Add group-accessible-repos option (#308)

* Add group-accessible-repos option

The group-accessible-repos option will let filesystem group id
be able to access files and dir within the restic repo
Default stick with old behaviour to be owner restricted
While here make dirMode and fileMode within Options struct
private

---------

Co-authored-by: Michael Eischer <michael.eischer@fau.de>

changelog/unreleased/issue-189

@@ -0,0 +1,9 @@
+Enhancement: Support group accessible repositories
+
+Rest-server now supports making repositories accessible to the filesystem group
+by setting the `--group-accessible-repos` option. Note that permissions of
+existing files are not modified. Use `chmod -R g+rwX /path/to/repo` to make
+the repository group-accessible.
+
+https://github.com/restic/rest-server/issues/189
+https://github.com/restic/rest-server/pull/308

cmd/rest-server/main.go

@@ -69,6 +69,7 @@ func newRestServerApp() *restServerApp {
 	flags.BoolVar(&rv.Server.PrivateRepos, "private-repos", rv.Server.PrivateRepos, "users can only access their private repo")
 	flags.BoolVar(&rv.Server.Prometheus, "prometheus", rv.Server.Prometheus, "enable Prometheus metrics")
 	flags.BoolVar(&rv.Server.PrometheusNoAuth, "prometheus-no-auth", rv.Server.PrometheusNoAuth, "disable auth for Prometheus /metrics endpoint")
+	flags.BoolVar(&rv.Server.GroupAccessibleRepos, "group-accessible-repos", rv.Server.GroupAccessibleRepos, "let filesystem group be able to access repo files")
 
 	return rv
 }
@@ -149,6 +150,12 @@ func (app *restServerApp) runRoot(_ *cobra.Command, _ []string) error {
 		log.Println("Private repositories disabled")
 	}
 
+	if app.Server.GroupAccessibleRepos {
+		log.Println("Group accessible repos enabled")
+	} else {
+		log.Println("Group accessible repos disabled")
+	}
+
 	enabledTLS, privateKey, publicKey, err := app.tlsSettings()
 	if err != nil {
 		return err

handlers.go

@@ -15,23 +15,24 @@ import (
 
 // Server encapsulates the rest-server's settings and repo management logic
 type Server struct {
-	Path             string
-	HtpasswdPath     string
-	Listen           string
-	Log              string
-	CPUProfile       string
-	TLSKey           string
-	TLSCert          string
-	TLS              bool
-	NoAuth           bool
-	AppendOnly       bool
-	PrivateRepos     bool
-	Prometheus       bool
-	PrometheusNoAuth bool
-	Debug            bool
-	MaxRepoSize      int64
-	PanicOnError     bool
-	NoVerifyUpload   bool
+	Path                 string
+	HtpasswdPath         string
+	Listen               string
+	Log                  string
+	CPUProfile           string
+	TLSKey               string
+	TLSCert              string
+	TLS                  bool
+	NoAuth               bool
+	AppendOnly           bool
+	PrivateRepos         bool
+	Prometheus           bool
+	PrometheusNoAuth     bool
+	Debug                bool
+	MaxRepoSize          int64
+	PanicOnError         bool
+	NoVerifyUpload       bool
+	GroupAccessibleRepos bool
 
 	htpasswdFile *HtpasswdFile
 	quotaManager *quota.Manager
@@ -88,12 +89,13 @@ func (s *Server) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 
 	// Pass the request to the repo.Handler
 	opt := repo.Options{
-		AppendOnly:     s.AppendOnly,
-		Debug:          s.Debug,
-		QuotaManager:   s.quotaManager, // may be nil
-		PanicOnError:   s.PanicOnError,
-		NoVerifyUpload: s.NoVerifyUpload,
-		FsyncWarning:   &s.fsyncWarning,
+		AppendOnly:      s.AppendOnly,
+		Debug:           s.Debug,
+		QuotaManager:    s.quotaManager, // may be nil
+		PanicOnError:    s.PanicOnError,
+		NoVerifyUpload:  s.NoVerifyUpload,
+		FsyncWarning:    &s.fsyncWarning,
+		GroupAccessible: s.GroupAccessibleRepos,
 	}
 	if s.Prometheus {
 		opt.BlobMetricFunc = makeBlobMetricFunc(username, folderPath)

repo/repo.go

@@ -28,8 +28,6 @@ import (
 type Options struct {
 	AppendOnly     bool // if set, delete actions are not allowed
 	Debug          bool
-	DirMode        os.FileMode
-	FileMode       os.FileMode
 	NoVerifyUpload bool
 
 	// If set, we will panic when an internal server error happens. This
@@ -39,6 +37,13 @@ type Options struct {
 	BlobMetricFunc BlobMetricFunc
 	QuotaManager   *quota.Manager
 	FsyncWarning   *sync.Once
+
+	// If set makes files group accessible
+	GroupAccessible bool
+
+	// Defaults dir and file mode
+	dirMode  os.FileMode
+	fileMode os.FileMode
 }
 
 // DefaultDirMode is the file mode used for directory creation if not
@@ -49,6 +54,14 @@ const DefaultDirMode os.FileMode = 0700
 // overridden in the Options
 const DefaultFileMode os.FileMode = 0600
 
+// GroupAccessibleDirMode is the file mode used for directory creation when
+// group access is enabled
+const GroupAccessibleDirMode os.FileMode = 0770
+
+// GroupAccessibleFileMode is the file mode used for file creation when
+// group access is enabled
+const GroupAccessibleFileMode os.FileMode = 0660
+
 // New creates a new Handler for a single Restic backup repo.
 // path is the full filesystem path to this repo directory.
 // opt is a set of options.
@@ -56,12 +69,15 @@ func New(path string, opt Options) (*Handler, error) {
 	if path == "" {
 		return nil, fmt.Errorf("path is required")
 	}
-	if opt.DirMode == 0 {
-		opt.DirMode = DefaultDirMode
-	}
-	if opt.FileMode == 0 {
-		opt.FileMode = DefaultFileMode
+
+	opt.dirMode = DefaultDirMode
+	opt.fileMode = DefaultFileMode
+
+	if opt.GroupAccessible {
+		opt.dirMode = GroupAccessibleDirMode
+		opt.fileMode = GroupAccessibleFileMode
 	}
+
 	h := Handler{
 		path: path,
 		opt:  opt,
@@ -288,7 +304,7 @@ func (h *Handler) saveConfig(w http.ResponseWriter, r *http.Request) {
 	}
 	cfg := h.getSubPath("config")
 
-	f, err := os.OpenFile(cfg, os.O_CREATE|os.O_WRONLY|os.O_EXCL, h.opt.FileMode)
+	f, err := os.OpenFile(cfg, os.O_CREATE|os.O_WRONLY|os.O_EXCL, h.opt.fileMode)
 	if err != nil && os.IsExist(err) {
 		if h.opt.Debug {
 			log.Print(err)
@@ -554,15 +570,15 @@ func (h *Handler) saveBlob(w http.ResponseWriter, r *http.Request) {
 	}
 
 	tmpFn := filepath.Join(filepath.Dir(path), objectID+".rest-server-temp")
-	tf, err := tempFile(tmpFn, h.opt.FileMode)
+	tf, err := tempFile(tmpFn, h.opt.fileMode)
 	if os.IsNotExist(err) {
 		// the error is caused by a missing directory, create it and retry
-		mkdirErr := os.MkdirAll(filepath.Dir(path), h.opt.DirMode)
+		mkdirErr := os.MkdirAll(filepath.Dir(path), h.opt.dirMode)
 		if mkdirErr != nil {
 			log.Print(mkdirErr)
 		} else {
 			// try again
-			tf, err = tempFile(tmpFn, h.opt.FileMode)
+			tf, err = tempFile(tmpFn, h.opt.fileMode)
 		}
 	}
 	if err != nil {
@@ -759,13 +775,13 @@ func (h *Handler) createRepo(w http.ResponseWriter, r *http.Request) {
 
 	log.Printf("Creating repository directories in %s\n", h.path)
 
-	if err := os.MkdirAll(h.path, h.opt.DirMode); err != nil {
+	if err := os.MkdirAll(h.path, h.opt.dirMode); err != nil {
 		h.internalServerError(w, err)
 		return
 	}
 
 	for _, d := range ObjectTypes {
-		if err := os.Mkdir(filepath.Join(h.path, d), h.opt.DirMode); err != nil && !os.IsExist(err) {
+		if err := os.Mkdir(filepath.Join(h.path, d), h.opt.dirMode); err != nil && !os.IsExist(err) {
 			h.internalServerError(w, err)
 			return
 		}
@@ -773,7 +789,7 @@ func (h *Handler) createRepo(w http.ResponseWriter, r *http.Request) {
 
 	for i := 0; i < 256; i++ {
 		dirPath := filepath.Join(h.path, "data", fmt.Sprintf("%02x", i))
-		if err := os.Mkdir(dirPath, h.opt.DirMode); err != nil && !os.IsExist(err) {
+		if err := os.Mkdir(dirPath, h.opt.dirMode); err != nil && !os.IsExist(err) {
 			h.internalServerError(w, err)
 			return
 		}