sch_htb: Fail on unsupported parameters when offload is requested

The current implementation of HTB offload doesn't support some
parameters. Instead of ignoring them, actively return the EINVAL error
when they are set to non-defaults.

As this patch goes to stable, the driver API is not changed here. If
future drivers support more offload parameters, the checks can be moved
to the driver side.

Note that the buffer and cbuffer parameters are also not supported, but
the tc userspace tool assigns some default values derived from rate and
ceil, and identifying these defaults in sch_htb would be unreliable, so
they are still ignored.

Fixes: d03b195b5aa0 ("sch_htb: Hierarchical QoS hardware offload")
Reported-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Maxim Mikityanskiy <maximmi@nvidia.com>
Reviewed-by: Tariq Toukan <tariqt@nvidia.com>
Link: https://lore.kernel.org/r/20220125100654.424570-1-maximmi@nvidia.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/net/sched/sch_htb.c b/net/sched/sch_htb.c
index 9267922ea9c375dc555e8c17f9d9e9a90721330a..23a9d6242429f1f9fadd047602108daffe3708ea 100644 (file)
--- a/net/sched/sch_htb.c
+++ b/net/sched/sch_htb.c
@@ -1810,6 +1810,26 @@ static int htb_change_class(struct Qdisc *sch, u32 classid,
        if (!hopt->rate.rate || !hopt->ceil.rate)
                goto failure;
 
+       if (q->offload) {
+               /* Options not supported by the offload. */
+               if (hopt->rate.overhead || hopt->ceil.overhead) {
+                       NL_SET_ERR_MSG(extack, "HTB offload doesn't support the overhead parameter");
+                       goto failure;
+               }
+               if (hopt->rate.mpu || hopt->ceil.mpu) {
+                       NL_SET_ERR_MSG(extack, "HTB offload doesn't support the mpu parameter");
+                       goto failure;
+               }
+               if (hopt->quantum) {
+                       NL_SET_ERR_MSG(extack, "HTB offload doesn't support the quantum parameter");
+                       goto failure;
+               }
+               if (hopt->prio) {
+                       NL_SET_ERR_MSG(extack, "HTB offload doesn't support the prio parameter");
+                       goto failure;
+               }
+       }
+
        /* Keeping backward compatible with rate_table based iproute2 tc */
        if (hopt->rate.linklayer == TC_LINKLAYER_UNAWARE)
                qdisc_put_rtab(qdisc_get_rtab(&hopt->rate, tb[TCA_HTB_RTAB],