like to start dtprobed *before* multi-user.target so that the
majority of daemons (those started after that point, in parallel)
already find it running and can register any USDT probes they may
contain.

We also need to "systemctl enable" everything at install time, since
dtprobed et al don't appear in the presets, so start disabled by
default.  (In the specfile, we not only need to do that but prod
udev to get the udev rules loaded.  This is peculiar since udev
uses filesystem notifies to do that itself, but if that's in the
packaging standard, so be it... we even need to start the thing
by hand after installation, because the systemd macros rely on
dtprobed being named in the presets, which it is not.)

Also turn off RestrictSUIDSGID: it's a good idea but it relies
on a seccomp filter, which stops us from enabling strict seccomp
later on for dtprobed's parser child.

Signed-off-by: Nick Alcock <nick.alcock@oracle.com>
Reviewed-by: Kris Van Hees <kris.van.hees@oracle.com>

dtprobed/Build

@@ -38,4 +38,7 @@ ifdef HAVE_LIBSYSTEMD
 	install -m 644 $(dtprobed_DIR)dtprobed.service $(INSTSYSTEMDUNITDIR)
 	$(call describe-install-target,$(INSTSYSTEMDUNITDIR),dtrace-usdt.target)
 	install -m 644 $(dtprobed_DIR)dtrace-usdt.target $(INSTSYSTEMDUNITDIR)
+	if [[ -z $RPM_BUILD_ROOT ]]; then \
+		systemctl enable dtprobed.service dtrace-usdt.target; \
+	fi
 endif

dtprobed/dtprobed.service

@@ -4,6 +4,11 @@
 [Unit]
 Description=DTrace USDT probe creation daemon
 Documentation=man:dtprobed(8)
+DefaultDependencies=no
+Requires=sysinit.target
+Wants=sysinit.target sockets.target paths.target
+After=sysinit.target sockets.target paths.target
+Before=basic.target
 
 [Service]
 Type=notify
@@ -15,4 +20,7 @@ ProtectHome=true
 PrivateDevices=false
 PrivateNetwork=true
 ProtectControlGroups=true
-RestrictSUIDSGID=true
+
+[Install]
+WantedBy=basic.target
+Also=dtrace-usdt.target

dtprobed/dtrace-usdt.target

@@ -1,3 +1,6 @@
+# Licensed under the Universal Permissive License v 1.0 as shown at
+# http://oss.oracle.com/licenses/upl.
+
 [Unit]
 Description=DTrace USDT operating normally
 Documentation=man:dtprobed(8)
@@ -6,3 +9,7 @@ BindsTo=dtprobed.service
 After=dtprobed.service
 RefuseManualStart=true
 RefuseManualStop=true
+
+[Install]
+WantedBy=basic.target
+Also=dtprobed.service

dtrace.spec

@@ -56,8 +56,9 @@ Name:         dtrace
 License:      Universal Permissive License (UPL), Version 1.0
 Group:        Development/Tools
 Requires:     cpp elfutils-libelf zlib libpcap fuse3 >= 3.2.0
-BuildRequires: glibc-headers bison flex zlib-devel elfutils-libelf-devel fuse3-devel >= 3.2.0 systemd-devel
+BuildRequires: glibc-headers bison flex zlib-devel elfutils-libelf-devel fuse3-devel >= 3.2.0 systemd systemd-devel
 BuildRequires: glibc-static %{glibc32} wireshark libpcap-devel valgrind-devel
+%{?systemd_requires}
 BuildRequires: kernel%{variant}-devel = %{build_kernel}
 %if "%{?dist}" == ".el8"
 BuildRequires: kernel%{variant}-devel = 5.15.0-0.16.2%{?dist}uek
@@ -192,6 +193,10 @@ rm -rf $RPM_BUILD_DIR/%{name}-%{version}
 
 %post
 /sbin/ldconfig
+%udev_rules_update
+%systemd_post dtprobed.service dtrace-usdt.target
+systemctl enable dtprobed.service dtrace-usdt.target
+systemctl start dtprobed.service
 # if systemtap-dtrace.1.gz doesn't exist then we can move the existing dtrace manpage
 MANDIR=/usr/share/man/man1
 if [ -e $MANDIR/dtrace.1.gz -a ! -e $MANDIR/systemtap-dtrace.1.gz ]; then
@@ -210,23 +215,32 @@ elif [ ! -e $SYSINCDIR/sdt.h ]; then
     ln -s $SYSINCDIR/sdt-dtrace.h $SYSINCDIR/sdt.h
 fi
 
+%preun
+%systemd_preun dtprobed.service dtrace-usdt.target
+
 %postun
 /sbin/ldconfig
 MANDIR=/usr/share/man/man1
 if [ -h $MANDIR/dtrace.1.gz ]; then
     rm -f $MANDIR/dtrace.1.gz
 fi
+%udev_rules_update
+%systemd_postun dtprobed.service dtrace-usdt.target
 
 %files
 %defattr(-,root,root,-)
 %{_libdir}/dtrace
 %exclude %{_libdir}/dtrace/testsuite
 %{_libdir}/libdtrace.so.*
 %{_sbindir}/dtrace
+%{_sbindir}/dtprobed
 %{_mandir}/man1/orcl-dtrace.1.gz
 %{_includedir}/sys/sdt-dtrace.h
 %{_includedir}/sys/sdt_internal.h
 %doc %{_docdir}/dtrace-%{version}/*
+%{_unitdir}/dtprobed.service
+%{_unitdir}/dtrace-usdt.target
+%{_udevrulesdir}/60-dtprobed.rules
 
 %files devel
 %defattr(-,root,root,-)