From 97396ff0bc2d31f8fcb29cbb57d2e0bbcb96d6c5 Mon Sep 17 00:00:00 2001 From: Jesper Dangaard Brouer Date: Tue, 9 Oct 2018 12:04:53 +0200 Subject: [PATCH] selftests/bpf: add XDP selftests for modifying and popping VLAN headers This XDP selftest also contain a small TC-bpf component. It provoke the generic-XDP bug fixed in previous commit. The selftest itself shows how to do VLAN manipulation from XDP and TC. The test demonstrate how XDP ingress can remove a VLAN tag, and how TC egress can add back a VLAN tag. This use-case originates from a production need by ISP (kviknet.dk), who gets DSL-lines terminated as VLAN Q-in-Q tagged packets, and want to avoid having an net_device for every end-customer on the box doing the L2 to L3 termination. The test-setup is done via a veth-pair and creating two network namespaces (ns1 and ns2). The 'ns1' simulate the ISP network that are loading the BPF-progs stripping and adding VLAN IDs. The 'ns2' simulate the DSL-customer that are using VLAN tagged packets. Running the script with --interactive, will simply not call the cleanup function. This gives the effect of creating a testlab, that the users can inspect and play with. The --verbose option will simply request that the shell will print input lines as they are read, this include comments, which in effect make the comments visible docs. Reported-by: Yoel Caspersen Signed-off-by: Jesper Dangaard Brouer Signed-off-by: Alexei Starovoitov --- tools/testing/selftests/bpf/Makefile | 6 +- tools/testing/selftests/bpf/test_xdp_vlan.c | 292 +++++++++++++++++++ tools/testing/selftests/bpf/test_xdp_vlan.sh | 195 +++++++++++++ 3 files changed, 491 insertions(+), 2 deletions(-) create mode 100644 tools/testing/selftests/bpf/test_xdp_vlan.c create mode 100755 tools/testing/selftests/bpf/test_xdp_vlan.sh diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile index 1381ab81099c..d24afe8b821d 100644 --- a/tools/testing/selftests/bpf/Makefile +++ b/tools/testing/selftests/bpf/Makefile @@ -36,7 +36,8 @@ TEST_GEN_FILES = test_pkt_access.o test_xdp.o test_l4lb.o test_tcp_estats.o test test_get_stack_rawtp.o test_sockmap_kern.o test_sockhash_kern.o \ test_lwt_seg6local.o sendmsg4_prog.o sendmsg6_prog.o test_lirc_mode2_kern.o \ get_cgroup_id_kern.o socket_cookie_prog.o test_select_reuseport_kern.o \ - test_skb_cgroup_id_kern.o bpf_flow.o netcnt_prog.o test_sk_lookup_kern.o + test_skb_cgroup_id_kern.o bpf_flow.o netcnt_prog.o \ + test_sk_lookup_kern.o test_xdp_vlan.o # Order correspond to 'make run_tests' order TEST_PROGS := test_kmod.sh \ @@ -49,7 +50,8 @@ TEST_PROGS := test_kmod.sh \ test_lwt_seg6local.sh \ test_lirc_mode2.sh \ test_skb_cgroup_id.sh \ - test_flow_dissector.sh + test_flow_dissector.sh \ + test_xdp_vlan.sh # Compile but not part of 'make run_tests' TEST_GEN_PROGS_EXTENDED = test_libbpf_open test_sock_addr test_skb_cgroup_id_user \ diff --git a/tools/testing/selftests/bpf/test_xdp_vlan.c b/tools/testing/selftests/bpf/test_xdp_vlan.c new file mode 100644 index 000000000000..365a7d2d9f5c --- /dev/null +++ b/tools/testing/selftests/bpf/test_xdp_vlan.c @@ -0,0 +1,292 @@ +/* SPDX-License-Identifier: GPL-2.0 + * Copyright(c) 2018 Jesper Dangaard Brouer. + * + * XDP/TC VLAN manipulation example + * + * GOTCHA: Remember to disable NIC hardware offloading of VLANs, + * else the VLAN tags are NOT inlined in the packet payload: + * + * # ethtool -K ixgbe2 rxvlan off + * + * Verify setting: + * # ethtool -k ixgbe2 | grep rx-vlan-offload + * rx-vlan-offload: off + * + */ +#include +#include +#include +#include +#include +#include +#include +#include + +#include "bpf_helpers.h" +#include "bpf_endian.h" + +/* linux/if_vlan.h have not exposed this as UAPI, thus mirror some here + * + * struct vlan_hdr - vlan header + * @h_vlan_TCI: priority and VLAN ID + * @h_vlan_encapsulated_proto: packet type ID or len + */ +struct _vlan_hdr { + __be16 h_vlan_TCI; + __be16 h_vlan_encapsulated_proto; +}; +#define VLAN_PRIO_MASK 0xe000 /* Priority Code Point */ +#define VLAN_PRIO_SHIFT 13 +#define VLAN_CFI_MASK 0x1000 /* Canonical Format Indicator */ +#define VLAN_TAG_PRESENT VLAN_CFI_MASK +#define VLAN_VID_MASK 0x0fff /* VLAN Identifier */ +#define VLAN_N_VID 4096 + +struct parse_pkt { + __u16 l3_proto; + __u16 l3_offset; + __u16 vlan_outer; + __u16 vlan_inner; + __u8 vlan_outer_offset; + __u8 vlan_inner_offset; +}; + +char _license[] SEC("license") = "GPL"; + +static __always_inline +bool parse_eth_frame(struct ethhdr *eth, void *data_end, struct parse_pkt *pkt) +{ + __u16 eth_type; + __u8 offset; + + offset = sizeof(*eth); + /* Make sure packet is large enough for parsing eth + 2 VLAN headers */ + if ((void *)eth + offset + (2*sizeof(struct _vlan_hdr)) > data_end) + return false; + + eth_type = eth->h_proto; + + /* Handle outer VLAN tag */ + if (eth_type == bpf_htons(ETH_P_8021Q) + || eth_type == bpf_htons(ETH_P_8021AD)) { + struct _vlan_hdr *vlan_hdr; + + vlan_hdr = (void *)eth + offset; + pkt->vlan_outer_offset = offset; + pkt->vlan_outer = bpf_ntohs(vlan_hdr->h_vlan_TCI) + & VLAN_VID_MASK; + eth_type = vlan_hdr->h_vlan_encapsulated_proto; + offset += sizeof(*vlan_hdr); + } + + /* Handle inner (double) VLAN tag */ + if (eth_type == bpf_htons(ETH_P_8021Q) + || eth_type == bpf_htons(ETH_P_8021AD)) { + struct _vlan_hdr *vlan_hdr; + + vlan_hdr = (void *)eth + offset; + pkt->vlan_inner_offset = offset; + pkt->vlan_inner = bpf_ntohs(vlan_hdr->h_vlan_TCI) + & VLAN_VID_MASK; + eth_type = vlan_hdr->h_vlan_encapsulated_proto; + offset += sizeof(*vlan_hdr); + } + + pkt->l3_proto = bpf_ntohs(eth_type); /* Convert to host-byte-order */ + pkt->l3_offset = offset; + + return true; +} + +/* Hint, VLANs are choosen to hit network-byte-order issues */ +#define TESTVLAN 4011 /* 0xFAB */ +// #define TO_VLAN 4000 /* 0xFA0 (hint 0xOA0 = 160) */ + +SEC("xdp_drop_vlan_4011") +int xdp_prognum0(struct xdp_md *ctx) +{ + void *data_end = (void *)(long)ctx->data_end; + void *data = (void *)(long)ctx->data; + struct parse_pkt pkt = { 0 }; + + if (!parse_eth_frame(data, data_end, &pkt)) + return XDP_ABORTED; + + /* Drop specific VLAN ID example */ + if (pkt.vlan_outer == TESTVLAN) + return XDP_ABORTED; + /* + * Using XDP_ABORTED makes it possible to record this event, + * via tracepoint xdp:xdp_exception like: + * # perf record -a -e xdp:xdp_exception + * # perf script + */ + return XDP_PASS; +} +/* +Commands to setup VLAN on Linux to test packets gets dropped: + + export ROOTDEV=ixgbe2 + export VLANID=4011 + ip link add link $ROOTDEV name $ROOTDEV.$VLANID type vlan id $VLANID + ip link set dev $ROOTDEV.$VLANID up + + ip link set dev $ROOTDEV mtu 1508 + ip addr add 100.64.40.11/24 dev $ROOTDEV.$VLANID + +Load prog with ip tool: + + ip link set $ROOTDEV xdp off + ip link set $ROOTDEV xdp object xdp_vlan01_kern.o section xdp_drop_vlan_4011 + +*/ + +/* Changing VLAN to zero, have same practical effect as removing the VLAN. */ +#define TO_VLAN 0 + +SEC("xdp_vlan_change") +int xdp_prognum1(struct xdp_md *ctx) +{ + void *data_end = (void *)(long)ctx->data_end; + void *data = (void *)(long)ctx->data; + struct parse_pkt pkt = { 0 }; + + if (!parse_eth_frame(data, data_end, &pkt)) + return XDP_ABORTED; + + /* Change specific VLAN ID */ + if (pkt.vlan_outer == TESTVLAN) { + struct _vlan_hdr *vlan_hdr = data + pkt.vlan_outer_offset; + + /* Modifying VLAN, preserve top 4 bits */ + vlan_hdr->h_vlan_TCI = + bpf_htons((bpf_ntohs(vlan_hdr->h_vlan_TCI) & 0xf000) + | TO_VLAN); + } + + return XDP_PASS; +} + +/* + * Show XDP+TC can cooperate, on creating a VLAN rewriter. + * 1. Create a XDP prog that can "pop"/remove a VLAN header. + * 2. Create a TC-bpf prog that egress can add a VLAN header. + */ + +#ifndef ETH_ALEN /* Ethernet MAC address length */ +#define ETH_ALEN 6 /* bytes */ +#endif +#define VLAN_HDR_SZ 4 /* bytes */ + +SEC("xdp_vlan_remove_outer") +int xdp_prognum2(struct xdp_md *ctx) +{ + void *data_end = (void *)(long)ctx->data_end; + void *data = (void *)(long)ctx->data; + struct parse_pkt pkt = { 0 }; + char *dest; + + if (!parse_eth_frame(data, data_end, &pkt)) + return XDP_ABORTED; + + /* Skip packet if no outer VLAN was detected */ + if (pkt.vlan_outer_offset == 0) + return XDP_PASS; + + /* Moving Ethernet header, dest overlap with src, memmove handle this */ + dest = data; + dest+= VLAN_HDR_SZ; + /* + * Notice: Taking over vlan_hdr->h_vlan_encapsulated_proto, by + * only moving two MAC addrs (12 bytes), not overwriting last 2 bytes + */ + __builtin_memmove(dest, data, ETH_ALEN * 2); + /* Note: LLVM built-in memmove inlining require size to be constant */ + + /* Move start of packet header seen by Linux kernel stack */ + bpf_xdp_adjust_head(ctx, VLAN_HDR_SZ); + + return XDP_PASS; +} + +static __always_inline +void shift_mac_4bytes_16bit(void *data) +{ + __u16 *p = data; + + p[7] = p[5]; /* delete p[7] was vlan_hdr->h_vlan_TCI */ + p[6] = p[4]; /* delete p[6] was ethhdr->h_proto */ + p[5] = p[3]; + p[4] = p[2]; + p[3] = p[1]; + p[2] = p[0]; +} + +static __always_inline +void shift_mac_4bytes_32bit(void *data) +{ + __u32 *p = data; + + /* Assuming VLAN hdr present. The 4 bytes in p[3] that gets + * overwritten, is ethhdr->h_proto and vlan_hdr->h_vlan_TCI. + * The vlan_hdr->h_vlan_encapsulated_proto take over role as + * ethhdr->h_proto. + */ + p[3] = p[2]; + p[2] = p[1]; + p[1] = p[0]; +} + +SEC("xdp_vlan_remove_outer2") +int xdp_prognum3(struct xdp_md *ctx) +{ + void *data_end = (void *)(long)ctx->data_end; + void *data = (void *)(long)ctx->data; + struct ethhdr *orig_eth = data; + struct parse_pkt pkt = { 0 }; + + if (!parse_eth_frame(orig_eth, data_end, &pkt)) + return XDP_ABORTED; + + /* Skip packet if no outer VLAN was detected */ + if (pkt.vlan_outer_offset == 0) + return XDP_PASS; + + /* Simply shift down MAC addrs 4 bytes, overwrite h_proto + TCI */ + shift_mac_4bytes_32bit(data); + + /* Move start of packet header seen by Linux kernel stack */ + bpf_xdp_adjust_head(ctx, VLAN_HDR_SZ); + + return XDP_PASS; +} + +/*===================================== + * BELOW: TC-hook based ebpf programs + * ==================================== + * The TC-clsact eBPF programs (currently) need to be attach via TC commands + */ + +SEC("tc_vlan_push") +int _tc_progA(struct __sk_buff *ctx) +{ + bpf_skb_vlan_push(ctx, bpf_htons(ETH_P_8021Q), TESTVLAN); + + return TC_ACT_OK; +} +/* +Commands to setup TC to use above bpf prog: + +export ROOTDEV=ixgbe2 +export FILE=xdp_vlan01_kern.o + +# Re-attach clsact to clear/flush existing role +tc qdisc del dev $ROOTDEV clsact 2> /dev/null ;\ +tc qdisc add dev $ROOTDEV clsact + +# Attach BPF prog EGRESS +tc filter add dev $ROOTDEV egress \ + prio 1 handle 1 bpf da obj $FILE sec tc_vlan_push + +tc filter show dev $ROOTDEV egress +*/ diff --git a/tools/testing/selftests/bpf/test_xdp_vlan.sh b/tools/testing/selftests/bpf/test_xdp_vlan.sh new file mode 100755 index 000000000000..51a3a31d1aac --- /dev/null +++ b/tools/testing/selftests/bpf/test_xdp_vlan.sh @@ -0,0 +1,195 @@ +#!/bin/bash + +TESTNAME=xdp_vlan + +usage() { + echo "Testing XDP + TC eBPF VLAN manipulations: $TESTNAME" + echo "" + echo "Usage: $0 [-vfh]" + echo " -v | --verbose : Verbose" + echo " --flush : Flush before starting (e.g. after --interactive)" + echo " --interactive : Keep netns setup running after test-run" + echo "" +} + +cleanup() +{ + local status=$? + + if [ "$status" = "0" ]; then + echo "selftests: $TESTNAME [PASS]"; + else + echo "selftests: $TESTNAME [FAILED]"; + fi + + if [ -n "$INTERACTIVE" ]; then + echo "Namespace setup still active explore with:" + echo " ip netns exec ns1 bash" + echo " ip netns exec ns2 bash" + exit $status + fi + + set +e + ip link del veth1 2> /dev/null + ip netns del ns1 2> /dev/null + ip netns del ns2 2> /dev/null +} + +# Using external program "getopt" to get --long-options +OPTIONS=$(getopt -o hvfi: \ + --long verbose,flush,help,interactive,debug -- "$@") +if (( $? != 0 )); then + usage + echo "selftests: $TESTNAME [FAILED] Error calling getopt, unknown option?" + exit 2 +fi +eval set -- "$OPTIONS" + +## --- Parse command line arguments / parameters --- +while true; do + case "$1" in + -v | --verbose) + export VERBOSE=yes + shift + ;; + -i | --interactive | --debug ) + INTERACTIVE=yes + shift + ;; + -f | --flush ) + cleanup + shift + ;; + -- ) + shift + break + ;; + -h | --help ) + usage; + echo "selftests: $TESTNAME [SKIP] usage help info requested" + exit 0 + ;; + * ) + shift + break + ;; + esac +done + +if [ "$EUID" -ne 0 ]; then + echo "selftests: $TESTNAME [FAILED] need root privileges" + exit 1 +fi + +ip link set dev lo xdp off 2>/dev/null > /dev/null +if [ $? -ne 0 ];then + echo "selftests: $TESTNAME [SKIP] need ip xdp support" + exit 0 +fi + +# Interactive mode likely require us to cleanup netns +if [ -n "$INTERACTIVE" ]; then + ip link del veth1 2> /dev/null + ip netns del ns1 2> /dev/null + ip netns del ns2 2> /dev/null +fi + +# Exit on failure +set -e + +# Some shell-tools dependencies +which ip > /dev/null +which tc > /dev/null +which ethtool > /dev/null + +# Make rest of shell verbose, showing comments as doc/info +if [ -n "$VERBOSE" ]; then + set -v +fi + +# Create two namespaces +ip netns add ns1 +ip netns add ns2 + +# Run cleanup if failing or on kill +trap cleanup 0 2 3 6 9 + +# Create veth pair +ip link add veth1 type veth peer name veth2 + +# Move veth1 and veth2 into the respective namespaces +ip link set veth1 netns ns1 +ip link set veth2 netns ns2 + +# NOTICE: XDP require VLAN header inside packet payload +# - Thus, disable VLAN offloading driver features +# - For veth REMEMBER TX side VLAN-offload +# +# Disable rx-vlan-offload (mostly needed on ns1) +ip netns exec ns1 ethtool -K veth1 rxvlan off +ip netns exec ns2 ethtool -K veth2 rxvlan off +# +# Disable tx-vlan-offload (mostly needed on ns2) +ip netns exec ns2 ethtool -K veth2 txvlan off +ip netns exec ns1 ethtool -K veth1 txvlan off + +export IPADDR1=100.64.41.1 +export IPADDR2=100.64.41.2 + +# In ns1/veth1 add IP-addr on plain net_device +ip netns exec ns1 ip addr add ${IPADDR1}/24 dev veth1 +ip netns exec ns1 ip link set veth1 up + +# In ns2/veth2 create VLAN device +export VLAN=4011 +export DEVNS2=veth2 +ip netns exec ns2 ip link add link $DEVNS2 name $DEVNS2.$VLAN type vlan id $VLAN +ip netns exec ns2 ip addr add ${IPADDR2}/24 dev $DEVNS2.$VLAN +ip netns exec ns2 ip link set $DEVNS2 up +ip netns exec ns2 ip link set $DEVNS2.$VLAN up + +# Bringup lo in netns (to avoids confusing people using --interactive) +ip netns exec ns1 ip link set lo up +ip netns exec ns2 ip link set lo up + +# At this point, the hosts cannot reach each-other, +# because ns2 are using VLAN tags on the packets. + +ip netns exec ns2 sh -c 'ping -W 1 -c 1 100.64.41.1 || echo "Okay ping fails"' + + +# Now we can use the test_xdp_vlan.c program to pop/push these VLAN tags +# ---------------------------------------------------------------------- +# In ns1: ingress use XDP to remove VLAN tags +export DEVNS1=veth1 +export FILE=test_xdp_vlan.o + +# First test: Remove VLAN by setting VLAN ID 0, using "xdp_vlan_change" +export XDP_PROG=xdp_vlan_change +ip netns exec ns1 ip link set $DEVNS1 xdp object $FILE section $XDP_PROG + +# In ns1: egress use TC to add back VLAN tag 4011 +# (del cmd) +# tc qdisc del dev $DEVNS1 clsact 2> /dev/null +# +ip netns exec ns1 tc qdisc add dev $DEVNS1 clsact +ip netns exec ns1 tc filter add dev $DEVNS1 egress \ + prio 1 handle 1 bpf da obj $FILE sec tc_vlan_push + +# Now the namespaces can reach each-other, test with ping: +ip netns exec ns2 ping -W 2 -c 3 $IPADDR1 +ip netns exec ns1 ping -W 2 -c 3 $IPADDR2 + +# Second test: Replace xdp prog, that fully remove vlan header +# +# Catch kernel bug for generic-XDP, that does didn't allow us to +# remove a VLAN header, because skb->protocol still contain VLAN +# ETH_P_8021Q indication, and this cause overwriting of our changes. +# +export XDP_PROG=xdp_vlan_remove_outer2 +ip netns exec ns1 ip link set $DEVNS1 xdp off +ip netns exec ns1 ip link set $DEVNS1 xdp object $FILE section $XDP_PROG + +# Now the namespaces should still be able reach each-other, test with ping: +ip netns exec ns2 ping -W 2 -c 3 $IPADDR1 +ip netns exec ns1 ping -W 2 -c 3 $IPADDR2