CVE-2024-52522

@@ -0,0 +1,16 @@
+//go:build windows || plan9 || js || linux
+
+package local
+
+import "os"
+
+const haveLChmod = false
+
+// lChmod changes the mode of the named file to mode. If the file is a symbolic
+// link, it changes the link, not the target. If there is an error,
+// it will be of type *PathError.
+func lChmod(name string, mode os.FileMode) error {
+	// Can't do this safely on this OS - chmoding a symlink always
+	// changes the destination.
+	return nil
+}

@@ -0,0 +1,41 @@
+//go:build !windows && !plan9 && !js && !linux
+
+package local
+
+import (
+	"os"
+	"syscall"
+
+	"golang.org/x/sys/unix"
+)
+
+const haveLChmod = true
+
+// syscallMode returns the syscall-specific mode bits from Go's portable mode bits.
+//
+// Borrowed from the syscall source since it isn't public.
+func syscallMode(i os.FileMode) (o uint32) {
+	o |= uint32(i.Perm())
+	if i&os.ModeSetuid != 0 {
+		o |= syscall.S_ISUID
+	}
+	if i&os.ModeSetgid != 0 {
+		o |= syscall.S_ISGID
+	}
+	if i&os.ModeSticky != 0 {
+		o |= syscall.S_ISVTX
+	}
+	return o
+}
+
+// lChmod changes the mode of the named file to mode. If the file is a symbolic
+// link, it changes the link, not the target. If there is an error,
+// it will be of type *PathError.
+func lChmod(name string, mode os.FileMode) error {
+	// NB linux does not support AT_SYMLINK_NOFOLLOW as a parameter to fchmodat
+	// and returns ENOTSUP if you try, so we don't support this on linux
+	if e := unix.Fchmodat(unix.AT_FDCWD, name, syscallMode(mode), unix.AT_SYMLINK_NOFOLLOW); e != nil {
+		return &os.PathError{Op: "lChmod", Path: name, Err: e}
+	}
+	return nil
+}

@@ -1,4 +1,4 @@
-//go:build windows || plan9 || js
+//go:build plan9 || js
 
 package local
 

@@ -0,0 +1,19 @@
+//go:build windows
+
+package local
+
+import (
+	"time"
+)
+
+const haveLChtimes = true
+
+// lChtimes changes the access and modification times of the named
+// link, similar to the Unix utime() or utimes() functions.
+//
+// The underlying filesystem may truncate or round the values to a
+// less precise time unit.
+// If there is an error, it will be of type *PathError.
+func lChtimes(name string, atime time.Time, mtime time.Time) error {
+	return setTimes(name, atime, mtime, time.Time{}, true)
+}

@@ -268,22 +268,66 @@ func TestMetadata(t *testing.T) {
 	r := fstest.NewRun(t)
 	const filePath = "metafile.txt"
 	when := time.Now()
-	const dayLength = len("2001-01-01")
-	whenRFC := when.Format(time.RFC3339Nano)
 	r.WriteFile(filePath, "metadata file contents", when)
 	f := r.Flocal.(*Fs)
 
+	// Set fs into "-l" / "--links" mode
+	f.opt.TranslateSymlinks = true
+
+	// Write a symlink to the file
+	symlinkPath := "metafile-link.txt"
+	osSymlinkPath := filepath.Join(f.root, symlinkPath)
+	symlinkPath += linkSuffix
+	require.NoError(t, os.Symlink(filePath, osSymlinkPath))
+	symlinkModTime := fstest.Time("2002-02-03T04:05:10.123123123Z")
+	require.NoError(t, lChtimes(osSymlinkPath, symlinkModTime, symlinkModTime))
+
 	// Get the object
 	obj, err := f.NewObject(ctx, filePath)
 	require.NoError(t, err)
 	o := obj.(*Object)
 
+	// Get the symlink object
+	symlinkObj, err := f.NewObject(ctx, symlinkPath)
+	require.NoError(t, err)
+	symlinkO := symlinkObj.(*Object)
+
+	// Record metadata for o
+	oMeta, err := o.Metadata(ctx)
+	require.NoError(t, err)
+
+	// Test symlink first to check it doesn't mess up file
+	t.Run("Symlink", func(t *testing.T) {
+		testMetadata(t, r, symlinkO, symlinkModTime)
+	})
+
+	// Read it again
+	oMetaNew, err := o.Metadata(ctx)
+	require.NoError(t, err)
+
+	// Check that operating on the symlink didn't change the file it was pointing to
+	// See: https://github.com/rclone/rclone/security/advisories/GHSA-hrxh-9w67-g4cv
+	assert.Equal(t, oMeta, oMetaNew, "metadata setting on symlink messed up file")
+
+	// Now run the same tests on the file
+	t.Run("File", func(t *testing.T) {
+		testMetadata(t, r, o, when)
+	})
+}
+
+func testMetadata(t *testing.T, r *fstest.Run, o *Object, when time.Time) {
+	ctx := context.Background()
+	whenRFC := when.Format(time.RFC3339Nano)
+	const dayLength = len("2001-01-01")
+
+	f := r.Flocal.(*Fs)
 	features := f.Features()
 
-	var hasXID, hasAtime, hasBtime bool
+	var hasXID, hasAtime, hasBtime, canSetXattrOnLinks bool
 	switch runtime.GOOS {
 	case "darwin", "freebsd", "netbsd", "linux":
 		hasXID, hasAtime, hasBtime = true, true, true
+		canSetXattrOnLinks = runtime.GOOS != "linux"
 	case "openbsd", "solaris":
 		hasXID, hasAtime = true, true
 	case "windows":
@@ -306,6 +350,10 @@ func TestMetadata(t *testing.T) {
 		require.NoError(t, err)
 		assert.Nil(t, m)
 
+		if !canSetXattrOnLinks && o.translatedLink {
+			t.Skip("Skip remainder of test as can't set xattr on symlinks on this OS")
+		}
+
 		inM := fs.Metadata{
 			"potato":  "chips",
 			"cabbage": "soup",
@@ -320,18 +368,21 @@ func TestMetadata(t *testing.T) {
 	})
 
 	checkTime := func(m fs.Metadata, key string, when time.Time) {
+		t.Helper()
 		mt, ok := o.parseMetadataTime(m, key)
 		assert.True(t, ok)
 		dt := mt.Sub(when)
 		precision := time.Second
-		assert.True(t, dt >= -precision && dt <= precision, fmt.Sprintf("%s: dt %v outside +/- precision %v", key, dt, precision))
+		assert.True(t, dt >= -precision && dt <= precision, fmt.Sprintf("%s: dt %v outside +/- precision %v want %v got %v", key, dt, precision, mt, when))
 	}
 
 	checkInt := func(m fs.Metadata, key string, base int) int {
+		t.Helper()
 		value, ok := o.parseMetadataInt(m, key, base)
 		assert.True(t, ok)
 		return value
 	}
+
 	t.Run("Read", func(t *testing.T) {
 		m, err := o.Metadata(ctx)
 		require.NoError(t, err)
@@ -341,13 +392,12 @@ func TestMetadata(t *testing.T) {
 		checkInt(m, "mode", 8)
 		checkTime(m, "mtime", when)
 
-		assert.Equal(t, len(whenRFC), len(m["mtime"]))
 		assert.Equal(t, whenRFC[:dayLength], m["mtime"][:dayLength])
 
-		if hasAtime {
+		if hasAtime && !o.translatedLink { // symlinks generally don't record atime
 			checkTime(m, "atime", when)
 		}
-		if hasBtime {
+		if hasBtime && !o.translatedLink { // symlinks generally don't record btime
 			checkTime(m, "btime", when)
 		}
 		if hasXID {
@@ -371,6 +421,10 @@ func TestMetadata(t *testing.T) {
 			"mode":   "0767",
 			"potato": "wedges",
 		}
+		if !canSetXattrOnLinks && o.translatedLink {
+			// Don't change xattr if not supported on symlinks
+			delete(newM, "potato")
+		}
 		err := o.writeMetadata(newM)
 		require.NoError(t, err)
 
@@ -380,7 +434,11 @@ func TestMetadata(t *testing.T) {
 
 		mode := checkInt(m, "mode", 8)
 		if runtime.GOOS != "windows" {
-			assert.Equal(t, 0767, mode&0777, fmt.Sprintf("mode wrong - expecting 0767 got 0%o", mode&0777))
+			expectedMode := 0767
+			if o.translatedLink && runtime.GOOS == "linux" {
+				expectedMode = 0777 // perms of symlinks always read as 0777 on linux
+			}
+			assert.Equal(t, expectedMode, mode&0777, fmt.Sprintf("mode wrong - expecting 0%o got 0%o", expectedMode, mode&0777))
 		}
 
 		checkTime(m, "mtime", newMtime)
@@ -390,7 +448,7 @@ func TestMetadata(t *testing.T) {
 		if haveSetBTime {
 			checkTime(m, "btime", newBtime)
 		}
-		if xattrSupported {
+		if xattrSupported && (canSetXattrOnLinks || !o.translatedLink) {
 			assert.Equal(t, "wedges", m["potato"])
 		}
 	})

@@ -105,7 +105,11 @@ func (o *Object) writeMetadataToFile(m fs.Metadata) (outErr error) {
 	}
 	if haveSetBTime {
 		if btimeOK {
-			err = setBTime(o.path, btime)
+			if o.translatedLink {
+				err = lsetBTime(o.path, btime)
+			} else {
+				err = setBTime(o.path, btime)
+			}
 			if err != nil {
 				outErr = fmt.Errorf("failed to set birth (creation) time: %w", err)
 			}
@@ -121,7 +125,11 @@ func (o *Object) writeMetadataToFile(m fs.Metadata) (outErr error) {
 		if runtime.GOOS == "windows" || runtime.GOOS == "plan9" {
 			fs.Debugf(o, "Ignoring request to set ownership %o.%o on this OS", gid, uid)
 		} else {
-			err = os.Chown(o.path, uid, gid)
+			if o.translatedLink {
+				err = os.Lchown(o.path, uid, gid)
+			} else {
+				err = os.Chown(o.path, uid, gid)
+			}
 			if err != nil {
 				outErr = fmt.Errorf("failed to change ownership: %w", err)
 			}
@@ -132,7 +140,16 @@ func (o *Object) writeMetadataToFile(m fs.Metadata) (outErr error) {
 		if mode >= 0 {
 			umode := uint(mode)
 			if umode <= math.MaxUint32 {
-				err = os.Chmod(o.path, os.FileMode(umode))
+				if o.translatedLink {
+					if haveLChmod {
+						err = lChmod(o.path, os.FileMode(umode))
+					} else {
+						fs.Debugf(o, "Unable to set mode %v on a symlink on this OS", os.FileMode(umode))
+						err = nil
+					}
+				} else {
+					err = os.Chmod(o.path, os.FileMode(umode))
+				}
 				if err != nil {
 					outErr = fmt.Errorf("failed to change permissions: %w", err)
 				}

@@ -13,3 +13,9 @@ func setBTime(name string, btime time.Time) error {
 	// Does nothing
 	return nil
 }
+
+// lsetBTime changes the birth time of the link passed in
+func lsetBTime(name string, btime time.Time) error {
+	// Does nothing
+	return nil
+}

@@ -9,15 +9,20 @@ import (
 
 const haveSetBTime = true
 
-// setBTime sets the birth time of the file passed in
-func setBTime(name string, btime time.Time) (err error) {
+// setTimes sets any of atime, mtime or btime
+// if link is set it sets a link rather than the target
+func setTimes(name string, atime, mtime, btime time.Time, link bool) (err error) {
 	pathp, err := syscall.UTF16PtrFromString(name)
 	if err != nil {
 		return err
 	}
+	fileFlag := uint32(syscall.FILE_FLAG_BACKUP_SEMANTICS)
+	if link {
+		fileFlag |= syscall.FILE_FLAG_OPEN_REPARSE_POINT
+	}
 	h, err := syscall.CreateFile(pathp,
 		syscall.FILE_WRITE_ATTRIBUTES, syscall.FILE_SHARE_WRITE, nil,
-		syscall.OPEN_EXISTING, syscall.FILE_FLAG_BACKUP_SEMANTICS, 0)
+		syscall.OPEN_EXISTING, fileFlag, 0)
 	if err != nil {
 		return err
 	}
@@ -27,6 +32,28 @@ func setBTime(name string, btime time.Time) (err error) {
 			err = closeErr
 		}
 	}()
-	bFileTime := syscall.NsecToFiletime(btime.UnixNano())
-	return syscall.SetFileTime(h, &bFileTime, nil, nil)
+	var patime, pmtime, pbtime *syscall.Filetime
+	if !atime.IsZero() {
+		t := syscall.NsecToFiletime(atime.UnixNano())
+		patime = &t
+	}
+	if !mtime.IsZero() {
+		t := syscall.NsecToFiletime(mtime.UnixNano())
+		pmtime = &t
+	}
+	if !btime.IsZero() {
+		t := syscall.NsecToFiletime(btime.UnixNano())
+		pbtime = &t
+	}
+	return syscall.SetFileTime(h, pbtime, patime, pmtime)
+}
+
+// setBTime sets the birth time of the file passed in
+func setBTime(name string, btime time.Time) (err error) {
+	return setTimes(name, time.Time{}, time.Time{}, btime, false)
+}
+
+// lsetBTime changes the birth time of the link passed in
+func lsetBTime(name string, btime time.Time) error {
+	return setTimes(name, time.Time{}, time.Time{}, btime, true)
 }