Commit 8e08bb75 authored Jan 28, 2023 by Xin Long Committed by Jakub Kicinski Feb 01, 2023

packet: add TP_STATUS_GSO_TCP for tp_status



Introduce TP_STATUS_GSO_TCP tp_status flag to tell the af_packet user
that this is a TCP GSO packet. When parsing IPv4 BIG TCP packets in
tcpdump/libpcap, it can use tp_len as the IPv4 packet len when this
flag is set, as iph tot_len is set to 0 for IPv4 BIG TCP packets.

Signed-off-by: Xin Long <lucien.xin@gmail.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

parent 50e6fb5c

include/uapi/linux/if_packet.h

+1 −0

Original line number	Diff line number	Diff line
		@@ -115,6 +115,7 @@ struct tpacket_auxdata {
		#define TP_STATUS_BLK_TMO (1 << 5)
		#define TP_STATUS_VLAN_TPID_VALID (1 << 6) /* auxdata has valid tp_vlan_tpid */
		#define TP_STATUS_CSUM_VALID (1 << 7)
		#define TP_STATUS_GSO_TCP (1 << 8)

		/* Tx ring - header status */
		#define TP_STATUS_AVAILABLE 0

net/packet/af_packet.c

+4 −0

Original line number	Diff line number	Diff line
		@@ -2296,6 +2296,8 @@ static int tpacket_rcv(struct sk_buff skb, struct net_device dev,
		else if (skb->pkt_type != PACKET_OUTGOING &&
		skb_csum_unnecessary(skb))
		status \|= TP_STATUS_CSUM_VALID;
		if (skb_is_gso(skb) && skb_is_gso_tcp(skb))
		status \|= TP_STATUS_GSO_TCP;

		if (snaplen > res)
		snaplen = res;
		@@ -3522,6 +3524,8 @@ static int packet_recvmsg(struct socket sock, struct msghdr msg, size_t len,
		else if (skb->pkt_type != PACKET_OUTGOING &&
		skb_csum_unnecessary(skb))
		aux.tp_status \|= TP_STATUS_CSUM_VALID;
		if (skb_is_gso(skb) && skb_is_gso_tcp(skb))
		aux.tp_status \|= TP_STATUS_GSO_TCP;

		aux.tp_len = origlen;
		aux.tp_snaplen = skb->len;