selftests: bpf: tc-bpf flow shaping with EDT
Add a small test that shows how to shape a TCP flow in tc-bpf with EDT and ECN. Signed-off-by: Peter Oskolkov <posk@google.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Peter Oskolkov
Alexei Starovoitov
parent
315a202987
commit
7df5e3db8f
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@ -53,7 +53,8 @@ TEST_PROGS := test_kmod.sh \
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test_xdp_vlan.sh \
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test_lwt_ip_encap.sh \
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test_tcp_check_syncookie.sh \
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test_tc_tunnel.sh
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test_tc_tunnel.sh \
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test_tc_edt.sh
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TEST_PROGS_EXTENDED := with_addr.sh \
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with_tunnels.sh \
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@ -0,0 +1,109 @@
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// SPDX-License-Identifier: GPL-2.0
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#include <stdint.h>
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#include <linux/bpf.h>
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#include <linux/if_ether.h>
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#include <linux/in.h>
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#include <linux/ip.h>
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#include <linux/pkt_cls.h>
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#include <linux/tcp.h>
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#include "bpf_helpers.h"
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#include "bpf_endian.h"
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/* the maximum delay we are willing to add (drop packets beyond that) */
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#define TIME_HORIZON_NS (2000 * 1000 * 1000)
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#define NS_PER_SEC 1000000000
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#define ECN_HORIZON_NS 5000000
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#define THROTTLE_RATE_BPS (5 * 1000 * 1000)
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/* flow_key => last_tstamp timestamp used */
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struct bpf_map_def SEC("maps") flow_map = {
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.type = BPF_MAP_TYPE_HASH,
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.key_size = sizeof(uint32_t),
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.value_size = sizeof(uint64_t),
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.max_entries = 1,
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};
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static inline int throttle_flow(struct __sk_buff *skb)
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{
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int key = 0;
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uint64_t *last_tstamp = bpf_map_lookup_elem(&flow_map, &key);
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uint64_t delay_ns = ((uint64_t)skb->len) * NS_PER_SEC /
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THROTTLE_RATE_BPS;
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uint64_t now = bpf_ktime_get_ns();
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uint64_t tstamp, next_tstamp = 0;
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if (last_tstamp)
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next_tstamp = *last_tstamp + delay_ns;
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tstamp = skb->tstamp;
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if (tstamp < now)
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tstamp = now;
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/* should we throttle? */
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if (next_tstamp <= tstamp) {
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if (bpf_map_update_elem(&flow_map, &key, &tstamp, BPF_ANY))
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return TC_ACT_SHOT;
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return TC_ACT_OK;
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}
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/* do not queue past the time horizon */
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if (next_tstamp - now >= TIME_HORIZON_NS)
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return TC_ACT_SHOT;
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/* set ecn bit, if needed */
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if (next_tstamp - now >= ECN_HORIZON_NS)
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bpf_skb_ecn_set_ce(skb);
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if (bpf_map_update_elem(&flow_map, &key, &next_tstamp, BPF_EXIST))
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return TC_ACT_SHOT;
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skb->tstamp = next_tstamp;
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return TC_ACT_OK;
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}
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static inline int handle_tcp(struct __sk_buff *skb, struct tcphdr *tcp)
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{
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void *data_end = (void *)(long)skb->data_end;
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/* drop malformed packets */
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if ((void *)(tcp + 1) > data_end)
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return TC_ACT_SHOT;
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if (tcp->dest == bpf_htons(9000))
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return throttle_flow(skb);
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return TC_ACT_OK;
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}
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static inline int handle_ipv4(struct __sk_buff *skb)
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{
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void *data_end = (void *)(long)skb->data_end;
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void *data = (void *)(long)skb->data;
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struct iphdr *iph;
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uint32_t ihl;
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/* drop malformed packets */
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if (data + sizeof(struct ethhdr) > data_end)
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return TC_ACT_SHOT;
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iph = (struct iphdr *)(data + sizeof(struct ethhdr));
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if ((void *)(iph + 1) > data_end)
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return TC_ACT_SHOT;
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ihl = iph->ihl * 4;
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if (((void *)iph) + ihl > data_end)
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return TC_ACT_SHOT;
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if (iph->protocol == IPPROTO_TCP)
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return handle_tcp(skb, (struct tcphdr *)(((void *)iph) + ihl));
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return TC_ACT_OK;
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}
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SEC("cls_test") int tc_prog(struct __sk_buff *skb)
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{
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if (skb->protocol == bpf_htons(ETH_P_IP))
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return handle_ipv4(skb);
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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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@ -0,0 +1,99 @@
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#!/bin/bash
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# SPDX-License-Identifier: GPL-2.0
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#
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# This test installs a TC bpf program that throttles a TCP flow
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# with dst port = 9000 down to 5MBps. Then it measures actual
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# throughput of the flow.
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if [[ $EUID -ne 0 ]]; then
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echo "This script must be run as root"
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echo "FAIL"
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exit 1
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fi
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# check that nc, dd, and timeout are present
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command -v nc >/dev/null 2>&1 || \
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{ echo >&2 "nc is not available"; exit 1; }
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command -v dd >/dev/null 2>&1 || \
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{ echo >&2 "nc is not available"; exit 1; }
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command -v timeout >/dev/null 2>&1 || \
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{ echo >&2 "timeout is not available"; exit 1; }
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readonly NS_SRC="ns-src-$(mktemp -u XXXXXX)"
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readonly NS_DST="ns-dst-$(mktemp -u XXXXXX)"
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readonly IP_SRC="172.16.1.100"
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readonly IP_DST="172.16.2.100"
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cleanup()
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{
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ip netns del ${NS_SRC}
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ip netns del ${NS_DST}
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}
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trap cleanup EXIT
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set -e # exit on error
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ip netns add "${NS_SRC}"
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ip netns add "${NS_DST}"
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ip link add veth_src type veth peer name veth_dst
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ip link set veth_src netns ${NS_SRC}
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ip link set veth_dst netns ${NS_DST}
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ip -netns ${NS_SRC} addr add ${IP_SRC}/24 dev veth_src
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ip -netns ${NS_DST} addr add ${IP_DST}/24 dev veth_dst
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ip -netns ${NS_SRC} link set dev veth_src up
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ip -netns ${NS_DST} link set dev veth_dst up
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ip -netns ${NS_SRC} route add ${IP_DST}/32 dev veth_src
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ip -netns ${NS_DST} route add ${IP_SRC}/32 dev veth_dst
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# set up TC on TX
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ip netns exec ${NS_SRC} tc qdisc add dev veth_src root fq
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ip netns exec ${NS_SRC} tc qdisc add dev veth_src clsact
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ip netns exec ${NS_SRC} tc filter add dev veth_src egress \
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bpf da obj test_tc_edt.o sec cls_test
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# start the listener
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ip netns exec ${NS_DST} bash -c \
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"nc -4 -l -s ${IP_DST} -p 9000 >/dev/null &"
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declare -i NC_PID=$!
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sleep 1
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declare -ir TIMEOUT=20
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declare -ir EXPECTED_BPS=5000000
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# run the load, capture RX bytes on DST
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declare -ir RX_BYTES_START=$( ip netns exec ${NS_DST} \
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cat /sys/class/net/veth_dst/statistics/rx_bytes )
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set +e
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ip netns exec ${NS_SRC} bash -c "timeout ${TIMEOUT} dd if=/dev/zero \
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bs=1000 count=1000000 > /dev/tcp/${IP_DST}/9000 2>/dev/null"
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set -e
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declare -ir RX_BYTES_END=$( ip netns exec ${NS_DST} \
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cat /sys/class/net/veth_dst/statistics/rx_bytes )
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declare -ir ACTUAL_BPS=$(( ($RX_BYTES_END - $RX_BYTES_START) / $TIMEOUT ))
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echo $TIMEOUT $ACTUAL_BPS $EXPECTED_BPS | \
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awk '{printf "elapsed: %d sec; bps difference: %.2f%%\n",
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$1, ($2-$3)*100.0/$3}'
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# Pass the test if the actual bps is within 1% of the expected bps.
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# The difference is usually about 0.1% on a 20-sec test, and ==> zero
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# the longer the test runs.
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declare -ir RES=$( echo $ACTUAL_BPS $EXPECTED_BPS | \
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awk 'function abs(x){return ((x < 0.0) ? -x : x)}
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{if (abs(($1-$2)*100.0/$2) > 1.0) { print "1" }
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else { print "0"} }' )
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if [ "${RES}" == "0" ] ; then
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echo "PASS"
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else
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echo "FAIL"
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exit 1
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fi
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