netdev - Re: [PATCH net] net: ip6_gre: use erspan key field for tunnel lookup

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Date:   Wed, 16 Jan 2019 10:47:14 +0100
From:   Davide Caratti <dcaratti@...hat.com>
To:     Lorenzo Bianconi <lorenzo.bianconi@...hat.com>, davem@...emloft.net
Cc:     netdev@...r.kernel.org, u9012063@...il.com
Subject: Re: [PATCH net] net: ip6_gre: use erspan key field for tunnel
 lookup

On Tue, 2019-01-15 at 17:43 +0100, Lorenzo Bianconi wrote:
> Use ERSPAN key header field as tunnel key in gre_parse_header routine
> since ERSPAN protocol sets the key field of the external GRE header to
> 0 resulting in a possible tunnel lookup fail.
> In addition remove key field parsing in erspan_rcv and ip6erspan_rcv
> 
> Fixes: 5a963eb61b7c ("ip6_gre: Add ERSPAN native tunnel support")
> Signed-off-by: Lorenzo Bianconi <lorenzo.bianconi@...hat.com>
> ---
>  net/ipv4/gre_demux.c | 14 ++++++++++++++
>  net/ipv4/ip_gre.c    |  4 ----
>  net/ipv6/ip6_gre.c   |  1 -
>  3 files changed, 14 insertions(+), 5 deletions(-)
> 
> diff --git a/net/ipv4/gre_demux.c b/net/ipv4/gre_demux.c
> index a4bf22ee3aed..ee09d657606e 100644
> --- a/net/ipv4/gre_demux.c
> +++ b/net/ipv4/gre_demux.c
> @@ -25,6 +25,7 @@
>  #include <linux/spinlock.h>
>  #include <net/protocol.h>
>  #include <net/gre.h>
> +#include <net/erspan.h>
>  
>  #include <net/icmp.h>
>  #include <net/route.h>
> @@ -119,6 +120,19 @@ int gre_parse_header(struct sk_buff *skb, struct tnl_ptk_info *tpi,
>  			hdr_len += 4;
>  	}
>  	tpi->hdr_len = hdr_len;
> +
> +	/* ERSPAN ver 1 and 2 protocol sets GRE key field
> +	 * to 0 and sets the configured key in the
> +	 * inner erspan header field
> +	 */
> +	if (tpi->proto == htons(ETH_P_ERSPAN) ||
> +	    tpi->proto == htons(ETH_P_ERSPAN2)) {
> +		struct erspan_base_hdr *ershdr;
> +
> +		ershdr = (struct erspan_base_hdr *)options;
> +		tpi->key = cpu_to_be32(get_session_id(ershdr));
> +	}
> +

hi Lorenzo,

are we sure that 'ershdr' is in the linear part of skb? if not, we might
need a call to pskb_may_pull() here.

thanks!
-- 
davide