[strongSwan] AES-GCM-16: payload length is not multiple of a blocksize

[Mike Belopuhov]

Hi,

I'm sorry if this is a wrong place to ask, but I hope I'll get some
hints as I'm not a Linux guy.

So I'm using strongswan-4.4.1 on ubuntu server 10.4 with an updated
kernel: linux-image-2.6.33-02063305-generic (with fixed SHA2) on one
end and OpenBSD with isakmpd on the other.

This is a strongswan config:

conn aesgcm-test-ikev1
     keyexchange=ikev1
     left=172.23.61.144
     leftid=172.23.61.144
     right=172.23.61.156
     rightid=172.23.61.156
     ike=aes128-sha2_256-modp1024!
     esp=aes128gcm16-modp1024!
     mobike=no
     authby=psk
     auto=start

Now the problem is that 90% of packets sent by Linux box in the
quick mode (after establishing an IPsec connection) have a
payload which is not multiple of a cipher blocksize (16).
OpenBSD detects this early on and drops such packets (this
happens before the actual crypto processing).

Funny enough I don't see this happening with neither AES-CBC nor
AES-CTR.

Any opinions/hints/advices?

Thanks,
Mike