Message-ID: <ad281865-47d3-cdfe-2a6f-b05b7a0ee88f@netfilter.org>
Date: Tue, 7 May 2024 14:05:19 +0200 (CEST)
From: Jozsef Kadlecsik <kadlec@...filter.org>
To: Florian Westphal <fw@...len.de>
cc: netfilter-devel@...r.kernel.org, netdev@...r.kernel.org, kuba@...nel.org, 
    ncardwell@...gle.com, edumazet@...gle.com, pablo@...filter.org
Subject: Re: [PATCH nf-next] selftests: netfilter: add packetdrill based
 conntrack tests

Hi Florian,

On Tue, 7 May 2024, Florian Westphal wrote:

> Add a new test script that uses packetdrill tool to exercise conntrack
> state machine.

This is really great!! It was missing to actually test and verify the
conntrack state machine.

Best regards,
Jozsef
 
> Needs ip/ip6tables and conntrack tool (to check if we have an entry in
> the expected state).
> 
> Test cases added here cover following scenarios:
> 1. already-acked (retransmitted) packets are not tagged as INVALID
> 2. RST packet coming when conntrack is already closing (FIN/CLOSE_WAIT)
>   transitions conntrack to CLOSE even if the RST is not an exact match
> 3. RST packets with out-of-window sequence numbers are marked as INVALID
> 4. SYN+Challenge ACK: check that challenge ack is allowed to pass
> 5. Old SYN/ACK: check conntrack handles the case where SYN is answered
>   with SYN/ACK for an old, previous connection attempt
> 6. Check SYN reception while in ESTABLISHED state generates a challenge
>    ack, RST response clears 'outdated' state + next SYN retransmit gets
>    us into 'SYN_RECV' conntrack state.
> 
> Tests get run twice, once with ipv4 and once with ipv6.
> 
> Signed-off-by: Florian Westphal <fw@...len.de>
> ---
>  .../testing/selftests/net/netfilter/Makefile  |   2 +
>  tools/testing/selftests/net/netfilter/config  |   1 +
>  .../net/netfilter/nf_conntrack_packetdrill.sh |  71 +++++++++++
>  .../net/netfilter/packetdrill/common.sh       |  33 +++++
>  .../packetdrill/conntrack_ack_loss_stall.pkt  | 118 ++++++++++++++++++
>  .../packetdrill/conntrack_inexact_rst.pkt     |  62 +++++++++
>  .../packetdrill/conntrack_rst_invalid.pkt     |  59 +++++++++
>  .../conntrack_syn_challenge_ack.pkt           |  44 +++++++
>  .../packetdrill/conntrack_synack_old.pkt      |  51 ++++++++
>  .../packetdrill/conntrack_synack_reuse.pkt    |  34 +++++
>  10 files changed, 475 insertions(+)
>  create mode 100755 tools/testing/selftests/net/netfilter/nf_conntrack_packetdrill.sh
>  create mode 100755 tools/testing/selftests/net/netfilter/packetdrill/common.sh
>  create mode 100644 tools/testing/selftests/net/netfilter/packetdrill/conntrack_ack_loss_stall.pkt
>  create mode 100644 tools/testing/selftests/net/netfilter/packetdrill/conntrack_inexact_rst.pkt
>  create mode 100644 tools/testing/selftests/net/netfilter/packetdrill/conntrack_rst_invalid.pkt
>  create mode 100644 tools/testing/selftests/net/netfilter/packetdrill/conntrack_syn_challenge_ack.pkt
>  create mode 100644 tools/testing/selftests/net/netfilter/packetdrill/conntrack_synack_old.pkt
>  create mode 100644 tools/testing/selftests/net/netfilter/packetdrill/conntrack_synack_reuse.pkt
> 
> diff --git a/tools/testing/selftests/net/netfilter/Makefile b/tools/testing/selftests/net/netfilter/Makefile
> index e9a6c702b8c9..47945b2b3f92 100644
> --- a/tools/testing/selftests/net/netfilter/Makefile
> +++ b/tools/testing/selftests/net/netfilter/Makefile
> @@ -13,6 +13,7 @@ TEST_PROGS += conntrack_tcp_unreplied.sh
>  TEST_PROGS += conntrack_sctp_collision.sh
>  TEST_PROGS += conntrack_vrf.sh
>  TEST_PROGS += ipvs.sh
> +TEST_PROGS += nf_conntrack_packetdrill.sh
>  TEST_PROGS += nf_nat_edemux.sh
>  TEST_PROGS += nft_audit.sh
>  TEST_PROGS += nft_concat_range.sh
> @@ -45,6 +46,7 @@ $(OUTPUT)/conntrack_dump_flush: CFLAGS += $(MNL_CFLAGS)
>  $(OUTPUT)/conntrack_dump_flush: LDLIBS += $(MNL_LDLIBS)
>  
>  TEST_FILES := lib.sh
> +TEST_FILES += packetdrill
>  
>  TEST_INCLUDES := \
>  	../lib.sh
> diff --git a/tools/testing/selftests/net/netfilter/config b/tools/testing/selftests/net/netfilter/config
> index 5b5b764f6cd0..63ef80ef47a4 100644
> --- a/tools/testing/selftests/net/netfilter/config
> +++ b/tools/testing/selftests/net/netfilter/config
> @@ -86,3 +86,4 @@ CONFIG_VLAN_8021Q=m
>  CONFIG_XFRM_USER=m
>  CONFIG_XFRM_STATISTICS=y
>  CONFIG_NET_PKTGEN=m
> +CONFIG_TUN=m
> diff --git a/tools/testing/selftests/net/netfilter/nf_conntrack_packetdrill.sh b/tools/testing/selftests/net/netfilter/nf_conntrack_packetdrill.sh
> new file mode 100755
> index 000000000000..c6fdd2079f4d
> --- /dev/null
> +++ b/tools/testing/selftests/net/netfilter/nf_conntrack_packetdrill.sh
> @@ -0,0 +1,71 @@
> +#!/bin/bash
> +# SPDX-License-Identifier: GPL-2.0
> +
> +source lib.sh
> +
> +checktool "conntrack --version" "run test without conntrack"
> +checktool "iptables --version" "run test without iptables"
> +checktool "ip6tables --version" "run test without ip6tables"
> +
> +modprobe -q tun
> +modprobe -q nf_conntrack
> +# echo 1 > /proc/sys/net/netfilter/nf_log_all_netns
> +
> +PDRILL_TIMEOUT=10
> +
> +files="
> +conntrack_ack_loss_stall.pkt
> +conntrack_inexact_rst.pkt
> +conntrack_syn_challenge_ack.pkt
> +conntrack_synack_old.pkt
> +conntrack_synack_reuse.pkt
> +conntrack_rst_invalid.pkt
> +"
> +
> +if ! packetdrill --dry_run --verbose "packetdrill/conntrack_ack_loss_stall.pkt";then
> +	echo "SKIP: packetdrill not installed"
> +	exit ${ksft_skip}
> +fi
> +
> +ret=0
> +
> +run_packetdrill()
> +{
> +	filename="$1"
> +	ipver="$2"
> +	local mtu=1500
> +
> +	export NFCT_IP_VERSION="$ipver"
> +
> +	if [ "$ipver" = "ipv4" ];then
> +		export xtables="iptables"
> +	elif [ "$ipver" = "ipv6" ];then
> +		export xtables="ip6tables"
> +		mtu=1520
> +	fi
> +
> +	timeout "$PDRILL_TIMEOUT" unshare -n packetdrill --ip_version="$ipver" --mtu=$mtu \
> +		--tolerance_usecs=1000000 --non_fatal packet "$filename"
> +}
> +
> +run_one_test_file()
> +{
> +	filename="$1"
> +
> +	for v in ipv4 ipv6;do
> +		printf "%-50s(%s)%-20s" "$filename" "$v" ""
> +		if run_packetdrill packetdrill/"$f" "$v";then
> +			echo OK
> +		else
> +			echo FAIL
> +			ret=1
> +		fi
> +	done
> +}
> +
> +echo "Replaying packetdrill test cases:"
> +for f in $files;do
> +	run_one_test_file packetdrill/"$f"
> +done
> +
> +exit $ret
> diff --git a/tools/testing/selftests/net/netfilter/packetdrill/common.sh b/tools/testing/selftests/net/netfilter/packetdrill/common.sh
> new file mode 100755
> index 000000000000..ed36d535196d
> --- /dev/null
> +++ b/tools/testing/selftests/net/netfilter/packetdrill/common.sh
> @@ -0,0 +1,33 @@
> +#!/bin/bash
> +# SPDX-License-Identifier: GPL-2.0
> +
> +# for debugging set net.netfilter.nf_log_all_netns=1 in init_net
> +# or do not use net namespaces.
> +modprobe -q nf_conntrack
> +sysctl -q net.netfilter.nf_conntrack_log_invalid=6
> +
> +# Flush old cached data (fastopen cookies).
> +ip tcp_metrics flush all > /dev/null 2>&1
> +
> +# TCP min, default, and max receive and send buffer sizes.
> +sysctl -q net.ipv4.tcp_rmem="4096 540000 $((15*1024*1024))"
> +sysctl -q net.ipv4.tcp_wmem="4096 $((256*1024)) 4194304"
> +
> +# TCP congestion control.
> +sysctl -q net.ipv4.tcp_congestion_control=cubic
> +
> +# TCP slow start after idle.
> +sysctl -q net.ipv4.tcp_slow_start_after_idle=0
> +
> +# TCP Explicit Congestion Notification (ECN)
> +sysctl -q net.ipv4.tcp_ecn=0
> +
> +sysctl -q net.ipv4.tcp_notsent_lowat=4294967295 > /dev/null 2>&1
> +
> +# Override the default qdisc on the tun device.
> +# Many tests fail with timing errors if the default
> +# is FQ and that paces their flows.
> +tc qdisc add dev tun0 root pfifo
> +
> +# Enable conntrack
> +$xtables -A INPUT -m conntrack --ctstate NEW -p tcp --syn
> diff --git a/tools/testing/selftests/net/netfilter/packetdrill/conntrack_ack_loss_stall.pkt b/tools/testing/selftests/net/netfilter/packetdrill/conntrack_ack_loss_stall.pkt
> new file mode 100644
> index 000000000000..d755bd64c54f
> --- /dev/null
> +++ b/tools/testing/selftests/net/netfilter/packetdrill/conntrack_ack_loss_stall.pkt
> @@ -0,0 +1,118 @@
> +// check that already-acked (retransmitted) packet is let through rather
> +// than tagged as INVALID.
> +
> +`packetdrill/common.sh`
> +
> +// should set -P DROP but it disconnects VM w.o. extra netns
> ++0 `$xtables -A INPUT -m conntrack --ctstate INVALID -j DROP`
> +
> ++0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3
> ++0 setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0
> ++0 bind(3, ..., ...) = 0
> ++0 listen(3, 10) = 0
> +
> ++0 < S 0:0(0) win 32792 <mss 1000>
> ++0 > S. 0:0(0) ack 1 <mss 1460>
> ++.01 < . 1:1(0) ack 1 win 65535
> ++0 accept(3, ..., ...) = 4
> +
> ++0.0001 < P. 1:1461(1460) ack 1 win 257
> ++.0 > . 1:1(0) ack 1461 win 65535
> ++0.0001 < P. 1461:2921(1460) ack 1 win 257
> ++.0 > . 1:1(0) ack 2921 win 65535
> ++0.0001 < P. 2921:4381(1460) ack 1 win 257
> ++.0 > . 1:1(0) ack 4381 win 65535
> ++0.0001 < P. 4381:5841(1460) ack 1 win 257
> ++.0 > . 1:1(0) ack 5841 win 65535
> ++0.0001 < P. 5841:7301(1460) ack 1 win 257
> ++.0 > . 1:1(0) ack 7301 win 65535
> ++0.0001 < P. 7301:8761(1460) ack 1 win 257
> ++.0 > . 1:1(0) ack 8761 win 65535
> ++0.0001 < P. 8761:10221(1460) ack 1 win 257
> ++.0 > . 1:1(0) ack 10221 win 65535
> ++0.0001 < P. 10221:11681(1460) ack 1 win 257
> ++.0 > . 1:1(0) ack 11681 win 65535
> ++0.0001 < P. 11681:13141(1460) ack 1 win 257
> ++.0 > . 1:1(0) ack 13141 win 65535
> ++0.0001 < P. 13141:14601(1460) ack 1 win 257
> ++.0 > . 1:1(0) ack 14601 win 65535
> ++0.0001 < P. 14601:16061(1460) ack 1 win 257
> ++.0 > . 1:1(0) ack 16061 win 65535
> ++0.0001 < P. 16061:17521(1460) ack 1 win 257
> ++.0 > . 1:1(0) ack 17521 win 65535
> ++0.0001 < P. 17521:18981(1460) ack 1 win 257
> ++.0 > . 1:1(0) ack 18981 win 65535
> ++0.0001 < P. 18981:20441(1460) ack 1 win 257
> ++.0 > . 1:1(0) ack 20441 win 65535
> ++0.0001 < P. 20441:21901(1460) ack 1 win 257
> ++.0 > . 1:1(0) ack 21901 win 65535
> ++0.0001 < P. 21901:23361(1460) ack 1 win 257
> ++.0 > . 1:1(0) ack 23361 win 65535
> ++0.0001 < P. 23361:24821(1460) ack 1 win 257
> +0.055 > . 1:1(0) ack 24821 win 65535
> ++0.0001 < P. 24821:26281(1460) ack 1 win 257
> ++.0 > . 1:1(0) ack 26281 win 65535
> ++0.0001 < P. 26281:27741(1460) ack 1 win 257
> ++.0 > . 1:1(0) ack 27741 win 65535
> ++0.0001 < P. 27741:29201(1460) ack 1 win 257
> ++.0 > . 1:1(0) ack 29201 win 65535
> ++0.0001 < P. 29201:30661(1460) ack 1 win 257
> ++.0 > . 1:1(0) ack 30661 win 65535
> ++0.0001 < P. 30661:32121(1460) ack 1 win 257
> ++.0 > . 1:1(0) ack 32121 win 65535
> ++0.0001 < P. 32121:33581(1460) ack 1 win 257
> ++.0 > . 1:1(0) ack 33581 win 65535
> ++0.0001 < P. 33581:35041(1460) ack 1 win 257
> ++.0 > . 1:1(0) ack 35041 win 65535
> ++0.0001 < P. 35041:36501(1460) ack 1 win 257
> ++.0 > . 1:1(0) ack 36501 win 65535
> ++0.0001 < P. 36501:37961(1460) ack 1 win 257
> ++.0 > . 1:1(0) ack 37961 win 65535
> ++0.0001 < P. 37961:39421(1460) ack 1 win 257
> ++.0 > . 1:1(0) ack 39421 win 65535
> ++0.0001 < P. 39421:40881(1460) ack 1 win 257
> ++.0 > . 1:1(0) ack 40881 win 65535
> ++0.0001 < P. 40881:42341(1460) ack 1 win 257
> ++.0 > . 1:1(0) ack 42341 win 65535
> ++0.0001 < P. 42341:43801(1460) ack 1 win 257
> ++.0 > . 1:1(0) ack 43801 win 65535
> ++0.0001 < P. 43801:45261(1460) ack 1 win 257
> ++.0 > . 1:1(0) ack 45261 win 65535
> ++0.0001 < P. 45261:46721(1460) ack 1 win 257
> ++.0 > . 1:1(0) ack 46721 win 65535
> ++0.0001 < P. 46721:48181(1460) ack 1 win 257
> ++.0 > . 1:1(0) ack 48181 win 65535
> ++0.0001 < P. 48181:49641(1460) ack 1 win 257
> ++.0 > . 1:1(0) ack 49641 win 65535
> ++0.0001 < P. 49641:51101(1460) ack 1 win 257
> ++.0 > . 1:1(0) ack 51101 win 65535
> ++0.0001 < P. 51101:52561(1460) ack 1 win 257
> ++.0 > . 1:1(0) ack 52561 win 65535
> ++0.0001 < P. 52561:54021(1460) ack 1 win 257
> ++.0 > . 1:1(0) ack 54021 win 65535
> ++0.0001 < P. 54021:55481(1460) ack 1 win 257
> ++.0 > . 1:1(0) ack 55481 win 65535
> ++0.0001 < P. 55481:56941(1460) ack 1 win 257
> ++.0 > . 1:1(0) ack 56941 win 65535
> ++0.0001 < P. 56941:58401(1460) ack 1 win 257
> ++.0 > . 1:1(0) ack 58401 win 65535
> ++0.0001 < P. 58401:59861(1460) ack 1 win 257
> ++.0 > . 1:1(0) ack 59861 win 65535
> ++0.0001 < P. 59861:61321(1460) ack 1 win 257
> ++.0 > . 1:1(0) ack 61321 win 65535
> ++0.0001 < P. 61321:62781(1460) ack 1 win 257
> ++.0 > . 1:1(0) ack 62781 win 65535
> ++0.0001 < P. 62781:64241(1460) ack 1 win 257
> ++.0 > . 1:1(0) ack 64241 win 65535
> ++0.0001 < P. 64241:65701(1460) ack 1 win 257
> ++.0 > . 1:1(0) ack 65701 win 65535
> ++0.0001 < P. 65701:67161(1460) ack 1 win 257
> ++.0 > . 1:1(0) ack 67161 win 65535
> +
> +// nf_ct_proto_6: SEQ is under the lower bound (already ACKed data retransmitted) IN=tun0 OUT= MAC= SRC=192.0.2.1 DST=192.168.24.72 LEN=1500 TOS=0x00 PREC=0x00 TTL=255 ID=0 PROTO=TCP SPT=34375 DPT=8080 SEQ=1 ACK=4162510439 WINDOW=257 RES=0x00 ACK PSH URGP=0
> ++0.0001 < P. 1:1461(1460) ack 1 win 257
> +
> +// only sent if above packet isn't flagged as invalid
> ++.0 > . 1:1(0) ack 67161 win 65535
> +
> ++0 `$xtables -D INPUT -m conntrack --ctstate INVALID -j DROP`
> diff --git a/tools/testing/selftests/net/netfilter/packetdrill/conntrack_inexact_rst.pkt b/tools/testing/selftests/net/netfilter/packetdrill/conntrack_inexact_rst.pkt
> new file mode 100644
> index 000000000000..dccdd4c009c6
> --- /dev/null
> +++ b/tools/testing/selftests/net/netfilter/packetdrill/conntrack_inexact_rst.pkt
> @@ -0,0 +1,62 @@
> +// check RST packet that doesn't exactly match expected next sequence
> +// number still transitions conntrack state to CLOSE iff its already in
> +// FIN/CLOSE_WAIT.
> +
> +`packetdrill/common.sh`
> +
> +//  5.771921 server_ip > client_ip TLSv1.2 337 [Packet size limited during capture]
> +//  5.771994 server_ip > client_ip TLSv1.2 337 [Packet size limited during capture]
> +//  5.772212 client_ip > server_ip TCP 66 45020 > 443 [ACK] Seq=1905874048 Ack=781810658 Win=36352 Len=0 TSval=3317842872 TSecr=675936334
> +//  5.787924 server_ip > client_ip TLSv1.2 1300 [Packet size limited during capture]
> +//  5.788126 server_ip > client_ip TLSv1.2 90 Application Data
> +//  5.788207 server_ip > client_ip TCP 66 443 > 45020 [FIN, ACK] Seq=781811916 Ack=1905874048 Win=31104 Len=0 TSval=675936350 TSecr=3317842872
> +//  5.788447 client_ip > server_ip TLSv1.2 90 Application Data
> +//  5.788479 client_ip > server_ip TCP 66 45020 > 443 [RST, ACK] Seq=1905874072 Ack=781811917 Win=39040 Len=0 TSval=3317842889 TSecr=675936350
> +//  5.788581 server_ip > client_ip TCP 54 8443 > 45020 [RST] Seq=781811892 Win=0 Len=0
> +
> ++0 `iptables -A INPUT -p tcp -m conntrack --ctstate INVALID -j DROP`
> ++0 `iptables -A OUTPUT -p tcp -m conntrack --ctstate INVALID -j DROP`
> +
> ++0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3
> ++0 fcntl(3, F_SETFL, O_RDWR|O_NONBLOCK) = 0
> +
> +0.1 connect(3, ..., ...) = -1 EINPROGRESS (Operation now in progress)
> +
> +0.1 > S 0:0(0) win 65535 <mss 1460,sackOK,TS val 1 ecr 0,nop,wscale 8>
> +
> ++0.1 < S. 1:1(0) ack 1 win 65535 <mss 1460>
> +
> ++0 > . 1:1(0) ack 1 win 65535
> ++0 < . 1:1001(1000) ack 1 win 65535
> ++0 < . 1001:2001(1000) ack 1 win 65535
> ++0 < . 2001:3001(1000) ack 1 win 65535
> +
> ++0 > . 1:1(0) ack 1001 win 65535
> ++0 > . 1:1(0) ack 2001 win 65535
> ++0 > . 1:1(0) ack 3001 win 65535
> +
> ++0 write(3, ..., 1000) = 1000
> +
> ++0.0 > P. 1:1001(1000) ack 3001 win 65535
> +
> ++0.1 read(3, ..., 1000) = 1000
> +
> +// Conntrack should move to FIN_WAIT, then CLOSE_WAIT.
> ++0 < F. 3001:3001(0) ack 1001 win 65535
> ++0 >  . 1001:1001(0) ack 3002 win 65535
> +
> ++0 `conntrack -f $NFCT_IP_VERSION -L -p tcp --dport 8080 2>/dev/null |grep -q CLOSE_WAIT`
> +
> ++1 close(3) = 0
> +// RST: unread data. FIN was seen, hence ack + 1
> ++0 > R. 1001:1001(0) ack 3002 win 65535
> +// ... and then, CLOSE.
> ++0 `conntrack -f $NFCT_IP_VERSION -L -p tcp --dport 8080 2>/dev/null |grep -q CLOSE\ `
> +
> +// Spurious RST from peer -- no sk state.  Should NOT get
> +// marked INVALID, because conntrack is already closing.
> ++0.1 < R 2001:2001(0) win 0
> +
> +// No packets should have been marked INVALID
> ++0 `iptables -v -S INPUT  | grep INVALID | grep -q -- "-c 0 0"`
> ++0 `iptables -v -S OUTPUT | grep INVALID | grep -q -- "-c 0 0"`
> diff --git a/tools/testing/selftests/net/netfilter/packetdrill/conntrack_rst_invalid.pkt b/tools/testing/selftests/net/netfilter/packetdrill/conntrack_rst_invalid.pkt
> new file mode 100644
> index 000000000000..686f18a3d9ef
> --- /dev/null
> +++ b/tools/testing/selftests/net/netfilter/packetdrill/conntrack_rst_invalid.pkt
> @@ -0,0 +1,59 @@
> +// check that out of window resets are marked as INVALID and conntrack remains
> +// in ESTABLISHED state.
> +
> +`packetdrill/common.sh`
> +
> ++0 `$xtables -A INPUT -p tcp -m conntrack --ctstate INVALID -j DROP`
> ++0 `$xtables -A OUTPUT -p tcp -m conntrack --ctstate INVALID -j DROP`
> +
> ++0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3
> ++0 fcntl(3, F_SETFL, O_RDWR|O_NONBLOCK) = 0
> +
> +0.1 connect(3, ..., ...) = -1 EINPROGRESS (Operation now in progress)
> +
> +0.1 > S 0:0(0) win 65535 <mss 1460,sackOK,TS val 1 ecr 0,nop,wscale 8>
> +
> ++0.1 < S. 1:1(0) ack 1 win 65535 <mss 1460>
> +
> ++0 > . 1:1(0) ack 1 win 65535
> ++0 < . 1:1001(1000) ack 1 win 65535
> ++0 < . 1001:2001(1000) ack 1 win 65535
> ++0 < . 2001:3001(1000) ack 1 win 65535
> +
> ++0 > . 1:1(0) ack 1001 win 65535
> ++0 > . 1:1(0) ack 2001 win 65535
> ++0 > . 1:1(0) ack 3001 win 65535
> +
> ++0 write(3, ..., 1000) = 1000
> +
> +// out of window
> ++0.0 < R	0:0(0)	win 0
> ++0 `conntrack -f $NFCT_IP_VERSION -L -p tcp --dport 8080 2>/dev/null |grep -q ESTABLISHED`
> +
> +// out of window
> ++0.0 < R	1000000:1000000(0)	win 0
> ++0 `conntrack -f $NFCT_IP_VERSION -L -p tcp --dport 8080 2>/dev/null |grep -q ESTABLISHED`
> +
> +// in-window but not exact match
> ++0.0 < R	42:42(0)	win 0
> ++0 `conntrack -f $NFCT_IP_VERSION -L -p tcp --dport 8080 2>/dev/null |grep -q ESTABLISHED`
> +
> ++0.0 > P. 1:1001(1000) ack 3001 win 65535
> +
> ++0.1 read(3, ..., 1000) = 1000
> ++0 `conntrack -f $NFCT_IP_VERSION -L -p tcp --dport 8080 2>/dev/null |grep -q ESTABLISHED`
> +
> ++0 < . 3001:3001(0) ack 1001 win 65535
> +
> ++0.0 < R. 3000:3000(0) ack 1001 win 0
> ++0 `conntrack -f $NFCT_IP_VERSION -L -p tcp --dport 8080 2>/dev/null |grep -q ESTABLISHED`
> +
> +// exact next sequence
> ++0.0 < R. 3001:3001(0) ack 1001 win 0
> +// Conntrack should move to CLOSE
> +
> +// Expect four invalid RSTs
> ++0 `$xtables -v -S INPUT  | grep INVALID | grep -q -- "-c 4 "`
> ++0 `$xtables -v -S OUTPUT | grep INVALID | grep -q -- "-c 0 0"`
> +
> ++0 `conntrack -f $NFCT_IP_VERSION -L -p tcp --dport 8080 2>/dev/null |grep -q CLOSE\ `
> diff --git a/tools/testing/selftests/net/netfilter/packetdrill/conntrack_syn_challenge_ack.pkt b/tools/testing/selftests/net/netfilter/packetdrill/conntrack_syn_challenge_ack.pkt
> new file mode 100644
> index 000000000000..3442cd29bc93
> --- /dev/null
> +++ b/tools/testing/selftests/net/netfilter/packetdrill/conntrack_syn_challenge_ack.pkt
> @@ -0,0 +1,44 @@
> +// Check connection re-use, i.e. peer that receives the SYN answers with
> +// a challenge-ACK.
> +// Check that conntrack lets all packets pass, including the challenge ack,
> +// and that a new connection is established.
> +
> +`packetdrill/common.sh`
> +
> +// S  >
> +//  . < (challnge-ack)
> +// R. >
> +// S  >
> +// S. <
> +// Expected outcome: established connection.
> +
> ++0 `$xtables -A INPUT -p tcp -m conntrack --ctstate INVALID -j DROP`
> ++0 `$xtables -A OUTPUT -p tcp -m conntrack --ctstate INVALID -j DROP`
> +
> ++0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3
> ++0 fcntl(3, F_SETFL, O_RDWR|O_NONBLOCK) = 0
> +
> +0.1 connect(3, ..., ...) = -1 EINPROGRESS (Operation now in progress)
> +0.1 > S 0:0(0) win 65535 <mss 1460,sackOK,TS val 1 ecr 0,nop,wscale 8>
> +
> +// Challenge ACK, old incarnation.
> +0.1 < . 145824453:145824453(0) ack 643160523 win 240 <mss 1460,nop,nop,TS val 1 ecr 1,nop,wscale 0>
> +
> ++0.01 > R 643160523:643160523(0) win 0
> +
> ++0.01 `conntrack -f $NFCT_IP_VERSION -L -p tcp --dport 8080 2>/dev/null | grep UNREPLIED | grep -q SYN_SENT`
> +
> +// Must go through.
> ++0.01 > S 0:0(0) win 65535 <mss 1460,sackOK,TS val 1 ecr 0,nop,wscale 8>
> +
> +// correct synack
> ++0.1 < S. 0:0(0) ack 1 win 250 <mss 1460,nop,nop,TS val 1 ecr 1,nop,wscale 0>
> +
> +// 3whs completes.
> ++0.01 > . 1:1(0) ack 1 win 256 <nop,nop,TS val 1 ecr 1>
> +
> ++0 `conntrack -f $NFCT_IP_VERSION -L -p tcp --dport 8080 2>/dev/null | grep ESTABLISHED | grep -q ASSURED`
> +
> +// No packets should have been marked INVALID
> ++0 `$xtables -v -S INPUT  | grep INVALID | grep -q -- "-c 0 0"`
> ++0 `$xtables -v -S OUTPUT | grep INVALID | grep -q -- "-c 0 0"`
> diff --git a/tools/testing/selftests/net/netfilter/packetdrill/conntrack_synack_old.pkt b/tools/testing/selftests/net/netfilter/packetdrill/conntrack_synack_old.pkt
> new file mode 100644
> index 000000000000..3047160c4bf3
> --- /dev/null
> +++ b/tools/testing/selftests/net/netfilter/packetdrill/conntrack_synack_old.pkt
> @@ -0,0 +1,51 @@
> +// Check conntrack copes with syn/ack reply for a previous, old incarnation.
> +
> +// tcpdump with buggy sequence
> +// 10.176.25.8.829 > 10.192.171.30.2049: Flags [S], seq 2375731741, win 29200, options [mss 1460,sackOK,TS val 2083107423 ecr 0,nop,wscale 7], length 0
> +// OLD synack, for old/previous S
> +// 10.192.171.30.2049 > 10.176.25.8.829: Flags [S.], seq 145824453, ack 643160523, win 65535, options [mss 8952,nop,wscale 5,TS val 3215437785 ecr 2082921663,nop,nop], length 0
> +// This reset never makes it to the endpoint, elided in the packetdrill script
> +// 10.192.171.30.2049 > 10.176.25.8.829: Flags [R.], seq 1, ack 1, win 65535, options [mss 8952,nop,wscale 5,TS val 3215443451 ecr 2082921663,nop,nop], length 0
> +// Syn retransmit, no change
> +// 10.176.25.8.829 > 10.192.171.30.2049: Flags [S], seq 2375731741, win 29200, options [mss 1460,sackOK,TS val 2083115583 ecr 0,nop,wscale 7], length 0
> +// CORRECT synack, should be accepted, but conntrack classified this as INVALID:
> +// SEQ is over the upper bound (over the window of the receiver) IN=tun0 OUT= MAC= SRC=192.0.2.1 DST=192.168.37.78 LEN=40 TOS=0x00 PREC=0x00 TTL=255 ID=0 PROTO=TCP SPT=8080 DPT=34500 SEQ=162602411 ACK=2124350315 ..
> +// 10.192.171.30.2049 > 10.176.25.8.829: Flags [S.], seq 162602410, ack 2375731742, win 65535, options [mss 8952,nop,wscale 5,TS val 3215445754 ecr 2083115583,nop,nop], length 0
> +
> +`packetdrill/common.sh`
> +
> ++0 `$xtables -A INPUT -p tcp -m conntrack --ctstate INVALID -j DROP`
> ++0 `$xtables -A OUTPUT -p tcp -m conntrack --ctstate INVALID -j DROP`
> +
> ++0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3
> ++0 fcntl(3, F_SETFL, O_RDWR|O_NONBLOCK) = 0
> +
> +0.1 connect(3, ..., ...) = -1 EINPROGRESS (Operation now in progress)
> +0.1 > S 0:0(0) win 65535 <mss 1460,sackOK,TS val 1 ecr 0,nop,wscale 8>
> +
> +// bogus/outdated synack, invalid ack value
> +0.1 < S. 145824453:145824453(0) ack 643160523 win 240 <mss 1440,nop,nop,TS val 1 ecr 1,nop,wscale 0>
> +
> +// syn retransmitted
> +1.01 > S 0:0(0) win 65535 <mss 1460,sackOK,TS val 1015 ecr 0,nop,wscale 8>
> ++0 `conntrack -f $NFCT_IP_VERSION -L -p tcp --dport 8080 2>/dev/null | grep UNREPLIED | grep -q SYN_SENT`
> +
> +// correct synack
> ++0 < S. 145758918:145758918(0) ack 1 win 250 <mss 1460,nop,nop,TS val 1 ecr 1,nop,wscale 0>
> ++0 write(3, ..., 1) = 1
> +
> +// with buggy conntrack above packet is dropped, so SYN rtx is seen:
> +// script packet:  1.054007 . 1:1(0) ack 16777958 win 256 <nop,nop,TS val 1033 ecr 1>
> +// actual packet:  3.010000 S 0:0(0) win 65535 <mss 1460,sackOK,TS val 1015 ecr 0,nop,wscale 8>
> ++0 `conntrack -f $NFCT_IP_VERSION -L -p tcp --dport 8080 2>/dev/null | grep ESTABLISHED | grep -q ASSURED`
> +
> ++0 > P. 1:2(1) ack 4294901762 win 256 <nop,nop,TS val 1067 ecr 1>
> +
> ++0 `conntrack -f $NFCT_IP_VERSION -L -p tcp --dport 8080 2>/dev/null | grep ASSURED | grep -q ESTABLISHED`
> +
> +// No packets should have been marked INVALID in OUTPUT direction, 1 in INPUT
> ++0 `$xtables -v -S OUTPUT | grep INVALID | grep -q -- "-c 0 0"`
> ++0 `$xtables -v -S INPUT  | grep INVALID | grep -q -- "-c 1 "`
> +
> ++0 `$xtables -D INPUT -p tcp -m conntrack --ctstate INVALID -j DROP`
> ++0 `$xtables -D OUTPUT -p tcp -m conntrack --ctstate INVALID -j DROP`
> diff --git a/tools/testing/selftests/net/netfilter/packetdrill/conntrack_synack_reuse.pkt b/tools/testing/selftests/net/netfilter/packetdrill/conntrack_synack_reuse.pkt
> new file mode 100644
> index 000000000000..21e1bb6395e4
> --- /dev/null
> +++ b/tools/testing/selftests/net/netfilter/packetdrill/conntrack_synack_reuse.pkt
> @@ -0,0 +1,34 @@
> +// Check reception of another SYN while we have an established conntrack state.
> +// Challenge ACK is supposed to pass through, RST reply should clear conntrack
> +// state and SYN retransmit should give us new 'SYN_RECV' connection state.
> +
> +`packetdrill/common.sh`
> +
> +// should show a match if bug is present:
> ++0 `iptables -A INPUT -m conntrack --ctstate INVALID -p tcp --tcp-flags SYN,ACK SYN,ACK`
> +
> ++0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3
> ++0 setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0
> ++0 bind(3, ..., ...) = 0
> ++0 listen(3, 10) = 0
> +
> ++0 < S 0:0(0) win 32792 <mss 1000,nop,wscale 7, TS val 1 ecr 0,nop,nop>
> ++0 > S. 0:0(0) ack 1 <mss 1460,nop,nop,TS val 100 ecr 1,nop,wscale 8>
> ++.01 < . 1:1(0) ack 1 win 257 <TS val 1 ecr 100,nop,nop>
> ++0 accept(3, ..., ...) = 4
> +
> ++0 < P. 1:101(100) ack 1 win 257 <TS val 2 ecr 100,nop,nop>
> ++.001 > . 1:1(0) ack 101 win 256 <nop,nop,TS val 110 ecr 2>
> ++0 read(4, ..., 101) = 100
> +
> +1.0 < S 2000:2000(0) win 32792 <mss 1000,nop,wscale 7, TS val 233 ecr 0,nop,nop>
> +// Won't expect this: challenge ack.
> +
> ++0 > . 1:1(0) ack 101 win 256 <nop,nop,TS val 112 ecr 2>
> ++0 < R. 101:101(0) ack 1 win 257
> ++0 close(4) = 0
> +
> +1.5 < S 2000:2000(0) win 32792 <mss 1000,nop,wscale 0, TS val 233 ecr 0,nop,nop>
> +
> ++0 `conntrack -L -p tcp --dport 8080 2>/dev/null | grep -q SYN_RECV`
> ++0 `iptables -v -S INPUT | grep INVALID | grep -q -- "-c 0 0"`
> -- 
> 2.43.2
> 
> 
> 

-- 
E-mail  : kadlec@...ckhole.kfki.hu, kadlecsik.jozsef@...ner.hu
PGP key : https://wigner.hu/~kadlec/pgp_public_key.txt
Address : Wigner Research Centre for Physics
          H-1525 Budapest 114, POB. 49, Hungary

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