Adds support for calling sock_ops BPF program when there is a
retransmission. Two arguments are used; one for the sequence number and
other for the number of segments retransmitted. Does not include syn-ack
retransmissions.
New op: BPF_SOCK_OPS_RETRANS_CB.
Signed-off-by: Lawrence Brakmo <bra...@fb.com>
---
include/uapi/linux/bpf.h | 4 ++++
include/uapi/linux/tcp.h | 3 ++-
net/ipv4/tcp_output.c | 3 +++
3 files changed, 9 insertions(+), 1 deletion(-)
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 1c80ff4..2f752f3 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -1039,6 +1039,10 @@ enum {
* Arg2: value of icsk_rto
* Arg3: whether RTO has expired
*/
+ BPF_SOCK_OPS_RETRANS_CB, /* Called when skb is retransmitted.
+ * Arg1: sequence number of 1st byte
+ * Arg2: # segments
+ */
};
#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 129032ca..ec03a2b 100644
--- a/include/uapi/linux/tcp.h
+++ b/include/uapi/linux/tcp.h
@@ -270,7 +270,8 @@ struct tcp_diag_md5sig {
/* Definitions for bpf_sock_ops_cb_flags */
#define BPF_SOCK_OPS_RTO_CB_FLAG (1<<0)
-#define BPF_SOCK_OPS_ALL_CB_FLAGS 0x1 /* Mask of all currently
+#define BPF_SOCK_OPS_RETRANS_CB_FLAG (1<<1)
+#define BPF_SOCK_OPS_ALL_CB_FLAGS 0x3 /* Mask of all currently
* supported cb flags
*/
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index d12f7f7..f7d34f01 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -2908,6 +2908,9 @@ int __tcp_retransmit_skb(struct sock *sk, struct sk_buff
*skb, int segs)
if (likely(!err)) {
TCP_SKB_CB(skb)->sacked |= TCPCB_EVER_RETRANS;
trace_tcp_retransmit_skb(sk, skb);
+ if (BPF_SOCK_OPS_TEST_FLAG(tp, BPF_SOCK_OPS_RETRANS_CB_FLAG))
+ tcp_call_bpf_2arg(sk, BPF_SOCK_OPS_RETRANS_CB,
+ TCP_SKB_CB(skb)->seq, segs);
} else if (err != -EBUSY) {
NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPRETRANSFAIL);
}
--
2.9.5
