[PATCH net-next 6/6] sfc: generate encap headers for TC offload

[<edward.cree@amd.com>]

From: Edward Cree <ecree.xilinx@gmail.com>

Support constructing VxLAN and GENEVE headers, on either IPv4 or IPv6,
 using the neighbouring information obtained in encap->neigh to
 populate the Ethernet header.
Note that the ef100 hardware does not insert UDP checksums when
 performing encap, so for IPv6 the remote endpoint will need to be
 configured with udp6zerocsumrx or equivalent.

Signed-off-by: Edward Cree <ecree.xilinx@gmail.com>
---
 drivers/net/ethernet/sfc/tc_encap_actions.c | 194 +++++++++++++++++++-
 1 file changed, 185 insertions(+), 9 deletions(-)

diff --git a/drivers/net/ethernet/sfc/tc_encap_actions.c b/drivers/net/ethernet/sfc/tc_encap_actions.c
index 601141190f42..9a51d91d16bd 100644
--- a/drivers/net/ethernet/sfc/tc_encap_actions.c
+++ b/drivers/net/ethernet/sfc/tc_encap_actions.c
@@ -239,12 +239,183 @@ static void efx_release_neigh(struct efx_nic *efx,
 	efx_free_neigh(neigh);
 }
 
-static void efx_gen_encap_header(struct efx_tc_encap_action *encap)
+static void efx_gen_tun_header_eth(struct efx_tc_encap_action *encap, u16 proto)
 {
-	/* stub for now */
-	encap->n_valid = false;
-	memset(encap->encap_hdr, 0, sizeof(encap->encap_hdr));
-	encap->encap_hdr_len = ETH_HLEN;
+	struct efx_neigh_binder *neigh = encap->neigh;
+	struct ethhdr *eth;
+
+	encap->encap_hdr_len = sizeof(*eth);
+	eth = (struct ethhdr *)encap->encap_hdr;
+
+	if (encap->neigh->n_valid)
+		ether_addr_copy(eth->h_dest, neigh->ha);
+	else
+		eth_zero_addr(eth->h_dest);
+	ether_addr_copy(eth->h_source, neigh->egdev->dev_addr);
+	eth->h_proto = htons(proto);
+}
+
+static void efx_gen_tun_header_ipv4(struct efx_tc_encap_action *encap, u8 ipproto, u8 len)
+{
+	struct efx_neigh_binder *neigh = encap->neigh;
+	struct ip_tunnel_key *key = &encap->key;
+	struct iphdr *ip;
+
+	ip = (struct iphdr *)(encap->encap_hdr + encap->encap_hdr_len);
+	encap->encap_hdr_len += sizeof(*ip);
+
+	ip->daddr = key->u.ipv4.dst;
+	ip->saddr = key->u.ipv4.src;
+	ip->ttl = neigh->ttl;
+	ip->protocol = ipproto;
+	ip->version = 0x4;
+	ip->ihl = 0x5;
+	ip->tot_len = cpu_to_be16(ip->ihl * 4 + len);
+	ip_send_check(ip);
+}
+
+#ifdef CONFIG_IPV6
+static void efx_gen_tun_header_ipv6(struct efx_tc_encap_action *encap, u8 ipproto, u8 len)
+{
+	struct efx_neigh_binder *neigh = encap->neigh;
+	struct ip_tunnel_key *key = &encap->key;
+	struct ipv6hdr *ip;
+
+	ip = (struct ipv6hdr *)(encap->encap_hdr + encap->encap_hdr_len);
+	encap->encap_hdr_len += sizeof(*ip);
+
+	ip6_flow_hdr(ip, key->tos, key->label);
+	ip->daddr = key->u.ipv6.dst;
+	ip->saddr = key->u.ipv6.src;
+	ip->hop_limit = neigh->ttl;
+	ip->nexthdr = ipproto;
+	ip->version = 0x6;
+	ip->payload_len = cpu_to_be16(len);
+}
+#endif
+
+static void efx_gen_tun_header_udp(struct efx_tc_encap_action *encap, u8 len)
+{
+	struct ip_tunnel_key *key = &encap->key;
+	struct udphdr *udp;
+
+	udp = (struct udphdr *)(encap->encap_hdr + encap->encap_hdr_len);
+	encap->encap_hdr_len += sizeof(*udp);
+
+	udp->dest = key->tp_dst;
+	udp->len = cpu_to_be16(sizeof(*udp) + len);
+}
+
+static void efx_gen_tun_header_vxlan(struct efx_tc_encap_action *encap)
+{
+	struct ip_tunnel_key *key = &encap->key;
+	struct vxlanhdr *vxlan;
+
+	vxlan = (struct vxlanhdr *)(encap->encap_hdr + encap->encap_hdr_len);
+	encap->encap_hdr_len += sizeof(*vxlan);
+
+	vxlan->vx_flags = VXLAN_HF_VNI;
+	vxlan->vx_vni = vxlan_vni_field(tunnel_id_to_key32(key->tun_id));
+}
+
+static void efx_gen_tun_header_geneve(struct efx_tc_encap_action *encap)
+{
+	struct ip_tunnel_key *key = &encap->key;
+	struct genevehdr *geneve;
+	u32 vni;
+
+	geneve = (struct genevehdr *)(encap->encap_hdr + encap->encap_hdr_len);
+	encap->encap_hdr_len += sizeof(*geneve);
+
+	geneve->proto_type = htons(ETH_P_TEB);
+	/* convert tun_id to host-endian so we can use host arithmetic to
+	 * extract individual bytes.
+	 */
+	vni = ntohl(tunnel_id_to_key32(key->tun_id));
+	geneve->vni[0] = vni >> 16;
+	geneve->vni[1] = vni >> 8;
+	geneve->vni[2] = vni;
+}
+
+#define vxlan_header_l4_len	(sizeof(struct udphdr) + sizeof(struct vxlanhdr))
+#define vxlan4_header_len	(sizeof(struct ethhdr) + sizeof(struct iphdr) + vxlan_header_l4_len)
+static void efx_gen_vxlan_header_ipv4(struct efx_tc_encap_action *encap)
+{
+	BUILD_BUG_ON(sizeof(encap->encap_hdr) < vxlan4_header_len);
+	efx_gen_tun_header_eth(encap, ETH_P_IP);
+	efx_gen_tun_header_ipv4(encap, IPPROTO_UDP, vxlan_header_l4_len);
+	efx_gen_tun_header_udp(encap, sizeof(struct vxlanhdr));
+	efx_gen_tun_header_vxlan(encap);
+}
+
+#define geneve_header_l4_len	(sizeof(struct udphdr) + sizeof(struct genevehdr))
+#define geneve4_header_len	(sizeof(struct ethhdr) + sizeof(struct iphdr) + geneve_header_l4_len)
+static void efx_gen_geneve_header_ipv4(struct efx_tc_encap_action *encap)
+{
+	BUILD_BUG_ON(sizeof(encap->encap_hdr) < geneve4_header_len);
+	efx_gen_tun_header_eth(encap, ETH_P_IP);
+	efx_gen_tun_header_ipv4(encap, IPPROTO_UDP, geneve_header_l4_len);
+	efx_gen_tun_header_udp(encap, sizeof(struct genevehdr));
+	efx_gen_tun_header_geneve(encap);
+}
+
+#ifdef CONFIG_IPV6
+#define vxlan6_header_len	(sizeof(struct ethhdr) + sizeof(struct ipv6hdr) + vxlan_header_l4_len)
+static void efx_gen_vxlan_header_ipv6(struct efx_tc_encap_action *encap)
+{
+	BUILD_BUG_ON(sizeof(encap->encap_hdr) < vxlan6_header_len);
+	efx_gen_tun_header_eth(encap, ETH_P_IPV6);
+	efx_gen_tun_header_ipv6(encap, IPPROTO_UDP, vxlan_header_l4_len);
+	efx_gen_tun_header_udp(encap, sizeof(struct vxlanhdr));
+	efx_gen_tun_header_vxlan(encap);
+}
+
+#define geneve6_header_len	(sizeof(struct ethhdr) + sizeof(struct ipv6hdr) + geneve_header_l4_len)
+static void efx_gen_geneve_header_ipv6(struct efx_tc_encap_action *encap)
+{
+	BUILD_BUG_ON(sizeof(encap->encap_hdr) < geneve6_header_len);
+	efx_gen_tun_header_eth(encap, ETH_P_IPV6);
+	efx_gen_tun_header_ipv6(encap, IPPROTO_UDP, geneve_header_l4_len);
+	efx_gen_tun_header_udp(encap, sizeof(struct genevehdr));
+	efx_gen_tun_header_geneve(encap);
+}
+#endif
+
+static void efx_gen_encap_header(struct efx_nic *efx,
+				 struct efx_tc_encap_action *encap)
+{
+	encap->n_valid = encap->neigh->n_valid;
+
+	/* GCC stupidly thinks that only values explicitly listed in the enum
+	 * definition can _possibly_ be sensible case values, so without this
+	 * cast it complains about the IPv6 versions.
+	 */
+	switch ((int)encap->type) {
+	case EFX_ENCAP_TYPE_VXLAN:
+		efx_gen_vxlan_header_ipv4(encap);
+		break;
+	case EFX_ENCAP_TYPE_GENEVE:
+		efx_gen_geneve_header_ipv4(encap);
+		break;
+#ifdef CONFIG_IPV6
+	case EFX_ENCAP_TYPE_VXLAN | EFX_ENCAP_FLAG_IPV6:
+		efx_gen_vxlan_header_ipv6(encap);
+		break;
+	case EFX_ENCAP_TYPE_GENEVE | EFX_ENCAP_FLAG_IPV6:
+		efx_gen_geneve_header_ipv6(encap);
+		break;
+#endif
+	default:
+		/* unhandled encap type, can't happen */
+		if (net_ratelimit())
+			netif_err(efx, drv, efx->net_dev,
+				  "Bogus encap type %d, can't generate\n",
+				  encap->type);
+
+		/* Use fallback action. */
+		encap->n_valid = false;
+		break;
+	}
 }
 
 static void efx_tc_update_encap(struct efx_nic *efx,
@@ -278,14 +449,19 @@ static void efx_tc_update_encap(struct efx_nic *efx,
 		}
 	}
 
+	/* Make sure we don't leak arbitrary bytes on the wire;
+	 * set an all-0s ethernet header.  A successful call to
+	 * efx_gen_encap_header() will overwrite this.
+	 */
+	memset(encap->encap_hdr, 0, sizeof(encap->encap_hdr));
+	encap->encap_hdr_len = ETH_HLEN;
+
 	if (encap->neigh) {
 		read_lock_bh(&encap->neigh->lock);
-		efx_gen_encap_header(encap);
+		efx_gen_encap_header(efx, encap);
 		read_unlock_bh(&encap->neigh->lock);
 	} else {
 		encap->n_valid = false;
-		memset(encap->encap_hdr, 0, sizeof(encap->encap_hdr));
-		encap->encap_hdr_len = ETH_HLEN;
 	}
 
 	rc = efx_mae_update_encap_md(efx, encap);
@@ -482,7 +658,7 @@ struct efx_tc_encap_action *efx_tc_flower_create_encap_md(
 	}
 	encap->dest_mport = rc;
 	read_lock_bh(&encap->neigh->lock);
-	efx_gen_encap_header(encap);
+	efx_gen_encap_header(efx, encap);
 	read_unlock_bh(&encap->neigh->lock);
 
 	rc = efx_mae_allocate_encap_md(efx, encap);