ifupdown: Don't configure errornous interfaces.

Do not configure interfaces which have a configuration know to be broken.
  Currently this only happens when using "inherit" to an non-existing iface
  or to an iface and not a template, and having allow_any_iface_as_template
  set to 0.

  In those cases broken ifaces will not be configured unless ifup/ifdown is
  invoked with --force.

Signed-off-by: Maximilian Wilhelm <max@sdn.clinic>

cmd/ifupdown.c

@@ -3,6 +3,7 @@
  * Purpose: bring interfaces up or down
  *
  * Copyright (c) 2020 Ariadne Conill <ariadne@dereferenced.org>
+ * Copyright (c) 2020 Maximilian Wilhelm <max@sdn.clinic>
  *
  * Permission to use, copy, modify, and/or distribute this software for any
  * purpose with or without fee is hereby granted, provided that the above
@@ -105,6 +106,12 @@ skip_interface(struct lif_interface *iface, const char *ifname)
 	if (exec_opts.force)
 		return false;
 
+	if (iface->has_config_error)
+	{
+		fprintf(stderr, "%s: skipping interface %s due to config errors\n", argv0, ifname);
+		return true;
+	}
+
 	if (up && iface->refcount > 0)
 	{
 		if (exec_opts.verbose)

libifupdown/interface-file.c

@@ -3,6 +3,7 @@
  * Purpose: /etc/network/interfaces parser
  *
  * Copyright (c) 2020 Ariadne Conill <ariadne@dereferenced.org>
+ * Copyright (c) 2020 Maximilian Wilhelm <max@sdn.clinic>
  *
  * Permission to use, copy, modify, and/or distribute this software for any
  * purpose with or without fee is hereby granted, provided that the above
@@ -137,7 +138,8 @@ handle_address(struct lif_dict *collection, const char *filename, size_t lineno,
 	if (cur_iface == NULL)
 	{
 		report_error(filename, lineno, "%s '%s' without interface", token, addr);
-		return false;
+		/* Ignore this address, but don't fail hard */
+		return true;
 	}
 
 	lif_interface_address_add(cur_iface, addr);
@@ -154,7 +156,10 @@ handle_auto(struct lif_dict *collection, const char *filename, size_t lineno, ch
 
 	char *ifname = lif_next_token(&bufp);
 	if (!*ifname && cur_iface == NULL)
-		return false;
+	{
+		report_error(filename, lineno, "auto without interface");
+		return true;
+	}
 	else
 	{
 		cur_iface = lif_interface_collection_find(collection, ifname);
@@ -179,7 +184,8 @@ handle_gateway(struct lif_dict *collection, const char *filename, size_t lineno,
 	if (cur_iface == NULL)
 	{
 		report_error(filename, lineno, "%s '%s' without interface", token, addr);
-		return false;
+		/* Ignore this gateway, but don't fail hard */
+		return true;
 	}
 
 	lif_interface_use_executor(cur_iface, "static");
@@ -228,7 +234,8 @@ handle_iface(struct lif_dict *collection, const char *filename, size_t lineno, c
 	if (!*ifname)
 	{
 		report_error(filename, lineno, "%s without any other tokens", token);
-		return false;
+		/* This is broken but not fatal */
+		return true;
 	}
 
 	cur_iface = lif_interface_collection_find(collection, ifname);
@@ -278,19 +285,44 @@ handle_inherit(struct lif_dict *collection, const char *filename, size_t lineno,
 	if (cur_iface == NULL)
 	{
 		report_error(filename, lineno, "%s '%s' without interface", token, target);
-		return false;
+		/* This is broken but not fatal */
+		return true;
 	}
 
 	if (!*target)
 	{
-		report_error(filename, lineno, "%s: unspecified interface");
+		report_error(filename, lineno, "iface %s: unspecified inherit target", cur_iface->ifname);
-		return false;
+		/* Mark this interface as errornous but carry on */
+		cur_iface->has_config_error = true;
+		return true;
 	}
 
-	if (!lif_interface_collection_inherit(cur_iface, collection, target))
+	struct lif_interface *parent = lif_interface_collection_find(collection, target);
+	if (parent == NULL)
 	{
-		report_error(filename, lineno, "could not inherit %s", target);
+		report_error(filename, lineno, "iface %s: could not inherit from %s: not found",
-		return false;
+		             cur_iface->ifname, target);
+		/* Mark this interface as errornous but carry on */
+		cur_iface->has_config_error = true;
+		return true;
+
+	}
+
+	if (!lif_config.allow_any_iface_as_template && !parent->is_template)
+	{
+		report_error(filename, lineno, "iface %s: could not inherit from %ss: inheritence from interface not allowed",
+		             cur_iface->ifname, target);
+		/* Mark this interface as errornous but carry on */
+		cur_iface->has_config_error = true;
+		return true;
+	}
+
+	if (!lif_interface_collection_inherit(cur_iface, parent))
+	{
+		report_error(filename, lineno, "iface %s: could not inherit from %s", cur_iface->ifname, target);
+		/* Mark this interface as errornous but carry on */
+		cur_iface->has_config_error = true;
+		return true;
 	}
 
 	return true;
@@ -305,14 +337,16 @@ handle_source(struct lif_dict *collection, const char *filename, size_t lineno,
 	if (!*source_filename)
 	{
 		report_error(filename, lineno, "missing filename to source");
-		return false;
+		/* Broken but not fatal */
+		return true;
 	}
 
 	if (!strcmp(filename, source_filename))
 	{
 		report_error(filename, lineno, "attempt to source %s would create infinite loop",
 			     source_filename);
-		return false;
+		/* Broken but not fatal */
+		return true;
 	}
 
 	return lif_interface_file_parse(collection, source_filename);
@@ -328,7 +362,8 @@ handle_use(struct lif_dict *collection, const char *filename, size_t lineno, cha
 	if (cur_iface == NULL)
 	{
 		report_error(filename, lineno, "%s '%s' without interface", token, executor);
-		return false;
+		/* Broken but not fatal */
+		return true;
 	}
 
 	lif_interface_use_executor(cur_iface, executor);

libifupdown/interface.c

@@ -3,6 +3,7 @@
  * Purpose: interface management
  *
  * Copyright (c) 2020 Ariadne Conill <ariadne@dereferenced.org>
+ * Copyright (c) 2020 Maximilian Wilhelm <max@sdn.clinic>
  *
  * Permission to use, copy, modify, and/or distribute this software for any
  * purpose with or without fee is hereby granted, provided that the above
@@ -233,21 +234,13 @@ lif_interface_collection_delete(struct lif_dict *collection, struct lif_interfac
 }
 
 bool
-lif_interface_collection_inherit(struct lif_interface *interface, struct lif_dict *collection, const char *ifname)
+lif_interface_collection_inherit(struct lif_interface *interface, struct lif_interface *parent)
 {
-	struct lif_interface *parent = lif_interface_collection_find(collection, ifname);
-
-	if (parent == NULL)
-		return false;
-
-	if (!lif_config.allow_any_iface_as_template && !parent->is_template)
-		return false;
-
 	/* maybe convert any interface we are inheriting from into a template */
 	if (lif_config.implicit_template_conversion)
 		parent->is_template = true;
 
-	lif_dict_add(&interface->vars, "inherit", strdup(ifname));
+	lif_dict_add(&interface->vars, "inherit", strdup(parent->ifname));
 	interface->is_bond = parent->is_bond;
 	interface->is_bridge = parent->is_bridge;
 

libifupdown/interface.h

@@ -3,6 +3,7 @@
  * Purpose: interface management
  *
  * Copyright (c) 2020 Ariadne Conill <ariadne@dereferenced.org>
+ * Copyright (c) 2020 Maximilian Wilhelm <max@sdn.clinic>
  *
  * Permission to use, copy, modify, and/or distribute this software for any
  * purpose with or without fee is hereby granted, provided that the above
@@ -52,6 +53,8 @@ struct lif_interface {
 	bool is_bond;
 	bool is_template;
 
+	bool has_config_error;	/* error found in interface configuration */
+
 	struct lif_dict vars;
 
 	size_t refcount;	/* > 0 if up, else 0 */
@@ -74,7 +77,7 @@ extern void lif_interface_collection_init(struct lif_dict *collection);
 extern void lif_interface_collection_fini(struct lif_dict *collection);
 extern struct lif_interface *lif_interface_collection_find(struct lif_dict *collection, const char *ifname);
 extern struct lif_interface *lif_interface_collection_upsert(struct lif_dict *collection, struct lif_interface *interface);
-extern bool lif_interface_collection_inherit(struct lif_interface *interface, struct lif_dict *collection, const char *ifname);
+extern bool lif_interface_collection_inherit(struct lif_interface *interface, struct lif_interface *parent);
 extern void lif_interface_collection_delete(struct lif_dict *collection, struct lif_interface *interface);
 
 #endif

libifupdown/lifecycle.c

@@ -3,6 +3,7 @@
  * Purpose: management of interface lifecycle (bring up, takedown, reload)
  *
  * Copyright (c) 2020 Ariadne Conill <ariadne@dereferenced.org>
+ * Copyright (c) 2020 Maximilian Wilhelm <max@sdn.clinic>
  *
  * Permission to use, copy, modify, and/or distribute this software for any
  * purpose with or without fee is hereby granted, provided that the above
@@ -313,6 +314,19 @@ handle_dependents(const struct lif_execute_opts *opts, struct lif_interface *par
 	{
 		struct lif_interface *iface = lif_interface_collection_find(collection, tokenp);
 
+		if (iface->has_config_error)
+		{
+			if (opts->force)
+				fprintf (stderr, "ifupdown: (de)configuring dependent interface %s (of %s) despite config errors\n",
+				         iface->ifname, parent->ifname);
+			else
+			{
+				fprintf (stderr, "ifupdown: skipping dependent interface %s (of %s) as it has config errors\n",
+			        iface->ifname, parent->ifname);
+				continue;
+			}
+		}
+
 		/* if handle_refcounting returns true, it means we've already
 		 * configured the interface, or it is too soon to deconfigure
 		 * the interface.