Re: [HACKERS] pageinspect option to forgo buffer locking? - Mailing list pgsql-hackers

From Tom Lane
Subject Re: [HACKERS] pageinspect option to forgo buffer locking?
Date
Msg-id 18369.1510265651@sss.pgh.pa.us
Whole thread Raw
In response to Re: [HACKERS] pageinspect option to forgo buffer locking?  (Robert Haas <robertmhaas@gmail.com>)
Responses Re: [HACKERS] pageinspect option to forgo buffer locking?  (Andres Freund <andres@anarazel.de>)
List pgsql-hackers
Robert Haas <robertmhaas@gmail.com> writes:
> On Thu, Nov 9, 2017 at 12:58 PM, Andres Freund <andres@anarazel.de> wrote:
>> You can already pass arbitrary byteas to heap_page_items(), so I don't
>> see how this'd change anything exposure-wise? Or are you thinking that
>> users would continually do this with actual page contents and would be
>> more likely to hit edge cases than if using pg_read_binary_file() or
>> such (which obviously sees an out of date page)?

> More the latter.  It's not really an increase in terms of security
> exposure, but it might lead to more trouble in practice.

If we do this, I'd suggest exposing it as a separate SQL function
get_raw_page_unlocked() rather than as an option to get_raw_page().

The reasoning is that if we ever allow these functions to be controlled
via GRANT instead of hardwired superuser checks (cf nearby debate about
lo_import/lo_export), one might reasonably consider the unlocked form as
more risky than the locked form, and hence not wish to have to give out
privileges to both at once.
        regards, tom lane


-- 
Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-hackers

pgsql-hackers by date:

Previous
From: Tom Lane
Date:
Subject: Re: [HACKERS] Simplify ACL handling for large objects and removal of superuser() checks
Next
From: Andres Freund
Date:
Subject: Re: [HACKERS] pageinspect option to forgo buffer locking?