From 98b34f3e8c3492cfc89ff943c9d92b4d52863d1d Mon Sep 17 00:00:00 2001 From: Jamal Hadi Salim Date: Mon, 25 May 2026 08:25:48 -0400 Subject: [PATCH 1/9] net: Introduce skb tc depth field to track packet loops Add a 2-bit per-skb tc depth field to track packet loops across the stack. The previous per-CPU loop counters like MIRRED_NEST_LIMIT assume a single call stack and lose state in two cases: 1) When a packet is queued and reprocessed later (e.g., egress->ingress via backlog), the per-cpu state is gone by the time it is dequeued. 2) With XPS/RPS a packet may arrive on one CPU and be processed on another. A per-skb field solves both by travelling with the packet itself. The field fits in existing padding, using 2 bits that were previously a hole: pahole before(-) and after (+) diff looks like: __u8 slow_gro:1; /* 132: 3 1 */ __u8 csum_not_inet:1; /* 132: 4 1 */ __u8 unreadable:1; /* 132: 5 1 */ + __u8 tc_depth:2; /* 132: 6 1 */ - /* XXX 2 bits hole, try to pack */ /* XXX 1 byte hole, try to pack */ __u16 tc_index; /* 134 2 */ There used to be a ttl field which was removed as part of tc_verd in commit aec745e2c520 ("net-tc: remove unused tc_verd fields"). It was already unused by that time, due to remove earlier in commit c19ae86a510c ("tc: remove unused redirect ttl"). The first user of this field is netem, which increments tc_depth on duplicated packets before re-enqueueing them at the root qdisc. On re-entry, netem skips duplication for any skb with tc_depth already set, bounding recursion to a single level regardless of tree topology. The other user is mirred which increments it on each pass and limits to depth to MIRRED_DEFER_LIMIT (3). The new field was called ttl in earlier versions of this patch but renamed to tc_depth to avoid confusion with IP ttl. Note (looking at you Sashiko! Dont ignore me and continue bringing this up): 1. Since both mirred and netem utilize the same 2-bit tc_depth field it is possible when netem and mirred are used together that netem qdisc to skip the duplication step. This is a known trade-off, as a 2-bit field cannot independently track both features' recursion depths and it is not considered sane to have a setup that addresses both features on at the same time. 2. skb_scrub_packet does not clear tc_depth. This means a packet's loop history is preserved even across namespaces. While this might be restrictive for some topologies, it is also design intent to provide robustness against loops across namespaces. Reviewed-by: Stephen Hemminger Signed-off-by: Jamal Hadi Salim Link: https://patch.msgid.link/20260525122556.973584-2-jhs@mojatatu.com Signed-off-by: Paolo Abeni --- include/linux/skbuff.h | 2 ++ 1 file changed, 2 insertions(+) diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h index 2bcf78a4de7b..3f06254ab1b7 100644 --- a/include/linux/skbuff.h +++ b/include/linux/skbuff.h @@ -821,6 +821,7 @@ enum skb_tstamp_type { * @_sk_redir: socket redirection information for skmsg * @_nfct: Associated connection, if any (with nfctinfo bits) * @skb_iif: ifindex of device we arrived on + * @tc_depth: counter for packet duplication * @tc_index: Traffic control index * @hash: the packet hash * @queue_mapping: Queue mapping for multiqueue devices @@ -1030,6 +1031,7 @@ struct sk_buff { __u8 csum_not_inet:1; #endif __u8 unreadable:1; + __u8 tc_depth:2; #if defined(CONFIG_NET_SCHED) || defined(CONFIG_NET_XGRESS) __u16 tc_index; /* traffic control index */ #endif From eda0b7f203bb166c98d1418b204135bd566ac83b Mon Sep 17 00:00:00 2001 From: Jamal Hadi Salim Date: Mon, 25 May 2026 08:25:49 -0400 Subject: [PATCH 2/9] net/sched: Revert "net/sched: Restrict conditions for adding duplicating netems to qdisc tree" This reverts commit ec8e0e3d7adef940cdf9475e2352c0680189d14e. The original patch rejects any tree containing two netems when either has duplication set, even when they sit on unrelated classes of the same classful parent. That broke configurations that have worked since netem was introduced. The re-entrancy problem the original commit was trying to solve is handled by later patch using tc_depth flag. Doing this revert will (re)expose the original bug with multiple netem duplication. When this patch is backported make sure and get the full series. Fixes: ec8e0e3d7ade ("net/sched: Restrict conditions for adding duplicating netems to qdisc tree") Reported-by: Ji-Soo Chung Reported-by: Gerlinde Closes: https://bugzilla.kernel.org/show_bug.cgi?id=220774 Reported-by: zyc zyc Closes: https://lore.kernel.org/all/19adda5a1e2.12410b78222774.9191120410578703463@zohomail.cn/ Reported-by: Manas Ghandat Closes: https://lore.kernel.org/netdev/f69b2c8f-8325-4c2e-a011-6dbc089f30e4@gmail.com/ Reviewed-by: Stephen Hemminger Signed-off-by: Jamal Hadi Salim Link: https://patch.msgid.link/20260525122556.973584-3-jhs@mojatatu.com Signed-off-by: Paolo Abeni --- net/sched/sch_netem.c | 40 ---------------------------------------- 1 file changed, 40 deletions(-) diff --git a/net/sched/sch_netem.c b/net/sched/sch_netem.c index bc18e1976b6e..d97acd2f3923 100644 --- a/net/sched/sch_netem.c +++ b/net/sched/sch_netem.c @@ -1007,41 +1007,6 @@ static int parse_attr(struct nlattr *tb[], int maxtype, struct nlattr *nla, return 0; } -static const struct Qdisc_class_ops netem_class_ops; - -static int check_netem_in_tree(struct Qdisc *sch, bool duplicates, - struct netlink_ext_ack *extack) -{ - struct Qdisc *root, *q; - unsigned int i; - - root = qdisc_root_sleeping(sch); - - if (sch != root && root->ops->cl_ops == &netem_class_ops) { - if (duplicates || - ((struct netem_sched_data *)qdisc_priv(root))->duplicate) - goto err; - } - - if (!qdisc_dev(root)) - return 0; - - hash_for_each(qdisc_dev(root)->qdisc_hash, i, q, hash) { - if (sch != q && q->ops->cl_ops == &netem_class_ops) { - if (duplicates || - ((struct netem_sched_data *)qdisc_priv(q))->duplicate) - goto err; - } - } - - return 0; - -err: - NL_SET_ERR_MSG(extack, - "netem: cannot mix duplicating netems with other netems in tree"); - return -EINVAL; -} - /* Parse netlink message to set options */ static int netem_change(struct Qdisc *sch, struct nlattr *opt, struct netlink_ext_ack *extack) @@ -1118,11 +1083,6 @@ static int netem_change(struct Qdisc *sch, struct nlattr *opt, q->gap = qopt->gap; q->counter = 0; q->loss = qopt->loss; - - ret = check_netem_in_tree(sch, qopt->duplicate, extack); - if (ret) - goto unlock; - q->duplicate = qopt->duplicate; /* for compatibility with earlier versions. From b213a4c6074fc4ee4f1cdef9a73b34732606b637 Mon Sep 17 00:00:00 2001 From: Jamal Hadi Salim Date: Mon, 25 May 2026 08:25:50 -0400 Subject: [PATCH 3/9] Revert "selftests/tc-testing: Add tests for restrictions on netem duplication" This reverts commit ecdec65ec78d67d3ebd17edc88b88312054abe0d. The tests added were related to check_netem_in_tree() which was just reverted in the previous patch. Reviewed-by: Stephen Hemminger Signed-off-by: Jamal Hadi Salim Link: https://patch.msgid.link/20260525122556.973584-4-jhs@mojatatu.com Signed-off-by: Paolo Abeni --- .../tc-testing/tc-tests/infra/qdiscs.json | 5 +- .../tc-testing/tc-tests/qdiscs/netem.json | 81 ------------------- 2 files changed, 3 insertions(+), 83 deletions(-) diff --git a/tools/testing/selftests/tc-testing/tc-tests/infra/qdiscs.json b/tools/testing/selftests/tc-testing/tc-tests/infra/qdiscs.json index 848696c373fc..82c38a13dfbf 100644 --- a/tools/testing/selftests/tc-testing/tc-tests/infra/qdiscs.json +++ b/tools/testing/selftests/tc-testing/tc-tests/infra/qdiscs.json @@ -702,6 +702,7 @@ "$TC qdisc add dev $DUMMY parent 1:1 handle 2:0 netem duplicate 100%", "$TC filter add dev $DUMMY parent 1:0 protocol ip prio 1 u32 match ip dst 10.10.10.1/32 flowid 1:1", "$TC class add dev $DUMMY parent 1:0 classid 1:2 hfsc ls m2 10Mbit", + "$TC qdisc add dev $DUMMY parent 1:2 handle 3:0 netem duplicate 100%", "$TC filter add dev $DUMMY parent 1:0 protocol ip prio 2 u32 match ip dst 10.10.10.2/32 flowid 1:2", "ping -c 1 10.10.10.1 -I$DUMMY > /dev/null || true", "$TC filter del dev $DUMMY parent 1:0 protocol ip prio 1", @@ -714,8 +715,8 @@ { "kind": "hfsc", "handle": "1:", - "bytes": 294, - "packets": 3 + "bytes": 392, + "packets": 4 } ], "matchCount": "1", diff --git a/tools/testing/selftests/tc-testing/tc-tests/qdiscs/netem.json b/tools/testing/selftests/tc-testing/tc-tests/qdiscs/netem.json index 718d2df2aafa..3c4444961488 100644 --- a/tools/testing/selftests/tc-testing/tc-tests/qdiscs/netem.json +++ b/tools/testing/selftests/tc-testing/tc-tests/qdiscs/netem.json @@ -336,86 +336,5 @@ "teardown": [ "$TC qdisc del dev $DUMMY handle 1: root" ] - }, - { - "id": "d34d", - "name": "NETEM test qdisc duplication restriction in qdisc tree in netem_change root", - "category": ["qdisc", "netem"], - "plugins": { - "requires": "nsPlugin" - }, - "setup": [ - "$TC qdisc add dev $DUMMY root handle 1: netem limit 1", - "$TC qdisc add dev $DUMMY parent 1: handle 2: netem limit 1" - ], - "cmdUnderTest": "$TC qdisc change dev $DUMMY handle 1: netem duplicate 50%", - "expExitCode": "2", - "verifyCmd": "$TC -s qdisc show dev $DUMMY", - "matchPattern": "qdisc netem", - "matchCount": "2", - "teardown": [ - "$TC qdisc del dev $DUMMY handle 1:0 root" - ] - }, - { - "id": "b33f", - "name": "NETEM test qdisc duplication restriction in qdisc tree in netem_change non-root", - "category": ["qdisc", "netem"], - "plugins": { - "requires": "nsPlugin" - }, - "setup": [ - "$TC qdisc add dev $DUMMY root handle 1: netem limit 1", - "$TC qdisc add dev $DUMMY parent 1: handle 2: netem limit 1" - ], - "cmdUnderTest": "$TC qdisc change dev $DUMMY handle 2: netem duplicate 50%", - "expExitCode": "2", - "verifyCmd": "$TC -s qdisc show dev $DUMMY", - "matchPattern": "qdisc netem", - "matchCount": "2", - "teardown": [ - "$TC qdisc del dev $DUMMY handle 1:0 root" - ] - }, - { - "id": "cafe", - "name": "NETEM test qdisc duplication restriction in qdisc tree", - "category": ["qdisc", "netem"], - "plugins": { - "requires": "nsPlugin" - }, - "setup": [ - "$TC qdisc add dev $DUMMY root handle 1: netem limit 1 duplicate 100%" - ], - "cmdUnderTest": "$TC qdisc add dev $DUMMY parent 1: handle 2: netem duplicate 100%", - "expExitCode": "2", - "verifyCmd": "$TC -s qdisc show dev $DUMMY", - "matchPattern": "qdisc netem", - "matchCount": "1", - "teardown": [ - "$TC qdisc del dev $DUMMY handle 1:0 root" - ] - }, - { - "id": "1337", - "name": "NETEM test qdisc duplication restriction in qdisc tree across branches", - "category": ["qdisc", "netem"], - "plugins": { - "requires": "nsPlugin" - }, - "setup": [ - "$TC qdisc add dev $DUMMY parent root handle 1:0 hfsc", - "$TC class add dev $DUMMY parent 1:0 classid 1:1 hfsc rt m2 10Mbit", - "$TC qdisc add dev $DUMMY parent 1:1 handle 2:0 netem", - "$TC class add dev $DUMMY parent 1:0 classid 1:2 hfsc rt m2 10Mbit" - ], - "cmdUnderTest": "$TC qdisc add dev $DUMMY parent 1:2 handle 3:0 netem duplicate 100%", - "expExitCode": "2", - "verifyCmd": "$TC -s qdisc show dev $DUMMY", - "matchPattern": "qdisc netem", - "matchCount": "1", - "teardown": [ - "$TC qdisc del dev $DUMMY handle 1:0 root" - ] } ] From 9552b11e3edabc97cfcd9f29103d5afbce7ae183 Mon Sep 17 00:00:00 2001 From: Jamal Hadi Salim Date: Mon, 25 May 2026 08:25:51 -0400 Subject: [PATCH 4/9] net/sched: fix packet loop on netem when duplicate is on When netem duplicates a packet it re-enqueues the copy at the root qdisc. If another netem sits in the tree the copy can be duplicated again, recursing until the stack or memory is exhausted. The original duplication guard temporarily zeroed q->duplicate around the re-enqueue, but that does not cover all cases because it is per-qdisc state shared across all concurrent enqueue paths and is not safe without additional locking. Use the skb tc_depth field introduced in an earlier patch: - increment it on the duplicate before re-enqueue - skip duplication for any skb whose tc_depth is already non-zero. This marks the packet itself rather than mutating qdisc state, therefore it is safe regardless of tree topology or concurrency. Fixes: 0afb51e72855 ("[PKT_SCHED]: netem: reinsert for duplication") Reported-by: William Liu Reported-by: Savino Dicanosa Closes: https://lore.kernel.org/netdev/8DuRWwfqjoRDLDmBMlIfbrsZg9Gx50DHJc1ilxsEBNe2D6NMoigR_eIRIG0LOjMc3r10nUUZtArXx4oZBIdUfZQrwjcQhdinnMis_0G7VEk=@willsroot.io/ Co-developed-by: Victor Nogueira Signed-off-by: Victor Nogueira Reviewed-by: William Liu Reviewed-by: Stephen Hemminger Signed-off-by: Jamal Hadi Salim Link: https://patch.msgid.link/20260525122556.973584-5-jhs@mojatatu.com Signed-off-by: Paolo Abeni --- net/sched/sch_netem.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) diff --git a/net/sched/sch_netem.c b/net/sched/sch_netem.c index d97acd2f3923..17a79fe2f091 100644 --- a/net/sched/sch_netem.c +++ b/net/sched/sch_netem.c @@ -461,7 +461,8 @@ static int netem_enqueue(struct sk_buff *skb, struct Qdisc *sch, skb->prev = NULL; /* Random duplication */ - if (q->duplicate && q->duplicate >= get_crandom(&q->dup_cor, &q->prng)) + if (q->duplicate && skb->tc_depth == 0 && + q->duplicate >= get_crandom(&q->dup_cor, &q->prng)) ++count; /* Drop packet? */ @@ -540,11 +541,9 @@ static int netem_enqueue(struct sk_buff *skb, struct Qdisc *sch, */ if (skb2) { struct Qdisc *rootq = qdisc_root_bh(sch); - u32 dupsave = q->duplicate; /* prevent duplicating a dup... */ - q->duplicate = 0; + skb2->tc_depth++; /* prevent duplicating a dup... */ rootq->enqueue(skb2, rootq, to_free); - q->duplicate = dupsave; skb2 = NULL; } From db875221ab08d213a83bf30196ae8b64d55a3403 Mon Sep 17 00:00:00 2001 From: Jamal Hadi Salim Date: Mon, 25 May 2026 08:25:52 -0400 Subject: [PATCH 5/9] net/sched: Fix ethx:ingress -> ethy:egress -> ethx:ingress mirred loop When mirred redirects to ingress (from either ingress or egress) the loop state from sched_mirred_dev array dev is lost because of 1) the packet deferral into the backlog and 2) the fact the sched_mirred_dev array is cleared. In such cases, if there was a loop we won't discover it. Here's a simple test to reproduce: ip a add dev port0 10.10.10.11/24 tc qdisc add dev port0 clsact tc filter add dev port0 egress protocol ip \ prio 10 matchall action mirred ingress redirect dev port1 tc qdisc add dev port1 clsact tc filter add dev port1 ingress protocol ip \ prio 10 matchall action mirred egress redirect dev port0 ping -c 1 -W0.01 10.10.10.10 Fixes: fe946a751d9b ("net/sched: act_mirred: add loop detection") Tested-by: Victor Nogueira Reviewed-by: Stephen Hemminger Signed-off-by: Jamal Hadi Salim Link: https://patch.msgid.link/20260525122556.973584-6-jhs@mojatatu.com Signed-off-by: Paolo Abeni --- net/sched/act_mirred.c | 47 +++++++++++++++++++++++++++--------------- 1 file changed, 30 insertions(+), 17 deletions(-) diff --git a/net/sched/act_mirred.c b/net/sched/act_mirred.c index 2c5a7a321a94..dd5e7ea7ef26 100644 --- a/net/sched/act_mirred.c +++ b/net/sched/act_mirred.c @@ -26,6 +26,10 @@ #include #include +#define MIRRED_DEFER_LIMIT 3 +_Static_assert(MIRRED_DEFER_LIMIT <= 3, + "MIRRED_DEFER_LIMIT exceeds tc_depth bitfield width"); + static LIST_HEAD(mirred_list); static DEFINE_SPINLOCK(mirred_list_lock); @@ -234,12 +238,15 @@ tcf_mirred_forward(bool at_ingress, bool want_ingress, struct sk_buff *skb) { int err; - if (!want_ingress) + if (!want_ingress) { err = tcf_dev_queue_xmit(skb, dev_queue_xmit); - else if (!at_ingress) - err = netif_rx(skb); - else - err = netif_receive_skb(skb); + } else { + skb->tc_depth++; + if (!at_ingress) + err = netif_rx(skb); + else + err = netif_receive_skb(skb); + } return err; } @@ -426,6 +433,7 @@ TC_INDIRECT_SCOPE int tcf_mirred_act(struct sk_buff *skb, struct netdev_xmit *xmit; bool m_mac_header_xmit; struct net_device *dev; + bool want_ingress; int i, m_eaction; u32 blockid; @@ -434,7 +442,8 @@ TC_INDIRECT_SCOPE int tcf_mirred_act(struct sk_buff *skb, #else xmit = this_cpu_ptr(&softnet_data.xmit); #endif - if (unlikely(xmit->sched_mirred_nest >= MIRRED_NEST_LIMIT)) { + if (unlikely(xmit->sched_mirred_nest >= MIRRED_NEST_LIMIT || + skb->tc_depth >= MIRRED_DEFER_LIMIT)) { net_warn_ratelimited("Packet exceeded mirred recursion limit on dev %s\n", netdev_name(skb->dev)); return TC_ACT_SHOT; @@ -453,23 +462,27 @@ TC_INDIRECT_SCOPE int tcf_mirred_act(struct sk_buff *skb, tcf_action_inc_overlimit_qstats(&m->common); return retval; } - for (i = 0; i < xmit->sched_mirred_nest; i++) { - if (xmit->sched_mirred_dev[i] != dev) - continue; - pr_notice_once("tc mirred: loop on device %s\n", - netdev_name(dev)); - tcf_action_inc_overlimit_qstats(&m->common); - return retval; + + m_eaction = READ_ONCE(m->tcfm_eaction); + want_ingress = tcf_mirred_act_wants_ingress(m_eaction); + if (!want_ingress) { + for (i = 0; i < xmit->sched_mirred_nest; i++) { + if (xmit->sched_mirred_dev[i] != dev) + continue; + pr_notice_once("tc mirred: loop on device %s\n", + netdev_name(dev)); + tcf_action_inc_overlimit_qstats(&m->common); + return retval; + } + xmit->sched_mirred_dev[xmit->sched_mirred_nest++] = dev; } - xmit->sched_mirred_dev[xmit->sched_mirred_nest++] = dev; - m_mac_header_xmit = READ_ONCE(m->tcfm_mac_header_xmit); - m_eaction = READ_ONCE(m->tcfm_eaction); retval = tcf_mirred_to_dev(skb, m, dev, m_mac_header_xmit, m_eaction, retval); - xmit->sched_mirred_nest--; + if (!want_ingress) + xmit->sched_mirred_nest--; return retval; } From a005fa5d7502eefec7ee6e1c01adadc06de2f9ad Mon Sep 17 00:00:00 2001 From: "Kito Xu (veritas501)" Date: Mon, 25 May 2026 08:25:53 -0400 Subject: [PATCH 6/9] net/sched: act_mirred: Fix blockcast recursion bypass leading to stack overflow tcf_mirred_act() checks sched_mirred_nest against MIRRED_NEST_LIMIT (4) to prevent deep recursion. However, when the action uses blockcast (tcfm_blockid != 0), the function returns at the tcf_blockcast() call BEFORE reaching the counter increment. As a result, the recursion counter never advances and the limit check is entirely bypassed. When two devices share a TC egress block with a mirred blockcast rule, a packet egressing on device A is mirrored to device B via blockcast; device B's egress TC re-enters tcf_mirred_act() via blockcast and mirrors back to A, creating an unbounded recursion loop: tcf_mirred_act -> tcf_blockcast -> tcf_mirred_to_dev -> dev_queue_xmit -> sch_handle_egress -> tcf_classify -> tcf_mirred_act -> (repeat) This recursion continues until the kernel stack overflows. The bug is reachable from an unprivileged user via unshare(CLONE_NEWUSER | CLONE_NEWNET): user namespaces grant CAP_NET_ADMIN in the new network namespace, which is sufficient to create dummy devices, attach clsact qdiscs with shared blocks, and install mirred blockcast filters. BUG: TASK stack guard page was hit at ffffc90000b7fff8 Oops: stack guard page: 0000 [#1] SMP KASAN NOPTI CPU: 2 UID: 1000 PID: 169 Comm: poc Not tainted 7.0.0-rc7-next-20260410 RIP: 0010:xas_find+0x17/0x480 Call Trace: xa_find+0x17b/0x1d0 tcf_mirred_act+0x640/0x1060 tcf_action_exec+0x400/0x530 basic_classify+0x128/0x1d0 tcf_classify+0xd83/0x1150 tc_run+0x328/0x620 __dev_queue_xmit+0x797/0x3100 tcf_mirred_to_dev+0x7b1/0xf70 tcf_mirred_act+0x68a/0x1060 [repeating ~30+ times until stack overflow] Kernel panic - not syncing: Fatal exception in interrupt Fix this by incrementing sched_mirred_nest before calling tcf_blockcast() and decrementing it on return, mirroring the non-blockcast path. This ensures subsequent recursive entries see the updated counter and are correctly limited by MIRRED_NEST_LIMIT. Fixes: fe946a751d9b ("net/sched: act_mirred: add loop detection") Signed-off-by: Kito Xu (veritas501) Link: https://patch.msgid.link/20260525122556.973584-7-jhs@mojatatu.com Signed-off-by: Paolo Abeni --- net/sched/act_mirred.c | 18 +++++++++++------- 1 file changed, 11 insertions(+), 7 deletions(-) diff --git a/net/sched/act_mirred.c b/net/sched/act_mirred.c index dd5e7ea7ef26..dbe4a4ff3e08 100644 --- a/net/sched/act_mirred.c +++ b/net/sched/act_mirred.c @@ -396,14 +396,12 @@ static int tcf_blockcast_mirror(struct sk_buff *skb, struct tcf_mirred *m, static int tcf_blockcast(struct sk_buff *skb, struct tcf_mirred *m, const u32 blockid, struct tcf_result *res, - int retval) + int m_eaction, int retval) { const u32 exception_ifindex = skb->dev->ifindex; struct tcf_block *block; bool is_redirect; - int m_eaction; - m_eaction = READ_ONCE(m->tcfm_eaction); is_redirect = tcf_mirred_is_act_redirect(m_eaction); /* we are already under rcu protection, so can call block lookup @@ -453,8 +451,16 @@ TC_INDIRECT_SCOPE int tcf_mirred_act(struct sk_buff *skb, tcf_action_update_bstats(&m->common, skb); blockid = READ_ONCE(m->tcfm_blockid); - if (blockid) - return tcf_blockcast(skb, m, blockid, res, retval); + m_eaction = READ_ONCE(m->tcfm_eaction); + want_ingress = tcf_mirred_act_wants_ingress(m_eaction); + if (blockid) { + if (!want_ingress) + xmit->sched_mirred_dev[xmit->sched_mirred_nest++] = NULL; + retval = tcf_blockcast(skb, m, blockid, res, m_eaction, retval); + if (!want_ingress) + xmit->sched_mirred_nest--; + return retval; + } dev = rcu_dereference_bh(m->tcfm_dev); if (unlikely(!dev)) { @@ -463,8 +469,6 @@ TC_INDIRECT_SCOPE int tcf_mirred_act(struct sk_buff *skb, return retval; } - m_eaction = READ_ONCE(m->tcfm_eaction); - want_ingress = tcf_mirred_act_wants_ingress(m_eaction); if (!want_ingress) { for (i = 0; i < xmit->sched_mirred_nest; i++) { if (xmit->sched_mirred_dev[i] != dev) From e80ad525fc7e8c933ad78478c5dda286cfd55c60 Mon Sep 17 00:00:00 2001 From: Victor Nogueira Date: Mon, 25 May 2026 08:25:54 -0400 Subject: [PATCH 7/9] net/sched: act_mirred: Fix return code in early mirred redirect error paths Since retval is set as TC_ACT_STOLEN in the mirred redirect case, returning retval in cases where redirect failed will make the callers not register the skb as being dropped. Fix this by returning TC_ACT_SHOT instead in such scenarios. Fixes: 16085e48cb48 ("net/sched: act_mirred: Create function tcf_mirred_to_dev and improve readability") Reported-by: Sashiko Closes: https://sashiko.dev/#/patchset/20260413082027.2244884-1-hxzene%40gmail.com Signed-off-by: Victor Nogueira Link: https://patch.msgid.link/20260525122556.973584-8-jhs@mojatatu.com Signed-off-by: Paolo Abeni --- net/sched/act_mirred.c | 18 +++++++++++++----- 1 file changed, 13 insertions(+), 5 deletions(-) diff --git a/net/sched/act_mirred.c b/net/sched/act_mirred.c index dbe4a4ff3e08..553342c55cf7 100644 --- a/net/sched/act_mirred.c +++ b/net/sched/act_mirred.c @@ -372,7 +372,8 @@ static int tcf_blockcast_redir(struct sk_buff *skb, struct tcf_mirred *m, dev_is_mac_header_xmit(dev_prev), m_eaction, retval); - return retval; + /* If the packet wasn't redirected, we have to register as a drop */ + return TC_ACT_SHOT; } static int tcf_blockcast_mirror(struct sk_buff *skb, struct tcf_mirred *m, @@ -410,7 +411,7 @@ static int tcf_blockcast(struct sk_buff *skb, struct tcf_mirred *m, block = tcf_block_lookup(dev_net(skb->dev), blockid); if (!block || xa_empty(&block->ports)) { tcf_action_inc_overlimit_qstats(&m->common); - return retval; + return is_redirect ? TC_ACT_SHOT : retval; } if (is_redirect) @@ -428,8 +429,8 @@ TC_INDIRECT_SCOPE int tcf_mirred_act(struct sk_buff *skb, { struct tcf_mirred *m = to_mirred(a); int retval = READ_ONCE(m->tcf_action); + bool m_mac_header_xmit, is_redirect; struct netdev_xmit *xmit; - bool m_mac_header_xmit; struct net_device *dev; bool want_ingress; int i, m_eaction; @@ -462,11 +463,13 @@ TC_INDIRECT_SCOPE int tcf_mirred_act(struct sk_buff *skb, return retval; } + is_redirect = tcf_mirred_is_act_redirect(m_eaction); + dev = rcu_dereference_bh(m->tcfm_dev); if (unlikely(!dev)) { pr_notice_once("tc mirred: target device is gone\n"); tcf_action_inc_overlimit_qstats(&m->common); - return retval; + goto err_out; } if (!want_ingress) { @@ -476,7 +479,7 @@ TC_INDIRECT_SCOPE int tcf_mirred_act(struct sk_buff *skb, pr_notice_once("tc mirred: loop on device %s\n", netdev_name(dev)); tcf_action_inc_overlimit_qstats(&m->common); - return retval; + goto err_out; } xmit->sched_mirred_dev[xmit->sched_mirred_nest++] = dev; } @@ -489,6 +492,11 @@ TC_INDIRECT_SCOPE int tcf_mirred_act(struct sk_buff *skb, xmit->sched_mirred_nest--; return retval; + +err_out: + if (is_redirect) + retval = TC_ACT_SHOT; + return retval; } static void tcf_stats_update(struct tc_action *a, u64 bytes, u64 packets, From d38dc56a0225664e494221b5b251931b35d125ef Mon Sep 17 00:00:00 2001 From: Victor Nogueira Date: Mon, 25 May 2026 08:25:55 -0400 Subject: [PATCH 8/9] selftests/tc-testing: Add mirred test cases exercising loops Add mirred loop test cases to validate that those will be caught and other test cases that were previously misinterpreted as loops by mirred. This commit adds 12 test cases: - Redirect multiport: dummy egress -> dev1 ingress -> dummy egress (Loop) - Redirect singleport: dev1 ingress -> dev1 egress -> dev1 ingress (Loop) - Redirect multiport: dev1 ingress -> dummy ingress -> dev1 egress (No Loop) - Redirect multiport: dev1 ingress -> dummy ingress -> dev1 ingress (Loop) - Redirect multiport: dev1 ingress -> dummy egress -> dev1 ingress (Loop) - Redirect multiport: dummy egress -> dev1 ingress -> dummy egress, different prios (Loop) - Redirect multiport: dev1 ingress -> dummy ingress -> dummy egress -> dev1 egress (No Loop) - Redirect multiport: dev1 ingress -> dummy egress -> dev1 egress (No Loop) - Redirect multiport: dev1 ingress -> dummy egress -> dummy ingress (No Loop) - Redirect singleport: dev1 ingress -> dev1 ingress (Loop) - Redirect singleport: dummy egress -> dummy ingress (No Loop) - Redirect multiport: dev1 ingress -> dummy ingress -> dummy egress (No Loop) Acked-by: Jamal Hadi Salim Acked-by: Stephen Hemminger Signed-off-by: Victor Nogueira Link: https://patch.msgid.link/20260525122556.973584-9-jhs@mojatatu.com Signed-off-by: Paolo Abeni --- .../tc-testing/tc-tests/actions/mirred.json | 616 +++++++++++++++++- 1 file changed, 615 insertions(+), 1 deletion(-) diff --git a/tools/testing/selftests/tc-testing/tc-tests/actions/mirred.json b/tools/testing/selftests/tc-testing/tc-tests/actions/mirred.json index b056eb966871..d0cad6571691 100644 --- a/tools/testing/selftests/tc-testing/tc-tests/actions/mirred.json +++ b/tools/testing/selftests/tc-testing/tc-tests/actions/mirred.json @@ -1144,6 +1144,620 @@ "teardown": [ "$TC qdisc del dev $DUMMY clsact" ] + }, + { + "id": "531c", + "name": "Redirect multiport: dummy egress -> dev1 ingress -> dummy egress (Loop)", + "category": [ + "filter", + "mirred" + ], + "plugins": { + "requires": [ + "nsPlugin" + ] + }, + "setup": [ + "$IP link set dev $DUMMY up || true", + "$IP addr add 10.10.10.10/24 dev $DUMMY || true", + "$TC qdisc add dev $DUMMY clsact", + "$TC filter add dev $DUMMY egress protocol ip prio 10 matchall action mirred ingress redirect dev $DEV1 index 1", + "$TC qdisc add dev $DEV1 clsact", + "$TC filter add dev $DEV1 ingress protocol ip prio 10 matchall action mirred egress redirect dev $DUMMY index 2" + ], + "cmdUnderTest": "ping -c1 -W0.01 -I $DUMMY 10.10.10.1", + "expExitCode": "1", + "verifyCmd": "$TC -j -s actions get action mirred index 1", + "matchJSON": [ + { + "total acts": 0 + }, + { + "actions": [ + { + "order": 1, + "kind": "mirred", + "mirred_action": "redirect", + "direction": "ingress", + "index": 1, + "stats": { + "packets": 3 + }, + "not_in_hw": true + } + ] + } + ], + "teardown": [ + "$TC qdisc del dev $DUMMY clsact", + "$TC qdisc del dev $DEV1 clsact" + ] + }, + { + "id": "b1d7", + "name": "Redirect singleport: dev1 ingress -> dev1 egress -> dev1 ingress (Loop)", + "category": [ + "filter", + "mirred" + ], + "plugins": { + "requires": [ + "nsPlugin", + "scapyPlugin" + ] + }, + "setup": [ + "$TC qdisc add dev $DEV1 clsact", + "$TC filter add dev $DEV1 ingress protocol ip prio 10 matchall action mirred egress redirect dev $DEV1 index 1" + ], + "cmdUnderTest": "$TC filter add dev $DEV1 egress protocol ip prio 11 matchall action mirred ingress redirect dev $DEV1 index 2", + "scapy": [ + { + "iface": "$DEV0", + "count": 1, + "packet": "Ether()/IP(dst='10.10.10.1', src='10.10.10.10')/ICMP()" + } + ], + "expExitCode": "0", + "verifyCmd": "$TC -j -s actions get action mirred index 1", + "matchJSON": [ + { + "total acts": 0 + }, + { + "actions": [ + { + "order": 1, + "kind": "mirred", + "mirred_action": "redirect", + "direction": "egress", + "index": 1, + "stats": { + "packets": 3 + }, + "not_in_hw": true + } + ] + } + ], + "teardown": [ + "$TC qdisc del dev $DEV1 clsact" + ] + }, + { + "id": "c66d", + "name": "Redirect multiport: dev1 ingress -> dummy ingress -> dev1 egress (No Loop)", + "category": [ + "filter", + "mirred" + ], + "plugins": { + "requires": [ + "nsPlugin", + "scapyPlugin" + ] + }, + "setup": [ + "$TC qdisc add dev $DEV1 clsact", + "$TC filter add dev $DEV1 ingress protocol ip prio 10 matchall action mirred ingress redirect dev $DUMMY index 1", + "$TC qdisc add dev $DUMMY clsact" + ], + "cmdUnderTest": "$TC filter add dev $DUMMY ingress protocol ip prio 11 matchall action mirred egress redirect dev $DEV1 index 2", + "scapy": [ + { + "iface": "$DEV0", + "count": 1, + "packet": "Ether()/IP(dst='10.10.10.1', src='10.10.10.10')/ICMP()" + } + ], + "expExitCode": "0", + "verifyCmd": "$TC -j -s actions get action mirred index 1", + "matchJSON": [ + { + "total acts": 0 + }, + { + "actions": [ + { + "order": 1, + "kind": "mirred", + "mirred_action": "redirect", + "direction": "ingress", + "index": 1, + "stats": { + "packets": 1 + }, + "not_in_hw": true + } + ] + } + ], + "teardown": [ + "$TC qdisc del dev $DEV1 clsact", + "$TC qdisc del dev $DUMMY clsact" + ] + }, + { + "id": "aa99", + "name": "Redirect multiport: dev1 ingress -> dummy ingress -> dev1 ingress (Loop)", + "category": [ + "filter", + "mirred" + ], + "plugins": { + "requires": [ + "nsPlugin", + "scapyPlugin" + ] + }, + "setup": [ + "$TC qdisc add dev $DEV1 clsact", + "$TC filter add dev $DEV1 ingress protocol ip prio 10 matchall action mirred ingress redirect dev $DUMMY index 1", + "$TC qdisc add dev $DUMMY clsact" + ], + "cmdUnderTest": "$TC filter add dev $DUMMY ingress protocol ip prio 11 matchall action mirred ingress redirect dev $DEV1 index 2", + "scapy": [ + { + "iface": "$DEV0", + "count": 1, + "packet": "Ether()/IP(dst='10.10.10.1', src='10.10.10.10')/ICMP()" + } + ], + "expExitCode": "0", + "verifyCmd": "$TC -j -s actions get action mirred index 1", + "matchJSON": [ + { + "total acts": 0 + }, + { + "actions": [ + { + "order": 1, + "kind": "mirred", + "mirred_action": "redirect", + "direction": "ingress", + "index": 1, + "stats": { + "packets": 2, + "overlimits": 1 + }, + "not_in_hw": true + } + ] + } + ], + "teardown": [ + "$TC qdisc del dev $DEV1 clsact", + "$TC qdisc del dev $DUMMY clsact" + ] + }, + { + "id": "37d7", + "name": "Redirect multiport: dev1 ingress -> dummy egress -> dev1 ingress (Loop)", + "category": [ + "filter", + "mirred" + ], + "plugins": { + "requires": [ + "nsPlugin", + "scapyPlugin" + ] + }, + "setup": [ + "$TC qdisc add dev $DEV1 clsact", + "$TC filter add dev $DEV1 ingress protocol ip prio 10 matchall action mirred egress redirect dev $DUMMY index 1", + "$TC qdisc add dev $DUMMY clsact" + ], + "cmdUnderTest": "$TC filter add dev $DUMMY egress protocol ip prio 11 matchall action mirred ingress redirect dev $DEV1 index 2", + "scapy": [ + { + "iface": "$DEV0", + "count": 1, + "packet": "Ether()/IP(dst='10.10.10.1', src='10.10.10.10')/ICMP()" + } + ], + "expExitCode": "0", + "verifyCmd": "$TC -j -s actions get action mirred index 1", + "matchJSON": [ + { + "total acts": 0 + }, + { + "actions": [ + { + "order": 1, + "kind": "mirred", + "mirred_action": "redirect", + "direction": "egress", + "index": 1, + "stats": { + "packets": 3 + }, + "not_in_hw": true + } + ] + } + ], + "teardown": [ + "$TC qdisc del dev $DEV1 clsact", + "$TC qdisc del dev $DUMMY clsact" + ] + }, + { + "id": "6d02", + "name": "Redirect multiport: dummy egress -> dev1 ingress -> dummy egress, different prios (Loop)", + "category": [ + "filter", + "mirred" + ], + "plugins": { + "requires": [ + "nsPlugin" + ] + }, + "setup": [ + "$IP link set dev $DUMMY up || true", + "$IP addr add 10.10.10.10/24 dev $DUMMY || true", + "$TC qdisc add dev $DUMMY clsact", + "$TC filter add dev $DUMMY egress protocol ip prio 10 matchall action mirred ingress redirect dev $DEV1 index 1", + "$TC qdisc add dev $DEV1 clsact", + "$TC filter add dev $DEV1 ingress protocol ip prio 11 matchall action mirred egress redirect dev $DUMMY index 2" + ], + "cmdUnderTest": "ping -c1 -W0.01 -I $DUMMY 10.10.10.1", + "expExitCode": "1", + "verifyCmd": "$TC -j -s actions get action mirred index 1", + "matchJSON": [ + { + "total acts": 0 + }, + { + "actions": [ + { + "order": 1, + "kind": "mirred", + "mirred_action": "redirect", + "direction": "ingress", + "index": 1, + "stats": { + "packets": 3 + }, + "not_in_hw": true + } + ] + } + ], + "teardown": [ + "$TC qdisc del dev $DUMMY clsact", + "$TC qdisc del dev $DEV1 clsact" + ] + }, + { + "id": "8115", + "name": "Redirect multiport: dev1 ingress -> dummy ingress -> dummy egress -> dev1 egress (No Loop)", + "category": [ + "filter", + "mirred" + ], + "plugins": { + "requires": [ + "nsPlugin", + "scapyPlugin" + ] + }, + "setup": [ + "$TC qdisc add dev $DEV1 clsact", + "$TC filter add dev $DEV1 ingress protocol ip prio 10 matchall action mirred ingress redirect dev $DUMMY index 1", + "$TC qdisc add dev $DUMMY clsact", + "$TC filter add dev $DUMMY ingress protocol ip prio 11 matchall action mirred egress redirect dev $DUMMY index 2" + ], + "cmdUnderTest": "$TC filter add dev $DUMMY egress protocol ip prio 12 matchall action mirred egress redirect dev $DEV1 index 3", + "scapy": [ + { + "iface": "$DEV0", + "count": 1, + "packet": "Ether()/IP(dst='10.10.10.1', src='10.10.10.10')/ICMP()" + } + ], + "expExitCode": "0", + "verifyCmd": "$TC -j -s actions get action mirred index 1", + "matchJSON": [ + { + "total acts": 0 + }, + { + "actions": [ + { + "order": 1, + "kind": "mirred", + "mirred_action": "redirect", + "direction": "ingress", + "index": 1, + "stats": { + "packets": 1 + }, + "not_in_hw": true + } + ] + } + ], + "teardown": [ + "$TC qdisc del dev $DEV1 clsact", + "$TC qdisc del dev $DUMMY clsact" + ] + }, + { + "id": "9eb3", + "name": "Redirect multiport: dev1 ingress -> dummy egress -> dev1 egress (No Loop)", + "category": [ + "filter", + "mirred" + ], + "plugins": { + "requires": [ + "nsPlugin", + "scapyPlugin" + ] + }, + "setup": [ + "$TC qdisc add dev $DEV1 clsact", + "$TC filter add dev $DEV1 ingress protocol ip prio 10 matchall action mirred egress redirect dev $DUMMY index 1", + "$TC qdisc add dev $DUMMY clsact" + ], + "cmdUnderTest": "$TC filter add dev $DUMMY egress protocol ip prio 11 matchall action mirred egress redirect dev $DEV1 index 2", + "scapy": [ + { + "iface": "$DEV0", + "count": 1, + "packet": "Ether()/IP(dst='10.10.10.1', src='10.10.10.10')/ICMP()" + } + ], + "expExitCode": "0", + "verifyCmd": "$TC -j -s actions get action mirred index 1", + "matchJSON": [ + { + "total acts": 0 + }, + { + "actions": [ + { + "order": 1, + "kind": "mirred", + "mirred_action": "redirect", + "direction": "egress", + "index": 1, + "stats": { + "packets": 1 + }, + "not_in_hw": true + } + ] + } + ], + "teardown": [ + "$TC qdisc del dev $DEV1 clsact", + "$TC qdisc del dev $DUMMY clsact" + ] + }, + { + "id": "d837", + "name": "Redirect multiport: dev1 ingress -> dummy egress -> dummy ingress (No Loop)", + "category": [ + "filter", + "mirred" + ], + "plugins": { + "requires": [ + "nsPlugin", + "scapyPlugin" + ] + }, + "setup": [ + "$TC qdisc add dev $DEV1 clsact", + "$TC filter add dev $DEV1 ingress protocol ip prio 10 matchall action mirred egress redirect dev $DUMMY index 1", + "$TC qdisc add dev $DUMMY clsact" + ], + "cmdUnderTest": "$TC filter add dev $DUMMY egress protocol ip prio 11 matchall action mirred ingress redirect dev $DUMMY index 2", + "scapy": [ + { + "iface": "$DEV0", + "count": 1, + "packet": "Ether()/IP(dst='10.10.10.1', src='10.10.10.10')/ICMP()" + } + ], + "expExitCode": "0", + "verifyCmd": "$TC -j -s actions get action mirred index 1", + "matchJSON": [ + { + "total acts": 0 + }, + { + "actions": [ + { + "order": 1, + "kind": "mirred", + "mirred_action": "redirect", + "direction": "egress", + "index": 1, + "stats": { + "packets": 1 + }, + "not_in_hw": true + } + ] + } + ], + "teardown": [ + "$TC qdisc del dev $DEV1 clsact", + "$TC qdisc del dev $DUMMY clsact" + ] + }, + { + "id": "2071", + "name": "Redirect singleport: dev1 ingress -> dev1 ingress (Loop)", + "category": [ + "filter", + "mirred" + ], + "plugins": { + "requires": [ + "nsPlugin", + "scapyPlugin" + ] + }, + "setup": [ + "$TC qdisc add dev $DEV1 clsact" + ], + "cmdUnderTest": "$TC filter add dev $DEV1 ingress protocol ip prio 10 matchall action mirred ingress redirect dev $DEV1 index 1", + "scapy": [ + { + "iface": "$DEV0", + "count": 1, + "packet": "Ether()/IP(dst='10.10.10.1', src='10.10.10.10')/ICMP()" + } + ], + "expExitCode": "0", + "verifyCmd": "$TC -j -s actions get action mirred index 1", + "matchJSON": [ + { + "total acts": 0 + }, + { + "actions": [ + { + "order": 1, + "kind": "mirred", + "mirred_action": "redirect", + "direction": "ingress", + "index": 1, + "stats": { + "packets": 1, + "overlimits": 1 + }, + "not_in_hw": true + } + ] + } + ], + "teardown": [ + "$TC qdisc del dev $DEV1 clsact" + ] + }, + { + "id": "0101", + "name": "Redirect singleport: dummy egress -> dummy ingress (No Loop)", + "category": [ + "filter", + "mirred" + ], + "plugins": { + "requires": [ + "nsPlugin" + ] + }, + "setup": [ + "$IP addr add 10.10.10.10/24 dev $DUMMY || true", + "$TC qdisc add dev $DUMMY clsact", + "$TC filter add dev $DUMMY egress protocol ip prio 11 matchall action mirred ingress redirect dev $DUMMY index 1" + ], + "cmdUnderTest": "ping -c1 -W0.01 -I $DUMMY 10.10.10.1", + "expExitCode": "1", + "verifyCmd": "$TC -j -s actions get action mirred index 1", + "matchJSON": [ + { + "total acts": 0 + }, + { + "actions": [ + { + "order": 1, + "kind": "mirred", + "mirred_action": "redirect", + "direction": "ingress", + "index": 1, + "stats": { + "packets": 1 + }, + "not_in_hw": true + } + ] + } + ], + "teardown": [ + "$TC qdisc del dev $DUMMY clsact" + ] + }, + { + "id": "cf97", + "name": "Redirect multiport: dev1 ingress -> dummy ingress -> dummy egress (No Loop)", + "category": [ + "filter", + "mirred" + ], + "plugins": { + "requires": [ + "nsPlugin", + "scapyPlugin" + ] + }, + "setup": [ + "$TC qdisc add dev $DEV1 clsact", + "$TC filter add dev $DEV1 ingress protocol ip prio 10 matchall action mirred ingress redirect dev $DUMMY index 1", + "$TC qdisc add dev $DUMMY clsact" + ], + "cmdUnderTest": "$TC filter add dev $DUMMY ingress protocol ip prio 11 matchall action mirred egress redirect dev $DUMMY index 2", + "scapy": [ + { + "iface": "$DEV0", + "count": 1, + "packet": "Ether()/IP(dst='10.10.10.1', src='10.10.10.10')/ICMP()" + } + ], + "expExitCode": "0", + "verifyCmd": "$TC -j -s actions get action mirred index 1", + "matchJSON": [ + { + "total acts": 0 + }, + { + "actions": [ + { + "order": 1, + "kind": "mirred", + "mirred_action": "redirect", + "direction": "ingress", + "index": 1, + "stats": { + "packets": 1 + }, + "not_in_hw": true + } + ] + } + ], + "teardown": [ + "$TC qdisc del dev $DEV1 clsact", + "$TC qdisc del dev $DUMMY clsact" + ] } - ] From 0f6e00aa5f652f5653e0039b9c9a8835f4b4174b Mon Sep 17 00:00:00 2001 From: Victor Nogueira Date: Mon, 25 May 2026 08:25:56 -0400 Subject: [PATCH 9/9] selftests/tc-testing: Add netem test case exercising loops Add a netem nested duplicate test case to validate that it won't cause an infinite loop Acked-by: Jamal Hadi Salim Acked-by: Stephen Hemminger Signed-off-by: Victor Nogueira Link: https://patch.msgid.link/20260525122556.973584-10-jhs@mojatatu.com Signed-off-by: Paolo Abeni --- .../tc-testing/tc-tests/qdiscs/netem.json | 33 ++++++++++++++++++- 1 file changed, 32 insertions(+), 1 deletion(-) diff --git a/tools/testing/selftests/tc-testing/tc-tests/qdiscs/netem.json b/tools/testing/selftests/tc-testing/tc-tests/qdiscs/netem.json index 3c4444961488..472b672a600d 100644 --- a/tools/testing/selftests/tc-testing/tc-tests/qdiscs/netem.json +++ b/tools/testing/selftests/tc-testing/tc-tests/qdiscs/netem.json @@ -336,5 +336,36 @@ "teardown": [ "$TC qdisc del dev $DUMMY handle 1: root" ] - } + }, + { + "id": "8c17", + "name": "Test netem's recursive duplicate", + "category": [ + "qdisc", + "netem" + ], + "plugins": { + "requires": "nsPlugin" + }, + "setup": [ + "$IP link set dev $DUMMY up || true", + "$IP addr add 10.10.11.10/24 dev $DUMMY || true", + "$TC qdisc add dev $DUMMY root handle 1: netem limit 1000 duplicate 100%", + "$TC qdisc add dev $DUMMY parent 1: handle 2: netem limit 1000 duplicate 100%" + ], + "cmdUnderTest": "ping -c 1 10.10.11.11 -W 0.01", + "expExitCode": "1", + "verifyCmd": "$TC -s -j qdisc ls dev $DUMMY root", + "matchJSON": [ + { + "kind": "netem", + "handle": "1:", + "bytes": 294, + "packets": 3 + } + ], + "teardown": [ + "$TC qdisc del dev $DUMMY handle 1: root" + ] + } ]