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Merge branch 'net-sched-use-the-backlog-for-nested-mirred-ingress'

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Davide Caratti says:

====================
net/sched: use the backlog for nested mirred ingress

TC mirred has a protection against excessive stack growth, but that
protection doesn't really guarantee the absence of recursion, nor
it guards against loops. Patch 1/2 rewords "recursion" to "nesting" to
make this more clear.
We can leverage on this existing mechanism to prevent TCP / SCTP from doing
soft lock-up in some specific scenarios that uses mirred egress->ingress:
patch 2 changes mirred so that the networking backlog is used for nested
mirred ingress actions.
====================

Link: https://lore.kernel.org/r/cover.1674233458.git.dcaratti@redhat.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
This commit is contained in:
Paolo Abeni 2023-01-24 10:30:56 +01:00
commit d961bee454
2 changed files with 63 additions and 9 deletions
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23
net/sched/act_mirred.c
View File

@ -29,8 +29,8 @@
static LIST_HEAD(mirred_list);
static DEFINE_SPINLOCK(mirred_list_lock);
#define MIRRED_RECURSION_LIMIT 4
static DEFINE_PER_CPU(unsigned int, mirred_rec_level);
#define MIRRED_NEST_LIMIT 4
static DEFINE_PER_CPU(unsigned int, mirred_nest_level);
static bool tcf_mirred_is_act_redirect(int action)
{
@ -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 = tcf_dev_queue_xmit(skb, dev_queue_xmit);
else if (is_mirred_nested())
err = netif_rx(skb);
else
err = netif_receive_skb(skb);
@ -226,7 +233,7 @@ TC_INDIRECT_SCOPE int tcf_mirred_act(struct sk_buff *skb,
struct sk_buff *skb2 = skb;
bool m_mac_header_xmit;
struct net_device *dev;
unsigned int rec_level;
unsigned int nest_level;
int retval, err = 0;
bool use_reinsert;
bool want_ingress;
@ -237,11 +244,11 @@ TC_INDIRECT_SCOPE int tcf_mirred_act(struct sk_buff *skb,
int mac_len;
bool at_nh;
rec_level = __this_cpu_inc_return(mirred_rec_level);
if (unlikely(rec_level > MIRRED_RECURSION_LIMIT)) {
nest_level = __this_cpu_inc_return(mirred_nest_level);
if (unlikely(nest_level > MIRRED_NEST_LIMIT)) {
net_warn_ratelimited("Packet exceeded mirred recursion limit on dev %s\n",
netdev_name(skb->dev));
__this_cpu_dec(mirred_rec_level);
__this_cpu_dec(mirred_nest_level);
return TC_ACT_SHOT;
}
@ -310,7 +317,7 @@ TC_INDIRECT_SCOPE int tcf_mirred_act(struct sk_buff *skb,
err = tcf_mirred_forward(want_ingress, skb);
if (err)
tcf_action_inc_overlimit_qstats(&m->common);
__this_cpu_dec(mirred_rec_level);
__this_cpu_dec(mirred_nest_level);
return TC_ACT_CONSUMED;
}
}
@ -322,7 +329,7 @@ out:
if (tcf_mirred_is_act_redirect(m_eaction))
retval = TC_ACT_SHOT;
}
__this_cpu_dec(mirred_rec_level);
__this_cpu_dec(mirred_nest_level);
return retval;
}

49
tools/testing/selftests/net/forwarding/tc_actions.sh
View File

@ -3,7 +3,8 @@
ALL_TESTS="gact_drop_and_ok_test mirred_egress_redirect_test \
mirred_egress_mirror_test matchall_mirred_egress_mirror_test \
gact_trap_test mirred_egress_to_ingress_test"
gact_trap_test mirred_egress_to_ingress_test \
mirred_egress_to_ingress_tcp_test"
NUM_NETIFS=4
source tc_common.sh
source lib.sh
@ -198,6 +199,52 @@ mirred_egress_to_ingress_test()
log_test "mirred_egress_to_ingress ($tcflags)"
}
mirred_egress_to_ingress_tcp_test()
{
local tmpfile=$(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]}