net: Make accesses to ->br_port safe for sparse RCU

The new versions of the rcu_dereference() APIs requires that any pointers
passed to one of these APIs be fully defined.  The ->br_port field
in struct net_device points to a struct net_bridge_port, which is an
incomplete type.  This commit therefore changes ->br_port to be a void*,
and introduces a br_port() helper function to convert the type to struct
net_bridge_port, and applies this new helper function where required.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: David Miller <davem@davemloft.net>
Cc: Stephen Hemminger <shemminger@linux-foundation.org>
Cc: Eric Dumazet <eric.dumazet@gmail.com>

8 files changed, 18 insertions, 10 deletions

diff --git a/include/linux/if_bridge.h b/include/linux/if_bridge.h
index 938b7e81df95..d001d782922d 100644
--- a/include/linux/if_bridge.h
+++ b/include/linux/if_bridge.h
@@ -101,6 +101,9 @@ struct __fdb_entry {
 
 #include <linux/netdevice.h>
 
+/* br_handle_frame_hook() needs the following forward declaration. */
+struct net_bridge_port;
+
 extern void brioctl_set(int (*ioctl_hook)(struct net *, unsigned int, void __user *));
 extern struct sk_buff *(*br_handle_frame_hook)(struct net_bridge_port *p,
                                                struct sk_buff *skb);
diff --git a/net/bridge/br_fdb.c b/net/bridge/br_fdb.c
index 26637439965b..845710bca49c 100644
--- a/net/bridge/br_fdb.c
+++ b/net/bridge/br_fdb.c
@@ -246,7 +246,7 @@ int br_fdb_test_addr(struct net_device *dev, unsigned char *addr)
                 return 0;
 
         rcu_read_lock();
-        fdb = __br_fdb_get(dev->br_port->br, addr);
+        fdb = __br_fdb_get(br_port(dev)->br, addr);
         ret = fdb && fdb->dst->dev != dev &&
                 fdb->dst->state == BR_STATE_FORWARDING;
         rcu_read_unlock();
diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h
index 0f4a74bc6a9b..3255188355b5 100644
--- a/net/bridge/br_private.h
+++ b/net/bridge/br_private.h
@@ -268,6 +268,11 @@ static inline int br_is_root_bridge(const struct net_bridge *br)
         return !memcmp(&br->bridge_id, &br->designated_root, 8);
 }
 
+static inline struct net_bridge_port *br_port(const struct net_device *dev)
+{
+        return rcu_dereference(dev->br_port);
+}
+
 /* br_device.c */
 extern void br_dev_setup(struct net_device *dev);
 extern netdev_tx_t br_dev_xmit(struct sk_buff *skb,
diff --git a/net/bridge/netfilter/ebt_redirect.c b/net/bridge/netfilter/ebt_redirect.c
index 9e19166ba453..a39df0ae0f81 100644
--- a/net/bridge/netfilter/ebt_redirect.c
+++ b/net/bridge/netfilter/ebt_redirect.c
@@ -25,7 +25,7 @@ ebt_redirect_tg(struct sk_buff *skb, const struct xt_action_param *par)
 
         if (par->hooknum != NF_BR_BROUTING)
                 memcpy(eth_hdr(skb)->h_dest,
-                       par->in->br_port->br->dev->dev_addr, ETH_ALEN);
+                       br_port(par->in)->br->dev->dev_addr, ETH_ALEN);
         else
                 memcpy(eth_hdr(skb)->h_dest, par->in->dev_addr, ETH_ALEN);
         skb->pkt_type = PACKET_HOST;
diff --git a/net/bridge/netfilter/ebt_ulog.c b/net/bridge/netfilter/ebt_ulog.c
index ae3c7cef1484..5a4996bbb090 100644
--- a/net/bridge/netfilter/ebt_ulog.c
+++ b/net/bridge/netfilter/ebt_ulog.c
@@ -178,7 +178,7 @@ static void ebt_ulog_packet(unsigned int hooknr, const struct sk_buff *skb,
                 strcpy(pm->physindev, in->name);
                 /* If in isn't a bridge, then physindev==indev */
                 if (in->br_port)
-                        strcpy(pm->indev, in->br_port->br->dev->name);
+                        strcpy(pm->indev, br_port(in)->br->dev->name);
                 else
                         strcpy(pm->indev, in->name);
         } else
@@ -187,7 +187,7 @@ static void ebt_ulog_packet(unsigned int hooknr, const struct sk_buff *skb,
         if (out) {
                 /* If out exists, then out is a bridge port */
                 strcpy(pm->physoutdev, out->name);
-                strcpy(pm->outdev, out->br_port->br->dev->name);
+                strcpy(pm->outdev, br_port(out)->br->dev->name);
         } else
                 pm->outdev[0] = pm->physoutdev[0] = '\0';
 
diff --git a/net/bridge/netfilter/ebtables.c b/net/bridge/netfilter/ebtables.c
index 59ca00e40dec..4c2aab8cbfc7 100644
--- a/net/bridge/netfilter/ebtables.c
+++ b/net/bridge/netfilter/ebtables.c
@@ -141,10 +141,10 @@ ebt_basic_match(const struct ebt_entry *e, const struct ethhdr *h,
         if (FWINV2(ebt_dev_check(e->out, out), EBT_IOUT))
                 return 1;
         if ((!in || !in->br_port) ? 0 : FWINV2(ebt_dev_check(
-           e->logical_in, in->br_port->br->dev), EBT_ILOGICALIN))
+           e->logical_in, br_port(in)->br->dev), EBT_ILOGICALIN))
                 return 1;
         if ((!out || !out->br_port) ? 0 : FWINV2(ebt_dev_check(
-           e->logical_out, out->br_port->br->dev), EBT_ILOGICALOUT))
+           e->logical_out, br_port(out)->br->dev), EBT_ILOGICALOUT))
                 return 1;
 
         if (e->bitmask & EBT_SOURCEMAC) {
diff --git a/net/netfilter/nfnetlink_log.c b/net/netfilter/nfnetlink_log.c
index fc9a211e629e..78957cfa3bdd 100644
--- a/net/netfilter/nfnetlink_log.c
+++ b/net/netfilter/nfnetlink_log.c
@@ -404,7 +404,7 @@ __build_packet_message(struct nfulnl_instance *inst,
                                      htonl(indev->ifindex));
                         /* this is the bridge group "brX" */
                         NLA_PUT_BE32(inst->skb, NFULA_IFINDEX_INDEV,
-                                     htonl(indev->br_port->br->dev->ifindex));
+                                     htonl(br_port(indev)->br->dev->ifindex));
                 } else {
                         /* Case 2: indev is bridge group, we need to look for
                          * physical device (when called from ipv4) */
@@ -431,7 +431,7 @@ __build_packet_message(struct nfulnl_instance *inst,
                                      htonl(outdev->ifindex));
                         /* this is the bridge group "brX" */
                         NLA_PUT_BE32(inst->skb, NFULA_IFINDEX_OUTDEV,
-                                     htonl(outdev->br_port->br->dev->ifindex));
+                                     htonl(br_port(outdev)->br->dev->ifindex));
                 } else {
                         /* Case 2: indev is a bridge group, we need to look
                          * for physical device (when called from ipv4) */
diff --git a/net/netfilter/nfnetlink_queue.c b/net/netfilter/nfnetlink_queue.c
index 12e1ab37fcd8..c3c17498298e 100644
--- a/net/netfilter/nfnetlink_queue.c
+++ b/net/netfilter/nfnetlink_queue.c
@@ -297,7 +297,7 @@ nfqnl_build_packet_message(struct nfqnl_instance *queue,
                                      htonl(indev->ifindex));
                         /* this is the bridge group "brX" */
                         NLA_PUT_BE32(skb, NFQA_IFINDEX_INDEV,
-                                     htonl(indev->br_port->br->dev->ifindex));
+                                     htonl(br_port(indev)->br->dev->ifindex));
                 } else {
                         /* Case 2: indev is bridge group, we need to look for
                          * physical device (when called from ipv4) */
@@ -322,7 +322,7 @@ nfqnl_build_packet_message(struct nfqnl_instance *queue,
                                      htonl(outdev->ifindex));
                         /* this is the bridge group "brX" */
                         NLA_PUT_BE32(skb, NFQA_IFINDEX_OUTDEV,
-                                     htonl(outdev->br_port->br->dev->ifindex));
+                                     htonl(br_port(outdev)->br->dev->ifindex));
                 } else {
                         /* Case 2: outdev is bridge group, we need to look for
                          * physical output device (when called from ipv4) */