mirrors/linux
2
0
Fork 0
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git synced 2026-05-16 04:21:09 -04:00
Code Issues Packages Projects Releases Wiki Activity

selftests: seg6: add test for dst_cache isolation in seg6 lwtunnel

Browse Source 
Add a selftest that verifies the dst_cache in seg6 lwtunnel is not
shared between the input (forwarding) and output (locally generated)
paths.

The test creates three namespaces (ns_src, ns_router, ns_dst)
connected in a line. An SRv6 encap route on ns_router encapsulates
traffic destined to cafe::1 with SID fc00::100. The SID is
reachable only for forwarded traffic (from ns_src) via an ip rule
matching the ingress interface (iif veth-r0 lookup 100), and
blackholed in the main table.

The test verifies that:

  1. A packet generated locally on ns_router does not reach
     ns_dst with an empty cache, since the SID is blackholed;
  2. A forwarded packet from ns_src populates the input cache
     from table 100 and reaches ns_dst;
  3. A packet generated locally on ns_router still does not
     reach ns_dst after the input cache is populated,
     confirming the output path does not reuse the input
     cache entry.

Both the forwarded and local packets are pinned to the same CPU
with taskset, since dst_cache is per-cpu.

Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrea Mayer <andrea.mayer@uniroma2.it>
Reviewed-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Reviewed-by: Justin Iurman <justin.iurman@gmail.com>
Link: https://patch.msgid.link/20260404004405.4057-3-andrea.mayer@uniroma2.it
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Andrea Mayer
2026-04-04 02:44:05 +02:00
committed by Jakub Kicinski
parent c3812651b5
commit 32dfd742f0
2 changed files with 198 additions and 0 deletions
Download Patch File Download Diff File Expand all files Collapse all files

1
tools/testing/selftests/net/Makefile
View File

@@ -89,6 +89,7 @@ TEST_PROGS := \
srv6_end_x_next_csid_l3vpn_test.sh \
srv6_hencap_red_l3vpn_test.sh \
srv6_hl2encap_red_l2vpn_test.sh \
srv6_iptunnel_cache.sh \
stress_reuseport_listen.sh \
tcp_fastopen_backup_key.sh \
test_bpf.sh \

197
tools/testing/selftests/net/srv6_iptunnel_cache.sh Executable file
View File

@@ -0,0 +1,197 @@
#!/bin/bash
# SPDX-License-Identifier: GPL-2.0
#
# author: Andrea Mayer <andrea.mayer@uniroma2.it>
# This test verifies that the seg6 lwtunnel does not share the dst_cache
# between the input (forwarding) and output (locally generated) paths.
#
# A shared dst_cache allows a forwarded packet to populate the cache and a
# subsequent locally generated packet to silently reuse that entry, bypassing
# its own route lookup. To expose this, the SID is made reachable only for
# forwarded traffic (via an ip rule matching iif) and blackholed for everything
# else. A local ping on ns_router must always hit the blackhole;
# if it succeeds after a forwarded packet has populated the
# cache, the bug is confirmed.
#
# Both forwarded and local packets are pinned to the same CPU with taskset,
# since dst_cache is per-cpu.
#
#
# +--------------------+ +--------------------+
# | ns_src | | ns_dst |
# | | | |
# | veth-s0 | | veth-d0 |
# | fd00::1/64 | | fd01::2/64 |
# +-------+------------+ +----------+---------+
# | |
# | +--------------------+ |
# | | ns_router | |
# | | | |
# +------------+ veth-r0 veth-r1 +--------------+
# | fd00::2 fd01::1 |
# +--------------------+
#
#
# ns_router: encap (main table)
# +---------+---------------------------------------+
# | dst | action |
# +---------+---------------------------------------+
# | cafe::1 | encap seg6 mode encap segs fc00::100 |
# +---------+---------------------------------------+
#
# ns_router: post-encap SID resolution
# +-------+------------+----------------------------+
# | table | dst | action |
# +-------+------------+----------------------------+
# | 100 | fc00::100 | via fd01::2 dev veth-r1 |
# +-------+------------+----------------------------+
# | main | fc00::100 | blackhole |
# +-------+------------+----------------------------+
#
# ns_router: ip rule
# +------------------+------------------------------+
# | match | action |
# +------------------+------------------------------+
# | iif veth-r0 | lookup 100 |
# +------------------+------------------------------+
#
# ns_dst: SRv6 decap (main table)
# +--------------+----------------------------------+
# | SID | action |
# +--------------+----------------------------------+
# | fc00::100 | End.DT6 table 255 (local) |
# +--------------+----------------------------------+
source lib.sh
readonly SID="fc00::100"
readonly DEST="cafe::1"
readonly SRC_MAC="02:00:00:00:00:01"
readonly RTR_R0_MAC="02:00:00:00:00:02"
readonly RTR_R1_MAC="02:00:00:00:00:03"
readonly DST_MAC="02:00:00:00:00:04"
cleanup()
{
cleanup_ns "${NS_SRC}" "${NS_RTR}" "${NS_DST}"
}
check_prerequisites()
{
if ! command -v ip &>/dev/null; then
echo "SKIP: ip tool not found"
exit "${ksft_skip}"
fi
if ! command -v ping &>/dev/null; then
echo "SKIP: ping not found"
exit "${ksft_skip}"
fi
if ! command -v sysctl &>/dev/null; then
echo "SKIP: sysctl not found"
exit "${ksft_skip}"
fi
if ! command -v taskset &>/dev/null; then
echo "SKIP: taskset not found"
exit "${ksft_skip}"
fi
}
setup()
{
setup_ns NS_SRC NS_RTR NS_DST
ip link add veth-s0 netns "${NS_SRC}" type veth \
peer name veth-r0 netns "${NS_RTR}"
ip link add veth-r1 netns "${NS_RTR}" type veth \
peer name veth-d0 netns "${NS_DST}"
ip -n "${NS_SRC}" link set veth-s0 address "${SRC_MAC}"
ip -n "${NS_RTR}" link set veth-r0 address "${RTR_R0_MAC}"
ip -n "${NS_RTR}" link set veth-r1 address "${RTR_R1_MAC}"
ip -n "${NS_DST}" link set veth-d0 address "${DST_MAC}"
# ns_src
ip -n "${NS_SRC}" link set veth-s0 up
ip -n "${NS_SRC}" addr add fd00::1/64 dev veth-s0 nodad
ip -n "${NS_SRC}" -6 route add "${DEST}"/128 via fd00::2
# ns_router
ip -n "${NS_RTR}" link set veth-r0 up
ip -n "${NS_RTR}" addr add fd00::2/64 dev veth-r0 nodad
ip -n "${NS_RTR}" link set veth-r1 up
ip -n "${NS_RTR}" addr add fd01::1/64 dev veth-r1 nodad
ip netns exec "${NS_RTR}" sysctl -qw net.ipv6.conf.all.forwarding=1
ip -n "${NS_RTR}" -6 route add "${DEST}"/128 \
encap seg6 mode encap segs "${SID}" dev veth-r0
ip -n "${NS_RTR}" -6 route add "${SID}"/128 table 100 \
via fd01::2 dev veth-r1
ip -n "${NS_RTR}" -6 route add blackhole "${SID}"/128
ip -n "${NS_RTR}" -6 rule add iif veth-r0 lookup 100
# ns_dst
ip -n "${NS_DST}" link set veth-d0 up
ip -n "${NS_DST}" addr add fd01::2/64 dev veth-d0 nodad
ip -n "${NS_DST}" addr add "${DEST}"/128 dev lo nodad
ip -n "${NS_DST}" -6 route add "${SID}"/128 \
encap seg6local action End.DT6 table 255 dev veth-d0
ip -n "${NS_DST}" -6 route add fd00::/64 via fd01::1
# static neighbors
ip -n "${NS_SRC}" -6 neigh add fd00::2 dev veth-s0 \
lladdr "${RTR_R0_MAC}" nud permanent
ip -n "${NS_RTR}" -6 neigh add fd00::1 dev veth-r0 \
lladdr "${SRC_MAC}" nud permanent
ip -n "${NS_RTR}" -6 neigh add fd01::2 dev veth-r1 \
lladdr "${DST_MAC}" nud permanent
ip -n "${NS_DST}" -6 neigh add fd01::1 dev veth-d0 \
lladdr "${RTR_R1_MAC}" nud permanent
}
test_cache_isolation()
{
RET=0
# local ping with empty cache: must fail (SID is blackholed)
if ip netns exec "${NS_RTR}" taskset -c 0 \
ping -c 1 -W 2 "${DEST}" &>/dev/null; then
echo "SKIP: local ping succeeded, topology broken"
exit "${ksft_skip}"
fi
# forward from ns_src to populate the input cache
if ! ip netns exec "${NS_SRC}" taskset -c 0 \
ping -c 1 -W 2 "${DEST}" &>/dev/null; then
echo "SKIP: forwarded ping failed, topology broken"
exit "${ksft_skip}"
fi
# local ping again: must still fail; if the output path reuses
# the input cache, it bypasses the blackhole and the ping succeeds
if ip netns exec "${NS_RTR}" taskset -c 0 \
ping -c 1 -W 2 "${DEST}" &>/dev/null; then
echo "FAIL: output path used dst cached by input path"
RET="${ksft_fail}"
else
echo "PASS: output path dst_cache is independent"
fi
return "${RET}"
}
if [ "$(id -u)" -ne 0 ]; then
echo "SKIP: Need root privileges"
exit "${ksft_skip}"
fi
trap cleanup EXIT
check_prerequisites
setup
test_cache_isolation
exit "${RET}"