openvswitch: add Ethernet push and pop actions

It's not allowed to push Ethernet header in front of another Ethernet
header.

It's not allowed to pop Ethernet header if there's a vlan tag. This
preserves the invariant that L3 packet never has a vlan tag.

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>

2 files changed, 67 insertions, 0 deletions

diff --git a/net/openvswitch/actions.c b/net/openvswitch/actions.c
index 064cbcb7b0c5..514f7bcf7c63 100644
--- a/net/openvswitch/actions.c
+++ b/net/openvswitch/actions.c
@@ -317,6 +317,47 @@ static int set_eth_addr(struct sk_buff *skb, struct sw_flow_key *flow_key,
 	return 0;
 }
 
+/* pop_eth does not support VLAN packets as this action is never called
+ * for them.
+ */
+static int pop_eth(struct sk_buff *skb, struct sw_flow_key *key)
+{
+	skb_pull_rcsum(skb, ETH_HLEN);
+	skb_reset_mac_header(skb);
+	skb_reset_mac_len(skb);
+
+	/* safe right before invalidate_flow_key */
+	key->mac_proto = MAC_PROTO_NONE;
+	invalidate_flow_key(key);
+	return 0;
+}
+
+static int push_eth(struct sk_buff *skb, struct sw_flow_key *key,
+		    const struct ovs_action_push_eth *ethh)
+{
+	struct ethhdr *hdr;
+
+	/* Add the new Ethernet header */
+	if (skb_cow_head(skb, ETH_HLEN) < 0)
+		return -ENOMEM;
+
+	skb_push(skb, ETH_HLEN);
+	skb_reset_mac_header(skb);
+	skb_reset_mac_len(skb);
+
+	hdr = eth_hdr(skb);
+	ether_addr_copy(hdr->h_source, ethh->addresses.eth_src);
+	ether_addr_copy(hdr->h_dest, ethh->addresses.eth_dst);
+	hdr->h_proto = skb->protocol;
+
+	skb_postpush_rcsum(skb, hdr, ETH_HLEN);
+
+	/* safe right before invalidate_flow_key */
+	key->mac_proto = MAC_PROTO_ETHERNET;
+	invalidate_flow_key(key);
+	return 0;
+}
+
 static void update_ip_l4_checksum(struct sk_buff *skb, struct iphdr *nh,
 				  __be32 addr, __be32 new_addr)
 {
@@ -1200,6 +1241,14 @@ static int do_execute_actions(struct datapath *dp, struct sk_buff *skb,
 			if (err)
 				return err == -EINPROGRESS ? 0 : err;
 			break;
+
+		case OVS_ACTION_ATTR_PUSH_ETH:
+			err = push_eth(skb, key, nla_data(a));
+			break;
+
+		case OVS_ACTION_ATTR_POP_ETH:
+			err = pop_eth(skb, key);
+			break;
 		}
 
 		if (unlikely(err)) {
diff --git a/net/openvswitch/flow_netlink.c b/net/openvswitch/flow_netlink.c
index c3d0cc4321c3..d19044f2b1f4 100644
--- a/net/openvswitch/flow_netlink.c
+++ b/net/openvswitch/flow_netlink.c
@@ -2383,6 +2383,8 @@ static int __ovs_nla_copy_actions(struct net *net, const struct nlattr *attr,
 			[OVS_ACTION_ATTR_HASH] = sizeof(struct ovs_action_hash),
 			[OVS_ACTION_ATTR_CT] = (u32)-1,
 			[OVS_ACTION_ATTR_TRUNC] = sizeof(struct ovs_action_trunc),
+			[OVS_ACTION_ATTR_PUSH_ETH] = sizeof(struct ovs_action_push_eth),
+			[OVS_ACTION_ATTR_POP_ETH] = 0,
 		};
 		const struct ovs_action_push_vlan *vlan;
 		int type = nla_type(a);
@@ -2517,6 +2519,22 @@ static int __ovs_nla_copy_actions(struct net *net, const struct nlattr *attr,
 			skip_copy = true;
 			break;
 
+		case OVS_ACTION_ATTR_PUSH_ETH:
+			/* Disallow pushing an Ethernet header if one
+			 * is already present */
+			if (mac_proto != MAC_PROTO_NONE)
+				return -EINVAL;
+			mac_proto = MAC_PROTO_NONE;
+			break;
+
+		case OVS_ACTION_ATTR_POP_ETH:
+			if (mac_proto != MAC_PROTO_ETHERNET)
+				return -EINVAL;
+			if (vlan_tci & htons(VLAN_TAG_PRESENT))
+				return -EINVAL;
+			mac_proto = MAC_PROTO_ETHERNET;
+			break;
+
 		default:
 			OVS_NLERR(log, "Unknown Action type %d", type);
 			return -EINVAL;