[Buildroot] [PATCH v2 3/7] support/scripts/cpedb.py: new CPE XML helper

[Yann E. MORIN <yann.morin.1998@free.fr>]

Gr?gory, All,

On 2021-01-31 14:38 +0100, Thomas Petazzoni spake thusly:
> From: Matt Weber <matthew.weber@rockwellcollins.com>
> 
> Python class which consumes a NIST CPE XML and provides helper
> functions to access and search the db's data.
> 
>  - Defines the CPE as a object with operations / formats
>  - Processing of CPE dictionary
> 
> Signed-off-by: Matthew Weber <matthew.weber@rockwellcollins.com>
> Co-Developed-by: Gr?gory Clement <gregory.clement@bootlin.com>

Gr?gory, you need to add your SOB line right after your CDB line.

Ditto for the following patch.

Regards,
Yann E. MORIN.

> Co-Developed-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
> Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
> ---
>  support/scripts/cpedb.py | 203 +++++++++++++++++++++++++++++++++++++++
>  1 file changed, 203 insertions(+)
>  create mode 100644 support/scripts/cpedb.py
> 
> diff --git a/support/scripts/cpedb.py b/support/scripts/cpedb.py
> new file mode 100644
> index 0000000000..825ed6cb1e
> --- /dev/null
> +++ b/support/scripts/cpedb.py
> @@ -0,0 +1,203 @@
> +#!/usr/bin/env python3
> +
> +import xml.etree.ElementTree as ET
> +from xml.etree.ElementTree import Element, SubElement
> +import gzip
> +import os
> +import pickle
> +import requests
> +import time
> +from xml.dom import minidom
> +
> +VALID_REFS = ['VENDOR', 'VERSION', 'CHANGE_LOG', 'PRODUCT', 'PROJECT', 'ADVISORY']
> +
> +CPEDB_URL = "https://static.nvd.nist.gov/feeds/xml/cpe/dictionary/official-cpe-dictionary_v2.3.xml.gz"
> +
> +ns = {
> +    '': 'http://cpe.mitre.org/dictionary/2.0',
> +    'cpe-23': 'http://scap.nist.gov/schema/cpe-extension/2.3',
> +    'xml': 'http://www.w3.org/XML/1998/namespace'
> +}
> +
> +
> +class CPE:
> +    def __init__(self, cpe_str, titles, refs):
> +        self.cpe_str = cpe_str
> +        self.titles = titles
> +        self.references = refs
> +        self.cpe_cur_ver = "".join(self.cpe_str.split(":")[5:6])
> +
> +    def update_xml_dict(self):
> +        ET.register_namespace('', 'http://cpe.mitre.org/dictionary/2.0')
> +        cpes = Element('cpe-list')
> +        cpes.set('xmlns:cpe-23', "http://scap.nist.gov/schema/cpe-extension/2.3")
> +        cpes.set('xmlns:ns6', "http://scap.nist.gov/schema/scap-core/0.1")
> +        cpes.set('xmlns:scap-core', "http://scap.nist.gov/schema/scap-core/0.3")
> +        cpes.set('xmlns:config', "http://scap.nist.gov/schema/configuration/0.1")
> +        cpes.set('xmlns:xsi', "http://www.w3.org/2001/XMLSchema-instance")
> +        cpes.set('xmlns:meta', "http://scap.nist.gov/schema/cpe-dictionary-metadata/0.2")
> +        cpes.set('xsi:schemaLocation', " ".join(["http://scap.nist.gov/schema/cpe-extension/2.3",
> +                                                 "https://scap.nist.gov/schema/cpe/2.3/cpe-dictionary-extension_2.3.xsd",
> +                                                 "http://cpe.mitre.org/dictionary/2.0",
> +                                                 "https://scap.nist.gov/schema/cpe/2.3/cpe-dictionary_2.3.xsd",
> +                                                 "http://scap.nist.gov/schema/cpe-dictionary-metadata/0.2",
> +                                                 "https://scap.nist.gov/schema/cpe/2.1/cpe-dictionary-metadata_0.2.xsd",
> +                                                 "http://scap.nist.gov/schema/scap-core/0.3",
> +                                                 "https://scap.nist.gov/schema/nvd/scap-core_0.3.xsd",
> +                                                 "http://scap.nist.gov/schema/configuration/0.1",
> +                                                 "https://scap.nist.gov/schema/nvd/configuration_0.1.xsd",
> +                                                 "http://scap.nist.gov/schema/scap-core/0.1",
> +                                                 "https://scap.nist.gov/schema/nvd/scap-core_0.1.xsd"]))
> +        item = SubElement(cpes, 'cpe-item')
> +        cpe_short_name = CPE.short_name(self.cpe_str)
> +        cpe_new_ver = CPE.version_update(self.cpe_str)
> +
> +        item.set('name', 'cpe:/' + cpe_short_name)
> +        self.titles[0].text.replace(self.cpe_cur_ver, cpe_new_ver)
> +        for title in self.titles:
> +            item.append(title)
> +        if self.references:
> +            item.append(self.references)
> +        cpe23item = SubElement(item, 'cpe-23:cpe23-item')
> +        cpe23item.set('name', self.cpe_str)
> +
> +        # Generate the XML as a string
> +        xmlstr = ET.tostring(cpes)
> +
> +        # And use minidom to pretty print the XML
> +        return minidom.parseString(xmlstr).toprettyxml(encoding="utf-8").decode("utf-8")
> +
> +    @staticmethod
> +    def version(cpe):
> +        return cpe.split(":")[5]
> +
> +    @staticmethod
> +    def product(cpe):
> +        return cpe.split(":")[4]
> +
> +    @staticmethod
> +    def short_name(cpe):
> +        return ":".join(cpe.split(":")[2:6])
> +
> +    @staticmethod
> +    def version_update(cpe):
> +        return ":".join(cpe.split(":")[5:6])
> +
> +    @staticmethod
> +    def no_version(cpe):
> +        return ":".join(cpe.split(":")[:5])
> +
> +
> +class CPEDB:
> +    def __init__(self, nvd_path):
> +        self.all_cpes = dict()
> +        self.all_cpes_no_version = dict()
> +        self.nvd_path = nvd_path
> +
> +    def gen_cached_cpedb(self, cpedb, cache_all_cpes, cache_all_cpes_no_version):
> +        print("CPE: Unzipping xml manifest...")
> +        nist_cpe_file = gzip.GzipFile(fileobj=open(cpedb, 'rb'))
> +        print("CPE: Converting xml manifest to dict...")
> +        tree = ET.parse(nist_cpe_file)
> +        all_cpedb = tree.getroot()
> +        self.parse_dict(all_cpedb)
> +
> +        print("CPE: Caching dictionary")
> +        cpes_file = open(cache_all_cpes, 'wb')
> +        pickle.dump(self.all_cpes, cpes_file)
> +        cpes_file.close()
> +        cpes_file = open(cache_all_cpes_no_version, 'wb')
> +        pickle.dump(self.all_cpes_no_version, cpes_file)
> +        cpes_file.close()
> +
> +    def get_xml_dict(self):
> +        print("CPE: Setting up NIST dictionary")
> +        if not os.path.exists(os.path.join(self.nvd_path, "cpe")):
> +            os.makedirs(os.path.join(self.nvd_path, "cpe"))
> +
> +        cpe_dict_local = os.path.join(self.nvd_path, "cpe", os.path.basename(CPEDB_URL))
> +        if not os.path.exists(cpe_dict_local) or os.stat(cpe_dict_local).st_mtime < time.time() - 86400:
> +            print("CPE: Fetching xml manifest from [" + CPEDB_URL + "]")
> +            cpe_dict = requests.get(CPEDB_URL)
> +            open(cpe_dict_local, "wb").write(cpe_dict.content)
> +
> +        cache_all_cpes = os.path.join(self.nvd_path, "cpe", "all_cpes.pkl")
> +        cache_all_cpes_no_version = os.path.join(self.nvd_path, "cpe", "all_cpes_no_version.pkl")
> +
> +        if not os.path.exists(cache_all_cpes) or \
> +           not os.path.exists(cache_all_cpes_no_version) or \
> +           os.stat(cache_all_cpes).st_mtime < os.stat(cpe_dict_local).st_mtime or \
> +           os.stat(cache_all_cpes_no_version).st_mtime < os.stat(cpe_dict_local).st_mtime:
> +            self.gen_cached_cpedb(cpe_dict_local,
> +                                  cache_all_cpes,
> +                                  cache_all_cpes_no_version)
> +
> +        print("CPE: Loading CACHED dictionary")
> +        cpe_file = open(cache_all_cpes, 'rb')
> +        self.all_cpes = pickle.load(cpe_file)
> +        cpe_file.close()
> +        cpe_file = open(cache_all_cpes_no_version, 'rb')
> +        self.all_cpes_no_version = pickle.load(cpe_file)
> +        cpe_file.close()
> +
> +    def parse_dict(self, all_cpedb):
> +        # Cycle through the dict and build two dict to be used for custom
> +        # lookups of partial and complete CPE objects
> +        # The objects are then used to create new proposed XML updates if
> +        # if is determined one is required
> +        # Out of the different language titles, select English
> +        for cpe in all_cpedb.findall(".//{http://cpe.mitre.org/dictionary/2.0}cpe-item"):
> +            cpe_titles = []
> +            for title in cpe.findall('.//{http://cpe.mitre.org/dictionary/2.0}title[@xml:lang="en-US"]', ns):
> +                title.tail = None
> +                cpe_titles.append(title)
> +
> +            # Some older CPE don't include references, if they do, make
> +            # sure we handle the case of one ref needing to be packed
> +            # in a list
> +            cpe_ref = cpe.find(".//{http://cpe.mitre.org/dictionary/2.0}references")
> +            if cpe_ref:
> +                for ref in cpe_ref.findall(".//{http://cpe.mitre.org/dictionary/2.0}reference"):
> +                    ref.tail = None
> +                    ref.text = ref.text.upper()
> +                    if ref.text not in VALID_REFS:
> +                        ref.text = ref.text + "-- UPDATE this entry, here are some examples and just one word should be used -- " + ' '.join(VALID_REFS) # noqa E501
> +                cpe_ref.tail = None
> +                cpe_ref.text = None
> +
> +            cpe_str = cpe.find(".//{http://scap.nist.gov/schema/cpe-extension/2.3}cpe23-item").get('name')
> +            item = CPE(cpe_str, cpe_titles, cpe_ref)
> +            cpe_str_no_version = CPE.no_version(cpe_str)
> +            # This dict must have a unique key for every CPE version
> +            # which allows matching to the specific obj data of that
> +            # NIST dict entry
> +            self.all_cpes.update({cpe_str: item})
> +            # This dict has one entry for every CPE (w/o version) to allow
> +            # partial match (no valid version) check (the obj is saved and
> +            # used as seed for suggested xml updates. By updating the same
> +            # non-version'd entry, it assumes the last update here is the
> +            # latest version in the NIST dict)
> +            self.all_cpes_no_version.update({cpe_str_no_version: item})
> +
> +    def find_partial(self, cpe_str):
> +        cpe_str_no_version = CPE.no_version(cpe_str)
> +        if cpe_str_no_version in self.all_cpes_no_version:
> +            return cpe_str_no_version
> +
> +    def find_partial_obj(self, cpe_str):
> +        cpe_str_no_version = CPE.no_version(cpe_str)
> +        if cpe_str_no_version in self.all_cpes_no_version:
> +            return self.all_cpes_no_version[cpe_str_no_version]
> +
> +    def find_partial_latest_version(self, cpe_str_partial):
> +        cpe_obj = self.find_partial_obj(cpe_str_partial)
> +        return cpe_obj.cpe_cur_ver
> +
> +    def find(self, cpe_str):
> +        if self.find_partial(cpe_str):
> +            if cpe_str in self.all_cpes:
> +                return cpe_str
> +
> +    def gen_update_xml(self, cpe_str):
> +        cpe = self.find_partial_obj(cpe_str)
> +        return cpe.update_xml_dict()
> -- 
> 2.29.2
> 

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