[bpf-next,09/10] tcp: bpf: Add TCP_BPF_DELACK_MAX and TCP_BPF_RTO_MIN to bpf_setsockopt

Message ID 20200626175558.1462731-1-kafai@fb.com
State New
Headers show
Series
  • Untitled series #40562
Related show

Commit Message

Martin KaFai Lau June 26, 2020, 5:55 p.m.
This change is mostly from an internal patch and adapts it from sysctl
config to the bpf_setsockopt setup.

The bpf_prog can set the max delay ack by using
bpf_setsockopt(TCP_BPF_DELACK_MAX).  This max delay ack can be communicated
to its peer through bpf header option.  The receiving peer can then use
this max delay ack and set a potentially lower rto by using
bpf_setsockopt(TCP_BPF_RTO_MIN).  A latter patch will use it
like this in a test as an example.

Signed-off-by: Martin KaFai Lau <kafai@fb.com>
---
 include/net/inet_connection_sock.h |  2 ++
 include/net/tcp.h                  |  2 +-
 include/uapi/linux/bpf.h           |  2 ++
 net/core/filter.c                  | 15 +++++++++++++++
 net/ipv4/tcp.c                     |  4 ++++
 net/ipv4/tcp_output.c              |  2 ++
 tools/include/uapi/linux/bpf.h     |  2 ++
 7 files changed, 28 insertions(+), 1 deletion(-)

Patch

diff --git a/include/net/inet_connection_sock.h b/include/net/inet_connection_sock.h
index e5b388f5fa20..43d45864e5f0 100644
--- a/include/net/inet_connection_sock.h
+++ b/include/net/inet_connection_sock.h
@@ -93,6 +93,8 @@  struct inet_connection_sock {
  	struct timer_list	  icsk_retransmit_timer;
  	struct timer_list	  icsk_delack_timer;
 	__u32			  icsk_rto;
+	__u32                     icsk_rto_min;
+	__u32                     icsk_delack_max;
 	__u32			  icsk_pmtu_cookie;
 	const struct tcp_congestion_ops *icsk_ca_ops;
 	const struct inet_connection_sock_af_ops *icsk_af_ops;
diff --git a/include/net/tcp.h b/include/net/tcp.h
index e93ef2d324f3..8a682d678971 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -703,7 +703,7 @@  static inline void tcp_fast_path_check(struct sock *sk)
 static inline u32 tcp_rto_min(struct sock *sk)
 {
 	const struct dst_entry *dst = __sk_dst_get(sk);
-	u32 rto_min = TCP_RTO_MIN;
+	u32 rto_min = inet_csk(sk)->icsk_rto_min;
 
 	if (dst && dst_metric_locked(dst, RTAX_RTO_MIN))
 		rto_min = dst_metric_rtt(dst, RTAX_RTO_MIN);
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 479b83d05811..2ccc81548eef 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -4299,6 +4299,8 @@  enum {
 	 *	    is not saved by TCP_SAVE_SYN.
 	 */
 	TCP_BPF_SYN_HDR_OPT	= 1003,
+	TCP_BPF_DELACK_MAX	= 1004, /* Max delay ack in usecs */
+	TCP_BPF_RTO_MIN		= 1005, /* Min delay ack in usecs */
 };
 
 struct bpf_perf_event_value {
diff --git a/net/core/filter.c b/net/core/filter.c
index 5784f1bede2f..4b80934e6876 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -4431,6 +4431,7 @@  static int _bpf_setsockopt(struct sock *sk, int level, int optname,
 		} else {
 			struct inet_connection_sock *icsk = inet_csk(sk);
 			struct tcp_sock *tp = tcp_sk(sk);
+			unsigned long timeout;
 
 			if (optlen != sizeof(int))
 				return -EINVAL;
@@ -4452,6 +4453,20 @@  static int _bpf_setsockopt(struct sock *sk, int level, int optname,
 					tp->snd_ssthresh = val;
 				}
 				break;
+			case TCP_BPF_DELACK_MAX:
+				timeout = usecs_to_jiffies(val);
+				if (timeout > TCP_DELACK_MAX ||
+				    timeout < TCP_TIMEOUT_MIN)
+					return -EINVAL;
+				inet_csk(sk)->icsk_delack_max = timeout;
+				break;
+			case TCP_BPF_RTO_MIN:
+				timeout = usecs_to_jiffies(val);
+				if (timeout > TCP_RTO_MIN ||
+				    timeout < TCP_TIMEOUT_MIN)
+					return -EINVAL;
+				inet_csk(sk)->icsk_rto_min = timeout;
+				break;
 			case TCP_SAVE_SYN:
 				if (val < 0 || val > 1)
 					ret = -EINVAL;
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 60093a211f4d..02be3e2a2fdb 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -418,6 +418,8 @@  void tcp_init_sock(struct sock *sk)
 	INIT_LIST_HEAD(&tp->tsorted_sent_queue);
 
 	icsk->icsk_rto = TCP_TIMEOUT_INIT;
+	icsk->icsk_rto_min = TCP_RTO_MIN;
+	icsk->icsk_delack_max = TCP_DELACK_MAX;
 	tp->mdev_us = jiffies_to_usecs(TCP_TIMEOUT_INIT);
 	minmax_reset(&tp->rtt_min, tcp_jiffies32, ~0U);
 
@@ -2685,6 +2687,8 @@  int tcp_disconnect(struct sock *sk, int flags)
 	icsk->icsk_backoff = 0;
 	icsk->icsk_probes_out = 0;
 	icsk->icsk_rto = TCP_TIMEOUT_INIT;
+	icsk->icsk_rto_min = TCP_RTO_MIN;
+	icsk->icsk_delack_max = TCP_DELACK_MAX;
 	tp->snd_ssthresh = TCP_INFINITE_SSTHRESH;
 	tp->snd_cwnd = TCP_INIT_CWND;
 	tp->snd_cwnd_cnt = 0;
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index a78a29980e1f..db872a2a01c6 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -3899,6 +3899,8 @@  void tcp_send_delayed_ack(struct sock *sk)
 		ato = min(ato, max_ato);
 	}
 
+	ato = min_t(u32, ato, inet_csk(sk)->icsk_delack_max);
+
 	/* Stay within the limit we were given */
 	timeout = jiffies + ato;
 
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index 479b83d05811..2ccc81548eef 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -4299,6 +4299,8 @@  enum {
 	 *	    is not saved by TCP_SAVE_SYN.
 	 */
 	TCP_BPF_SYN_HDR_OPT	= 1003,
+	TCP_BPF_DELACK_MAX	= 1004, /* Max delay ack in usecs */
+	TCP_BPF_RTO_MIN		= 1005, /* Min delay ack in usecs */
 };
 
 struct bpf_perf_event_value {