selftests: add prepare_system.sh

Bugzilla: https://bugzilla.redhat.com/2177177
Upstream-status: RHEL9 only

The selftests do not necessarily run out of box. Add a script to
configure the system for the selftests. As this can be fairly
destructive to the system, three levels of safety/destructiveness are
available. Of course, some tests will fail if you don't apply the most
destructive level.

This is not upstream for two major reasons:

1. We use different kernel config than the one mandated upstream. At
   least for bpf selftests, upstream is refusing to accommodate systems
   that differ to selftests/bpf/config.

2. Some of the setup is inherently RHEL specific.

This is not applied to ARK, since the necessary modifications evolve
over time and are tied to the particular RHEL version.

Signed-off-by: Jiri Benc <jbenc@redhat.com>

Author: Jiri Benc

tools/testing/selftests/Makefile

@@ -219,6 +219,7 @@ ifdef INSTALL_PATH
 	install -m 744 kselftest/runner.sh $(INSTALL_PATH)/kselftest/
 	install -m 744 kselftest/prefix.pl $(INSTALL_PATH)/kselftest/
 	install -m 744 run_kselftest.sh $(INSTALL_PATH)/
+	install -m 744 prepare_system.sh $(INSTALL_PATH)/
 	rm -f $(TEST_LIST)
 	@ret=1;	\
 	for TARGET in $(TARGETS); do \

tools/testing/selftests/prepare_system.sh

@@ -0,0 +1,104 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+# Copyright Red Hat
+# author: Jiri Benc <jbenc@redhat.com>
+
+set -e
+
+function print_help
+{
+	{
+	echo "Usage: $0 OPTIONS collection..."
+	echo
+	echo "Prepares the system to execute kernel selftests for the given collection(s)."
+	echo "To list the available collections, run ./run_kselftest.sh -l. Alternatively,"
+	echo "specify 'all' to prepare for all collections."
+	echo
+	echo "Options:"
+	echo "  -s  safe modifications only"
+	echo "  -m  load kernel modules; -s is implied"
+	echo "  -d  destructive modifications; -m and -s is implied"
+	echo
+	echo "Note that if you use -d, your system will not be useful for anything else"
+	echo "than the selftests afterwards."
+	} >&2
+	exit $1
+}
+
+# If you need to add a particular modification for a test collection, just
+# add a new function with the name prepare_collection_safe,
+# prepare_collection_modules and/or prepare_collection_destructive. The rest
+# will be taken care of automatically. The - and / characters in collection
+# names are translated to underscore. Beware that "set -e" is enabled.
+
+function prepare_bpf_safe
+{
+	echo 1 > /proc/sys/net/mptcp/enabled
+}
+
+function prepare_bpf_modules
+{
+	modprobe nf_conntrack
+	modprobe nf_nat
+}
+
+function prepare_bpf_destructive
+{
+	dnf install -y --allowerasing \
+		https://kojipkgs.fedoraproject.org/packages/iptables/1.8.7/15.fc36/x86_64/iptables-libs-1.8.7-15.fc36.x86_64.rpm \
+		https://kojipkgs.fedoraproject.org/packages/iptables/1.8.7/15.fc36/x86_64/iptables-legacy-libs-1.8.7-15.fc36.x86_64.rpm \
+		https://kojipkgs.fedoraproject.org/packages/iptables/1.8.7/15.fc36/x86_64/iptables-legacy-1.8.7-15.fc36.x86_64.rpm
+}
+
+level=0
+while getopts smdh opt; do
+	case $opt in
+	s) (( level > 1 )) || level=1 ;;
+	m) (( level > 2 )) || level=2 ;;
+	d) (( level > 3 )) || level=3 ;;
+	h) print_help 0 ;;
+	?) exit 1 ;;
+	esac
+done
+shift $((OPTIND - 1))
+[[ $# -gt 0 ]] || print_help 1
+if (( level == 0 )); then
+	echo "You must specify -s, -m or -d. See $0 -h for help." >&2
+	exit 1
+fi
+
+if (( UID != 0 )); then
+	echo "Please run this as root.">&2
+	exit 1
+fi
+
+unset available
+declare -A available
+for func in $(compgen -A function); do
+	[[ $func == prepare_* ]] || continue
+	available[$func]=1
+done
+
+for component in "$@"; do
+	# convert characters not valid in function names to _
+	component=${component//[-\/]/_}
+	if [[ $component == all ]]; then
+		for func in "${!available[@]}"; do
+			if [[ ( $func == *_safe && $level -ge 1 ) || \
+			      ( $func == *_modules && $level -ge 2 ) || \
+			      ( $func == *_destructive && $level -ge 3 ) ]]; then
+				$func
+			fi
+		done
+	else
+		if [[ $level -ge 1 && ${available[prepare_${component}_safe]} ]]; then
+			prepare_${component}_safe
+		fi
+		if [[ $level -ge 2 && ${available[prepare_${component}_modules]} ]]; then
+			prepare_${component}_modules
+		fi
+		if [[ $level -ge 3 && ${available[prepare_${component}_destructive]} ]]; then
+			prepare_${component}_destructive
+		fi
+	fi
+done