netdev - Re: [PATCH ipsec v2] vti[6]: fix packet tx through bpf

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Message-ID: <20200204114604.GA59185@bistromath.localdomain>
Date:   Tue, 4 Feb 2020 12:46:04 +0100
From:   Sabrina Dubroca <sd@...asysnail.net>
To:     Nicolas Dichtel <nicolas.dichtel@...nd.com>
Cc:     steffen.klassert@...unet.com, davem@...emloft.net,
        netdev@...r.kernel.org
Subject: Re: [PATCH ipsec v2] vti[6]: fix packet tx through bpf_redirect() in
 XinY cases

Hi,

2020-02-04, 11:52:48 +0100, Nicolas Dichtel wrote:
> I forgot the 4in6/6in4 cases in my previous patch. Let's fix them.
> 
> Fixes: 95224166a903 ("vti[6]: fix packet tx through bpf_redirect()")
> Signed-off-by: Nicolas Dichtel <nicolas.dichtel@...nd.com>
> ---
> 
> v1 -> v2:
>  - fix compilation when IPv6 is disabled
> 
>  net/ipv4/ip_vti.c  | 38 ++++++++++++++++++++++++++++++--------
>  net/ipv6/ip6_vti.c | 32 +++++++++++++++++++++++++-------
>  2 files changed, 55 insertions(+), 15 deletions(-)
> 
> diff --git a/net/ipv4/ip_vti.c b/net/ipv4/ip_vti.c
> index 37cddd18f282..1b4e6f298648 100644
> --- a/net/ipv4/ip_vti.c
> +++ b/net/ipv4/ip_vti.c
> @@ -187,17 +187,39 @@ static netdev_tx_t vti_xmit(struct sk_buff *skb, struct net_device *dev,
>  	int mtu;
>  
>  	if (!dst) {
> -		struct rtable *rt;
> -
> -		fl->u.ip4.flowi4_oif = dev->ifindex;
> -		fl->u.ip4.flowi4_flags |= FLOWI_FLAG_ANYSRC;
> -		rt = __ip_route_output_key(dev_net(dev), &fl->u.ip4);
> -		if (IS_ERR(rt)) {
> +		switch (skb->protocol) {
> +		case htons(ETH_P_IP): {
> +			struct rtable *rt;
> +
> +			fl->u.ip4.flowi4_oif = dev->ifindex;
> +			fl->u.ip4.flowi4_flags |= FLOWI_FLAG_ANYSRC;
> +			rt = __ip_route_output_key(dev_net(dev), &fl->u.ip4);
> +			if (IS_ERR(rt)) {
> +				dev->stats.tx_carrier_errors++;
> +				goto tx_error_icmp;
> +			}
> +			dst = &rt->dst;
> +			skb_dst_set(skb, dst);
> +			break;
> +		}
> +#if IS_ENABLED(CONFIG_IPV6)
> +		case htons(ETH_P_IPV6):
> +			fl->u.ip6.flowi6_oif = dev->ifindex;
> +			fl->u.ip6.flowi6_flags |= FLOWI_FLAG_ANYSRC;
> +			dst = ip6_route_output(dev_net(dev), NULL, &fl->u.ip6);

I don't think that works with CONFIG_IPV6=m and CONFIG_NET_IPVTI=y:

ld: net/ipv4/ip_vti.o: in function `ip6_route_output':
/home/sab/linux/net/./include/net/ip6_route.h:98: undefined reference to `ip6_route_output_flags'

You probably have to do like ipvlan did in commit 7f897db37b76
("ipvlan: fix building with modular IPV6").

-- 
Sabrina