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From:   Jamal Hadi Salim <jhs@mojatatu.com>
Date:   Mon, 8 May 2023 07:23:54 -0400
Message-ID: <CAM0EoMnZGmRh87bwcRxgB3ZZChWmhHniA7M-ptXt7AKXtuY-Bg@mail.gmail.com>
Subject: Re: [PATCH net 3/6] net/sched: Reserve TC_H_INGRESS (TC_H_CLSACT) for
 ingress (clsact) Qdiscs
To:     Peilin Ye <yepeilin.cs@gmail.com>
Cc:     "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>,
        Cong Wang <xiyou.wangcong@gmail.com>,
        Jiri Pirko <jiri@resnulli.us>,
        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>
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On Fri, May 5, 2023 at 8:14=E2=80=AFPM Peilin Ye <yepeilin.cs@gmail.com> wr=
ote:
>
> 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 =3D netdev_get_by_name(prog, "ifb0")
>   >>> qdisc =3D 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>

Reviewed-by: Jamal Hadi Salim <jhs@mojatatu.com>
Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>


cheers,
jamal

> ---
>  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_devic=
e *dev,
>         sch->parent =3D parent;
>
>         if (handle =3D=3D TC_H_INGRESS) {
> -               sch->flags |=3D TCQ_F_INGRESS;
> +               if (!(sch->flags & TCQ_F_INGRESS)) {
> +                       NL_SET_ERR_MSG(extack,
> +                                      "Specified parent ID is reserved f=
or ingress and clsact Qdiscs");
> +                       err =3D -EINVAL;
> +                       goto err_out3;
> +               }
>                 handle =3D TC_H_MAKE(TC_H_INGRESS, 0);
>         } else {
>                 if (handle =3D=3D 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_most=
ly =3D {
>         .cl_ops                 =3D       &ingress_class_ops,
>         .id                     =3D       "ingress",
>         .priv_size              =3D       sizeof(struct ingress_sched_dat=
a),
> -       .static_flags           =3D       TCQ_F_CPUSTATS,
> +       .static_flags           =3D       TCQ_F_INGRESS | TCQ_F_CPUSTATS,
>         .init                   =3D       ingress_init,
>         .destroy                =3D       ingress_destroy,
>         .dump                   =3D       ingress_dump,
> @@ -275,7 +275,7 @@ static struct Qdisc_ops clsact_qdisc_ops __read_mostl=
y =3D {
>         .cl_ops                 =3D       &clsact_class_ops,
>         .id                     =3D       "clsact",
>         .priv_size              =3D       sizeof(struct clsact_sched_data=
),
> -       .static_flags           =3D       TCQ_F_CPUSTATS,
> +       .static_flags           =3D       TCQ_F_INGRESS | TCQ_F_CPUSTATS,
>         .init                   =3D       clsact_init,
>         .destroy                =3D       clsact_destroy,
>         .dump                   =3D       ingress_dump,
> --
> 2.20.1
>