added helper script to compile eBPF modules

utils/packaging/build_modules.sh

@@ -0,0 +1,62 @@
+#!/bin/sh
+#
+# opensnitch - 2022
+#
+echo """
+
+  Dependencies needed to compile the eBPF modules:
+  sudo apt install -y wget flex bison ca-certificates wget python3 rsync bc libssl-dev clang llvm libelf-dev libzip-dev git libpcap-dev
+  ---
+"""
+
+kernel_version=$(uname -r | cut -d. -f1,2)
+if [ ! -z $1 ]; then
+    kernel_version=$1
+fi
+
+kernel_sources="v${kernel_version}.tar.gz"
+
+if [ -f "${kernel_sources}" ]; then
+    echo -n "[i] Deleting previous kernel sources ${kernel_sources}: "
+    rm -f ${kernel_sources} && echo "OK" || echo "ERROR"
+fi
+echo "[+] Downloading kernel sources:"
+wget -nv --show-progress https://github.com/torvalds/linux/archive/${kernel_sources} 1>/dev/null
+echo
+
+if [ -d "linux-${kernel_version}/" ]; then
+    echo -n "[i] Deleting previous kernel sources dir linux-${kernel_version}/: "
+    rm -rf linux-${kernel_version}/ && echo "OK" || echo "ERROR"
+fi
+echo -n "[+] Uncompressing kernel sources: "
+tar -xf v${kernel_version}.tar.gz && echo "OK" || echo "ERROR"
+
+echo "[+] Patching kernel sources"
+patch linux-${kernel_version}/tools/lib/bpf/bpf_helpers.h < ebpf_prog/file.patch
+cp ebpf_prog/opensnitch*.c ebpf_prog/common.h ebpf_prog/Makefile linux-${kernel_version}/samples/bpf
+
+echo -n "[+] Preparing kernel sources... (1-2 minutes): "
+echo -n "."
+cd linux-${kernel_version} && yes "" | make oldconfig 1>/dev/null
+echo -n "."
+make prepare 1>/dev/null
+echo -n "."
+make headers_install 1>/dev/null
+echo " DONE"
+
+echo "[+] Compiling eBPF modules..."
+cd samples/bpf && make 1>/dev/null
+# objdump -h opensnitch.o #you should see many section, number 1 should be called kprobe/tcp_v4_connect
+
+if [ ! -d ../../../ebpf_prog/modules/ ]; then
+    mkdir ../../../ebpf_prog/modules/
+fi
+cp opensnitch*o ../../../ebpf_prog/modules/
+cd ../../../
+llvm-strip -g ebpf_prog/modules/opensnitch.o #remove debug info
+
+if [ -f ebpf_prog/modules/opensnitch.o ]; then
+    echo
+    ls ebpf_prog/modules/*.o
+    echo -e "\n * eBPF modules compiled. Now you can copy the *.o files to /etc/opensnitchd/ and restart the daemon\n"
+fi