From: Peilin Ye peilin.ye@bytedance.com
[ Upstream commit 9de95df5d15baa956c2b70b9e794842e790a8a13 ]
Currently, after creating an ingress (or clsact) Qdisc and grafting it under TC_H_INGRESS (TC_H_CLSACT), it is possible to graft it again under e.g. a TBF Qdisc:
$ ip link add ifb0 type ifb $ tc qdisc add dev ifb0 handle 1: root tbf rate 20kbit buffer 1600 limit 3000 $ tc qdisc add dev ifb0 clsact $ tc qdisc link dev ifb0 handle ffff: parent 1:1 $ tc qdisc show dev ifb0 qdisc tbf 1: root refcnt 2 rate 20Kbit burst 1600b lat 560.0ms qdisc clsact ffff: parent ffff:fff1 refcnt 2 ^^^^^^^^
clsact's refcount has increased: it is now grafted under both TC_H_CLSACT and 1:1.
ingress and clsact Qdiscs should only be used under TC_H_INGRESS (TC_H_CLSACT). Prohibit regrafting them.
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Fixes: 1f211a1b929c ("net, sched: add clsact qdisc") Tested-by: Pedro Tammela pctammela@mojatatu.com Acked-by: Jamal Hadi Salim jhs@mojatatu.com Reviewed-by: Jamal Hadi Salim jhs@mojatatu.com Reviewed-by: Vlad Buslov vladbu@nvidia.com Signed-off-by: Peilin Ye peilin.ye@bytedance.com Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- net/sched/sch_api.c | 5 +++++ 1 file changed, 5 insertions(+)
diff --git a/net/sched/sch_api.c b/net/sched/sch_api.c index b7c230f9c5b19..a686d7cae5130 100644 --- a/net/sched/sch_api.c +++ b/net/sched/sch_api.c @@ -1594,6 +1594,11 @@ static int tc_modify_qdisc(struct sk_buff *skb, struct nlmsghdr *n, NL_SET_ERR_MSG(extack, "Invalid qdisc name"); return -EINVAL; } + if (q->flags & TCQ_F_INGRESS) { + NL_SET_ERR_MSG(extack, + "Cannot regraft ingress or clsact Qdiscs"); + return -EINVAL; + } if (q == p || (p && check_loop(q, p, 0))) { NL_SET_ERR_MSG(extack, "Qdisc parent/child loop detected");