From mboxrd@z Thu Jan 1 00:00:00 1970 From: Lawrence Brakmo Subject: [RFC PATCH net-next 04/15] bpf: Sample bpf program to set SYN/SYN-ACK RTOs Date: Tue, 13 Jun 2017 10:59:53 -0700 Message-ID: <20170613180004.3008403-5-brakmo@fb.com> References: <20170613180004.3008403-1-brakmo@fb.com> Mime-Version: 1.0 Content-Type: text/plain Cc: Kernel Team , Blake Matheny , Alexei Starovoitov , Daniel Borkmann , David Ahern To: netdev Return-path: Received: from mx0b-00082601.pphosted.com ([67.231.153.30]:44263 "EHLO mx0a-00082601.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1753760AbdFMSAL (ORCPT ); Tue, 13 Jun 2017 14:00:11 -0400 Received: from pps.filterd (m0001255.ppops.net [127.0.0.1]) by mx0b-00082601.pphosted.com (8.16.0.20/8.16.0.20) with SMTP id v5DHv7fv000935 for ; Tue, 13 Jun 2017 11:00:10 -0700 Received: from mail.thefacebook.com ([199.201.64.23]) by mx0b-00082601.pphosted.com with ESMTP id 2b29g4bt3m-1 (version=TLSv1 cipher=ECDHE-RSA-AES256-SHA bits=256 verify=NOT) for ; Tue, 13 Jun 2017 11:00:10 -0700 Received: from facebook.com (2401:db00:11:d025:face:0:13:0) by mx-out.facebook.com (2401:db00:2050:5102:face:0000:003b:0000) with ESMTP id 23712c6c506211e7b8fd77a337fa907c-76b3c8f0 for ; Tue, 13 Jun 2017 11:00:09 -0700 In-Reply-To: <20170613180004.3008403-1-brakmo@fb.com> Sender: netdev-owner@vger.kernel.org List-ID: The sample BPF program, tcp_synrto_kern.c, sets the SYN and SYN-ACK RTOs to 10ms when both hosts are within the same datacenter (i.e. small RTTs) in an environment where common IPv6 prefixes indicate both hosts are in the same data center. Signed-off-by: Lawrence Brakmo --- samples/bpf/Makefile | 1 + samples/bpf/tcp_synrto_kern.c | 53 +++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 54 insertions(+) create mode 100644 samples/bpf/tcp_synrto_kern.c diff --git a/samples/bpf/Makefile b/samples/bpf/Makefile index b13436c..c5008c4 100644 --- a/samples/bpf/Makefile +++ b/samples/bpf/Makefile @@ -113,6 +113,7 @@ always += lwt_len_hist_kern.o always += xdp_tx_iptunnel_kern.o always += test_map_in_map_kern.o always += cookie_uid_helper_example.o +always += tcp_synrto_kern.o HOSTCFLAGS += -I$(objtree)/usr/include HOSTCFLAGS += -I$(srctree)/tools/lib/ diff --git a/samples/bpf/tcp_synrto_kern.c b/samples/bpf/tcp_synrto_kern.c new file mode 100644 index 0000000..1af2a34 --- /dev/null +++ b/samples/bpf/tcp_synrto_kern.c @@ -0,0 +1,53 @@ +/* + * BPF program to set SYN and SYN-ACK RTOs to 10ms when using IPv6 addresses + * and the first 5.5 bytes of the IPv6 addresses are the same (in this example + * that means both hosts are in the same datacenter. + */ + +#include +#include +#include +#include +#include +#include "bpf_helpers.h" + +#define DEBUG 1 + +SEC("sockops") +int bpf_synrto(struct __sk_buff *skb) +{ + struct bpf_socket_ops *skops = (struct bpf_socket_ops *) skb; + char fmt1[] = "BPF command: %d\n"; + char fmt2[] = " Returning %d\n"; + int op; + int rv = -1; + + // For testing purposes, only execute rest of BPF program + // if neither port numberis 55601 + if (skops->remote_port != 55601 && skops->local_port != 55601) + return -1; + + op = (int) skops->op; + +#ifdef DEBUG + bpf_trace_printk(fmt1, sizeof(fmt1), op); +#endif + + // Check for TIMEOUT_INIT operation and IPv6 addresses + if (op == BPF_SOCKET_OPS_TIMEOUT_INIT && + skops->family == AF_INET6) { + + // If the first 5.5 bytes of the IPv6 address are the same + // then both hosts are in the same datacenter + // so use an RTO of 10ms + if (skops->local_ip6[0] == skops->remote_ip6[0] && + (skops->local_ip6[1] & 0xfff00000) == + (skops->remote_ip6[1] & 0xfff00000)) + rv = 10; + } +#ifdef DEBUG + bpf_trace_printk(fmt2, sizeof(fmt2), rv); +#endif + return rv; +} +char _license[] SEC("license") = "GPL"; -- 2.9.3