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Re: Updates of SE-PostgreSQL 8.4devel patches (r1710)

From: KaiGai Kohei <kaigai(at)ak(dot)jp(dot)nec(dot)com>
To: Alvaro Herrera <alvherre(at)commandprompt(dot)com>
Cc: Gregory Stark <stark(at)enterprisedb(dot)com>, Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com>, Stephen Frost <sfrost(at)snowman(dot)net>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, KaiGai Kohei <kaigai(at)kaigai(dot)gr(dot)jp>, Bruce Momjian <bruce(at)momjian(dot)us>, Joshua Brindle <method(at)manicmethod(dot)com>, Robert Haas <robertmhaas(at)gmail(dot)com>, Andrew Dunstan <andrew(at)dunslane(dot)net>, Josh Berkus <josh(at)agliodbs(dot)com>, PG Hackers <pgsql-hackers(at)postgresql(dot)org>, Jaime Casanova <jcasanov(at)systemguards(dot)com(dot)ec>
Subject: Re: Updates of SE-PostgreSQL 8.4devel patches (r1710)
Date: 2009-03-13 01:37:19
Message-ID: 49B9B8CF.2090809@ak.jp.nec.com (view raw or flat)
Thread:
Lists: pgsql-hackers
Alvaro Herrera wrote:
> Gregory Stark escribió:
>> Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com> writes:
>>
>>> KaiGai Kohei wrote:
>>>>  * ACL_SELECT_FOR_UPDATE has same value with ACL_UPDATE, so SE-PostgreSQL
>>>>    checks db_table:{update} permission on SELECT ... FOR SHARE OF,
>>>>    instead of db_table:{lock} permission.
>>> This again falls into the category of trying to have more fine-grained
>>> permissions than vanilla PostgreSQL has. Just give up on the lock permission,
>>> and let it check update permission instead. Yes, it can be annoying that you
>>> need update-permission to do SELECT FOR SHARE, but that's an existing problem
>>> and not in scope for this patch.
>> Would it make sense to instead of removing and deferring pieces bit by bit to
>> instead work the other way around? Extract just the part of the patch that
>> maps SELinux capabilities to Postgres privileges as a first patch? Then
>> discuss any other parts individually at a later date? 
> 
> I think that makes sense.  Implement just a very basic core in a first
> patch, and start adding checks slowly, one patch each.  We have talked
> about "incremental patches" in the past.
> 
> We wouldn't get "unbreakable PostgreSQL" in a single commit, but we
> would at least start moving.
> 
> The good thing about having started in the opposite direction is that by
> now we know that the foundation APIs are good enough to build the
> complete feature.

What should I do for this matter?
At least, it is necessary to decide when we should fix it. v8.4? v8.5?

If we fix it soon, what strategy is desirable?
  1) Add a new GRANT privilege something like "LOCK".
     It is straight forward approach, but contains user visible change.
     In MySQL, it has an individual privilege for explicit table locks.

  2) Shrink ACL_SELECT_FOR_UPDATE to ACL_UPDATE in runtime.
     It is invisible from users, but GRANT UPDATE still contains
     a meaning of explicit table locks.

  3) "GRANT UPDATE ..." also allows users ACL_SELECT_FOR_UPDATE, not only
     ACL_UPDATE.
     It is similar to 2) option, but it also modifies ACL side, not the
     requiredPerms side.

  4) Other strategy?

Thanks,
-- 
OSS Platform Development Division, NEC
KaiGai Kohei <kaigai(at)ak(dot)jp(dot)nec(dot)com>

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