From: Roy Marples <roy@marples.name>
Date: Wed, 9 Oct 2019 11:47:06 +0000 (+0100)
Subject: if: Ignore TAP interfaces by default
X-Git-Tag: v8.1.0~11
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=b2af48e581d28f72ca918d87ace8a8af31854499;p=thirdparty%2Fdhcpcd.git

if: Ignore TAP interfaces by default

TAP interfaces are virtual ethernet and not really distinguishable
from real interfaces other than the interface name.

On BSD the interfaces are always called tapN.
---

diff --git a/src/if-bsd.c b/src/if-bsd.c
index 89013b11..476a3fe2 100644
--- a/src/if-bsd.c
+++ b/src/if-bsd.c
@@ -101,6 +101,12 @@
 #define RT_ADVANCE(x, n) (x += RT_ROUNDUP((n)->sa_len))
 #endif
 
+/* Ignore these interface names which look like ethernet but are virtual. */
+static const char * const ifnames_ignore[] = {
+	"tap",
+	NULL
+};
+
 #ifdef INET6
 static void ifa_setscope(struct sockaddr_in6 *, unsigned int);
 static unsigned int ifa_getscope(const struct sockaddr_in6 *);
@@ -208,6 +214,18 @@ if_closesockets_os(struct dhcpcd_ctx *ctx)
 		close(priv->pf_inet6_fd);
 }
 
+bool
+if_ignore(const char *drvname)
+{
+	const char * const *p;
+
+	for (p = ifnames_ignore; *p; p++) {
+		if (strcmp(*p, drvname) == 0)
+			return true;
+	}
+	return false;
+}
+
 int
 if_carrier(struct interface *ifp)
 {
diff --git a/src/if-linux.c b/src/if-linux.c
index 57e6030e..061b1fa8 100644
--- a/src/if-linux.c
+++ b/src/if-linux.c
@@ -252,6 +252,14 @@ if_conf(struct interface *ifp)
 	return 0;
 }
 
+/* XXX work out TAP interfaces? */
+bool
+if_ignore(__unused const char *drvname)
+{
+
+	return false;
+}
+
 /* XXX work out Virtal Interface Masters */
 int
 if_vimaster(__unused const struct dhcpcd_ctx *ctx, __unused const char *ifname)
diff --git a/src/if-sun.c b/src/if-sun.c
index 687a6ad0..4008698f 100644
--- a/src/if-sun.c
+++ b/src/if-sun.c
@@ -249,14 +249,21 @@ if_mtu_os(const struct interface *ifp)
 }
 
 int
-if_getssid(struct interface *ifp)
+if_getssid(__unused struct interface *ifp)
 {
 
-	UNUSED(ifp);
 	errno = ENOTSUP;
 	return -1;
 }
 
+/* XXX work out TAP interfaces? */
+bool
+if_ignore(__unused const char *drvname)
+{
+
+	return false;
+}
+
 unsigned short
 if_vlanid(__unused const struct interface *ifp)
 {
diff --git a/src/if.c b/src/if.c
index c483f046..b9cf63ed 100644
--- a/src/if.c
+++ b/src/if.c
@@ -405,13 +405,6 @@ if_discover(struct dhcpcd_ctx *ctx, struct ifaddrs **ifaddrs,
 			continue;
 #endif
 
-		/* Don't allow loopback or pointopoint unless explicit */
-		if (ifa->ifa_flags & (IFF_LOOPBACK | IFF_POINTOPOINT)) {
-			if ((argc == 0 || argc == -1) &&
-			    ctx->ifac == 0 && !if_hasconf(ctx, spec.devname))
-				active = IF_INACTIVE;
-		}
-
 		if (if_vimaster(ctx, spec.devname) == 1) {
 			logfunc_t *logfunc = argc != 0 ? logerrx : logdebugx;
 			logfunc("%s: is a Virtual Interface Master, skipping",
@@ -419,6 +412,17 @@ if_discover(struct dhcpcd_ctx *ctx, struct ifaddrs **ifaddrs,
 			continue;
 		}
 
+#define	IF_NOCONF	((argc == 0 || argc == -1) && ctx->ifac == 0 && \
+			 !if_hasconf(ctx, spec.devname))
+
+		/* Don't allow loopback or pointopoint unless explicit.
+		 * Don't allow some reserved interface names unless explicit. */
+		if (IF_NOCONF) {
+			if (ifa->ifa_flags & (IFF_LOOPBACK | IFF_POINTOPOINT) ||
+			    if_ignore(spec.drvname))
+				active = IF_INACTIVE;
+		}
+
 		ifp = calloc(1, sizeof(*ifp));
 		if (ifp == NULL) {
 			logerr(__func__);
@@ -495,9 +499,7 @@ if_discover(struct dhcpcd_ctx *ctx, struct ifaddrs **ifaddrs,
 #endif
 			default:
 				/* Don't allow unless explicit */
-				if ((argc == 0 || argc == -1) &&
-				    ctx->ifac == 0 &&
-				    !if_hasconf(ctx, ifp->name))
+				if (IF_NOCONF)
 					active = IF_INACTIVE;
 				if (active)
 					logwarnx("%s: unsupported"
diff --git a/src/if.h b/src/if.h
index 4126fd33..0800c102 100644
--- a/src/if.h
+++ b/src/if.h
@@ -152,6 +152,7 @@ int if_nametospec(const char *, struct if_spec *);
 int if_conf(struct interface *);
 int if_init(struct interface *);
 int if_getssid(struct interface *);
+bool if_ignore(const char *);
 int if_vimaster(const struct dhcpcd_ctx *ctx, const char *);
 unsigned short if_vlanid(const struct interface *);
 int if_opensockets(struct dhcpcd_ctx *);