1 files changed, 100 insertions, 1 deletions

diff --git a/net/ipv4/udp_offload.c b/net/ipv4/udp_offload.c
index ea6e6e7df0ee..92dc9e5a7ff3 100644
--- a/net/ipv4/udp_offload.c
+++ b/net/ipv4/udp_offload.c
@@ -187,6 +187,102 @@ out_unlock:
 }
 EXPORT_SYMBOL(skb_udp_tunnel_segment);
 
+struct sk_buff *__udp_gso_segment(struct sk_buff *gso_skb,
+				  netdev_features_t features)
+{
+	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;
+
+	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 (unlikely(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);
+
+	/* 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)
 {
@@ -203,12 +299,15 @@ static struct sk_buff *udp4_ufo_fragment(struct sk_buff *skb,
 		goto out;
 	}
 
-	if (!(skb_shinfo(skb)->gso_type & SKB_GSO_UDP))
+	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);
+
 	mss = skb_shinfo(skb)->gso_size;
 	if (unlikely(skb->len <= mss))
 		goto out;