mirror of
https://github.com/xdp-project/bpf-examples.git
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Merge pull request #15 from freysteinn/master
Added an eBPF Qdisc classifier example
This commit is contained in:
Toke Høiland-Jørgensen
GitHub
31
tc-basic-classifier/Makefile
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31
tc-basic-classifier/Makefile
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# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
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TC_BPF_TARGETS := filter
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BPF_TARGETS += $(TC_BPF_TARGETS)
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EXTRA_DEPS += config.mk
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LIB_DIR = ../lib
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include $(LIB_DIR)/common.mk
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include config.mk
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all: config.mk
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config.mk: configure
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@sh configure
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ifndef HAVE_TC_LIBBPF
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# If the iproute2 'tc' tool doesn't understand BTF debug info
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# use llvm-strip to remove this debug info from object file
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#
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# *BUT* cannot strip everything as it removes ELF elems needed for
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# creating maps
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#
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.PHONY: strip_tc_obj
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strip_tc_obj: ${TC_BPF_TARGETS:=.o}
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$(Q) echo "TC don't support libbpf - strip BTF info"
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$(Q) llvm-strip --no-strip-all --remove-section .BTF $?
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all: strip_tc_obj
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endif
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66
tc-basic-classifier/README.org
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66
tc-basic-classifier/README.org
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#+TITLE: eBPF Qdisc classifier example
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This example demonstrates how to write a simple eBPF Qdisc classifier that
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classifies flows depending on their destination TCP port. The example script,
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runner.sh shows how you can use the eBPF Qdisc classifier and implement the same
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functionality using u32. The script creates two network namespaces called
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Left and Right, representing two different hosts, as seen in Figure 1. The
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script then illustrates the classifiers in action using iperf3.
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#+CAPTION: The figure depicts the network and classifier setup of the two network namespaces setup provided by the runner.sh script.
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#+NAME: fig:Figure 1
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[[./overview.png]]
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The Left namespace loads a Qdisc classifier that rate-limit TCP ports 8080 and
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8082 to get a higher rate than default traffic. The runner.sh script shows the
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higher rate limits by connecting to both target ports and TCP port 8082 to
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establish the default rate limit of 20 Mbps.
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To run the application, choose either the "bpf" or "u32" parameters:
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#+BEGIN_SRC bash
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[root@bpfexamples]# ./runner.sh bpf
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bash-5.0# ./runner.sh bpf
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Starting setup
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Starting iperf3
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Connecting to host 172.16.16.20, port 8080
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[ 5] local 172.16.16.10 port 56332 connected to 172.16.16.20 port 8080
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[ ID] Interval Transfer Bitrate Retr Cwnd
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[ 5] 0.00-1.00 sec 9.51 MBytes 79.8 Mbits/sec 0 86.3 KBytes
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[ 5] 1.00-2.00 sec 9.38 MBytes 78.7 Mbits/sec 0 112 KBytes
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[ 5] 2.00-3.00 sec 8.95 MBytes 75.1 Mbits/sec 0 112 KBytes
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[ 5] 3.00-4.00 sec 9.20 MBytes 77.2 Mbits/sec 0 112 KBytes
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- - - - - - - - - - - - - - - - - - - - - - - - -
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[ ID] Interval Transfer Bitrate Retr
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[ 5] 0.00-4.00 sec 37.0 MBytes 77.7 Mbits/sec 0 sender
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[ 5] 0.00-4.01 sec 36.5 MBytes 76.4 Mbits/sec receiver
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iperf Done.
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Connecting to host 172.16.16.20, port 8081
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[ 5] local 172.16.16.10 port 45084 connected to 172.16.16.20 port 8081
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[ ID] Interval Transfer Bitrate Retr Cwnd
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[ 5] 0.00-1.00 sec 4.92 MBytes 41.3 Mbits/sec 0 62.2 KBytes
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[ 5] 1.00-2.00 sec 4.47 MBytes 37.5 Mbits/sec 0 62.2 KBytes
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[ 5] 2.00-3.00 sec 4.66 MBytes 39.1 Mbits/sec 0 62.2 KBytes
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[ 5] 3.00-4.00 sec 4.47 MBytes 37.5 Mbits/sec 0 62.2 KBytes
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- - - - - - - - - - - - - - - - - - - - - - - - -
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[ ID] Interval Transfer Bitrate Retr
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[ 5] 0.00-4.00 sec 18.5 MBytes 38.9 Mbits/sec 0 sender
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[ 5] 0.00-4.01 sec 18.3 MBytes 38.2 Mbits/sec receiver
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iperf Done.
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Connecting to host 172.16.16.20, port 8082
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[ 5] local 172.16.16.10 port 33196 connected to 172.16.16.20 port 8082
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[ ID] Interval Transfer Bitrate Retr Cwnd
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[ 5] 0.00-1.00 sec 2.94 MBytes 24.6 Mbits/sec 0 153 KBytes
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[ 5] 1.00-2.00 sec 2.49 MBytes 20.9 Mbits/sec 0 153 KBytes
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[ 5] 2.00-3.00 sec 2.17 MBytes 18.2 Mbits/sec 0 153 KBytes
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[ 5] 3.00-4.00 sec 2.17 MBytes 18.2 Mbits/sec 0 153 KBytes
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- - - - - - - - - - - - - - - - - - - - - - - - -
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[ ID] Interval Transfer Bitrate Retr
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[ 5] 0.00-4.00 sec 9.77 MBytes 20.5 Mbits/sec 0 sender
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[ 5] 0.00-4.01 sec 9.14 MBytes 19.1 Mbits/sec receiver
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iperf Done.
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[root@bpfexamples]# ./runner.sh bpf
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#+END_SRC
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29
tc-basic-classifier/configure
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29
tc-basic-classifier/configure
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#!/bin/bash
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# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
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# This is not an autoconf generated configure
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#
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# Output file which is input to Makefile
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CONFIG=config.mk
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# Assume tc is in $PATH
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TC=tc
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check_tc_libbpf()
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{
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tc_version=$($TC -V)
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if echo $tc_version | grep -q libbpf; then
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libbpf_version=${tc_version##*libbpf }
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echo "HAVE_TC_LIBBPF:=y" >> $CONFIG
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echo "BPF_CFLAGS += -DHAVE_TC_LIBBPF" >> $CONFIG
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echo "yes ($libbpf_version)"
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else
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echo "no"
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fi
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}
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echo "# Generated config" > $CONFIG
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echo "Detecting available features on system"
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echo -n " - libbpf support in tc tool: "
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check_tc_libbpf
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70
tc-basic-classifier/filter.c
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70
tc-basic-classifier/filter.c
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/* SPDX-License-Identifier: GPL-2.0 */
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/* Copyright 2021 Frey Alfredsson <freysteinn@freysteinn.com> */
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/* Based on code by Jesper Dangaard Brouer <brouer@redhat.com> */
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#include <linux/bpf.h>
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#include <bpf/bpf_helpers.h>
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#include <linux/pkt_sched.h>
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#include <linux/pkt_cls.h>
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#include "../include/xdp/parsing_helpers.h"
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/*
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* This example eBPF code mirrors the TC u32 rules set in the runner.sh
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* script, where the script gives different rate limits depending on if the TCP
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* traffic is for ports 8080 or 8081. It must be loaded with the direct-action
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* flag on TC to function, as this is a Qdisc classifier, not a Qdisc action. The
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* runner.sh script shows an example of how it is loaded and used.
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*/
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SEC("classifier")
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int cls_filter(struct __sk_buff *skb)
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{
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void *data_end = (void *)(unsigned long long)skb->data_end;
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void *data = (void *)(unsigned long long)skb->data;
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struct hdr_cursor nh;
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struct ethhdr *eth;
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int eth_type;
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int ip_type;
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int tcp_type;
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struct iphdr *iphdr;
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struct ipv6hdr *ipv6hdr;
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struct tcphdr *tcphdr;
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skb->tc_classid = 0x30; /* Default class */
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nh.pos = data;
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/* Parse Ethernet and IP/IPv6 headers */
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eth_type = parse_ethhdr(&nh, data_end, ð);
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if (eth_type == bpf_htons(ETH_P_IP)) {
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ip_type = parse_iphdr(&nh, data_end, &iphdr);
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if (ip_type != IPPROTO_TCP)
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goto out;
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}
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else if (eth_type == bpf_htons(ETH_P_IPV6)) {
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ip_type = parse_ip6hdr(&nh, data_end, &ipv6hdr);
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if (ip_type != IPPROTO_TCP)
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goto out;
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} else {
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goto out;
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}
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/* Classify TCP ports 8080 and 8081 */
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tcp_type = parse_tcphdr(&nh, data_end, &tcphdr);
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if (tcphdr + 1 > data_end) {
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goto out;
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}
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switch (tcphdr->dest) {
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case bpf_htons(8080):
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skb->tc_classid = 0x10; /* Handles are always in hex */
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break;
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case bpf_htons(8081):
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skb->tc_classid = 0x20;
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}
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out:
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return TC_ACT_OK;
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}
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char _license[] SEC("license") = "GPL";
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BIN
tc-basic-classifier/overview.png
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BIN
tc-basic-classifier/overview.png
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Binary file not shown.
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After Width: | Height: | Size: 39 KiB |
103
tc-basic-classifier/runner.sh
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103
tc-basic-classifier/runner.sh
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#!/bin/bash
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# SPDX-License-Identifier: GPL-2.0
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# Copyright 2021 Frey Alfredsson <freysteinn@freysteinn.com>
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set -o errexit
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set -o nounset
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### Configuration
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IP="ip"
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TC="tc"
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# Left and right IPs
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L_IP=172.16.16.10
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R_IP=172.16.16.20
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L_CIDR="${L_IP}/24"
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R_CIDR="${R_IP}/24"
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LIMIT=100mbit
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START_RATE=5mbit
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P8080_LIMIT=80mbit
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P8081_LIMIT=40mbit
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DEFAULT_LIMIT=20mbit
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### Constants
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L_NS="left"
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R_NS="right"
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L_DEV="$L_NS-veth"
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R_DEV="$R_NS-veth"
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### Helper functions
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function filter-help() {
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cat <<-EOF
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Usage: [<bpf> | <u32>]
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Runs an example that either uses an eBPF based Qdisc filter or an u32
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filter to rate limit traffic destined for TCP ports 8080 and 8081. It
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relies on iperf3 to demonstrates the functionality.
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The following are mandatory arguments. Without them prints this help.
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u32 Runs the example with the u32 Qdisc filter
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bpf Runs the example with the bpf Qdisc filterdiff
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Please look at the script's source code to see how the examples differ.
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EOF
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}
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### Script main
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if [ $# -ne 1 ] || [[ "${1-}" != "bpf" && "${1-}" != "u32" ]]; then
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filter-help
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exit 1
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fi
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mode="$1"
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echo "Starting setup"
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# Remove network namespaces if this is the second run
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$IP netns delete "$L_NS" &> /dev/null || true
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$IP netns delete "$R_NS" &> /dev/null || true
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# Create network namespaces
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$IP netns add "$L_NS"
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$IP netns add "$R_NS"
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# Create connected virtual nics
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$IP link add "$L_DEV" type veth peer "$R_DEV"
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# Add the virtual nics to the network namespaces
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$IP link set "$L_DEV" netns "$L_NS"
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$IP link set "$R_DEV" netns "$R_NS"
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# Add IP addresses to links
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$IP -netns "$L_NS" addr add "$L_CIDR" dev "$L_DEV"
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$IP -netns "$R_NS" addr add "$R_CIDR" dev "$R_DEV"
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# Enable links
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$IP -netns "$L_NS" link set "$L_DEV" up
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$IP -netns "$R_NS" link set "$R_DEV" up
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# Setting up the qdiscs on Left
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$TC -netns "$L_NS" qdisc add dev "$L_DEV" root handle 1:0 htb default 30
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TC_CLASS_ADD="$TC -netns $L_NS class add dev $L_DEV parent"
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$TC_CLASS_ADD 1:0 classid 1:1 htb rate "$LIMIT"
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$TC_CLASS_ADD 1:1 classid 1:10 htb rate "$START_RATE" ceil "$P8080_LIMIT"
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$TC_CLASS_ADD 1:1 classid 1:20 htb rate "$START_RATE" ceil "$P8081_LIMIT"
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$TC_CLASS_ADD 1:1 classid 1:30 htb rate "$START_RATE" ceil "$DEFAULT_LIMIT"
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# Setup filters
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if [ "$mode" == "bpf" ]; then
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$TC -netns $L_NS filter add dev $L_DEV protocol ip parent 1:0 \
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bpf obj filter.o classid 1: direct-action
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else
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U32="$TC -netns $L_NS filter add dev $L_DEV protocol ip parent 1:0 prio 1 u32"
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$U32 match ip dport 8080 FFFF flowid 1:10
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$U32 match ip dport 8081 FFFF flowid 1:20
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fi
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# Setup iperf3
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echo "Starting iperf3"
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$IP netns exec "$R_NS" iperf3 -s -p 8080 &> /dev/null &
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$IP netns exec "$R_NS" iperf3 -s -p 8081 &> /dev/null &
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$IP netns exec "$R_NS" iperf3 -s -p 8082 &> /dev/null &
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sleep 1
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$IP netns exec "$L_NS" iperf3 -t 4 -c "$R_IP" -p 8080
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$IP netns exec "$L_NS" iperf3 -t 4 -c "$R_IP" -p 8081
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$IP netns exec "$L_NS" iperf3 -t 4 -c "$R_IP" -p 8082
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