bridge: vlan: use proper rcu for the vlgrp member

The bridge and port's vlgrp member is already used in RCU way, currently
we rely on the fact that it cannot disappear while the port exists but
that is error-prone and we might miss places with improper locking
(either RCU or RTNL must be held to walk the vlan_list). So make it
official and use RCU for vlgrp to catch offenders. Introduce proper vlgrp
accessors and use them consistently throughout the code.

Signed-off-by: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
Reviewed-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/bridge/br_device.c b/net/bridge/br_device.c
index bdfb9544ca0379a88df9ac31d1e68789cf4aedba..5e88d3e17546618a728bb429fc61e20d5f8d79dc 100644 (file)
--- a/net/bridge/br_device.c
+++ b/net/bridge/br_device.c
@@ -56,7 +56,7 @@ netdev_tx_t br_dev_xmit(struct sk_buff *skb, struct net_device *dev)
        skb_reset_mac_header(skb);
        skb_pull(skb, ETH_HLEN);
 
-       if (!br_allowed_ingress(br, br_vlan_group(br), skb, &vid))
+       if (!br_allowed_ingress(br, br_vlan_group_rcu(br), skb, &vid))
                goto out;
 
        if (is_broadcast_ether_addr(dest))

diff --git a/net/bridge/br_forward.c b/net/bridge/br_forward.c
index 6d5ed795c3e2ae2857edf404f6692b9d990e7c98..a9d424e20229c2c43a22240144ae7b973598871f 100644 (file)
--- a/net/bridge/br_forward.c
+++ b/net/bridge/br_forward.c
@@ -32,7 +32,7 @@ static inline int should_deliver(const struct net_bridge_port *p,
 {
        struct net_bridge_vlan_group *vg;
 
-       vg = nbp_vlan_group(p);
+       vg = nbp_vlan_group_rcu(p);
        return ((p->flags & BR_HAIRPIN_MODE) || skb->dev != p->dev) &&
                br_allowed_egress(vg, skb) && p->state == BR_STATE_FORWARDING;
 }
@@ -80,7 +80,7 @@ static void __br_deliver(const struct net_bridge_port *to, struct sk_buff *skb)
 {
        struct net_bridge_vlan_group *vg;
 
-       vg = nbp_vlan_group(to);
+       vg = nbp_vlan_group_rcu(to);
        skb = br_handle_vlan(to->br, vg, skb);
        if (!skb)
                return;
@@ -112,7 +112,7 @@ static void __br_forward(const struct net_bridge_port *to, struct sk_buff *skb)
                return;
        }
 
-       vg = nbp_vlan_group(to);
+       vg = nbp_vlan_group_rcu(to);
        skb = br_handle_vlan(to->br, vg, skb);
        if (!skb)
                return;

diff --git a/net/bridge/br_input.c b/net/bridge/br_input.c
index f5c5a4500e2f676f8f301da265474ec1e175a7dc..f7fba74108a9377b12610c9cdfa033dc8c7c92a0 100644 (file)
--- a/net/bridge/br_input.c
+++ b/net/bridge/br_input.c
@@ -44,7 +44,7 @@ static int br_pass_frame_up(struct sk_buff *skb)
        brstats->rx_bytes += skb->len;
        u64_stats_update_end(&brstats->syncp);
 
-       vg = br_vlan_group(br);
+       vg = br_vlan_group_rcu(br);
        /* Bridge is just like any other port.  Make sure the
         * packet is allowed except in promisc modue when someone
         * may be running packet capture.
@@ -140,7 +140,7 @@ int br_handle_frame_finish(struct net *net, struct sock *sk, struct sk_buff *skb
        if (!p || p->state == BR_STATE_DISABLED)
                goto drop;
 
-       if (!br_allowed_ingress(p->br, nbp_vlan_group(p), skb, &vid))
+       if (!br_allowed_ingress(p->br, nbp_vlan_group_rcu(p), skb, &vid))
                goto out;
 
        /* insert into forwarding database after filtering to avoid spoofing */

diff --git a/net/bridge/br_netlink.c b/net/bridge/br_netlink.c
index d792d1a848ad09fde1c883867f058af0efb9d48c..2ee8fd63c7269246b1663f71f0011daad4dca828 100644 (file)
--- a/net/bridge/br_netlink.c
+++ b/net/bridge/br_netlink.c
@@ -102,10 +102,10 @@ static size_t br_get_link_af_size_filtered(const struct net_device *dev,
        rcu_read_lock();
        if (br_port_exists(dev)) {
                p = br_port_get_rcu(dev);
-               vg = nbp_vlan_group(p);
+               vg = nbp_vlan_group_rcu(p);
        } else if (dev->priv_flags & IFF_EBRIDGE) {
                br = netdev_priv(dev);
-               vg = br_vlan_group(br);
+               vg = br_vlan_group_rcu(br);
        }
        num_vlan_infos = br_get_num_vlan_infos(vg, filter_mask);
        rcu_read_unlock();

diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h
index ba0c67b2159a59a277d8142d7871f3af91578c83..8835642a6326f1661403d6b257cb7d7391da5e1a 100644 (file)
--- a/net/bridge/br_private.h
+++ b/net/bridge/br_private.h
@@ -132,6 +132,7 @@ struct net_bridge_vlan_group {
        struct list_head                vlan_list;
        u16                             num_vlans;
        u16                             pvid;
+       struct rcu_head                 rcu;
 };
 
 struct net_bridge_fdb_entry
@@ -229,7 +230,7 @@ struct net_bridge_port
        struct netpoll                  *np;
 #endif
 #ifdef CONFIG_BRIDGE_VLAN_FILTERING
-       struct net_bridge_vlan_group    *vlgrp;
+       struct net_bridge_vlan_group    __rcu *vlgrp;
 #endif
 };
 
@@ -337,7 +338,7 @@ struct net_bridge
        struct kobject                  *ifobj;
        u32                             auto_cnt;
 #ifdef CONFIG_BRIDGE_VLAN_FILTERING
-       struct net_bridge_vlan_group    *vlgrp;
+       struct net_bridge_vlan_group    __rcu *vlgrp;
        u8                              vlan_enabled;
        __be16                          vlan_proto;
        u16                             default_pvid;
@@ -700,13 +701,25 @@ int nbp_get_num_vlan_infos(struct net_bridge_port *p, u32 filter_mask);
 static inline struct net_bridge_vlan_group *br_vlan_group(
                                        const struct net_bridge *br)
 {
-       return br->vlgrp;
+       return rtnl_dereference(br->vlgrp);
 }
 
 static inline struct net_bridge_vlan_group *nbp_vlan_group(
                                        const struct net_bridge_port *p)
 {
-       return p->vlgrp;
+       return rtnl_dereference(p->vlgrp);
+}
+
+static inline struct net_bridge_vlan_group *br_vlan_group_rcu(
+                                       const struct net_bridge *br)
+{
+       return rcu_dereference(br->vlgrp);
+}
+
+static inline struct net_bridge_vlan_group *nbp_vlan_group_rcu(
+                                       const struct net_bridge_port *p)
+{
+       return rcu_dereference(p->vlgrp);
 }
 
 /* Since bridge now depends on 8021Q module, but the time bridge sees the
@@ -853,6 +866,19 @@ static inline struct net_bridge_vlan_group *nbp_vlan_group(
 {
        return NULL;
 }
+
+static inline struct net_bridge_vlan_group *br_vlan_group_rcu(
+                                       const struct net_bridge *br)
+{
+       return NULL;
+}
+
+static inline struct net_bridge_vlan_group *nbp_vlan_group_rcu(
+                                       const struct net_bridge_port *p)
+{
+       return NULL;
+}
+
 #endif
 
 struct nf_br_ops {

diff --git a/net/bridge/br_vlan.c b/net/bridge/br_vlan.c
index ad7e4f6b6d6b5bf01c95e59aeab2657113c386c8..ffaa6d986505c941d2b4690b976bccf66b01cb6c 100644 (file)
--- a/net/bridge/br_vlan.c
+++ b/net/bridge/br_vlan.c
@@ -54,9 +54,9 @@ static void __vlan_add_flags(struct net_bridge_vlan *v, u16 flags)
        struct net_bridge_vlan_group *vg;
 
        if (br_vlan_is_master(v))
-               vg = v->br->vlgrp;
+               vg = br_vlan_group(v->br);
        else
-               vg = v->port->vlgrp;
+               vg = nbp_vlan_group(v->port);
 
        if (flags & BRIDGE_VLAN_INFO_PVID)
                __vlan_add_pvid(vg, v->vid);
@@ -91,11 +91,16 @@ static int __vlan_vid_add(struct net_device *dev, struct net_bridge *br,
 
 static void __vlan_add_list(struct net_bridge_vlan *v)
 {
+       struct net_bridge_vlan_group *vg;
        struct list_head *headp, *hpos;
        struct net_bridge_vlan *vent;
 
-       headp = br_vlan_is_master(v) ? &v->br->vlgrp->vlan_list :
-                                      &v->port->vlgrp->vlan_list;
+       if (br_vlan_is_master(v))
+               vg = br_vlan_group(v->br);
+       else
+               vg = nbp_vlan_group(v->port);
+
+       headp = &vg->vlan_list;
        list_for_each_prev(hpos, headp) {
                vent = list_entry(hpos, struct net_bridge_vlan, vlist);
                if (v->vid < vent->vid)
@@ -137,14 +142,16 @@ static int __vlan_vid_del(struct net_device *dev, struct net_bridge *br,
  */
 static struct net_bridge_vlan *br_vlan_get_master(struct net_bridge *br, u16 vid)
 {
+       struct net_bridge_vlan_group *vg;
        struct net_bridge_vlan *masterv;
 
-       masterv = br_vlan_find(br->vlgrp, vid);
+       vg = br_vlan_group(br);
+       masterv = br_vlan_find(vg, vid);
        if (!masterv) {
                /* missing global ctx, create it now */
                if (br_vlan_add(br, vid, 0))
                        return NULL;
-               masterv = br_vlan_find(br->vlgrp, vid);
+               masterv = br_vlan_find(vg, vid);
                if (WARN_ON(!masterv))
                        return NULL;
        }
@@ -155,11 +162,14 @@ static struct net_bridge_vlan *br_vlan_get_master(struct net_bridge *br, u16 vid
 
 static void br_vlan_put_master(struct net_bridge_vlan *masterv)
 {
+       struct net_bridge_vlan_group *vg;
+
        if (!br_vlan_is_master(masterv))
                return;
 
+       vg = br_vlan_group(masterv->br);
        if (atomic_dec_and_test(&masterv->refcnt)) {
-               rhashtable_remove_fast(&masterv->br->vlgrp->vlan_hash,
+               rhashtable_remove_fast(&vg->vlan_hash,
                                       &masterv->vnode, br_vlan_rht_params);
                __vlan_del_list(masterv);
                kfree_rcu(masterv, rcu);
@@ -189,12 +199,12 @@ static int __vlan_add(struct net_bridge_vlan *v, u16 flags)
        if (br_vlan_is_master(v)) {
                br = v->br;
                dev = br->dev;
-               vg = br->vlgrp;
+               vg = br_vlan_group(br);
        } else {
                p = v->port;
                br = p->br;
                dev = p->dev;
-               vg = p->vlgrp;
+               vg = nbp_vlan_group(p);
        }
 
        if (p) {
@@ -266,10 +276,10 @@ static int __vlan_del(struct net_bridge_vlan *v)
        int err = 0;
 
        if (br_vlan_is_master(v)) {
-               vg = v->br->vlgrp;
+               vg = br_vlan_group(v->br);
        } else {
                p = v->port;
-               vg = v->port->vlgrp;
+               vg = nbp_vlan_group(v->port);
                masterv = v->brvlan;
        }
 
@@ -305,7 +315,7 @@ static void __vlan_flush(struct net_bridge_vlan_group *vlgrp)
        list_for_each_entry_safe(vlan, tmp, &vlgrp->vlan_list, vlist)
                __vlan_del(vlan);
        rhashtable_destroy(&vlgrp->vlan_hash);
-       kfree(vlgrp);
+       kfree_rcu(vlgrp, rcu);
 }
 
 struct sk_buff *br_handle_vlan(struct net_bridge *br,
@@ -467,7 +477,7 @@ bool br_should_learn(struct net_bridge_port *p, struct sk_buff *skb, u16 *vid)
        if (!br->vlan_enabled)
                return true;
 
-       vg = p->vlgrp;
+       vg = nbp_vlan_group(p);
        if (!vg || !vg->num_vlans)
                return false;
 
@@ -493,12 +503,14 @@ bool br_should_learn(struct net_bridge_port *p, struct sk_buff *skb, u16 *vid)
  */
 int br_vlan_add(struct net_bridge *br, u16 vid, u16 flags)
 {
+       struct net_bridge_vlan_group *vg;
        struct net_bridge_vlan *vlan;
        int ret;
 
        ASSERT_RTNL();
 
-       vlan = br_vlan_find(br->vlgrp, vid);
+       vg = br_vlan_group(br);
+       vlan = br_vlan_find(vg, vid);
        if (vlan) {
                if (!br_vlan_is_brentry(vlan)) {
                        /* Trying to change flags of non-existent bridge vlan */
@@ -513,7 +525,7 @@ int br_vlan_add(struct net_bridge *br, u16 vid, u16 flags)
                        }
                        atomic_inc(&vlan->refcnt);
                        vlan->flags |= BRIDGE_VLAN_INFO_BRENTRY;
-                       br->vlgrp->num_vlans++;
+                       vg->num_vlans++;
                }
                __vlan_add_flags(vlan, flags);
                return 0;
@@ -541,11 +553,13 @@ int br_vlan_add(struct net_bridge *br, u16 vid, u16 flags)
  */
 int br_vlan_delete(struct net_bridge *br, u16 vid)
 {
+       struct net_bridge_vlan_group *vg;
        struct net_bridge_vlan *v;
 
        ASSERT_RTNL();
 
-       v = br_vlan_find(br->vlgrp, vid);
+       vg = br_vlan_group(br);
+       v = br_vlan_find(vg, vid);
        if (!v || !br_vlan_is_brentry(v))
                return -ENOENT;
 
@@ -626,6 +640,7 @@ int __br_vlan_set_proto(struct net_bridge *br, __be16 proto)
        int err = 0;
        struct net_bridge_port *p;
        struct net_bridge_vlan *vlan;
+       struct net_bridge_vlan_group *vg;
        __be16 oldproto;
 
        if (br->vlan_proto == proto)
@@ -633,7 +648,8 @@ int __br_vlan_set_proto(struct net_bridge *br, __be16 proto)
 
        /* Add VLANs for the new proto to the device filter. */
        list_for_each_entry(p, &br->port_list, list) {
-               list_for_each_entry(vlan, &p->vlgrp->vlan_list, vlist) {
+               vg = nbp_vlan_group(p);
+               list_for_each_entry(vlan, &vg->vlan_list, vlist) {
                        err = vlan_vid_add(p->dev, proto, vlan->vid);
                        if (err)
                                goto err_filt;
@@ -647,19 +663,23 @@ int __br_vlan_set_proto(struct net_bridge *br, __be16 proto)
        br_recalculate_fwd_mask(br);
 
        /* Delete VLANs for the old proto from the device filter. */
-       list_for_each_entry(p, &br->port_list, list)
-               list_for_each_entry(vlan, &p->vlgrp->vlan_list, vlist)
+       list_for_each_entry(p, &br->port_list, list) {
+               vg = nbp_vlan_group(p);
+               list_for_each_entry(vlan, &vg->vlan_list, vlist)
                        vlan_vid_del(p->dev, oldproto, vlan->vid);
+       }
 
        return 0;
 
 err_filt:
-       list_for_each_entry_continue_reverse(vlan, &p->vlgrp->vlan_list, vlist)
+       list_for_each_entry_continue_reverse(vlan, &vg->vlan_list, vlist)
                vlan_vid_del(p->dev, proto, vlan->vid);
 
-       list_for_each_entry_continue_reverse(p, &br->port_list, list)
-               list_for_each_entry(vlan, &p->vlgrp->vlan_list, vlist)
+       list_for_each_entry_continue_reverse(p, &br->port_list, list) {
+               vg = nbp_vlan_group(p);
+               list_for_each_entry(vlan, &vg->vlan_list, vlist)
                        vlan_vid_del(p->dev, proto, vlan->vid);
+       }
 
        return err;
 }
@@ -703,11 +723,11 @@ static void br_vlan_disable_default_pvid(struct net_bridge *br)
        /* Disable default_pvid on all ports where it is still
         * configured.
         */
-       if (vlan_default_pvid(br->vlgrp, pvid))
+       if (vlan_default_pvid(br_vlan_group(br), pvid))
                br_vlan_delete(br, pvid);
 
        list_for_each_entry(p, &br->port_list, list) {
-               if (vlan_default_pvid(p->vlgrp, pvid))
+               if (vlan_default_pvid(nbp_vlan_group(p), pvid))
                        nbp_vlan_delete(p, pvid);
        }
 
@@ -717,6 +737,7 @@ static void br_vlan_disable_default_pvid(struct net_bridge *br)
 int __br_vlan_set_default_pvid(struct net_bridge *br, u16 pvid)
 {
        const struct net_bridge_vlan *pvent;
+       struct net_bridge_vlan_group *vg;
        struct net_bridge_port *p;
        u16 old_pvid;
        int err = 0;
@@ -737,8 +758,9 @@ int __br_vlan_set_default_pvid(struct net_bridge *br, u16 pvid)
        /* Update default_pvid config only if we do not conflict with
         * user configuration.
         */
-       pvent = br_vlan_find(br->vlgrp, pvid);
-       if ((!old_pvid || vlan_default_pvid(br->vlgrp, old_pvid)) &&
+       vg = br_vlan_group(br);
+       pvent = br_vlan_find(vg, pvid);
+       if ((!old_pvid || vlan_default_pvid(vg, old_pvid)) &&
            (!pvent || !br_vlan_should_use(pvent))) {
                err = br_vlan_add(br, pvid,
                                  BRIDGE_VLAN_INFO_PVID |
@@ -754,9 +776,10 @@ int __br_vlan_set_default_pvid(struct net_bridge *br, u16 pvid)
                /* Update default_pvid config only if we do not conflict with
                 * user configuration.
                 */
+               vg = nbp_vlan_group(p);
                if ((old_pvid &&
-                    !vlan_default_pvid(p->vlgrp, old_pvid)) ||
-                   br_vlan_find(p->vlgrp, pvid))
+                    !vlan_default_pvid(vg, old_pvid)) ||
+                   br_vlan_find(vg, pvid))
                        continue;
 
                err = nbp_vlan_add(p, pvid,
@@ -825,17 +848,19 @@ unlock:
 
 int br_vlan_init(struct net_bridge *br)
 {
+       struct net_bridge_vlan_group *vg;
        int ret = -ENOMEM;
 
-       br->vlgrp = kzalloc(sizeof(struct net_bridge_vlan_group), GFP_KERNEL);
-       if (!br->vlgrp)
+       vg = kzalloc(sizeof(*vg), GFP_KERNEL);
+       if (!vg)
                goto out;
-       ret = rhashtable_init(&br->vlgrp->vlan_hash, &br_vlan_rht_params);
+       ret = rhashtable_init(&vg->vlan_hash, &br_vlan_rht_params);
        if (ret)
                goto err_rhtbl;
-       INIT_LIST_HEAD(&br->vlgrp->vlan_list);
+       INIT_LIST_HEAD(&vg->vlan_list);
        br->vlan_proto = htons(ETH_P_8021Q);
        br->default_pvid = 1;
+       rcu_assign_pointer(br->vlgrp, vg);
        ret = br_vlan_add(br, 1,
                          BRIDGE_VLAN_INFO_PVID | BRIDGE_VLAN_INFO_UNTAGGED |
                          BRIDGE_VLAN_INFO_BRENTRY);
@@ -846,9 +871,9 @@ out:
        return ret;
 
 err_vlan_add:
-       rhashtable_destroy(&br->vlgrp->vlan_hash);
+       rhashtable_destroy(&vg->vlan_hash);
 err_rhtbl:
-       kfree(br->vlgrp);
+       kfree(vg);
 
        goto out;
 }
@@ -866,9 +891,7 @@ int nbp_vlan_init(struct net_bridge_port *p)
        if (ret)
                goto err_rhtbl;
        INIT_LIST_HEAD(&vg->vlan_list);
-       /* Make sure everything's committed before publishing vg */
-       smp_wmb();
-       p->vlgrp = vg;
+       rcu_assign_pointer(p->vlgrp, vg);
        if (p->br->default_pvid) {
                ret = nbp_vlan_add(p, p->br->default_pvid,
                                   BRIDGE_VLAN_INFO_PVID |
@@ -897,7 +920,7 @@ int nbp_vlan_add(struct net_bridge_port *port, u16 vid, u16 flags)
 
        ASSERT_RTNL();
 
-       vlan = br_vlan_find(port->vlgrp, vid);
+       vlan = br_vlan_find(nbp_vlan_group(port), vid);
        if (vlan) {
                __vlan_add_flags(vlan, flags);
                return 0;
@@ -925,7 +948,7 @@ int nbp_vlan_delete(struct net_bridge_port *port, u16 vid)
 
        ASSERT_RTNL();
 
-       v = br_vlan_find(port->vlgrp, vid);
+       v = br_vlan_find(nbp_vlan_group(port), vid);
        if (!v)
                return -ENOENT;
        br_fdb_find_delete_local(port->br, port, port->dev->dev_addr, vid);
@@ -936,12 +959,14 @@ int nbp_vlan_delete(struct net_bridge_port *port, u16 vid)
 
 void nbp_vlan_flush(struct net_bridge_port *port)
 {
+       struct net_bridge_vlan_group *vg;
        struct net_bridge_vlan *vlan;
 
        ASSERT_RTNL();
 
-       list_for_each_entry(vlan, &port->vlgrp->vlan_list, vlist)
+       vg = nbp_vlan_group(port);
+       list_for_each_entry(vlan, &vg->vlan_list, vlist)
                vlan_vid_del(port->dev, port->br->vlan_proto, vlan->vid);
 
-       __vlan_flush(nbp_vlan_group(port));
+       __vlan_flush(vg);
 }