[PATCHv4 2/2] cve-check.bbclass: Add class

[mariano.lopez@linux.intel.com]

From: Mariano Lopez <mariano.lopez@linux.intel.com>

This class adds a new task for all the recipes to use
cve-check-tool in order to look for public CVEs affecting
the packages generated.

It is possible to use this class when building an image,
building a recipe, or using the "world" or "universe" cases.

In order to use this class it must be inherited and it will
add the task automatically to every recipe.

[YOCTO #7515]

Co-authored by Ross Burton & Mariano Lopez

Signed-off-by: Mariano Lopez <mariano.lopez@linux.intel.com>
---
 meta/classes/cve-check.bbclass | 267 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 267 insertions(+)
 create mode 100644 meta/classes/cve-check.bbclass

diff --git a/meta/classes/cve-check.bbclass b/meta/classes/cve-check.bbclass
new file mode 100644
index 0000000..8251ca7
--- /dev/null
+++ b/meta/classes/cve-check.bbclass
@@ -0,0 +1,267 @@
+# 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.
+
+CVE_CHECK_DB_DIR ?= "${DL_DIR}/CVE_CHECK"
+CVE_CHECK_DB_FILE ?= "${CVE_CHECK_DB_DIR}/nvd.db"
+
+CVE_CHECK_LOCAL_DIR ?= "${WORKDIR}/cve"
+CVE_CHECK_LOCAL_FILE ?= "${CVE_CHECK_LOCAL_DIR}/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 = "\
+    glibc-locale \
+"
+
+# Whitelist for CVE and version of package
+CVE_CHECK_CVE_WHITELIST = "{\
+    'CVE-2014-2524': ('6.3',), \
+}"
+
+python do_cve_check () {
+    """
+    Check recipe for patched and unpatched CVEs
+    """
+
+    if os.path.exists(d.getVar("CVE_CHECK_TMP_FILE", True)):
+        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("Failed to update CVE database, skipping CVE check")
+}
+
+addtask cve_check after do_unpack before do_build
+do_cve_check[depends] = "cve-check-tool-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", True))
+}
+
+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 os.path.exists(d.getVar("CVE_CHECK_TMP_FILE", True)):
+        bb.note("Writing rootfs CVE manifest")
+        deploy_dir = d.getVar("DEPLOY_DIR_IMAGE", True)
+        link_name = d.getVar("IMAGE_LINK_NAME", True)
+        manifest_name = d.getVar("CVE_CHECK_MANIFEST", True)
+        cve_tmp_file = d.getVar("CVE_CHECK_TMP_FILE", True)
+
+        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)):
+                if d.getVar('RM_OLD_IMAGE', True) == "1":
+                    os.remove(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', True) == '1' else ''}"
+
+def get_patches_cves(d):
+    """
+    Get patches that solve CVEs using the "CVE: " tag.
+    """
+
+    import re
+
+    pn = d.getVar("PN", True)
+    cve_match = re.compile("CVE:( CVE\-\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]
+        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 the "CVE: " line
+        match = cve_match.search(patch_text)
+        if match:
+            # 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)
+        else:
+            bb.debug(2, "Patch %s doesn't solve CVEs" % patch_file)
+
+    return patched_cves
+
+def check_cves(d, patched_cves):
+    """
+    Run cve-check-tool looking for patched and unpatched CVEs.
+    """
+
+    import ast, csv, tempfile, subprocess, io
+
+    cves_patched = []
+    cves_unpatched = []
+    bpn = d.getVar("BPN", True)
+    pv = d.getVar("PV", True).split("git+")[0]
+    cves = " ".join(patched_cves)
+    cve_db_dir = d.getVar("CVE_CHECK_DB_DIR", True)
+    cve_whitelist = ast.literal_eval(d.getVar("CVE_CHECK_CVE_WHITELIST", True))
+    cve_cmd = "cve-check-tool"
+    cmd = [cve_cmd, "--no-html", "--csv", "--not-affected", "-t", "faux", "-d", cve_db_dir]
+
+    # If the recipe has been whitlisted we return empty lists
+    if d.getVar("PN", True) in d.getVar("CVE_CHECK_PN_WHITELIST", True).split():
+        bb.note("Recipe has been whitelisted, skipping check")
+        return ([], [])
+
+    # It is needed to export the proxies to download the database using HTTP
+    bb.utils.export_proxies(d)
+
+    try:
+        # Write the faux CSV file to be used with cve-check-tool
+        fd, faux = tempfile.mkstemp(prefix="cve-faux-")
+        with os.fdopen(fd, "w") as f:
+            f.write("%s,%s,%s," % (bpn, pv, cves))
+        cmd.append(faux)
+
+        output = subprocess.check_output(cmd, stderr=subprocess.STDOUT).decode("utf-8")
+        bb.debug(2, "Output of command %s:\n%s" % ("\n".join(cmd), output))
+    except subprocess.CalledProcessError as e:
+        bb.warn("Couldn't check for CVEs: %s (output %s)" % (e, e.output))
+    finally:
+        os.remove(faux)
+
+    for row in csv.reader(io.StringIO(output)):
+        # Third row has the unpatched CVEs
+        if row[2]:
+            for cve in row[2].split():
+                # Skip if the CVE has been whitlisted for the current version
+                if pv in cve_whitelist.get(cve,[]):
+                    bb.note("%s-%s has been whitelisted for %s" % (bpn, pv, cve))
+                else:
+                    cves_unpatched.append(cve)
+                    bb.debug(2, "%s-%s is not patched for %s" % (bpn, pv, cve))
+        # Fourth row has patched CVEs
+        if row[3]:
+            for cve in row[3].split():
+                cves_patched.append(cve)
+                bb.debug(2, "%s-%s is patched for %s" % (bpn, pv, cve))
+
+    return (cves_patched, cves_unpatched)
+
+def get_cve_info(d, cves):
+    """
+    Get CVE information from the database used by cve-check-tool.
+
+    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", True)
+    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]]["score"] = row[2]
+        cve_data[row[0]]["modified"] = row[3]
+        cve_data[row[0]]["vector"] = row[4]
+    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_LOCAL_FILE", True)
+    nvd_link = "https://web.nvd.nist.gov/view/vuln/detail?vulnId="
+    write_string = ""
+    first_alert = True
+    bb.utils.mkdirhier(d.getVar("CVE_CHECK_LOCAL_DIR", True))
+
+    for cve in sorted(cve_data):
+        write_string += "PACKAGE NAME: %s\n" % d.getVar("PN", True)
+        write_string += "PACKAGE VERSION: %s\n" % d.getVar("PV", True)
+        write_string += "CVE: %s\n" % cve
+        if cve in patched:
+            write_string += "CVE STATUS: Patched\n"
+        else:
+            write_string += "CVE STATUS: Unpatched\n"
+            if first_alert:
+                bb.warn("Found unpatched CVE, for more information check %s" % cve_file)
+                first_alert = False
+        write_string += "CVE SUMMARY: %s\n" % cve_data[cve]["summary"]
+        write_string += "CVSS v2 BASE SCORE: %s\n" % cve_data[cve]["score"]
+        write_string += "VECTOR: %s\n" % cve_data[cve]["vector"]
+        write_string += "MORE INFORMATION: %s%s\n\n" % (nvd_link, cve)
+
+    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", True) == "1":
+        cve_dir = d.getVar("CVE_CHECK_DIR", True)
+        bb.utils.mkdirhier(cve_dir)
+        deploy_file = os.path.join(cve_dir, d.getVar("PN", True))
+        with open(deploy_file, "w") as f:
+            f.write(write_string)
+
+    if d.getVar("CVE_CHECK_CREATE_MANIFEST", True) == "1":
+        with open(d.getVar("CVE_CHECK_TMP_FILE", True), "a") as f:
+            f.write("%s" % write_string)
-- 
2.6.6