Refactor fuzzing

Structure the fuzz implementation to be closer to what go native will support.
Add Makefile target to enable smoketesting fuzzers.
Add github workflow to test and upload crash results.

Signed-off-by: Paulo Gomes <paulo.gomes@weave.works>

.github/workflows/cifuzz.yaml

@@ -0,0 +1,24 @@
+name: CIFuzz
+on: [pull_request]
+jobs:
+  Fuzzing:
+    runs-on: ubuntu-latest
+    steps:
+    - name: Build Fuzzers
+      id: build
+      uses: google/oss-fuzz/infra/cifuzz/actions/build_fuzzers@master
+      with:
+        oss-fuzz-project-name: 'fluxcd'
+        language: go
+    - name: Run Fuzzers
+      uses: google/oss-fuzz/infra/cifuzz/actions/run_fuzzers@master
+      with:
+        oss-fuzz-project-name: 'fluxcd'
+        language: go
+        fuzz-seconds: 180
+    - name: Upload Crash
+      uses: actions/upload-artifact@v1
+      if: failure() && steps.build.outcome == 'success'
+      with:
+        name: artifacts
+        path: ./out/artifacts

.gitignore

@@ -13,3 +13,5 @@
 
 # Dependency directories (remove the comment below to include it)
 # vendor/
+
+build/

Makefile

@@ -71,3 +71,23 @@ SETUP_ENVTEST=$(GOBIN)/setup-envtest
 else
 SETUP_ENVTEST=$(shell which setup-envtest)
 endif
+
+
+fuzz-build:
+	rm -rf $(shell pwd)/build/fuzz/
+	mkdir -p $(shell pwd)/build/fuzz/out/
+
+	docker build . --tag local-fuzzing:latest -f tests/fuzz/Dockerfile.builder
+	docker run --rm -it \
+		-e FUZZING_LANGUAGE=go -e FUZZ_SECONDS=600 -e MODE=batch \
+		-e CIFUZZ_DEBUG='True' -e OSS_FUZZ_PROJECT_NAME=fluxcd \
+		-e SANITIZER=address \
+		-v "$(shell pwd)/build/fuzz/out":/out \
+		local-fuzzing:latest
+
+fuzz-smoketest: fuzz-build
+	docker run --rm -ti \
+		-v "$(shell pwd)/build/fuzz/out":/out \
+		-v "$(shell pwd)/tests/fuzz/oss_fuzz_run.sh":/runner.sh \
+		gcr.io/oss-fuzz/fluxcd \
+		bash -c "/runner.sh"

gitutil/gitutil_fuzzer.go

@@ -0,0 +1,26 @@
+//go:build gofuzz
+// +build gofuzz
+
+/*
+Copyright 2021 The Flux authors
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+    http://www.apache.org/licenses/LICENSE-2.0
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+package gitutil
+
+import "errors"
+
+// FuzzLibGit2Error implements a fuzzer that
+// targets gitutil.LibGit2Error
+func FuzzLibGit2Error(data []byte) int {
+	err := errors.New(string(data))
+	_ = LibGit2Error(err)
+	return 1
+}

runtime/events/events_fuzzer.go

@@ -0,0 +1,131 @@
+//go:build gofuzz
+// +build gofuzz
+
+/*
+Copyright 2021 The Flux authors
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+    http://www.apache.org/licenses/LICENSE-2.0
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+package events
+
+import (
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"net/http/httptest"
+	"os"
+	"os/exec"
+	"sync"
+
+	fuzz "github.com/AdaLogics/go-fuzz-headers"
+	"github.com/fluxcd/pkg/runtime/testenv"
+	corev1 "k8s.io/api/core/v1"
+	"k8s.io/apimachinery/pkg/runtime"
+	utilruntime "k8s.io/apimachinery/pkg/util/runtime"
+	ctrl "sigs.k8s.io/controller-runtime"
+)
+
+var (
+	doOnce sync.Once
+	env    *testenv.Environment
+	ts     *httptest.Server
+	ctx    = ctrl.SetupSignalHandler()
+)
+
+func ensureDependencies() error {
+	// only install dependencies when running inside a container
+	if _, err := os.Stat("/.dockerenv"); os.IsNotExist(err) {
+		return nil
+	}
+
+	if os.Getenv("KUBEBUILDER_ASSETS") == "" {
+		cmd := exec.Command("/usr/bin/bash", "-c", `go install sigs.k8s.io/controller-runtime/tools/setup-envtest@latest && \
+		/root/go/bin/setup-envtest use -p path 1.21.x`)
+		cmd.Env = append(os.Environ(), "GOPATH=/root/go")
+		assetsPath, err := cmd.Output()
+		if err == nil {
+			os.Setenv("KUBEBUILDER_ASSETS", string(assetsPath))
+		}
+		return err
+	}
+
+	return nil
+}
+
+// FuzzEventInfof implements a fuzzer that
+// targets eventRecorder.Eventf()
+func FuzzEventf(data []byte) int {
+	doOnce.Do(func() {
+		if err := ensureDependencies(); err != nil {
+			panic(fmt.Sprintf("Failed to start the test environment manager: %v", err))
+		}
+	})
+
+	ts = httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		b, err := io.ReadAll(r.Body)
+		if err != nil {
+			return
+		}
+
+		var payload Event
+		err = json.Unmarshal(b, &payload)
+		if err != nil {
+			return
+		}
+	}))
+	defer ts.Close()
+
+	scheme := runtime.NewScheme()
+	utilruntime.Must(corev1.AddToScheme(scheme))
+
+	env = testenv.New(
+		testenv.WithScheme(scheme),
+	)
+
+	go func() {
+		fmt.Println("Starting the test environment")
+		if err := env.Start(ctx); err != nil {
+			panic(fmt.Sprintf("Failed to start the test environment manager: %v", err))
+		}
+	}()
+	<-env.Manager.Elected()
+
+	eventRecorder, err := NewRecorder(env, ctrl.Log, ts.URL, "test-controller")
+	if err != nil {
+		return 0
+	}
+	eventRecorder.Client.RetryMax = 2
+	//TODO: Reuse the setup above across fuzzing calls
+	// this will be easier once fuzzing is migrated to
+	// native golang fuzz.
+
+	f := fuzz.NewConsumer(data)
+	obj := corev1.ConfigMap{}
+	err = f.GenerateStruct(&obj)
+	if err != nil {
+		return 0
+	}
+	eventtype, err := f.GetString()
+	if err != nil {
+		return 0
+	}
+	reason, err := f.GetString()
+	if err != nil {
+		return 0
+	}
+	eventRecorder.Eventf(&obj, eventtype, reason, obj.Name)
+
+	if err = env.Stop(); err != nil {
+		return 0
+	}
+
+	return 1
+}