xfrm: ipv6: move mip6_rthdr_offset into xfrm core

Place the call into the xfrm core.  After this all remaining users
set the hdr_offset function pointer to the same function which opens
the possiblity to remove the indirection.
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>

net/ipv6/mip6.c

@@ -333,53 +333,6 @@ static int mip6_rthdr_output(struct xfrm_state *x, struct sk_buff *skb)
 	return 0;
 }
 
-static int mip6_rthdr_offset(struct xfrm_state *x, struct sk_buff *skb,
-			     u8 **nexthdr)
-{
-	u16 offset = sizeof(struct ipv6hdr);
-	struct ipv6_opt_hdr *exthdr =
-				   (struct ipv6_opt_hdr *)(ipv6_hdr(skb) + 1);
-	const unsigned char *nh = skb_network_header(skb);
-	unsigned int packet_len = skb_tail_pointer(skb) -
-		skb_network_header(skb);
-	int found_rhdr = 0;
-
-	*nexthdr = &ipv6_hdr(skb)->nexthdr;
-
-	while (offset + 1 <= packet_len) {
-
-		switch (**nexthdr) {
-		case NEXTHDR_HOP:
-			break;
-		case NEXTHDR_ROUTING:
-			if (offset + 3 <= packet_len) {
-				struct ipv6_rt_hdr *rt;
-				rt = (struct ipv6_rt_hdr *)(nh + offset);
-				if (rt->type != 0)
-					return offset;
-			}
-			found_rhdr = 1;
-			break;
-		case NEXTHDR_DEST:
-			if (ipv6_find_tlv(skb, offset, IPV6_TLV_HAO) >= 0)
-				return offset;
-
-			if (found_rhdr)
-				return offset;
-
-			break;
-		default:
-			return offset;
-		}
-
-		offset += ipv6_optlen(exthdr);
-		*nexthdr = &exthdr->nexthdr;
-		exthdr = (struct ipv6_opt_hdr *)(nh + offset);
-	}
-
-	return offset;
-}
-
 static int mip6_rthdr_init_state(struct xfrm_state *x)
 {
 	if (x->id.spi) {
@@ -413,7 +366,6 @@ static const struct xfrm_type mip6_rthdr_type = {
 	.destructor	= mip6_rthdr_destroy,
 	.input		= mip6_rthdr_input,
 	.output		= mip6_rthdr_output,
-	.hdr_offset	= mip6_rthdr_offset,
 };
 
 static int __init mip6_init(void)

net/xfrm/xfrm_output.c

@@ -123,6 +123,53 @@ static int mip6_destopt_offset(struct xfrm_state *x, struct sk_buff *skb,
 
 	return offset;
 }
+
+static int mip6_rthdr_offset(struct xfrm_state *x, struct sk_buff *skb,
+			     u8 **nexthdr)
+{
+	u16 offset = sizeof(struct ipv6hdr);
+	struct ipv6_opt_hdr *exthdr =
+				   (struct ipv6_opt_hdr *)(ipv6_hdr(skb) + 1);
+	const unsigned char *nh = skb_network_header(skb);
+	unsigned int packet_len = skb_tail_pointer(skb) -
+		skb_network_header(skb);
+	int found_rhdr = 0;
+
+	*nexthdr = &ipv6_hdr(skb)->nexthdr;
+
+	while (offset + 1 <= packet_len) {
+		switch (**nexthdr) {
+		case NEXTHDR_HOP:
+			break;
+		case NEXTHDR_ROUTING:
+			if (offset + 3 <= packet_len) {
+				struct ipv6_rt_hdr *rt;
+
+				rt = (struct ipv6_rt_hdr *)(nh + offset);
+				if (rt->type != 0)
+					return offset;
+			}
+			found_rhdr = 1;
+			break;
+		case NEXTHDR_DEST:
+			if (ipv6_find_tlv(skb, offset, IPV6_TLV_HAO) >= 0)
+				return offset;
+
+			if (found_rhdr)
+				return offset;
+
+			break;
+		default:
+			return offset;
+		}
+
+		offset += ipv6_optlen(exthdr);
+		*nexthdr = &exthdr->nexthdr;
+		exthdr = (struct ipv6_opt_hdr *)(nh + offset);
+	}
+
+	return offset;
+}
 #endif
 
 static int xfrm6_hdr_offset(struct xfrm_state *x, struct sk_buff *skb, u8 **prevhdr)
@@ -131,6 +178,8 @@ static int xfrm6_hdr_offset(struct xfrm_state *x, struct sk_buff *skb, u8 **prev
 #if IS_ENABLED(CONFIG_IPV6_MIP6)
 	case IPPROTO_DSTOPTS:
 		return mip6_destopt_offset(x, skb, prevhdr);
+	case IPPROTO_ROUTING:
+		return mip6_rthdr_offset(x, skb, prevhdr);
 #endif
 	default:
 		break;