Commit 80e425b6 authored by Coco Li's avatar Coco Li Committed by David S. Miller
Browse files

ipv6: Add hop-by-hop header to jumbograms in ip6_output 



Instead of simply forcing a 0 payload_len in IPv6 header,
implement RFC 2675 and insert a custom extension header.

Note that only TCP stack is currently potentially generating
jumbograms, and that this extension header is purely local,
it wont be sent on a physical link.

This is needed so that packet capture (tcpdump and friends)
can properly dissect these large packets.

Signed-off-by: default avatarCoco Li <lixiaoyan@google.com>
Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Acked-by: default avatarAlexander Duyck <alexanderduyck@fb.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 0fe79f28

include/linux/ipv6.h

+1 −0
Original line number Diff line number Diff line
@@ -145,6 +145,7 @@ struct inet6_skb_parm { 
#define IP6SKB_L3SLAVE         64

#define IP6SKB_JUMBOGRAM      128

#define IP6SKB_SEG6	      256

#define IP6SKB_FAKEJUMBO      512

};



#if defined(CONFIG_NET_L3_MASTER_DEV)

net/ipv6/ip6_output.c

+20 −2
Original line number Diff line number Diff line
@@ -182,7 +182,9 @@ static int __ip6_finish_output(struct net *net, struct sock *sk, struct sk_buff 
#endif



	mtu = ip6_skb_dst_mtu(skb);

	if (skb_is_gso(skb) && !skb_gso_validate_network_len(skb, mtu))

	if (skb_is_gso(skb) &&

	    !(IP6CB(skb)->flags & IP6SKB_FAKEJUMBO) &&

	    !skb_gso_validate_network_len(skb, mtu))

		return ip6_finish_output_gso_slowpath_drop(net, sk, skb, mtu);



	if ((skb->len > mtu && !skb_is_gso(skb)) ||
@@ -252,6 +254,8 @@ int ip6_xmit(const struct sock *sk, struct sk_buff *skb, struct flowi6 *fl6, 
	struct dst_entry *dst = skb_dst(skb);

	struct net_device *dev = dst->dev;

	struct inet6_dev *idev = ip6_dst_idev(dst);

	struct hop_jumbo_hdr *hop_jumbo;

	int hoplen = sizeof(*hop_jumbo);

	unsigned int head_room;

	struct ipv6hdr *hdr;

	u8  proto = fl6->flowi6_proto;
@@ -259,7 +263,7 @@ int ip6_xmit(const struct sock *sk, struct sk_buff *skb, struct flowi6 *fl6, 
	int hlimit = -1;

	u32 mtu;



	head_room = sizeof(struct ipv6hdr) + LL_RESERVED_SPACE(dev);

	head_room = sizeof(struct ipv6hdr) + hoplen + LL_RESERVED_SPACE(dev);

	if (opt)

		head_room += opt->opt_nflen + opt->opt_flen;
@@ -282,6 +286,20 @@ int ip6_xmit(const struct sock *sk, struct sk_buff *skb, struct flowi6 *fl6, 
					     &fl6->saddr);

	}



	if (unlikely(seg_len > IPV6_MAXPLEN)) {

		hop_jumbo = skb_push(skb, hoplen);



		hop_jumbo->nexthdr = proto;

		hop_jumbo->hdrlen = 0;

		hop_jumbo->tlv_type = IPV6_TLV_JUMBO;

		hop_jumbo->tlv_len = 4;

		hop_jumbo->jumbo_payload_len = htonl(seg_len + hoplen);



		proto = IPPROTO_HOPOPTS;

		seg_len = 0;

		IP6CB(skb)->flags |= IP6SKB_FAKEJUMBO;

	}



	skb_push(skb, sizeof(struct ipv6hdr));

	skb_reset_network_header(skb);

	hdr = ipv6_hdr(skb);