sch_htb: Fail on unsupported parameters when offload is requested

BugLink: https://bugs.launchpad.net/bugs/1959879
[ Upstream commit 429c3be8a5e2695b5b92a6a12361eb89eb185495 ]

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Paolo Pisati <paolo.pisati@canonical.com>

diff --git a/net/sched/sch_htb.c b/net/sched/sch_htb.c
index 5067a6e5d4fdedccfc74acc5b71f99349f67ac35..5cbc32fee8674650abe4f067a46deaceafd968f9 100644 (file)
--- a/net/sched/sch_htb.c
+++ b/net/sched/sch_htb.c
@@ -1803,6 +1803,26 @@ 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],