ssg.build_remediations.expand_xccdf_subs()

Complexity

Conditions

29

Size

Total Lines	254
Code Lines	106

Duplication

Lines	0
Ratio	0 %

Code Coverage

Tests	1
CRAP Score	843.7856

Importance

Changes

0

from __future__ import absolute_import
def expand_xccdf_subs(fix, remediation_type, remediation_functions):
    """For those remediation scripts utilizing some of the internal SCAP
    Security Guide remediation functions expand the selected shell variables
    and remediation functions calls with <xccdf:sub> element

    This routine translates any instance of the 'populate' function call in
    the form of:

            populate variable_name

    into

            variable_name="<sub idref="variable_name"/>"

    Also transforms any instance of the 'ansible-populate' function call in the
    form of:
            (ansible-populate variable_name)
    into

            <sub idref="variable_name"/>

    Also transforms any instance of some other known remediation function (e.g.
    'replace_or_append' etc.) from the form of:

            function_name "arg1" "arg2" ... "argN"

    into:

            <sub idref="function_function_name"/>
            function_name "arg1" "arg2" ... "argN"
    """

    if remediation_type == "ansible":
        fix_text = fix.text

        if "(ansible-populate " in fix_text:
            raise RuntimeError(
                "(ansible-populate VAR) has been deprecated. Please use "
                "(xccdf-var VAR) instead. Keep in mind that the latter will "
                "make an ansible variable out of XCCDF Value as opposed to "
                "substituting directly."
            )

        # If you change this string make sure it still matches the pattern
        # defined in OpenSCAP. Otherwise you break variable handling in
        # 'oscap xccdf generate fix' and the variables won't be customizable!
        # https://github.com/OpenSCAP/openscap/blob/1.2.17/src/XCCDF_POLICY/xccdf_policy_remediate.c#L588
        #   const char *pattern =
        #     "- name: XCCDF Value [^ ]+ # promote to variable\n  set_fact:\n"
        #     "    ([^:]+): (.+)\n  tags:\n    - always\n";
        # We use !!str typecast to prevent treating values as different types
        # eg. yes as a bool or 077 as an octal number
        fix_text = re.sub(
            r"- \(xccdf-var\s+(\S+)\)",
            r"- name: XCCDF Value \1 # promote to variable\n"
            r"  set_fact:\n"
            r"    \1: !!str (ansible-populate \1)\n"
            r"  tags:\n"
            r"    - always",
            fix_text
        )

        pattern = r'\(ansible-populate\s*(\S+)\)'

        # we will get list what looks like
        # [text, varname, text, varname, ..., text]
        parts = re.split(pattern, fix_text)

        fix.text = parts[0]  # add first "text"
        for index in range(1, len(parts), 2):
            varname = parts[index]
            text_between_vars = parts[index + 1]

            # we cannot combine elements and text easily
            # so text is in ".tail" of element
            xccdfvarsub = ElementTree.SubElement(fix, "sub", idref=varname)
            xccdfvarsub.tail = text_between_vars
        return

    elif remediation_type == "puppet":
        pattern = r'\(puppet-populate\s*(\S+)\)'

        # we will get list what looks like
        # [text, varname, text, varname, ..., text]
        parts = re.split(pattern, fix.text)

        fix.text = parts[0]  # add first "text"
        for index in range(1, len(parts), 2):
            varname = parts[index]
            text_between_vars = parts[index + 1]

            # we cannot combine elements and text easily
            # so text is in ".tail" of element
            xccdfvarsub = ElementTree.SubElement(fix, "sub", idref=varname)
            xccdfvarsub.tail = text_between_vars
        return

    elif remediation_type == "anaconda":
        pattern = r'\(anaconda-populate\s*(\S+)\)'

        # we will get list what looks like
        # [text, varname, text, varname, ..., text]
        parts = re.split(pattern, fix.text)

        fix.text = parts[0]  # add first "text"
        for index in range(1, len(parts), 2):
            varname = parts[index]
            text_between_vars = parts[index + 1]

            # we cannot combine elements and text easily
            # so text is in ".tail" of element
            xccdfvarsub = ElementTree.SubElement(fix, "sub", idref=varname)
            xccdfvarsub.tail = text_between_vars
        return

    elif remediation_type == "bash":
        # This remediation script doesn't utilize internal remediation functions
        # Skip it without any further processing
        if 'remediation_functions' not in fix.text:
            return

        # This remediation script utilizes some of internal remediation functions
        # Expand shell variables and remediation functions calls with <xccdf:sub>
        # elements
        pattern = r'\n+(\s*(?:' + r'|'.join(remediation_functions) + r')[^\n]*)\n'
        patcomp = re.compile(pattern, re.DOTALL)
        fixparts = re.split(patcomp, fix.text)
        if fixparts[0] is not None:
            # Split the portion of fix.text from fix start to first call of
            # remediation function, keeping only the third part:
            # * tail        to hold part of the fix.text after inclusion,
            #               but before first call of remediation function
            try:
                rfpattern = '(.*remediation_functions)(.*)'
                rfpatcomp = re.compile(rfpattern, re.DOTALL)
                _, _, tail, _ = re.split(rfpatcomp, fixparts[0], maxsplit=2)
            except ValueError:
                sys.stderr.write("Processing fix.text for: %s rule\n"
                                 % fix.get('rule'))
                sys.stderr.write("Unable to extract part of the fix.text "
                                 "after inclusion of remediation functions."
                                 " Aborting..\n")
                sys.exit(1)
            # If the 'tail' is not empty, make it new fix.text.
            # Otherwise use ''
            fix.text = tail if tail is not None else ''

The variable tail does not seem to be defined for all execution paths.

            # Drop the first element of 'fixparts' since it has been processed
            fixparts.pop(0)
            # Perform sanity check on new 'fixparts' list content (to continue
            # successfully 'fixparts' has to contain even count of elements)
            if len(fixparts) % 2 != 0:
                sys.stderr.write("Error performing XCCDF expansion on "
                                 "remediation script: %s\n"
                                 % fix.get("rule"))
                sys.stderr.write("Invalid count of elements. Exiting!\n")
                sys.exit(1)
            # Process remaining 'fixparts' elements in pairs
            # First pair element is remediation function to be XCCDF expanded
            # Second pair element (if not empty) is the portion of the original
            # fix text to be used in newly added sublement's tail
            for idx in range(0, len(fixparts), 2):
                # We previously removed enclosing newlines when creating
                # fixparts list. Add them back and reuse the above 'pattern'
                fixparts[idx] = "\n%s\n" % fixparts[idx]
                # Sanity check (verify the first field truly contains call of
                # some of the remediation functions)
                if re.match(pattern, fixparts[idx], re.DOTALL) is not None:
                    # This chunk contains call of 'populate' function
                    if "populate" in fixparts[idx]:
                        varname, fixtextcontrib = get_populate_replacement(remediation_type,
                                                                           fixparts[idx])
                        # Define new XCCDF <sub> element for the variable
                        xccdfvarsub = ElementTree.Element("sub", idref=varname)

                        # If this is first sub element,
                        # the textcontribution needs to go to fix text
                        # otherwise, append to last subelement
                        nfixchildren = len(list(fix))
                        if nfixchildren == 0:
                            fix.text += fixtextcontrib
                        else:
                            previouselem = fix[nfixchildren-1]
                            previouselem.tail += fixtextcontrib

                        # If second pair element is not empty, append it as
                        # tail for the subelement (prefixed with closing '"')
                        if fixparts[idx + 1] is not None:
                            xccdfvarsub.tail = '"' + '\n' + fixparts[idx + 1]
                        # Otherwise append just enclosing '"'
                        else:
                            xccdfvarsub.tail = '"' + '\n'
                        # Append the new subelement to the fix element
                        fix.append(xccdfvarsub)
                    # This chunk contains call of other remediation function
                    else:
                        # Extract remediation function name
                        funcname = re.search(r'\n\s*(\S+)(| .*)\n',
                                             fixparts[idx],
                                             re.DOTALL).group(1)
                        # Define new XCCDF <sub> element for the function
                        xccdffuncsub = ElementTree.Element(
                            "sub", idref='function_%s' % funcname)
                        # Append original function call into tail of the
                        # subelement
                        xccdffuncsub.tail = fixparts[idx]
                        # If the second element of the pair is not empty,
                        # append it to the tail of the subelement too
                        if fixparts[idx + 1] is not None:
                            xccdffuncsub.tail += fixparts[idx + 1]
                        # Append the new subelement to the fix element
                        fix.append(xccdffuncsub)
                        # Ensure the newly added <xccdf:sub> element for the
                        # function will be always inserted at newline
                        # If xccdffuncsub is the first <xccdf:sub> element
                        # being added as child of <fix> and fix.text doesn't
                        # end up with newline character, append the newline
                        # to the fix.text
                        if list(fix).index(xccdffuncsub) == 0:
                            if re.search(r'.*\n$', fix.text) is None:
                                fix.text += '\n'
                        # If xccdffuncsub isn't the first child (first
                        # <xccdf:sub> being added), and tail of previous
                        # child doesn't end up with newline, append the newline
                        # to the tail of previous child
                        else:
                            previouselem = fix[list(fix).index(xccdffuncsub) - 1]
                            if re.search(r'.*\n$', previouselem.tail) is None:
                                previouselem.tail += '\n'

        # Perform a sanity check if all known remediation function calls have been
        # properly XCCDF substituted. Exit with failure if some wasn't

        # First concat output form of modified fix text (including text appended
        # to all children of the fix)
        modfix = [fix.text]
        for child in fix.getchildren():
            if child is not None and child.text is not None:
                modfix.append(child.text)
        modfixtext = "".join(modfix)
        for func in remediation_functions:
            # Then efine expected XCCDF sub element form for this function
            funcxccdfsub = "<sub idref=\"function_%s\"" % func
            # Finally perform the sanity check -- if function was properly XCCDF
            # substituted both the original function call and XCCDF <sub> element
            # for that function need to be present in the modified text of the fix
            # Otherwise something went wrong, thus exit with failure
            if func in modfixtext and funcxccdfsub not in modfixtext:
                sys.stderr.write("Error performing XCCDF <sub> substitution "
                                 "for function %s in %s fix. Exiting...\n"
                                 % (func, fix.get("rule")))
                sys.exit(1)
    else:
        sys.stderr.write("Unknown remediation type '%s'\n" % (remediation_type))
        sys.exit(1)