tun: Proper handling of IPv6 header in tun driver when TUN_NO_PI is set

By default, tun.c running in TUN_TUN_DEV mode will set the protocol of
packet to IPv4 if TUN_NO_PI is set. My program failed to work when I
assumed that the driver will check the first nibble of packet,
determine IP version and set the appropriate protocol.

Signed-off-by: Ang Way Chuang <wcang@nav6.org>
Acked-by: Max Krasnyansky <maxk@qualcomm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 0ce07a3..7ab94c8 100644 (file)
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -313,6 +313,21 @@ static __inline__ ssize_t tun_get_user(struct tun_struct *tun, struct iovec *iv,
 
        switch (tun->flags & TUN_TYPE_MASK) {
        case TUN_TUN_DEV:
+               if (tun->flags & TUN_NO_PI) {
+                       switch (skb->data[0] & 0xf0) {
+                       case 0x40:
+                               pi.proto = htons(ETH_P_IP);
+                               break;
+                       case 0x60:
+                               pi.proto = htons(ETH_P_IPV6);
+                               break;
+                       default:
+                               tun->dev->stats.rx_dropped++;
+                               kfree_skb(skb);
+                               return -EINVAL;
+                       }
+               }
+
                skb_reset_mac_header(skb);
                skb->protocol = pi.proto;
                skb->dev = tun->dev;