[PATCH net-next v4 04/11] net-timestamp: support SCM_TSTAMP_SCHED for bpf extension

[Jason Xing <kerneljasonxing@gmail.com>]

From: Jason Xing <kernelxing@tencent.com>

Introducing SKBTX_BPF is used as an indicator telling us whether
the skb should be traced by the bpf prog.

Signed-off-by: Jason Xing <kernelxing@tencent.com>
---
 include/linux/skbuff.h         |  6 +++++-
 include/uapi/linux/bpf.h       |  5 +++++
 net/core/skbuff.c              | 29 ++++++++++++++++++++++++++---
 tools/include/uapi/linux/bpf.h |  5 +++++
 4 files changed, 41 insertions(+), 4 deletions(-)

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 53c6913560e4..af22c8326ca5 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -490,10 +490,14 @@ enum {
 
 	/* generate software time stamp when entering packet scheduling */
 	SKBTX_SCHED_TSTAMP = 1 << 6,
+
+	/* used for bpf extension when a bpf program is loaded */
+	SKBTX_BPF = 1 << 7,
 };
 
 #define SKBTX_ANY_SW_TSTAMP	(SKBTX_SW_TSTAMP    | \
-				 SKBTX_SCHED_TSTAMP)
+				 SKBTX_SCHED_TSTAMP	| \
+				 SKBTX_BPF)
 #define SKBTX_ANY_TSTAMP	(SKBTX_HW_TSTAMP | \
 				 SKBTX_HW_TSTAMP_USE_CYCLES | \
 				 SKBTX_ANY_SW_TSTAMP)
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index e629e09b0b31..72f93c6e45c1 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -7022,6 +7022,11 @@ enum {
 					 * by the kernel or the
 					 * earlier bpf-progs.
 					 */
+	BPF_SOCK_OPS_TS_SCHED_OPT_CB,	/* Called when skb is passing through
+					 * dev layer when SO_TIMESTAMPING
+					 * feature is on. It indicates the
+					 * recorded timestamp.
+					 */
 };
 
 /* List of TCP states. There is a build check in net/ipv4/tcp.c to detect
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 74b840ffaf94..fd4f06b88a2e 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -5539,6 +5539,24 @@ void skb_complete_tx_timestamp(struct sk_buff *skb,
 }
 EXPORT_SYMBOL_GPL(skb_complete_tx_timestamp);
 
+static void __skb_tstamp_tx_bpf(struct sock *sk, struct sk_buff *skb, int tstype)
+{
+	int op;
+
+	if (!sk)
+		return;
+
+	switch (tstype) {
+	case SCM_TSTAMP_SCHED:
+		op = BPF_SOCK_OPS_TS_SCHED_OPT_CB;
+		break;
+	default:
+		return;
+	}
+
+	bpf_skops_tx_timestamping(sk, skb, op);
+}
+
 static void skb_tstamp_tx_output(struct sk_buff *orig_skb,
 				 const struct sk_buff *ack_skb,
 				 struct skb_shared_hwtstamps *hwtstamps,
@@ -5595,11 +5613,14 @@ static void skb_tstamp_tx_output(struct sk_buff *orig_skb,
 	__skb_complete_tx_timestamp(skb, sk, tstype, opt_stats);
 }
 
-static bool skb_tstamp_is_set(const struct sk_buff *skb, int tstype)
+static bool skb_tstamp_is_set(const struct sk_buff *skb, int tstype, bool bpf_mode)
 {
+	int flag;
+
 	switch (tstype) {
 	case SCM_TSTAMP_SCHED:
-		if (unlikely(skb_shinfo(skb)->tx_flags & SKBTX_SCHED_TSTAMP))
+		flag = bpf_mode ? SKBTX_BPF : SKBTX_SCHED_TSTAMP;
+		if (unlikely(skb_shinfo(skb)->tx_flags & flag))
 			return true;
 		return false;
 	case SCM_TSTAMP_SND:
@@ -5620,8 +5641,10 @@ void __skb_tstamp_tx(struct sk_buff *orig_skb,
 		     struct skb_shared_hwtstamps *hwtstamps,
 		     struct sock *sk, int tstype)
 {
-	if (unlikely(skb_tstamp_is_set(orig_skb, tstype)))
+	if (unlikely(skb_tstamp_is_set(orig_skb, tstype, false)))
 		skb_tstamp_tx_output(orig_skb, ack_skb, hwtstamps, sk, tstype);
+	if (unlikely(skb_tstamp_is_set(orig_skb, tstype, true)))
+		__skb_tstamp_tx_bpf(sk, orig_skb, tstype);
 }
 EXPORT_SYMBOL_GPL(__skb_tstamp_tx);
 
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index 6b0a5b787b12..891217ab6d2d 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -7015,6 +7015,11 @@ enum {
 					 * by the kernel or the
 					 * earlier bpf-progs.
 					 */
+	BPF_SOCK_OPS_TS_SCHED_OPT_CB,	/* Called when skb is passing through
+					 * dev layer when SO_TIMESTAMPING
+					 * feature is on. It indicates the
+					 * recorded timestamp.
+					 */
 };
 
 /* List of TCP states. There is a build check in net/ipv4/tcp.c to detect
-- 
2.37.3