netdev - [PATCH net-next v2 5/5] net/sched: flower: Consider the number of tags for vlan filters

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Date:   Tue, 12 Apr 2022 13:02:36 +0300
From:   Boris Sukholitko <boris.sukholitko@...adcom.com>
To:     netdev@...r.kernel.org, "David S . Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Jamal Hadi Salim <jhs@...atatu.com>,
        Cong Wang <xiyou.wangcong@...il.com>,
        Jiri Pirko <jiri@...nulli.us>,
        "Gustavo A . R . Silva" <gustavoars@...nel.org>,
        Vladimir Oltean <vladimir.oltean@....com>,
        Eric Dumazet <edumazet@...gle.com>,
        zhang kai <zhangkaiheb@....com>,
        Yoshiki Komachi <komachi.yoshiki@...il.com>
Cc:     Ilya Lifshits <ilya.lifshits@...adcom.com>,
        Boris Sukholitko <boris.sukholitko@...adcom.com>
Subject: [PATCH net-next v2 5/5] net/sched: flower: Consider the number of tags for vlan filters

Currently the existence of vlan filters is conditional on the vlan
protocol being matched in the tc rule. I.e. the following rule:

tc filter add dev eth1 ingress flower vlan_prio 5

is illegal because we lack protocol 802.1q in the rule.

Having the num_of_vlans filter configured removes this restriction. The
following rule becomes ok:

tc filter add dev eth1 ingress flower num_of_vlans 1 vlan_prio 5

because we know that the packet is single tagged.

We achieve the above by having is_vlan_key helper look at the number of
vlans in addition to the vlan ethertype. Outer tag vlan filters (e.g.
vlan_prio) require the number of vlan tags be greater than 0. Inner
filters (e.g. cvlan_prio) require the number of vlan tags be greater
than 1.

Number of vlans filter may cause ethertype to be set to 0. Check this in
fl_set_key_vlan.

Signed-off-by: Boris Sukholitko <boris.sukholitko@...adcom.com>
---
 net/sched/cls_flower.c | 24 ++++++++++++++++--------
 1 file changed, 16 insertions(+), 8 deletions(-)

diff --git a/net/sched/cls_flower.c b/net/sched/cls_flower.c
index fafb74198c8d..9bf15b44292c 100644
--- a/net/sched/cls_flower.c
+++ b/net/sched/cls_flower.c
@@ -1029,8 +1029,10 @@ static void fl_set_key_vlan(struct nlattr **tb,
 			VLAN_PRIORITY_MASK;
 		key_mask->vlan_priority = VLAN_PRIORITY_MASK;
 	}
-	key_val->vlan_tpid = ethertype;
-	key_mask->vlan_tpid = cpu_to_be16(~0);
+	if (ethertype) {
+		key_val->vlan_tpid = ethertype;
+		key_mask->vlan_tpid = cpu_to_be16(~0);
+	}
 }
 
 static void fl_set_key_flag(u32 flower_key, u32 flower_mask,
@@ -1576,13 +1578,18 @@ static int fl_set_key_ct(struct nlattr **tb,
 }
 
 static bool is_vlan_key(struct nlattr *tb, __be16 *ethertype,
-			struct fl_flow_key *key, struct fl_flow_key *mask)
+			struct fl_flow_key *key, struct fl_flow_key *mask,
+			int vthresh)
 {
-	if (!tb)
-		return false;
+	const bool good_num_of_vlans = key->num_of_vlans.num_of_vlans > vthresh;
+
+	if (!tb) {
+		*ethertype = 0;
+		return good_num_of_vlans;
+	}
 
 	*ethertype = nla_get_be16(tb);
-	if (eth_type_vlan(*ethertype))
+	if (good_num_of_vlans || eth_type_vlan(*ethertype))
 		return true;
 
 	key->basic.n_proto = *ethertype;
@@ -1617,12 +1624,13 @@ static int fl_set_key(struct net *net, struct nlattr **tb,
 		       TCA_FLOWER_UNSPEC,
 		       sizeof(key->num_of_vlans));
 
-	if (is_vlan_key(tb[TCA_FLOWER_KEY_ETH_TYPE], &ethertype, key, mask)) {
+	if (is_vlan_key(tb[TCA_FLOWER_KEY_ETH_TYPE], &ethertype, key, mask, 0)) {
 		fl_set_key_vlan(tb, ethertype, TCA_FLOWER_KEY_VLAN_ID,
 				TCA_FLOWER_KEY_VLAN_PRIO, &key->vlan,
 				&mask->vlan);
 
-		if (is_vlan_key(tb[TCA_FLOWER_KEY_VLAN_ETH_TYPE], &ethertype, key, mask)) {
+		if (is_vlan_key(tb[TCA_FLOWER_KEY_VLAN_ETH_TYPE],
+				&ethertype, key, mask, 1)) {
 			fl_set_key_vlan(tb, ethertype,
 					TCA_FLOWER_KEY_CVLAN_ID,
 					TCA_FLOWER_KEY_CVLAN_PRIO,
-- 
2.29.2


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