Merge branch 'ip_gre-flags-update'

Xin Long says:

====================
ip_gre: add support for i/o_flags update

ip_gre is using as many ip_tunnel apis as possible, newlink works
fine as gre would do it's own part in .ndo_init. But when changing
link, ip_tunnel_changelink doesn't even update i/o_flags, and also
the update of these flags would cause some other gre's properties
need to be updated or recalculated.

These two patch are to add i/o_flags update and then do adjustment
on some gre's properties according to the new i/o_flags.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv4/ip_gre.c

@@ -773,20 +773,46 @@ static netdev_tx_t gre_tap_xmit(struct sk_buff *skb,
 	return NETDEV_TX_OK;
 }
 
+static void ipgre_link_update(struct net_device *dev, bool set_mtu)
+{
+	struct ip_tunnel *tunnel = netdev_priv(dev);
+	int len;
+
+	len = tunnel->tun_hlen;
+	tunnel->tun_hlen = gre_calc_hlen(tunnel->parms.o_flags);
+	len = tunnel->tun_hlen - len;
+	tunnel->hlen = tunnel->hlen + len;
+
+	dev->needed_headroom = dev->needed_headroom + len;
+	if (set_mtu)
+		dev->mtu = max_t(int, dev->mtu - len, 68);
+
+	if (!(tunnel->parms.o_flags & TUNNEL_SEQ)) {
+		if (!(tunnel->parms.o_flags & TUNNEL_CSUM) ||
+		    tunnel->encap.type == TUNNEL_ENCAP_NONE) {
+			dev->features |= NETIF_F_GSO_SOFTWARE;
+			dev->hw_features |= NETIF_F_GSO_SOFTWARE;
+		}
+		dev->features |= NETIF_F_LLTX;
+	}
+}
+
 static int ipgre_tunnel_ioctl(struct net_device *dev,
 			      struct ifreq *ifr, int cmd)
 {
-	int err;
 	struct ip_tunnel_parm p;
+	int err;
 
 	if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p)))
 		return -EFAULT;
+
 	if (cmd == SIOCADDTUNNEL || cmd == SIOCCHGTUNNEL) {
 		if (p.iph.version != 4 || p.iph.protocol != IPPROTO_GRE ||
-		    p.iph.ihl != 5 || (p.iph.frag_off&htons(~IP_DF)) ||
-		    ((p.i_flags|p.o_flags)&(GRE_VERSION|GRE_ROUTING)))
+		    p.iph.ihl != 5 || (p.iph.frag_off & htons(~IP_DF)) ||
+		    ((p.i_flags | p.o_flags) & (GRE_VERSION | GRE_ROUTING)))
 			return -EINVAL;
 	}
+
 	p.i_flags = gre_flags_to_tnl_flags(p.i_flags);
 	p.o_flags = gre_flags_to_tnl_flags(p.o_flags);
 
@@ -794,11 +820,22 @@ static int ipgre_tunnel_ioctl(struct net_device *dev,
 	if (err)
 		return err;
 
+	if (cmd == SIOCCHGTUNNEL) {
+		struct ip_tunnel *t = netdev_priv(dev);
+
+		t->parms.i_flags = p.i_flags;
+		t->parms.o_flags = p.o_flags;
+
+		if (strcmp(dev->rtnl_link_ops->kind, "erspan"))
+			ipgre_link_update(dev, true);
+	}
+
 	p.i_flags = gre_tnl_flags_to_gre_flags(p.i_flags);
 	p.o_flags = gre_tnl_flags_to_gre_flags(p.o_flags);
 
 	if (copy_to_user(ifr->ifr_ifru.ifru_data, &p, sizeof(p)))
 		return -EFAULT;
+
 	return 0;
 }
 
@@ -1307,9 +1344,9 @@ static int ipgre_changelink(struct net_device *dev, struct nlattr *tb[],
 			    struct netlink_ext_ack *extack)
 {
 	struct ip_tunnel *t = netdev_priv(dev);
-	struct ip_tunnel_parm p;
 	struct ip_tunnel_encap ipencap;
 	__u32 fwmark = t->fwmark;
+	struct ip_tunnel_parm p;
 	int err;
 
 	if (ipgre_netlink_encap_parms(data, &ipencap)) {
@@ -1322,7 +1359,18 @@ static int ipgre_changelink(struct net_device *dev, struct nlattr *tb[],
 	err = ipgre_netlink_parms(dev, data, tb, &p, &fwmark);
 	if (err < 0)
 		return err;
-	return ip_tunnel_changelink(dev, tb, &p, fwmark);
+
+	err = ip_tunnel_changelink(dev, tb, &p, fwmark);
+	if (err < 0)
+		return err;
+
+	t->parms.i_flags = p.i_flags;
+	t->parms.o_flags = p.o_flags;
+
+	if (strcmp(dev->rtnl_link_ops->kind, "erspan"))
+		ipgre_link_update(dev, !tb[IFLA_MTU]);
+
+	return 0;
 }
 
 static size_t ipgre_get_size(const struct net_device *dev)