rsyncd: descend into subdirectory (if specified)

fixes #40

Author: stapelberg

integration/receiver/receiver_daemon_test.go

@@ -54,6 +54,98 @@ func TestDaemonReceiverSync(t *testing.T) {
 	}
 }
 
+// like TestDaemonReceiverSync, but specifying a destination path that is a subdirectory
+// within the module.
+func TestDaemonReceiverSyncSubdir(t *testing.T) {
+	t.Parallel()
+
+	rsyncBin := rsynctest.TridgeOrGTFO(t, "TODO: reason")
+
+	tmp := t.TempDir()
+	source := filepath.Join(tmp, "source")
+	dest := filepath.Join(tmp, "dest")
+	destLarge := filepath.Join(dest, "destsubdir", "large-data-file")
+
+	headPattern := []byte{0x11}
+	bodyPattern := []byte{0xbb}
+	endPattern := []byte{0xee}
+	rsynctest.WriteLargeDataFile(t, source, headPattern, bodyPattern, endPattern)
+
+	// start a server which receives data
+	srv := rsynctest.New(t, rsynctest.WritableInteropModule(dest))
+
+	rsync := exec.Command(rsyncBin,
+		//		"--debug=all4",
+		"--archive",
+		// A verbosity level of 3 is enough, any higher than that and rsync
+		// will start listing individual chunk matches.
+		"-v", "-v", "-v", // "-v",
+		"--port="+srv.Port,
+		source+"/", // copy contents of source
+		"rsync://localhost/interop/destsubdir/")
+	rsync.Env = append(os.Environ(),
+		// Ensure rsync does not localize decimal separators and fractional
+		// points based on the current locale:
+		"LANG=C.UTF-8")
+	rsync.Stdout = testlogger.New(t)
+	rsync.Stderr = testlogger.New(t)
+	if err := rsync.Run(); err != nil {
+		t.Fatalf("%v: %v", rsync.Args, err)
+	}
+
+	if err := rsynctest.DataFileMatches(destLarge, headPattern, bodyPattern, endPattern); err != nil {
+		t.Fatal(err)
+	}
+}
+
+// like TestDaemonReceiverSync, but specifying a destination path that is a subdirectory
+// within the module.
+func TestDaemonReceiverSyncSubdirTraversal(t *testing.T) {
+	t.Parallel()
+
+	rsyncBin := rsynctest.TridgeOrGTFO(t, "TODO: reason")
+
+	tmp := t.TempDir()
+	source := filepath.Join(tmp, "source")
+	dest := filepath.Join(tmp, "dest")
+	destLarge := filepath.Join(dest, "destsubdir", "large-data-file")
+
+	headPattern := []byte{0x11}
+	bodyPattern := []byte{0xbb}
+	endPattern := []byte{0xee}
+	rsynctest.WriteLargeDataFile(t, source, headPattern, bodyPattern, endPattern)
+
+	// start a server which receives data
+	srv := rsynctest.New(t, rsynctest.WritableInteropModule(dest))
+
+	rsync := exec.Command(rsyncBin,
+		//		"--debug=all4",
+		"--archive",
+		// A verbosity level of 3 is enough, any higher than that and rsync
+		// will start listing individual chunk matches.
+		"-v", "-v", "-v", // "-v",
+		"--port="+srv.Port,
+		source+"/", // copy contents of source
+		"rsync://localhost/interop/../")
+	rsync.Env = append(os.Environ(),
+		// Ensure rsync does not localize decimal separators and fractional
+		// points based on the current locale:
+		"LANG=C.UTF-8")
+	var buf bytes.Buffer
+	rsync.Stdout = &buf
+	rsync.Stderr = &buf
+	if err := rsync.Run(); err != nil {
+		if strings.Contains(buf.String(), "path escapes from parent") {
+			return
+		}
+		t.Fatalf("%v: %v", rsync.Args, err)
+	}
+
+	if err := rsynctest.DataFileMatches(destLarge, headPattern, bodyPattern, endPattern); err != nil {
+		t.Fatal(err)
+	}
+}
+
 func TestDaemonReceiverDelete(t *testing.T) {
 	t.Parallel()
 

rsyncd/rsyncd.go

@@ -12,6 +12,7 @@ import (
 	"io"
 	"net"
 	"os"
+	"path/filepath"
 	"strings"
 	"time"
 
@@ -392,7 +393,9 @@ func (s *Server) handleConn(ctx context.Context, conn *Conn, module *Module, pc
 
 // handleConnReceiver is equivalent to rsync/main.c:do_server_recv
 func (s *Server) handleConnReceiver(module *Module, crd *rsyncwire.CountingReader, cwr *rsyncwire.CountingWriter, paths []string, opts *rsyncopts.Options, negotiate bool, c *rsyncwire.Conn, sessionChecksumSeed int32) (err error) {
-	if module == nil {
+	var destPath string
+	implicitModule := module == nil
+	if implicitModule {
 		if len(paths) != 1 {
 			return fmt.Errorf("precisely one destination path required, got %q", paths)
 		}
@@ -401,9 +404,10 @@ func (s *Server) handleConnReceiver(module *Module, crd *rsyncwire.CountingReade
 			Path:     paths[0],
 			Writable: true,
 		}
+		destPath = module.Path
 	}
 	if opts.Verbose() {
-		s.logger.Printf("handleConnReceiver(module=%+v)", module)
+		s.logger.Printf("handleConnReceiver(module=%+v, destPath=%q)", module, destPath)
 	}
 
 	if !module.Writable {
@@ -442,6 +446,34 @@ func (s *Server) handleConnReceiver(module *Module, crd *rsyncwire.CountingReade
 	}
 	defer rt.DestRoot.Close()
 
+	if !implicitModule {
+		if len(paths) > 1 {
+			return fmt.Errorf("module is available, and at most one destination path is allowed, got %q", paths)
+		}
+		// Descend into subdirectory (if requested),
+		// using the os.OpenRoot traversal-safe API.
+		if len(paths) == 1 && paths[0] != "/" {
+			subdir := strings.TrimPrefix(paths[0], "/")
+			subRoot, err := rt.DestRoot.OpenRoot(subdir)
+			if err != nil {
+				if os.IsNotExist(err) {
+					if err := rt.DestRoot.Mkdir(subdir, 0755); err != nil {
+						return fmt.Errorf("Mkdir(%s): %v", subdir, err)
+					}
+					subRoot, err = rt.DestRoot.OpenRoot(subdir)
+				}
+				if err != nil {
+					return fmt.Errorf("OpenRoot(%s): %v", subdir, err)
+				}
+			}
+			rt.Dest = filepath.Join(rt.Dest, subRoot.Name())
+			rt.DestRoot = subRoot
+			if opts.Verbose() {
+				s.logger.Printf("opened subdirectory %q", rt.Dest)
+			}
+		}
+	}
+
 	if opts.PreserveHardLinks() {
 		return fmt.Errorf("support for hard links not yet implemented")
 	}