On Tue, 2016-06-14 at 22:15 -0700, Eric Dumazet wrote:
> From: Eric Dumazet <eduma...@google.com>
>
> 1) gre_parse_header() can be called from gre_err()
>
> At this point transport header points to ICMP header, not the inner
> header.
>
> 2) We can not really change transport header as ipgre_err() will later
> assume transport header still points to ICMP header.
>
> 3) pskb_may_pull() logic in gre_parse_header() really works
> if we are interested at zone pointed by skb->data
>
> So this fix :
>
> A) changes gre_parse_header() to use skb->data instead of
> skb_transport_header()
>
> B) changes gre_err() to pull the IPv4 header immediately following
> the ICMP header that was already pulled earlier.
>
> C) remove obsolete IPV6 includes
>
> Signed-off-by: Eric Dumazet <eduma...@google.com>
> Cc: Tom Herbert <t...@herbertland.com>
> Cc: Maciej Żenczykowski <m...@google.com>
> ---
> net/ipv4/gre_demux.c | 4 ++--
> net/ipv4/ip_gre.c | 9 +++------
> 2 files changed, 5 insertions(+), 8 deletions(-)
>
> diff --git a/net/ipv4/gre_demux.c b/net/ipv4/gre_demux.c
> index 4c39f4fd332a..0ba26ad9809d 100644
> --- a/net/ipv4/gre_demux.c
> +++ b/net/ipv4/gre_demux.c
> @@ -71,7 +71,7 @@ int gre_parse_header(struct sk_buff *skb, struct
> tnl_ptk_info *tpi,
> if (unlikely(!pskb_may_pull(skb, sizeof(struct gre_base_hdr))))
> return -EINVAL;
>
> - greh = (struct gre_base_hdr *)skb_transport_header(skb);
> + greh = (struct gre_base_hdr *)skb->data;
> if (unlikely(greh->flags & (GRE_VERSION | GRE_ROUTING)))
> return -EINVAL;
>
> @@ -81,7 +81,7 @@ int gre_parse_header(struct sk_buff *skb, struct
> tnl_ptk_info *tpi,
> if (!pskb_may_pull(skb, hdr_len))
> return -EINVAL;
>
> - greh = (struct gre_base_hdr *)skb_transport_header(skb);
> + greh = (struct gre_base_hdr *)skb->data;
> tpi->proto = greh->protocol;
>
> options = (__be32 *)(greh + 1);
> diff --git a/net/ipv4/ip_gre.c b/net/ipv4/ip_gre.c
> index 4d2025f7ec57..454832bc2897 100644
> --- a/net/ipv4/ip_gre.c
> +++ b/net/ipv4/ip_gre.c
> @@ -49,12 +49,6 @@
> #include <net/gre.h>
> #include <net/dst_metadata.h>
>
> -#if IS_ENABLED(CONFIG_IPV6)
> -#include <net/ipv6.h>
> -#include <net/ip6_fib.h>
> -#include <net/ip6_route.h>
> -#endif
> -
> /*
> Problems & solutions
> --------------------
> @@ -217,11 +211,14 @@ static void gre_err(struct sk_buff *skb, u32 info)
> * by themselves???
> */
>
> + const struct iphdr *iph = (struct iphdr *)skb->data;
> const int type = icmp_hdr(skb)->type;
> const int code = icmp_hdr(skb)->code;
> struct tnl_ptk_info tpi;
> bool csum_err = false;
>
> + pskb_pull(skb, iph->ihl * 4);
> +
> if (gre_parse_header(skb, &tpi, &csum_err, htons(ETH_P_IP)) < 0) {
> if (!csum_err) /* ignore csum errors. */
> return;
>
Hmm... I read this prior commit. It looks like we need something else.
commit b7f8fe251e4609e2a437bd2c2dea01e61db6849c
Author: Jiri Benc <jb...@redhat.com>
Date: Fri Apr 29 23:31:32 2016 +0200
gre: do not pull header in ICMP error processing
iptunnel_pull_header expects that IP header was already pulled; with this
expectation, it pulls the tunnel header. This is not true in gre_err.
Furthermore, ipv4_update_pmtu and ipv4_redirect expect that skb->data points
to the IP header.
We cannot pull the tunnel header in this path. It's just a matter of not
calling iptunnel_pull_header - we don't need any of its effects.
Fixes: bda7bb463436 ("gre: Allow multiple protocol listener for gre
protocol.")
Signed-off-by: Jiri Benc <jb...@redhat.com>
Signed-off-by: David S. Miller <da...@davemloft.net>
