Merge branch 'gtp-fixes'

Pablo Neira Ayuso says:

====================
GTP tunneling fixes for net

The following patchset contains two GTP tunneling fixes for your net
tree, they are:

1) Offset to IPv4 header in gtp_check_src_ms_ipv4() is incorrect, thus
   this function always succeeds and therefore this defeats this sanity
   check. This allows packets that have no PDP to go though, patch from
   Lionel Gauthier.

2) According to Note 0 of Figure 2 in Section 6 of 3GPP TS 29.060 v13.5.0
   Release 13, always set GTPv1 reserved bit to zero. This may cause
   interoperability problems, patch from Harald Welte.

Please, apply, thanks a lot!
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/gtp.c

@@ -158,9 +158,9 @@ static bool gtp_check_src_ms_ipv4(struct sk_buff *skb, struct pdp_ctx *pctx,
 	if (!pskb_may_pull(skb, hdrlen + sizeof(struct iphdr)))
 		return false;
 
-	iph = (struct iphdr *)(skb->data + hdrlen + sizeof(struct iphdr));
+	iph = (struct iphdr *)(skb->data + hdrlen);
 
-	return iph->saddr != pctx->ms_addr_ip4.s_addr;
+	return iph->saddr == pctx->ms_addr_ip4.s_addr;
 }
 
 /* Check if the inner IP source address in this packet is assigned to any
@@ -423,11 +423,11 @@ static inline void gtp1_push_header(struct sk_buff *skb, struct pdp_ctx *pctx)
 
 	/* Bits    8  7  6  5  4  3  2	1
 	 *	  +--+--+--+--+--+--+--+--+
-	 *	  |version |PT| 1| E| S|PN|
+	 *	  |version |PT| 0| E| S|PN|
 	 *	  +--+--+--+--+--+--+--+--+
 	 *	    0  0  1  1	1  0  0  0
 	 */
-	gtp1->flags	= 0x38; /* v1, GTP-non-prime. */
+	gtp1->flags	= 0x30; /* v1, GTP-non-prime. */
 	gtp1->type	= GTP_TPDU;
 	gtp1->length	= htons(payload_len);
 	gtp1->tid	= htonl(pctx->u.v1.o_tei);