[PATCH] ipvs: add a sysctl switch to control ipvs to bypass OUTPUT chain or not

From: longguang.yue
Date: Fri Aug 19 2022 - 06:08:21 EST


Netfilter's rules are matched in sequence, more rules worse performance.
IPVS is a special system, its traffic is clear and definite, for better
performance, should better not be interfered heavily. This patch adds a
sysctl switch and enable ipvs to control traffic to pass netfilter
OUTPUT chain or not.

Signed-off-by: longguang.yue <bigclouds@xxxxxxx>
---
include/net/ip_vs.h | 11 +++++++++++
net/netfilter/ipvs/ip_vs_ctl.c | 8 ++++++++
net/netfilter/ipvs/ip_vs_xmit.c | 31 ++++++++++++++++++++++++-------
3 files changed, 43 insertions(+), 7 deletions(-)

diff --git a/include/net/ip_vs.h b/include/net/ip_vs.h
index ff1804a0c469..c1232ef3a1b5 100644
--- a/include/net/ip_vs.h
+++ b/include/net/ip_vs.h
@@ -932,6 +932,7 @@ struct netns_ipvs {
int sysctl_schedule_icmp;
int sysctl_ignore_tunneled;
int sysctl_run_estimation;
+ int sysctl_output_bypass;

/* ip_vs_lblc */
int sysctl_lblc_expiration;
@@ -1077,6 +1078,11 @@ static inline int sysctl_run_estimation(struct netns_ipvs *ipvs)
return ipvs->sysctl_run_estimation;
}

+static inline int sysctl_output_bypass(struct netns_ipvs *ipvs)
+{
+ return ipvs->sysctl_output_bypass;
+}
+
#else

static inline int sysctl_sync_threshold(struct netns_ipvs *ipvs)
@@ -1174,6 +1180,11 @@ static inline int sysctl_run_estimation(struct netns_ipvs *ipvs)
return 1;
}

+static inline int sysctl_output_bypass(struct netns_ipvs *ipvs)
+{
+ return 0;
+}
+
#endif

/* IPVS core functions
diff --git a/net/netfilter/ipvs/ip_vs_ctl.c b/net/netfilter/ipvs/ip_vs_ctl.c
index efab2b06d373..8a08a783e85e 100644
--- a/net/netfilter/ipvs/ip_vs_ctl.c
+++ b/net/netfilter/ipvs/ip_vs_ctl.c
@@ -2019,6 +2019,12 @@ static struct ctl_table vs_vars[] = {
.mode = 0644,
.proc_handler = proc_dointvec,
},
+ {
+ .procname = "output_bypass",
+ .maxlen = sizeof(int),
+ .mode = 0644,
+ .proc_handler = proc_dointvec,
+ },
#ifdef CONFIG_IP_VS_DEBUG
{
.procname = "debug_level",
@@ -4094,6 +4100,8 @@ static int __net_init ip_vs_control_net_init_sysctl(struct netns_ipvs *ipvs)
tbl[idx++].data = &ipvs->sysctl_ignore_tunneled;
ipvs->sysctl_run_estimation = 1;
tbl[idx++].data = &ipvs->sysctl_run_estimation;
+ ipvs->sysctl_output_bypass = 1;
+ tbl[idx++].data = &ipvs->sysctl_output_bypass;
#ifdef CONFIG_IP_VS_DEBUG
/* Global sysctls must be ro in non-init netns */
if (!net_eq(net, &init_net))
diff --git a/net/netfilter/ipvs/ip_vs_xmit.c b/net/netfilter/ipvs/ip_vs_xmit.c
index 029171379884..46a34dd2555e 100644
--- a/net/netfilter/ipvs/ip_vs_xmit.c
+++ b/net/netfilter/ipvs/ip_vs_xmit.c
@@ -653,8 +653,12 @@ static inline int ip_vs_nat_send_or_cont(int pf, struct sk_buff *skb,
skb_forward_csum(skb);
if (skb->dev)
skb_clear_tstamp(skb);
- NF_HOOK(pf, NF_INET_LOCAL_OUT, cp->ipvs->net, NULL, skb,
- NULL, skb_dst(skb)->dev, dst_output);
+ if (sysctl_output_bypass(cp->ipvs)) {
+ dst_output(cp->ipvs->net, NULL, skb);
+ } else {
+ NF_HOOK(pf, NF_INET_LOCAL_OUT, cp->ipvs->net, NULL, skb,
+ NULL, skb_dst(skb)->dev, dst_output);
+ }
} else
ret = NF_ACCEPT;

@@ -675,8 +679,12 @@ static inline int ip_vs_send_or_cont(int pf, struct sk_buff *skb,
skb_forward_csum(skb);
if (skb->dev)
skb_clear_tstamp(skb);
- NF_HOOK(pf, NF_INET_LOCAL_OUT, cp->ipvs->net, NULL, skb,
- NULL, skb_dst(skb)->dev, dst_output);
+ if (sysctl_output_bypass(cp->ipvs)) {
+ dst_output(cp->ipvs->net, NULL, skb);
+ } else {
+ NF_HOOK(pf, NF_INET_LOCAL_OUT, cp->ipvs->net, NULL, skb,
+ NULL, skb_dst(skb)->dev, dst_output);
+ }
} else
ret = NF_ACCEPT;
return ret;
@@ -1262,10 +1270,19 @@ ip_vs_tunnel_xmit(struct sk_buff *skb, struct ip_vs_conn *cp,
skb->ignore_df = 1;

ret = ip_vs_tunnel_xmit_prepare(skb, cp);
- if (ret == NF_ACCEPT)
- ip_local_out(net, skb->sk, skb);
- else if (ret == NF_DROP)
+ if (ret == NF_ACCEPT) {
+ if (sysctl_output_bypass(cp->ipvs)) {
+ struct iphdr *iph = ip_hdr(skb);
+
+ iph->tot_len = htons(skb->len);
+ ip_send_check(iph);
+ dst_output(cp->ipvs->net, NULL, skb);
+ } else {
+ ip_local_out(net, skb->sk, skb);
+ }
+ } else if (ret == NF_DROP) {
kfree_skb(skb);
+ }

LeaveFunction(10);

--
2.34.1