FAILED: patch "[PATCH] mptcp: don't account accept() of non-MPC client as fallback" failed to apply to 6.8-stable tree

FAILED: patch "[PATCH] mptcp: don't account accept() of non-MPC client as fallback" failed to apply to 6.8-stable tree

[gregkh]

The patch below does not apply to the 6.8-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.8.y
git checkout FETCH_HEAD
git cherry-pick -x 7a1b3490f47e88ec4cbde65f1a77a0f4bc972282
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2024040519-palpable-barrel-9103@gregkh' --subject-prefix 'PATCH 6.8.y' HEAD^..

Possible dependencies:



thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 7a1b3490f47e88ec4cbde65f1a77a0f4bc972282 Mon Sep 17 00:00:00 2001
From: Davide Caratti <dcaratti@redhat.com>
Date: Fri, 29 Mar 2024 13:08:52 +0100
Subject: [PATCH] mptcp: don't account accept() of non-MPC client as fallback
 to TCP

Current MPTCP servers increment MPTcpExtMPCapableFallbackACK when they
accept non-MPC connections. As reported by Christoph, this is "surprising"
because the counter might become greater than MPTcpExtMPCapableSYNRX.

MPTcpExtMPCapableFallbackACK counter's name suggests it should only be
incremented when a connection was seen using MPTCP options, then a
fallback to TCP has been done. Let's do that by incrementing it when
the subflow context of an inbound MPC connection attempt is dropped.
Also, update mptcp_connect.sh kselftest, to ensure that the
above MIB does not increment in case a pure TCP client connects to a
MPTCP server.

Fixes: fc518953bc9c ("mptcp: add and use MIB counter infrastructure")
Cc: stable@vger.kernel.org
Reported-by: Christoph Paasch <cpaasch@apple.com>
Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/449
Signed-off-by: Davide Caratti <dcaratti@redhat.com>
Reviewed-by: Mat Martineau <martineau@kernel.org>
Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://lore.kernel.org/r/20240329-upstream-net-20240329-fallback-mib-v1-1-324a8981da48@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index 3a1967bc7bad..7e74b812e366 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -3937,8 +3937,6 @@ static int mptcp_stream_accept(struct socket *sock, struct socket *newsock,
 				mptcp_set_state(newsk, TCP_CLOSE);
 		}
 	} else {
-		MPTCP_INC_STATS(sock_net(ssk),
-				MPTCP_MIB_MPCAPABLEPASSIVEFALLBACK);
 tcpfallback:
 		newsk->sk_kern_sock = kern;
 		lock_sock(newsk);
diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c
index 1626dd20c68f..6042a47da61b 100644
--- a/net/mptcp/subflow.c
+++ b/net/mptcp/subflow.c
@@ -905,6 +905,8 @@ static struct sock *subflow_syn_recv_sock(const struct sock *sk,
 	return child;
 
 fallback:
+	if (fallback)
+		SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_MPCAPABLEPASSIVEFALLBACK);
 	mptcp_subflow_drop_ctx(child);
 	return child;
 }
diff --git a/tools/testing/selftests/net/mptcp/mptcp_connect.sh b/tools/testing/selftests/net/mptcp/mptcp_connect.sh
index 4c4248554826..4131f3263a48 100755
--- a/tools/testing/selftests/net/mptcp/mptcp_connect.sh
+++ b/tools/testing/selftests/net/mptcp/mptcp_connect.sh
@@ -383,12 +383,14 @@ do_transfer()
 	local stat_cookierx_last
 	local stat_csum_err_s
 	local stat_csum_err_c
+	local stat_tcpfb_last_l
 	stat_synrx_last_l=$(mptcp_lib_get_counter "${listener_ns}" "MPTcpExtMPCapableSYNRX")
 	stat_ackrx_last_l=$(mptcp_lib_get_counter "${listener_ns}" "MPTcpExtMPCapableACKRX")
 	stat_cookietx_last=$(mptcp_lib_get_counter "${listener_ns}" "TcpExtSyncookiesSent")
 	stat_cookierx_last=$(mptcp_lib_get_counter "${listener_ns}" "TcpExtSyncookiesRecv")
 	stat_csum_err_s=$(mptcp_lib_get_counter "${listener_ns}" "MPTcpExtDataCsumErr")
 	stat_csum_err_c=$(mptcp_lib_get_counter "${connector_ns}" "MPTcpExtDataCsumErr")
+	stat_tcpfb_last_l=$(mptcp_lib_get_counter "${listener_ns}" "MPTcpExtMPCapableFallbackACK")
 
 	timeout ${timeout_test} \
 		ip netns exec ${listener_ns} \
@@ -457,11 +459,13 @@ do_transfer()
 	local stat_cookietx_now
 	local stat_cookierx_now
 	local stat_ooo_now
+	local stat_tcpfb_now_l
 	stat_synrx_now_l=$(mptcp_lib_get_counter "${listener_ns}" "MPTcpExtMPCapableSYNRX")
 	stat_ackrx_now_l=$(mptcp_lib_get_counter "${listener_ns}" "MPTcpExtMPCapableACKRX")
 	stat_cookietx_now=$(mptcp_lib_get_counter "${listener_ns}" "TcpExtSyncookiesSent")
 	stat_cookierx_now=$(mptcp_lib_get_counter "${listener_ns}" "TcpExtSyncookiesRecv")
 	stat_ooo_now=$(mptcp_lib_get_counter "${listener_ns}" "TcpExtTCPOFOQueue")
+	stat_tcpfb_now_l=$(mptcp_lib_get_counter "${listener_ns}" "MPTcpExtMPCapableFallbackACK")
 
 	expect_synrx=$((stat_synrx_last_l))
 	expect_ackrx=$((stat_ackrx_last_l))
@@ -508,6 +512,11 @@ do_transfer()
 		fi
 	fi
 
+	if [ ${stat_ooo_now} -eq 0 ] && [ ${stat_tcpfb_last_l} -ne ${stat_tcpfb_now_l} ]; then
+		mptcp_lib_pr_fail "unexpected fallback to TCP"
+		rets=1
+	fi
+
 	if [ $cookies -eq 2 ];then
 		if [ $stat_cookietx_last -ge $stat_cookietx_now ] ;then
 			extra+=" WARN: CookieSent: did not advance"

[PATCH 6.8.y 0/3] Backport "mptcp: don't account accept() of non-MPC client as fallback to TCP"

[Matthieu Baerts (NGI0)]

Commit 7a1b3490f47e ("mptcp: don't account accept() of non-MPC client as 
fallback to TCP") does not apply to the 6.8-stable tree. That's because 
there are some conflicts with recent refactoring done in the selftests:

- commit e3aae1098f10 ("selftests: mptcp: connect: fix shellcheck warnings")
- commit e7c42bf4d320 ("selftests: mptcp: use += operator to append strings")

These two patches look harmless, probably safer and easier to backport
them, than diverging even more from the development branch.

Note that all these three commits have been backported without 
conflicts.

Davide Caratti (1):
  mptcp: don't account accept() of non-MPC client as fallback to TCP

Geliang Tang (1):
  selftests: mptcp: use += operator to append strings

Matthieu Baerts (NGI0) (1):
  selftests: mptcp: connect: fix shellcheck warnings

 net/mptcp/protocol.c                          |   2 -
 net/mptcp/subflow.c                           |   2 +
 .../selftests/net/mptcp/mptcp_connect.sh      | 134 +++++++++++-------
 .../testing/selftests/net/mptcp/mptcp_join.sh |  30 ++--
 4 files changed, 99 insertions(+), 69 deletions(-)

-- 
2.43.0

[PATCH 6.8.y 1/3] selftests: mptcp: connect: fix shellcheck warnings

[Matthieu Baerts (NGI0)]

shellcheck recently helped to prevent issues. It is then good to fix the
other harmless issues in order to spot "real" ones later.

Here, two categories of warnings are now ignored:

- SC2317: Command appears to be unreachable. The cleanup() function is
  invoked indirectly via the EXIT trap.

- SC2086: Double quote to prevent globbing and word splitting. This is
  recommended, but the current usage is correct and there is no need to
  do all these modifications to be compliant with this rule.

For the modifications:

  - SC2034: ksft_skip appears unused.
  - SC2181: Check exit code directly with e.g. 'if mycmd;', not
            indirectly with $?.
  - SC2004: $/${} is unnecessary on arithmetic variables.
  - SC2155: Declare and assign separately to avoid masking return
            values.
  - SC2166: Prefer [ p ] && [ q ] as [ p -a q ] is not well defined.
  - SC2059: Don't use variables in the printf format string. Use printf
            '..%s..' "$foo".

Now this script is shellcheck (0.9.0) compliant. We can easily spot new
issues.

Reviewed-by: Mat Martineau <martineau@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://lore.kernel.org/r/20240306-upstream-net-next-20240304-selftests-mptcp-shared-code-shellcheck-v2-8-bc79e6e5e6a0@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
(cherry picked from commit e3aae1098f109f0bd33c971deff1926f4e4441d0)
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
---
 .../selftests/net/mptcp/mptcp_connect.sh      | 76 ++++++++++++-------
 1 file changed, 47 insertions(+), 29 deletions(-)

diff --git a/tools/testing/selftests/net/mptcp/mptcp_connect.sh b/tools/testing/selftests/net/mptcp/mptcp_connect.sh
index 7898d62fce0b..cce0e553976f 100755
--- a/tools/testing/selftests/net/mptcp/mptcp_connect.sh
+++ b/tools/testing/selftests/net/mptcp/mptcp_connect.sh
@@ -1,6 +1,11 @@
 #!/bin/bash
 # SPDX-License-Identifier: GPL-2.0
 
+# Double quotes to prevent globbing and word splitting is recommended in new
+# code but we accept it, especially because there were too many before having
+# address all other issues detected by shellcheck.
+#shellcheck disable=SC2086
+
 . "$(dirname "${0}")/mptcp_lib.sh"
 
 time_start=$(date +%s)
@@ -13,7 +18,6 @@ sout=""
 cin_disconnect=""
 cin=""
 cout=""
-ksft_skip=4
 capture=false
 timeout_poll=30
 timeout_test=$((timeout_poll * 2 + 1))
@@ -131,6 +135,8 @@ ns4="ns4-$rndh"
 TEST_COUNT=0
 TEST_GROUP=""
 
+# This function is used in the cleanup trap
+#shellcheck disable=SC2317
 cleanup()
 {
 	rm -f "$cin_disconnect" "$cout_disconnect"
@@ -225,8 +231,9 @@ set_ethtool_flags() {
 	local dev="$2"
 	local flags="$3"
 
-	ip netns exec $ns ethtool -K $dev $flags 2>/dev/null
-	[ $? -eq 0 ] && echo "INFO: set $ns dev $dev: ethtool -K $flags"
+	if ip netns exec $ns ethtool -K $dev $flags 2>/dev/null; then
+		echo "INFO: set $ns dev $dev: ethtool -K $flags"
+	fi
 }
 
 set_random_ethtool_flags() {
@@ -321,7 +328,7 @@ do_transfer()
 	local extra_args="$7"
 
 	local port
-	port=$((10000+$TEST_COUNT))
+	port=$((10000+TEST_COUNT))
 	TEST_COUNT=$((TEST_COUNT+1))
 
 	if [ "$rcvbuf" -gt 0 ]; then
@@ -378,12 +385,18 @@ do_transfer()
 			nstat -n
 	fi
 
-	local stat_synrx_last_l=$(mptcp_lib_get_counter "${listener_ns}" "MPTcpExtMPCapableSYNRX")
-	local stat_ackrx_last_l=$(mptcp_lib_get_counter "${listener_ns}" "MPTcpExtMPCapableACKRX")
-	local stat_cookietx_last=$(mptcp_lib_get_counter "${listener_ns}" "TcpExtSyncookiesSent")
-	local stat_cookierx_last=$(mptcp_lib_get_counter "${listener_ns}" "TcpExtSyncookiesRecv")
-	local stat_csum_err_s=$(mptcp_lib_get_counter "${listener_ns}" "MPTcpExtDataCsumErr")
-	local stat_csum_err_c=$(mptcp_lib_get_counter "${connector_ns}" "MPTcpExtDataCsumErr")
+	local stat_synrx_last_l
+	local stat_ackrx_last_l
+	local stat_cookietx_last
+	local stat_cookierx_last
+	local stat_csum_err_s
+	local stat_csum_err_c
+	stat_synrx_last_l=$(mptcp_lib_get_counter "${listener_ns}" "MPTcpExtMPCapableSYNRX")
+	stat_ackrx_last_l=$(mptcp_lib_get_counter "${listener_ns}" "MPTcpExtMPCapableACKRX")
+	stat_cookietx_last=$(mptcp_lib_get_counter "${listener_ns}" "TcpExtSyncookiesSent")
+	stat_cookierx_last=$(mptcp_lib_get_counter "${listener_ns}" "TcpExtSyncookiesRecv")
+	stat_csum_err_s=$(mptcp_lib_get_counter "${listener_ns}" "MPTcpExtDataCsumErr")
+	stat_csum_err_c=$(mptcp_lib_get_counter "${connector_ns}" "MPTcpExtDataCsumErr")
 
 	timeout ${timeout_test} \
 		ip netns exec ${listener_ns} \
@@ -446,11 +459,16 @@ do_transfer()
 	mptcp_lib_check_transfer $cin $sout "file received by server"
 	rets=$?
 
-	local stat_synrx_now_l=$(mptcp_lib_get_counter "${listener_ns}" "MPTcpExtMPCapableSYNRX")
-	local stat_ackrx_now_l=$(mptcp_lib_get_counter "${listener_ns}" "MPTcpExtMPCapableACKRX")
-	local stat_cookietx_now=$(mptcp_lib_get_counter "${listener_ns}" "TcpExtSyncookiesSent")
-	local stat_cookierx_now=$(mptcp_lib_get_counter "${listener_ns}" "TcpExtSyncookiesRecv")
-	local stat_ooo_now=$(mptcp_lib_get_counter "${listener_ns}" "TcpExtTCPOFOQueue")
+	local stat_synrx_now_l
+	local stat_ackrx_now_l
+	local stat_cookietx_now
+	local stat_cookierx_now
+	local stat_ooo_now
+	stat_synrx_now_l=$(mptcp_lib_get_counter "${listener_ns}" "MPTcpExtMPCapableSYNRX")
+	stat_ackrx_now_l=$(mptcp_lib_get_counter "${listener_ns}" "MPTcpExtMPCapableACKRX")
+	stat_cookietx_now=$(mptcp_lib_get_counter "${listener_ns}" "TcpExtSyncookiesSent")
+	stat_cookierx_now=$(mptcp_lib_get_counter "${listener_ns}" "TcpExtSyncookiesRecv")
+	stat_ooo_now=$(mptcp_lib_get_counter "${listener_ns}" "TcpExtTCPOFOQueue")
 
 	expect_synrx=$((stat_synrx_last_l))
 	expect_ackrx=$((stat_ackrx_last_l))
@@ -459,8 +477,8 @@ do_transfer()
 	cookies=${cookies##*=}
 
 	if [ ${cl_proto} = "MPTCP" ] && [ ${srv_proto} = "MPTCP" ]; then
-		expect_synrx=$((stat_synrx_last_l+$connect_per_transfer))
-		expect_ackrx=$((stat_ackrx_last_l+$connect_per_transfer))
+		expect_synrx=$((stat_synrx_last_l+connect_per_transfer))
+		expect_ackrx=$((stat_ackrx_last_l+connect_per_transfer))
 	fi
 
 	if [ ${stat_synrx_now_l} -lt ${expect_synrx} ]; then
@@ -468,7 +486,7 @@ do_transfer()
 			"${stat_synrx_now_l}" "${expect_synrx}" 1>&2
 		retc=1
 	fi
-	if [ ${stat_ackrx_now_l} -lt ${expect_ackrx} -a ${stat_ooo_now} -eq 0 ]; then
+	if [ ${stat_ackrx_now_l} -lt ${expect_ackrx} ] && [ ${stat_ooo_now} -eq 0 ]; then
 		if [ ${stat_ooo_now} -eq 0 ]; then
 			printf "[ FAIL ] lower MPC ACK rx (%d) than expected (%d)\n" \
 				"${stat_ackrx_now_l}" "${expect_ackrx}" 1>&2
@@ -479,18 +497,20 @@ do_transfer()
 	fi
 
 	if $checksum; then
-		local csum_err_s=$(mptcp_lib_get_counter "${listener_ns}" "MPTcpExtDataCsumErr")
-		local csum_err_c=$(mptcp_lib_get_counter "${connector_ns}" "MPTcpExtDataCsumErr")
+		local csum_err_s
+		local csum_err_c
+		csum_err_s=$(mptcp_lib_get_counter "${listener_ns}" "MPTcpExtDataCsumErr")
+		csum_err_c=$(mptcp_lib_get_counter "${connector_ns}" "MPTcpExtDataCsumErr")
 
 		local csum_err_s_nr=$((csum_err_s - stat_csum_err_s))
 		if [ $csum_err_s_nr -gt 0 ]; then
-			printf "[ FAIL ]\nserver got $csum_err_s_nr data checksum error[s]"
+			printf "[ FAIL ]\nserver got %d data checksum error[s]" ${csum_err_s_nr}
 			rets=1
 		fi
 
 		local csum_err_c_nr=$((csum_err_c - stat_csum_err_c))
 		if [ $csum_err_c_nr -gt 0 ]; then
-			printf "[ FAIL ]\nclient got $csum_err_c_nr data checksum error[s]"
+			printf "[ FAIL ]\nclient got %d data checksum error[s]" ${csum_err_c_nr}
 			retc=1
 		fi
 	fi
@@ -658,7 +678,7 @@ run_test_transparent()
 		return
 	fi
 
-ip netns exec "$listener_ns" nft -f /dev/stdin <<"EOF"
+	if ! ip netns exec "$listener_ns" nft -f /dev/stdin <<"EOF"
 flush ruleset
 table inet mangle {
 	chain divert {
@@ -669,7 +689,7 @@ table inet mangle {
 	}
 }
 EOF
-	if [ $? -ne 0 ]; then
+	then
 		echo "SKIP: $msg, could not load nft ruleset"
 		mptcp_lib_fail_if_expected_feature "nft rules"
 		mptcp_lib_result_skip "${TEST_GROUP}"
@@ -684,8 +704,7 @@ EOF
 		local_addr="0.0.0.0"
 	fi
 
-	ip -net "$listener_ns" $r6flag rule add fwmark 1 lookup 100
-	if [ $? -ne 0 ]; then
+	if ! ip -net "$listener_ns" $r6flag rule add fwmark 1 lookup 100; then
 		ip netns exec "$listener_ns" nft flush ruleset
 		echo "SKIP: $msg, ip $r6flag rule failed"
 		mptcp_lib_fail_if_expected_feature "ip rule"
@@ -693,8 +712,7 @@ EOF
 		return
 	fi
 
-	ip -net "$listener_ns" route add local $local_addr/0 dev lo table 100
-	if [ $? -ne 0 ]; then
+	if ! ip -net "$listener_ns" route add local $local_addr/0 dev lo table 100; then
 		ip netns exec "$listener_ns" nft flush ruleset
 		ip -net "$listener_ns" $r6flag rule del fwmark 1 lookup 100
 		echo "SKIP: $msg, ip route add local $local_addr failed"
@@ -857,7 +875,7 @@ stop_if_error "Could not even run ping tests"
 echo -n "INFO: Using loss of $tc_loss "
 test "$tc_delay" -gt 0 && echo -n "delay $tc_delay ms "
 
-reorder_delay=$(($tc_delay / 4))
+reorder_delay=$((tc_delay / 4))
 
 if [ -z "${tc_reorder}" ]; then
 	reorder1=$((RANDOM%10))
-- 
2.43.0

[PATCH 6.8.y 2/3] selftests: mptcp: use += operator to append strings

[Matthieu Baerts (NGI0)]

From: Geliang Tang <tanggeliang@kylinos.cn>

This patch uses addition assignment operator (+=) to append strings
instead of duplicating the variable name in mptcp_connect.sh and
mptcp_join.sh.

This can make the statements shorter.

Note: in mptcp_connect.sh, add a local variable extra in do_transfer to
save the various extra warning logs, using += to append it. And add a
new variable tc_info to save various tc info, also using += to append it.
This can make the code more readable and prepare for the next commit.

Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn>
Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://lore.kernel.org/r/20240308-upstream-net-next-20240308-selftests-mptcp-unification-v1-8-4f42c347b653@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
(cherry picked from commit e7c42bf4d320affe37337aa83ae0347832b3f568)
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
---
 .../selftests/net/mptcp/mptcp_connect.sh      | 53 ++++++++++---------
 .../testing/selftests/net/mptcp/mptcp_join.sh | 30 +++++------
 2 files changed, 43 insertions(+), 40 deletions(-)

diff --git a/tools/testing/selftests/net/mptcp/mptcp_connect.sh b/tools/testing/selftests/net/mptcp/mptcp_connect.sh
index cce0e553976f..f8e1b3daa748 100755
--- a/tools/testing/selftests/net/mptcp/mptcp_connect.sh
+++ b/tools/testing/selftests/net/mptcp/mptcp_connect.sh
@@ -332,15 +332,15 @@ do_transfer()
 	TEST_COUNT=$((TEST_COUNT+1))
 
 	if [ "$rcvbuf" -gt 0 ]; then
-		extra_args="$extra_args -R $rcvbuf"
+		extra_args+=" -R $rcvbuf"
 	fi
 
 	if [ "$sndbuf" -gt 0 ]; then
-		extra_args="$extra_args -S $sndbuf"
+		extra_args+=" -S $sndbuf"
 	fi
 
 	if [ -n "$testmode" ]; then
-		extra_args="$extra_args -m $testmode"
+		extra_args+=" -m $testmode"
 	fi
 
 	if [ -n "$extra_args" ] && $options_log; then
@@ -459,6 +459,7 @@ do_transfer()
 	mptcp_lib_check_transfer $cin $sout "file received by server"
 	rets=$?
 
+	local extra=""
 	local stat_synrx_now_l
 	local stat_ackrx_now_l
 	local stat_cookietx_now
@@ -492,7 +493,7 @@ do_transfer()
 				"${stat_ackrx_now_l}" "${expect_ackrx}" 1>&2
 			rets=1
 		else
-			printf "[ Note ] fallback due to TCP OoO"
+			extra+=" [ Note ] fallback due to TCP OoO"
 		fi
 	fi
 
@@ -515,39 +516,41 @@ do_transfer()
 		fi
 	fi
 
-	if [ $retc -eq 0 ] && [ $rets -eq 0 ]; then
-		printf "[ OK ]"
-		mptcp_lib_result_pass "${TEST_GROUP}: ${result_msg}"
-	else
-		mptcp_lib_result_fail "${TEST_GROUP}: ${result_msg}"
-	fi
-
 	if [ $cookies -eq 2 ];then
 		if [ $stat_cookietx_last -ge $stat_cookietx_now ] ;then
-			printf " WARN: CookieSent: did not advance"
+			extra+=" WARN: CookieSent: did not advance"
 		fi
 		if [ $stat_cookierx_last -ge $stat_cookierx_now ] ;then
-			printf " WARN: CookieRecv: did not advance"
+			extra+=" WARN: CookieRecv: did not advance"
 		fi
 	else
 		if [ $stat_cookietx_last -ne $stat_cookietx_now ] ;then
-			printf " WARN: CookieSent: changed"
+			extra+=" WARN: CookieSent: changed"
 		fi
 		if [ $stat_cookierx_last -ne $stat_cookierx_now ] ;then
-			printf " WARN: CookieRecv: changed"
+			extra+=" WARN: CookieRecv: changed"
 		fi
 	fi
 
 	if [ ${stat_synrx_now_l} -gt ${expect_synrx} ]; then
-		printf " WARN: SYNRX: expect %d, got %d (probably retransmissions)" \
-			"${expect_synrx}" "${stat_synrx_now_l}"
+		extra+=" WARN: SYNRX: expect ${expect_synrx},"
+		extra+=" got ${stat_synrx_now_l} (probably retransmissions)"
 	fi
 	if [ ${stat_ackrx_now_l} -gt ${expect_ackrx} ]; then
-		printf " WARN: ACKRX: expect %d, got %d (probably retransmissions)" \
-			"${expect_ackrx}" "${stat_ackrx_now_l}"
+		extra+=" WARN: ACKRX: expect ${expect_ackrx},"
+		extra+=" got ${stat_ackrx_now_l} (probably retransmissions)"
+	fi
+
+	if [ $retc -eq 0 ] && [ $rets -eq 0 ]; then
+		printf "[ OK ]%s\n" "${extra:1}"
+		mptcp_lib_result_pass "${TEST_GROUP}: ${result_msg}"
+	else
+		if [ -n "${extra}" ]; then
+			printf "%s\n" "${extra:1}"
+		fi
+		mptcp_lib_result_fail "${TEST_GROUP}: ${result_msg}"
 	fi
 
-	echo
 	cat "$capout"
 	[ $retc -eq 0 ] && [ $rets -eq 0 ]
 }
@@ -872,8 +875,8 @@ mptcp_lib_result_code "${ret}" "ping tests"
 stop_if_error "Could not even run ping tests"
 
 [ -n "$tc_loss" ] && tc -net "$ns2" qdisc add dev ns2eth3 root netem loss random $tc_loss delay ${tc_delay}ms
-echo -n "INFO: Using loss of $tc_loss "
-test "$tc_delay" -gt 0 && echo -n "delay $tc_delay ms "
+tc_info="loss of $tc_loss "
+test "$tc_delay" -gt 0 && tc_info+="delay $tc_delay ms "
 
 reorder_delay=$((tc_delay / 4))
 
@@ -884,17 +887,17 @@ if [ -z "${tc_reorder}" ]; then
 
 	if [ $reorder_delay -gt 0 ] && [ $reorder1 -lt 100 ] && [ $reorder2 -gt 0 ]; then
 		tc_reorder="reorder ${reorder1}% ${reorder2}%"
-		echo -n "$tc_reorder with delay ${reorder_delay}ms "
+		tc_info+="$tc_reorder with delay ${reorder_delay}ms "
 	fi
 elif [ "$tc_reorder" = "0" ];then
 	tc_reorder=""
 elif [ "$reorder_delay" -gt 0 ];then
 	# reordering requires some delay
 	tc_reorder="reorder $tc_reorder"
-	echo -n "$tc_reorder with delay ${reorder_delay}ms "
+	tc_info+="$tc_reorder with delay ${reorder_delay}ms "
 fi
 
-echo "on ns3eth4"
+echo "INFO: Using ${tc_info}on ns3eth4"
 
 tc -net "$ns3" qdisc add dev ns3eth4 root netem delay ${reorder_delay}ms $tc_reorder
 
diff --git a/tools/testing/selftests/net/mptcp/mptcp_join.sh b/tools/testing/selftests/net/mptcp/mptcp_join.sh
index e4581b0dfb96..df7521aa274b 100755
--- a/tools/testing/selftests/net/mptcp/mptcp_join.sh
+++ b/tools/testing/selftests/net/mptcp/mptcp_join.sh
@@ -799,18 +799,18 @@ pm_nl_check_endpoint()
 		line="${line% }"
 		# the dump order is: address id flags port dev
 		[ -n "$addr" ] && expected_line="$addr"
-		expected_line="$expected_line $id"
-		[ -n "$_flags" ] && expected_line="$expected_line ${_flags//","/" "}"
-		[ -n "$dev" ] && expected_line="$expected_line $dev"
-		[ -n "$port" ] && expected_line="$expected_line $port"
+		expected_line+=" $id"
+		[ -n "$_flags" ] && expected_line+=" ${_flags//","/" "}"
+		[ -n "$dev" ] && expected_line+=" $dev"
+		[ -n "$port" ] && expected_line+=" $port"
 	else
 		line=$(ip netns exec $ns ./pm_nl_ctl get $_id)
 		# the dump order is: id flags dev address port
 		expected_line="$id"
-		[ -n "$flags" ] && expected_line="$expected_line $flags"
-		[ -n "$dev" ] && expected_line="$expected_line $dev"
-		[ -n "$addr" ] && expected_line="$expected_line $addr"
-		[ -n "$_port" ] && expected_line="$expected_line $_port"
+		[ -n "$flags" ] && expected_line+=" $flags"
+		[ -n "$dev" ] && expected_line+=" $dev"
+		[ -n "$addr" ] && expected_line+=" $addr"
+		[ -n "$_port" ] && expected_line+=" $_port"
 	fi
 	if [ "$line" = "$expected_line" ]; then
 		print_ok
@@ -1261,7 +1261,7 @@ chk_csum_nr()
 	print_check "sum"
 	count=$(mptcp_lib_get_counter ${ns1} "MPTcpExtDataCsumErr")
 	if [ "$count" != "$csum_ns1" ]; then
-		extra_msg="$extra_msg ns1=$count"
+		extra_msg+=" ns1=$count"
 	fi
 	if [ -z "$count" ]; then
 		print_skip
@@ -1274,7 +1274,7 @@ chk_csum_nr()
 	print_check "csum"
 	count=$(mptcp_lib_get_counter ${ns2} "MPTcpExtDataCsumErr")
 	if [ "$count" != "$csum_ns2" ]; then
-		extra_msg="$extra_msg ns2=$count"
+		extra_msg+=" ns2=$count"
 	fi
 	if [ -z "$count" ]; then
 		print_skip
@@ -1318,7 +1318,7 @@ chk_fail_nr()
 	print_check "ftx"
 	count=$(mptcp_lib_get_counter ${ns_tx} "MPTcpExtMPFailTx")
 	if [ "$count" != "$fail_tx" ]; then
-		extra_msg="$extra_msg,tx=$count"
+		extra_msg+=",tx=$count"
 	fi
 	if [ -z "$count" ]; then
 		print_skip
@@ -1332,7 +1332,7 @@ chk_fail_nr()
 	print_check "failrx"
 	count=$(mptcp_lib_get_counter ${ns_rx} "MPTcpExtMPFailRx")
 	if [ "$count" != "$fail_rx" ]; then
-		extra_msg="$extra_msg,rx=$count"
+		extra_msg+=",rx=$count"
 	fi
 	if [ -z "$count" ]; then
 		print_skip
@@ -1367,7 +1367,7 @@ chk_fclose_nr()
 	if [ -z "$count" ]; then
 		print_skip
 	elif [ "$count" != "$fclose_tx" ]; then
-		extra_msg="$extra_msg,tx=$count"
+		extra_msg+=",tx=$count"
 		fail_test "got $count MP_FASTCLOSE[s] TX expected $fclose_tx"
 	else
 		print_ok
@@ -1378,7 +1378,7 @@ chk_fclose_nr()
 	if [ -z "$count" ]; then
 		print_skip
 	elif [ "$count" != "$fclose_rx" ]; then
-		extra_msg="$extra_msg,rx=$count"
+		extra_msg+=",rx=$count"
 		fail_test "got $count MP_FASTCLOSE[s] RX expected $fclose_rx"
 	else
 		print_ok
@@ -1747,7 +1747,7 @@ chk_rm_nr()
 		count=$((count + cnt))
 		if [ "$count" != "$rm_subflow_nr" ]; then
 			suffix="$count in [$rm_subflow_nr:$((rm_subflow_nr*2))]"
-			extra_msg="$extra_msg simult"
+			extra_msg+=" simult"
 		fi
 		if [ $count -ge "$rm_subflow_nr" ] && \
 		   [ "$count" -le "$((rm_subflow_nr *2 ))" ]; then
-- 
2.43.0

[PATCH 6.8.y 3/3] mptcp: don't account accept() of non-MPC client as fallback to TCP

[Matthieu Baerts (NGI0)]

From: Davide Caratti <dcaratti@redhat.com>

Current MPTCP servers increment MPTcpExtMPCapableFallbackACK when they
accept non-MPC connections. As reported by Christoph, this is "surprising"
because the counter might become greater than MPTcpExtMPCapableSYNRX.

MPTcpExtMPCapableFallbackACK counter's name suggests it should only be
incremented when a connection was seen using MPTCP options, then a
fallback to TCP has been done. Let's do that by incrementing it when
the subflow context of an inbound MPC connection attempt is dropped.
Also, update mptcp_connect.sh kselftest, to ensure that the
above MIB does not increment in case a pure TCP client connects to a
MPTCP server.

Fixes: fc518953bc9c ("mptcp: add and use MIB counter infrastructure")
Cc: stable@vger.kernel.org
Reported-by: Christoph Paasch <cpaasch@apple.com>
Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/449
Signed-off-by: Davide Caratti <dcaratti@redhat.com>
Reviewed-by: Mat Martineau <martineau@kernel.org>
Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://lore.kernel.org/r/20240329-upstream-net-20240329-fallback-mib-v1-1-324a8981da48@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
(cherry picked from commit 7a1b3490f47e88ec4cbde65f1a77a0f4bc972282)
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
---
 net/mptcp/protocol.c                               | 2 --
 net/mptcp/subflow.c                                | 2 ++
 tools/testing/selftests/net/mptcp/mptcp_connect.sh | 9 +++++++++
 3 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index 7833a49f6214..2b921af2718d 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -3916,8 +3916,6 @@ static int mptcp_stream_accept(struct socket *sock, struct socket *newsock,
 				mptcp_set_state(newsk, TCP_CLOSE);
 		}
 	} else {
-		MPTCP_INC_STATS(sock_net(ssk),
-				MPTCP_MIB_MPCAPABLEPASSIVEFALLBACK);
 tcpfallback:
 		newsk->sk_kern_sock = kern;
 		lock_sock(newsk);
diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c
index 71ba86246ff8..13f66d11b7a0 100644
--- a/net/mptcp/subflow.c
+++ b/net/mptcp/subflow.c
@@ -905,6 +905,8 @@ static struct sock *subflow_syn_recv_sock(const struct sock *sk,
 	return child;
 
 fallback:
+	if (fallback)
+		SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_MPCAPABLEPASSIVEFALLBACK);
 	mptcp_subflow_drop_ctx(child);
 	return child;
 }
diff --git a/tools/testing/selftests/net/mptcp/mptcp_connect.sh b/tools/testing/selftests/net/mptcp/mptcp_connect.sh
index f8e1b3daa748..713de8182222 100755
--- a/tools/testing/selftests/net/mptcp/mptcp_connect.sh
+++ b/tools/testing/selftests/net/mptcp/mptcp_connect.sh
@@ -391,12 +391,14 @@ do_transfer()
 	local stat_cookierx_last
 	local stat_csum_err_s
 	local stat_csum_err_c
+	local stat_tcpfb_last_l
 	stat_synrx_last_l=$(mptcp_lib_get_counter "${listener_ns}" "MPTcpExtMPCapableSYNRX")
 	stat_ackrx_last_l=$(mptcp_lib_get_counter "${listener_ns}" "MPTcpExtMPCapableACKRX")
 	stat_cookietx_last=$(mptcp_lib_get_counter "${listener_ns}" "TcpExtSyncookiesSent")
 	stat_cookierx_last=$(mptcp_lib_get_counter "${listener_ns}" "TcpExtSyncookiesRecv")
 	stat_csum_err_s=$(mptcp_lib_get_counter "${listener_ns}" "MPTcpExtDataCsumErr")
 	stat_csum_err_c=$(mptcp_lib_get_counter "${connector_ns}" "MPTcpExtDataCsumErr")
+	stat_tcpfb_last_l=$(mptcp_lib_get_counter "${listener_ns}" "MPTcpExtMPCapableFallbackACK")
 
 	timeout ${timeout_test} \
 		ip netns exec ${listener_ns} \
@@ -465,11 +467,13 @@ do_transfer()
 	local stat_cookietx_now
 	local stat_cookierx_now
 	local stat_ooo_now
+	local stat_tcpfb_now_l
 	stat_synrx_now_l=$(mptcp_lib_get_counter "${listener_ns}" "MPTcpExtMPCapableSYNRX")
 	stat_ackrx_now_l=$(mptcp_lib_get_counter "${listener_ns}" "MPTcpExtMPCapableACKRX")
 	stat_cookietx_now=$(mptcp_lib_get_counter "${listener_ns}" "TcpExtSyncookiesSent")
 	stat_cookierx_now=$(mptcp_lib_get_counter "${listener_ns}" "TcpExtSyncookiesRecv")
 	stat_ooo_now=$(mptcp_lib_get_counter "${listener_ns}" "TcpExtTCPOFOQueue")
+	stat_tcpfb_now_l=$(mptcp_lib_get_counter "${listener_ns}" "MPTcpExtMPCapableFallbackACK")
 
 	expect_synrx=$((stat_synrx_last_l))
 	expect_ackrx=$((stat_ackrx_last_l))
@@ -516,6 +520,11 @@ do_transfer()
 		fi
 	fi
 
+	if [ ${stat_ooo_now} -eq 0 ] && [ ${stat_tcpfb_last_l} -ne ${stat_tcpfb_now_l} ]; then
+		mptcp_lib_pr_fail "unexpected fallback to TCP"
+		rets=1
+	fi
+
 	if [ $cookies -eq 2 ];then
 		if [ $stat_cookietx_last -ge $stat_cookietx_now ] ;then
 			extra+=" WARN: CookieSent: did not advance"
-- 
2.43.0