[PATCH nf-next v5] netfilter: ipvs: Fix reuse connection if RS weight is 0

From: yangxingwu
Date: Sun Oct 31 2021 - 22:04:40 EST


We are changing expire_nodest_conn to work even for reused connections when
conn_reuse_mode=0, just as what was done with commit dc7b3eb900aa ("ipvs:
Fix reuse connection if real server is dead").

For controlled and persistent connections, the new connection will get the
needed real server depending on the rules in ip_vs_check_template().

Fixes: d752c3645717 ("ipvs: allow rescheduling of new connections when port reuse is detected")
Co-developed-by: Chuanqi Liu <legend050709@xxxxxx>
Signed-off-by: Chuanqi Liu <legend050709@xxxxxx>
Signed-off-by: yangxingwu <xingwu.yang@xxxxxxxxx>
---
Documentation/networking/ipvs-sysctl.rst | 3 +--
net/netfilter/ipvs/ip_vs_core.c | 8 ++++----
2 files changed, 5 insertions(+), 6 deletions(-)

diff --git a/Documentation/networking/ipvs-sysctl.rst b/Documentation/networking/ipvs-sysctl.rst
index 2afccc63856e..1cfbf1add2fc 100644
--- a/Documentation/networking/ipvs-sysctl.rst
+++ b/Documentation/networking/ipvs-sysctl.rst
@@ -37,8 +37,7 @@ conn_reuse_mode - INTEGER

0: disable any special handling on port reuse. The new
connection will be delivered to the same real server that was
- servicing the previous connection. This will effectively
- disable expire_nodest_conn.
+ servicing the previous connection.

bit 1: enable rescheduling of new connections when it is safe.
That is, whenever expire_nodest_conn and for TCP sockets, when
diff --git a/net/netfilter/ipvs/ip_vs_core.c b/net/netfilter/ipvs/ip_vs_core.c
index 128690c512df..f9d65d2c8da8 100644
--- a/net/netfilter/ipvs/ip_vs_core.c
+++ b/net/netfilter/ipvs/ip_vs_core.c
@@ -1964,7 +1964,6 @@ ip_vs_in(struct netns_ipvs *ipvs, unsigned int hooknum, struct sk_buff *skb, int
struct ip_vs_proto_data *pd;
struct ip_vs_conn *cp;
int ret, pkts;
- int conn_reuse_mode;
struct sock *sk;

/* Already marked as IPVS request or reply? */
@@ -2041,15 +2040,16 @@ ip_vs_in(struct netns_ipvs *ipvs, unsigned int hooknum, struct sk_buff *skb, int
cp = INDIRECT_CALL_1(pp->conn_in_get, ip_vs_conn_in_get_proto,
ipvs, af, skb, &iph);

- conn_reuse_mode = sysctl_conn_reuse_mode(ipvs);
- if (conn_reuse_mode && !iph.fragoffs && is_new_conn(skb, &iph) && cp) {
+ if (!iph.fragoffs && is_new_conn(skb, &iph) && cp) {
bool old_ct = false, resched = false;
+ int conn_reuse_mode = sysctl_conn_reuse_mode(ipvs);

if (unlikely(sysctl_expire_nodest_conn(ipvs)) && cp->dest &&
unlikely(!atomic_read(&cp->dest->weight))) {
resched = true;
old_ct = ip_vs_conn_uses_old_conntrack(cp, skb);
- } else if (is_new_conn_expected(cp, conn_reuse_mode)) {
+ } else if (conn_reuse_mode &&
+ is_new_conn_expected(cp, conn_reuse_mode)) {
old_ct = ip_vs_conn_uses_old_conntrack(cp, skb);
if (!atomic_read(&cp->n_control)) {
resched = true;
--
2.30.2