Commit b2936b4f authored by Alice Mikityanska's avatar Alice Mikityanska Committed by Jakub Kicinski
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net/ipv6: Introduce payload_len helpers 



The next commits will transition away from using the hop-by-hop
extension header to encode packet length for BIG TCP. Add wrappers
around ip6->payload_len that return the actual value if it's non-zero,
and calculate it from skb->len if payload_len is set to zero (and a
symmetrical setter).

The new helpers are used wherever the surrounding code supports the
hop-by-hop jumbo header for BIG TCP IPv6, or the corresponding IPv4 code
uses skb_ip_totlen (e.g., in include/net/netfilter/nf_tables_ipv6.h).

No behavioral change in this commit.

Signed-off-by: default avatarAlice Mikityanska <alice@isovalent.com>
Acked-by: default avatarPaolo Abeni <pabeni@redhat.com>
Reviewed-by: default avatarEric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20260205133925.526371-2-alice.kernel@fastmail.im


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent 5826eec8

include/linux/ipv6.h

+22 −0
Original line number Diff line number Diff line
@@ -126,6 +126,28 @@ static inline unsigned int ipv6_transport_len(const struct sk_buff *skb) 
	       skb_network_header_len(skb);

}



static inline unsigned int

ipv6_payload_len(const struct sk_buff *skb, const struct ipv6hdr *ip6)

{

	u32 len = ntohs(ip6->payload_len);



	return (len || !skb_is_gso(skb) || !skb_is_gso_tcp(skb)) ?

		len :

		skb->len - skb_network_offset(skb) - sizeof(struct ipv6hdr);

}



static inline unsigned int skb_ipv6_payload_len(const struct sk_buff *skb)

{

	return ipv6_payload_len(skb, ipv6_hdr(skb));

}



#define IPV6_MAXPLEN		65535



static inline void ipv6_set_payload_len(struct ipv6hdr *ip6, unsigned int len)

{

	ip6->payload_len = len <= IPV6_MAXPLEN ? htons(len) : 0;

}



/* 

   This structure contains results of exthdrs parsing

   as offsets from skb->nh.

include/net/ipv6.h

+0 −2
Original line number Diff line number Diff line
@@ -25,8 +25,6 @@ struct ip_tunnel_info; 


#define SIN6_LEN_RFC2133	24



#define IPV6_MAXPLEN		65535



/*

 *	NextHeader field of IPv6 header

 */

include/net/netfilter/nf_tables_ipv6.h

+2 −2
Original line number Diff line number Diff line
@@ -42,7 +42,7 @@ static inline int __nft_set_pktinfo_ipv6_validate(struct nft_pktinfo *pkt) 
	if (ip6h->version != 6)

		return -1;



	pkt_len = ntohs(ip6h->payload_len);

	pkt_len = ipv6_payload_len(pkt->skb, ip6h);

	skb_len = pkt->skb->len - skb_network_offset(pkt->skb);

	if (pkt_len + sizeof(*ip6h) > skb_len)

		return -1;
@@ -86,7 +86,7 @@ static inline int nft_set_pktinfo_ipv6_ingress(struct nft_pktinfo *pkt) 
	if (ip6h->version != 6)

		goto inhdr_error;



	pkt_len = ntohs(ip6h->payload_len);

	pkt_len = ipv6_payload_len(pkt->skb, ip6h);

	if (pkt_len + sizeof(*ip6h) > pkt->skb->len) {

		idev = __in6_dev_get(nft_in(pkt));

		__IP6_INC_STATS(nft_net(pkt), idev, IPSTATS_MIB_INTRUNCATEDPKTS);

net/bridge/br_netfilter_ipv6.c

+1 −1
Original line number Diff line number Diff line
@@ -58,7 +58,7 @@ int br_validate_ipv6(struct net *net, struct sk_buff *skb) 
	if (hdr->version != 6)

		goto inhdr_error;



	pkt_len = ntohs(hdr->payload_len);

	pkt_len = ipv6_payload_len(skb, hdr);

	if (hdr->nexthdr == NEXTHDR_HOP && nf_ip6_check_hbh_len(skb, &pkt_len))

		goto drop;

net/bridge/netfilter/nf_conntrack_bridge.c

+2 −2
Original line number Diff line number Diff line
@@ -229,7 +229,7 @@ static int nf_ct_br_ipv6_check(const struct sk_buff *skb) 
	if (hdr->version != 6)

		return -1;



	len = ntohs(hdr->payload_len) + sizeof(struct ipv6hdr) + nhoff;

	len = ipv6_payload_len(skb, hdr) + sizeof(struct ipv6hdr) + nhoff;

	if (skb->len < len)

		return -1;
@@ -269,7 +269,7 @@ static unsigned int nf_ct_bridge_pre(void *priv, struct sk_buff *skb, 
		if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))

			return NF_ACCEPT;



		len = sizeof(struct ipv6hdr) + ntohs(ipv6_hdr(skb)->payload_len);

		len = sizeof(struct ipv6hdr) + skb_ipv6_payload_len(skb);

		if (pskb_trim_rcsum(skb, len))

			return NF_ACCEPT;