[PATCH] VLAN: Apply bridge port parameters to dynamic VLAN interfaces

[Andrei-Alexandru Bleortu]

bridge_hairpin and bridge_multicast_to_unicast are set on the BSS's own
interface when it joins its bridge, but a dynamic VLAN interface that
vlan_newlink() adds to a VLAN bridge keeps the kernel defaults. Clients
assigned a VLAN then never get their group frames hairpinned back to the
other clients on that interface, so ARP and IPv6 neighbor discovery
between two clients in the same VLAN on the same BSS fail whenever the
driver does not relay them itself.

Set the same bridge port attributes on the VLAN interface once it is in
its bridge, including when it already was.

Assisted-by: LLM
Signed-off-by: Andrei-Alexandru Bleortu <me at andrei-z.com>
---
 src/ap/vlan_full.c | 50 +++++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 45 insertions(+), 5 deletions(-)

diff --git a/src/ap/vlan_full.c b/src/ap/vlan_full.c
index 687fa9c23..9ec3b6465 100644
--- a/src/ap/vlan_full.c
+++ b/src/ap/vlan_full.c
@@ -384,6 +384,39 @@ static int br_getnumports(const char *br_name)
 }
 
 
+/*
+ * Apply the BSS's bridge port parameters (bridge_hairpin,
+ * bridge_multicast_to_unicast) to a VLAN interface in a bridge, as
+ * hostapd_setup_bss() does for the BSS's own interface.
+ */
+static void vlan_br_port_attrs(struct hostapd_data *hapd, const char *ifname)
+{
+	const char *attrs[2];
+	char path[128];
+	unsigned int i, n = 0;
+	FILE *f;
+
+	if (hapd->conf->bridge_hairpin)
+		attrs[n++] = "hairpin_mode";
+	if (hapd->conf->bridge_multicast_to_unicast)
+		attrs[n++] = "multicast_to_unicast";
+
+	for (i = 0; i < n; i++) {
+		os_snprintf(path, sizeof(path), "/sys/class/net/%s/brport/%s",
+			    ifname, attrs[i]);
+		f = fopen(path, "w");
+		if (!f) {
+			wpa_printf(MSG_ERROR, "VLAN: Failed to open %s: %s",
+				   path, strerror(errno));
+			continue;
+		}
+		if (fputs("1", f) < 0 || fclose(f) != 0)
+			wpa_printf(MSG_ERROR, "VLAN: Failed to set %s on %s",
+				   attrs[i], ifname);
+	}
+}
+
+
 static void vlan_newlink_tagged(int vlan_naming, const char *tagged_interface,
 				const char *br_name, int vid,
 				struct hostapd_data *hapd)
@@ -463,7 +496,7 @@ void vlan_newlink(const char *ifname, struct hostapd_data *hapd)
 	char br_name[IFNAMSIZ];
 	struct hostapd_vlan *vlan;
 	struct hostapd_data *vlan_bss = hapd;
-	int untagged, *tagged, i, notempty;
+	int untagged, *tagged, i, notempty, ret;
 
 	wpa_printf(MSG_DEBUG, "VLAN: vlan_newlink(%s)", ifname);
 
@@ -491,16 +524,23 @@ void vlan_newlink(const char *ifname, struct hostapd_data *hapd)
 
 	if (!notempty) {
 		/* Non-VLAN STA */
-		if (hapd->conf->bridge[0] &&
-		    !br_addif(hapd->conf->bridge, ifname))
-			vlan->clean |= DVLAN_CLEAN_WLAN_PORT;
+		if (hapd->conf->bridge[0]) {
+			ret = br_addif(hapd->conf->bridge, ifname);
+			if (ret == 0)
+				vlan->clean |= DVLAN_CLEAN_WLAN_PORT;
+			if (ret >= 0)
+				vlan_br_port_attrs(hapd, ifname);
+		}
 	} else if (untagged > 0 && untagged <= MAX_VLAN_ID) {
 		vlan_bridge_name(br_name, hapd, vlan, untagged);
 
 		vlan_get_bridge(br_name, hapd, untagged);
 
-		if (!br_addif(br_name, ifname))
+		ret = br_addif(br_name, ifname);
+		if (ret == 0)
 			vlan->clean |= DVLAN_CLEAN_WLAN_PORT;
+		if (ret >= 0)
+			vlan_br_port_attrs(hapd, ifname);
 	}
 
 	for (i = 0; i < MAX_NUM_TAGGED_VLAN && tagged[i]; i++) {
-- 
2.47.3