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Commit 682f048b authored by Alexander Drozdov's avatar Alexander Drozdov Committed by David S. Miller
Browse files

af_packet: pass checksum validation status to the user 



Introduce TP_STATUS_CSUM_VALID tp_status flag to tell the
af_packet user that at least the transport header checksum
has been already validated.

For now, the flag may be set for incoming packets only.

Signed-off-by: default avatarAlexander Drozdov <al.drozdov@gmail.com>
Cc: Willem de Bruijn <willemb@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 68c2e5de

Documentation/networking/packet_mmap.txt

+10 −3
Original line number Diff line number Diff line
@@ -440,9 +440,10 @@ and the following flags apply: 
+++ Capture process:

     from include/linux/if_packet.h



     #define TP_STATUS_COPY          2 

     #define TP_STATUS_LOSING        4 

     #define TP_STATUS_CSUMNOTREADY  8 

     #define TP_STATUS_COPY          (1 << 1)

     #define TP_STATUS_LOSING        (1 << 2)

     #define TP_STATUS_CSUMNOTREADY  (1 << 3)

     #define TP_STATUS_CSUM_VALID    (1 << 7)



TP_STATUS_COPY        : This flag indicates that the frame (and associated

                        meta information) has been truncated because it's
@@ -466,6 +467,12 @@ TP_STATUS_CSUMNOTREADY: currently it's used for outgoing IP packets which 
                        reading the packet we should not try to check the 

                        checksum. 



TP_STATUS_CSUM_VALID  : This flag indicates that at least the transport

                        header checksum of the packet has been already

                        validated on the kernel side. If the flag is not set

                        then we are free to check the checksum by ourselves

                        provided that TP_STATUS_CSUMNOTREADY is also not set.



for convenience there are also the following defines:



     #define TP_STATUS_KERNEL        0

include/uapi/linux/if_packet.h

+1 −0
Original line number Diff line number Diff line
@@ -99,6 +99,7 @@ struct tpacket_auxdata { 
#define TP_STATUS_VLAN_VALID		(1 << 4) /* auxdata has valid tp_vlan_tci */

#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)



/* Tx ring - header status */

#define TP_STATUS_AVAILABLE	      0

net/packet/af_packet.c

+9 −0
Original line number Diff line number Diff line
@@ -1924,6 +1924,10 @@ static int tpacket_rcv(struct sk_buff *skb, struct net_device *dev, 


	if (skb->ip_summed == CHECKSUM_PARTIAL)

		status |= TP_STATUS_CSUMNOTREADY;

	else if (skb->pkt_type != PACKET_OUTGOING &&

		 (skb->ip_summed == CHECKSUM_COMPLETE ||

		  skb_csum_unnecessary(skb)))

		status |= TP_STATUS_CSUM_VALID;



	if (snaplen > res)

		snaplen = res;
@@ -3031,6 +3035,11 @@ static int packet_recvmsg(struct socket *sock, struct msghdr *msg, size_t len, 
		aux.tp_status = TP_STATUS_USER;

		if (skb->ip_summed == CHECKSUM_PARTIAL)

			aux.tp_status |= TP_STATUS_CSUMNOTREADY;

		else if (skb->pkt_type != PACKET_OUTGOING &&

			 (skb->ip_summed == CHECKSUM_COMPLETE ||

			  skb_csum_unnecessary(skb)))

			aux.tp_status |= TP_STATUS_CSUM_VALID;



		aux.tp_len = origlen;

		aux.tp_snaplen = skb->len;

		aux.tp_mac = 0;