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-rw-r--r--drivers/net/tun.c14
1 files changed, 14 insertions, 0 deletions
diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index d279151..d8b8e68 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -172,6 +172,18 @@ tun_net_mclist(struct net_device *dev)
}
}
+#define MIN_MTU 68
+#define MAX_MTU 65535
+
+static int
+tun_net_change_mtu(struct net_device *dev, int new_mtu)
+{
+ if (new_mtu < MIN_MTU || new_mtu + dev->hard_header_len > MAX_MTU)
+ return -EINVAL;
+ dev->mtu = new_mtu;
+ return 0;
+}
+
/* Initialize net device. */
static void tun_net_init(struct net_device *dev)
{
@@ -183,6 +195,7 @@ static void tun_net_init(struct net_device *dev)
dev->hard_header_len = 0;
dev->addr_len = 0;
dev->mtu = 1500;
+ dev->change_mtu = tun_net_change_mtu;
/* Zero header length */
dev->type = ARPHRD_NONE;
@@ -195,6 +208,7 @@ static void tun_net_init(struct net_device *dev)
dev->set_multicast_list = tun_net_mclist;
ether_setup(dev);
+ dev->change_mtu = tun_net_change_mtu;
/* random address already created for us by tun_set_iff, use it */
memcpy(dev->dev_addr, tun->dev_addr, min(sizeof(tun->dev_addr), sizeof(dev->dev_addr)) );
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