capabilities: CAP_CHOWN might be required by many plugins opening UNIX sockets

But as the sockets will be created with the user/group of the running
process this might not be required as no change may be needed.

src/libcharon/plugins/duplicheck/duplicheck_plugin.c

@@ -98,6 +98,12 @@ plugin_t *duplicheck_plugin_create()
 		return NULL;
 	}
 
+	if (!lib->caps->keep(lib->caps, CAP_CHOWN))
+	{	/* required to chown(2) notify socket */
+		DBG1(DBG_CFG, "duplicheck plugin requires CAP_CHOWN capability");
+		return NULL;
+	}
+
 	INIT(this,
 		.public = {
 			.plugin = {

src/libcharon/plugins/error_notify/error_notify_plugin.c

@@ -92,6 +92,12 @@ plugin_t *error_notify_plugin_create()
 {
 	private_error_notify_plugin_t *this;
 
+	if (!lib->caps->keep(lib->caps, CAP_CHOWN))
+	{	/* required to chown(2) notify socket */
+		DBG1(DBG_CFG, "error-notify plugin requires CAP_CHOWN capability");
+		return NULL;
+	}
+
 	INIT(this,
 		.public = {
 			.plugin = {

src/libcharon/plugins/ha/ha_plugin.c

@@ -179,6 +179,12 @@ plugin_t *ha_plugin_create()
 		return NULL;
 	}
 
+	if (!lib->caps->keep(lib->caps, CAP_CHOWN))
+	{	/* required to chown(2) control socket */
+		DBG1(DBG_CFG, "ha plugin requires CAP_CHOWN capability");
+		return NULL;
+	}
+
 	INIT(this,
 		.public = {
 			.plugin = {

src/libcharon/plugins/load_tester/load_tester_plugin.c

@@ -269,6 +269,12 @@ plugin_t *load_tester_plugin_create()
 		return NULL;
 	}
 
+	if (!lib->caps->keep(lib->caps, CAP_CHOWN))
+	{	/* required to chown(2) control socket */
+		DBG1(DBG_CFG, "load-tester plugin requires CAP_CHOWN capability");
+		return NULL;
+	}
+
 	INIT(this,
 		.public = {
 			.plugin = {

src/libcharon/plugins/lookip/lookip_plugin.c

@@ -92,6 +92,12 @@ plugin_t *lookip_plugin_create()
 {
 	private_lookip_plugin_t *this;
 
+	if (!lib->caps->keep(lib->caps, CAP_CHOWN))
+	{	/* required to chown(2) control socket */
+		DBG1(DBG_CFG, "lookip plugin requires CAP_CHOWN capability");
+		return NULL;
+	}
+
 	INIT(this,
 		.public = {
 			.plugin = {

src/libcharon/plugins/smp/smp.c

@@ -739,6 +739,12 @@ plugin_t *smp_plugin_create()
 	private_smp_t *this;
 	mode_t old;
 
+	if (!lib->caps->keep(lib->caps, CAP_CHOWN))
+	{	/* required to chown(2) control socket */
+		DBG1(DBG_CFG, "smp plugin requires CAP_CHOWN capability");
+		return NULL;
+	}
+
 	INIT(this,
 		.public = {
 			.plugin = {

src/libcharon/plugins/stroke/stroke_plugin.c

@@ -91,6 +91,12 @@ plugin_t *stroke_plugin_create()
 {
 	private_stroke_plugin_t *this;
 
+	if (!lib->caps->keep(lib->caps, CAP_CHOWN))
+	{	/* required to chown(2) stroke socket */
+		DBG1(DBG_CFG, "stroke plugin requires CAP_CHOWN capability");
+		return NULL;
+	}
+
 	INIT(this,
 		.public = {
 			.plugin = {

src/libcharon/plugins/whitelist/whitelist_plugin.c

@@ -92,6 +92,12 @@ plugin_t *whitelist_plugin_create()
 {
 	private_whitelist_plugin_t *this;
 
+	if (!lib->caps->keep(lib->caps, CAP_CHOWN))
+	{	/* required to chown(2) control socket */
+		DBG1(DBG_CFG, "whitelist plugin requires CAP_CHOWN capability");
+		return NULL;
+	}
+
 	INIT(this,
 		.public = {
 			.plugin = {