netdev - [PATCH net-next v2 2/5] net: openvswitch: set max limitation to meters

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Message-Id: <1587032223-49460-3-git-send-email-xiangxia.m.yue@gmail.com>
Date:   Thu, 16 Apr 2020 18:17:00 +0800
From:   xiangxia.m.yue@...il.com
To:     pshelar@....org, azhou@....org, blp@....org, u9012063@...il.com
Cc:     netdev@...r.kernel.org, dev@...nvswitch.org,
        Tonghao Zhang <xiangxia.m.yue@...il.com>
Subject: [PATCH net-next v2 2/5] net: openvswitch: set max limitation to meters

From: Tonghao Zhang <xiangxia.m.yue@...il.com>

Don't allow user to create meter unlimitedly,
which may cause to consume a large amount of kernel memory.
The 200,000 meters may be fine in general case.

Cc: Pravin B Shelar <pshelar@....org>
Cc: Andy Zhou <azhou@....org>
Signed-off-by: Tonghao Zhang <xiangxia.m.yue@...il.com>
---
 net/openvswitch/meter.c | 21 +++++++++++++++------
 net/openvswitch/meter.h |  1 +
 2 files changed, 16 insertions(+), 6 deletions(-)

diff --git a/net/openvswitch/meter.c b/net/openvswitch/meter.c
index 494a0014ecd8..1b6776f9c109 100644
--- a/net/openvswitch/meter.c
+++ b/net/openvswitch/meter.c
@@ -137,6 +137,7 @@ static int attach_meter(struct dp_meter_table *tbl, struct dp_meter *meter)
 {
 	struct dp_meter_instance *ti = rcu_dereference_ovsl(tbl->ti);
 	u32 hash = meter_hash(ti, meter->id);
+	int err;
 
 	/*
 	 * In generally, slot selected should be empty, because
@@ -148,16 +149,24 @@ static int attach_meter(struct dp_meter_table *tbl, struct dp_meter *meter)
 	dp_meter_instance_insert(ti, meter);
 
 	/* That function is thread-safe. */
-	if (++tbl->count >= ti->n_meters)
-		if (dp_meter_instance_realloc(tbl, ti->n_meters * 2))
-			goto expand_err;
+	tbl->count++;
+	if (tbl->count > DP_METER_NUM_MAX) {
+		err = -EFBIG;
+		goto attach_err;
+	}
+
+	if (tbl->count >= ti->n_meters &&
+	    dp_meter_instance_realloc(tbl, ti->n_meters * 2)) {
+		err = -ENOMEM;
+		goto attach_err;
+	}
 
 	return 0;
 
-expand_err:
+attach_err:
 	dp_meter_instance_remove(ti, meter);
 	tbl->count--;
-	return -ENOMEM;
+	return err;
 }
 
 static void detach_meter(struct dp_meter_table *tbl, struct dp_meter *meter)
@@ -264,7 +273,7 @@ static int ovs_meter_cmd_features(struct sk_buff *skb, struct genl_info *info)
 	if (IS_ERR(reply))
 		return PTR_ERR(reply);
 
-	if (nla_put_u32(reply, OVS_METER_ATTR_MAX_METERS, U32_MAX) ||
+	if (nla_put_u32(reply, OVS_METER_ATTR_MAX_METERS, DP_METER_NUM_MAX) ||
 	    nla_put_u32(reply, OVS_METER_ATTR_MAX_BANDS, DP_MAX_BANDS))
 		goto nla_put_failure;
 
diff --git a/net/openvswitch/meter.h b/net/openvswitch/meter.h
index d91940383bbe..cdfc6b9dbd42 100644
--- a/net/openvswitch/meter.h
+++ b/net/openvswitch/meter.h
@@ -19,6 +19,7 @@ struct datapath;
 
 #define DP_MAX_BANDS		1
 #define DP_METER_ARRAY_SIZE_MIN	(1ULL << 10)
+#define DP_METER_NUM_MAX	(200000ULL)
 
 struct dp_meter_band {
 	u32 type;
-- 
2.23.0