Re: BUG #15182: Canceling authentication due to timeout aka Denial ofService Attack

On Thu, Jul 19, 2018 at 7:17 PM, Jeremy Schneider <schnjere@amazon.com> wrote:
> I'd like to bump this old bug that Lloyd filed for more discussion. It
> seems serious enough to me that we should at least talk about it.
>
> Anyone with simply the login privilege and the ability to run SQL can
> instantly block all new incoming connections to a DB including new
> superuser connections.
>
> session 1:
> select pg_sleep(9999999999) from pg_stat_activity;
>
> session 2:
> vacuum full pg_authid; -or- truncate table pg_authid;
>
> (there are likely other SQL you could run in session 2 as well.)

ExecuteTruncate needs to be refactored to use RangeVarGetRelidExtended
with a non-NULL callback rather than heap_openrv, and
expand_vacuum_rel needs to use RangeVarGetRelidExtended with a
callback instead of RangeVarGetRelid.  See
cbe24a6dd8fb224b9585f25b882d5ffdb55a0ba5 as an example of what to do.
I fixed a large number of cases of this problem back around that time,
but then ran out of steam and had to move onto other things before I
got them all.  Patches welcome.

-- 
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company