From fc68c99577cc66e38d11b3e29304efb83fa08d53 Mon Sep 17 00:00:00 2001 From: Stefano Brivio Date: Tue, 4 Aug 2020 07:53:44 +0200 Subject: [PATCH] vxlan: Support for PMTU discovery on directly bridged links If the interface is a bridge or Open vSwitch port, and we can't forward a packet because it exceeds the local PMTU estimate, trigger an ICMP or ICMPv6 reply to the sender, using the same interface to forward it back. If metadata collection is enabled, reverse destination and source addresses, so that Open vSwitch is able to match this packet against the existing, reverse flow. v2: Use netif_is_any_bridge_port() (David Ahern) Signed-off-by: Stefano Brivio Signed-off-by: David S. Miller --- drivers/net/vxlan.c | 47 +++++++++++++++++++++++++++++++++++++++------ 1 file changed, 41 insertions(+), 6 deletions(-) diff --git a/drivers/net/vxlan.c b/drivers/net/vxlan.c index 1432544da507..6d5816be6131 100644 --- a/drivers/net/vxlan.c +++ b/drivers/net/vxlan.c @@ -2500,7 +2500,8 @@ static struct dst_entry *vxlan6_get_route(struct vxlan_dev *vxlan, /* Bypass encapsulation if the destination is local */ static void vxlan_encap_bypass(struct sk_buff *skb, struct vxlan_dev *src_vxlan, - struct vxlan_dev *dst_vxlan, __be32 vni) + struct vxlan_dev *dst_vxlan, __be32 vni, + bool snoop) { struct pcpu_sw_netstats *tx_stats, *rx_stats; union vxlan_addr loopback; @@ -2532,7 +2533,7 @@ static void vxlan_encap_bypass(struct sk_buff *skb, struct vxlan_dev *src_vxlan, goto drop; } - if (dst_vxlan->cfg.flags & VXLAN_F_LEARN) + if ((dst_vxlan->cfg.flags & VXLAN_F_LEARN) && snoop) vxlan_snoop(dev, &loopback, eth_hdr(skb)->h_source, 0, vni); u64_stats_update_begin(&tx_stats->syncp); @@ -2581,7 +2582,7 @@ static int encap_bypass_if_local(struct sk_buff *skb, struct net_device *dev, return -ENOENT; } - vxlan_encap_bypass(skb, vxlan, dst_vxlan, vni); + vxlan_encap_bypass(skb, vxlan, dst_vxlan, vni, true); return 1; } @@ -2617,7 +2618,8 @@ static void vxlan_xmit_one(struct sk_buff *skb, struct net_device *dev, if (vxlan_addr_any(dst)) { if (did_rsc) { /* short-circuited back to local bridge */ - vxlan_encap_bypass(skb, vxlan, vxlan, default_vni); + vxlan_encap_bypass(skb, vxlan, vxlan, + default_vni, true); return; } goto drop; @@ -2720,7 +2722,23 @@ static void vxlan_xmit_one(struct sk_buff *skb, struct net_device *dev, } ndst = &rt->dst; - skb_tunnel_check_pmtu(skb, ndst, VXLAN_HEADROOM, false); + err = skb_tunnel_check_pmtu(skb, ndst, VXLAN_HEADROOM, + netif_is_any_bridge_port(dev)); + if (err < 0) { + goto tx_error; + } else if (err) { + if (info) { + struct in_addr src, dst; + + src = remote_ip.sin.sin_addr; + dst = local_ip.sin.sin_addr; + info->key.u.ipv4.src = src.s_addr; + info->key.u.ipv4.dst = dst.s_addr; + } + vxlan_encap_bypass(skb, vxlan, vxlan, vni, false); + dst_release(ndst); + goto out_unlock; + } tos = ip_tunnel_ecn_encap(RT_TOS(tos), old_iph, skb); ttl = ttl ? : ip4_dst_hoplimit(&rt->dst); @@ -2760,7 +2778,24 @@ static void vxlan_xmit_one(struct sk_buff *skb, struct net_device *dev, goto out_unlock; } - skb_tunnel_check_pmtu(skb, ndst, VXLAN6_HEADROOM, false); + err = skb_tunnel_check_pmtu(skb, ndst, VXLAN6_HEADROOM, + netif_is_any_bridge_port(dev)); + if (err < 0) { + goto tx_error; + } else if (err) { + if (info) { + struct in6_addr src, dst; + + src = remote_ip.sin6.sin6_addr; + dst = local_ip.sin6.sin6_addr; + info->key.u.ipv6.src = src; + info->key.u.ipv6.dst = dst; + } + + vxlan_encap_bypass(skb, vxlan, vxlan, vni, false); + dst_release(ndst); + goto out_unlock; + } tos = ip_tunnel_ecn_encap(RT_TOS(tos), old_iph, skb); ttl = ttl ? : ip6_dst_hoplimit(ndst);