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Commit e582615a authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

gre: fix error handler 



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 (using icmp_hdr())

3) pskb_may_pull() logic in gre_parse_header() really works
  if we are interested at zone pointed by skb->data

4) As Jiri explained in commit b7f8fe25 ("gre: do not pull header in
ICMP error processing") we should not pull headers in error handler.

So this fix :

A) changes gre_parse_header() to use skb->data instead of
skb_transport_header()

B) Adds a nhs parameter to gre_parse_header() so that we can skip the
not pulled IP header from error path.
  This offset is 0 for normal receive path.

C) remove obsolete IPV6 includes

Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Cc: Tom Herbert <tom@herbertland.com>
Cc: Maciej Żenczykowski <maze@google.com>
Cc: Jiri Benc <jbenc@redhat.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent daddef76

include/net/gre.h

+1 −1
Original line number Diff line number Diff line
@@ -26,7 +26,7 @@ int gre_del_protocol(const struct gre_protocol *proto, u8 version); 
struct net_device *gretap_fb_dev_create(struct net *net, const char *name,

				       u8 name_assign_type);

int gre_parse_header(struct sk_buff *skb, struct tnl_ptk_info *tpi,

		     bool *csum_err, __be16 proto);

		     bool *csum_err, __be16 proto, int nhs);



static inline int gre_calc_hlen(__be16 o_flags)

{

net/ipv4/gre_demux.c

+5 −5
Original line number Diff line number Diff line
@@ -62,26 +62,26 @@ EXPORT_SYMBOL_GPL(gre_del_protocol); 


/* Fills in tpi and returns header length to be pulled. */

int gre_parse_header(struct sk_buff *skb, struct tnl_ptk_info *tpi,

		     bool *csum_err, __be16 proto)

		     bool *csum_err, __be16 proto, int nhs)

{

	const struct gre_base_hdr *greh;

	__be32 *options;

	int hdr_len;



	if (unlikely(!pskb_may_pull(skb, sizeof(struct gre_base_hdr))))

	if (unlikely(!pskb_may_pull(skb, nhs + sizeof(struct gre_base_hdr))))

		return -EINVAL;



	greh = (struct gre_base_hdr *)skb_transport_header(skb);

	greh = (struct gre_base_hdr *)(skb->data + nhs);

	if (unlikely(greh->flags & (GRE_VERSION | GRE_ROUTING)))

		return -EINVAL;



	tpi->flags = gre_flags_to_tnl_flags(greh->flags);

	hdr_len = gre_calc_hlen(tpi->flags);



	if (!pskb_may_pull(skb, hdr_len))

	if (!pskb_may_pull(skb, nhs + hdr_len))

		return -EINVAL;



	greh = (struct gre_base_hdr *)skb_transport_header(skb);

	greh = (struct gre_base_hdr *)(skb->data + nhs);

	tpi->proto = greh->protocol;



	options = (__be32 *)(greh + 1);

net/ipv4/ip_gre.c

+4 −8
Original line number Diff line number Diff line
@@ -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

   --------------------
@@ -217,12 +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;



	if (gre_parse_header(skb, &tpi, &csum_err, htons(ETH_P_IP)) < 0) {

	if (gre_parse_header(skb, &tpi, &csum_err, htons(ETH_P_IP),

			     iph->ihl * 4) < 0) {

		if (!csum_err)		/* ignore csum errors. */

			return;

	}
@@ -338,7 +334,7 @@ static int gre_rcv(struct sk_buff *skb) 
	}

#endif



	hdr_len = gre_parse_header(skb, &tpi, &csum_err, htons(ETH_P_IP));

	hdr_len = gre_parse_header(skb, &tpi, &csum_err, htons(ETH_P_IP), 0);

	if (hdr_len < 0)

		goto drop;

net/ipv6/ip6_gre.c

+1 −1
Original line number Diff line number Diff line
@@ -468,7 +468,7 @@ static int gre_rcv(struct sk_buff *skb) 
	bool csum_err = false;

	int hdr_len;



	hdr_len = gre_parse_header(skb, &tpi, &csum_err, htons(ETH_P_IPV6));

	hdr_len = gre_parse_header(skb, &tpi, &csum_err, htons(ETH_P_IPV6), 0);

	if (hdr_len < 0)

		goto drop;