Re: [RFC][PATCH] Fixing SA/SP dumps on netlink/af_key

David Miller wrote:

From: Timo_Teräs <redacted>
Date: Thu, 17 Jan 2008 11:38:13 +0200

quoted

The af_key issue is that in big dumps you get only first X
entries. The rest of the entries are dropped because the
socket receive buffer goes full. You get data corruption:
missing entries.

This is an inherent aspect of AF_KEY (and what it was
derived from, BSD routing sockets).

Yes, this is the way BSD does it.
 

It has to provide dumps atomically, and if there is no
space there is no way to provide those entries which
would require more rcvbuf space.

RFC does not say it has to be atomic.

It does say that the dump is terminated with SADB_DUMP
message having sadb_seq field set to zero. Currently
that is dropped too when the problem occurs. Thus the
socket is left in a bad state: dump ends never. This
can cause applications without any workarounds to hang.

- Timo