feat(configure): add sanity check for kmod/ebpf

Signed-off-by: Gerlando Falauto <[email protected]>

driver/bpf/configure/0__SANITY/test.c

@@ -0,0 +1,23 @@
+// SPDX-License-Identifier: GPL-2.0-only OR MIT
+/*
+
+Copyright (C) 2024 The Falco Authors.
+
+This file is dual licensed under either the MIT or GPL 2. See MIT.txt
+or GPL2.txt for full copies of the license.
+
+*/
+
+/*
+ * Check that the build system is sane.
+ */
+
+#include "../../quirks.h"
+#include "../../ppm_events_public.h"
+#include "../../types.h"
+
+BPF_PROBE("sanity/", sanity, sanity_args) {
+	return 0;
+}
+
+char __license[] __bpf_section("license") = "Dual MIT/GPL";

driver/bpf/configure/Makefile.inc.in

@@ -12,3 +12,12 @@ HAS_@CONFIGURE_MODULE@_OUT := $(subst @@NEWLINE@@,$(newline),$(HAS_@CONFIGURE_MO
 $(info [configure-bpf] Build output for HAS_@CONFIGURE_MODULE@:)
 $(info [configure-bpf] $(HAS_@CONFIGURE_MODULE@_OUT))
 endif
+
+ifeq ('@CONFIGURE_MODULE@','0__SANITY')
+    ifeq ($(HAS_@CONFIGURE_MODULE@),0)
+        $(info [configure-bpf] Build system is sane)
+    else
+        $(info [configure-bpf] Build system is broken, please see above errors)
+        $(error The build system is broken, please see above errors)
+    endif
+endif

driver/configure/0__SANITY/test.c

@@ -0,0 +1,26 @@
+/*
+
+Copyright (C) 2023 The Falco Authors.
+
+This file is dual licensed under either the MIT or GPL 2. See MIT.txt
+or GPL2.txt for full copies of the license.
+
+*/
+
+/*
+ * Check that the build environment is sane
+ */
+
+#include <linux/module.h>
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("the Falco authors");
+
+static int empty_init(void) {
+	return 0;
+}
+
+static void empty_exit(void) {}
+
+module_init(empty_init);
+module_exit(empty_exit);

driver/configure/Makefile.inc.in

@@ -14,3 +14,12 @@ HAS_@CONFIGURE_MODULE@_OUT := $(subst @@NEWLINE@@,$(newline),$(HAS_@CONFIGURE_MO
 $(info [configure-kmod] Build output for HAS_@CONFIGURE_MODULE@:)
 $(info [configure-kmod] $(HAS_@CONFIGURE_MODULE@_OUT))
 endif
+
+ifeq ('@CONFIGURE_MODULE@','0__SANITY')
+    ifeq ($(HAS_@CONFIGURE_MODULE@),0)
+        $(info [configure-kmod] Build system is sane)
+    else
+        $(info [configure-kmod] Build system is broken, please see above errors)
+        $(error The build system is broken, please see above errors)
+    endif
+endif