packet_mmap: expose hw packet timestamps to network packet capture utilities

This patch adds a setting, PACKET_TIMESTAMP, to specify the packet
timestamp source that is exported to capture utilities like tcpdump by
packet_mmap.

PACKET_TIMESTAMP accepts the same integer bit field as
SO_TIMESTAMPING.  However, only the SOF_TIMESTAMPING_SYS_HARDWARE and
SOF_TIMESTAMPING_RAW_HARDWARE values are currently recognized by
PACKET_TIMESTAMP.  SOF_TIMESTAMPING_SYS_HARDWARE takes precedence over
SOF_TIMESTAMPING_RAW_HARDWARE if both bits are set.

If PACKET_TIMESTAMP is not set, a software timestamp generated inside
the networking stack is used (the behavior before this setting was
added).

Signed-off-by: Scott McMillan <scott.a.mcmillan@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 35 insertions, 2 deletions

diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index 2078a27..9a17f28 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -83,6 +83,7 @@
 #include <linux/if_vlan.h>
 #include <linux/virtio_net.h>
 #include <linux/errqueue.h>
+#include <linux/net_tstamp.h>
 
 #ifdef CONFIG_INET
 #include <net/inet_common.h>
@@ -202,6 +203,7 @@ struct packet_sock {
 	unsigned int		tp_hdrlen;
 	unsigned int		tp_reserve;
 	unsigned int		tp_loss:1;
+	unsigned int		tp_tstamp;
 	struct packet_type	prot_hook ____cacheline_aligned_in_smp;
 };
 
@@ -656,6 +658,7 @@ static int tpacket_rcv(struct sk_buff *skb, struct net_device *dev,
 	struct sk_buff *copy_skb = NULL;
 	struct timeval tv;
 	struct timespec ts;
+	struct skb_shared_hwtstamps *shhwtstamps = skb_hwtstamps(skb);
 
 	if (skb->pkt_type == PACKET_LOOPBACK)
 		goto drop;
@@ -737,7 +740,13 @@ static int tpacket_rcv(struct sk_buff *skb, struct net_device *dev,
 		h.h1->tp_snaplen = snaplen;
 		h.h1->tp_mac = macoff;
 		h.h1->tp_net = netoff;
-		if (skb->tstamp.tv64)
+		if ((po->tp_tstamp & SOF_TIMESTAMPING_SYS_HARDWARE)
+				&& shhwtstamps->syststamp.tv64)
+			tv = ktime_to_timeval(shhwtstamps->syststamp);
+		else if ((po->tp_tstamp & SOF_TIMESTAMPING_RAW_HARDWARE)
+				&& shhwtstamps->hwtstamp.tv64)
+			tv = ktime_to_timeval(shhwtstamps->hwtstamp);
+		else if (skb->tstamp.tv64)
 			tv = ktime_to_timeval(skb->tstamp);
 		else
 			do_gettimeofday(&tv);
@@ -750,7 +759,13 @@ static int tpacket_rcv(struct sk_buff *skb, struct net_device *dev,
 		h.h2->tp_snaplen = snaplen;
 		h.h2->tp_mac = macoff;
 		h.h2->tp_net = netoff;
-		if (skb->tstamp.tv64)
+		if ((po->tp_tstamp & SOF_TIMESTAMPING_SYS_HARDWARE)
+				&& shhwtstamps->syststamp.tv64)
+			ts = ktime_to_timespec(shhwtstamps->syststamp);
+		else if ((po->tp_tstamp & SOF_TIMESTAMPING_RAW_HARDWARE)
+				&& shhwtstamps->hwtstamp.tv64)
+			ts = ktime_to_timespec(shhwtstamps->hwtstamp);
+		else if (skb->tstamp.tv64)
 			ts = ktime_to_timespec(skb->tstamp);
 		else
 			getnstimeofday(&ts);
@@ -2027,6 +2042,18 @@ packet_setsockopt(struct socket *sock, int level, int optname, char __user *optv
 		po->has_vnet_hdr = !!val;
 		return 0;
 	}
+	case PACKET_TIMESTAMP:
+	{
+		int val;
+
+		if (optlen != sizeof(val))
+			return -EINVAL;
+		if (copy_from_user(&val, optval, sizeof(val)))
+			return -EFAULT;
+
+		po->tp_tstamp = val;
+		return 0;
+	}
 	default:
 		return -ENOPROTOOPT;
 	}
@@ -2119,6 +2146,12 @@ static int packet_getsockopt(struct socket *sock, int level, int optname,
 		val = po->tp_loss;
 		data = &val;
 		break;
+	case PACKET_TIMESTAMP:
+		if (len > sizeof(int))
+			len = sizeof(int);
+		val = po->tp_tstamp;
+		data = &val;
+		break;
 	default:
 		return -ENOPROTOOPT;
 	}