netdev - [net-next 1/2] dummy: add device MTU validation check

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Date:   Thu, 21 Sep 2017 21:32:01 +0800
From:   Zhang Shengju <zhangshengju@...s.chinamobile.com>
To:     davem@...emloft.net, willemb@...gle.com,
        stephen@...workplumber.org, netdev@...r.kernel.org
Subject: [net-next 1/2] dummy: add device MTU validation check

Currently, any mtu value can be assigned when adding a new dummy device:
[~]# ip link add name dummy1 mtu 100000 type dummy
[~]# ip link show dummy1
15: dummy1: <BROADCAST,NOARP> mtu 100000 qdisc noop state DOWN mode DEFAULT group default qlen 1000
    link/ether 0a:61:6b:16:14:ce brd ff:ff:ff:ff:ff:ff

This patch adds device MTU validation check.

Signed-off-by: Zhang Shengju <zhangshengju@...s.chinamobile.com>
---
 drivers/net/dummy.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/net/dummy.c b/drivers/net/dummy.c
index e31ab3b..0276b2b 100644
--- a/drivers/net/dummy.c
+++ b/drivers/net/dummy.c
@@ -365,6 +365,14 @@ static int dummy_validate(struct nlattr *tb[], struct nlattr *data[],
 		if (!is_valid_ether_addr(nla_data(tb[IFLA_ADDRESS])))
 			return -EADDRNOTAVAIL;
 	}
+
+	if (tb[IFLA_MTU]) {
+		u32 mtu = nla_get_u32(tb[IFLA_MTU]);
+
+		if (mtu > ETH_MAX_MTU)
+			return -EINVAL;
+	}
+
 	return 0;
 }
 
-- 
1.8.3.1