Re: [PATCH v5 net 3/6] net/sched: Reserve TC_H_INGRESS (TC_H_CLSACT) for ingress (clsact) Qdiscs

[Pedro Tammela]

On 23/05/2023 22:19, Peilin Ye wrote:
> From: Peilin Ye <peilin.ye@xxxxxxxxxxxxx>
>
> 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")
> Reviewed-by: Jamal Hadi Salim <jhs@xxxxxxxxxxxx>
> Acked-by: Jamal Hadi Salim <jhs@xxxxxxxxxxxx>
> Signed-off-by: Peilin Ye <peilin.ye@xxxxxxxxxxxxx>

Tested-by: Pedro Tammela <pctammela@xxxxxxxxxxxx>

> ---
> change in v3, v4:
>    - add in-body From: tag
>
>   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 35963929e117..e43a45499372 100644
> --- a/net/sched/sch_ingress.c
> +++ b/net/sched/sch_ingress.c
> @@ -140,7 +140,7 @@ 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,
> @@ -281,7 +281,7 @@ 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,