Re: [PATCH] ipvs: optimize tunnel dumps for icmp errors

[Julian Anastasov]

	Hello,

On Sun, 15 Mar 2020, Haishuang Yan wrote:

> After strip GRE/UDP tunnel header for icmp errors, it's better to show
> "ICMP for GRE/UDP" instead of "ICMP for IPIP" in debug message.
> 
> Signed-off-by: Haishuang Yan <yanhaishuang@xxxxxxxxxxxxxxxxxxxx>
> ---
>  net/netfilter/ipvs/ip_vs_core.c | 41 +++++++++++++++++++++++------------------
>  1 file changed, 23 insertions(+), 18 deletions(-)
> 
> diff --git a/net/netfilter/ipvs/ip_vs_core.c b/net/netfilter/ipvs/ip_vs_core.c
> index 512259f..f39ae6b 100644
> --- a/net/netfilter/ipvs/ip_vs_core.c
> +++ b/net/netfilter/ipvs/ip_vs_core.c

> @@ -1703,8 +1707,8 @@ static int ipvs_gre_decap(struct netns_ipvs *ipvs, struct sk_buff *skb,
>  		return NF_ACCEPT; /* The packet looks wrong, ignore */
>  	raddr = (union nf_inet_addr *)&cih->daddr;
>  
> -	/* Special case for errors for IPIP packets */
> -	ipip = false;
> +	/* Special case for errors for IPIP/UDP/GRE tunnel packets */
> +	tunnel = false;

	At this point it is safe to store cih->protocol in some new
var, eg. outer_proto...

> @@ -1809,17 +1813,18 @@ static int ipvs_gre_decap(struct netns_ipvs *ipvs, struct sk_buff *skb,
>  			u32 mtu = ntohs(ic->un.frag.mtu);
>  			__be16 frag_off = cih->frag_off;
>  
> -			/* Strip outer IP and ICMP, go to IPIP header */
> +			/* Strip outer IP and ICMP, go to IPIP/UDP/GRE header */
>  			if (pskb_pull(skb, ihl + sizeof(_icmph)) == NULL)
> -				goto ignore_ipip;
> +				goto ignore_tunnel;
>  			offset2 -= ihl + sizeof(_icmph);
>  			skb_reset_network_header(skb);
> -			IP_VS_DBG(12, "ICMP for IPIP %pI4->%pI4: mtu=%u\n",
> -				&ip_hdr(skb)->saddr, &ip_hdr(skb)->daddr, mtu);
> +			IP_VS_DBG(12, "ICMP for %s %pI4->%pI4: mtu=%u\n",
> +				  ip_vs_proto_name(cih->protocol),

	Because here cih points to the embedded UDP/TCP/SCTP IP header, so
we can not see GRE here. Or it is even better if we do not add more code 
to ip_vs_proto_name(), just use char *outer_proto and assign it with 
"IPIP" (where ipip was set) and "UDP"/"GRE" (where ulen was set) and print
outer_proto here.

> +				  &ip_hdr(skb)->saddr, &ip_hdr(skb)->daddr, mtu);

Regards

--
Julian Anastasov <ja@xxxxxx>