xfrm: state: remove extract_input indirection from xfrm_state_afinfo

In order to keep CONFIG_IPV6=m working, xfrm6_extract_header needs to be
duplicated.  It will be removed again in a followup change when the
remaining caller is moved to net/xfrm as well.
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>

include/net/xfrm.h

@@ -362,8 +362,6 @@ struct xfrm_state_afinfo {
 
 	int			(*output)(struct net *net, struct sock *sk, struct sk_buff *skb);
 	int			(*output_finish)(struct sock *sk, struct sk_buff *skb);
-	int			(*extract_input)(struct xfrm_state *x,
-						 struct sk_buff *skb);
 	int			(*extract_output)(struct xfrm_state *x,
 						  struct sk_buff *skb);
 	int			(*transport_finish)(struct sk_buff *skb,
@@ -1587,7 +1585,6 @@ int xfrm4_protocol_deregister(struct xfrm4_protocol *handler, unsigned char prot
 int xfrm4_tunnel_register(struct xfrm_tunnel *handler, unsigned short family);
 int xfrm4_tunnel_deregister(struct xfrm_tunnel *handler, unsigned short family);
 void xfrm4_local_error(struct sk_buff *skb, u32 mtu);
-int xfrm6_extract_header(struct sk_buff *skb);
 int xfrm6_extract_input(struct xfrm_state *x, struct sk_buff *skb);
 int xfrm6_rcv_spi(struct sk_buff *skb, int nexthdr, __be32 spi,
 		  struct ip6_tnl *t);

net/ipv4/xfrm4_input.c

@@ -18,11 +18,6 @@
 #include <net/ip.h>
 #include <net/xfrm.h>
 
-int xfrm4_extract_input(struct xfrm_state *x, struct sk_buff *skb)
-{
-	return xfrm4_extract_header(skb);
-}
-
 static int xfrm4_rcv_encap_finish2(struct net *net, struct sock *sk,
 				   struct sk_buff *skb)
 {

net/ipv4/xfrm4_state.c

@@ -36,7 +36,6 @@ static struct xfrm_state_afinfo xfrm4_state_afinfo = {
 	.proto			= IPPROTO_IPIP,
 	.output			= xfrm4_output,
 	.output_finish		= xfrm4_output_finish,
-	.extract_input		= xfrm4_extract_input,
 	.transport_finish	= xfrm4_transport_finish,
 	.local_error		= xfrm4_local_error,
 };

net/ipv6/xfrm6_input.c

@@ -17,11 +17,6 @@
 #include <net/ipv6.h>
 #include <net/xfrm.h>
 
-int xfrm6_extract_input(struct xfrm_state *x, struct sk_buff *skb)
-{
-	return xfrm6_extract_header(skb);
-}
-
 int xfrm6_rcv_spi(struct sk_buff *skb, int nexthdr, __be32 spi,
 		  struct ip6_tnl *t)
 {

net/ipv6/xfrm6_output.c

@@ -94,6 +94,20 @@ static int xfrm6_tunnel_check_size(struct sk_buff *skb)
 	return ret;
 }
 
+static void __xfrm6_extract_header(struct sk_buff *skb)
+{
+	struct ipv6hdr *iph = ipv6_hdr(skb);
+
+	XFRM_MODE_SKB_CB(skb)->ihl = sizeof(*iph);
+	XFRM_MODE_SKB_CB(skb)->id = 0;
+	XFRM_MODE_SKB_CB(skb)->frag_off = htons(IP_DF);
+	XFRM_MODE_SKB_CB(skb)->tos = ipv6_get_dsfield(iph);
+	XFRM_MODE_SKB_CB(skb)->ttl = iph->hop_limit;
+	XFRM_MODE_SKB_CB(skb)->optlen = 0;
+	memcpy(XFRM_MODE_SKB_CB(skb)->flow_lbl, iph->flow_lbl,
+	       sizeof(XFRM_MODE_SKB_CB(skb)->flow_lbl));
+}
+
 int xfrm6_extract_output(struct xfrm_state *x, struct sk_buff *skb)
 {
 	int err;
@@ -104,7 +118,8 @@ int xfrm6_extract_output(struct xfrm_state *x, struct sk_buff *skb)
 
 	XFRM_MODE_SKB_CB(skb)->protocol = ipv6_hdr(skb)->nexthdr;
 
-	return xfrm6_extract_header(skb);
+	__xfrm6_extract_header(skb);
+	return 0;
 }
 
 int xfrm6_output_finish(struct sock *sk, struct sk_buff *skb)

net/ipv6/xfrm6_state.c

@@ -13,36 +13,12 @@
  */
 
 #include <net/xfrm.h>
-#include <linux/pfkeyv2.h>
-#include <linux/ipsec.h>
-#include <linux/netfilter_ipv6.h>
-#include <linux/export.h>
-#include <net/dsfield.h>
-#include <net/ipv6.h>
-#include <net/addrconf.h>
-
-int xfrm6_extract_header(struct sk_buff *skb)
-{
-	struct ipv6hdr *iph = ipv6_hdr(skb);
-
-	XFRM_MODE_SKB_CB(skb)->ihl = sizeof(*iph);
-	XFRM_MODE_SKB_CB(skb)->id = 0;
-	XFRM_MODE_SKB_CB(skb)->frag_off = htons(IP_DF);
-	XFRM_MODE_SKB_CB(skb)->tos = ipv6_get_dsfield(iph);
-	XFRM_MODE_SKB_CB(skb)->ttl = iph->hop_limit;
-	XFRM_MODE_SKB_CB(skb)->optlen = 0;
-	memcpy(XFRM_MODE_SKB_CB(skb)->flow_lbl, iph->flow_lbl,
-	       sizeof(XFRM_MODE_SKB_CB(skb)->flow_lbl));
-
-	return 0;
-}
 
 static struct xfrm_state_afinfo xfrm6_state_afinfo = {
 	.family			= AF_INET6,
 	.proto			= IPPROTO_IPV6,
 	.output			= xfrm6_output,
 	.output_finish		= xfrm6_output_finish,
-	.extract_input		= xfrm6_extract_input,
 	.extract_output		= xfrm6_extract_output,
 	.transport_finish	= xfrm6_transport_finish,
 	.local_error		= xfrm6_local_error,

net/xfrm/xfrm_inout.h

@@ -6,6 +6,24 @@
 #ifndef XFRM_INOUT_H
 #define XFRM_INOUT_H 1
 
+static inline void xfrm6_extract_header(struct sk_buff *skb)
+{
+#if IS_ENABLED(CONFIG_IPV6)
+	struct ipv6hdr *iph = ipv6_hdr(skb);
+
+	XFRM_MODE_SKB_CB(skb)->ihl = sizeof(*iph);
+	XFRM_MODE_SKB_CB(skb)->id = 0;
+	XFRM_MODE_SKB_CB(skb)->frag_off = htons(IP_DF);
+	XFRM_MODE_SKB_CB(skb)->tos = ipv6_get_dsfield(iph);
+	XFRM_MODE_SKB_CB(skb)->ttl = iph->hop_limit;
+	XFRM_MODE_SKB_CB(skb)->optlen = 0;
+	memcpy(XFRM_MODE_SKB_CB(skb)->flow_lbl, iph->flow_lbl,
+	       sizeof(XFRM_MODE_SKB_CB(skb)->flow_lbl));
+#else
+	WARN_ON_ONCE(1);
+#endif
+}
+
 static inline void xfrm6_beet_make_header(struct sk_buff *skb)
 {
 	struct ipv6hdr *iph = ipv6_hdr(skb);

net/xfrm/xfrm_input.c

@@ -353,17 +353,18 @@ xfrm_inner_mode_encap_remove(struct xfrm_state *x,
 static int xfrm_prepare_input(struct xfrm_state *x, struct sk_buff *skb)
 {
 	const struct xfrm_mode *inner_mode = &x->inner_mode;
-	const struct xfrm_state_afinfo *afinfo;
-	int err = -EAFNOSUPPORT;
-
-	rcu_read_lock();
-	afinfo = xfrm_state_afinfo_get_rcu(x->outer_mode.family);
-	if (likely(afinfo))
-		err = afinfo->extract_input(x, skb);
-	rcu_read_unlock();
 
-	if (err)
-		return err;
+	switch (x->outer_mode.family) {
+	case AF_INET:
+		xfrm4_extract_header(skb);
+		break;
+	case AF_INET6:
+		xfrm6_extract_header(skb);
+		break;
+	default:
+		WARN_ON_ONCE(1);
+		return -EAFNOSUPPORT;
+	}
 
 	if (x->sel.family == AF_UNSPEC) {
 		inner_mode = xfrm_ip2inner_mode(x, XFRM_MODE_SKB_CB(skb)->protocol);