# This class is used to check recipes against public CVEs. # # In order to use this class just inherit the class in the # local.conf file and it will add the cve_check task for # every recipe. The task can be used per recipe, per image, # or using the special cases "world" and "universe". The # cve_check task will print a warning for every unpatched # CVE found and generate a file in the recipe WORKDIR/cve # directory. If an image is build it will generate a report # in DEPLOY_DIR_IMAGE for all the packages used. # # Example: # bitbake -c cve_check openssl # bitbake core-image-sato # bitbake -k -c cve_check universe # # DISCLAIMER # # This class/tool is meant to be used as support and not # the only method to check against CVEs. Running this tool # doesn't guarantee your packages are free of CVEs. # The product name that the CVE database uses. Defaults to BPN, but may need to # be overriden per recipe (for example tiff.bb sets CVE_PRODUCT=libtiff). CVE_PRODUCT ??= "${BPN}" CVE_VERSION ??= "${PV}" CVE_CHECK_DB_DIR ?= "${DL_DIR}/CVE_CHECK" CVE_CHECK_DB_FILE ?= "${CVE_CHECK_DB_DIR}/nvdcve_1.0.db" CVE_CHECK_LOG ?= "${T}/cve.log" CVE_CHECK_TMP_FILE ?= "${TMPDIR}/cve_check" CVE_CHECK_DIR ??= "${DEPLOY_DIR}/cve" CVE_CHECK_MANIFEST ?= "${DEPLOY_DIR_IMAGE}/${IMAGE_NAME}${IMAGE_NAME_SUFFIX}.cve" CVE_CHECK_COPY_FILES ??= "1" CVE_CHECK_CREATE_MANIFEST ??= "1" # Whitelist for packages (PN) CVE_CHECK_PN_WHITELIST ?= "" # Whitelist for CVE. If a CVE is found, then it is considered patched. # The value is a string containing space separated CVE values: # # CVE_CHECK_WHITELIST = 'CVE-2014-2524 CVE-2018-1234' # CVE_CHECK_WHITELIST ?= "" python do_cve_check () { """ Check recipe for patched and unpatched CVEs """ if os.path.exists(d.getVar("CVE_CHECK_DB_FILE")): patched_cves = get_patches_cves(d) patched, unpatched = check_cves(d, patched_cves) if patched or unpatched: cve_data = get_cve_info(d, patched + unpatched) cve_write_data(d, patched, unpatched, cve_data) else: bb.note("No CVE database found, skipping CVE check") } addtask cve_check after do_unpack before do_build do_cve_check[depends] = "cve-update-db-native:do_populate_cve_db" do_cve_check[nostamp] = "1" python cve_check_cleanup () { """ Delete the file used to gather all the CVE information. """ bb.utils.remove(e.data.getVar("CVE_CHECK_TMP_FILE")) } addhandler cve_check_cleanup cve_check_cleanup[eventmask] = "bb.cooker.CookerExit" python cve_check_write_rootfs_manifest () { """ Create CVE manifest when building an image """ import shutil if d.getVar("CVE_CHECK_COPY_FILES") == "1": deploy_file = os.path.join(d.getVar("CVE_CHECK_DIR"), d.getVar("PN")) if os.path.exists(deploy_file): bb.utils.remove(deploy_file) if os.path.exists(d.getVar("CVE_CHECK_TMP_FILE")): bb.note("Writing rootfs CVE manifest") deploy_dir = d.getVar("DEPLOY_DIR_IMAGE") link_name = d.getVar("IMAGE_LINK_NAME") manifest_name = d.getVar("CVE_CHECK_MANIFEST") cve_tmp_file = d.getVar("CVE_CHECK_TMP_FILE") shutil.copyfile(cve_tmp_file, manifest_name) if manifest_name and os.path.exists(manifest_name): manifest_link = os.path.join(deploy_dir, "%s.cve" % link_name) # If we already have another manifest, update symlinks if os.path.exists(os.path.realpath(manifest_link)): os.remove(manifest_link) os.symlink(os.path.basename(manifest_name), manifest_link) bb.plain("Image CVE report stored in: %s" % manifest_name) } ROOTFS_POSTPROCESS_COMMAND_prepend = "${@'cve_check_write_rootfs_manifest; ' if d.getVar('CVE_CHECK_CREATE_MANIFEST') == '1' else ''}" do_rootfs[recrdeptask] += "${@'do_cve_check' if d.getVar('CVE_CHECK_CREATE_MANIFEST') == '1' else ''}" def get_patches_cves(d): """ Get patches that solve CVEs using the "CVE: " tag. """ import re pn = d.getVar("PN") cve_match = re.compile("CVE:( CVE\-\d{4}\-\d+)+") # Matches last CVE-1234-211432 in the file name, also if written # with small letters. Not supporting multiple CVE id's in a single # file name. cve_file_name_match = re.compile(".*([Cc][Vv][Ee]\-\d{4}\-\d+)") patched_cves = set() bb.debug(2, "Looking for patches that solves CVEs for %s" % pn) for url in src_patches(d): patch_file = bb.fetch.decodeurl(url)[2] # Check patch file name for CVE ID fname_match = cve_file_name_match.search(patch_file) if fname_match: cve = fname_match.group(1).upper() patched_cves.add(cve) bb.debug(2, "Found CVE %s from patch file name %s" % (cve, patch_file)) with open(patch_file, "r", encoding="utf-8") as f: try: patch_text = f.read() except UnicodeDecodeError: bb.debug(1, "Failed to read patch %s using UTF-8 encoding" " trying with iso8859-1" % patch_file) f.close() with open(patch_file, "r", encoding="iso8859-1") as f: patch_text = f.read() # Search for one or more "CVE: " lines text_match = False for match in cve_match.finditer(patch_text): # Get only the CVEs without the "CVE: " tag cves = patch_text[match.start()+5:match.end()] for cve in cves.split(): bb.debug(2, "Patch %s solves %s" % (patch_file, cve)) patched_cves.add(cve) text_match = True if not fname_match and not text_match: bb.debug(2, "Patch %s doesn't solve CVEs" % patch_file) return patched_cves def check_cves(d, patched_cves): """ Connect to the NVD database and find unpatched cves. """ import ast, csv, tempfile, subprocess, io from distutils.version import LooseVersion cves_unpatched = [] # CVE_PRODUCT can contain more than one product (eg. curl/libcurl) products = d.getVar("CVE_PRODUCT").split() # If this has been unset then we're not scanning for CVEs here (for example, image recipes) if not products: return ([], []) pv = d.getVar("CVE_VERSION").split("+git")[0] # If the recipe has been whitlisted we return empty lists if d.getVar("PN") in d.getVar("CVE_CHECK_PN_WHITELIST").split(): bb.note("Recipe has been whitelisted, skipping check") return ([], []) old_cve_whitelist = d.getVar("CVE_CHECK_CVE_WHITELIST") if old_cve_whitelist: bb.warn("CVE_CHECK_CVE_WHITELIST is deprecated, please use CVE_CHECK_WHITELIST.") cve_whitelist = d.getVar("CVE_CHECK_WHITELIST").split() import sqlite3 db_file = d.getVar("CVE_CHECK_DB_FILE") conn = sqlite3.connect(db_file) for product in products: c = conn.cursor() if ":" in product: vendor, product = product.split(":", 1) c.execute("SELECT * FROM PRODUCTS WHERE PRODUCT IS ? AND VENDOR IS ?", (product, vendor)) else: c.execute("SELECT * FROM PRODUCTS WHERE PRODUCT IS ?", (product,)) for row in c: cve = row[0] version_start = row[3] operator_start = row[4] version_end = row[5] operator_end = row[6] if cve in cve_whitelist: bb.note("%s-%s has been whitelisted for %s" % (product, pv, cve)) # TODO: this should be in the report as 'whitelisted' patched_cves.add(cve) elif cve in patched_cves: bb.note("%s has been patched" % (cve)) else: to_append = False if (operator_start == '=' and pv == version_start): to_append = True else: if operator_start: try: to_append_start = (operator_start == '>=' and LooseVersion(pv) >= LooseVersion(version_start)) to_append_start |= (operator_start == '>' and LooseVersion(pv) > LooseVersion(version_start)) except: bb.note("%s: Failed to compare %s %s %s for %s" % (product, pv, operator_start, version_start, cve)) to_append_start = False else: to_append_start = False if operator_end: try: to_append_end = (operator_end == '<=' and LooseVersion(pv) <= LooseVersion(version_end)) to_append_end |= (operator_end == '<' and LooseVersion(pv) < LooseVersion(version_end)) except: bb.note("%s: Failed to compare %s %s %s for %s" % (product, pv, operator_end, version_end, cve)) to_append_end = False else: to_append_end = False if operator_start and operator_end: to_append = to_append_start and to_append_end else: to_append = to_append_start or to_append_end if to_append: bb.note("%s-%s is vulnerable to %s" % (product, pv, cve)) cves_unpatched.append(cve) else: bb.note("%s-%s is not vulnerable to %s" % (product, pv, cve)) patched_cves.add(cve) conn.close() return (list(patched_cves), cves_unpatched) def get_cve_info(d, cves): """ Get CVE information from the database. Unfortunately the only way to get CVE info is set the output to html (hard to parse) or query directly the database. """ try: import sqlite3 except ImportError: from pysqlite2 import dbapi2 as sqlite3 cve_data = {} db_file = d.getVar("CVE_CHECK_DB_FILE") placeholder = ",".join("?" * len(cves)) query = "SELECT * FROM NVD WHERE id IN (%s)" % placeholder conn = sqlite3.connect(db_file) cur = conn.cursor() for row in cur.execute(query, tuple(cves)): cve_data[row[0]] = {} cve_data[row[0]]["summary"] = row[1] cve_data[row[0]]["scorev2"] = row[2] cve_data[row[0]]["scorev3"] = row[3] cve_data[row[0]]["modified"] = row[4] cve_data[row[0]]["vector"] = row[5] conn.close() return cve_data def cve_write_data(d, patched, unpatched, cve_data): """ Write CVE information in WORKDIR; and to CVE_CHECK_DIR, and CVE manifest if enabled. """ cve_file = d.getVar("CVE_CHECK_LOG") nvd_link = "https://web.nvd.nist.gov/view/vuln/detail?vulnId=" write_string = "" unpatched_cves = [] bb.utils.mkdirhier(os.path.dirname(cve_file)) for cve in sorted(cve_data): write_string += "PACKAGE NAME: %s\n" % d.getVar("PN") write_string += "PACKAGE VERSION: %s\n" % d.getVar("PV") write_string += "CVE: %s\n" % cve if cve in patched: write_string += "CVE STATUS: Patched\n" else: unpatched_cves.append(cve) write_string += "CVE STATUS: Unpatched\n" write_string += "CVE SUMMARY: %s\n" % cve_data[cve]["summary"] write_string += "CVSS v2 BASE SCORE: %s\n" % cve_data[cve]["scorev2"] write_string += "CVSS v3 BASE SCORE: %s\n" % cve_data[cve]["scorev3"] write_string += "VECTOR: %s\n" % cve_data[cve]["vector"] write_string += "MORE INFORMATION: %s%s\n\n" % (nvd_link, cve) if unpatched_cves: bb.warn("Found unpatched CVE (%s), for more information check %s" % (" ".join(unpatched_cves),cve_file)) with open(cve_file, "w") as f: bb.note("Writing file %s with CVE information" % cve_file) f.write(write_string) if d.getVar("CVE_CHECK_COPY_FILES") == "1": cve_dir = d.getVar("CVE_CHECK_DIR") bb.utils.mkdirhier(cve_dir) deploy_file = os.path.join(cve_dir, d.getVar("PN")) with open(deploy_file, "w") as f: f.write(write_string) if d.getVar("CVE_CHECK_CREATE_MANIFEST") == "1": with open(d.getVar("CVE_CHECK_TMP_FILE"), "a") as f: f.write("%s" % write_string)