UPSTREAM: net: WireGuard secure network tunnel

WireGuard is a layer 3 secure networking tunnel made specifically for
the kernel, that aims to be much simpler and easier to audit than IPsec.
Extensive documentation and description of the protocol and
considerations, along with formal proofs of the cryptography, are
available at:

  * https://www.wireguard.com/
  * https://www.wireguard.com/papers/wireguard.pdf

This commit implements WireGuard as a simple network device driver,
accessible in the usual RTNL way used by virtual network drivers. It
makes use of the udp_tunnel APIs, GRO, GSO, NAPI, and the usual set of
networking subsystem APIs. It has a somewhat novel multicore queueing
system designed for maximum throughput and minimal latency of encryption
operations, but it is implemented modestly using workqueues and NAPI.
Configuration is done via generic Netlink, and following a review from
the Netlink maintainer a year ago, several high profile userspace tools
have already implemented the API.

This commit also comes with several different tests, both in-kernel
tests and out-of-kernel tests based on network namespaces, taking profit
of the fact that sockets used by WireGuard intentionally stay in the
namespace the WireGuard interface was originally created, exactly like
the semantics of userspace tun devices. See wireguard.com/netns/ for
pictures and examples.

The source code is fairly short, but rather than combining everything
into a single file, WireGuard is developed as cleanly separable files,
making auditing and comprehension easier. Things are laid out as
follows:

  * noise.[ch], cookie.[ch], messages.h: These implement the bulk of the
    cryptographic aspects of the protocol, and are mostly data-only in
    nature, taking in buffers of bytes and spitting out buffers of
    bytes. They also handle reference counting for their various shared
    pieces of data, like keys and key lists.

  * ratelimiter.[ch]: Used as an integral part of cookie.[ch] for
    ratelimiting certain types of cryptographic operations in accordance
    with particular WireGuard semantics.

  * allowedips.[ch], peerlookup.[ch]: The main lookup structures of
    WireGuard, the former being trie-like with particular semantics, an
    integral part of the design of the protocol, and the latter just
    being nice helper functions around the various hashtables we use.

  * device.[ch]: Implementation of functions for the netdevice and for
    rtnl, responsible for maintaining the life of a given interface and
    wiring it up to the rest of WireGuard.

  * peer.[ch]: Each interface has a list of peers, with helper functions
    available here for creation, destruction, and reference counting.

  * socket.[ch]: Implementation of functions related to udp_socket and
    the general set of kernel socket APIs, for sending and receiving
    ciphertext UDP packets, and taking care of WireGuard-specific sticky
    socket routing semantics for the automatic roaming.

  * netlink.[ch]: Userspace API entry point for configuring WireGuard
    peers and devices. The API has been implemented by several userspace
    tools and network management utility, and the WireGuard project
    distributes the basic wg(8) tool.

  * queueing.[ch]: Shared function on the rx and tx path for handling
    the various queues used in the multicore algorithms.

  * send.c: Handles encrypting outgoing packets in parallel on
    multiple cores, before sending them in order on a single core, via
    workqueues and ring buffers. Also handles sending handshake and cookie
    messages as part of the protocol, in parallel.

  * receive.c: Handles decrypting incoming packets in parallel on
    multiple cores, before passing them off in order to be ingested via
    the rest of the networking subsystem with GRO via the typical NAPI
    poll function. Also handles receiving handshake and cookie messages
    as part of the protocol, in parallel.

  * timers.[ch]: Uses the timer wheel to implement protocol particular
    event timeouts, and gives a set of very simple event-driven entry
    point functions for callers.

  * main.c, version.h: Initialization and deinitialization of the module.

  * selftest/*.h: Runtime unit tests for some of the most security
    sensitive functions.

  * tools/testing/selftests/wireguard/netns.sh: Aforementioned testing
    script using network namespaces.

This commit aims to be as self-contained as possible, implementing
WireGuard as a standalone module not needing much special handling or
coordination from the network subsystem. I expect for future
optimizations to the network stack to positively improve WireGuard, and
vice-versa, but for the time being, this exists as intentionally
standalone.

We introduce a menu option for CONFIG_WIREGUARD, as well as providing a
verbose debug log and self-tests via CONFIG_WIREGUARD_DEBUG.

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Cc: David Miller <davem@davemloft.net>
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: linux-crypto@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: netdev@vger.kernel.org
Signed-off-by: David S. Miller <davem@davemloft.net>
[Jason: ported to 4.19 by doing the following:
 - wg_get_device_start uses genl_family_attrbuf
 - skb_probe_transport_header has an extra argument
 - NLA_EXACT/MIN_LEN is not there yet
 - nla policy is per verb not family
 - totalram_pages isn't a function]
 - __kernel_timespec -> __uapi_kernel_timespec]
(cherry picked from commit e7096c131e5161fa3b8e52a650d7719d2857adfd)
Bug: 152722841
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
Change-Id: I04cd661a4cfec9b9fa64c3ab0ea39e4e2352fa13

1 files changed, 537 insertions, 0 deletions

diff --git a/tools/testing/selftests/wireguard/netns.sh b/tools/testing/selftests/wireguard/netns.sh
new file mode 100755
index 000000000000..e7310d9390f7
--- /dev/null
+++ b/tools/testing/selftests/wireguard/netns.sh
@@ -0,0 +1,537 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+#
+# Copyright (C) 2015-2019 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
+#
+# This script tests the below topology:
+#
+# ┌─────────────────────┐   ┌──────────────────────────────────┐   ┌─────────────────────┐
+# │   $ns1 namespace    │   │          $ns0 namespace          │   │   $ns2 namespace    │
+# │                     │   │                                  │   │                     │
+# │┌────────┐           │   │            ┌────────┐            │   │           ┌────────┐│
+# ││  wg0   │───────────┼───┼────────────│   lo   │────────────┼───┼───────────│  wg0   ││
+# │├────────┴──────────┐│   │    ┌───────┴────────┴────────┐   │   │┌──────────┴────────┤│
+# ││192.168.241.1/24   ││   │    │(ns1)         (ns2)      │   │   ││192.168.241.2/24   ││
+# ││fd00::1/24         ││   │    │127.0.0.1:1   127.0.0.1:2│   │   ││fd00::2/24         ││
+# │└───────────────────┘│   │    │[::]:1        [::]:2     │   │   │└───────────────────┘│
+# └─────────────────────┘   │    └─────────────────────────┘   │   └─────────────────────┘
+#                           └──────────────────────────────────┘
+#
+# After the topology is prepared we run a series of TCP/UDP iperf3 tests between the
+# wireguard peers in $ns1 and $ns2. Note that $ns0 is the endpoint for the wg0
+# interfaces in $ns1 and $ns2. See https://www.wireguard.com/netns/ for further
+# details on how this is accomplished.
+set -e
+
+exec 3>&1
+export WG_HIDE_KEYS=never
+netns0="wg-test-$$-0"
+netns1="wg-test-$$-1"
+netns2="wg-test-$$-2"
+pretty() { echo -e "\x1b[32m\x1b[1m[+] ${1:+NS$1: }${2}\x1b[0m" >&3; }
+pp() { pretty "" "$*"; "$@"; }
+maybe_exec() { if [[ $BASHPID -eq $$ ]]; then "$@"; else exec "$@"; fi; }
+n0() { pretty 0 "$*"; maybe_exec ip netns exec $netns0 "$@"; }
+n1() { pretty 1 "$*"; maybe_exec ip netns exec $netns1 "$@"; }
+n2() { pretty 2 "$*"; maybe_exec ip netns exec $netns2 "$@"; }
+ip0() { pretty 0 "ip $*"; ip -n $netns0 "$@"; }
+ip1() { pretty 1 "ip $*"; ip -n $netns1 "$@"; }
+ip2() { pretty 2 "ip $*"; ip -n $netns2 "$@"; }
+sleep() { read -t "$1" -N 0 || true; }
+waitiperf() { pretty "${1//*-}" "wait for iperf:5201"; while [[ $(ss -N "$1" -tlp 'sport = 5201') != *iperf3* ]]; do sleep 0.1; done; }
+waitncatudp() { pretty "${1//*-}" "wait for udp:1111"; while [[ $(ss -N "$1" -ulp 'sport = 1111') != *ncat* ]]; do sleep 0.1; done; }
+waitncattcp() { pretty "${1//*-}" "wait for tcp:1111"; while [[ $(ss -N "$1" -tlp 'sport = 1111') != *ncat* ]]; do sleep 0.1; done; }
+waitiface() { pretty "${1//*-}" "wait for $2 to come up"; ip netns exec "$1" bash -c "while [[ \$(< \"/sys/class/net/$2/operstate\") != up ]]; do read -t .1 -N 0 || true; done;"; }
+
+cleanup() {
+	set +e
+	exec 2>/dev/null
+	printf "$orig_message_cost" > /proc/sys/net/core/message_cost
+	ip0 link del dev wg0
+	ip1 link del dev wg0
+	ip2 link del dev wg0
+	local to_kill="$(ip netns pids $netns0) $(ip netns pids $netns1) $(ip netns pids $netns2)"
+	[[ -n $to_kill ]] && kill $to_kill
+	pp ip netns del $netns1
+	pp ip netns del $netns2
+	pp ip netns del $netns0
+	exit
+}
+
+orig_message_cost="$(< /proc/sys/net/core/message_cost)"
+trap cleanup EXIT
+printf 0 > /proc/sys/net/core/message_cost
+
+ip netns del $netns0 2>/dev/null || true
+ip netns del $netns1 2>/dev/null || true
+ip netns del $netns2 2>/dev/null || true
+pp ip netns add $netns0
+pp ip netns add $netns1
+pp ip netns add $netns2
+ip0 link set up dev lo
+
+ip0 link add dev wg0 type wireguard
+ip0 link set wg0 netns $netns1
+ip0 link add dev wg0 type wireguard
+ip0 link set wg0 netns $netns2
+key1="$(pp wg genkey)"
+key2="$(pp wg genkey)"
+key3="$(pp wg genkey)"
+pub1="$(pp wg pubkey <<<"$key1")"
+pub2="$(pp wg pubkey <<<"$key2")"
+pub3="$(pp wg pubkey <<<"$key3")"
+psk="$(pp wg genpsk)"
+[[ -n $key1 && -n $key2 && -n $psk ]]
+
+configure_peers() {
+	ip1 addr add 192.168.241.1/24 dev wg0
+	ip1 addr add fd00::1/24 dev wg0
+
+	ip2 addr add 192.168.241.2/24 dev wg0
+	ip2 addr add fd00::2/24 dev wg0
+
+	n1 wg set wg0 \
+		private-key <(echo "$key1") \
+		listen-port 1 \
+		peer "$pub2" \
+			preshared-key <(echo "$psk") \
+			allowed-ips 192.168.241.2/32,fd00::2/128
+	n2 wg set wg0 \
+		private-key <(echo "$key2") \
+		listen-port 2 \
+		peer "$pub1" \
+			preshared-key <(echo "$psk") \
+			allowed-ips 192.168.241.1/32,fd00::1/128
+
+	ip1 link set up dev wg0
+	ip2 link set up dev wg0
+}
+configure_peers
+
+tests() {
+	# Ping over IPv4
+	n2 ping -c 10 -f -W 1 192.168.241.1
+	n1 ping -c 10 -f -W 1 192.168.241.2
+
+	# Ping over IPv6
+	n2 ping6 -c 10 -f -W 1 fd00::1
+	n1 ping6 -c 10 -f -W 1 fd00::2
+
+	# TCP over IPv4
+	n2 iperf3 -s -1 -B 192.168.241.2 &
+	waitiperf $netns2
+	n1 iperf3 -Z -t 3 -c 192.168.241.2
+
+	# TCP over IPv6
+	n1 iperf3 -s -1 -B fd00::1 &
+	waitiperf $netns1
+	n2 iperf3 -Z -t 3 -c fd00::1
+
+	# UDP over IPv4
+	n1 iperf3 -s -1 -B 192.168.241.1 &
+	waitiperf $netns1
+	n2 iperf3 -Z -t 3 -b 0 -u -c 192.168.241.1
+
+	# UDP over IPv6
+	n2 iperf3 -s -1 -B fd00::2 &
+	waitiperf $netns2
+	n1 iperf3 -Z -t 3 -b 0 -u -c fd00::2
+}
+
+[[ $(ip1 link show dev wg0) =~ mtu\ ([0-9]+) ]] && orig_mtu="${BASH_REMATCH[1]}"
+big_mtu=$(( 34816 - 1500 + $orig_mtu ))
+
+# Test using IPv4 as outer transport
+n1 wg set wg0 peer "$pub2" endpoint 127.0.0.1:2
+n2 wg set wg0 peer "$pub1" endpoint 127.0.0.1:1
+# Before calling tests, we first make sure that the stats counters and timestamper are working
+n2 ping -c 10 -f -W 1 192.168.241.1
+{ read _; read _; read _; read rx_bytes _; read _; read tx_bytes _; } < <(ip2 -stats link show dev wg0)
+(( rx_bytes == 1372 && (tx_bytes == 1428 || tx_bytes == 1460) ))
+{ read _; read _; read _; read rx_bytes _; read _; read tx_bytes _; } < <(ip1 -stats link show dev wg0)
+(( tx_bytes == 1372 && (rx_bytes == 1428 || rx_bytes == 1460) ))
+read _ rx_bytes tx_bytes < <(n2 wg show wg0 transfer)
+(( rx_bytes == 1372 && (tx_bytes == 1428 || tx_bytes == 1460) ))
+read _ rx_bytes tx_bytes < <(n1 wg show wg0 transfer)
+(( tx_bytes == 1372 && (rx_bytes == 1428 || rx_bytes == 1460) ))
+read _ timestamp < <(n1 wg show wg0 latest-handshakes)
+(( timestamp != 0 ))
+
+tests
+ip1 link set wg0 mtu $big_mtu
+ip2 link set wg0 mtu $big_mtu
+tests
+
+ip1 link set wg0 mtu $orig_mtu
+ip2 link set wg0 mtu $orig_mtu
+
+# Test using IPv6 as outer transport
+n1 wg set wg0 peer "$pub2" endpoint [::1]:2
+n2 wg set wg0 peer "$pub1" endpoint [::1]:1
+tests
+ip1 link set wg0 mtu $big_mtu
+ip2 link set wg0 mtu $big_mtu
+tests
+
+# Test that route MTUs work with the padding
+ip1 link set wg0 mtu 1300
+ip2 link set wg0 mtu 1300
+n1 wg set wg0 peer "$pub2" endpoint 127.0.0.1:2
+n2 wg set wg0 peer "$pub1" endpoint 127.0.0.1:1
+n0 iptables -A INPUT -m length --length 1360 -j DROP
+n1 ip route add 192.168.241.2/32 dev wg0 mtu 1299
+n2 ip route add 192.168.241.1/32 dev wg0 mtu 1299
+n2 ping -c 1 -W 1 -s 1269 192.168.241.1
+n2 ip route delete 192.168.241.1/32 dev wg0 mtu 1299
+n1 ip route delete 192.168.241.2/32 dev wg0 mtu 1299
+n0 iptables -F INPUT
+
+ip1 link set wg0 mtu $orig_mtu
+ip2 link set wg0 mtu $orig_mtu
+
+# Test using IPv4 that roaming works
+ip0 -4 addr del 127.0.0.1/8 dev lo
+ip0 -4 addr add 127.212.121.99/8 dev lo
+n1 wg set wg0 listen-port 9999
+n1 wg set wg0 peer "$pub2" endpoint 127.0.0.1:2
+n1 ping6 -W 1 -c 1 fd00::2
+[[ $(n2 wg show wg0 endpoints) == "$pub1	127.212.121.99:9999" ]]
+
+# Test using IPv6 that roaming works
+n1 wg set wg0 listen-port 9998
+n1 wg set wg0 peer "$pub2" endpoint [::1]:2
+n1 ping -W 1 -c 1 192.168.241.2
+[[ $(n2 wg show wg0 endpoints) == "$pub1	[::1]:9998" ]]
+
+# Test that crypto-RP filter works
+n1 wg set wg0 peer "$pub2" allowed-ips 192.168.241.0/24
+exec 4< <(n1 ncat -l -u -p 1111)
+ncat_pid=$!
+waitncatudp $netns1
+n2 ncat -u 192.168.241.1 1111 <<<"X"
+read -r -N 1 -t 1 out <&4 && [[ $out == "X" ]]
+kill $ncat_pid
+more_specific_key="$(pp wg genkey | pp wg pubkey)"
+n1 wg set wg0 peer "$more_specific_key" allowed-ips 192.168.241.2/32
+n2 wg set wg0 listen-port 9997
+exec 4< <(n1 ncat -l -u -p 1111)
+ncat_pid=$!
+waitncatudp $netns1
+n2 ncat -u 192.168.241.1 1111 <<<"X"
+! read -r -N 1 -t 1 out <&4 || false
+kill $ncat_pid
+n1 wg set wg0 peer "$more_specific_key" remove
+[[ $(n1 wg show wg0 endpoints) == "$pub2	[::1]:9997" ]]
+
+# Test that we can change private keys keys and immediately handshake
+n1 wg set wg0 private-key <(echo "$key1") peer "$pub2" preshared-key <(echo "$psk") allowed-ips 192.168.241.2/32 endpoint 127.0.0.1:2
+n2 wg set wg0 private-key <(echo "$key2") listen-port 2 peer "$pub1" preshared-key <(echo "$psk") allowed-ips 192.168.241.1/32
+n1 ping -W 1 -c 1 192.168.241.2
+n1 wg set wg0 private-key <(echo "$key3")
+n2 wg set wg0 peer "$pub3" preshared-key <(echo "$psk") allowed-ips 192.168.241.1/32 peer "$pub1" remove
+n1 ping -W 1 -c 1 192.168.241.2
+
+ip1 link del wg0
+ip2 link del wg0
+
+# Test using NAT. We now change the topology to this:
+# ┌────────────────────────────────────────┐    ┌────────────────────────────────────────────────┐     ┌────────────────────────────────────────┐
+# │             $ns1 namespace             │    │                 $ns0 namespace                 │     │             $ns2 namespace             │
+# │                                        │    │                                                │     │                                        │
+# │  ┌─────┐             ┌─────┐           │    │    ┌──────┐              ┌──────┐              │     │  ┌─────┐            ┌─────┐            │
+# │  │ wg0 │─────────────│vethc│───────────┼────┼────│vethrc│              │vethrs│──────────────┼─────┼──│veths│────────────│ wg0 │            │
+# │  ├─────┴──────────┐  ├─────┴──────────┐│    │    ├──────┴─────────┐    ├──────┴────────────┐ │     │  ├─────┴──────────┐ ├─────┴──────────┐ │
+# │  │192.168.241.1/24│  │192.168.1.100/24││    │    │192.168.1.1/24  │    │10.0.0.1/24        │ │     │  │10.0.0.100/24   │ │192.168.241.2/24│ │
+# │  │fd00::1/24      │  │                ││    │    │                │    │SNAT:192.168.1.0/24│ │     │  │                │ │fd00::2/24      │ │
+# │  └────────────────┘  └────────────────┘│    │    └────────────────┘    └───────────────────┘ │     │  └────────────────┘ └────────────────┘ │
+# └────────────────────────────────────────┘    └────────────────────────────────────────────────┘     └────────────────────────────────────────┘
+
+ip1 link add dev wg0 type wireguard
+ip2 link add dev wg0 type wireguard
+configure_peers
+
+ip0 link add vethrc type veth peer name vethc
+ip0 link add vethrs type veth peer name veths
+ip0 link set vethc netns $netns1
+ip0 link set veths netns $netns2
+ip0 link set vethrc up
+ip0 link set vethrs up
+ip0 addr add 192.168.1.1/24 dev vethrc
+ip0 addr add 10.0.0.1/24 dev vethrs
+ip1 addr add 192.168.1.100/24 dev vethc
+ip1 link set vethc up
+ip1 route add default via 192.168.1.1
+ip2 addr add 10.0.0.100/24 dev veths
+ip2 link set veths up
+waitiface $netns0 vethrc
+waitiface $netns0 vethrs
+waitiface $netns1 vethc
+waitiface $netns2 veths
+
+n0 bash -c 'printf 1 > /proc/sys/net/ipv4/ip_forward'
+n0 bash -c 'printf 2 > /proc/sys/net/netfilter/nf_conntrack_udp_timeout'
+n0 bash -c 'printf 2 > /proc/sys/net/netfilter/nf_conntrack_udp_timeout_stream'
+n0 iptables -t nat -A POSTROUTING -s 192.168.1.0/24 -d 10.0.0.0/24 -j SNAT --to 10.0.0.1
+
+n1 wg set wg0 peer "$pub2" endpoint 10.0.0.100:2 persistent-keepalive 1
+n1 ping -W 1 -c 1 192.168.241.2
+n2 ping -W 1 -c 1 192.168.241.1
+[[ $(n2 wg show wg0 endpoints) == "$pub1	10.0.0.1:1" ]]
+# Demonstrate n2 can still send packets to n1, since persistent-keepalive will prevent connection tracking entry from expiring (to see entries: `n0 conntrack -L`).
+pp sleep 3
+n2 ping -W 1 -c 1 192.168.241.1
+n1 wg set wg0 peer "$pub2" persistent-keepalive 0
+
+# Do a wg-quick(8)-style policy routing for the default route, making sure vethc has a v6 address to tease out bugs.
+ip1 -6 addr add fc00::9/96 dev vethc
+ip1 -6 route add default via fc00::1
+ip2 -4 addr add 192.168.99.7/32 dev wg0
+ip2 -6 addr add abab::1111/128 dev wg0
+n1 wg set wg0 fwmark 51820 peer "$pub2" allowed-ips 192.168.99.7,abab::1111
+ip1 -6 route add default dev wg0 table 51820
+ip1 -6 rule add not fwmark 51820 table 51820
+ip1 -6 rule add table main suppress_prefixlength 0
+ip1 -4 route add default dev wg0 table 51820
+ip1 -4 rule add not fwmark 51820 table 51820
+ip1 -4 rule add table main suppress_prefixlength 0
+# suppress_prefixlength only got added in 3.12, and we want to support 3.10+.
+if [[ $(ip1 -4 rule show all) == *suppress_prefixlength* ]]; then
+	# Flood the pings instead of sending just one, to trigger routing table reference counting bugs.
+	n1 ping -W 1 -c 100 -f 192.168.99.7
+	n1 ping -W 1 -c 100 -f abab::1111
+fi
+
+n0 iptables -t nat -F
+ip0 link del vethrc
+ip0 link del vethrs
+ip1 link del wg0
+ip2 link del wg0
+
+# Test that saddr routing is sticky but not too sticky, changing to this topology:
+# ┌────────────────────────────────────────┐    ┌────────────────────────────────────────┐
+# │             $ns1 namespace             │    │             $ns2 namespace             │
+# │                                        │    │                                        │
+# │  ┌─────┐             ┌─────┐           │    │  ┌─────┐            ┌─────┐            │
+# │  │ wg0 │─────────────│veth1│───────────┼────┼──│veth2│────────────│ wg0 │            │
+# │  ├─────┴──────────┐  ├─────┴──────────┐│    │  ├─────┴──────────┐ ├─────┴──────────┐ │
+# │  │192.168.241.1/24│  │10.0.0.1/24     ││    │  │10.0.0.2/24     │ │192.168.241.2/24│ │
+# │  │fd00::1/24      │  │fd00:aa::1/96   ││    │  │fd00:aa::2/96   │ │fd00::2/24      │ │
+# │  └────────────────┘  └────────────────┘│    │  └────────────────┘ └────────────────┘ │
+# └────────────────────────────────────────┘    └────────────────────────────────────────┘
+
+ip1 link add dev wg0 type wireguard
+ip2 link add dev wg0 type wireguard
+configure_peers
+ip1 link add veth1 type veth peer name veth2
+ip1 link set veth2 netns $netns2
+n1 bash -c 'printf 0 > /proc/sys/net/ipv6/conf/all/accept_dad'
+n2 bash -c 'printf 0 > /proc/sys/net/ipv6/conf/all/accept_dad'
+n1 bash -c 'printf 0 > /proc/sys/net/ipv6/conf/veth1/accept_dad'
+n2 bash -c 'printf 0 > /proc/sys/net/ipv6/conf/veth2/accept_dad'
+n1 bash -c 'printf 1 > /proc/sys/net/ipv4/conf/veth1/promote_secondaries'
+
+# First we check that we aren't overly sticky and can fall over to new IPs when old ones are removed
+ip1 addr add 10.0.0.1/24 dev veth1
+ip1 addr add fd00:aa::1/96 dev veth1
+ip2 addr add 10.0.0.2/24 dev veth2
+ip2 addr add fd00:aa::2/96 dev veth2
+ip1 link set veth1 up
+ip2 link set veth2 up
+waitiface $netns1 veth1
+waitiface $netns2 veth2
+n1 wg set wg0 peer "$pub2" endpoint 10.0.0.2:2
+n1 ping -W 1 -c 1 192.168.241.2
+ip1 addr add 10.0.0.10/24 dev veth1
+ip1 addr del 10.0.0.1/24 dev veth1
+n1 ping -W 1 -c 1 192.168.241.2
+n1 wg set wg0 peer "$pub2" endpoint [fd00:aa::2]:2
+n1 ping -W 1 -c 1 192.168.241.2
+ip1 addr add fd00:aa::10/96 dev veth1
+ip1 addr del fd00:aa::1/96 dev veth1
+n1 ping -W 1 -c 1 192.168.241.2
+
+# Now we show that we can successfully do reply to sender routing
+ip1 link set veth1 down
+ip2 link set veth2 down
+ip1 addr flush dev veth1
+ip2 addr flush dev veth2
+ip1 addr add 10.0.0.1/24 dev veth1
+ip1 addr add 10.0.0.2/24 dev veth1
+ip1 addr add fd00:aa::1/96 dev veth1
+ip1 addr add fd00:aa::2/96 dev veth1
+ip2 addr add 10.0.0.3/24 dev veth2
+ip2 addr add fd00:aa::3/96 dev veth2
+ip1 link set veth1 up
+ip2 link set veth2 up
+waitiface $netns1 veth1
+waitiface $netns2 veth2
+n2 wg set wg0 peer "$pub1" endpoint 10.0.0.1:1
+n2 ping -W 1 -c 1 192.168.241.1
+[[ $(n2 wg show wg0 endpoints) == "$pub1	10.0.0.1:1" ]]
+n2 wg set wg0 peer "$pub1" endpoint [fd00:aa::1]:1
+n2 ping -W 1 -c 1 192.168.241.1
+[[ $(n2 wg show wg0 endpoints) == "$pub1	[fd00:aa::1]:1" ]]
+n2 wg set wg0 peer "$pub1" endpoint 10.0.0.2:1
+n2 ping -W 1 -c 1 192.168.241.1
+[[ $(n2 wg show wg0 endpoints) == "$pub1	10.0.0.2:1" ]]
+n2 wg set wg0 peer "$pub1" endpoint [fd00:aa::2]:1
+n2 ping -W 1 -c 1 192.168.241.1
+[[ $(n2 wg show wg0 endpoints) == "$pub1	[fd00:aa::2]:1" ]]
+
+# What happens if the inbound destination address belongs to a different interface as the default route?
+ip1 link add dummy0 type dummy
+ip1 addr add 10.50.0.1/24 dev dummy0
+ip1 link set dummy0 up
+ip2 route add 10.50.0.0/24 dev veth2
+n2 wg set wg0 peer "$pub1" endpoint 10.50.0.1:1
+n2 ping -W 1 -c 1 192.168.241.1
+[[ $(n2 wg show wg0 endpoints) == "$pub1	10.50.0.1:1" ]]
+
+ip1 link del dummy0
+ip1 addr flush dev veth1
+ip2 addr flush dev veth2
+ip1 route flush dev veth1
+ip2 route flush dev veth2
+
+# Now we see what happens if another interface route takes precedence over an ongoing one
+ip1 link add veth3 type veth peer name veth4
+ip1 link set veth4 netns $netns2
+ip1 addr add 10.0.0.1/24 dev veth1
+ip2 addr add 10.0.0.2/24 dev veth2
+ip1 addr add 10.0.0.3/24 dev veth3
+ip1 link set veth1 up
+ip2 link set veth2 up
+ip1 link set veth3 up
+ip2 link set veth4 up
+waitiface $netns1 veth1
+waitiface $netns2 veth2
+waitiface $netns1 veth3
+waitiface $netns2 veth4
+ip1 route flush dev veth1
+ip1 route flush dev veth3
+ip1 route add 10.0.0.0/24 dev veth1 src 10.0.0.1 metric 2
+n1 wg set wg0 peer "$pub2" endpoint 10.0.0.2:2
+n1 ping -W 1 -c 1 192.168.241.2
+[[ $(n2 wg show wg0 endpoints) == "$pub1	10.0.0.1:1" ]]
+ip1 route add 10.0.0.0/24 dev veth3 src 10.0.0.3 metric 1
+n1 bash -c 'printf 0 > /proc/sys/net/ipv4/conf/veth1/rp_filter'
+n2 bash -c 'printf 0 > /proc/sys/net/ipv4/conf/veth4/rp_filter'
+n1 bash -c 'printf 0 > /proc/sys/net/ipv4/conf/all/rp_filter'
+n2 bash -c 'printf 0 > /proc/sys/net/ipv4/conf/all/rp_filter'
+n1 ping -W 1 -c 1 192.168.241.2
+[[ $(n2 wg show wg0 endpoints) == "$pub1	10.0.0.3:1" ]]
+
+ip1 link del veth1
+ip1 link del veth3
+ip1 link del wg0
+ip2 link del wg0
+
+# We test that Netlink/IPC is working properly by doing things that usually cause split responses
+ip0 link add dev wg0 type wireguard
+config=( "[Interface]" "PrivateKey=$(wg genkey)" "[Peer]" "PublicKey=$(wg genkey)" )
+for a in {1..255}; do
+	for b in {0..255}; do
+		config+=( "AllowedIPs=$a.$b.0.0/16,$a::$b/128" )
+	done
+done
+n0 wg setconf wg0 <(printf '%s\n' "${config[@]}")
+i=0
+for ip in $(n0 wg show wg0 allowed-ips); do
+	((++i))
+done
+((i == 255*256*2+1))
+ip0 link del wg0
+ip0 link add dev wg0 type wireguard
+config=( "[Interface]" "PrivateKey=$(wg genkey)" )
+for a in {1..40}; do
+	config+=( "[Peer]" "PublicKey=$(wg genkey)" )
+	for b in {1..52}; do
+		config+=( "AllowedIPs=$a.$b.0.0/16" )
+	done
+done
+n0 wg setconf wg0 <(printf '%s\n' "${config[@]}")
+i=0
+while read -r line; do
+	j=0
+	for ip in $line; do
+		((++j))
+	done
+	((j == 53))
+	((++i))
+done < <(n0 wg show wg0 allowed-ips)
+((i == 40))
+ip0 link del wg0
+ip0 link add wg0 type wireguard
+config=( )
+for i in {1..29}; do
+	config+=( "[Peer]" "PublicKey=$(wg genkey)" )
+done
+config+=( "[Peer]" "PublicKey=$(wg genkey)" "AllowedIPs=255.2.3.4/32,abcd::255/128" )
+n0 wg setconf wg0 <(printf '%s\n' "${config[@]}")
+n0 wg showconf wg0 > /dev/null
+ip0 link del wg0
+
+allowedips=( )
+for i in {1..197}; do
+        allowedips+=( abcd::$i )
+done
+saved_ifs="$IFS"
+IFS=,
+allowedips="${allowedips[*]}"
+IFS="$saved_ifs"
+ip0 link add wg0 type wireguard
+n0 wg set wg0 peer "$pub1"
+n0 wg set wg0 peer "$pub2" allowed-ips "$allowedips"
+{
+	read -r pub allowedips
+	[[ $pub == "$pub1" && $allowedips == "(none)" ]]
+	read -r pub allowedips
+	[[ $pub == "$pub2" ]]
+	i=0
+	for _ in $allowedips; do
+		((++i))
+	done
+	((i == 197))
+} < <(n0 wg show wg0 allowed-ips)
+ip0 link del wg0
+
+! n0 wg show doesnotexist || false
+
+ip0 link add wg0 type wireguard
+n0 wg set wg0 private-key <(echo "$key1") peer "$pub2" preshared-key <(echo "$psk")
+[[ $(n0 wg show wg0 private-key) == "$key1" ]]
+[[ $(n0 wg show wg0 preshared-keys) == "$pub2	$psk" ]]
+n0 wg set wg0 private-key /dev/null peer "$pub2" preshared-key /dev/null
+[[ $(n0 wg show wg0 private-key) == "(none)" ]]
+[[ $(n0 wg show wg0 preshared-keys) == "$pub2	(none)" ]]
+n0 wg set wg0 peer "$pub2"
+n0 wg set wg0 private-key <(echo "$key2")
+[[ $(n0 wg show wg0 public-key) == "$pub2" ]]
+[[ -z $(n0 wg show wg0 peers) ]]
+n0 wg set wg0 peer "$pub2"
+[[ -z $(n0 wg show wg0 peers) ]]
+n0 wg set wg0 private-key <(echo "$key1")
+n0 wg set wg0 peer "$pub2"
+[[ $(n0 wg show wg0 peers) == "$pub2" ]]
+n0 wg set wg0 private-key <(echo "/${key1:1}")
+[[ $(n0 wg show wg0 private-key) == "+${key1:1}" ]]
+n0 wg set wg0 peer "$pub2" allowed-ips 0.0.0.0/0,10.0.0.0/8,100.0.0.0/10,172.16.0.0/12,192.168.0.0/16
+n0 wg set wg0 peer "$pub2" allowed-ips 0.0.0.0/0
+n0 wg set wg0 peer "$pub2" allowed-ips ::/0,1700::/111,5000::/4,e000::/37,9000::/75
+n0 wg set wg0 peer "$pub2" allowed-ips ::/0
+ip0 link del wg0
+
+declare -A objects
+while read -t 0.1 -r line 2>/dev/null || [[ $? -ne 142 ]]; do
+	[[ $line =~ .*(wg[0-9]+:\ [A-Z][a-z]+\ [0-9]+)\ .*(created|destroyed).* ]] || continue
+	objects["${BASH_REMATCH[1]}"]+="${BASH_REMATCH[2]}"
+done < /dev/kmsg
+alldeleted=1
+for object in "${!objects[@]}"; do
+	if [[ ${objects["$object"]} != *createddestroyed ]]; then
+		echo "Error: $object: merely ${objects["$object"]}" >&3
+		alldeleted=0
+	fi
+done
+[[ $alldeleted -eq 1 ]]
+pretty "" "Objects that were created were also destroyed."