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authorJulian Anastasov <ja@ssi.bg>2013-03-10 01:25:04 +0400
committerSimon Horman <horms@verge.net.au>2013-03-19 16:21:51 +0400
commit0c12582fbcdea0cbb0dfd224e1c5f9a8428ffa18 (patch)
tree04cdcc7982a7bed6f51bb2b8b55ffcf83c1f9e50
parentcf2e39429c245245db889fffdfbdf3f889a6cb22 (diff)
downloadlinux-0c12582fbcdea0cbb0dfd224e1c5f9a8428ffa18.tar.xz
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 <dimak@stalker.com> Tested-by: German Myzovsky <lawyer@sipnet.ru> Signed-off-by: Julian Anastasov <ja@ssi.bg> Signed-off-by: Simon Horman <horms@verge.net.au>
-rw-r--r--Documentation/networking/ipvs-sysctl.txt7
-rw-r--r--include/net/ip_vs.h12
-rw-r--r--net/netfilter/ipvs/ip_vs_core.c12
-rw-r--r--net/netfilter/ipvs/ip_vs_ctl.c7
4 files changed, 34 insertions, 4 deletions
diff --git a/Documentation/networking/ipvs-sysctl.txt b/Documentation/networking/ipvs-sysctl.txt
index f2a2488f1bf3..9573d0c48c6e 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 68c69d54d392..fce8e6b66d55 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 47edf5a40a59..18b4bc55fa3d 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 c68198bf9128..9e2d1cccd1eb 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);