[PATCH] ipvs: make drop_entry protection effective for SIP-pe

[Marco Angaroni <marcoangaroni@xxxxxxxxx>]

DoS protection policy that deletes connections to avoid out of memory is
currently not effective for SIP-pe plus OPS-mode for two reasons:
  1) connection templates (holding SIP call-id) are always skipped in
     ip_vs_random_dropentry()
  2) in_pkts counter (used by drop_entry algorithm) is not incremented
     for connection templates

This patch addresses such problems with the following changes:
  a) connection templates associated (via their dest) to virtual-services 
     configured in OPS mode are included in ip_vs_random_dropentry()
     monitoring. This applies to SIP-pe over UDP (which requires OPS mode),
     but is more general principle: when OPS is controlled by templates
     memory can be used only by templates themselves, since OPS conns are
     deleted after packet is forwarded.
  b) OPS connections, if controlled by a template, cause increment of 
     in_pkts counter of their template. This is already happening but only
     in case director is in master-slave mode (see ip_vs_sync_conn()).

Signed-off-by: Marco Angaroni <marcoangaroni@xxxxxxxxx>
---
 net/netfilter/ipvs/ip_vs_conn.c | 22 +++++++++++++++++++---
 net/netfilter/ipvs/ip_vs_core.c |  8 +++++++-
 2 files changed, 26 insertions(+), 4 deletions(-)

diff --git a/net/netfilter/ipvs/ip_vs_conn.c b/net/netfilter/ipvs/ip_vs_conn.c
index 292365f..2cb3c62 100644
--- a/net/netfilter/ipvs/ip_vs_conn.c
+++ b/net/netfilter/ipvs/ip_vs_conn.c
@@ -1261,6 +1261,16 @@ static inline int todrop_entry(struct ip_vs_conn *cp)
        return 1;
 }
 
+static inline bool ip_vs_conn_ops_mode(struct ip_vs_conn *cp)
+{
+       struct ip_vs_service *svc;
+
+       if (!cp->dest)
+               return false;
+       svc = rcu_dereference(cp->dest->svc);
+       return svc && (svc->flags & IP_VS_SVC_F_ONEPACKET);
+}
+
 /* Called from keventd and must protect itself from softirqs */
 void ip_vs_random_dropentry(struct netns_ipvs *ipvs)
 {
@@ -1275,11 +1285,16 @@ void ip_vs_random_dropentry(struct netns_ipvs *ipvs)
                unsigned int hash = prandom_u32() & ip_vs_conn_tab_mask;
 
                hlist_for_each_entry_rcu(cp, &ip_vs_conn_tab[hash], c_list) {
-                       if (cp->flags & IP_VS_CONN_F_TEMPLATE)
-                               /* connection template */
-                               continue;
                        if (cp->ipvs != ipvs)
                                continue;
+                       if (cp->flags & IP_VS_CONN_F_TEMPLATE) {
+                               if (atomic_read(&cp->n_control) ||
+                                   !ip_vs_conn_ops_mode(cp))
+                                       continue;
+                               else
+                                       /* connection template of OPS */
+                                       goto try_drop;
+                       }
                        if (cp->protocol == IPPROTO_TCP) {
                                switch(cp->state) {
                                case IP_VS_TCP_S_SYN_RECV:
@@ -1307,6 +1322,7 @@ void ip_vs_random_dropentry(struct netns_ipvs *ipvs)
                                        continue;
                                }
                        } else {
+try_drop:
                                if (!todrop_entry(cp))
                                        continue;
                        }
diff --git a/net/netfilter/ipvs/ip_vs_core.c b/net/netfilter/ipvs/ip_vs_core.c
index 398ccb5..a97de51 100644
--- a/net/netfilter/ipvs/ip_vs_core.c
+++ b/net/netfilter/ipvs/ip_vs_core.c
@@ -612,7 +612,10 @@ int ip_vs_leave(struct ip_vs_service *svc, struct sk_buff 
*skb,
                ret = cp->packet_xmit(skb, cp, pd->pp, iph);
                /* do not touch skb anymore */
 
-               atomic_inc(&cp->in_pkts);
+               if ((cp->flags & IP_VS_CONN_F_ONE_PACKET) && cp->control)
+                       atomic_inc(&cp->control->in_pkts);
+               else
+                       atomic_inc(&cp->in_pkts);
                ip_vs_conn_put(cp);
                return ret;
        }
@@ -1971,6 +1974,9 @@ ip_vs_in(struct netns_ipvs *ipvs, unsigned int hooknum, 
struct sk_buff *skb, int
 
        if (ipvs->sync_state & IP_VS_STATE_MASTER)
                ip_vs_sync_conn(ipvs, cp, pkts);
+       else if ((cp->flags & IP_VS_CONN_F_ONE_PACKET) && cp->control)
+               /* increment is done inside ip_vs_sync_conn too */
+               atomic_inc(&cp->control->in_pkts);
 
        ip_vs_conn_put(cp);
        return ret;
-- 
1.8.3.1

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