diff --git a/api/v1beta1/provider_types.go b/api/v1beta1/provider_types.go index a1043202a..e3622fed8 100644 --- a/api/v1beta1/provider_types.go +++ b/api/v1beta1/provider_types.go @@ -30,7 +30,7 @@ const ( // ProviderSpec defines the desired state of Provider type ProviderSpec struct { // Type of provider - // +kubebuilder:validation:Enum=slack;discord;msteams;rocket;generic;github;gitlab;bitbucket;azuredevops;googlechat;webex;sentry;azureeventhub;telegram;lark;matrix;opsgenie;alertmanager;grafana;githubdispatch; + // +kubebuilder:validation:Enum=slack;discord;msteams;rocket;generic;generic-hmac;github;gitlab;bitbucket;azuredevops;googlechat;webex;sentry;azureeventhub;telegram;lark;matrix;opsgenie;alertmanager;grafana;githubdispatch; // +required Type string `json:"type"` @@ -78,6 +78,7 @@ type ProviderSpec struct { const ( GenericProvider string = "generic" + GenericHMACProvider string = "generic-hmac" SlackProvider string = "slack" GrafanaProvider string = "grafana" DiscordProvider string = "discord" diff --git a/config/crd/bases/notification.toolkit.fluxcd.io_providers.yaml b/config/crd/bases/notification.toolkit.fluxcd.io_providers.yaml index 425fb3609..f80113523 100644 --- a/config/crd/bases/notification.toolkit.fluxcd.io_providers.yaml +++ b/config/crd/bases/notification.toolkit.fluxcd.io_providers.yaml @@ -92,6 +92,7 @@ spec: - msteams - rocket - generic + - generic-hmac - github - gitlab - bitbucket diff --git a/docs/spec/v1beta1/provider.md b/docs/spec/v1beta1/provider.md index fb4d83978..b36f92cf5 100644 --- a/docs/spec/v1beta1/provider.md +++ b/docs/spec/v1beta1/provider.md @@ -9,7 +9,7 @@ Spec: ```go type ProviderSpec struct { // Type of provider - // +kubebuilder:validation:Enum=slack;discord;msteams;rocket;generic;github;gitlab;bitbucket;azuredevops;googlechat;webex;sentry;azureeventhub;telegram;lark;matrix;opsgenie;githubdispatch + // +kubebuilder:validation:Enum=slack;discord;msteams;rocket;generic;generic-hmac;github;gitlab;bitbucket;azuredevops;googlechat;webex;sentry;azureeventhub;telegram;lark;matrix;opsgenie;githubdispatch // +required Type string `json:"type"` @@ -51,22 +51,23 @@ Notification providers: | Provider | Type | | --------------- | -------------- | -| Alertmanager | alertmanager | -| Azure Event Hub | azureeventhub | -| Discord | discord | -| Generic webhook | generic | -| GitHub dispatch | githubdispatch | -| Google Chat | googlechat | -| Grafana | grafana | -| Lark | lark | -| Matrix | matrix | -| Microsoft Teams | msteams | -| Opsgenie | opsgenie | -| Rocket | rocket | -| Sentry | sentry | -| Slack | slack | -| Telegram | telegram | -| WebEx | webex | +| Alertmanager | alertmanager | +| Azure Event Hub | azureeventhub | +| Discord | discord | +| Generic webhook | generic | +| Generic webhook with HMAC | generic-hmac | +| GitHub dispatch | githubdispatch | +| Google Chat | googlechat | +| Grafana | grafana | +| Lark | lark | +| Matrix | matrix | +| Microsoft Teams | msteams | +| Opsgenie | opsgenie | +| Rocket | rocket | +| Sentry | sentry | +| Slack | slack | +| Telegram | telegram | +| WebEx | webex | Git commit status providers: @@ -211,6 +212,54 @@ stringData: X-Forwarded-Proto: https ``` +### Generic webhook with HMAC + +If you set the `.spec.type` of a `Provider` resource to `generic-hmac` then the HTTP request sent to the webhook will include the `X-Signature` HTTP header carrying the HMAC of the request body. This allows the webhook server to authenticate the request. The key used for the HMAC must be supplied in the `token` field of the Secret resource referenced in `.spec.secretRef`. The HTTP header value has the following format: + +``` +X-Signature: HASH_FUNC=HASH +``` + +`HASH_FUNC` denotes the Hash function used to generate the HMAC and currently defaults to `sha256` but may change in the future. You must make sure to take this value into account when verifying the HMAC. `HASH` is the hex-encoded HMAC value. The following Go code illustrates how the header is parsed and verified: + +```go +func verifySignature(sig string, payload, key []byte) error { + sigHdr := strings.Split(sig, "=") + if len(shgHdr) != 2 { + return fmt.Errorf("invalid signature value") + } + var newF func() hash.Hash + switch sigHdr[0] { + case "sha224": + newF = sha256.New224 + case "sha256": + newF = sha256.New + case "sha384": + newF = sha512.New384 + case "sha512": + newF = sha512.New + default: + return fmt.Errorf("unsupported signature algorithm %q", sigHdr[0]) + } + mac := hmac.New(newF, key) + if _, err := mac.Write(payload); err != nil { + return fmt.Errorf("error MAC'ing payload: %w", err) + } + sum := fmt.Sprintf("%x", mac.Sum(nil)) + if sum != sigHdr[1] { + return fmt.Errorf("HMACs don't match: %#v != %#v", sum, sigHdr[1]) + } + return nil +} +[...] +key := []byte("b1fad212fb1b87a56c79e5da48018650b85ab7cf") +if len(r.Header["X-Signature"]) > 0 { + if err := verifySignature(r.Header["X-Signature"][0], body, key); err != nil { + // handle signature verification failure here + } +} +``` + ### Self-signed certificates The `certSecretRef` field names a secret with TLS certificate data. This is for the purpose diff --git a/internal/notifier/factory.go b/internal/notifier/factory.go index 6d6b23eaa..91a52d90c 100644 --- a/internal/notifier/factory.go +++ b/internal/notifier/factory.go @@ -56,7 +56,9 @@ func (f Factory) Notifier(provider string) (Interface, error) { var err error switch provider { case v1beta1.GenericProvider: - n, err = NewForwarder(f.URL, f.ProxyURL, f.Headers, f.CertPool) + n, err = NewForwarder(f.URL, f.ProxyURL, f.Headers, f.CertPool, nil) + case v1beta1.GenericHMACProvider: + n, err = NewForwarder(f.URL, f.ProxyURL, f.Headers, f.CertPool, []byte(f.Token)) case v1beta1.SlackProvider: n, err = NewSlack(f.URL, f.ProxyURL, f.Token, f.CertPool, f.Username, f.Channel) case v1beta1.DiscordProvider: diff --git a/internal/notifier/forwarder.go b/internal/notifier/forwarder.go index 203cca070..474c71791 100644 --- a/internal/notifier/forwarder.go +++ b/internal/notifier/forwarder.go @@ -18,7 +18,10 @@ package notifier import ( "context" + "crypto/hmac" + "crypto/sha256" "crypto/x509" + "encoding/json" "fmt" "net/url" @@ -38,23 +41,46 @@ type Forwarder struct { ProxyURL string Headers map[string]string CertPool *x509.CertPool + HMACKey []byte } -func NewForwarder(hookURL string, proxyURL string, headers map[string]string, certPool *x509.CertPool) (*Forwarder, error) { +func NewForwarder(hookURL string, proxyURL string, headers map[string]string, certPool *x509.CertPool, hmacKey []byte) (*Forwarder, error) { if _, err := url.ParseRequestURI(hookURL); err != nil { return nil, fmt.Errorf("invalid hook URL %s: %w", hookURL, err) } + if hmacKey != nil && len(hmacKey) == 0 { + return nil, fmt.Errorf("HMAC key is empty") + } + return &Forwarder{ URL: hookURL, ProxyURL: proxyURL, Headers: headers, CertPool: certPool, + HMACKey: hmacKey, }, nil } +func sign(payload, key []byte) string { + h := hmac.New(sha256.New, key) + h.Write(payload) + return fmt.Sprintf("%x", h.Sum(nil)) +} + func (f *Forwarder) Post(ctx context.Context, event events.Event) error { + var sig string + if len(f.HMACKey) != 0 { + eventJSON, err := json.Marshal(event) + if err != nil { + return fmt.Errorf("failed marshalling event: %w", err) + } + sig = fmt.Sprintf("sha256=%s", sign(eventJSON, f.HMACKey)) + } err := postMessage(ctx, f.URL, f.ProxyURL, f.CertPool, event, func(req *retryablehttp.Request) { + if sig != "" { + req.Header.Set("X-Signature", sig) + } req.Header.Set(NotificationHeader, event.ReportingController) for key, val := range f.Headers { req.Header.Set(key, val) diff --git a/internal/notifier/forwarder_test.go b/internal/notifier/forwarder_test.go index eb4dd6621..34d30db0b 100644 --- a/internal/notifier/forwarder_test.go +++ b/internal/notifier/forwarder_test.go @@ -25,42 +25,83 @@ import ( "net/http" "net/http/httptest" "testing" + "time" fuzz "github.com/AdaLogics/go-fuzz-headers" "github.com/fluxcd/pkg/runtime/events" + metav1 "k8s.io/apimachinery/pkg/apis/meta/v1" "github.com/stretchr/testify/require" ) func TestForwarder_Post(t *testing.T) { - ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) { - b, err := io.ReadAll(r.Body) - require.NoError(t, err) - - require.Equal(t, "source-controller", r.Header.Get("gotk-component")) - require.Equal(t, "token", r.Header.Get("Authorization")) - var payload = events.Event{} - err = json.Unmarshal(b, &payload) - require.NoError(t, err) - require.Equal(t, "webapp", payload.InvolvedObject.Name) - require.Equal(t, "metadata", payload.Metadata["test"]) - })) - defer ts.Close() - - headers := make(map[string]string) - headers["Authorization"] = "token" - forwarder, err := NewForwarder(ts.URL, "", headers, nil) - require.NoError(t, err) - - err = forwarder.Post(context.TODO(), testEvent()) - require.NoError(t, err) + tests := []struct { + name string + hmacKey []byte + hmacHeader string + }{ + { + name: "happy path with nil HMAC key", + hmacKey: nil, + hmacHeader: "", + }, + { + name: "happy path with empty HMAC key", + hmacKey: []byte{}, + hmacHeader: "", + }, + { + name: "happy path with HMAC key from empty string", + hmacKey: []byte(""), + hmacHeader: "", + }, + { + name: "non-empty HMAC key adds signature header", + hmacKey: []byte("7152fed34dd6149a7c75a276c510da27cb6f82b0"), + hmacHeader: "sha256=65b018549b1254e7226d1c08f9567ee45bc9de0fc4e7b1a40253f9a018b08be7", + }, + } + + for _, tt := range tests { + t.Run(tt.name, func(t *testing.T) { + ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) { + b, err := io.ReadAll(r.Body) + require.NoError(t, err) + + require.Equal(t, "source-controller", r.Header.Get("gotk-component")) + require.Equal(t, "token", r.Header.Get("Authorization")) + if tt.hmacHeader == "" { + _, ok := r.Header["X-Signature"] + require.Equal(t, false, ok, "expected signature header to be absent but it was present") + } else { + require.Equal(t, tt.hmacHeader, r.Header.Get("X-Signature")) + } + var payload = events.Event{} + err = json.Unmarshal(b, &payload) + require.NoError(t, err) + require.Equal(t, "webapp", payload.InvolvedObject.Name) + require.Equal(t, "metadata", payload.Metadata["test"]) + })) + defer ts.Close() + + headers := make(map[string]string) + headers["Authorization"] = "token" + forwarder, err := NewForwarder(ts.URL, "", headers, nil, tt.hmacKey) + require.NoError(t, err) + + ev := testEvent() + ev.Timestamp = metav1.NewTime(time.Unix(1664520029, 0)) + err = forwarder.Post(context.TODO(), ev) + require.NoError(t, err) + }) + } } func Fuzz_Forwarder(f *testing.F) { - f.Add("", []byte{}, []byte{}) + f.Add("", []byte{}, []byte{}, []byte{}) f.Fuzz(func(t *testing.T, - urlSuffix string, seed, response []byte) { + urlSuffix string, seed, response, hmacKey []byte) { ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) { w.Write(response) io.Copy(io.Discard, r.Body) @@ -74,7 +115,7 @@ func Fuzz_Forwarder(f *testing.F) { header := make(map[string]string) _ = fuzz.NewConsumer(seed).FuzzMap(&header) - forwarder, err := NewForwarder(fmt.Sprintf("%s/%s", ts.URL, urlSuffix), "", header, &cert) + forwarder, err := NewForwarder(fmt.Sprintf("%s/%s", ts.URL, urlSuffix), "", header, &cert, hmacKey) if err != nil { return }