net: ip6_gre: fix tunnel metadata device sharing.

Currently ip6gre and ip6erspan share single metadata mode device,
using 'collect_md_tun'.  Thus, when doing:
  ip link add dev ip6gre11 type ip6gretap external
  ip link add dev ip6erspan12 type ip6erspan external
  RTNETLINK answers: File exists
simply fails due to the 2nd tries to create the same collect_md_tun.

The patch fixes it by adding a separate collect md tunnel device
for the ip6erspan, 'collect_md_tun_erspan'.  As a result, a couple
of places need to refactor/split up in order to distinguish ip6gre
and ip6erspan.

First, move the collect_md check at ip6gre_tunnel_{unlink,link} and
create separate function {ip6gre,ip6ersapn}_tunnel_{link_md,unlink_md}.
Then before link/unlink, make sure the link_md/unlink_md is called.
Finally, a separate ndo_uninit is created for ip6erspan.  Tested it
using the samples/bpf/test_tunnel_bpf.sh.

Fixes: ef7baf5e083c ("ip6_gre: add ip6 erspan collect_md mode")
Signed-off-by: William Tu <u9012063@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv6/ip6_gre.c b/net/ipv6/ip6_gre.c
index 5162ecc45c202a88d3781e9617126551c13e60d3..458de353f5d9618f31d3fa28b7ae71c5a246f4a9 100644 (file)
--- a/net/ipv6/ip6_gre.c
+++ b/net/ipv6/ip6_gre.c
@@ -71,6 +71,7 @@ struct ip6gre_net {
        struct ip6_tnl __rcu *tunnels[4][IP6_GRE_HASH_SIZE];
 
        struct ip6_tnl __rcu *collect_md_tun;
+       struct ip6_tnl __rcu *collect_md_tun_erspan;
        struct net_device *fb_tunnel_dev;
 };
 
@@ -233,7 +234,12 @@ static struct ip6_tnl *ip6gre_tunnel_lookup(struct net_device *dev,
        if (cand)
                return cand;
 
-       t = rcu_dereference(ign->collect_md_tun);
+       if (gre_proto == htons(ETH_P_ERSPAN) ||
+           gre_proto == htons(ETH_P_ERSPAN2))
+               t = rcu_dereference(ign->collect_md_tun_erspan);
+       else
+               t = rcu_dereference(ign->collect_md_tun);
+
        if (t && t->dev->flags & IFF_UP)
                return t;
 
@@ -262,6 +268,31 @@ static struct ip6_tnl __rcu **__ip6gre_bucket(struct ip6gre_net *ign,
        return &ign->tunnels[prio][h];
 }
 
+static void ip6gre_tunnel_link_md(struct ip6gre_net *ign, struct ip6_tnl *t)
+{
+       if (t->parms.collect_md)
+               rcu_assign_pointer(ign->collect_md_tun, t);
+}
+
+static void ip6erspan_tunnel_link_md(struct ip6gre_net *ign, struct ip6_tnl *t)
+{
+       if (t->parms.collect_md)
+               rcu_assign_pointer(ign->collect_md_tun_erspan, t);
+}
+
+static void ip6gre_tunnel_unlink_md(struct ip6gre_net *ign, struct ip6_tnl *t)
+{
+       if (t->parms.collect_md)
+               rcu_assign_pointer(ign->collect_md_tun, NULL);
+}
+
+static void ip6erspan_tunnel_unlink_md(struct ip6gre_net *ign,
+                                      struct ip6_tnl *t)
+{
+       if (t->parms.collect_md)
+               rcu_assign_pointer(ign->collect_md_tun_erspan, NULL);
+}
+
 static inline struct ip6_tnl __rcu **ip6gre_bucket(struct ip6gre_net *ign,
                const struct ip6_tnl *t)
 {
@@ -272,9 +303,6 @@ static void ip6gre_tunnel_link(struct ip6gre_net *ign, struct ip6_tnl *t)
 {
        struct ip6_tnl __rcu **tp = ip6gre_bucket(ign, t);
 
-       if (t->parms.collect_md)
-               rcu_assign_pointer(ign->collect_md_tun, t);
-
        rcu_assign_pointer(t->next, rtnl_dereference(*tp));
        rcu_assign_pointer(*tp, t);
 }
@@ -284,9 +312,6 @@ static void ip6gre_tunnel_unlink(struct ip6gre_net *ign, struct ip6_tnl *t)
        struct ip6_tnl __rcu **tp;
        struct ip6_tnl *iter;
 
-       if (t->parms.collect_md)
-               rcu_assign_pointer(ign->collect_md_tun, NULL);
-
        for (tp = ip6gre_bucket(ign, t);
             (iter = rtnl_dereference(*tp)) != NULL;
             tp = &iter->next) {
@@ -375,11 +400,23 @@ failed_free:
        return NULL;
 }
 
+static void ip6erspan_tunnel_uninit(struct net_device *dev)
+{
+       struct ip6_tnl *t = netdev_priv(dev);
+       struct ip6gre_net *ign = net_generic(t->net, ip6gre_net_id);
+
+       ip6erspan_tunnel_unlink_md(ign, t);
+       ip6gre_tunnel_unlink(ign, t);
+       dst_cache_reset(&t->dst_cache);
+       dev_put(dev);
+}
+
 static void ip6gre_tunnel_uninit(struct net_device *dev)
 {
        struct ip6_tnl *t = netdev_priv(dev);
        struct ip6gre_net *ign = net_generic(t->net, ip6gre_net_id);
 
+       ip6gre_tunnel_unlink_md(ign, t);
        ip6gre_tunnel_unlink(ign, t);
        dst_cache_reset(&t->dst_cache);
        dev_put(dev);
@@ -1806,7 +1843,7 @@ static int ip6erspan_tap_init(struct net_device *dev)
 
 static const struct net_device_ops ip6erspan_netdev_ops = {
        .ndo_init =             ip6erspan_tap_init,
-       .ndo_uninit =           ip6gre_tunnel_uninit,
+       .ndo_uninit =           ip6erspan_tunnel_uninit,
        .ndo_start_xmit =       ip6erspan_tunnel_xmit,
        .ndo_set_mac_address =  eth_mac_addr,
        .ndo_validate_addr =    eth_validate_addr,
@@ -1875,8 +1912,6 @@ static int ip6gre_newlink_common(struct net *src_net, struct net_device *dev,
                                 struct netlink_ext_ack *extack)
 {
        struct ip6_tnl *nt;
-       struct net *net = dev_net(dev);
-       struct ip6gre_net *ign = net_generic(net, ip6gre_net_id);
        struct ip_tunnel_encap ipencap;
        int err;
 
@@ -1889,16 +1924,6 @@ static int ip6gre_newlink_common(struct net *src_net, struct net_device *dev,
                        return err;
        }
 
-       ip6gre_netlink_parms(data, &nt->parms);
-
-       if (nt->parms.collect_md) {
-               if (rtnl_dereference(ign->collect_md_tun))
-                       return -EEXIST;
-       } else {
-               if (ip6gre_tunnel_find(net, &nt->parms, dev->type))
-                       return -EEXIST;
-       }
-
        if (dev->type == ARPHRD_ETHER && !tb[IFLA_ADDRESS])
                eth_hw_addr_random(dev);
 
@@ -1922,12 +1947,26 @@ static int ip6gre_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);
+       struct ip6gre_net *ign;
+       int err;
+
+       ip6gre_netlink_parms(data, &nt->parms);
+       ign = net_generic(net, ip6gre_net_id);
+
+       if (nt->parms.collect_md) {
+               if (rtnl_dereference(ign->collect_md_tun))
+                       return -EEXIST;
+       } else {
+               if (ip6gre_tunnel_find(net, &nt->parms, dev->type))
+                       return -EEXIST;
+       }
 
+       err = ip6gre_newlink_common(src_net, dev, tb, data, extack);
        if (!err) {
                ip6gre_tnl_link_config(nt, !tb[IFLA_MTU]);
+               ip6gre_tunnel_link_md(ign, nt);
                ip6gre_tunnel_link(net_generic(net, ip6gre_net_id), nt);
        }
        return err;
@@ -1979,8 +2018,10 @@ static int ip6gre_changelink(struct net_device *dev, struct nlattr *tb[],
        if (IS_ERR(t))
                return PTR_ERR(t);
 
+       ip6gre_tunnel_unlink_md(ign, t);
        ip6gre_tunnel_unlink(ign, t);
        ip6gre_tnl_change(t, &p, !tb[IFLA_MTU]);
+       ip6gre_tunnel_link_md(ign, t);
        ip6gre_tunnel_link(ign, t);
        return 0;
 }
@@ -2134,12 +2175,26 @@ 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);
+       struct ip6gre_net *ign;
+       int err;
+
+       ip6gre_netlink_parms(data, &nt->parms);
+       ign = net_generic(net, ip6gre_net_id);
+
+       if (nt->parms.collect_md) {
+               if (rtnl_dereference(ign->collect_md_tun_erspan))
+                       return -EEXIST;
+       } else {
+               if (ip6gre_tunnel_find(net, &nt->parms, dev->type))
+                       return -EEXIST;
+       }
 
+       err = ip6gre_newlink_common(src_net, dev, tb, data, extack);
        if (!err) {
                ip6erspan_tnl_link_config(nt, !tb[IFLA_MTU]);
+               ip6erspan_tunnel_link_md(ign, nt);
                ip6gre_tunnel_link(net_generic(net, ip6gre_net_id), nt);
        }
        return err;
@@ -2171,8 +2226,10 @@ static int ip6erspan_changelink(struct net_device *dev, struct nlattr *tb[],
        if (IS_ERR(t))
                return PTR_ERR(t);
 
+       ip6gre_tunnel_unlink_md(ign, t);
        ip6gre_tunnel_unlink(ign, t);
        ip6erspan_tnl_change(t, &p, !tb[IFLA_MTU]);
+       ip6erspan_tunnel_link_md(ign, t);
        ip6gre_tunnel_link(ign, t);
        return 0;
 }