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 <yoel@kviknet.dk>
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 195 insertions, 0 deletions

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