On 8/26/14, 6:05 AM, Jan Lieskovsky wrote:
> Hello folks,
>
> within effort to rewrite umask checks (more about the motivation for this
> later within its dedicated email thread) encountered the following
> RHEL/6/transforms/cpe_generate.py script related issue.
>
> Use case: Let's consider RHEL/6/input/checks/accounts_umask_etc_profile.xml
> OVAL check would have the form as attached (it's not the final form of the
> check. The final one will be slightly more complex yet. In any case the
> attached
> form is syntactically correct one & sufficient to demonstrate the issue I
> would
> like to speak below about), then running 'make' in scap-security-guide/RHEL/6
> subdirectory returns the following error when trying to generate the
> datastream
> output:
>
> oscap ds sds-compose output/ssg-rhel6-xccdf-1.2.xml output/ssg-rhel6-ds.xml
> oscap ds sds-add output/ssg-rhel6-cpe-dictionary.xml output/ssg-rhel6-ds.xml
> File 'output/ssg-rhel6-ds.xml' line 32236: Element
> '{http://oval.mitre.org/XMLSchema/oval-definitions-5}object_component': No
> match found for key-sequence ['oval:ssg:obj:111'] of keyref
> '{http://oval.mitre.org/XMLSchema/oval-definitions-5}objectKeyRef'.
> Invalid SCAP Source Datastream content(1.2) in output/ssg-rhel6-ds.xml.
> make: *** [content] Error 1
Tried to replicate this to no avail... building on RHEL 6:
> xsltproc /usr/share/openscap/xsl/xccdf_1.1_remove_dangling_sub.xsl
> output/ssg-rhel6-xccdf.xml \
> > output/ssg-rhel6-xccdf-nodangles.xml
> xsltproc --stringparam reverse_DNS org.ssgproject.content
> /usr/share/openscap/xsl/xccdf_1.1_to_1.2.xsl \
> output/ssg-rhel6-xccdf-nodangles.xml >
> output/ssg-rhel6-xccdf-1.2.xml
> sed -i '/idref="dangling reference to /d' output/ssg-rhel6-xccdf-1.2.xml
> oscap ds sds-compose output/ssg-rhel6-xccdf-1.2.xml
> output/ssg-rhel6-ds.xml
> oscap ds sds-add output/ssg-rhel6-cpe-dictionary.xml
> output/ssg-rhel6-ds.xml
> oscap ds sds-add output/ssg-rhel6-oval.xml output/ssg-rhel6-ds.xml
>
> Investigated the problem further, and noticed the problem is content of
> RHEL/6/output/ssg-rhel6-cpe-oval.xml
> file. Namely it contains the content as follows:
>
> ...
> </states><variables><local_variable id="oval:ssg:var:110" datatype="int"
> comment="x" version="1">
> <substring substring_start="1" substring_length="1">
> <object_component item_field="subexpression"
> object_ref="oval:ssg:obj:111"/>
> </substring>
> </local_variable>
> </variables></oval_definitions>
>
> which after more detailed look explains why 'oval:ssg:obj:111' wouldn't be
> defined in output/ssg-rhel6-ds.xml
> file (the oval:ssg:var:110 local variable references oval:ssg:obj:111, but
> this object isn't defined
> within that ssg-rhel6-cpe-oval.xml file [only in different part of
> ssg-rhel6-ds.xml file]).
>
> So investigated further to see, which part of the RHEL/6's Makefile generates
> / includes this variable,
> when creating ssg-rhel6-cpe-oval.xml file, and noticed the responsible script
> being RHEL/6/transforms/cpe_generate.py.
>
> The questions:
> 1) Can someone more familiar with the implementation of this script clarify
> it's purpose?
> It requires two input files (OVAL file & CPE file), and one identifier
> (ssg), and generates
> 'ssg-rhel6-cpe-oval.xml' file.
>
> 2) Can someone more familiar with the implementation of this script clarify
> the need for the
> following construct within it?:
>
> 82 variables = ovaltree.find("./{%s}variables" % oval_ns)
> 83 cpe_variables = extract_referred_nodes(ovaltree, variables,
> "var_ref")
> 84 if cpe_variables:
> 85 variables.clear()
> 86 [variables.append(cpe_variable) for cpe_variable in
> cpe_variables]
> 87 else:
> 88 ovaltree.remove(variables)
>
> Is it there to (when generating ssg.ini object name to object id file) to
> incorporate
> also OVAL local_variables that might reference another variables via the
> "var_ref"
> attribute?
>
> The reason why I am asking being that have noticed, when I comment out
> the following part
> of this file (IOW when the cpe_generate.py script has the following form
> around the
> critical lines):
>
> 82 variables = ovaltree.find("./{%s}variables" % oval_ns)
> 83 #cpe_variables = extract_referred_nodes(ovaltree, variables,
> "var_ref")
> 84 #if cpe_variables:
> 85 # variables.clear()
> 86 # [variables.append(cpe_variable) for cpe_variable in
> cpe_variables]
> 87 #else:
> 88 ovaltree.remove(variables)
>
> the aforementioned error message:
>
> File 'output/ssg-rhel6-ds.xml' line 32236: Element
> '{http://oval.mitre.org/XMLSchema/oval-definitions-5}object_component': No
> match found for key-sequence ['oval:ssg:obj:111'] of keyref
> '{http://oval.mitre.org/XMLSchema/oval-definitions-5}objectKeyRef'.
>
> when generating ssg-rhel6-ds.xml isn't reported anymore & the content
> builds successfully.
>
> Since I wouldn't like to break something, the purpose of this email is to ask
> someone more familiar
> with the implementation of cpe_generate.py script, why the cpe_variables
> section (lines from #83 up
> to #87 need to be present there)?
>
> Is there a chance this behaviour is somehow related with the following commit:
> [1]
> https://github.com/OpenSCAP/scap-security-guide/commit/59d650ffe140e4ae742dc7b4893df278bf1b3334
> ?
>
> For example in the sense the original meaning of 'cpe_variables' part of
> cpe_generate.py was to include
> also variables, that reference other variables via 'var_ref' attribute into
> final ssg.ini file
> (and assign IDs in the form of "oval:ssg:var:..." to them too)? But the
> change [1] is causing
> variable objects having 'var_ref' attribute is now included within
> relabelids.py script & therefore
> the 'cpe_variables' section of the cpe_generate.py script is not needed
> anymore & can be safely remove
> as suggested above (or in the also attached
> RHEL_6_transforms_cpe_generate_py.diff patch)?
>
> Any hints you can provide wrt to observed cpe_generate.py behaviour & how to
> possibly fix it
> are appreciated.
>
> Thank you && Regards, Jan.
> --
> Jan iankko Lieskovsky / Red Hat Security Technologies Team
>
> P.S.: If wondering why this problem didn't show earlier, assuming there isn't
> such construct
> (local_variable referencing another local_variable referencing
> textfilecontent54_object)
> used in the current content yet. Tried also different approach
> (encapsulate those local_variables
> into variable_objects & reference those objects instead), but it didn't
> help (in the sense
> datastream output would be successfully generated).
>
>
--
Shawn Wells
Director, Innovation Programs
[email protected] | 443.534.0130
@shawndwells
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