On 8/5/22 17:08, Paolo Valerio wrote:
> The following test sequence:
> 
> conntrack - IPv4 fragmentation incomplete reassembled packet
> conntrack - IPv4 fragmentation with fragments specified
> 
> leads to a systematic failure of the latter test on the kernel
> datapath (linux).  Multiple executions of the former may also lead to
> multiple failures.
> This is due to the fact that fragments not yet reassembled are kept in
> a queue for /proc/sys/net/ipv4/ipfrag_time seconds, and if the
> kernel receives a fragment already present in the queue, it returns
> -EINVAL.

Thanks for the patch!  I've been looking at the issue earlier
this week.  One thing I don't understand is that we're reloading
all the netfilter modules between tests, shouldn't this clear
all the pending queues?  Or this re-assembly is happening outside
of the conntrack?

> 
> Below the related log message:
> |00058|dpif|WARN|system@ovs-system: execute ct(commit) failed (Invalid 
> argument)
>   on packet 
> udp,vlan_tci=0x0000,dl_src=50:54:00:00:00:09,dl_dst=50:54:00:00:00:0a,
>   
> nw_src=10.1.1.1,nw_dst=10.1.1.2,nw_tos=0,nw_ecn=0,nw_ttl=0,nw_frag=first,tp_src=1,
>   tp_dst=2 udp_csum:0
> 
> Fix the sequence by sending the second fragment in "conntrack - IPv4
> fragmentation incomplete reassembled packet", once the checks are
> done.
> 
> IPv6 tests are not affected as the defrag kernel code path pretends to
> add the duplicate fragment to the queue returning -EINPROGRESS, when a
> duplicate is detected.
> 
> Signed-off-by: Paolo Valerio <[email protected]>
> ---
>  tests/system-traffic.at |    5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/tests/system-traffic.at b/tests/system-traffic.at
> index 1a864057c..8497b4d9e 100644
> --- a/tests/system-traffic.at
> +++ b/tests/system-traffic.at
> @@ -3452,6 +3452,11 @@ AT_CHECK([ovs-ofctl bundle br0 bundle.txt])
>  AT_CHECK([ovs-appctl dpctl/dump-conntrack | FORMAT_CT(10.1.1.2)], [0], [dnl
>  ])
>  
> +dnl Send the second fragment in order to avoid keeping the first fragment
> +dnl in the queue until the expiration occurs. Fragments already queued, if 
> resent,
> +dnl may lead to failures on the kernel datapath.
> +AT_CHECK([ovs-ofctl -O OpenFlow13 packet-out br0 "in_port=1, 
> packet=50540000000a505400000009080045000030000100320011a4860a0101010a01010200010002000800000010203040506070809000010203040506070809,
>  actions=ct(commit)"])
> +
>  OVS_TRAFFIC_VSWITCHD_STOP
>  AT_CLEANUP
>  
> 

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