gre: Allow multiple protocol listener for gre protocol.

Currently there is only one user is allowed to register for gre
protocol.  Following patch adds de-multiplexer.  So that multiple
modules can listen on gre protocol e.g. kernel gre devices and ovs.

Signed-off-by: Pravin B Shelar <pshelar@nicira.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 26 insertions, 147 deletions

diff --git a/net/ipv4/ip_gre.c b/net/ipv4/ip_gre.c
index a982657d05e7..19863a81cea1 100644
--- a/net/ipv4/ip_gre.c
+++ b/net/ipv4/ip_gre.c
@@ -121,103 +121,8 @@ static int ipgre_tunnel_init(struct net_device *dev);
 static int ipgre_net_id __read_mostly;
 static int gre_tap_net_id __read_mostly;
 
-static __sum16 check_checksum(struct sk_buff *skb)
-{
-        __sum16 csum = 0;
-
-        switch (skb->ip_summed) {
-        case CHECKSUM_COMPLETE:
-                csum = csum_fold(skb->csum);
-
-                if (!csum)
-                        break;
-                /* Fall through. */
-
-        case CHECKSUM_NONE:
-                skb->csum = 0;
-                csum = __skb_checksum_complete(skb);
-                skb->ip_summed = CHECKSUM_COMPLETE;
-                break;
-        }
-
-        return csum;
-}
-
-static int ip_gre_calc_hlen(__be16 o_flags)
-{
-        int addend = 4;
-
-        if (o_flags&TUNNEL_CSUM)
-                addend += 4;
-        if (o_flags&TUNNEL_KEY)
-                addend += 4;
-        if (o_flags&TUNNEL_SEQ)
-                addend += 4;
-        return addend;
-}
-
-static int parse_gre_header(struct sk_buff *skb, struct tnl_ptk_info *tpi,
-                            bool *csum_err, int *hdr_len)
-{
-        unsigned int ip_hlen = ip_hdrlen(skb);
-        const struct gre_base_hdr *greh;
-        __be32 *options;
-
-        if (unlikely(!pskb_may_pull(skb, sizeof(struct gre_base_hdr))))
-                return -EINVAL;
-
-        greh = (struct gre_base_hdr *)(skb_network_header(skb) + ip_hlen);
-        if (unlikely(greh->flags & (GRE_VERSION | GRE_ROUTING)))
-                return -EINVAL;
-
-        tpi->flags = gre_flags_to_tnl_flags(greh->flags);
-        *hdr_len = ip_gre_calc_hlen(tpi->flags);
-
-        if (!pskb_may_pull(skb, *hdr_len))
-                return -EINVAL;
-
-        greh = (struct gre_base_hdr *)(skb_network_header(skb) + ip_hlen);
-
-        tpi->proto = greh->protocol;
-
-        options = (__be32 *)(greh + 1);
-        if (greh->flags & GRE_CSUM) {
-                if (check_checksum(skb)) {
-                        *csum_err = true;
-                        return -EINVAL;
-                }
-                options++;
-        }
-
-        if (greh->flags & GRE_KEY) {
-                tpi->key = *options;
-                options++;
-        } else
-                tpi->key = 0;
-
-        if (unlikely(greh->flags & GRE_SEQ)) {
-                tpi->seq = *options;
-                options++;
-        } else
-                tpi->seq = 0;
-
-        /* WCCP version 1 and 2 protocol decoding.
-         * - Change protocol to IP
-         * - When dealing with WCCPv2, Skip extra 4 bytes in GRE header
-         */
-        if (greh->flags == 0 && tpi->proto == htons(ETH_P_WCCP)) {
-                tpi->proto = htons(ETH_P_IP);
-                if ((*(u8 *)options & 0xF0) != 0x40) {
-                        *hdr_len += 4;
-                        if (!pskb_may_pull(skb, *hdr_len))
-                                return -EINVAL;
-                }
-        }
-
-        return 0;
-}
-
-static void ipgre_err(struct sk_buff *skb, u32 info)
+static int ipgre_err(struct sk_buff *skb, u32 info,
+                     const struct tnl_ptk_info *tpi)
 {
 
         /* All the routers (except for Linux) return only
@@ -239,26 +144,18 @@ static void ipgre_err(struct sk_buff *skb, u32 info)
         const int type = icmp_hdr(skb)->type;
         const int code = icmp_hdr(skb)->code;
         struct ip_tunnel *t;
-        struct tnl_ptk_info tpi;
-        int hdr_len;
-        bool csum_err = false;
-
-        if (parse_gre_header(skb, &tpi, &csum_err, &hdr_len)) {
-                if (!csum_err)          /* ignore csum errors. */
-                        return;
-        }
 
         switch (type) {
         default:
         case ICMP_PARAMETERPROB:
-                return;
+                return PACKET_RCVD;
 
         case ICMP_DEST_UNREACH:
                 switch (code) {
                 case ICMP_SR_FAILED:
                 case ICMP_PORT_UNREACH:
                         /* Impossible event. */
-                        return;
+                        return PACKET_RCVD;
                 default:
                         /* All others are translated to HOST_UNREACH.
                            rfc2003 contains "deep thoughts" about NET_UNREACH,
@@ -269,79 +166,61 @@ static void ipgre_err(struct sk_buff *skb, u32 info)
                 break;
         case ICMP_TIME_EXCEEDED:
                 if (code != ICMP_EXC_TTL)
-                        return;
+                        return PACKET_RCVD;
                 break;
 
         case ICMP_REDIRECT:
                 break;
         }
 
-        if (tpi.proto == htons(ETH_P_TEB))
+        if (tpi->proto == htons(ETH_P_TEB))
                 itn = net_generic(net, gre_tap_net_id);
         else
                 itn = net_generic(net, ipgre_net_id);
 
         iph = (const struct iphdr *)skb->data;
-        t = ip_tunnel_lookup(itn, skb->dev->ifindex, tpi.flags,
-                             iph->daddr, iph->saddr, tpi.key);
+        t = ip_tunnel_lookup(itn, skb->dev->ifindex, tpi->flags,
+                             iph->daddr, iph->saddr, tpi->key);
 
         if (t == NULL)
-                return;
+                return PACKET_REJECT;
 
-        if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED) {
-                ipv4_update_pmtu(skb, dev_net(skb->dev), info,
-                                 t->parms.link, 0, IPPROTO_GRE, 0);
-                return;
-        }
-        if (type == ICMP_REDIRECT) {
-                ipv4_redirect(skb, dev_net(skb->dev), t->parms.link, 0,
-                              IPPROTO_GRE, 0);
-                return;
-        }
         if (t->parms.iph.daddr == 0 ||
             ipv4_is_multicast(t->parms.iph.daddr))
-                return;
+                return PACKET_RCVD;
 
         if (t->parms.iph.ttl == 0 && type == ICMP_TIME_EXCEEDED)
-                return;
+                return PACKET_RCVD;
 
         if (time_before(jiffies, t->err_time + IPTUNNEL_ERR_TIMEO))
                 t->err_count++;
         else
                 t->err_count = 1;
         t->err_time = jiffies;
+        return PACKET_RCVD;
 }
 
-static int ipgre_rcv(struct sk_buff *skb)
+static int ipgre_rcv(struct sk_buff *skb, const struct tnl_ptk_info *tpi)
 {
         struct net *net = dev_net(skb->dev);
         struct ip_tunnel_net *itn;
         const struct iphdr *iph;
         struct ip_tunnel *tunnel;
-        struct tnl_ptk_info tpi;
-        int hdr_len;
-        bool csum_err = false;
-
-        if (parse_gre_header(skb, &tpi, &csum_err, &hdr_len) < 0)
-                goto drop;
 
-        if (tpi.proto == htons(ETH_P_TEB))
+        if (tpi->proto == htons(ETH_P_TEB))
                 itn = net_generic(net, gre_tap_net_id);
         else
                 itn = net_generic(net, ipgre_net_id);
 
         iph = ip_hdr(skb);
-        tunnel = ip_tunnel_lookup(itn, skb->dev->ifindex, tpi.flags,
-                                  iph->saddr, iph->daddr, tpi.key);
+        tunnel = ip_tunnel_lookup(itn, skb->dev->ifindex, tpi->flags,
+                                  iph->saddr, iph->daddr, tpi->key);
 
         if (tunnel) {
-                ip_tunnel_rcv(tunnel, skb, &tpi, log_ecn_error);
-                return 0;
+                ip_tunnel_rcv(tunnel, skb, tpi, log_ecn_error);
+                return PACKET_RCVD;
         }
-        icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PORT_UNREACH, 0);
-drop:
-        kfree_skb(skb);
-        return 0;
+        return PACKET_REJECT;
 }
 
 static struct sk_buff *handle_offloads(struct ip_tunnel *tunnel, struct sk_buff *skb)
@@ -708,9 +587,10 @@ static int ipgre_tunnel_init(struct net_device *dev)
         return ip_tunnel_init(dev);
 }
 
-static const struct gre_protocol ipgre_protocol = {
-        .handler     = ipgre_rcv,
-        .err_handler = ipgre_err,
+static struct gre_cisco_protocol ipgre_protocol = {
+        .handler        = ipgre_rcv,
+        .err_handler    = ipgre_err,
+        .priority       = 0,
 };
 
 static int __net_init ipgre_init_net(struct net *net)
@@ -978,7 +858,7 @@ static int __init ipgre_init(void)
         if (err < 0)
                 goto pnet_tap_faied;
 
-        err = gre_add_protocol(&ipgre_protocol, GREPROTO_CISCO);
+        err = gre_cisco_register(&ipgre_protocol);
         if (err < 0) {
                 pr_info("%s: can't add protocol\n", __func__);
                 goto add_proto_failed;
@@ -997,7 +877,7 @@ static int __init ipgre_init(void)
 tap_ops_failed:
         rtnl_link_unregister(&ipgre_link_ops);
 rtnl_link_failed:
-        gre_del_protocol(&ipgre_protocol, GREPROTO_CISCO);
+        gre_cisco_unregister(&ipgre_protocol);
 add_proto_failed:
         unregister_pernet_device(&ipgre_tap_net_ops);
 pnet_tap_faied:
@@ -1009,8 +889,7 @@ static void __exit ipgre_fini(void)
 {
         rtnl_link_unregister(&ipgre_tap_ops);
         rtnl_link_unregister(&ipgre_link_ops);
-        if (gre_del_protocol(&ipgre_protocol, GREPROTO_CISCO) < 0)
-                pr_info("%s: can't remove protocol\n", __func__);
+        gre_cisco_unregister(&ipgre_protocol);
         unregister_pernet_device(&ipgre_tap_net_ops);
         unregister_pernet_device(&ipgre_net_ops);
 }