[PATCH v7 3/4] kernel-generate-cve-exclusions: Add a .bbclass

[ValentinBoudevin <valentin.boudevin@gmail.com>]

Add a new class named kernel-generate-cve-exclusions.bbclass to
generate-cve-exclusions to use this script at every run.

Two steps for testing:

1) inherit this class in the kernel recipe with "inherit
   kernel-generate-cve-exclusions.bbclass"
2) Use the following command to generate cve exclusions .json, and .inc
   file : "bitbake linux-yocto -c "do_generate_cve_exclusions"

This class contains several methods:

*do_generate_cve_exclusions: Use the script generate-cve-exclusions.py.
It uses the new "--output-json-file" argument to generate a JSON file as
an output stored in ${GENERATE_CVE_EXCLUSIONS_OUTPUT_JSON}, and a .inc
file in ${GENERATE_CVE_EXCLUSIONS_OUTPUT_INC}

*do_cve_check:prepend: Parse the previously generated JSON file to set
the variable CVE_STATUS corretly

The class also provides some variables:

*GENERATE_CVE_EXCLUSIONS_OUTPUT_JSON: path of the output JSON file used
to set CVE_STATUS
*GENERATE_CVE_EXCLUSIONS_OUTPUT_INC: cve exclusions .inc file output
path. Not used directly by this class (needs to be inherit manually).

Signed-off-by: Valentin Boudevin <valentin.boudevin@gmail.com>
---
 .../kernel-generate-cve-exclusions.bbclass    | 46 +++++++++++++++++++
 1 file changed, 46 insertions(+)
 create mode 100644 meta/classes/kernel-generate-cve-exclusions.bbclass

diff --git a/meta/classes/kernel-generate-cve-exclusions.bbclass b/meta/classes/kernel-generate-cve-exclusions.bbclass
new file mode 100644
index 0000000000..8efa32f6a1
--- /dev/null
+++ b/meta/classes/kernel-generate-cve-exclusions.bbclass
@@ -0,0 +1,46 @@
+# Generate CVE exclusions for the kernel build (set to "1" to enable)
+GENERATE_CVE_EXCLUSIONS_OUTPUT_JSON = "${WORKDIR}/temp/cve-exclusion_${LINUX_VERSION}.json"
+GENERATE_CVE_EXCLUSIONS_OUTPUT_INC  = "${WORKDIR}/temp//cve-exclusion_${LINUX_VERSION}.inc"
+
+do_generate_cve_exclusions() {
+    # Check for required files and directories
+    generate_cve_exclusions_script=${COREBASE}/scripts/contrib/generate-cve-exclusions.py
+    if [ ! -f "${generate_cve_exclusions_script}" ]; then
+        bbwarn "generate-cve-exclusions.py not found in ${generate_cve_exclusions_script}."
+        return 0
+    fi
+    if [ ! -d "${STAGING_DATADIR_NATIVE}/cvelistv5-native" ]; then
+        bbwarn "CVE exclusions source directory not found in ${STAGING_DATADIR_NATIVE}/cvelistv5-native."
+        return 0
+    fi
+    # Generate the CVE exclusions JSON & INC file
+    python3 "${generate_cve_exclusions_script}" \
+        "${STAGING_DATADIR_NATIVE}/cvelistv5-native" \
+        ${LINUX_VERSION} \
+        --output-json-file "${GENERATE_CVE_EXCLUSIONS_OUTPUT_JSON}" \
+        --output-inc-file "${GENERATE_CVE_EXCLUSIONS_OUTPUT_INC}"
+    bbplain "CVE exclusions generated for kernel version ${LINUX_VERSION} at ${GENERATE_CVE_EXCLUSIONS_OUTPUT_INC} and ${GENERATE_CVE_EXCLUSIONS_OUTPUT_JSON}."
+}
+do_generate_cve_exclusions[depends] += "cvelistv5-native:do_populate_sysroot"
+do_generate_cve_exclusions[nostamp] = "1"
+do_generate_cve_exclusions[doc] = "Generate CVE exclusions for the kernel build. (e.g., cve-exclusion_6.12.json)"
+addtask generate_cve_exclusions after do_prepare_recipe_sysroot before do_cve_check
+
+python do_cve_check:prepend() {
+    import os
+    import json
+    workdir = d.getVar("${STAGING_DATADIR_NATIVE}/cvelistv5-native")
+    kernel_version = d.getVar("LINUX_VERSION")
+    json_input_file = d.getVar("GENERATE_CVE_EXCLUSIONS_OUTPUT_JSON")
+    if os.path.exists(json_input_file):
+        with open(json_input_file, 'r', encoding='utf-8') as f:
+            cve_data = json.load(f)
+        cve_status_dict = cve_data.get("cve_status", {})
+        count = 0
+        for cve_id, info in cve_status_dict.items():
+            if info.get("active", True):
+                continue
+            d.setVarFlag("CVE_STATUS", cve_id, info.get("message", ""))
+            count += 1
+        bb.note("Loaded %d CVE_STATUS entries from JSON output for kernel %s" % (count, kernel_version))
+}