[syslog-ng] syslog-ng-3.38.1 causing type hint errors in patterndb - bug?

Balazs Scheidler bazsi77 at gmail.com
Tue Nov 22 15:03:51 UTC 2022


Hi,

You are right. This was a bug in 3.38 which was fixed in PR #4158, which
has already been merged to master, and I was testing with the current
master and not 3.38.1

Even though I did that PR, I forgot we merged a fix for this already.

With the current master the same is like this:

$ bin/pdbtool test --validate sample.pdb
WARNING: the template specified in value()/<value> options for your
grouping-by() or db-parser() configuration has been changed to support
typing from syslog-ng 4.0. You are using an older config version and your
template contains an unrecognized type-cast, probably a parenthesis in the
value field. This will be interpreted in the `type(value)' format in future
versions. Please add an explicit string() cast as shown in the
'fixed-value' tag of this log message or remove the parenthesis. The value
will be processed as a 'string' expression; config-version='3.38',
name='AUTHPROGRAM', value='su(pam_unix)', fixed-value='string(su(pam_unix))'
$ echo $?
0

The issue is that with the release of v4.0 (which we started to prepare
for), this would become an error in earnest, as pdbtool does not allow you
to specify the config version and uses the syslog-ng version number by
default. And I don't see too much value in extending pdbtool in this
direction, as having to add an explicit config version number to pdbtool
when using it is not very intuitive.

The PR I mentioned in my previous email (#4222) improves this further by
checking the pdb version field (in the topmost <patterndb> tag) and uses
string based values if it's below v6.

What I am thinking about is whether to revert to using an attribute to
specify the type, e.g.

        <values>
           <value name="AUTHPROGRAM"
type="whatevertype-syslog-ng-supports">su(pam_unix)</value>
        </values>

We would default to using a string. The only downside is that
add-contextual-data() uses the parenthesis based format in a CSV file and I
can't extend the CSV format as easily as XML.

So by changing to the use of an attribute types would mean we have
different syntaxes for these use-cases where one can use typed templates:

- config file anywhere: `type(value)`
- add-contextual-data, 3rd column in the CSV file: `type(value)`
- db-parser(): `<value name="foo" type="whatever"/>`




On Tue, Nov 22, 2022 at 3:14 PM Evan Rempel <erempel at uvic.ca> wrote:

> I'm not sure if you still think this is only a warning.
>
> [xerr at pangolin etc]$ rpm -q syslog-ng
> syslog-ng-3.38.1-1.el8.x86_64
> [xerr at pangolin etc]$ rpm -qi syslog-ng
> Name        : syslog-ng
> Version     : 3.38.1
> Release     : 1.el8
> Architecture: x86_64
> Install Date: Thu 03 Nov 2022 04:08:02 AM PDT
> Group       : System Environment/Daemons
> Size        : 3651296
> License     : GPLv2+
> Signature   : RSA/SHA256, Mon 03 Oct 2022 03:00:51 AM PDT, Key ID
> c96af856c87e88fe
> Source RPM  : syslog-ng-3.38.1-1.el8.src.rpm
> Build Date  : Mon 03 Oct 2022 03:00:39 AM PDT
> Build Host  : copr-hv-x86-64-01-prod-02441780-20221003-095224
> Relocations : (not relocatable)
> Vendor      : Fedora Copr - user czanik
> URL         : http://www.balabit.com/network-security/syslog-ng
> Summary     : Next-generation syslog server
>
> A very small patterndb
>
> <patterndb version="4" pub_date="2009-09-01">
>   <ruleset name="su(pam_unix)"
> id="RS-d2fae001-a7f6-4e39-ae62-5658906fe48c">
>     <pattern>su_pam_unix_</pattern>
>     <rules>
>       <rule id="unmatched-program-su(pam_unix)" class="unknown"
> provider="UVic">
>         <patterns>
>            <pattern>@ANYSTRING@</pattern>
>         </patterns>
>         <values>
>            <value name="AUTHPROGRAM">su(pam_unix)</value>
>         </values>
>       </rule>
>     </rules>
>   </ruleset>
> </patterndb>
>
> [xerr at pangolin etc]$ /usr/bin/pdbtool test --validate test.xml
> Error parsing pattern database file; filename='test.xml',
> error='test.xml:10:51: Error compiling value template,
> rule=unmatched-program-su(pam_unix), name=AUTHPROGRAM, value=su(pam_unix),
> error=Unknown type specified in type hinting: su'
>
> Evan.
>
> On 2022-11-22 01:39, Balazs Scheidler wrote:
>
>
> I only got warnings and not errors, when trying to use this in my XML file:
>
>           <value name="seq-matches">su(pam_unix)</value>
>
> how did you execute syslog-ng so you got the error above? The only case
> where this is an error, if you are using "@version: 4.0"
>
> This was the warning produced (both by syslog-ng and pdbtool):
>
> WARNING: the template specified in value()/<value> options for your
> grouping-by() or db-parser() configuration has been changed to support
> typing from syslog-ng 4.0. You are using an older config version and your
> template contains an unrecognized type-cast, probably a parenthesis in the
> value field. This will be interpreted in the `type(value)' format in future
> versions. Please add an explicit string() cast as shown in the
> 'fixed-value' tag of this log message or remove the parenthesis. The value
> will be processed as a 'string' expression; config-version='3.38',
> name='seq-matches', value='su(pam_unix)', fixed-value='string(su(pam_unix))'
>
> I chose to embed the type-hint field in the body of the <value> tag, as
> this is the format that is used everywhere else. I might be able to bump
> the db-parser XML file version, in the file header:
>
> <patterndb version='5'>
>
> I could bump this up to version 6, in which case you'd only need to add
> the type-hint if you also bumped the version number. That I think is doable.
>
> On the documentation front, there's an XML schema in the source tree under
> the doc/xsd/ directory for each version of patterndb, and I assume the
> documentation also has a chapter on the db-parser() format.
>
> On Mon, Nov 21, 2022 at 5:22 PM Evan Rempel <erempel at uvic.ca> wrote:
>
>> We have a patterndb file that contains both patterns and values with
>> fixed text that include a strings of the form "xxxx (yyy)" which now can
>> not be loaded by the patterndb.
>>
>> Syslog-ng throws the error
>>
>> Error parsing pattern database file; ... Error compiling value template,
>> rule=FLARE-3543, name=AUTHPROGRAM, value=su(pam_unix), error=Unknown
>> type specified in type hinting: su'
>>
>> I have not enabled the version 4.0 testing of type hinting. The version
>> configuration is
>>
>> @version: 3.36
>>
>> I am unable to find documentation for the full syntax of the patterndb
>> file (seems to have been lost from the docs since perhaps 3.16?)
>>
>> Is there a patterndb syntax specification document?
>>
>> I would expect that even when type hinting is enabled in the patterndb
>> file, given that it is an XML document, that the type hinting would be
>> part of the XML tag metadata, rather than part of the XML static data.
>>
>> --
>> Evan
>
>
>
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>

-- 
Bazsi
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