From 13d73250676eae52cdf84768cfcf9c792b81d01b Mon Sep 17 00:00:00 2001
From: Aaron LI <aly@aaronly.me>
Date: Tue, 27 Nov 2018 12:05:58 +0800
Subject: [PATCH] ifconfig(8): Add option -n to disable auto module loading

This option may be used by rc scripts to disable the auto loading of
network modules when try to configure/stop a non-existent interface.
e.g., `ifconfig tap0` will auto load `if_tap.ko` when `tap0` doesn't
exist yet.

Taken-from: FreeBSD (r169873)
---
 sbin/ifconfig/ifconfig.8 | 11 ++++++++++-
 sbin/ifconfig/ifconfig.c | 17 +++++++++++++----
 2 files changed, 23 insertions(+), 5 deletions(-)

diff --git a/sbin/ifconfig/ifconfig.8 b/sbin/ifconfig/ifconfig.8
index 09c1a7118d..dc5df9c141 100644
--- a/sbin/ifconfig/ifconfig.8
+++ b/sbin/ifconfig/ifconfig.8
@@ -28,7 +28,7 @@
 .\"     From: @(#)ifconfig.8	8.3 (Berkeley) 1/5/94
 .\" $FreeBSD: src/sbin/ifconfig/ifconfig.8,v 1.124 2006/10/10 09:44:08 ru Exp $
 .\"
-.Dd June 16, 2018
+.Dd November 27, 2018
 .Dt IFCONFIG 8
 .Os
 .Sh NAME
@@ -39,6 +39,7 @@
 .Op Fl L
 .Op Fl k
 .Op Fl m
+.Op Fl n
 .Ar interface
 .Op Cm create
 .Op Ar address_family
@@ -48,6 +49,7 @@
 .Oc
 .Op Ar parameters
 .Nm
+.Op Fl n
 .Ar interface
 .Cm destroy
 .Nm
@@ -2319,6 +2321,13 @@ the current user.
 This information is not printed by default, as it may be considered
 sensitive.
 .Pp
+If the network interface driver is not present in the kernel then
+.Nm
+will attempt to load it.
+The
+.Fl n
+flag disables this behavior.
+.Pp
 Only the super-user may modify the configuration of a network interface.
 .Sh DIAGNOSTICS
 Messages indicating the specified interface does not exist, the
diff --git a/sbin/ifconfig/ifconfig.c b/sbin/ifconfig/ifconfig.c
index 4d2562d44b..b7f475cc01 100644
--- a/sbin/ifconfig/ifconfig.c
+++ b/sbin/ifconfig/ifconfig.c
@@ -77,6 +77,7 @@ int	doalias;
 int	clearaddr;
 int	newaddr = 1;
 int	verbose;
+int	noload;
 
 int	supmedia = 0;
 int	printkeys = 0;		/* Print keying material for interfaces. */
@@ -118,9 +119,10 @@ usage(void)
 	}
 
 	fprintf(stderr,
-	"usage: ifconfig %sinterface address_family [address [dest_address]]\n"
+	"usage: ifconfig %s[-n] interface address_family [address [dest_address]]\n"
 	"                [parameters]\n"
-	"       ifconfig interface create\n"
+	"       ifconfig [-n] interface create\n"
+	"       ifconfig [-n] interface destroy\n"
 	"       ifconfig -a %s[-d] [-m] [-u] [-v] [address_family]\n"
 	"       ifconfig -l [-d] [-u] [address_family]\n"
 	"       ifconfig %s[-d] [-m] [-u] [-v]\n",
@@ -152,7 +154,7 @@ main(int argc, char *argv[])
 	struct option *p;
 	size_t iflen;
 
-	all = downonly = uponly = namesonly = verbose = 0;
+	all = downonly = uponly = namesonly = verbose = noload = 0;
 
 	/*
 	 * Ensure we print interface name when expected to,
@@ -161,7 +163,7 @@ main(int argc, char *argv[])
 	atexit(printifnamemaybe);
 
 	/* Parse leading line options */
-	strlcpy(options, "adklmuv", sizeof(options));
+	strlcpy(options, "adklmnuv", sizeof(options));
 	for (p = opts; p != NULL; p = p->next)
 		strlcat(options, p->opt, sizeof(options));
 	while ((c = getopt(argc, argv, options)) != -1) {
@@ -181,6 +183,9 @@ main(int argc, char *argv[])
 		case 'm':	/* show media choices in status */
 			supmedia = 1;
 			break;
+		case 'n':	/* suppress module loading */
+			noload++;
+			break;
 		case 'u':	/* restrict scan to "up" interfaces */
 			uponly++;
 			break;
@@ -1035,6 +1040,10 @@ ifmaybeload(const char *name)
 	char ifkind[IFNAMSIZ + MOD_PREFIX_LEN], ifname[IFNAMSIZ], *dp;
 	const char *cp;
 
+	/* loading suppressed by the user */
+	if (noload)
+		return;
+
 	/* trim the interface number off the end */
 	strlcpy(ifname, name, sizeof(ifname));
 	for (dp = ifname; *dp != 0; dp++)
-- 
2.41.0