bridge: Add a default_pvid sysfs attribute

This patch allows the user to set and retrieve default_pvid
value.  A new value can only be stored when vlan filtering
is disabled.

Signed-off-by: Vladislav Yasevich <vyasevic@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 48 insertions, 0 deletions

diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h
index fe7463c2af9a..5a347eb1d139 100644
--- a/net/bridge/br_private.h
+++ b/net/bridge/br_private.h
@@ -299,6 +299,7 @@ struct net_bridge
 #ifdef CONFIG_BRIDGE_VLAN_FILTERING
         u8                              vlan_enabled;
         __be16                          vlan_proto;
+        u16                             default_pvid;
         struct net_port_vlans __rcu     *vlan_info;
 #endif
 };
@@ -605,6 +606,7 @@ void br_recalculate_fwd_mask(struct net_bridge *br);
 int br_vlan_filter_toggle(struct net_bridge *br, unsigned long val);
 int br_vlan_set_proto(struct net_bridge *br, unsigned long val);
 void br_vlan_init(struct net_bridge *br);
+int br_vlan_set_default_pvid(struct net_bridge *br, unsigned long val);
 int nbp_vlan_add(struct net_bridge_port *port, u16 vid, u16 flags);
 int nbp_vlan_delete(struct net_bridge_port *port, u16 vid);
 void nbp_vlan_flush(struct net_bridge_port *port);
diff --git a/net/bridge/br_sysfs_br.c b/net/bridge/br_sysfs_br.c
index cb431c6016ee..4c97fc50fb70 100644
--- a/net/bridge/br_sysfs_br.c
+++ b/net/bridge/br_sysfs_br.c
@@ -725,6 +725,22 @@ static ssize_t vlan_protocol_store(struct device *d,
         return store_bridge_parm(d, buf, len, br_vlan_set_proto);
 }
 static DEVICE_ATTR_RW(vlan_protocol);
+
+static ssize_t default_pvid_show(struct device *d,
+                                 struct device_attribute *attr,
+                                 char *buf)
+{
+        struct net_bridge *br = to_bridge(d);
+        return sprintf(buf, "%d\n", br->default_pvid);
+}
+
+static ssize_t default_pvid_store(struct device *d,
+                                  struct device_attribute *attr,
+                                  const char *buf, size_t len)
+{
+        return store_bridge_parm(d, buf, len, br_vlan_set_default_pvid);
+}
+static DEVICE_ATTR_RW(default_pvid);
 #endif
 
 static struct attribute *bridge_attrs[] = {
@@ -771,6 +787,7 @@ static struct attribute *bridge_attrs[] = {
 #ifdef CONFIG_BRIDGE_VLAN_FILTERING
         &dev_attr_vlan_filtering.attr,
         &dev_attr_vlan_protocol.attr,
+        &dev_attr_default_pvid.attr,
 #endif
         NULL
 };
diff --git a/net/bridge/br_vlan.c b/net/bridge/br_vlan.c
index 3ba57fcdcd13..dfa7c9a7e193 100644
--- a/net/bridge/br_vlan.c
+++ b/net/bridge/br_vlan.c
@@ -499,9 +499,38 @@ err_filt:
         goto unlock;
 }
 
+int br_vlan_set_default_pvid(struct net_bridge *br, unsigned long val)
+{
+        u16 pvid = val;
+        int err = 0;
+
+        if (!val || val >= VLAN_VID_MASK)
+                return -EINVAL;
+
+        if (!rtnl_trylock())
+                return restart_syscall();
+
+        if (pvid == br->default_pvid)
+                goto unlock;
+
+        /* Only allow default pvid change when filtering is disabled */
+        if (br->vlan_enabled) {
+                pr_info_once("Please disable vlan filtering to change default_pvid\n");
+                err = -EPERM;
+                goto unlock;
+        }
+
+        br->default_pvid = pvid;
+
+unlock:
+        rtnl_unlock();
+        return err;
+}
+
 void br_vlan_init(struct net_bridge *br)
 {
         br->vlan_proto = htons(ETH_P_8021Q);
+        br->default_pvid = 1;
 }
 
 /* Must be protected by RTNL.