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>

1 files changed, 15 insertions, 0 deletions

diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 0ce07a339c7e..7ab94c825b57 100644
--- 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;