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: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Jakub Kicinski 2023-08-04 18:24:53 -07:00
commit ec93518839
2 changed files with 36 additions and 1 deletions

View file

@ -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));

View file

@ -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() {