net: ip6_gre: Fix ip6erspan hlen calculation

Even though ip6erspan_tap_init() sets up hlen and tun_hlen according to
what ERSPAN needs, it goes ahead to call ip6gre_tnl_link_config() which
overwrites these settings with GRE-specific ones.

Similarly for changelink callbacks, which are handled by
ip6gre_changelink() calls ip6gre_tnl_change() calls
ip6gre_tnl_link_config() as well.

The difference ends up being 12 vs. 20 bytes, and this is generally not
a problem, because a 12-byte request likely ends up allocating more and
the extra 8 bytes are thus available. However correct it is not.

So replace the newlink and changelink callbacks with an ERSPAN-specific
ones, reusing the newly-introduced _common() functions.

Fixes: 5a963eb61b7c ("ip6_gre: Add ERSPAN native tunnel support")
Signed-off-by: Petr Machata <petrm@mellanox.com>
Acked-by: William Tu <u9012063@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 65 insertions, 9 deletions

diff --git a/net/ipv6/ip6_gre.c b/net/ipv6/ip6_gre.c
index 41fd5735f931..5162ecc45c20 100644
--- a/net/ipv6/ip6_gre.c
+++ b/net/ipv6/ip6_gre.c
@@ -81,6 +81,7 @@ static int ip6gre_tunnel_init(struct net_device *dev);
 static void ip6gre_tunnel_setup(struct net_device *dev);
 static void ip6gre_tunnel_link(struct ip6gre_net *ign, struct ip6_tnl *t);
 static void ip6gre_tnl_link_config(struct ip6_tnl *t, int set_mtu);
+static void ip6erspan_tnl_link_config(struct ip6_tnl *t, int set_mtu);
 
 /* Tunnel hash table */
 
@@ -1754,6 +1755,19 @@ static const struct net_device_ops ip6gre_tap_netdev_ops = {
         .ndo_get_iflink = ip6_tnl_get_iflink,
 };
 
+static int ip6erspan_calc_hlen(struct ip6_tnl *tunnel)
+{
+        int t_hlen;
+
+        tunnel->tun_hlen = 8;
+        tunnel->hlen = tunnel->tun_hlen + tunnel->encap_hlen +
+                       erspan_hdr_len(tunnel->parms.erspan_ver);
+
+        t_hlen = tunnel->hlen + sizeof(struct ipv6hdr);
+        tunnel->dev->hard_header_len = LL_MAX_HEADER + t_hlen;
+        return t_hlen;
+}
+
 static int ip6erspan_tap_init(struct net_device *dev)
 {
         struct ip6_tnl *tunnel;
@@ -1777,12 +1791,7 @@ static int ip6erspan_tap_init(struct net_device *dev)
                 return ret;
         }
 
-        tunnel->tun_hlen = 8;
-        tunnel->hlen = tunnel->tun_hlen + tunnel->encap_hlen +
-                       erspan_hdr_len(tunnel->parms.erspan_ver);
-        t_hlen = tunnel->hlen + sizeof(struct ipv6hdr);
-
-        dev->hard_header_len = LL_MAX_HEADER + t_hlen;
+        t_hlen = ip6erspan_calc_hlen(tunnel);
         dev->mtu = ETH_DATA_LEN - t_hlen;
         if (dev->type == ARPHRD_ETHER)
                 dev->mtu -= ETH_HLEN;
@@ -1790,7 +1799,7 @@ static int ip6erspan_tap_init(struct net_device *dev)
                 dev->mtu -= 8;
 
         dev->priv_flags |= IFF_LIVE_ADDR_CHANGE;
-        ip6gre_tnl_link_config(tunnel, 1);
+        ip6erspan_tnl_link_config(tunnel, 1);
 
         return 0;
 }
@@ -2121,6 +2130,53 @@ static void ip6erspan_tap_setup(struct net_device *dev)
         netif_keep_dst(dev);
 }
 
+static int ip6erspan_newlink(struct net *src_net, struct net_device *dev,
+                             struct nlattr *tb[], struct nlattr *data[],
+                             struct netlink_ext_ack *extack)
+{
+        int err = ip6gre_newlink_common(src_net, dev, tb, data, extack);
+        struct ip6_tnl *nt = netdev_priv(dev);
+        struct net *net = dev_net(dev);
+
+        if (!err) {
+                ip6erspan_tnl_link_config(nt, !tb[IFLA_MTU]);
+                ip6gre_tunnel_link(net_generic(net, ip6gre_net_id), nt);
+        }
+        return err;
+}
+
+static void ip6erspan_tnl_link_config(struct ip6_tnl *t, int set_mtu)
+{
+        ip6gre_tnl_link_config_common(t);
+        ip6gre_tnl_link_config_route(t, set_mtu, ip6erspan_calc_hlen(t));
+}
+
+static int ip6erspan_tnl_change(struct ip6_tnl *t,
+                                const struct __ip6_tnl_parm *p, int set_mtu)
+{
+        ip6gre_tnl_copy_tnl_parm(t, p);
+        ip6erspan_tnl_link_config(t, set_mtu);
+        return 0;
+}
+
+static int ip6erspan_changelink(struct net_device *dev, struct nlattr *tb[],
+                                struct nlattr *data[],
+                                struct netlink_ext_ack *extack)
+{
+        struct ip6gre_net *ign = net_generic(dev_net(dev), ip6gre_net_id);
+        struct __ip6_tnl_parm p;
+        struct ip6_tnl *t;
+
+        t = ip6gre_changelink_common(dev, tb, data, &p, extack);
+        if (IS_ERR(t))
+                return PTR_ERR(t);
+
+        ip6gre_tunnel_unlink(ign, t);
+        ip6erspan_tnl_change(t, &p, !tb[IFLA_MTU]);
+        ip6gre_tunnel_link(ign, t);
+        return 0;
+}
+
 static struct rtnl_link_ops ip6gre_link_ops __read_mostly = {
         .kind           = "ip6gre",
         .maxtype        = IFLA_GRE_MAX,
@@ -2157,8 +2213,8 @@ static struct rtnl_link_ops ip6erspan_tap_ops __read_mostly = {
         .priv_size      = sizeof(struct ip6_tnl),
         .setup          = ip6erspan_tap_setup,
         .validate       = ip6erspan_tap_validate,
-        .newlink        = ip6gre_newlink,
-        .changelink     = ip6gre_changelink,
+        .newlink        = ip6erspan_newlink,
+        .changelink     = ip6erspan_changelink,
         .get_size       = ip6gre_get_size,
         .fill_info      = ip6gre_fill_info,
         .get_link_net   = ip6_tnl_get_link_net,