Commit ec935188 authored by Jakub Kicinski's avatar Jakub Kicinski
Browse files

Merge branch 'tunnels-fix-ipv4-pmtu-icmp-checksum' 

Florian Westphal says:

====================
tunnels: fix ipv4 pmtu icmp checksum

The checksum of the generated ipv4 icmp pmtud message is
only correct if the skb that causes the icmp error generation
is linear.

Fix this and add a selftest for this.
====================

Link: https://lore.kernel.org/r/20230803152653.29535-1-fw@strlen.de


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parents 8a989617 136a1b43

net/ipv4/ip_tunnel_core.c

+1 −1
Original line number Diff line number Diff line
@@ -224,7 +224,7 @@ static int iptunnel_pmtud_build_icmp(struct sk_buff *skb, int mtu) 
		.un.frag.__unused	= 0,

		.un.frag.mtu		= htons(mtu),

	};

	icmph->checksum = ip_compute_csum(icmph, len);

	icmph->checksum = csum_fold(skb_checksum(skb, 0, len, 0));

	skb_reset_transport_header(skb);



	niph = skb_push(skb, sizeof(*niph));

tools/testing/selftests/net/pmtu.sh

+35 −0
Original line number Diff line number Diff line
@@ -361,6 +361,7 @@ err_buf= 
tcpdump_pids=

nettest_pids=

socat_pids=

tmpoutfile=



err() {

	err_buf="${err_buf}${1}
@@ -951,6 +952,7 @@ cleanup() { 
	ip link del veth_A-R1			2>/dev/null

	ovs-vsctl --if-exists del-port vxlan_a	2>/dev/null

	ovs-vsctl --if-exists del-br ovs_br0	2>/dev/null

	rm -f "$tmpoutfile"

}



mtu() {
@@ -1328,6 +1330,39 @@ test_pmtu_ipvX_over_bridged_vxlanY_or_geneveY_exception() { 
	check_pmtu_value ${exp_mtu} "${pmtu}" "exceeding link layer MTU on bridged ${type} interface"

	pmtu="$(route_get_dst_pmtu_from_exception "${ns_a}" ${dst})"

	check_pmtu_value ${exp_mtu} "${pmtu}" "exceeding link layer MTU on locally bridged ${type} interface"



	tmpoutfile=$(mktemp)



	# Flush Exceptions, retry with TCP

	run_cmd ${ns_a} ip route flush cached ${dst}

	run_cmd ${ns_b} ip route flush cached ${dst}

	run_cmd ${ns_c} ip route flush cached ${dst}



	for target in "${ns_a}" "${ns_c}" ; do

		if [ ${family} -eq 4 ]; then

			TCPDST=TCP:${dst}:50000

		else

			TCPDST="TCP:[${dst}]:50000"

		fi

		${ns_b} socat -T 3 -u -6 TCP-LISTEN:50000 STDOUT > $tmpoutfile &



		sleep 1



		dd if=/dev/zero of=/dev/stdout status=none bs=1M count=1 | ${target} socat -T 3 -u STDIN $TCPDST,connect-timeout=3



		size=$(du -sb $tmpoutfile)

		size=${size%%/tmp/*}



		[ $size -ne 1048576 ] && err "File size $size mismatches exepcted value in locally bridged vxlan test" && return 1

	done



	rm -f "$tmpoutfile"



	# Check that exceptions were created

	pmtu="$(route_get_dst_pmtu_from_exception "${ns_c}" ${dst})"

	check_pmtu_value ${exp_mtu} "${pmtu}" "tcp: exceeding link layer MTU on bridged ${type} interface"

	pmtu="$(route_get_dst_pmtu_from_exception "${ns_a}" ${dst})"

	check_pmtu_value ${exp_mtu} "${pmtu}" "tcp exceeding link layer MTU on locally bridged ${type} interface"

}



test_pmtu_ipv4_br_vxlan4_exception() {