registry: repo URL and dockerconfig URL mismatch

Registry login option should verify that the obtained dockerconfig
credentials are for the same host. When the helmrepo URL and the URL in
docker auth config don't match, the docker config store returns an
empty auth config, instead of failing. This results in accepting empty
username and password. The HelmRepo would appear to be ready in such
situation because the creds are empty, no login is attempted. But when
a HelmChart tries to use the login options, it'd fail.

Signed-off-by: Sunny <darkowlzz@protonmail.com>

internal/helm/registry/auth.go

@@ -1,3 +1,19 @@
+/*
+Copyright 2022 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 registry
 
 import (
@@ -30,6 +46,13 @@ func LoginOptionFromSecret(registryURL string, secret corev1.Secret) (registry.L
 		if err != nil {
 			return nil, fmt.Errorf("unable to get authentication data from Secret '%s': %w", secret.Name, err)
 		}
+		// Make sure that the obtained auth config is for the requested host.
+		// When the docker config does not contain the credentials for a host,
+		// the credential store returns an empty auth config.
+		// Refer: https://github.com/docker/cli/blob/v20.10.16/cli/config/credentials/file_store.go#L44
+		if authConfig.ServerAddress != parsedURL.Host {
+			return nil, fmt.Errorf("no auth config for '%s' in the docker-registry Secret '%s'", parsedURL.Host, secret.Name)
+		}
 		username = authConfig.Username
 		password = authConfig.Password
 	} else {

internal/helm/registry/auth_test.go

@@ -0,0 +1,121 @@
+/*
+Copyright 2022 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 registry
+
+import (
+	"testing"
+
+	. "github.com/onsi/gomega"
+	corev1 "k8s.io/api/core/v1"
+)
+
+func TestLoginOptionFromSecret(t *testing.T) {
+	testURL := "oci://registry.example.com/foo/bar"
+	testUser := "flux"
+	testPassword := "somepassword"
+	testDockerconfigjson := `{"auths":{"registry.example.com":{"username":"flux","password":"somepassword","auth":"Zmx1eDpzb21lcGFzc3dvcmQ="}}}`
+	dockerconfigjsonKey := ".dockerconfigjson"
+
+	tests := []struct {
+		name       string
+		url        string
+		secretType corev1.SecretType
+		secretData map[string][]byte
+		wantErr    bool
+	}{
+		{
+			name:       "generic secret",
+			url:        testURL,
+			secretType: corev1.SecretTypeOpaque,
+			secretData: map[string][]byte{
+				"username": []byte(testUser),
+				"password": []byte(testPassword),
+			},
+		},
+		{
+			name:       "generic secret without username",
+			url:        testURL,
+			secretType: corev1.SecretTypeOpaque,
+			secretData: map[string][]byte{
+				"password": []byte(testPassword),
+			},
+			wantErr: true,
+		},
+		{
+			name:       "generic secret without password",
+			url:        testURL,
+			secretType: corev1.SecretTypeOpaque,
+			secretData: map[string][]byte{
+				"username": []byte(testUser),
+			},
+			wantErr: true,
+		},
+		{
+			name: "generic secret without username and password",
+			url:  testURL,
+		},
+		{
+			name:       "docker-registry secret",
+			url:        testURL,
+			secretType: corev1.SecretTypeDockerConfigJson,
+			secretData: map[string][]byte{
+				dockerconfigjsonKey: []byte(testDockerconfigjson),
+			},
+		},
+		{
+			name:       "docker-registry secret host mismatch",
+			url:        "oci://registry.gitlab.com",
+			secretType: corev1.SecretTypeDockerConfigJson,
+			secretData: map[string][]byte{
+				".dockerconfigjson": []byte(testDockerconfigjson),
+			},
+			wantErr: true,
+		},
+		{
+			name:       "docker-registry secret invalid host",
+			url:        "oci://registry .gitlab.com",
+			secretType: corev1.SecretTypeDockerConfigJson,
+			secretData: map[string][]byte{
+				".dockerconfigjson": []byte(testDockerconfigjson),
+			},
+			wantErr: true,
+		},
+		{
+			name:       "docker-registry secret invalid docker config",
+			url:        testURL,
+			secretType: corev1.SecretTypeDockerConfigJson,
+			secretData: map[string][]byte{
+				".dockerconfigjson": []byte("foo"),
+			},
+			wantErr: true,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			g := NewWithT(t)
+
+			secret := corev1.Secret{}
+			secret.Name = "test-secret"
+			secret.Data = tt.secretData
+			secret.Type = tt.secretType
+
+			_, err := LoginOptionFromSecret(tt.url, secret)
+			g.Expect(err != nil).To(Equal(tt.wantErr))
+		})
+	}
+}