netdev - [PATCH bpf 06/11] bpf: Add sock

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Message-ID: <20171219062200.372711-7-brakmo@fb.com>
Date:   Mon, 18 Dec 2017 22:21:55 -0800
From:   Lawrence Brakmo <brakmo@...com>
To:     netdev <netdev@...r.kernel.org>
CC:     Kernel Team <kernel-team@...com>, Blake Matheny <bmatheny@...com>,
        Alexei Starovoitov <ast@...com>,
        Daniel Borkmann <daniel@...earbox.net>
Subject: [PATCH bpf 06/11] bpf: Add sock_ops RTO callback

Adds an optional call to sock_ops BPF program based on whether the
BPF_SOCK_OPS_RTO_CB_FLAG is set in bpf_sock_ops_flags.
The BPF program is passed 2 arguments: icsk_retransmits and whether the
RTO has expired.

Signed-off-by: Lawrence Brakmo <brakmo@...com>
---
 include/uapi/linux/bpf.h | 5 +++++
 include/uapi/linux/tcp.h | 3 +++
 net/ipv4/tcp_timer.c     | 9 +++++++++
 3 files changed, 17 insertions(+)

diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index dfbf43a..1c36795 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -989,6 +989,11 @@ enum {
 					 * a congestion threshold. RTTs above
 					 * this indicate congestion
 					 */
+	BPF_SOCK_OPS_RTO_CB,		/* Called when an RTO has triggered.
+					 * Arg1: value of icsk_retransmits
+					 * Arg2: value of icsk_rto
+					 * Arg3: whether RTO has expired
+					 */
 };
 
 #define TCP_BPF_IW		1001	/* Set TCP initial congestion window */
diff --git a/include/uapi/linux/tcp.h b/include/uapi/linux/tcp.h
index b4a4f64..089c19e 100644
--- a/include/uapi/linux/tcp.h
+++ b/include/uapi/linux/tcp.h
@@ -259,6 +259,9 @@ struct tcp_md5sig {
 	__u8	tcpm_key[TCP_MD5SIG_MAXKEYLEN];		/* key (binary) */
 };
 
+/* Definitions for bpf_sock_ops_flags */
+#define BPF_SOCK_OPS_RTO_CB_FLAG	(1<<0)
+
 /* INET_DIAG_MD5SIG */
 struct tcp_diag_md5sig {
 	__u8	tcpm_family;
diff --git a/net/ipv4/tcp_timer.c b/net/ipv4/tcp_timer.c
index 16df6dd..e6afd93 100644
--- a/net/ipv4/tcp_timer.c
+++ b/net/ipv4/tcp_timer.c
@@ -230,9 +230,18 @@ static int tcp_write_timeout(struct sock *sk)
 	}
 	if (expired) {
 		/* Has it gone just too far? */
+		if (BPF_SOCK_OPS_TEST_FLAG(tp, BPF_SOCK_OPS_RTO_CB_FLAG))
+			tcp_call_bpf_3arg(sk, BPF_SOCK_OPS_RTO_CB,
+					  icsk->icsk_retransmits,
+					  icsk->icsk_rto, 1);
 		tcp_write_err(sk);
 		return 1;
 	}
+
+	if (BPF_SOCK_OPS_TEST_FLAG(tp, BPF_SOCK_OPS_RTO_CB_FLAG))
+		tcp_call_bpf_3arg(sk, BPF_SOCK_OPS_RTO_CB,
+				  icsk->icsk_retransmits,
+				  icsk->icsk_rto, 0);
 	return 0;
 }
 
-- 
2.9.5