[PATCHv2 03/21] bridge: track inter-BSS usage
Michael Braun
michael-dev
Thu Jun 6 03:09:23 PDT 2013
Currently, struct hostapd_vlan is a per-BSS data structure which
also contains informations about whether to remove the bridge
or clear wlan / tagged-vlan interface from the bridge.
In a multi-interface multi-BSS setup, this can lead to the following
race condition:
1. wlan0 creates VLAN A, sets DVLAN_CLEAN_BR and DVLAN_CLEAN_VLAN_PORT
2. wlan1 creates VLAN A, does not set DVLAN_CLEAN_BR and DVLAN_CLEAN_VLAN_PORT
as already there
3. wlan0 removes VLAN A, removes tagged-interface from the bridge
but not the bridge.
Now wlan1 VLAN A is unusable due to the missing uplink.
4. wlan1 removes VLAN A, does not cleanup
Solution: This requires an inter-BSS inter-interface data structure
to track the bridge / bridge port usage within hostapd.
This data structure could also be used to track any other
device-has-been-created-by-hostapd information or when
retarding interface freeing.
Signed-hostap: Michael Braun <michael-dev at fami-braun.de>
diff --git a/src/ap/hostapd.h b/src/ap/hostapd.h
index 55f6dd8..75d9c66 100644
--- a/src/ap/hostapd.h
+++ b/src/ap/hostapd.h
@@ -25,6 +25,7 @@ enum wps_event;
union wps_event_data;
struct hostapd_iface;
+struct hostapd_dynamic_iface;
struct hapd_interfaces {
int (*reload_config)(struct hostapd_iface *iface);
@@ -37,11 +38,13 @@ struct hapd_interfaces {
int (*driver_init)(struct hostapd_iface *iface);
size_t count;
+ size_t count_dynamic;
int global_ctrl_sock;
char *global_iface_path;
char *global_iface_name;
gid_t ctrl_iface_group;
struct hostapd_iface **iface;
+ struct hostapd_dynamic_iface **dynamic_iface;
};
@@ -275,6 +278,16 @@ struct hostapd_iface {
void (*scan_cb)(struct hostapd_iface *iface);
};
+/**
+ * struct hostapd_dynamic_iface - hostapd per dynamically allocated
+ * or added interface data structure
+ */
+struct hostapd_dynamic_iface {
+ char parent[IFNAMSIZ + 1];
+ char iface[IFNAMSIZ + 1];
+ unsigned int usage;
+};
+
/* hostapd.c */
int hostapd_for_each_interface(struct hapd_interfaces *interfaces,
int (*cb)(struct hostapd_iface *iface,
diff --git a/src/ap/vlan_init.c b/src/ap/vlan_init.c
index 3cdd1a6..dd234a0 100644
--- a/src/ap/vlan_init.c
+++ b/src/ap/vlan_init.c
@@ -479,6 +479,120 @@ static int vlan_set_name_type(unsigned int name_type)
#endif /* CONFIG_VLAN_NETLINK */
+/**
+ * Increase the usage counter for given parent/ifname combination.
+ * If create is set, then this iface is added to the global list.
+ * Returns
+ * -1 on error
+ * 0 if iface is not in list
+ * 1 if iface is in list (was there or has been added)
+ */
+static int hapd_get_dynamic_iface(char *parent, char *ifname, int create,
+ struct hostapd_data *hapd)
+{
+ int i;
+ struct hostapd_dynamic_iface *j = NULL, **tmp;
+ struct hapd_interfaces *hapd_global = hapd->iface->interfaces;
+
+ if (!parent)
+ parent = "";
+
+ for (i = 0; i < hapd_global->count_dynamic; i++) {
+ j = hapd_global->dynamic_iface[i];
+ if (os_strncmp(j->iface, ifname, sizeof(j->iface)) == 0 &&
+ os_strncmp(j->parent, parent, sizeof(j->parent)) == 0)
+ break;
+ }
+ if (i < hapd_global->count_dynamic) {
+ j->usage++;
+ return 1;
+ }
+
+ /* new entry required */
+ if (!create)
+ return 0;
+
+ j = os_zalloc(sizeof(*j));
+ if (!j)
+ return -1;
+ os_strncpy(j->iface, ifname, sizeof(j->iface));
+ os_strncpy(j->parent, parent, sizeof(j->parent));
+
+ tmp = os_realloc_array(hapd_global->dynamic_iface, i + 1,
+ sizeof(*hapd_global->dynamic_iface));
+ if (!tmp) {
+ wpa_printf(MSG_ERROR, "VLAN: failed to allocate memory in %s",
+ __FUNCTION__);
+ return -1;
+ }
+ hapd_global->count_dynamic++;
+ hapd_global->dynamic_iface = tmp;
+ hapd_global->dynamic_iface[i] = j;
+
+ return 1;
+}
+
+/**
+ * Decrease the usage counter for given ifname.
+ * Returns
+ * -1 on error or if iface was not found
+ * 0 if iface was found and is still present
+ * 1 if iface was removed from global list
+ */
+static int hapd_put_dynamic_iface(char *parent, char *ifname,
+ struct hostapd_data *hapd)
+{
+ int i;
+ struct hostapd_dynamic_iface *j = NULL, **tmp;
+ struct hapd_interfaces *hapd_glob = hapd->iface->interfaces;
+
+ if (!parent)
+ parent = "";
+
+ for (i = 0; i < hapd_glob->count_dynamic; i++) {
+ j = hapd_glob->dynamic_iface[i];
+ if (os_strncmp(j->iface, ifname, sizeof(j->iface)) == 0 &&
+ os_strncmp(j->parent, parent, sizeof(j->parent)) == 0)
+ break;
+ }
+
+ if (i == hapd_glob->count_dynamic) {
+ /* interface not in global list
+ * Could happen if alloc in _get_ failed.
+ */
+ return -1;
+ }
+
+ if (j->usage > 0) {
+ j->usage--;
+ return 0;
+ }
+
+ os_free(j);
+ for (; i < hapd_glob->count_dynamic - 1; i++) {
+ hapd_glob->dynamic_iface[i] = hapd_glob->dynamic_iface[i + 1];
+ }
+ hapd_glob->dynamic_iface[hapd_glob->count_dynamic - 1] = NULL;
+ hapd_glob->count_dynamic--;
+
+ if (hapd_glob->count_dynamic == 0) {
+ os_free(hapd_glob->dynamic_iface);
+ hapd_glob->dynamic_iface = NULL;
+ return 1;
+ }
+
+ tmp = os_realloc_array(hapd_glob->dynamic_iface,
+ hapd_glob->count_dynamic,
+ sizeof(*hapd_glob->dynamic_iface));
+ if (!tmp) {
+ wpa_printf(MSG_ERROR, "VLAN: failed to release memory in %s",
+ __FUNCTION__);
+ return -1;
+ }
+ hapd_glob->dynamic_iface = tmp;
+
+ return 1;
+}
static void vlan_newlink(char *ifname, struct hostapd_data *hapd)
{
@@ -487,6 +601,7 @@ static void vlan_newlink(char *ifname, struct hostapd_data *hapd)
struct hostapd_vlan *vlan = hapd->conf->vlan;
char *tagged_interface = hapd->conf->ssid.vlan_tagged_interface;
int vlan_naming = hapd->conf->ssid.vlan_naming;
+ int ret;
wpa_printf(MSG_DEBUG, "VLAN: vlan_newlink(%s)", ifname);
@@ -506,7 +621,9 @@ static void vlan_newlink(char *ifname, struct hostapd_data *hapd)
"brvlan%d", vlan->vlan_id);
}
- if (!br_addbr(br_name))
+ ret = br_addbr(br_name);
+ if (hapd_get_dynamic_iface(NULL, br_name, (ret == 0),
+ hapd))
vlan->clean |= DVLAN_CLEAN_BR;
ifconfig_up(br_name);
@@ -524,17 +641,24 @@ static void vlan_newlink(char *ifname, struct hostapd_data *hapd)
"vlan%d", vlan->vlan_id);
ifconfig_up(tagged_interface);
- if (!vlan_add(tagged_interface, vlan->vlan_id,
- vlan_ifname))
+ ret = vlan_add(tagged_interface, vlan->vlan_id,
+ vlan_ifname);
+ if (hapd_get_dynamic_iface(NULL, vlan_ifname,
+ (ret == 0), hapd))
vlan->clean |= DVLAN_CLEAN_VLAN;
- if (!br_addif(br_name, vlan_ifname))
+ ret = br_addif(br_name, vlan_ifname);
+ if (hapd_get_dynamic_iface(br_name,
+ vlan_ifname,
+ (ret == 0), hapd))
vlan->clean |= DVLAN_CLEAN_VLAN_PORT;
ifconfig_up(vlan_ifname);
}
- if (!br_addif(br_name, ifname))
+ ret = br_addif(br_name, ifname);
+ if (hapd_get_dynamic_iface(br_name, ifname, (ret == 0),
+ hapd))
vlan->clean |= DVLAN_CLEAN_WLAN_PORT;
ifconfig_up(ifname);
@@ -573,7 +697,9 @@ static void vlan_dellink(char *ifname, struct hostapd_data *hapd)
"brvlan%d", vlan->vlan_id);
}
- if (vlan->clean & DVLAN_CLEAN_WLAN_PORT)
+ if ((vlan->clean & DVLAN_CLEAN_WLAN_PORT) &&
+ hapd_put_dynamic_iface(br_name, vlan->ifname,
+ hapd))
br_delif(br_name, vlan->ifname);
if (tagged_interface) {
@@ -587,15 +713,20 @@ static void vlan_dellink(char *ifname, struct hostapd_data *hapd)
os_snprintf(vlan_ifname,
sizeof(vlan_ifname),
"vlan%d", vlan->vlan_id);
- if (vlan->clean & DVLAN_CLEAN_VLAN_PORT)
+ if ((vlan->clean & DVLAN_CLEAN_VLAN_PORT) &&
+ hapd_put_dynamic_iface(br_name,
+ vlan_ifname, hapd))
br_delif(br_name, vlan_ifname);
ifconfig_down(vlan_ifname);
- if (vlan->clean & DVLAN_CLEAN_VLAN)
+ if ((vlan->clean & DVLAN_CLEAN_VLAN) &&
+ hapd_put_dynamic_iface(NULL,
+ vlan_ifname, hapd))
vlan_rem(vlan_ifname);
}
if ((vlan->clean & DVLAN_CLEAN_BR) &&
+ hapd_put_dynamic_iface(NULL, br_name, hapd) &&
br_getnumports(br_name) == 0) {
ifconfig_down(br_name);
br_delbr(br_name);
More information about the Hostap
mailing list