Revert "tcp/udp: Make early_demux back namespacified."

This reverts commit 7162f05f1f which is
commit 11052589cf5c0bab3b4884d423d5f60c38fcf25d upstream.

It is breaks the abi and is not needed in Android systems, so revert it.

Bug: 161946584
Change-Id: I357d52cd6a635050f305127246f95cb2302633be
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>

include/net/protocol.h

@@ -39,6 +39,8 @@
 
 /* This is used to register protocols. */
 struct net_protocol {
+	int			(*early_demux)(struct sk_buff *skb);
+	int			(*early_demux_handler)(struct sk_buff *skb);
 	int			(*handler)(struct sk_buff *skb);
 	void			(*err_handler)(struct sk_buff *skb, u32 info);
 	unsigned int		no_policy:1,
@@ -52,6 +54,8 @@ struct net_protocol {
 
 #if IS_ENABLED(CONFIG_IPV6)
 struct inet6_protocol {
+	void	(*early_demux)(struct sk_buff *skb);
+	void    (*early_demux_handler)(struct sk_buff *skb);
 	int	(*handler)(struct sk_buff *skb);
 
 	void	(*err_handler)(struct sk_buff *skb,

include/net/tcp.h

@@ -901,8 +901,6 @@ static inline int tcp_v6_sdif(const struct sk_buff *skb)
 #endif
 	return 0;
 }
-
-void tcp_v6_early_demux(struct sk_buff *skb);
 #endif
 
 static inline bool inet_exact_dif_match(struct net *net, struct sk_buff *skb)

include/net/udp.h

@@ -173,7 +173,6 @@ typedef struct sock *(*udp_lookup_t)(struct sk_buff *skb, __be16 sport,
 struct sk_buff *udp_gro_receive(struct list_head *head, struct sk_buff *skb,
 				struct udphdr *uh, udp_lookup_t lookup);
 int udp_gro_complete(struct sk_buff *skb, int nhoff, udp_lookup_t lookup);
-void udp_v6_early_demux(struct sk_buff *skb);
 
 struct sk_buff *__udp_gso_segment(struct sk_buff *gso_skb,
 				  netdev_features_t features);

net/ipv4/af_inet.c

@@ -1678,7 +1678,12 @@ static const struct net_protocol igmp_protocol = {
 };
 #endif
 
-static const struct net_protocol tcp_protocol = {
+/* thinking of making this const? Don't.
+ * early_demux can change based on sysctl.
+ */
+static struct net_protocol tcp_protocol = {
+	.early_demux	=	tcp_v4_early_demux,
+	.early_demux_handler =  tcp_v4_early_demux,
 	.handler	=	tcp_v4_rcv,
 	.err_handler	=	tcp_v4_err,
 	.no_policy	=	1,
@@ -1686,7 +1691,12 @@ static const struct net_protocol tcp_protocol = {
 	.icmp_strict_tag_validation = 1,
 };
 
-static const struct net_protocol udp_protocol = {
+/* thinking of making this const? Don't.
+ * early_demux can change based on sysctl.
+ */
+static struct net_protocol udp_protocol = {
+	.early_demux =	udp_v4_early_demux,
+	.early_demux_handler =	udp_v4_early_demux,
 	.handler =	udp_rcv,
 	.err_handler =	udp_err,
 	.no_policy =	1,

net/ipv4/ip_input.c

@@ -306,38 +306,28 @@ static inline bool ip_rcv_options(struct sk_buff *skb, struct net_device *dev)
 	return true;
 }
 
-int udp_v4_early_demux(struct sk_buff *);
-int tcp_v4_early_demux(struct sk_buff *);
 static int ip_rcv_finish_core(struct net *net, struct sock *sk,
 			      struct sk_buff *skb, struct net_device *dev)
 {
 	const struct iphdr *iph = ip_hdr(skb);
+	int (*edemux)(struct sk_buff *skb);
 	struct rtable *rt;
 	int err;
 
-	if (READ_ONCE(net->ipv4.sysctl_ip_early_demux) &&
+	if (net->ipv4.sysctl_ip_early_demux &&
 	    !skb_dst(skb) &&
 	    !skb->sk &&
 	    !ip_is_fragment(iph)) {
-		switch (iph->protocol) {
+		const struct net_protocol *ipprot;
-		case IPPROTO_TCP:
+		int protocol = iph->protocol;
-			if (READ_ONCE(net->ipv4.sysctl_tcp_early_demux)) {
-				tcp_v4_early_demux(skb);
 
-				/* must reload iph, skb->head might have changed */
+		ipprot = rcu_dereference(inet_protos[protocol]);
-				iph = ip_hdr(skb);
+		if (ipprot && (edemux = READ_ONCE(ipprot->early_demux))) {
-			}
+			err = edemux(skb);
-			break;
+			if (unlikely(err))
-		case IPPROTO_UDP:
+				goto drop_error;
-			if (READ_ONCE(net->ipv4.sysctl_udp_early_demux)) {
+			/* must reload iph, skb->head might have changed */
-				err = udp_v4_early_demux(skb);
+			iph = ip_hdr(skb);
-				if (unlikely(err))
-					goto drop_error;
-
-				/* must reload iph, skb->head might have changed */
-				iph = ip_hdr(skb);
-			}
-			break;
 		}
 	}
 

net/ipv4/sysctl_net_ipv4.c

@@ -332,6 +332,61 @@ static int proc_tcp_fastopen_key(struct ctl_table *table, int write,
 	return ret;
 }
 
+static void proc_configure_early_demux(int enabled, int protocol)
+{
+	struct net_protocol *ipprot;
+#if IS_ENABLED(CONFIG_IPV6)
+	struct inet6_protocol *ip6prot;
+#endif
+
+	rcu_read_lock();
+
+	ipprot = rcu_dereference(inet_protos[protocol]);
+	if (ipprot)
+		ipprot->early_demux = enabled ? ipprot->early_demux_handler :
+						NULL;
+
+#if IS_ENABLED(CONFIG_IPV6)
+	ip6prot = rcu_dereference(inet6_protos[protocol]);
+	if (ip6prot)
+		ip6prot->early_demux = enabled ? ip6prot->early_demux_handler :
+						 NULL;
+#endif
+	rcu_read_unlock();
+}
+
+static int proc_tcp_early_demux(struct ctl_table *table, int write,
+				void __user *buffer, size_t *lenp, loff_t *ppos)
+{
+	int ret = 0;
+
+	ret = proc_dointvec(table, write, buffer, lenp, ppos);
+
+	if (write && !ret) {
+		int enabled = init_net.ipv4.sysctl_tcp_early_demux;
+
+		proc_configure_early_demux(enabled, IPPROTO_TCP);
+	}
+
+	return ret;
+}
+
+static int proc_udp_early_demux(struct ctl_table *table, int write,
+				void __user *buffer, size_t *lenp, loff_t *ppos)
+{
+	int ret = 0;
+
+	ret = proc_dointvec(table, write, buffer, lenp, ppos);
+
+	if (write && !ret) {
+		int enabled = init_net.ipv4.sysctl_udp_early_demux;
+
+		proc_configure_early_demux(enabled, IPPROTO_UDP);
+	}
+
+	return ret;
+}
+
 static int proc_tfo_blackhole_detect_timeout(struct ctl_table *table,
 					     int write,
 					     void __user *buffer,
@@ -583,14 +638,14 @@ static struct ctl_table ipv4_net_table[] = {
 		.data           = &init_net.ipv4.sysctl_udp_early_demux,
 		.maxlen         = sizeof(int),
 		.mode           = 0644,
-		.proc_handler   = proc_douintvec_minmax,
+		.proc_handler   = proc_udp_early_demux
 	},
 	{
 		.procname       = "tcp_early_demux",
 		.data           = &init_net.ipv4.sysctl_tcp_early_demux,
 		.maxlen         = sizeof(int),
 		.mode           = 0644,
-		.proc_handler   = proc_douintvec_minmax,
+		.proc_handler   = proc_tcp_early_demux
 	},
 	{
 		.procname	= "ip_default_ttl",

net/ipv6/ip6_input.c

@@ -47,25 +47,18 @@
 #include <net/inet_ecn.h>
 #include <net/dst_metadata.h>
 
-void udp_v6_early_demux(struct sk_buff *);
-void tcp_v6_early_demux(struct sk_buff *);
 static void ip6_rcv_finish_core(struct net *net, struct sock *sk,
 				struct sk_buff *skb)
 {
-	if (READ_ONCE(net->ipv4.sysctl_ip_early_demux) &&
+	void (*edemux)(struct sk_buff *skb);
-	    !skb_dst(skb) && !skb->sk) {
-		switch (ipv6_hdr(skb)->nexthdr) {
-		case IPPROTO_TCP:
-			if (READ_ONCE(net->ipv4.sysctl_tcp_early_demux))
-				tcp_v6_early_demux(skb);
-			break;
-		case IPPROTO_UDP:
-			if (READ_ONCE(net->ipv4.sysctl_udp_early_demux))
-				udp_v6_early_demux(skb);
-			break;
-		}
-	}
 
+	if (net->ipv4.sysctl_ip_early_demux && !skb_dst(skb) && skb->sk == NULL) {
+		const struct inet6_protocol *ipprot;
+
+		ipprot = rcu_dereference(inet6_protos[ipv6_hdr(skb)->nexthdr]);
+		if (ipprot && (edemux = READ_ONCE(ipprot->early_demux)))
+			edemux(skb);
+	}
 	if (!skb_valid_dst(skb))
 		ip6_route_input(skb);
 }

net/ipv6/tcp_ipv6.c

@@ -1673,7 +1673,7 @@ static int tcp_v6_rcv(struct sk_buff *skb)
 	goto discard_it;
 }
 
-void tcp_v6_early_demux(struct sk_buff *skb)
+static void tcp_v6_early_demux(struct sk_buff *skb)
 {
 	const struct ipv6hdr *hdr;
 	const struct tcphdr *th;
@@ -2028,7 +2028,12 @@ struct proto tcpv6_prot = {
 	.diag_destroy		= tcp_abort,
 };
 
-static const struct inet6_protocol tcpv6_protocol = {
+/* thinking of making this const? Don't.
+ * early_demux can change based on sysctl.
+ */
+static struct inet6_protocol tcpv6_protocol = {
+	.early_demux	=	tcp_v6_early_demux,
+	.early_demux_handler =  tcp_v6_early_demux,
 	.handler	=	tcp_v6_rcv,
 	.err_handler	=	tcp_v6_err,
 	.flags		=	INET6_PROTO_NOPOLICY|INET6_PROTO_FINAL,

net/ipv6/udp.c

@@ -912,7 +912,7 @@ static struct sock *__udp6_lib_demux_lookup(struct net *net,
 	return NULL;
 }
 
-void udp_v6_early_demux(struct sk_buff *skb)
+static void udp_v6_early_demux(struct sk_buff *skb)
 {
 	struct net *net = dev_net(skb->dev);
 	const struct udphdr *uh;
@@ -1533,7 +1533,12 @@ int compat_udpv6_getsockopt(struct sock *sk, int level, int optname,
 }
 #endif
 
-static const struct inet6_protocol udpv6_protocol = {
+/* thinking of making this const? Don't.
+ * early_demux can change based on sysctl.
+ */
+static struct inet6_protocol udpv6_protocol = {
+	.early_demux	=	udp_v6_early_demux,
+	.early_demux_handler =  udp_v6_early_demux,
 	.handler	=	udpv6_rcv,
 	.err_handler	=	udpv6_err,
 	.flags		=	INET6_PROTO_NOPOLICY|INET6_PROTO_FINAL,