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: Alexander Drozdov <al.drozdov@gmail.com>
Cc: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 9 insertions, 0 deletions

diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index 9d854c5ce0b5..5102c3cc4eec 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -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;