ip_vti: Fix 'ip tunnel add' with 'key' parameters

ip tunnel add remote 10.2.2.1 local 10.2.2.2 mode vti ikey 1 okey 2
translates to p->iflags = VTI_ISVTI|GRE_KEY and p->i_key = 1, but GRE_KEY !=
TUNNEL_KEY, so ip_tunnel_ioctl would set i_key to 0 (same story with o_key)
making us unable to create vti tunnels with [io]key via ip tunnel.

We cannot simply translate GRE_KEY to TUNNEL_KEY (as GRE module does) because
vti_tunnels with same local/remote addresses but different ikeys will be treated
as different then. So, imo the best option here is to move p->i_flags & *_KEY
check for vti tunnels from ip_tunnel.c to ip_vti.c and to think about [io]_mark
field for ip_tunnel_parm in the future.
Signed-off-by: Dmitry Popov <ixaphire@qrator.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv4/ip_tunnel.c

@@ -748,10 +748,12 @@ int ip_tunnel_ioctl(struct net_device *dev, struct ip_tunnel_parm *p, int cmd)
 			goto done;
 		if (p->iph.ttl)
 			p->iph.frag_off |= htons(IP_DF);
-		if (!(p->i_flags&TUNNEL_KEY))
-			p->i_key = 0;
-		if (!(p->o_flags&TUNNEL_KEY))
-			p->o_key = 0;
+		if (!(p->i_flags & VTI_ISVTI)) {
+			if (!(p->i_flags & TUNNEL_KEY))
+				p->i_key = 0;
+			if (!(p->o_flags & TUNNEL_KEY))
+				p->o_key = 0;
+		}
 
 		t = ip_tunnel_find(itn, p, itn->fb_tunnel_dev->type);
 

net/ipv4/ip_vti.c

@@ -313,7 +313,13 @@ vti_tunnel_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
 			return -EINVAL;
 	}
 
-	p.i_flags |= VTI_ISVTI;
+	if (!(p.i_flags & GRE_KEY))
+		p.i_key = 0;
+	if (!(p.o_flags & GRE_KEY))
+		p.o_key = 0;
+
+	p.i_flags = VTI_ISVTI;
+
 	err = ip_tunnel_ioctl(dev, &p, cmd);
 	if (err)
 		return err;