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net/sched: Prohibit regrafting ingress or clsact Qdiscs

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[ 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: 1da177e4c3 ("Linux-2.6.12-rc2")
Fixes: 1f211a1b92 ("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>
This commit is contained in:
Peilin Ye 2023-05-29 12:54:26 -07:00 • committed by Greg Kroah-Hartman
parent 80b20d528a
commit 2188c0f095
1 changed files with 5 additions and 0 deletions
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5
net/sched/sch_api.c
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@ -1579,6 +1579,11 @@ replay:
NL_SET_ERR_MSG(extack, "Invalid qdisc name"); NL_SET_ERR_MSG(extack, "Invalid qdisc name");
return -EINVAL; return -EINVAL;
} }
if (q->flags & TCQ_F_INGRESS) {
NL_SET_ERR_MSG(extack,
"Cannot regraft ingress or clsact Qdiscs");
return -EINVAL;
}
if (q == p || if (q == p ||
(p && check_loop(q, p, 0))) { (p && check_loop(q, p, 0))) {
NL_SET_ERR_MSG(extack, "Qdisc parent/child loop detected"); NL_SET_ERR_MSG(extack, "Qdisc parent/child loop detected");