diff mbox series

[ovs-dev,PATCHv3,net-next,1/4] net: move the ct helper function to nf_conntrack_helper for ovs and tc

Message ID 77bf40ce177056d460cc7ed32ef4d19d1f7b5290.1667230381.git.lucien.xin@gmail.com
State Handled Elsewhere
Headers show
Series net: add helper support in tc act_ct for ovs offloading | expand

Commit Message

Xin Long Oct. 31, 2022, 3:36 p.m. UTC
Move ovs_ct_helper from openvswitch to nf_conntrack_helper and rename
as nf_ct_helper so that it can be used in TC act_ct in the next patch.
Note that it also adds the checks for the family and proto, as in TC
act_ct, the packets with correct family and proto are not guaranteed.

Signed-off-by: Xin Long <lucien.xin@gmail.com>
---
 include/net/netfilter/nf_conntrack_helper.h |  2 +
 net/netfilter/nf_conntrack_helper.c         | 71 +++++++++++++++++++++
 net/openvswitch/conntrack.c                 | 61 +-----------------
 3 files changed, 74 insertions(+), 60 deletions(-)

Comments

Aaron Conole Nov. 2, 2022, 7:21 p.m. UTC | #1
Xin Long <lucien.xin@gmail.com> writes:

> Move ovs_ct_helper from openvswitch to nf_conntrack_helper and rename
> as nf_ct_helper so that it can be used in TC act_ct in the next patch.
> Note that it also adds the checks for the family and proto, as in TC
> act_ct, the packets with correct family and proto are not guaranteed.
>
> Signed-off-by: Xin Long <lucien.xin@gmail.com>
> ---

Hi Xin,

>  include/net/netfilter/nf_conntrack_helper.h |  2 +
>  net/netfilter/nf_conntrack_helper.c         | 71 +++++++++++++++++++++
>  net/openvswitch/conntrack.c                 | 61 +-----------------
>  3 files changed, 74 insertions(+), 60 deletions(-)
>
> diff --git a/include/net/netfilter/nf_conntrack_helper.h b/include/net/netfilter/nf_conntrack_helper.h
> index 9939c366f720..6c32e59fc16f 100644
> --- a/include/net/netfilter/nf_conntrack_helper.h
> +++ b/include/net/netfilter/nf_conntrack_helper.h
> @@ -115,6 +115,8 @@ struct nf_conn_help *nf_ct_helper_ext_add(struct nf_conn *ct, gfp_t gfp);
>  int __nf_ct_try_assign_helper(struct nf_conn *ct, struct nf_conn *tmpl,
>  			      gfp_t flags);
>  
> +int nf_ct_helper(struct sk_buff *skb, u16 proto);
> +
>  void nf_ct_helper_destroy(struct nf_conn *ct);
>  
>  static inline struct nf_conn_help *nfct_help(const struct nf_conn *ct)
> diff --git a/net/netfilter/nf_conntrack_helper.c b/net/netfilter/nf_conntrack_helper.c
> index ff737a76052e..83615e479f87 100644
> --- a/net/netfilter/nf_conntrack_helper.c
> +++ b/net/netfilter/nf_conntrack_helper.c
> @@ -26,7 +26,9 @@
>  #include <net/netfilter/nf_conntrack_extend.h>
>  #include <net/netfilter/nf_conntrack_helper.h>
>  #include <net/netfilter/nf_conntrack_l4proto.h>
> +#include <net/netfilter/nf_conntrack_seqadj.h>
>  #include <net/netfilter/nf_log.h>
> +#include <net/ip.h>
>  
>  static DEFINE_MUTEX(nf_ct_helper_mutex);
>  struct hlist_head *nf_ct_helper_hash __read_mostly;
> @@ -240,6 +242,75 @@ 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, u16 proto)

AFAICT, in all the places we call this we will have the nf_conn and
ip_conntrack_info already.  Maybe it makes sense to pass them here
rather than looking up again?  Originally, that information wasn't
available in the calling function - over time this has been added so we
might as well reduce the amount of "extra lookups" performed.

> +{
> +	const struct nf_conntrack_helper *helper;
> +	const struct nf_conn_help *help;
> +	enum ip_conntrack_info ctinfo;
> +	unsigned int protoff;
> +	struct nf_conn *ct;
> +	int err;
> +
> +	ct = nf_ct_get(skb, &ctinfo);
> +	if (!ct || 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);
> +
>  /* appropriate ct lock protecting must be taken by caller */
>  static int unhelp(struct nf_conn *ct, void *me)
>  {
> diff --git a/net/openvswitch/conntrack.c b/net/openvswitch/conntrack.c
> index c7b10234cf7c..19b5c54615c8 100644
> --- a/net/openvswitch/conntrack.c
> +++ b/net/openvswitch/conntrack.c
> @@ -434,65 +434,6 @@ static int ovs_ct_set_labels(struct nf_conn *ct, struct sw_flow_key *key,
>  	return 0;
>  }
>  
> -/* 'skb' should already be pulled to nh_ofs. */
> -static int ovs_ct_helper(struct sk_buff *skb, u16 proto)
> -{
> -	const struct nf_conntrack_helper *helper;
> -	const struct nf_conn_help *help;
> -	enum ip_conntrack_info ctinfo;
> -	unsigned int protoff;
> -	struct nf_conn *ct;
> -	int err;
> -
> -	ct = nf_ct_get(skb, &ctinfo);
> -	if (!ct || 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;
> -
> -	switch (proto) {
> -	case NFPROTO_IPV4:
> -		protoff = ip_hdrlen(skb);
> -		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;
> -		break;
> -	}
> -	default:
> -		WARN_ONCE(1, "helper invoked on non-IP family!");
> -		return NF_DROP;
> -	}
> -
> -	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;
> -}
> -
>  /* Returns 0 on success, -EINPROGRESS if 'skb' is stolen, or other nonzero
>   * value if 'skb' is freed.
>   */
> @@ -1038,7 +979,7 @@ static int __ovs_ct_lookup(struct net *net, struct sw_flow_key *key,
>  		 */
>  		if ((nf_ct_is_confirmed(ct) ? !cached || add_helper :
>  					      info->commit) &&
> -		    ovs_ct_helper(skb, info->family) != NF_ACCEPT) {
> +		    nf_ct_helper(skb, info->family) != NF_ACCEPT) {
>  			return -EINVAL;
>  		}
Xin Long Nov. 2, 2022, 8:01 p.m. UTC | #2
On Wed, Nov 2, 2022 at 3:21 PM Aaron Conole <aconole@redhat.com> wrote:
>
> Xin Long <lucien.xin@gmail.com> writes:
>
> > Move ovs_ct_helper from openvswitch to nf_conntrack_helper and rename
> > as nf_ct_helper so that it can be used in TC act_ct in the next patch.
> > Note that it also adds the checks for the family and proto, as in TC
> > act_ct, the packets with correct family and proto are not guaranteed.
> >
> > Signed-off-by: Xin Long <lucien.xin@gmail.com>
> > ---
>
> Hi Xin,
>
> >  include/net/netfilter/nf_conntrack_helper.h |  2 +
> >  net/netfilter/nf_conntrack_helper.c         | 71 +++++++++++++++++++++
> >  net/openvswitch/conntrack.c                 | 61 +-----------------
> >  3 files changed, 74 insertions(+), 60 deletions(-)
> >
> > diff --git a/include/net/netfilter/nf_conntrack_helper.h b/include/net/netfilter/nf_conntrack_helper.h
> > index 9939c366f720..6c32e59fc16f 100644
> > --- a/include/net/netfilter/nf_conntrack_helper.h
> > +++ b/include/net/netfilter/nf_conntrack_helper.h
> > @@ -115,6 +115,8 @@ struct nf_conn_help *nf_ct_helper_ext_add(struct nf_conn *ct, gfp_t gfp);
> >  int __nf_ct_try_assign_helper(struct nf_conn *ct, struct nf_conn *tmpl,
> >                             gfp_t flags);
> >
> > +int nf_ct_helper(struct sk_buff *skb, u16 proto);
> > +
> >  void nf_ct_helper_destroy(struct nf_conn *ct);
> >
> >  static inline struct nf_conn_help *nfct_help(const struct nf_conn *ct)
> > diff --git a/net/netfilter/nf_conntrack_helper.c b/net/netfilter/nf_conntrack_helper.c
> > index ff737a76052e..83615e479f87 100644
> > --- a/net/netfilter/nf_conntrack_helper.c
> > +++ b/net/netfilter/nf_conntrack_helper.c
> > @@ -26,7 +26,9 @@
> >  #include <net/netfilter/nf_conntrack_extend.h>
> >  #include <net/netfilter/nf_conntrack_helper.h>
> >  #include <net/netfilter/nf_conntrack_l4proto.h>
> > +#include <net/netfilter/nf_conntrack_seqadj.h>
> >  #include <net/netfilter/nf_log.h>
> > +#include <net/ip.h>
> >
> >  static DEFINE_MUTEX(nf_ct_helper_mutex);
> >  struct hlist_head *nf_ct_helper_hash __read_mostly;
> > @@ -240,6 +242,75 @@ 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, u16 proto)
>
> AFAICT, in all the places we call this we will have the nf_conn and
> ip_conntrack_info already.  Maybe it makes sense to pass them here
> rather than looking up again?  Originally, that information wasn't
> available in the calling function - over time this has been added so we
> might as well reduce the amount of "extra lookups" performed.
I just tried to keep nf_ct_helper() as similar as possible
to the original ovs_ct_helper().

But sure, we can also pass ct and ctinfo as the arguments,
like some other functions where it passes all of skb, ct and ctinfo.

Thanks.

>
> > +{
> > +     const struct nf_conntrack_helper *helper;
> > +     const struct nf_conn_help *help;
> > +     enum ip_conntrack_info ctinfo;
> > +     unsigned int protoff;
> > +     struct nf_conn *ct;
> > +     int err;
> > +
> > +     ct = nf_ct_get(skb, &ctinfo);
> > +     if (!ct || 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);
> > +
> >  /* appropriate ct lock protecting must be taken by caller */
> >  static int unhelp(struct nf_conn *ct, void *me)
> >  {
> > diff --git a/net/openvswitch/conntrack.c b/net/openvswitch/conntrack.c
> > index c7b10234cf7c..19b5c54615c8 100644
> > --- a/net/openvswitch/conntrack.c
> > +++ b/net/openvswitch/conntrack.c
> > @@ -434,65 +434,6 @@ static int ovs_ct_set_labels(struct nf_conn *ct, struct sw_flow_key *key,
> >       return 0;
> >  }
> >
> > -/* 'skb' should already be pulled to nh_ofs. */
> > -static int ovs_ct_helper(struct sk_buff *skb, u16 proto)
> > -{
> > -     const struct nf_conntrack_helper *helper;
> > -     const struct nf_conn_help *help;
> > -     enum ip_conntrack_info ctinfo;
> > -     unsigned int protoff;
> > -     struct nf_conn *ct;
> > -     int err;
> > -
> > -     ct = nf_ct_get(skb, &ctinfo);
> > -     if (!ct || 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;
> > -
> > -     switch (proto) {
> > -     case NFPROTO_IPV4:
> > -             protoff = ip_hdrlen(skb);
> > -             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;
> > -             break;
> > -     }
> > -     default:
> > -             WARN_ONCE(1, "helper invoked on non-IP family!");
> > -             return NF_DROP;
> > -     }
> > -
> > -     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;
> > -}
> > -
> >  /* Returns 0 on success, -EINPROGRESS if 'skb' is stolen, or other nonzero
> >   * value if 'skb' is freed.
> >   */
> > @@ -1038,7 +979,7 @@ static int __ovs_ct_lookup(struct net *net, struct sw_flow_key *key,
> >                */
> >               if ((nf_ct_is_confirmed(ct) ? !cached || add_helper :
> >                                             info->commit) &&
> > -                 ovs_ct_helper(skb, info->family) != NF_ACCEPT) {
> > +                 nf_ct_helper(skb, info->family) != NF_ACCEPT) {
> >                       return -EINVAL;
> >               }
>
diff mbox series

Patch

diff --git a/include/net/netfilter/nf_conntrack_helper.h b/include/net/netfilter/nf_conntrack_helper.h
index 9939c366f720..6c32e59fc16f 100644
--- a/include/net/netfilter/nf_conntrack_helper.h
+++ b/include/net/netfilter/nf_conntrack_helper.h
@@ -115,6 +115,8 @@  struct nf_conn_help *nf_ct_helper_ext_add(struct nf_conn *ct, gfp_t gfp);
 int __nf_ct_try_assign_helper(struct nf_conn *ct, struct nf_conn *tmpl,
 			      gfp_t flags);
 
+int nf_ct_helper(struct sk_buff *skb, u16 proto);
+
 void nf_ct_helper_destroy(struct nf_conn *ct);
 
 static inline struct nf_conn_help *nfct_help(const struct nf_conn *ct)
diff --git a/net/netfilter/nf_conntrack_helper.c b/net/netfilter/nf_conntrack_helper.c
index ff737a76052e..83615e479f87 100644
--- a/net/netfilter/nf_conntrack_helper.c
+++ b/net/netfilter/nf_conntrack_helper.c
@@ -26,7 +26,9 @@ 
 #include <net/netfilter/nf_conntrack_extend.h>
 #include <net/netfilter/nf_conntrack_helper.h>
 #include <net/netfilter/nf_conntrack_l4proto.h>
+#include <net/netfilter/nf_conntrack_seqadj.h>
 #include <net/netfilter/nf_log.h>
+#include <net/ip.h>
 
 static DEFINE_MUTEX(nf_ct_helper_mutex);
 struct hlist_head *nf_ct_helper_hash __read_mostly;
@@ -240,6 +242,75 @@  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, u16 proto)
+{
+	const struct nf_conntrack_helper *helper;
+	const struct nf_conn_help *help;
+	enum ip_conntrack_info ctinfo;
+	unsigned int protoff;
+	struct nf_conn *ct;
+	int err;
+
+	ct = nf_ct_get(skb, &ctinfo);
+	if (!ct || 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);
+
 /* appropriate ct lock protecting must be taken by caller */
 static int unhelp(struct nf_conn *ct, void *me)
 {
diff --git a/net/openvswitch/conntrack.c b/net/openvswitch/conntrack.c
index c7b10234cf7c..19b5c54615c8 100644
--- a/net/openvswitch/conntrack.c
+++ b/net/openvswitch/conntrack.c
@@ -434,65 +434,6 @@  static int ovs_ct_set_labels(struct nf_conn *ct, struct sw_flow_key *key,
 	return 0;
 }
 
-/* 'skb' should already be pulled to nh_ofs. */
-static int ovs_ct_helper(struct sk_buff *skb, u16 proto)
-{
-	const struct nf_conntrack_helper *helper;
-	const struct nf_conn_help *help;
-	enum ip_conntrack_info ctinfo;
-	unsigned int protoff;
-	struct nf_conn *ct;
-	int err;
-
-	ct = nf_ct_get(skb, &ctinfo);
-	if (!ct || 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;
-
-	switch (proto) {
-	case NFPROTO_IPV4:
-		protoff = ip_hdrlen(skb);
-		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;
-		break;
-	}
-	default:
-		WARN_ONCE(1, "helper invoked on non-IP family!");
-		return NF_DROP;
-	}
-
-	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;
-}
-
 /* Returns 0 on success, -EINPROGRESS if 'skb' is stolen, or other nonzero
  * value if 'skb' is freed.
  */
@@ -1038,7 +979,7 @@  static int __ovs_ct_lookup(struct net *net, struct sw_flow_key *key,
 		 */
 		if ((nf_ct_is_confirmed(ct) ? !cached || add_helper :
 					      info->commit) &&
-		    ovs_ct_helper(skb, info->family) != NF_ACCEPT) {
+		    nf_ct_helper(skb, info->family) != NF_ACCEPT) {
 			return -EINVAL;
 		}