Re: Disallowing multiple queries per PQexec()

From: Andres Freund <andres(at)anarazel(dot)de>
To: Andreas Karlsson <andreas(at)proxel(dot)se>
Cc: Bruce Momjian <bruce(at)momjian(dot)us>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Surafel Temesgen <surafel3000(at)gmail(dot)com>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: Disallowing multiple queries per PQexec()
Date: 2017-02-28 20:45:43
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On 2017-02-28 15:59:08 +0100, Andreas Karlsson wrote:
> On 02/28/2017 03:13 PM, Bruce Momjian wrote:
> > I might have added that one; the text is:
> >
> > Consider disallowing multiple queries in PQexec()
> > as an additional barrier to SQL injection attacks
> >
> > and it is a "consider" item. Should it be moved to the Wire Protocol
> > Changes / v4 Protocol section or removed?
> A new protocol version wont solve the breakage of the C API, so I am not
> sure we can ever drop this feature other than by adding a new function
> something in the protocol to support this.

The protocol and C APIs to enforce this are already available, no? The
extended protocol (and thus PQexecParam/PQExecPrepared/...) don't allow
multiple statements:

* We only allow a single user statement in a prepared statement. This is
* mainly to keep the protocol simple --- otherwise we'd need to worry
* about multiple result tupdescs and things like that.
if (list_length(parsetree_list) > 1)
errmsg("cannot insert multiple commands into a prepared statement")));

So if you don't want to allow multiple statements, use PQexecParams et

- Andres

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