openvswitch: Add conntrack action

Expose the kernel connection tracker via OVS. Userspace components can
make use of the CT action to populate the connection state (ct_state)
field for a flow. This state can be subsequently matched.

Exposed connection states are OVS_CS_F_*:
- NEW (0x01) - Beginning of a new connection.
- ESTABLISHED (0x02) - Part of an existing connection.
- RELATED (0x04) - Related to an established connection.
- INVALID (0x20) - Could not track the connection for this packet.
- REPLY_DIR (0x40) - This packet is in the reply direction for the flow.
- TRACKED (0x80) - This packet has been sent through conntrack.

When the CT action is executed by itself, it will send the packet
through the connection tracker and populate the ct_state field with one
or more of the connection state flags above. The CT action will always
set the TRACKED bit.

When the COMMIT flag is passed to the conntrack action, this specifies
that information about the connection should be stored. This allows
subsequent packets for the same (or related) connections to be
correlated with this connection. Sending subsequent packets for the
connection through conntrack allows the connection tracker to consider
the packets as ESTABLISHED, RELATED, and/or REPLY_DIR.

The CT action may optionally take a zone to track the flow within. This
allows connections with the same 5-tuple to be kept logically separate
from connections in other zones. If the zone is specified, then the
"ct_zone" match field will be subsequently populated with the zone id.

IP fragments are handled by transparently assembling them as part of the
CT action. The maximum received unit (MRU) size is tracked so that
refragmentation can occur during output.

IP frag handling contributed by Andy Zhou.

Based on original design by Justin Pettit.

Signed-off-by: Joe Stringer <joestringer@nicira.com>
Signed-off-by: Justin Pettit <jpettit@nicira.com>
Signed-off-by: Andy Zhou <azhou@nicira.com>
Acked-by: Thomas Graf <tgraf@suug.ch>
Acked-by: Pravin B Shelar <pshelar@nicira.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 169 insertions, 6 deletions

diff --git a/net/openvswitch/actions.c b/net/openvswitch/actions.c
index 520438b77dc8..72ca2c491b0a 100644
--- a/net/openvswitch/actions.c
+++ b/net/openvswitch/actions.c
@@ -22,6 +22,7 @@
 #include <linux/in.h>
 #include <linux/ip.h>
 #include <linux/openvswitch.h>
+#include <linux/netfilter_ipv6.h>
 #include <linux/sctp.h>
 #include <linux/tcp.h>
 #include <linux/udp.h>
@@ -29,6 +30,7 @@
 #include <linux/if_arp.h>
 #include <linux/if_vlan.h>
 
+#include <net/dst.h>
 #include <net/ip.h>
 #include <net/ipv6.h>
 #include <net/checksum.h>
@@ -38,6 +40,7 @@
 
 #include "datapath.h"
 #include "flow.h"
+#include "conntrack.h"
 #include "vport.h"
 
 static int do_execute_actions(struct datapath *dp, struct sk_buff *skb,
@@ -52,6 +55,20 @@ struct deferred_action {
 	struct sw_flow_key pkt_key;
 };
 
+#define MAX_L2_LEN	(VLAN_ETH_HLEN + 3 * MPLS_HLEN)
+struct ovs_frag_data {
+	unsigned long dst;
+	struct vport *vport;
+	struct ovs_skb_cb cb;
+	__be16 inner_protocol;
+	__u16 vlan_tci;
+	__be16 vlan_proto;
+	unsigned int l2_len;
+	u8 l2_data[MAX_L2_LEN];
+};
+
+static DEFINE_PER_CPU(struct ovs_frag_data, ovs_frag_data_storage);
+
 #define DEFERRED_ACTION_FIFO_SIZE 10
 struct action_fifo {
 	int head;
@@ -602,14 +619,145 @@ static int set_sctp(struct sk_buff *skb, struct sw_flow_key *flow_key,
 	return 0;
 }
 
-static void do_output(struct datapath *dp, struct sk_buff *skb, int out_port)
+static int ovs_vport_output(struct sock *sock, struct sk_buff *skb)
+{
+	struct ovs_frag_data *data = this_cpu_ptr(&ovs_frag_data_storage);
+	struct vport *vport = data->vport;
+
+	if (skb_cow_head(skb, data->l2_len) < 0) {
+		kfree_skb(skb);
+		return -ENOMEM;
+	}
+
+	__skb_dst_copy(skb, data->dst);
+	*OVS_CB(skb) = data->cb;
+	skb->inner_protocol = data->inner_protocol;
+	skb->vlan_tci = data->vlan_tci;
+	skb->vlan_proto = data->vlan_proto;
+
+	/* Reconstruct the MAC header.  */
+	skb_push(skb, data->l2_len);
+	memcpy(skb->data, &data->l2_data, data->l2_len);
+	ovs_skb_postpush_rcsum(skb, skb->data, data->l2_len);
+	skb_reset_mac_header(skb);
+
+	ovs_vport_send(vport, skb);
+	return 0;
+}
+
+static unsigned int
+ovs_dst_get_mtu(const struct dst_entry *dst)
+{
+	return dst->dev->mtu;
+}
+
+static struct dst_ops ovs_dst_ops = {
+	.family = AF_UNSPEC,
+	.mtu = ovs_dst_get_mtu,
+};
+
+/* prepare_frag() is called once per (larger-than-MTU) frame; its inverse is
+ * ovs_vport_output(), which is called once per fragmented packet.
+ */
+static void prepare_frag(struct vport *vport, struct sk_buff *skb)
+{
+	unsigned int hlen = skb_network_offset(skb);
+	struct ovs_frag_data *data;
+
+	data = this_cpu_ptr(&ovs_frag_data_storage);
+	data->dst = skb->_skb_refdst;
+	data->vport = vport;
+	data->cb = *OVS_CB(skb);
+	data->inner_protocol = skb->inner_protocol;
+	data->vlan_tci = skb->vlan_tci;
+	data->vlan_proto = skb->vlan_proto;
+	data->l2_len = hlen;
+	memcpy(&data->l2_data, skb->data, hlen);
+
+	memset(IPCB(skb), 0, sizeof(struct inet_skb_parm));
+	skb_pull(skb, hlen);
+}
+
+static void ovs_fragment(struct vport *vport, struct sk_buff *skb, u16 mru,
+			 __be16 ethertype)
+{
+	if (skb_network_offset(skb) > MAX_L2_LEN) {
+		OVS_NLERR(1, "L2 header too long to fragment");
+		return;
+	}
+
+	if (ethertype == htons(ETH_P_IP)) {
+		struct dst_entry ovs_dst;
+		unsigned long orig_dst;
+
+		prepare_frag(vport, skb);
+		dst_init(&ovs_dst, &ovs_dst_ops, NULL, 1,
+			 DST_OBSOLETE_NONE, DST_NOCOUNT);
+		ovs_dst.dev = vport->dev;
+
+		orig_dst = skb->_skb_refdst;
+		skb_dst_set_noref(skb, &ovs_dst);
+		IPCB(skb)->frag_max_size = mru;
+
+		ip_do_fragment(skb->sk, skb, ovs_vport_output);
+		refdst_drop(orig_dst);
+	} else if (ethertype == htons(ETH_P_IPV6)) {
+		const struct nf_ipv6_ops *v6ops = nf_get_ipv6_ops();
+		unsigned long orig_dst;
+		struct rt6_info ovs_rt;
+
+		if (!v6ops) {
+			kfree_skb(skb);
+			return;
+		}
+
+		prepare_frag(vport, skb);
+		memset(&ovs_rt, 0, sizeof(ovs_rt));
+		dst_init(&ovs_rt.dst, &ovs_dst_ops, NULL, 1,
+			 DST_OBSOLETE_NONE, DST_NOCOUNT);
+		ovs_rt.dst.dev = vport->dev;
+
+		orig_dst = skb->_skb_refdst;
+		skb_dst_set_noref(skb, &ovs_rt.dst);
+		IP6CB(skb)->frag_max_size = mru;
+
+		v6ops->fragment(skb->sk, skb, ovs_vport_output);
+		refdst_drop(orig_dst);
+	} else {
+		WARN_ONCE(1, "Failed fragment ->%s: eth=%04x, MRU=%d, MTU=%d.",
+			  ovs_vport_name(vport), ntohs(ethertype), mru,
+			  vport->dev->mtu);
+		kfree_skb(skb);
+	}
+}
+
+static void do_output(struct datapath *dp, struct sk_buff *skb, int out_port,
+		      struct sw_flow_key *key)
 {
 	struct vport *vport = ovs_vport_rcu(dp, out_port);
 
-	if (likely(vport))
-		ovs_vport_send(vport, skb);
-	else
+	if (likely(vport)) {
+		u16 mru = OVS_CB(skb)->mru;
+
+		if (likely(!mru || (skb->len <= mru + ETH_HLEN))) {
+			ovs_vport_send(vport, skb);
+		} else if (mru <= vport->dev->mtu) {
+			__be16 ethertype = key->eth.type;
+
+			if (!is_flow_key_valid(key)) {
+				if (eth_p_mpls(skb->protocol))
+					ethertype = skb->inner_protocol;
+				else
+					ethertype = vlan_get_protocol(skb);
+			}
+
+			ovs_fragment(vport, skb, mru, ethertype);
+		} else {
+			kfree_skb(skb);
+		}
+	} else {
 		kfree_skb(skb);
+	}
 }
 
 static int output_userspace(struct datapath *dp, struct sk_buff *skb,
@@ -623,6 +771,7 @@ static int output_userspace(struct datapath *dp, struct sk_buff *skb,
 
 	memset(&upcall, 0, sizeof(upcall));
 	upcall.cmd = OVS_PACKET_CMD_ACTION;
+	upcall.mru = OVS_CB(skb)->mru;
 
 	for (a = nla_data(attr), rem = nla_len(attr); rem > 0;
 		 a = nla_next(a, &rem)) {
@@ -816,6 +965,11 @@ static int execute_masked_set_action(struct sk_buff *skb,
 		err = set_mpls(skb, flow_key, nla_data(a), get_mask(a,
 								    __be32 *));
 		break;
+
+	case OVS_KEY_ATTR_CT_STATE:
+	case OVS_KEY_ATTR_CT_ZONE:
+		err = -EINVAL;
+		break;
 	}
 
 	return err;
@@ -885,7 +1039,7 @@ static int do_execute_actions(struct datapath *dp, struct sk_buff *skb,
 			struct sk_buff *out_skb = skb_clone(skb, GFP_ATOMIC);
 
 			if (out_skb)
-				do_output(dp, out_skb, prev_port);
+				do_output(dp, out_skb, prev_port, key);
 
 			prev_port = -1;
 		}
@@ -942,6 +1096,15 @@ static int do_execute_actions(struct datapath *dp, struct sk_buff *skb,
 		case OVS_ACTION_ATTR_SAMPLE:
 			err = sample(dp, skb, key, a, attr, len);
 			break;
+
+		case OVS_ACTION_ATTR_CT:
+			err = ovs_ct_execute(ovs_dp_get_net(dp), skb, key,
+					     nla_data(a));
+
+			/* Hide stolen IP fragments from user space. */
+			if (err == -EINPROGRESS)
+				return 0;
+			break;
 		}
 
 		if (unlikely(err)) {
@@ -951,7 +1114,7 @@ static int do_execute_actions(struct datapath *dp, struct sk_buff *skb,
 	}
 
 	if (prev_port != -1)
-		do_output(dp, skb, prev_port);
+		do_output(dp, skb, prev_port, key);
 	else
 		consume_skb(skb);