1 files changed, 700 insertions, 0 deletions

diff --git a/net/ipv4/udp_offload.c b/net/ipv4/udp_offload.c
new file mode 100644
index 000000000..f4b8e5606
--- /dev/null
+++ b/net/ipv4/udp_offload.c
@@ -0,0 +1,700 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *	IPV4 GSO/GRO offload support
+ *	Linux INET implementation
+ *
+ *	UDPv4 GSO support
+ */
+
+#include <linux/skbuff.h>
+#include <net/udp.h>
+#include <net/protocol.h>
+#include <net/inet_common.h>
+
+static struct sk_buff *__skb_udp_tunnel_segment(struct sk_buff *skb,
+	netdev_features_t features,
+	struct sk_buff *(*gso_inner_segment)(struct sk_buff *skb,
+					     netdev_features_t features),
+	__be16 new_protocol, bool is_ipv6)
+{
+	int tnl_hlen = skb_inner_mac_header(skb) - skb_transport_header(skb);
+	bool remcsum, need_csum, offload_csum, gso_partial;
+	struct sk_buff *segs = ERR_PTR(-EINVAL);
+	struct udphdr *uh = udp_hdr(skb);
+	u16 mac_offset = skb->mac_header;
+	__be16 protocol = skb->protocol;
+	u16 mac_len = skb->mac_len;
+	int udp_offset, outer_hlen;
+	__wsum partial;
+	bool need_ipsec;
+
+	if (unlikely(!pskb_may_pull(skb, tnl_hlen)))
+		goto out;
+
+	/* Adjust partial header checksum to negate old length.
+	 * We cannot rely on the value contained in uh->len as it is
+	 * possible that the actual value exceeds the boundaries of the
+	 * 16 bit length field due to the header being added outside of an
+	 * IP or IPv6 frame that was already limited to 64K - 1.
+	 */
+	if (skb_shinfo(skb)->gso_type & SKB_GSO_PARTIAL)
+		partial = (__force __wsum)uh->len;
+	else
+		partial = (__force __wsum)htonl(skb->len);
+	partial = csum_sub(csum_unfold(uh->check), partial);
+
+	/* setup inner skb. */
+	skb->encapsulation = 0;
+	SKB_GSO_CB(skb)->encap_level = 0;
+	__skb_pull(skb, tnl_hlen);
+	skb_reset_mac_header(skb);
+	skb_set_network_header(skb, skb_inner_network_offset(skb));
+	skb->mac_len = skb_inner_network_offset(skb);
+	skb->protocol = new_protocol;
+
+	need_csum = !!(skb_shinfo(skb)->gso_type & SKB_GSO_UDP_TUNNEL_CSUM);
+	skb->encap_hdr_csum = need_csum;
+
+	remcsum = !!(skb_shinfo(skb)->gso_type & SKB_GSO_TUNNEL_REMCSUM);
+	skb->remcsum_offload = remcsum;
+
+	need_ipsec = skb_dst(skb) && dst_xfrm(skb_dst(skb));
+	/* Try to offload checksum if possible */
+	offload_csum = !!(need_csum &&
+			  !need_ipsec &&
+			  (skb->dev->features &
+			   (is_ipv6 ? (NETIF_F_HW_CSUM | NETIF_F_IPV6_CSUM) :
+				      (NETIF_F_HW_CSUM | NETIF_F_IP_CSUM))));
+
+	features &= skb->dev->hw_enc_features;
+
+	/* The only checksum offload we care about from here on out is the
+	 * outer one so strip the existing checksum feature flags and
+	 * instead set the flag based on our outer checksum offload value.
+	 */
+	if (remcsum) {
+		features &= ~NETIF_F_CSUM_MASK;
+		if (!need_csum || offload_csum)
+			features |= NETIF_F_HW_CSUM;
+	}
+
+	/* segment inner packet. */
+	segs = gso_inner_segment(skb, features);
+	if (IS_ERR_OR_NULL(segs)) {
+		skb_gso_error_unwind(skb, protocol, tnl_hlen, mac_offset,
+				     mac_len);
+		goto out;
+	}
+
+	gso_partial = !!(skb_shinfo(segs)->gso_type & SKB_GSO_PARTIAL);
+
+	outer_hlen = skb_tnl_header_len(skb);
+	udp_offset = outer_hlen - tnl_hlen;
+	skb = segs;
+	do {
+		unsigned int len;
+
+		if (remcsum)
+			skb->ip_summed = CHECKSUM_NONE;
+
+		/* Set up inner headers if we are offloading inner checksum */
+		if (skb->ip_summed == CHECKSUM_PARTIAL) {
+			skb_reset_inner_headers(skb);
+			skb->encapsulation = 1;
+		}
+
+		skb->mac_len = mac_len;
+		skb->protocol = protocol;
+
+		__skb_push(skb, outer_hlen);
+		skb_reset_mac_header(skb);
+		skb_set_network_header(skb, mac_len);
+		skb_set_transport_header(skb, udp_offset);
+		len = skb->len - udp_offset;
+		uh = udp_hdr(skb);
+
+		/* If we are only performing partial GSO the inner header
+		 * will be using a length value equal to only one MSS sized
+		 * segment instead of the entire frame.
+		 */
+		if (gso_partial && skb_is_gso(skb)) {
+			uh->len = htons(skb_shinfo(skb)->gso_size +
+					SKB_GSO_CB(skb)->data_offset +
+					skb->head - (unsigned char *)uh);
+		} else {
+			uh->len = htons(len);
+		}
+
+		if (!need_csum)
+			continue;
+
+		uh->check = ~csum_fold(csum_add(partial,
+				       (__force __wsum)htonl(len)));
+
+		if (skb->encapsulation || !offload_csum) {
+			uh->check = gso_make_checksum(skb, ~uh->check);
+			if (uh->check == 0)
+				uh->check = CSUM_MANGLED_0;
+		} else {
+			skb->ip_summed = CHECKSUM_PARTIAL;
+			skb->csum_start = skb_transport_header(skb) - skb->head;
+			skb->csum_offset = offsetof(struct udphdr, check);
+		}
+	} while ((skb = skb->next));
+out:
+	return segs;
+}
+
+struct sk_buff *skb_udp_tunnel_segment(struct sk_buff *skb,
+				       netdev_features_t features,
+				       bool is_ipv6)
+{
+	__be16 protocol = skb->protocol;
+	const struct net_offload **offloads;
+	const struct net_offload *ops;
+	struct sk_buff *segs = ERR_PTR(-EINVAL);
+	struct sk_buff *(*gso_inner_segment)(struct sk_buff *skb,
+					     netdev_features_t features);
+
+	rcu_read_lock();
+
+	switch (skb->inner_protocol_type) {
+	case ENCAP_TYPE_ETHER:
+		protocol = skb->inner_protocol;
+		gso_inner_segment = skb_mac_gso_segment;
+		break;
+	case ENCAP_TYPE_IPPROTO:
+		offloads = is_ipv6 ? inet6_offloads : inet_offloads;
+		ops = rcu_dereference(offloads[skb->inner_ipproto]);
+		if (!ops || !ops->callbacks.gso_segment)
+			goto out_unlock;
+		gso_inner_segment = ops->callbacks.gso_segment;
+		break;
+	default:
+		goto out_unlock;
+	}
+
+	segs = __skb_udp_tunnel_segment(skb, features, gso_inner_segment,
+					protocol, is_ipv6);
+
+out_unlock:
+	rcu_read_unlock();
+
+	return segs;
+}
+EXPORT_SYMBOL(skb_udp_tunnel_segment);
+
+static void __udpv4_gso_segment_csum(struct sk_buff *seg,
+				     __be32 *oldip, __be32 *newip,
+				     __be16 *oldport, __be16 *newport)
+{
+	struct udphdr *uh;
+	struct iphdr *iph;
+
+	if (*oldip == *newip && *oldport == *newport)
+		return;
+
+	uh = udp_hdr(seg);
+	iph = ip_hdr(seg);
+
+	if (uh->check) {
+		inet_proto_csum_replace4(&uh->check, seg, *oldip, *newip,
+					 true);
+		inet_proto_csum_replace2(&uh->check, seg, *oldport, *newport,
+					 false);
+		if (!uh->check)
+			uh->check = CSUM_MANGLED_0;
+	}
+	*oldport = *newport;
+
+	csum_replace4(&iph->check, *oldip, *newip);
+	*oldip = *newip;
+}
+
+static struct sk_buff *__udpv4_gso_segment_list_csum(struct sk_buff *segs)
+{
+	struct sk_buff *seg;
+	struct udphdr *uh, *uh2;
+	struct iphdr *iph, *iph2;
+
+	seg = segs;
+	uh = udp_hdr(seg);
+	iph = ip_hdr(seg);
+
+	if ((udp_hdr(seg)->dest == udp_hdr(seg->next)->dest) &&
+	    (udp_hdr(seg)->source == udp_hdr(seg->next)->source) &&
+	    (ip_hdr(seg)->daddr == ip_hdr(seg->next)->daddr) &&
+	    (ip_hdr(seg)->saddr == ip_hdr(seg->next)->saddr))
+		return segs;
+
+	while ((seg = seg->next)) {
+		uh2 = udp_hdr(seg);
+		iph2 = ip_hdr(seg);
+
+		__udpv4_gso_segment_csum(seg,
+					 &iph2->saddr, &iph->saddr,
+					 &uh2->source, &uh->source);
+		__udpv4_gso_segment_csum(seg,
+					 &iph2->daddr, &iph->daddr,
+					 &uh2->dest, &uh->dest);
+	}
+
+	return segs;
+}
+
+static struct sk_buff *__udp_gso_segment_list(struct sk_buff *skb,
+					      netdev_features_t features,
+					      bool is_ipv6)
+{
+	unsigned int mss = skb_shinfo(skb)->gso_size;
+
+	skb = skb_segment_list(skb, features, skb_mac_header_len(skb));
+	if (IS_ERR(skb))
+		return skb;
+
+	udp_hdr(skb)->len = htons(sizeof(struct udphdr) + mss);
+
+	return is_ipv6 ? skb : __udpv4_gso_segment_list_csum(skb);
+}
+
+struct sk_buff *__udp_gso_segment(struct sk_buff *gso_skb,
+				  netdev_features_t features, bool is_ipv6)
+{
+	struct sock *sk = gso_skb->sk;
+	unsigned int sum_truesize = 0;
+	struct sk_buff *segs, *seg;
+	struct udphdr *uh;
+	unsigned int mss;
+	bool copy_dtor;
+	__sum16 check;
+	__be16 newlen;
+
+	if (skb_shinfo(gso_skb)->gso_type & SKB_GSO_FRAGLIST)
+		return __udp_gso_segment_list(gso_skb, features, is_ipv6);
+
+	mss = skb_shinfo(gso_skb)->gso_size;
+	if (gso_skb->len <= sizeof(*uh) + mss)
+		return ERR_PTR(-EINVAL);
+
+	skb_pull(gso_skb, sizeof(*uh));
+
+	/* clear destructor to avoid skb_segment assigning it to tail */
+	copy_dtor = gso_skb->destructor == sock_wfree;
+	if (copy_dtor)
+		gso_skb->destructor = NULL;
+
+	segs = skb_segment(gso_skb, features);
+	if (IS_ERR_OR_NULL(segs)) {
+		if (copy_dtor)
+			gso_skb->destructor = sock_wfree;
+		return segs;
+	}
+
+	/* GSO partial and frag_list segmentation only requires splitting
+	 * the frame into an MSS multiple and possibly a remainder, both
+	 * cases return a GSO skb. So update the mss now.
+	 */
+	if (skb_is_gso(segs))
+		mss *= skb_shinfo(segs)->gso_segs;
+
+	seg = segs;
+	uh = udp_hdr(seg);
+
+	/* preserve TX timestamp flags and TS key for first segment */
+	skb_shinfo(seg)->tskey = skb_shinfo(gso_skb)->tskey;
+	skb_shinfo(seg)->tx_flags |=
+			(skb_shinfo(gso_skb)->tx_flags & SKBTX_ANY_TSTAMP);
+
+	/* compute checksum adjustment based on old length versus new */
+	newlen = htons(sizeof(*uh) + mss);
+	check = csum16_add(csum16_sub(uh->check, uh->len), newlen);
+
+	for (;;) {
+		if (copy_dtor) {
+			seg->destructor = sock_wfree;
+			seg->sk = sk;
+			sum_truesize += seg->truesize;
+		}
+
+		if (!seg->next)
+			break;
+
+		uh->len = newlen;
+		uh->check = check;
+
+		if (seg->ip_summed == CHECKSUM_PARTIAL)
+			gso_reset_checksum(seg, ~check);
+		else
+			uh->check = gso_make_checksum(seg, ~check) ? :
+				    CSUM_MANGLED_0;
+
+		seg = seg->next;
+		uh = udp_hdr(seg);
+	}
+
+	/* last packet can be partial gso_size, account for that in checksum */
+	newlen = htons(skb_tail_pointer(seg) - skb_transport_header(seg) +
+		       seg->data_len);
+	check = csum16_add(csum16_sub(uh->check, uh->len), newlen);
+
+	uh->len = newlen;
+	uh->check = check;
+
+	if (seg->ip_summed == CHECKSUM_PARTIAL)
+		gso_reset_checksum(seg, ~check);
+	else
+		uh->check = gso_make_checksum(seg, ~check) ? : CSUM_MANGLED_0;
+
+	/* update refcount for the packet */
+	if (copy_dtor) {
+		int delta = sum_truesize - gso_skb->truesize;
+
+		/* In some pathological cases, delta can be negative.
+		 * We need to either use refcount_add() or refcount_sub_and_test()
+		 */
+		if (likely(delta >= 0))
+			refcount_add(delta, &sk->sk_wmem_alloc);
+		else
+			WARN_ON_ONCE(refcount_sub_and_test(-delta, &sk->sk_wmem_alloc));
+	}
+	return segs;
+}
+EXPORT_SYMBOL_GPL(__udp_gso_segment);
+
+static struct sk_buff *udp4_ufo_fragment(struct sk_buff *skb,
+					 netdev_features_t features)
+{
+	struct sk_buff *segs = ERR_PTR(-EINVAL);
+	unsigned int mss;
+	__wsum csum;
+	struct udphdr *uh;
+	struct iphdr *iph;
+
+	if (skb->encapsulation &&
+	    (skb_shinfo(skb)->gso_type &
+	     (SKB_GSO_UDP_TUNNEL|SKB_GSO_UDP_TUNNEL_CSUM))) {
+		segs = skb_udp_tunnel_segment(skb, features, false);
+		goto out;
+	}
+
+	if (!(skb_shinfo(skb)->gso_type & (SKB_GSO_UDP | SKB_GSO_UDP_L4)))
+		goto out;
+
+	if (!pskb_may_pull(skb, sizeof(struct udphdr)))
+		goto out;
+
+	if (skb_shinfo(skb)->gso_type & SKB_GSO_UDP_L4)
+		return __udp_gso_segment(skb, features, false);
+
+	mss = skb_shinfo(skb)->gso_size;
+	if (unlikely(skb->len <= mss))
+		goto out;
+
+	/* Do software UFO. Complete and fill in the UDP checksum as
+	 * HW cannot do checksum of UDP packets sent as multiple
+	 * IP fragments.
+	 */
+
+	uh = udp_hdr(skb);
+	iph = ip_hdr(skb);
+
+	uh->check = 0;
+	csum = skb_checksum(skb, 0, skb->len, 0);
+	uh->check = udp_v4_check(skb->len, iph->saddr, iph->daddr, csum);
+	if (uh->check == 0)
+		uh->check = CSUM_MANGLED_0;
+
+	skb->ip_summed = CHECKSUM_UNNECESSARY;
+
+	/* If there is no outer header we can fake a checksum offload
+	 * due to the fact that we have already done the checksum in
+	 * software prior to segmenting the frame.
+	 */
+	if (!skb->encap_hdr_csum)
+		features |= NETIF_F_HW_CSUM;
+
+	/* Fragment the skb. IP headers of the fragments are updated in
+	 * inet_gso_segment()
+	 */
+	segs = skb_segment(skb, features);
+out:
+	return segs;
+}
+
+#define UDP_GRO_CNT_MAX 64
+static struct sk_buff *udp_gro_receive_segment(struct list_head *head,
+					       struct sk_buff *skb)
+{
+	struct udphdr *uh = udp_gro_udphdr(skb);
+	struct sk_buff *pp = NULL;
+	struct udphdr *uh2;
+	struct sk_buff *p;
+	unsigned int ulen;
+	int ret = 0;
+
+	/* requires non zero csum, for symmetry with GSO */
+	if (!uh->check) {
+		NAPI_GRO_CB(skb)->flush = 1;
+		return NULL;
+	}
+
+	/* Do not deal with padded or malicious packets, sorry ! */
+	ulen = ntohs(uh->len);
+	if (ulen <= sizeof(*uh) || ulen != skb_gro_len(skb)) {
+		NAPI_GRO_CB(skb)->flush = 1;
+		return NULL;
+	}
+	/* pull encapsulating udp header */
+	skb_gro_pull(skb, sizeof(struct udphdr));
+
+	list_for_each_entry(p, head, list) {
+		if (!NAPI_GRO_CB(p)->same_flow)
+			continue;
+
+		uh2 = udp_hdr(p);
+
+		/* Match ports only, as csum is always non zero */
+		if ((*(u32 *)&uh->source != *(u32 *)&uh2->source)) {
+			NAPI_GRO_CB(p)->same_flow = 0;
+			continue;
+		}
+
+		if (NAPI_GRO_CB(skb)->is_flist != NAPI_GRO_CB(p)->is_flist) {
+			NAPI_GRO_CB(skb)->flush = 1;
+			return p;
+		}
+
+		/* Terminate the flow on len mismatch or if it grow "too much".
+		 * Under small packet flood GRO count could elsewhere grow a lot
+		 * leading to excessive truesize values.
+		 * On len mismatch merge the first packet shorter than gso_size,
+		 * otherwise complete the GRO packet.
+		 */
+		if (ulen > ntohs(uh2->len)) {
+			pp = p;
+		} else {
+			if (NAPI_GRO_CB(skb)->is_flist) {
+				if (!pskb_may_pull(skb, skb_gro_offset(skb))) {
+					NAPI_GRO_CB(skb)->flush = 1;
+					return NULL;
+				}
+				if ((skb->ip_summed != p->ip_summed) ||
+				    (skb->csum_level != p->csum_level)) {
+					NAPI_GRO_CB(skb)->flush = 1;
+					return NULL;
+				}
+				ret = skb_gro_receive_list(p, skb);
+			} else {
+				skb_gro_postpull_rcsum(skb, uh,
+						       sizeof(struct udphdr));
+
+				ret = skb_gro_receive(p, skb);
+			}
+		}
+
+		if (ret || ulen != ntohs(uh2->len) ||
+		    NAPI_GRO_CB(p)->count >= UDP_GRO_CNT_MAX)
+			pp = p;
+
+		return pp;
+	}
+
+	/* mismatch, but we never need to flush */
+	return NULL;
+}
+
+struct sk_buff *udp_gro_receive(struct list_head *head, struct sk_buff *skb,
+				struct udphdr *uh, struct sock *sk)
+{
+	struct sk_buff *pp = NULL;
+	struct sk_buff *p;
+	struct udphdr *uh2;
+	unsigned int off = skb_gro_offset(skb);
+	int flush = 1;
+
+	NAPI_GRO_CB(skb)->is_flist = 0;
+	if (skb->dev->features & NETIF_F_GRO_FRAGLIST)
+		NAPI_GRO_CB(skb)->is_flist = sk ? !udp_sk(sk)->gro_enabled: 1;
+
+	if ((sk && udp_sk(sk)->gro_enabled) || NAPI_GRO_CB(skb)->is_flist) {
+		pp = call_gro_receive(udp_gro_receive_segment, head, skb);
+		return pp;
+	}
+
+	if (!sk || NAPI_GRO_CB(skb)->encap_mark ||
+	    (uh->check && skb->ip_summed != CHECKSUM_PARTIAL &&
+	     NAPI_GRO_CB(skb)->csum_cnt == 0 &&
+	     !NAPI_GRO_CB(skb)->csum_valid) ||
+	    !udp_sk(sk)->gro_receive)
+		goto out;
+
+	/* mark that this skb passed once through the tunnel gro layer */
+	NAPI_GRO_CB(skb)->encap_mark = 1;
+
+	flush = 0;
+
+	list_for_each_entry(p, head, list) {
+		if (!NAPI_GRO_CB(p)->same_flow)
+			continue;
+
+		uh2 = (struct udphdr   *)(p->data + off);
+
+		/* Match ports and either checksums are either both zero
+		 * or nonzero.
+		 */
+		if ((*(u32 *)&uh->source != *(u32 *)&uh2->source) ||
+		    (!uh->check ^ !uh2->check)) {
+			NAPI_GRO_CB(p)->same_flow = 0;
+			continue;
+		}
+	}
+
+	skb_gro_pull(skb, sizeof(struct udphdr)); /* pull encapsulating udp header */
+	skb_gro_postpull_rcsum(skb, uh, sizeof(struct udphdr));
+	pp = call_gro_receive_sk(udp_sk(sk)->gro_receive, sk, head, skb);
+
+out:
+	skb_gro_flush_final(skb, pp, flush);
+	return pp;
+}
+EXPORT_SYMBOL(udp_gro_receive);
+
+static struct sock *udp4_gro_lookup_skb(struct sk_buff *skb, __be16 sport,
+					__be16 dport)
+{
+	const struct iphdr *iph = skb_gro_network_header(skb);
+
+	return __udp4_lib_lookup(dev_net(skb->dev), iph->saddr, sport,
+				 iph->daddr, dport, inet_iif(skb),
+				 inet_sdif(skb), &udp_table, NULL);
+}
+
+INDIRECT_CALLABLE_SCOPE
+struct sk_buff *udp4_gro_receive(struct list_head *head, struct sk_buff *skb)
+{
+	struct udphdr *uh = udp_gro_udphdr(skb);
+	struct sock *sk = NULL;
+	struct sk_buff *pp;
+
+	if (unlikely(!uh))
+		goto flush;
+
+	/* Don't bother verifying checksum if we're going to flush anyway. */
+	if (NAPI_GRO_CB(skb)->flush)
+		goto skip;
+
+	if (skb_gro_checksum_validate_zero_check(skb, IPPROTO_UDP, uh->check,
+						 inet_gro_compute_pseudo))
+		goto flush;
+	else if (uh->check)
+		skb_gro_checksum_try_convert(skb, IPPROTO_UDP,
+					     inet_gro_compute_pseudo);
+skip:
+	NAPI_GRO_CB(skb)->is_ipv6 = 0;
+	rcu_read_lock();
+
+	if (static_branch_unlikely(&udp_encap_needed_key))
+		sk = udp4_gro_lookup_skb(skb, uh->source, uh->dest);
+
+	pp = udp_gro_receive(head, skb, uh, sk);
+	rcu_read_unlock();
+	return pp;
+
+flush:
+	NAPI_GRO_CB(skb)->flush = 1;
+	return NULL;
+}
+
+static int udp_gro_complete_segment(struct sk_buff *skb)
+{
+	struct udphdr *uh = udp_hdr(skb);
+
+	skb->csum_start = (unsigned char *)uh - skb->head;
+	skb->csum_offset = offsetof(struct udphdr, check);
+	skb->ip_summed = CHECKSUM_PARTIAL;
+
+	skb_shinfo(skb)->gso_segs = NAPI_GRO_CB(skb)->count;
+	skb_shinfo(skb)->gso_type |= SKB_GSO_UDP_L4;
+
+	if (skb->encapsulation)
+		skb->inner_transport_header = skb->transport_header;
+
+	return 0;
+}
+
+int udp_gro_complete(struct sk_buff *skb, int nhoff,
+		     udp_lookup_t lookup)
+{
+	__be16 newlen = htons(skb->len - nhoff);
+	struct udphdr *uh = (struct udphdr *)(skb->data + nhoff);
+	int err = -ENOSYS;
+	struct sock *sk;
+
+	uh->len = newlen;
+
+	rcu_read_lock();
+	sk = INDIRECT_CALL_INET(lookup, udp6_lib_lookup_skb,
+				udp4_lib_lookup_skb, skb, uh->source, uh->dest);
+	if (sk && udp_sk(sk)->gro_complete) {
+		skb_shinfo(skb)->gso_type = uh->check ? SKB_GSO_UDP_TUNNEL_CSUM
+					: SKB_GSO_UDP_TUNNEL;
+
+		/* Set encapsulation before calling into inner gro_complete()
+		 * functions to make them set up the inner offsets.
+		 */
+		skb->encapsulation = 1;
+		err = udp_sk(sk)->gro_complete(sk, skb,
+				nhoff + sizeof(struct udphdr));
+	} else {
+		err = udp_gro_complete_segment(skb);
+	}
+	rcu_read_unlock();
+
+	if (skb->remcsum_offload)
+		skb_shinfo(skb)->gso_type |= SKB_GSO_TUNNEL_REMCSUM;
+
+	return err;
+}
+EXPORT_SYMBOL(udp_gro_complete);
+
+INDIRECT_CALLABLE_SCOPE int udp4_gro_complete(struct sk_buff *skb, int nhoff)
+{
+	const struct iphdr *iph = ip_hdr(skb);
+	struct udphdr *uh = (struct udphdr *)(skb->data + nhoff);
+
+	if (NAPI_GRO_CB(skb)->is_flist) {
+		uh->len = htons(skb->len - nhoff);
+
+		skb_shinfo(skb)->gso_type |= (SKB_GSO_FRAGLIST|SKB_GSO_UDP_L4);
+		skb_shinfo(skb)->gso_segs = NAPI_GRO_CB(skb)->count;
+
+		if (skb->ip_summed == CHECKSUM_UNNECESSARY) {
+			if (skb->csum_level < SKB_MAX_CSUM_LEVEL)
+				skb->csum_level++;
+		} else {
+			skb->ip_summed = CHECKSUM_UNNECESSARY;
+			skb->csum_level = 0;
+		}
+
+		return 0;
+	}
+
+	if (uh->check)
+		uh->check = ~udp_v4_check(skb->len - nhoff, iph->saddr,
+					  iph->daddr, 0);
+
+	return udp_gro_complete(skb, nhoff, udp4_lib_lookup_skb);
+}
+
+static const struct net_offload udpv4_offload = {
+	.callbacks = {
+		.gso_segment = udp4_ufo_fragment,
+		.gro_receive  =	udp4_gro_receive,
+		.gro_complete =	udp4_gro_complete,
+	},
+};
+
+int __init udpv4_offload_init(void)
+{
+	return inet_add_offload(&udpv4_offload, IPPROTO_UDP);
+}