From 590e3f79a21edd2e9857ac3ced25ba6b2a491ef8 Mon Sep 17 00:00:00 2001 From: Jesper Dangaard Brouer Date: Tue, 28 Aug 2012 22:05:51 +0200 Subject: [PATCH] ipvs: IPv6 MTU checking cleanup and bugfix Cleaning up the IPv6 MTU checking in the IPVS xmit code, by using a common helper function __mtu_check_toobig_v6(). The MTU check for tunnel mode can also use this helper as ntohs(old_iph->payload_len) + sizeof(struct ipv6hdr) is qual to skb->len. And the 'mtu' variable have been adjusted before calling helper. Notice, this also fixes a bug, as the the MTU check in ip_vs_dr_xmit_v6() were missing a check for skb_is_gso(). This bug e.g. caused issues for KVM IPVS setups, where different Segmentation Offloading techniques are utilized, between guests, via the virtio driver. This resulted in very bad performance, due to the ICMPv6 "too big" messages didn't affect the sender. Signed-off-by: Jesper Dangaard Brouer Signed-off-by: Patrick McHardy Signed-off-by: Pablo Neira Ayuso --- net/netfilter/ipvs/ip_vs_xmit.c | 21 +++++++++++++++------ 1 file changed, 15 insertions(+), 6 deletions(-) diff --git a/net/netfilter/ipvs/ip_vs_xmit.c b/net/netfilter/ipvs/ip_vs_xmit.c index 543a554008af..67a39786b0a1 100644 --- a/net/netfilter/ipvs/ip_vs_xmit.c +++ b/net/netfilter/ipvs/ip_vs_xmit.c @@ -85,6 +85,15 @@ __ip_vs_dst_check(struct ip_vs_dest *dest, u32 rtos) return dst; } +static inline bool +__mtu_check_toobig_v6(const struct sk_buff *skb, u32 mtu) +{ + if (skb->len > mtu && !skb_is_gso(skb)) { + return true; /* Packet size violate MTU size */ + } + return false; +} + /* Get route to daddr, update *saddr, optionally bind route to saddr */ static struct rtable *do_output_route4(struct net *net, __be32 daddr, u32 rtos, int rt_mode, __be32 *saddr) @@ -491,7 +500,7 @@ ip_vs_bypass_xmit_v6(struct sk_buff *skb, struct ip_vs_conn *cp, /* MTU checking */ mtu = dst_mtu(&rt->dst); - if (skb->len > mtu && !skb_is_gso(skb)) { + if (__mtu_check_toobig_v6(skb, mtu)) { if (!skb->dev) { struct net *net = dev_net(skb_dst(skb)->dev); @@ -712,7 +721,7 @@ ip_vs_nat_xmit_v6(struct sk_buff *skb, struct ip_vs_conn *cp, /* MTU checking */ mtu = dst_mtu(&rt->dst); - if (skb->len > mtu && !skb_is_gso(skb)) { + if (__mtu_check_toobig_v6(skb, mtu)) { if (!skb->dev) { struct net *net = dev_net(skb_dst(skb)->dev); @@ -946,8 +955,8 @@ ip_vs_tunnel_xmit_v6(struct sk_buff *skb, struct ip_vs_conn *cp, if (skb_dst(skb)) skb_dst(skb)->ops->update_pmtu(skb_dst(skb), NULL, skb, mtu); - if (mtu < ntohs(old_iph->payload_len) + sizeof(struct ipv6hdr) && - !skb_is_gso(skb)) { + /* MTU checking: Notice that 'mtu' have been adjusted before hand */ + if (__mtu_check_toobig_v6(skb, mtu)) { if (!skb->dev) { struct net *net = dev_net(skb_dst(skb)->dev); @@ -1113,7 +1122,7 @@ ip_vs_dr_xmit_v6(struct sk_buff *skb, struct ip_vs_conn *cp, /* MTU checking */ mtu = dst_mtu(&rt->dst); - if (skb->len > mtu) { + if (__mtu_check_toobig_v6(skb, mtu)) { if (!skb->dev) { struct net *net = dev_net(skb_dst(skb)->dev); @@ -1349,7 +1358,7 @@ ip_vs_icmp_xmit_v6(struct sk_buff *skb, struct ip_vs_conn *cp, /* MTU checking */ mtu = dst_mtu(&rt->dst); - if (skb->len > mtu && !skb_is_gso(skb)) { + if (__mtu_check_toobig_v6(skb, mtu)) { if (!skb->dev) { struct net *net = dev_net(skb_dst(skb)->dev); -- 2.20.1