MFC r347241 (partial), r347392, r347429: ifconfig(8) ifname <-> kld mapping

MFC r347241 (partial): Initial mechanism for mapping ifname <-> kld

if_tun/if_tap mappings have been removed and the vmnet mapping has been
updated to the if_tap module.

MFC r347392: ifconfig(8): Partial revert of r347241

r347241 introduced an ifname <-> kld mapping table, mostly so tun/tap/vmnet
can autoload the correct module on use. It also inadvertently made bogus
some previously valid uses of sizeof().

Revert back to ifkind on the stack for simplicity sake. This reduces the
diff from the previous version of ifmaybeload for easiser auditing.

MFC r347429: ifconfig(8): Add kld mappings for ipsec/enc

Additionally, providing mappings makes the comparison for already loaded
modules a little more strict. This should have been done at initial
introduction, but there was no real reason- however, it proves necessary for
enc which has a standard enc -> if_enc mapping but there also exists an
'enc' module that's actually CAM. The mapping lets us unambiguously
determine the correct module.

1 files changed, 53 insertions, 6 deletions

diff --git a/sbin/ifconfig/ifconfig.c b/sbin/ifconfig/ifconfig.c
index e330cc915667..4c37ae7d89b0 100644
--- a/sbin/ifconfig/ifconfig.c
+++ b/sbin/ifconfig/ifconfig.c
@@ -71,6 +71,7 @@ static const char rcsid[] =
 #ifdef JAIL
 #include <jail.h>
 #endif
+#include <stdbool.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -130,6 +131,31 @@ struct ifa_order_elt {
 
 TAILQ_HEAD(ifa_queue, ifa_order_elt);
 
+static struct module_map_entry {
+	const char *ifname;
+	const char *kldname;
+} module_map[] = {
+	{
+		.ifname = "vmnet",
+		.kldname = "if_tap",
+	},
+	{
+		.ifname = "ipsec",
+		.kldname = "ipsec",
+	},
+	{
+		/*
+		 * This mapping exists because there is a conflicting enc module
+		 * in CAM.  ifconfig's guessing behavior will attempt to match
+		 * the ifname to a module as well as if_${ifname} and clash with
+		 * CAM enc.  This is an assertion of the correct module to load.
+		 */
+		.ifname = "enc",
+		.kldname = "if_enc",
+	},
+};
+
+
 void
 opt_register(struct option *p)
 {
@@ -1413,9 +1439,11 @@ ifmaybeload(const char *name)
 {
 #define MOD_PREFIX_LEN		3	/* "if_" */
 	struct module_stat mstat;
-	int fileid, modid;
+	int i, fileid, modid;
 	char ifkind[IFNAMSIZ + MOD_PREFIX_LEN], ifname[IFNAMSIZ], *dp;
 	const char *cp;
+	struct module_map_entry *mme;
+	bool found;
 
 	/* loading suppressed by the user */
 	if (noload)
@@ -1429,9 +1457,24 @@ ifmaybeload(const char *name)
 			break;
 		}
 
-	/* turn interface and unit into module name */
-	strlcpy(ifkind, "if_", sizeof(ifkind));
-	strlcat(ifkind, ifname, sizeof(ifkind));
+	/* Either derive it from the map or guess otherwise */
+	*ifkind = '\0';
+	found = false;
+	for (i = 0; i < nitems(module_map); ++i) {
+		mme = &module_map[i];
+		if (strcmp(mme->ifname, ifname) == 0) {
+			strlcpy(ifkind, mme->kldname, sizeof(ifkind));
+			found = true;
+			break;
+		}
+	}
+
+	/* We didn't have an alias for it... we'll guess. */
+	if (!found) {
+	    /* turn interface and unit into module name */
+	    strlcpy(ifkind, "if_", sizeof(ifkind));
+	    strlcat(ifkind, ifname, sizeof(ifkind));
+	}
 
 	/* scan files in kernel */
 	mstat.version = sizeof(struct module_stat);
@@ -1447,8 +1490,12 @@ ifmaybeload(const char *name)
 			} else {
 				cp = mstat.name;
 			}
-			/* already loaded? */
-			if (strcmp(ifname, cp) == 0 ||
+			/*
+			 * Is it already loaded?  Don't compare with ifname if
+			 * we were specifically told which kld to use.  Doing
+			 * so could lead to conflicts not trivially solved.
+			 */
+			if ((!found && strcmp(ifname, cp) == 0) ||
 			    strcmp(ifkind, cp) == 0)
 				return;
 		}