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From:   Peilin Ye <yepeilin.cs@gmail.com>
To:     "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>,
        Jamal Hadi Salim <jhs@mojatatu.com>,
        Cong Wang <xiyou.wangcong@gmail.com>,
        Jiri Pirko <jiri@resnulli.us>
Cc:     Peilin Ye <peilin.ye@bytedance.com>,
        Daniel Borkmann <daniel@iogearbox.net>,
        John Fastabend <john.r.fastabend@intel.com>,
        Vlad Buslov <vladbu@mellanox.com>,
        Pedro Tammela <pctammela@mojatatu.com>,
        Hillf Danton <hdanton@sina.com>, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org, Cong Wang <cong.wang@bytedance.com>,
        Peilin Ye <yepeilin.cs@gmail.com>
Subject: [PATCH net 3/6] net/sched: Reserve TC_H_INGRESS (TC_H_CLSACT) for ingress (clsact) Qdiscs
Date:   Fri,  5 May 2023 17:14:07 -0700
Message-Id: <9969180f9219ed18656d8f3c92e717f6eb398aa1.1683326865.git.peilin.ye@bytedance.com>
In-Reply-To: <cover.1683326865.git.peilin.ye@bytedance.com>
References: <cover.1683326865.git.peilin.ye@bytedance.com>
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Currently it is possible to add e.g. an HTB Qdisc under ffff:fff1
(TC_H_INGRESS, TC_H_CLSACT):

  $ ip link add name ifb0 type ifb
  $ tc qdisc add dev ifb0 parent ffff:fff1 htb
  $ tc qdisc add dev ifb0 clsact
  Error: Exclusivity flag on, cannot modify.
  $ drgn
  ...
  >>> ifb0 = netdev_get_by_name(prog, "ifb0")
  >>> qdisc = ifb0.ingress_queue.qdisc_sleeping
  >>> print(qdisc.ops.id.string_().decode())
  htb
  >>> qdisc.flags.value_() # TCQ_F_INGRESS
  2

Only allow ingress and clsact Qdiscs under ffff:fff1.  Return -EINVAL
for everything else.  Make TCQ_F_INGRESS a static flag of ingress and
clsact Qdiscs.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Fixes: 1f211a1b929c ("net, sched: add clsact qdisc")
Signed-off-by: Peilin Ye <peilin.ye@bytedance.com>
---
 net/sched/sch_api.c     | 7 ++++++-
 net/sched/sch_ingress.c | 4 ++--
 2 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/net/sched/sch_api.c b/net/sched/sch_api.c
index fdb8f429333d..383195955b7d 100644
--- a/net/sched/sch_api.c
+++ b/net/sched/sch_api.c
@@ -1252,7 +1252,12 @@ static struct Qdisc *qdisc_create(struct net_device *dev,
 	sch->parent = parent;
 
 	if (handle == TC_H_INGRESS) {
-		sch->flags |= TCQ_F_INGRESS;
+		if (!(sch->flags & TCQ_F_INGRESS)) {
+			NL_SET_ERR_MSG(extack,
+				       "Specified parent ID is reserved for ingress and clsact Qdiscs");
+			err = -EINVAL;
+			goto err_out3;
+		}
 		handle = TC_H_MAKE(TC_H_INGRESS, 0);
 	} else {
 		if (handle == 0) {
diff --git a/net/sched/sch_ingress.c b/net/sched/sch_ingress.c
index 13218a1fe4a5..caea51e0d4e9 100644
--- a/net/sched/sch_ingress.c
+++ b/net/sched/sch_ingress.c
@@ -137,7 +137,7 @@ static struct Qdisc_ops ingress_qdisc_ops __read_mostly = {
 	.cl_ops			=	&ingress_class_ops,
 	.id			=	"ingress",
 	.priv_size		=	sizeof(struct ingress_sched_data),
-	.static_flags		=	TCQ_F_CPUSTATS,
+	.static_flags		=	TCQ_F_INGRESS | TCQ_F_CPUSTATS,
 	.init			=	ingress_init,
 	.destroy		=	ingress_destroy,
 	.dump			=	ingress_dump,
@@ -275,7 +275,7 @@ static struct Qdisc_ops clsact_qdisc_ops __read_mostly = {
 	.cl_ops			=	&clsact_class_ops,
 	.id			=	"clsact",
 	.priv_size		=	sizeof(struct clsact_sched_data),
-	.static_flags		=	TCQ_F_CPUSTATS,
+	.static_flags		=	TCQ_F_INGRESS | TCQ_F_CPUSTATS,
 	.init			=	clsact_init,
 	.destroy		=	clsact_destroy,
 	.dump			=	ingress_dump,
-- 
2.20.1