[PATCH net-next v2 05/12] net-timestamp: add bpf infrastructure to allow exposing timestamp later

[Jason Xing <kerneljasonxing@xxxxxxxxx>]

From: Jason Xing <kernelxing@xxxxxxxxxxx>

Implement basic codes so that we later can easily add each tx points.
Introducing BPF_SOCK_OPS_ALL_CB_FLAGS used as a test statement can help
use control whether to output or not.

Signed-off-by: Jason Xing <kernelxing@xxxxxxxxxxx>
---
 include/uapi/linux/bpf.h       | 5 ++++-
 net/core/skbuff.c              | 8 ++++++++
 tools/include/uapi/linux/bpf.h | 5 ++++-
 3 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index c6cd7c7aeeee..157e139ed6fc 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -6900,8 +6900,11 @@ enum {
 	 * options first before the BPF program does.
 	 */
 	BPF_SOCK_OPS_WRITE_HDR_OPT_CB_FLAG = (1<<6),
+	/* Call bpf when the kernel is generating tx timestamps.
+	 */
+	BPF_SOCK_OPS_TX_TIMESTAMPING_OPT_CB_FLAG = (1<<7),
 /* Mask of all currently supported cb flags */
-	BPF_SOCK_OPS_ALL_CB_FLAGS       = 0x7F,
+	BPF_SOCK_OPS_ALL_CB_FLAGS       = 0xFF,
 };
 
 /* List of known BPF sock_ops operators.
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index d0f912f1ff7b..3a4110d0f983 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -5621,11 +5621,19 @@ static void skb_tstamp_tx_output(struct sk_buff *orig_skb,
 
 static void bpf_skb_tstamp_tx_output(struct sock *sk, int tstype)
 {
+	struct tcp_sock *tp;
 	u32 tsflags;
 
+	if (!sk_is_tcp(sk))
+		return;
+
 	tsflags = READ_ONCE(sk->sk_tsflags[BPFPROG_TS_REQUESTOR]);
 	if (!sk_tstamp_tx_flags(sk, tsflags, tstype))
 		return;
+
+	tp = tcp_sk(sk);
+	if (BPF_SOCK_OPS_TEST_FLAG(tp, BPF_SOCK_OPS_TX_TIMESTAMPING_OPT_CB_FLAG))
+		return;
 }
 
 void __skb_tstamp_tx(struct sk_buff *orig_skb,
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index 1fb3cb2636e6..93853d9d4922 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -6899,8 +6899,11 @@ enum {
 	 * options first before the BPF program does.
 	 */
 	BPF_SOCK_OPS_WRITE_HDR_OPT_CB_FLAG = (1<<6),
+	/* Call bpf when the kernel is generating tx timestamps.
+	 */
+	BPF_SOCK_OPS_TX_TIMESTAMPING_OPT_CB_FLAG = (1<<7),
 /* Mask of all currently supported cb flags */
-	BPF_SOCK_OPS_ALL_CB_FLAGS       = 0x7F,
+	BPF_SOCK_OPS_ALL_CB_FLAGS       = 0xFF,
 };
 
 /* List of known BPF sock_ops operators.
-- 
2.37.3