gre: Add netlink interface

This patch adds a netlink interface that will eventually displace
the existing ioctl interface.  It utilises the elegant rtnl_link_ops
mechanism.

This also means that user-space no longer needs to rely on the
tunnel interface being of type GRE to identify GRE tunnels.  The
identification can now occur using rtnl_link_ops.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 262 insertions, 4 deletions

diff --git a/include/linux/if_tunnel.h b/include/linux/if_tunnel.h
index d4efe4014705..aeab2cb32a9c 100644
--- a/include/linux/if_tunnel.h
+++ b/include/linux/if_tunnel.h
@@ -2,6 +2,7 @@
 #define _IF_TUNNEL_H_
 
 #include <linux/types.h>
+#include <linux/ip.h>
 
 #define SIOCGETTUNNEL   (SIOCDEVPRIVATE + 0)
 #define SIOCADDTUNNEL   (SIOCDEVPRIVATE + 1)
@@ -47,4 +48,22 @@ struct ip_tunnel_prl {
 /* PRL flags */
 #define PRL_DEFAULT             0x0001
 
+enum
+{
+        IFLA_GRE_UNSPEC,
+        IFLA_GRE_LINK,
+        IFLA_GRE_IFLAGS,
+        IFLA_GRE_OFLAGS,
+        IFLA_GRE_IKEY,
+        IFLA_GRE_OKEY,
+        IFLA_GRE_LOCAL,
+        IFLA_GRE_REMOTE,
+        IFLA_GRE_TTL,
+        IFLA_GRE_TOS,
+        IFLA_GRE_PMTUDISC,
+        __IFLA_GRE_MAX,
+};
+
+#define IFLA_GRE_MAX    (__IFLA_GRE_MAX - 1)
+
 #endif /* _IF_TUNNEL_H_ */
diff --git a/net/ipv4/ip_gre.c b/net/ipv4/ip_gre.c
index 80622dd6fb3f..25d2c77a7f38 100644
--- a/net/ipv4/ip_gre.c
+++ b/net/ipv4/ip_gre.c
@@ -41,6 +41,7 @@
 #include <net/xfrm.h>
 #include <net/net_namespace.h>
 #include <net/netns/generic.h>
+#include <net/rtnetlink.h>
 
 #ifdef CONFIG_IPV6
 #include <net/ipv6.h>
@@ -117,6 +118,7 @@
    Alexey Kuznetsov.
  */
 
+static struct rtnl_link_ops ipgre_link_ops __read_mostly;
 static int ipgre_tunnel_init(struct net_device *dev);
 static void ipgre_tunnel_setup(struct net_device *dev);
 static int ipgre_tunnel_bind_dev(struct net_device *dev);
@@ -286,9 +288,9 @@ static struct ip_tunnel * ipgre_tunnel_locate(struct net *net,
                         goto failed_free;
         }
 
-        dev->init = ipgre_tunnel_init;
         nt = netdev_priv(dev);
         nt->parms = *parms;
+        dev->rtnl_link_ops = &ipgre_link_ops;
 
         dev->mtu = ipgre_tunnel_bind_dev(dev);
 
@@ -1087,6 +1089,7 @@ static int ipgre_close(struct net_device *dev)
 
 static void ipgre_tunnel_setup(struct net_device *dev)
 {
+        dev->init               = ipgre_tunnel_init;
         dev->uninit             = ipgre_tunnel_uninit;
         dev->destructor         = free_netdev;
         dev->hard_start_xmit    = ipgre_tunnel_xmit;
@@ -1196,6 +1199,7 @@ static int ipgre_init_net(struct net *net)
 
         ign->fb_tunnel_dev->init = ipgre_fb_tunnel_init;
         dev_net_set(ign->fb_tunnel_dev, net);
+        ign->fb_tunnel_dev->rtnl_link_ops = &ipgre_link_ops;
 
         if ((err = register_netdev(ign->fb_tunnel_dev)))
                 goto err_reg_dev;
@@ -1228,6 +1232,229 @@ static struct pernet_operations ipgre_net_ops = {
         .exit = ipgre_exit_net,
 };
 
+static int ipgre_tunnel_validate(struct nlattr *tb[], struct nlattr *data[])
+{
+        __be16 flags;
+
+        if (!data)
+                return 0;
+
+        flags = 0;
+        if (data[IFLA_GRE_IFLAGS])
+                flags |= nla_get_be16(data[IFLA_GRE_IFLAGS]);
+        if (data[IFLA_GRE_OFLAGS])
+                flags |= nla_get_be16(data[IFLA_GRE_OFLAGS]);
+        if (flags & (GRE_VERSION|GRE_ROUTING))
+                return -EINVAL;
+
+        return 0;
+}
+
+static void ipgre_netlink_parms(struct nlattr *data[],
+                                struct ip_tunnel_parm *parms)
+{
+        memset(parms, 0, sizeof(parms));
+
+        parms->iph.protocol = IPPROTO_GRE;
+
+        if (!data)
+                return;
+
+        if (data[IFLA_GRE_LINK])
+                parms->link = nla_get_u32(data[IFLA_GRE_LINK]);
+
+        if (data[IFLA_GRE_IFLAGS])
+                parms->i_flags = nla_get_be16(data[IFLA_GRE_IFLAGS]);
+
+        if (data[IFLA_GRE_OFLAGS])
+                parms->o_flags = nla_get_be16(data[IFLA_GRE_OFLAGS]);
+
+        if (data[IFLA_GRE_IKEY])
+                parms->i_key = nla_get_be32(data[IFLA_GRE_IKEY]);
+
+        if (data[IFLA_GRE_OKEY])
+                parms->o_key = nla_get_be32(data[IFLA_GRE_OKEY]);
+
+        if (data[IFLA_GRE_LOCAL])
+                memcpy(&parms->iph.saddr, nla_data(data[IFLA_GRE_LOCAL]), 4);
+
+        if (data[IFLA_GRE_REMOTE])
+                memcpy(&parms->iph.daddr, nla_data(data[IFLA_GRE_REMOTE]), 4);
+
+        if (data[IFLA_GRE_TTL])
+                parms->iph.ttl = nla_get_u8(data[IFLA_GRE_TTL]);
+
+        if (data[IFLA_GRE_TOS])
+                parms->iph.tos = nla_get_u8(data[IFLA_GRE_TOS]);
+
+        if (!data[IFLA_GRE_PMTUDISC] || nla_get_u8(data[IFLA_GRE_PMTUDISC]))
+                parms->iph.frag_off = htons(IP_DF);
+}
+
+static int ipgre_newlink(struct net_device *dev, struct nlattr *tb[],
+                         struct nlattr *data[])
+{
+        struct ip_tunnel *nt;
+        struct net *net = dev_net(dev);
+        struct ipgre_net *ign = net_generic(net, ipgre_net_id);
+        int mtu;
+        int err;
+
+        nt = netdev_priv(dev);
+        ipgre_netlink_parms(data, &nt->parms);
+
+        if (ipgre_tunnel_locate(net, &nt->parms, 0))
+                return -EEXIST;
+
+        mtu = ipgre_tunnel_bind_dev(dev);
+        if (!tb[IFLA_MTU])
+                dev->mtu = mtu;
+
+        err = register_netdevice(dev);
+        if (err)
+                goto out;
+
+        dev_hold(dev);
+        ipgre_tunnel_link(ign, nt);
+
+out:
+        return err;
+}
+
+static int ipgre_changelink(struct net_device *dev, struct nlattr *tb[],
+                            struct nlattr *data[])
+{
+        struct ip_tunnel *t, *nt;
+        struct net *net = dev_net(dev);
+        struct ipgre_net *ign = net_generic(net, ipgre_net_id);
+        struct ip_tunnel_parm p;
+        int mtu;
+
+        if (dev == ign->fb_tunnel_dev)
+                return -EINVAL;
+
+        nt = netdev_priv(dev);
+        ipgre_netlink_parms(data, &p);
+
+        t = ipgre_tunnel_locate(net, &p, 0);
+
+        if (t) {
+                if (t->dev != dev)
+                        return -EEXIST;
+        } else {
+                unsigned nflags = 0;
+
+                t = nt;
+
+                if (ipv4_is_multicast(p.iph.daddr))
+                        nflags = IFF_BROADCAST;
+                else if (p.iph.daddr)
+                        nflags = IFF_POINTOPOINT;
+
+                if ((dev->flags ^ nflags) &
+                    (IFF_POINTOPOINT | IFF_BROADCAST))
+                        return -EINVAL;
+
+                ipgre_tunnel_unlink(ign, t);
+                t->parms.iph.saddr = p.iph.saddr;
+                t->parms.iph.daddr = p.iph.daddr;
+                t->parms.i_key = p.i_key;
+                memcpy(dev->dev_addr, &p.iph.saddr, 4);
+                memcpy(dev->broadcast, &p.iph.daddr, 4);
+                ipgre_tunnel_link(ign, t);
+                netdev_state_change(dev);
+        }
+
+        t->parms.o_key = p.o_key;
+        t->parms.iph.ttl = p.iph.ttl;
+        t->parms.iph.tos = p.iph.tos;
+        t->parms.iph.frag_off = p.iph.frag_off;
+
+        if (t->parms.link != p.link) {
+                t->parms.link = p.link;
+                mtu = ipgre_tunnel_bind_dev(dev);
+                if (!tb[IFLA_MTU])
+                        dev->mtu = mtu;
+                netdev_state_change(dev);
+        }
+
+        return 0;
+}
+
+static size_t ipgre_get_size(const struct net_device *dev)
+{
+        return
+                /* IFLA_GRE_LINK */
+                nla_total_size(4) +
+                /* IFLA_GRE_IFLAGS */
+                nla_total_size(2) +
+                /* IFLA_GRE_OFLAGS */
+                nla_total_size(2) +
+                /* IFLA_GRE_IKEY */
+                nla_total_size(4) +
+                /* IFLA_GRE_OKEY */
+                nla_total_size(4) +
+                /* IFLA_GRE_LOCAL */
+                nla_total_size(4) +
+                /* IFLA_GRE_REMOTE */
+                nla_total_size(4) +
+                /* IFLA_GRE_TTL */
+                nla_total_size(1) +
+                /* IFLA_GRE_TOS */
+                nla_total_size(1) +
+                /* IFLA_GRE_PMTUDISC */
+                nla_total_size(1) +
+                0;
+}
+
+static int ipgre_fill_info(struct sk_buff *skb, const struct net_device *dev)
+{
+        struct ip_tunnel *t = netdev_priv(dev);
+        struct ip_tunnel_parm *p = &t->parms;
+
+        NLA_PUT_U32(skb, IFLA_GRE_LINK, p->link);
+        NLA_PUT_BE16(skb, IFLA_GRE_IFLAGS, p->i_flags);
+        NLA_PUT_BE16(skb, IFLA_GRE_OFLAGS, p->o_flags);
+        NLA_PUT_BE32(skb, IFLA_GRE_IFLAGS, p->i_flags);
+        NLA_PUT_BE32(skb, IFLA_GRE_OFLAGS, p->o_flags);
+        NLA_PUT(skb, IFLA_GRE_LOCAL, 4, &p->iph.saddr);
+        NLA_PUT(skb, IFLA_GRE_REMOTE, 4, &p->iph.daddr);
+        NLA_PUT_U8(skb, IFLA_GRE_TTL, p->iph.ttl);
+        NLA_PUT_U8(skb, IFLA_GRE_TOS, p->iph.tos);
+        NLA_PUT_U8(skb, IFLA_GRE_PMTUDISC, !!(p->iph.frag_off & htons(IP_DF)));
+
+        return 0;
+
+nla_put_failure:
+        return -EMSGSIZE;
+}
+
+static const struct nla_policy ipgre_policy[IFLA_GRE_MAX + 1] = {
+        [IFLA_GRE_LINK]         = { .type = NLA_U32 },
+        [IFLA_GRE_IFLAGS]       = { .type = NLA_U16 },
+        [IFLA_GRE_OFLAGS]       = { .type = NLA_U16 },
+        [IFLA_GRE_IKEY]         = { .type = NLA_U32 },
+        [IFLA_GRE_OKEY]         = { .type = NLA_U32 },
+        [IFLA_GRE_LOCAL]        = { .len = 4 },
+        [IFLA_GRE_REMOTE]       = { .len = 4 },
+        [IFLA_GRE_TTL]          = { .type = NLA_U8 },
+        [IFLA_GRE_TOS]          = { .type = NLA_U8 },
+        [IFLA_GRE_PMTUDISC]     = { .type = NLA_U8 },
+};
+
+static struct rtnl_link_ops ipgre_link_ops __read_mostly = {
+        .kind           = "gre",
+        .maxtype        = IFLA_GRE_MAX,
+        .policy         = ipgre_policy,
+        .priv_size      = sizeof(struct ip_tunnel),
+        .setup          = ipgre_tunnel_setup,
+        .validate       = ipgre_tunnel_validate,
+        .newlink        = ipgre_newlink,
+        .changelink     = ipgre_changelink,
+        .get_size       = ipgre_get_size,
+        .fill_info      = ipgre_fill_info,
+};
+
 /*
  *      And now the modules code and kernel interface.
  */
@@ -1245,19 +1472,31 @@ static int __init ipgre_init(void)
 
         err = register_pernet_gen_device(&ipgre_net_id, &ipgre_net_ops);
         if (err < 0)
-                inet_del_protocol(&ipgre_protocol, IPPROTO_GRE);
+                goto gen_device_failed;
 
+        err = rtnl_link_register(&ipgre_link_ops);
+        if (err < 0)
+                goto rtnl_link_failed;
+
+out:
         return err;
+
+rtnl_link_failed:
+        unregister_pernet_gen_device(ipgre_net_id, &ipgre_net_ops);
+gen_device_failed:
+        inet_del_protocol(&ipgre_protocol, IPPROTO_GRE);
+        goto out;
 }
 
 static void __exit ipgre_fini(void)
 {
+        rtnl_link_unregister(&ipgre_link_ops);
+        unregister_pernet_gen_device(ipgre_net_id, &ipgre_net_ops);
         if (inet_del_protocol(&ipgre_protocol, IPPROTO_GRE) < 0)
                 printk(KERN_INFO "ipgre close: can't remove protocol\n");
-
-        unregister_pernet_gen_device(ipgre_net_id, &ipgre_net_ops);
 }
 
 module_init(ipgre_init);
 module_exit(ipgre_fini);
 MODULE_LICENSE("GPL");
+MODULE_ALIAS("rtnl-link-gre");