Exclude dependencies from wolfTrust Coverity scans

.github/workflows/README.md

@@ -4,11 +4,17 @@ CI has a fast per-PR host lane, the tiered M33MU emulator matrix, and static
 analysis. M33MU runs a per-port smoke set on every pull request and the full
 matrix on labels, main pushes, and nightly.
 
-`codeql.yml` runs C security queries on pull requests, pushes to `main` and
-release branches, and weekly. `coverity.yml` scans on pushes to `main`, daily,
-or on manual dispatch from `wolfSSL/wolfTrust` only. Both trace host suite
-builds and secure-image builds for STM32H563 and MIMXRT700 with both crypto
-engines via `tools/ci-static-analysis-build.sh`.
+`codeql.yml` runs C security queries. `coverity.yml` runs on Sundays at
+00:00 UTC or by manual dispatch. Both build the host suites and secure images
+for STM32H563 and MIMXRT700 with both crypto engines.
+
+Coverity scans wolfTrust runtime, ports, tests, and generated policy code.
+`tools/ci-coverity-filter.py` removes dependency source units before upload
+and rejects an invalid capture. Keep submodules under `lib/` and enable
+**Ignore component in analysis** for the `Third party dependencies` component
+(`.*/lib/.*`) in Coverity Scan to exclude dependency headers too.
+
+An accepted upload queues analysis; results appear after Coverity processes it.
 
 ## At a glance
 

.github/workflows/coverity.yml

@@ -1,10 +1,8 @@
 name: Coverity Scan
 
 on:
-  push:
-    branches: [main]
   schedule:
-    - cron: '0 0 * * *'
+    - cron: '0 0 * * 0' # Sundays at 00:00 UTC
   workflow_dispatch:
 
 concurrency:
@@ -43,10 +41,41 @@ jobs:
             echo 'Register wolfTrust on Coverity Scan and configure COVERITY_SCAN_TOKEN and COVERITY_SCAN_EMAIL.' >&2
             exit 1
           fi
-      - name: Run Coverity Scan
+      - name: Capture Coverity build
         uses: vapier/coverity-scan-action@1b6fd4eaba6651aa354c9ea7f48caa1710b4e12e # v1
         with:
           project: wolfTrust
           token: ${{ secrets.COVERITY_SCAN_TOKEN }}
           email: ${{ secrets.COVERITY_SCAN_EMAIL }}
           command: sh tools/ci-static-analysis-build.sh
+          dry_run: 'true'
+      - name: Restrict capture to wolfTrust sources
+        shell: bash
+        run: |
+          export PATH="$PWD/cov-analysis/bin:$PATH"
+          python3 tools/ci-coverity-filter.py
+          tar -czf cov-int.tgz cov-int
+      - name: Submit build to Coverity Scan
+        shell: bash
+        env:
+          COVERITY_TOKEN: ${{ secrets.COVERITY_SCAN_TOKEN }}
+          COVERITY_EMAIL: ${{ secrets.COVERITY_SCAN_EMAIL }}
+        run: |
+          response_file="$RUNNER_TEMP/coverity-upload-response.txt"
+          http_status=$(curl \
+            --silent --show-error \
+            --output "$response_file" \
+            --write-out '%{http_code}' \
+            --form-string "token=$COVERITY_TOKEN" \
+            --form-string "email=$COVERITY_EMAIL" \
+            --form 'file=@cov-int.tgz' \
+            --form-string "version=$GITHUB_SHA" \
+            --form-string "description=wolfTrust $GITHUB_REF" \
+            'https://scan.coverity.com/builds?project=wolfTrust')
+          cat "$response_file"
+          # Coverity's official upload script requires 201 for a new submission.
+          if [ "$http_status" != '201' ]; then
+            echo "::error::Coverity did not accept the build submission (HTTP $http_status)."
+            exit 1
+          fi
+          printf '%s\n' 'Coverity accepted the build for analysis. Results are published after server-side processing.' >> "$GITHUB_STEP_SUMMARY"

tools/ci-coverity-filter.py

@@ -0,0 +1,64 @@
+#!/usr/bin/env python3
+"""Remove dependency translation units before a Coverity Scan upload."""
+
+import re
+import subprocess
+from pathlib import Path
+
+
+def filter_capture():
+    root = Path.cwd().resolve()
+    dependencies = {root / "lib"}
+    index = subprocess.check_output(["git", "ls-files", "--stage", "-z"])
+    for entry in index.split(b"\0"):
+        if entry.startswith(b"160000 "):
+            dependencies.add(root / entry.split(b"\t", 1)[1].decode())
+    # Coverity Scan's ignored component also covers included headers in lib/.
+    # Refuse a new submodule elsewhere rather than upload unexcluded headers.
+    if any(path != root / "lib" and root / "lib" not in path.parents
+           for path in dependencies):
+        raise ValueError("Coverity dependencies must reside under lib/ to "
+                         "match the project's ignored component")
+
+    command = ["cov-manage-emit", "--dir", "cov-int"]
+
+    def owned(source):
+        path = Path(source).resolve()
+        return root in path.parents and not any(
+            dependency in path.parents for dependency in dependencies
+        )
+
+    def list_units():
+        output = subprocess.check_output(command + ["list"], text=True)
+        print(output, end="")
+        units = []
+        for line in output.splitlines():
+            if "->" not in line:
+                continue
+            match = re.fullmatch(
+                r"\s*([0-9]+)\s+->\s+(/.+?)(?: \(recoverable errors\))?", line
+            )
+            if match is None:
+                raise ValueError("Unrecognized Coverity translation unit listing")
+            units.append((match[1], match[2]))
+        if not units:
+            raise ValueError("Coverity capture is empty")
+        return units
+
+    units = list_units()
+    excluded = [unit for unit, source in units if not owned(source)]
+    if excluded:
+        subprocess.run(command + ["--tu", ",".join(excluded), "delete"],
+                       check=True)
+    retained = list_units()
+    if any(not owned(source) for _, source in retained):
+        raise ValueError("Coverity capture still contains dependency sources")
+    print(f"Coverity scope: excluded {len(excluded)} dependency units; "
+          f"retained {len(retained)} wolfTrust units")
+
+
+if __name__ == "__main__":
+    try:
+        filter_capture()
+    except (OSError, ValueError, subprocess.CalledProcessError) as error:
+        raise SystemExit(f"::error::{error}") from error