Commit 41307417 authored by David S. Miller's avatar David S. Miller
Browse files

Merge branch 'net-fix-regressions-for-generic-XDP' 

Jesper Dangaard Brouer says:

====================
net: fix regressions for generic-XDP

Thanks to Brandon Cazander, who wrote a very detailed bug report that
even used perf probe's on xdp-newbies mailing list, we discovered that
generic-XDP contains some regressions when using bpf_xdp_adjust_head().

First issue were that my selftests script, that use bpf_xdp_adjust_head(),
by mistake didn't use generic-XDP any-longer. That selftest should have
caught the real regression introduced in commit 458bf2f2 ("net: core:
support XDP generic on stacked devices.").

To verify this patchset fix the regressions, you can invoked manually via:

  cd tools/testing/selftests/bpf/
  sudo ./test_xdp_vlan_mode_generic.sh
  sudo ./test_xdp_vlan_mode_native.sh
====================

Link: https://www.spinics.net/lists/xdp-newbies/msg01231.html


Fixes: 458bf2f2 ("net: core: support XDP generic on stacked devices.")
Reported by: Brandon Cazander <brandon.cazander@multapplied.net>
Signed-off-by: default avatarJesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parents 60d60c8f 065af355

net/core/dev.c

+10 −5
Original line number Diff line number Diff line
@@ -4374,12 +4374,17 @@ static u32 netif_receive_generic_xdp(struct sk_buff *skb, 


	act = bpf_prog_run_xdp(xdp_prog, xdp);



	/* check if bpf_xdp_adjust_head was used */

	off = xdp->data - orig_data;

	if (off) {

		if (off > 0)

			__skb_pull(skb, off);

		else if (off < 0)

			__skb_push(skb, -off);



		skb->mac_header += off;

		skb_reset_network_header(skb);

	}



	/* check if bpf_xdp_adjust_tail was used. it can only "shrink"

	 * pckt.

tools/testing/selftests/bpf/Makefile

+2 −1
Original line number Diff line number Diff line
@@ -57,7 +57,8 @@ TEST_PROGS := test_kmod.sh \ 
	test_lirc_mode2.sh \

	test_skb_cgroup_id.sh \

	test_flow_dissector.sh \

	test_xdp_vlan.sh \

	test_xdp_vlan_mode_generic.sh \

	test_xdp_vlan_mode_native.sh \

	test_lwt_ip_encap.sh \

	test_tcp_check_syncookie.sh \

	test_tc_tunnel.sh \

tools/testing/selftests/bpf/test_xdp_vlan.sh

+45 −12
Original line number Diff line number Diff line 
#!/bin/bash

# SPDX-License-Identifier: GPL-2.0

# Author: Jesper Dangaard Brouer <hawk@kernel.org>



# Allow wrapper scripts to name test

if [ -z "$TESTNAME" ]; then

    TESTNAME=xdp_vlan

fi



# Default XDP mode

XDP_MODE=xdpgeneric



usage() {

  echo "Testing XDP + TC eBPF VLAN manipulations: $TESTNAME"
@@ -9,9 +17,23 @@ usage() { 
  echo "  -v | --verbose : Verbose"

  echo "  --flush        : Flush before starting (e.g. after --interactive)"

  echo "  --interactive  : Keep netns setup running after test-run"

  echo "  --mode=XXX     : Choose XDP mode (xdp | xdpgeneric | xdpdrv)"

  echo ""

}



valid_xdp_mode()

{

	local mode=$1



	case "$mode" in

		xdpgeneric | xdpdrv | xdp)

			return 0

			;;

		*)

			return 1

	esac

}



cleanup()

{

	local status=$?
@@ -37,7 +59,7 @@ cleanup() 


# Using external program "getopt" to get --long-options

OPTIONS=$(getopt -o hvfi: \

    --long verbose,flush,help,interactive,debug -- "$@")

    --long verbose,flush,help,interactive,debug,mode: -- "$@")

if (( $? != 0 )); then

    usage

    echo "selftests: $TESTNAME [FAILED] Error calling getopt, unknown option?"
@@ -60,6 +82,11 @@ while true; do 
		cleanup

		shift

		;;

	    --mode )

		shift

		XDP_MODE=$1

		shift

		;;

	    -- )

		shift

		break
@@ -81,7 +108,13 @@ if [ "$EUID" -ne 0 ]; then 
	exit 1

fi



ip link set dev lo xdp off 2>/dev/null > /dev/null

valid_xdp_mode $XDP_MODE

if [ $? -ne 0 ]; then

	echo "selftests: $TESTNAME [FAILED] unknown XDP mode ($XDP_MODE)"

	exit 1

fi



ip link set dev lo xdpgeneric off 2>/dev/null > /dev/null

if [ $? -ne 0 ]; then

	echo "selftests: $TESTNAME [SKIP] need ip xdp support"

	exit 0
@@ -155,7 +188,7 @@ 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"'

ip netns exec ns2 sh -c 'ping -W 1 -c 1 100.64.41.1 || echo "Success: First ping must fail"'





# Now we can use the test_xdp_vlan.c program to pop/push these VLAN tags
@@ -166,7 +199,7 @@ 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

ip netns exec ns1 ip link set $DEVNS1 $XDP_MODE object $FILE section $XDP_PROG



# In ns1: egress use TC to add back VLAN tag 4011

#  (del cmd)
@@ -177,8 +210,8 @@ 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

ip netns exec ns2 ping -i 0.2 -W 2 -c 2 $IPADDR1

ip netns exec ns1 ping -i 0.2 -W 2 -c 2 $IPADDR2



# Second test: Replace xdp prog, that fully remove vlan header

#
@@ -187,9 +220,9 @@ ip netns exec ns1 ping -W 2 -c 3 $IPADDR2 
# 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

ip netns exec ns1 ip link set $DEVNS1 $XDP_MODE off

ip netns exec ns1 ip link set $DEVNS1 $XDP_MODE 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
 
ip netns exec ns2 ping -i 0.2 -W 2 -c 2 $IPADDR1

ip netns exec ns1 ping -i 0.2 -W 2 -c 2 $IPADDR2

tools/testing/selftests/bpf/test_xdp_vlan_mode_generic.sh

0 → 100755
+9 −0
Original line number Diff line number Diff line 
#!/bin/bash

# SPDX-License-Identifier: GPL-2.0



# Exit on failure

set -e



# Wrapper script to test generic-XDP

export TESTNAME=xdp_vlan_mode_generic

./test_xdp_vlan.sh --mode=xdpgeneric

tools/testing/selftests/bpf/test_xdp_vlan_mode_native.sh

0 → 100755
+9 −0
Original line number Diff line number Diff line 
#!/bin/bash

# SPDX-License-Identifier: GPL-2.0



# Exit on failure

set -e



# Wrapper script to test native-XDP

export TESTNAME=xdp_vlan_mode_native

./test_xdp_vlan.sh --mode=xdpdrv

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