This is a note to let you know that I've just added the patch titled
act_mirred: use the backlog for nested calls to mirred ingress
to the 5.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
act_mirred-use-the-backlog-for-nested-calls-to-mirred-ingress.patch
and it can be found in the queue-5.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From stable-owner@xxxxxxxxxxxxxxx Tue May 16 20:01:54 2023
From: Dragos-Marian Panait <dragos.panait@xxxxxxxxxxxxx>
Date: Tue, 16 May 2023 22:00:40 +0300
Subject: act_mirred: use the backlog for nested calls to mirred ingress
To: stable@xxxxxxxxxxxxxxx
Cc: wenxu <wenxu@xxxxxxxxx>, Jakub Kicinski <kuba@xxxxxxxxxx>, Jamal Hadi Salim <jhs@xxxxxxxxxxxx>, Davide Caratti <dcaratti@xxxxxxxxxx>, Marcelo Ricardo Leitner <marcelo.leitner@xxxxxxxxx>, Paolo Abeni <pabeni@xxxxxxxxxx>, William Zhao <wizhao@xxxxxxxxxx>, Xin Long <lucien.xin@xxxxxxxxx>, "David S . Miller" <davem@xxxxxxxxxxxxx>, Eric Dumazet <edumazet@xxxxxxxxxx>, Cong Wang <xiyou.wangcong@xxxxxxxxx>, Jiri Pirko <jiri@xxxxxxxxxxx>, Shuah Khan <shuah@xxxxxxxxxx>, linux-kselftest@xxxxxxxxxxxxxxx, netdev@xxxxxxxxxxxxxxx
Message-ID: <20230516190040.636627-4-dragos.panait@xxxxxxxxxxxxx>
From: Davide Caratti <dcaratti@xxxxxxxxxx>
[ Upstream commit ca22da2fbd693b54dc8e3b7b54ccc9f7e9ba3640 ]
William reports kernel soft-lockups on some OVS topologies when TC mirred
egress->ingress action is hit by local TCP traffic [1].
The same can also be reproduced with SCTP (thanks Xin for verifying), when
client and server reach themselves through mirred egress to ingress, and
one of the two peers sends a "heartbeat" packet (from within a timer).
Enqueueing to backlog proved to fix this soft lockup; however, as Cong
noticed [2], we should preserve - when possible - the current mirred
behavior that counts as "overlimits" any eventual packet drop subsequent to
the mirred forwarding action [3]. A compromise solution might use the
backlog only when tcf_mirred_act() has a nest level greater than one:
change tcf_mirred_forward() accordingly.
Also, add a kselftest that can reproduce the lockup and verifies TC mirred
ability to account for further packet drops after TC mirred egress->ingress
(when the nest level is 1).
[1] https://lore.kernel.org/netdev/33dc43f587ec1388ba456b4915c75f02a8aae226.1663945716.git.dcaratti@xxxxxxxxxx/
[2] https://lore.kernel.org/netdev/Y0w%2FWWY60gqrtGLp@pop-os.localdomain/
[3] such behavior is not guaranteed: for example, if RPS or skb RX
timestamping is enabled on the mirred target device, the kernel
can defer receiving the skb and return NET_RX_SUCCESS inside
tcf_mirred_forward().
Reported-by: William Zhao <wizhao@xxxxxxxxxx>
CC: Xin Long <lucien.xin@xxxxxxxxx>
Signed-off-by: Davide Caratti <dcaratti@xxxxxxxxxx>
Reviewed-by: Marcelo Ricardo Leitner <marcelo.leitner@xxxxxxxxx>
Acked-by: Jamal Hadi Salim <jhs@xxxxxxxxxxxx>
Signed-off-by: Paolo Abeni <pabeni@xxxxxxxxxx>
[DP: adjusted context for linux-5.10.y]
Signed-off-by: Dragos-Marian Panait <dragos.panait@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/sched/act_mirred.c | 7 ++
tools/testing/selftests/net/forwarding/tc_actions.sh | 48 ++++++++++++++++++-
2 files changed, 54 insertions(+), 1 deletion(-)
--- a/net/sched/act_mirred.c
+++ b/net/sched/act_mirred.c
@@ -206,12 +206,19 @@ release_idr:
return err;
}
+static bool is_mirred_nested(void)
+{
+ return unlikely(__this_cpu_read(mirred_nest_level) > 1);
+}
+
static int tcf_mirred_forward(bool want_ingress, struct sk_buff *skb)
{
int err;
if (!want_ingress)
err = dev_queue_xmit(skb);
+ else if (is_mirred_nested())
+ err = netif_rx(skb);
else
err = netif_receive_skb(skb);
--- a/tools/testing/selftests/net/forwarding/tc_actions.sh
+++ b/tools/testing/selftests/net/forwarding/tc_actions.sh
@@ -3,7 +3,7 @@
ALL_TESTS="gact_drop_and_ok_test mirred_egress_redirect_test \
mirred_egress_mirror_test matchall_mirred_egress_mirror_test \
- gact_trap_test"
+ gact_trap_test mirred_egress_to_ingress_tcp_test"
NUM_NETIFS=4
source tc_common.sh
source lib.sh
@@ -153,6 +153,52 @@ gact_trap_test()
log_test "trap ($tcflags)"
}
+mirred_egress_to_ingress_tcp_test()
+{
+ local tmpfile=$(mktemp) tmpfile1=$(mktemp)
+
+ RET=0
+ dd conv=sparse status=none if=/dev/zero bs=1M count=2 of=$tmpfile
+ tc filter add dev $h1 protocol ip pref 100 handle 100 egress flower \
+ $tcflags ip_proto tcp src_ip 192.0.2.1 dst_ip 192.0.2.2 \
+ action ct commit nat src addr 192.0.2.2 pipe \
+ action ct clear pipe \
+ action ct commit nat dst addr 192.0.2.1 pipe \
+ action ct clear pipe \
+ action skbedit ptype host pipe \
+ action mirred ingress redirect dev $h1
+ tc filter add dev $h1 protocol ip pref 101 handle 101 egress flower \
+ $tcflags ip_proto icmp \
+ action mirred ingress redirect dev $h1
+ tc filter add dev $h1 protocol ip pref 102 handle 102 ingress flower \
+ ip_proto icmp \
+ action drop
+
+ ip vrf exec v$h1 nc --recv-only -w10 -l -p 12345 -o $tmpfile1 &
+ local rpid=$!
+ ip vrf exec v$h1 nc -w1 --send-only 192.0.2.2 12345 <$tmpfile
+ wait -n $rpid
+ cmp -s $tmpfile $tmpfile1
+ check_err $? "server output check failed"
+
+ $MZ $h1 -c 10 -p 64 -a $h1mac -b $h1mac -A 192.0.2.1 -B 192.0.2.1 \
+ -t icmp "ping,id=42,seq=5" -q
+ tc_check_packets "dev $h1 egress" 101 10
+ check_err $? "didn't mirred redirect ICMP"
+ tc_check_packets "dev $h1 ingress" 102 10
+ check_err $? "didn't drop mirred ICMP"
+ local overlimits=$(tc_rule_stats_get ${h1} 101 egress .overlimits)
+ test ${overlimits} = 10
+ check_err $? "wrong overlimits, expected 10 got ${overlimits}"
+
+ tc filter del dev $h1 egress protocol ip pref 100 handle 100 flower
+ tc filter del dev $h1 egress protocol ip pref 101 handle 101 flower
+ tc filter del dev $h1 ingress protocol ip pref 102 handle 102 flower
+
+ rm -f $tmpfile $tmpfile1
+ log_test "mirred_egress_to_ingress_tcp ($tcflags)"
+}
+
setup_prepare()
{
h1=${NETIFS[p1]}
Patches currently in stable-queue which might be from stable-owner@xxxxxxxxxxxxxxx are
queue-5.10/act_mirred-use-the-backlog-for-nested-calls-to-mirred-ingress.patch
queue-5.10/net-sched-act_mirred-better-wording-on-protection-against-excessive-stack-growth.patch
queue-5.10/net-sched-act_mirred-refactor-the-handle-of-xmit.patch
