From: Davide Caratti dcaratti@redhat.com
[ 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/33dc43f587ec1388ba456b4915c75f02a8aae226.1663... [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@redhat.com CC: Xin Long lucien.xin@gmail.com Signed-off-by: Davide Caratti dcaratti@redhat.com Reviewed-by: Marcelo Ricardo Leitner marcelo.leitner@gmail.com Acked-by: Jamal Hadi Salim jhs@mojatatu.com Signed-off-by: Paolo Abeni pabeni@redhat.com [DP: adjusted context for linux-5.10.y] Signed-off-by: Dragos-Marian Panait dragos.panait@windriver.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- 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]}