Allow setting MTU on interface creation

2 files changed, 14 insertions, 1 deletions

diff --git a/fastd.c b/fastd.c
index 98b6565..7373e86 100644
--- a/fastd.c
+++ b/fastd.c
@@ -63,6 +63,9 @@
 #define FASTD_HEADROOM \
 	(ETH_HLEN + sizeof(struct ipv6hdr) + sizeof(struct udphdr) + 24)
 
+#define FASTD_DEFAULT_MTU 1500
+#define FASTD_MIN_MTU 68
+
 
 static LIST_HEAD(fastd_list);
 static struct workqueue_struct *fastd_workqueue;
@@ -195,7 +198,6 @@ static void fastd_netdev_init(struct net_device *dev)
 
 		dev->addr_len = 0;
 		dev->hard_header_len = FASTD_HEADROOM;
-		dev->mtu = 1500;
 
 		dev->type = ARPHRD_NONE;
 		dev->flags = IFF_POINTOPOINT | IFF_NOARP | IFF_MULTICAST;
@@ -221,6 +223,7 @@ static int fastd_cmd_create(struct sk_buff *skb, struct genl_info *info)
 	struct net_device *dev;
 	struct fastd_struct *fastd;
 	u16 mode;
+	u16 mtu = FASTD_DEFAULT_MTU;
 	const char *name = "fastd%d";
 	int err;
 
@@ -234,6 +237,13 @@ static int fastd_cmd_create(struct sk_buff *skb, struct genl_info *info)
 	if (mode != FASTD_MODE_ETH && mode != FASTD_MODE_IP)
 		return -EINVAL;
 
+	if (info->attrs[FASTD_A_MTU])
+		mtu = nla_get_u16(info->attrs[FASTD_A_MTU]);
+
+	if (mtu < FASTD_MIN_MTU)
+		return -EINVAL;
+
+
 	if (info->attrs[FASTD_A_IFNAME])
 		name = nla_data(info->attrs[FASTD_A_IFNAME]);
 
@@ -257,6 +267,7 @@ static int fastd_cmd_create(struct sk_buff *skb, struct genl_info *info)
 	INIT_WORK(&fastd->destroy_work, fastd_destroy_work);
 
 	fastd_netdev_init(dev);
+	dev->mtu = mtu;
 
 	rtnl_lock();
 	err = register_netdevice(dev);
@@ -284,6 +295,7 @@ err_module_put:
 static struct nla_policy fastd_nl_policy[__FASTD_A_MAX] = {
 	[FASTD_A_IFNAME]	= { .type = NLA_NUL_STRING, .len = IFNAMSIZ-1 },
 	[FASTD_A_MODE]		= { .type = NLA_U16 },
+	[FASTD_A_MTU]		= { .type = NLA_U16 },
 };
 
 static struct genl_ops fastd_nl_ops[] = {
diff --git a/fastd.h b/fastd.h
index 026846a..5c3ca86 100644
--- a/fastd.h
+++ b/fastd.h
@@ -53,6 +53,7 @@ enum {
 	FASTD_A_UNSPEC,
 	FASTD_A_IFNAME,
 	FASTD_A_MODE,
+	FASTD_A_MTU,
 	__FASTD_A_MAX
 };