From 24e82b7c045ba5afde5bd81f691b7a72283de35e Mon Sep 17 00:00:00 2001
From: Jason Xing <kerneljasonxing@gmail.com>
Date: Thu, 20 Feb 2025 15:29:29 +0800
Subject: [PATCH 01/12] bpf: Add networking timestamping support to
 bpf_get/setsockopt()

The new SK_BPF_CB_FLAGS and new SK_BPF_CB_TX_TIMESTAMPING are
added to bpf_get/setsockopt. The later patches will implement the
BPF networking timestamping. The BPF program will use
bpf_setsockopt(SK_BPF_CB_FLAGS, SK_BPF_CB_TX_TIMESTAMPING) to
enable the BPF networking timestamping on a socket.

Signed-off-by: Jason Xing <kerneljasonxing@gmail.com>
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Link: https://patch.msgid.link/20250220072940.99994-2-kerneljasonxing@gmail.com
---
 include/net/sock.h             |  3 +++
 include/uapi/linux/bpf.h       |  7 +++++++
 net/core/filter.c              | 23 +++++++++++++++++++++++
 tools/include/uapi/linux/bpf.h |  7 +++++++
 4 files changed, 40 insertions(+)

diff --git a/include/net/sock.h b/include/net/sock.h
index 60ebf3c7b229..a95eedacae76 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -303,6 +303,7 @@ struct sk_filter;
   *	@sk_stamp: time stamp of last packet received
   *	@sk_stamp_seq: lock for accessing sk_stamp on 32 bit architectures only
   *	@sk_tsflags: SO_TIMESTAMPING flags
+  *	@sk_bpf_cb_flags: used in bpf_setsockopt()
   *	@sk_use_task_frag: allow sk_page_frag() to use current->task_frag.
   *			   Sockets that can be used under memory reclaim should
   *			   set this to false.
@@ -525,6 +526,8 @@ struct sock {
 	u8			sk_txtime_deadline_mode : 1,
 				sk_txtime_report_errors : 1,
 				sk_txtime_unused : 6;
+#define SK_BPF_CB_FLAG_TEST(SK, FLAG) ((SK)->sk_bpf_cb_flags & (FLAG))
+	u8			sk_bpf_cb_flags;
 
 	void			*sk_user_data;
 #ifdef CONFIG_SECURITY
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 2acf9b336371..4e0632848440 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -6913,6 +6913,12 @@ enum {
 	BPF_SOCK_OPS_ALL_CB_FLAGS       = 0x7F,
 };
 
+enum {
+	SK_BPF_CB_TX_TIMESTAMPING	= 1<<0,
+	SK_BPF_CB_MASK			= (SK_BPF_CB_TX_TIMESTAMPING - 1) |
+					   SK_BPF_CB_TX_TIMESTAMPING
+};
+
 /* List of known BPF sock_ops operators.
  * New entries can only be added at the end
  */
@@ -7091,6 +7097,7 @@ enum {
 	TCP_BPF_SYN_IP		= 1006, /* Copy the IP[46] and TCP header */
 	TCP_BPF_SYN_MAC         = 1007, /* Copy the MAC, IP[46], and TCP header */
 	TCP_BPF_SOCK_OPS_CB_FLAGS = 1008, /* Get or Set TCP sock ops flags */
+	SK_BPF_CB_FLAGS		= 1009, /* Get or set sock ops flags in socket */
 };
 
 enum {
diff --git a/net/core/filter.c b/net/core/filter.c
index ffec7b4357f9..5b7e44dfc037 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -5222,6 +5222,25 @@ static const struct bpf_func_proto bpf_get_socket_uid_proto = {
 	.arg1_type      = ARG_PTR_TO_CTX,
 };
 
+static int sk_bpf_set_get_cb_flags(struct sock *sk, char *optval, bool getopt)
+{
+	u32 sk_bpf_cb_flags;
+
+	if (getopt) {
+		*(u32 *)optval = sk->sk_bpf_cb_flags;
+		return 0;
+	}
+
+	sk_bpf_cb_flags = *(u32 *)optval;
+
+	if (sk_bpf_cb_flags & ~SK_BPF_CB_MASK)
+		return -EINVAL;
+
+	sk->sk_bpf_cb_flags = sk_bpf_cb_flags;
+
+	return 0;
+}
+
 static int sol_socket_sockopt(struct sock *sk, int optname,
 			      char *optval, int *optlen,
 			      bool getopt)
@@ -5238,6 +5257,7 @@ static int sol_socket_sockopt(struct sock *sk, int optname,
 	case SO_MAX_PACING_RATE:
 	case SO_BINDTOIFINDEX:
 	case SO_TXREHASH:
+	case SK_BPF_CB_FLAGS:
 		if (*optlen != sizeof(int))
 			return -EINVAL;
 		break;
@@ -5247,6 +5267,9 @@ static int sol_socket_sockopt(struct sock *sk, int optname,
 		return -EINVAL;
 	}
 
+	if (optname == SK_BPF_CB_FLAGS)
+		return sk_bpf_set_get_cb_flags(sk, optval, getopt);
+
 	if (getopt) {
 		if (optname == SO_BINDTODEVICE)
 			return -EINVAL;
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index 2acf9b336371..4e0632848440 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -6913,6 +6913,12 @@ enum {
 	BPF_SOCK_OPS_ALL_CB_FLAGS       = 0x7F,
 };
 
+enum {
+	SK_BPF_CB_TX_TIMESTAMPING	= 1<<0,
+	SK_BPF_CB_MASK			= (SK_BPF_CB_TX_TIMESTAMPING - 1) |
+					   SK_BPF_CB_TX_TIMESTAMPING
+};
+
 /* List of known BPF sock_ops operators.
  * New entries can only be added at the end
  */
@@ -7091,6 +7097,7 @@ enum {
 	TCP_BPF_SYN_IP		= 1006, /* Copy the IP[46] and TCP header */
 	TCP_BPF_SYN_MAC         = 1007, /* Copy the MAC, IP[46], and TCP header */
 	TCP_BPF_SOCK_OPS_CB_FLAGS = 1008, /* Get or Set TCP sock ops flags */
+	SK_BPF_CB_FLAGS		= 1009, /* Get or set sock ops flags in socket */
 };
 
 enum {

From df600f3b1d7963e2203ebf0987f564946a2647f1 Mon Sep 17 00:00:00 2001
From: Jason Xing <kerneljasonxing@gmail.com>
Date: Thu, 20 Feb 2025 15:29:30 +0800
Subject: [PATCH 02/12] bpf: Prepare the sock_ops ctx and call bpf prog for TX
 timestamping

This patch introduces a new bpf_skops_tx_timestamping() function
that prepares the "struct bpf_sock_ops" ctx and then executes the
sockops BPF program.

The subsequent patch will utilize bpf_skops_tx_timestamping() at
the existing TX timestamping kernel callbacks (__sk_tstamp_tx
specifically) to call the sockops BPF program. Later, four callback
points to report information to user space based on this patch will
be introduced.

Signed-off-by: Jason Xing <kerneljasonxing@gmail.com>
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Link: https://patch.msgid.link/20250220072940.99994-3-kerneljasonxing@gmail.com
---
 include/net/sock.h |  7 +++++++
 net/core/sock.c    | 14 ++++++++++++++
 2 files changed, 21 insertions(+)

diff --git a/include/net/sock.h b/include/net/sock.h
index a95eedacae76..2f6b55c59c16 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -2924,6 +2924,13 @@ int sock_set_timestamping(struct sock *sk, int optname,
 			  struct so_timestamping timestamping);
 
 void sock_enable_timestamps(struct sock *sk);
+#if defined(CONFIG_CGROUP_BPF)
+void bpf_skops_tx_timestamping(struct sock *sk, struct sk_buff *skb, int op);
+#else
+static inline void bpf_skops_tx_timestamping(struct sock *sk, struct sk_buff *skb, int op)
+{
+}
+#endif
 void sock_no_linger(struct sock *sk);
 void sock_set_keepalive(struct sock *sk);
 void sock_set_priority(struct sock *sk, u32 priority);
diff --git a/net/core/sock.c b/net/core/sock.c
index a197f0a0b878..ba653c6a1229 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -949,6 +949,20 @@ int sock_set_timestamping(struct sock *sk, int optname,
 	return 0;
 }
 
+#if defined(CONFIG_CGROUP_BPF)
+void bpf_skops_tx_timestamping(struct sock *sk, struct sk_buff *skb, int op)
+{
+	struct bpf_sock_ops_kern sock_ops;
+
+	memset(&sock_ops, 0, offsetof(struct bpf_sock_ops_kern, temp));
+	sock_ops.op = op;
+	sock_ops.is_fullsock = 1;
+	sock_ops.sk = sk;
+	bpf_skops_init_skb(&sock_ops, skb, 0);
+	__cgroup_bpf_run_filter_sock_ops(sk, &sock_ops, CGROUP_SOCK_OPS);
+}
+#endif
+
 void sock_set_keepalive(struct sock *sk)
 {
 	lock_sock(sk);

From fd93eaffb3f977b23bc0a48d4c8616e654fcf133 Mon Sep 17 00:00:00 2001
From: Jason Xing <kerneljasonxing@gmail.com>
Date: Thu, 20 Feb 2025 15:29:31 +0800
Subject: [PATCH 03/12] bpf: Prevent unsafe access to the sock fields in the
 BPF timestamping callback

The subsequent patch will implement BPF TX timestamping. It will
call the sockops BPF program without holding the sock lock.

This breaks the current assumption that all sock ops programs will
hold the sock lock. The sock's fields of the uapi's bpf_sock_ops
requires this assumption.

To address this, a new "u8 is_locked_tcp_sock;" field is added. This
patch sets it in the current sock_ops callbacks. The "is_fullsock"
test is then replaced by the "is_locked_tcp_sock" test during
sock_ops_convert_ctx_access().

The new TX timestamping callbacks added in the subsequent patch will
not have this set. This will prevent unsafe access from the new
timestamping callbacks.

Potentially, we could allow read-only access. However, this would
require identifying which callback is read-safe-only and also requires
additional BPF instruction rewrites in the covert_ctx. Since the BPF
program can always read everything from a socket (e.g., by using
bpf_core_cast), this patch keeps it simple and disables all read
and write access to any socket fields through the bpf_sock_ops
UAPI from the new TX timestamping callback.

Moreover, note that some of the fields in bpf_sock_ops are specific
to tcp_sock, and sock_ops currently only supports tcp_sock. In
the future, UDP timestamping will be added, which will also break
this assumption. The same idea used in this patch will be reused.
Considering that the current sock_ops only supports tcp_sock, the
variable is named is_locked_"tcp"_sock.

Signed-off-by: Jason Xing <kerneljasonxing@gmail.com>
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Link: https://patch.msgid.link/20250220072940.99994-4-kerneljasonxing@gmail.com
---
 include/linux/filter.h | 1 +
 include/net/tcp.h      | 1 +
 net/core/filter.c      | 8 ++++----
 net/ipv4/tcp_input.c   | 2 ++
 net/ipv4/tcp_output.c  | 2 ++
 5 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/include/linux/filter.h b/include/linux/filter.h
index a3ea46281595..d36d5d5180b1 100644
--- a/include/linux/filter.h
+++ b/include/linux/filter.h
@@ -1508,6 +1508,7 @@ struct bpf_sock_ops_kern {
 	void	*skb_data_end;
 	u8	op;
 	u8	is_fullsock;
+	u8	is_locked_tcp_sock;
 	u8	remaining_opt_len;
 	u64	temp;			/* temp and everything after is not
 					 * initialized to 0 before calling
diff --git a/include/net/tcp.h b/include/net/tcp.h
index 7fd2d7fa4532..94ea09faedf4 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -2657,6 +2657,7 @@ static inline int tcp_call_bpf(struct sock *sk, int op, u32 nargs, u32 *args)
 	memset(&sock_ops, 0, offsetof(struct bpf_sock_ops_kern, temp));
 	if (sk_fullsock(sk)) {
 		sock_ops.is_fullsock = 1;
+		sock_ops.is_locked_tcp_sock = 1;
 		sock_owned_by_me(sk);
 	}
 
diff --git a/net/core/filter.c b/net/core/filter.c
index 5b7e44dfc037..7a20ddae7667 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -10382,10 +10382,10 @@ static u32 sock_ops_convert_ctx_access(enum bpf_access_type type,
 		}							      \
 		*insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(			      \
 						struct bpf_sock_ops_kern,     \
-						is_fullsock),		      \
+						is_locked_tcp_sock),	      \
 				      fullsock_reg, si->src_reg,	      \
 				      offsetof(struct bpf_sock_ops_kern,      \
-					       is_fullsock));		      \
+					       is_locked_tcp_sock));	      \
 		*insn++ = BPF_JMP_IMM(BPF_JEQ, fullsock_reg, 0, jmp);	      \
 		if (si->dst_reg == si->src_reg)				      \
 			*insn++ = BPF_LDX_MEM(BPF_DW, reg, si->src_reg,	      \
@@ -10470,10 +10470,10 @@ static u32 sock_ops_convert_ctx_access(enum bpf_access_type type,
 					       temp));			      \
 		*insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(			      \
 						struct bpf_sock_ops_kern,     \
-						is_fullsock),		      \
+						is_locked_tcp_sock),	      \
 				      reg, si->dst_reg,			      \
 				      offsetof(struct bpf_sock_ops_kern,      \
-					       is_fullsock));		      \
+					       is_locked_tcp_sock));	      \
 		*insn++ = BPF_JMP_IMM(BPF_JEQ, reg, 0, 2);		      \
 		*insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(			      \
 						struct bpf_sock_ops_kern, sk),\
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 4686783b70de..4a9e70e23ef8 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -169,6 +169,7 @@ static void bpf_skops_parse_hdr(struct sock *sk, struct sk_buff *skb)
 	memset(&sock_ops, 0, offsetof(struct bpf_sock_ops_kern, temp));
 	sock_ops.op = BPF_SOCK_OPS_PARSE_HDR_OPT_CB;
 	sock_ops.is_fullsock = 1;
+	sock_ops.is_locked_tcp_sock = 1;
 	sock_ops.sk = sk;
 	bpf_skops_init_skb(&sock_ops, skb, tcp_hdrlen(skb));
 
@@ -185,6 +186,7 @@ static void bpf_skops_established(struct sock *sk, int bpf_op,
 	memset(&sock_ops, 0, offsetof(struct bpf_sock_ops_kern, temp));
 	sock_ops.op = bpf_op;
 	sock_ops.is_fullsock = 1;
+	sock_ops.is_locked_tcp_sock = 1;
 	sock_ops.sk = sk;
 	/* sk with TCP_REPAIR_ON does not have skb in tcp_finish_connect */
 	if (skb)
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 464232a0d637..a796cf451e55 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -525,6 +525,7 @@ static void bpf_skops_hdr_opt_len(struct sock *sk, struct sk_buff *skb,
 		sock_owned_by_me(sk);
 
 		sock_ops.is_fullsock = 1;
+		sock_ops.is_locked_tcp_sock = 1;
 		sock_ops.sk = sk;
 	}
 
@@ -570,6 +571,7 @@ static void bpf_skops_write_hdr_opt(struct sock *sk, struct sk_buff *skb,
 		sock_owned_by_me(sk);
 
 		sock_ops.is_fullsock = 1;
+		sock_ops.is_locked_tcp_sock = 1;
 		sock_ops.sk = sk;
 	}
 

From 2958624b25305142e24203165ff65409ba9dd9d7 Mon Sep 17 00:00:00 2001
From: Jason Xing <kerneljasonxing@gmail.com>
Date: Thu, 20 Feb 2025 15:29:32 +0800
Subject: [PATCH 04/12] bpf: Disable unsafe helpers in TX timestamping
 callbacks

New TX timestamping sock_ops callbacks will be added in the
subsequent patch. Some of the existing BPF helpers will not
be safe to be used in the TX timestamping callbacks.

The bpf_sock_ops_setsockopt, bpf_sock_ops_getsockopt, and
bpf_sock_ops_cb_flags_set require owning the sock lock. TX
timestamping callbacks will not own the lock.

The bpf_sock_ops_load_hdr_opt needs the skb->data pointing
to the TCP header. This will not be true in the TX timestamping
callbacks.

At the beginning of these helpers, this patch checks the
bpf_sock->op to ensure these helpers are used by the existing
sock_ops callbacks only.

Signed-off-by: Jason Xing <kerneljasonxing@gmail.com>
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Link: https://patch.msgid.link/20250220072940.99994-5-kerneljasonxing@gmail.com
---
 net/core/filter.c | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/net/core/filter.c b/net/core/filter.c
index 7a20ddae7667..90a8fbc2e096 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -5524,6 +5524,11 @@ static int __bpf_setsockopt(struct sock *sk, int level, int optname,
 	return -EINVAL;
 }
 
+static bool is_locked_tcp_sock_ops(struct bpf_sock_ops_kern *bpf_sock)
+{
+	return bpf_sock->op <= BPF_SOCK_OPS_WRITE_HDR_OPT_CB;
+}
+
 static int _bpf_setsockopt(struct sock *sk, int level, int optname,
 			   char *optval, int optlen)
 {
@@ -5674,6 +5679,9 @@ static const struct bpf_func_proto bpf_sock_addr_getsockopt_proto = {
 BPF_CALL_5(bpf_sock_ops_setsockopt, struct bpf_sock_ops_kern *, bpf_sock,
 	   int, level, int, optname, char *, optval, int, optlen)
 {
+	if (!is_locked_tcp_sock_ops(bpf_sock))
+		return -EOPNOTSUPP;
+
 	return _bpf_setsockopt(bpf_sock->sk, level, optname, optval, optlen);
 }
 
@@ -5759,6 +5767,9 @@ static int bpf_sock_ops_get_syn(struct bpf_sock_ops_kern *bpf_sock,
 BPF_CALL_5(bpf_sock_ops_getsockopt, struct bpf_sock_ops_kern *, bpf_sock,
 	   int, level, int, optname, char *, optval, int, optlen)
 {
+	if (!is_locked_tcp_sock_ops(bpf_sock))
+		return -EOPNOTSUPP;
+
 	if (IS_ENABLED(CONFIG_INET) && level == SOL_TCP &&
 	    optname >= TCP_BPF_SYN && optname <= TCP_BPF_SYN_MAC) {
 		int ret, copy_len = 0;
@@ -5801,6 +5812,9 @@ BPF_CALL_2(bpf_sock_ops_cb_flags_set, struct bpf_sock_ops_kern *, bpf_sock,
 	struct sock *sk = bpf_sock->sk;
 	int val = argval & BPF_SOCK_OPS_ALL_CB_FLAGS;
 
+	if (!is_locked_tcp_sock_ops(bpf_sock))
+		return -EOPNOTSUPP;
+
 	if (!IS_ENABLED(CONFIG_INET) || !sk_fullsock(sk))
 		return -EINVAL;
 
@@ -7610,6 +7624,9 @@ BPF_CALL_4(bpf_sock_ops_load_hdr_opt, struct bpf_sock_ops_kern *, bpf_sock,
 	u8 search_kind, search_len, copy_len, magic_len;
 	int ret;
 
+	if (!is_locked_tcp_sock_ops(bpf_sock))
+		return -EOPNOTSUPP;
+
 	/* 2 byte is the minimal option len except TCPOPT_NOP and
 	 * TCPOPT_EOL which are useless for the bpf prog to learn
 	 * and this helper disallow loading them also.

From aa290f93a4af662b8d2d9e9df65798f9f24cecf3 Mon Sep 17 00:00:00 2001
From: Jason Xing <kerneljasonxing@gmail.com>
Date: Thu, 20 Feb 2025 15:29:33 +0800
Subject: [PATCH 05/12] net-timestamp: Prepare for isolating two modes of
 SO_TIMESTAMPING

No functional changes here. Only add test to see if the orig_skb
matches the usage of application SO_TIMESTAMPING.

In this series, bpf timestamping and previous socket timestamping
are implemented in the same function __skb_tstamp_tx(). To test
the socket enables socket timestamping feature, this function
skb_tstamp_tx_report_so_timestamping() is added.

In the next patch, another check for bpf timestamping feature
will be introduced just like the above report function, namely,
skb_tstamp_tx_report_bpf_timestamping(). Then users will be able
to know the socket enables either or both of features.

Signed-off-by: Jason Xing <kerneljasonxing@gmail.com>
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Link: https://patch.msgid.link/20250220072940.99994-6-kerneljasonxing@gmail.com
---
 net/core/skbuff.c | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index a441613a1e6c..341a3290e898 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -5539,6 +5539,23 @@ err:
 }
 EXPORT_SYMBOL_GPL(skb_complete_tx_timestamp);
 
+static bool skb_tstamp_tx_report_so_timestamping(struct sk_buff *skb,
+						 struct skb_shared_hwtstamps *hwtstamps,
+						 int tstype)
+{
+	switch (tstype) {
+	case SCM_TSTAMP_SCHED:
+		return skb_shinfo(skb)->tx_flags & SKBTX_SCHED_TSTAMP;
+	case SCM_TSTAMP_SND:
+		return skb_shinfo(skb)->tx_flags & (hwtstamps ? SKBTX_HW_TSTAMP :
+						    SKBTX_SW_TSTAMP);
+	case SCM_TSTAMP_ACK:
+		return TCP_SKB_CB(skb)->txstamp_ack;
+	}
+
+	return false;
+}
+
 void __skb_tstamp_tx(struct sk_buff *orig_skb,
 		     const struct sk_buff *ack_skb,
 		     struct skb_shared_hwtstamps *hwtstamps,
@@ -5551,6 +5568,9 @@ void __skb_tstamp_tx(struct sk_buff *orig_skb,
 	if (!sk)
 		return;
 
+	if (!skb_tstamp_tx_report_so_timestamping(orig_skb, hwtstamps, tstype))
+		return;
+
 	tsflags = READ_ONCE(sk->sk_tsflags);
 	if (!hwtstamps && !(tsflags & SOF_TIMESTAMPING_OPT_TX_SWHW) &&
 	    skb_shinfo(orig_skb)->tx_flags & SKBTX_IN_PROGRESS)

From 6b98ec7e882af1c3088a88757e2226d06c8514f9 Mon Sep 17 00:00:00 2001
From: Jason Xing <kerneljasonxing@gmail.com>
Date: Thu, 20 Feb 2025 15:29:34 +0800
Subject: [PATCH 06/12] bpf: Add BPF_SOCK_OPS_TSTAMP_SCHED_CB callback

Support SCM_TSTAMP_SCHED case for bpf timestamping.

Add a new sock_ops callback, BPF_SOCK_OPS_TSTAMP_SCHED_CB. This
callback will occur at the same timestamping point as the user
space's SCM_TSTAMP_SCHED. The BPF program can use it to get the
same SCM_TSTAMP_SCHED timestamp without modifying the user-space
application.

A new SKBTX_BPF flag is added to mark skb_shinfo(skb)->tx_flags,
ensuring that the new BPF timestamping and the current user
space's SO_TIMESTAMPING do not interfere with each other.

Signed-off-by: Jason Xing <kerneljasonxing@gmail.com>
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Link: https://patch.msgid.link/20250220072940.99994-7-kerneljasonxing@gmail.com
---
 include/linux/skbuff.h         |  6 +++++-
 include/uapi/linux/bpf.h       |  5 +++++
 net/core/dev.c                 |  3 ++-
 net/core/skbuff.c              | 20 ++++++++++++++++++++
 tools/include/uapi/linux/bpf.h |  5 +++++
 5 files changed, 37 insertions(+), 2 deletions(-)

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index bb2b751d274a..52f6e033e704 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -489,10 +489,14 @@ 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 4e0632848440..bb62fe25b2d0 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -7031,6 +7031,11 @@ enum {
 					 * by the kernel or the
 					 * earlier bpf-progs.
 					 */
+	BPF_SOCK_OPS_TSTAMP_SCHED_CB,	/* Called when skb is passing
+					 * through dev layer when
+					 * SK_BPF_CB_TX_TIMESTAMPING
+					 * feature is on.
+					 */
 };
 
 /* List of TCP states. There is a build check in net/ipv4/tcp.c to detect
diff --git a/net/core/dev.c b/net/core/dev.c
index d5ab9a4b318e..436f2bdfb2d5 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -4501,7 +4501,8 @@ int __dev_queue_xmit(struct sk_buff *skb, struct net_device *sb_dev)
 	skb_reset_mac_header(skb);
 	skb_assert_len(skb);
 
-	if (unlikely(skb_shinfo(skb)->tx_flags & SKBTX_SCHED_TSTAMP))
+	if (unlikely(skb_shinfo(skb)->tx_flags &
+		     (SKBTX_SCHED_TSTAMP | SKBTX_BPF)))
 		__skb_tstamp_tx(skb, NULL, NULL, skb->sk, SCM_TSTAMP_SCHED);
 
 	/* Disable soft irqs for various locks below. Also
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 341a3290e898..3206f7708974 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -5556,6 +5556,23 @@ static bool skb_tstamp_tx_report_so_timestamping(struct sk_buff *skb,
 	return false;
 }
 
+static void skb_tstamp_tx_report_bpf_timestamping(struct sk_buff *skb,
+						  struct sock *sk,
+						  int tstype)
+{
+	int op;
+
+	switch (tstype) {
+	case SCM_TSTAMP_SCHED:
+		op = BPF_SOCK_OPS_TSTAMP_SCHED_CB;
+		break;
+	default:
+		return;
+	}
+
+	bpf_skops_tx_timestamping(sk, skb, op);
+}
+
 void __skb_tstamp_tx(struct sk_buff *orig_skb,
 		     const struct sk_buff *ack_skb,
 		     struct skb_shared_hwtstamps *hwtstamps,
@@ -5568,6 +5585,9 @@ void __skb_tstamp_tx(struct sk_buff *orig_skb,
 	if (!sk)
 		return;
 
+	if (skb_shinfo(orig_skb)->tx_flags & SKBTX_BPF)
+		skb_tstamp_tx_report_bpf_timestamping(orig_skb, sk, tstype);
+
 	if (!skb_tstamp_tx_report_so_timestamping(orig_skb, hwtstamps, tstype))
 		return;
 
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index 4e0632848440..bb62fe25b2d0 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -7031,6 +7031,11 @@ enum {
 					 * by the kernel or the
 					 * earlier bpf-progs.
 					 */
+	BPF_SOCK_OPS_TSTAMP_SCHED_CB,	/* Called when skb is passing
+					 * through dev layer when
+					 * SK_BPF_CB_TX_TIMESTAMPING
+					 * feature is on.
+					 */
 };
 
 /* List of TCP states. There is a build check in net/ipv4/tcp.c to detect

From ecebb17ad818bc043e558c278a6c56d5bbaebacc Mon Sep 17 00:00:00 2001
From: Jason Xing <kerneljasonxing@gmail.com>
Date: Thu, 20 Feb 2025 15:29:35 +0800
Subject: [PATCH 07/12] bpf: Add BPF_SOCK_OPS_TSTAMP_SND_SW_CB callback

Support sw SCM_TSTAMP_SND case for bpf timestamping.

Add a new sock_ops callback, BPF_SOCK_OPS_TSTAMP_SND_SW_CB. This
callback will occur at the same timestamping point as the user
space's software SCM_TSTAMP_SND. The BPF program can use it to
get the same SCM_TSTAMP_SND timestamp without modifying the
user-space application.

Based on this patch, BPF program will get the software
timestamp when the driver is ready to send the skb. In the
sebsequent patch, the hardware timestamp will be supported.

Signed-off-by: Jason Xing <kerneljasonxing@gmail.com>
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Link: https://patch.msgid.link/20250220072940.99994-8-kerneljasonxing@gmail.com
---
 include/linux/skbuff.h         | 2 +-
 include/uapi/linux/bpf.h       | 4 ++++
 net/core/skbuff.c              | 9 ++++++++-
 tools/include/uapi/linux/bpf.h | 4 ++++
 4 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 52f6e033e704..76582500c5ea 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -4568,7 +4568,7 @@ void skb_tstamp_tx(struct sk_buff *orig_skb,
 static inline void skb_tx_timestamp(struct sk_buff *skb)
 {
 	skb_clone_tx_timestamp(skb);
-	if (skb_shinfo(skb)->tx_flags & SKBTX_SW_TSTAMP)
+	if (skb_shinfo(skb)->tx_flags & (SKBTX_SW_TSTAMP | SKBTX_BPF))
 		skb_tstamp_tx(skb, NULL);
 }
 
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index bb62fe25b2d0..abe8d6c30dae 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -7036,6 +7036,10 @@ enum {
 					 * SK_BPF_CB_TX_TIMESTAMPING
 					 * feature is on.
 					 */
+	BPF_SOCK_OPS_TSTAMP_SND_SW_CB,	/* Called when skb is about to send
+					 * to the nic when SK_BPF_CB_TX_TIMESTAMPING
+					 * feature is on.
+					 */
 };
 
 /* 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 3206f7708974..308db7dae1ab 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -5557,6 +5557,7 @@ static bool skb_tstamp_tx_report_so_timestamping(struct sk_buff *skb,
 }
 
 static void skb_tstamp_tx_report_bpf_timestamping(struct sk_buff *skb,
+						  struct skb_shared_hwtstamps *hwtstamps,
 						  struct sock *sk,
 						  int tstype)
 {
@@ -5566,6 +5567,11 @@ static void skb_tstamp_tx_report_bpf_timestamping(struct sk_buff *skb,
 	case SCM_TSTAMP_SCHED:
 		op = BPF_SOCK_OPS_TSTAMP_SCHED_CB;
 		break;
+	case SCM_TSTAMP_SND:
+		if (hwtstamps)
+			return;
+		op = BPF_SOCK_OPS_TSTAMP_SND_SW_CB;
+		break;
 	default:
 		return;
 	}
@@ -5586,7 +5592,8 @@ void __skb_tstamp_tx(struct sk_buff *orig_skb,
 		return;
 
 	if (skb_shinfo(orig_skb)->tx_flags & SKBTX_BPF)
-		skb_tstamp_tx_report_bpf_timestamping(orig_skb, sk, tstype);
+		skb_tstamp_tx_report_bpf_timestamping(orig_skb, hwtstamps,
+						      sk, tstype);
 
 	if (!skb_tstamp_tx_report_so_timestamping(orig_skb, hwtstamps, tstype))
 		return;
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index bb62fe25b2d0..abe8d6c30dae 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -7036,6 +7036,10 @@ enum {
 					 * SK_BPF_CB_TX_TIMESTAMPING
 					 * feature is on.
 					 */
+	BPF_SOCK_OPS_TSTAMP_SND_SW_CB,	/* Called when skb is about to send
+					 * to the nic when SK_BPF_CB_TX_TIMESTAMPING
+					 * feature is on.
+					 */
 };
 
 /* List of TCP states. There is a build check in net/ipv4/tcp.c to detect

From 2deaf7f42b8c551e84da20483ca2d4a65c3623b3 Mon Sep 17 00:00:00 2001
From: Jason Xing <kerneljasonxing@gmail.com>
Date: Thu, 20 Feb 2025 15:29:36 +0800
Subject: [PATCH 08/12] bpf: Add BPF_SOCK_OPS_TSTAMP_SND_HW_CB callback

Support hw SCM_TSTAMP_SND case for bpf timestamping.

Add a new sock_ops callback, BPF_SOCK_OPS_TSTAMP_SND_HW_CB. This
callback will occur at the same timestamping point as the user
space's hardware SCM_TSTAMP_SND. The BPF program can use it to
get the same SCM_TSTAMP_SND timestamp without modifying the
user-space application.

To avoid increasing the code complexity, replace SKBTX_HW_TSTAMP
with SKBTX_HW_TSTAMP_NOBPF instead of changing numerous callers
from driver side using SKBTX_HW_TSTAMP. The new definition of
SKBTX_HW_TSTAMP means the combination tests of socket timestamping
and bpf timestamping. After this patch, drivers can work under the
bpf timestamping.

Considering some drivers don't assign the skb with hardware
timestamp, this patch does the assignment and then BPF program
can acquire the hwstamp from skb directly.

Signed-off-by: Jason Xing <kerneljasonxing@gmail.com>
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Link: https://patch.msgid.link/20250220072940.99994-9-kerneljasonxing@gmail.com
---
 include/linux/skbuff.h         |  4 +++-
 include/uapi/linux/bpf.h       |  4 ++++
 net/core/skbuff.c              | 11 +++++++----
 net/dsa/user.c                 |  2 +-
 net/socket.c                   |  2 +-
 tools/include/uapi/linux/bpf.h |  4 ++++
 6 files changed, 20 insertions(+), 7 deletions(-)

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 76582500c5ea..0b4f1889500d 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -470,7 +470,7 @@ struct skb_shared_hwtstamps {
 /* Definitions for tx_flags in struct skb_shared_info */
 enum {
 	/* generate hardware time stamp */
-	SKBTX_HW_TSTAMP = 1 << 0,
+	SKBTX_HW_TSTAMP_NOBPF = 1 << 0,
 
 	/* generate software time stamp when queueing packet to NIC */
 	SKBTX_SW_TSTAMP = 1 << 1,
@@ -494,6 +494,8 @@ enum {
 	SKBTX_BPF = 1 << 7,
 };
 
+#define SKBTX_HW_TSTAMP		(SKBTX_HW_TSTAMP_NOBPF | SKBTX_BPF)
+
 #define SKBTX_ANY_SW_TSTAMP	(SKBTX_SW_TSTAMP    | \
 				 SKBTX_SCHED_TSTAMP | \
 				 SKBTX_BPF)
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index abe8d6c30dae..72045c242396 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -7040,6 +7040,10 @@ enum {
 					 * to the nic when SK_BPF_CB_TX_TIMESTAMPING
 					 * feature is on.
 					 */
+	BPF_SOCK_OPS_TSTAMP_SND_HW_CB,	/* Called in hardware phase when
+					 * SK_BPF_CB_TX_TIMESTAMPING feature
+					 * is on.
+					 */
 };
 
 /* 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 308db7dae1ab..77b8866f94c5 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -5547,7 +5547,7 @@ static bool skb_tstamp_tx_report_so_timestamping(struct sk_buff *skb,
 	case SCM_TSTAMP_SCHED:
 		return skb_shinfo(skb)->tx_flags & SKBTX_SCHED_TSTAMP;
 	case SCM_TSTAMP_SND:
-		return skb_shinfo(skb)->tx_flags & (hwtstamps ? SKBTX_HW_TSTAMP :
+		return skb_shinfo(skb)->tx_flags & (hwtstamps ? SKBTX_HW_TSTAMP_NOBPF :
 						    SKBTX_SW_TSTAMP);
 	case SCM_TSTAMP_ACK:
 		return TCP_SKB_CB(skb)->txstamp_ack;
@@ -5568,9 +5568,12 @@ static void skb_tstamp_tx_report_bpf_timestamping(struct sk_buff *skb,
 		op = BPF_SOCK_OPS_TSTAMP_SCHED_CB;
 		break;
 	case SCM_TSTAMP_SND:
-		if (hwtstamps)
-			return;
-		op = BPF_SOCK_OPS_TSTAMP_SND_SW_CB;
+		if (hwtstamps) {
+			op = BPF_SOCK_OPS_TSTAMP_SND_HW_CB;
+			*skb_hwtstamps(skb) = *hwtstamps;
+		} else {
+			op = BPF_SOCK_OPS_TSTAMP_SND_SW_CB;
+		}
 		break;
 	default:
 		return;
diff --git a/net/dsa/user.c b/net/dsa/user.c
index 2296a4ead020..804dc7dac4f2 100644
--- a/net/dsa/user.c
+++ b/net/dsa/user.c
@@ -897,7 +897,7 @@ static void dsa_skb_tx_timestamp(struct dsa_user_priv *p,
 {
 	struct dsa_switch *ds = p->dp->ds;
 
-	if (!(skb_shinfo(skb)->tx_flags & SKBTX_HW_TSTAMP))
+	if (!(skb_shinfo(skb)->tx_flags & SKBTX_HW_TSTAMP_NOBPF))
 		return;
 
 	if (!ds->ops->port_txtstamp)
diff --git a/net/socket.c b/net/socket.c
index 28bae5a94234..0545e9ea7058 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -681,7 +681,7 @@ void __sock_tx_timestamp(__u32 tsflags, __u8 *tx_flags)
 	u8 flags = *tx_flags;
 
 	if (tsflags & SOF_TIMESTAMPING_TX_HARDWARE) {
-		flags |= SKBTX_HW_TSTAMP;
+		flags |= SKBTX_HW_TSTAMP_NOBPF;
 
 		/* PTP hardware clocks can provide a free running cycle counter
 		 * as a time base for virtual clocks. Tell driver to use the
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index abe8d6c30dae..72045c242396 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -7040,6 +7040,10 @@ enum {
 					 * to the nic when SK_BPF_CB_TX_TIMESTAMPING
 					 * feature is on.
 					 */
+	BPF_SOCK_OPS_TSTAMP_SND_HW_CB,	/* Called in hardware phase when
+					 * SK_BPF_CB_TX_TIMESTAMPING feature
+					 * is on.
+					 */
 };
 
 /* List of TCP states. There is a build check in net/ipv4/tcp.c to detect

From b3b81e6b009dd8f85cd3b9c65eb492249c2649a8 Mon Sep 17 00:00:00 2001
From: Jason Xing <kerneljasonxing@gmail.com>
Date: Thu, 20 Feb 2025 15:29:37 +0800
Subject: [PATCH 09/12] bpf: Add BPF_SOCK_OPS_TSTAMP_ACK_CB callback

Support the ACK case for bpf timestamping.

Add a new sock_ops callback, BPF_SOCK_OPS_TSTAMP_ACK_CB. This
callback will occur at the same timestamping point as the user
space's SCM_TSTAMP_ACK. The BPF program can use it to get the
same SCM_TSTAMP_ACK timestamp without modifying the user-space
application.

This patch extends txstamp_ack to two bits: 1 stands for
SO_TIMESTAMPING mode, 2 bpf extension.

Signed-off-by: Jason Xing <kerneljasonxing@gmail.com>
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Link: https://patch.msgid.link/20250220072940.99994-10-kerneljasonxing@gmail.com
---
 include/net/tcp.h              | 6 ++++--
 include/uapi/linux/bpf.h       | 5 +++++
 net/core/skbuff.c              | 5 ++++-
 net/ipv4/tcp.c                 | 2 +-
 tools/include/uapi/linux/bpf.h | 5 +++++
 5 files changed, 19 insertions(+), 4 deletions(-)

diff --git a/include/net/tcp.h b/include/net/tcp.h
index 94ea09faedf4..ae6c95b01012 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -964,10 +964,12 @@ struct tcp_skb_cb {
 
 	__u8		sacked;		/* State flags for SACK.	*/
 	__u8		ip_dsfield;	/* IPv4 tos or IPv6 dsfield	*/
-	__u8		txstamp_ack:1,	/* Record TX timestamp for ack? */
+#define TSTAMP_ACK_SK	0x1
+#define TSTAMP_ACK_BPF	0x2
+	__u8		txstamp_ack:2,	/* Record TX timestamp for ack? */
 			eor:1,		/* Is skb MSG_EOR marked? */
 			has_rxtstamp:1,	/* SKB has a RX timestamp	*/
-			unused:5;
+			unused:4;
 	__u32		ack_seq;	/* Sequence number ACK'd	*/
 	union {
 		struct {
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 72045c242396..cc10104f34a0 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -7044,6 +7044,11 @@ enum {
 					 * SK_BPF_CB_TX_TIMESTAMPING feature
 					 * is on.
 					 */
+	BPF_SOCK_OPS_TSTAMP_ACK_CB,	/* Called when all the skbs in the
+					 * same sendmsg call are acked
+					 * when SK_BPF_CB_TX_TIMESTAMPING
+					 * feature is on.
+					 */
 };
 
 /* 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 77b8866f94c5..dd33c12f00ca 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -5550,7 +5550,7 @@ static bool skb_tstamp_tx_report_so_timestamping(struct sk_buff *skb,
 		return skb_shinfo(skb)->tx_flags & (hwtstamps ? SKBTX_HW_TSTAMP_NOBPF :
 						    SKBTX_SW_TSTAMP);
 	case SCM_TSTAMP_ACK:
-		return TCP_SKB_CB(skb)->txstamp_ack;
+		return TCP_SKB_CB(skb)->txstamp_ack & TSTAMP_ACK_SK;
 	}
 
 	return false;
@@ -5575,6 +5575,9 @@ static void skb_tstamp_tx_report_bpf_timestamping(struct sk_buff *skb,
 			op = BPF_SOCK_OPS_TSTAMP_SND_SW_CB;
 		}
 		break;
+	case SCM_TSTAMP_ACK:
+		op = BPF_SOCK_OPS_TSTAMP_ACK_CB;
+		break;
 	default:
 		return;
 	}
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 992d5c9b2487..2171e2f045bb 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -492,7 +492,7 @@ static void tcp_tx_timestamp(struct sock *sk, struct sockcm_cookie *sockc)
 
 		sock_tx_timestamp(sk, sockc, &shinfo->tx_flags);
 		if (tsflags & SOF_TIMESTAMPING_TX_ACK)
-			tcb->txstamp_ack = 1;
+			tcb->txstamp_ack |= TSTAMP_ACK_SK;
 		if (tsflags & SOF_TIMESTAMPING_TX_RECORD_MASK)
 			shinfo->tskey = TCP_SKB_CB(skb)->seq + skb->len - 1;
 	}
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index 72045c242396..cc10104f34a0 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -7044,6 +7044,11 @@ enum {
 					 * SK_BPF_CB_TX_TIMESTAMPING feature
 					 * is on.
 					 */
+	BPF_SOCK_OPS_TSTAMP_ACK_CB,	/* Called when all the skbs in the
+					 * same sendmsg call are acked
+					 * when SK_BPF_CB_TX_TIMESTAMPING
+					 * feature is on.
+					 */
 };
 
 /* List of TCP states. There is a build check in net/ipv4/tcp.c to detect

From c9525d240c8117de35171ae705058ddf9667be27 Mon Sep 17 00:00:00 2001
From: Jason Xing <kerneljasonxing@gmail.com>
Date: Thu, 20 Feb 2025 15:29:38 +0800
Subject: [PATCH 10/12] bpf: Add BPF_SOCK_OPS_TSTAMP_SENDMSG_CB callback

This patch introduces a new callback in tcp_tx_timestamp() to correlate
tcp_sendmsg timestamp with timestamps from other tx timestamping
callbacks (e.g., SND/SW/ACK).

Without this patch, BPF program wouldn't know which timestamps belong
to which flow because of no socket lock protection. This new callback
is inserted in tcp_tx_timestamp() to address this issue because
tcp_tx_timestamp() still owns the same socket lock with
tcp_sendmsg_locked() in the meanwhile tcp_tx_timestamp() initializes
the timestamping related fields for the skb, especially tskey. The
tskey is the bridge to do the correlation.

For TCP, BPF program hooks the beginning of tcp_sendmsg_locked() and
then stores the sendmsg timestamp at the bpf_sk_storage, correlating
this timestamp with its tskey that are later used in other sending
timestamping callbacks.

Signed-off-by: Jason Xing <kerneljasonxing@gmail.com>
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Link: https://patch.msgid.link/20250220072940.99994-11-kerneljasonxing@gmail.com
---
 include/uapi/linux/bpf.h       | 5 +++++
 net/ipv4/tcp.c                 | 4 ++++
 tools/include/uapi/linux/bpf.h | 5 +++++
 3 files changed, 14 insertions(+)

diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index cc10104f34a0..defa5bb881f4 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -7049,6 +7049,11 @@ enum {
 					 * when SK_BPF_CB_TX_TIMESTAMPING
 					 * feature is on.
 					 */
+	BPF_SOCK_OPS_TSTAMP_SENDMSG_CB,	/* Called when every sendmsg syscall
+					 * is triggered. It's used to correlate
+					 * sendmsg timestamp with corresponding
+					 * tskey.
+					 */
 };
 
 /* List of TCP states. There is a build check in net/ipv4/tcp.c to detect
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 2171e2f045bb..298d1da05bee 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -496,6 +496,10 @@ static void tcp_tx_timestamp(struct sock *sk, struct sockcm_cookie *sockc)
 		if (tsflags & SOF_TIMESTAMPING_TX_RECORD_MASK)
 			shinfo->tskey = TCP_SKB_CB(skb)->seq + skb->len - 1;
 	}
+
+	if (cgroup_bpf_enabled(CGROUP_SOCK_OPS) &&
+	    SK_BPF_CB_FLAG_TEST(sk, SK_BPF_CB_TX_TIMESTAMPING) && skb)
+		bpf_skops_tx_timestamping(sk, skb, BPF_SOCK_OPS_TSTAMP_SENDMSG_CB);
 }
 
 static bool tcp_stream_is_readable(struct sock *sk, int target)
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index cc10104f34a0..defa5bb881f4 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -7049,6 +7049,11 @@ enum {
 					 * when SK_BPF_CB_TX_TIMESTAMPING
 					 * feature is on.
 					 */
+	BPF_SOCK_OPS_TSTAMP_SENDMSG_CB,	/* Called when every sendmsg syscall
+					 * is triggered. It's used to correlate
+					 * sendmsg timestamp with corresponding
+					 * tskey.
+					 */
 };
 
 /* List of TCP states. There is a build check in net/ipv4/tcp.c to detect

From 59422464266f8baa091edcb3779f0955a21abf00 Mon Sep 17 00:00:00 2001
From: Jason Xing <kerneljasonxing@gmail.com>
Date: Thu, 20 Feb 2025 15:29:39 +0800
Subject: [PATCH 11/12] bpf: Support selective sampling for bpf timestamping

Add the bpf_sock_ops_enable_tx_tstamp kfunc to allow BPF programs to
selectively enable TX timestamping on a skb during tcp_sendmsg().

For example, BPF program will limit tracking X numbers of packets
and then will stop there instead of tracing all the sendmsgs of
matched flow all along. It would be helpful for users who cannot
afford to calculate latencies from every sendmsg call probably
due to the performance or storage space consideration.

Signed-off-by: Jason Xing <kerneljasonxing@gmail.com>
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Link: https://patch.msgid.link/20250220072940.99994-12-kerneljasonxing@gmail.com
---
 kernel/bpf/btf.c  |  1 +
 net/core/filter.c | 31 ++++++++++++++++++++++++++++++-
 2 files changed, 31 insertions(+), 1 deletion(-)

diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index 9de6acddd479..551eedb87d58 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -8524,6 +8524,7 @@ static int bpf_prog_type_to_kfunc_hook(enum bpf_prog_type prog_type)
 	case BPF_PROG_TYPE_CGROUP_SOCK_ADDR:
 	case BPF_PROG_TYPE_CGROUP_SOCKOPT:
 	case BPF_PROG_TYPE_CGROUP_SYSCTL:
+	case BPF_PROG_TYPE_SOCK_OPS:
 		return BTF_KFUNC_HOOK_CGROUP;
 	case BPF_PROG_TYPE_SCHED_ACT:
 		return BTF_KFUNC_HOOK_SCHED_ACT;
diff --git a/net/core/filter.c b/net/core/filter.c
index 90a8fbc2e096..a0867c5b32b3 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -12103,6 +12103,25 @@ __bpf_kfunc int bpf_sk_assign_tcp_reqsk(struct __sk_buff *s, struct sock *sk,
 #endif
 }
 
+__bpf_kfunc int bpf_sock_ops_enable_tx_tstamp(struct bpf_sock_ops_kern *skops,
+					      u64 flags)
+{
+	struct sk_buff *skb;
+
+	if (skops->op != BPF_SOCK_OPS_TSTAMP_SENDMSG_CB)
+		return -EOPNOTSUPP;
+
+	if (flags)
+		return -EINVAL;
+
+	skb = skops->skb;
+	skb_shinfo(skb)->tx_flags |= SKBTX_BPF;
+	TCP_SKB_CB(skb)->txstamp_ack |= TSTAMP_ACK_BPF;
+	skb_shinfo(skb)->tskey = TCP_SKB_CB(skb)->seq + skb->len - 1;
+
+	return 0;
+}
+
 __bpf_kfunc_end_defs();
 
 int bpf_dynptr_from_skb_rdonly(struct __sk_buff *skb, u64 flags,
@@ -12136,6 +12155,10 @@ BTF_KFUNCS_START(bpf_kfunc_check_set_tcp_reqsk)
 BTF_ID_FLAGS(func, bpf_sk_assign_tcp_reqsk, KF_TRUSTED_ARGS)
 BTF_KFUNCS_END(bpf_kfunc_check_set_tcp_reqsk)
 
+BTF_KFUNCS_START(bpf_kfunc_check_set_sock_ops)
+BTF_ID_FLAGS(func, bpf_sock_ops_enable_tx_tstamp, KF_TRUSTED_ARGS)
+BTF_KFUNCS_END(bpf_kfunc_check_set_sock_ops)
+
 static const struct btf_kfunc_id_set bpf_kfunc_set_skb = {
 	.owner = THIS_MODULE,
 	.set = &bpf_kfunc_check_set_skb,
@@ -12156,6 +12179,11 @@ static const struct btf_kfunc_id_set bpf_kfunc_set_tcp_reqsk = {
 	.set = &bpf_kfunc_check_set_tcp_reqsk,
 };
 
+static const struct btf_kfunc_id_set bpf_kfunc_set_sock_ops = {
+	.owner = THIS_MODULE,
+	.set = &bpf_kfunc_check_set_sock_ops,
+};
+
 static int __init bpf_kfunc_init(void)
 {
 	int ret;
@@ -12174,7 +12202,8 @@ static int __init bpf_kfunc_init(void)
 	ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_XDP, &bpf_kfunc_set_xdp);
 	ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_CGROUP_SOCK_ADDR,
 					       &bpf_kfunc_set_sock_addr);
-	return ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_SCHED_CLS, &bpf_kfunc_set_tcp_reqsk);
+	ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_SCHED_CLS, &bpf_kfunc_set_tcp_reqsk);
+	return ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_SOCK_OPS, &bpf_kfunc_set_sock_ops);
 }
 late_initcall(bpf_kfunc_init);
 

From f4924aec58dd9e14779f4bc11a6bf3a830a42a6c Mon Sep 17 00:00:00 2001
From: Jason Xing <kerneljasonxing@gmail.com>
Date: Thu, 20 Feb 2025 15:29:40 +0800
Subject: [PATCH 12/12] selftests/bpf: Add simple bpf tests in the tx path for
 timestamping feature

BPF program calculates a couple of latency deltas between each tx
timestamping callbacks. It can be used in the real world to diagnose
the kernel behaviour in the tx path.

Check the safety issues by accessing a few bpf calls in
bpf_test_access_bpf_calls() which are implemented in the patch 3 and 4.

Check if the bpf timestamping can co-exist with socket timestamping.

There remains a few realistic things[1][2] to highlight:
1. in general a packet may pass through multiple qdiscs. For instance
with bonding or tunnel virtual devices in the egress path.
2. packets may be resent, in which case an ACK might precede a repeat
SCHED and SND.
3. erroneous or malicious peers may also just never send an ACK.

[1]: https://lore.kernel.org/all/67a389af981b0_14e0832949d@willemb.c.googlers.com.notmuch/
[2]: https://lore.kernel.org/all/c329a0c1-239b-4ca1-91f2-cb30b8dd2f6a@linux.dev/

Signed-off-by: Jason Xing <kerneljasonxing@gmail.com>
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Link: https://patch.msgid.link/20250220072940.99994-13-kerneljasonxing@gmail.com
---
 .../bpf/prog_tests/net_timestamping.c         | 239 +++++++++++++++++
 .../selftests/bpf/progs/net_timestamping.c    | 248 ++++++++++++++++++
 2 files changed, 487 insertions(+)
 create mode 100644 tools/testing/selftests/bpf/prog_tests/net_timestamping.c
 create mode 100644 tools/testing/selftests/bpf/progs/net_timestamping.c

diff --git a/tools/testing/selftests/bpf/prog_tests/net_timestamping.c b/tools/testing/selftests/bpf/prog_tests/net_timestamping.c
new file mode 100644
index 000000000000..dbfd87499b6b
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/net_timestamping.c
@@ -0,0 +1,239 @@
+#include <linux/net_tstamp.h>
+#include <sys/time.h>
+#include <linux/errqueue.h>
+#include "test_progs.h"
+#include "network_helpers.h"
+#include "net_timestamping.skel.h"
+
+#define CG_NAME "/net-timestamping-test"
+#define NSEC_PER_SEC    1000000000LL
+
+static const char addr4_str[] = "127.0.0.1";
+static const char addr6_str[] = "::1";
+static struct net_timestamping *skel;
+static const int cfg_payload_len = 30;
+static struct timespec usr_ts;
+static u64 delay_tolerance_nsec = 10000000000; /* 10 seconds */
+int SK_TS_SCHED;
+int SK_TS_TXSW;
+int SK_TS_ACK;
+
+static int64_t timespec_to_ns64(struct timespec *ts)
+{
+	return ts->tv_sec * NSEC_PER_SEC + ts->tv_nsec;
+}
+
+static void validate_key(int tskey, int tstype)
+{
+	static int expected_tskey = -1;
+
+	if (tstype == SCM_TSTAMP_SCHED)
+		expected_tskey = cfg_payload_len - 1;
+
+	ASSERT_EQ(expected_tskey, tskey, "tskey mismatch");
+
+	expected_tskey = tskey;
+}
+
+static void validate_timestamp(struct timespec *cur, struct timespec *prev)
+{
+	int64_t cur_ns, prev_ns;
+
+	cur_ns = timespec_to_ns64(cur);
+	prev_ns = timespec_to_ns64(prev);
+
+	ASSERT_LT(cur_ns - prev_ns, delay_tolerance_nsec, "latency");
+}
+
+static void test_socket_timestamp(struct scm_timestamping *tss, int tstype,
+				  int tskey)
+{
+	static struct timespec prev_ts;
+
+	validate_key(tskey, tstype);
+
+	switch (tstype) {
+	case SCM_TSTAMP_SCHED:
+		validate_timestamp(&tss->ts[0], &usr_ts);
+		SK_TS_SCHED += 1;
+		break;
+	case SCM_TSTAMP_SND:
+		validate_timestamp(&tss->ts[0], &prev_ts);
+		SK_TS_TXSW += 1;
+		break;
+	case SCM_TSTAMP_ACK:
+		validate_timestamp(&tss->ts[0], &prev_ts);
+		SK_TS_ACK += 1;
+		break;
+	}
+
+	prev_ts = tss->ts[0];
+}
+
+static void test_recv_errmsg_cmsg(struct msghdr *msg)
+{
+	struct sock_extended_err *serr = NULL;
+	struct scm_timestamping *tss = NULL;
+	struct cmsghdr *cm;
+
+	for (cm = CMSG_FIRSTHDR(msg);
+	     cm && cm->cmsg_len;
+	     cm = CMSG_NXTHDR(msg, cm)) {
+		if (cm->cmsg_level == SOL_SOCKET &&
+		    cm->cmsg_type == SCM_TIMESTAMPING) {
+			tss = (void *)CMSG_DATA(cm);
+		} else if ((cm->cmsg_level == SOL_IP &&
+			    cm->cmsg_type == IP_RECVERR) ||
+			   (cm->cmsg_level == SOL_IPV6 &&
+			    cm->cmsg_type == IPV6_RECVERR) ||
+			   (cm->cmsg_level == SOL_PACKET &&
+			    cm->cmsg_type == PACKET_TX_TIMESTAMP)) {
+			serr = (void *)CMSG_DATA(cm);
+			ASSERT_EQ(serr->ee_origin, SO_EE_ORIGIN_TIMESTAMPING,
+				  "cmsg type");
+		}
+
+		if (serr && tss)
+			test_socket_timestamp(tss, serr->ee_info,
+					      serr->ee_data);
+	}
+}
+
+static bool socket_recv_errmsg(int fd)
+{
+	static char ctrl[1024 /* overprovision*/];
+	char data[cfg_payload_len];
+	static struct msghdr msg;
+	struct iovec entry;
+	int n = 0;
+
+	memset(&msg, 0, sizeof(msg));
+	memset(&entry, 0, sizeof(entry));
+	memset(ctrl, 0, sizeof(ctrl));
+
+	entry.iov_base = data;
+	entry.iov_len = cfg_payload_len;
+	msg.msg_iov = &entry;
+	msg.msg_iovlen = 1;
+	msg.msg_name = NULL;
+	msg.msg_namelen = 0;
+	msg.msg_control = ctrl;
+	msg.msg_controllen = sizeof(ctrl);
+
+	n = recvmsg(fd, &msg, MSG_ERRQUEUE);
+	if (n == -1)
+		ASSERT_EQ(errno, EAGAIN, "recvmsg MSG_ERRQUEUE");
+
+	if (n >= 0)
+		test_recv_errmsg_cmsg(&msg);
+
+	return n == -1;
+}
+
+static void test_socket_timestamping(int fd)
+{
+	while (!socket_recv_errmsg(fd));
+
+	ASSERT_EQ(SK_TS_SCHED, 1, "SCM_TSTAMP_SCHED");
+	ASSERT_EQ(SK_TS_TXSW, 1, "SCM_TSTAMP_SND");
+	ASSERT_EQ(SK_TS_ACK, 1, "SCM_TSTAMP_ACK");
+
+	SK_TS_SCHED = 0;
+	SK_TS_TXSW = 0;
+	SK_TS_ACK = 0;
+}
+
+static void test_tcp(int family, bool enable_socket_timestamping)
+{
+	struct net_timestamping__bss *bss;
+	char buf[cfg_payload_len];
+	int sfd = -1, cfd = -1;
+	unsigned int sock_opt;
+	struct netns_obj *ns;
+	int cg_fd;
+	int ret;
+
+	cg_fd = test__join_cgroup(CG_NAME);
+	if (!ASSERT_OK_FD(cg_fd, "join cgroup"))
+		return;
+
+	ns = netns_new("net_timestamping_ns", true);
+	if (!ASSERT_OK_PTR(ns, "create ns"))
+		goto out;
+
+	skel = net_timestamping__open_and_load();
+	if (!ASSERT_OK_PTR(skel, "open and load skel"))
+		goto out;
+
+	if (!ASSERT_OK(net_timestamping__attach(skel), "attach skel"))
+		goto out;
+
+	skel->links.skops_sockopt =
+		bpf_program__attach_cgroup(skel->progs.skops_sockopt, cg_fd);
+	if (!ASSERT_OK_PTR(skel->links.skops_sockopt, "attach cgroup"))
+		goto out;
+
+	bss = skel->bss;
+	memset(bss, 0, sizeof(*bss));
+
+	skel->bss->monitored_pid = getpid();
+
+	sfd = start_server(family, SOCK_STREAM,
+			   family == AF_INET6 ? addr6_str : addr4_str, 0, 0);
+	if (!ASSERT_OK_FD(sfd, "start_server"))
+		goto out;
+
+	cfd = connect_to_fd(sfd, 0);
+	if (!ASSERT_OK_FD(cfd, "connect_to_fd_server"))
+		goto out;
+
+	if (enable_socket_timestamping) {
+		sock_opt = SOF_TIMESTAMPING_SOFTWARE |
+			   SOF_TIMESTAMPING_OPT_ID |
+			   SOF_TIMESTAMPING_TX_SCHED |
+			   SOF_TIMESTAMPING_TX_SOFTWARE |
+			   SOF_TIMESTAMPING_TX_ACK;
+		ret = setsockopt(cfd, SOL_SOCKET, SO_TIMESTAMPING,
+				 (char *) &sock_opt, sizeof(sock_opt));
+		if (!ASSERT_OK(ret, "setsockopt SO_TIMESTAMPING"))
+			goto out;
+
+		ret = clock_gettime(CLOCK_REALTIME, &usr_ts);
+		if (!ASSERT_OK(ret, "get user time"))
+			goto out;
+	}
+
+	ret = write(cfd, buf, sizeof(buf));
+	if (!ASSERT_EQ(ret, sizeof(buf), "send to server"))
+		goto out;
+
+	if (enable_socket_timestamping)
+		test_socket_timestamping(cfd);
+
+	ASSERT_EQ(bss->nr_active, 1, "nr_active");
+	ASSERT_EQ(bss->nr_snd, 2, "nr_snd");
+	ASSERT_EQ(bss->nr_sched, 1, "nr_sched");
+	ASSERT_EQ(bss->nr_txsw, 1, "nr_txsw");
+	ASSERT_EQ(bss->nr_ack, 1, "nr_ack");
+
+out:
+	if (sfd >= 0)
+		close(sfd);
+	if (cfd >= 0)
+		close(cfd);
+	net_timestamping__destroy(skel);
+	netns_free(ns);
+	close(cg_fd);
+}
+
+void test_net_timestamping(void)
+{
+	if (test__start_subtest("INET4: bpf timestamping"))
+		test_tcp(AF_INET, false);
+	if (test__start_subtest("INET4: bpf and socket timestamping"))
+		test_tcp(AF_INET, true);
+	if (test__start_subtest("INET6: bpf timestamping"))
+		test_tcp(AF_INET6, false);
+	if (test__start_subtest("INET6: bpf and socket timestamping"))
+		test_tcp(AF_INET6, true);
+}
diff --git a/tools/testing/selftests/bpf/progs/net_timestamping.c b/tools/testing/selftests/bpf/progs/net_timestamping.c
new file mode 100644
index 000000000000..b4c2f0f2be11
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/net_timestamping.c
@@ -0,0 +1,248 @@
+#include "vmlinux.h"
+#include "bpf_tracing_net.h"
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+#include "bpf_misc.h"
+#include "bpf_kfuncs.h"
+#include <errno.h>
+
+__u32 monitored_pid = 0;
+
+int nr_active;
+int nr_snd;
+int nr_passive;
+int nr_sched;
+int nr_txsw;
+int nr_ack;
+
+struct sk_stg {
+	__u64 sendmsg_ns;	/* record ts when sendmsg is called */
+};
+
+struct sk_tskey {
+	u64 cookie;
+	u32 tskey;
+};
+
+struct delay_info {
+	u64 sendmsg_ns;		/* record ts when sendmsg is called */
+	u32 sched_delay;	/* SCHED_CB - sendmsg_ns */
+	u32 snd_sw_delay;	/* SND_SW_CB - SCHED_CB */
+	u32 ack_delay;		/* ACK_CB - SND_SW_CB */
+};
+
+struct {
+	__uint(type, BPF_MAP_TYPE_SK_STORAGE);
+	__uint(map_flags, BPF_F_NO_PREALLOC);
+	__type(key, int);
+	__type(value, struct sk_stg);
+} sk_stg_map SEC(".maps");
+
+struct {
+	__uint(type, BPF_MAP_TYPE_HASH);
+	__type(key, struct sk_tskey);
+	__type(value, struct delay_info);
+	__uint(max_entries, 1024);
+} time_map SEC(".maps");
+
+static u64 delay_tolerance_nsec = 10000000000; /* 10 second as an example */
+
+extern int bpf_sock_ops_enable_tx_tstamp(struct bpf_sock_ops_kern *skops, u64 flags) __ksym;
+
+static int bpf_test_sockopt(void *ctx, const struct sock *sk, int expected)
+{
+	int tmp, new = SK_BPF_CB_TX_TIMESTAMPING;
+	int opt = SK_BPF_CB_FLAGS;
+	int level = SOL_SOCKET;
+
+	if (bpf_setsockopt(ctx, level, opt, &new, sizeof(new)) != expected)
+		return 1;
+
+	if (bpf_getsockopt(ctx, level, opt, &tmp, sizeof(tmp)) != expected ||
+	    (!expected && tmp != new))
+		return 1;
+
+	return 0;
+}
+
+static bool bpf_test_access_sockopt(void *ctx, const struct sock *sk)
+{
+	if (bpf_test_sockopt(ctx, sk, -EOPNOTSUPP))
+		return true;
+	return false;
+}
+
+static bool bpf_test_access_load_hdr_opt(struct bpf_sock_ops *skops)
+{
+	u8 opt[3] = {0};
+	int load_flags = 0;
+	int ret;
+
+	ret = bpf_load_hdr_opt(skops, opt, sizeof(opt), load_flags);
+	if (ret != -EOPNOTSUPP)
+		return true;
+
+	return false;
+}
+
+static bool bpf_test_access_cb_flags_set(struct bpf_sock_ops *skops)
+{
+	int ret;
+
+	ret = bpf_sock_ops_cb_flags_set(skops, 0);
+	if (ret != -EOPNOTSUPP)
+		return true;
+
+	return false;
+}
+
+/* In the timestamping callbacks, we're not allowed to call the following
+ * BPF CALLs for the safety concern. Return false if expected.
+ */
+static bool bpf_test_access_bpf_calls(struct bpf_sock_ops *skops,
+				      const struct sock *sk)
+{
+	if (bpf_test_access_sockopt(skops, sk))
+		return true;
+
+	if (bpf_test_access_load_hdr_opt(skops))
+		return true;
+
+	if (bpf_test_access_cb_flags_set(skops))
+		return true;
+
+	return false;
+}
+
+static bool bpf_test_delay(struct bpf_sock_ops *skops, const struct sock *sk)
+{
+	struct bpf_sock_ops_kern *skops_kern;
+	u64 timestamp = bpf_ktime_get_ns();
+	struct skb_shared_info *shinfo;
+	struct delay_info dinfo = {0};
+	struct sk_tskey key = {0};
+	struct delay_info *val;
+	struct sk_buff *skb;
+	struct sk_stg *stg;
+	u64 prior_ts, delay;
+
+	if (bpf_test_access_bpf_calls(skops, sk))
+		return false;
+
+	skops_kern = bpf_cast_to_kern_ctx(skops);
+	skb = skops_kern->skb;
+	shinfo = bpf_core_cast(skb->head + skb->end, struct skb_shared_info);
+
+	key.cookie = bpf_get_socket_cookie(skops);
+	if (!key.cookie)
+		return false;
+
+	if (skops->op == BPF_SOCK_OPS_TSTAMP_SENDMSG_CB) {
+		stg = bpf_sk_storage_get(&sk_stg_map, (void *)sk, 0, 0);
+		if (!stg)
+			return false;
+		dinfo.sendmsg_ns = stg->sendmsg_ns;
+		bpf_sock_ops_enable_tx_tstamp(skops_kern, 0);
+		key.tskey = shinfo->tskey;
+		if (!key.tskey)
+			return false;
+		bpf_map_update_elem(&time_map, &key, &dinfo, BPF_ANY);
+		return true;
+	}
+
+	key.tskey = shinfo->tskey;
+	if (!key.tskey)
+		return false;
+
+	val = bpf_map_lookup_elem(&time_map, &key);
+	if (!val)
+		return false;
+
+	switch (skops->op) {
+	case BPF_SOCK_OPS_TSTAMP_SCHED_CB:
+		val->sched_delay = timestamp - val->sendmsg_ns;
+		delay = val->sched_delay;
+		break;
+	case BPF_SOCK_OPS_TSTAMP_SND_SW_CB:
+		prior_ts = val->sched_delay + val->sendmsg_ns;
+		val->snd_sw_delay = timestamp - prior_ts;
+		delay = val->snd_sw_delay;
+		break;
+	case BPF_SOCK_OPS_TSTAMP_ACK_CB:
+		prior_ts = val->snd_sw_delay + val->sched_delay + val->sendmsg_ns;
+		val->ack_delay = timestamp - prior_ts;
+		delay = val->ack_delay;
+		break;
+	}
+
+	if (delay >= delay_tolerance_nsec)
+		return false;
+
+	/* Since it's the last one, remove from the map after latency check */
+	if (skops->op == BPF_SOCK_OPS_TSTAMP_ACK_CB)
+		bpf_map_delete_elem(&time_map, &key);
+
+	return true;
+}
+
+SEC("fentry/tcp_sendmsg_locked")
+int BPF_PROG(trace_tcp_sendmsg_locked, struct sock *sk, struct msghdr *msg,
+	     size_t size)
+{
+	__u32 pid = bpf_get_current_pid_tgid() >> 32;
+	u64 timestamp = bpf_ktime_get_ns();
+	u32 flag = sk->sk_bpf_cb_flags;
+	struct sk_stg *stg;
+
+	if (pid != monitored_pid || !flag)
+		return 0;
+
+	stg = bpf_sk_storage_get(&sk_stg_map, sk, 0,
+				 BPF_SK_STORAGE_GET_F_CREATE);
+	if (!stg)
+		return 0;
+
+	stg->sendmsg_ns = timestamp;
+	nr_snd += 1;
+	return 0;
+}
+
+SEC("sockops")
+int skops_sockopt(struct bpf_sock_ops *skops)
+{
+	struct bpf_sock *bpf_sk = skops->sk;
+	const struct sock *sk;
+
+	if (!bpf_sk)
+		return 1;
+
+	sk = (struct sock *)bpf_skc_to_tcp_sock(bpf_sk);
+	if (!sk)
+		return 1;
+
+	switch (skops->op) {
+	case BPF_SOCK_OPS_ACTIVE_ESTABLISHED_CB:
+		nr_active += !bpf_test_sockopt(skops, sk, 0);
+		break;
+	case BPF_SOCK_OPS_TSTAMP_SENDMSG_CB:
+		if (bpf_test_delay(skops, sk))
+			nr_snd += 1;
+		break;
+	case BPF_SOCK_OPS_TSTAMP_SCHED_CB:
+		if (bpf_test_delay(skops, sk))
+			nr_sched += 1;
+		break;
+	case BPF_SOCK_OPS_TSTAMP_SND_SW_CB:
+		if (bpf_test_delay(skops, sk))
+			nr_txsw += 1;
+		break;
+	case BPF_SOCK_OPS_TSTAMP_ACK_CB:
+		if (bpf_test_delay(skops, sk))
+			nr_ack += 1;
+		break;
+	}
+
+	return 1;
+}
+
+char _license[] SEC("license") = "GPL";