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Michal Kubecek |
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From: Davide Caratti <dcaratti@redhat.com>
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Michal Kubecek |
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Date: Fri, 20 Jan 2023 18:01:40 +0100
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Michal Kubecek |
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Subject: act_mirred: use the backlog for nested calls to mirred ingress
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Michal Kubecek |
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Patch-mainline: v6.3-rc1
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Michal Kubecek |
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Git-commit: ca22da2fbd693b54dc8e3b7b54ccc9f7e9ba3640
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Michal Kubecek |
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References: CVE-2022-4269 bsc#1206024
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Michal Kubecek |
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Michal Kubecek |
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William reports kernel soft-lockups on some OVS topologies when TC mirred
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Michal Kubecek |
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egress->ingress action is hit by local TCP traffic [1].
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Michal Kubecek |
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The same can also be reproduced with SCTP (thanks Xin for verifying), when
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Michal Kubecek |
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client and server reach themselves through mirred egress to ingress, and
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Michal Kubecek |
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one of the two peers sends a "heartbeat" packet (from within a timer).
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Michal Kubecek |
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Michal Kubecek |
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Enqueueing to backlog proved to fix this soft lockup; however, as Cong
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Michal Kubecek |
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noticed [2], we should preserve - when possible - the current mirred
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Michal Kubecek |
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behavior that counts as "overlimits" any eventual packet drop subsequent to
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Michal Kubecek |
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the mirred forwarding action [3]. A compromise solution might use the
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Michal Kubecek |
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backlog only when tcf_mirred_act() has a nest level greater than one:
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Michal Kubecek |
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change tcf_mirred_forward() accordingly.
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Michal Kubecek |
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Michal Kubecek |
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Also, add a kselftest that can reproduce the lockup and verifies TC mirred
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Michal Kubecek |
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ability to account for further packet drops after TC mirred egress->ingress
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Michal Kubecek |
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(when the nest level is 1).
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Michal Kubecek |
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Michal Kubecek |
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[1] https://lore.kernel.org/netdev/33dc43f587ec1388ba456b4915c75f02a8aae226.1663945716.git.dcaratti@redhat.com/
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Michal Kubecek |
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[2] https://lore.kernel.org/netdev/Y0w%2FWWY60gqrtGLp@pop-os.localdomain/
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Michal Kubecek |
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[3] such behavior is not guaranteed: for example, if RPS or skb RX
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Michal Kubecek |
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timestamping is enabled on the mirred target device, the kernel
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Michal Kubecek |
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can defer receiving the skb and return NET_RX_SUCCESS inside
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Michal Kubecek |
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tcf_mirred_forward().
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Michal Kubecek |
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Michal Kubecek |
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Reported-by: William Zhao <wizhao@redhat.com>
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Michal Kubecek |
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CC: Xin Long <lucien.xin@gmail.com>
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Michal Kubecek |
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Signed-off-by: Davide Caratti <dcaratti@redhat.com>
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Michal Kubecek |
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Reviewed-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
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Michal Kubecek |
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Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>
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Michal Kubecek |
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Signed-off-by: Paolo Abeni <pabeni@redhat.com>
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Michal Kubecek |
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Acked-by: Michal Kubecek <mkubecek@suse.cz>
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Michal Kubecek |
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Michal Kubecek |
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---
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Michal Kubecek |
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net/sched/act_mirred.c | 7 +++
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Michal Kubecek |
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.../selftests/net/forwarding/tc_actions.sh | 49 ++++++++++++++++++-
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Michal Kubecek |
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2 files changed, 55 insertions(+), 1 deletion(-)
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Michal Kubecek |
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Michal Kubecek |
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--- a/net/sched/act_mirred.c
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Michal Kubecek |
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+++ b/net/sched/act_mirred.c
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Michal Kubecek |
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@@ -207,12 +207,19 @@ static int tcf_mirred_init(struct net *net, struct nlattr *nla,
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Michal Kubecek |
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return err;
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Michal Kubecek |
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}
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Michal Kubecek |
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Michal Kubecek |
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+static bool is_mirred_nested(void)
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Michal Kubecek |
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+{
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Michal Kubecek |
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+ return unlikely(__this_cpu_read(mirred_nest_level) > 1);
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Michal Kubecek |
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+}
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Michal Kubecek |
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+
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Michal Kubecek |
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static int tcf_mirred_forward(bool want_ingress, struct sk_buff *skb)
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Michal Kubecek |
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{
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Michal Kubecek |
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int err;
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Michal Kubecek |
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Michal Kubecek |
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if (!want_ingress)
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Michal Kubecek |
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err = dev_queue_xmit(skb);
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Michal Kubecek |
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+ else if (is_mirred_nested())
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Michal Kubecek |
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+ err = netif_rx(skb);
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Michal Kubecek |
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else
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Michal Kubecek |
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err = netif_receive_skb(skb);
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Michal Kubecek |
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Michal Kubecek |
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--- a/tools/testing/selftests/net/forwarding/tc_actions.sh
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Michal Kubecek |
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+++ b/tools/testing/selftests/net/forwarding/tc_actions.sh
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Michal Kubecek |
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@@ -2,7 +2,8 @@
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Michal Kubecek |
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# SPDX-License-Identifier: GPL-2.0
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Michal Kubecek |
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Michal Kubecek |
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ALL_TESTS="gact_drop_and_ok_test mirred_egress_redirect_test \
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Michal Kubecek |
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- mirred_egress_mirror_test gact_trap_test"
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Michal Kubecek |
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+ mirred_egress_mirror_test gact_trap_test \
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Michal Kubecek |
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+ mirred_egress_to_ingress_tcp_test"
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Michal Kubecek |
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NUM_NETIFS=4
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Michal Kubecek |
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source tc_common.sh
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Michal Kubecek |
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source lib.sh
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Michal Kubecek |
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@@ -148,6 +149,52 @@ gact_trap_test()
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Michal Kubecek |
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log_test "trap ($tcflags)"
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Michal Kubecek |
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}
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Michal Kubecek |
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Michal Kubecek |
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+mirred_egress_to_ingress_tcp_test()
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Michal Kubecek |
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+{
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Michal Kubecek |
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+ local tmpfile=$(mktemp) tmpfile1=$(mktemp)
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Michal Kubecek |
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+
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Michal Kubecek |
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+ RET=0
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Michal Kubecek |
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+ dd conv=sparse status=none if=/dev/zero bs=1M count=2 of=$tmpfile
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Michal Kubecek |
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+ tc filter add dev $h1 protocol ip pref 100 handle 100 egress flower \
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Michal Kubecek |
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+ $tcflags ip_proto tcp src_ip 192.0.2.1 dst_ip 192.0.2.2 \
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Michal Kubecek |
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+ action ct commit nat src addr 192.0.2.2 pipe \
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Michal Kubecek |
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+ action ct clear pipe \
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Michal Kubecek |
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+ action ct commit nat dst addr 192.0.2.1 pipe \
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Michal Kubecek |
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+ action ct clear pipe \
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Michal Kubecek |
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+ action skbedit ptype host pipe \
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Michal Kubecek |
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+ action mirred ingress redirect dev $h1
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Michal Kubecek |
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+ tc filter add dev $h1 protocol ip pref 101 handle 101 egress flower \
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Michal Kubecek |
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+ $tcflags ip_proto icmp \
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Michal Kubecek |
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+ action mirred ingress redirect dev $h1
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Michal Kubecek |
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+ tc filter add dev $h1 protocol ip pref 102 handle 102 ingress flower \
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Michal Kubecek |
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+ ip_proto icmp \
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Michal Kubecek |
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+ action drop
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Michal Kubecek |
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+
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Michal Kubecek |
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+ ip vrf exec v$h1 nc --recv-only -w10 -l -p 12345 -o $tmpfile1 &
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Michal Kubecek |
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+ local rpid=$!
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Michal Kubecek |
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+ ip vrf exec v$h1 nc -w1 --send-only 192.0.2.2 12345 <$tmpfile
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Michal Kubecek |
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+ wait -n $rpid
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Michal Kubecek |
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+ cmp -s $tmpfile $tmpfile1
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Michal Kubecek |
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+ check_err $? "server output check failed"
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+
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Michal Kubecek |
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+ $MZ $h1 -c 10 -p 64 -a $h1mac -b $h1mac -A 192.0.2.1 -B 192.0.2.1 \
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Michal Kubecek |
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+ -t icmp "ping,id=42,seq=5" -q
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Michal Kubecek |
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+ tc_check_packets "dev $h1 egress" 101 10
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Michal Kubecek |
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+ check_err $? "didn't mirred redirect ICMP"
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Michal Kubecek |
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+ tc_check_packets "dev $h1 ingress" 102 10
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Michal Kubecek |
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+ check_err $? "didn't drop mirred ICMP"
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Michal Kubecek |
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+ local overlimits=$(tc_rule_stats_get ${h1} 101 egress .overlimits)
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Michal Kubecek |
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+ test ${overlimits} = 10
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Michal Kubecek |
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+ check_err $? "wrong overlimits, expected 10 got ${overlimits}"
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Michal Kubecek |
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+
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Michal Kubecek |
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+ tc filter del dev $h1 egress protocol ip pref 100 handle 100 flower
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Michal Kubecek |
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+ tc filter del dev $h1 egress protocol ip pref 101 handle 101 flower
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Michal Kubecek |
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+ tc filter del dev $h1 ingress protocol ip pref 102 handle 102 flower
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Michal Kubecek |
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+
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Michal Kubecek |
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+ rm -f $tmpfile $tmpfile1
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Michal Kubecek |
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+ log_test "mirred_egress_to_ingress_tcp ($tcflags)"
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Michal Kubecek |
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+}
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Michal Kubecek |
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+
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Michal Kubecek |
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setup_prepare()
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Michal Kubecek |
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{
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Michal Kubecek |
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h1=${NETIFS[p1]}
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