diff mbox series

[2/3] vex.bbclass: add a new class

Message ID 20240715102003.10122-2-marta.rybczynska@syslinbit.com
State New
Headers show
Series [1/3] cve-check: enrich annotation of CVEs | expand

Commit Message

Marta Rybczynska July 15, 2024, 10:20 a.m. UTC
The "vex" class generates the minimum information that is necessary
for VEX generation by an external CVE checking tool. It is a drop-in
replacement of "cve-check". It uses the same variables from recipes
to make the migration and backporting easier.

The goal if this class is to allow generation of the CVE list of
an image or distribution on-demand, including the latest information
from vulnerability databases. Vulnerability data changes every day,
so a status generated at build becomes out-of-date very soon.

Research done for this work shows that the current VEX formats (CSAF
and OpenVEX) do not provide enough information to generate such
rolling information. Instead, we extract the needed data from recipe
annotations (package names, CPEs, versions, CVE patches applied...)
and store for later use in the format that is an extension of the
CVE-check JSON output format.

This output can be then used (separately or with SPDX of the same
build) by an external tool to generate the vulnerability annotation
and VEX statements in standard formats.

Signed-off-by: Marta Rybczynska <marta.rybczynska@syslinbit.com>
Signed-off-by: Samantha Jalabert <samantha.jalabert@syslinbit.com>
---
 meta/classes/vex.bbclass | 316 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 316 insertions(+)
 create mode 100644 meta/classes/vex.bbclass
diff mbox series

Patch

diff --git a/meta/classes/vex.bbclass b/meta/classes/vex.bbclass
new file mode 100644
index 0000000000..94842d4c7f
--- /dev/null
+++ b/meta/classes/vex.bbclass
@@ -0,0 +1,316 @@ 
+#
+# Copyright OpenEmbedded Contributors
+#
+# SPDX-License-Identifier: MIT
+#
+
+# 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_SUMMARY_DIR ?= "${LOG_DIR}/cve"
+
+CVE_CHECK_SUMMARY_FILE_NAME_JSON = "cve-summary.json"
+CVE_CHECK_SUMMARY_INDEX_PATH = "${CVE_CHECK_SUMMARY_DIR}/cve-summary-index.txt"
+
+CVE_CHECK_DIR ??= "${DEPLOY_DIR}/cve"
+CVE_CHECK_RECIPE_FILE_JSON ?= "${CVE_CHECK_DIR}/${PN}_cve.json"
+CVE_CHECK_MANIFEST_JSON ?= "${IMGDEPLOYDIR}/${IMAGE_NAME}.json"
+
+# Report Patched or Ignored CVEs
+CVE_CHECK_REPORT_PATCHED ??= "1"
+
+CVE_CHECK_SHOW_WARNINGS ??= "1"
+
+# Skip CVE Check for packages (PN)
+CVE_CHECK_SKIP_RECIPE ?= ""
+
+# Replace NVD DB check status for a given CVE. Each of CVE has to be mentioned
+# separately with optional detail and description for this status.
+#
+# CVE_STATUS[CVE-1234-0001] = "not-applicable-platform: Issue only applies on Windows"
+# CVE_STATUS[CVE-1234-0002] = "fixed-version: Fixed externally"
+#
+# Settings the same status and reason for multiple CVEs is possible
+# via CVE_STATUS_GROUPS variable.
+#
+# CVE_STATUS_GROUPS = "CVE_STATUS_WIN CVE_STATUS_PATCHED"
+#
+# CVE_STATUS_WIN = "CVE-1234-0001 CVE-1234-0003"
+# CVE_STATUS_WIN[status] = "not-applicable-platform: Issue only applies on Windows"
+# CVE_STATUS_PATCHED = "CVE-1234-0002 CVE-1234-0004"
+# CVE_STATUS_PATCHED[status] = "fixed-version: Fixed externally"
+#
+# All possible CVE statuses could be found in cve-check-map.conf
+# CVE_CHECK_STATUSMAP[not-applicable-platform] = "Ignored"
+# CVE_CHECK_STATUSMAP[fixed-version] = "Patched"
+#
+# CVE_CHECK_IGNORE is deprecated and CVE_STATUS has to be used instead.
+# Keep CVE_CHECK_IGNORE until other layers migrate to new variables
+CVE_CHECK_IGNORE ?= ""
+
+# Layers to be excluded
+CVE_CHECK_LAYER_EXCLUDELIST ??= ""
+
+# Layers to be included
+CVE_CHECK_LAYER_INCLUDELIST ??= ""
+
+
+# set to "alphabetical" for version using single alphabetical character as increment release
+CVE_VERSION_SUFFIX ??= ""
+
+python () {
+    # Fallback all CVEs from CVE_CHECK_IGNORE to CVE_STATUS
+    cve_check_ignore = d.getVar("CVE_CHECK_IGNORE")
+    if cve_check_ignore:
+        bb.warn("CVE_CHECK_IGNORE is deprecated in favor of CVE_STATUS")
+        for cve in (d.getVar("CVE_CHECK_IGNORE") or "").split():
+            d.setVarFlag("CVE_STATUS", cve, "ignored")
+
+    # Process CVE_STATUS_GROUPS to set multiple statuses and optional detail or description at once
+    for cve_status_group in (d.getVar("CVE_STATUS_GROUPS") or "").split():
+        cve_group = d.getVar(cve_status_group)
+        if cve_group is not None:
+            for cve in cve_group.split():
+                d.setVarFlag("CVE_STATUS", cve, d.getVarFlag(cve_status_group, "status"))
+        else:
+            bb.warn("CVE_STATUS_GROUPS contains undefined variable %s" % cve_status_group)
+}
+
+def generate_json_report(d, out_path, link_path):
+    if os.path.exists(d.getVar("CVE_CHECK_SUMMARY_INDEX_PATH")):
+        import json
+        from oe.cve_check import cve_check_merge_jsons, update_symlinks
+
+        bb.note("Generating JSON CVE summary")
+        index_file = d.getVar("CVE_CHECK_SUMMARY_INDEX_PATH")
+        summary = {"version":"1", "package": []}
+        with open(index_file) as f:
+            filename = f.readline()
+            while filename:
+                with open(filename.rstrip()) as j:
+                    data = json.load(j)
+                    cve_check_merge_jsons(summary, data)
+                filename = f.readline()
+
+        summary["package"].sort(key=lambda d: d['name'])
+
+        with open(out_path, "w") as f:
+            json.dump(summary, f, indent=2)
+
+        update_symlinks(out_path, link_path)
+
+python vex_save_summary_handler () {
+    import shutil
+    import datetime
+    from oe.cve_check import update_symlinks
+
+    cvelogpath = d.getVar("CVE_CHECK_SUMMARY_DIR")
+
+    bb.utils.mkdirhier(cvelogpath)
+    timestamp = datetime.datetime.now().strftime('%Y%m%d%H%M%S')
+
+    json_summary_link_name = os.path.join(cvelogpath, d.getVar("CVE_CHECK_SUMMARY_FILE_NAME_JSON"))
+    json_summary_name = os.path.join(cvelogpath, "cve-summary-%s.json" % (timestamp))
+    generate_json_report(d, json_summary_name, json_summary_link_name)
+    bb.plain("Complete CVE JSON report summary created at: %s" % json_summary_link_name)
+}
+
+addhandler vex_save_summary_handler
+vex_save_summary_handler[eventmask] = "bb.event.BuildCompleted"
+
+python do_generate_vex () {
+    """
+    Check recipe for patched and unpatched CVEs
+    """
+    from oe.cve_check import get_patched_cves
+
+    try:
+        patched_cves = get_patched_cves(d)
+        cves_status = []
+        products = d.getVar("CVE_PRODUCT").split()
+        for product in products:
+            if ":" in product:
+                _, product = product.split(":", 1)
+            cves_status.append([product, False])
+
+    except FileNotFoundError:
+        bb.fatal("Failure in searching patches")
+
+    cve_write_data_json(d, patched_cves, cves_status)
+}
+
+addtask generate_vex before do_build
+
+python vex_cleanup () {
+    """
+    Delete the file used to gather all the CVE information.
+    """
+    bb.utils.remove(e.data.getVar("CVE_CHECK_SUMMARY_INDEX_PATH"))
+}
+
+addhandler vex_cleanup
+vex_cleanup[eventmask] = "bb.event.BuildCompleted"
+
+python vex_write_rootfs_manifest () {
+    """
+    Create CVE manifest when building an image
+    """
+
+    import json
+    from oe.rootfs import image_list_installed_packages
+    from oe.cve_check import cve_check_merge_jsons, update_symlinks
+
+    deploy_file_json = d.getVar("CVE_CHECK_RECIPE_FILE_JSON")
+    if os.path.exists(deploy_file_json):
+        bb.utils.remove(deploy_file_json)
+
+    # Create a list of relevant recipies
+    recipies = set()
+    for pkg in list(image_list_installed_packages(d)):
+        pkg_info = os.path.join(d.getVar('PKGDATA_DIR'),
+                                'runtime-reverse', pkg)
+        pkg_data = oe.packagedata.read_pkgdatafile(pkg_info)
+        recipies.add(pkg_data["PN"])
+
+    bb.note("Writing rootfs CVE manifest")
+    deploy_dir = d.getVar("IMGDEPLOYDIR")
+    link_name = d.getVar("IMAGE_LINK_NAME")
+
+    json_data = {"version":"1", "package": []}
+    text_data = ""
+
+    save_pn = d.getVar("PN")
+
+    for pkg in recipies:
+        # To be able to use the CVE_CHECK_RECIPE_FILE_JSON variable we have to evaluate
+        # it with the different PN names set each time.
+        d.setVar("PN", pkg)
+
+        pkgfilepath = d.getVar("CVE_CHECK_RECIPE_FILE_JSON")
+        if os.path.exists(pkgfilepath):
+            with open(pkgfilepath) as j:
+                data = json.load(j)
+                cve_check_merge_jsons(json_data, data)
+
+    d.setVar("PN", save_pn)
+
+    link_path = os.path.join(deploy_dir, "%s.json" % link_name)
+    manifest_name = d.getVar("CVE_CHECK_MANIFEST_JSON")
+
+    with open(manifest_name, "w") as f:
+        json.dump(json_data, f, indent=2)
+
+    update_symlinks(manifest_name, link_path)
+    bb.plain("Image CVE JSON report stored in: %s" % manifest_name)
+}
+
+ROOTFS_POSTPROCESS_COMMAND:prepend = "vex_write_rootfs_manifest; "
+do_rootfs[recrdeptask] += "do_generate_vex "
+do_populate_sdk[recrdeptask] += "do_generate_vex "
+
+def cve_write_data_json(d, cve_data, cve_status):
+    """
+    Prepare CVE data for the JSON format, then write it.
+    Done for each recipe.
+    """
+
+    from oe.cve_check import get_cpe_ids
+    import json
+
+    output = {"version":"1", "package": []}
+    nvd_link = "https://nvd.nist.gov/vuln/detail/"
+
+    fdir_name  = d.getVar("FILE_DIRNAME")
+    layer = fdir_name.split("/")[-3]
+
+    include_layers = d.getVar("CVE_CHECK_LAYER_INCLUDELIST").split()
+    exclude_layers = d.getVar("CVE_CHECK_LAYER_EXCLUDELIST").split()
+
+    if exclude_layers and layer in exclude_layers:
+        return
+
+    if include_layers and layer not in include_layers:
+        return
+
+    product_data = []
+    for s in cve_status:
+        p = {"product": s[0], "cvesInRecord": "Yes"}
+        if s[1] == False:
+            p["cvesInRecord"] = "No"
+        product_data.append(p)
+    product_data = list({p['product']:p for p in product_data}.values())
+
+    package_version = "%s%s" % (d.getVar("EXTENDPE"), d.getVar("PV"))
+    cpes = get_cpe_ids(d.getVar("CVE_PRODUCT"), d.getVar("CVE_VERSION"))
+    package_data = {
+        "name" : d.getVar("PN"),
+        "layer" : layer,
+        "version" : package_version,
+        "products": product_data,
+        "cpes": cpes
+    }
+
+    cve_list = []
+
+    for cve in sorted(cve_data):
+        issue_link = "%s%s" % (nvd_link, cve)
+
+        cve_item = {
+            "id" : cve,
+            "status" : cve_data[cve]["abbrev-status"],
+            "link": issue_link,
+        }
+        if 'NVD-summary' in cve_data[cve]:
+            cve_item["summary"] = cve_data[cve]["NVD-summary"]
+            cve_item["scorev2"] = cve_data[cve]["NVD-scorev2"]
+            cve_item["scorev3"] = cve_data[cve]["NVD-scorev3"]
+            cve_item["vector"] = cve_data[cve]["NVD-vector"]
+            cve_item["vectorString"] = cve_data[cve]["NVD-vectorString"]
+        if 'status' in cve_data[cve]:
+            cve_item["detail"] = cve_data[cve]["status"]
+        if 'justification' in cve_data[cve]:
+            cve_item["description"] = cve_data[cve]["justification"]
+        if 'resource' in cve_data[cve]:
+            cve_item["patch-file"] = cve_data[cve]["resource"]
+        cve_list.append(cve_item)
+
+    package_data["issue"] = cve_list
+    output["package"].append(package_data)
+
+    deploy_file = d.getVar("CVE_CHECK_RECIPE_FILE_JSON")
+
+    write_string = json.dumps(output, indent=2)
+
+    cvelogpath = d.getVar("CVE_CHECK_SUMMARY_DIR")
+    index_path = d.getVar("CVE_CHECK_SUMMARY_INDEX_PATH")
+    bb.utils.mkdirhier(cvelogpath)
+    fragment_file = os.path.basename(deploy_file)
+    fragment_path = os.path.join(cvelogpath, fragment_file)
+    with open(fragment_path, "w") as f:
+        f.write(write_string)
+    with open(index_path, "a+") as f:
+        f.write("%s\n" % fragment_path)