net: create nf_conntrack_ovs for ovs and tc use

Similar to nf_nat_ovs created by Commit ebddb140 ("net: move the
nat function to nf_nat_ovs for ovs and tc"), this patch is to create
nf_conntrack_ovs to get these functions shared by OVS and TC only.

There are nf_ct_helper() and nf_ct_add_helper() from nf_conntrak_helper
in this patch, and will be more in the following patches.
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Reviewed-by: Aaron Conole <aconole@redhat.com>
Acked-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

net/netfilter/Kconfig

@@ -189,6 +189,9 @@ config NF_CONNTRACK_LABELS
 	  to connection tracking entries.  It can be used with xtables connlabel
 	  match and the nftables ct expression.
 
+config NF_CONNTRACK_OVS
+	bool
+
 config NF_CT_PROTO_DCCP
 	bool 'DCCP protocol connection tracking support'
 	depends on NETFILTER_ADVANCED

net/netfilter/Makefile

@@ -11,6 +11,7 @@ nf_conntrack-$(CONFIG_NF_CONNTRACK_TIMEOUT) += nf_conntrack_timeout.o
 nf_conntrack-$(CONFIG_NF_CONNTRACK_TIMESTAMP) += nf_conntrack_timestamp.o
 nf_conntrack-$(CONFIG_NF_CONNTRACK_EVENTS) += nf_conntrack_ecache.o
 nf_conntrack-$(CONFIG_NF_CONNTRACK_LABELS) += nf_conntrack_labels.o
+nf_conntrack-$(CONFIG_NF_CONNTRACK_OVS) += nf_conntrack_ovs.o
 nf_conntrack-$(CONFIG_NF_CT_PROTO_DCCP) += nf_conntrack_proto_dccp.o
 nf_conntrack-$(CONFIG_NF_CT_PROTO_SCTP) += nf_conntrack_proto_sctp.o
 nf_conntrack-$(CONFIG_NF_CT_PROTO_GRE) += nf_conntrack_proto_gre.o

net/netfilter/nf_conntrack_helper.c

@@ -242,104 +242,6 @@ int __nf_ct_try_assign_helper(struct nf_conn *ct, struct nf_conn *tmpl,
 }
 EXPORT_SYMBOL_GPL(__nf_ct_try_assign_helper);
 
-/* 'skb' should already be pulled to nh_ofs. */
-int nf_ct_helper(struct sk_buff *skb, struct nf_conn *ct,
-		 enum ip_conntrack_info ctinfo, u16 proto)
-{
-	const struct nf_conntrack_helper *helper;
-	const struct nf_conn_help *help;
-	unsigned int protoff;
-	int err;
-
-	if (ctinfo == IP_CT_RELATED_REPLY)
-		return NF_ACCEPT;
-
-	help = nfct_help(ct);
-	if (!help)
-		return NF_ACCEPT;
-
-	helper = rcu_dereference(help->helper);
-	if (!helper)
-		return NF_ACCEPT;
-
-	if (helper->tuple.src.l3num != NFPROTO_UNSPEC &&
-	    helper->tuple.src.l3num != proto)
-		return NF_ACCEPT;
-
-	switch (proto) {
-	case NFPROTO_IPV4:
-		protoff = ip_hdrlen(skb);
-		proto = ip_hdr(skb)->protocol;
-		break;
-	case NFPROTO_IPV6: {
-		u8 nexthdr = ipv6_hdr(skb)->nexthdr;
-		__be16 frag_off;
-		int ofs;
-
-		ofs = ipv6_skip_exthdr(skb, sizeof(struct ipv6hdr), &nexthdr,
-				       &frag_off);
-		if (ofs < 0 || (frag_off & htons(~0x7)) != 0) {
-			pr_debug("proto header not found\n");
-			return NF_ACCEPT;
-		}
-		protoff = ofs;
-		proto = nexthdr;
-		break;
-	}
-	default:
-		WARN_ONCE(1, "helper invoked on non-IP family!");
-		return NF_DROP;
-	}
-
-	if (helper->tuple.dst.protonum != proto)
-		return NF_ACCEPT;
-
-	err = helper->help(skb, protoff, ct, ctinfo);
-	if (err != NF_ACCEPT)
-		return err;
-
-	/* Adjust seqs after helper.  This is needed due to some helpers (e.g.,
-	 * FTP with NAT) adusting the TCP payload size when mangling IP
-	 * addresses and/or port numbers in the text-based control connection.
-	 */
-	if (test_bit(IPS_SEQ_ADJUST_BIT, &ct->status) &&
-	    !nf_ct_seq_adjust(skb, ct, ctinfo, protoff))
-		return NF_DROP;
-	return NF_ACCEPT;
-}
-EXPORT_SYMBOL_GPL(nf_ct_helper);
-
-int nf_ct_add_helper(struct nf_conn *ct, const char *name, u8 family,
-		     u8 proto, bool nat, struct nf_conntrack_helper **hp)
-{
-	struct nf_conntrack_helper *helper;
-	struct nf_conn_help *help;
-	int ret = 0;
-
-	helper = nf_conntrack_helper_try_module_get(name, family, proto);
-	if (!helper)
-		return -EINVAL;
-
-	help = nf_ct_helper_ext_add(ct, GFP_KERNEL);
-	if (!help) {
-		nf_conntrack_helper_put(helper);
-		return -ENOMEM;
-	}
-#if IS_ENABLED(CONFIG_NF_NAT)
-	if (nat) {
-		ret = nf_nat_helper_try_module_get(name, family, proto);
-		if (ret) {
-			nf_conntrack_helper_put(helper);
-			return ret;
-		}
-	}
-#endif
-	rcu_assign_pointer(help->helper, helper);
-	*hp = helper;
-	return ret;
-}
-EXPORT_SYMBOL_GPL(nf_ct_add_helper);
-
 /* appropriate ct lock protecting must be taken by caller */
 static int unhelp(struct nf_conn *ct, void *me)
 {

net/netfilter/nf_conntrack_ovs.c

+// SPDX-License-Identifier: GPL-2.0-only
+/* Support ct functions for openvswitch and used by OVS and TC conntrack. */
+
+#include <net/netfilter/nf_conntrack_helper.h>
+#include <net/netfilter/nf_conntrack_seqadj.h>
+#include <net/ip.h>
+
+/* 'skb' should already be pulled to nh_ofs. */
+int nf_ct_helper(struct sk_buff *skb, struct nf_conn *ct,
+		 enum ip_conntrack_info ctinfo, u16 proto)
+{
+	const struct nf_conntrack_helper *helper;
+	const struct nf_conn_help *help;
+	unsigned int protoff;
+	int err;
+
+	if (ctinfo == IP_CT_RELATED_REPLY)
+		return NF_ACCEPT;
+
+	help = nfct_help(ct);
+	if (!help)
+		return NF_ACCEPT;
+
+	helper = rcu_dereference(help->helper);
+	if (!helper)
+		return NF_ACCEPT;
+
+	if (helper->tuple.src.l3num != NFPROTO_UNSPEC &&
+	    helper->tuple.src.l3num != proto)
+		return NF_ACCEPT;
+
+	switch (proto) {
+	case NFPROTO_IPV4:
+		protoff = ip_hdrlen(skb);
+		proto = ip_hdr(skb)->protocol;
+		break;
+	case NFPROTO_IPV6: {
+		u8 nexthdr = ipv6_hdr(skb)->nexthdr;
+		__be16 frag_off;
+		int ofs;
+
+		ofs = ipv6_skip_exthdr(skb, sizeof(struct ipv6hdr), &nexthdr,
+				       &frag_off);
+		if (ofs < 0 || (frag_off & htons(~0x7)) != 0) {
+			pr_debug("proto header not found\n");
+			return NF_ACCEPT;
+		}
+		protoff = ofs;
+		proto = nexthdr;
+		break;
+	}
+	default:
+		WARN_ONCE(1, "helper invoked on non-IP family!");
+		return NF_DROP;
+	}
+
+	if (helper->tuple.dst.protonum != proto)
+		return NF_ACCEPT;
+
+	err = helper->help(skb, protoff, ct, ctinfo);
+	if (err != NF_ACCEPT)
+		return err;
+
+	/* Adjust seqs after helper.  This is needed due to some helpers (e.g.,
+	 * FTP with NAT) adusting the TCP payload size when mangling IP
+	 * addresses and/or port numbers in the text-based control connection.
+	 */
+	if (test_bit(IPS_SEQ_ADJUST_BIT, &ct->status) &&
+	    !nf_ct_seq_adjust(skb, ct, ctinfo, protoff))
+		return NF_DROP;
+	return NF_ACCEPT;
+}
+EXPORT_SYMBOL_GPL(nf_ct_helper);
+
+int nf_ct_add_helper(struct nf_conn *ct, const char *name, u8 family,
+		     u8 proto, bool nat, struct nf_conntrack_helper **hp)
+{
+	struct nf_conntrack_helper *helper;
+	struct nf_conn_help *help;
+	int ret = 0;
+
+	helper = nf_conntrack_helper_try_module_get(name, family, proto);
+	if (!helper)
+		return -EINVAL;
+
+	help = nf_ct_helper_ext_add(ct, GFP_KERNEL);
+	if (!help) {
+		nf_conntrack_helper_put(helper);
+		return -ENOMEM;
+	}
+#if IS_ENABLED(CONFIG_NF_NAT)
+	if (nat) {
+		ret = nf_nat_helper_try_module_get(name, family, proto);
+		if (ret) {
+			nf_conntrack_helper_put(helper);
+			return ret;
+		}
+	}
+#endif
+	rcu_assign_pointer(help->helper, helper);
+	*hp = helper;
+	return ret;
+}
+EXPORT_SYMBOL_GPL(nf_ct_add_helper);

net/openvswitch/Kconfig

@@ -15,6 +15,7 @@ config OPENVSWITCH
 	select NET_MPLS_GSO
 	select DST_CACHE
 	select NET_NSH
+	select NF_CONNTRACK_OVS if NF_CONNTRACK
 	select NF_NAT_OVS if NF_NAT
 	help
 	  Open vSwitch is a multilayer Ethernet switch targeted at virtualized

net/sched/Kconfig

@@ -984,6 +984,7 @@ config NET_ACT_TUNNEL_KEY
 config NET_ACT_CT
 	tristate "connection tracking tc action"
 	depends on NET_CLS_ACT && NF_CONNTRACK && (!NF_NAT || NF_NAT) && NF_FLOW_TABLE
+	select NF_CONNTRACK_OVS
 	select NF_NAT_OVS if NF_NAT
 	help
 	  Say Y here to allow sending the packets to conntrack module.