[PATCH v5 0/3] net/af_packet: do not return outgoing packets from rte_eth_rx_burst

[Frank Dressler]

On 10/9/26 21:03, Stephen Hemminger wrote:

 >
 > A separate, older bug turned up while checking fanout_add() in the 
kernel. get_fanout_mode() always ORs in PACKET_FANOUT_FLAG_ROLLOVER, and 
the kernel returns -EINVAL for PACKET_FANOUT_ROLLOVER combined with that 
flag. So fanout_mode=rollover with qpairs > 1 always fails setsockopt. 
It’s not part of this series, but it deserves its own Fixes patch
 >

I agree, this is an issue that needs to be fixed. Another issue with 
unconditionally setting PACKET_FANOUT_FLAG_ROLLOVER is that packets 
might spill over to another queue and then be received by a worker that 
does not track the flow the packet belongs to in case of per-worker flow 
tables. So I think that it should be configurable.

A related issue is with the PACKET_FANOUT_FLAG_DEFRAG flag that is also 
always set. Setting it can be harmful to IDS/IPS and similar 
applications that want to see the IP fragments as the come in to detect 
excessive IP fragmentation and overlapping fragments as is used to 
bypass detection.