ACME Certificate Revocation

CHANGELOG.md

@@ -6,6 +6,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 
 ## [Unreleased - 0.18.1] - DATE
 ### Added
+- Support for ACME revocation.
 ### Changed
 ### Deprecated
 ### Removed

acme/api/handler.go

@@ -100,11 +100,17 @@ func (h *Handler) Route(r api.Router) {
 	r.MethodFunc("GET", getPath(DirectoryLinkType, "{provisionerID}"), h.baseURLFromRequest(h.lookupProvisioner(h.GetDirectory)))
 	r.MethodFunc("HEAD", getPath(DirectoryLinkType, "{provisionerID}"), h.baseURLFromRequest(h.lookupProvisioner(h.GetDirectory)))
 
+	validatingMiddleware := func(next nextHTTP) nextHTTP {
+		return h.baseURLFromRequest(h.lookupProvisioner(h.addNonce(h.addDirLink(h.verifyContentType(h.parseJWS(h.validateJWS(next)))))))
+	}
 	extractPayloadByJWK := func(next nextHTTP) nextHTTP {
-		return h.baseURLFromRequest(h.lookupProvisioner(h.addNonce(h.addDirLink(h.verifyContentType(h.parseJWS(h.validateJWS(h.extractJWK(h.verifyAndExtractJWSPayload(next)))))))))
+		return validatingMiddleware(h.extractJWK(h.verifyAndExtractJWSPayload(next)))
 	}
 	extractPayloadByKid := func(next nextHTTP) nextHTTP {
-		return h.baseURLFromRequest(h.lookupProvisioner(h.addNonce(h.addDirLink(h.verifyContentType(h.parseJWS(h.validateJWS(h.lookupJWK(h.verifyAndExtractJWSPayload(next)))))))))
+		return validatingMiddleware(h.lookupJWK(h.verifyAndExtractJWSPayload(next)))
+	}
+	extractPayloadByKidOrJWK := func(next nextHTTP) nextHTTP {
+		return validatingMiddleware(h.extractOrLookupJWK(h.verifyAndExtractJWSPayload(next)))
 	}
 
 	r.MethodFunc("POST", getPath(NewAccountLinkType, "{provisionerID}"), extractPayloadByJWK(h.NewAccount))
@@ -117,6 +123,7 @@ func (h *Handler) Route(r api.Router) {
 	r.MethodFunc("POST", getPath(AuthzLinkType, "{provisionerID}", "{authzID}"), extractPayloadByKid(h.isPostAsGet(h.GetAuthorization)))
 	r.MethodFunc("POST", getPath(ChallengeLinkType, "{provisionerID}", "{authzID}", "{chID}"), extractPayloadByKid(h.GetChallenge))
 	r.MethodFunc("POST", getPath(CertificateLinkType, "{provisionerID}", "{certID}"), extractPayloadByKid(h.isPostAsGet(h.GetCertificate)))
+	r.MethodFunc("POST", getPath(RevokeCertLinkType, "{provisionerID}"), extractPayloadByKidOrJWK(h.RevokeCert))
 }
 
 // GetNonce just sets the right header since a Nonce is added to each response

acme/api/middleware.go

@@ -262,11 +262,11 @@ func (h *Handler) extractJWK(next nextHTTP) nextHTTP {
 		// Store the JWK in the context.
 		ctx = context.WithValue(ctx, jwkContextKey, jwk)
 
-		// Get Account or continue to generate a new one.
+		// Get Account OR continue to generate a new one OR continue Revoke with certificate private key
 		acc, err := h.db.GetAccountByKeyID(ctx, jwk.KeyID)
 		switch {
 		case errors.Is(err, acme.ErrNotFound):
-			// For NewAccount requests ...
+			// For NewAccount and Revoke requests ...
 			break
 		case err != nil:
 			api.WriteError(w, err)
@@ -352,6 +352,42 @@ func (h *Handler) lookupJWK(next nextHTTP) nextHTTP {
 	}
 }
 
+// extractOrLookupJWK forwards handling to either extractJWK or
+// lookupJWK based on the presence of a JWK or a KID, respectively.
+func (h *Handler) extractOrLookupJWK(next nextHTTP) nextHTTP {
+	return func(w http.ResponseWriter, r *http.Request) {
+		ctx := r.Context()
+		jws, err := jwsFromContext(ctx)
+		if err != nil {
+			api.WriteError(w, err)
+			return
+		}
+
+		// at this point the JWS has already been verified (if correctly configured in middleware),
+		// and it can be used to check if a JWK exists. This flow is used when the ACME client
+		// signed the payload with a certificate private key.
+		if canExtractJWKFrom(jws) {
+			h.extractJWK(next)(w, r)
+			return
+		}
+
+		// default to looking up the JWK based on KeyID. This flow is used when the ACME client
+		// signed the payload with an account private key.
+		h.lookupJWK(next)(w, r)
+	}
+}
+
+// canExtractJWKFrom checks if the JWS has a JWK that can be extracted
+func canExtractJWKFrom(jws *jose.JSONWebSignature) bool {
+	if jws == nil {
+		return false
+	}
+	if len(jws.Signatures) == 0 {
+		return false
+	}
+	return jws.Signatures[0].Protected.JSONWebKey != nil
+}
+
 // verifyAndExtractJWSPayload extracts the JWK from the JWS and saves it in the context.
 // Make sure to parse and validate the JWS before running this middleware.
 func (h *Handler) verifyAndExtractJWSPayload(next nextHTTP) nextHTTP {

acme/api/middleware_test.go

@@ -1472,3 +1472,187 @@ func TestHandler_validateJWS(t *testing.T) {
 		})
 	}
 }
+
+func Test_canExtractJWKFrom(t *testing.T) {
+	jwk, err := jose.GenerateJWK("EC", "P-256", "ES256", "sig", "", 0)
+	assert.FatalError(t, err)
+	type args struct {
+		jws *jose.JSONWebSignature
+	}
+	tests := []struct {
+		name string
+		args args
+		want bool
+	}{
+		{
+			name: "no-jws",
+			args: args{
+				jws: nil,
+			},
+			want: false,
+		},
+		{
+			name: "no-signatures",
+			args: args{
+				jws: &jose.JSONWebSignature{
+					Signatures: []jose.Signature{},
+				},
+			},
+			want: false,
+		},
+		{
+			name: "no-jwk",
+			args: args{
+				jws: &jose.JSONWebSignature{
+					Signatures: []jose.Signature{
+						{
+							Protected: jose.Header{},
+						},
+					},
+				},
+			},
+			want: false,
+		},
+		{
+			name: "ok",
+			args: args{
+				jws: &jose.JSONWebSignature{
+					Signatures: []jose.Signature{
+						{
+							Protected: jose.Header{
+								JSONWebKey: jwk,
+							},
+						},
+					},
+				},
+			},
+			want: true,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := canExtractJWKFrom(tt.args.jws); got != tt.want {
+				t.Errorf("canExtractJWKFrom() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}
+
+func TestHandler_extractOrLookupJWK(t *testing.T) {
+	u := "https://ca.smallstep.com/acme/account"
+	type test struct {
+		db         acme.DB
+		linker     Linker
+		statusCode int
+		ctx        context.Context
+		err        *acme.Error
+		next       func(w http.ResponseWriter, r *http.Request)
+	}
+	var tests = map[string]func(t *testing.T) test{
+		"ok/extract": func(t *testing.T) test {
+			jwk, err := jose.GenerateJWK("EC", "P-256", "ES256", "sig", "", 0)
+			assert.FatalError(t, err)
+			kid, err := jwk.Thumbprint(crypto.SHA256)
+			assert.FatalError(t, err)
+			pub := jwk.Public()
+			pub.KeyID = base64.RawURLEncoding.EncodeToString(kid)
+			so := new(jose.SignerOptions)
+			so.WithHeader("jwk", pub) // JWK for certificate private key flow
+			signer, err := jose.NewSigner(jose.SigningKey{
+				Algorithm: jose.SignatureAlgorithm(jwk.Algorithm),
+				Key:       jwk.Key,
+			}, so)
+			assert.FatalError(t, err)
+			signed, err := signer.Sign([]byte("foo"))
+			assert.FatalError(t, err)
+			raw, err := signed.CompactSerialize()
+			assert.FatalError(t, err)
+			parsedJWS, err := jose.ParseJWS(raw)
+			assert.FatalError(t, err)
+			return test{
+				linker: NewLinker("dns", "acme"),
+				db: &acme.MockDB{
+					MockGetAccountByKeyID: func(ctx context.Context, kid string) (*acme.Account, error) {
+						assert.Equals(t, kid, pub.KeyID)
+						return nil, acme.ErrNotFound
+					},
+				},
+				ctx:        context.WithValue(context.Background(), jwsContextKey, parsedJWS),
+				statusCode: 200,
+				next: func(w http.ResponseWriter, r *http.Request) {
+					w.Write(testBody)
+				},
+			}
+		},
+		"ok/lookup": func(t *testing.T) test {
+			prov := newProv()
+			provName := url.PathEscape(prov.GetName())
+			baseURL := &url.URL{Scheme: "https", Host: "test.ca.smallstep.com"}
+			jwk, err := jose.GenerateJWK("EC", "P-256", "ES256", "sig", "", 0)
+			assert.FatalError(t, err)
+			accID := "accID"
+			prefix := fmt.Sprintf("%s/acme/%s/account/", baseURL, provName)
+			so := new(jose.SignerOptions)
+			so.WithHeader("kid", fmt.Sprintf("%s%s", prefix, accID)) // KID for account private key flow
+			signer, err := jose.NewSigner(jose.SigningKey{
+				Algorithm: jose.SignatureAlgorithm(jwk.Algorithm),
+				Key:       jwk.Key,
+			}, so)
+			assert.FatalError(t, err)
+			jws, err := signer.Sign([]byte("baz"))
+			assert.FatalError(t, err)
+			raw, err := jws.CompactSerialize()
+			assert.FatalError(t, err)
+			parsedJWS, err := jose.ParseJWS(raw)
+			assert.FatalError(t, err)
+			acc := &acme.Account{ID: "accID", Key: jwk, Status: "valid"}
+			ctx := context.WithValue(context.Background(), provisionerContextKey, prov)
+			ctx = context.WithValue(ctx, baseURLContextKey, baseURL)
+			ctx = context.WithValue(ctx, jwsContextKey, parsedJWS)
+			return test{
+				linker: NewLinker("test.ca.smallstep.com", "acme"),
+				db: &acme.MockDB{
+					MockGetAccount: func(ctx context.Context, accID string) (*acme.Account, error) {
+						assert.Equals(t, accID, acc.ID)
+						return acc, nil
+					},
+				},
+				ctx:        ctx,
+				statusCode: 200,
+				next: func(w http.ResponseWriter, r *http.Request) {
+					w.Write(testBody)
+				},
+			}
+		},
+	}
+	for name, prep := range tests {
+		tc := prep(t)
+		t.Run(name, func(t *testing.T) {
+			h := &Handler{db: tc.db, linker: tc.linker}
+			req := httptest.NewRequest("GET", u, nil)
+			req = req.WithContext(tc.ctx)
+			w := httptest.NewRecorder()
+			h.extractOrLookupJWK(tc.next)(w, req)
+			res := w.Result()
+
+			assert.Equals(t, res.StatusCode, tc.statusCode)
+
+			body, err := io.ReadAll(res.Body)
+			res.Body.Close()
+			assert.FatalError(t, err)
+
+			if res.StatusCode >= 400 && assert.NotNil(t, tc.err) {
+				var ae acme.Error
+				assert.FatalError(t, json.Unmarshal(bytes.TrimSpace(body), &ae))
+
+				assert.Equals(t, ae.Type, tc.err.Type)
+				assert.Equals(t, ae.Detail, tc.err.Detail)
+				assert.Equals(t, ae.Identifier, tc.err.Identifier)
+				assert.Equals(t, ae.Subproblems, tc.err.Subproblems)
+				assert.Equals(t, res.Header["Content-Type"], []string{"application/problem+json"})
+			} else {
+				assert.Equals(t, bytes.TrimSpace(body), testBody)
+			}
+		})
+	}
+}