2 files changed, 56 insertions, 1 deletions

diff --git a/include/net/ipv6.h b/include/net/ipv6.h
index 63d019953c47..b6df0314aa02 100644
--- a/include/net/ipv6.h
+++ b/include/net/ipv6.h
@@ -467,6 +467,39 @@ bool ipv6_opt_accepted(const struct sock *sk, const struct sk_buff *skb,
 struct ipv6_txoptions *ipv6_update_options(struct sock *sk,
 					   struct ipv6_txoptions *opt);
 
+/* This helper is specialized for BIG TCP needs.
+ * It assumes the hop_jumbo_hdr will immediately follow the IPV6 header.
+ * It assumes headers are already in skb->head.
+ * Returns 0, or IPPROTO_TCP if a BIG TCP packet is there.
+ */
+static inline int ipv6_has_hopopt_jumbo(const struct sk_buff *skb)
+{
+	const struct hop_jumbo_hdr *jhdr;
+	const struct ipv6hdr *nhdr;
+
+	if (likely(skb->len <= GRO_MAX_SIZE))
+		return 0;
+
+	if (skb->protocol != htons(ETH_P_IPV6))
+		return 0;
+
+	if (skb_network_offset(skb) +
+	    sizeof(struct ipv6hdr) +
+	    sizeof(struct hop_jumbo_hdr) > skb_headlen(skb))
+		return 0;
+
+	nhdr = ipv6_hdr(skb);
+
+	if (nhdr->nexthdr != NEXTHDR_HOP)
+		return 0;
+
+	jhdr = (const struct hop_jumbo_hdr *) (nhdr + 1);
+	if (jhdr->tlv_type != IPV6_TLV_JUMBO || jhdr->hdrlen != 0 ||
+	    jhdr->nexthdr != IPPROTO_TCP)
+		return 0;
+	return jhdr->nexthdr;
+}
+
 static inline bool ipv6_accept_ra(struct inet6_dev *idev)
 {
 	/* If forwarding is enabled, RA are not accepted unless the special
diff --git a/net/ipv6/ip6_offload.c b/net/ipv6/ip6_offload.c
index c4fc03c1ac99..a6a6c1539c28 100644
--- a/net/ipv6/ip6_offload.c
+++ b/net/ipv6/ip6_offload.c
@@ -77,7 +77,7 @@ static struct sk_buff *ipv6_gso_segment(struct sk_buff *skb,
 	struct sk_buff *segs = ERR_PTR(-EINVAL);
 	struct ipv6hdr *ipv6h;
 	const struct net_offload *ops;
-	int proto;
+	int proto, nexthdr;
 	struct frag_hdr *fptr;
 	unsigned int payload_len;
 	u8 *prevhdr;
@@ -87,6 +87,28 @@ static struct sk_buff *ipv6_gso_segment(struct sk_buff *skb,
 	bool gso_partial;
 
 	skb_reset_network_header(skb);
+	nexthdr = ipv6_has_hopopt_jumbo(skb);
+	if (nexthdr) {
+		const int hophdr_len = sizeof(struct hop_jumbo_hdr);
+		int err;
+
+		err = skb_cow_head(skb, 0);
+		if (err < 0)
+			return ERR_PTR(err);
+
+		/* remove the HBH header.
+		 * Layout: [Ethernet header][IPv6 header][HBH][TCP header]
+		 */
+		memmove(skb_mac_header(skb) + hophdr_len,
+			skb_mac_header(skb),
+			ETH_HLEN + sizeof(struct ipv6hdr));
+		skb->data += hophdr_len;
+		skb->len -= hophdr_len;
+		skb->network_header += hophdr_len;
+		skb->mac_header += hophdr_len;
+		ipv6h = (struct ipv6hdr *)skb->data;
+		ipv6h->nexthdr = nexthdr;
+	}
 	nhoff = skb_network_header(skb) - skb_mac_header(skb);
 	if (unlikely(!pskb_may_pull(skb, sizeof(*ipv6h))))
 		goto out;