rtlwifi: rtl8192se: Fix Smatch warning

[cascardo/linux.git] / net / ipv4 / ip_input.c

diff --git a/net/ipv4/ip_input.c b/net/ipv4/ip_input.c
index d77eb0c..e3d7827 100644 (file)
--- a/net/ipv4/ip_input.c
+++ b/net/ipv4/ip_input.c
@@ -308,15 +308,12 @@ drop:
        return true;
 }
 
-int sysctl_ip_early_demux __read_mostly = 1;
-EXPORT_SYMBOL(sysctl_ip_early_demux);
-
 static int ip_rcv_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
 {
        const struct iphdr *iph = ip_hdr(skb);
        struct rtable *rt;
 
-       if (sysctl_ip_early_demux &&
+       if (net->ipv4.sysctl_ip_early_demux &&
            !skb_dst(skb) &&
            !skb->sk &&
            !ip_is_fragment(iph)) {
@@ -362,8 +359,31 @@ static int ip_rcv_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
        rt = skb_rtable(skb);
        if (rt->rt_type == RTN_MULTICAST) {
                IP_UPD_PO_STATS_BH(net, IPSTATS_MIB_INMCAST, skb->len);
-       } else if (rt->rt_type == RTN_BROADCAST)
+       } else if (rt->rt_type == RTN_BROADCAST) {
                IP_UPD_PO_STATS_BH(net, IPSTATS_MIB_INBCAST, skb->len);
+       } else if (skb->pkt_type == PACKET_BROADCAST ||
+                  skb->pkt_type == PACKET_MULTICAST) {
+               struct in_device *in_dev = __in_dev_get_rcu(skb->dev);
+
+               /* RFC 1122 3.3.6:
+                *
+                *   When a host sends a datagram to a link-layer broadcast
+                *   address, the IP destination address MUST be a legal IP
+                *   broadcast or IP multicast address.
+                *
+                *   A host SHOULD silently discard a datagram that is received
+                *   via a link-layer broadcast (see Section 2.4) but does not
+                *   specify an IP multicast or broadcast destination address.
+                *
+                * This doesn't explicitly say L2 *broadcast*, but broadcast is
+                * in a way a form of multicast and the most common use case for
+                * this is 802.11 protecting against cross-station spoofing (the
+                * so-called "hole-196" attack) so do it for both.
+                */
+               if (in_dev &&
+                   IN_DEV_ORCONF(in_dev, DROP_UNICAST_IN_L2_MULTICAST))
+                       goto drop;
+       }
 
        return dst_input(skb);