From 3bf3947526c1053ddf2523f261395d682718f56c Mon Sep 17 00:00:00 2001 From: Tom Herbert Date: Thu, 8 Jan 2015 12:31:18 -0800 Subject: [PATCH] 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 Signed-off-by: David S. Miller --- drivers/net/vxlan.c | 42 ++++++++++++++++++++++++++++-------------- include/net/vxlan.h | 7 +++++++ 2 files changed, 35 insertions(+), 14 deletions(-) diff --git a/drivers/net/vxlan.c b/drivers/net/vxlan.c index 2ab0922af0b4..3a18d8ed89ca 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 @@ static int vxlan_udp_encap_recv(struct sock *sk, struct sk_buff *skb) { 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 @@ static int vxlan_udp_encap_recv(struct sock *sk, struct sk_buff *skb) 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 @@ drop: 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 @@ static int vxlan6_xmit_skb(struct vxlan_sock *vs, } 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 @@ int vxlan_xmit_skb(struct vxlan_sock *vs, 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)); diff --git a/include/net/vxlan.h b/include/net/vxlan.h index 903461aa5644..a0d80736224f 100644 --- a/include/net/vxlan.h +++ b/include/net/vxlan.h @@ -17,6 +17,13 @@ struct vxlanhdr { __be32 vx_vni; }; +/* VXLAN header flags. */ +#define VXLAN_HF_VNI 0x08000000 + +#define VXLAN_N_VID (1u << 24) +#define VXLAN_VID_MASK (VXLAN_N_VID - 1) +#define VXLAN_HLEN (sizeof(struct udphdr) + sizeof(struct vxlanhdr)) + struct vxlan_sock; typedef void (vxlan_rcv_t)(struct vxlan_sock *vh, struct sk_buff *skb, __be32 key); -- 2.20.1