[strongSwan-dev] [PATCH] Avoid duplicate IKE SA from concurrent SADB_ACQUIRE

Jean-Francois HREN jean-francois.hren at stormshield.eu
Thu Nov 22 17:04:51 CET 2018


Hello, 

I'm trying to avoid duplicate IKE SA creation when concurrent SADB_ACQUIRE are received from a FreeBSD kernel: 

[...] 
Nov 22 11:27:29 14[KNL] received an SADB_ACQUIRE 
Nov 22 11:27:29 14[KNL] creating acquire job for policy 192.168.1.1/32 === 192.168.1.2/32 with reqid {2} 
Nov 22 11:27:29 16[MGR] checkout IKE_SA by config 
Nov 22 11:27:29 03[JOB] watcher got notification, rebuilding 
Nov 22 11:27:29 03[JOB] watcher going to poll() 5 fds 
Nov 22 11:27:29 03[JOB] watched FD 7 ready to read 
Nov 22 11:27:29 14[KNL] received an SADB_ACQUIRE 
Nov 22 11:27:29 03[JOB] watcher going to poll() 4 fds 
Nov 22 11:27:29 16[MGR] created IKE_SA (unnamed)[1] 
Nov 22 11:27:29 14[KNL] creating acquire job for policy 192.168.1.1/32 === 192.168.1.2/32 with reqid {1} 
Nov 22 11:27:29 16[MGR] tracking created IKE_SA (unnamed)[1] 
Nov 22 11:27:29 03[JOB] watcher got notification, rebuilding 
Nov 22 11:27:29 06[MGR] checkout IKE_SA by config 
[...] 

The IKE SA created by calling checkout_by_config() is not tracked until its checkin later thus leading to the creation of another unamed IKE SA with the same peer and IKE configurations. 
To circumvent this, I added the created IKE SA as an entry in the IKE SA manager like done (somehow) when calling checkout_by_message(). 
With this, the second SADB_ACQUIRE finds the entry : 

[...] 
Nov 22 11:27:29 16[MGR] checkin IKE_SA (ZDI1NjM0NWFkMDUzYWVmZDU3ZDg0OTcyZTZkOTM3ZTEA)(fb8d6ee724d5d9157518502da724119d)[1] 
Nov 22 11:27:29 16[MGR] checkin of IKE_SA successful 
Nov 22 11:27:29 06[MGR] found existing IKE_SA 1 with a '(ZDI1NjM0NWFkMDUzYWVmZDU3ZDg0OTcyZTZkOTM3ZTEA)(fb8d6ee724d5d9157518502da724119d)' config 
Nov 22 11:27:29 06[IKE] <(ZDI1NjM0NWFkMDUzYWVmZDU3ZDg0OTcyZTZkOTM3ZTEA)(fb8d6ee724d5d9157518502da724119d)|1> queueing CHILD_CREATE task 
Nov 22 11:27:29 06[IKE] <(ZDI1NjM0NWFkMDUzYWVmZDU3ZDg0OTcyZTZkOTM3ZTEA)(fb8d6ee724d5d9157518502da724119d)|1> delaying task initiation, IKE_SA_INIT exchange in progress 
[...] 

avoiding duplicate IKE SA. 

Is this approach correct ? 

Regards, 
Jean-Fran├žois 

--- 
src/libcharon/sa/ike_sa_manager.c | 13 +++++++++++++ 
1 file changed, 13 insertions(+) 

diff --git a/src/libcharon/sa/ike_sa_manager.c b/src/libcharon/sa/ike_sa_manager.c 
index c50c70860..cb31e8ce1 100644 
--- a/src/libcharon/sa/ike_sa_manager.c 
+++ b/src/libcharon/sa/ike_sa_manager.c 
@@ -1462,6 +1462,19 @@ METHOD(ike_sa_manager_t, checkout_by_config, ike_sa_t*, 
if (!ike_sa) 
{ /* no IKE_SA using such a config, hand out a new */ 
ike_sa = checkout_new(this, peer_cfg->get_ike_version(peer_cfg), TRUE); 
+ if (ike_sa) 
+ { 
+ ike_sa_id_t *ike_sa_id = ike_sa->get_id(ike_sa); 
+ entry = entry_create(); 
+ entry->ike_sa_id = ike_sa_id->clone(ike_sa_id); 
+ entry->ike_sa = ike_sa; 
+ entry->checked_out = thread_current(); 
+ segment = put_entry(this, entry); 
+ unlock_single_segment(this, segment); 
+ 
+ DBG2(DBG_MGR, "tracking created IKE_SA %s[%u]", ike_sa->get_name(ike_sa), 
+ ike_sa->get_unique_id(ike_sa)); 
+ } 
} 
charon->bus->set_sa(charon->bus, ike_sa); 

-- 
2.19.1 

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