From 27942a15209f564ed8ee2a9e126cb7b105181355 Mon Sep 17 00:00:00 2001 From: Martin KaFai Lau Date: Wed, 2 Mar 2022 11:55:38 -0800 Subject: net: Handle delivery_time in skb->tstamp during network tapping with af_packet A latter patch will set the skb->mono_delivery_time to flag the skb->tstamp is used as the mono delivery_time (EDT) instead of the (rcv) timestamp. skb_clear_tstamp() will then keep this delivery_time during forwarding. This patch is to make the network tapping (with af_packet) to handle the delivery_time stored in skb->tstamp. Regardless of tapping at the ingress or egress, the tapped skb is received by the af_packet socket, so it is ingress to the af_packet socket and it expects the (rcv) timestamp. When tapping at egress, dev_queue_xmit_nit() is used. It has already expected skb->tstamp may have delivery_time, so it does skb_clone()+net_timestamp_set() to ensure the cloned skb has the (rcv) timestamp before passing to the af_packet sk. This patch only adds to clear the skb->mono_delivery_time bit in net_timestamp_set(). When tapping at ingress, it currently expects the skb->tstamp is either 0 or the (rcv) timestamp. Meaning, the tapping at ingress path has already expected the skb->tstamp could be 0 and it will get the (rcv) timestamp by ktime_get_real() when needed. There are two cases for tapping at ingress: One case is af_packet queues the skb to its sk_receive_queue. The skb is either not shared or new clone created. The newly added skb_clear_delivery_time() is called to clear the delivery_time (if any) and set the (rcv) timestamp if needed before the skb is queued to the sk_receive_queue. Another case, the ingress skb is directly copied to the rx_ring and tpacket_get_timestamp() is used to get the (rcv) timestamp. The newly added skb_tstamp() is used in tpacket_get_timestamp() to check the skb->mono_delivery_time bit before returning skb->tstamp. As mentioned earlier, the tapping@ingress has already expected the skb may not have the (rcv) timestamp (because no sk has asked for it) and has handled this case by directly calling ktime_get_real(). Signed-off-by: Martin KaFai Lau Signed-off-by: David S. Miller --- net/packet/af_packet.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'net/packet/af_packet.c') diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c index ab87f22cc7ec..1b93ce1a5600 100644 --- a/net/packet/af_packet.c +++ b/net/packet/af_packet.c @@ -460,7 +460,7 @@ static __u32 tpacket_get_timestamp(struct sk_buff *skb, struct timespec64 *ts, return TP_STATUS_TS_RAW_HARDWARE; if ((flags & SOF_TIMESTAMPING_SOFTWARE) && - ktime_to_timespec64_cond(skb->tstamp, ts)) + ktime_to_timespec64_cond(skb_tstamp(skb), ts)) return TP_STATUS_TS_SOFTWARE; return 0; @@ -2199,6 +2199,7 @@ static int packet_rcv(struct sk_buff *skb, struct net_device *dev, spin_lock(&sk->sk_receive_queue.lock); po->stats.stats1.tp_packets++; sock_skb_set_dropcount(sk, skb); + skb_clear_delivery_time(skb); __skb_queue_tail(&sk->sk_receive_queue, skb); spin_unlock(&sk->sk_receive_queue.lock); sk->sk_data_ready(sk); @@ -2377,6 +2378,7 @@ static int tpacket_rcv(struct sk_buff *skb, struct net_device *dev, po->stats.stats1.tp_packets++; if (copy_skb) { status |= TP_STATUS_COPY; + skb_clear_delivery_time(copy_skb); __skb_queue_tail(&sk->sk_receive_queue, copy_skb); } spin_unlock(&sk->sk_receive_queue.lock); -- cgit