config: validate proxy path

Like shim, we should validate the proxy path if it is provided.

Fixes: #1424

Signed-off-by: Peng Tao <bergwolf@hyper.sh>

pkg/katautils/config.go

@@ -357,12 +357,13 @@ func (h hypervisor) getInitrdAndImage() (initrd string, image string, err error)
 	return
 }
 
-func (p proxy) path() string {
-	if p.Path == "" {
-		return defaultProxyPath
+func (p proxy) path() (string, error) {
+	path := p.Path
+	if path == "" {
+		path = defaultProxyPath
 	}
 
-	return p.Path
+	return ResolvePath(path)
 }
 
 func (p proxy) debug() bool {
@@ -606,8 +607,13 @@ func updateRuntimeConfigProxy(configPath string, tomlConf tomlConfig, config *oc
 			config.ProxyType = vc.KataProxyType
 		}
 
+		path, err := proxy.path()
+		if err != nil {
+			return err
+		}
+
 		config.ProxyConfig = vc.ProxyConfig{
-			Path:  proxy.path(),
+			Path:  path,
 			Debug: proxy.debug(),
 		}
 	}

pkg/katautils/config_test.go

@@ -1122,13 +1122,43 @@ func TestHypervisorDefaultsGuestHookPath(t *testing.T) {
 }
 
 func TestProxyDefaults(t *testing.T) {
+	assert := assert.New(t)
+
+	tmpdir, err := ioutil.TempDir(testDir, "")
+	assert.NoError(err)
+	defer os.RemoveAll(tmpdir)
+
+	testProxyPath := filepath.Join(tmpdir, "proxy")
+	testProxyLinkPath := filepath.Join(tmpdir, "proxy-link")
+
+	err = createEmptyFile(testProxyPath)
+	assert.NoError(err)
+
+	err = syscall.Symlink(testProxyPath, testProxyLinkPath)
+	assert.NoError(err)
+
+	savedProxyPath := defaultProxyPath
+
+	defer func() {
+		defaultProxyPath = savedProxyPath
+	}()
+
+	defaultProxyPath = testProxyPath
 	p := proxy{}
+	path, err := p.path()
+	assert.NoError(err)
+	assert.Equal(path, defaultProxyPath, "default proxy path wrong")
 
-	assert.Equal(t, p.path(), defaultProxyPath, "default proxy path wrong")
+	// test path resolution
+	defaultProxyPath = testProxyLinkPath
+	p = proxy{}
+	path, err = p.path()
+	assert.NoError(err)
+	assert.Equal(path, testProxyPath)
 
-	path := "/foo/bar/baz/proxy"
-	p.Path = path
-	assert.Equal(t, p.path(), path, "custom proxy path wrong")
+	assert.False(p.debug())
+	p.Debug = true
+	assert.True(p.debug())
 }
 
 func TestShimDefaults(t *testing.T) {