With an IPsec tunnel without dedicated interface, netfilter sees locally
generated packets twice as they exit the physical interface: Once as "the
inner packet" with IPsec context attached and once as the encrypted
(ESP) packet.
With xfrm_interface, the inner packet did not traverse NF_INET_LOCAL_OUT
hook anymore, making it impossible to match on both inner header values
and associated IPsec data from that hook.
Fix this by looping packets transmitted from xfrm_interface through
NF_INET_LOCAL_OUT before passing them on to dst_output(), which makes
behaviour consistent again from netfilter's point of view.
Fixes: f203b76d78092 ("xfrm: Add virtual xfrm interfaces")
Signed-off-by: Phil Sutter <[email protected]>
---
net/xfrm/xfrm_interface.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/net/xfrm/xfrm_interface.c b/net/xfrm/xfrm_interface.c
index aa4cdcf69d471..24af61c95b4d4 100644
--- a/net/xfrm/xfrm_interface.c
+++ b/net/xfrm/xfrm_interface.c
@@ -317,7 +317,8 @@ xfrmi_xmit2(struct sk_buff *skb, struct net_device *dev, struct flowi *fl)
skb_dst_set(skb, dst);
skb->dev = tdev;
- err = dst_output(xi->net, skb->sk, skb);
+ err = NF_HOOK(skb_dst(skb)->ops->family, NF_INET_LOCAL_OUT, xi->net,
+ skb->sk, skb, NULL, skb_dst(skb)->dev, dst_output);
if (net_xmit_eval(err) == 0) {
struct pcpu_sw_netstats *tstats = this_cpu_ptr(dev->tstats);
--
2.28.0
On Mon, Dec 07, 2020 at 02:03:03PM +0100, Phil Sutter wrote:
> With an IPsec tunnel without dedicated interface, netfilter sees locally
> generated packets twice as they exit the physical interface: Once as "the
> inner packet" with IPsec context attached and once as the encrypted
> (ESP) packet.
>
> With xfrm_interface, the inner packet did not traverse NF_INET_LOCAL_OUT
> hook anymore, making it impossible to match on both inner header values
> and associated IPsec data from that hook.
>
> Fix this by looping packets transmitted from xfrm_interface through
> NF_INET_LOCAL_OUT before passing them on to dst_output(), which makes
> behaviour consistent again from netfilter's point of view.
>
> Fixes: f203b76d78092 ("xfrm: Add virtual xfrm interfaces")
> Signed-off-by: Phil Sutter <[email protected]>
> ---
> net/xfrm/xfrm_interface.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/net/xfrm/xfrm_interface.c b/net/xfrm/xfrm_interface.c
> index aa4cdcf69d471..24af61c95b4d4 100644
> --- a/net/xfrm/xfrm_interface.c
> +++ b/net/xfrm/xfrm_interface.c
> @@ -317,7 +317,8 @@ xfrmi_xmit2(struct sk_buff *skb, struct net_device *dev, struct flowi *fl)
> skb_dst_set(skb, dst);
> skb->dev = tdev;
>
> - err = dst_output(xi->net, skb->sk, skb);
> + err = NF_HOOK(skb_dst(skb)->ops->family, NF_INET_LOCAL_OUT, xi->net,
> + skb->sk, skb, NULL, skb_dst(skb)->dev, dst_output);
> if (net_xmit_eval(err) == 0) {
> struct pcpu_sw_netstats *tstats = this_cpu_ptr(dev->tstats);
This is networking code, so please send your patch also to the netdev list:
[email protected]