[PATCH net-next 0/4] mptcp: misc improvements for v7.4

[PATCH net-next 0/4] mptcp: misc improvements for v7.4

[Matthieu Baerts (NGI0)]

Here are some unrelated improvements for MPTCP and its selftests:

- Patches 1-2: avoid printing (pr_debug) uninitialised data. These are
  non-urgent fixes that can be backported to silence errors or if it
  helps with other backports.

- Patches 3-4: convert IPTables to NFTables in MPTCP selftests.

Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
---
Note: patches 3-4 have been previously sent as part of another series:

  https://lore.kernel.org/20260926-net-next-mptcp-misc-feat-7-4-v1-0-67af4ab37406@kernel.org

---
Hangbin Liu (2):
      selftests: mptcp: convert iptables to nftables for mptcp_sockopt.sh
      selftests: mptcp: convert iptables to nftables for mptcp_join.sh

Matthieu Baerts (NGI0) (2):
      mptcp: options: mpc: avoid printing uninit data
      mptcp: options: dss: avoid printing uninit csum

 net/mptcp/options.c                                |   9 +-
 tools/testing/selftests/net/mptcp/config           |  15 +-
 tools/testing/selftests/net/mptcp/mptcp_join.sh    | 158 +++++++++------------
 tools/testing/selftests/net/mptcp/mptcp_lib.sh     |   9 +-
 tools/testing/selftests/net/mptcp/mptcp_sockopt.sh |  53 +++----
 5 files changed, 113 insertions(+), 131 deletions(-)
---
base-commit: d7804253678eb18d2be950e0542364b50be096a9
change-id: 20261012-net-next-mptcp-misc-feat-7-4-part2-214a09fa1025

Best regards,
--  
Matthieu Baerts (NGI0) <matttbe@kernel.org>

[PATCH net-next 1/4] mptcp: options: mpc: avoid printing uninit data

[Matthieu Baerts (NGI0)]

When parsing the MP_CAPABLE suboption, this pr_debug() might read and
print uninitialised values.

That's mostly harmless, but that's also confusing. Fixing that also
avoids some tools to complain about accessing uninit data.

So read these fields only if they have been set.

Note: this was initially reported by Clashiko as an existing issue. The
code has been analysed by a human and confirmed. This is a non-urgent
fix.

Fixes: cc7972ea1932 ("mptcp: parse and emit MP_CAPABLE option according to v1 spec")
Reviewed-by: Mat Martineau <martineau@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
---
 net/mptcp/options.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/net/mptcp/options.c b/net/mptcp/options.c
index c2f4d7bd080c..3b4a22846055 100644
--- a/net/mptcp/options.c
+++ b/net/mptcp/options.c
@@ -126,8 +126,11 @@ static void mptcp_parse_option(const struct sk_buff *skb,
 			ptr += 2;
 		}
 		pr_debug("MP_CAPABLE version=%x, flags=%x, optlen=%d sndr=%llu, rcvr=%llu len=%d csum=%u\n",
-			 version, flags, opsize, mp_opt->sndr_key,
-			 mp_opt->rcvr_key, mp_opt->data_len, mp_opt->csum);
+			 version, flags, opsize,
+			 opsize >= TCPOLEN_MPTCP_MPC_SYNACK ? mp_opt->sndr_key : 0,
+			 opsize >= TCPOLEN_MPTCP_MPC_ACK ? mp_opt->rcvr_key : 0,
+			 opsize >= TCPOLEN_MPTCP_MPC_ACK_DATA ? mp_opt->data_len : 0,
+			 opsize == TCPOLEN_MPTCP_MPC_ACK_DATA_CSUM ? mp_opt->csum : 0);
 		break;
 
 	case MPTCPOPT_MP_JOIN:

-- 
2.55.0

[PATCH net-next 2/4] mptcp: options: dss: avoid printing uninit csum

[Matthieu Baerts (NGI0)]

When parsing the DSS suboption, this pr_debug() might read and print
uninitialised checksum value.

That's mostly harmless, but that's also confusing. Fixing that also
avoids some tools to complain about accessing uninit data.

So read this csum field only if it has been set.

Note: this was initially reported by Clashiko as an existing issue. The
code has been analysed by a human and confirmed. This is a non-urgent
fix.

Fixes: 390b95a5fb84 ("mptcp: receive checksum for DSS")
Reviewed-by: Mat Martineau <martineau@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
---
 net/mptcp/options.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/mptcp/options.c b/net/mptcp/options.c
index 3b4a22846055..64aa7a516a23 100644
--- a/net/mptcp/options.c
+++ b/net/mptcp/options.c
@@ -259,7 +259,7 @@ static void mptcp_parse_option(const struct sk_buff *skb,
 			pr_debug("data_seq=%llu subflow_seq=%u data_len=%u csum=%d:%u\n",
 				 mp_opt->data_seq, mp_opt->subflow_seq,
 				 mp_opt->data_len, !!(mp_opt->suboptions & OPTION_MPTCP_CSUMREQD),
-				 mp_opt->csum);
+				 (mp_opt->suboptions & OPTION_MPTCP_CSUMREQD) ? mp_opt->csum : 0);
 		}
 
 		break;

-- 
2.55.0

[PATCH net-next 3/4] selftests: mptcp: convert iptables to nftables for mptcp_sockopt.sh

[Matthieu Baerts (NGI0)]

From: Hangbin Liu <liuhangbin@kylinos.cn>

During the conversion, we retain the same filter and chain names previously
used by iptables/ip6tables. Counters are not added to accept rules because
the test does not inspect them. The syn mark rule is removed as it is
only for debugging, which could be added easily when needed.

After conversion, the generated output matches the original
iptables/ip6tables behavior.

Signed-off-by: Hangbin Liu <liuhangbin@kylinos.cn>
Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
---
To: Shuah Khan <shuah@kernel.org>
Cc: linux-kselftest@vger.kernel.org
v2:
 - Use nft --version + JSON to support old/weird versions. (Clashiko)
 - Remove syn mark rule. (Clashiko)
---
 tools/testing/selftests/net/mptcp/mptcp_lib.sh     |  9 +++-
 tools/testing/selftests/net/mptcp/mptcp_sockopt.sh | 53 ++++++++++++----------
 2 files changed, 36 insertions(+), 26 deletions(-)

diff --git a/tools/testing/selftests/net/mptcp/mptcp_lib.sh b/tools/testing/selftests/net/mptcp/mptcp_lib.sh
index b9d14647f401..20853d0198ff 100644
--- a/tools/testing/selftests/net/mptcp/mptcp_lib.sh
+++ b/tools/testing/selftests/net/mptcp/mptcp_lib.sh
@@ -528,7 +528,14 @@ mptcp_lib_check_tools() {
 				exit ${KSFT_SKIP}
 			fi
 			;;
-		"iptables"* | "ip6tables"*)
+		"nft")
+			if ! nft --version &> /dev/null || \
+			   ! nft -j list ruleset &> /dev/null; then
+				mptcp_lib_pr_skip "Could not run all tests without nft -j"
+				exit ${KSFT_SKIP}
+			fi
+			;;
+		"iptables"* | "ip6tables"* | "jq")
 			if ! "${tool}" -V &> /dev/null; then
 				mptcp_lib_pr_skip "Could not run all tests without ${tool}"
 				exit ${KSFT_SKIP}
diff --git a/tools/testing/selftests/net/mptcp/mptcp_sockopt.sh b/tools/testing/selftests/net/mptcp/mptcp_sockopt.sh
index e850a87429b6..ef2738720e24 100755
--- a/tools/testing/selftests/net/mptcp/mptcp_sockopt.sh
+++ b/tools/testing/selftests/net/mptcp/mptcp_sockopt.sh
@@ -15,8 +15,6 @@ cin=""
 cout=""
 timeout_poll=30
 timeout_test=$((timeout_poll * 2 + 1))
-iptables="iptables"
-ip6tables="ip6tables"
 
 ns1=""
 ns2=""
@@ -49,16 +47,22 @@ add_mark_rules()
 	local ns=$1
 	local m=$2
 
-	local t
-	for t in ${iptables} ${ip6tables}; do
-		# just to debug: check we have multiple subflows connection requests
-		ip netns exec $ns $t -A OUTPUT -p tcp --syn -m mark --mark $m -j ACCEPT
+	local table
+	for table in ip ip6; do
+		ip netns exec "$ns" nft -f - <<-EOF
+			add table $table filter
+			add chain $table filter OUTPUT \
+				{ type filter hook output priority 0; policy accept; }
 
-		# RST packets might be handled by a internal dummy socket
-		ip netns exec $ns $t -A OUTPUT -p tcp --tcp-flags RST RST -m mark --mark 0 -j ACCEPT
+			# RST packets might be handled by a internal dummy socket
+			add rule $table filter OUTPUT \
+				tcp flags & rst == rst meta mark 0x0 accept
 
-		ip netns exec $ns $t -A OUTPUT -p tcp -m mark --mark $m -j ACCEPT
-		ip netns exec $ns $t -A OUTPUT -p tcp -m mark --mark 0 -j DROP
+			add rule $table filter OUTPUT \
+				meta l4proto tcp meta mark $m accept
+			add rule $table filter OUTPUT \
+				meta l4proto tcp meta mark 0 counter drop
+		EOF
 	done
 }
 
@@ -105,32 +109,31 @@ cleanup()
 
 mptcp_lib_check_mptcp
 mptcp_lib_check_kallsyms
-mptcp_lib_check_tools ip "${iptables}" "${ip6tables}"
+mptcp_lib_check_tools ip nft jq
 
 check_mark()
 {
 	local ns=$1
 	local af=$2
 
-	local tables=${iptables}
+	local tables="ip"
 
 	if [ $af -eq 6 ];then
-		tables=${ip6tables}
+		tables="ip6"
 	fi
 
-	local counters values
-	counters=$(ip netns exec $ns $tables -v -L OUTPUT | grep DROP)
-	values=${counters%DROP*}
+	local drops
+	drops=$(ip netns exec "$ns" nft -j list table "$tables" filter | \
+		jq '.nftables[] | select(has("rule")) | .rule |
+			select (.chain=="OUTPUT" and any(.expr[]; has("drop"))) |
+			.expr[] | select(has("counter")) | .counter.packets')
 
-	local v
-	for v in $values; do
-		if [ $v -ne 0 ]; then
-			mptcp_lib_pr_fail "got $tables $values in ns $ns," \
-					  "not 0 - not all expected packets marked"
-			ret=${KSFT_FAIL}
-			return 1
-		fi
-	done
+	if [ -z "$drops" ] || [ "$drops" -ne 0 ]; then
+		mptcp_lib_pr_fail "got $tables $drops in ns $ns," \
+				  "not 0 - not all expected packets marked"
+		ret=${KSFT_FAIL}
+		return 1
+	fi
 
 	return 0
 }

-- 
2.55.0

Re: [PATCH net-next 3/4] selftests: mptcp: convert iptables to nftables for mptcp_sockopt.sh

[netdev-bot+sashiko]

Thank you for your contribution! Sashiko AI review found more severe
issue(s) in other patches of this series. This mail is only an FYI, in case
you want to address the nit picks below when you respin.

Low priority / nit picks for your consideration:

- [Low] The commit message does not mention two new runtime requirements
  added by this patch.

--

selftests: mptcp: convert iptables to nftables for mptcp_sockopt.sh

This patch moves the mark rules in mptcp_sockopt.sh from iptables/ip6tables
to nftables and keeps the same table and chain names. check_mark() now reads
the drop counter from nft JSON output and parses it with jq.
mptcp_lib_check_tools() gets new checks for nft and jq.

> diff --git a/tools/testing/selftests/net/mptcp/mptcp_lib.sh b/tools/testing/selftests/net/mptcp/mptcp_lib.sh
> index b9d14647f4019..20853d0198ffc 100644
> --- a/tools/testing/selftests/net/mptcp/mptcp_lib.sh
> +++ b/tools/testing/selftests/net/mptcp/mptcp_lib.sh
> @@ -528,7 +528,14 @@ mptcp_lib_check_tools() {
>  				exit ${KSFT_SKIP}
>  			fi
>  			;;
> -		"iptables"* | "ip6tables"*)
> +		"nft")
> +			if ! nft --version &> /dev/null || \
> +			   ! nft -j list ruleset &> /dev/null; then
> +				mptcp_lib_pr_skip "Could not run all tests without nft -j"
> +				exit ${KSFT_SKIP}
> +			fi
> +			;;
> +		"iptables"* | "ip6tables"* | "jq")
>  			if ! "${tool}" -V &> /dev/null; then
>  				mptcp_lib_pr_skip "Could not run all tests without ${tool}"
>  				exit ${KSFT_SKIP}
> diff --git a/tools/testing/selftests/net/mptcp/mptcp_sockopt.sh b/tools/testing/selftests/net/mptcp/mptcp_sockopt.sh
> index e850a87429b61..ef2738720e249 100755
> --- a/tools/testing/selftests/net/mptcp/mptcp_sockopt.sh
> +++ b/tools/testing/selftests/net/mptcp/mptcp_sockopt.sh

[ ... ]

> @@ -105,32 +109,31 @@ cleanup()
>  
>  mptcp_lib_check_mptcp
>  mptcp_lib_check_kallsyms
> -mptcp_lib_check_tools ip "${iptables}" "${ip6tables}"
> +mptcp_lib_check_tools ip nft jq

[Severity: Low]
This isn't a bug, but should the commit message list the new runtime
requirements? The script now needs jq and an nft built with JSON support
(nft -j list ruleset). The shared mptcp_lib_check_tools() helper in
mptcp_lib.sh also gets new "nft" and "jq" cases.

The commit message only says:

    After conversion, the generated output matches the original
    iptables/ip6tables behavior.

The reason for using JSON and jq appears only in the v2 notes below the
--- line, and those notes are dropped when the patch is applied.

This check runs at top level, before any subtest. So a system that has
iptables but no jq, or an nft without JSON support, now skips the whole
script. That includes do_mptcp_sockopt_tests and do_tcpinq_tests, which
don't use netfilter.

Could the commit message mention the jq and nft JSON dependencies and the
mptcp_lib.sh change?

[ ... ]

-- 
Sashiko AI review · https://netdev-ai.bots.linux.dev/sashiko/#/patchset/20261013-net-next-mptcp-misc-feat-7-4-part2-v1-0-1181e5d2fda4%40kernel.org

[PATCH net-next 4/4] selftests: mptcp: convert iptables to nftables for mptcp_join.sh

[Matthieu Baerts (NGI0)]

From: Hangbin Liu <liuhangbin@kylinos.cn>

During conversion, we retain the same table and chain names used by the
original iptables/ip6tables setup, so rule output is identical to the
former iptables/ip6tables output. Add new function init_nftables so we
only do nft table setup when test need set nft rules.

Unlike iptables, nftables cannot match rules based on their full
specification. Since endpoint_tests is the only test that delete rules,
which inserts and deletes rules one by one. Flushing the table
directly is safe and easier than using nft_handle.

The cBPF bytecode matching MPTCP add‑addr is replaced with native nft
matching using "tcp option mptcp subtype add-addr". But the RM_ADDR
suboption is added after the MPTCP DSS option, and nft is unable to
handle this because it stops parsing further TCP options once it matches
the first one. We therefore use hard-coded offsets to match the RM_ADDR
suboption.

The config file adds CONFIG_NFT_NUMGEN (replaces iptables statistic nth),
CONFIG_NFT_REJECT and CONFIG_NFT_REJECT_INET for reject‑related rules.
Remove other unneeded configs.

Remove the iptables/ip6tables check in mptcp_lib.sh since no script use
it now.

Signed-off-by: Hangbin Liu <liuhangbin@kylinos.cn>
Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
---
To: Shuah Khan <shuah@kernel.org>
Cc: linux-kselftest@vger.kernel.org
Cc: bpf@vger.kernel.org
v2:
 - Remove more unused kconfigs. (Clashiko)
 - Use offset to match RM_ADDR, instead of "mptcp subtype". (Clashiko)
---
 tools/testing/selftests/net/mptcp/config        |  15 +--
 tools/testing/selftests/net/mptcp/mptcp_join.sh | 158 ++++++++++--------------
 tools/testing/selftests/net/mptcp/mptcp_lib.sh  |   2 +-
 3 files changed, 72 insertions(+), 103 deletions(-)

diff --git a/tools/testing/selftests/net/mptcp/config b/tools/testing/selftests/net/mptcp/config
index bb9c4c97c620..6a96cfbbc461 100644
--- a/tools/testing/selftests/net/mptcp/config
+++ b/tools/testing/selftests/net/mptcp/config
@@ -1,12 +1,7 @@
 CONFIG_INET_DIAG=m
 CONFIG_INET_MPTCP_DIAG=m
-CONFIG_IP6_NF_FILTER=m
-CONFIG_IP6_NF_TARGET_REJECT=m
 CONFIG_IP_ADVANCED_ROUTER=y
 CONFIG_IP_MULTIPLE_TABLES=y
-CONFIG_IP_NF_FILTER=m
-CONFIG_IP_NF_MANGLE=m
-CONFIG_IP_NF_TARGET_REJECT=m
 CONFIG_IPV6=y
 CONFIG_IPV6_MULTIPLE_TABLES=y
 CONFIG_KALLSYMS=y
@@ -19,17 +14,13 @@ CONFIG_NET_CLS_FW=m
 CONFIG_NETFILTER=y
 CONFIG_NETFILTER_ADVANCED=y
 CONFIG_NETFILTER_NETLINK=y
-CONFIG_NETFILTER_XTABLES=m
-CONFIG_NETFILTER_XTABLES_LEGACY=y
-CONFIG_NETFILTER_XT_MATCH_BPF=m
-CONFIG_NETFILTER_XT_MATCH_LENGTH=m
-CONFIG_NETFILTER_XT_MATCH_STATISTIC=m
-CONFIG_NETFILTER_XT_TARGET_MARK=m
 CONFIG_NET_SCH_INGRESS=m
 CONFIG_NET_SCH_NETEM=m
 CONFIG_NF_TABLES=m
 CONFIG_NF_TABLES_INET=y
-CONFIG_NFT_COMPAT=m
+CONFIG_NFT_NUMGEN=m
+CONFIG_NFT_REJECT=m
+CONFIG_NFT_REJECT_INET=m
 CONFIG_NFT_SOCKET=m
 CONFIG_NFT_TPROXY=m
 CONFIG_SYN_COOKIES=y
diff --git a/tools/testing/selftests/net/mptcp/mptcp_join.sh b/tools/testing/selftests/net/mptcp/mptcp_join.sh
index 18ce7136a2b0..f4d8afaeda4f 100755
--- a/tools/testing/selftests/net/mptcp/mptcp_join.sh
+++ b/tools/testing/selftests/net/mptcp/mptcp_join.sh
@@ -26,8 +26,6 @@ capout=""
 cappid=""
 ns1=""
 ns2=""
-iptables="iptables"
-ip6tables="ip6tables"
 timeout_poll=30
 timeout_test=$((timeout_poll * 2 + 1))
 capture=false
@@ -99,41 +97,16 @@ unset add_addr_tx_nr
 unset add_addr_echo_tx_nr
 unset add_addr_drop_tx_nr
 
-# generated using "nfbpf_compile '(ip && (ip[54] & 0xf0) == 0x30) ||
-#				  (ip6 && (ip6[74] & 0xf0) == 0x30)'"
-CBPF_MPTCP_SUBOPTION_ADD_ADDR="14,
-			       48 0 0 0,
-			       84 0 0 240,
-			       21 0 3 64,
-			       48 0 0 54,
-			       84 0 0 240,
-			       21 6 7 48,
-			       48 0 0 0,
-			       84 0 0 240,
-			       21 0 4 96,
-			       48 0 0 74,
-			       84 0 0 240,
-			       21 0 1 48,
-			       6 0 0 65535,
-			       6 0 0 0"
-
-# IPv4: TCP hdr of 48B, a first suboption of 12B (DACK8), the RM_ADDR suboption
-# generated using "nfbpf_compile '(ip[32] & 0xf0) == 0xc0 && ip[53] == 0x0c &&
-#				  (ip[66] & 0xf0) == 0x40'"
-CBPF_MPTCP_SUBOPTION_RM_ADDR="13,
-			      48 0 0 0,
-			      84 0 0 240,
-			      21 0 9 64,
-			      48 0 0 32,
-			      84 0 0 240,
-			      21 0 6 192,
-			      48 0 0 53,
-			      21 0 4 12,
-			      48 0 0 66,
-			      84 0 0 240,
-			      21 0 1 64,
-			      6 0 0 65535,
-			      6 0 0 0"
+# nft cannot process the RM_ADDR option because it stops parsing after matching
+# the first DSS option. Use hard-coded byte offsets to match RM_ADDR messages.
+# A tcpdump capture of the RM_ADDR message looks like:
+#  [TCP header: 20 bytes] [nop] [nop] [timestamp: 10 bytes]
+#  [MPTCP DSS: 12 bytes] [MPTCP RM_ADDR: 4 bytes]
+#
+# - TCP Data Offset (12 x 4 = 48 bytes)
+# - DSS (TCP[32] x 8) kind (MPTCP 0x1e), length (0x0c) and subtype (2)
+# - RM_ADDR (TCP[44] x 8) kind (MPTCP 0x1e), variable length and subtype (4)
+RM_ADDR_OFFSETS="tcp doff 12 @th,256,20 == 0x1e0c2 @th,352,8 == 0x1e @th,368,4 == 4"
 
 init_partial()
 {
@@ -184,6 +157,26 @@ init_shapers()
 	done
 }
 
+init_nftables()
+{
+	local netns table
+	for netns in "$ns1" "$ns2"; do
+		for table in ip ip6; do
+			ip netns exec "$netns" nft -f - <<-EOF
+				add table $table filter
+				add chain $table filter INPUT \
+					{ type filter hook input priority filter; policy accept; }
+				add chain $table filter OUTPUT \
+					{ type filter hook output priority filter; policy accept; }
+
+				add table $table mangle
+				add chain $table mangle OUTPUT \
+					{ type route hook output priority mangle; policy accept; }
+			EOF
+		done
+	done
+}
+
 cleanup_partial()
 {
 	rm -f "$capout"
@@ -196,7 +189,7 @@ init() {
 
 	mptcp_lib_check_mptcp
 	mptcp_lib_check_kallsyms
-	mptcp_lib_check_tools ip tc ss "${iptables}" "${ip6tables}"
+	mptcp_lib_check_tools ip tc ss nft
 
 	sin=$(mktemp)
 	sout=$(mktemp)
@@ -380,24 +373,18 @@ reset_with_cookies()
 # $1: test name
 reset_with_add_addr_timeout()
 {
-	local ip="${2:-4}"
-	local tables
+	local ip="${2:-}"
 
 	reset "${1}" || return 1
-
-	tables="${iptables}"
-	if [ $ip -eq 6 ]; then
-		tables="${ip6tables}"
-	fi
+	init_nftables
 
 	# set a maximum, to avoid too long timeout with exponential backoff
 	ip netns exec $ns1 sysctl -q net.mptcp.add_addr_timeout=1
 
-	if ! ip netns exec $ns2 $tables -A OUTPUT -p tcp \
-			-m tcp --tcp-option 30 \
-			-m bpf --bytecode \
-			"$CBPF_MPTCP_SUBOPTION_ADD_ADDR" \
-			-j DROP; then
+	if ! ip netns exec "$ns2" nft add rule \
+			ip"$ip" filter OUTPUT meta l4proto tcp \
+			tcp option mptcp subtype add-addr \
+			drop; then
 		mark_as_skipped "unable to set the 'add addr' rule"
 		return 1
 	fi
@@ -449,22 +436,14 @@ setup_fail_rules()
 	check_invert=1
 	validate_checksum=true
 	local i="$1"
-	local ip="${2:-4}"
-	local tables
+	local ip="${2:-}"
 
-	tables="${iptables}"
-	if [ $ip -eq 6 ]; then
-		tables="${ip6tables}"
-	fi
-
-	ip netns exec $ns2 $tables \
-		-t mangle \
-		-A OUTPUT \
-		-o ns2eth$i \
-		-p tcp \
-		-m length --length 150:9999 \
-		-m statistic --mode nth --packet 1 --every 99999 \
-		-j MARK --set-mark 42 || return ${KSFT_SKIP}
+	init_nftables
+	ip netns exec "$ns2" nft add rule \
+		ip"$ip" mangle OUTPUT oifname ns2eth$i \
+		meta l4proto tcp \
+		meta length 150-9999 numgen inc mod 99999 1 \
+		meta mark set 42 || return ${KSFT_SKIP}
 
 	tc -n $ns2 qdisc add dev ns2eth$i clsact || return ${KSFT_SKIP}
 	tc -n $ns2 filter add dev ns2eth$i egress \
@@ -510,16 +489,15 @@ reset_with_tcp_filter()
 	reset "${1}" || return 1
 	shift
 
+	init_nftables
+
 	local ns="${!1}"
 	local src="${2}"
 	local target="${3}"
 	local chain="${4:-INPUT}"
 
-	if ! ip netns exec "${ns}" ${iptables} \
-			-A "${chain}" \
-			-s "${src}" \
-			-p tcp \
-			-j "${target}"; then
+	if ! ip netns exec "$ns" nft add rule ip filter "${chain}" \
+			ip saddr "${src}" meta l4proto tcp "${target,,}"; then
 		mark_as_skipped "unable to set the filter rules"
 		return 1
 	fi
@@ -4313,12 +4291,15 @@ userspace_tests()
 		chk_mptcp_info subflows 1 subflows 1
 		chk_subflows_total 2 2
 
+		init_nftables
 		# force quick loss
 		ip netns exec $ns2 sysctl -q net.ipv4.tcp_syn_retries=1
-		if ip netns exec "${ns1}" ${iptables} -A INPUT -s "10.0.1.2" \
-		      -p tcp --tcp-option 30 -j REJECT --reject-with tcp-reset &&
-		   ip netns exec "${ns2}" ${iptables} -A INPUT -d "10.0.1.2" \
-		      -p tcp --tcp-option 30 -j REJECT --reject-with tcp-reset; then
+		if ip netns exec "${ns1}" nft add rule ip filter INPUT \
+				ip saddr "10.0.1.2" meta l4proto tcp \
+				tcp option mptcp exists reject with tcp reset &&
+		   ip netns exec "${ns2}" nft add rule ip filter INPUT \
+				ip daddr "10.0.1.2" meta l4proto tcp \
+				tcp option mptcp exists reject with tcp reset; then
 			wait_event ns2 MPTCP_LIB_EVENT_SUB_CLOSED 1
 			wait_event ns1 MPTCP_LIB_EVENT_SUB_CLOSED 1
 			chk_subflows_total 1 1
@@ -4393,7 +4374,7 @@ endpoint_tests()
 		chk_subflow_nr "after new reject" 2
 		chk_mptcp_info subflows 1 subflows 1
 
-		ip netns exec "${ns2}" ${iptables} -D OUTPUT -s "10.0.3.2" -p tcp -j REJECT
+		ip netns exec "${ns2}" nft flush chain ip filter OUTPUT
 		pm_nl_del_endpoint $ns2 3 10.0.3.2
 		pm_nl_add_endpoint $ns2 10.0.3.2 id 3 flags subflow
 		wait_mpj 3
@@ -4402,12 +4383,10 @@ endpoint_tests()
 
 		# To make sure RM_ADDR are sent over a different subflow, but
 		# allow the rest to quickly and cleanly close the subflow
-		local ipt=1
-		ip netns exec "${ns2}" ${iptables} -I OUTPUT -s "10.0.1.2" \
-			-p tcp -m tcp --tcp-option 30 \
-			-m bpf --bytecode \
-			"$CBPF_MPTCP_SUBOPTION_RM_ADDR" \
-			-j DROP || ipt=0
+		local nft=1
+		ip netns exec "${ns2}" nft insert rule ip filter OUTPUT \
+			ip saddr 10.0.1.2 meta l4proto tcp \
+			"${RM_ADDR_OFFSETS}" drop || nft=0
 		local i
 		for i in $(seq 3); do
 			pm_nl_del_endpoint $ns2 1 10.0.1.2
@@ -4420,7 +4399,7 @@ endpoint_tests()
 			chk_subflow_nr "after re-add id 0 ($i)" 3
 			chk_mptcp_info subflows 3 subflows 3
 		done
-		[ ${ipt} = 1 ] && ip netns exec "${ns2}" ${iptables} -D OUTPUT 1
+		[ "${nft}" = 1 ] && ip netns exec "${ns2}" nft flush chain ip filter OUTPUT
 
 		mptcp_lib_kill_group_wait $tests_pid
 
@@ -4480,20 +4459,19 @@ endpoint_tests()
 		chk_mptcp_info subflows 2 subflows 2
 		chk_mptcp_info add_addr_signal 2 add_addr_accepted 2
 
+		init_nftables
 		# To make sure RM_ADDR are sent over a different subflow, but
 		# allow the rest to quickly and cleanly close the subflow
-		local ipt=1
-		ip netns exec "${ns1}" ${iptables} -I OUTPUT -s "10.0.1.1" \
-			-p tcp -m tcp --tcp-option 30 \
-			-m bpf --bytecode \
-			"$CBPF_MPTCP_SUBOPTION_RM_ADDR" \
-			-j DROP || ipt=0
+		local nft=1
+		ip netns exec "${ns1}" nft insert rule ip filter OUTPUT \
+			ip saddr 10.0.1.1 meta l4proto tcp \
+			"${RM_ADDR_OFFSETS}" drop || nft=0
 		pm_nl_del_endpoint $ns1 42 10.0.1.1
 		sleep 0.5
 		chk_subflow_nr "after delete ID 0" 2
 		chk_mptcp_info subflows 2 subflows 2
 		chk_mptcp_info add_addr_signal 2 add_addr_accepted 2
-		[ ${ipt} = 1 ] && ip netns exec "${ns1}" ${iptables} -D OUTPUT 1
+		[ "${nft}" = 1 ] && ip netns exec "${ns1}" nft flush chain ip filter OUTPUT
 
 		pm_nl_add_endpoint $ns1 10.0.1.1 id 42 flags signal
 		wait_mpj 4
@@ -4555,7 +4533,7 @@ endpoint_tests()
 		pm_nl_flush_endpoint $ns2
 		pm_nl_flush_endpoint $ns1
 		wait_rm_addr $ns2 0
-		ip netns exec "${ns2}" ${iptables} -D OUTPUT -s "10.0.3.2" -p tcp -j REJECT
+		ip netns exec "${ns2}" nft flush chain ip filter OUTPUT
 		pm_nl_add_endpoint $ns2 10.0.3.2 id 3 flags subflow
 		wait_mpj 1
 		pm_nl_add_endpoint $ns1 10.0.3.1 id 2 flags signal
diff --git a/tools/testing/selftests/net/mptcp/mptcp_lib.sh b/tools/testing/selftests/net/mptcp/mptcp_lib.sh
index 20853d0198ff..e1c8c6fd8820 100644
--- a/tools/testing/selftests/net/mptcp/mptcp_lib.sh
+++ b/tools/testing/selftests/net/mptcp/mptcp_lib.sh
@@ -535,7 +535,7 @@ mptcp_lib_check_tools() {
 				exit ${KSFT_SKIP}
 			fi
 			;;
-		"iptables"* | "ip6tables"* | "jq")
+		"jq")
 			if ! "${tool}" -V &> /dev/null; then
 				mptcp_lib_pr_skip "Could not run all tests without ${tool}"
 				exit ${KSFT_SKIP}

-- 
2.55.0

Re: [PATCH net-next 4/4] selftests: mptcp: convert iptables to nftables for mptcp_join.sh

[netdev-bot+sashiko]

Thank you for your contribution! Sashiko AI review found 1 potential
issue(s) to consider.

Critical: 0 · High: 0 · Medium: 1 · Low: 0

If you believe none of the issues are legitimate, please reply to each
issue of Medium severity or higher and explain why the AI is wrong.
If any of them are legitimate and you plan to respin, please let patchwork
know by including "pw-bot: cr" as a separate line at the end of your reply
(one such reply per series is enough).

- [Medium] mptcp_join.sh init() now calls `mptcp_lib_check_tools ip tc ss
  nft` (mptcp_join.sh:192).

--

selftests: mptcp: convert iptables to nftables for mptcp_join.sh

This converts the iptables/ip6tables rules in mptcp_join.sh to nftables.
The cBPF bytecode matches are replaced with native nft matching, and
hard-coded offsets are used for RM_ADDR. The config file is updated to
match, and the iptables/ip6tables tool check is removed from
mptcp_lib.sh.

> diff --git a/tools/testing/selftests/net/mptcp/mptcp_join.sh b/tools/testing/selftests/net/mptcp/mptcp_join.sh
> index 18ce7136a2b0e..f4d8afaeda4f3 100755
> --- a/tools/testing/selftests/net/mptcp/mptcp_join.sh
> +++ b/tools/testing/selftests/net/mptcp/mptcp_join.sh

[ ... ]

> @@ -196,7 +189,7 @@ init() {
>  
>  	mptcp_lib_check_mptcp
>  	mptcp_lib_check_kallsyms
> -	mptcp_lib_check_tools ip tc ss "${iptables}" "${ip6tables}"
> +	mptcp_lib_check_tools ip tc ss nft

[Severity: Medium]
Will this skip the whole mptcp_join.sh suite when nft has no JSON
support?

The shared "nft" case in mptcp_lib_check_tools() in mptcp_lib.sh also
requires JSON output:

tools/testing/selftests/net/mptcp/mptcp_lib.sh:mptcp_lib_check_tools() {
    ...
		"nft")
			if ! nft --version &> /dev/null || \
			   ! nft -j list ruleset &> /dev/null; then
				mptcp_lib_pr_skip "Could not run all tests without nft -j"
				exit ${KSFT_SKIP}
			fi
			;;
    ...
}

As far as I can tell, that JSON requirement is there for
mptcp_sockopt.sh, which pipes "nft -j list table ... filter" into jq.

mptcp_join.sh never uses JSON output. It only runs "nft -f -" from
init_nftables(), plus "nft add rule", "nft insert rule" and "nft flush
chain".

If nft was built without JSON support, init() would exit with
KSFT_SKIP. Every join, PM, endpoint and userspace subtest would then be
skipped, including the many that do not use nft at all. The skip
message would also point at "nft -j", which this script does not need.

Before this patch, mptcp_join.sh only checked for iptables/ip6tables, so
nft JSON support did not matter here.

Would it make sense to check only for plain nft in mptcp_join.sh, for
example with a separate non-JSON case in mptcp_lib_check_tools()?

-- 
Sashiko AI review · https://netdev-ai.bots.linux.dev/sashiko/#/patchset/20261013-net-next-mptcp-misc-feat-7-4-part2-v1-0-1181e5d2fda4%40kernel.org