netdev - [PATCH net-next v2 4/4] net/sched: cls_route: make netlink errors meaningful

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Message-Id: <20230825155148.659895-5-pctammela@mojatatu.com>
Date: Fri, 25 Aug 2023 12:51:48 -0300
From: Pedro Tammela <pctammela@...atatu.com>
To: netdev@...r.kernel.org
Cc: jhs@...atatu.com,
	xiyou.wangcong@...il.com,
	jiri@...nulli.us,
	davem@...emloft.net,
	edumazet@...gle.com,
	kuba@...nel.org,
	pabeni@...hat.com,
	shuah@...nel.org,
	victor@...atatu.com,
	Pedro Tammela <pctammela@...atatu.com>
Subject: [PATCH net-next v2 4/4] net/sched: cls_route: make netlink errors meaningful

Use netlink extended ack and parsing policies to return more meaningful
errors instead of the relying solely on errnos.

Signed-off-by: Pedro Tammela <pctammela@...atatu.com>
---
 net/sched/cls_route.c | 27 +++++++++++++++------------
 1 file changed, 15 insertions(+), 12 deletions(-)

diff --git a/net/sched/cls_route.c b/net/sched/cls_route.c
index 1e20bbd687f1..b34cf02c6c51 100644
--- a/net/sched/cls_route.c
+++ b/net/sched/cls_route.c
@@ -400,30 +400,32 @@ static int route4_set_parms(struct net *net, struct tcf_proto *tp,
 		if (new && handle & 0x8000)
 			return -EINVAL;
 		to = nla_get_u32(tb[TCA_ROUTE4_TO]);
-		if (to > 0xFF)
-			return -EINVAL;
 		nhandle = to;
 	}
 
+	if (tb[TCA_ROUTE4_FROM] && tb[TCA_ROUTE4_IIF]) {
+		NL_SET_ERR_MSG(extack,
+			       "'from' and 'fromif' are mutually exclusive");
+		return -EINVAL;
+	}
+
 	if (tb[TCA_ROUTE4_FROM]) {
-		if (tb[TCA_ROUTE4_IIF])
-			return -EINVAL;
 		id = nla_get_u32(tb[TCA_ROUTE4_FROM]);
-		if (id > 0xFF)
-			return -EINVAL;
 		nhandle |= id << 16;
 	} else if (tb[TCA_ROUTE4_IIF]) {
 		id = nla_get_u32(tb[TCA_ROUTE4_IIF]);
-		if (id > 0x7FFF)
-			return -EINVAL;
 		nhandle |= (id | 0x8000) << 16;
 	} else
 		nhandle |= 0xFFFF << 16;
 
 	if (handle && new) {
 		nhandle |= handle & 0x7F00;
-		if (nhandle != handle)
+		if (nhandle != handle) {
+			NL_SET_ERR_MSG_FMT(extack,
+					   "Unexpected handle %x (expected %x)",
+					   handle, nhandle);
 			return -EINVAL;
+		}
 	}
 
 	if (!nhandle) {
@@ -478,7 +480,6 @@ static int route4_change(struct net *net, struct sk_buff *in_skb,
 	struct route4_filter __rcu **fp;
 	struct route4_filter *fold, *f1, *pfp, *f = NULL;
 	struct route4_bucket *b;
-	struct nlattr *opt = tca[TCA_OPTIONS];
 	struct nlattr *tb[TCA_ROUTE4_MAX + 1];
 	unsigned int h, th;
 	int err;
@@ -489,10 +490,12 @@ static int route4_change(struct net *net, struct sk_buff *in_skb,
 		return -EINVAL;
 	}
 
-	if (opt == NULL)
+	if (NL_REQ_ATTR_CHECK(extack, NULL, tca, TCA_OPTIONS)) {
+		NL_SET_ERR_MSG_MOD(extack, "missing options");
 		return -EINVAL;
+	}
 
-	err = nla_parse_nested_deprecated(tb, TCA_ROUTE4_MAX, opt,
+	err = nla_parse_nested_deprecated(tb, TCA_ROUTE4_MAX, tca[TCA_OPTIONS],
 					  route4_policy, NULL);
 	if (err < 0)
 		return err;
-- 
2.39.2