bridge: reduce size of input cb to 16 bytes

Reduce size of br_input_skb_cb from 24 to 16 bytes by
using bitfield for those values that can only be 0 or 1.

igmp is the igmp type value, so it needs to be at least u8.

Furthermore, the bridge currently relies on step-by-step initialization
of br_input_skb_cb fields as the skb passes through the stack.

Explicitly zero out the bridge input cb instead, this avoids having to
review/validate that no BR_INPUT_SKB_CB(skb)->foo test can see a
'random' value from previous protocol cb.

AFAICS all current fields are always set up before they are read again,
so this is not a bug fix.

Signed-off-by: Florian Westphal <fw@strlen.de>
Acked-by: David S. Miller <davem@davemloft.net>
Acked-by: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

3 files changed, 16 insertions, 16 deletions

diff --git a/net/bridge/br_arp_nd_proxy.c b/net/bridge/br_arp_nd_proxy.c
index 724b474ade54..15116752365a 100644
--- a/net/bridge/br_arp_nd_proxy.c
+++ b/net/bridge/br_arp_nd_proxy.c
@@ -131,7 +131,7 @@ void br_do_proxy_suppress_arp(struct sk_buff *skb, struct net_bridge *br,
         u8 *arpptr, *sha;
         __be32 sip, tip;
 
-        BR_INPUT_SKB_CB(skb)->proxyarp_replied = false;
+        BR_INPUT_SKB_CB(skb)->proxyarp_replied = 0;
 
         if ((dev->flags & IFF_NOARP) ||
             !pskb_may_pull(skb, arp_hdr_len(dev)))
@@ -161,7 +161,7 @@ void br_do_proxy_suppress_arp(struct sk_buff *skb, struct net_bridge *br,
                         return;
                 if (ipv4_is_zeronet(sip) || sip == tip) {
                         /* prevent flooding to neigh suppress ports */
-                        BR_INPUT_SKB_CB(skb)->proxyarp_replied = true;
+                        BR_INPUT_SKB_CB(skb)->proxyarp_replied = 1;
                         return;
                 }
         }
@@ -181,7 +181,7 @@ void br_do_proxy_suppress_arp(struct sk_buff *skb, struct net_bridge *br,
                 /* its our local ip, so don't proxy reply
                  * and don't forward to neigh suppress ports
                  */
-                BR_INPUT_SKB_CB(skb)->proxyarp_replied = true;
+                BR_INPUT_SKB_CB(skb)->proxyarp_replied = 1;
                 return;
         }
 
@@ -217,7 +217,7 @@ void br_do_proxy_suppress_arp(struct sk_buff *skb, struct net_bridge *br,
                          */
                         if (replied ||
                             br_opt_get(br, BROPT_NEIGH_SUPPRESS_ENABLED))
-                                BR_INPUT_SKB_CB(skb)->proxyarp_replied = true;
+                                BR_INPUT_SKB_CB(skb)->proxyarp_replied = 1;
                 }
 
                 neigh_release(n);
@@ -393,7 +393,7 @@ void br_do_suppress_nd(struct sk_buff *skb, struct net_bridge *br,
         struct ipv6hdr *iphdr;
         struct neighbour *n;
 
-        BR_INPUT_SKB_CB(skb)->proxyarp_replied = false;
+        BR_INPUT_SKB_CB(skb)->proxyarp_replied = 0;
 
         if (p && (p->flags & BR_NEIGH_SUPPRESS))
                 return;
@@ -401,7 +401,7 @@ void br_do_suppress_nd(struct sk_buff *skb, struct net_bridge *br,
         if (msg->icmph.icmp6_type == NDISC_NEIGHBOUR_ADVERTISEMENT &&
             !msg->icmph.icmp6_solicited) {
                 /* prevent flooding to neigh suppress ports */
-                BR_INPUT_SKB_CB(skb)->proxyarp_replied = true;
+                BR_INPUT_SKB_CB(skb)->proxyarp_replied = 1;
                 return;
         }
 
@@ -414,7 +414,7 @@ void br_do_suppress_nd(struct sk_buff *skb, struct net_bridge *br,
 
         if (ipv6_addr_any(saddr) || !ipv6_addr_cmp(saddr, daddr)) {
                 /* prevent flooding to neigh suppress ports */
-                BR_INPUT_SKB_CB(skb)->proxyarp_replied = true;
+                BR_INPUT_SKB_CB(skb)->proxyarp_replied = 1;
                 return;
         }
 
@@ -432,7 +432,7 @@ void br_do_suppress_nd(struct sk_buff *skb, struct net_bridge *br,
                 /* its our own ip, so don't proxy reply
                  * and don't forward to arp suppress ports
                  */
-                BR_INPUT_SKB_CB(skb)->proxyarp_replied = true;
+                BR_INPUT_SKB_CB(skb)->proxyarp_replied = 1;
                 return;
         }
 
@@ -465,7 +465,7 @@ void br_do_suppress_nd(struct sk_buff *skb, struct net_bridge *br,
                          */
                         if (replied ||
                             br_opt_get(br, BROPT_NEIGH_SUPPRESS_ENABLED))
-                                BR_INPUT_SKB_CB(skb)->proxyarp_replied = true;
+                                BR_INPUT_SKB_CB(skb)->proxyarp_replied = 1;
                 }
                 neigh_release(n);
         }
diff --git a/net/bridge/br_input.c b/net/bridge/br_input.c
index 5ea7e56119c1..e2f93e5c72da 100644
--- a/net/bridge/br_input.c
+++ b/net/bridge/br_input.c
@@ -227,6 +227,8 @@ rx_handler_result_t br_handle_frame(struct sk_buff **pskb)
         if (!skb)
                 return RX_HANDLER_CONSUMED;
 
+        memset(skb->cb, 0, sizeof(struct br_input_skb_cb));
+
         p = br_port_get_rcu(skb->dev);
         if (p->flags & BR_VLAN_TUNNEL) {
                 if (br_handle_ingress_vlan_tunnel(skb, p,
diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h
index 7946aa3b6e09..e7110a6e2b7e 100644
--- a/net/bridge/br_private.h
+++ b/net/bridge/br_private.h
@@ -425,15 +425,13 @@ struct br_input_skb_cb {
         struct net_device *brdev;
 
 #ifdef CONFIG_BRIDGE_IGMP_SNOOPING
-        int igmp;
-        int mrouters_only;
+        u8 igmp;
+        u8 mrouters_only:1;
 #endif
-
-        bool proxyarp_replied;
-        bool src_port_isolated;
-
+        u8 proxyarp_replied:1;
+        u8 src_port_isolated:1;
 #ifdef CONFIG_BRIDGE_VLAN_FILTERING
-        bool vlan_filtered;
+        u8 vlan_filtered:1;
 #endif
 
 #ifdef CONFIG_NET_SWITCHDEV