Merge pull request #169 from rhatdan/lgetfile

Add LFileLabel and LSetFileLabel

Author: rhatdan

go-selinux/selinux.go

@@ -61,16 +61,30 @@ func ClassIndex(class string) (int, error) {
 	return classIndex(class)
 }
 
-// SetFileLabel sets the SELinux label for this path or returns an error.
+// SetFileLabel sets the SELinux label for this path, following symlinks,
+// or returns an error.
 func SetFileLabel(fpath string, label string) error {
 	return setFileLabel(fpath, label)
 }
 
-// FileLabel returns the SELinux label for this path or returns an error.
+// LsetFileLabel sets the SELinux label for this path, not following symlinks,
+// or returns an error.
+func LsetFileLabel(fpath string, label string) error {
+	return lSetFileLabel(fpath, label)
+}
+
+// FileLabel returns the SELinux label for this path, following symlinks,
+// or returns an error.
 func FileLabel(fpath string) (string, error) {
 	return fileLabel(fpath)
 }
 
+// LfileLabel returns the SELinux label for this path, not following symlinks,
+// or returns an error.
+func LfileLabel(fpath string) (string, error) {
+	return lFileLabel(fpath)
+}
+
 // SetFSCreateLabel tells the kernel what label to use for all file system objects
 // created by this task.
 // Set the label to an empty string to return to the default label. Calls to SetFSCreateLabel

go-selinux/selinux_linux.go

@@ -316,8 +316,9 @@ func classIndex(class string) (int, error) {
 	return index, nil
 }
 
-// setFileLabel sets the SELinux label for this path or returns an error.
-func setFileLabel(fpath string, label string) error {
+// lSetFileLabel sets the SELinux label for this path, not following symlinks,
+// or returns an error.
+func lSetFileLabel(fpath string, label string) error {
 	if fpath == "" {
 		return ErrEmptyPath
 	}
@@ -334,12 +335,50 @@ func setFileLabel(fpath string, label string) error {
 	return nil
 }
 
-// fileLabel returns the SELinux label for this path or returns an error.
+// setFileLabel sets the SELinux label for this path, following symlinks,
+// or returns an error.
+func setFileLabel(fpath string, label string) error {
+	if fpath == "" {
+		return ErrEmptyPath
+	}
+	for {
+		err := unix.Setxattr(fpath, xattrNameSelinux, []byte(label), 0)
+		if err == nil {
+			break
+		}
+		if err != unix.EINTR { //nolint:errorlint // unix errors are bare
+			return &os.PathError{Op: "setxattr", Path: fpath, Err: err}
+		}
+	}
+
+	return nil
+}
+
+// fileLabel returns the SELinux label for this path, following symlinks,
+// or returns an error.
 func fileLabel(fpath string) (string, error) {
 	if fpath == "" {
 		return "", ErrEmptyPath
 	}
 
+	label, err := getxattr(fpath, xattrNameSelinux)
+	if err != nil {
+		return "", &os.PathError{Op: "getxattr", Path: fpath, Err: err}
+	}
+	// Trim the NUL byte at the end of the byte buffer, if present.
+	if len(label) > 0 && label[len(label)-1] == '\x00' {
+		label = label[:len(label)-1]
+	}
+	return string(label), nil
+}
+
+// lFileLabel returns the SELinux label for this path, not following symlinks,
+// or returns an error.
+func lFileLabel(fpath string) (string, error) {
+	if fpath == "" {
+		return "", ErrEmptyPath
+	}
+
 	label, err := lgetxattr(fpath, xattrNameSelinux)
 	if err != nil {
 		return "", &os.PathError{Op: "lgetxattr", Path: fpath, Err: err}

go-selinux/selinux_stub.go

@@ -17,10 +17,18 @@ func setFileLabel(fpath string, label string) error {
 	return nil
 }
 
+func lSetFileLabel(fpath string, label string) error {
+	return nil
+}
+
 func fileLabel(fpath string) (string, error) {
 	return "", nil
 }
 
+func lFileLabel(fpath string) (string, error) {
+	return "", nil
+}
+
 func setFSCreateLabel(label string) error {
 	return nil
 }

go-selinux/xattrs_linux.go

@@ -36,3 +36,36 @@ func doLgetxattr(path, attr string, dest []byte) (int, error) {
 		}
 	}
 }
+
+// getxattr returns a []byte slice containing the value of
+// an extended attribute attr set for path.
+func getxattr(path, attr string) ([]byte, error) {
+	// Start with a 128 length byte array
+	dest := make([]byte, 128)
+	sz, errno := dogetxattr(path, attr, dest)
+	for errno == unix.ERANGE { //nolint:errorlint // unix errors are bare
+		// Buffer too small, use zero-sized buffer to get the actual size
+		sz, errno = dogetxattr(path, attr, []byte{})
+		if errno != nil {
+			return nil, errno
+		}
+
+		dest = make([]byte, sz)
+		sz, errno = dogetxattr(path, attr, dest)
+	}
+	if errno != nil {
+		return nil, errno
+	}
+
+	return dest[:sz], nil
+}
+
+// dogetxattr is a wrapper that retries on EINTR
+func dogetxattr(path, attr string, dest []byte) (int, error) {
+	for {
+		sz, err := unix.Getxattr(path, attr, dest)
+		if err != unix.EINTR { //nolint:errorlint // unix errors are bare
+			return sz, err
+		}
+	}
+}