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Date: Fri, 06 Jun 2008 13:21:06 -0700
From: Max Krasnyanskiy <maxk@...lcomm.com>
To: Ang Way Chuang <wcang@...6.org>,
David Miller <davem@...emloft.net>,
"Zabele, Stephen (US SSA)" <steve.zabele@...systems.com>
CC: netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] NET: Proper handling of IPv6 header in tun driver when
TUN_NO_PI is set
Acked-by: Max Krasnyansky <maxk@...lcomm.com>
Dave, can you please add this patch to your tree.
--
Steve, this is what I meant by "we do not need extra copy_from_user". We
already do copy into the SKB and can parse the header right there.
Max
Ang Way Chuang wrote:
> 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.
>
> The test for this change was conducted on 2.6.24.7 kernel. But the diff
> is produced using git commit
> c3b25b32e8bef526cca748e1ba023c6bdd705a99. I couldn't test it on kernel
> version greater than 2.6.25 due to out of tree driver failing to
> compile. But tun_get_user doesn't change that much between 2.6.24 and
> 2.6.26, so it should work, I hope :-D. This patch is trivial because
> this problem can also be fixed by not using TUN_NO_PI.
>
> Signed-off-by: Ang Way Chuang <wcang@...6.org>
> ---
>
> diff --git a/drivers/net/tun.c b/drivers/net/tun.c
> index 0ce07a3..77964bc 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 = __constant_htons(ETH_P_IP);
> + break;
> + case 0x60:
> + pi.proto = __constant_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;
>
> --
>
--
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