vxlan: Improve support for header flags
This patch cleans up the header flags of VXLAN in anticipation of defining some new ones: - Move header related definitions from vxlan.c to vxlan.h - Change VXLAN_FLAGS to be VXLAN_HF_VNI (only currently defined flag) - Move check for unknown flags to after we find vxlan_sock, this assumes that some flags may be processed based on tunnel configuration - Add a comment about why the stack treating unknown set flags as an error instead of ignoring them Signed-off-by: Tom Herbert <therbert@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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@ -61,12 +61,6 @@
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#define FDB_AGE_DEFAULT 300 /* 5 min */
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#define FDB_AGE_INTERVAL (10 * HZ) /* rescan interval */
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#define VXLAN_N_VID (1u << 24)
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#define VXLAN_VID_MASK (VXLAN_N_VID - 1)
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#define VXLAN_HLEN (sizeof(struct udphdr) + sizeof(struct vxlanhdr))
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#define VXLAN_FLAGS 0x08000000 /* struct vxlanhdr.vx_flags required value. */
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/* UDP port for VXLAN traffic.
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* The IANA assigned port is 4789, but the Linux default is 8472
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* for compatibility with early adopters.
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@ -1095,18 +1089,21 @@ static int vxlan_udp_encap_recv(struct sock *sk, struct sk_buff *skb)
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{
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struct vxlan_sock *vs;
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struct vxlanhdr *vxh;
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u32 flags, vni;
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/* Need Vxlan and inner Ethernet header to be present */
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if (!pskb_may_pull(skb, VXLAN_HLEN))
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goto error;
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/* Return packets with reserved bits set */
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vxh = (struct vxlanhdr *)(udp_hdr(skb) + 1);
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if (vxh->vx_flags != htonl(VXLAN_FLAGS) ||
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(vxh->vx_vni & htonl(0xff))) {
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netdev_dbg(skb->dev, "invalid vxlan flags=%#x vni=%#x\n",
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ntohl(vxh->vx_flags), ntohl(vxh->vx_vni));
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goto error;
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flags = ntohl(vxh->vx_flags);
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vni = ntohl(vxh->vx_vni);
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if (flags & VXLAN_HF_VNI) {
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flags &= ~VXLAN_HF_VNI;
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} else {
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/* VNI flag always required to be set */
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goto bad_flags;
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}
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if (iptunnel_pull_header(skb, VXLAN_HLEN, htons(ETH_P_TEB)))
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@ -1116,6 +1113,19 @@ static int vxlan_udp_encap_recv(struct sock *sk, struct sk_buff *skb)
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if (!vs)
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goto drop;
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if (flags || (vni & 0xff)) {
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/* If there are any unprocessed flags remaining treat
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* this as a malformed packet. This behavior diverges from
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* VXLAN RFC (RFC7348) which stipulates that bits in reserved
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* in reserved fields are to be ignored. The approach here
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* maintains compatbility with previous stack code, and also
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* is more robust and provides a little more security in
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* adding extensions to VXLAN.
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*/
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goto bad_flags;
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}
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vs->rcv(vs, skb, vxh->vx_vni);
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return 0;
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@ -1124,6 +1134,10 @@ drop:
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kfree_skb(skb);
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return 0;
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bad_flags:
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netdev_dbg(skb->dev, "invalid vxlan flags=%#x vni=%#x\n",
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ntohl(vxh->vx_flags), ntohl(vxh->vx_vni));
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error:
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/* Return non vxlan pkt */
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return 1;
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@ -1563,7 +1577,7 @@ static int vxlan6_xmit_skb(struct vxlan_sock *vs,
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}
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vxh = (struct vxlanhdr *) __skb_push(skb, sizeof(*vxh));
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vxh->vx_flags = htonl(VXLAN_FLAGS);
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vxh->vx_flags = htonl(VXLAN_HF_VNI);
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vxh->vx_vni = vni;
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skb_set_inner_protocol(skb, htons(ETH_P_TEB));
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@ -1607,7 +1621,7 @@ int vxlan_xmit_skb(struct vxlan_sock *vs,
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return -ENOMEM;
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vxh = (struct vxlanhdr *) __skb_push(skb, sizeof(*vxh));
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vxh->vx_flags = htonl(VXLAN_FLAGS);
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vxh->vx_flags = htonl(VXLAN_HF_VNI);
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vxh->vx_vni = vni;
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skb_set_inner_protocol(skb, htons(ETH_P_TEB));
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@ -17,6 +17,13 @@ struct vxlanhdr {
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__be32 vx_vni;
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};
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/* VXLAN header flags. */
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#define VXLAN_HF_VNI 0x08000000
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#define VXLAN_N_VID (1u << 24)
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#define VXLAN_VID_MASK (VXLAN_N_VID - 1)
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#define VXLAN_HLEN (sizeof(struct udphdr) + sizeof(struct vxlanhdr))
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struct vxlan_sock;
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typedef void (vxlan_rcv_t)(struct vxlan_sock *vh, struct sk_buff *skb, __be32 key);
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