From 0c12582fbcdea0cbb0dfd224e1c5f9a8428ffa18 Mon Sep 17 00:00:00 2001 From: Julian Anastasov Date: Sat, 9 Mar 2013 23:25:04 +0200 Subject: [PATCH] ipvs: add backup_only flag to avoid loops Dmitry Akindinov is reporting for a problem where SYNs are looping between the master and backup server when the backup server is used as real server in DR mode and has IPVS rules to function as director. Even when the backup function is enabled we continue to forward traffic and schedule new connections when the current master is using the backup server as real server. While this is not a problem for NAT, for DR and TUN method the backup server can not determine if a request comes from client or from director. To avoid such loops add new sysctl flag backup_only. It can be needed for DR/TUN setups that do not need backup and director function at the same time. When the backup function is enabled we stop any forwarding and pass the traffic to the local stack (real server mode). The flag disables the director function when the backup function is enabled. For setups that enable backup function for some virtual services and director function for other virtual services there should be another more complex solution to support DR/TUN mode, may be to assign per-virtual service syncid value, so that we can differentiate the requests. Reported-by: Dmitry Akindinov Tested-by: German Myzovsky Signed-off-by: Julian Anastasov Signed-off-by: Simon Horman --- Documentation/networking/ipvs-sysctl.txt | 7 +++++++ include/net/ip_vs.h | 12 ++++++++++++ net/netfilter/ipvs/ip_vs_core.c | 12 ++++++++---- net/netfilter/ipvs/ip_vs_ctl.c | 7 +++++++ 4 files changed, 34 insertions(+), 4 deletions(-) diff --git a/Documentation/networking/ipvs-sysctl.txt b/Documentation/networking/ipvs-sysctl.txt index f2a2488f1bf..9573d0c48c6 100644 --- a/Documentation/networking/ipvs-sysctl.txt +++ b/Documentation/networking/ipvs-sysctl.txt @@ -15,6 +15,13 @@ amemthresh - INTEGER enabled and the variable is automatically set to 2, otherwise the strategy is disabled and the variable is set to 1. +backup_only - BOOLEAN + 0 - disabled (default) + not 0 - enabled + + If set, disable the director function while the server is + in backup mode to avoid packet loops for DR/TUN methods. + conntrack - BOOLEAN 0 - disabled (default) not 0 - enabled diff --git a/include/net/ip_vs.h b/include/net/ip_vs.h index 68c69d54d39..fce8e6b66d5 100644 --- a/include/net/ip_vs.h +++ b/include/net/ip_vs.h @@ -976,6 +976,7 @@ struct netns_ipvs { int sysctl_sync_retries; int sysctl_nat_icmp_send; int sysctl_pmtu_disc; + int sysctl_backup_only; /* ip_vs_lblc */ int sysctl_lblc_expiration; @@ -1067,6 +1068,12 @@ static inline int sysctl_pmtu_disc(struct netns_ipvs *ipvs) return ipvs->sysctl_pmtu_disc; } +static inline int sysctl_backup_only(struct netns_ipvs *ipvs) +{ + return ipvs->sync_state & IP_VS_STATE_BACKUP && + ipvs->sysctl_backup_only; +} + #else static inline int sysctl_sync_threshold(struct netns_ipvs *ipvs) @@ -1114,6 +1121,11 @@ static inline int sysctl_pmtu_disc(struct netns_ipvs *ipvs) return 1; } +static inline int sysctl_backup_only(struct netns_ipvs *ipvs) +{ + return 0; +} + #endif /* diff --git a/net/netfilter/ipvs/ip_vs_core.c b/net/netfilter/ipvs/ip_vs_core.c index 47edf5a40a5..18b4bc55fa3 100644 --- a/net/netfilter/ipvs/ip_vs_core.c +++ b/net/netfilter/ipvs/ip_vs_core.c @@ -1577,7 +1577,8 @@ ip_vs_in(unsigned int hooknum, struct sk_buff *skb, int af) } /* ipvs enabled in this netns ? */ net = skb_net(skb); - if (!net_ipvs(net)->enable) + ipvs = net_ipvs(net); + if (unlikely(sysctl_backup_only(ipvs) || !ipvs->enable)) return NF_ACCEPT; ip_vs_fill_iph_skb(af, skb, &iph); @@ -1654,7 +1655,6 @@ ip_vs_in(unsigned int hooknum, struct sk_buff *skb, int af) } IP_VS_DBG_PKT(11, af, pp, skb, 0, "Incoming packet"); - ipvs = net_ipvs(net); /* Check the server status */ if (cp->dest && !(cp->dest->flags & IP_VS_DEST_F_AVAILABLE)) { /* the destination server is not available */ @@ -1815,13 +1815,15 @@ ip_vs_forward_icmp(unsigned int hooknum, struct sk_buff *skb, { int r; struct net *net; + struct netns_ipvs *ipvs; if (ip_hdr(skb)->protocol != IPPROTO_ICMP) return NF_ACCEPT; /* ipvs enabled in this netns ? */ net = skb_net(skb); - if (!net_ipvs(net)->enable) + ipvs = net_ipvs(net); + if (unlikely(sysctl_backup_only(ipvs) || !ipvs->enable)) return NF_ACCEPT; return ip_vs_in_icmp(skb, &r, hooknum); @@ -1835,6 +1837,7 @@ ip_vs_forward_icmp_v6(unsigned int hooknum, struct sk_buff *skb, { int r; struct net *net; + struct netns_ipvs *ipvs; struct ip_vs_iphdr iphdr; ip_vs_fill_iph_skb(AF_INET6, skb, &iphdr); @@ -1843,7 +1846,8 @@ ip_vs_forward_icmp_v6(unsigned int hooknum, struct sk_buff *skb, /* ipvs enabled in this netns ? */ net = skb_net(skb); - if (!net_ipvs(net)->enable) + ipvs = net_ipvs(net); + if (unlikely(sysctl_backup_only(ipvs) || !ipvs->enable)) return NF_ACCEPT; return ip_vs_in_icmp_v6(skb, &r, hooknum, &iphdr); diff --git a/net/netfilter/ipvs/ip_vs_ctl.c b/net/netfilter/ipvs/ip_vs_ctl.c index c68198bf912..9e2d1cccd1e 100644 --- a/net/netfilter/ipvs/ip_vs_ctl.c +++ b/net/netfilter/ipvs/ip_vs_ctl.c @@ -1808,6 +1808,12 @@ static struct ctl_table vs_vars[] = { .mode = 0644, .proc_handler = proc_dointvec, }, + { + .procname = "backup_only", + .maxlen = sizeof(int), + .mode = 0644, + .proc_handler = proc_dointvec, + }, #ifdef CONFIG_IP_VS_DEBUG { .procname = "debug_level", @@ -3741,6 +3747,7 @@ static int __net_init ip_vs_control_net_init_sysctl(struct net *net) tbl[idx++].data = &ipvs->sysctl_nat_icmp_send; ipvs->sysctl_pmtu_disc = 1; tbl[idx++].data = &ipvs->sysctl_pmtu_disc; + tbl[idx++].data = &ipvs->sysctl_backup_only; ipvs->sysctl_hdr = register_net_sysctl(net, "net/ipv4/vs", tbl); -- 2.43.2