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>
diff --git a/drivers/net/vxlan.c b/drivers/net/vxlan.c
index 2ab0922..3a18d8e 100644
--- a/drivers/net/vxlan.c
+++ b/drivers/net/vxlan.c
@@ -61,12 +61,6 @@
#define FDB_AGE_DEFAULT 300 /* 5 min */
#define FDB_AGE_INTERVAL (10 * HZ) /* rescan interval */
-#define VXLAN_N_VID (1u << 24)
-#define VXLAN_VID_MASK (VXLAN_N_VID - 1)
-#define VXLAN_HLEN (sizeof(struct udphdr) + sizeof(struct vxlanhdr))
-
-#define VXLAN_FLAGS 0x08000000 /* struct vxlanhdr.vx_flags required value. */
-
/* UDP port for VXLAN traffic.
* The IANA assigned port is 4789, but the Linux default is 8472
* for compatibility with early adopters.
@@ -1095,18 +1089,21 @@
{
struct vxlan_sock *vs;
struct vxlanhdr *vxh;
+ u32 flags, vni;
/* Need Vxlan and inner Ethernet header to be present */
if (!pskb_may_pull(skb, VXLAN_HLEN))
goto error;
- /* Return packets with reserved bits set */
vxh = (struct vxlanhdr *)(udp_hdr(skb) + 1);
- if (vxh->vx_flags != htonl(VXLAN_FLAGS) ||
- (vxh->vx_vni & htonl(0xff))) {
- netdev_dbg(skb->dev, "invalid vxlan flags=%#x vni=%#x\n",
- ntohl(vxh->vx_flags), ntohl(vxh->vx_vni));
- goto error;
+ flags = ntohl(vxh->vx_flags);
+ vni = ntohl(vxh->vx_vni);
+
+ if (flags & VXLAN_HF_VNI) {
+ flags &= ~VXLAN_HF_VNI;
+ } else {
+ /* VNI flag always required to be set */
+ goto bad_flags;
}
if (iptunnel_pull_header(skb, VXLAN_HLEN, htons(ETH_P_TEB)))
@@ -1116,6 +1113,19 @@
if (!vs)
goto drop;
+ if (flags || (vni & 0xff)) {
+ /* 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
+ * in reserved fields are to be ignored. The approach here
+ * maintains compatbility with previous stack code, and also
+ * is more robust and provides a little more security in
+ * adding extensions to VXLAN.
+ */
+
+ goto bad_flags;
+ }
+
vs->rcv(vs, skb, vxh->vx_vni);
return 0;
@@ -1124,6 +1134,10 @@
kfree_skb(skb);
return 0;
+bad_flags:
+ netdev_dbg(skb->dev, "invalid vxlan flags=%#x vni=%#x\n",
+ ntohl(vxh->vx_flags), ntohl(vxh->vx_vni));
+
error:
/* Return non vxlan pkt */
return 1;
@@ -1563,7 +1577,7 @@
}
vxh = (struct vxlanhdr *) __skb_push(skb, sizeof(*vxh));
- vxh->vx_flags = htonl(VXLAN_FLAGS);
+ vxh->vx_flags = htonl(VXLAN_HF_VNI);
vxh->vx_vni = vni;
skb_set_inner_protocol(skb, htons(ETH_P_TEB));
@@ -1607,7 +1621,7 @@
return -ENOMEM;
vxh = (struct vxlanhdr *) __skb_push(skb, sizeof(*vxh));
- vxh->vx_flags = htonl(VXLAN_FLAGS);
+ vxh->vx_flags = htonl(VXLAN_HF_VNI);
vxh->vx_vni = vni;
skb_set_inner_protocol(skb, htons(ETH_P_TEB));