From 429c3be8a5e2695b5b92a6a12361eb89eb185495 Mon Sep 17 00:00:00 2001
From: Maxim Mikityanskiy <maximmi@nvidia.com>
Date: Tue, 25 Jan 2022 12:06:54 +0200
Subject: [PATCH] sch_htb: Fail on unsupported parameters when offload is requested
Git-commit: 429c3be8a5e2695b5b92a6a12361eb89eb185495
Patch-mainline: v5.17-rc2
References: git-fixes

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>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 net/sched/sch_htb.c | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/net/sched/sch_htb.c b/net/sched/sch_htb.c
index 9267922ea9c3..23a9d6242429 100644
--- 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],
-- 
2.31.1