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  1. invalid UTF-8 via pl/perl

    Hannu Krosing <hannu@2ndquadrant.com> — 2010-01-02T22:21:51Z

    It is possible to get an invalid byte sequence into a text field via pl,
in this case pl/perl :

---8<------8<------8<------8<------8<------8<---
CREATE TABLE utf_test
(
  id serial PRIMARY KEY,
  data character varying
);

CREATE OR REPLACE FUNCTION invalid_utf_seq()
  RETURNS character varying AS
$BODY$
return "\xd0";
$BODY$
LANGUAGE 'plperlu' VOLATILE STRICT;

insert into utf_test(data) values(invalid_utf_seq());
---8<------8<------8<------8<------8<------8<---

This results in a table, which has invalid utf sequence in it and
consequently does not pass dump/load

What would be the best place to fix this ?

Should there be checks in all text types ? 
(probably too expensive)

Or should pl/perl check it's return values for compliance with
server_encoding ?

Or should postgresql itself check that pl-s return what they promise to
return ?


-- 
Hannu Krosing   http://www.2ndQuadrant.com
PostgreSQL Scalability and Availability 
   Services, Consulting and Training

  2. Re: invalid UTF-8 via pl/perl

    Andrew Dunstan <andrew@dunslane.net> — 2010-01-02T22:50:40Z

    
Hannu Krosing wrote:

[plperl can return data that is not valid in the server encoding and it 
is not caught]

> This results in a table, which has invalid utf sequence in it and
> consequently does not pass dump/load
>
> What would be the best place to fix this ?
>
> Should there be checks in all text types ? 
> (probably too expensive)
>   

The plperl code has no type-specific checks, and in any case limiting it 
to "text" types would defeat third party and contrib types of which it 
knows nothing (think citext). We should check all strings returned by 
plperl.
> Or should pl/perl check it's return values for compliance with
> server_encoding ?
>   

I think the plperl glue code should check returned strings using 
pg_verifymbstr().

> Or should postgresql itself check that pl-s return what they promise to
> return ?
>
>   


There is no central place for it to check. The pl glue code is the right 
place, I think.

cheers

andrew

  3. Re: invalid UTF-8 via pl/perl

    Andrew Dunstan <andrew@dunslane.net> — 2010-01-03T01:51:22Z

    
Andrew Dunstan wrote:
>  
> I think the plperl glue code should check returned strings using 
> pg_verifymbstr().
>
>

Please test this patch. I think we'd probably want to trap the encoding 
error and issue a customised error message, but this plugs all the holes 
I can see with the possible exception of values inserted via SPI calls. 
I'll check that out.

cheers

andrew

  4. Re: invalid UTF-8 via pl/perl

    Andrew Dunstan <andrew@dunslane.net> — 2010-01-03T14:28:29Z

    
Andrew Dunstan wrote:
>
>
> Andrew Dunstan wrote:
>>  
>> I think the plperl glue code should check returned strings using 
>> pg_verifymbstr().
>>
>>
>
> Please test this patch. I think we'd probably want to trap the 
> encoding error and issue a customised error message, but this plugs 
> all the holes I can see with the possible exception of values inserted 
> via SPI calls. I'll check that out.
>
>   

I think the attached patch plugs the direct SPI holes as well.

One thing that I am pondering is: how does SPI handle things if the 
client encoding and server encoding are not the same? Won't the strings 
it passes the parser be interpreted in the client encoding? If so, that 
doesn't seem right at all, since these strings come from a server side 
call and not from the client at all. It looks to me like the call to 
pg_parse_query() in spi.c should possibly be surrounded by code to 
temporarily set the client encoding to the server encoding and then 
restore it afterwards.

cheers

andrew

  5. Re: invalid UTF-8 via pl/perl

    Tom Lane <tgl@sss.pgh.pa.us> — 2010-01-03T17:17:38Z

    Andrew Dunstan <andrew@dunslane.net> writes:
> One thing that I am pondering is: how does SPI handle things if the 
> client encoding and server encoding are not the same?

What?  client_encoding is not used anywhere within the backend.
Everything should be server_encoding.

			regards, tom lane

  6. Re: invalid UTF-8 via pl/perl

    Andrew Dunstan <andrew@dunslane.net> — 2010-01-03T17:44:32Z

    
Tom Lane wrote:
> Andrew Dunstan <andrew@dunslane.net> writes:
>   
>> One thing that I am pondering is: how does SPI handle things if the 
>> client encoding and server encoding are not the same?
>>     
>
> What?  client_encoding is not used anywhere within the backend.
> Everything should be server_encoding.
>
> 			
>   

Oh, for some reason I thought the translation was done in the scanner. 
Sorry for the noise.

cheers

andrew

  7. Re: invalid UTF-8 via pl/perl

    Andrew Dunstan <andrew@dunslane.net> — 2010-01-03T19:54:53Z

    
I wrote:
>
> I think the attached patch plugs the direct SPI holes as well.

There are two issues with this patch. First, how far if at all should it 
be backpatched? All the way, or 8.3, where we tightened the encoding 
rules, or not at all?

Second, It produces errors like this:

    andrew=# select 'a' || invalid_utf_seq() || 'b';
    ERROR:  invalid byte sequence for encoding "UTF8": 0xd0
    HINT:  This error can also happen if the byte sequence does not
    match the encoding expected by the server, which is controlled by
    "client_encoding".
    CONTEXT:  PL/Perl function "invalid_utf_seq"
    andrew=#


That hint seems rather misleading. I'm not sure what we can do about it 
though. If we set the noError param on pg_verifymbstr() we would miss 
the error message that actually identified the bad data, so that doesn't 
seem like a good plan.

cheers

andrew

  8. Re: invalid UTF-8 via pl/perl

    David E. Wheeler <david@kineticode.com> — 2010-01-03T20:09:39Z

    On Jan 3, 2010, at 11:54 AM, Andrew Dunstan wrote:

> There are two issues with this patch. First, how far if at all should it be backpatched? All the way, or 8.3, where we tightened the encoding rules, or not at all?

8.3 seems reasonable.

> Second, It produces errors like this:
> 
>   andrew=# select 'a' || invalid_utf_seq() || 'b';
>   ERROR:  invalid byte sequence for encoding "UTF8": 0xd0
>   HINT:  This error can also happen if the byte sequence does not
>   match the encoding expected by the server, which is controlled by
>   "client_encoding".
>   CONTEXT:  PL/Perl function "invalid_utf_seq"
>   andrew=#
> 
> 
> That hint seems rather misleading. I'm not sure what we can do about it though. If we set the noError param on pg_verifymbstr() we would miss the error message that actually identified the bad data, so that doesn't seem like a good plan.

I'm sure I'm just revealing my ignorance here, but how is the hint misleading?

Best,

David

  9. Re: invalid UTF-8 via pl/perl

    Andrew Dunstan <andrew@dunslane.net> — 2010-01-03T20:14:05Z

    
David E. Wheeler wrote:
>> Second, It produces errors like this:
>>
>>   andrew=# select 'a' || invalid_utf_seq() || 'b';
>>   ERROR:  invalid byte sequence for encoding "UTF8": 0xd0
>>   HINT:  This error can also happen if the byte sequence does not
>>   match the encoding expected by the server, which is controlled by
>>   "client_encoding".
>>   CONTEXT:  PL/Perl function "invalid_utf_seq"
>>   andrew=#
>>
>>
>> That hint seems rather misleading. I'm not sure what we can do about it though. If we set the noError param on pg_verifymbstr() we would miss the error message that actually identified the bad data, so that doesn't seem like a good plan.
>>     
>
> I'm sure I'm just revealing my ignorance here, but how is the hint misleading?
>
>
>   

The string that causes the trouble does not come from the client and has 
nothing to do with client_encoding.

cheers

andrew

  10. Re: invalid UTF-8 via pl/perl

    Tom Lane <tgl@sss.pgh.pa.us> — 2010-01-03T20:15:11Z

    Andrew Dunstan <andrew@dunslane.net> writes:
>     andrew=# select 'a' || invalid_utf_seq() || 'b';
>     ERROR:  invalid byte sequence for encoding "UTF8": 0xd0
>     HINT:  This error can also happen if the byte sequence does not
>     match the encoding expected by the server, which is controlled by
>     "client_encoding".
>     CONTEXT:  PL/Perl function "invalid_utf_seq"

> That hint seems rather misleading. I'm not sure what we can do about it 
> though. If we set the noError param on pg_verifymbstr() we would miss 
> the error message that actually identified the bad data, so that doesn't 
> seem like a good plan.

Yeah, we want the detailed error info.  The problem is that the hint is
targeted to the case where we are checking data coming from the client.
We could add another parameter to pg_verifymbstr to indicate the
context, perhaps.  I'm not sure how to do it exactly --- just a bool
that suppresses the hint, or do we want to make a provision for some
other hint or detail message?

			regards, tom lane

  11. Re: invalid UTF-8 via pl/perl

    Tom Lane <tgl@sss.pgh.pa.us> — 2010-01-03T20:17:11Z

    Andrew Dunstan <andrew@dunslane.net> writes:
> There are two issues with this patch. First, how far if at all should it 
> be backpatched? All the way, or 8.3, where we tightened the encoding 
> rules, or not at all?

Forgot to mention --- I'm not in favor of backpatching.  First because
tightening encoding verification has been a process over multiple
releases; it's not a bug fix in the normal sense of the word, and might
break things that people had been doing without trouble.  Second because
I think we'll have to change pg_verifymbstr's API, and that's not
something to back-patch if we can avoid it.

			regards, tom lane

  12. Re: invalid UTF-8 via pl/perl

    Andrew Dunstan <andrew@dunslane.net> — 2010-01-03T23:40:40Z

    
Tom Lane wrote:
> Andrew Dunstan <andrew@dunslane.net> writes:
>   
>>     andrew=# select 'a' || invalid_utf_seq() || 'b';
>>     ERROR:  invalid byte sequence for encoding "UTF8": 0xd0
>>     HINT:  This error can also happen if the byte sequence does not
>>     match the encoding expected by the server, which is controlled by
>>     "client_encoding".
>>     CONTEXT:  PL/Perl function "invalid_utf_seq"
>>     
>
>   
>> That hint seems rather misleading. I'm not sure what we can do about it 
>> though. If we set the noError param on pg_verifymbstr() we would miss 
>> the error message that actually identified the bad data, so that doesn't 
>> seem like a good plan.
>>     
>
> Yeah, we want the detailed error info.  The problem is that the hint is
> targeted to the case where we are checking data coming from the client.
> We could add another parameter to pg_verifymbstr to indicate the
> context, perhaps.  I'm not sure how to do it exactly --- just a bool
> that suppresses the hint, or do we want to make a provision for some
> other hint or detail message?
>
> 			
>   

Or instead of another param we could change the third param to be one of 
(NO_ERROR, CLIENT_ERROR, SERVER_ERROR) or some such.

Or we could just add another verify func. I don't have terribly strong 
opinions about it.

Incidentally, I guess we need to look at plpython and pltcl for similar 
issues.

cheers

andrew

  13. Re: invalid UTF-8 via pl/perl

    Peter Eisentraut <peter_e@gmx.net> — 2010-01-04T10:46:52Z

    On sön, 2010-01-03 at 18:40 -0500, Andrew Dunstan wrote:
> Incidentally, I guess we need to look at plpython and pltcl for
> similar issues.

I confirm that the same issue exists in plpython.

  14. Re: invalid UTF-8 via pl/perl

    Andrew Dunstan <andrew@dunslane.net> — 2010-01-04T14:44:53Z

    
Tom Lane wrote:
> Andrew Dunstan <andrew@dunslane.net> writes:
>   
>>     andrew=# select 'a' || invalid_utf_seq() || 'b';
>>     ERROR:  invalid byte sequence for encoding "UTF8": 0xd0
>>     HINT:  This error can also happen if the byte sequence does not
>>     match the encoding expected by the server, which is controlled by
>>     "client_encoding".
>>     CONTEXT:  PL/Perl function "invalid_utf_seq"
>>     
>
>   
>> That hint seems rather misleading. I'm not sure what we can do about it 
>> though. If we set the noError param on pg_verifymbstr() we would miss 
>> the error message that actually identified the bad data, so that doesn't 
>> seem like a good plan.
>>     
>
> Yeah, we want the detailed error info.  The problem is that the hint is
> targeted to the case where we are checking data coming from the client.
> We could add another parameter to pg_verifymbstr to indicate the
> context, perhaps.  I'm not sure how to do it exactly --- just a bool
> that suppresses the hint, or do we want to make a provision for some
> other hint or detail message?
>
> 			
>   

This is a mess. It affects four or five levels of visible functions that 
are called in about 18 files.

How about we just change the hint so it also refers to the possibility 
that the data comes from a PL? That would save lots of trouble.

cheers

andrew

  15. Re: invalid UTF-8 via pl/perl

    Tom Lane <tgl@sss.pgh.pa.us> — 2010-01-04T15:11:24Z

    Andrew Dunstan <andrew@dunslane.net> writes:
> How about we just change the hint so it also refers to the possibility 
> that the data comes from a PL? That would save lots of trouble.

Maybe just lose the hint altogether.  It's not adding that much,
and I seem to recall that there have already been complaints about
other cases where it's misleading.

			regards, tom lane

  16. Re: invalid UTF-8 via pl/perl

    Hannu Krosing <hannu@2ndquadrant.com> — 2010-03-08T22:06:21Z

    On Sat, 2010-01-02 at 20:51 -0500, Andrew Dunstan wrote:
> 
> Andrew Dunstan wrote:
> >  
> > I think the plperl glue code should check returned strings using 
> > pg_verifymbstr().
> >
> >
> 
> Please test this patch. I think we'd probably want to trap the encoding 
> error and issue a customised error message, but this plugs all the holes 
> I can see with the possible exception of values inserted via SPI calls. 
> I'll check that out.

I got a report, that the patch fixes one case but leaves open another:

CREATE TABLE utf_test
(
  id serial PRIMARY KEY,
  data character varying
);

CREATE OR REPLACE FUNCTION utf_test()
  RETURNS character varying AS
$BODY$
return "\xd0";
$BODY$
  LANGUAGE 'plperlu' VOLATILE STRICT;

CREATE OR REPLACE FUNCTION utf_test2()
  RETURNS character varying AS
$BODY$
spi_exec_query("insert into utf_test (data) values('\xd0');");
return "VIGA";
$BODY$
  LANGUAGE 'plperlu' VOLATILE STRICT;


The report siad, that patch fixes case

        insert into utf_test (data) values(utf_test());

so that it return an error, but the second function

        select utf_test2();

still enters wrong data to the table

So SPI interface should also be fixed, either from perl side, or maybe
from inside SPI ?




-- 
Hannu Krosing   http://www.2ndQuadrant.com
PostgreSQL Scalability and Availability 
   Services, Consulting and Training

  17. Re: invalid UTF-8 via pl/perl

    Tom Lane <tgl@sss.pgh.pa.us> — 2010-03-09T00:11:21Z

    Hannu Krosing <hannu@2ndquadrant.com> writes:
> So SPI interface should also be fixed, either from perl side, or maybe
> from inside SPI ?

SPI has every right to assume that data it's given is already in the
database encoding.

			regards, tom lane

  18. Re: invalid UTF-8 via pl/perl

    Andrew Dunstan <andrew@dunslane.net> — 2010-03-09T02:52:57Z

    
Tom Lane wrote:
> Hannu Krosing <hannu@2ndquadrant.com> writes:
>   
>> So SPI interface should also be fixed, either from perl side, or maybe
>> from inside SPI ?
>>     
>
> SPI has every right to assume that data it's given is already in the
> database encoding.
>
> 			
>   

Yeah, looks like we missed a few spots. I have added three more checks 
that I think plug the remaining holes in plperl.

Hannu, please test again against CVS HEAD.

cheers

andrew

  19. Re: invalid UTF-8 via pl/perl

    Hannu Krosing <hannu@2ndquadrant.com> — 2010-03-12T14:32:19Z

    On Mon, 2010-03-08 at 21:52 -0500, Andrew Dunstan wrote:
> 
> Tom Lane wrote:
> > Hannu Krosing <hannu@2ndquadrant.com> writes:
> >   
> >> So SPI interface should also be fixed, either from perl side, or maybe
> >> from inside SPI ?
> >>     
> >
> > SPI has every right to assume that data it's given is already in the
> > database encoding.
> >
> > 			
> >   
> 
> Yeah, looks like we missed a few spots. I have added three more checks 
> that I think plug the remaining holes in plperl.
> 
> Hannu, please test again against CVS HEAD.

Seems to work now

Do you plan to back-port this ?

-- 
Hannu Krosing   http://www.2ndQuadrant.com
PostgreSQL Scalability and Availability 
   Services, Consulting and Training

  20. Re: invalid UTF-8 via pl/perl

    Andrew Dunstan <andrew@dunslane.net> — 2010-03-12T15:25:36Z

    
Hannu Krosing wrote:
> On Mon, 2010-03-08 at 21:52 -0500, Andrew Dunstan wrote:
>   
>> Tom Lane wrote:
>>     
>>> Hannu Krosing <hannu@2ndquadrant.com> writes:
>>>   
>>>       
>>>> So SPI interface should also be fixed, either from perl side, or maybe
>>>> from inside SPI ?
>>>>     
>>>>         
>>> SPI has every right to assume that data it's given is already in the
>>> database encoding.
>>>
>>> 			
>>>   
>>>       
>> Yeah, looks like we missed a few spots. I have added three more checks 
>> that I think plug the remaining holes in plperl.
>>
>> Hannu, please test again against CVS HEAD.
>>     
>
> Seems to work now
>
> Do you plan to back-port this ?
>   

I wasn't going to. The previous fixes weren't backpatched either, and in 
general when we have plugged encoding holes the changes have not been 
backpatched, on the grounds that it would be a behaviour change, e.g. 
when we tightened things a lot for 8.3.

I think there an outstanding TODO to plug the other PLs, however. It's a 
pity it has to be done over and over for each PL. Maybe we need some new 
versions of some of the SPI calls that would do the checking so it could 
be centralized.

cheers

andrew