openvswitch: add processing of L3 packets

Support receiving, extracting flow key and sending of L3 packets (packets
without an Ethernet header).

Note that even after this patch, non-Ethernet interfaces are still not
allowed to be added to bridges. Similarly, netlink interface for sending and
receiving L3 packets to/from user space is not in place yet.

Based on previous versions by Lorand Jakab and Simon Horman.

Signed-off-by: Lorand Jakab <lojakab@cisco.com>
Signed-off-by: Simon Horman <simon.horman@netronome.com>
Signed-off-by: Jiri Benc <jbenc@redhat.com>
Acked-by: Pravin B Shelar <pshelar@ovn.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 81 insertions, 25 deletions

diff --git a/net/openvswitch/flow.c b/net/openvswitch/flow.c
index 96c8c4716603..08aa926cd5cf 100644
--- a/net/openvswitch/flow.c
+++ b/net/openvswitch/flow.c
@@ -334,14 +334,17 @@ static int parse_vlan_tag(struct sk_buff *skb, struct vlan_head *key_vh)
         return 1;
 }
 
-static int parse_vlan(struct sk_buff *skb, struct sw_flow_key *key)
+static void clear_vlan(struct sw_flow_key *key)
 {
-        int res;
-
         key->eth.vlan.tci = 0;
         key->eth.vlan.tpid = 0;
         key->eth.cvlan.tci = 0;
         key->eth.cvlan.tpid = 0;
+}
+
+static int parse_vlan(struct sk_buff *skb, struct sw_flow_key *key)
+{
+        int res;
 
         if (skb_vlan_tag_present(skb)) {
                 key->eth.vlan.tci = htons(skb->vlan_tci);
@@ -483,17 +486,20 @@ invalid:
  *
  * Returns 0 if successful, otherwise a negative errno value.
  *
- * Initializes @skb header pointers as follows:
+ * Initializes @skb header fields as follows:
  *
- *    - skb->mac_header: the Ethernet header.
+ *    - skb->mac_header: the L2 header.
  *
- *    - skb->network_header: just past the Ethernet header, or just past the
- *      VLAN header, to the first byte of the Ethernet payload.
+ *    - skb->network_header: just past the L2 header, or just past the
+ *      VLAN header, to the first byte of the L2 payload.
  *
  *    - skb->transport_header: If key->eth.type is ETH_P_IP or ETH_P_IPV6
  *      on output, then just past the IP header, if one is present and
  *      of a correct length, otherwise the same as skb->network_header.
  *      For other key->eth.type values it is left untouched.
+ *
+ *    - skb->protocol: the type of the data starting at skb->network_header.
+ *      Equals to key->eth.type.
  */
 static int key_extract(struct sk_buff *skb, struct sw_flow_key *key)
 {
@@ -505,28 +511,35 @@ static int key_extract(struct sk_buff *skb, struct sw_flow_key *key)
 
         skb_reset_mac_header(skb);
 
-        /* Link layer.  We are guaranteed to have at least the 14 byte Ethernet
-         * header in the linear data area.
-         */
-        eth = eth_hdr(skb);
-        ether_addr_copy(key->eth.src, eth->h_source);
-        ether_addr_copy(key->eth.dst, eth->h_dest);
+        /* Link layer. */
+        clear_vlan(key);
+        if (key->mac_proto == MAC_PROTO_NONE) {
+                if (unlikely(eth_type_vlan(skb->protocol)))
+                        return -EINVAL;
 
-        __skb_pull(skb, 2 * ETH_ALEN);
-        /* We are going to push all headers that we pull, so no need to
-         * update skb->csum here.
-         */
+                skb_reset_network_header(skb);
+        } else {
+                eth = eth_hdr(skb);
+                ether_addr_copy(key->eth.src, eth->h_source);
+                ether_addr_copy(key->eth.dst, eth->h_dest);
 
-        if (unlikely(parse_vlan(skb, key)))
-                return -ENOMEM;
+                __skb_pull(skb, 2 * ETH_ALEN);
+                /* We are going to push all headers that we pull, so no need to
+                * update skb->csum here.
+                */
 
-        key->eth.type = parse_ethertype(skb);
-        if (unlikely(key->eth.type == htons(0)))
-                return -ENOMEM;
+                if (unlikely(parse_vlan(skb, key)))
+                        return -ENOMEM;
+
+                skb->protocol = parse_ethertype(skb);
+                if (unlikely(skb->protocol == htons(0)))
+                        return -ENOMEM;
 
-        skb_reset_network_header(skb);
+                skb_reset_network_header(skb);
+                __skb_push(skb, skb->data - skb_mac_header(skb));
+        }
         skb_reset_mac_len(skb);
-        __skb_push(skb, skb->data - skb_mac_header(skb));
+        key->eth.type = skb->protocol;
 
         /* Network layer. */
         if (key->eth.type == htons(ETH_P_IP)) {
@@ -721,9 +734,25 @@ int ovs_flow_key_update(struct sk_buff *skb, struct sw_flow_key *key)
         return key_extract(skb, key);
 }
 
+static int key_extract_mac_proto(struct sk_buff *skb)
+{
+        switch (skb->dev->type) {
+        case ARPHRD_ETHER:
+                return MAC_PROTO_ETHERNET;
+        case ARPHRD_NONE:
+                if (skb->protocol == htons(ETH_P_TEB))
+                        return MAC_PROTO_ETHERNET;
+                return MAC_PROTO_NONE;
+        }
+        WARN_ON_ONCE(1);
+        return -EINVAL;
+}
+
 int ovs_flow_key_extract(const struct ip_tunnel_info *tun_info,
                          struct sk_buff *skb, struct sw_flow_key *key)
 {
+        int res;
+
         /* Extract metadata from packet. */
         if (tun_info) {
                 key->tun_proto = ip_tunnel_info_af(tun_info);
@@ -751,7 +780,10 @@ int ovs_flow_key_extract(const struct ip_tunnel_info *tun_info,
         key->phy.skb_mark = skb->mark;
         ovs_ct_fill_key(skb, key);
         key->ovs_flow_hash = 0;
-        key->mac_proto = MAC_PROTO_ETHERNET;
+        res = key_extract_mac_proto(skb);
+        if (res < 0)
+                return res;
+        key->mac_proto = res;
         key->recirc_id = 0;
 
         return key_extract(skb, key);
@@ -768,5 +800,29 @@ int ovs_flow_key_extract_userspace(struct net *net, const struct nlattr *attr,
         if (err)
                 return err;
 
+        if (ovs_key_mac_proto(key) == MAC_PROTO_NONE) {
+                /* key_extract assumes that skb->protocol is set-up for
+                 * layer 3 packets which is the case for other callers,
+                 * in particular packets recieved from the network stack.
+                 * Here the correct value can be set from the metadata
+                 * extracted above.
+                 */
+                skb->protocol = key->eth.type;
+        } else {
+                struct ethhdr *eth;
+
+                skb_reset_mac_header(skb);
+                eth = eth_hdr(skb);
+
+                /* Normally, setting the skb 'protocol' field would be
+                 * handled by a call to eth_type_trans(), but it assumes
+                 * there's a sending device, which we may not have.
+                 */
+                if (eth_proto_is_802_3(eth->h_proto))
+                        skb->protocol = eth->h_proto;
+                else
+                        skb->protocol = htons(ETH_P_802_2);
+        }
+
         return key_extract(skb, key);
 }