vxlan: keep flags and vni in network byte order

Prevent repeated conversions from and to network order in the fast path.

To achieve this, define all flag constants in big endian order and store VNI
as __be32. To prevent confusion between the actual VNI value and the VNI
field from the header (which contains additional reserved byte), strictly
distinguish between "vni" and "vni_field".
Signed-off-by: Jiri Benc <jbenc@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/vxlan.c

@@ -197,9 +197,9 @@ static int vxlan_nla_put_addr(struct sk_buff *skb, int attr,
 #endif
 
 /* Virtual Network hash table head */
-static inline struct hlist_head *vni_head(struct vxlan_sock *vs, u32 id)
+static inline struct hlist_head *vni_head(struct vxlan_sock *vs, __be32 vni)
 {
-	return &vs->vni_list[hash_32(id, VNI_HASH_BITS)];
+	return &vs->vni_list[hash_32((__force u32)vni, VNI_HASH_BITS)];
 }
 
 /* Socket hash table head */
@@ -242,12 +242,12 @@ static struct vxlan_sock *vxlan_find_sock(struct net *net, sa_family_t family,
 	return NULL;
 }
 
-static struct vxlan_dev *vxlan_vs_find_vni(struct vxlan_sock *vs, u32 id)
+static struct vxlan_dev *vxlan_vs_find_vni(struct vxlan_sock *vs, __be32 vni)
 {
 	struct vxlan_dev *vxlan;
 
-	hlist_for_each_entry_rcu(vxlan, vni_head(vs, id), hlist) {
-		if (vxlan->default_dst.remote_vni == id)
+	hlist_for_each_entry_rcu(vxlan, vni_head(vs, vni), hlist) {
+		if (vxlan->default_dst.remote_vni == vni)
 			return vxlan;
 	}
 
@@ -255,7 +255,7 @@ static struct vxlan_dev *vxlan_vs_find_vni(struct vxlan_sock *vs, u32 id)
 }
 
 /* Look up VNI in a per net namespace table */
-static struct vxlan_dev *vxlan_find_vni(struct net *net, u32 id,
+static struct vxlan_dev *vxlan_find_vni(struct net *net, __be32 vni,
 					sa_family_t family, __be16 port,
 					u32 flags)
 {
@@ -265,7 +265,7 @@ static struct vxlan_dev *vxlan_find_vni(struct net *net, u32 id,
 	if (!vs)
 		return NULL;
 
-	return vxlan_vs_find_vni(vs, id);
+	return vxlan_vs_find_vni(vs, vni);
 }
 
 /* Fill in neighbour message in skbuff. */
@@ -315,7 +315,7 @@ static int vxlan_fdb_info(struct sk_buff *skb, struct vxlan_dev *vxlan,
 	    nla_put_be16(skb, NDA_PORT, rdst->remote_port))
 		goto nla_put_failure;
 	if (rdst->remote_vni != vxlan->default_dst.remote_vni &&
-	    nla_put_u32(skb, NDA_VNI, rdst->remote_vni))
+	    nla_put_u32(skb, NDA_VNI, be32_to_cpu(rdst->remote_vni)))
 		goto nla_put_failure;
 	if (rdst->remote_ifindex &&
 	    nla_put_u32(skb, NDA_IFINDEX, rdst->remote_ifindex))
@@ -383,7 +383,7 @@ static void vxlan_ip_miss(struct net_device *dev, union vxlan_addr *ipa)
 	};
 	struct vxlan_rdst remote = {
 		.remote_ip = *ipa, /* goes to NDA_DST */
-		.remote_vni = VXLAN_N_VID,
+		.remote_vni = cpu_to_be32(VXLAN_N_VID),
 	};
 
 	vxlan_fdb_notify(vxlan, &f, &remote, RTM_GETNEIGH);
@@ -452,7 +452,7 @@ static struct vxlan_fdb *vxlan_find_mac(struct vxlan_dev *vxlan,
 /* caller should hold vxlan->hash_lock */
 static struct vxlan_rdst *vxlan_fdb_find_rdst(struct vxlan_fdb *f,
 					      union vxlan_addr *ip, __be16 port,
-					      __u32 vni, __u32 ifindex)
+					      __be32 vni, __u32 ifindex)
 {
 	struct vxlan_rdst *rd;
 
@@ -469,7 +469,8 @@ static struct vxlan_rdst *vxlan_fdb_find_rdst(struct vxlan_fdb *f,
 
 /* Replace destination of unicast mac */
 static int vxlan_fdb_replace(struct vxlan_fdb *f,
-			     union vxlan_addr *ip, __be16 port, __u32 vni, __u32 ifindex)
+			     union vxlan_addr *ip, __be16 port, __be32 vni,
+			     __u32 ifindex)
 {
 	struct vxlan_rdst *rd;
 
@@ -491,7 +492,7 @@ static int vxlan_fdb_replace(struct vxlan_fdb *f,
 
 /* Add/update destinations for multicast */
 static int vxlan_fdb_append(struct vxlan_fdb *f,
-			    union vxlan_addr *ip, __be16 port, __u32 vni,
+			    union vxlan_addr *ip, __be16 port, __be32 vni,
 			    __u32 ifindex, struct vxlan_rdst **rdp)
 {
 	struct vxlan_rdst *rd;
@@ -523,7 +524,8 @@ static int vxlan_fdb_append(struct vxlan_fdb *f,
 static struct vxlanhdr *vxlan_gro_remcsum(struct sk_buff *skb,
 					  unsigned int off,
 					  struct vxlanhdr *vh, size_t hdrlen,
-					  u32 data, struct gro_remcsum *grc,
+					  __be32 vni_field,
+					  struct gro_remcsum *grc,
 					  bool nopartial)
 {
 	size_t start, offset;
@@ -534,10 +536,8 @@ static struct vxlanhdr *vxlan_gro_remcsum(struct sk_buff *skb,
 	if (!NAPI_GRO_CB(skb)->csum_valid)
 		return NULL;
 
-	start = (data & VXLAN_RCO_MASK) << VXLAN_RCO_SHIFT;
-	offset = start + ((data & VXLAN_RCO_UDP) ?
-			  offsetof(struct udphdr, check) :
-			  offsetof(struct tcphdr, check));
+	start = vxlan_rco_start(vni_field);
+	offset = start + vxlan_rco_offset(vni_field);
 
 	vh = skb_gro_remcsum_process(skb, (void *)vh, off, hdrlen,
 				     start, offset, grc, nopartial);
@@ -557,7 +557,7 @@ static struct sk_buff **vxlan_gro_receive(struct sk_buff **head,
 	int flush = 1;
 	struct vxlan_sock *vs = container_of(uoff, struct vxlan_sock,
 					     udp_offloads);
-	u32 flags;
+	__be32 flags;
 	struct gro_remcsum grc;
 
 	skb_gro_remcsum_init(&grc);
@@ -573,11 +573,11 @@ static struct sk_buff **vxlan_gro_receive(struct sk_buff **head,
 
 	skb_gro_postpull_rcsum(skb, vh, sizeof(struct vxlanhdr));
 
-	flags = ntohl(vh->vx_flags);
+	flags = vh->vx_flags;
 
 	if ((flags & VXLAN_HF_RCO) && (vs->flags & VXLAN_F_REMCSUM_RX)) {
 		vh = vxlan_gro_remcsum(skb, off_vx, vh, sizeof(struct vxlanhdr),
-				       ntohl(vh->vx_vni), &grc,
+				       vh->vx_vni, &grc,
 				       !!(vs->flags &
 					  VXLAN_F_REMCSUM_NOPARTIAL));
 
@@ -668,7 +668,7 @@ static void vxlan_notify_del_rx_port(struct vxlan_sock *vs)
 static int vxlan_fdb_create(struct vxlan_dev *vxlan,
 			    const u8 *mac, union vxlan_addr *ip,
 			    __u16 state, __u16 flags,
-			    __be16 port, __u32 vni, __u32 ifindex,
+			    __be16 port, __be32 vni, __u32 ifindex,
 			    __u8 ndm_flags)
 {
 	struct vxlan_rdst *rd = NULL;
@@ -777,7 +777,8 @@ static void vxlan_fdb_destroy(struct vxlan_dev *vxlan, struct vxlan_fdb *f)
 }
 
 static int vxlan_fdb_parse(struct nlattr *tb[], struct vxlan_dev *vxlan,
-			   union vxlan_addr *ip, __be16 *port, u32 *vni, u32 *ifindex)
+			   union vxlan_addr *ip, __be16 *port, __be32 *vni,
+			   u32 *ifindex)
 {
 	struct net *net = dev_net(vxlan->dev);
 	int err;
@@ -810,7 +811,7 @@ static int vxlan_fdb_parse(struct nlattr *tb[], struct vxlan_dev *vxlan,
 	if (tb[NDA_VNI]) {
 		if (nla_len(tb[NDA_VNI]) != sizeof(u32))
 			return -EINVAL;
-		*vni = nla_get_u32(tb[NDA_VNI]);
+		*vni = cpu_to_be32(nla_get_u32(tb[NDA_VNI]));
 	} else {
 		*vni = vxlan->default_dst.remote_vni;
 	}
@@ -840,7 +841,8 @@ static int vxlan_fdb_add(struct ndmsg *ndm, struct nlattr *tb[],
 	/* struct net *net = dev_net(vxlan->dev); */
 	union vxlan_addr ip;
 	__be16 port;
-	u32 vni, ifindex;
+	__be32 vni;
+	u32 ifindex;
 	int err;
 
 	if (!(ndm->ndm_state & (NUD_PERMANENT|NUD_REACHABLE))) {
@@ -877,7 +879,8 @@ static int vxlan_fdb_delete(struct ndmsg *ndm, struct nlattr *tb[],
 	struct vxlan_rdst *rd = NULL;
 	union vxlan_addr ip;
 	__be16 port;
-	u32 vni, ifindex;
+	__be32 vni;
+	u32 ifindex;
 	int err;
 
 	err = vxlan_fdb_parse(tb, vxlan, &ip, &port, &vni, &ifindex);
@@ -1133,17 +1136,16 @@ static int vxlan_igmp_leave(struct vxlan_dev *vxlan)
 }
 
 static struct vxlanhdr *vxlan_remcsum(struct sk_buff *skb, struct vxlanhdr *vh,
-				      size_t hdrlen, u32 data, bool nopartial)
+				      size_t hdrlen, __be32 vni_field,
+				      bool nopartial)
 {
 	size_t start, offset, plen;
 
 	if (skb->remcsum_offload)
 		return vh;
 
-	start = (data & VXLAN_RCO_MASK) << VXLAN_RCO_SHIFT;
-	offset = start + ((data & VXLAN_RCO_UDP) ?
-			  offsetof(struct udphdr, check) :
-			  offsetof(struct tcphdr, check));
+	start = vxlan_rco_start(vni_field);
+	offset = start + vxlan_rco_offset(vni_field);
 
 	plen = hdrlen + offset + sizeof(u16);
 
@@ -1159,7 +1161,7 @@ static struct vxlanhdr *vxlan_remcsum(struct sk_buff *skb, struct vxlanhdr *vh,
 }
 
 static void vxlan_rcv(struct vxlan_sock *vs, struct sk_buff *skb,
-		      struct vxlan_metadata *md, u32 vni,
+		      struct vxlan_metadata *md, __be32 vni,
 		      struct metadata_dst *tun_dst)
 {
 	struct iphdr *oip = NULL;
@@ -1257,7 +1259,7 @@ static int vxlan_udp_encap_recv(struct sock *sk, struct sk_buff *skb)
 {
 	struct metadata_dst *tun_dst = NULL;
 	struct vxlan_sock *vs;
-	u32 flags, vni;
+	__be32 flags, vni_field;
 	struct vxlan_metadata _md;
 	struct vxlan_metadata *md = &_md;
 
@@ -1265,8 +1267,8 @@ static int vxlan_udp_encap_recv(struct sock *sk, struct sk_buff *skb)
 	if (!pskb_may_pull(skb, VXLAN_HLEN))
 		goto error;
 
-	flags = ntohl(vxlan_hdr(skb)->vx_flags);
-	vni = ntohl(vxlan_hdr(skb)->vx_vni);
+	flags = vxlan_hdr(skb)->vx_flags;
+	vni_field = vxlan_hdr(skb)->vx_vni;
 
 	if (flags & VXLAN_HF_VNI) {
 		flags &= ~VXLAN_HF_VNI;
@@ -1283,17 +1285,18 @@ static int vxlan_udp_encap_recv(struct sock *sk, struct sk_buff *skb)
 		goto drop;
 
 	if ((flags & VXLAN_HF_RCO) && (vs->flags & VXLAN_F_REMCSUM_RX)) {
-		if (!vxlan_remcsum(skb, vxlan_hdr(skb), sizeof(struct vxlanhdr), vni,
+		if (!vxlan_remcsum(skb, vxlan_hdr(skb), sizeof(struct vxlanhdr),
+				   vni_field,
 				   !!(vs->flags & VXLAN_F_REMCSUM_NOPARTIAL)))
 			goto drop;
 
 		flags &= ~VXLAN_HF_RCO;
-		vni &= VXLAN_VNI_MASK;
+		vni_field &= VXLAN_VNI_MASK;
 	}
 
 	if (vxlan_collect_metadata(vs)) {
 		tun_dst = udp_tun_rx_dst(skb, vxlan_get_sk_family(vs), TUNNEL_KEY,
-					 cpu_to_be64(vni >> 8), sizeof(*md));
+					 vxlan_vni(vni_field), sizeof(*md));
 
 		if (!tun_dst)
 			goto drop;
@@ -1324,7 +1327,7 @@ static int vxlan_udp_encap_recv(struct sock *sk, struct sk_buff *skb)
 		flags &= ~VXLAN_GBP_USED_BITS;
 	}
 
-	if (flags || vni & ~VXLAN_VNI_MASK) {
+	if (flags || vni_field & ~VXLAN_VNI_MASK) {
 		/* If there are any unprocessed flags remaining treat
 		 * this as a malformed packet. This behavior diverges from
 		 * VXLAN RFC (RFC7348) which stipulates that bits in reserved
@@ -1337,7 +1340,7 @@ static int vxlan_udp_encap_recv(struct sock *sk, struct sk_buff *skb)
 		goto bad_flags;
 	}
 
-	vxlan_rcv(vs, skb, md, vni >> 8, tun_dst);
+	vxlan_rcv(vs, skb, md, vxlan_vni(vni_field), tun_dst);
 	return 0;
 
 drop:
@@ -1680,7 +1683,7 @@ static void vxlan_build_gbp_hdr(struct vxlanhdr *vxh, u32 vxflags,
 		return;
 
 	gbp = (struct vxlanhdr_gbp *)vxh;
-	vxh->vx_flags |= htonl(VXLAN_HF_GBP);
+	vxh->vx_flags |= VXLAN_HF_GBP;
 
 	if (md->gbp & VXLAN_GBP_DONT_LEARN)
 		gbp->dont_learn = 1;
@@ -1700,7 +1703,6 @@ static int vxlan_build_skb(struct sk_buff *skb, struct dst_entry *dst,
 	int min_headroom;
 	int err;
 	int type = udp_sum ? SKB_GSO_UDP_TUNNEL_CSUM : SKB_GSO_UDP_TUNNEL;
-	u16 hdrlen = sizeof(struct vxlanhdr);
 
 	if ((vxflags & VXLAN_F_REMCSUM_TX) &&
 	    skb->ip_summed == CHECKSUM_PARTIAL) {
@@ -1733,18 +1735,15 @@ static int vxlan_build_skb(struct sk_buff *skb, struct dst_entry *dst,
 		return PTR_ERR(skb);
 
 	vxh = (struct vxlanhdr *) __skb_push(skb, sizeof(*vxh));
-	vxh->vx_flags = htonl(VXLAN_HF_VNI);
-	vxh->vx_vni = vni;
+	vxh->vx_flags = VXLAN_HF_VNI;
+	vxh->vx_vni = vxlan_vni_field(vni);
 
 	if (type & SKB_GSO_TUNNEL_REMCSUM) {
-		u32 data = (skb_checksum_start_offset(skb) - hdrlen) >>
-			   VXLAN_RCO_SHIFT;
-
-		if (skb->csum_offset == offsetof(struct udphdr, check))
-			data |= VXLAN_RCO_UDP;
+		unsigned int start;
 
-		vxh->vx_vni |= htonl(data);
-		vxh->vx_flags |= htonl(VXLAN_HF_RCO);
+		start = skb_checksum_start_offset(skb) - sizeof(struct vxlanhdr);
+		vxh->vx_vni |= vxlan_compute_rco(start, skb->csum_offset);
+		vxh->vx_flags |= VXLAN_HF_RCO;
 
 		if (!skb_is_gso(skb)) {
 			skb->ip_summed = CHECKSUM_NONE;
@@ -1892,7 +1891,7 @@ static void vxlan_xmit_one(struct sk_buff *skb, struct net_device *dev,
 	struct vxlan_metadata _md;
 	struct vxlan_metadata *md = &_md;
 	__be16 src_port = 0, dst_port;
-	u32 vni;
+	__be32 vni;
 	__be16 df = 0;
 	__u8 tos, ttl;
 	int err;
@@ -1914,7 +1913,7 @@ static void vxlan_xmit_one(struct sk_buff *skb, struct net_device *dev,
 			goto drop;
 		}
 		dst_port = info->key.tp_dst ? : vxlan->cfg.dst_port;
-		vni = be64_to_cpu(info->key.tun_id);
+		vni = vxlan_tun_id_to_vni(info->key.tun_id);
 		remote_ip.sa.sa_family = ip_tunnel_info_af(info);
 		if (remote_ip.sa.sa_family == AF_INET)
 			remote_ip.sin.sin_addr.s_addr = info->key.u.ipv4.dst;
@@ -2007,7 +2006,7 @@ static void vxlan_xmit_one(struct sk_buff *skb, struct net_device *dev,
 		tos = ip_tunnel_ecn_encap(tos, old_iph, skb);
 		ttl = ttl ? : ip4_dst_hoplimit(&rt->dst);
 		err = vxlan_build_skb(skb, &rt->dst, sizeof(struct iphdr),
-				      htonl(vni << 8), md, flags, udp_sum);
+				      vni, md, flags, udp_sum);
 		if (err < 0)
 			goto xmit_tx_error;
 
@@ -2065,7 +2064,7 @@ static void vxlan_xmit_one(struct sk_buff *skb, struct net_device *dev,
 		ttl = ttl ? : ip6_dst_hoplimit(ndst);
 		skb_scrub_packet(skb, xnet);
 		err = vxlan_build_skb(skb, ndst, sizeof(struct ipv6hdr),
-				      htonl(vni << 8), md, flags, udp_sum);
+				      vni, md, flags, udp_sum);
 		if (err < 0) {
 			dst_release(ndst);
 			return;
@@ -2222,7 +2221,7 @@ static void vxlan_cleanup(unsigned long arg)
 static void vxlan_vs_add_dev(struct vxlan_sock *vs, struct vxlan_dev *vxlan)
 {
 	struct vxlan_net *vn = net_generic(vxlan->net, vxlan_net_id);
-	__u32 vni = vxlan->default_dst.remote_vni;
+	__be32 vni = vxlan->default_dst.remote_vni;
 
 	spin_lock(&vn->sock_lock);
 	hlist_add_head_rcu(&vxlan->hlist, vni_head(vs, vni));
@@ -2837,7 +2836,7 @@ static int vxlan_newlink(struct net *src_net, struct net_device *dev,
 	memset(&conf, 0, sizeof(conf));
 
 	if (data[IFLA_VXLAN_ID])
-		conf.vni = nla_get_u32(data[IFLA_VXLAN_ID]);
+		conf.vni = cpu_to_be32(nla_get_u32(data[IFLA_VXLAN_ID]));
 
 	if (data[IFLA_VXLAN_GROUP]) {
 		conf.remote_ip.sin.sin_addr.s_addr = nla_get_in_addr(data[IFLA_VXLAN_GROUP]);
@@ -2941,7 +2940,7 @@ static int vxlan_newlink(struct net *src_net, struct net_device *dev,
 		break;
 
 	case -EEXIST:
-		pr_info("duplicate VNI %u\n", conf.vni);
+		pr_info("duplicate VNI %u\n", be32_to_cpu(conf.vni));
 		break;
 	}
 
@@ -2999,7 +2998,7 @@ static int vxlan_fill_info(struct sk_buff *skb, const struct net_device *dev)
 		.high = htons(vxlan->cfg.port_max),
 	};
 
-	if (nla_put_u32(skb, IFLA_VXLAN_ID, dst->remote_vni))
+	if (nla_put_u32(skb, IFLA_VXLAN_ID, be32_to_cpu(dst->remote_vni)))
 		goto nla_put_failure;
 
 	if (!vxlan_addr_any(&dst->remote_ip)) {

include/net/vxlan.h

@@ -24,11 +24,11 @@ struct vxlanhdr {
 };
 
 /* VXLAN header flags. */
-#define VXLAN_HF_VNI BIT(27)
+#define VXLAN_HF_VNI	cpu_to_be32(BIT(27))
 
 #define VXLAN_N_VID     (1u << 24)
 #define VXLAN_VID_MASK  (VXLAN_N_VID - 1)
-#define VXLAN_VNI_MASK  (VXLAN_VID_MASK << 8)
+#define VXLAN_VNI_MASK	cpu_to_be32(VXLAN_VID_MASK << 8)
 #define VXLAN_HLEN (sizeof(struct udphdr) + sizeof(struct vxlanhdr))
 
 #define VNI_HASH_BITS	10
@@ -55,14 +55,14 @@ struct vxlanhdr {
  */
 
 /* VXLAN-RCO header flags. */
-#define VXLAN_HF_RCO BIT(21)
+#define VXLAN_HF_RCO	cpu_to_be32(BIT(21))
 
 /* Remote checksum offload header option */
-#define VXLAN_RCO_MASK  0x7f    /* Last byte of vni field */
-#define VXLAN_RCO_UDP   0x80    /* Indicate UDP RCO (TCP when not set *) */
+#define VXLAN_RCO_MASK	cpu_to_be32(0x7f)  /* Last byte of vni field */
+#define VXLAN_RCO_UDP	cpu_to_be32(0x80)  /* Indicate UDP RCO (TCP when not set *) */
 #define VXLAN_RCO_SHIFT	1		   /* Left shift of start */
 #define VXLAN_RCO_SHIFT_MASK ((1 << VXLAN_RCO_SHIFT) - 1)
-#define VXLAN_MAX_REMCSUM_START (VXLAN_RCO_MASK << VXLAN_RCO_SHIFT)
+#define VXLAN_MAX_REMCSUM_START (0x7f << VXLAN_RCO_SHIFT)
 
 /*
  * VXLAN Group Based Policy Extension (VXLAN_F_GBP):
@@ -105,9 +105,9 @@ struct vxlanhdr_gbp {
 };
 
 /* VXLAN-GBP header flags. */
-#define VXLAN_HF_GBP BIT(31)
+#define VXLAN_HF_GBP	cpu_to_be32(BIT(31))
 
-#define VXLAN_GBP_USED_BITS (VXLAN_HF_GBP | 0xFFFFFF)
+#define VXLAN_GBP_USED_BITS (VXLAN_HF_GBP | cpu_to_be32(0xFFFFFF))
 
 /* skb->mark mapping
  *
@@ -144,7 +144,7 @@ union vxlan_addr {
 struct vxlan_rdst {
 	union vxlan_addr	 remote_ip;
 	__be16			 remote_port;
-	u32			 remote_vni;
+	__be32			 remote_vni;
 	u32			 remote_ifindex;
 	struct list_head	 list;
 	struct rcu_head		 rcu;
@@ -154,7 +154,7 @@ struct vxlan_rdst {
 struct vxlan_config {
 	union vxlan_addr	remote_ip;
 	union vxlan_addr	saddr;
-	u32			vni;
+	__be32			vni;
 	int			remote_ifindex;
 	int			mtu;
 	__be16			dst_port;
@@ -267,6 +267,54 @@ static inline struct vxlanhdr *vxlan_hdr(struct sk_buff *skb)
 	return (struct vxlanhdr *)(udp_hdr(skb) + 1);
 }
 
+static inline __be32 vxlan_vni(__be32 vni_field)
+{
+#if defined(__BIG_ENDIAN)
+	return vni_field >> 8;
+#else
+	return (vni_field & VXLAN_VNI_MASK) << 8;
+#endif
+}
+
+static inline __be32 vxlan_vni_field(__be32 vni)
+{
+#if defined(__BIG_ENDIAN)
+	return vni << 8;
+#else
+	return vni >> 8;
+#endif
+}
+
+static inline __be32 vxlan_tun_id_to_vni(__be64 tun_id)
+{
+#if defined(__BIG_ENDIAN)
+	return tun_id;
+#else
+	return tun_id >> 32;
+#endif
+}
+
+static inline size_t vxlan_rco_start(__be32 vni_field)
+{
+	return be32_to_cpu(vni_field & VXLAN_RCO_MASK) << VXLAN_RCO_SHIFT;
+}
+
+static inline size_t vxlan_rco_offset(__be32 vni_field)
+{
+	return (vni_field & VXLAN_RCO_UDP) ?
+		offsetof(struct udphdr, check) :
+		offsetof(struct tcphdr, check);
+}
+
+static inline __be32 vxlan_compute_rco(unsigned int start, unsigned int offset)
+{
+	__be32 vni_field = cpu_to_be32(start >> VXLAN_RCO_SHIFT);
+
+	if (offset == offsetof(struct udphdr, check))
+		vni_field |= VXLAN_RCO_UDP;
+	return vni_field;
+}
+
 #if IS_ENABLED(CONFIG_VXLAN)
 void vxlan_get_rx_port(struct net_device *netdev);
 #else